JP7703383B2 - Toner and method for producing the same - Google Patents

Description

This disclosure relates to toner used in electrophotographic image forming devices.

In recent years, there has been an increasing demand for power saving in electrophotographic image forming devices. In order to meet this demand for power saving, toners with excellent low-temperature fixing properties that can be fixed to media such as paper even at low temperatures are being studied.

A method is known for lowering the glass transition temperature of the resin component of the toner in order to improve the low-temperature fixability of the toner. However, when outputting images in a low-temperature environment, some of the heat required for fixation is likely to transfer into the paper or the air, making it difficult to provide a sufficient amount of heat to the toner. As a result, a higher fixing temperature is required to fix the toner, making fixing at low temperatures difficult. On the other hand, if the glass transition temperature of the resin component of the toner is lowered too much, the toner's storage stability against heat deteriorates, so a method is needed to further improve the low-temperature fixability of the toner.

In order to improve the low-temperature fixing ability of toner, toners that make it easier to melt the surface area of toner particles and therefore make it easier for the entire toner particle to melt quickly during fixing have been studied. Patent Documents 1 and 2 propose toners in which wax is unevenly distributed near the surface of the toner particles. It is believed that the uneven distribution of wax near the surface of the toner particles makes it easier for the wax to quickly melt the resin near the surface of the toner particles during fixing, and this allows for excellent low-temperature fixing ability even when image output is performed in a low-temperature environment.

JP 2016-62041 A JP 2016-224248 A

However, as a result of the inventors' investigation of the toners described in Patent Documents 1 and 2, it was found that the developability is likely to decrease when an image is output after an image forming apparatus has been left unused for a long period of time in a high-temperature, high-humidity environment. Specifically, it was found that the toners are likely to contaminate the non-image areas of the fixed image.

One aspect of the present disclosure provides a toner that has excellent low-temperature fixing properties even in a low-temperature environment, and also has excellent developability when outputting images after being left in a high-temperature, high-humidity environment for a long period of time.

One aspect of the present disclosure is a toner comprising toner particles containing a resin component and a wax, and inorganic fine particles on the surfaces of the toner particles,
In the cross-sectional observation of the toner particle,
Domains comprising said wax are observed;
Among the observed domains, a domain having a major axis of 10 to 300 nm is designated as a domain S, and an occupied area ratio of the domain S in a region from the surface of the toner particle to 600 nm is designated as R1, the R1 being 3.0 to 15.0%,
The inorganic fine particles contain fine particles A,
The volume resistivity of the fine particles A is 1.0×10 ³ to 3.0×10 ⁵ Ω·cm;
The toner is characterized in that the fine particles A have a relative dielectric constant εr of 100 or more.

According to the present disclosure, it is possible to provide a toner that has excellent low-temperature fixing properties even in a low-temperature environment, and also has excellent developability when outputting images after being left in a high-temperature, high-humidity environment for a long period of time.

1 is a schematic diagram of a cross section of a toner particle for explaining a hypothetical mechanism for achieving the effects of the present disclosure. FIG. 2 is a schematic diagram of a rotating body that can be used in a mixing device used in the external addition step of the present disclosure. FIG. 2 is a schematic diagram of a rotating body that can be used in a mixing device used in the external addition step of the present disclosure.

When a numerical range is expressed as "xx or more and xx or less" or "xx to xx", it means that the numerical range includes the lower and upper limit endpoints, unless otherwise specified.

When numerical ranges are stated in stages, the upper and lower limits of each numerical range can be combined in any way.

In this disclosure, a wax domain refers to a domain that contains wax, and a minute wax domain refers to a wax domain with a major axis of 10 to 300 nm.

When observing the cross section of a toner particle, the region from the surface of the toner particle to 600 nm refers to the region between the contour line corresponding to the surface of the toner particle and the contour line that is reduced by a distance of 600 nm inward from the contour line.

The near-surface region of a toner particle means the region extending from the surface of the toner particle to within 600 nm.

<The reason why non-image areas are easily stained and the background to the invention>
The present inventors speculate that the reason why the non-image areas of the fixed image are easily contaminated when the toners according to Patent Documents 1 and 2 are used and then left in a high-temperature, high-humidity environment for a long period of time and then an image is output is as follows.

Toner particles with minute wax domains dispersed near the surface of the toner particles tend to have excellent low-temperature fixing properties. The inventors believe that this is because the contact area between the dispersed wax and the resin near the surface of the toner particles is large, and the wax and the resin become compatible during fixing, making it easier for the resin near the surface of the toner particles to melt with a small amount of heat. In addition, as the resin near the surface of the toner particles melts with a small amount of heat, the entire toner particle tends to melt quickly. This is an advantageous characteristic because it allows the temperature during fixing to be lowered in electrophotographic image forming devices with high process speeds.

However, it is believed that toner particles with minute wax domains dispersed near the surface of the toner particle are prone to have non-uniform charge levels within the toner particle. If the charge level within the toner particle is non-uniform, the charge distribution throughout the toner is likely to be broad, and toner with a charge level outside the range of charge levels suitable for development is likely to be produced. Such toner is likely to adhere not only to the image areas in the fixed image, but also to the non-image areas, resulting in contamination of the non-image areas.

The inventors speculate that the reason why the charge amount in the toner particles according to Patent Documents 1 and 2 tends to be non-uniform is that a difference in charge amount tends to occur between the areas near the surface of the toner particles where wax is present and the areas where wax is not present.

It was also found that the above problem is more pronounced in image output after being left in a high-temperature, high-humidity environment for a long period of time. The inventors speculate that one of the reasons for this is that the charge on the surface of the toner particles is affected by the amount of moisture in the air.

As a result of further investigations based on these considerations, it was found that a toner containing fine particles A having the following volume resistivity and relative dielectric constant on the surface of the toner particles is less likely to contaminate non-image areas of a fixed image, even though the toner particles have minute wax particles near the surface.

Volume resistivity of fine particles A: 1.0×10 ³ to 3.0×10 ⁵ Ω·cm
Relative dielectric constant εr of fine particles A: 100 or more <Expected mechanism by which the effects of the present disclosure are manifested>
The mechanism by which the toner having the above-described configuration exhibits the effects of the present disclosure will be described with reference to FIG.

Figure 1 is an example of a schematic cross-sectional view of a toner particle according to the present disclosure.

In the area (surface vicinity area) from contour line 2, which corresponds to the surface of the toner particle, to contour line 3, which is reduced by a distance of 600 nm inward, minute wax domains 1 occupy a specific percentage of the area. In addition, fine particles 5 (fine particles A) are contained near the area where the wax domains exist near the surface of the toner particle.

Toner with this composition is believed to have fine wax domains 1 that are easily dispersed in the surface vicinity region of the toner particles, and the resin near the surface of the toner particles is likely to melt during fixing, making it easier to obtain a toner with excellent low-temperature fixing properties.

In addition, when the toner is charged, it is believed that the charge amount differs between the area near the surface where wax is present and the area near the surface where wax is not present, and therefore it is believed that fine particles 5 (fine particles A) with a high relative dielectric constant are more likely to be contained on the surface where the charge amount is high and the electric field is stronger. Furthermore, the inventors speculate that fine particles 5 (fine particles A) having a moderate volume resistivity makes it easier for an appropriate amount of charge to escape from the area where the charge amount is high, and the charge distribution tends to become sharper. Figure 1 shows an example where the area where wax is present near the surface of the toner particle has a stronger electric field.

As a specific example of fine particles A in this disclosure, one aspect of this disclosure is a toner that contains inorganic fine particles containing strontium titanate on the surface of the toner particles.

<Wax>
<Occupied Area Ratio of Micro Wax Domains Near the Surface of Toner Particles>
When observing a cross section of a toner particle, a wax domain having a major axis of 10 to 300 nm among the wax domains observed is defined as domain S, and the occupied area ratio of domain S in a region from the toner particle surface to 600 nm is defined as R1, where R1 is 3.0 to 15.0%. The inventors speculate that a wax domain having a major axis of less than 10 nm is too small in size to contribute much to improving the low-temperature fixability of the toner.

When R1 is 3.0% or more, a toner with excellent low-temperature fixing properties is easily obtained. Therefore, R1 is 3.0% or more, and more preferably 5.0% or more. Furthermore, when R1 is 15.0% or less, the resin component near the surface of the toner particles is less likely to melt excessively, and a toner with excellent heat-resistant storage stability is easily obtained. Therefore, R1 is 15.0% or less, and preferably 12.0% or less, more preferably 10.0% or less, and even more preferably 9.0% or less.

In addition, when observing the cross section of a toner particle, when the occupied area ratio of all wax domains in the region from the surface of the toner particle to 600 nm is taken as R2, it is preferable that the above-mentioned R2 is 3.0 to 25.0%. It is presumed that by having R1 be 3.0 to 15.0% and R2 be within the above range, it is easy to obtain a toner that has excellent low-temperature fixing properties and in which inorganic fine particles including fine particles A are not easily embedded in the surface of the toner particle. It is more preferable that it is 3.0 to 20.0%, and even more preferable that it is 3.0 to 15.0%.

The wax domain area ratio in the region extending 600 nm inward from the surface of the toner particle means the ratio of the area of the domain to the area of the region extending 600 nm inward from the surface of the toner particle.

<Number of Micro Wax Domains Near the Surface of Toner Particle>
In cross-sectional observation of a toner particle, the number of the domains S in the region from the surface of the toner particle to 600 nm is preferably 100 or more. If the number of the domains S is 100 or more, it is assumed that the resin near the surface of the toner particle is likely to melt quickly during fixing, so that a toner having excellent low-temperature fixing properties is likely to be obtained. Therefore, it is preferably 100 or more, more preferably 150 or more, and even more preferably 200 or more. The upper limit is not particularly limited from the viewpoint of low-temperature fixing properties, but from the viewpoint of heat-resistant storage stability, it is preferably 350 or less, and more preferably 300 or less.

<Number Average Long Diameter of Wax Domains Near the Surface of Toner Particles>
In cross-sectional observation of a toner particle, when the number average major axis A1 of all wax domains in the region from the surface of the toner particle to 600 nm is taken as the diameter, it is preferable that the A1 is 30 to 150 nm. When A1 is 30 nm or more, many wax domains of appropriate size are likely to be contained in the surface vicinity region of the toner particle, and a toner having excellent low-temperature fixing property is likely to be obtained. Therefore, it is preferable that the A1 is 30 nm or more, more preferably 50 nm or more, and even more preferably 70 nm or more. Furthermore, when A1 is 150 nm or less, it is considered that the wax domains of excessive size are unlikely to increase in the surface vicinity region, and therefore a toner having appropriate elasticity and heat-resistant storage stability is likely to be obtained. Therefore, it is preferable that the A1 is 150 nm or less, preferably 120 nm or less, and even more preferably 100 nm or less.

The above R1, R2 and A1 can be controlled by the manufacturing conditions of the toner particles during toner production (particularly the cooling process and annealing process), the conditions of the external addition process, the type of wax, and the amount of wax added. The inventors speculate that in order to set the above R1, R2 and A1 within the above value ranges, a process for microcrystallizing the wax contained within the toner particles and a process for microcrystallizing the wax present near the surface of the toner particles are further required.

The process for microcrystallizing the wax contained in the toner particles includes the process of rapidly cooling the toner particles and then annealing them, which will be described later. This is thought to be because the rapid cooling of the toner particles makes it easier for crystalline nuclei of the wax contained in the toner particles to form, and the subsequent annealing promotes crystal growth of the crystalline nuclei, making it easier for minute wax domains to form within the toner particles.

In addition, a process for microcrystallizing the wax present near the surface of the toner particles can include a process of externally adding inorganic fine particles to the toner particles at a temperature at which the wax is likely to crystallize. It is presumed that by externally adding inorganic fine particles to the toner particles at this temperature, the uncrystallized wax present near the surface of the toner particles is likely to form a large number of crystal nuclei due to the impact from the inorganic fine particles. As a result, it is believed that minute wax domains are likely to be formed near the surface of the toner particles.

<Types of wax>
The toner particles preferably contain an ester wax, which is considered to be compatible with the resin component and therefore easily melts the resin component during fixing, making it easy to obtain a toner having excellent low-temperature fixing properties.

To make it easier to obtain a toner with excellent low-temperature fixing properties, it is preferable that the mass ratio of the ester wax to the mass of the resin component contained in the toner particles is 10.0 to 20.0 mass%.

The ester wax contained in the toner particles is not particularly limited, and the following ester waxes can be used:

Monofunctional ester waxes such as behenyl stearate, behenyl behenate, and stearyl behenate; bifunctional ester waxes such as ethylene glycol distearate, dibehenyl sebacate, and hexanediol dibehenate; trifunctional ester waxes such as glycerin tribehenate; tetrafunctional ester waxes such as pentaerythritol tetrastearate and pentaerythritol tetrapalmitate; hexafunctional ester waxes such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate; multifunctional ester waxes such as polyglycerin behenate; natural ester waxes such as carnauba wax and rice wax.

The toner particles may also contain waxes other than ester waxes, such as hydrocarbon waxes.

<Wax content>
The wax content in the toner particles is preferably 5.0 to 25.0% by mass. By including the wax in the toner particles in the above ratio, a toner having excellent low-temperature fixing property and releasability is easily obtained. More preferably, the wax content is 5.0 to 15.0% by mass.

<Inorganic fine particles>
<Fine particles A>
The inorganic fine particles contain fine particles A, and the volume resistivity of fine particles A is 1.0×10 ³ to 3.0×10 ⁵ Ω·cm. When the volume resistivity is 1.0×10 ³ Ω·cm or more, the charge charged on the surface of the toner particles is unlikely to escape excessively, and a toner having excellent charging properties and developing properties is likely to be obtained. When the volume resistivity is 3.0×10 ⁵ Ω·cm or less, the amount of charge escaping from the toner particles is unlikely to become too small, and a toner having excellent developing properties is likely to be obtained.

Fine particle A also has a relative dielectric constant εr of 100 or more. If the relative dielectric constant εr is 100 or more, fine particle A is likely to be contained in the highly charged portion of the surface of the toner particle. Therefore, it is preferably 100 or more, more preferably 150 or more, and even more preferably 200 or more. There is no particular upper limit, but it is preferably 1000 or less, more preferably 500 or less, and even more preferably 300 or less. In other words, the preferred range for the relative dielectric constant εr of fine particle A is 100 or more and 300 or less.

The volume resistivity and dielectric constant can be controlled by the type of inorganic fine particles added to the toner.

The fine particles A are preferably strontium titanate. Strontium titanate has the above-mentioned volume resistivity and relative dielectric constant, and also has high thermal conductivity, so that it easily transfers heat to the wax near the surface of the toner particles during fixing, and tends to produce a toner with excellent low-temperature fixing properties.

It is preferable that the inorganic microparticles contain other microparticles in addition to the above-mentioned microparticle A.

Other examples of fine particles include silica fine particles. Examples of silica fine particles include wet silica particles produced by the precipitation method or sol-gel method, and dry silica particles produced by the deflagration method or fumed method. From the viewpoint of dispersibility on the surface of the toner particles, wet silica particles produced by the sol-gel method or the like are preferred.

To make it easier to obtain a toner with excellent developing properties, it is preferable that the ratio of the mass of inorganic fine particles to the mass of toner particles is 0.10 to 2.00% by mass. More preferably, it is 0.10 to 1.00% by mass.

In addition, since it is easy to obtain a toner with excellent developing properties, the ratio of the mass of fine particles A to the mass of the toner particles is preferably 0.10 to 1.00 mass %, and more preferably 0.15 to 0.25 mass %.

<Number average particle size of fine particles A>
When the number average particle diameter of the fine particles A is A2, it is preferable that A2 is 10 to 80 nm. When A2 is within the above range, the particle diameter of the fine particles A is sufficiently small and the fine particles A easily move on the surface of the toner particles. This is preferable because when an electric field is applied to the toner, the fine particles A easily exist in the parts of the surface of the toner particles where the electric field is strong.

In order to prevent development streaks from occurring in a fixed image, it is preferable that the number average major axis A1 of the wax domains in the vicinity of the surface of the toner particles and the number average particle diameter A2 of the fine particles A satisfy the following formula (1).
0.3≦A2/A1≦1.2 (1)

<Migration index of fine particles A>
The fine particles A preferably have a migration index to a polycarbonate film of 3.5 to 6.5, as calculated by the following formula (2). The measurement method will be described later.
Migration index for polycarbonate film=area ratio of fine particles A migrated to polycarbonate film [X1]/coverage ratio of fine particles A on the surface of toner particle [X2]×100 (2)

The migration index is a value indicating the ease with which fine particles A migrate to the polycarbonate film, and the larger the value, the easier it is to detach from the toner matrix and migrate to other components. It is presumed that if the migration index is 3.5 or more, the adhesion force of fine particles A to the toner particles is unlikely to be excessive, and fine particles A are likely to be contained in positions on the surface of the toner particles where the electric field is strong. Also, if the migration index is 6.5 or less, the adhesion force of inorganic fine particles to the toner particles is unlikely to be too small, and a toner with excellent fluidity is likely to be obtained.

The migration index of the inorganic fine particles can be controlled by the temperature when the inorganic fine particles are added to the toner particles. The higher the temperature when the particles are added, the lower the migration index, and the lower the temperature when the particles are added, the higher the migration index.

<Weight average particle diameter of toner particles (D4)>
The weight average particle diameter (D4) of the toner particles is preferably 5.0 to 10.0 μm. When the weight average particle diameter (D4) of the toner particles is in the above range, the charge stability, fixability, and developability of the toner are easily maintained appropriately. More preferably, the D4 of the toner particles is 5.0 to 9.0 μm.

The weight average particle diameter (D4) of the toner particles can be controlled by the grinding conditions when the toner is produced by a grinding method. When the toner is produced in an aqueous medium, it can be controlled by the amount of dispersion stabilizer, the rotation speed of the stirrer, etc.

<Resin Component>
The resin component is preferably a binder resin, that is, the toner particles preferably contain a binder resin and a wax.

There are no particular limitations on the resin contained in the resin component, and the following can be used, for example:

Homopolymers of styrene and its substitutes such as polystyrene and polyvinyltoluene; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, and other styrene-based copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester, polyamide resin, epoxy resin, and polyacrylic acid resin. These can be used alone or in combination. Among these, styrene-acrylic resins such as styrene-butyl acrylate copolymer are particularly preferred from the viewpoints of development characteristics, fixability, and the like. It is also preferable that the content of styrene acrylic resin in the resin component is 80.0 to 100.0 mass%.

<Styrene acrylic resin>
Examples of the polymerizable monomer corresponding to the monomer unit constituting the styrene-acrylic resin include the following.

As styrene-based polymerizable monomers, styrene; α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-ethylstyrene, and other styrene-based polymerizable monomers.

Acrylic polymerizable monomers include methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, cyclohexyl acrylate, and phenyl acrylate.

Methacrylic polymerizable monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, n-octyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

Other monomers include acrylonitrile, methacrylonitrile, acrylamide, etc.

The method for producing the styrene-acrylic resin is not particularly limited. The resin component may also be a combination of resins other than the styrene-acrylic resin.

<Polyester P>
The toner particles have a core containing a resin component and a wax, and a shell covering the surface of the core. The shell preferably contains a polyester P having a monomer unit represented by the following formula (3).

A toner with excellent developability is easily obtained by using a shell containing a polyester having an isosorbide-derived monomer unit represented by formula (3). The present inventors speculate on the mechanism behind this as follows.

Wax is generally highly hydrophobic, so it is believed that the areas where wax is present near the surface of the toner particles have little interaction with moisture in the air. As a result, especially in high humidity environments, differences in charge amount are likely to occur between areas where wax is not present near the surface of the toner particles.

In contrast, the above-mentioned monomer unit derived from isosorbide has high water absorption, and toner particles having a shell containing polyester P having this monomer unit are likely to have a strong interaction with moisture in the air, even in the area where the wax is present near the surface. This is thought to make it easier to alleviate uneven charging in the toner particles. As a result, the inventors speculate that it will be easier to obtain a toner with excellent developability.

Polyesters can be produced, for example, by a method utilizing a dehydration condensation reaction from a carboxylic acid compound and an alcohol compound, or by an ester exchange reaction. Catalysts include acidic or alkaline catalysts used in esterification reactions. Examples include zinc acetate and titanium compounds.

The alcohol component in the polyester P is preferably 43 to 57 mol %, and the carboxylic acid component in the polyester P is preferably 57 to 43 mol %.

Polyester is a resin composed of an alcohol component and a carboxylic acid component, and examples of both components are given below.

Examples of alcohol components include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, cyclohexanedimethanol, butenediol, octenediol, cyclohexenedimethanol, hydrogenated bisphenol A, bisphenol and its derivatives represented by the following formula (A); diols represented by the following formula (B), etc.

(In formula (A), R is (--CH ₂ -CH ₂ -) or (--CH ₂ -CH ₂ -CH ₂ -). x and y are each an integer of 1 or more, and the average value of x+y is 2 to 10.)

(In formula (B), R' is any one of (B1) to (B3) above. x' and y' are integers of 1 or more, and the average value of x'+y' is 2 to 10.)
The alcohol component of the polyester P preferably contains a bisphenol represented by formula (A) and a derivative thereof. It is more preferable that the average value of x+y in formula (A) is 1 to 4. It is more preferable that R in formula (A) is (-CH ₂ -CH ₂ -).

Similarly, it is preferable that the alcohol component of polyester P contains ethylene glycol.

Examples of the carboxylic acid component include benzenedicarboxylic acids or their anhydrides, such as phthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, diphenyl-P.P'-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, diphenylmethane-P.P'-dicarboxylic acid, benzophenone-4,4'-dicarboxylic acid, and 1,2-diphenoxyethane-P.P'-dicarboxylic acid; alkyldicarboxylic acids or their anhydrides, such as succinic acid, adipic acid, sebacic acid, azelaic acid, glutaric acid, cyclohexanedicarboxylic acid, triethylenedicarboxylic acid, and malonic acid; succinic acid or its anhydride substituted with an alkyl group or alkenyl group having 6 to 18 carbon atoms; and unsaturated dicarboxylic acids or their anhydrides, such as fumaric acid, maleic acid, citraconic acid, and itaconic acid.

Among the above, it is preferable that the carboxylic acid component of polyester P contains terephthalic acid.

In the present disclosure, polyester P can be obtained by synthesis from a dicarboxylic acid and a diol, but in some cases, a trivalent or higher polycarboxylic acid or polyol may be used.

The content of polyester P in the resin component is preferably 0.1 to 10.0% by mass.

<Various additives>
If necessary, the toner may contain one or more additives selected from a colorant, a release agent, a magnetic material, a charge control agent, a fluidizing agent, etc. Various additives used in the toner will be specifically described.

<Coloring Agent>
Examples of black colorants include carbon black, magnetic materials, and those toned black using the yellow, magenta, and cyan colorants described below.

Yellow colorants include monoazo compounds, disazo compounds, condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

Magenta colorants include monoazo compounds, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.

Cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds.

<Magnetic material>
The toner may be a magnetic toner, that is, the toner particles may contain a magnetic material.

The magnetic material is preferably one whose main component is magnetic iron oxide such as triiron tetroxide or gamma-iron oxide, and contains elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. That is, the magnetic material contained in the toner particles is preferably iron oxide. The shape of the magnetic material may be polyhedral, octahedral, hexahedral, spherical, needle-like, or scaly, but shapes with little anisotropy such as polyhedral, octahedral, hexahedral, or spherical shapes are preferred in terms of increasing image density. In addition, the magnetic material is preferably one that has been subjected to a hydrophobic surface treatment.

It is also preferable that the content of magnetic material in the toner particles is 25.0 to 45.0% by mass.

It is also preferable that the number-average particle diameter of the magnetic material is 0.10 to 0.40 μm. If the number-average particle diameter is 0.10 μm or more, the magnetic material itself is less likely to become a reddish black, making it easier to obtain high-quality images. On the other hand, if the number-average particle diameter is 0.40 μm or less, the toner has good coloring power and is easier to disperse uniformly within the toner particles.

The number-average particle size of the magnetic material can be measured using a transmission electron microscope. Specifically, the toner to be observed is thoroughly dispersed in epoxy resin, and then cured for two days in an atmosphere at a temperature of 40°C to obtain a cured product. The cured product is cut into thin slices using a microtome, and the particle sizes of 100 magnetic powder particles in the field of view are measured using a transmission electron microscope (TEM) at a magnification of 10,000 to 40,000 times. The number-average particle size is then calculated based on the equivalent diameter of a circle equal to the projected area of the magnetic powder. It is also possible to measure the particle size using an image analyzer.

<Charge Control Agent>
Examples of negatively charged charge control agents include the following.

Monoazo metal compounds, acetylacetone metal compounds. Aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic acids and dicarboxylic acid-based metal compounds. Aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids, as well as their metal salts, anhydrides and esters. Phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarenes, resin-based charge control agents.

Positively charged charge control agents include the following:

Nigrosine and nigrosine modified with fatty acid metal salts, etc.; guanidine compounds; imidazole compounds; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts, which are analogues of these, and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (lake agents include phosphotungstic acid, phosphomolybdic acid, phosphotungstomolybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.); metal salts of higher fatty acids; diorgano tin oxides such as dibutyltin oxide, dioctyltin oxide, and dicyclohexyltin oxide; diorgano tin borates such as dibutyltin borate, dioctyltin borate, and dicyclohexyltin borate; and resin-based charge control agents.

These can be used alone or in combination of two or more types.

Among the above, metal-containing salicylic acid compounds are preferred, and those in which the metal is aluminum or zirconium are more preferred. Aluminum salicylate compounds are even more preferred.

Similarly, among the above, it is preferable to use a polymer or copolymer having a sulfonic acid group, a sulfonate group or a sulfonate ester group, a salicylic acid moiety, or a benzoic acid moiety.

The content of the charge control agent is preferably 0.01 parts by mass or more and 20.0 parts by mass or less, and more preferably 0.05 parts by mass or more and 10.0 parts by mass or less, per 100.0 parts by mass of the resin component.

<Toner Manufacturing Method>
The toner may be produced by any method, such as a pulverization method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension method, etc., but is not limited thereto. Since the state of existence of the wax contained in the toner particles can be easily controlled, the toner is preferably produced by a suspension polymerization method.

The cooling step and annealing step are also described below as preferred steps in the manufacturing method for producing the toner of the present disclosure.

As a cooling step, it is preferable to carry out a cooling step in which the temperature is lowered from the cooling start temperature to the cooling end temperature before sending the dispersion liquid of toner particles after the volatile component removal step to the next step. It is believed that the ease of formation of crystal nuclei of wax domains in the toner particles can be controlled by the conditions of the cooling step. The cooling conditions can be changed by changing the cooling start temperature, cooling rate, and cooling end temperature.

When the crystallization peak temperature of the wax is Ta, it is preferable that the toner manufacturing method has a holding step of holding the dispersion of toner particles at Ta+15 (°C) to Ta+35 (°C). It is presumed that by having a step of holding the toner particles in this temperature range, the fluidity of the wax in the toner particles is improved, making it easier to disperse the wax in the toner particles.

It is also preferable to have a cooling step in which the dispersion liquid that has undergone the above-mentioned holding step is cooled from the cooling start temperature to the cooling end temperature at a cooling rate of 40.0 to 200.0°C/min.

It is presumed that if the cooling rate is within the above range, the wax crystallizes sufficiently quickly upon cooling, making it easier to form crystal nuclei of wax domains within the toner particles. It is more preferable that the cooling rate is 100.0 to 140.0°C/min.

It is preferable that the cooling start temperature is between Ta+15 (°C) and Ta+35 (°C), and the cooling end temperature is between Ta-35 (°C) and Ta-20°C.

It is preferable that the cooling start temperature is within the above range, since the wax is easily melted in the toner particles and easily dispersed throughout the toner particles.

When the cooling temperature is within the above range, the wax in the toner particles crystallizes quickly, which is thought to facilitate the formation of many wax crystal nuclei in the toner particles. Since many crystal nuclei are formed, it is thought that the wax domains are more likely to be inhibited from crystallizing and coalescing, and fine wax domains are more likely to be formed.

It is preferable to carry out an annealing process on the dispersion liquid that has been through the cooling process in order to promote the crystallization of the wax. It is assumed that the annealing process makes it easier to microcrystallize the wax around the crystal nuclei formed in the cooling process.

The conditions for the annealing process can be determined by the annealing temperature and annealing time. As for the annealing temperature and annealing time, it is preferable to hold the dispersion liquid at Ta-35 (°C) to Ta-20 (°C) for 30 minutes or more. It is also preferable that the annealing process time is 150 minutes or less.

In addition, it is preferable to have an external addition step in which, after removing the toner particles from the dispersion liquid that has been subjected to the annealing step, the toner particles are mixed with inorganic fine particles at Ta-35 (°C) to Ta-20 (°C). It is presumed that by externally adding inorganic fine particles to the toner particles within the above temperature range, the uncrystallized wax present near the surface of the toner particles is more likely to form a large number of crystal nuclei due to the impact from the inorganic fine particles. As a result, the inventors presume that minute wax domains are more likely to be formed near the surface of the toner particles. In addition, it is preferable that the rotation speed during mixing in the external addition step is 1500 to 2500 rpm.

Toner produced through the above manufacturing process is preferred because R1 and A1 tend to satisfy the above preferred ranges.

That is, the method for producing the toner comprises the steps of:
(i) forming particles containing a polymerizable monomer and a wax in an aqueous medium;
(ii) obtaining a dispersion liquid containing toner particles containing a wax and a resin component obtained by polymerizing the polymerizable monomer contained in the particles;
(iii) a holding step of holding the dispersion at Ta+15 (°C) to Ta+35 (°C), where Ta is the crystallization peak temperature of the wax; (iv) a cooling step of cooling the dispersion from Ta+15 (°C) to Ta+35 (°C) to Ta-35 (°C) to Ta-20 (°C) at a cooling rate of 40.0 to 200.0°C/min;
(v) an annealing step of holding the dispersion liquid having been subjected to the cooling step at Ta-35 (°C) to Ta-20 (°C) for 30 minutes or more;
(vi) a step of extracting the toner particles from the dispersion liquid that has been subjected to the annealing step; and (vii) an external addition step of externally adding inorganic fine particles to the toner particles extracted in the extracting step at Ta-35 (° C.) to Ta-20 (° C.),
The inorganic fine particles contain fine particles A,
The volume resistivity of the fine particles A is 1.0×10 ³ to 3.0×10 ⁵ Ω·cm;
In the method for producing a toner, the fine particles A preferably have a relative dielectric constant εr of 100 or more.

When multiple types of wax are contained in the toner particles, the above value of Ta is the crystallization peak temperature of the wax that is contained in the toner particles at the highest ratio.

<Various measurement methods, etc.>
Various measurement methods etc. are described below.

<Method for measuring the occupied area ratio of minute wax domains in the surface vicinity region of a toner particle>
(1) Observation of a toner cross section by STEM To observe crystalline materials such as wax inside a toner, a slice of the toner is prepared, stained with ruthenium tetroxide, and observed by STEM. By staining with ruthenium tetroxide, a contrast difference occurs between amorphous resins such as binder resins and crystalline materials such as wax during STEM observation. This makes it possible to easily distinguish and observe crystalline materials such as wax.

First, the toner is dispersed in a visible light curable resin (product name: Aronix LCR Series D-800, manufactured by Toagosei Co., Ltd.), and then cured by irradiating it with short wavelength light. The resulting cured product is cut using an ultramicrotome equipped with a diamond knife to prepare a 250 nm thin sample.

Next, the cut sample is magnified at a magnification of 40,000 to 50,000 using a transmission electron microscope (product name: electron microscope JEM-2800, manufactured by JEOL Ltd.) (TEM-EDX) to obtain a cross-sectional image of the toner particles.

The toner particles to be observed are selected as follows:

First, the cross-sectional area of the toner particle is calculated from the cross-sectional image of the toner particle, and the diameter of a circle having an area equal to that cross-sectional area (equivalent circle diameter) is calculated. Only images of the cross-sections of toner particles where the absolute value of the difference between this equivalent circle diameter and the weight average particle diameter (D4) of the toner particles is within 1.0 μm are observed.

(2) Binarization using image analysis software The wax domain portion of the TEM image is binarized using image analysis software. In the present disclosure, binarization was performed using ImageJ, which is image analysis software. The binarization conditions are automatically determined by a discriminant analysis method that can be selected in ImageJ by selecting [Image]-[Adjust]-[Auto Threshold]-[Method: Otsu]. However, when a material with a different brightness is observed other than the wax domain in the cross-sectional observation of the toner particle, a histogram of the brightness of the image is calculated, a threshold is determined by a discriminant analysis method, and binarization is performed using the upper and lower thresholds of the area including the wax domain.

As an example of measuring the wax domain area ratio in a specific region when observing the cross section of a toner particle, the following describes the measurement of the wax domain area ratio and the average number of wax domains in a region 600 nm inward from the surface of the toner particle.

Reopen the TEM image before binarization using ImageJ, select [Process] - [Find Edge], and extract the toner contour. From [Analyze] - [Set Measurements], select [centroid], then select [Analyze] - [Analyze Particles] to find the center of gravity of the toner particles, and find the length from this center of gravity to any toner contour. Select [Image] - [Scale] to scale the image so that the length to this contour is 600 nm shorter. Overlay the scaled image with the initial image of the binarized wax domain, and mask the area 600 nm or more from the surface of the toner particles.

(3) Method for measuring the occupied area ratio R1 of wax domains with major axes of 10 to 300 nm in the region from the surface of a toner particle to 600 nm (region near the surface of a toner particle) After completing the above binarization operation in Image J, select [Ferret's Diameter] and [Area] from [Analyze]-[Set Measurements], and then select [Analyze]-[Analyze Particles] to obtain the area and major axis of the wax domain, and calculate the total area of domains with major axes of 10 nm to 300 nm. In addition, the toner particle contour extraction images before and after reduction are used so that the entire region within 600 nm from the toner particle surface is binarized. The area of the region from the surface of the toner particle to 600 nm is obtained by selecting [Analyze] - [Analyze Particles], and the occupied area ratio of the wax domain with a major axis of 10 nm or more and 300 nm or less is obtained.

The above operation is performed on STEM cross-sectional images of 10 toner particles. The average occupied area ratio of the wax domains with a major axis of 10 nm or more and 300 nm or less is taken as R1, and the average number of the wax domains is taken as the number of the wax domains. In addition, the number average value A1 of the major axis of the wax domains can be calculated from the major axis obtained above.

When a wax domain, like wax domain 4 in Figure 1, straddles contour line 3, which is obtained by shrinking contour line 2 of the toner particle cross section in the direction of the center of gravity by a distance of 600 nm inward, the wax domain is not considered to be included in that region.

<Method of measuring dielectric constant and volume resistivity>
The dielectric constant and volume resistivity are values inherent to a material and can be calculated by the following measurements.

To measure the dielectric constant of the microparticles, an SI 1260 electrochemical interface (manufactured by Toyo Corporation) is used as the power source and ammeter, and a 1296 dielectric interface (manufactured by Toyo Corporation) is used as the current amplifier.

The measurement sample is prepared by heating and molding the sample into a disk shape with a thickness of 3.0 ± 0.5 mm using a tablet molder. A gold electrode is created in a circular shape with a diameter of 10 mm on the top and bottom surfaces of the sample using mask deposition.

Measurement electrodes are attached to the prepared measurement sample, and an AC voltage with a peak-to-peak voltage (Vp-p) of 100 mV is applied at a frequency of 0.1 MHz to measure the capacitance and impedance. The relative dielectric constant εr and volume resistivity ρv of the measurement sample are calculated from the following formulas.
・εr=dC/ _ε0S
ρv=ZS/d
d: thickness of the measurement sample (m)
C: Capacitance (F)
ε ₀ : Dielectric constant of vacuum (F/m)
S: Electrode area (m ² )
Z: Impedance (Ω)
<Measurement of Number Average Particle Size A2 of Fine Particles A Contained on the Surface of Toner Particles>
The number average particle diameter of fine particles A is measured using a scanning electron microscope "S-4800" (manufactured by Hitachi High-Technologies Corporation). The toner to which inorganic fine particles have been externally added is observed, and the number average particle diameter is determined by measuring the major axis of 100 randomly selected fine particles A in a field of view magnified up to 50,000 times. The observation magnification is appropriately adjusted depending on the size of the inorganic fine particles. By specifying the circle equivalent diameter and circularity of fine particles A externally added to the toner particles in advance and setting these values, it is possible to extract only the number average particle diameter of fine particles A.

<Method for measuring the migration index of fine particles A>
As a method for indexing the adhesion state of the fine particles A, the migration amount of the fine particles A when the toner is brought into contact with the substrate is evaluated. As a material for the surface layer of the substrate, in this disclosure, a substrate using a polycarbonate resin as a surface layer material is used as a substrate simulating the surface layer of a photoreceptor. Specifically, first, a bisphenol Z type polycarbonate resin (product name: Iupilon Z-400, manufactured by Mitsubishi Engineering Plastics Corporation, viscosity average molecular weight (Mv): 40000) is dissolved in toluene to a concentration of 10 mass % to prepare a coating liquid.

This coating liquid is applied to an aluminum sheet with a thickness of 50 μm using a No. 50 Meyer bar to form a coating film. This coating film is then dried at 100°C for 10 minutes to produce a sheet having a polycarbonate resin layer (film thickness 10 μm) on the aluminum sheet. This sheet is held by a substrate holder. The substrate is a square with each side measuring approximately 3 mm.

Below, the measurement process is explained by dividing it into the process of placing the toner on the substrate, the process of removing the toner from the substrate, and the process of quantifying the amount of adhesion of the fine particles A supplied to the substrate.

- Step of placing toner on substrate Toner is contained in a porous soft material (hereinafter referred to as "toner holder"), and the toner holder is brought into contact with the substrate. A sponge (product name: White Wiper, manufactured by Marusan Sangyo Co., Ltd.) is used as the toner holder. The toner holder is fixed to the tip of a load meter fixed to a stage that moves in a direction perpendicular to the contact surface of the substrate, so that the toner holder and substrate can come into contact while measuring the load. The contact between the toner holder and substrate is achieved by moving the stage and pressing the toner holder against the substrate until the load meter indicates 10 N, and then separating the toner holder from the substrate, which is repeated five times.

- Step of removing toner from the substrate After the toner holder is brought into contact with the substrate, an elastomer suction port with an inner diameter of about 5 mm connected to the tip of the nozzle of a vacuum cleaner is brought close to the substrate perpendicular to the toner placement surface, and the toner adhering to the substrate is removed. At this time, the amount of remaining toner is visually confirmed while removing the toner. The distance between the end of the suction port and the substrate is 1 mm, the suction time is 3 seconds, and the suction pressure is 6 kPa.

- Step of quantifying the amount of adhesion of fine particles A supplied to the substrate When quantifying the amount and shape of fine particles A remaining on the substrate after removing the toner, observation and image measurement using a scanning electron microscope are used. First, platinum is sputtered on the substrate after removing the toner under conditions of a current of 20 mA and 60 seconds to obtain a specimen for observation. Using the above scanning electron microscope, observation was performed using a reflected electron image obtained from the specimen for observation. The observation magnification was 50,000 times, the acceleration voltage was 10 kV, and the working distance was 3 mm. In the image obtained by observation, inorganic fine particles are represented with high brightness and the substrate with low brightness, so that the amount of fine particles A in the field of view can be quantified by binarization. The conditions for binarization are automatically determined by a discriminant analysis method included in [Auto Threshold] of ImageJ. In this disclosure, image analysis software Image J was used for binarizing the observed image. The area ratio of fine particle A in the observation field is calculated by integrating only the area of fine particle A in Image J and dividing by the area of the entire observation field. The circle equivalent diameter and circularity of fine particle A externally added to the toner particles are specified in advance, and by setting these values, it is possible to extract only the area of fine particle A. The above measurement is performed on 100 binarized images, and the average value is taken as the area ratio [X1] (unit: area %) of fine particle A on the substrate.

Next, the coverage rate of fine particle A on the toner particles [X2] (unit: area %) is calculated. The coverage rate of fine particle A is measured using the above-mentioned scanning electron microscope observation and image measurement. When observing fine particle A with a scanning electron microscope, the observation magnification used is the same as the magnification used to observe fine particle A on the substrate.

The steps to calculate the transition index are shown below.

(1) Sample preparation: Apply a thin layer of conductive paste to a sample stage (aluminum sample stage 15 mm x 6 mm), then spray toner onto the paste. Use air to remove excess toner from the sample stage and allow to dry thoroughly. Set the sample stage in the sample holder, and adjust the sample stage height to 36 mm using the sample height gauge.

(2) Setting of observation conditions for S-4800 The coverage rate [X2] of fine particles A is calculated using an image obtained by observing a backscattered electron image with the S-4800. Backscattered electron images have less charge-up than secondary electron images, so the coverage rate [X2] of fine particles A can be measured with high accuracy.

Pour liquid nitrogen into the anti-contamination trap attached to the S-4800 housing until it overflows, and leave it for 30 minutes. Start the S-4800's "PC-SEM" and perform flushing (cleaning the FE chip, which is the electron source). Click the acceleration voltage display area on the control panel on the screen, and press the [Flushing] button to open the flushing execution dialog. Check that the flushing intensity is 2 and execute it. Check that the emission current due to flushing is 20 to 40 μA. Insert the sample holder into the sample chamber of the S-4800 housing. Press [Origin] on the control panel to move the sample holder to the observation position. Click the acceleration voltage display area to open the HV setting dialog, and set the acceleration voltage to [0.8 kV] and the emission current to [20 μA]. In the [Basic] tab of the operation panel, set the signal selection to [SE], select [Upper (U)] and [+BSE] for the SE detector, and select [L. A. 100] and switch to the backscattered electron image observation mode.

Also on the [Basic] tab of the operation panel, set the probe current in the electron optical system condition block to [Normal], the focus mode to [UHR], and the WD to [3.0 mm]. Press the [ON] button on the acceleration voltage display section of the control panel to apply the acceleration voltage.

(3) Focus adjustment Drag within the magnification display area on the control panel to set the magnification to 5000 (5k). Rotate the focus knob [COARSE] on the operation panel to adjust the aperture alignment when the entire field of view is in focus to some extent. Click [Align] on the control panel to display the alignment dialog and select [Beam]. Rotate the STIGMA/ALIGNMENT knobs (X, Y) on the operation panel to move the displayed beam to the center of the concentric circles. Next, select [Aperture] and rotate the STIGMA/ALIGNMENT knobs (X, Y) one by one to stop the image movement or adjust it so that it moves as little as possible. Close the aperture dialog and adjust the focus using autofocus. Repeat this operation two more times to adjust the focus.

Next, for the target toner, align the midpoint of the maximum diameter with the center of the measurement screen, and drag within the magnification display on the control panel to set the magnification to 10,000 (10k). Rotate the focus knob [COARSE] on the operation panel, and once the image is in focus to a certain extent, adjust the aperture alignment. Click [Align] on the control panel to display the alignment dialog, and select [Beam]. Rotate the STIGMA/ALIGNMENT knobs (X, Y) on the operation panel to move the displayed beam to the center of the concentric circles.

Next, select [Aperture] and turn the STIGMA/ALIGNMENT knobs (X, Y) one by one to stop the image movement or adjust it so that it moves as little as possible. Close the Aperture dialog and use autofocus to adjust the focus. After that, set the magnification to 50,000 (50k)x and use the focus knob and STIGMA/ALIGNMENT knob to adjust the focus as above, then use autofocus to adjust the focus again. Repeat this operation to adjust the focus. Here, if the tilt angle of the observation surface is large, the accuracy of the coverage measurement is likely to be low, so when adjusting the focus, select one that brings the entire observation surface into focus at the same time, and select one with as little surface tilt as possible for analysis.

(4) Image storage Adjust the brightness in ABC mode, take a photograph with a size of 640 x 480 pixels, and save it. Use this image file to perform the following analysis. Take one photograph for each toner particle, and obtain images for at least 100 toner particles.

The observed image is binarized using the image analysis software Image J. After binarization, the circle equivalent diameter and circularity of the corresponding fine particle A are set from [Analyze] - [Analyze Particles] to extract only the fine particle A, and the coverage rate (unit: area %) of the fine particle A on the surface of the toner particles is calculated. The above measurement is performed on 100 binarized images, and the average value of the coverage rate (unit: area %) of fine particle A is taken as the coverage rate [X2] of fine particle A.

The migration index of particle A is calculated using the following formula from the area ratio [X1] of particle A on the substrate and the coverage rate [X2] of particle A.

Transfer index of particle A=area ratio of particle A on substrate [X1]/coverage ratio of particle A [X2]×100
Observation of the presence or absence of a shell on toner particles
The presence or absence of a shell in a toner particle can be observed by observing the cross-sectional shape of the toner particle. A specific method for observing the cross-sectional shape of a toner particle is as follows.

First, toner particles are thoroughly dispersed in a photocurable epoxy resin, and then the epoxy resin is cured by irradiating it with ultraviolet light to obtain a cured product. The cured product is cut using a microtome equipped with a diamond blade to prepare a thin flake sample with a thickness of 100 nm. The sample is dyed with ruthenium tetroxide as necessary, and then a transmission electron microscope (TEM) (product name: Tecnai TF20XT electron microscope, manufactured by FEI) is used to observe the cross section of the toner at an acceleration voltage of 120 kV to obtain a TEM image.

In the above observation method, if a shell is present and the core and shell are of different components, differences in the staining state and contrast due to element mapping are observed. The observation magnification is 20,000 times.

<Detection of isosorbide-derived monomer units present on the surface of toner particles>
To detect the isosorbide-derived monomer units present on the surface of the toner particles, a TOF-SIMS (TRIFT-IV, manufactured by ULVAC-PHI, Inc.) is used. The analysis conditions are as follows.

Sample preparation: Adhere the toner particles to an indium sheet.

Sample pretreatment: None Primary ion: Au+
Acceleration voltage: 30 kV
Charge neutralization mode: On
Measurement mode: Positive
Raster size: 100 μm
Accumulation time: 180 seconds By carrying out the above measurement, it is possible to detect the polyester P having a monomer unit derived from isosorbide present on the surface of the toner particles. By confirming the presence of the shell of the toner particles by observation and carrying out the measurement, it is possible to determine whether the shell contains the polyester P.

<Method of measuring the crystallization peak temperature of a sample>
The crystallization peak temperature of the sample is measured using a differential scanning calorimeter "Q2000 (manufactured by TA Instruments)" in accordance with ASTM D3418-82.

The melting points of indium and zinc are used to correct the temperature of the device's detection section, and the heat of fusion of indium is used to correct the amount of heat.

Specifically, 2 mg of sample is weighed out and placed in an aluminum pan, and an empty aluminum pan is used as a reference.

The measurement temperature range is -10°C to 200°C, and the measurement is performed at a heating rate of 10°C/min. During the measurement, the temperature is first raised from -10°C to 200°C at a heating rate of 10°C/min, and then lowered from 200°C to -10°C at a heating rate of 10°C/min.

Then, the temperature is increased again from -10°C to 200°C at a rate of 10°C/min.

The crystallization peak temperature is obtained from the DSC curve in the range of temperatures from 200°C to -10°C during the first cooling step.

In the DSC curve during the first cooling, the temperatures before and after the specific heat change are used as the baseline, and the temperature at which the peak height is the highest is the crystallization peak temperature of the sample.

<Method of measuring weight average particle diameter (D4) of toner particles>
The weight average particle diameter (D4) of the toner particles is measured as follows.

The measuring device used is a precision particle size distribution measuring device using the pore electrical resistance method, the Coulter Counter Multisizer 3 (registered trademark, manufactured by Beckman Coulter, Inc.), equipped with a 100 μm aperture tube. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software, Beckman Coulter Multisizer 3 Version 3.51 (manufactured by Beckman Coulter, Inc.). The measurement is performed using an effective measurement channel count of 25,000.

The aqueous electrolyte solution used for the measurements is one in which special grade sodium chloride is dissolved in ion-exchanged water to give a concentration of 1% by mass, for example "ISOTON II" (manufactured by Beckman Coulter).

Before performing measurements and analysis, configure the dedicated software as follows:

On the "Change Standard Measurement Method (SOM)" screen of the dedicated software, set the total count number in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (manufactured by Beckman Coulter). Press the "Threshold/Noise Level Measurement Button" to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement."

In the dedicated software's "Pulse to particle size conversion setting" screen, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm to 60 μm.

The specific measurement method is as follows:

(1) Pour 200 mL of electrolyte solution into a 250 mL round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture tube flush" function of the dedicated software to remove dirt and air bubbles from inside the aperture tube.

(2) Put 30 mL of the electrolyte solution into a 100 mL flat-bottom glass beaker. Add 0.3 mL of a solution of "Contaminon N" (a 10% aqueous solution of a neutral detergent for cleaning precision measuring instruments with a pH of 7, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted 3 times by mass with ion-exchanged water as a dispersant.

(3) Prepare an ultrasonic disperser "Ultrasonic Dispersion System Tetorara 150" (manufactured by Nikkaki Bios Co., Ltd.) that has two built-in oscillators with an oscillation frequency of 50 kHz and a phase shift of 180 degrees and an electrical output of 120 W. Place 3.3 L of ion-exchanged water in the water tank of the ultrasonic disperser, and add 2 mL of Contaminon N to this water tank.

(4) Place the beaker from (2) above into the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the electrolyte solution surface in the beaker is maximized.

(5) While the electrolyte solution in the beaker in (4) is being irradiated with ultrasonic waves, 10 mg of toner particles are added little by little to the electrolyte solution and dispersed. Then, ultrasonic dispersion processing is continued for another 60 seconds. During ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted so that it is between 10°C and 40°C.

(6) Using a pipette, drip the electrolyte solution (5) in which the toner particles have been dispersed into the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to 5%. Then, measurements are continued until the number of particles measured reaches 50,000.

(7) The measurement data is analyzed using the dedicated software that comes with the device, and the weight average particle diameter (D4) is calculated. Note that when the dedicated software is set to Graph/Volume %, the "Average diameter" on the "Analysis/Volume Statistics (Arithmetic Mean)" screen is the weight average particle diameter (D4) of the toner particles.

The present disclosure will be explained in more detail below with reference to examples and comparative examples, but the present disclosure is in no way limited thereto. Parts used in the examples are by weight unless otherwise specified.

<Production example of magnetic material (a type of black colorant)>
An aqueous solution containing ferrous hydroxide was prepared by mixing 1.0 equivalent of an aqueous solution of sodium hydroxide relative to the iron ions (containing 1% by mass of sodium hexametaphosphate calculated as P relative to Fe) into an aqueous solution of ferrous sulfate. While maintaining the pH of the aqueous solution at 9, air was blown in and an oxidation reaction was carried out at 80°C to prepare a slurry liquid for producing seed crystals.

Next, an aqueous solution of ferrous sulfate was added to the slurry in an amount equivalent to 1.0 relative to the initial amount of alkali (sodium component of sodium hydroxide). The pH of the slurry was maintained at 8, and the oxidation reaction was allowed to proceed while blowing in air, and the pH was adjusted to 6 at the end of the oxidation reaction. Thereafter, 1.5 parts by mass of n-C ₆ H ₁₃ Si(OCH ₃ ) ₃ was added as a silane coupling agent relative to 100 parts by mass of iron oxide, and the mixture was thoroughly stirred, followed by washing, filtration, and drying to obtain hydrophobic iron oxide particles. The aggregated hydrophobic iron oxide particles were crushed, and then heat-treated at a temperature of 70° C. for 5 hours to obtain magnetic substance 1. The number-average particle size of magnetic substance 1 was 0.25 μm.

<Production Example of Polyester P1>
Terephthalic acid: 29.9 parts by mass Bisphenol A-propylene oxide 2 mole adduct: 48.5 parts by mass Isosorbide: 1.2 parts by mass Ethylene glycol: 4.5 parts by mass Tetrabutoxytitanate: 0.125 parts by mass The above materials were charged into an autoclave equipped with a pressure reducing device, a water separating device, a nitrogen gas introducing device, a temperature measuring device, and a stirrer, and reacted under a nitrogen atmosphere at normal pressure and 200°C for 5 hours.

2.1 parts by mass of trimellitic acid and 0.120 parts by mass of tetrabutoxytitanate were then added, and the mixture was reacted at 220°C for 3 hours, and then further reacted for 2 hours under reduced pressure of 10 to 20 mmHg to obtain polyester P1.

(Production Example of Polyester P2)
Polyester P2 was obtained by carrying out the same operation as in Production Example of Polyester P1, except that isosorbide was omitted from Production Example of Polyester P1.

<Production Example of Wax 1>
Stearic acid 100.00 parts by mass Behenyl alcohol 48.00 parts by mass p-toluenesulfonic acid 0.50 parts by mass The above materials were added under reflux, and the esterification reaction was allowed to proceed for 6 hours at 120°C. During this time, the water produced was removed from the system by toluene/water azeotropy. After the reaction was completed, p-toluenesulfonic acid was neutralized with sodium hydrogen carbonate. The resulting solution was evaporated to remove toluene. The product was heated to 90°C and filtered through Celite to remove sodium p-toluenesulfonate, thereby obtaining Wax 1. The crystallization peak temperature of Wax 1 was measured by the above-mentioned measurement method and was found to be 65°C.

The type and physical properties of the fine particles A used in the following manufacturing examples are shown in Table 1. The number-average particle size A2, relative dielectric constant, and volume resistivity in Table 1 were measured using the above-mentioned measurement methods.

<Production Example of Toner Particle 1>
Styrene 78.0 parts by mass n-Butyl acrylate 22.0 parts by mass Polyester P1 3.0 parts by mass Magnetic material 1 80.0 parts by mass Negative charge control agent T-77 (manufactured by Hodogaya Chemical Co., Ltd.) 1.0 part by mass Wax 1 20.0 parts by mass The above materials were uniformly dispersed and mixed using an attritor (Nippon Coke & Engineering Co., Ltd.). Then, the mixture was heated to a temperature of 60°C, and 10.0 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) as a polymerization initiator was added and mixed/dissolved in the mixture to prepare a mixed solution containing a polymerizable monomer composition.

In addition, 450 parts by mass of a 0.1 mol/L _{Na3PO4 aqueous} solution was added to 720 parts by mass of ion-exchanged water while stirring at 33 m/s using Clearmix (M Technique Co., Ltd.).Then, the mixture was heated to a temperature of 60°C, and 67.7 parts by mass of a 1.0 mol/L _CaCl2 aqueous solution was added to obtain an aqueous medium containing a calcium phosphate compound.

The mixed solution was added to the aqueous medium, and the mixture was stirred at 33 m/s for 15 minutes under a nitrogen atmosphere at 60°C using Clearmix (M Technique Co., Ltd.) to granulate. The mixture was then stirred with a paddle stirring blade, the temperature was raised to 70°C, and a polymerization reaction was carried out for 300 minutes. After the polymerization reaction was completed, the suspension was heated to 100°C and held under reduced pressure for 2 hours to remove the residual monomer. Next, as a cooling process, the suspension was cooled from 95°C to 45°C at 120°C/min (cooling rate). After cooling, as an annealing process, the suspension was heated to 50°C (annealing temperature) and held for 120 minutes (annealing time). After the annealing process, hydrochloric acid was added to reduce the pH to 2.0 or less to dissolve and remove the calcium phosphate compound. After repeated water washing several times, the mixture was dried at 40°C for 72 hours using a dryer, and classified using a multi-division classifier utilizing the Coanda effect to obtain toner particles 1. The physical properties of toner particle 1 are shown in Table 2.

<Production Examples of Toner Particles 2 to 9>
Toner particles 2 to 9 were obtained in the same manner as in the production example of toner particle 1, except that the number of parts of wax, the type of polyester, the cooling rate, the annealing temperature, and the annealing time were changed as shown in Table 2. The physical properties of toner particles 2 to 9 are shown in Table 2.

The weight average particle diameter D4 in Table 2 was measured using the measurement method described above, and the presence or absence of a shell was confirmed by observation using the observation method described above.

<Production Example of Toner 1>
100.0 parts of toner particles 1 and 0.3 parts of octyltrimethoxysilane-treated sol-gel silica fine particles (number average particle size 115 nm) were added to an FM mixer (product name: FM10C, manufactured by Nippon Coke and Engineering Co., Ltd.) in which the treatment blade was changed from the rotor shown in FIG. 3 to the rotor shown in FIG. 2, and a first-stage external addition was performed in which the particles were mixed at 2000 rpm for 15 minutes, thereby obtaining toner precursor 1-1.

At this time, as soon as mixing began, hot and cold water was passed through the jacket appropriately to maintain the temperature inside the tank at 50°C.

Then, as the second-stage external addition, 100 parts of the above toner precursor 1-1 and 0.2 parts of fine particles A1 were added to the same FM mixer as that used for the first-stage external addition. Water was passed through the mixer so that the water temperature in the jacket was 7°C, and the mixer was mixed at 2400 rpm for 5 minutes to obtain toner precursor 1-2. At this time, the flow rate of water in the jacket was appropriately adjusted so that the temperature inside the FM mixer tank was 20°C. The obtained toner precursor 1-2 was then sieved through a mesh with 75 μm openings to obtain toner 1 (black toner). The physical properties of toner 1 are shown in Table 4.

The rotor shown in Figure 3 is the rotor that the FM10C has at the time of sale. In Figures 2 and 3, 140 and 150 are processing blades, 141 and 151 are the main body of the processing blade, and 142 and 152 are processing sections. In each figure, (a) is a top view, and (b) is a side view.

<Production Examples of Toners 2 to 19>
Toners 2 to 19 were obtained in the same manner as in the production example of Toner 1, except that the type of toner particles, the type and number of fine particles A, the first-stage external addition conditions, and the second-stage external addition conditions were changed as shown in Table 3. The physical properties of Toners 2 to 19 are shown in Table 4.

The physical properties of the toner listed in Table 4 were measured using the measurement method described above.

Example 1
Toner 1 was evaluated as follows. The evaluation results are shown in Table 5.

<Evaluation of low temperature fixability>
For the evaluation of low-temperature fixing property, a modified laser beam printer (product name: HP LaserJet Enterprise M609dn, manufactured by Hewlett-Packard Company) was used as the image forming apparatus. The modification of the image forming apparatus was to allow the fixing temperature of the fixing unit to be set arbitrarily. The paper used for image formation was white paper (product name: GF-C081, Canon Marketing Japan, Inc., 81.4 g/m ² ).

First, the toner inside the cartridge was removed and emptied, and then 300 g of toner 1 was filled into the cartridge.

In a low temperature, low humidity environment (7.5°C/15% RH), using the modified machine and white paper, the temperature of the fixing unit was adjusted in 5°C increments within the range of 170°C to 230°C, and halftone images were output at each temperature. At this time, the bias was adjusted so that the image density of the halftone image at each temperature was 0.60 to 0.65. The image density was measured using a Macbeth densitometer (manufactured by Macbeth Co.), which is a reflection densitometer, using an SPI filter.

Each halftone image obtained was rubbed five times back and forth with Silbon paper under a load of 4.9 kPa. The lowest fixing temperature that output an image in which the decrease in image density before and after rubbing was 15% or less was used to evaluate low-temperature fixability. Fixing temperatures of 190°C or less were determined to be those in which the effects of the present disclosure were achieved.

<Evaluation of Image Density>
The image density was evaluated using the image forming apparatus and white paper used in the evaluation of low-temperature fixability described above. The image forming apparatus used in the evaluation was not modified.

After printing 100 sheets of horizontal line patterns with a printing rate of 1% in a high temperature and high humidity environment (30.0°C, 80% RH), the device was stopped for 10 days. After that, a 5 mm x 5 mm solid black image was printed, and the image density of the solid black image was measured. The image density was measured using a Macbeth densitometer (manufactured by Macbeth) which is a reflection densitometer, and an SPI filter. In this measurement, an image density of 1.35 or more was determined to be one in which the effects of the present disclosure were obtained.

<Evaluation of Contamination in Non-Image Area>
After the above image density measurement, a solid white image was printed in a high temperature and high humidity environment (30.0°C/80% RH) and the image density (%) was measured. In addition, the image density (%) of a white paper that had not been printed was measured, and the difference (%) between these two image densities was calculated and used to evaluate the contamination of non-image areas by toner. The image density in this measurement was measured using a TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.), and the average value of the measurement results at five points was taken as the image density. In this measurement, an image density difference of less than 2.5% was judged to be a good result.

<Evaluation of development streaks>
After the above-mentioned evaluation of the staining of the non-image area, 100 sheets of solid white images were printed in a high temperature and high humidity environment (30.0°C/80% RH), and then a halftone image with a toner loading of 0.2 mg/ ^cm2 was created. Then, the halftone image and the developing roller were visually inspected and evaluated in that state. The evaluation criteria are shown below.

(Evaluation Criteria)
A: No streaks are observed on the developing roller or on the halftone image.

B: There are 1 to 3 small circumferential lines on the developing roller, but no lines are visible on the halftone image.

C: There are 1 to 3 fine circumferential lines on the developing roller, and 1 to 3 fine lines can also be seen on the halftone image.

D: Four or more streaks are visible on the developing roller and halftone image.

<Examples 2 to 14 and Comparative Examples 1 to 5>
The evaluation was carried out in the same manner as in Example 1. The evaluation results are shown in Table 5.

1 Micro wax domain 2 Contour line of the surface of a toner particle 3 Contour line reduced by a distance of 600 nm inward from the surface of a toner particle 4 Wax domain spanning the contour line reduced by a distance of 600 nm inward from the surface of a toner particle 5 Inorganic fine particles 140 Treatment blade 141 Main body of treatment blade 142 Treatment section 150 Treatment blade 151 Main body of treatment blade 152 Treatment section

Claims (14)

A toner comprising toner particles containing a resin component and a wax, and inorganic fine particles on the surfaces of the toner particles,
In the cross-sectional observation of the toner particle,
Domains comprising said wax are observed;
Among the observed domains, a domain having a major axis of 10 to 300 nm is designated as a domain S, and an occupied area ratio of the domain S in a region from the surface of the toner particle to 600 nm is designated as R1, the R1 being 3.0 to 15.0%,
The inorganic fine particles contain fine particles A,
The volume resistivity of the fine particles A is 1.0×10 ³ to 3.0×10 ⁵ Ω·cm;
The relative dielectric constant εr of the fine particles A is 100 or more,
the toner particles have a core containing the resin component and the wax, and a shell covering a surface of the core,
The shell contains a polyester P having a monomer unit represented by the following formula (3):
A toner characterized by:

A toner comprising toner particles containing a resin component and a wax, and inorganic fine particles on the surfaces of the toner particles,
the toner is a magnetic toner,
In the cross-sectional observation of the toner particle,
Domains comprising said wax are observed;
Among the observed domains, a domain having a major axis of 10 to 300 nm is designated as a domain S, and an occupied area ratio of the domain S in a region from the surface of the toner particle to 600 nm is designated as R1, the R1 being 3.0 to 15.0%,
The inorganic fine particles contain fine particles A,
The volume resistivity of the fine particles A is 1.0×10 ³ to 3.0×10 ⁵ Ω·cm;
The toner is characterized in that the fine particles A have a relative dielectric constant εr of 100 or more. In the cross-sectional observation of the toner particle,
3. The toner according to claim 1 , wherein a number average major axis A1 of all the domains in the region is 30 to 150 nm. In the cross-sectional observation of the toner particle,
The toner according to claim 1 , wherein when an occupied area ratio of all of the domains in the region is R2, the R2 is 3.0 to 25.0%. In the cross-sectional observation of the toner particle,
The toner according to claim 1 , wherein the number of the domains S in the region is 100 or more. The number average particle diameter of the fine particles A is A2,
In the cross-sectional observation of the toner particle,
When the number average major axis of all the domains in the region is A1,
The A1 and A2 satisfy the following formula (1): 0.3≦A2/A1≦1.2 (1)
The toner according to any one of claims 1 to 5 . The migration index of the fine particles A to the polycarbonate film, calculated by the following formula (2), is 3.5 to 6.5. Migration index to polycarbonate film=area ratio of fine particles A migrated to the polycarbonate film [X1]/coverage ratio of fine particles A on the surface of the toner particle [X2]×100 (2)
The toner according to any one of claims 1 to 6 . 8. The toner according to claim 1, wherein the fine particles A are strontium titanate. The toner according to any one of claims 1 to 8, wherein the relative dielectric constant εr of the fine particles A is 100 or more and 300 or less. The toner according to any one of claims 1 to 9, wherein the weight average particle diameter (D4) of the toner particles is 5.0 to 10.0 μm. The resin component contains a styrene-acrylic resin,
The toner according to any one of claims 1 to 10, wherein the content of the styrene-acrylic resin in the resin component is 80.0 to 100.0% by mass. The wax is an ester wax,
The toner according to any one of claims 1 to 11, wherein the content of the wax in the toner particles is 5.0 to 25.0% by mass. The toner according to any one of claims 1 to 12, wherein A2, which is a number average particle diameter of the fine particles A, is 10 to 80 nm. A method for producing a toner, comprising the steps of:
The manufacturing method comprises:
(i) forming particles containing a polymerizable monomer and a wax in an aqueous medium;
(ii) obtaining a dispersion liquid containing toner particles containing a wax and a resin component obtained by polymerizing the polymerizable monomer contained in the particles;
(iii) a holding step of holding the dispersion at Ta+15 (°C) to Ta+35 (°C), where Ta is the crystallization peak temperature of the wax; (iv) a cooling step of cooling the dispersion from Ta+15 (°C) to Ta+35 (°C) to Ta-35 (°C) to Ta-20 (°C) at a cooling rate of 40.0 to 200.0°C/min;
(v) an annealing step of holding the dispersion liquid having been subjected to the cooling step at Ta-35 (°C) to Ta-20 (°C) for 30 minutes or more;
(vi) a step of extracting the toner particles from the dispersion liquid that has been subjected to the annealing step; and (vii) an external addition step of externally adding inorganic fine particles to the toner particles extracted in the extracting step at Ta-35 (° C.) to Ta-20 (° C.),
The inorganic fine particles contain fine particles A,
The volume resistivity of the fine particles A is 1.0×10 ³ to 3.0×10 ⁵ Ω·cm;
The toner manufacturing method according to the present invention is characterized in that the fine particles A have a relative dielectric constant εr of 100 or more.

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