JP7098104B2 - Inkjet printing method and inkjet printing equipment - Google Patents

Description

The present invention relates to a curable composition, an ink, a composition container, an inkjet printing method, an inkjet printing device, a cured product processing method, a cured product, a three-dimensional model, and a molded product.

As a method for forming an image on a recording medium such as paper or plastic based on image data, there are an electrophotographic method, a screen printing method, an inkjet method, and the like. The electrophotographic method requires a complicated process such as charging and exposure on the photoconductor, and as a result, the manufacturing cost becomes high. The screen printing method requires frequent plate production and storage, review of printing condition settings, and the like, which increases the cost.

On the other hand, the inkjet method is good at on-demand printing because the printing device is relatively inexpensive, it does not require a plate, and ink is ejected only to the image part to form an image, so that ink consumption is efficient. , Has been attracting attention in recent years to replace the above printing method.
Among them, the inkjet ink composition (active energy ray-curable inkjet ink composition) that can be cured by irradiation with active energy rays such as ultraviolet rays has a shorter drying time than water-based or solvent-based ink jets, and has environmentally harmful evaporations. It is an excellent method in that it can be printed on various substrates because it does not appear and the image does not easily bleed.

In recent years, not only process colors but also metallic inks are required as special colors in active energy ray-curable inkjet inks.

In metallic ink as an active energy ray-curable inkjet ink, there is a concern that the ejection property may be deteriorated due to pigment precipitation when a metal pigment is used. When the particle size of the metal pigment is large, the metallic luster of the image is improved, but the settling speed is high and continuous ejection becomes difficult.

Therefore, in order to solve these problems, in Patent Document 1, the desired metallic luster cannot be obtained if the metal particles have a diameter of less than 2 μm, but the metal particles having a diameter of 2 μm or more settle and lose the uniformity of the ink. It is shown that the metallic luster is obtained and the uniform dispersibility is ensured by using the particles in which the surface of the resin particles is coated with metal. However, the particles coated with the resin with metal lack the concealing property and the metallic luster. Further, if the content of the metal-coated particles is increased, the hiding property and the metallic luster are improved, but the settling property is deteriorated and the uniformity of the ink is lost.

As described above, there is not yet an inkjet printing method that achieves both the metallic luster and the metallic ink ejection property shown above at a sufficient level.

Therefore, an object of the present invention is to provide a curable composition having an excellent metallic luster and good ejection properties.

The inventors have found that a metallic ink containing a flake-like metal pigment having a large particle size can be printed with an image having excellent metallic luster by combining a head having a circulation mechanism, and have completed the present invention. ..

That is, the present invention is a curable composition as described below.
Contains polymerizable compounds, polymerization initiators and pigments
The pigment is a flaky metal pigment having a volume average particle diameter of 2.0 μm or more and 5 μm or less, and has a content of 1% by mass or more and less than 10% by mass in the ink composition.

The curable composition of the present invention has excellent ejection properties and can print an image having excellent metallic luster.

It is an external perspective explanatory view of the liquid discharge head which concerns on embodiment of this invention. It is sectional drawing in the direction orthogonal to the nozzle arrangement direction of the head. It is a partial cross-sectional explanatory view of the direction parallel to the nozzle arrangement direction of the head. It is a plane explanatory view of the nozzle plate of the head. It is a plane explanatory view of each member constituting the flow path member of the head. It is a plane explanatory view of each member constituting the common liquid chamber member of the head. It is a block diagram which shows an example of the liquid circulation system which concerns on this invention. FIG. 2 is a cross-sectional view taken along the line AA'in FIG. FIG. 2 is a cross-sectional view taken along the line BB'in FIG. It is a plane explanatory view of the main part of an example of the apparatus which discharges a liquid which concerns on this invention. It is explanatory drawing of the main part side surface of the apparatus. It is a plane explanatory view of the main part of another example of the liquid discharge unit which concerns on this invention. It is a figure which shows an example of the image forming apparatus which uses the curable composition of this invention. It is a perspective view of the main tank which houses the curable composition of this invention.

Hereinafter, the curable composition of the present invention will be specifically described.
<Polymerizable compound>
The curable composition of the present invention contains a polymerizable compound.
As the polymerizable compound, a monofunctional monomer and a polyfunctional monomer can be used, but the content of the monofunctional monomer is preferably 50% by mass or more and less than 90% by mass in the total amount of the curable composition.

(Monofunctional monomer)
Examples of the monofunctional monomer include, but are not limited to, hydroxyethyl acrylamide and 4-hydroxybutyl (meth) acrylate, and examples of the (meth) acrylate having a cyclic structure or acrylamide include 2-phenoxyethyl (meth). Examples thereof include acrylate, isobornyl (meth) acrylate, N-vinylcaprolactam, N-vinylpyrrolidone, acryloylmorpholin, cyclic trimethylolpropaneformal (meth) acrylate, and benzyl (meth) acrylate.

(Polyfunctional monomer)
As the polyfunctional monomer, a polyfunctional acrylate, a polyfunctional urethane acrylate oligomer and the like can be used. The polyfunctional monomer can be contained in the range of 1% by mass or more and 15% by mass or less with respect to the cured composition. As the polyfunctional monomer, a polyfunctional urethane acrylate oligomer can be used. Examples of the polyfunctional urethane acrylate oligomer include, but are not limited to, CN704 (Sartmer) and CN996H90 (Sartmer).

<Metal pigment>
Examples of the scale-like metal pigment include, but are not limited to, aluminum and the like. As the scaly metal pigment, a pigment having a volume average particle diameter of 2.0 μm or more and 5 μm or less is used, but it is preferably 2.0 or more and 3.0 μm or less.

但し、
Ｄ_ｐ：金属顔料粒子の体積平均粒子径
ρ_ｐ：金属顔料粒子の密度
ρ_ｆ：媒体の密度（インクから顔料を抜いた媒体の密度）
ｇ：重力加速度（９．８ｍ／ｓ^２ ）
η：媒体の粘度（インクから顔料を抜いた媒体の粘度） The sedimentation rate of the metal pigment is calculated using the following Stokes' equation.

however,
D _p : Volume average particle diameter of metal pigment particles ρ _p : Density of metal pigment particles ρ _f : Density of medium (density of medium from which pigment is removed from ink)
g: Gravitational acceleration (9.8 m / s ² )
η: Viscosity of the medium (viscosity of the medium from which the pigment is removed from the ink)

<Polymer initiator>
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 a ketooxime ester compound, a borate compound, an azinium compound, a metallocene compound, an active ester compound, a compound having a carbon halogen bond, and an alkylamine compound.
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, and is, 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.

<Active energy ray>
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 beams, α rays, β rays, γ rays, and X rays 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.

<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.

<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 adjusting 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 adjusted 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 not only forms a design coating film on two-dimensional characters and images and various substrates when used as ink, but also forms 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). FIG. 3 shows that the storage pool (accommodation portion) 1 of the active energy ray-curable composition 5 of the present invention is irradiated with the active energy ray 4 to form a cured layer 6 having a predetermined shape on the movable stage 3. 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 that 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. Further, 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.

<Recording device, recording method>
The liquid composition of the present invention can be suitably used for various recording devices by an inkjet recording method, for example, a printer, a facsimile device, a copying device, a printer / fax / copier multifunction device, a three-dimensional modeling device, and the like.
In the present invention, the recording device and the recording method are devices capable of discharging a liquid composition, various treatment liquids, and the like to a recording medium, and a method for recording using the device. The recording medium means a medium to which a liquid composition or various treatment liquids can be attached even temporarily.
The recording medium 22 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. Not limited to those used as general recording media, cardboard, building materials such as wallpaper and flooring, cloth for clothing such as concrete and T-shirts, textiles, leather and the like can be appropriately used.
This recording device includes not only a head portion for discharging a liquid composition, but also means related to feeding, transporting, and discharging paper of a recording medium, and other devices called pretreatment devices and posttreatment devices. Can be done.
The recording device and recording method may include a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, means for heating and drying the printed surface and the back surface of the recording medium. The heating means and the drying means are not particularly limited, but for example, a hot air heater and an infrared heater can be used. The drying temperature is preferably 100 ° C. or higher and 200 ° C. or lower, and more preferably 120 ° C. or higher and 150 ° C. or lower. Heating and drying can be performed before printing, during printing, after printing, and the like.
Further, the recording device and the recording method are not limited to those in which significant images such as characters and figures are visualized by the liquid composition. For example, those that form patterns such as geometric patterns and those that form three-dimensional images are also included.
Further, the recording device includes both a serial type device that moves the discharge head and a line type device that does not move the discharge head, unless otherwise specified.
Further, as this recording device, it is possible to use not only a desktop type but also a wide recording device capable of printing on an A0 size recording medium, or, for example, continuous paper wound in a roll shape as a recording medium. A continuous book printer is also included.
An example of the recording device will be described with reference to FIGS. 13 and 14. FIG. 1 is a perspective explanatory view of the device. FIG. 14 is a perspective explanatory view of the main tank. The image forming apparatus 400 as an example of the recording apparatus is a serial type image forming apparatus. A mechanism portion 420 is provided in the exterior 401 of the image forming apparatus 400. Each liquid composition accommodating portion 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is, for example, an aluminum laminated film or the like. It is formed by the packaging member of. The liquid composition storage unit 411 is housed in, for example, a plastic storage container case 414. As a result, the main tank 410 is used as a cartridge for each color.
On the other hand, a cartridge holder 404 is provided behind the opening when the cover 401c of the main body of the apparatus is opened. A main tank 410 is detachably attached to the cartridge holder 404. As a result, each liquid composition discharge port 413 of the main tank 410 and the discharge head 434 for each color communicate with each other via the supply tube 436 for each color, and the liquid composition can be discharged from the discharge head 434 to the recording medium. Become.

Specific examples of the ejection head using the liquid composition as ink will be described below.
As the ejection head for ejecting this ink, it is preferable to use a flow-through type in which the ink circulates in the individual liquid chamber of the ejection head. The ink circulation can be performed not only when the ink ejection head is operated but also when the ink is not ejected. By circulating the ink during the suspension of operation, the ink in the individual liquid chamber is constantly refreshed, and the aggregation and sedimentation of the components contained in the ink can be suppressed, which is preferable.
When the ink of the present invention is used as a white ink, the titanium oxide particles used as a pigment tend to settle due to their high specific gravity, and nozzle clogging is likely to occur when the liquid is stationary. This can be prevented, and maintenance work can be simplified especially when returning from discharge suspension.

A printing coating apparatus provided with a flow-through type ejection head will be described with reference to FIGS. 1 to 12.
First, an embodiment of the present invention will be described with reference to the accompanying drawings. An example of the liquid discharge head according to the embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG. 1 is an external perspective explanatory view of the liquid discharge head, FIG. 2 is a cross-sectional explanatory view in a direction orthogonal to the nozzle arrangement direction of the head, and FIG. 3 is a cross-sectional explanatory view in a direction parallel to the nozzle arrangement direction of the head. 4 is a plan view of the nozzle plate of the head, FIG. 5 is a plan view of each member constituting the flow path member of the head, and FIG. 6 is a plan view of each member constituting the common liquid chamber member of the head. Is. 8 is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 9 is a cross-sectional view taken along the line BB of FIG.

In this liquid discharge head, a nozzle plate 1, a flow path plate 2, and a diaphragm member 3 as a wall surface member are laminated and joined. It also includes a piezoelectric actuator 11 that displaces the diaphragm member 3, a common liquid chamber member 20, and a cover 29.
The nozzle plate 1 has a plurality of nozzles 4 for discharging a liquid.
The flow path plate 2 forms an individual liquid chamber 6 leading to the nozzle 4, a fluid resistance portion 7 communicating with the individual liquid chamber 6, and a liquid introducing 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 wall portion from the flow path plate 2 side and a second layer that forms a thick wall 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. 4, a plurality of nozzles 4 are arranged in a staggered pattern on the nozzle plate 1. As shown in FIG. 5A, 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 and a fluid resistance portion 51. Through-groove portions 51a and 52a constituting the circulation flow path 52 are formed.
Similarly, as shown in FIG. 5B, 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. 5C, 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. Has been done.
Similarly, as shown in FIG. 5D, the plate-shaped member 44 has a through-groove portion 6d constituting the individual liquid chamber 6, a through-groove portion 7a as a fluid resistance portion 7, and a through-groove portion 8a constituting the liquid introduction portion 8. And the through groove portion 53b having the nozzle arrangement direction constituting the circulation flow path 53 as the longitudinal direction is formed.
Similarly, as shown in FIG. 5E, the plate-shaped member 45 has a through groove portion 6e constituting the individual liquid chamber 6 and a through groove portion 8b (filter) having the nozzle arrangement direction constituting the liquid introduction portion 8 as the longitudinal direction. The liquid chamber on the downstream side) and the through groove portion 53c having the nozzle arrangement direction constituting the circulation flow path 53 as the longitudinal direction are formed.
As shown in FIG. 5 (f), the diaphragm member 3 is formed with a vibration region 30, a filter portion 9, and a through groove portion 53d having a nozzle arrangement direction constituting the circulation flow path 53 as a longitudinal direction. ..
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 liquid is supplied from the supply / circulation mechanism 494 and a circulation common liquid chamber 50.
As shown in FIG. 6A, the first common liquid chamber member 21 constituting the common liquid chamber member 20 has a through hole 25a for a piezoelectric actuator, a through groove portion 10a serving as a common liquid chamber 10A on the downstream side, and circulation. A groove portion 50a having a bottom that serves as a common liquid chamber 50 is formed.
Similarly, as shown in FIG. 6B, 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, with reference to FIG. 1, the second common liquid chamber member 22 is formed with a through hole 71a which is an end portion of the common liquid chamber 10 in the nozzle arrangement direction and a supply port portion through the supply port 71.
Similarly, the first common liquid chamber member 21 and the second common liquid chamber member 22 are provided with 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. Through holes 81a and 81b are formed.
In addition, in FIG. 6, the groove portion having a 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 of the circulation common liquid chamber 50 are not 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.
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 liquid is supplied from a head tank or a liquid 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 for deforming the vibration region 30 of the diaphragm member 3 is arranged.
As shown in FIG. 3, 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 liquid discharge 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 volume of the individual liquid chamber 6 As the liquid expands, the liquid 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 liquid in the individual liquid chamber 6 is pressurized, and the liquid is discharged from the nozzle 4.
Then, the liquid is drawn from the common liquid chamber 10 by the surface tension and is filled with the liquid. Finally, the meniscus surface is stabilized by the balance between the negative pressure defined by the supply tank, the circulation tank, and the head difference, and the surface tension of the meniscus, so that the next discharge operation can be performed.

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 the pressure generating means for giving the 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 cause pressure fluctuation, or to generate pressure fluctuation by using electrostatic force. ..
Next, an example of the liquid circulation system using the liquid discharge head according to the present embodiment will be described with reference to FIG. 7.

FIG. 7 is a block diagram showing a liquid circulation system according to the present embodiment.
As shown in FIG. 7, the liquid circulation system includes a main tank, a liquid discharge head, a supply tank, a circulation tank, a compressor, a vacuum pump, a liquid feed pump, a regulator (R), a supply side pressure sensor, a circulation side pressure sensor, and the like. It is configured. The supply-side pressure sensor is connected between the supply tank and the liquid discharge head to the supply flow path side connected to the supply port 71 (see FIG. 1) of the liquid discharge head. The circulation side pressure sensor is connected between the liquid discharge head and the circulation tank and is connected to the circulation flow path side connected to the circulation port 81 (see FIG. 1) of the liquid discharge 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 liquid flows from the supply tank through the supply port 71 into the liquid discharge head, is discharged from the circulation port and is discharged to the circulation tank, and further, the liquid is sent from the circulation tank to the supply tank by the first liquid feed pump. The liquid circulates by being pumped.

Further, a compressor 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 is connected to the circulation tank, and the circulation side pressure sensor is controlled to detect a predetermined negative pressure. This makes it possible to keep the negative pressure of the meniscus constant while circulating the liquid through the liquid discharge head.
In addition, when droplets are ejected from the nozzle of the liquid ejection head, the amount of liquid in the supply tank and the circulation tank decreases, so the liquid from the main tank to the circulation tank is appropriately used from the main tank to the circulation tank. It is desirable to replenish. The timing of liquid replenishment from the main tank to the circulation tank depends on the detection result of the liquid level sensor installed in the circulation tank, such as replenishing the liquid when the liquid level height of the ink in the circulation tank drops below the specified height. Can be controlled.

Next, the circulation of the liquid in the liquid discharge head will be described. As shown in FIG. 1, 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 / circulation tank (see FIG. 7) for storing liquid, respectively, via a tube. Then, the liquid 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 liquid in the individual liquid chamber 6 is discharged from the nozzle 4 by the drive of the piezoelectric element 12, some or all of the liquid that remains in the individual liquid chamber 6 without being discharged is circulated in the fluid resistance portion 51. It is circulated to the circulation tank via the flow paths 52 and 53, the circulation common liquid chamber 50, and the circulation port 81.
It should be noted that the circulation of the liquid can be carried out not only when the liquid discharge head is operated but also when the operation is stopped. By circulating during the suspension of operation, the liquid in the individual liquid chamber is constantly refreshed, and the aggregation and sedimentation of the components contained in the liquid can be suppressed, which is preferable.
It is desirable that the ink flow rate in the individual liquid chamber during printing is 60 ln / min to 120 ln / min.
It is desirable that the nozzle diameter is 26 μm to 50 μm.

Next, an example of the device for discharging the liquid according to the present invention will be described with reference to FIGS. 10 and 11. FIG. 10 is an explanatory plan view of a main part of the device, and FIG. 11 is an explanatory view of a side surface of the main part of the device.
This device is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged over the left and right side plates 491A and 491B to movably hold the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407.
The carriage 403 is equipped with a liquid discharge unit 440 equipped with the liquid discharge head 404 according to the present invention. The liquid discharge head 404 of the liquid discharge unit 440 discharges, for example, liquids of each color of yellow (Y), cyan (C), magenta (M), and black (K). Further, the liquid discharge head 404 is mounted by arranging a nozzle row composed of a plurality of nozzles in a sub-scanning direction orthogonal to the main scanning direction and facing the discharge direction downward.
The liquid is supplied and circulated in the liquid discharge head 404 by the supply / circulation mechanism 494 for supplying the liquid stored outside the liquid discharge head 404 to the liquid discharge head 404. In this example, the supply / circulation mechanism 494 includes a supply tank, a circulation tank, a compressor, a vacuum pump, a liquid feed pump, a regulator (R), and the like. Further, the supply-side pressure sensor is connected between the supply tank and the liquid discharge head to the supply flow path side connected to the supply pipe port 71 of the liquid discharge head. The circulation side pressure sensor is connected between the liquid discharge head and the circulation tank and is connected to the circulation flow path side connected to the circulation port 81 of the liquid discharge head.

This device includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.
The transport belt 412 attracts the paper 410 and transports it at a position facing the liquid discharge head 404. The transport belt 412 is an endless belt, and is hung between the transport roller 413 and the tension roller 414. Adsorption can be performed by electrostatic adsorption, air suction, or the like.
Then, the transport belt 412 orbits in the sub-scanning direction by rotationally driving the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.
Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 for maintaining / recovering the liquid discharge head 404 is arranged on the side of the transport belt 412.
The maintenance / recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the liquid discharge head 404, a wiper member 422 that wipes the nozzle surface, and the like.
The main scanning movement mechanism 493, the supply / circulation mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.

In this apparatus configured in this way, the paper 410 is fed onto the transport belt 412 and sucked, and the paper 410 is conveyed in the sub-scanning direction by the circumferential movement of the conveyor belt 412.
Therefore, by driving the liquid ejection head 404 in response to the image signal while moving the carriage 403 in the main scanning direction, the liquid is ejected onto the stopped paper 410 to form an image.
As described above, since this device includes the liquid discharge head according to the present invention, it is possible to stably form a high-quality image.
Next, another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 12 is an explanatory plan view of a main part of the unit.
This liquid discharge unit includes a housing portion composed of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid among the members constituting the device for discharging the liquid. It is composed of a discharge head 404.
A liquid discharge unit may be configured in which at least one of the above-mentioned maintenance / recovery mechanism 420 and the supply / circulation mechanism 494 is further attached to, for example, the side plate 491B of the liquid discharge unit.

This recording device can include not only a portion for discharging the liquid composition, but also a pretreatment device, a device called a posttreatment device, and the like.
As one aspect of the pretreatment apparatus and the posttreatment apparatus, as in the case of liquid compositions such as black (K), cyan (C), magenta (M), and yellow (Y), a pretreatment liquid or a posttreatment liquid is used. There is an embodiment in which a liquid accommodating portion and a liquid discharge head are added, and the pretreatment liquid and the posttreatment liquid are discharged by an inkjet recording method.
As another aspect of the pretreatment device and the posttreatment device, there is a mode in which a pretreatment device and a posttreatment device by, for example, a blade coating method, a roll coating method, and a spray coating method are provided other than the inkjet recording method.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In the following description, "parts" and "%" indicate "parts by mass" and "% by mass" unless otherwise specified.

[Examples 1 to 6, Comparative Examples 1 to 3]
As the metal pigment, ECKA Granules Germany GmbH, which has a volume average particle diameter as shown in Table 1, was used, and a trade name: air atomized non-spherical aluminum powder (D50 = 3 μm grade) was used.
The monomer was put into a stainless steel or PP container according to the formulation shown in Table 1, and the mixture was stirred at 200 to 500 rpm using a stirring blade. Then, the initiator was added and stirred until it was visually dissolved. Then, the dispersion liquid of the metal particles was added, and the mixture was stirred for 30 to 60 minutes. Then, it was filtered with a PP capsule filter having a limit filtration accuracy of 3 μm to 8 μm and filled in a clean bottle.
The following evaluation items were evaluated for the obtained inks of Examples 1 to 6 and Comparative Examples 1 to 3.

但し、
Ｄ_ｐ：金属顔料粒子の体積平均粒子径
ρ_ｐ：金属顔料粒子の密度
ρ_ｆ：媒体の密度（インクから顔料を抜いた媒体の密度）
ｇ：重力加速度（９．８ｍ／ｓ^２ ）
η：媒体の粘度（インクから顔料を抜いた媒体の粘度）
（評価基準）
Ａ：０μｍ／ｓ以上、２．０μｍ／ｓ未満
Ｂ：２．０μｍ／ｓ以上～２．５μｍ／ｓ未満
Ｃ：２．５μｍ／ｓ以上 [evaluation]
[Evaluation of sedimentation velocity]
(Measurement method of sedimentation speed)
The settling velocity was calculated using the Stokes equation below.
The measurement was carried out at 25 ° C., and the sedimentation rate when 3% by mass of metal particles was placed in a medium having a density of 1.1 g / cm ³ and 10 mPa · s was measured.

however,
D _p : Volume average particle diameter of metal pigment particles ρ _p : Density of metal pigment particles ρ _f : Density of medium (density of medium from which pigment is removed from ink)
g: Gravitational acceleration (9.8 m / s ² )
η: Viscosity of the medium (viscosity of the medium from which the pigment is removed from the ink)
(Evaluation criteria)
A: 0 μm / s or more, less than 2.0 μm / s B: 2.0 μm / s or more to less than 2.5 μm / s C: 2.5 μm / s or more

[Evaluation of discharge stability]
(Evaluation method of discharge stability)
The ejection stability is the number of nozzles that do not eject when the ink is continuously ejected at a frequency of 20 kHz for 1 minute under the condition that the ink flying speed is 7 ± 1 m / s with a circulation type head (total number of nozzles 320). It was measured and evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: Number of non-discharge nozzles = 0 B: Number of non-discharge nozzles = 1 to 5 C: Number of non-discharge nozzles = 6 or more

[Evaluation of metallic luster]
(Evaluation method of metallic luster)
Using a printing device having a circulating head, print at a resolution of 600 * 600 dpi so that the amount of ink adhered to the substrate is 10 g / m ² or more, and UV so that the integrated light amount is 500 mJ / cm ² or more. A solid image was obtained by irradiating with light.
For the metallic luster, 4501-microgloss manufactured by Gardner was used, and the luster was measured at a fanning angle of 60 °.
(Evaluation criteria)
A: 400 or more B: 200 or more and less than 400 C: less than 200

(About FIGS. 1 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 7 Fluid resistance 7a Through groove 8 Liquid introduction 8a, 8b Through groove 9 Filter 10 Common liquid Chamber 10A Downstream side common liquid chamber 10B Upstream side common liquid chamber 10a Through groove part 10b Groove part 11 Hydraulic actuator 12 Hydraulic member 12A, 12B Hydraulic element 13 Base member 15 Flexible wiring member 20 Common liquid chamber member 21 First common liquid chamber member 22 No. 2 Common liquid chamber member 25a Through hole for piezoelectric actuator 25b Through hole for piezoelectric actuator 29 Cover 30 Vibration region 30a Convex part 30b Convex part 40 Flow path member 41 to 45 Plate-shaped member 50 Circulation common liquid chamber 50a Groove part 51 Fluid resistance part 51a Through groove 52 Circulation flow path 52a Through groove 52b Through groove 53 Circulation flow path 53a, 53b, 53c, 53d Through groove 71 Supply port 71a Through hole 81 Circulation port 81a, 81b Through hole 401 Guide member 403 Carrying 404 Liquid discharge head 405 Main Scanning motor 406 Drive pulley 407 Driven pulley 408 Timing belt 410 Paper 412 Conveying belt 413 Conveying roller 414 Tension roller 416 Sub-scanning motor 417 Timing belt 418 Timing pulley 420 Maintenance recovery mechanism 421 Cap member 422 Wiper member 440 Liquid discharge unit 491A, 491B Side plate 491C Back plate 493 Main scanning moving mechanism 494 Supply / circulation mechanism 495 Transport mechanism

(About FIGS. 13 and 14)
400 Image forming device 401 Image forming device exterior 401c Device body cover 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For each color of black (K), cyan (C), magenta (M), yellow (Y) Main tank 411 Liquid composition storage 413 Liquid composition discharge port 414 Storage container case 420 Mechanism part 434 Discharge head 436 Supply tube

Japanese Patent No. 4864200

Claims (6)

An inkjet printing method that prints ink using an inkjet printing device.
The ink contains a polymerizable compound, a polymerization initiator and a pigment, and the pigment is a scaly metal pigment having a volume average particle size of 2.0 μm or more and 5 μm or less, and has a content of 1 mass in the ink composition. % Or more and less than 10% by mass, an ink for ink jet made of a curable composition.
In the inkjet printing device, the head for ejecting ink has a plurality of nozzles for ejecting liquid, an individual liquid chamber leading to the nozzles, a circulation flow path leading to the individual liquid chamber, and a circulating common liquid leading to the circulation flow path. It is an inkjet printing apparatus provided with a chamber and a pressure generating means for applying pressure to the liquid in the individual liquid chamber.
The ink flow rate in the individual liquid chamber during printing is 60 ln / min to 120 ln / min.
An inkjet printing method characterized by this . The inkjet printing method according to claim 1, wherein the scaly metal pigment has an average thickness of 20 nm or more and 50 nm or less. The volume average particle size of the scaly pigment particles is 2.0 μm or more and 3.0 μm or less, the average thickness is 20 to 30 nm, and the sedimentation rate calculated based on Stokes' equation is less than 2.0 μm / s. The inkjet printing method according to claim 1. The inkjet printing method according to any one of claims 1 to 3, wherein the nozzle diameter is 26 μm to 50 μm. The inkjet printing method according to any one of claims 1 to 4 , further comprising an irradiation step of irradiating the ejected ink with active energy rays. An inkjet printing apparatus including a composition storage container containing ink and a discharge head for ejecting a curable composition or ink in the composition storage container.
The discharge head
Multiple nozzles that eject liquid and
An individual liquid chamber leading to the nozzle, a common liquid chamber for supplying liquid to the individual liquid chamber, and a common liquid chamber.
The circulation flow path leading to the individual liquid chamber and
The circulation common liquid chamber leading to the circulation flow path and
It is provided with a pressure generating means for applying pressure to the liquid in the individual liquid chamber.
The ink contains a polymerizable compound, a polymerization initiator and a pigment, and the pigment is a scaly metal pigment having a volume average particle size of 2.0 μm or more and 5 μm or less, and has a content of 1 mass in the ink composition. % Or more and less than 10% by mass, an ink for ink jet made of a curable composition.
The ink flow rate in the individual liquid chamber during printing is 60 ln / min to 120 ln / min.
An inkjet printing device characterized by this .

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