Liquid ejection device, inkjet printing device, liquid ejection method, and inkjet printing method

Abstract

To provide a liquid discharge device which has high discharge reliability and enables production of a discharge material having excellent non-transferability and scratch resistance.SOLUTION: A liquid discharge device has a storage part storing a liquid composition containing water, an organic solvent and a polyurethane resin, and a discharge head having an individual liquid chamber having a circulation flow channel circulating the liquid composition and a nozzle that communicates with the individual liquid chamber and discharges droplets composed of the liquid composition, in which a content of the polyurethane resin is 7.0 mass% or more and 20.0 mass% or less in a solid content.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a liquid ejection device, an inkjet printing device, a liquid ejection method, and an inkjet printing method.

Background Art

[0002] Compared with other recording methods, the inkjet recording method has a simple process, is easy to achieve full-color printing, and even with a device having a simple configuration, a high-resolution image can be obtained. Therefore, it is spreading from personal and office applications to the field of industrial printing.

[0003] In the field of industrial printing, high productivity is required. In particular, for applications such as wallpaper, wall covering, and home decoration, it is also necessary to improve fastness such as water resistance and abrasion resistance. Generally, various resins are added to give the ink composition functions, and it is known that the higher the resin addition amount, the better the fastness. However, as the resin addition amount increases, the ink tends to dry, so that ink sticking on the head nozzle surface is likely to occur, and there is a problem that the ejection reliability decreases.

[0004] Therefore, for example, an ink adsorption layer is formed by screen printing a liquid or paste-like binder composition for forming an ink adsorption layer directly or through another layer on a required portion of a cloth-like fiber product, so that an image formed on the cloth-like fiber product with an aqueous pigment ink can be made clearer and higher in density, and a flexible and highly fast image forming method has been proposed (see, for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a liquid ejection device that provides high ejection reliability and can obtain an ejection product having excellent non-transferability and abrasion resistance.

Means for Solving the Problem

[0006] The liquid ejection device of the present invention as means for solving the above problems includes a storage section that stores a liquid composition containing water, an organic solvent, and a polyurethane resin, an individual liquid chamber having a circulation flow path through which the liquid composition circulates, and a discharge head having a nozzle that communicates with the individual liquid chamber and discharges droplets composed of the liquid composition, and the content of the polyurethane resin is 7.0% by mass or more and 20.0% by mass or less in terms of solid content.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a liquid ejection device capable of obtaining an ejection product having high ejection reliability and excellent non-transferability and abrasion resistance.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] (Liquid Discharge Device and Liquid Discharge Method) The liquid discharge device of the present invention includes a storage unit that stores a liquid composition containing water, an organic solvent, and a polyurethane resin, an individual liquid chamber having a circulation flow path through which the liquid composition circulates, and a nozzle that communicates with the individual liquid chamber and discharges droplets composed of the liquid composition. The content of the polyurethane resin is 7% by mass or more and 20.0% by mass or less in terms of solid content, and further has other parts as required.

[0010] The liquid ejection method of the present invention includes an ejection step of ejecting droplets composed of the liquid composition from the nozzles of an ejection head while circulating a liquid composition containing water, an organic solvent, and a polyurethane resin in individual liquid chambers. The content of the polyurethane resin is 7% by mass or more and 20% by mass or less, and further includes other steps as necessary.

[0011] The liquid ejection method of the present invention can be preferably implemented by the liquid ejection device of the present invention. The ejection step can be performed by an ejection head, and other steps can be performed by other parts. The liquid ejection method of the present invention and the liquid ejection device of the present invention are preferably used as an inkjet printing method and an inkjet printing device using ink as the liquid composition.

[0012] In the prior art, before printing by inkjet, a printing process for forming an ink adsorption layer is included, and many working steps are required, and it is a problem to achieve both high productivity and fastness.

[0013] As a result of intensive studies by the present inventors, a liquid composition containing water, an organic solvent, and a polyurethane resin, and having a content of the polyurethane resin of 7% by mass or more and 20.0% by mass or less in terms of solid content, is used with a liquid ejection device equipped with an ejection head having a circulation mechanism. By ejecting droplets composed of the liquid composition, it has been found that an ejected product (printed matter) having high ejection reliability and excellent non-transferability and abrasion resistance can be obtained, and the present invention has been completed.

[0014] Hereinafter, the liquid composition used in the liquid ejection method and the liquid ejection device of the present invention will be described in detail.

[0015] <Liquid composition> The liquid composition contains water, an organic solvent, and a polyurethane resin, preferably contains a coloring material, and further contains other components as necessary.

[0016] - Polyurethane resin - Examples of the polyurethane resin include polycarbonate polyurethane resin, polyether polyurethane resin, polyester polyurethane resin, polyester polycarbonate polyurethane resin, etc. These may be used alone or in combination of two or more. Among these, from the viewpoint of improving the film fastness, particularly the scratch resistance, polycarbonate polyurethane resin and polyester polyurethane resin are preferable, and it is particularly preferable to use them in combination.

[0017] As the polyurethane resin, it is preferable to use a polycarbonate polyurethane resin having a glass transition temperature (Tg) of -30°C or higher and -10°C or lower from the viewpoint of obtaining high discharge reliability. It is preferable to use a polyester polyurethane resin having a glass transition temperature (Tg) of 50°C or higher and 60°C or lower from the viewpoint of obtaining a printed matter excellent in high fastness, and it is particularly preferable to use these two polyurethane resins in combination. The glass transition temperature (Tg) of the polyurethane resin can be measured, for example, using a differential scanning calorimeter (TA-60WS and DSC-60, manufactured by Shimadzu Corporation). Specifically, 4.0 mg of the polyurethane resin is placed in an aluminum sample container, the sample container is placed on a holder unit, and set in an electric furnace. Then, under a nitrogen atmosphere, the temperature is raised from 0°C to 150°C at a heating rate of 10°C / min, and then, after cooling from 150°C to -80°C at a cooling rate of 5°C / min, the temperature is further raised to 150°C at a heating rate of 10°C / min to measure the DSC curve. From the obtained DSC curve, using the analysis program in the DSC-60 system, it is analyzed by the midpoint method from the inflection point during the second heating to obtain the glass transition temperature (Tg).

[0018] As the polyurethane resin, those synthesized as appropriate may be used, or commercially available products may be used. Examples of the commercially available products include Takelac WS-4000, W-6010, W-5030, W-635, W-6110, WS-5000, WS-5100, WS-4022, WS-5984 (manufactured by Mitsui Chemicals, Inc., etc.). Among these, as commercially available products of polycarbonate polyurethane resins having a glass transition temperature (Tg) of -30°C or higher and -10°C or lower, Takelac W-6110 (Tg: -20°C) is particularly preferred, and as commercially available products of polyester polyurethane resins having a glass transition temperature (Tg) of 50°C or higher and 60°C or lower, Takelac WS-5000 (Tg: 60°C) is particularly preferred.

[0019] The content of the polyurethane resin is 7% by mass or more and 20.0% by mass or less in terms of solid content with respect to the total amount of the liquid composition, and preferably 7.2% by mass or more and 15% by mass or less. When the content of the polyurethane resin is 7% by mass or more and 20.0% by mass or less, it is preferable from the viewpoint of obtaining high ejection reliability and printed matter excellent in high fastness.

[0020] The liquid composition may contain other resins in addition to the above polyurethane resin. There are no particular restrictions on the other resins, and they can be appropriately selected according to the purpose. For example, polyester resins, acrylic resins, vinyl acetate resins, styrene resins, butadiene resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, acrylic-silicone resins, etc. can be mentioned. Resin particles composed of these resins may be used. It is possible to obtain ink by mixing resin particles in the state of a resin emulsion dispersed with water as a dispersion medium with materials such as colorants and organic solvents. As the resin particles, those appropriately synthesized may be used, or commercially available products may be used. These may be used alone or in combination of two or more.

[0021] The volume average particle diameter of the resin particles is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of obtaining good fixability and high image hardness, it is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 100 nm or less. The volume average particle diameter can be measured, for example, using a particle size analyzer (NanoTrack Wave-UT151, manufactured by Microtrac Bell Corporation).

[0022] There is no particular limitation on the particle diameter of the solid content in the liquid composition, and it can be appropriately selected according to the purpose. However, from the viewpoint of improving image quality such as discharge stability and image density, the maximum frequency in terms of the maximum number is preferably 20 nm or more and 1000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solid content includes resin particles, pigment particles, etc. The particle diameter can be measured using a particle size analyzer (NanoTrack Wave-UT151, manufactured by Microtrac Bell Corporation).

[0023] -Organic solvent- The organic solvent used in the present invention is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include polyhydric alcohols, polyhydric alcohol alkyl ethers, ethers such as polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, and the like. Examples of the water-soluble organic solvent include polyhydric alcohols such as ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol; polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone; amides such as formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; amines such as monoethanolamine, diethanolamine, and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; and propylene carbonate and ethylene carbonate. Since it not only functions as a wetting agent but also provides good drying properties, it is preferable to use an organic solvent having a boiling point of 250°C or lower.

[0024] Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol. Examples of the glycol ether compound include polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

[0025] <Water> Water is not particularly limited and can be appropriately selected according to the purpose. Examples include pure water such as ion-exchanged water, ultrafiltration water, reverse osmosis water, and distilled water, and ultrapure water. These can be used alone or in combination of two or more. The water content is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of the drying property and ejection reliability of the liquid composition, it is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass to 60% by mass.

[0026] <Colorant> As the pigment, an inorganic pigment or an organic pigment can be used. These can be used alone or in combination of two or more. Also, mixed crystals can be used. Examples of the pigment include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, lustrous pigments such as gold and silver, and metallic pigments. As the inorganic pigment, for example, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, carbon black produced by known methods such as the contact method, the furnace method, and the thermal method can be used. Examples of the organic pigment include azo pigments, polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (for example, basic dye type chelates, acid dye type chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like. Among these pigments, those having good affinity with the solvent are preferably used. In addition, the use of resin hollow particles and inorganic hollow particles is also possible. Specific examples of the pigment include, for black, carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, channel black, etc., or metals such as copper, iron (C.I. Pigment Black 11), titanium oxide, etc., and organic pigments such as aniline black (C.I. Pigment Black 1). Furthermore, as colorants, C.I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101 (Vermilion), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38, C.I. Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63, C.I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc. can be mentioned.

[0027] In order to obtain ink by dispersing the pigment, methods such as introducing a hydrophilic functional group into the pigment to form a self-dispersing pigment, coating the surface of the pigment with a resin for dispersion, and using a dispersant for dispersion can be mentioned. As a method of introducing a hydrophilic functional group into the pigment to form a self-dispersing pigment, for example, a method of making it dispersible in water by adding a functional group such as a sulfone group or a carboxyl group to the pigment (for example, carbon) can be mentioned. As a method of coating and dispersing the surface of a pigment with a resin, there is a method of encapsulating the pigment in microcapsules to make it dispersible in water. This can be rephrased as resin-coated pigment. In this case, not all of the pigments incorporated into the liquid composition need to be coated with resin, and uncoated pigments and partially coated pigments may be dispersed in the liquid composition as long as the effects of the present invention are not impaired. As a method of dispersing using a dispersant, there are methods of dispersing using known low-molecular-type dispersants and high-molecular-type dispersants typified by surfactants. As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used according to the pigment. RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalene sulfonate formalin condensate can also be suitably used as the dispersant. The above-mentioned dispersant may be used alone or in combination of two or more.

[0028] <Pigment dispersion> It is possible to obtain a liquid composition by mixing materials such as water and organic solvents with the pigment. It is also possible to produce a liquid composition by mixing materials such as water and organic solvents with a pigment dispersion obtained by mixing the pigment with other materials such as water and a dispersant. The pigment dispersion is obtained by mixing, dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. It is advisable to use a disperser for dispersion. Although there is no particular limitation on the particle size of the pigment in the pigment dispersion, from the viewpoint of good dispersion stability of the pigment and high image quality such as ejection stability and image density, the maximum frequency in terms of the maximum number is preferably 20 nm or more and 500 nm or less, and more preferably 20 nm or more and 150 nm or less. The particle size of the pigment can be measured using a particle size analyzer (NanoTrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.). The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of obtaining good ejection stability and increasing the image density, it is preferably 0.1% by mass or more and 50% by mass or less, and more preferably 0.1% by mass or more and 30% by mass or less. The pigment dispersion is preferably filtered and degassed of coarse particles with a filter, a centrifugal separator, etc. as necessary.

[0029] -Other components- Examples of the other components include surfactants, defoamers, antiseptics, rust preventives, pH adjusters, etc. as necessary.

[0030] --Surfactant-- As the surfactant, any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used. There is no particular limitation on the silicone surfactant, and it can be appropriately selected according to the purpose. Among them, those that do not decompose even at high pH are preferable. For example, side-chain modified polydimethylsiloxane, both-terminal modified polydimethylsiloxane, one-terminal modified polydimethylsiloxane, side-chain both-terminal modified polydimethylsiloxane, etc. can be mentioned. Those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferable because they exhibit good properties as an aqueous surfactant. In addition, a polyether-modified silicone surfactant can also be used as the silicone surfactant. For example, compounds in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylpolysiloxane can be mentioned.

[0031] As the fluorosurfactant, for example, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are particularly preferable because of their low foaming properties. Examples of the perfluoroalkyl sulfonic acid compounds include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate. Examples of the perfluoroalkyl carboxylic acid compounds include perfluoroalkyl carboxylic acid and perfluoroalkyl carboxylate. Examples of the polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain include sulfate esters of polyoxyalkylene ether polymers having a perfluoroalkyl ether group in the side chain and salts of polyoxyalkylene ether polymers having a perfluoroalkyl ether group in the side chain. Examples of the counter ions of the salts in these fluorosurfactants include Li, Na, K, NH4, NH3CH2CH2OH, NH2(CH2CH2OH)2, NH(CH2CH2OH)3, and the like.

[0032] Examples of the amphoteric surfactant include lauryl aminopropionate, lauryldimethyl betaine, stearyldimethyl betaine, lauryldihydroxyethyl betaine, and the like. Examples of the nonionic surfactant include polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and ethylene oxide adduct of acetylene alcohol. Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, and salts of polyoxyethylene alkyl ether sulfate. These surfactants may be used alone or in combination of two or more.

[0033] The content of the surfactant is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of excellent wettability and ejection stability and improved image quality, it is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.05% by mass or more and 5% by mass or less, based on the total amount of the liquid composition.

[0034] --Defoaming agent-- The defoaming agent is not particularly limited, and examples thereof include silicone-based defoaming agents, polyether-based defoaming agents, and fatty acid ester-based defoaming agents. These may be used alone or in combination of two or more. Among these, silicone-based defoaming agents are preferred from the viewpoint of excellent defoaming effect.

[0035] --Antiseptic and antifungal agent-- The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

[0036] --Rust inhibitor-- The rust inhibitor is not particularly limited, and examples thereof include acid sulfite and sodium thiosulfate.

[0037] --pH adjuster-- The pH adjuster is not particularly limited as long as it can adjust the pH to 7 or more, and examples thereof include amines such as diethanolamine and triethanolamine.

[0038] The physical properties of the liquid composition are not particularly limited and can be appropriately selected according to the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc. are in the following ranges. The viscosity of the liquid composition at 25°C is preferably 5 mPa·s or more and 30 mPa·s or less, more preferably 5 mPa·s or more and 25 mPa·s or less, from the viewpoints of improving the printing density and the character quality and obtaining good dischargeability. Here, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used to measure the viscosity. The measurement conditions are as follows: at 25°C, with a standard cone rotor (1°34’×R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and it can be measured in 3 minutes. The surface tension of the liquid composition is preferably 35 mN / m or less, more preferably 32 mN / m or less, at 25°C, from the viewpoints of the liquid composition being preferably leveled on the recording medium and shortening the drying time of the liquid composition. The pH of the liquid composition is preferably 7 to 12, more preferably 8 to 11, from the viewpoint of preventing corrosion of the metal members in contact with the liquid.

[0039] <Liquid discharge device> The liquid discharge device of the present invention includes a storage part that stores a liquid composition containing water, an organic solvent, and a polyurethane resin, an individual liquid chamber having a circulation flow path through which the liquid composition circulates, and a discharge head having a nozzle that communicates with the individual liquid chamber and discharges liquid droplets, and further includes other members as necessary.

[0040] The discharge head includes a pressure sensor that detects the pressure of the liquid composition and a circulation speed control part that controls the circulation speed of the liquid composition, and it is preferable to control the circulation speed so as to reach a desired pressure. Thereby, the liquid discharge device can suppress the drying of the liquid composition and maintain uniform dispersion. When the detected value of the pressure sensor is smaller than the desired pressure, it is preferable for the circulation speed control part to increase the circulation speed from the viewpoint of suppressing the drying of the liquid composition.

[0041] It is preferable that the discharge head has a piezo element that discharges liquid droplets, and the pressure sensor and the piezo element are integrally formed. It is preferable to detect by applying a load in the discharge direction of the liquid composition at a level where the piezo element does not discharge. Even when the ejection head does not eject, it is preferable to control the circulation rate based on the detected value of the pressure sensor.

[0042] Hereinafter, an example of an ejection head according to an embodiment of the present invention will be described with reference to FIGS. 1 to 12. FIG. 1 is an external perspective explanatory view of an ejection head according to an embodiment of the present invention, FIG. 2 is a cross-sectional explanatory view in a direction orthogonal to the nozzle array direction of the ejection head according to an embodiment of the present invention, FIG. 3 is a cross-sectional explanatory view in a direction parallel to the nozzle array direction of the ejection head according to an embodiment of the present invention, FIG. 4 is a plan explanatory view of a nozzle plate of the ejection head according to an embodiment of the present invention, FIG. 5 is a plan explanatory view of each member constituting a flow path member of the ejection head according to an embodiment of the present invention, and FIGS. 6A and 6B are plan explanatory views of each member constituting a common liquid chamber member of the ejection head according to an embodiment of the present invention. FIG. 7 is a block diagram showing an example of a circulation system of the present invention. FIG. 8 is a cross-sectional view taken along line A-A' of FIG. 2, and FIG. 9 is a cross-sectional view taken along line B-B' of FIG. 2.

[0043] This ejection head is formed by laminating and joining a nozzle plate 1, a flow path plate 2, and a diaphragm member 3 as a wall surface member. Further, it includes a piezoelectric actuator 11 for deforming 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 ejecting droplets made of a liquid composition. The flow path plate 2 forms an individual liquid chamber 6 communicating with the nozzle 4, a fluid resistance portion 7 communicating with the individual liquid chamber 6, 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-like members 41 to 45 from the nozzle plate 1 side, and the flow path member 40 is formed by laminating and joining these plate-like members 41 to 45 and the diaphragm member 3. The diaphragm member 3 has a filter portion 9 as an opening communicating with a common liquid chamber 10 formed by the liquid introduction portion 8 and the common liquid chamber member 20. The diaphragm member 3 is a wall surface member forming the wall surface of the individual liquid chamber 6 of the flow path plate 2. This diaphragm member 3 has a two-layer structure (not limited), and is formed of a first layer forming a thin portion and a second layer forming a thick portion from the flow path plate 2 side, and a deformable vibration region 30 is formed in a portion corresponding to the individual liquid chamber 6 in the first layer.

[0044] Here, as shown in FIG. 4, a plurality of nozzles 4 are arranged in a staggered pattern on the nozzle plate 1. In the plate-like member 41 that constitutes the flow path plate 2, as shown in FIG. 5A, a through groove portion 6a (meaning a groove-shaped through hole) that constitutes the individual liquid chamber 6, and through groove portions 51a and 52a that constitute the fluid resistance portion 51 and the circulation flow path 52 are formed. Similarly, in the plate-like member 42, as shown in FIG. 5B, a through groove portion 6b that constitutes the individual liquid chamber 6 and a through groove portion 52b that constitutes the circulation flow path 52 are formed. Similarly, in the plate-like member 43, as shown in FIG. 5C, a through groove portion 6c that constitutes the individual liquid chamber 6 and a through groove portion 53a that has the nozzle arrangement direction as the longitudinal direction and constitutes the circulation flow path 53 are formed. Similarly, in the plate-like member 44, as shown in FIG. 5D, a through groove portion 6d that constitutes the individual liquid chamber 6, a through groove portion 7a that serves as the fluid resistance portion 7, a through groove portion 8a that constitutes the liquid introduction portion 8, and a through groove portion 53b that has the nozzle arrangement direction as the longitudinal direction and constitutes the circulation flow path 53 are formed. Similarly, in the plate-like member 45, as shown in FIG. 5E, a through groove portion 6e that constitutes the individual liquid chamber 6, a through groove portion 8b (which becomes the filter downstream side liquid chamber) that has the nozzle arrangement direction as the longitudinal direction and constitutes the liquid introduction portion 8, and a through groove portion 53c that has the nozzle arrangement direction as the longitudinal direction and constitutes the circulation flow path 53 are formed. In the diaphragm member 3, as shown in FIG. 5F, a vibration region 30, a filter portion 9, and a through groove portion 53d that has the nozzle arrangement direction as the longitudinal direction and constitutes the circulation flow path 53 are formed. In this way, by configuring the flow path member by laminating and joining a plurality of plate-like members, a complex flow path can be formed with a simple configuration. With the above configuration, in the flow path member 40 composed of the flow path plate 2 and the diaphragm member 3, a fluid resistance portion 51, a circulation flow path 52, and a circulation flow path 53 in the thickness direction of the flow path member 40 that communicates with the circulation flow path 52 are formed along the surface direction of the flow path plate 2 that communicates with each individual liquid chamber 6. Note that the circulation flow path 53 communicates with a circulation common liquid chamber 50 described later.

[0045] On one hand, in the common liquid chamber member 20, a common liquid chamber 10 to which a liquid composition is supplied from a supply / circulation mechanism (not shown) and a circulation common liquid chamber 50 are formed. As shown in Fig. 6A, in the first common liquid chamber member 21 constituting the common liquid chamber member 20, a through-hole 25a for a piezoelectric actuator, a through-groove portion 10a serving as a downstream common liquid chamber 10A, and a grooved portion 50a with a bottom serving as the circulation common liquid chamber 50 are formed. Similarly, in the second common liquid chamber member 22, as shown in Fig. 6B, a through-hole 25b for a piezoelectric actuator and a groove portion 10b serving as an upstream common liquid chamber 10B are formed. Also, referring to Fig. 1, in the second common liquid chamber member 22, a through-hole 71a serving as a supply port portion communicating with one end portion in the nozzle arrangement direction of the common liquid chamber 10 and the supply port 71 is formed. Similarly, in the first common liquid chamber member 21 and the second common liquid chamber member 22, through-holes 81a and 81b communicating with the other end portion in the nozzle arrangement direction of the circulation common liquid chamber 50 (the end portion opposite to the through-hole 71a) and the circulation port 81 are formed. In Figs. 6A and 6B, the grooved portion with a bottom is shown with surface coating (the same applies to the following figures). In this way, the common liquid chamber member 20 is constituted by the first common liquid chamber member 21 and the second common liquid chamber member 22. The first common liquid chamber member 21 is joined to the diaphragm member 3 side of the flow path member 40, and the second common liquid chamber member 22 is laminated and joined to the first common liquid chamber member 21.

[0046] 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 communicating with the liquid introduction portion 8 and a circulation common liquid chamber 50 communicating with the circulation flow path 53. Also, the second common liquid chamber member 22 forms an upstream common liquid chamber 10B which is the remaining part of the common liquid chamber 10. At this time, the downstream common liquid chamber 10A which is a part of the common liquid chamber 10 and the circulation common liquid chamber 50 are arranged side by side in a direction orthogonal to the nozzle arrangement direction, and the circulation common liquid chamber 50 is arranged at a position projected into the common liquid chamber 10. As a result, the dimensions of the circulation common liquid chamber 50 are no longer restricted by the dimensions required for the flow paths formed by the flow path member 40, which include the individual liquid chambers 6, the fluid resistance portions 7, and the liquid introduction portions 8. Then, a part of 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 into the common liquid chamber 10, so that the width of the head in the direction orthogonal to the nozzle array direction can be suppressed, and an increase in the size of the head can be suppressed. The common liquid chamber member 20 forms the common liquid chamber 10 and the circulation common liquid chamber 50 to which the liquid composition is supplied from the head tank and the 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 driving means for deforming the vibration region 30 of the diaphragm member 3 is arranged. As shown in FIG. 3, this piezoelectric actuator 11 has a piezoelectric member joined on a base member 13, and the piezoelectric member is grooved by half-cut dicing to form a required number of columnar piezoelectric elements 12A and 12B in a comb shape at a predetermined interval with respect to one piezoelectric member. Here, the piezoelectric element 12A is used as a piezoelectric element to which a driving waveform is applied for driving, and the piezoelectric element 12B is used as a mere support without applying a driving waveform, but all the piezoelectric elements 12A and 12B can also be used as piezoelectric elements to be driven. The piezoelectric element 12A is joined to a convex portion 30a, which is an island-shaped thick portion formed in the vibration region 30 of the diaphragm member 3. The piezoelectric element 12B is joined to a convex portion 30b, which is a thick portion of the diaphragm member 3. This piezoelectric member is formed by alternately laminating a piezoelectric layer and an internal electrode. The internal electrodes are respectively drawn out to the end faces to provide external electrodes, and a flexible wiring member 15 is connected to the external electrodes.

[0047] In the discharge head configured as described above, for example, when the voltage applied to the piezoelectric element 12A is lowered from the reference potential, the piezoelectric element 12A contracts, the vibration region 30 of the diaphragm member 3 descends, and the volume of the individual liquid chamber 6 expands, so that the liquid composition flows into the individual liquid chamber 6. Thereafter, 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 diaphragm member 3 is deformed in the direction toward the nozzle 4 to contract the volume of the individual liquid chamber 6, whereby the liquid composition in the individual liquid chamber 6 is pressurized and the liquid composition is discharged from the nozzle 4. Then, the liquid composition is drawn from the common liquid chamber 10 by surface tension and filled with the liquid composition. Finally, due to the balance between the negative pressure defined by the supply tank, the circulation tank, and the water head difference and the surface tension of the meniscus, the meniscus surface is stabilized, enabling the transition to the next discharge operation. Note that the driving method of this head is not limited to the above example (pull - push strike), and pull strike, push strike, etc. can also be performed depending on the driving waveform applied. Further, in the above - described embodiment, a stacked piezoelectric element has been described as the pressure - generating means for applying pressure fluctuations to the individual liquid chamber 6, but it is not limited thereto, and a thin - film piezoelectric element can also be used. Furthermore, a heating resistor can be disposed in the individual liquid chamber 6 to generate bubbles by the heat generation of the heating resistor to apply pressure fluctuations, or an electrostatic force can be used to generate pressure fluctuations.

[0048] Next, an example of a liquid circulation system using the discharge head according to the present embodiment will be described with reference to FIG. 7. FIG. 7 is a block diagram showing the liquid circulation system according to the present embodiment. As shown in FIG. 7, the liquid circulation system includes a main tank, a 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, etc., and further includes a circulation speed control unit for adjusting the overall liquid circulation speed. The supply - side pressure sensor is between the supply tank and the discharge head and is connected to the supply flow path side connected to the supply port 71 (see FIG. 1) of the discharge head. The circulation - side pressure sensor is between the 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 discharge head. One side of the circulation tank is connected to the supply tank via the first liquid delivery pump, and the other side of the circulation tank is connected to the main tank via the second liquid delivery pump. As a result, the liquid composition flows into the discharge head from the supply tank through the supply port 71, is discharged from the circulation port, discharged into the circulation tank, and further, the liquid composition is circulated by being sent from the circulation tank to the supply tank by the first liquid delivery pump. In addition, a compressor is connected to the supply tank and is controlled so that a predetermined positive pressure is detected by the supply side pressure sensor. On the other hand, a vacuum pump 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, while circulating the liquid composition through the discharge head, the negative pressure of the meniscus can be kept constant. In addition, when droplets are discharged from the nozzles of the discharge head, the amounts of the liquid composition in the supply tank and the circulation tank decrease. Therefore, it is desirable to appropriately replenish the liquid composition from the main tank to the circulation tank using the second liquid delivery pump. The timing of replenishing the liquid composition from the main tank to the circulation tank can be controlled according to the detection results of a liquid level sensor provided in the circulation tank, such as replenishing the liquid composition when the liquid level height of the liquid composition in the circulation tank drops below a predetermined height.

[0049] Next, the circulation of the liquid composition in the discharge head will be described. As shown in FIG. 1, at the end of the common liquid chamber member 20, 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. The supply port 71 and the circulation port 81 are each connected to a supply tank and a circulation tank (see FIG. 7) for storing the liquid composition via tubes. Then, the liquid composition stored in the supply tank is supplied to the individual liquid chambers 6 through the supply port 71, the common liquid chamber 10, the liquid introduction section 8, and the fluid resistance section 7. Furthermore, while the liquid composition in the individual liquid chamber 6 is discharged from the nozzle 4 by the drive of the piezoelectric element 12, part or all of the liquid composition remaining in the individual liquid chamber 6 without being discharged is circulated to the circulation tank through the fluid resistance section 51, the circulation flow paths 52, 53, the circulation common liquid chamber 50, and the circulation port 81. Note that the circulation of the liquid composition can be carried out not only during the operation of the discharge head but also during the pause of the operation. By circulating during the pause of the operation, the liquid composition in the individual liquid chambers is always refreshed, and the aggregation and sedimentation of the components contained in the liquid composition can be suppressed, which is preferable.

[0050] Furthermore, as in the present invention, when titanium oxide particles that are likely to settle are contained in the liquid composition, if the circulation rate of the liquid composition is slow, sedimentation or adhesion of the particles may occur in the circulation flow path. Then, since the resistance in the circulation flow path becomes strong, the detected value by the supply-side pressure sensor or the circulation-side pressure sensor becomes small. In that case, the sedimentation part can be eliminated by controlling to increase the circulation rate of the liquid composition. Specifically, when the detected value by the supply-side pressure sensor or the circulation-side pressure sensor drops to a preset lower limit target value (for example, less than half of the normal pressure), the flow rate is controlled to increase the pressure to the target pressure (normal pressure) at a preset pressure change rate. The increased flow rate is maintained until a predetermined time has elapsed since the detected value reached the target pressure. Thereby, the sedimentation part can be eliminated.

[0051] Next, an example of the liquid discharge device according to the present invention will be described with reference to FIGS. 10 and 11. FIG. 10 is a plan explanatory view of the main part of the liquid discharge device, and FIG. 11 is a side explanatory view of the main part of the liquid discharge device. This liquid discharge device is a serial type device, and the carriage 403 reciprocates in the main scanning direction by the main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, etc. The guide member 401 is bridged between the left and right side plates 491A and 491B and holds the carriage 403 movably. Then, by the main scanning motor 405, the carriage 403 is reciprocated in the main scanning direction via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407. This carriage 403 is equipped with a liquid ejection unit 440 on which a ejection head 404 according to the present invention is mounted. The ejection head 404 of the liquid ejection unit 440 ejects liquid compositions of respective colors such as yellow (Y), cyan (C), magenta (M), and black (K). Further, the ejection head 404 is arranged with a nozzle row composed of a plurality of nozzles in a sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ejection direction facing downward. The liquid composition stored outside the ejection head 404 is supplied and circulated into the ejection head 404 by a supply and circulation mechanism for supplying the liquid composition to the ejection head 404. In this example, the supply and circulation mechanism is composed of 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 between the supply tank and the ejection head, and is connected to the supply flow path side connected to the supply port 71 of the ejection head. The circulation side pressure sensor is between the ejection head and the circulation tank, and is connected to the circulation flow path side connected to the circulation port 81 of the ejection head. This apparatus includes a conveyance mechanism 495 for conveying a sheet 410. The conveyance mechanism 495 includes a conveyance belt 412 as a conveyance means and a sub-scanning motor 416 for driving the conveyance belt 412. The conveyance belt 412 adsorbs the sheet 410 and conveys it to a position facing the ejection head 404. This conveyance belt 412 is an endless belt and is stretched between a conveyance roller 413 and a tension roller 414. Adsorption can be performed by electrostatic adsorption or air suction. Then, the conveyance belt 412 moves circularly in the sub-scanning direction by the conveyance roller 413 being rotationally driven via a timing belt 417 and a timing pulley 418 by the sub-scanning motor 416. Furthermore, on one side in the main scanning direction of the carriage 403, a maintenance and recovery mechanism 420 for maintaining and recovering the ejection head 404 is arranged on the side of the conveyance belt 412. The maintenance and recovery mechanism 420 is composed of, for example, a cap member 421 for capping the nozzle surface (the surface on which nozzles are formed) of the ejection head 404, a wiper member 422 for wiping the nozzle surface, and the like. The main scanning movement mechanism 493, the supply / circulation mechanism, the maintenance / restoration mechanism 420, and the conveyance mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C. In this apparatus configured as described above, the paper 410 is fed onto the conveyance belt 412 and adsorbed, and the paper 410 is conveyed in the sub-scanning direction by the circumferential movement of the conveyance belt 412. Therefore, while moving the carriage 403 in the main scanning direction, the ejection head 404 is driven according to the image signal to eject the liquid composition onto the stopped paper 410 to form an image. Thus, in this apparatus, since it is provided with the ejection head according to the present invention, a high-quality image can be stably formed.

[0052] Next, another example of the liquid ejection unit according to the present invention will be described with reference to FIG. 12. FIG. 12 is a plan explanatory view of the main part of the liquid ejection unit. This liquid ejection unit is composed of a housing portion formed by side plates 491A, 491B, and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and an ejection head 404 among the members constituting the apparatus for ejecting the liquid composition. Note that a liquid ejection unit can also be configured by further attaching at least one of the above-described maintenance / restoration mechanism 420 and supply / circulation mechanism to, for example, the side plate 491B of this liquid ejection unit.

[0053] In the present invention, the "ejection head" is a functional component that ejects and sprays a liquid composition from a nozzle. The liquid composition to be ejected only needs to have a viscosity and surface tension that can be ejected from the head, and is not particularly limited, but preferably has a viscosity of 30 mPa·s or less at normal temperature and pressure, or by heating or cooling. More specifically, it is a solution, suspension, emulsion, etc. containing solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, and edible materials such as natural pigments. These can be used, for example, in applications such as inkjet inks and surface treatment liquids.

[0054] As an energy source for ejecting the liquid composition, those using electrothermal conversion elements such as piezoelectric actuators (laminated piezoelectric elements and thin film piezoelectric elements) and thermal actuators using heating resistors, and electrostatic actuators composed of a diaphragm and a counter electrode are included. The "liquid ejection unit" is an integrated unit of functional components and mechanisms in the ejection head, and is an assembly of components related to the ejection of the liquid composition. For example, the "liquid ejection unit" includes those in which at least one of the supply / circulation mechanism, carriage, maintenance and recovery mechanism, and main scanning movement mechanism is combined with the ejection head. Here, integration includes, for example, those in which the ejection head and functional components and mechanisms are fixed to each other by fastening, adhesion, engagement, etc., and those in which one is movably held with respect to the other. Also, the ejection head and functional components and mechanisms may be configured to be detachable from each other. For example, as a liquid ejection unit, there is one in which the ejection head and the supply / circulation mechanism are integrated. Also, there is one in which they are connected to each other by a tube or the like and the ejection head and the supply / circulation mechanism are integrated. Here, a unit including a filter can also be added between the supply / circulation mechanism and the ejection head of these liquid ejection units. Also, as a liquid ejection unit, there is one in which the ejection head and the carriage are integrated. In addition, as a liquid ejection unit, there is one in which a discharge head is movably held by a guide member that forms part of a scanning movement mechanism, and the discharge head and the scanning movement mechanism are integrated. In addition, as a liquid ejection unit, there is one in which a cap member that is part of a maintenance and recovery mechanism is fixed to a carriage to which a discharge head is attached, and the discharge head, the carriage, and the maintenance and recovery mechanism are integrated. In addition, as a liquid ejection unit, there is one in which a tube is connected to a discharge head to which a supply / circulation mechanism or a flow path member is attached, and the discharge head and the supply mechanism are integrated. Through this tube, a liquid composition from a liquid storage source is supplied to the discharge head. The main scanning movement mechanism shall include a guide member alone. Also, the supply mechanism shall include a tube alone and a loading unit alone.

[0055] In the present invention, the "liquid ejection device" is a device that includes a discharge head or a liquid ejection unit and drives the discharge head to eject a liquid composition. The device for ejecting a liquid composition includes not only a device capable of ejecting a liquid composition onto an object to which the liquid composition can adhere, but also a device capable of ejecting a liquid composition into the air and into a liquid. This "liquid ejection device" can also include means related to the feeding, conveyance, and paper discharge of an object to which a liquid composition can adhere, as well as other pretreatment devices, post-treatment devices, and the like. For example, as a "liquid ejection device", there is an image forming device that ejects a liquid composition to form an image on a sheet, and a three-dimensional modeling device (three-dimensional shaping device) that ejects a shaping liquid onto a powder layer formed by layering powder in order to shape a three-dimensional object (three-dimensional shaped object). Also, the "liquid ejection device" is not limited to those in which a significant image such as characters or figures is visualized by the ejected droplets. For example, it includes those that form a pattern or the like that has no meaning by itself, and those that shape a three-dimensional image.

[0056] The above-mentioned "substrate to which the liquid composition can adhere" means a substrate to which the liquid composition can adhere at least temporarily, including those to which the liquid composition adheres and adheres firmly, those to which the liquid composition adheres and penetrates, etc. Specific examples include recording media such as paper, recording paper, recording sheets, films, cloth, and wallpaper, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder beds), organ models, media such as test cells, etc. Unless otherwise particularly limited, all substrates to which the liquid composition can adhere are included. The material of the above-mentioned "substrate to which the liquid composition can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as the liquid composition can adhere even temporarily. Also, the "liquid composition" only needs to have a viscosity and surface tension that can be discharged from the discharge head, and is not particularly limited, but it is preferably one whose viscosity becomes 30 mPa·s or less at normal temperature and normal pressure, or by heating or cooling. More specifically, it includes solutions, suspensions, emulsions, etc. containing solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional additive materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, edible materials such as natural pigments, etc. These can be used, for example, in applications such as inkjet inks, surface treatment liquids, components for electronic elements and light-emitting elements, and liquids for forming electronic circuit resist patterns, and material liquids for three-dimensional modeling.

[0057] Also, the "liquid discharge device" includes, but is not limited to, a device in which the discharge head and a substrate to which the liquid composition can adhere move relative to each other. Specific examples include serial type devices that move the discharge head and line type devices that do not move the discharge head. In addition, as the "liquid discharge device", there are also treatment liquid coating devices that discharge a treatment liquid onto paper for the purpose of modifying the surface of the paper, and injection granulation devices that inject a composition liquid in which raw materials are dispersed in a solution through a nozzle to granulate the particles of the raw materials. Also, in the terms of the present invention, image formation, recording, printing, copying, printing, modeling, etc. are all synonymous.

Examples

[0058] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments at all.

[0059] (Production Example 1 of Pigment Dispersion) <Preparation of Cyan Pigment Dispersion> A cyan pigment dispersion was obtained in the same manner as the method described in [Pigment Surface Modification Treatment] - Method A - of JP-A-2012-207202. Specifically, 20 g of C.I. Pigment Blue 15:3 (trade name: Chromophine Blue, manufactured by Dainichi Seika Kogyo Co., Ltd.), 20 mmol of the compound described in the following structural formula (A), and 200 mL of ion-exchanged water were mixed with a Silverson mixer (6,000 rpm (0.6% by mass)) at room temperature to obtain a slurry. When the pH of the obtained slurry was higher than 4, 20 mmol of nitric acid was added. After 30 minutes, sodium nitrite (20 mmol) dissolved in a small amount of ion-exchanged water was slowly added to the above slurry. Further, it was heated to 60 °C with stirring and reacted for 1 hour. A modified pigment in which the compound described in the following structural formula (A) was added to the surface of C.I. Pigment Blue 15:3 was obtained. Subsequently, by adjusting the pH to 10 with an aqueous NaOH solution, a modified pigment dispersion was obtained after 30 minutes. Ultrafiltration using a dialysis membrane was performed using the modified pigment dispersion and ion-exchanged water, and further ultrasonic dispersion was performed to obtain a cyan pigment dispersion (self-dispersing type) having a bisphosphonic acid group as a hydrophilic functional group with a pigment concentration of 15% by mass.

[0060] [Structural Formula (A)] [Chemical Formula]

[0061] (Production Example 2 of Pigment Dispersion) <Preparation of Magenta Pigment Dispersion> In Production Example 1 of the pigment dispersion, except that 20 g of C.I. Pigment Blue 15:3 was changed to 20 g of C.I. Pigment Red 122 (trade name: Toner Magenta EO02, manufactured by Clariant Japan K.K.), a magenta pigment dispersion having a pigment concentration of 15% by mass was prepared in the same manner as in Production Example 1 of the pigment dispersion.

[0062] (Production Example 3 of the pigment dispersion) <Preparation of Yellow Pigment Dispersion> In Production Example 1 of the pigment dispersion, except that 20 g of C.I. Pigment Blue 15:3 was changed to 20 g of C.I. Pigment Yellow 74 (trade name: First Yellow 531, manufactured by Dainichi Seika Kogyo Co., Ltd.), a yellow pigment dispersion having a pigment concentration of 15% by mass was prepared in the same manner as in Production Example 1 of the pigment dispersion.

[0063] (Production Example 4 of the pigment dispersion) <Preparation of Black Pigment Dispersion> In Production Example 1 of the pigment dispersion, except that 20 g of C.I. Pigment Blue 15:3 was changed to 20 g of carbon black (NIPEX 160, manufactured by Degussa), a black pigment dispersion having a pigment concentration of 15% by mass was prepared in the same manner as in Production Example 1 of the pigment dispersion.

[0064] (Production Example 1 of resin particles) <Preparation of Polycarbonate Urethane Resin Particle Liquid> Into a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, 1,500 g of polycarbonate diol (reaction product of 1,6 - hexanediol and dimethyl carbonate (number average molecular weight (Mn): 1,200)), 220 g of 2,2 - dimethylolpropionic acid (hereinafter sometimes referred to as "DMPA"), and 1,347 g of N - methylpyrrolidone (hereinafter sometimes referred to as "NMP") were charged under a nitrogen stream and heated to 60°C to dissolve DMPA. Next, 1,445 g of 4,4'-dicyclohexylmethane diisocyanate and 2.6 g of dibutyltin dilaurate (catalyst) were added, and the mixture was heated to 90°C. A urethanization reaction was carried out over 5 hours to obtain an isocyanate-terminated urethane prepolymer. The reaction mixture was cooled to 80°C, 149 g of triethylamine was added thereto, 4,340 g was withdrawn from the mixture, and it was added to a mixed solution of 5,400 g of water and 15 g of triethylamine under strong stirring. Next, 1,500 g of ice was charged, 626 g of a 35 mass% aqueous solution of 2-methyl-1,5-pentanediamine was added, and a chain extension reaction was carried out. The solvent was distilled off so that the solid content concentration became 40 mass%, and a polycarbonate urethane resin particle liquid was obtained.

[0065] <Measurement of glass transition temperature> Next, for the obtained polycarbonate urethane resin particle liquid, the glass transition temperature (Tg) of the polyurethane resin was measured using a differential scanning calorimeter (TA-60WS and DSC-60, manufactured by Shimadzu Corporation). First, 4 g of the resin emulsion was placed in a 50 mm diameter petri dish made of tetrafluoroethylene·perfluoroalkyl vinyl ether copolymer (PFA) so as to spread uniformly. After drying at 50°C for 1 week, 5.0 mg was placed in an aluminum sample container from the obtained resin film. The sample container was placed on a holder unit and set in an electric furnace. Then, under a nitrogen atmosphere, the temperature was raised from 0°C to 150°C at a heating rate of 10°C / min, and then, after the temperature was lowered from 150°C to -80°C at a cooling rate of 5°C / min, the temperature was further raised from -80°C to 150°C at a heating rate of 10°C / min to measure the DSC curve. From the obtained DSC curve, when analyzed by the midpoint method from the inflection point during the second heating using the analysis program in the DSC-60 system, Tg was -20°C.

[0066] (Production Example 2 of resin particles) In the same manner as in Production Example 1 of resin particles, except that the polycarbonate diol (the reaction product of 1,6 - hexanediol and dimethyl carbonate (number average molecular weight (Mn): 1,200)) was changed to a polycarbonate diol (the reaction product of 1,6 - hexanediol and dimethyl carbonate (number average molecular weight (Mn): 1,600)), a polycarbonate urethane resin particle liquid 2 with a solid content concentration of 40% by mass was obtained in the same manner as in Production Example 1 of resin particles. When the obtained polycarbonate urethane resin particle liquid 2 was measured in the same manner as in Production Example 1 of the resin particle liquid, the Tg was - 30°C.

[0067] (Production Example 3 of Resin Particles) In the same manner as in Production Example 1 of resin particles, except that the polycarbonate diol (the reaction product of 1,6 - hexanediol and dimethyl carbonate (number average molecular weight (Mn): 1,200)) was changed to a polycarbonate diol (the reaction product of 1,6 - hexanediol and dimethyl carbonate (number average molecular weight (Mn): 500)), a polycarbonate urethane resin particle liquid 3 with a solid content concentration of 40% by mass was obtained in the same manner as in Production Example 1 of resin particles. When the obtained polycarbonate urethane resin particle liquid 3 was measured in the same manner as in Preparation Example 1 of the resin particle liquid, the Tg was - 10°C.

[0068] (Production Example 4 of Resin Particles) <Preparation of Polyester Urethane Resin Particle Liquid> In Production Example 1 of resin particles, except that the polycarbonate diol (the reaction product of 1,6 - hexanediol and dimethyl carbonate (number average molecular weight (Mn): 1,200)) was changed to a polyester polyol (「PolyLite OD - X - 2251」, manufactured by DIC Corporation, weight average molecular weight: 2,000), a polyester urethane resin particle liquid with a solid content concentration of 30% by mass was obtained in the same manner as in Production Example 1 of resin particles. Next, when the glass transition temperature (Tg) of the resin was measured for the obtained polyester urethane resin particle liquid in the same manner as in Production Example 1 of resin particles, it was 57°C.

[0069] (Production Example 5 of Resin Particles) In the same manner as in Production Example 4 of resin particles, except that the polyester polyol (“Polylite OD-X-2251”, manufactured by DIC Corporation, weight average molecular weight: 2,000) was changed to a polyester polyol (“Polylite OD-X-2420”, manufactured by DIC Corporation, weight average molecular weight: 2,000), a polyester urethane resin particle liquid 5 with a solid content concentration of 30% by mass was obtained in the same manner as in Production Example 4 of resin particles. Regarding the obtained polyester urethane resin particle liquid 5, when the glass transition temperature (Tg) of the resin was measured in the same manner as in Production Example 1 of resin particles, it was 60°C.

[0070] (Preparation Example 6 of Resin Particles) In the same manner as in Production Example 4 of resin particles, except that the polyester polyol (“Polylite OD-X-2251”, manufactured by DIC Corporation, weight average molecular weight: 2,000) was changed to a polyester polyol (“Polylite OD-X-2722”, manufactured by DIC Corporation, weight average molecular weight: 2,000), a polyester urethane resin particle liquid 6 with a solid content concentration of 30% by mass was obtained in the same manner as in Production Example 4 of the resin particles. Regarding the obtained polyester urethane resin particle liquid 6, when the glass transition temperature (Tg) of the resin was measured in the same manner as in Production Example 1 of resin particles, it was 50°C.

[0071] (Production Example 1 of Ink) (Production of Ink 1) 15.0% by mass of the black pigment dispersion (pigment solid content concentration: 15% by mass), 12.0% by mass of the polycarbonate urethane resin particle liquid of Production Example 1 of the resin particles (solid content concentration: 40% by mass), 8.0% by mass of the polyester urethane resin particle liquid of Production Example 2 of the resin particles (solid content concentration: 30% by mass), 20.0% by mass of 1,2-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), 10.0% by mass of 3-methoxy-3-methyl-1-butanol (manufactured by Kuraray Co., Ltd.), 5.0% by mass of 2,3-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), and 3.0% by mass of 2-ethylhexyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.0% by mass of a polyether-modified surfactant (trade name: Wet270, manufactured by TEGO), 0.1% by mass of a preservative with the trade name Proxel LV (manufactured by Arch Chemicals Japan Co., Ltd.), and 25.9% by mass of high-purity water were added, and these were mixed and stirred, and then filtered through a polypropylene filter with an average pore diameter of 1.0 μm to obtain Ink 1.

[0072] (Production Examples 2 to 12 of Ink and Comparative Production Examples 1 to 4 of Ink) <Production of Inks 2 to 16> In Production Example 1 of Ink, Inks 2 to 16 were obtained in the same manner as in Production Example 1 of Ink, except that the materials and contents shown in Tables 1 to 3 were changed. Note that for the polyester resin particle liquid of Comparative Production Example 4 (Ink 16) of Ink, KT-0507 (Tg: -25°C, manufactured by Unitika Ltd.) was used.

[0073]

Table 1

[0074]

Table 2

[0075]

Table 3

[0076] (Examples 1 to 12 and Comparative Examples 1 to 4) <Image formation> Next, using the inkjet ejection device shown in FIG. 10 having a discharge head with the circulation mechanism shown in FIGS. 1 to 9, the obtained inks 1 to 12 and inks 14 to 16 were each used to print a solid image on a PE wallpaper media (Sunlight 110, manufactured by TAYA Corporation). After printing, the solid image was dried on a hot plate (NINOS ND-1, manufactured by AS ONE Corporation) set at 100° C. for 1 hour. Note that the ink 13 used in Comparative Example 1 was printed as a solid image on a PE wallpaper media (Sunlight 110, manufactured by TAYA Corporation) using an inkjet ejection device equipped with a GEN5 head (manufactured by Ricoh Printing Systems Co., Ltd.) (without a circulation mechanism). After printing, the solid image was dried on a hot plate set at 100° C. for 1 hour.

[0077] Next, the "discharge reliability", "non-transferability", and "rub resistance" were evaluated as follows. The results are shown in Tables 4 to 6.

[0078] <Discharge reliability> The discharge reliability of inks 1 to 12 and inks 14 to 16 was evaluated using the inkjet ejection device shown in FIG. 10 having a discharge head with the circulation mechanism shown in FIGS. 1 to 9. The discharge reliability of ink 13 was evaluated using an inkjet ejection device equipped with a GEN5 head (manufactured by Ricoh Printing Systems Co., Ltd.) (without a circulation mechanism). First, each of the obtained inks was filled into the inkjet ejection device, and after printing a nozzle check pattern and confirming that no "nozzle clogging" occurred, the inkjet printer was left for 12 hours. After leaving it for 12 hours, a nozzle check pattern was printed without performing cleaning maintenance, the number of occurrences of "nozzle clogging" was counted, and the "discharge reliability" was evaluated based on the following evaluation criteria. It is desirable for the evaluation to be ○ for actual use. Note that the "nozzle clogging" means that ink is not ejected and a normal ink image cannot be drawn. [Evaluation criteria] ○: Two or fewer nozzle cloggings △: Three or more and four or fewer nozzle cloggings ×: Five or more nozzle detachments

[0079] <Non-transferability> Two solid images created were cut into 3 cm × 3 cm sizes, overlapped so that the two solid images were in contact with each other, and a pressure of 1.0 MPa was applied for 10 seconds from above with a press machine. Then, the two evaluation samples were peeled off, and the ease of peeling at this time and the presence or absence of damage to the image after peeling were visually observed, and "non-transferability" was evaluated based on the following evaluation criteria. It is desirable in actual use that the evaluation is ○. [Evaluation Criteria] ○: When peeling off the two solid images, there was no feeling of sticking and they peeled off naturally, and no color transfer to the respective base materials was observed △: When peeling off the two solid images, there was a slight feeling of sticking, but no damage to the image was observed ×: When peeling off the two solid images, there was a feeling of sticking, and slight damage to the image was observed

[0080] <Scratch resistance> Each created solid image was rubbed 25 times with a dry cotton (Kanakin No. 3) under a load of 200 g, and the state of the image was visually observed, and "scratch resistance" was evaluated based on the following evaluation criteria. It is desirable in actual use that the evaluation is △ or higher. [Evaluation Criteria] ○: The image did not change △: Some scratches remained, but the image density was not affected ×: The image density decreased

[0081]

Table 4

[0082]

Table 5

[0083]

Table 6

[0084] Examples of aspects of the present invention are as follows. <1> A housing portion that houses a liquid composition containing water, an organic solvent, and a polyurethane resin, A discharge head having an individual liquid chamber having a circulation flow path through which the liquid composition circulates, and a nozzle that communicates with the individual liquid chamber and discharges droplets composed of the liquid composition, and having, A liquid discharge device characterized in that the content of the polyurethane resin is 7% by mass or more and 20.0% by mass or less in terms of solid content. <2> The liquid discharge device according to <1>, wherein the polyurethane resin contains at least one of a polycarbonate polyurethane resin and a polyester polyurethane resin. <3> The glass transition temperature of the polycarbonate polyurethane resin is -30°C or higher and -10°C or lower, The liquid discharge device according to <2>, wherein the glass transition temperature Tg of the polyester polyurethane resin is 50°C or higher and 60°C or lower. <4> The discharge head has a pressure sensor that detects the pressure of the liquid composition and a circulation speed control unit that controls the circulation speed of the liquid composition, and controls the circulation speed so as to reach a desired pressure. The liquid discharge device according to any one of <1> to <3>. <5> The liquid discharge device according to <4>, wherein the circulation speed control unit controls the circulation speed of the liquid composition to be faster when the detected value of the pressure sensor is smaller than the desired pressure. <6> A housing portion that houses ink containing water, an organic solvent, and a polyurethane resin, A discharge head having an individual liquid chamber having a circulation flow path through which the ink circulates, and a nozzle that communicates with the individual liquid chamber and discharges droplets composed of the ink, and having, An inkjet printing device characterized in that the content of the polyurethane resin is 7% by mass or more and 20.0% by mass or less in terms of solid content. <7> A discharging step of discharging droplets composed of the liquid composition from the nozzles of a discharging head while circulating a liquid composition containing water, an organic solvent, and a polyurethane resin in individual liquid chambers is included. The liquid discharging method is characterized in that the content of the polyurethane resin is 7% by mass or more and 20.0% by mass or less in terms of solid content. <8> An inkjet printing method including a discharging step of discharging droplets composed of the ink from the nozzles of a discharging head while circulating an ink containing water, an organic solvent, and a polyurethane resin in individual liquid chambers. The inkjet printing method is characterized in that the content of the polyurethane resin is 7% by mass or more and 20.0% by mass or less in terms of solid content.

[0085] According to the liquid discharging device described in any one of <1> to <5> above, the inkjet printing device described in <6> above, the liquid discharging method described in <7> above, and the inkjet printing method described in <8> above, various problems in the prior art can be solved and the object of the present invention can be achieved.

Explanation of reference numerals

[0086] 404 Discharging head

Prior art documents

Patent documents

[0087]

Patent Document 1

Claims

1. A housing portion that houses a liquid composition containing water, an organic solvent, and a polyurethane resin; A discharge head having an individual liquid chamber having a circulation flow path through which the liquid composition circulates, and a nozzle that communicates with the individual liquid chamber and discharges droplets composed of the liquid composition; characterized by the content of the polyurethane resin being 7% by mass or more and 20.0% by mass or less in terms of solid content; the polyurethane resin including a polycarbonate polyurethane resin and a polyester polyurethane resin; the glass transition temperature Tg of the polycarbonate polyurethane resin being -30°C or higher and -10°C or lower; and the glass transition temperature Tg of the polyester polyurethane resin being 50°C or higher and 60°C or lower. A liquid discharge device.

2. The discharge head according to claim 1, further comprising a pressure sensor that detects the pressure of the liquid composition and a circulation speed control unit that controls the circulation speed of the liquid composition, and controlling the circulation speed so as to achieve a desired pressure.

3. The liquid discharge device according to claim 2, wherein when the detected value of the pressure sensor is smaller than the desired pressure, the circulation speed control unit controls the circulation speed of the liquid composition to increase.

4. A housing portion that houses an ink containing water, an organic solvent, and a polyurethane resin; A discharge head having an individual liquid chamber having a circulation flow path through which the ink circulates, and a nozzle that communicates with the individual liquid chamber and discharges droplets composed of the ink; characterized by the content of the polyurethane resin being 7% by mass or more and 20.0% by mass or less in terms of solid content; the polyurethane resin including a polycarbonate polyurethane resin and a polyester polyurethane resin; the glass transition temperature Tg of the polycarbonate polyurethane resin being -30°C or higher and -10°C or lower; and the glass transition temperature Tg of the polyester polyurethane resin being 50°C or higher and 60°C or lower. An inkjet printing device.

5. A discharge step of discharging droplets composed of the liquid composition from a nozzle of a discharge head while circulating a liquid composition containing water, an organic solvent, and a polyurethane resin in an individual liquid chamber, the content of the polyurethane resin being 7% by mass or more and 20.0% by mass or less in terms of solid content; the polyurethane resin including a polycarbonate polyurethane resin and a polyester polyurethane resin; The glass transition temperature Tg of the polycarbonate polyurethane resin is -30°C or higher and -10°C or lower, The glass transition temperature Tg of the polyester polyurethane resin is 50°C or higher and 60°C or lower, and a liquid discharge method characterized by this. **Claim 6** including a discharge step of discharging droplets composed of the ink from a nozzle of a discharge head while circulating the ink containing water, an organic solvent, and a polyurethane resin in an individual liquid chamber, the content of the polyurethane resin is 7% by mass or more and 20.0% by mass or less in terms of solid content, the polyurethane resin includes a polycarbonate polyurethane resin and a polyester polyurethane resin, the glass transition temperature Tg of the polycarbonate polyurethane resin is -30°C or higher and -10°C or lower, the glass transition temperature Tg of the polyester polyurethane resin is 50°C or higher and 60°C or lower, and an inkjet printing method characterized by this.

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