JP7830864B2 - Pressure-responsive particles, cartridges, printing apparatus, printing method, printed material, printing sheet, and printing sheet manufacturing method. - Google Patents

Description

This invention relates to pressure-responsive particles, cartridges, a printing apparatus, a method for manufacturing printed materials, printed materials, a sheet for manufacturing printed materials, and a method for manufacturing a sheet for manufacturing printed materials.

Patent Document 1 describes a water-dispersible adhesive composition containing two types of acrylic polymers in an aqueous solvent.

Patent Document 2 describes an adhesive material that satisfies the formula "20°C ≤ T(1MPa) - T(10MPa)" (where T(1MPa) represents the temperature at which the viscosity becomes ^10⁴ Pa·s at an applied pressure of 1 MPa, and T(10MPa) represents the temperature at which the viscosity becomes ^10⁴ Pa·s at an applied pressure of 10 MPa).

Patent Document 3 describes a pressure-fixing toner comprising a core portion having a sea-island structure composed of a sea portion containing styrene resin and an island portion containing (meth)acrylic acid ester resin, the island portion having a major axis of 200 nm to 500 nm, and a shell layer covering the core portion and containing a resin with a glass transition temperature of 50°C or higher.

Patent Document 4 describes a water-dispersible adhesive composition comprising an acrylic polymer (A) which is a polymer of monomer raw material (A) and an acrylic polymer (B) which is a polymer of monomer raw material (B), wherein the glass transition temperature of acrylic polymer (B) is 0°C or higher, the weight-average molecular weight of acrylic polymer (B) is greater than 0.3 × ^10⁴ and 5 × ^10⁴ or less, the weight-average molecular weight of acrylic polymer (A) is 40 × ^10⁴ or higher, the difference between the glass transition temperature of acrylic polymer (B) and the glass transition temperature of acrylic polymer (A) is 70°C or higher, and the monomer raw material (B) contains carboxyl group-containing monomers in a proportion of 3% by weight or more and 20% by weight or less.

Patent Document 5 describes a pressure-sensitive postcard paper in which the adhesive layer contains an acrylic acid/alkyl methacrylate copolymer.

Patent Document 6 describes pressure-responsive particles comprising a styrene-based resin containing styrene and other vinyl monomers as polymerization components, and a (meth)acrylic acid ester-based resin containing at least two types of (meth)acrylic acid esters as polymerization components, wherein the mass ratio of (meth)acrylic acid esters to the total polymerization components is 90% by mass or more; and silica particles having an average primary particle diameter of 50 nm to 300 nm, having at least two glass transition temperatures, and the difference between the lowest and highest glass transition temperatures being 30°C or more.

Patent Document 7 describes a toner for developing electrostatic images, to which at least a binder resin, a release agent, and a charge control agent are added, wherein the toner particles have a circularity of 0.93 to 0.98, the number proportion of ultrafine particles 2.0 μm or less is 10% or less, and at least two types of external additives are added, with at least one of the external additives having a primary particle diameter of 40 nm to 500 nm.

Patent Document 8 describes a toner containing a binder resin, comprising toner particles and inorganic fine particles, wherein the average circularity of the toner particles is 0.980 or less, and when inorganic fine particles present on the toner particles that are 80 nm or larger and have a primary particle shape coefficient SF-2 of 116 or less are defined as the inorganic fine particle group, the content of the inorganic fine particle group is 0.5 parts by mass or more and 30.0 parts by mass or less per 100 parts by mass of toner particles, and when the particle size at which the cumulative value from the smallest particle side in the volume-based particle size distribution of the inorganic fine particle group on the toner particles is defined as D16, the particle size at which the cumulative value is 50 volume%, and the particle size at which the cumulative value is 84 volume%, D50 is 130 nm or more and 700 nm or less, and the particle size distribution index expressed as D84/D16 is 1.70 or more and 5.00 or less.

Japanese Patent Publication No. 2012-188512 Japanese Patent Publication No. 2018-002889 Japanese Patent Publication No. 2018-163198 Patent No. 646872 Japanese Patent Publication No. 2007-229993 Japanese Patent Publication No. 2021-018423 Japanese Patent Publication No. 2006-184748 Japanese Patent Publication No. 2019-101280

This disclosure aims to provide pressure-responsive particles comprising pressure-responsive mother particles containing a styrene-based resin and a (meth)acrylic acid ester-based resin, and silica particles, which exhibit superior adhesion to the surfaces of recording media in a peelable manner compared to pressure-responsive particles where the ratio of surface coverage Cs1 to surface coverage Cs2 by silica particles before and after stress application (Cs2/Cs1) is less than 0.4 or greater than 0.8.

The following embodiments are included as specific means for solving the aforementioned problem.

<1> A pressure-responsive mother particle containing a styrene-based resin containing styrene and other vinyl monomers as polymerization components, and a (meth)acrylic acid ester-based resin containing at least two types of (meth)acrylic acid esters as polymerization components, wherein the mass ratio of (meth)acrylic acid esters to the total polymerization components is 90% by mass or more,
Contains silica particles,
It has at least two glass transition temperatures, and the difference between the lowest and highest glass transition temperatures is 30°C or more.
A pressure-responsive particle in which the ratio of the surface coverage rate Cs1 of silica particles before stress is applied to the surface coverage rate Cs2 of silica particles after the application of the first stress described below satisfies the relationship 0.4 ≤ Cs2/Cs1 ≤ 0.8.
First stress test: Under a temperature of 20°C and a relative humidity of 50%, 10 g of pressure-responsive particles and 90 g of resin-coated ferrite particles are placed in a 0.5 L rotary V-type mixer and operated at a rotation speed of 40 revolutions per minute for 20 minutes.
<2> The pressure-responsive particle according to <1>, wherein the ratio of the surface coverage Cs1 to the surface coverage Cs2 satisfies the relationship 0.5 ≤ Cs2/Cs1 ≤ 0.7.
<3> The pressure-responsive particle according to <1> or <2>, wherein the surface coverage Cs1 is 40% or more and 80% or less, and the surface coverage Cs2 is 35% or more and 60% or less.
<4> The pressure-responsive particle according to <3>, wherein the surface coverage Cs1 is 50% or more and 80% or less, and the surface coverage Cs2 is 35% or more and 50% or less.
<5> The pressure-responsive particle according to any one of <1> to <4>, wherein the average circularity of the pressure-responsive matrix particle is 0.955 or more and 0.975 or less.
<6> The pressure-responsive particle according to <5>, wherein the average circularity of the pressure-responsive matrix particle is 0.955 or more and 0.970 or less.
<7> A pressure-responsive particle according to any one of <1> to <6>, wherein the ratio of the surface coverage rate Cs2 to the surface coverage rate Cs3 of silica particles after the second stress described below is 0.4 ≤ Cs2/Cs3 ≤ 0.9.
Second stress test: Under a temperature of 20°C and a relative humidity of 50%, 10 g of pressure-responsive particles are placed in a 0.5 L rotary V-type mixer and operated at a rotation speed of 40 revolutions per minute for 20 minutes.
<8> The pressure-responsive particle according to <7>, wherein the ratio of the surface coverage Cs2 to the surface coverage Cs3 satisfies the relationship 0.4 ≤ Cs2/Cs3 ≤ 0.8.
<9> The pressure-responsive particle according to <7> or <8>, wherein the surface coverage Cs3 is 40% or more and 60% or less.
<10> The pressure-responsive particle according to any one of <1> to <9>, wherein the concentration of Al element on the surface of the pressure-responsive particle is 0.1 atomic% or more and 1.5 atomic% or less.
<11> The pressure-responsive particle according to <10>, wherein the concentration of Al element on the surface of the pressure-responsive particle is 0.3 atomic% or more and 0.9 atomic% or less.
<12> The pressure-responsive particle according to any one of <1> to <11>, wherein the particle size distribution of the silica particles has peaks in the range of particle size 100 nm or less and in the range of particle size greater than 100 nm.
<13> A pressure-responsive particle according to any one of <1> to <12>, wherein the ratio of the mass Ms1 of silica particles with a particle size of 100 nm or less, determined from the particle size distribution of the silica particles, to the mass Ms2 of silica particles with a particle size greater than 100 nm, determined from the particle size distribution of the silica particles, satisfies the relationship 0.5 ≤ Ms2/Ms1 ≤ 1.3.
<14> The pressure-responsive particle according to any one of <1> to <13>, wherein the pressure-responsive mother particle comprises a sea phase containing the styrene resin and an island phase containing the (meth)acrylic acid ester resin dispersed in the sea phase.
<15> The pressure-responsive particle according to <14>, wherein the average diameter of the island phase is 200 nm or more and 500 nm or less.
<16> The pressure-responsive particle according to any one of <1> to <15>, wherein the pressure-responsive mother particle has a core portion containing the styrene resin and the (meth)acrylic acid ester resin and a shell layer covering the core portion.
<17> The pressure-responsive particle according to <16>, wherein the shell layer contains the styrene resin.

<18> A cartridge containing pressure-responsive particles as described in any one of items <1> to <17>, which is attached to and detached from a printing apparatus.
<19> Arrangement means for accommodating pressure-responsive particles described in any one of <1> to <17> and arranging the pressure-responsive particles on a recording medium,
A crimping means for folding and crimping the recording medium, or for crimping the recording medium and another recording medium on top of each other,
A manufacturing apparatus for printed materials, including those containing printed materials.
<20> The apparatus for manufacturing printed matter according to <19>, further comprising a means for forming a colored image on a recording medium using a colorant.
<21> Arrangement step of arranging pressure-responsive particles on a recording medium using pressure-responsive particles described in any one of <1> to <17>,
A crimping step of folding and crimping the recording medium, or crimping the recording medium and another recording medium together,
A method for manufacturing printed materials that include [the specified material].
<22> The method for manufacturing a printed material according to <21>, further comprising a color image forming step of forming a color image on a recording medium using a colorant.
<23> A printed material in which overlapping recording media are bonded together on opposing surfaces by pressure-responsive particles described in any one of <1> to <17>.
<24> A printed material in which multiple overlapping recording media are bonded together on opposing surfaces by pressure-responsive particles described in any one of <1> to <17>.
<25> Pressure-responsive particles described in any one of items <1> to <17> are used.
A sheet for manufacturing printed materials, comprising a base material and pressure-responsive particles disposed on the base material.
<26> A placement step of placing pressure-responsive particles on a substrate using pressure-responsive particles described in any one of <1> to <17>,
A method for manufacturing sheets for printed materials.

According to the inventions of <1>, <12>, or <13>, pressure-responsive particles are provided that include pressure-responsive mother particles containing a styrene resin and a (meth)acrylic acid ester resin and silica particles, wherein the ratio Cs2/Cs1 of the surface coverage rate Cs1 by silica particles before and after stress application is less than 0.4 or greater than 0.8, and which exhibit superior adhesion to the surfaces of recording media in a peelable manner.
According to the invention described in <2>, pressure-responsive particles are provided that have superior adhesion to the surfaces of recording media in a peelable manner, compared to pressure-responsive particles having a ratio of Cs2/Cs1 of less than 0.5 or greater than 0.7.
According to the invention described in <3>, pressure-responsive particles are provided that have superior adhesion to the surfaces of recording media in a peelable manner, compared to pressure-responsive particles with a surface coverage ratio Cs2 of more than 60%.
According to the invention described in <4>, pressure-responsive particles are provided that have superior adhesion to the surfaces of recording media in a peelable manner, compared to pressure-responsive particles having a surface coverage ratio Cs2 of more than 50%.
According to the invention described in <5>, pressure-responsive particles are provided that have superior adhesion and storage properties compared to pressure-responsive particles in which the average circularity of the pressure-responsive mother particles is less than 0.955 or greater than 0.975.
According to the invention described in <6>, pressure-responsive particles are provided that have superior adhesion and storage properties compared to pressure-responsive particles in which the average circularity of the pressure-responsive mother particles is less than 0.955 or greater than 0.970.
According to the invention described in <7>, pressure-responsive particles are provided that have superior adhesion and storage properties compared to pressure-responsive particles having a Cs2/Cs3 ratio of less than 0.4 or greater than 0.9.
According to the invention described in <8>, pressure-responsive particles are provided that have superior adhesion and storage properties compared to pressure-responsive particles having a Cs2/Cs3 ratio of less than 0.4 or greater than 0.8.
According to the invention described in <9>, pressure-responsive particles are provided that have superior adhesion and storage properties compared to pressure-responsive particles having a surface coverage ratio Cs3 of less than 40% or more than 60%.
According to the invention of <10>, pressure-responsive particles are provided that have superior adhesion to the surfaces of recording media, allowing them to be peeled and bonded together, compared to pressure-responsive particles in which the Al element concentration on the surface layer of the pressure-responsive particles is less than 0.1 atomic%.
According to the invention described in <11>, pressure-responsive particles are provided that have superior adhesion to the surfaces of recording media, allowing them to be peeled and bonded together, compared to pressure-responsive particles in which the Al element concentration on the surface layer of the pressure-responsive particles is less than 0.3 atomic%.
According to the invention of <14>, pressure-responsive particles with superior adhesive properties that allow the surfaces of a recording medium to be peelably bonded together are provided, compared to the case where the sea-island structure is not present.
According to the invention described in <15>, pressure-responsive particles with superior adhesion that allow the surfaces of a recording medium to be peelably bonded together are provided, compared to the case where the average diameter of the island phase is greater than 500 nm.
According to the invention described in <16>, pressure-responsive particles with excellent adhesive properties that allow the surfaces of a recording medium to be peelably bonded together are provided, compared to a core-shell structure in which the core portion contains only a styrene-based resin or only a (meth)acrylic acid ester-based resin.
According to the invention of <17>, pressure-responsive particles with excellent adhesive properties that allow the surfaces of the recording medium to adhere to each other in a peelable manner are provided, compared to the case in which the shell layer does not contain a styrene-based resin but contains a resin other than that.

According to the invention of <18>, a cartridge is provided containing pressure-responsive particles comprising pressure-responsive mother particles containing a styrene resin and a (meth)acrylic acid ester resin and silica particles, wherein the ratio Cs2/Cs1 of the surface coverage rate Cs1 by silica particles before and after stress application is less than 0.4 or greater than 0.8, and the pressure-responsive particles have superior adhesion to the surfaces of a recording medium in a peelable manner.
According to the invention of <19> or <20>, a printing apparatus is provided that applies pressure-responsive particles comprising pressure-responsive mother particles containing a styrene resin and a (meth)acrylic acid ester resin and silica particles, wherein the ratio Cs2/Cs1 of the surface coverage rate Cs1 by silica particles before and after stress application is less than 0.4 or greater than 0.8, and which have superior adhesion to the surfaces of a recording medium so that they can be peeled apart.
According to the invention of <21> or <22>, a method for manufacturing printed materials is provided that applies pressure-responsive particles comprising pressure-responsive mother particles containing a styrene resin and a (meth)acrylic acid ester resin and silica particles, wherein the ratio Cs2/Cs1 of the surface coverage rate Cs1 by silica particles before and after stress application is less than 0.4 or greater than 0.8, and which have superior adhesion to the surfaces of a recording medium so as to be peelable.
According to the invention of <23> or <24>, a printed material is provided to which pressure-responsive particles are applied that have superior adhesion to the surfaces of a recording medium in a peelable manner, compared to pressure-responsive particles that include pressure-responsive mother particles containing a styrene resin and a (meth)acrylic acid ester resin and silica particles, wherein the ratio Cs2/Cs1 of the surface coverage rate Cs1 by silica particles before and after stress application to the surface coverage rate Cs2 is less than 0.4 or greater than 0.8.
According to the invention of <25>, a sheet for manufacturing printed materials is provided that uses pressure-responsive particles comprising pressure-responsive mother particles containing a styrene resin and a (meth)acrylic acid ester resin and silica particles, wherein the ratio Cs2/Cs1 of the surface coverage rate Cs1 by silica particles before and after stress application is less than 0.4 or greater than 0.8, and the pressure-responsive particles have superior adhesion to the surfaces of a recording medium so that they can be peeled apart.
According to the invention of <26>, a method for manufacturing a sheet for printing is provided, which uses pressure-responsive particles comprising pressure-responsive mother particles containing a styrene resin and a (meth)acrylic acid ester resin and silica particles, wherein the ratio Cs2/Cs1 of the surface coverage rate Cs1 by silica particles before and after stress application is less than 0.4 or greater than 0.8, and which have superior adhesion to the surfaces of a recording medium so that they can be peeled together.

This is a schematic diagram showing an example of a printing apparatus according to this embodiment. This is a schematic diagram of an inkjet recording device, which is an example of a color image forming device. This is a schematic diagram showing another example of a printing apparatus according to this embodiment. This is a schematic diagram showing another example of a printing apparatus according to this embodiment.

The embodiments of this disclosure are described below. These descriptions and embodiments are illustrative and do not limit the scope of the embodiments.

In this disclosure, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively.

In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values shown in the examples.

In this disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that their intended purpose is achieved.

When embodiments are described in this disclosure with reference to the drawings, the configuration of such embodiments is not limited to that shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the components are not limited thereto.

In this disclosure, each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition in this disclosure, if multiple types of the substance corresponding to each component are present in the composition, unless otherwise specified, it refers to the total amount of those multiple types of substances present in the composition.

In this disclosure, each component may contain multiple types of particles. If multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for a mixture of such multiple types of particles present in the composition, unless otherwise specified.

In this disclosure, the term "(meth)acrylic" means that either "acrylic" or "methacrylic" is acceptable.

In this disclosure, a printed material formed by folding recording media and bonding opposing surfaces together, or a printed material formed by stacking two or more recording media and bonding opposing surfaces together, is referred to as a "pressure-bonded printed material."

<Pressure-responsive particles>
The pressure-responsive particles according to this embodiment are
A pressure-responsive mother particle containing a styrene-based resin containing styrene and other vinyl monomers as polymerization components, and a (meth)acrylic acid ester-based resin containing at least two types of (meth)acrylic acid esters as polymerization components, wherein the mass ratio of (meth)acrylic acid esters to the total polymerization components is 90% by mass or more,
Contains silica particles,
It has at least two glass transition temperatures, and the difference between the lowest and highest glass transition temperatures is 30°C or more.

The pressure-responsive particles according to this embodiment are pressure-responsive particles that soften under pressure and adhere to the surfaces of recording media in a peelable manner.

The pressure-responsive particles according to this embodiment undergo a phase transition in response to pressure by exhibiting the thermal characteristic of having "at least two glass transition temperatures, with a difference of 30°C or more between the lowest and highest glass transition temperatures." In this disclosure, a pressure-responsive particle that undergoes a phase transition in response to pressure refers to a pressure-responsive particle that satisfies the following equation 1.

Formula 1...10℃≦T1-T2
In Equation 1, T1 is the temperature at which the viscosity is 10,000 Pa·s at a pressure of 1 MPa, and T2 is the temperature at which the viscosity is 10,000 Pa·s at a pressure of 10 MPa. The methods for determining temperatures T1 and T2 will be described later.

The pressure-responsive particles according to this embodiment contain a "styrene-based resin containing styrene and other vinyl monomers as polymerization components" and a "(meth)acrylic acid ester-based resin containing at least two types of (meth)acrylic acid esters as polymerization components, wherein the mass ratio of (meth)acrylic acid esters to the total polymerization components is 90% by mass or more." This allows for easy phase transition under pressure and excellent adhesion. The following mechanism is presumed to be responsible:

Generally, styrene resins and (meth)acrylic acid ester resins have low compatibility with each other, so it is thought that both resins are contained in a phase-separated state within the pressure-responsive mother particles. Furthermore, when the pressure-responsive mother particles are pressurized, the (meth)acrylic acid ester resin, which has a relatively low glass transition temperature, is thought to flow first, and this flow then spreads to the styrene resin, causing both resins to flow. In addition, it is thought that after the two resins in the pressure-responsive mother particles flow under pressure, they solidify as the pressure decreases to form a resin layer, and due to their low compatibility, they form a phase-separated state again.
A (meth)acrylic acid ester resin containing at least two types of (meth)acrylic acid esters as polymerization components is presumed to have a lower degree of molecular alignment in the solid state compared to a (meth)acrylic acid ester homopolymer, because at least two types of ester groups are bonded to the main chain, and therefore is more easily fluidized by pressure. Furthermore, if the mass ratio of (meth)acrylic acid esters to the total polymerization component is 90% by mass or more, at least two types of ester groups will be present at a high density, so the degree of molecular alignment in the solid state will be even lower, and therefore it is presumed to be even more easily fluidized by pressure. Accordingly, it is presumed that the pressure-responsive particles according to this embodiment are more easily fluidized by pressure, that is, more easily undergo a phase transition by pressure, compared to pressure-responsive particles in which the (meth)acrylic acid ester resin is a (meth)acrylic acid ester homopolymer.
Furthermore, a (meth)acrylic acid ester resin containing at least two types of (meth)acrylic acid esters as polymer components, in which the mass ratio of (meth)acrylic acid esters to the total polymer components is 90% by mass or more, is presumed to have a low degree of molecular alignment even when solidified again, resulting in minimal phase separation with the styrene resin. The smaller the phase separation between the styrene resin and the (meth)acrylic acid ester resin, the more uniform the state of the adhesive surface to the adherend becomes, and the superior the adhesive properties are presumed to be. Therefore, the pressure-responsive particles according to this embodiment are presumed to have superior adhesive properties compared to pressure-responsive particles in which the (meth)acrylic acid ester resin is a homopolymer of (meth)acrylic acid esters.

The pressure-responsive particles according to this embodiment include pressure-responsive mother particles and silica particles, and the ratio of the surface coverage rate Cs1 by the silica particles before applying stress (first stress and second stress) to the surface coverage rate Cs2 by the silica particles after applying the first stress satisfies the relationship 0.4 ≤ Cs2/Cs1 ≤ 0.8.
First stress test: Under a temperature of 20°C and a relative humidity of 50%, 10 g of pressure-responsive particles and 90 g of resin-coated ferrite particles are placed in a 0.5 L rotary V-type mixer and operated at a rotation speed of 40 revolutions per minute for 20 minutes.

From the standpoint of storage suitability for pressure-responsive particles, it is necessary that a portion of the surface of the pressure-responsive particles be coated with silica particles. However, when pressure-responsive particles soften under pressure and adhere to the surfaces of recording media, the silica particles tend to weaken the adhesive properties. To achieve excellent storage and adhesive properties for pressure-responsive particles, it is desirable that the surface coating rate of silica particles be relatively high during storage and relatively low during adhesion.
Incidentally, while there are no limitations on the method of imparting pressure-responsive particles to a recording medium, most methods apply mechanical stress to the pressure-responsive particles inside and at the outlet of the imparting device. The inventor focused on the mechanical stress in the imparting device and conceived of varying the surface coverage of the silica particles within an appropriate range before and after a predetermined stress is applied to the pressure-responsive particles.
If the ratio of surface coverage Cs1 to surface coverage Cs2, Cs2/Cs1, is greater than 0.8, a relatively large amount of silica particles remain on the surface of the pressure-responsive particles and are attached to the recording medium, which may result in insufficient adhesion to the recording medium.
If the ratio of surface coverage rate Cs1 to surface coverage rate Cs2, Cs2/Cs1, is less than 0.4, a relatively large amount of silica particles may detach from the pressure-responsive particles inside or at the outlet of the application device. As a result, the pressure-responsive particles aggregate and are applied to the recording medium, leading to uneven application of the pressure-responsive particles and potentially insufficient adhesion to the recording medium.
Therefore, the ratio of surface coverage Cs1 to surface coverage Cs2, Cs2/Cs1, is preferably 0.4 ≤ Cs2/Cs1 ≤ 0.8, and 0.5 ≤ Cs2/Cs1 ≤ 0.7.

From the viewpoint of storage properties of pressure-responsive particles, the surface coverage ratio Cs1 is preferably 40% or more, more preferably 45% or more, and even more preferably 50% or more. From the viewpoint of excellent adhesion due to the ease with which pressure-responsive particles undergo phase transitions, it is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less.

The surface coverage ratio Cs2 is preferably 35% or more, more preferably 40% or more, and even more preferably 45% or more, from the viewpoint of suppressing the aggregation of pressure-responsive particles inside the application device or on the recording medium. From the viewpoint of excellent adhesion due to the ease with which pressure-responsive particles undergo phase transitions, it is preferably 60% or less, more preferably 55% or less, and even more preferably 50% or less.

In this embodiment, from the viewpoint of achieving both adhesion and storage properties of the pressure-responsive particles, it is preferable that the ratio of the surface coverage rate Cs2 of the silica particles after applying a first stress to the surface coverage rate Cs3 of the silica particles after applying a second stress satisfies the relationship 0.4 ≤ Cs2/Cs3 ≤ 0.9.
When the ratio of surface coverage Cs2 to surface coverage Cs3, Cs2/Cs3, is 0.4 or higher, for example, when pressure-responsive particles are applied to a recording medium and then excess pressure-responsive particles are recovered, an appropriate dispersion of the external additive can be formed on the particle surface while the recovered pressure-responsive particles are being transported. This suppresses the aggregation of the particles, resulting in excellent adhesion and storage properties of the pressure-responsive particles (especially the storage properties of the recovered pressure-responsive particles).
When the ratio of surface coverage Cs2 to surface coverage Cs3, Cs2/Cs3, is 0.9 or less, the external coating state of the recovered pressure-responsive particle surface can be maintained, resulting in excellent adhesion and storage properties of the pressure-responsive particles (especially the storage properties of the recovered pressure-responsive particles). When Cs2/Cs3 is greater than 0.9, aggregation may occur among the recovered pressure-responsive particles, which can lead to the adhesion of pressure-responsive particles inside the printing equipment using the pressure-responsive particles and the resulting contamination of the printing equipment, which is undesirable.
From the above viewpoint, the ratio of surface coverage Cs2 to surface coverage Cs3, Cs2/Cs3, is preferably 0.4 ≤ Cs2/Cs3 ≤ 0.9, and more preferably 0.4 ≤ Cs2/Cs3 ≤ 0.8.

From the viewpoint of excellent adhesion and storage properties of pressure-responsive particles (especially storage properties of recovered pressure-responsive particles), the surface coverage ratio Cs3 is preferably 40% or more, more preferably 45% or more, preferably 60% or less, and more preferably 55% or less.

The application of the first and second stresses to the pressure-responsive particles shall be carried out as follows:

-The first stressor-
Prepare resin-coated ferrite particles. The coating resin is polymethyl methacrylate. The specific gravity of the resin-coated ferrite particles is 4.6 g/ ^cm³ . The volume-average particle size of the resin-coated ferrite particles is between 25 μm and 50 μm.
After controlling the temperature and humidity by placing pressure-responsive particles and resin-coated ferrite particles at a temperature of 20°C and a relative humidity of 50% for 24 hours or more, 10 g of pressure-responsive particles are placed in a 0.5 L rotary V-type mixer, followed by 90 g of resin-coated ferrite particles. The rotary V-type mixer is then operated at a rotation speed of 40 revolutions per minute for 20 minutes at a temperature of 20°C and a relative humidity of 50%.
After operation, the powder is removed from the container-rotating V-type mixer, and the pressure-responsive particles and resin-coated ferrite particles are separated by the electrode plate separation method. The recovered pressure-responsive particles are designated as the pressure-responsive particles after the first stress application.
- Plate separation method -
Two stainless steel plates are placed opposite each other with a 2 mm gap between them, and a DC voltage of 150 V is applied between the plates. Powder is placed between the two stainless steel plates. Only pressure-responsive particles adhere to the stainless steel plates, allowing for the separation of pressure-responsive particles from resin-coated ferrite particles.

- The second type of stress -
After controlling the temperature and humidity of the pressure-responsive particles by leaving them at 20°C and 50% relative humidity for 24 hours or more, 10 g of the pressure-responsive particles are placed in a 0.5 L rotary V-type mixer. The rotary V-type mixer is then operated at a rotation speed of 40 revolutions per minute for 20 minutes at 20°C and 50% relative humidity.
After operation, the powder is removed from the container-rotating V-type mixer, and the recovered pressure-responsive particles are designated as pressure-responsive particles after a second stress application.

The surface coverage ratio of pressure-responsive particles by silica particles is determined as follows:
Prepare 120 mg each of silica particles, pressure-responsive particles without silica, pressure-responsive particles before stress application, and pressure-responsive particles after stress (first or second stress). Using a tablet press, each is compressed into a 13 mm diameter disc, and these are used as the measurement samples.
X-ray photoelectron spectroscopy is used to analyze the types and quantities of elements in the sample at an acceleration voltage of 15 kV. By setting the acceleration voltage to the low voltage mentioned above, the surface of the sample is analyzed, that is, the surface of the particles is analyzed.
A calibration curve is created from sets of silica particles and pressure-responsive particles without silica added. The silicon content of the measurement sample consisting of pressure-responsive particles before stress application (or measurement sample consisting of pressure-responsive particles after stress application) is applied to this curve, and the surface coverage ratio Cs1 (or surface coverage ratio Cs2, surface coverage ratio Cs3) is calculated.

One method for controlling the surface coverage ratio Cs1 within the aforementioned range is to adjust the amount of silica particles added externally.
Methods for controlling the surface coverage ratio Cs2 and the ratio Cs2/Cs1 within the aforementioned ranges include, for example, adding relatively small silica particles and relatively large silica particles in an adjusted ratio, and adjusting the hardness of the pressure-responsive particle surface by ionic crosslinking of components contained in the surface layer of the pressure-responsive particles.

One method for controlling the surface coverage Cs3 within the aforementioned range is to adjust the circularity of the pressure-responsive matrix particles. Using pressure-responsive matrix particles with appropriate surface irregularities makes it easier to control the surface coverage Cs3 within the aforementioned range. Specifically, the circularity of the pressure-responsive matrix particles is preferably within the following range.

In this embodiment, from the viewpoint of achieving both adhesion and storability of the pressure-responsive particles, it is preferable that the average circularity of the pressure-responsive mother particles is 0.955 or more and 0.975 or less.
When the average circularity of the pressure-responsive mother particles is 0.955 or higher, the particles have a moderately rounded surface, allowing the external additive to be present between the particles, resulting in excellent adhesion and storability of the pressure-responsive particles (especially under high-stress conditions during transport in containers).
When the average circularity of the pressure-responsive mother particles is 0.975 or less, the pressure-responsive particles become capable of containing external additives in the surface irregularities, resulting in excellent adhesion and storability of the pressure-responsive particles (especially under high-stress conditions during transport in containers).
From the above viewpoint, the average circularity of the pressure-responsive mother particles is preferably 0.955 or more and 0.975 or less, more preferably 0.955 or more and 0.970 or less, and even more preferably 0.956 or more and 0.968 or less.

The average circularity of pressure-responsive mother particles can be controlled by adjusting the target temperature or holding time during the fusion and coalescence process when pressure-responsive mother particles are manufactured by the agglomeration and coalescence method. A higher target temperature during the fusion and coalescence process tends to result in higher average circularity of the manufactured particles. Similarly, a longer holding time at the target temperature during the fusion and coalescence process also tends to result in higher average circularity of the manufactured particles.

The average circularity of pressure-responsive matrix particles is measured as follows.
Pressure-responsive particles are added to a 5% by mass aqueous solution of sodium alkylbenzenesulfonate and stirred. Next, ultrasonic waves are applied using a bath-type ultrasonic disperser to release the external additive from the surface of the pressure-responsive mother particles. Then, the pressure-responsive mother particles are settled by centrifugation, and the supernatant liquid containing the released and dispersed external additive is removed. The process from ultrasonic treatment to supernatant removal is repeated three times to recover the solid components (i.e., pressure-responsive mother particles).
Add 0.1 ml of alkylbenzene sulfonate sodium to 100 ml of water, add 0.1 g of pressure-responsive mother particles, and disperse in a bath-type ultrasonic disperser for 1 to 3 minutes to prepare a dispersion. Using this dispersion as a measurement sample, analyze the projection images of 4500 particles using a flow-type particle image analyzer (e.g., Sysmex FPIA-3000). Calculate the circularity of each particle = {(perimeter of a circle with the same area as the particle projection image) ÷ (perimeter of the particle projection image)}, take the arithmetic mean of these values, and round to the fourth decimal place to obtain the average circularity.

In this embodiment, the Al element concentration on the surface of the pressure-responsive particles is preferably 0.1 atomic% to 1.5 atomic%. When the Al element concentration on the particle surface is 0.1 atomic% or higher, the particle surface hardens due to Al ion crosslinking, resulting in superior storage properties and easier control of the surface coverage ratio Cs2 and Cs2/Cs1 ratio. When the Al element concentration on the particle surface is 1.5 atomic% or lower, the pressure-responsive particles undergo a phase transition more easily under pressure, resulting in superior adhesion that allows for peelable bonding between surfaces of recording media. From these viewpoints, the Al element concentration on the surface of the pressure-responsive particles is more preferably 0.3 atomic% to 0.9 atomic%, and even more preferably 0.4 atomic% to 0.8 atomic%.

The Al element concentration on the surface of pressure-responsive particles is measured as follows:
Using a tablet press, 120 mg of pressure-responsive particles are compressed into a 13 mm diameter disc, which is used as the measurement sample. X-ray photoelectron spectroscopy is used to analyze the types and quantities of elements in the measurement sample with an acceleration voltage of 15 kV. By setting the acceleration voltage to the low voltage described above, the surface layer of the measurement sample is analyzed, that is, the surface layer of the pressure-responsive particles is analyzed. The surface layer refers to the range detectable by X-ray photoelectron spectroscopy under the above measurement conditions.
If the pressure-responsive particles contain an external additive, the external additive is removed from the surface of the pressure-responsive particles before preparing the measurement sample using a tablet molder. The external additive is removed from the surface of the pressure-responsive particles by repeatedly performing ultrasonic treatment in water (ultrasonic homogenizer "US-300T" manufactured by Nippon Seiki Seisakusho Co., Ltd., water temperature 40°C, amplitude 200 μm, 45 minutes), solid-liquid separation, and drying.

Methods for controlling the Al element concentration on the surface of pressure-responsive particles include, for example, selecting the type of flocculant and increasing or decreasing the amount of flocculant added in the pressure-responsive mother particle manufacturing method described later.

The components, structure, and properties of the pressure-responsive particles according to this embodiment will be described in detail below. In the following description, unless otherwise specified, "styrene-based resin" means "styrene-based resin containing styrene and other vinyl monomers as polymerization components," and "(meth)acrylic acid ester resin" means "(meth)acrylic acid ester resin containing at least two types of (meth)acrylic acid esters as polymerization components, wherein the mass ratio of (meth)acrylic acid esters to the total polymerization components is 90% by mass or more."

[Pressure-responsive parent particles]
The pressure-responsive mother particles contain at least a styrene-based resin and a (meth)acrylic acid ester-based resin. The pressure-responsive mother particles may also contain colorants, release agents, and other additives.

From the viewpoint of maintaining adhesion, the pressure-responsive mother particles preferably contain more styrene resin than (meth)acrylic acid ester resin. The styrene resin content is preferably 55% to 80% by mass, more preferably 60% to 75% by mass, and even more preferably 65% to 70% by mass, relative to the total content of styrene resin and (meth)acrylic acid ester resin.

- Styrene resin -
The pressure-responsive mother particles constituting the pressure-responsive particles according to this embodiment contain a styrene-based resin that includes styrene and other vinyl monomers as polymerization components.

The mass percentage of styrene in the total polymerization component of the styrene-based resin is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more, from the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state. From the viewpoint of forming pressure-responsive particles that are prone to phase transition under pressure, it is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

Examples of vinyl monomers other than styrene that constitute styrene-based resins include styrene-based monomers other than styrene and acrylic monomers.

Examples of styrene monomers other than styrene include vinylnaphthalene; alkyl-substituted styrenes such as α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, and p-n-dodecylstyrene; aryl-substituted styrenes such as p-phenylstyrene; alkoxy-substituted styrenes such as p-methoxystyrene; halogen-substituted styrenes such as p-chlorostyrene, 3,4-dichlorostyrene, p-fluorostyrene, and 2,5-difluorostyrene; and nitro-substituted styrenes such as m-nitrostyrene, o-nitrostyrene, and p-nitrostyrene. Styrene monomers may be used individually or in combination of two or more.

As the acrylic monomer, at least one acrylic monomer selected from the group consisting of (meth)acrylic acid and (meth)acrylic acid esters is preferred. Examples of (meth)acrylic acid esters include alkyl (meth)acrylates, carboxylated alkyl (meth)acrylates, hydroxylated alkyl (meth)acrylates, alkoxylated alkyl (meth)acrylates, and di(meth)acrylic acid esters. The acrylic monomer may be used alone or in combination of two or more.

Examples of alkyl methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, and isobornyl methacrylate.
Examples of carboxylated alkyl esters of (meth)acrylate include 2-carboxyethyl (meth)acrylate.
Examples of hydroxysubstituted alkyl esters of (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.
Examples of alkoxy-substituted alkyl esters of (meth)acrylate include 2-methoxyethyl (meth)acrylate.
Examples of di(meth)acrylic acid esters include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, pentanediol di(meth)acrylate, hexanediol di(meth)acrylate, nonanediol di(meth)acrylate, and decanediol di(meth)acrylate.

Examples of (meth)acrylic acid esters include 2-(diethylamino)ethyl (meth)acrylate, benzyl (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate.

Other vinyl monomers that constitute styrene-based resins include, in addition to styrene-based and acrylic-based monomers, (meth)acrylonitrile; vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone; and olefins such as isoprene, butene, and butadiene.

From the viewpoint of forming pressure-responsive particles that readily undergo phase transitions under pressure, styrene-based resins preferably contain (meth)acrylic acid esters as polymerization components, more preferably (meth)acrylic acid alkyl esters, even more preferably (meth)acrylic acid alkyl esters with 2 to 10 carbon atoms in the alkyl group, even more preferably (meth)acrylic acid alkyl esters with 4 to 8 carbon atoms in the alkyl group, and particularly preferably contain at least one of n-butyl acrylate and 2-ethylhexyl acrylate. From the viewpoint of forming pressure-responsive particles that readily undergo phase transitions under pressure, it is preferable for styrene-based resins and (meth)acrylic acid ester resins to contain the same type of (meth)acrylic acid ester as polymerization components.

The mass percentage of (meth)acrylic acid ester in the total polymerization components of the styrene-based resin is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, from the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state. From the viewpoint of forming pressure-responsive particles that are prone to phase transition under pressure, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Here, alkyl (meth)acrylic acid esters are preferred, alkyl (meth)acrylic acid esters with 2 to 10 carbon atoms in the alkyl group are more preferred, and alkyl (meth)acrylic acid esters with 4 to 8 carbon atoms in the alkyl group are even more preferred.

The styrene-based resin is particularly preferably composed of at least one of n-butyl acrylate and 2-ethylhexyl acrylate as polymerization components. The total amount of n-butyl acrylate and 2-ethylhexyl acrylate in the total polymerization components of the styrene-based resin is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, from the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state. From the viewpoint of forming pressure-responsive particles that are prone to phase transition under pressure, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more.

The weight-average molecular weight of the styrene-based resin is preferably 3000 or more, more preferably 4000 or more, and even more preferably 5000 or more, from the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state. From the viewpoint of forming pressure-responsive particles that are prone to phase transitions under pressure, it is preferably 60000 or less, more preferably 55000 or less, and even more preferably 50000 or less.

In this disclosure, the weight-average molecular weight of the resin is measured by gel permeation chromatography (GPC). The GPC measurement is performed using a Tosoh HLC-8120GPC as the GPC instrument, a Tosoh TSKgel SuperHM-M (15 cm) as the column, and tetrahydrofuran as the solvent. The weight-average molecular weight of the resin is calculated using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

The glass transition temperature of the styrene-based resin is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 50°C or higher, from the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state. From the viewpoint of forming pressure-responsive particles that are easily subjected to phase transition by pressure, it is preferably 110°C or lower, more preferably 100°C or lower, and even more preferably 90°C or lower.

In this disclosure, the glass transition temperature of the resin is determined from the differential scanning calorimetry (DSC) curve obtained by differential scanning calorimetry (DSC). More specifically, it is determined according to the "extracorporeal glass transition onset temperature" described in JIS K7121:1987 "Method for Measuring the Transition Temperature of Plastics".

The glass transition temperature of a resin can be controlled by the type and polymerization ratio of the polymerization components. The glass transition temperature tends to be lower when the density of flexible units such as methylene groups, ethylene groups, and oxyethylene groups in the main chain is high, and higher when the density of rigid units such as aromatic rings and cyclohexane rings in the main chain is high. Furthermore, the glass transition temperature tends to be lower when the density of aliphatic groups in the side chains is high.

In this embodiment, the mass percentage of styrene-based resin in the total pressure-responsive mother particles is preferably 55% by mass or more, more preferably 60% by mass or more, and even more preferably 65% by mass or more, from the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state. From the viewpoint of forming pressure-responsive particles that are prone to phase transition under pressure, it is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less.

- (meth)acrylic acid ester resin -
The pressure-responsive mother particles constituting the pressure-responsive particles according to this embodiment contain a (meth)acrylic acid ester resin in which at least two types of (meth)acrylic acid esters are included as polymerization components, and the mass ratio of (meth)acrylic acid esters to the total polymerization components is 90% by mass or more.

The mass percentage of (meth)acrylic acid ester in the total polymerization components of the (meth)acrylic acid ester resin is 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

Examples of (meth)acrylic acid esters include alkyl (meth)acrylates, carboxylated alkyl (meth)acrylates, hydroxylated alkyl (meth)acrylates, alkoxylated alkyl (meth)acrylates, and di(meth)acrylic acid esters.

Examples of alkyl methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, and isobornyl methacrylate.
Examples of carboxylated alkyl esters of (meth)acrylate include 2-carboxyethyl (meth)acrylate.
Examples of hydroxysubstituted alkyl esters of (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.
Examples of alkoxy-substituted alkyl esters of (meth)acrylate include 2-methoxyethyl (meth)acrylate.
Examples of di(meth)acrylic acid esters include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, pentanediol di(meth)acrylate, hexanediol di(meth)acrylate, nonanediol di(meth)acrylate, and decanediol di(meth)acrylate.

Examples of (meth)acrylic acid esters include 2-(diethylamino)ethyl (meth)acrylate, benzyl (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate.

(Meth)acrylic acid esters may be used individually or in combination of two or more types.

As the (meth)acrylic acid ester, from the viewpoint of forming pressure-responsive particles that readily undergo phase transition under pressure and exhibit excellent adhesion, alkyl (meth)acrylic acid esters are preferred, more preferably (meth)acrylic acid alkyl esters with 2 to 10 carbon atoms in the alkyl group, even more preferably (meth)acrylic acid alkyl esters with 4 to 8 carbon atoms in the alkyl group, and particularly preferred are n-butyl acrylate and 2-ethylhexyl acrylate. From the viewpoint of forming pressure-responsive particles that readily undergo phase transition under pressure, it is preferable that the styrene-based resin and the (meth)acrylic acid ester-based resin contain the same type of (meth)acrylic acid ester as a polymerization component.

The mass percentage of alkyl (meth)acrylate in the total polymerization components of the (meth)acrylic acid ester resin is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass, from the viewpoint of forming pressure-responsive particles that readily undergo phase transition under pressure and have excellent adhesive properties. Here, alkyl (meth)acrylate has two to ten carbon atoms in the alkyl group, and alkyl (meth)acrylate has four to eight carbon atoms in the alkyl group, which is more preferable.

Of the at least two (meth)acrylic acid esters included as polymerization components in the (meth)acrylic acid ester resin, the mass ratio of the two most abundant esters is preferably 80:20 to 20:80, more preferably 70:30 to 30:70, and even more preferably 60:40 to 40:60, from the viewpoint of forming pressure-responsive particles that readily undergo phase transitions under pressure and exhibit excellent adhesion.

In a (meth)acrylic acid ester resin, it is preferable that the two (meth)acrylic acid esters present in the largest mass proportions among at least two (meth)acrylic acid esters included as polymerization components are alkyl (meth)acrylic acid esters. Here, alkyl (meth)acrylic acid esters with 2 to 10 carbon atoms in the alkyl group are preferred, and alkyl (meth)acrylic acid esters with 4 to 8 carbon atoms in the alkyl group are more preferred.

When at least two types of (meth)acrylic acid esters are included as polymerization components in a (meth)acrylic acid ester resin, and the two types with the highest mass proportions are alkyl (meth)acrylic acid esters, the difference in the number of carbon atoms between the alkyl groups of these two alkyl (meth)acrylic acid esters is preferably 1 to 4, more preferably 2 to 4, and even more preferably 3 or 4, from the viewpoint of forming pressure-responsive particles that are easily transferred by pressure and have excellent adhesive properties.

From the viewpoint of forming pressure-responsive particles that readily undergo phase transition under pressure and exhibit excellent adhesion, (meth)acrylic acid ester resins preferably contain n-butyl acrylate and 2-ethylhexyl acrylate as polymerization components. It is particularly preferable that, among the at least two (meth)acrylic acid esters included as polymerization components in the (meth)acrylic acid ester resin, the two with the highest mass proportions are n-butyl acrylate and 2-ethylhexyl acrylate. The total amount of n-butyl acrylate and 2-ethylhexyl acrylate in the total polymerization components of the (meth)acrylic acid ester resin is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

(Meth)acrylic acid ester resins may contain vinyl monomers other than (meth)acrylic acid esters as polymerization components. Examples of vinyl monomers other than (meth)acrylic acid esters include (meth)acrylic acid; styrene; styrene monomers other than styrene; (meth)acrylonitrile; vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone; and olefins such as isoprene, butene, and butadiene. These vinyl monomers may be used individually or in combination of two or more.

When a (meth)acrylic acid ester resin contains a vinyl monomer other than (meth)acrylic acid ester as a polymerization component, at least one of acrylic acid and methacrylic acid is preferred as the vinyl monomer other than (meth)acrylic acid ester, with acrylic acid being more preferred.

The weight-average molecular weight of the (meth)acrylic acid ester resin is preferably 50,000 or more, more preferably 100,000 or more, even more preferably 120,000 or more, and even more preferably 150,000 or more, from the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state. From the viewpoint of forming pressure-responsive particles that are prone to phase transition under pressure, it is preferably 250,000 or less, more preferably 220,000 or less, and even more preferably 200,000 or less.

The glass transition temperature of (meth)acrylic acid ester resins is preferably 10°C or lower, more preferably 0°C or lower, and even more preferably -10°C or lower, from the viewpoint of forming pressure-responsive particles that readily undergo phase transition under pressure. From the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state, it is preferably -90°C or higher, more preferably -80°C or higher, and even more preferably -70°C or higher.

In this embodiment, the mass percentage of the (meth)acrylic acid ester resin in the total pressure-responsive mother particles is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, from the viewpoint of forming pressure-responsive particles that readily undergo phase transitions under pressure. From the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state, it is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less.

In this embodiment, the total amount of styrene-based resin and (meth)acrylic acid ester-based resin contained in the pressure-responsive mother particles is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass, relative to the total amount of pressure-responsive mother particles.

- Other resins -
The pressure-responsive mother particles may contain, for example, polystyrene; non-vinyl resins such as epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, and modified rosin. These resins may be used individually or in combination of two or more.

- Various additives -
The pressure-responsive mother particles may, if necessary, contain colorants (e.g., pigments, dyes), release agents (e.g., hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral/petroleum waxes such as montan wax; ester waxes such as fatty acid esters and montanic acid esters), and charge control agents.

When the pressure-responsive particles according to this embodiment are transparent, the amount of colorant in the pressure-responsive mother particles is preferably 1.0% by mass or less relative to the total amount of pressure-responsive mother particles, and from the viewpoint of increasing the transparency of the pressure-responsive particles, the less colorant, the better.

- Structure of pressure-responsive parent particles -
In the pressure-responsive mother particles, it is preferable that styrene resin and (meth)acrylic acid ester resin are mixed in a phase-separated state. In this case, it is preferable that the styrene resin is contained in a relatively continuous state and the (meth)acrylic acid ester resin is contained in a relatively discontinuous state. In this case, the continuous phase containing the styrene resin is the "sea phase," and the dispersed phase containing the (meth)acrylic acid ester resin is the "island phase." In this embodiment, a structure having a continuous sea phase and a dispersed island phase is called a sea-island structure.

The internal structure of the pressure-responsive mother particles is preferably a sea-island structure. Preferably, this sea-island structure comprises a sea phase containing a styrene-based resin and island phases containing (meth)acrylic acid ester resin dispersed within the sea phase. The specific form of the styrene-based resin contained in the sea phase is as described above. The specific form of the (meth)acrylic acid ester resin contained in the island phase is as described above. Island phases without (meth)acrylic acid ester resin may also be dispersed in the sea phase.

When the pressure-responsive parent particles have a sea-island structure, the average diameter of the island phase is preferably between 200 nm and 500 nm. A minimum average island phase diameter of 500 nm facilitates phase transitions in the pressure-responsive parent particles, while a minimum average island phase diameter of 200 nm provides superior mechanical strength (e.g., resistance to deformation when agitated in a developing chamber). From these perspectives, a minimum average island phase diameter of 220 nm to 450 nm is more preferable, and 250 nm to 400 nm is even more preferable.

Methods for controlling the average diameter of the island phase in a sea-island structure within the above range include, for example, increasing or decreasing the amount of (meth)acrylic acid ester resin relative to the amount of styrene resin in the pressure-responsive mother particle manufacturing method described later, and increasing or decreasing the time spent maintaining a high temperature in the process of fusing and coalescing aggregated resin particles.

The confirmation of the sea-island structure and the measurement of the average diameter of the island formation will be carried out by the following method.
Pressure-responsive particles are embedded in epoxy resin, sections are prepared using a diamond knife or similar tool, and the prepared sections are stained with osmium tetroxide or ruthenium tetroxide in a desiccator. The stained sections are observed using a scanning electron microscope (SEM). The sea phase and island phase of a sea-island structure are distinguished by the degree of staining of the resin with osmium tetroxide or ruthenium tetroxide, and this is used to confirm the presence or absence of a sea-island structure. 100 island phases are randomly selected from the SEM images, the major axis of each island phase is measured, and the average of the major axes of the 100 is taken as the average diameter.

The pressure-responsive mother particle may be a single-layer structure or a core-shell structure having a core and a shell layer covering the core. From the viewpoint of suppressing the fluidization of the pressure-responsive particle in the unpressurized state, a core-shell structure is preferable for the pressure-responsive mother particle.

When pressure-responsive parent particles have a core-shell structure, it is preferable that the core portion contains a styrene-based resin and a (meth)acrylic acid ester resin, from the viewpoint of easily undergoing a phase transition under pressure. Furthermore, from the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state, it is preferable that the shell layer contains a styrene-based resin. The specific form of the styrene-based resin is as described above. The specific form of the (meth)acrylic acid ester resin is as described above.

When the pressure-responsive mother particles have a core-shell structure, it is preferable that the core portion has a sea phase containing a styrene-based resin and an island phase containing a (meth)acrylic acid ester resin dispersed in the sea phase. The average diameter of the island phase is preferably within the range described above. Furthermore, in addition to the above configuration of the core portion, it is preferable that the shell layer also contains a styrene-based resin. In this case, the sea phase and shell layer of the core portion have a continuous structure, making the pressure-responsive mother particles more susceptible to phase transitions under pressure. The specific forms of the styrene-based resin contained in the sea phase and shell layer of the core portion are as described above. The specific forms of the (meth)acrylic acid ester resin contained in the island phase of the core portion are as described above.

Examples of resins that can be included in the shell layer include polystyrene; epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, modified rosin, and other non-vinyl resins. These resins may be used individually or in combination of two or more.

The average thickness of the shell layer is preferably 120 nm or more, more preferably 130 nm or more, and even more preferably 140 nm or more, from the viewpoint of suppressing deformation of pressure-responsive parent particles. From the viewpoint of the pressure-responsive parent particles being more susceptible to phase transitions, it is preferably 550 nm or less, more preferably 500 nm or less, and even more preferably 400 nm or less.

The average thickness of the shell layer is measured by the following method.
Pressure-responsive particles are embedded in epoxy resin, sections are prepared using a diamond knife or similar tool, and the prepared sections are stained with osmium tetroxide or ruthenium tetroxide in a desiccator. The stained sections are observed using a scanning electron microscope (SEM). Ten cross-sections of pressure-responsive parent particles are randomly selected from the SEM images, and the thickness of the shell layer is measured at 20 locations for each pressure-responsive parent particle. The average value is calculated, and the average value of the 10 pressure-responsive parent particles is taken as the average thickness.

The volume-average particle size (D50v) of the pressure-responsive mother particles is preferably 4 μm or larger, more preferably 5 μm or larger, and even more preferably 6 μm or larger, from the viewpoint of ease of handling the pressure-responsive mother particles. From the viewpoint of the overall phase transition of the pressure-responsive mother particles being easily affected by pressure, it is preferably 12 μm or smaller, more preferably 10 μm or smaller, and even more preferably 9 μm or smaller.

The volume-average particle size (D50v) of pressure-responsive mother particles is measured using a Coulter Multisizer II (Beckman Coulter) and an aperture with a diameter of 100 μm. 0.5 mg to 50 mg of pressure-responsive mother particles are added to 2 mL of a 5% by mass aqueous solution of sodium alkylbenzenesulfonate and dispersed. Then, 100 mL to 150 mL of electrolyte (ISOTON-II, Beckman Coulter) is added, and the mixture is dispersed for 1 minute using an ultrasonic disperser. The resulting dispersion is used as the sample. The particle sizes of 50,000 particles with a diameter of 2 μm to 60 μm in the sample are measured. The volume-average particle size (D50v) is defined as the particle size that accounts for 50% of the cumulative volume-based particle size distribution calculated from the smallest diameter side.

[Silica particles]
The pressure-responsive particles according to this embodiment include silica particles as an external additive. Examples of silica particles include fumed silica particles, sol-gel silica particles, and mixtures thereof.
Methods for producing fumed silica particles are well known. Sol-gel methods for producing sol-gel silica particles are also well known. The sol-gel method includes, for example, preparing a silica sol suspension by dropping ammonia water into a mixture of tetraalkoxysilane, water, and alcohol, centrifuging wet silica gel from the silica sol suspension, and drying the wet silica gel to obtain silica particles. Examples of tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

The surface of the silica particles is preferably subjected to a hydrophobic treatment. The hydrophobic treatment is performed, for example, by immersing the silica particles in a hydrophobic agent. The hydrophobic agent is not particularly limited, but examples include silane-based coupling agents, silicone oil, titanate-based coupling agents, and aluminum-based coupling agents. These may be used individually or in combination of two or more. The amount of the hydrophobic agent is, for example, 1 to 10 parts by mass per 100 parts by mass of silica particles.

From the viewpoint of controlling the surface coverage ratio Cs2/Cs1, it is preferable to use in combination silica particles with a particle size of 100 nm or less (referred to as "small-diameter silica particles" in this disclosure) and silica particles with a particle size greater than 100 nm (referred to as "large-diameter silica particles" in this disclosure).
When small-diameter silica particles and large-diameter silica particles are added to a pressure-responsive mother particle, the small-diameter silica particles tend to adhere relatively strongly to the surface of the pressure-responsive mother particle, while the large-diameter silica particles tend to adhere relatively weakly to the surface of the pressure-responsive mother particle. The surface coverage ratio Cs2/Cs1 can be adjusted by changing the amount of small-diameter and large-diameter silica particles added.

Therefore, in this embodiment, when the particle size distribution of silica particles, which are an external additive for pressure-responsive particles, is analyzed, it is preferable that there are peaks in the range of particle size 100 nm or less and in the range of particle size greater than 100 nm.
The ratio of the mass Ms1 of silica particles with a particle size of 100 nm or less, determined from the particle size distribution of silica particles, to the mass Ms2 of silica particles with a particle size greater than 100 nm, determined from the particle size distribution of silica particles, is preferably 0.5 ≤ Ms2/Ms1 ≤ 1.3, and more preferably 0.6 ≤ Ms2/Ms1 ≤ 1.0.

The particle size distribution of silica particles is determined as follows.
Pressure-responsive particles are observed using a scanning electron microscope (S-4800, Hitachi High-Technologies Corporation) equipped with an energy-dispersive X-ray analyzer (EMAX Evolution, Horiba, Ltd.), and images are captured at a magnification of 40,000x. During this process, energy-dispersive X-ray analysis is used to identify more than 300 primary silica particles within a single field of view, based on the presence of silicon. The scanning electron microscope observation is performed with an acceleration voltage of 15kV, emission current of 20μA, and a WD of 15mm, while energy-dispersive X-ray analysis is performed under the same conditions with a detection time of 60 minutes. The captured images are imported into an image analysis system (LUZEXIII, Nireco Corporation) to determine the area of the primary silica particles. The equivalent circle diameter (nm) is calculated from the area, and this equivalent circle diameter is used as the particle size of the silica particles to draw a distribution curve.

The amount of small-diameter silica particles added is preferably 1.0 part by mass or more and 2.5 parts by mass or less, and more preferably 1.2 parts by mass or more and 2.2 parts by mass or less, per 100 parts by mass of pressure-responsive mother particles.
The amount of large-diameter silica particles added is preferably 0.8 parts by mass or more and 2.0 parts by mass or less, and more preferably 1.0 part by mass or more and 1.8 parts by mass or less, per 100 parts by mass of pressure-responsive mother particles.
The total amount of silica particles added is preferably 1.8 parts by mass or more and 4.5 parts by mass or less, and more preferably 2.0 parts by mass or more and 4.0 parts by mass or less, per 100 parts by mass of pressure-responsive mother particles.

From the viewpoint of achieving both adhesion and storage properties of the pressure-responsive particles according to this embodiment, the average particle size of the silica particles attached to the pressure-responsive particles is preferably 50 nm to 300 nm, more preferably 80 nm to 200 nm, and even more preferably 100 nm to 150 nm.
The average particle size of the silica particles attached to the pressure-responsive particles is the particle size at which the cumulative 50% of the particle size distribution is calculated from the smallest diameter side, using the equivalent circle diameter (nm) obtained from the aforementioned scanning electron microscope observation as the particle size of the silica particles.

[Other external additives]
The pressure-responsive particles according to this embodiment may contain external additives other than silica particles. Examples of external additives other than silica particles include _TiO₂ , _Al₂O₃ , _CuO , ZnO _{, SnO₂} , _CeO₂ , _Fe₂O₃ , _MgO , BaO, CaO, _K₂O , Na₂O, _ZrO₂ , CaO・_SiO₂ , _K₂O・( _TiO₂ )n, _Al₂O₃・_2SiO₂ , _CaCO₃ , _MgCO₃ , _BaSO₄ , _{MgSO₄ ,} and the like.

The surface of the inorganic particles used as an external additive should preferably be subjected to a hydrophobic treatment. This hydrophobic treatment can be performed, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, but examples include silane-based coupling agents, silicone oil, titanate-based coupling agents, and aluminum-based coupling agents. These may be used individually or in combination of two or more. The amount of the hydrophobic treatment agent is, for example, 1 to 10 parts by mass per 100 parts by mass of inorganic particles.

Examples of external additives include resin particles (such as polystyrene, polymethyl methacrylate, and melamine resin particles), and cleaning activators (for example, metal salts of higher fatty acids represented by zinc stearate, and fluorine-based high molecular weight particles).

When pressure-responsive particles contain external additives other than silica particles, the total amount of external additives other than silica particles is preferably 0.01% to 5% by mass, and more preferably 0.01% to 2.0% by mass, relative to the pressure-responsive mother particles.

[Characteristics of pressure-responsive particles]
The pressure-responsive particles according to this embodiment have at least two glass transition temperatures, one of which is presumed to be the glass transition temperature of the styrene-based resin, and the other presumed to be the glass transition temperature of the (meth)acrylic acid ester-based resin.

The pressure-responsive particles according to this embodiment may have three or more glass transition temperatures, but it is preferable that the number of glass transition temperatures be two. Examples of forms with two glass transition temperatures include: a form in which the resin contained in the pressure-responsive particles consists only of styrene-based resin and (meth)acrylic acid ester resin; and a form in which the content of other resins other than styrene-based resin and (meth)acrylic acid ester resin is low (for example, a form in which the content of other resins is 5% by mass or less relative to the total pressure-responsive particles).

The pressure-responsive particles according to this embodiment have at least two glass transition temperatures, with a difference of 30°C or more between the lowest and highest glass transition temperatures. From the viewpoint of facilitating phase transitions in the pressure-responsive particles, the difference between the lowest and highest glass transition temperatures is more preferably 40°C or more, even more preferably 50°C or more, and even more preferably 60°C or more. The upper limit of the difference between the lowest and highest glass transition temperatures is, for example, 140°C or less, 130°C or less, and 120°C or less.

The lowest glass transition temperature exhibited by the pressure-responsive particles according to this embodiment is preferably 10°C or lower, more preferably 0°C or lower, and even more preferably -10°C or lower, from the viewpoint of easily causing the pressure-responsive particles to undergo a phase transition under pressure. From the viewpoint of suppressing the fluidization of the pressure-responsive particles in the unpressurized state, it is preferably -90°C or higher, more preferably -80°C or higher, and even more preferably -70°C or higher.

The highest glass transition temperature exhibited by the pressure-responsive particles according to this embodiment is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 50°C or higher, from the viewpoint of suppressing fluidization of the pressure-responsive particles in the unpressurized state. From the viewpoint of the pressure-responsive particles being more susceptible to phase transition under pressure, it is preferably 70°C or lower, more preferably 65°C or lower, and even more preferably 60°C or lower.

In this disclosure, the glass transition temperature of pressure-responsive particles is determined from a differential scanning calorimetry (DSC) curve obtained by differential scanning calorimetry (DSC). More specifically, it is determined according to the "extracorporeal glass transition onset temperature" described in JIS K7121:1987 "Method for Measuring Transition Temperatures of Plastics".

The pressure-responsive particles according to this embodiment are pressure-responsive particles that undergo a phase transition due to pressure, and satisfy the following equation 1.
Formula 1...10℃≦T1-T2
In Equation 1, T1 is the temperature at which the viscosity is 10,000 Pa·s at a pressure of 1 MPa, and T2 is the temperature at which the viscosity is 10,000 Pa·s at a pressure of 10 MPa.

The temperature difference (T1-T2) is preferably 10°C or higher, more preferably 15°C or higher, and more preferably 20°C or higher, from the viewpoint of making pressure-responsive particles more susceptible to phase transitions under pressure. From the viewpoint of suppressing the fluidization of pressure-responsive particles in the unpressurized state, it is preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower.

The temperature T1 is preferably 140°C or lower, more preferably 130°C or lower, even more preferably 120°C or lower, and even more preferably 115°C or lower. The lower limit of the temperature T1 is preferably 80°C or higher, and more preferably 85°C or higher.
The temperature T2 is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. The upper limit of the temperature T2 is preferably 85°C or lower.

An indicator of how easily pressure-responsive particles undergo a phase transition due to pressure is the temperature difference (T1-T3) between the temperature T1 at which a viscosity of 10,000 Pa·s is observed at a pressure of 1 MPa and the temperature T3 at which a viscosity of 10,000 Pa·s is observed at a pressure of 4 MPa, with the temperature difference (T1-T3) preferably being 5°C or more. In this embodiment, from the viewpoint of how easily pressure-responsive particles undergo a phase transition due to pressure, the temperature difference (T1-T3) is preferably 5°C or more, and more preferably 10°C or more.
The temperature difference (T1-T3) is generally 25°C or less.

In this embodiment, the pressure-responsive particles exhibiting a viscosity of 10,000 Pa·s at a pressure of 4 MPa are preferably at a temperature T3 of 90°C or lower, more preferably at 85°C or lower, and even more preferably at 80°C or lower, from the viewpoint of achieving a temperature difference (T1-T3) of 5°C or more. The lower limit of temperature T3 is preferably 60°C or higher.

The method for determining temperatures T1, T2, and T3 is as follows:
A pelletized sample is prepared by compressing pressure-responsive particles. The pelletized sample is placed in a flow tester (Shimadzu Corporation, CFT-500), and the viscosity as a function of temperature at 1 MPa is measured with a fixed applied pressure of 1 MPa. From the obtained viscosity graph, the temperature T1 at which the viscosity is ^10⁴ Pa·s at an applied pressure of 1 MPa is determined. Temperature T2 is determined in the same manner as for temperature T1, except that the applied pressure is set to 10 MPa instead of 1 MPa. Temperature T3 is determined in the same manner as for temperature T1, except that the applied pressure is set to 4 MPa instead of 1 MPa. The temperature difference (T1-T2) is calculated from temperatures T1 and T2. The temperature difference (T1-T3) is calculated from temperatures T1 and T3.

[Method for manufacturing pressure-responsive particles]
The pressure-responsive particles according to this embodiment are obtained by manufacturing pressure-responsive mother particles and then adding an external additive to the pressure-responsive mother particles.

Pressure-responsive mother particles may be manufactured by either a dry method (e.g., kneading and grinding method) or a wet method (e.g., agglomeration, suspension polymerization, dissolution and suspension method). There are no particular restrictions on these methods; known methods can be used. Among these, obtaining pressure-responsive mother particles by agglomeration is preferable.

When producing pressure-responsive parent particles by agglomeration and coalescence method, for example,
The process involves preparing a styrene resin particle dispersion in which styrene resin particles containing styrene resin are dispersed (styrene resin particle dispersion preparation process),
A step of polymerizing a (meth)acrylic acid ester resin in a styrene resin particle dispersion to form composite resin particles containing styrene resin and (meth)acrylic acid ester resin (composite resin particle formation step),
The process involves agglomerating composite resin particles in a composite resin particle dispersion liquid to form aggregated particles (aggregated particle formation process),
Pressure-responsive parent particles are produced through a process (fusion and unification process) in which a dispersion of aggregated particles is heated to fuse and unify the aggregated particles and form pressure-responsive parent particles.

The details of each step are explained below.
The following description explains a method for obtaining pressure-responsive mother particles that do not contain colorants or release agents. Colorants, release agents, and other additives may be used as needed. When colorants and release agents are included in the pressure-responsive mother particles, a fusion and unification process is performed after mixing the composite resin particle dispersion, the colorant particle dispersion, and the release agent particle dispersion. The colorant particle dispersion and the release agent particle dispersion can be prepared, for example, by mixing the materials and then performing a dispersion process using a known disperser.

- Preparation process for styrene resin particle dispersion -
A styrene-based resin particle dispersion is, for example, a dispersion in which styrene-based resin particles are dispersed in a dispersion medium using a surfactant.

Examples of dispersion media include aqueous media such as water and alcohols. These may be used individually or in combination of two or more.

Examples of surfactants include anionic surfactants such as sulfate ester salts, sulfonates, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycol, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Nonionic surfactants may be used in combination with anionic or cationic surfactants. Among these, anionic surfactants are preferred. Surfactants may be used individually or in combination of two or more.

Methods for dispersing styrene-based resin particles in a dispersion medium include, for example, mixing the styrene-based resin with the dispersion medium and then dispersing it by stirring using a rotary shear homogenizer, a ball mill with media, a sand mill, a dyno mill, or the like.

Another method for dispersing styrene-based resin particles in a dispersion medium is emulsion polymerization. Specifically, the polymerization components of the styrene-based resin are mixed with a chain transfer agent or polymerization initiator, then an aqueous medium containing a surfactant is further mixed and stirred to prepare an emulsion, in which the styrene-based resin is polymerized. In this case, dodecanethiol is preferably used as the chain transfer agent.

The volume-average particle size of the styrene-based resin particles dispersed in the styrene-based resin particle dispersion is preferably 100 nm to 250 nm, more preferably 120 nm to 220 nm, and even more preferably 150 nm to 200 nm.
The volume-average particle size of resin particles contained in a resin particle dispersion is determined by measuring the particle size using a laser diffraction particle size distribution analyzer (for example, LA-700 manufactured by Horiba, Ltd.). The volume-average particle size (D50v) is defined as the particle size that accounts for 50% of the cumulative particle size distribution calculated from the smallest diameter side.

The content of styrene-based resin particles in the styrene-based resin particle dispersion is preferably 30% to 60% by mass, and more preferably 40% to 50% by mass.

-Composite resin particle formation process-
A dispersion of styrene-based resin particles and a polymerization component of (meth)acrylic acid ester resin are mixed, and the (meth)acrylic acid ester resin is polymerized in the dispersion of styrene-based resin particles to form composite resin particles containing styrene-based resin and (meth)acrylic acid ester resin.

The composite resin particles are preferably resin particles containing styrene-based resin and (meth)acrylic acid ester-based resin in a state of microphase separation. These resin particles can be manufactured, for example, by the following method.

A polymerization component of a (meth)acrylic acid ester resin (a monomer group containing at least two (meth)acrylic acid esters) is added to a dispersion of styrene resin particles, and an aqueous medium is added as needed. Next, while slowly stirring the dispersion, the temperature of the dispersion is heated to a temperature above the glass transition temperature of the styrene resin (for example, 10°C to 30°C higher than the glass transition temperature of the styrene resin). Then, while maintaining the temperature, an aqueous medium containing a polymerization initiator is slowly added dropwise, and stirring is continued for a long period of time, ranging from 1 hour to 15 hours. In this case, ammonium persulfate is preferably used as the polymerization initiator.

Although the detailed mechanism is not entirely clear, it is presumed that when the above method is employed, monomers and polymerization initiators are impregnated into the styrene-based resin particles, and (meth)acrylic acid ester polymerizes within the styrene-based resin particles. This is presumed to result in composite resin particles in which the (meth)acrylic acid ester resin is contained within the styrene-based resin particles, forming a state of microphase separation between the styrene-based resin and the (meth)acrylic acid ester resin within the particles.

During or after the manufacture of the above-mentioned composite resin particles, polymerization components of styrene-based resin (i.e., styrene and other vinyl monomers) may be added to the dispersion in which the composite resin particles are dispersed, and the polymerization reaction may be continued. It is presumed that this will result in composite resin particles in which the styrene-based resin and the (meth)acrylic acid ester resin form a state of microphase separation inside the particles, and the styrene-based resin adheres to the surface of the particles. Pressure-responsive particles manufactured using composite resin particles with styrene-based resin adhered to the surface generate relatively little coarse powder.
The other vinyl monomers that are polymerization components of the styrene-based resin attached to the surface of the composite resin particles preferably include at least one monomer that constitutes the styrene-based resin or (meth)acrylic acid ester resin inside the composite resin particles, and more preferably include at least one of n-butyl acrylate and 2-ethylhexyl acrylate.

The volume-average particle size of the composite resin particles dispersed in the composite resin particle dispersion is preferably 140 nm to 300 nm, more preferably 150 nm to 280 nm, and even more preferably 160 nm to 250 nm.

The content of composite resin particles in the composite resin particle dispersion is preferably 20% to 50% by mass, and more preferably 30% to 40% by mass.

-Agglomerated particle formation process-
The composite resin particles are aggregated in a composite resin particle dispersion to form aggregated particles with a diameter close to that of the target pressure-responsive mother particles.

Specifically, for example, a flocculant is added to a composite resin particle dispersion, the pH of the composite resin particle dispersion is adjusted to be acidic (e.g., pH 2 to 5), a dispersion stabilizer is added as needed, and then the mixture is heated to a temperature close to the glass transition temperature of the styrene resin (specifically, for example, between the glass transition temperature of the styrene resin - 30°C and below the glass transition temperature - 10°C) to flocce the composite resin particles and form flocculated particles.

In the aggregated particle formation process, the composite resin particle dispersion is stirred in a rotary shear homogenizer, a flocculant is added at room temperature (e.g., 25°C), the pH of the composite resin particle dispersion is adjusted to acidic (e.g., pH 2 to 5), a dispersion stabilizer is added as needed, and then heating may be performed.

Examples of flocculants include surfactants with opposite polarity to the surfactant contained in the composite resin particle dispersion, inorganic metal salts, and metal complexes with a valency of two or higher. When a metal complex is used as a flocculant, the amount of surfactant used is reduced and the electrostatic properties are improved.
Along with the flocculant, an additive that forms a complex or similar bond with the metal ions of the flocculant may be used as needed. A chelating agent is preferably used as this additive.

Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.
As a chelating agent, a water-soluble chelating agent may be used. Examples of chelating agents include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; and aminocarboxylic acids such as iminodiacid acetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA).
The amount of chelating agent added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of resin particles, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass.

-Fusion/unification process-
Next, the dispersion of aggregated particles is heated to a temperature above the glass transition temperature of the styrene resin (for example, 10°C to 30°C higher than the glass transition temperature of the styrene resin) to fuse and combine the aggregated particles and form pressure-responsive parent particles.

The pressure-responsive mother particles obtained through the above process typically have a sea-island structure, comprising a sea phase containing styrene-based resin and island phases containing (meth)acrylic acid ester resin dispersed within the sea phase. In the composite resin particles, the styrene-based resin and (meth)acrylic acid ester resin were in a state of microphase separation. It is presumed that during the fusion and coalescence process, the styrene-based resins aggregate to form the sea phase, and the (meth)acrylic acid ester resins aggregate to form the island phase.

The average diameter of the island phase in the sea-island structure can be controlled, for example, by increasing or decreasing the amount of styrene-based resin particle dispersion or the amount of at least two types of (meth)acrylic acid esters used in the composite resin particle formation process, or by increasing or decreasing the time maintained at high temperature in the fusion/combination process.

Pressure-responsive parent particles in a core-shell structure are, for example,
After obtaining an aggregated particle dispersion, the aggregated particle dispersion and the styrene-based resin particle dispersion are further mixed to aggregate the aggregated particles so that styrene-based resin particles adhere to the surface of the aggregated particles, thereby forming second aggregated particles.
A step of heating a second aggregate particle dispersion containing second aggregate particles to fuse and combine the second aggregate particles to form pressure-responsive mother particles with a core-shell structure,
It is manufactured through the following process.
The pressure-responsive core-shell structure obtained through the above process has a shell layer containing a styrene-based resin. Alternatively, a resin particle dispersion containing other types of resin particles may be used instead of the styrene-based resin particle dispersion to form a shell layer containing other types of resins.

After the fusion and coalescence process is complete, the pressure-responsive mother particles formed in the solution are subjected to known washing, solid-liquid separation, and drying processes to obtain dried pressure-responsive mother particles. From the viewpoint of electrostatic properties, the washing process should ideally involve thorough displacement washing with deionized water. From the viewpoint of productivity, the solid-liquid separation process should ideally involve suction filtration, pressure filtration, etc. From the viewpoint of productivity, the drying process should ideally involve freeze-drying, airflow drying, fluidized bed drying, vibratory fluidized bed drying, etc.

The pressure-responsive particles according to this embodiment are produced, for example, by adding an external additive to the obtained dry pressure-responsive mother particles and mixing them. Mixing is preferably performed using a V-blender, Henschel mixer, Lödige mixer, etc. Furthermore, if necessary, coarse particles of the pressure-responsive particles may be removed using a vibrating screen separator, wind screen separator, etc.

<Cartridge>
The cartridge according to this embodiment is a cartridge that contains pressure-responsive particles according to this embodiment and is attached to and detached from a printing apparatus. When the cartridge is attached to the printing apparatus, the cartridge and the arrangement means of the printing apparatus for arranging pressure-responsive particles on a recording medium are connected by a supply pipe.
Pressure-responsive particles are supplied from the cartridge to the dispensing mechanism, and when the amount of pressure-responsive particles contained in the cartridge decreases, the cartridge is replaced.

<Printing equipment, printing method, printed materials>
The printing apparatus according to this embodiment includes a placement means for containing pressure-responsive particles according to this embodiment and arranging the pressure-responsive particles on a recording medium, and a crimping means for folding and crimping the recording medium, or for stacking and crimping the recording medium with another recording medium.

The arrangement means may include, for example, an application device for applying pressure-responsive particles onto a recording medium, and further, a fixing device for fixing the pressure-responsive particles applied to the recording medium onto the recording medium.

The crimping means includes, for example, a folding device for folding a recording medium on which pressure-responsive particles are arranged, or a stacking device for stacking a recording medium on which pressure-responsive particles are arranged with another recording medium, and a pressing device for applying pressure to the stacked recording media.

The pressurizing device of the crimping means applies pressure to the recording medium on which the pressure-responsive particles are arranged. This causes the pressure-responsive particles to fluidize on the recording medium, resulting in adhesive properties.

The printing method according to this embodiment is carried out using the printing apparatus according to this embodiment. The printing method according to this embodiment includes a placement step of arranging the pressure-responsive particles according to this embodiment on a recording medium, and a pressing step of folding and pressing the recording medium, or pressing the recording medium and another recording medium together.

The placement process may include, for example, a step of applying pressure-responsive particles onto a recording medium, and further, a step of fixing the pressure-responsive particles applied to the recording medium onto the recording medium.

The crimping process includes, for example, a folding process in which recording media are folded, or a stacking process in which one recording media is stacked with another, and a pressing process in which the stacked recording media are pressed.

Pressure-responsive particles may be arranged across the entire surface of the recording medium or on a portion of it. One or more layers of pressure-responsive particles are arranged on the recording medium. The layers of pressure-responsive particles may be continuous in the plane direction of the recording medium or discontinuous in the plane direction of the recording medium. The layers of pressure-responsive particles may consist of individual particles arranged in a row, or they may consist of adjacent pressure-responsive particles that have fused together.

The amount of pressure-responsive particles (preferably transparent pressure-responsive particles) on the recording medium is, for example, 0.5 g/ ^m² to 50 g/ ^m² , 1 g/ ^m² to 40 g/ ^m² , or 1.5 g/ ^m² to 30 g/ ^m² in the area where they are arranged. The layer thickness of the pressure-responsive particles (preferably transparent pressure-responsive particles) on the recording medium is, for example, 0.2 μm to 25 μm, 0.4 μm to 20 μm, or 0.6 μm to 15 μm.

Examples of recording media applicable to the printing apparatus according to this embodiment include paper, coated paper (paper with a resin coating on its surface), cloth, nonwoven fabric, resin film, and resin sheet. The recording media may have images on one or both sides.

The following shows an example of a printing apparatus according to this embodiment, but this embodiment is not limited to this example.

Figure 1 is a schematic diagram showing an example of a printing apparatus according to this embodiment. The printing apparatus shown in Figure 1 comprises a placement means 100 and a crimping means 200 located downstream of the placement means 100. The arrows indicate the direction of transport of the recording medium.

The arrangement means 100 is an apparatus for arranging pressure-responsive particles on a recording medium P using pressure-responsive particles according to this embodiment. An image is pre-formed on one or both sides of the recording medium P.

The placement means 100 includes a dispensing device 110 and a fixing device 120 located downstream of the dispensing device 110.

The particle application device 110 applies pressure-responsive particles M onto the recording medium P. Examples of application methods employed by the application device 110 include spraying, bar coating, die coating, knife coating, roll coating, reverse roll coating, gravure coating, screen printing, inkjet printing, lamination, and electrophotography. Depending on the application method, pressure-responsive particles M may be dispersed in a dispersion medium to prepare a liquid composition, and this liquid composition may be applied to the application device 110.

The recording medium P to which pressure-responsive particles M have been applied by the application device 110 is then transported to the fixing device 120.

The fixing device 120 may include, for example, a heating device equipped with a heating source that heats pressure-responsive particles M on the passing recording medium P and fixes the pressure-responsive particles M on the recording medium P; a pressurizing device equipped with a pair of pressurizing members (roll/roll, belt/roll) that pressurizes the passing recording medium P and fixes the pressure-responsive particles M on the recording medium P; or a pressurizing and heating device equipped with a pair of pressurizing members (roll/roll, belt/roll) with an internal heating source that pressurizes and heats the passing recording medium P and fixes the pressure-responsive particles M on the recording medium P.

When the fixing device 120 has a heating source, the surface temperature of the recording medium P when heated by the fixing device 120 is preferably 10°C to 80°C, more preferably 20°C to 60°C, and even more preferably 30°C to 50°C.

If the fixing device 120 has a pressurizing member, the pressure applied by the pressurizing member to the recording medium P may be lower than the pressure applied by the pressurizing device 230 to the recording medium P2.

The recording medium P, upon passing through the placement means 100, becomes a recording medium P1 on which pressure-responsive particles M are imprinted on the image. The recording medium P1 is then transported toward the crimping means 200.

In the printing apparatus according to this embodiment, the placement means 100 and the crimping means 200 may be located in close proximity or at a distance from each other. When the placement means 100 and the crimping means 200 are at a distance from each other, they may be connected, for example, by a transport means (e.g., a belt conveyor) that transports the recording medium P1.

The crimping means 200 comprises a folding device 220 and a pressing device 230, and is a means for folding and crimping the recording medium P1.

The folding device 220 folds the recording medium P1 passing through the device to produce a folded recording medium P2. The folding of the recording medium P2 can be, for example, a two-fold, a three-fold, or a four-fold, and it may also be a form in which only a portion of the recording medium P2 is folded. The recording medium P2 has pressure-responsive particles M arranged on at least a portion of at least one of two opposing surfaces.

The folding device 220 may have a pair of pressurizing members (e.g., roll/roll, belt/roll) that apply pressure to the recording medium P2. The pressure applied to the recording medium P2 by the pressurizing members of the folding device 220 may be lower than the pressure applied to the recording medium P2 by the pressurizing device 230.

The crimping means 200 may include a stacking device for stacking recording medium P1 and another recording medium instead of a folding device 220. The form of stacking between recording medium P1 and the other recording medium may be, for example, one other recording medium stacked on top of recording medium P1, or one other recording medium stacked on multiple locations on recording medium P1. The other recording medium may be a recording medium with an image pre-formed on one or both sides, a recording medium without an image, or a pre-made crimped print.

The recording medium P2, having exited the folding device 220 (or stacking device), is transported toward the pressurizing device 230.

The pressurizing device 230 comprises a pair of pressurizing members (i.e., pressurizing rolls 231 and 232). The pressurizing rolls 231 and 232 contact and push against each other on their outer surfaces, applying pressure to the passing recording medium P2. The pair of pressurizing members in the pressurizing device 230 are not limited to a combination of pressurizing rolls; they may also be a combination of pressurizing rolls and a pressurizing belt, or a combination of pressurizing belts.

When pressure is applied to the recording medium P2 as it passes through the pressurizing device 230, the pressure-responsive particles M on the recording medium P2 become fluid due to the pressure and exhibit adhesive properties.

The pressurizing device 230 may or may not have an internal heat source (e.g., a halogen heater) for heating the recording medium P2. However, the absence of an internal heat source in the pressurizing device 230 does not rule out the possibility that the temperature inside the pressurizing device 230 may exceed the ambient temperature due to heat generated by the motor or other components within the device.

As the recording medium P2 passes through the pressurizing device 230, the overlapping surfaces are bonded together by the fluidized pressure-responsive particles M, thereby producing a crimped print P3. In the crimped print P3, two opposing surfaces are partially or completely bonded together.

The completed pressure-pressed printed material P3 is discharged from the pressure device 230.

The first form of the pressure-sensitive printed material P3 is a pressure-sensitive printed material in which folded recording media are bonded together on opposing surfaces by pressure-responsive particles M. This form of pressure-sensitive printed material P3 is manufactured by a printing apparatus equipped with a folding device 220.

The second form of the pressure-sensitive printed material P3 is a pressure-sensitive printed material in which multiple overlapping recording media are bonded together on opposing surfaces by pressure-responsive particles M. This form of pressure-sensitive printed material P3 is manufactured using a pressure-sensitive printed material manufacturing apparatus equipped with an overlapping device.

The printing apparatus according to this embodiment is not limited to an apparatus that continuously transports the recording medium P2 from the folding device 220 (or stacking device) to the pressurizing device 230. The printing apparatus according to this embodiment may also be an apparatus that stores the recording medium P2 after it exits the folding device 220 (or stacking device), and then transports the recording medium P2 to the pressurizing device 230 after the amount of stored recording medium P2 reaches a predetermined amount.

In the printing apparatus according to this embodiment, the folding device 220 (or stacking device) and the pressure-sealing device 230 may be located in close proximity or at a distance from each other. When the folding device 220 (or stacking device) and the pressure-sealing device 230 are at a distance from each other, they may be connected, for example, by a conveying means (e.g., a belt conveyor) for transporting the recording medium P2.

The printing apparatus according to this embodiment may include cutting means for cutting the recording medium to predetermined dimensions. Examples of cutting means include: cutting means positioned between the placement means 100 and the crimping means 200 to cut off a portion of the recording medium P1 where pressure-responsive particles M are not present; cutting means positioned between the folding device 220 and the pressing device 230 to cut off a portion of the recording medium P2 where pressure-responsive particles M are not present; cutting means positioned downstream of the crimping means 200 to cut off a portion of the crimped print P3 where it is not bonded by pressure-responsive particles M; and so on.

The printing apparatus according to this embodiment is not limited to a sheet-fed apparatus. The printing apparatus according to this embodiment may be a device that performs a placement process and a pressing process on a long recording medium to form a long pressed printed material, and then cuts the long pressed printed material to predetermined dimensions.

The printing apparatus according to this embodiment may further include a color image forming means for forming a color image on a recording medium using a colorant. Examples of color image forming means include a means for forming a color ink image on a recording medium using a colored ink as the colorant by an inkjet method, and a means for forming a color image on a recording medium using a colored electrostatic image developer by an electrophotographic method.

The manufacturing apparatus with the above configuration enables the manufacturing method for printed materials according to this embodiment, further including a color image formation step of forming a colored image on a recording medium using a colorant. Specifically, the color image formation step may include, for example, a step of forming a colored ink image on a recording medium using a colored ink as the colorant by an inkjet method, or a step of forming a colored image on a recording medium using a colored electrostatic image developer by an electrophotographic method.

As a means for forming a colored image, an inkjet-type colored image forming means will be described with reference to the drawings. Figure 2 shows an inkjet recording device 400, which is an example of an embodiment of the inkjet method. The inkjet recording device 400 is installed, for example, upstream of the placement means 100 in the printing apparatus shown in Figure 1.

The inkjet recording device 400 comprises, within its housing 40, a container 42 for housing the recording medium P before image recording, an endless conveyor belt 50 stretched over a drive roll 52 and a driven roll 54, ink ejection heads 30Y, 30M, 30C, and 30K (collectively referred to as ink ejection heads 30), drying means 34Y, 34M, 34C, and 34K (collectively referred to as drying means 34), and a container 66 for housing the recording medium P after image recording.

The space between the container 42 and the conveyor belt 50 is a conveyor path 44 through which the recording medium P is transported before image recording. The conveyor path 44 includes a roll 46 for removing the recording medium P one by one from the container 42, and multiple pairs of rolls 48 for transporting the recording medium P. A charged roll 56 is positioned upstream of the conveyor belt 50. The charged roll 56 moves while sandwiching the conveyor belt 50 and the recording medium P between itself and a driven roll 54, creating a potential difference between the charged roll 56 and the grounded driven roll 54, thereby imparting charge to the recording medium P and causing it to electrostatically adhere to the conveyor belt 50.

The ink ejection head 30 is positioned above the conveyor belt 50, facing the flat portion of the conveyor belt 50. The area where the ink ejection head 30 and the conveyor belt 50 face each other is the area where ink droplets are ejected from the ink ejection head 30.

The ink ejection heads 30Y, 30M, 30C, and 30K are, respectively, heads for recording yellow (Y) images, magenta (M) images, cyan (C) images, and black (K) images. The ink ejection heads 30Y, 30M, 30C, and 30K are arranged, for example, in this order from the upstream to the downstream side of the transport belt 50. Each of the ink ejection heads 30Y, 30M, 30C, and 30K is connected to the respective color ink cartridges 32Y, 32M, 32C, and 32K, which are attached to and detached from the inkjet recording device 400, via supply pipes (not shown), and ink of each color is supplied from the ink cartridges to the ink ejection heads.

Examples of the ink ejection head 30 include a long head whose effective recording area (the area where the ink ejection nozzles are arranged) is greater than or equal to the width of the recording medium P (the length in the direction perpendicular to the transport direction of the recording medium P); and a short head whose effective recording area is shorter than the width of the recording medium P, and which is a carriage-type head that moves in the width direction of the recording medium P to eject ink.

Examples of inkjet methods employed by the ink ejection head 30 include: a piezoelectric method that utilizes the vibration pressure of a piezoelectric element; a charge control method that ejects ink using electrostatic attraction; an acoustic inkjet method that converts electrical signals into an acoustic beam, irradiates the ink with it, and ejects the ink using the resulting radiation pressure; and a thermal inkjet method that heats the ink to form bubbles and utilizes the resulting pressure.

The ink ejection head 30 is, for example, a low-resolution recording head (e.g., a 600 dpi recording head) that ejects ink droplets in the range of 10 pL to 15 pL, and a high-resolution recording head (e.g., a 1200 dpi recording head) that ejects ink droplets in the range of less than 10 pL. dpi stands for "dots per inch".

The inkjet recording device 400 is not limited to a configuration with four ink ejection heads. The inkjet recording device 400 may have four or more ink ejection heads, including intermediate colors in addition to YMCK; or it may have one ink ejection head and record an image of only one color.

Downstream of the ink ejection head 30, above the conveyor belt 50, drying means 34Y, 60M, 60C, and 60K are arranged for each ink ejection head of each color. Examples of drying means 34 include contact heating means and hot air blowing means. The inkjet recording device 400 is not limited to having a drying means for each ink ejection head of each color; it may also have only one drying means downstream of the furthest downstream ink ejection head.

Downstream of the drying means 34, a release plate 58 is positioned opposite the drive roll 52. The release plate 58 separates the recording medium P from the conveyor belt 50.

The space between the conveyor belt 50 and the container 66 is a conveyor path 62 through which the recording medium P is transported after image recording. Multiple pairs of rolls 64 for transporting the recording medium P are arranged in the conveyor path 62.

The operation of the inkjet recording device 400 will be explained.
Before image recording, the recording media P are removed one by one from the container 42 by a roll 46 and transported to the conveyor belt 50 by a plurality of roll pairs 48. Next, the recording media P are electrostatically attracted to the conveyor belt 50 by a charged roll 56 and transported below the ink ejection head 30 by the rotation of the conveyor belt 50. Next, ink is ejected onto the recording media P from the ink ejection head 30 and an image is recorded. Next, the ink on the recording media P is dried by the drying means 34. Finally, the recording media P, with the ink dried and the image fixed, is peeled off the conveyor belt 50 by a release plate 58 and transported to the container 66 by a plurality of roll pairs 64.

<Sheets for printing, methods for manufacturing printed materials>
The printed material manufacturing sheet according to this embodiment comprises a substrate and pressure-responsive particles disposed on the substrate. The printed material manufacturing sheet according to this embodiment is manufactured using the pressure-responsive particles according to this embodiment. The pressure-responsive particles on the substrate may or may not retain the particle shape they had before being placed on the substrate.

The printing sheet according to this embodiment is applicable, for example, to a masking sheet that is bonded to a recording medium when it is desired to conceal the information recorded on the recording medium; or to a release sheet used to provide an adhesive layer on a recording medium when bonding multiple recording media together.

Examples of substrates applicable to the printed material manufacturing sheet according to this embodiment include paper, coated paper (paper surface coated with resin, etc.), cloth, nonwoven fabric, resin film, and resin sheet. The substrate may have an image formed on one or both sides.

In the printed material manufacturing sheet according to this embodiment, the pressure-responsive particles may be arranged across the entire surface of the substrate or on a portion of the substrate. The pressure-responsive particles are arranged in one or more layers on the substrate. The layers of pressure-responsive particles may be continuous in the planar direction of the substrate or discontinuous in the planar direction of the substrate. The layers of pressure-responsive particles may be layers where the pressure-responsive particles are arranged as individual particles, or layers where adjacent pressure-responsive particles are fused together.

The amount of pressure-responsive particles on the substrate is, for example, 0.5 g/ ^m² to 50 g/ ^m² , 1 g/ ^m² to 40 g/ ^m² , or 1.5 g/ ^m² to 30 g/ ^m² in the area where they are placed. The layer thickness of the pressure-responsive particles on the substrate is, for example, 0.2 μm to 25 μm, 0.4 μm to 20 μm, or 0.6 μm to 15 μm.

The printed material manufacturing sheet according to this embodiment is manufactured, for example, by a manufacturing method that uses pressure-responsive particles according to this embodiment and includes a placement step of arranging the pressure-responsive particles on a substrate.

The placement process may include, for example, a placement step of applying pressure-responsive particles onto the substrate, and further, a fixing step of fixing the pressure-responsive particles applied to the substrate onto the substrate.

The application process can be implemented by application methods such as spraying, bar coating, die coating, knife coating, roll coating, reverse roll coating, gravure coating, screen printing, inkjet printing, lamination, or electrophotography. Depending on the application method, pressure-responsive particles may be dispersed in a dispersion medium to prepare a liquid composition, and this liquid composition may be applied to the application process.

The fixing process includes, for example, a heating process in which pressure-responsive particles on a substrate are heated with a heat source to fix the pressure-responsive particles on the substrate; a pressurizing process in which the substrate to which the pressure-responsive particles have been applied is pressurized with a pair of pressurizing members (roll/roll, belt/roll) to fix the pressure-responsive particles on the substrate; and a pressurizing and heating process in which the substrate to which the pressure-responsive particles have been applied is pressurized and heated with a pair of pressurizing members (roll/roll, belt/roll) equipped with an internal heat source to fix the pressure-responsive particles on the substrate.

<Manufacturing of printed materials using electrophotography>
An example of an embodiment in which the pressure-responsive particles according to this embodiment are applied to an electrophotographic system will be described. In the electrophotographic system, the pressure-responsive particles are used as a toner for developing electrostatic images (also simply referred to as "toner").

[Electrostatic Image Developer]
The electrostatic image developer (also simply referred to as "developer") according to this embodiment contains at least the pressure-responsive particles according to this embodiment. The electrostatic image developer according to this embodiment may be a one-component developer containing only the pressure-responsive particles according to this embodiment, or it may be a two-component developer in which the pressure-responsive particles according to this embodiment and a carrier are mixed.

There are no particular restrictions on the carriers used; known carriers can be used. Examples of carriers include coated carriers, where a resin coating is applied to the surface of a core material made of magnetic powder; magnetic powder dispersed carriers, where magnetic powder is dispersed and blended in a matrix resin; and resin-impregnated carriers, where resin is impregnated into porous magnetic powder. In the case of magnetic powder dispersed carriers and resin-impregnated carriers, the constituent particles of the carrier may be used as the core material, with the surface coated with resin.

Examples of magnetic powders include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

Examples of coating resins and matrix resins include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resins or modified products thereof containing organosiloxane bonds, fluororesins, polyesters, polycarbonates, phenolic resins, epoxy resins, etc. The coating resin and matrix resin may also contain conductive particles and other additives. Examples of conductive particles include metals such as gold, silver, and copper, carbon black, titanium dioxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

To coat the surface of the core material with resin, one method is to coat it with a coating layer-forming solution prepared by dissolving a coating resin and various additives (used as needed) in a suitable solvent. The solvent is not particularly limited and should be selected considering the type of resin used and its suitability for coating.
Specific resin coating methods include the immersion method, in which the core material is immersed in a coating layer forming solution; the spray method, in which the coating layer forming solution is sprayed onto the surface of the core material; the fluidized bed method, in which the coating layer forming solution is sprayed onto the core material while it is suspended by fluidized air; and the kneader coater method, in which the carrier core material and the coating layer forming solution are mixed in a kneader coater, and then the solvent is removed.

In a two-component developer, the mixing ratio (mass ratio) of pressure-responsive particles to carriers is preferably 1:100 to 30:100, and more preferably 3:100 to 20:100.

[Printing equipment, printing method]
A printing apparatus applying an electrophotographic method includes a placement means for containing a developer containing pressure-responsive particles according to this embodiment and arranging the pressure-responsive particles on a recording medium by an electrophotographic method, and a crimping means for folding and crimping the recording medium, or for crimping the recording medium with another recording medium.

The printing apparatus according to this embodiment enables the manufacturing of printed materials using an electrophotographic method. The manufacturing method according to this embodiment includes a placement step of placing pressure-responsive particles on a recording medium using an electrophotographic method with a developer containing the pressure-responsive particles according to this embodiment, and a pressing step of folding and pressing the recording medium, or pressing the recording medium with another recording medium.

The arrangement means included in the printing apparatus according to this embodiment is, for example,
Photoreceptor and
A charging means for charging the surface of the photoreceptor,
A means for forming an electrostatic image on the surface of the charged photoreceptor,
A developing means containing an electrostatic image developer according to this embodiment, which develops the electrostatic image formed on the surface of the photoreceptor as a pressure-responsive particle-granting part using the electrostatic image developer,
A transfer means for transferring the pressure-responsive particle-granting portion formed on the surface of the photoreceptor to the surface of the recording medium,
It is equipped with.
Preferably, the arrangement means further includes fixing means for fixing the pressure-responsive particle-applying portion transferred to the surface of the recording medium.

The arrangement step included in the method for manufacturing printed materials according to this embodiment is, for example,
A charging process in which the surface of the photoreceptor is charged,
A step of forming an electrostatic image on the surface of the charged photoreceptor,
The development step of developing the electrostatic image formed on the surface of the photoreceptor as a pressure-responsive particle-granting section using the electrostatic image developer according to this embodiment,
A transfer step of transferring the pressure-responsive particle-granting portion formed on the surface of the photoreceptor to the surface of the recording medium,
Includes.
The arrangement step preferably further includes a fixing step of fixing the pressure-responsive particle-imparting portion transferred to the surface of the recording medium.

The arrangement means is, for example, a direct transfer device that directly transfers a pressure-responsive particle-granulating portion formed on the surface of a photoreceptor to a recording medium; an intermediate transfer device that first transfers the pressure-responsive particle-granulating portion formed on the surface of a photoreceptor to the surface of an intermediate transfer body, and then secondarily transfers the pressure-responsive particle-granulating portion transferred to the surface of the intermediate transfer body to the surface of a recording medium; a device equipped with cleaning means for cleaning the surface of the photoreceptor after the transfer of the pressure-responsive particle-granulating portion and before charging; a device equipped with static elimination means for irradiating the surface of the photoreceptor with static elimination light to eliminate static charge after the transfer of the pressure-responsive particle-granulating portion and before charging; and so on. In the case of an intermediate transfer device, the transfer means includes, for example, an intermediate transfer body on which the pressure-responsive particle-granulating portion is transferred; a primary transfer means for first transferring the pressure-responsive particle-granulating portion formed on the surface of the photoreceptor to the surface of the intermediate transfer body; and a secondary transfer means for secondarily transferring the pressure-responsive particle-granulating portion transferred to the surface of the intermediate transfer body to the surface of a recording medium.

The aforementioned arrangement means may be a cartridge structure (a so-called process cartridge) in which the developing means is attached to and detached from the arrangement means. As the process cartridge, for example, a process cartridge containing the electrostatic image developer according to this embodiment and equipped with a developing means is preferably used.

The crimping means included in the printing apparatus according to this embodiment applies pressure to the recording medium on which the pressure-responsive particles according to this embodiment are arranged. This causes the pressure-responsive particles according to this embodiment to fluidize on the recording medium and exhibit adhesive properties. The pressure applied by the crimping means to the recording medium for the purpose of fluidizing the pressure-responsive particles according to this embodiment is preferably 3 MPa to 300 MPa, more preferably 10 MPa to 200 MPa, and even more preferably 30 MPa to 150 MPa.

The pressure-responsive particles according to this embodiment may be arranged across the entire surface of the recording medium or on a portion of it. One or more layers of pressure-responsive particles according to this embodiment are arranged on the recording medium. The layers of pressure-responsive particles according to this embodiment may be continuous in the planar direction of the recording medium or discontinuous in the planar direction of the recording medium. The layers of pressure-responsive particles according to this embodiment may be layers where the pressure-responsive particles are arranged as individual particles, or layers where adjacent pressure-responsive particles are fused together.

The amount of pressure-responsive particles (preferably transparent pressure-responsive particles) according to this embodiment on the recording medium is, for example, 0.5 g/ ^m² to 50 g/ ^m² , 1 g/ ^m² to 40 g/ ^m² , or 1.5 g/ ^m² to 30 g/ ^m² in the area where they are arranged. The layer thickness of the pressure-responsive particles (preferably transparent pressure-responsive particles) according to this embodiment on the recording medium is, for example, 0.2 μm to 25 μm, 0.4 μm to 20 μm, or 0.6 μm to 15 μm.

Examples of recording media applicable to the printing apparatus according to this embodiment include paper, coated paper (paper with a resin coating on its surface), cloth, nonwoven fabric, resin film, and resin sheet. The recording media may have images on one or both sides.

The following shows an example of a printing apparatus according to this embodiment that applies the electrophotographic method, but this embodiment is not limited to this example.

Figure 3 is a schematic diagram showing an example of a printing apparatus according to this embodiment. The printing apparatus shown in Figure 3 comprises a placement means 100 and a crimping means 200 located downstream of the placement means 100. The arrows indicate the rotation direction of the photoreceptor or the transport direction of the recording medium.

The placement means 100 is a direct transfer apparatus that uses a developer containing the pressure-responsive particles according to this embodiment to place the pressure-responsive particles on the recording medium P using an electrophotographic method. The recording medium P has an image pre-formed on one or both sides.

The arrangement means 100 includes a photoreceptor 101. Around the photoreceptor 101, the following are arranged in order: a charging roll (an example of a charging means) 102 for charging the surface of the photoreceptor 101; an exposure device (an example of a static charge image forming means) 103 for exposing the charged surface of the photoreceptor 101 with a laser beam to form a static charge image; a developing device (an example of a developing means) 104 for developing the static charge image by supplying pressure-responsive particles to it; a transfer roll (an example of a transfer means) 105 for transferring the developed pressure-responsive particle application area onto the recording medium P; and a photoreceptor cleaning device (an example of a cleaning means) 106 for removing pressure-responsive particles remaining on the surface of the photoreceptor 101 after transfer.

The operation by which the placement means 100 places the pressure-responsive particles according to this embodiment onto the recording medium P will be described.
First, the surface of the photoreceptor 101 is charged by the charging roll 102. The exposure apparatus 103 irradiates the charged surface of the photoreceptor 101 with a laser beam according to image data sent from a control unit (not shown). As a result, an electrostatic charge image of the arrangement pattern of pressure-responsive particles according to this embodiment is formed on the surface of the photoreceptor 101.

The electrostatic charge image formed on the photoreceptor 101 rotates as the photoreceptor 101 moves to the development position. At the development position, the electrostatic charge image on the photoreceptor 101 is developed by the development device 104, becoming a pressure-responsive particle-adding section.

The developing device 104 contains a developer containing at least the pressure-responsive particles and carriers according to this embodiment. The pressure-responsive particles according to this embodiment are triboelectrically charged by agitation with the carriers inside the developing device 104 and are held on the developer roll. As the surface of the photoreceptor 101 passes through the developing device 104, the pressure-responsive particles electrostatically adhere to the electrostatic charge image on the surface of the photoreceptor 101, and the electrostatic charge image is developed by the pressure-responsive particles. The photoreceptor 101, with the pressure-responsive particle application section formed thereon, continues to move, and the pressure-responsive particle application section on the photoreceptor 101 is transported to the transfer position.

When the pressure-responsive particle application area on the photoreceptor 101 is transported to the transfer position, a transfer bias is applied to the transfer roll 105. An electrostatic force from the photoreceptor 101 towards the transfer roll 105 acts on the pressure-responsive particle application area, transferring the pressure-responsive particle application area from the photoreceptor 101 onto the recording medium P.

Pressure-responsive particles remaining on the photoreceptor 101 are removed and recovered by the photoreceptor cleaning device 106. The photoreceptor cleaning device 106 is, for example, a cleaning blade or a cleaning brush. From the viewpoint of suppressing the phenomenon where pressure-responsive particles remaining on the surface of the photoreceptor according to this embodiment become fluid due to pressure and adhere to the surface of the photoreceptor in a film-like manner, the photoreceptor cleaning device 106 is preferably a cleaning brush.

The recording medium P to which the pressure-responsive particle application unit has been transferred is transported to a fixing device (an example of a fixing means) 107. The fixing device 107 is, for example, a pair of fixing members (roll/roll, belt/roll). The placement means 100 does not necessarily have to include the fixing device 107, but it is preferable to include the fixing device 107 from the viewpoint of suppressing the detachment of the pressure-responsive particles according to this embodiment from the recording medium P. The pressure applied to the recording medium P by the fixing device 107 may be lower than the pressure applied to the recording medium P2 by the pressurizing device 230, and specifically, 0.2 MPa to 1 MPa is preferable.

The fixing device 107 may or may not have an internal heating source (e.g., a halogen heater) for heating the recording medium P. If the fixing device 107 has an internal heating source, the surface temperature of the recording medium P when heated by the heating source is preferably 150°C to 220°C, more preferably 155°C to 210°C, and even more preferably 160°C to 200°C. Note that the absence of an internal heating source in the fixing device 107 does not rule out the possibility that the temperature inside the fixing device 107 may exceed the ambient temperature due to heat generated by the motor or other components of the placement means 100.

The recording medium P, upon passing through the placement means 100, becomes a recording medium P1 on which pressure-responsive particles according to this embodiment are imprinted on the image. The recording medium P1 is then transported toward the crimping means 200.

In the printing apparatus according to this embodiment, the placement means 100 and the crimping means 200 may be located in close proximity or at a distance from each other. When the placement means 100 and the crimping means 200 are at a distance from each other, they may be connected, for example, by a transport means (e.g., a belt conveyor) that transports the recording medium P1.

The crimping means 200 comprises a folding device 220 and a pressing device 230, and is a means for folding and crimping the recording medium P1.

The folding device 220 folds the recording medium P1 passing through the device to produce a folded recording medium P2. The folding of the recording medium P2 can be, for example, a two-fold, a three-fold, or a four-fold, and it may also be a form in which only a portion of the recording medium P2 is folded. The recording medium P2 is in a state where the pressure-responsive particles according to this embodiment are arranged on at least a portion of at least one of two opposing surfaces.

The folding device 220 may have a pair of pressurizing members (e.g., roll/roll, belt/roll) that apply pressure to the recording medium P2. The pressure applied to the recording medium P2 by the pressurizing members of the folding device 220 may be lower than the pressure applied to the recording medium P2 by the pressurizing device 230; specifically, 1 MPa to 10 MPa is preferred.

The crimping means 200 may include a stacking device for stacking recording medium P1 and another recording medium instead of a folding device 220. The form of stacking between recording medium P1 and the other recording medium may be, for example, one other recording medium stacked on top of recording medium P1, or one other recording medium stacked on multiple locations on recording medium P1. The other recording medium may be a recording medium with an image pre-formed on one or both sides, a recording medium without an image, or a pre-made crimped print.

The recording medium P2, having exited the folding device 220 (or stacking device), is transported toward the pressurizing device 230.

The pressurizing device 230 comprises a pair of pressurizing members (i.e., pressurizing rolls 231 and 232). The pressurizing rolls 231 and 232 contact and push against each other on their outer surfaces, applying pressure to the passing recording medium P2. The pair of pressurizing members in the pressurizing device 230 are not limited to a combination of pressurizing rolls; they may also be a combination of pressurizing rolls and a pressurizing belt, or a combination of pressurizing belts.

When pressure is applied to the recording medium P2 passing through the pressurizing device 230, the pressure-responsive particles according to this embodiment become fluid due to the pressure and exhibit adhesive properties on the recording medium P2. The pressure applied to the recording medium P2 by the pressurizing device 230 is preferably 3 MPa to 300 MPa, more preferably 10 MPa to 200 MPa, and even more preferably 30 MPa to 150 MPa.

The pressurizing device 230 may or may not have an internal heat source (e.g., a halogen heater) for heating the recording medium P2. If the pressurizing device 230 has an internal heat source, the surface temperature of the recording medium P2 when heated by the heat source is preferably 30°C to 120°C, more preferably 40°C to 100°C, and even more preferably 50°C to 90°C. Note that the absence of an internal heat source in the pressurizing device 230 does not rule out the possibility that the temperature inside the pressurizing device 230 may exceed the ambient temperature due to heat generated by the motor or other components within the pressurizing device 230.

As the recording medium P2 passes through the pressurizing device 230, the overlapping surfaces are bonded together by the pressure-responsive particles of this embodiment, which have been fluidized, thereby producing a crimped printed material P3. The crimped printed material P3 has opposing surfaces that are partially or completely bonded together.

The completed pressure-pressed printed material P3 is discharged from the pressure device 230.

The first embodiment of the pressure-sensitive printed material P3 is a pressure-sensitive printed material in which folded recording media are bonded together on opposing surfaces by pressure-responsive particles according to this embodiment. The pressure-sensitive printed material P3 of this embodiment is manufactured by a printing apparatus equipped with a folding device 220.

A second embodiment of the pressure-sensitive printed material P3 is a pressure-sensitive printed material in which multiple overlapping recording media are bonded together on opposing surfaces by pressure-responsive particles according to this embodiment. The pressure-sensitive printed material P3 of this embodiment is manufactured by a pressure-sensitive printed material manufacturing apparatus equipped with an overlapping device.

The printing apparatus according to this embodiment is not limited to an apparatus that continuously transports the recording medium P2 from the folding device 220 (or stacking device) to the pressurizing device 230. The printing apparatus according to this embodiment may also be an apparatus that stores the recording medium P2 after it exits the folding device 220 (or stacking device), and then transports the recording medium P2 to the pressurizing device 230 after the amount of stored recording medium P2 reaches a predetermined amount.

In the printing apparatus according to this embodiment, the folding device 220 (or stacking device) and the pressure-sealing device 230 may be located in close proximity or at a distance from each other. When the folding device 220 (or stacking device) and the pressure-sealing device 230 are at a distance from each other, they may be connected, for example, by a conveying means (e.g., a belt conveyor) for transporting the recording medium P2.

The printing apparatus according to this embodiment may include cutting means for cutting the recording medium to predetermined dimensions. Examples of cutting means include: cutting means positioned between the placement means 100 and the crimping means 200 to cut off a portion of the recording medium P1 where the pressure-responsive particles according to this embodiment are not present; cutting means positioned between the folding device 220 and the pressing device 230 to cut off a portion of the recording medium P2 where the pressure-responsive particles according to this embodiment are not present; cutting means positioned downstream of the crimping means 200 to cut off a portion of the crimped print P3 where it is not bonded by the pressure-responsive particles according to this embodiment; and so on.

The printing apparatus according to this embodiment is not limited to a sheet-fed apparatus. The printing apparatus according to this embodiment may be a device that performs a placement process and a pressing process on a long recording medium to form a long pressed printed material, and then cuts the long pressed printed material to predetermined dimensions.

The printing apparatus according to this embodiment may further include a color image forming means for forming a color image on a recording medium by an electrophotographic method using a colored electrostatic image developer. The color image forming means is, for example,
Photoreceptor and
A charging means for charging the surface of the photoreceptor,
A means for forming an electrostatic image on the surface of the charged photoreceptor,
A developing means containing a colored electrostatic image developer, which develops the electrostatic image formed on the surface of the photoreceptor as a colored toner image using the colored electrostatic image developer,
A transfer means for transferring a colored toner image formed on the surface of the photoreceptor to the surface of a recording medium,
The system includes a thermal fixing means for thermally fixing a colored toner image transferred to the surface of the recording medium.

The manufacturing apparatus with the above configuration enables the manufacturing method for printed materials according to this embodiment, further comprising a color image forming step of forming a color image on a recording medium by an electrophotographic method using a colored electrostatic image developer. Specifically, the color image forming step is:
A charging process in which the surface of the photoreceptor is charged,
A step of forming an electrostatic image on the surface of the charged photoreceptor,
A developing step in which a static charge image formed on the surface of the photoreceptor is developed as a colored toner image using a colored electrostatic image developer,
A transfer step of transferring a colored toner image formed on the surface of the photoreceptor to the surface of a recording medium,
The process includes a thermal fixing step of thermally fixing a colored toner image transferred to the surface of the recording medium.

The color image forming means included in the printing apparatus according to this embodiment is, for example, a direct transfer apparatus that directly transfers a color toner image formed on the surface of a photoreceptor to a recording medium; an intermediate transfer apparatus that first transfers the color toner image formed on the surface of a photoreceptor to the surface of an intermediate transfer body, and then secondarily transfers the color toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium; an apparatus equipped with cleaning means for cleaning the surface of the photoreceptor before charging after the transfer of the color toner image; an apparatus equipped with static elimination means for irradiating the surface of the photoreceptor with static elimination light before charging after the transfer of the color toner image; and so on. In the case of an intermediate transfer apparatus, the transfer means includes, for example, an intermediate transfer body on which a color toner image is transferred; a primary transfer means for first transferring the color toner image formed on the surface of the photoreceptor to the surface of the intermediate transfer body; and a secondary transfer means for secondarily transferring the color toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

In the printing apparatus according to this embodiment, if the placement means for the developer containing pressure-responsive particles according to this embodiment and the colored image forming means employ an intermediate transfer method, the placement means and the colored image forming means may share an intermediate transfer body and a secondary transfer means.

In the printing apparatus according to this embodiment, the means for arranging the image developer containing pressure-responsive particles according to this embodiment and the means for forming a colored image may share a heat fixing means.

The following describes an example of a printing apparatus according to this embodiment, equipped with a color image forming means; however, this embodiment is not limited to this example. In the following description, only the main parts shown in the figures will be described; other parts will be omitted.

Figure 4 is a schematic diagram showing an example of a printing apparatus according to this embodiment, applying an electrophotographic method. The printing apparatus shown in Figure 4 comprises a printing means 300 that simultaneously arranges pressure-responsive particles according to this embodiment onto a recording medium and forms a colored image, and a pressing means 200 located downstream of the printing means 300.

The printing means 300 is a five-tandem and intermediate transfer printing means. The printing means 300 comprises a unit 10T for arranging the pressure-responsive particles (T) according to this embodiment, and units 10Y, 10M, 10C, and 10K for forming yellow (Y), magenta (M), cyan (C), and black (K) color images. Unit 10T is an arrangement means for arranging the pressure-responsive particles according to this embodiment on the recording medium P using a developer containing the pressure-responsive particles according to this embodiment. Units 10Y, 10M, 10C, and 10K are means for forming colored images on the recording medium P using a developer containing colored toner. Units 10T, 10Y, 10M, 10C, and 10K employ an electrophotographic method.

Units 10T, 10Y, 10M, 10C, and 10K are arranged side by side, spaced apart from each other in the horizontal direction. Units 10T, 10Y, 10M, 10C, and 10K may also be process cartridges that can be attached to and detached from the printing means 300.

Below units 10T, 10Y, 10M, 10C, and 10K, an intermediate transfer belt (an example of an intermediate transfer body) 20 extends through each unit. The intermediate transfer belt 20 is wound around a drive roll 22, a support roll 23, and an opposing roll 24, which are in contact with the inner surface of the intermediate transfer belt 20, and travels in the direction from unit 10T to unit 10K. An intermediate transfer body cleaning device 21 is provided on the image-holding surface side of the intermediate transfer belt 20, opposite the drive roll 22.

Units 10T, 10Y, 10M, 10C, and 10K are each equipped with developing devices (examples of developing means) 4T, 4Y, 4M, 4C, and 4K, respectively. Each of the developing devices 4T, 4Y, 4M, 4C, and 4K is supplied with pressure-responsive particles according to this embodiment, contained in a pressure-responsive particle cartridge 8T, or yellow toner, magenta toner, cyan toner, and black toner, contained in toner cartridges 8Y, 8M, 8C, and 8K.

Since units 10T, 10Y, 10M, 10C, and 10K have equivalent configurations and operations, unit 10T, which arranges the pressure-responsive particles on the recording medium according to this embodiment, will be described as representative.

Unit 10T has a photoreceptor 1T. Around the photoreceptor 1T, the following are arranged in order: a charging roll (an example of a charging means) 2T for charging the surface of the photoreceptor 1T; an exposure device (an example of a static charge image forming means) 3T for exposing the charged surface of the photoreceptor 1T with a laser beam to form a static charge image; a developing device (an example of a developing means) 4T for developing the static charge image by supplying pressure-responsive particles to it; a primary transfer roll (an example of a primary transfer means) 5T for transferring the developed pressure-responsive particle application section onto the intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning means) 6T for removing pressure-responsive particles remaining on the surface of the photoreceptor 1T after primary transfer. The primary transfer roll 5T is positioned inside the intermediate transfer belt 20 and opposite the photoreceptor 1T.

The following describes the operation of arranging pressure-responsive particles according to this embodiment and forming a colored image on the recording medium P, with the operation of unit 10T as an example.
First, the surface of the photoreceptor 1T is charged by the charging roll 2T. The exposure apparatus 3T irradiates the charged surface of the photoreceptor 1T with a laser beam according to image data sent from a control unit (not shown). As a result, an electrostatic charge image of the arrangement pattern of pressure-responsive particles according to this embodiment is formed on the surface of the photoreceptor 1T.

The electrostatic charge image formed on the photoreceptor 1T rotates as the photoreceptor 1T moves to the development position. At the development position, the electrostatic charge image on the photoreceptor 1T is developed by the development device 4T, becoming a pressure-responsive particle application section.

The developing apparatus 4T contains a developer containing at least the pressure-responsive particles and carriers according to this embodiment. The pressure-responsive particles according to this embodiment are triboelectrically charged by agitation with the carriers inside the developing apparatus 4T and are held on the developer roll. As the surface of the photoreceptor 1T passes through the developing apparatus 4T, the pressure-responsive particles electrostatically adhere to the electrostatic charge image on the surface of the photoreceptor 1T, and the electrostatic charge image is developed by the pressure-responsive particles. The photoreceptor 1T, with the pressure-responsive particle application section formed thereon, continues to move, and the pressure-responsive particle application section on the photoreceptor 1T is transported to the primary transfer position.

When the pressure-responsive particle application area on the photoreceptor 1T is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5T. An electrostatic force acts on the pressure-responsive particle application area from the photoreceptor 1T toward the primary transfer roll 5T, transferring the pressure-responsive particle application area from the photoreceptor 1T onto the intermediate transfer belt 20. The pressure-responsive particles remaining on the photoreceptor 1T are removed and recovered by the photoreceptor cleaning device 6T. The photoreceptor cleaning device 6T is, for example, a cleaning blade, a cleaning brush, etc., and a cleaning brush is preferred.

In units 10Y, 10M, 10C, and 10K, the same operation as in unit 10T is performed using a developer containing colored toner. The intermediate transfer belt 20, onto which the pressure-responsive particle application section was transferred in unit 10T, sequentially passes through units 10Y, 10M, 10C, and 10K, and multiple toner images of each color are transferred onto the intermediate transfer belt 20.

The intermediate transfer belt 20, through units 10T, 10Y, 10M, 10C, and 10K, onto which the pressure-responsive particle application unit and toner image have been multiple-transferred, proceeds to a secondary transfer unit composed of the intermediate transfer belt 20, a counter roll 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer means) 26 positioned on the image-holding side of the intermediate transfer belt 20. Meanwhile, the recording medium P is fed via a supply mechanism into the gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact, and a secondary transfer bias is applied to the counter roll 24. At this time, an electrostatic force from the intermediate transfer belt 20 toward the recording medium P acts on the pressure-responsive particle application unit and toner image, transferring the pressure-responsive particle application unit and toner image from the intermediate transfer belt 20 onto the recording medium P.

The pressure-responsive particle application unit and the recording medium P onto which the toner image has been transferred are transported to a thermal fixing device (an example of a thermal fixing means) 28. The thermal fixing device 28 is equipped with a heating source such as a halogen heater and heats the recording medium P. The surface temperature of the recording medium P when heated by the thermal fixing device 28 is preferably 150°C to 220°C, more preferably 155°C to 210°C, and even more preferably 160°C to 200°C. By passing through the thermal fixing device 28, the colored toner image is thermally fixed onto the recording medium P.

The thermal fixing device 28 is preferably a device that applies heat and pressure simultaneously, from the viewpoint of suppressing the detachment of pressure-responsive particles according to this embodiment from the recording medium P and from the viewpoint of improving the fixation of colored images to the recording medium P. For example, it may be a pair of fixing members (roll/roll, belt/roll) equipped with a heating source inside. When the thermal fixing device 28 applies pressure, the pressure applied by the thermal fixing device 28 to the recording medium P may be lower than the pressure applied by the pressurizing device 230 to the recording medium P2, and specifically, 0.2 MPa to 1 MPa is preferred.

The recording medium P, upon passing through the printing means 300, becomes a recording medium P1 onto which a colored image and pressure-responsive particles according to this embodiment are imprinted. The recording medium P1 is then transported toward the crimping means 200.

The configuration of the crimping mechanism 200 in Figure 4 is the same as that of the crimping mechanism 200 in Figure 3, and a detailed explanation of the configuration and operation of the crimping mechanism 200 is omitted.

In the printing apparatus according to this embodiment, the printing means 300 and the crimping means 200 may be located in close proximity or separated from each other. When the printing means 300 and the crimping means 200 are separated, they are connected, for example, by a conveying means (e.g., a belt conveyor) that transports the recording medium P1.

The printing apparatus according to this embodiment may include cutting means for cutting the recording medium to predetermined dimensions. Examples of cutting means include: cutting means positioned between the printing means 300 and the crimping means 200 to cut off a portion of the recording medium P1 where the pressure-responsive particles according to this embodiment are not present; cutting means positioned between the folding device 220 and the pressing device 230 to cut off a portion of the recording medium P2 where the pressure-responsive particles according to this embodiment are not present; cutting means positioned downstream of the crimping means 200 to cut off a portion of the crimped printed material P3 where it is not bonded by the pressure-responsive particles according to this embodiment; and so on.

The printing apparatus according to this embodiment is not limited to a sheet-fed apparatus. The printing apparatus according to this embodiment may be a type of apparatus that performs a color image formation process, a placement process, and a pressure pressing process on a long recording medium to form a long pressure-pressed printed material, and then cuts the long pressure-pressed printed material to predetermined dimensions.

[Process Cartridge]
This document describes a process cartridge for use in electrophotographic printing equipment.
The process cartridge according to this embodiment contains the electrostatic image developer according to this embodiment and includes a developing means for developing the electrostatic image formed on the surface of the photoreceptor as a pressure-responsive particle-granting unit using the electrostatic image developer, and is a process cartridge that can be attached to and detached from a printing apparatus.

The process cartridge according to this embodiment may comprise a developing means and, if necessary, at least one selected from a photoreceptor, charging means, electrostatic image forming means, transfer means, etc.

An example of a process cartridge embodiment is a cartridge in which a photoreceptor, a charging roll (an example of a charging means) provided around the photoreceptor, a developing device (an example of a developing means), and a photoreceptor cleaning device (an example of a cleaning means) are integrated by a housing. The housing has an opening for exposure. The housing has a mounting rail, and the process cartridge is mounted on a printing production apparatus via the mounting rail.

The embodiments of the invention will be described in detail below with reference to examples, but the embodiments of the invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" refer to mass.

<Preparation of a dispersion containing styrene-based resin particles>
[Preparation of Styrene-based resin particle dispersion (St1)]
A monomer solution was prepared by mixing and dissolving the following materials: 390 parts styrene, 100 parts n-butyl acrylate, 10 parts acrylic acid, and 7.5 parts dodecanethiol.
Eight parts of an anionic surfactant (Dowfax 2A1, manufactured by Dow Chemical) were dissolved in 205 parts of deionized water, and the monomer solution was added to disperse and emulsify it to obtain an emulsion.
2.2 parts of anionic surfactant (Dowfax 2A1, manufactured by Dow Chemical) were dissolved in 462 parts of deionized water. This mixture was then placed in a polymerization flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, and heated to 73°C while stirring, and the temperature was maintained there.
Three parts of ammonium persulfate were dissolved in 21 parts of deionized water and added dropwise to the polymerization flask via a metering pump over 15 minutes. The emulsion was then added dropwise via a metering pump over 160 minutes.
Next, the polymerization flask was kept at 75°C for 3 hours while continuing to stir slowly, and then returned to room temperature.
This resulted in a styrene-based resin particle dispersion (St1) containing styrene-based resin particles, with a volume-average particle size (D50v) of 174 nm, a weight-average molecular weight of 49,000 determined by GPC (UV detection), a glass transition temperature of 54°C, and a solid content of 42%.

A dispersion of styrene-based resin particles (St1) was dried to extract the styrene-based resin particles. The thermal behavior of these particles in the temperature range of -100°C to 100°C was analyzed using a differential scanning calorimeter (Shimadzu Corporation, DSC-60A). One glass transition temperature was observed. Table 1 shows the glass transition temperature.

[Preparation of styrene resin particle dispersions (St2) to (St13)]
Styrene resin particle dispersions (St2) to (St13) were prepared in the same manner as the preparation of styrene resin particle dispersion (St1), except that the monomer was changed as shown in Table 1.

Table 1 shows the composition and physical properties of styrene resin particle dispersion (St1), etc. In Table 1, monomers are indicated by the following abbreviations.
Styrene: St, n-butyl acrylate: BA, 2-ethylhexyl acrylate: 2EHA, ethyl acrylate: EA, 4-hydroxybutyl acrylate: 4HBA, acrylic acid: AA, methacrylic acid: MAA, 2-carboxyethyl acrylate: CEA

<Preparation of a dispersion containing composite resin particles>
[Preparation of composite resin particle dispersion (M1)]
Styrene-based resin particle dispersion (St1): 1190 parts (500 parts solids)
- 250 parts of 2-ethylhexyl acrylate - 250 parts of n-butyl acrylate - 982 parts of deionized water The above materials were placed in a polymerization flask, stirred at 25°C for 1 hour, and then heated to 70°C.
2.5 parts of ammonium persulfate were dissolved in 75 parts of deionized water and added dropwise to the polymerization flask via a metering pump over a period of 60 minutes.
Next, the polymerization flask was kept at 70°C for 3 hours while continuing to stir slowly, and then returned to room temperature.
This resulted in a composite resin particle dispersion (M1) containing composite resin particles, with a volume-average particle size (D50v) of 219 nm, a weight-average molecular weight of 219,000 determined by GPC (UV detection), and a solid content of 32%.

The composite resin particle dispersion (M1) was dried to extract the composite resin particles, and their thermal behavior was analyzed using a differential scanning calorimeter (Shimadzu DSC-60A) in the temperature range of -150°C to 100°C. Two glass transition temperatures were observed. Table 2 shows the glass transition temperatures.

[Preparation of composite resin particle dispersions (M2) to (M21) and (cM1) to (cM3)]
Composite resin particle dispersions (M2) to (M21) and (cM1) to (cM3) were prepared in the same manner as the preparation of composite resin particle dispersion (M1), except that the styrene-based resin particle dispersion (St1) was changed as shown in Table 2, or the polymerization component of the (meth)acrylic acid ester resin was changed as shown in Table 2.

[Preparation of composite resin particle dispersions (M22) to (M27)]
Composite resin particle dispersions (M22) to (M27) were prepared in the same manner as the preparation of composite resin particle dispersion (M1), except that the amounts of 2-ethylhexyl acrylate and n-butyl acrylate used were adjusted.

Table 2 shows the composition and physical properties of the composite resin particle dispersion (M1), etc. In Table 2, monomers are indicated by the following abbreviations.
Styrene: St, n-butyl acrylate: BA, 2-ethylhexyl acrylate: 2EHA, ethyl acrylate: EA, 4-hydroxybutyl acrylate: 4HBA, acrylic acid: AA, methacrylic acid: MAA, 2-carboxyethyl acrylate: CEA, hexyl acrylate: HA, propyl acrylate: PA

[Preparation of composite resin particle dispersions (M28) to (M30)]
Composite resin particle dispersions (M28) to (M30) with different weight-average molecular weights of composite resin particles were prepared in the same manner as the preparation of composite resin particle dispersion (M1), except that the amount of ammonium persulfate was changed as shown in Table 3.

Table 4 shows the composition and physical properties of the composite resin particle dispersion (M28), etc. In Table 4, monomers are indicated by the following abbreviations.
Styrene: St, n-butyl acrylate: BA, acrylic acid: AA, 2-ethylhexyl acrylate: 2EHA

<Preparation of pressure-responsive particles>
[Preparation of pressure-responsive particles (1)]
• Composite resin particle dispersion (M1): 504 parts • Ion-exchanged water: 710 parts • Anionic surfactant (Dow Chemical Company, Dowfax 2A1): 1 part

The above materials were placed in a reaction vessel equipped with a thermometer and a pH meter. A 1.0% nitric acid aqueous solution was added to adjust the pH to 3.0 at a temperature of 25°C. Then, 23 parts of a 2.0% aluminum sulfate aqueous solution were added while dispersing the mixture in a homogenizer (IKA Ultra-Turrax T50) at a rotation speed of 5000 rpm. Next, a stirrer and mantle heater were installed in the reaction vessel, and the temperature was increased at a rate of 0.2°C/min up to 40°C, and then at a rate of 0.05°C/min thereafter. The particle size was measured every 10 minutes using a Multisizer II (aperture diameter 50 μm, Beckman-Coulter). When the volume-average particle size reached 5.0 μm, the temperature was maintained, and 170 parts of a styrene-based resin particle dispersion (St1) were added over 5 minutes. After the addition was complete, the mixture was maintained at 50°C for 30 minutes, and then a 1.0% sodium hydroxide aqueous solution was added to adjust the pH of the slurry to 6.0. Next, the temperature was increased to 90°C at a rate of 1°C/min while adjusting the pH to 6.0 every 5°C, and then maintained at 90°C. Particle shape and surface properties were observed using an optical microscope and a field emission scanning electron microscope (FE-SEM). Particle coalescence was confirmed after 10 hours, so the container was cooled to 30°C with cooling water over 5 minutes.

The cooled slurry was passed through a 15 μm nylon mesh to remove coarse particles, and the slurry that passed through the mesh was filtered under reduced pressure using an aspirator. The remaining solids on the filter paper were crushed as finely as possible by hand and added to 10 times the volume of deionized water (at 30°C), and stirred for 30 minutes. Next, the mixture was filtered under reduced pressure using an aspirator, the remaining solids on the filter paper were crushed as finely as possible by hand and added to 10 times the volume of deionized water (at 30°C), stirred for 30 minutes, and then filtered again under reduced pressure using an aspirator. The electrical conductivity of the filtrate was measured. This process was repeated until the electrical conductivity of the filtrate was 10 μS/cm or less, and the solids were washed away.

The washed solids were finely crushed using a wet-dry granulator (Cormill) and vacuum-dried in a 25°C oven for 36 hours to obtain pressure-responsive mother particles (1). The volume-average particle size of pressure-responsive mother particles (1) was 8.0 μm.

100 parts of pressure-responsive mother particles (1), 1.6 parts of first hydrophobic silica particles (number-average particle size 82 nm, silica particles surface-treated with hexamethyldisilazane to make them hydrophobic), and 1.3 parts of second hydrophobic silica particles (number-average particle size 121 nm, silica particles surface-treated with hexamethyldisilazane to make them hydrophobic) were mixed and mixed for 30 seconds at a rotation speed of 13,000 rpm using a sample mill. The mixture was then sieved using a vibrating sieve with a mesh size of 45 μm to obtain pressure-responsive particles (1).

Using pressure-responsive particles (1) as a sample, their thermal behavior was analyzed using a differential scanning calorimeter (Shimadzu DSC-60A) in the temperature range of -150°C to 100°C. Two glass transition temperatures were observed. Table 5 shows the glass transition temperatures.

The temperatures T1 and T2 of the pressure-responsive particle (1) were determined using the measurement method described above, and it was found that the pressure-responsive particle (1) satisfied equation 1, "10°C ≤ T1 - T2".

A cross-sectional view of the pressure-responsive particle (1) was observed using a scanning electron microscope (SEM), revealing a sea-island structure. The pressure-responsive particle (1) consisted of a core containing island phases and a shell layer lacking these island phases. The sea phase contained styrene-based resin, while the island phases contained (meth)acrylic acid ester-based resin. The average diameter of the island phases was determined using the previously described measurement method. Table 5 shows the average diameter of the island phases.

The ratio of surface coverage Cs1 to surface coverage Cs2 in the pressure-responsive particle (1) satisfied the relationship 0.4 ≤ Cs2/Cs1 ≤ 0.8.

[Preparation of pressure-responsive particles (2) to (27)]
Pressure-responsive particles (2) to (27) were prepared in the same manner as the preparation of pressure-responsive particles (1), except that the composite resin particle dispersion and styrene-based resin particle dispersion were changed as shown in Table 5.

The temperatures T1 and T2 of pressure-responsive particles (2) to (27) were determined using the measurement method described above, and all pressure-responsive particles (2) to (27) satisfied equation 1, "10°C ≤ T1 - T2".

The ratio of surface coverage Cs1 to surface coverage Cs2 in pressure-responsive particles (2) to (27) satisfied the relationship 0.4 ≤ Cs2/Cs1 ≤ 0.8.

[Preparation of pressure-responsive particles (28) to (30)]
Pressure-responsive particles (28) to (30) were prepared in the same manner as the preparation of pressure-responsive particles (1), except that the composite resin particle dispersion was changed as shown in Table 6.

The temperatures T1 and T2 of the pressure-responsive particles (28) to (30) were determined using the measurement method described above, and all of the pressure-responsive particles (28) to (30) satisfied equation 1, "10°C ≤ T1 - T2".

The ratio of surface coverage Cs1 to surface coverage Cs2 in the pressure-responsive particles (28) to (30) satisfied the relationship 0.4 ≤ Cs2/Cs1 ≤ 0.8.

[Preparation of pressure-responsive particles (31)]
Pressure-responsive mother particles were prepared using the following grinding method.
A composite resin particle dispersion (M1) was dried to obtain composite resin particles (M31). The composite resin particles (M31) were heat-mixed in an extruder at a set temperature of 100°C, cooled, then pulverized and classified to obtain pressure-responsive mother particles (31) with a volume-average particle size of 8.0 μm.

100 parts of pressure-responsive mother particles (31), 1.6 parts of first hydrophobic silica particles (number-average particle size 82 nm, silica particles surface-treated with hexamethyldisilazane to make them hydrophobic), and 1.3 parts of second hydrophobic silica particles (number-average particle size 121 nm, silica particles surface-treated with hexamethyldisilazane to make them hydrophobic) were mixed and mixed for 30 seconds at a rotation speed of 13,000 rpm using a sample mill. The mixture was then sieved using a vibrating sieve with a mesh size of 45 μm to obtain pressure-responsive particles (31).

Using pressure-responsive particles (31) as a sample, their thermal behavior was analyzed using a differential scanning calorimeter (Shimadzu DSC-60A) in the temperature range of -150°C to 100°C. Two glass transition temperatures were observed. Table 6 shows the glass transition temperatures.

The temperatures T1 and T2 of the pressure-responsive particles (31) were determined using the measurement method described above, and it was found that the pressure-responsive particles (31) satisfied equation 1, "10°C ≤ T1 - T2".

The ratio of surface coverage Cs1 to surface coverage Cs2 in the pressure-responsive particle (31) satisfied the relationship 0.4 ≤ Cs2/Cs1 ≤ 0.8.

[Preparation of pressure-responsive particles (c1) to (c3) for comparison]
Pressure-responsive particles (c1) to (c3) were prepared in the same manner as the preparation of pressure-responsive particles (1), except that the composite resin particle dispersion and styrene-based resin particle dispersion were changed as shown in Table 5.

[Evaluation of pressure-responsive phase transitions]
The temperature difference (T1-T3), an indicator of how easily pressure-responsive particles undergo a phase transition due to pressure, was determined. Each pressure-responsive particle was used as a sample, and temperatures T1 and T3 were measured using a flow tester (Shimadzu Corporation, CFT-500). The temperature difference (T1-T3) is calculated. Tables 5 and 6 show the temperature differences (T1-T3).

[Evaluation of adhesion]
Fuji Xerox V424 postcard paper was used as the recording medium. Using a Fuji Xerox DocuCentre C7550I image forming machine and commercially available yellow, magenta, cyan, and black toners from Fuji Xerox, an image with a 30% area density, containing a mixture of black text and a full-color photographic image, was formed on one side of the postcard paper, and the image was fixed.
Pressure-responsive particles were scattered over the entire image-forming surface of a postcard paper at a concentration of 3 g/ ^m² . The postcard paper was then passed through a belt-roll type fixing machine to fix the pressure-responsive particles to the image-forming surface, forming a layer of pressure-responsive particles.
Postcard paper having a layer of pressure-responsive particles on the image-forming surface was folded in half with the image-forming surface facing inward using a sealer, PRESSLE multiII, manufactured by Toppan Forms. Pressure was then applied to the folded postcard paper, and the inner image-forming surfaces were bonded together at a pressure of 90 MPa.
Under the above apparatus and conditions, ten postcards were continuously produced, each folded in half with the image-forming surface facing inward and the image-forming surfaces adhered together.
The tenth postcard was cut along its longest side to create rectangular test pieces with a width of 15 mm, and a 90-degree peel test was performed. The peeling speed for the 90-degree peel test was set to 20 mm/min. The load (N) was measured at 0.4 mm intervals from 10 mm to 50 mm after the start of measurement, and the average was calculated. The load (N) of the three test pieces was then averaged. The load (N) required for peeling was classified as follows. The results are shown in Tables 5 and 6.

A: 0.8N or more B: 0.6N or more, less than 0.8N C: 0.4N or more, less than 0.6N D: 0.2N or more, less than 0.4N E: Less than 0.2N

When pressure-responsive particles (1) to (31) were subjected to the same evaluation as described below in [Evaluation of Storage Properties - Storage Properties (1)], pressure-responsive particles (1) to (31) were each classified as A.

<Preparation of a dispersion containing composite resin particles>
[Preparation of composite resin particle dispersion (M50)]
Styrene-based resin particle dispersion (St1): 1190 parts (500 parts solids)
- 200 parts of 2-ethylhexyl acrylate - 200 parts of n-butyl acrylate - 1360 parts of deionized water The above materials were placed in a polymerization flask, stirred at 25°C for 1 hour, and then heated to 70°C.
2.5 parts of ammonium persulfate were dissolved in 75 parts of deionized water and added dropwise to the polymerization flask via a metering pump over a period of 60 minutes.
Next, the polymerization flask was kept at 70°C for 2 hours while continuing to stir slowly, and then a mixture of 85 parts styrene and 15 parts n-butyl acrylate was added dropwise over 60 minutes. After the dropwise addition, it was kept at 75°C for 3 hours, and then allowed to return to room temperature.
This resulted in a composite resin particle dispersion (M50) containing composite resin particles, with a volume-average particle size (D50v) of 223 nm, a weight-average molecular weight of 220,000 determined by GPC (UV detection), and a solid content of 32%.

The composite resin particle dispersion (M50) was dried to extract the composite resin particles, and their thermal behavior was analyzed using a differential scanning calorimeter (Shimadzu DSC-60A) in the temperature range of -150°C to 100°C. Two glass transition temperatures were observed. Table 7 shows the glass transition temperatures.

[Preparation of composite resin particle dispersions (M51) to (M55)]
Composite resin particle dispersions (M51) to (M55) were prepared in the same manner as the preparation of composite resin particle dispersion (M50), except that the materials were changed to the specifications shown in Table 7.

Table 7 shows the composition and physical properties of the composite resin particle dispersion (M50), etc. In Table 7, monomers are indicated by the following abbreviations.
Styrene: St, n-butyl acrylate: BA, acrylic acid: AA, 2-ethylhexyl acrylate: 2EHA

<Preparation of pressure-responsive particles>
[Preparation of pressure-responsive particles (50) to (55)]
Pressure-responsive particles (50) to (55) were prepared in the same manner as the preparation of pressure-responsive particle (1), except that the material was changed to the specifications shown in Table 8.

Using pressure-responsive particles (50) to (55) as samples, their thermal behavior was analyzed using a differential scanning calorimeter (Shimadzu DSC-60A) in the temperature range of -150°C to 100°C. Two glass transition temperatures were observed. Table 8 shows the glass transition temperatures.

The temperatures T1 and T2 of the pressure-responsive particles (50) to (55) were determined using the measurement method described above, and all of the pressure-responsive particles (50) to (55) satisfied equation 1, "10°C ≤ T1 - T2".

Cross-sections of pressure-responsive particles (50) to (55) were observed using a scanning electron microscope (SEM), revealing a sea-island structure. Pressure-responsive particles (50) to (55) consisted of a core containing island phases and a shell layer lacking these island phases. The sea phases contained styrene-based resin, while the island phases contained (meth)acrylic acid ester-based resin. The average diameter of the island phases was determined using the previously described measurement method. Table 8 shows the average diameters of the island phases.

The ratio of surface coverage Cs1 to surface coverage Cs2 in the pressure-responsive particles (50) to (55) satisfied the relationship 0.4 ≤ Cs2/Cs1 ≤ 0.8.

[Evaluation of pressure-responsive phase transitions]
Each pressure-responsive particle was used as a sample, and temperatures T1 and T3 were measured using a flow tester (Shimadzu Corporation, CFT-500). The temperature difference (T1-T3) was then calculated. Table 8 shows the temperature difference (T1-T3).

[Evaluation of adhesion]
Similar to the pressure-responsive particles (1), the adhesion was evaluated using the evaluation method described in [Evaluation of Adhesion] above. The results are shown in Table 8.

When pressure-responsive particles (50) to (55) were subjected to the same evaluation as described later in [Evaluation of Storage Properties - Storage Properties (1)], pressure-responsive particles (50) to (55) were each classified as A.

<Manufacturing of printed materials using electrophotography>
Ten parts of any of the pressure-responsive particles (1) to (31), (c1) to (c3), and (50) to (55) were placed in a V-type blender and stirred for 20 minutes. Then, the mixture was sieved with a vibrating sieve with a mesh size of 212 μm to obtain the developers (1) to (31), (c1) to (c3), and (50) to (55), respectively.

- Resin-coated carrier (1) -
- Mn-Mg-Sr ferrite particles (average particle size 40 μm): 100 parts - Toluene: 14 parts - Polymethyl methacrylate: 2 parts - Carbon black (VXC72: manufactured by Cabot): 0.12 parts The above materials, excluding the ferrite particles, were mixed with glass beads (1 mm in diameter, same amount as toluene), and stirred for 30 minutes at a rotation speed of 1200 rpm using a sand mill manufactured by Kansai Paint Co., Ltd. to obtain a dispersion. This dispersion and the ferrite particles were placed in a vacuum-degassing kneader, and dried under reduced pressure while stirring to obtain a resin-coated carrier (1).

As a printing apparatus, we prepared an apparatus in the form shown in Figure 4. Specifically, we prepared a printing apparatus that includes a five-tandem and intermediate transfer printing means that performs the arrangement of pressure-responsive particles according to this embodiment onto a recording medium and the formation of a colored image in a single operation, and a crimping means that has a folding device and a pressing device.
Each of the five developing units in the printing apparatus contained the developer according to this embodiment (or a comparative developer), a yellow developer, a magenta developer, a cyan developer, and a black developer. Commercially available developers from Fuji Xerox Corporation were used for each color, including yellow.
Fuji Xerox V424 postcard paper was prepared as the recording medium.
The image formed on the postcard paper was a 30% area density image consisting of a mixture of black text and a full-color photograph, and was formed on one side of the postcard paper.
In this embodiment, the amount of pressure-responsive particles (or comparative pressure-responsive particles) applied to the image-forming area of the image-forming surface of the postcard paper was 3 g/ ^m² .
The folding device was designed to fold postcard paper in half so that the image-forming surface was on the inside.
The pressurizing device was set to a pressure of 90 MPa.
Under the above apparatus and conditions, ten postcards were continuously produced, each folded in half with the image-forming surface facing inward and the image-forming surfaces adhered together.
The tenth postcard was cut along its longest side to create rectangular test pieces with a width of 15 mm, and a 90-degree peel test was performed. The peeling speed for the 90-degree peel test was set to 20 mm/min, and the load (N) was measured at 0.4 mm intervals from 10 mm to 50 mm after the start of measurement. The average of these measurements was calculated, and the load (N) of the three test pieces was then averaged. The load (N) required for peeling was classified as follows. The results are shown in Tables 9, 10, and 11.

A: 0.8N or more B: 0.6N or more, less than 0.8N C: 0.4N or more, less than 0.6N D: 0.2N or more, less than 0.4N E: Less than 0.2N

<Investigation of surface coverage rate using silica particles (1)>
[Preparation of pressure-responsive particles (60)]
Pressure-responsive mother particles (60) with a volume-average particle size of 9.5 μm were prepared in the same manner as the preparation of pressure-responsive mother particles (1), except that 5.0 parts of a 2.0% aluminum sulfate aqueous solution were added during the fusion and coalescence step, and the time of the fusion and coalescence step was adjusted.

100 parts of pressure-responsive mother particles (60), 1.6 parts of small-diameter silica particles (number-average particle size 82 nm, surface-treated with hexamethyldisilazane and hydrophobized silica particles), and 1.3 parts of large-diameter silica particles (number-average particle size 121 nm, surface-treated with hexamethyldisilazane and hydrophobized silica particles) were mixed and mixed for 30 seconds at a rotation speed of 13,000 rpm using a sample mill. The mixture was then sieved using a vibrating sieve with a mesh size of 45 μm to obtain pressure-responsive particles (60).

Using pressure-responsive particles (60) as a sample, the thermal behavior was analyzed using a differential scanning calorimeter (Shimadzu DSC-60A) in the temperature range of -150°C to 100°C. Two glass transition temperatures were observed: -52°C and 54°C.

The temperatures T1 and T2 of the pressure-responsive particles (60) were determined using the measurement method described above, and it was found that the pressure-responsive particles (60) satisfied Equation 1, "10°C ≤ T1 - T2".

[Preparation of pressure-responsive particles (61) to (64) and (c4) to (c5)]
Pressure-responsive particles (61) to (64) and (c4) to (c5) were prepared in the same manner as the preparation of pressure-responsive particles (60), except that the small-diameter silica particles and large-diameter silica particles were changed to the specifications shown in Table 12.

The temperatures T1 and T2 of the pressure-responsive particles (61) to (64) were determined using the measurement method described above, and all of the pressure-responsive particles (61) to (64) satisfied Equation 1, "10°C ≤ T1 - T2".

[Preparation of pressure-responsive particles (65)]
Pressure-responsive mother particles (65) with a volume-average particle size of 9.5 μm were prepared in the same manner as the preparation of pressure-responsive mother particles (60), except that 2.5 parts of a 2.0% aluminum sulfate aqueous solution were added in the fusion and coalescence step, and the time of the fusion and coalescence step was adjusted.

Pressure-responsive particles (65) were prepared in the same manner as the pressure-responsive particles (60), except that pressure-responsive parent particles (65) were used instead of pressure-responsive parent particles (60).

The temperatures T1 and T2 of the pressure-responsive particles (65) were determined using the measurement method described above, and it was found that the pressure-responsive particles (65) satisfied Equation 1, "10°C ≤ T1 - T2".

[Preparation of pressure-responsive particles (66)]
Pressure-responsive mother particles (66) with a volume-average particle size of 9.5 μm were prepared in the same manner as the preparation of pressure-responsive mother particles (60), except that 4.0 parts of a 2.0% aluminum sulfate aqueous solution were added in the fusion and coalescence step, and the time of the fusion and coalescence step was adjusted.

Pressure-responsive particles (66) were prepared in the same manner as the pressure-responsive particles (60), except that pressure-responsive parent particles (66) were used instead of pressure-responsive parent particles (60).

The temperatures T1 and T2 of the pressure-responsive particles (66) were determined using the measurement method described above, and it was found that the pressure-responsive particles (66) satisfied Equation 1, "10°C ≤ T1 - T2".

[Preparation of pressure-responsive particles (67)]
Pressure-responsive mother particles (67) with a volume-average particle size of 9.5 μm were prepared in the same manner as the preparation of pressure-responsive mother particles (60), except that 10.0 parts of 2.0% aluminum sulfate aqueous solution were added in the fusion and coalescence step, and the time of the fusion and coalescence step was adjusted.

Pressure-responsive particles (67) were prepared in the same manner as pressure-responsive particles (60), except that pressure-responsive parent particles (67) were used instead of pressure-responsive parent particles (60).

The temperatures T1 and T2 of the pressure-responsive particles (67) were determined using the measurement method described above, and it was found that the pressure-responsive particles (67) satisfied Equation 1, "10°C ≤ T1 - T2".

[Preparation of pressure-responsive particles (68)]
Pressure-responsive mother particles (68) with a volume-average particle size of 9.5 μm were prepared in the same manner as the preparation of pressure-responsive mother particles (60), except that 20.0 parts of a 2.0% aluminum sulfate aqueous solution were added in the fusion and coalescence step, and the time of the fusion and coalescence step was adjusted.

Pressure-responsive particles (68) were prepared in the same manner as the pressure-responsive particles (60), except that pressure-responsive parent particles (68) were used instead of pressure-responsive parent particles (60).

The temperatures T1 and T2 of the pressure-responsive particles (68) were determined using the measurement method described above, and it was found that the pressure-responsive particles (68) satisfied Equation 1, "10°C ≤ T1 - T2".

[Evaluation of storage capacity - Storage capacity (1) -]
Ten g of pressure-responsive particles were placed in a constant temperature and humidity chamber controlled at 50°C and 50% relative humidity for 17 hours. The particles were then sieved using a 200-mesh (75 micron opening) vibrating sieve, and the amount passing through was measured. The particles were then classified as follows. Table 12 shows the results.
A: Passage rate of 90% by mass or more B: Passage rate of 80% by mass or more, but less than 90% by mass C: Passage rate of 70% by mass or more, but less than 80% by mass D: Passage rate of 60% by mass or more, but less than 70% by mass E: Passage rate of less than 60% by mass

[Evaluation of adhesion]
The adhesion properties were evaluated using the aforementioned evaluation method for pressure-responsive particles (1), etc. The results are shown in Table 12.

<Investigation of surface coverage rate using silica particles (2)>
[Preparation of pressure-responsive particles (70)]
Pressure-responsive mother particles (70) with an average circularity of 0.961 were prepared in the same manner as the preparation of pressure-responsive mother particles (1), except that the temperature reached and the holding time in the fusion and coalescence step were adjusted.

100 parts of pressure-responsive mother particles (70), 1.6 parts of small-diameter silica particles (number-average particle size 82 nm, surface-treated with hexamethyldisilazane to make them hydrophobic), and 1.3 parts of large-diameter silica particles (number-average particle size 121 nm, surface-treated with hexamethyldisilazane to make them hydrophobic) were mixed and mixed for 30 seconds at a rotation speed of 13,000 rpm using a sample mill. The mixture was then sieved using a vibrating sieve with a mesh size of 45 μm to obtain pressure-responsive particles (70).

Using pressure-responsive particles (70) as a sample, the thermal behavior was analyzed using a differential scanning calorimeter (Shimadzu DSC-60A) in the temperature range of -150°C to 100°C. Two glass transition temperatures were observed: -52°C and 54°C.

The temperatures T1 and T2 of the pressure-responsive particles (70) were determined using the measurement method described above, and it was found that the pressure-responsive particles (70) satisfied Equation 1, "10°C ≤ T1 - T2".

[Preparation of pressure-responsive particles (71) to (75) and (c6) to (c7)]
Pressure-responsive particles (71) to (75) and (c6) to (c7) were prepared in the same manner as the preparation of pressure-responsive particles (70), except that the average circularity of the pressure-responsive mother particles was adjusted by adjusting the temperature reached and the holding time during the fusion and coalescence process in the preparation of pressure-responsive mother particles, and the amount of silica particles added was set to the specifications shown in Table 13.

The temperatures T1 and T2 of the pressure-responsive particles (71) to (75) were determined using the measurement method described above, and all of the pressure-responsive particles (71) to (75) satisfied Equation 1, "10°C ≤ T1 - T2".

[Evaluation of storage capacity - Storage capacity (1) -]
The storage properties were evaluated using the same method as described above for pressure-responsive particles (60), etc. [Evaluation of storage properties - Storage properties (1) -]. The results are shown in Table 13.

[Evaluation of storage capacity - Storage capacity (2) -]
Ten grams of pressure-responsive particles, after being subjected to a second stress, were placed in a circular container with an inner diameter of 5 cm. A weight with a base diameter of approximately 5 cm and a weight of 10 g was placed on the exposed surface of the pressure-responsive particles, and the container was left in an environment of 23°C and 55% relative humidity for 30 days. The ease of removing the pressure-responsive particles from the container was classified as follows. The results are shown in Table 13.
A: When the container is turned upside down, the contents easily flow out, and pressure-responsive particles can be extracted.
B: By turning the container upside down and applying vibration, pressure-responsive particles can be extracted.
C: When a spatula is placed in the container and gently stirred, pressure-responsive particles can be extracted, but some are aggregated.
D: When a spatula is placed in the container and stirred vigorously, pressure-responsive particles can be extracted, but most of them are aggregated.
E: Pressure-responsive particles cannot be removed from the container.

[Evaluation of adhesion]
The pressure-responsive particles after the second stress was applied were evaluated for adhesion using the same evaluation method as described above for pressure-responsive particles (1), etc. The results are shown in Table 13.

100 Arrangement means 110 Applied device 120 Fixing device 200 Crimping means 220 Folding device 230 Pressurizing devices 231, 232 Pressurizing roll M Pressure-responsive particles P Recording medium P1 Recording medium P2 on which pressure-responsive particles are applied to an image Folded recording medium P3 Crimped print

400 Inkjet recording device 30Y, 30M, 30C, 30K Ink ejection head 32Y, 32M, 32C, 32K Ink cartridge 34Y, 34M, 34C, 34K Drying means 40 Housing 42, 66 Container 44, 62 Conveyor path 46 Roll 48, 64 Roll pair 50 Conveyor belt 52 Driven roll 54 Driven roll 56 Charging roll 58 Release plate

101 Photoreceptor 102 Charging roll (an example of a charging means)
103 Exposure apparatus (an example of electrostatic image formation means)
104 Developing apparatus (an example of a developing means)
105 Transfer Roll (An example of a transfer method)
106 Photoreceptor cleaning device (an example of a cleaning method)
107 Fixing device (an example of fixing means)

300 Printing means 1T, 1Y, 1M, 1C, 1K Photoreceptor 2T, 2Y, 2M, 2C, 2K Charging roll (example of charging means)
3T, 3Y, 3M, 3C, 3K exposure device (an example of electrostatic image forming means)
4T, 4Y, 4M, 4C, 4K developing apparatus (an example of a developing method)
5T, 5Y, 5M, 5C, 5K Primary Transfer Rolls (Example of Primary Transfer Method)
6T, 6Y, 6M, 6C, 6K Photoreceptor Cleaning Device (Example of Cleaning Method)
8T Pressure-responsive particle cartridges 8Y, 8M, 8C, 8K Toner cartridges 10T, 10Y, 10M, 10C, 10K Unit 20 Intermediate transfer belt (an example of an intermediate transfer body)
21 Intermediate transfer body cleaning device 22 Drive roll 23 Support roll 24 Opposing roll 26 Secondary transfer roll (an example of a secondary transfer means)
28. Thermal fixing device (an example of a thermal fixing means)

Claims (26)

A pressure-responsive mother particle containing a styrene-based resin containing styrene and other vinyl monomers as polymerization components, and a (meth)acrylic acid ester-based resin containing at least two types of (meth)acrylic acid esters as polymerization components, wherein the mass ratio of (meth)acrylic acid esters to the total polymerization components is 90% by mass or more,
Contains silica particles,
It has at least two glass transition temperatures, and the difference between the lowest and highest glass transition temperatures is 30°C or more.
A pressure-responsive particle in which the ratio of the surface coverage rate Cs1 of silica particles before stress is applied to the surface coverage rate Cs2 of silica particles after the application of the first stress described below satisfies the relationship 0.4 ≤ Cs2/Cs1 ≤ 0.8.
First stress test: Under a temperature of 20°C and a relative humidity of 50%, 10 g of pressure-responsive particles and 90 g of resin-coated ferrite particles are placed in a 0.5 L rotary V-type mixer and operated at a rotation speed of 40 revolutions per minute for 20 minutes. The pressure-responsive particle according to claim 1, wherein the ratio of the surface coverage ratio Cs1 to the surface coverage ratio Cs2 satisfies the relationship 0.5 ≤ Cs2/Cs1 ≤ 0.7. The pressure-responsive particle according to claim 1 or 2, wherein the surface coverage ratio Cs1 is 40% or more and 80% or less, and the surface coverage ratio Cs2 is 35% or more and 60% or less. The pressure-responsive particle according to claim 3, wherein the surface coverage ratio Cs1 is 50% or more and 80% or less, and the surface coverage ratio Cs2 is 35% or more and 50% or less. The pressure-responsive particle according to any one of claims 1 to 4, wherein the average circularity of the pressure-responsive matrix particle is 0.955 or more and 0.975 or less. The pressure-responsive particle according to claim 5, wherein the average circularity of the pressure-responsive matrix particle is 0.955 or more and 0.970 or less. A pressure-responsive particle according to any one of claims 1 to 6, wherein the ratio of the surface coverage rate Cs2 to the surface coverage rate Cs3 of silica particles after the second stress described below is satisfied with the relationship 0.4 ≤ Cs2/Cs3 ≤ 0.9.
Second stress test: Under a temperature of 20°C and a relative humidity of 50%, 10 g of pressure-responsive particles are placed in a 0.5 L rotary V-type mixer and operated at a rotation speed of 40 revolutions per minute for 20 minutes. The pressure-responsive particle according to claim 7, wherein the ratio of the surface coverage ratio Cs2 to the surface coverage ratio Cs3 satisfies the relationship 0.4 ≤ Cs2/Cs3 ≤ 0.8. The pressure-responsive particle according to claim 7 or claim 8, wherein the surface coverage Cs3 is 40% or more and 60% or less. The pressure-responsive particle according to any one of claims 1 to 9, wherein the concentration of Al element on the surface of the pressure-responsive mother particle is 0.1 atomic% or more and 1.5 atomic% or less. The pressure-responsive particle according to claim 10, wherein the Al element concentration on the surface of the pressure-responsive mother particle is 0.3 atomic% or more and 0.9 atomic% or less. The pressure-responsive particle according to any one of claims 1 to 11, wherein the particle size distribution of the silica particles has peaks in the range of particle size 100 nm or less and in the range of particle size greater than 100 nm. A pressure-responsive particle according to any one of claims 1 to 12, wherein the ratio of the mass Ms1 of silica particles with a particle size of 100 nm or less, determined from the particle size distribution of the silica particles, to the mass Ms2 of silica particles with a particle size greater than 100 nm, determined from the particle size distribution of the silica particles, satisfies the relationship 0.5 ≤ Ms2/Ms1 ≤ 1.3. The pressure-responsive particle according to any one of claims 1 to 13, wherein the pressure-responsive mother particle comprises a sea phase containing the styrene-based resin and an island phase containing the (meth)acrylic acid ester-based resin dispersed in the sea phase. The pressure-responsive particle according to claim 14, wherein the average diameter of the island phase is 200 nm or more and 500 nm or less. The pressure-responsive particle according to any one of claims 1 to 15, wherein the pressure-responsive mother particle comprises a core portion containing the styrene-based resin and the (meth)acrylic acid ester-based resin, and a shell layer covering the core portion. The pressure-responsive particle according to claim 16, wherein the shell layer contains the styrene-based resin. A cartridge containing pressure-responsive particles as described in any one of claims 1 to 17, and which is attached to and detached from a printing apparatus. Arrangement means for accommodating pressure-responsive particles according to any one of claims 1 to 17 and arranging the pressure-responsive particles on a recording medium,
A crimping means for folding and crimping the recording medium, or for crimping the recording medium and another recording medium on top of each other,
A manufacturing apparatus for printed materials, including those containing printed materials. The apparatus for manufacturing printed materials according to claim 19, further comprising a means for forming a colored image on a recording medium using a colorant. A placement step of arranging pressure-responsive particles on a recording medium using pressure-responsive particles according to any one of claims 1 to 17,
A crimping step of folding and crimping the recording medium, or crimping the recording medium and another recording medium together,
A method for manufacturing printed materials that include [the specified material]. A method for manufacturing a printed material according to claim 21, further comprising a color image forming step of forming a colored image on a recording medium using a colorant. A printed material comprising folded recording media bonded together on opposing surfaces by pressure-responsive particles as described in any one of claims 1 to 17. A printed material comprising multiple overlapping recording media bonded together on opposing surfaces by pressure-responsive particles as described in any one of claims 1 to 17. A pressure-responsive particle according to any one of claims 1 to 17 is used,
A sheet for manufacturing printed materials, comprising a base material and pressure-responsive particles disposed on the base material. The process includes a placement step of arranging pressure-responsive particles on a substrate using pressure-responsive particles according to any one of claims 1 to 17.
A method for manufacturing sheets for printed materials.