JP7010089B2 - Active energy ray-curable composition, active energy ray-curable inkjet ink and inkjet recording device - Google Patents

Description

The present invention relates to an active energy ray-curable composition, an active energy ray-curable inkjet ink, and an inkjet recording apparatus.

An inkjet recording method is known as a method of forming an image on a recording medium such as paper. The inkjet recording method has high ink consumption efficiency and excellent resource saving, and it is possible to keep the cost of ink per unit recording low.
In recent years, an inkjet recording method using an ultraviolet curable ink has attracted attention.

On the other hand, the coating film formed by the inkjet recording method is required to have high wear resistance depending on its usage state, and in order to solve this problem, for example, silica particles are added to an active energy ray-curable inkjet ink. The technique of adding is known (see, for example, Patent Document 1). However, the silica particles have a problem that they are severely settled due to aggregation and the intermittent ejection property is deteriorated. Further, there is a similar problem when an inorganic pigment is used as a coloring material. Further, for an active energy ray-curable inkjet ink using silica particles, there is a demand from the industry for further improvement in abrasion resistance and color unevenness of a coating film.

Therefore, an object of the present invention is to provide an active energy ray-curable composition which suppresses sedimentation due to aggregation of silica particles, improves intermittent ejection property and color unevenness of printed images, and has high coating hardness and excellent wear resistance. To provide.

The above problem is solved by the following configuration 1).
1) In an active energy ray-curable composition containing an inorganic pigment and silica particles,
The feature is that the volume average particle size of the silica particles is 1/10 to 1/3 of the volume average particle size of the inorganic pigment, and the surface of the silica particles is modified with a (meth) acrylate compound. An active energy ray-curable composition.

According to the present invention, there is provided an active energy ray-curable composition which suppresses sedimentation due to aggregation of silica particles, improves intermittent ejection property and color unevenness of printed images, and has high coating film hardness and excellent wear resistance. Will be done.

It is a schematic diagram which shows an example of the image forming apparatus in this invention. It is a schematic diagram which shows an example of another image forming apparatus in this invention. It is a schematic diagram which shows an example of still another image forming apparatus in this invention. It is external perspective view which shows an example of the ink ejection head in a printing apparatus. It is sectional drawing explanatory drawing of the direction orthogonal to the nozzle arrangement direction of the ink ejection head of FIG. It is a partial cross-sectional explanatory view of the direction parallel to the nozzle arrangement direction of the ink ejection head of FIG. It is a plane explanatory view of the nozzle plate of the ink ejection head of FIG. It is a plane explanatory view of each member constituting the flow path member of the ink ejection head of FIG. It is a plane explanatory view of each member constituting the common liquid chamber member of the ink ejection head of FIG. It is a block diagram which shows an example of the ink circulation system which concerns on this invention. It is a figure explaining the circulation of ink in an ink ejection head. It is a figure explaining the circulation of ink in an ink ejection head.

Hereinafter, the present invention will be described in more detail.
As a result of diligent studies to solve the above problems, the present inventor sets the volume average particle size of the silica particles to 1/10 to 1/3 of the volume average particle size of the inorganic pigment, and the silica particles. By using a compound whose surface is modified with a (meth) acrylate compound, the silica particles form a loosely aggregated state in the composition, suppress sedimentation due to aggregation, and improve intermittent ejection property and color unevenness of the printed image. Further, they have found that an active energy ray-curable composition having high coating film hardness and excellent wear resistance can be obtained, and have completed the present invention.

Further, as a result of further studies, by using the inkjet recording apparatus of the present invention described below, which is provided with a circulation mechanism in the ejection head, the formation of a loosely aggregated state of silica particles in the composition progresses and is dispersed. It was found that there is an effect of stabilizing, and in particular, it was found that the color unevenness of the printed image was reduced and a good image could be obtained.

The active energy ray-curable composition of the present invention contains an inorganic pigment and silica particles.

<Color material>
The active energy ray-curable composition of the present invention contains a coloring material. As the coloring material, various pigments that impart black, white, magenta, cyan, yellow, green, orange, glossy colors such as gold and silver, and the like are used according to the purpose and required characteristics of the composition in the present invention. be able to. The content of the coloring material may be appropriately determined in consideration of a desired color concentration, dispersibility in the composition, etc., and is not particularly limited, but is 0. It is preferably 1 to 20% by mass.
As the pigment, an inorganic pigment or an inorganic pigment and an organic pigment can be used in combination, and one type may be used alone or two or more types may be used in combination.
As the inorganic pigment, for example, carbon black (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, and titanium oxide can be used.
Examples of organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azolakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments and quinophthalones. Polycyclic pigments such as pigments, dye chelate (for example, basic dye type chelate, acidic dye type chelate, etc.), dyeing rake (basic dye type rake, acidic dye type rake), nitro pigment, nitroso pigment, aniline black, Daylight fluorescent pigments can be mentioned.

Further, in order to improve the dispersibility of the pigment, a dispersant may be further contained.
The dispersant is not particularly limited, and examples thereof include dispersants commonly used for preparing pigment dispersions such as polymer dispersants.

<Silica particles>
The silica particles used in the present invention need to have a volume average particle diameter of 1/10 to 1/3 of the volume average particle diameter of the pigment, and are 1 / from the viewpoint of enhancing dispersion stability. It is more preferably 10 to 1/5. The volume average particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The surface of the silica particles used in the present invention is modified with a (meth) acrylate compound.
When the silica particles satisfy the above requirements, a loosely aggregated state can be formed between the inorganic pigments. The loosely aggregated state can be controlled by adjusting the ratio of the volume average particle diameters of the silica particles and the inorganic pigment.

The volume average particle diameter of the silica particles is, for example, 10 nm to 100 nm, preferably 40 nm to 50 nm.

The type of silica particles is not particularly limited, but from the viewpoint of viscosity, a silica dispersion liquid which is synthesized by a wet method, has an organic surface treatment, and is solvent-substituted with an organic dispersion medium is preferable. Further, a silica dispersion obtained by mill-dispersing the silica powder while adding a surface treatment agent, a dispersant, or the like is also preferable.

Known methods can be applied to modify the surface of the silica particles with acrylate. For example, it can be carried out by using a silane coupling agent having an acrylate group and stirring the silane coupling agent and the silica in an organic solvent containing an alcohol such as methanol or isopropyl alcohol at room temperature.
As the silica particles in the present invention, commercially available silica particles can be used. For example, as silica particles whose surface is modified with acrylate, the trade names MEK-AC-2140Y and MEK-AC manufactured by Nissan Chemical Industries, Ltd. -4130Y, MEK-AC-5140Y, etc. can be used.

The silica particles used in the present invention preferably contain 20 to 30% by mass, more preferably 20 to 25% by mass, as a solid content, based on the entire active energy ray-curable composition of the present invention. When the content of the silica particles satisfies the above range, the effect of the present invention is further enhanced and the increase in viscosity can be suppressed.

<Curing means>
Examples of the means for curing the active energy ray-curable composition of the present invention include heat curing or curing with active energy rays, and among these, curing with active energy rays is preferable.
The active energy rays used for curing the active energy ray-curable composition of the present invention include polymerizable components in the composition such as electron beam, α ray, β ray, γ ray, and X ray in addition to ultraviolet rays. It is not particularly limited as long as it can impart the energy required for advancing the polymerization reaction of the above. In particular, when a high-energy light source is used, the polymerization reaction can proceed without using a polymerization initiator. Further, in the case of ultraviolet irradiation, mercury-free is strongly desired from the viewpoint of environmental protection, and replacement with a GaN-based semiconductor ultraviolet light emitting device is very useful industrially and environmentally. Further, the ultraviolet light emitting diode (UV-LED) and the ultraviolet laser diode (UV-LD) are compact, have a long life, have high efficiency, and are low in cost, and are preferable as an ultraviolet light source.

<Initiator of polymerization>
The active energy ray-curable composition of the present invention may contain a polymerization initiator. The polymerization initiator may be any one capable of generating active species such as radicals and cations by the energy of the active energy ray and initiating the polymerization of the polymerizable compound (monomer or oligomer). As such a polymerization initiator, known radical polymerization initiators, cationic polymerization initiators, base generators and the like can be used alone or in combination of two or more, and among them, a radical polymerization initiator is used. Is preferable. Further, the polymerization initiator is preferably contained in an amount of 5 to 20% by mass with respect to the total mass (100% by mass) of the composition in order to obtain a sufficient curing rate.
Examples of the radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, and the like. Examples thereof include ketooxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon halogen bond, and alkylamine compounds.
Further, in addition to the above-mentioned polymerization initiator, a polymerization accelerator (sensitizer) can also be used in combination. The polymerization accelerator is not particularly limited, but for example, trimethylamine, methyldimethylamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, p-dimethylaminobenzoic acid-2-ethylhexyl, N, Amine compounds such as N-dimethylbenzylamine and 4,4'-bis (diethylamino) benzophenone are preferable, and the content thereof may be appropriately set according to the polymerization initiator used and the amount thereof.

<Organic solvent>
The active energy ray-curable composition of the present invention may contain an organic solvent, but it is preferable not to contain it if possible. If the composition does not contain an organic solvent, particularly a volatile organic solvent (VOC (Volatile Organic Compounds) free), the safety of the place where the composition is handled is further enhanced, and it is possible to prevent environmental pollution. .. The "organic solvent" means a general non-reactive organic solvent such as ether, ketone, xylene, ethyl acetate, cyclohexanone, and toluene, and should be distinguished from the reactive monomer. be. Further, "not containing" the organic solvent means that it is substantially free of the organic solvent, and it is preferably less than 0.1% by mass.

<Other ingredients>
The active energy ray-curable composition of the present invention may contain other known components, if necessary. The other components are not particularly limited, but are, for example, conventionally known surfactants, polymerization inhibitors, leveling agents, antifoaming agents, fluorescent whitening agents, penetration promoters, wetting agents (moisturizing agents), and fixing agents. Agents, viscosity stabilizers, fungicides, preservatives, antioxidants, UV absorbers, chelating agents, pH regulators, thickeners and the like can be mentioned.

<Preparation of active energy ray-curable composition>
The active energy ray-curable composition of the present invention can be produced by using the above-mentioned various components, and the preparation means and conditions thereof are not particularly limited. For example, a polymerizable monomer, a pigment, a dispersant and the like can be used in a ball mill. It is put into a disperser such as a kitty mill, a disc mill, a pin mill, and a dyno mill, and dispersed to prepare a pigment dispersion, and the pigment dispersion is further mixed with a polymerizable monomer, an initiator, a polymerization inhibitor, a surfactant, and the like. It can be prepared by letting it.

<Viscosity>
The viscosity of the active energy ray-curable composition of the present invention may be appropriately adjusted according to the intended use and application means, and is not particularly limited. For example, when a discharge means for discharging the composition from a nozzle is applied. The viscosity in the range of 20 ° C. to 65 ° C., preferably 3 to 40 mPa · s, more preferably 5 to 15 mPa · s, and particularly preferably 6 to 12 mPa · s at 25 ° C. Further, it is particularly preferable that the viscosity range is satisfied without containing the organic solvent. For the above viscosity, a cone rotor (1 ° 34'× R24) was used with a cone plate type rotational viscometer VISCOMETER TVE-22L manufactured by Toki Sangyo Co., Ltd., the rotation speed was 50 rpm, and the temperature of constant temperature circulating water was 20 ° C. It can be appropriately set and measured in the range of about 65 ° C. VISCOMATE VM-150III can be used to adjust the temperature of the circulating water.

<Use>
The application of the active energy ray-curable composition of the present invention is not particularly limited as long as it is in a field where an active energy ray-curable material is generally used, and can be appropriately selected depending on the intended purpose, for example, for molding. Examples thereof include resins, paints, adhesives, insulating materials, mold release agents, coating materials, sealing materials, various resists, and various optical materials.
Further, the active energy ray-curable composition of the present invention can be used as an ink to not only form a design coating film on two-dimensional characters and images and various substrates, but also to form a three-dimensional stereoscopic image (three-dimensional model). It can also be used as a three-dimensional modeling material for forming. This three-dimensional modeling material may be used, for example, as a binder between powder particles used in a powder laminating method in which three-dimensional modeling is performed by repeatedly curing and laminating a powder layer, and is also shown in FIGS. 2 and 3. It may be used as a three-dimensional constituent material (model material) or a support member (support material) used in such a laminated molding method (stereolithography). Note that FIG. 2 is a method in which the active energy ray-curable composition of the present invention is discharged into a predetermined region, and the ones cured by irradiating with active energy rays are sequentially laminated to perform three-dimensional modeling (details will be described later). In FIG. 3, the storage pool (accommodation portion) 91 of the active energy ray-curable composition 95 of the present invention is irradiated with the active energy ray 94 to form a cured layer 96 having a predetermined shape on the movable stage 93. This is a method of sequentially stacking and performing three-dimensional modeling.
As a three-dimensional modeling device for modeling a three-dimensional model using the active energy ray-curable composition of the present invention, a known one can be used, and the present invention is not particularly limited, but for example, a means for accommodating the composition. , A supply means, a discharge means, an active energy ray irradiation means, and the like.
The present invention also includes a cured product obtained by curing an active energy ray-curable composition and a molded product obtained by processing a structure in which the cured product is formed on a substrate. The molded product is, for example, a cured product or structure formed in a sheet shape or a film shape, which has been subjected to molding processing such as heat stretching or punching, and is, for example, an automobile, an OA device, or electricity. -Suitably used for applications that require molding after decorating the surface, such as electronic devices, meters for cameras, and panels for operation units.
The base material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, or a composite material thereof and the like. From the viewpoint of processability, a plastic base material is preferable.

<Composition container>
The composition container of the present invention means a container in which an active energy ray-curable composition is stored, and is suitable for use in the above-mentioned applications. For example, when the active energy ray-curable composition of the present invention is used for ink, the container containing the ink can be used as an ink cartridge or an ink bottle, whereby ink transfer, ink replacement, etc. It is not necessary to touch the ink directly in the work, and it is possible to prevent the fingers and clothes from getting dirty. In addition, it is possible to prevent foreign substances such as dust from being mixed into the ink. The shape, size, material, etc. of the container itself may be suitable for the intended use and usage, and is not particularly limited, but the material is a light-shielding material that does not transmit light, or the container blocks light. It is desirable that it is covered with a sex sheet or the like.

<Image formation method, forming device>
The method for forming an image of the present invention includes, at least, an irradiation step of irradiating an active energy ray to cure the active energy ray-curable composition of the present invention, and the image forming apparatus of the present invention has an active energy. An irradiation means for irradiating the rays and an accommodating portion for accommodating the active energy ray-curable composition of the present invention may be provided, and the container may be accommodated in the accommodating portion. Further, it may have a discharge step and a discharge means for discharging the active energy ray-curable composition. The method of discharging is not particularly limited, and examples thereof include a continuous injection type and an on-demand type. Examples of the on-demand type include a piezo method, a thermal method, and an electrostatic method.
FIG. 1 is an example of an image forming apparatus provided with an inkjet ejection means. Ink is ejected to the recorded medium 22 supplied from the supply roll 210 by each color printing unit 230a, 230b, 230c, 230d provided with an ink cartridge for each color active energy ray-curable ink of yellow, magenta, cyan, and black and an ejection head. Will be done. Then, the light sources 240a, 240b, 240c, and 240d for curing the ink are irradiated with active energy rays to cure the ink, and a color image is formed. After that, the recording medium 220 is conveyed to the processing unit 250 and the printed matter take-up roll 260. Each printing unit 230a, 230b, 230c, 230d may be provided with a heating mechanism so that the ink is liquefied at the ink ejection portion. Further, if necessary, a mechanism for cooling the recording medium to about room temperature by contact or non-contact may be provided. Further, as the inkjet recording method, a serial method in which the head is moved to eject ink onto the recording medium or a recording medium is continuously moved with respect to the recording medium which moves intermittently according to the ejection head width. Any of the line methods of ejecting ink onto the recording medium from the head held at a fixed position can be applied.
The recording medium 220 is not particularly limited, and examples thereof include paper, film, ceramics, glass, metal, and composite materials thereof, and may be in the form of a sheet. Further, the configuration may be such that only single-sided printing is possible or double-sided printing is possible. Further, the recording medium 22 is not limited to that used as a general recording medium, and cardboard, building materials such as wallpaper and floor materials, cloth for clothing such as concrete and T-shirts, textiles, leather and the like are appropriately used. be able to.
Further, the activation of the active energy rays from the light sources 240a, 240b and 240c may be weakened or omitted, and after printing a plurality of colors, the activation energy rays may be irradiated from the light source 240d. This makes it possible to save energy and reduce costs.
The recorded materials recorded by the ink of the present invention include not only those printed on a smooth surface such as ordinary paper or resin film, but also those printed on a surface to be printed having irregularities, metal, ceramics, and the like. It also includes those printed on the printed surface made of various materials. Further, by stacking two-dimensional images, it is possible to form a partially three-dimensional image (an image composed of two-dimensional and three-dimensional) or a three-dimensional object.
FIG. 2 is a schematic view showing an example of another image forming apparatus (three-dimensional stereoscopic image forming apparatus) according to the present invention. The image forming apparatus 390 of FIG. 2 uses a head unit (movable in the AB direction) in which inkjet heads are arranged to discharge the first active energy ray-curable composition from the discharge head unit 300 for a modeled object for a support. A second active energy ray-curable composition having a composition different from that of the first active energy ray-curable composition is discharged from the head units 310 and 320, and each of these compositions is cured by the adjacent ultraviolet irradiation means 330 and 340. It is laminated while being laminated. More specifically, for example, the second active energy ray-curable composition is discharged from the support discharge head units 310 and 320 onto the modeled object support substrate 370, and is irradiated with the active energy rays to be solidified. After forming the first support layer having the reservoir, the first active energy ray-curable composition is discharged from the discharge head unit 300 for a modeled object to the reservoir, and the active energy ray is irradiated to solidify the reservoir. By repeating the process of forming the first modeled object layer multiple times while lowering the vertically movable stage 380 according to the number of layers, the support layer and the modeled object layer are laminated to form the three-dimensional model 350. To make. After that, the support laminated portion 360 is removed as needed. In FIG. 2, only one discharge head unit 300 for a modeled object is provided, but two or more may be provided.

Next, the inkjet recording apparatus of the present invention will be described. The inkjet recording apparatus of the present invention supplies a liquid to a plurality of individual liquid chambers through a common liquid chamber, discharges the liquid from a nozzle hole communicating with the individual liquid chambers, and circulates the liquid communicating with the individual liquid chambers. It has a liquid ejection head that circulates a liquid to a common liquid chamber through a flow path, and the liquid is an active energy ray-curable inkjet ink made of the active energy ray-curable composition of the present invention. ..
As the liquid ejection head (ink ejection head) of the inkjet recording apparatus of the present invention, for example, the following can be used.

An example will be described with reference to FIGS. 4, 5, 6, 7, 7, 8a-8f, 9a, and 9b. FIG. 4 is an external perspective view showing an example of an ink ejection head in the inkjet printing apparatus of the present invention. FIG. 5 is a cross-sectional explanatory view in a direction orthogonal to the nozzle arrangement direction of the ink ejection head of FIG. FIG. 6 is a partial cross-sectional explanatory view of the ink ejection head of FIG. 4 in a direction parallel to the nozzle arrangement direction. FIG. 7 is a plan view of the nozzle plate of the ink ejection head of FIG. 8a to 8f are planar explanatory views of each member constituting the flow path member of the ink ejection head of FIG. 9a and 9b are plan explanatory views of each member constituting the common liquid chamber member of the ink ejection head of FIG.

In the ink ejection head, the nozzle plate 1, the flow path plate 2, and the diaphragm member 3 as a wall surface member are laminated and joined, and the piezoelectric actuator 11 that displaces the diaphragm member 3 and the common liquid chamber member 20 are joined. And a cover 29.

The nozzle plate 1 has a plurality of nozzles 4 for ejecting the ink.
The flow path plate 2 is formed with an individual liquid chamber 6 leading to the nozzle 4, a fluid resistance portion 7 communicating with the individual liquid chamber 6 as the inflow flow path, and a liquid introduction portion 8 communicating with the fluid resistance portion 7. Further, the flow path plate 2 is formed by laminating and joining a plurality of plate-shaped members 41 to 45 from the nozzle plate 1 side, and laminating and joining these plate-shaped members 41 to 45 and the diaphragm member 3 to form a flow path. The member 40 is configured.
The diaphragm member 3 has a filter portion 9 as an opening through the liquid introduction portion 8 and the common liquid chamber 10 formed by the common liquid chamber member 20.
The diaphragm member 3 is a wall surface member that forms the wall surface of the individual liquid chamber 6 of the flow path plate 2. The diaphragm member 3 has a two-layer structure (not limited), and is formed of a first layer that forms a thin-walled portion from the flow path plate 2 side and a second layer that forms a thick-walled portion, and the first layer is an individual liquid. A deformable vibration region 30 is formed in a portion corresponding to the chamber 6.

Here, as shown in FIG. 7, a plurality of nozzles 4 are arranged in a staggered pattern on the nozzle plate 1.
As shown in FIG. 8a, the plate-shaped member 41 constituting the flow path plate 2 includes a through groove portion (meaning a groove-shaped through hole) 6a constituting the individual liquid chamber 6, a fluid resistance portion 51, and the outflow flow. Through-groove portions 51a and 52a constituting the circulation flow path 52 as a path are formed.
Similarly, as shown in FIG. 8b, the plate-shaped member 42 is formed with a through groove portion 6b constituting the individual liquid chamber 6 and a through groove portion 52b constituting the circulation flow path 52.
Similarly, as shown in FIG. 8c, the plate-shaped member 43 is formed with a through groove portion 6c constituting the individual liquid chamber 6 and a through groove portion 53a having the nozzle arrangement direction constituting the circulation flow path 53 as the longitudinal direction. ..
Similarly, as shown in FIG. 8d, the plate-shaped member 44 has a through groove portion 6d constituting the individual liquid chamber 6, a through groove portion 7a which is a fluid resistance portion 7, and a through groove portion 8a constituting the liquid introduction portion 8. A through groove portion 53b having a longitudinal direction in which the nozzles are arranged to form the circulation flow path 53 is formed.
Similarly, as shown in FIG. 8e, the plate-shaped member 45 has a through groove portion 6e constituting the individual liquid chamber 6 and a through groove portion 8b (filter downstream side liquid) having the nozzle arrangement direction constituting the liquid introduction portion 8 as the longitudinal direction. A through groove portion 53c is formed in which the nozzle arrangement direction constituting the circulation flow path 53 is the longitudinal direction.
As shown in FIG. 8f, the diaphragm member 3 is formed with a vibration region 30, a filter portion 9, and a through groove portion 53d whose longitudinal direction is the nozzle arrangement direction constituting the circulation flow path 53.
In this way, by forming the flow path member by laminating and joining a plurality of plate-shaped members, it is possible to form a complicated flow path with a simple structure.

With the above configuration, the flow path member 40 composed of the flow path plate 2 and the diaphragm member 3 has a fluid resistance portion 51, a circulation flow path 52, and circulation along the surface direction of the flow path plate 2 leading to each individual liquid chamber 6. A circulation flow path 53 in the thickness direction of the flow path member 40 leading to the flow path 52 is formed. The circulation flow path 53 leads to the circulation common liquid chamber 50, which will be described later.

On the other hand, the common liquid chamber member 20 is formed with a common liquid chamber 10 to which the ink is supplied from a main tank or an ink cartridge and a circulation common liquid chamber 50.
As shown in FIG. 9a, the first common liquid chamber member 21 has a through hole 25a for a piezoelectric actuator, a through groove portion 10a which is a common liquid chamber 10A on the downstream side, and a groove portion 50a having a bottom which is a circulation common liquid chamber 50. Is formed.
As shown in FIG. 9b, the second common liquid chamber member 22 is formed with a through hole 25b for a piezoelectric actuator and a groove portion 10b that serves as a common liquid chamber 10B on the upstream side. Further, as shown in FIG. 4, the second common liquid chamber member 22 is formed with a through hole 71a which is one end of the common liquid chamber 10 in the nozzle arrangement direction and a supply port through the supply port 71.
The first common liquid chamber member 21 and the second common liquid chamber member 22 have a through hole through which the other end (the end opposite to the through hole 71a) of the circulation common liquid chamber 50 in the nozzle arrangement direction and the circulation port 81 pass through. 81a and 81b are formed.
In addition, in FIGS. 9a and 9b, the groove portion having the bottom is shown by applying a surface coating (the same applies to the following figures).
As described above, the common liquid chamber member 20 is composed of the first common liquid chamber member 21 and the second common liquid chamber member 22, and the first common liquid chamber member 21 is joined to the diaphragm member 3 side of the flow path member 40. The second common liquid chamber member 22 is laminated and joined to the first common liquid chamber member 21.

Here, the first common liquid chamber member 21 forms a downstream common liquid chamber 10A which is a part of the common liquid chamber 10 leading to the liquid introduction portion 8 and a circulation common liquid chamber 50 leading to the circulation flow path 53. ing. Further, the second common liquid chamber member 22 forms the upstream common liquid chamber 10B which is the rest of the common liquid chamber 10.
At this time, the downstream common liquid chamber 10A and the circulation common liquid chamber 50, which are a part of the common liquid chamber 10, are arranged side by side in the direction orthogonal to the nozzle arrangement direction, and the circulation common liquid chamber 50 is the common liquid chamber 10. It is placed at the position projected inside.
As a result, the dimensions (size) of the circulation common liquid chamber 50 are restricted by the dimensions required for the flow path including the individual liquid chamber 6, the fluid resistance portion 7, and the liquid introduction portion 8 formed by the flow path member 40. Is gone.
Then, the circulation common liquid chamber 50 and a part of the common liquid chamber 10 are arranged side by side, and the circulation common liquid chamber 50 is arranged at a position projected in the common liquid chamber 10 so as to be orthogonal to the nozzle arrangement direction. The width of the head in the direction can be suppressed, and the increase in size of the head can be suppressed. The common liquid chamber member 20 forms a circulation common liquid chamber 50 with a common liquid chamber 10 to which the ink is supplied from the head tank or the ink cartridge.

On the other hand, on the side of the diaphragm member 3 opposite to the individual liquid chamber 6, a piezoelectric actuator 11 including an electromechanical conversion element as a driving means (actuator means, pressure generating means) for deforming the vibration region 30 of the diaphragm member 3 is provided. It is arranged.
As shown in FIG. 6, the piezoelectric actuator 11 has a piezoelectric member 12 joined on a base member 13, and the piezoelectric member 12 is grooved by half-cut dicing to form a required number for one piezoelectric member 12. The columnar piezoelectric elements 12A and 12B are formed in a comb-teeth shape at predetermined intervals.
Here, the piezoelectric element 12A of the piezoelectric member 12 is a piezoelectric element that is driven by giving a drive waveform, and the piezoelectric element 12B is used as a mere column without giving a drive waveform, but all the piezoelectric elements 12A and 12B are driven. It can also be used as a piezoelectric element.
Then, the piezoelectric element 12A is joined to the convex portion 30a, which is an island-shaped thick portion formed in the vibration region 30 of the diaphragm member 3. Further, the piezoelectric element 12B is joined to the convex portion 30b which is a thick portion of the diaphragm member 3.

The piezoelectric member 12 is formed by alternately stacking piezoelectric layers and internal electrodes. The internal electrodes are respectively drawn out to the end faces to provide external electrodes, and the flexible wiring member 15 is connected to the external electrodes.
In the ink ejection head configured in this way, for example, by lowering the voltage applied to the piezoelectric element 12A from the reference potential, the piezoelectric element 12A contracts, the vibration region 30 of the vibrating plate member 3 descends, and the individual liquid chamber 6 As the volume expands, the ink flows into the individual liquid chamber 6.
After that, the voltage applied to the piezoelectric element 12A is increased to extend the piezoelectric element 12A in the stacking direction, and the vibration region 30 of the vibrating plate member 3 is deformed in the direction toward the nozzle 4 to contract the volume of the individual liquid chamber 6. As a result, the ink in the individual liquid chamber 6 is pressurized, and the ink is ejected from the nozzle 4.
Then, by returning the voltage applied to the piezoelectric element 12A to the reference potential, the vibration region 30 of the vibrating plate member 3 is restored to the initial position, the individual liquid chamber 6 expands, and a negative pressure is generated. Therefore, at this time, the common liquid is generated. The ink is filled from the chamber 10 into the individual liquid chamber 6. Therefore, after the vibration of the meniscus surface of the nozzle 4 is attenuated and stabilized, the operation for the next ejection is started.
The driving method of this head is not limited to the above example (pull-pushing), and pulling or pushing may be performed depending on the driving waveform. Further, in the above-described embodiment, the laminated piezoelectric element has been described as a means for giving pressure fluctuation to the individual liquid chamber 6, but the present invention is not limited to this, and a thin-film piezoelectric element can also be used. Further, it is possible to use a heat-generating resistor arranged in the individual liquid chamber 6 to generate air bubbles by the heat generated by the heat-generating resistor to give pressure fluctuation, or to generate pressure fluctuation by using electrostatic force. ..

Next, an example of the ink circulation system using the ink ejection head according to the present embodiment will be described with reference to FIG.

FIG. 10 is a block diagram showing an example of the ink circulation system according to the present invention.
As shown in FIG. 10, the ink circulation system includes a main tank, an ink ejection head, a supply tank, a circulation tank, a compressor, a vacuum pump, a first liquid feed pump, a second liquid feed pump, a regulator (R), and a supply side. It consists of a pressure sensor, a circulation side pressure sensor, and the like. The supply-side pressure sensor is connected between the supply tank and the ink ejection head to the supply flow path side connected to the supply port 71 (see FIG. 4) of the ink ejection head. The circulation side pressure sensor is connected between the ink ejection head and the circulation tank and is connected to the circulation flow path side connected to the circulation port 81 (see FIG. 4) of the ink ejection head.
One of the circulation tanks is connected to the supply tank via the first liquid feed pump, and the other of the circulation tanks is connected to the main tank via the second liquid feed pump. As a result, the ink flows from the supply tank through the supply port 71 into the ink ejection head, is discharged from the circulation port and is discharged to the circulation tank, and further, the ink is discharged from the circulation tank to the supply tank by the first liquid feeding pump. Is sent to circulate the ink.
Further, a compressor (not shown) is connected to the supply tank, and the pressure sensor on the supply side is controlled so that a predetermined positive pressure is detected. On the other hand, a vacuum pump (not shown) is connected to the circulation tank, and is controlled so that a predetermined negative pressure is detected by the circulation side pressure sensor. As a result, the negative pressure of the meniscus can be kept constant while circulating the ink through the ink ejection head.
Further, when the droplets are ejected from the nozzle of the ink ejection head, the amount of the ink in the supply tank and the circulation tank decreases, so that the second liquid feeding pump is appropriately used from the main tank to the circulation tank. It is desirable to replenish the ink. The timing of replenishing the ink from the main tank to the circulation tank is detected by a liquid level sensor provided in the circulation tank, such as replenishing the ink when the liquid level height of the ink in the circulation tank falls below a predetermined height. It can be controlled by the result.

Next, the circulation of the ink in the ink ejection head will be described. As shown in FIG. 4, a supply port 71 communicating with the common liquid chamber and a circulation port 81 communicating with the circulation common liquid chamber 50 are formed at the end of the common liquid chamber member 20. The supply port 71 and the circulation port 81 are connected to a supply tank and a circulation tank (see FIGS. 11 and 12) for storing the ink, respectively, via a tube. Then, the ink stored in the supply tank is supplied to the individual liquid chamber 6 via the supply port 71, the common liquid chamber 10, the liquid introduction unit 8, and the fluid resistance unit 7.
Further, while the ink in the individual liquid chamber 6 is ejected from the nozzle 4 by the drive of the piezoelectric member 12, part or all of the ink that remains in the individual liquid chamber 6 without being ejected is the fluid resistance portion 51. It is circulated to the circulation tank via the circulation flow paths 52 and 53, the circulation common liquid chamber 50, and the circulation port 81.
The ink circulation can be performed not only when the ink ejection head is operated but also when the operation is stopped. It is preferable that the ink in the individual liquid chamber is constantly refreshed by circulating during the operation suspension, and the aggregation and sedimentation of the components contained in the ink can be suppressed.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to the following examples.

<Preparation of Inorganic Magenta Pigment Dispersion Liquid 1>
Dispersant polymer (trade name: BYKJET-9151, manufactured by Big Chemie Japan Co., Ltd., amine value: 17.2 mgKOH / g) 18 parts by mass of acryloyl morpholin (trade name: ACMO, manufactured by Kojin Film & Chemicals Co., Ltd., structural formula : The following formula (M-2)) was placed in 162 parts by mass and stirred and dissolved at 40 ° C. for 4 hours to prepare a dispersion medium.
In a 70 mL mayonnaise bottle (trade name: UM sample bottle, manufactured by AS ONE Co., Ltd.), 80 parts by mass of zirconia balls having a diameter of 2 mm, 4.5 parts by mass of CI 101M (manufactured by Rankses), and 18 parts by mass of the dispersion medium are placed. In addition, the mixture was dispersed in a ball mill under the following conditions for 8 hours to remove zirconia balls having a diameter of 2 mm, then 80 parts by mass of zirconia balls having a diameter of 1 mm were added, and further dispersed in a ball mill for 10 days. 1] (pigment concentration: 20% by mass, volume average particle diameter 100 nm) was prepared.

-Ball mill conditions-
Media: YTZ ball diameter 2 mm (zirconia ball, manufactured by Nikkato Corporation)
YTZ ball diameter 1 mm (zirconia ball, manufactured by Nikkato Corporation)
Mill: MIX-ROTAR VMR-5 (manufactured by AS ONE Corporation)
Rotation speed: Mayonnaise bottle rotation speed 75 rpm

<Preparation of Inorganic Magenta Pigment Dispersion Liquid 2>
The magenta pigment dispersion 1 was prepared in the same manner as the magenta pigment dispersion 1 except that the dispersion time of the magenta pigment dispersion 1 was 5 days, and a [magenta pigment dispersion 2] (pigment concentration: 20% by mass, volume average particle diameter 300 nm) was prepared.

<Preparation of Inorganic Magenta Pigment Dispersion Liquid 3>
The magenta pigment dispersion 1 was prepared in the same manner as the magenta pigment dispersion 1 except that the dispersion time of the magenta pigment dispersion 1 was 3 days, and a [magenta pigment dispersion 3] (pigment concentration: 20% by mass, volume average particle diameter 400 nm) was prepared.

The volume average particle size can be measured by, for example, a particle size analyzer (Microtrack MODEL UPA9340, manufactured by Nikkiso Co., Ltd.).

Examples 1-8, Comparative Examples 1-5
Inks of each Example and Comparative Example were prepared according to the formulations (parts by mass) in Table 1. The MEK-ST-40 manufactured by Nissan Chemical Industries, Ltd. in Table 1 is silica particles whose surface is not modified with a (meth) acrylate compound.

The characteristics of the inks of each example and comparative example were evaluated as follows. The results are also shown in Table 1.

<Curable>
Kobayashi Seisakusho Co., Ltd., Winding No. Fusion to a solid coating film with a thickness of about 40 μm, which was produced by applying the inks of each example and comparative example to a base material (Iupilon sheet NF2000: manufactured by Mitsubishi Gas Chemical Company) using the wire bar of # 6. An LED UV irradiator LH6 manufactured by Systems Japan Co., Ltd. was used to irradiate active energy rays in a long wavelength region with a wavelength of 395 nm under the condition of 500 mJ / cm ² , and the coating film was cured to obtain a cured product. Then, the surface of the coating film made of the obtained cured product was evaluated by palpation using a cotton swab according to the following criteria.
⊚: The surface of the coating film is not scratched.
◯: The surface of the coating film is not scratched, but there is a slight sticky feeling, but there is no problem in practical use.
Δ: The surface of the coating film is slightly scratched and has a sticky feeling.
X: The surface of the coating film is scratched, and a part of the cured film is transferred to the hand.

<Intermittent discharge stability>
The inks of each example and comparative example are filled in an inkjet printer (device name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.), left to stand for a predetermined time after the nozzle cleaning operation, and then a nozzle check pattern is printed, resulting in non-ejection. The time until the nozzle was generated was measured.
⊚: 5 hours or more.
〇: 3 to 5 hours.
Δ: 1 to 3 hours.
X: Less than 1 hour.

<Evaluation of color unevenness in printed image>
The inks of each example and comparative example are filled in an inkjet printer (device name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.), and as a pattern sample for color unevenness evaluation, the mixing ratio of each ink is 1: 1 and Y, M, and C are used. A mixed color pattern in which and M overlap was printed, and the red part and the green part were visually observed from a distance of about 30 cm to evaluate the color uniformity. The evaluation criteria are as follows.
⊚: No unevenness has occurred in the mixed color part.
〇: The unevenness of the color mixture is not noticeable.
X: The color mixture is clearly uneven.

Example 9
As shown in FIGS. 4 to 12, a liquid is supplied to a plurality of individual liquid chambers, the liquid is discharged from a nozzle hole communicating with the individual liquid chambers, and a circulation flow path communicating with the individual liquid chambers is provided. The above embodiment was repeated except that an inkjet recording device having a liquid ejection head for circulating the liquid to the common liquid chamber was provided.

In the ink prepared in each example, the volume average particle size of the silica particles is 1/10 to 1/3 of the volume average particle size of the inorganic pigment, and the surface of the silica particles is a (meth) acrylate compound. It was found that the sol was modified by the above method, so that the sedimentation due to the aggregation of the silica particles was suppressed, the intermittent ejection property and the color unevenness of the printed image were improved, the coating film hardness was high, and the abrasion resistance was also excellent.
In particular, since Example 9 is an example in which the inkjet recording apparatus particularly suitable for the present invention is used, the evaluation of color unevenness in the printed image is much better than that of the other examples.
On the other hand, in Comparative Examples 1 to 5 , the volume average particle diameter of the silica particles was 1/10 to 1/3 of the volume average particle diameter of the inorganic pigment, and the surface of the silica particles was (meth). Since both the requirements of being modified with the acrylate compound are not satisfied at the same time, the intermittent ejection stability and the evaluation of color unevenness of the printed image are inferior.

(Figs. 1 to 3)
91 Storage pool (accommodation)
93 Movable stage 94 Active energy ray 95 Active energy ray Curable composition 96 Cured layer 210 Supply roll 220 Recorded matter 230a, 230b, 230c, 230d Each color printing unit 240a, 240b, 240c, 240d Light source 250 Processing unit 260 Printed matter winding Roll 300 Discharge head unit for modeled object 310, 320 Discharge head unit for support 330, 340 Ultraviolet irradiation means 350 Three-dimensional modeled object 360 Support laminated part 370 Modeled object support substrate 380 Swage 390 Image forming device (FIGS. 4 to 12)
1 Nozzle plate 2 Flow plate 3 Vibrating plate member 4 Nozzle 6 Individual liquid chambers 6a, 6b, 6c, 6d, 6e Through groove part 7 Fluid resistance part 7a Through groove part 8 Liquid introduction part which is a fluid resistance part 8a, 8b Through groove portion 9 that constitutes the liquid introduction section Filter section 10 Common liquid chamber 10A Downstream side common liquid chamber 10a Through groove section 10B Upstream side common liquid chamber 10b Groove section 11 Piezoelectric actuator 12 Piezoelectric member 12A, 12B Piezoelectric element 13 Base member 15 Flexible wiring member 20 Common liquid chamber member 21 First common liquid chamber member 22 Second common liquid chamber member 25a, 25b Through hole for piezoelectric actuator 29 Cover 30 Vibration region 30a, 30b Convex part 40 Flow path member 41 to 45 Plate-shaped member 50 Circulation common liquid chamber 50a Groove 51 Fluid resistance 51a Through groove 52, 53 that constitutes the fluid resistance section 52a, 52b Through groove 53a, 53b, 53c, 53d that constitutes the circulation channel Through groove 71 Supply port 71a Through hole 81 Circulation port 81a, 81b Through hole

JP-A-2017-160405

Claims (4)

In an active energy ray-curable composition containing an inorganic pigment and silica particles,
The feature is that the volume average particle size of the silica particles is 1/10 to 1/3 of the volume average particle size of the inorganic pigment, and the surface of the silica particles is modified with a (meth) acrylate compound. An active energy ray-curable composition. The active energy ray-curable composition according to claim 1, wherein the content of the silica particles in the active energy ray-curable composition is 20 to 30% by mass. An active energy ray-curable inkjet ink comprising the active energy ray-curable composition according to claim 1 or 2. A liquid is supplied to a plurality of individual liquid chambers via a common liquid chamber, the liquid is discharged from a nozzle hole communicating with the individual liquid chamber, and the common liquid chamber is passed through a circulation flow path communicating with the individual liquid chamber. An inkjet recording apparatus having a liquid ejection head that circulates a liquid to the liquid, wherein the liquid is the active energy ray-curable inkjet ink according to claim 3.

Images