Ink, ink set, inkjet printing device and inkjet printing method

Abstract

To provide an ink excellent in discharge stability, ink filtration properties, storage stability and fastness.SOLUTION: There is provided an ink used in an inkjet printing device having an inkjet head equipped with a nozzle plate having a nozzle for discharging an ink and an ink repellent layer containing a silicon resin or a fluororesin on the ink discharging surface side surface, wherein the ink contains a color material, an organic solvent, resin particles and water, the resin particles contain urethane resin particles, a cumulative 90% particle diameter (D90) based on the volume of the resin particles is 50 nm or less, the particle number of resin particles of 0.5 μm or more is 50000 particles / 5 μL or less and the maximum absorbance in the range of 1700 cm-1 or more and 1750 cm-1 or less in the FT-IR of the resin particles is 0.10 or more and 0.40 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink, an ink set, an inkjet printing apparatus, and an inkjet printing method. [Background technology]

[0002] Patent Document 1 describes a white ink that has a dynamic surface tension (10 ms) of 33 mN / m to 42 mN / m and a static surface tension of 23 mN / m to 30 mN / m, and contains a polyether or polyester urethane resin. Patent Document 2 describes a clear ink in which the volume average particle size of the resin particles is 50 nm or less and the Tg is 0°C to 50°C. Patent Document 3 describes an ink containing carbon black having a hydrophilic group and carbon black dispersed with a sodium naphthalenesulfonate formalin condensate. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is to provide an ink that is excellent in ejection stability, ink filterability, storage stability, and fastness. [Means for solving the problem]

[0004] The present invention, which solves the above problems, relates to an ink as described in (1) below. (1) An ink for use in an inkjet printing device having an inkjet head equipped with a nozzle plate having a nozzle for ejecting ink and an ink-repellent layer containing a silicone resin or a fluororesin on the surface of the ink ejection surface side, the ink contains a colorant, an organic solvent, resin particles, and water; the resin particles include urethane resin particles, The resin particles have a volume-based cumulative 90% particle diameter (D90) of 50 nm or less, the number of particles of 0.5 μm or more of the resin particles is 50,000 particles / 5 μL or less, and the resin particles have a FT-IR peak at 1700 cm -1 More than 1750cm -1 An ink characterized in that the maximum absorbance in the following region is 0.10 or more and 0.40 or less. [Effects of the Invention]

[0005] The present invention can provide an ink that is excellent in ejection stability, ink filterability, storage stability, and fastness. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing an example of an inkjet printing apparatus of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing an example of the overall configuration of the inkjet printing apparatus of the present invention. [Figure 3] FIG. 3 is an explanatory plan view showing an example of a nozzle plate in the inkjet printing apparatus of the present invention. [Figure 4] FIG. 4 is an enlarged cross-sectional view illustrating a nozzle portion of a nozzle plate in the inkjet printing apparatus of the present invention. [Figure 5] FIG. 5 is a diagram showing a state in which an ink-repellent layer is formed by applying silicone resin using a dispenser. DETAILED DESCRIPTION OF THE INVENTION

[0007] <Ink> The organic solvent, water, coloring material, resin, additives, etc. used in the ink will be described below.

[0008] <Organic solvents> The organic solvent used in the present invention is not particularly limited, and any water-soluble organic solvent can be used, including, for example, polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds. Specific examples of the water-soluble organic solvent include 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, and the like. Polyhydric alcohols such as 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, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether. polyhydric alcohol alkyl ethers such as 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; propylene carbonate; and ethylene carbonate. It is preferable to use an organic solvent having a boiling point of 250° C. or less, since it not only functions as a wetting agent but also provides good drying properties.

[0009] Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol. Specific examples of glycol ether compounds 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.

[0010] Polyol compounds having 8 or more carbon atoms and glycol ether compounds can improve the permeability of ink when paper or cloth is used as a recording medium.

[0011] The content of the organic solvent in the ink is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of the drying property and ejection reliability of the ink, however, the content is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

[0012] Silicone oil may also be added to prevent ink from adhering to the nozzle surface of the inkjet head. Silicone oil is a non-aqueous compound, and because the surface of the ink is covered with this non-aqueous component, even if ink adheres to the nozzle surface, the ink does not solidify on the nozzle surface, and the ink can be removed by the cleaning operation of the main body. The content of silicone oil is preferably 0.01% by mass to 1% by mass, more preferably 0.01% by mass to 0.5% by mass, based on the total amount of ink.

[0013] <Water> The water content in the ink is not particularly limited and can be selected appropriately depending on the purpose, but from the viewpoint of the drying property and ejection reliability of the ink, it is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass to 60% by mass.

[0014] <Colorant> The coloring material is not particularly limited, and pigments and dyes can be used. The pigment may be an inorganic pigment or an organic pigment. These may be used alone or in combination of two or more. Mixed crystals may also be used. Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments. As inorganic pigments, titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used. In addition, examples of organic pigments that can be used include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments), dye chelates (e.g., basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, and aniline black. Of these pigments, those with good affinity for the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used. Specific examples of pigments for black include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (CI Pigment Black 11), and titanium oxide; and organic pigments such as aniline black (CI Pigment Black 1). In addition, for color, CI 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, CI Pigment Yellow Ranges 5, 13, 16, 17, 36, 43, 51, CI Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 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 (Red Iron), 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, CI Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38; CI Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone, or two or more types may be used in combination. Examples of the dyes include CI Acid Yellow 17, 23, 42, 44, 79, 142, CI Acid Red 52, 80, 82, 249, 254, 289, CI Acid Blue 9, 45, 249, CI Acid Black 1, 2, 24, 94, CI Food Black 1, 2, CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, CI Direct Red 1, 4, 9, 80, 81, 225, 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, CI Directed Black 19, 38, 51, 71, 154, 168, 171, 195, and CI Reactive Red. 14, 32, 55, 79, 249, and CI Reactive Black 3, 4, and 35.

[0015] Methods for dispersing a pigment to obtain an ink include a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of dispersing the pigment by coating the surface of the pigment with a resin, and a method of dispersing the pigment using a dispersant. As a method for introducing a hydrophilic functional group into a pigment to make it a self-dispersible pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (e.g., carbon) to make it dispersible in water can be mentioned. One method for dispersing a pigment by coating its surface with a resin is to encapsulate the pigment in microcapsules to make it dispersible in water. This can be rephrased as a resin-coated pigment. In this case, it is not necessary for all of the pigments blended into the ink to be coated with resin; uncoated or partially coated pigments may be dispersed in the ink, provided that the effects of the present invention are not impaired. Examples of the method for dispersing using a dispersant include a method for dispersing using a known low molecular weight dispersant or a high molecular weight dispersant, such as a surfactant. The dispersant used is a compound represented by the following general formula (1) or (2): By using this dispersant, it is possible to obtain an aqueous pigment dispersion and an aqueous ink having a small average particle size and excellent storage stability. The content of the dispersant represented by the following general formula (1) or (2) is preferably 0.01% by mass or more and 0.5% by mass or less, and more preferably 0.1% by mass or more and 0.4% by mass or less, relative to 1% by mass of the pigment in the ink. A content within this range is preferable because it allows for an ink with a small volume average particle size to be obtained, improving the dispersibility of the pigment and optimizing the viscosity of the ink.

[0016] [ka] (In general formula (1), m represents an integer of 1 to 4.) [ka] (In general formula (2), R 1 represents an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 8 carbon atoms, or an allyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200.

[0017] It is preferable to use a naphthalenesulfonic acid formalin condensate as the compound represented by general formula (1) and polyoxyethylene-β-naphthyl ether as the compound represented by general formula (2), since good dispersibility can be obtained.

[0018] <Fluorescent whitening agents> Fluorescent brightening agents absorb invisible short-wavelength ultraviolet light and convert it into visible purple to blue light, and are also called fluorescent dyes. These fluorescent brightening agents may be used to achieve a higher visual density. The fluorescent whitening agent used may be, for example, one having a structural unit represented by the following structural formula (1) or (2).

[0019] [ka] [ka]

[0020] Those having the structural unit represented by the structural formula (1) are benzoxazole or derivatives thereof, and those having the structural unit represented by the structural formula (2) are coumarin or derivatives thereof, and may be either hydrophilic or hydrophobic.

[0021] The content of the fluorescent brightening agent in the ink is preferably 0.001% by mass or more and 1% by mass or less, and more preferably 0.005% by mass or more and 0.2% by mass or less. By setting the content of the fluorescent brightening agent to 0.001% by mass or more, a high concentration can be visually observed. On the other hand, by setting the content of the fluorescent brightening agent to 1% by mass or less, concentration quenching, in which incident light is quickly absorbed or fluorescence intensity is reduced due to collisions between molecules, can be suppressed. Examples of commercially available fluorescent brighteners include TINOPAL OB (manufactured by BASF), Nikkafluor OB, Nikkabright PAW-L, and Nikkafluor MCT (manufactured by Nippon Chemical Industry Co., Ltd.).

[0022] <Fluorescent whitening enhancer> In the present invention, a fluorescent brightening enhancer may be used to improve the effect of the fluorescent brightening agent. The fluorescent brightening enhancer improves the dispersibility of the fluorescent brightening agent and migrates it to the surface, thereby improving the effect of the fluorescent brightening agent, and specifically, is a polyether polyol. The content of the fluorescent brightening enhancer in the ink is preferably 0.2% by mass or more and 2% by mass or less, and more preferably 0.5% by mass or more and 2% by mass or less, relative to the content of the colorant. By setting the content of the fluorescent brightening enhancer to 0.2% by mass or more relative to the content of the colorant, a high visual density can be achieved. On the other hand, by setting the content of the fluorescent brightening enhancer to 2% by mass or less relative to the content of the colorant, it is possible to improve ejection stability. As a fluorescent whitening enhancer, for example, a commercially available product such as Optiact I-10 manufactured by San Nopco Corporation can be mentioned.

[0023] <Pigment dispersion> Ink can be obtained by mixing a pigment with water, an organic solvent, or other materials. Alternatively, ink can be produced by mixing a pigment with other materials such as water and a dispersant to form a pigment dispersion, and then mixing the resulting mixture with water, an organic solvent, or other materials. The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and optionally other components, and adjusting the particle size. Dispersion is preferably performed using a disperser. Although there are no particular restrictions on the particle size of the pigment in the pigment dispersion, the maximum frequency, calculated as 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, in order to improve the dispersion stability of the pigment and image quality such as ejection stability and image density. The particle size of the pigment can be measured using a particle size analyzer (Nanotrac 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 depending on the purpose. However, from the viewpoint of obtaining good ejection stability and increasing image density, the content 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. It is preferable that the pigment dispersion is degassed, if necessary, by filtering coarse particles using a filter, a centrifugal separator, or the like.

[0024] <Resin> The resin contained in the ink must be a urethane resin. Other resins can be selected appropriately depending on the purpose, and examples include polyester resins, acrylic resins, vinyl acetate resins, styrene resins, butadiene resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, and acrylic silicone resins. Resin particles made of these resins may also be used. The resin particles are dispersed in water as a dispersion medium to form a resin emulsion, which can be mixed with materials such as coloring materials and organic solvents to obtain an ink. The resin particles may be appropriately synthesized or commercially available. These may be used alone or in combination of two or more types of resin particles.

[0025] <d90> The volume-based cumulative 90% particle diameter (D90) of the resin particles is 50 nm or less, and more preferably 20 nm or more and 40 nm or less, in order to obtain good fixability and high image hardness. The D90 was measured, for example, using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.) using a sample diluted with ion-exchanged water so that the pigment concentration (mass concentration) in the measurement sample was 0.01 mass%.

[0026] <Number of particles 0.5 μm or larger> In order to obtain good ink filtering properties, the number of resin particles is preferably 50,000 particles / 5 μL or less, and more preferably 17,000 particles / 5 μm or more and 30,000 particles / 5 μL or less. The particle count was measured using, for example, a coarse particle measuring device (Accusizer 780APS, manufactured by Anton Paar) as follows. First, the measurement sample was diluted with ion-exchanged water until it was within the measurement range, and then the number of particles of 0.5 μm or more in 5 μL of the sample was calculated based on the measurement results, converted to a solids concentration of 1%.

[0027] 1700cm in FT-IR of resin particles -1 More than 1750cm -1 The maximum absorbance in the following range is preferably 0.10 or more and 0.40 or less, and more preferably 0.20 or more and 0.30 or less. The maximum absorbance can be measured using, for example, a Fourier transform infrared spectrometer (Nicolet iS20 FT-IR spectrophotometer, manufactured by Thermo Fisher Scientific).

[0028] The content of the resin particles is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of fixability and storage stability of the ink, however, the content is preferably from 1% by mass to 30% by mass, and more preferably from 5% by mass to 20% by mass, of the total amount of the ink. When the resin particles are urethane resin particles, the content of the urethane resin particles is preferably 1% by mass or more and 20% by mass or less.

[0029] To improve image density and fixability, the ratio (R / P) of the colorant amount (P) to the total resin amount (R) is preferably 0.10 or more and 2.00 or less. The total resin amount refers to all resins contained in the ink, including resins used to coat the colorant and resins contained in the ink as binder resins. Resin refers to organic substances with a weight-average molecular weight of 5,000 or more.

[0030] <Additives> If necessary, surfactants, antifoaming agents, antiseptic and antifungal agents, antirust agents, pH adjusters, etc. may be added to the ink.

[0031] <Surfactant> In the ink of the present invention, silicon compounds, acetylene compounds, and polyoxyethylene alkyl ether compounds can be suitably used as surfactants. Surfactants are added to improve penetration or wettability into the substrate, and generally have a low HLB (Hydrophilic Lipophilic Balance). However, surfactants with a low HLB generally have low solubility in vehicles containing water, which can lead to problems such as poor storage stability and separation. The present invention includes any one of a silicon-based compound represented by the following general formula (3), an acetylene-based compound represented by the following general formula (4), and a polyoxyethylene alkyl ether-based compound represented by the following general formula (5). The compounds of the following general formulas (3) to (5) can be identified by using, for example, GC-MS and NMR. [ka] (In the general formula (3), a represents an integer of 1 to 8, and R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) [ka] (In the general formula (4), R1 to R4 represent an alkyl group, m+n represents an integer of 1 to 20, and Y represents an acetylene group.) [ka] (In the general formula (5), n represents an integer of 3 to 11.)

[0032] The content of the silicon compound is preferably 0.001% by mass or more and 3% by mass or less, and more preferably 0.01% by mass or more and 1% by mass or less, based on the total amount of the ink. The silicon-based compound may be a synthesized compound or a commercially available product, such as KF-6028, KF-6038 (manufactured by Shin-Etsu Chemical Co., Ltd.), SAG002, or SAG503A (manufactured by Nissin Chemical Industry Co., Ltd.), and among these, KF6028 and SAG503A are particularly preferred from the viewpoint of storage stability. In the present invention, it is preferable to use an acetylene-based compound represented by the general formula (4) having an HLB value of 8 or more and 13 or less. When the HLB value is 8 or more, the compound is easily dissolved in a vehicle containing water, and separation is difficult, resulting in improved storage stability. On the other hand, when the HLB value is 13 or less, the compound has good defoaming properties. The content of the acetylene-based compound is preferably 0.1% by mass or more and 3.0% by mass or less, and more preferably 0.5% by mass or more and 2.0% by mass or less, based on the total amount of the ink.

[0033] The HLB value of the surfactant used in the present invention is a value proposed by Griffin to evaluate the hydrophilicity of a compound, and refers to a value calculated by the following mathematical formula (1): The HLB value according to the Griffin method indicates a value within the range of 0 to 20, and the larger the value, the more hydrophilic the compound is. HLB value = 20 x (mass % of hydrophilic groups) = 20 × (total formula weight of hydrophilic groups / molecular weight of surfactant) Formula (1)

[0034] The acetylene-based compound may be synthesized appropriately or may be a commercially available product. Examples of commercially available products include Surfynol 104 series, Surfynol 420, 440, 465, 485, Olfine PD-002W, EXP.4001, EXP.4200, EXP.4123 (manufactured by Nissin Chemical Industry Co., Ltd.), and Acetinol E60, E100, E200 (manufactured by Kawaken Fine Chemicals Co., Ltd.). Among these, Surfynol 440, 465, Olfine PD-002W, EXP.4001, EXP.4200, EXP.4123 (manufactured by Nissin Chemical Industry Co., Ltd.) are particularly preferred from the viewpoint of antifoaming properties and storage stability. These compounds may be used alone or in combination of two or more.

[0035] The content of the polyoxyethylene alkyl ether compound is preferably 0.1% by mass or more and 2.0% by mass or less, and more preferably 0.5% by mass or more and 1.0% by mass or less, based on the total amount of ink. When the content of the compound represented by general formula (5) is 0.1% by mass or more based on the total amount of ink, the dots do not spread after the ink lands on the recording medium, and the desired image density can be obtained. When the content is 2.0% by mass or less, the surface tension does not decrease, and after ejection from an ink ejection means such as an inkjet head, the time it takes for the ink to return to the nozzle does not become long, and there is no risk of frequent deflection of the ink. The polyoxyethylene alkyl ether compound may be a synthesized compound or a commercially available product. Examples of commercially available products include TRITON (registered trademark) HW-1000, TMN-3, TMN-6, TMN-100X, and TMN-10 (manufactured by The Dow Chemical Company). Among these, TRITON (registered trademark) HW-1000 and TMN-6 are particularly preferred. These compounds may be used alone or in combination of two or more.

[0036] The above surfactants may be used in combination with other surfactants, and for example, any of fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants may be used.

[0037] Silicone surfactants are not particularly limited and can be appropriately selected depending on the purpose.Among them, those that do not decompose even at high pH are preferred, such as side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end modified polydimethylsiloxane of side chain, and those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferred because they exhibit good properties as aqueous surfactants.In addition, polyether-modified silicone surfactants can also be used as the silicone surfactant, and examples thereof include compounds in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane. As fluorosurfactants, for example, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain are particularly preferred due to their low foaming properties. Examples of the perfluoroalkyl sulfonic acid compounds include perfluoroalkyl sulfonic acids and perfluoroalkyl sulfonate salts. Examples of the perfluoroalkyl carboxylic acid compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylate salts. Examples of the polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain include sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain, and salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain. Counterions of the salts in these fluorosurfactants include Li, Na, K, NH, NHCHCHOH, NH(CHCHOH), NH(CHCHOH), and the like.

[0038] Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.

[0039] Examples of nonionic surfactants include polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl amines, polyoxyethylene alkyl amides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, ethylene oxide adducts of acetylene alcohol, and the like. Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, salts of polyoxyethylene alkyl ether sulfates, and the like. These may be used alone or in combination of two or more.

[0040] <Defoamer> There are no particular restrictions on the defoamer. Examples include silicone defoamers, polyether defoamers, fatty acid ester defoamers, acetylene defoamers, and the like. These may be used alone or in combination of two or more. Among these, silicone defoamers are preferred because of their excellent defoaming effect.

[0041] <Antiseptic and antifungal agent> There are no particular restrictions on the antiseptic and antifungal agent. Examples include 1,2-benzisothiazolin-3-one and the like.

[0042] <Rust inhibitor> There are no particular restrictions on the rust inhibitor. Examples include acid sulfite, sodium thiosulfate, and the like.

[0043] <pH adjuster> There are no particular restrictions on the pH adjuster as long as it can adjust the pH to 7 or higher. Examples include amines such as diethanolamine and triethanolamine.

[0044] The physical properties of the ink are not particularly limited and can be appropriately selected depending on the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc. are within the following ranges. The ink viscosity at 25°C is preferably 5 mPa·s or more and 30 mPa·s or less, and more preferably 5 mPa·s or more and 25 mPa·s or less, in order to improve print density and character quality and obtain good ejection properties. Here, viscosity can be measured using, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.). Measurement conditions include 25°C, a standard cone rotor (1°34' x R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes. The surface tension of the ink is preferably 30.0 mN / m or more and 40.0 mN / m or less, and more preferably 30 mN / m or more and 35.0 mN / m or less at 25°C, in order to ensure that the ink is well leveled on the recording medium and the drying time of the ink is shortened. The pH of the ink is preferably 7 to 12, and more preferably 8 to 11, from the viewpoint of preventing corrosion of metal members that come into contact with the ink.

[0045] <Pretreatment liquid> The pretreatment liquid contains a flocculant, an organic solvent, resin particles, and water, and may also contain surfactants, antifoaming agents, pH adjusters, antiseptic and antifungal agents, antirust agents, and the like, as required. The organic solvent, surfactant, antifoaming agent, pH adjuster, antiseptic / fungal agent, and antirust agent may be the same as those used in ink, and other materials used in known treatment liquids may also be used. The flocculant has the effect of flocculating the coloring material in the ink. Examples of the flocculant include magnesium metal salts and calcium metal salts. The flocculant is preferably a calcium metal salt because it improves image density, and among calcium metal salts, calcium chloride is particularly preferred.

[0046] <Post-processing liquid> The post-treatment liquid is not particularly limited as long as it can form a transparent layer. The post-treatment liquid can be obtained by selecting and mixing organic solvents, water, resins, surfactants, antifoaming agents, pH adjusters, antiseptic and antifungal agents, anti-rust agents, etc. as needed. The post-treatment liquid may be applied to the entire recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

[0047] <Recording Media> The recording medium used for recording is not particularly limited, but examples thereof include plain paper, glossy paper, special paper, cloth, film, OHP sheets, and general-purpose printing paper.

[0048] <Recordings> The ink recorded matter of the present invention comprises an image formed on a recording medium using the ink of the present invention. Recording can be performed using an inkjet recording apparatus and an inkjet recording method to produce a recorded product.

[0049] <Recording device> 1, the inkjet recording device used in the present invention comprises a device main body 101, a paper feed tray 102 for loading paper sheets that are attached to the device main body 101, and a paper discharge tray 103 for stocking paper sheets that have images recorded on them that are attached to the device main body 101. The top surface of an upper cover 111 of the device main body 101 is flat, and a front surface 112 of a front cover of the device main body 101 is inclined diagonally downward and rearward relative to the top surface, and below the inclined front surface 112 of the front cover are provided the paper discharge tray 103 and paper feed tray 102 that protrude forward (toward the viewer). Furthermore, at one end of the front surface 112, there is an ink cartridge loading section 104 that protrudes forward from the front surface 112 and is lower than the upper cover 111, and this ink cartridge loading section 104 has an openable front cover 115 for installing and removing ink cartridges.

[0050] As shown in FIG. 2, inside the device body 101, a carriage 133 is held slidably in the main scanning direction by a guide rod 131 and a stay 132, which are guide members that are hung horizontally on the left and right side plates, and is moved and scanned by a main scanning motor (not shown). This carriage 133 is fitted with a recording head 134 consisting of an inkjet head that ejects ink droplets of each color (white (W), yellow (Y), cyan (C), magenta (M), and black (K)), with multiple ink ejection ports arranged in a direction intersecting the main scanning direction and the ink droplet ejection direction facing downward.

[0051] The inkjet head constituting the recording head 134 may be equipped with an energy generating means for ejecting ink, such as a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses an electrothermal conversion element such as a heating resistor to utilize a phase change caused by film boiling of a liquid, a shape memory alloy actuator that uses a metal phase change caused by a temperature change, or an electrostatic actuator that uses static electricity.

[0052] The carriage 133 also carries sub-tanks 135 of the respective colors for supplying ink of the respective colors to the recording head 134. Ink is replenished and supplied to these sub-tanks 135 from the ink cartridges according to the present invention loaded in the ink cartridge loading section 104 via ink supply tubes (not shown).

[0053] On the other hand, as a paper feed section for feeding the paper 142 loaded on the paper stacking section 141 of the paper feed tray 103, there is provided a crescent roller (paper feed roller) 143 that separates and feeds the paper 142 one sheet at a time from the paper stacking section 141, and a separation pad 144 that faces the paper feed roller 143 and is made of a material with a large friction coefficient, and this separation pad 144 is urged toward the paper feed roller 143.

[0054] On the other hand, the conveying section for conveying the paper 142 fed from this paper feed section below the recording head 134 includes a conveying belt 151 for electrostatically attracting and conveying the paper 142, a counter roller 152 for sandwiching and conveying the paper 142 fed from the paper feed section via a guide 145 between the conveying belt 151, a conveying guide 153 for turning the paper 142 fed vertically upward by 90 degrees so that it follows the conveying belt 151, and a tip pressure roller 155 urged toward the conveying belt 151 by a pressing member 154. Also, a charging roller 156 is provided as charging means for charging the surface of the conveying belt 151.

[0055] Here, the conveyor belt 151 is an endless belt that is stretched between a conveyor roller 157 and a tension roller 158 and configured to rotate in the belt conveyance direction. The conveyor belt 151 has a surface layer that serves as a paper adsorption surface and is formed, for example, from a pure resin material with a thickness of about 40 μm that is not subjected to resistance control, such as pure ETFE material, and a back layer (earth layer) that is made of the same material as the surface layer and has resistance control using carbon. Further, a guide member 161 is disposed on the rear side of the conveyor belt 151 in correspondence with the printing area of the recording head 134 . Furthermore, as a paper discharge section for discharging the paper 142 recorded by the recording head 134, a separation claw 171 for separating the paper 142 from the conveyor belt 151, a paper discharge roller 172 and a paper discharge roller 173 are provided, and a paper discharge tray 103 is provided below the paper discharge roller 172.

[0056] The recording paper is adsorbed to the conveyor belt and ejected by the ejection rollers, which press down from above. The conveyor belt and rollers are the primary means of transporting the recording paper, and the ejection rollers in this printer only play a secondary role, such as preventing the paper from floating. This makes it possible to significantly reduce the number of rollers compared to conventional inkjet printers, thereby reducing smudges and scratches on the recorded image. A duplex paper feed unit 181 is detachably mounted on the rear surface of the apparatus main body 101. This duplex paper feed unit 181 takes in paper 142 returned by the reverse rotation of the conveyor belt 151, turns it over, and feeds paper 142 again between the counter roller 152 and the conveyor belt 151. A manual paper feed unit 182 is also provided on the top surface of this duplex paper feed unit 181.

[0057] When double-sided printing is performed, the paper is transported to the double-sided paper feed unit and reversed immediately after printing on the front side, without waiting time. The ink of the present invention has high permeability into paper and, because it has little moisture, evaporates quickly, making it possible to reverse the paper without smearing the printed image, without the need for drying time or drying means such as a heater. In the inkjet recording device configured in this manner, the paper 142 is separated and fed one sheet at a time from the paper feed section, and the paper 142 fed vertically upward is guided by a guide 145, sandwiched between a conveyor belt 151 and a counter roller 152 and conveyed, and further, the leading edge is guided by a conveyor guide 153 and pressed against the conveyor belt 151 by a leading edge pressure roller 155, and the conveying direction is changed by 90°. At this time, the conveyor belt 157 is charged by the charging roller 156, and the paper 142 is electrostatically attracted to the conveyor belt 151 and conveyed. There, by driving the recording head 134 in accordance with an image signal while moving the carriage 133, ink droplets are ejected onto the stationary paper 142 to record one line, and after conveying the paper 142 a predetermined distance, the next line is recorded. Upon receiving a recording end signal or a signal indicating that the rear end of the paper 142 has reached the recording area, the recording operation is terminated and the paper 142 is discharged to the paper discharge tray 103.

[0058] An AC bias is applied to the charging belt, alternating positive and negative charges are applied to the conveyor belt at a constant pitch, and the recording paper is attracted to the conveyor belt by the electrostatic force generated by the intermittent micro-electric fields. The preferred range of the applied AC bias is ±1.2 kV to ±2.6 kV, and more preferably ±1.6 kV to ±2.4 kV. If the AC bias value is below the lower limit, sufficient attraction force cannot be obtained, and if it is above the upper limit, the tiny droplets generated when ink is ejected from the nozzle are affected by the charge and return to the head without landing on the paper, soiling the area around the head. The influence of the charge on the tiny droplets is related to the electrical properties of the ink. In other words, the higher the electrical conductivity of the ink, the more difficult it is to eject. Since the droplets become more susceptible to electrical charges, the ink's electrical conductivity must be reduced. When it is detected that the remaining amount of ink in the sub-tank 135 is low, a predetermined amount of ink is replenished from the ink cartridge to the sub-tank 135.

[0059] FIG. 3 is an explanatory plan view showing an example of a nozzle plate in the inkjet printing apparatus of the present invention. Here, the nozzle plate used in the inkjet printing apparatus of the present invention will be described with reference to FIGS. FIG. 3 is a plan view of the nozzle plate, and FIG. 4 is an enlarged cross-sectional view of one nozzle portion.

[0060] The nozzle plate 10 has a nozzle substrate 20 in which holes (hereinafter sometimes referred to as "nozzles") 21 that become nozzles 11 for ejecting liquid are formed, an intermediate layer 30 formed on the surface of the nozzle substrate 20, and an ink-repellent layer 40 formed on the liquid ejection surface side. The nozzle substrate 20 is, for example, a metal flat plate member. Although a stainless steel metal flat plate member is used as the nozzle substrate 20, the nozzle substrate 20 is not limited to this. The nozzle 11 has a cylindrical portion 21a on the liquid ejection surface side, and a truncated cone portion 21b on the surface opposite to the liquid ejection surface.

[0061] The intermediate layer 30 is composed of one or more layers that serve as a base layer, such as an SiO2 layer, a silane coupling agent layer, etc. This intermediate layer 30 does not necessarily have to be provided. The ink-repellent layer 40 is a layer containing a silicone resin. The ink-repellent layer 40 has a sloped region 41 formed on the outer periphery of the nozzle 11, where the sloped surface 41a is inclined in a direction in which the film thickness becomes thinner toward the edge 11a of the nozzle 11. A region 42 of the ink-repellent layer 40 other than the sloped region 41 is flat and has a substantially constant film thickness. The sloped surface 41a of the sloped region 41 may be inclined linearly or curvedly inclined in cross section. The average film thickness of the ink-repellent layer 40 on the ink ejection surface side is preferably 1 μm or more and 3 μm or less. Furthermore, the intermediate layer 30 is preferably a silane coupling agent layer having an amino group as a layer underlying the ink-repellent layer 40. This allows the amino group to interact with the liquid-repellent film material, resulting in high adhesion.

[0062] (Method for manufacturing nozzle members of inkjet heads) FIG. 5 is a diagram showing a configuration in which an ink-repellent layer 31 is formed on the surface of a nozzle plate 32 by applying silicone resin using a dispenser 34 according to this embodiment. A dispenser 34 is arranged to apply a silicone solution to the ink ejection surface side of the Ni electroformed nozzle plate 32, and the dispenser 34 is scanned while ejecting silicone resin from the tip of the needle 35 so that a predetermined constant distance is maintained between the nozzle plate 32 and the tip of the needle 35, thereby selectively forming a silicone resin coating on the ink ejection surface of the nozzle plate 32.

[0063] In this embodiment, room-temperature curing silicone resin SR2411 (manufactured by Dow Corning Toray Co., Ltd.) was used as the silicone resin. However, some silicone was observed to have infiltrated into the nozzle holes and the back surface of the nozzle plate. The thickness of the silicone resin coating selectively formed in this way was 1.2 μm, and the surface roughness (Ra) was 0.18 μm.

[0064] The ink-repellent layer is made of a silicone-based water-repellent material or a fluorine-based water-repellent material. By using the ink of the present invention in an inkjet head printing device in which such a material is used for the ink-repellent layer of the nozzle plate, it is possible to prevent the ink from over-wetting the nozzle plate from the beginning, and to prevent the ink from being ejected in a deviated manner or from being particulate abnormally from the beginning. The silicone-based water-repellent material may be a room temperature curing liquid silicone resin or elastomer, which is preferably applied to the surface of a substrate and left in the air at room temperature to polymerize and harden to form an ink-repellent coating.

[0065] The above-mentioned silicone-based water-repellent material may be a heat-curing liquid silicone resin or elastomer, which is applied to the surface of the substrate and cured by heat treatment to form an ink-repellent coating. The silicone-based water-repellent material may be an ultraviolet-curable liquid silicone resin or elastomer, which is applied to the surface of the substrate and cured by irradiating it with ultraviolet light to form an ink-repellent coating. The viscosity of the silicone-based water-repellent material is preferably 1000 cp or less.

[0066] The critical surface tension of the ink-repellent layer is preferably 5.0 mN / m or more and 40.0 mN / m or less, and more preferably 5.0 mN / m or more and 30.0 mN / m or less. If the critical surface tension exceeds 30.0 mN / m, the nozzle plate may become too wet with ink over long-term use, which may result in deflected ink discharge or abnormal particle formation during repeated printing. If the critical surface tension exceeds 40.0 mN / m, the nozzle plate may become too wet with ink from the beginning, which may result in deflected ink discharge or abnormal particle formation from the beginning.

[0067] In the present invention, the terms image formation, recording, printing, printing, etc. are all synonymous.

[0068] Recording medium, media, and printed material are all synonymous terms.

[0069] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified. Unless otherwise specified, preparation, evaluation, etc. were carried out under conditions of 23°C and 50% humidity.

[0070] (Preparation of pigment dispersion) <Preparation of black pigment dispersion> A mixed slurry was prepared by premixing 250 parts of carbon black (Degussa), 50 parts of the compound represented by formula (1) (Takesurf A-45-K, manufactured by Takemoto Oil & Fat Co., Ltd.), and 700 parts of distilled water. The mixture was then circulated and dispersed using a disk-type media mill (UMA type, manufactured by Kotobuki Industries Co., Ltd.) with 0.015 mm zirconia beads (filling rate: 70%) at a peripheral speed of 6 m / s and a liquid temperature of 10°C until a volume average particle diameter of approximately 100 nm was achieved. Coarse particles were then separated using a centrifuge (Model-7700, manufactured by Kubota Shoji Co., Ltd.). The mixture was then filtered through a 1.2 μm pore filter, and the water content was adjusted to a solids concentration of 15%, yielding a black pigment dispersion with a pigment concentration of 15%.

[0071] <Preparation of blue pigment dispersion> A mixed slurry was obtained by premixing 250 parts of Pigment Blue 15:3 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), 50 parts of the compound represented by formula (2) (Paionin D-7240, manufactured by Takemoto Yushi Co., Ltd.), and 700 parts of distilled water. The mixture was then circulated and dispersed using a disk-type media mill (UMA type, manufactured by Kotobuki Industries Co., Ltd.) with 0.015 mm zirconia beads (filling rate 70%) at a peripheral speed of 6 m / s and a liquid temperature of 10°C until a volume average particle diameter of approximately 100 nm was achieved. Coarse particles were then separated using a centrifuge (Model-7700, manufactured by Kubota Shoji Co., Ltd.). The mixture was then filtered through a 1.2 μm pore filter, and the water content was adjusted to a solids concentration of 15%, yielding a blue pigment dispersion with a pigment concentration of 15%.

[0072] <Preparation of red pigment dispersion> A red pigment dispersion with a pigment concentration of 15% was obtained in the same manner as in the preparation of the blue pigment dispersion, except that Pigment Blue 15:3 was changed to Pigment Red 122 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.).

[0073] <Preparation of yellow pigment dispersion> A yellow pigment dispersion with a pigment concentration of 15% was obtained in the same manner as in the preparation of the blue pigment dispersion, except that Pigment Blue 15:3 was changed to Pigment Yellow 74 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.).

[0074] <Preparation of White Pigment Dispersion> 25 parts of titanium oxide (STR-100, manufactured by Sakai Chemical Industry Co., Ltd.), 5 parts of a compound represented by the general formula (1) (Takesurf A-45-K, manufactured by Takemoto Oil & Fat Co., Ltd.), and 70 parts of water were mixed, and the mixture was dispersed with zirconia beads having a diameter of 0.3 mm in a bead mill (Research Lab, manufactured by Shinmaru Enterprises Co., Ltd.) at a filling rate of 60% and a speed of 8 m / s for 5 minutes to obtain a white dispersion with a pigment concentration of 25%.

[0075] The other ink components used were as follows:

[0076] <Flocculant> Flocculant A (Kanto Chemical Co., Ltd., magnesium sulfate heptahydrate) Flocculant B (Kanto Chemical Co., Ltd., calcium chloride)

[0077] <Resin particles> Urethane resin particles A (manufactured by Daicel Allnex Co., Ltd., VTW6460 / 35WA) D90 particle size: 48nm, 0.5μm or more Number of particles: 13,000 pieces / 5μL, 1700cm -1 ~1750cm -1 Maximum absorbance: 0.37 Urethane resin particles B (Taisei Fine Chemical Co., Ltd. WBR-016U) D90 particle size: 24nm, 0.5μm or more Number of particles: 11,000 pieces / 5μL, 1700cm -1 ~1750cm -1 Maximum absorbance: 0.14 Urethane resin particles C (UBE UW1527DF-C1) D90 particle size: 48nm, 0.5μm or more Number of particles: 48,196 pieces / 5μL, 1700cm -1 ~1750cm -1 Maximum absorbance: 0.39 Urethane resin particles D (Mitsui Chemicals, Inc., Takelac W6110) D90 particle size: 55nm, 0.5μm or more Number of particles: 18,000 pieces / 5μL, 1700cm -1 ~1750cm -1 Maximum absorbance: 0.51 Urethane resin particles E (manufactured by Daicel Allnex Co., Ltd., VTW1265 / 36WA) D90 particle size: 49nm, 0.5μm or more Number of particles: 450,000 pieces / 5μL, 1700cm -1 ~1750cm -1 Maximum absorbance: 0.39 Urethane resin particles F (UBE STD-6001D-C1) D90 particle size: 82nm, 0.5μm or more Number of particles: 850,000 pieces / 5μL, 1700cm -1 ~1750cm -1 Maximum absorbance: 0.48 The physical properties of the urethane resin particles are shown in Table 1 below.

[0078] [Table 1]

[0079] <Organic solvents> Organic solvent A (Glycerin manufactured by Sakamoto Pharmaceutical Co., Ltd.) Organic solvent B (Tokyo Chemical Industry Co., Ltd., 1,3-butylene glycol)

[0080] <Surfactant> Silicone surfactant (Nissin Chemical Industry Co., Ltd., SAG503A) *Compound of general formula (3) · Acetylene-based surfactant (Surfynol 440 manufactured by Nissin Chemical Industry Co., Ltd.) ※ Compound of general formula (4) · Polyoxyethylene alkyl ether-based surfactant (TRITON (registered trademark) HW-1000 manufactured by Dow Chemical Co., Ltd.) ※ Compound of general formula (5) · Fluorine-based surfactant (PF656 manufactured by OMNOVA Co., Ltd.)

[0081] <Silicone oil> · Polyether-modified silicone oil (KF353 manufactured by Shin-Etsu Chemical Co., Ltd.)

[0082] <Defoaming agent> · 2,4,7,9-Tetramethyldecane-4,7-diol (Surfynol AD01 manufactured by Nissin Chemical Industry Co., Ltd.)

[0083] <pH adjuster> · 2-Amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0084] <Antiseptic and antifungal agent> · LV(S) (manufactured by Abisia Co., Ltd.)

[0085] (Preparation of ink) <Examples 1 to 22, Comparative Examples 1 to 3> Table 2-1 to Table 2-3 show the composition of the ink for each example and comparative example. First, for each example and comparative example, an organic solvent, a surfactant, other additives (defoaming agent, pH adjuster, antibacterial agent, etc.), and ion-exchanged water shown in Table 2-1 to Table 2-3 were mixed and then stirred for 1 hour. Next, resin particles were added and stirred for another 1 hour to mix uniformly. Then, various pigment dispersions were added and stirred for another 1 hour to mix uniformly. This mixture was pressure-filtered through a polyvinylidene fluoride membrane filter with an average pore diameter of 0.8 μm to remove coarse particles and dust, and ink was obtained. Table 2-1 to Table 2-3 show the physical properties and characteristics of the obtained ink.

[0086] <Examples 23 to 34> The pretreatment liquid and ink were combined as shown in Table 3, and printing was performed on a dark cotton T-shirt (Toms Printstar 00085-CVT Black) by introducing the ink into a textile printer (Mastermind MMP813BT) equipped with a nozzle plate with an ink-repellent layer containing silicone resin. The printing conditions were 1,440 dpi x 720 dpi, 80 mm x 80 mm solid printing, and a deposition amount of 200 mg / cm. 2 The printed matter was then heat-treated at 170°C for 3 minutes to dry, and a print sample was obtained. After printing white, black, cyan, magenta, and yellow inks were printed. When printing with the pretreatment liquid before printing with ink, the pretreatment liquid was introduced into a textile printer (Mastermind MMP813BT) and a solid image was printed over the entire surface. The deposition amount was 3.0 mg / cm. 2 It was decided. The image density was evaluated for each example, and the image density values are shown in Table 3.

[0087] The evaluation methods for the ink and printed matter are shown below. (Ink property measurement) <Ink viscosity measurement> The viscosity of the ink was measured at 25°C using a viscometer (RE-85L manufactured by Toki Sangyo Co., Ltd.).

[0088] <Ink surface tension measurement> The surface tension of the ink was measured at 25° C. by the plate method (Wilhelmy method) using a static surface tensiometer (DY-300 manufactured by Kyowa Interface Science Co., Ltd.).

[0089] (Ink characteristic evaluation) <Evaluation of ejection stability> The printing conditions for producing the print sample were 1,440 dpi x 720 dpi, 180 mm x 200 mm, 50% gray solid printing, and 10 T-shirts (textile prints) were printed in succession, and the results were evaluated according to the following criteria. Note that if the number of nozzles that had missing nozzles was three or less, it was considered to be at an acceptable level. (Evaluation criteria) ○: Number of nozzles with missing nozzles: 0 △: Number of nozzles with missing nozzles: 1 to 3 ×: Number of nozzles with missing nozzles: 4 or more

[0090] <Evaluation of washing fastness> The print sample was washed 10 times using a fully automatic washing machine (Sanyo Electric Co., Ltd., ASW-45A1 model). The K image density before and after washing was measured using an image density colorimeter (X-Rite Co., Ltd., exact). The evaluation criteria were as follows: if the difference in image density before and after washing was 0.10 or less, the print was deemed suitable for practical use. (Evaluation criteria) ○: Image density difference before and after washing is 0.05 or less △: Image density difference before and after washing: 0.06 to 0.10 ×: Image density difference before and after washing is 0.11 or more

[0091] <Evaluation of ink filtration> 100ml of each inkjet recording ink was pressure filtered through a 25mm diameter 0.2µm cellulose acetate membrane filter, and the number of filters used for filtration was counted to evaluate filterability. The filtration method was to assemble the ink into a 20ml syringe and then pressurize it by hand, replacing the filter when the filtration rate reached less than one drop per second. The evaluation criteria were as follows: 3 or fewer filters were considered to be practically usable. (Evaluation criteria) ○: Number of filters used: 1 or less △: Number of filters used: 2 or more and 3 or less ×: Number of filters used: 4 or more

[0092] <Evaluation of storage stability> The ink was placed in an airtight container (As One Eye Boy) and stored in a thermostatic chamber (ESPEC PR-3J) at 70°C for 14 days. The viscosity was measured before and after storage using a viscometer (Toki Sangyo RE-85L) and evaluated according to the following criteria. Note that if the rate of change in viscosity is less than the initial viscosity ±10%, the ink is at a level suitable for practical use. (Evaluation criteria) ○: Viscosity change rate: ±2.5% or less △: Viscosity change rate: ±2.6% or more to ±10% or less ×: Viscosity change rate: ±11% or more

[0093] <Evaluation of image density> The image sample was measured using an image density colorimeter (X-Rite Exact). The ink of Example 1 was used as the white ink printed prior to printing the black, cyan, magenta, and yellow inks.

[0094] [Table 2-1]

[0095] [Table 2-2]

[0096] [Table 2-3]

[0097] [Table 3]

[0098] The aspects of the present invention are as follows, for example. (1) An ink for use in an inkjet printing device having an inkjet head equipped with a nozzle plate having a nozzle for ejecting ink and an ink-repellent layer containing a silicone resin or a fluororesin on the surface of the ink ejection surface side, the ink contains a colorant, an organic solvent, resin particles, and water; the resin particles include urethane resin particles, The resin particles have a volume-based cumulative 90% particle diameter (D90) of 50 nm or less, the number of particles of 0.5 μm or more of the resin particles is 50,000 particles / 5 μL or less, and the resin particles have a FT-IR peak at 1700 cm -1 More than 1750cm -1 An ink characterized in that the maximum absorbance in the following region is 0.10 or more and 0.40 or less. (2) The ink according to (1) above, wherein the content of the urethane resin particles is 1% by mass or more and 20% by mass or less. (3) The ink according to (1) or (2) above, wherein the surface tension of the ink is 30.0 mN / m or more and 40.0 mN / m or less. (4) The ink according to any one of (1) to (3) above, which contains a compound represented by the following general formula (1) or (2): [ka] (In general formula (1), m represents an integer of 1 to 4.) [ka] (In general formula (2), R 1 represents an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 8 carbon atoms, or an allyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200. (5) The ink according to any one of (1) to (4) above, further comprising any one of a silicon-based compound represented by the following general formula (3), an acetylene-based compound represented by the following general formula (4), and a polyoxyethylene alkyl ether-based compound represented by the following general formula (5). [ka] (In the general formula (3), a represents an integer of 1 to 8, and R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) [ka] (In the general formula (4), R1 to R4 represent an alkyl group, m+n represents an integer of 1 to 20, and Y represents an acetylene group.) [ka] (In the general formula (5), n represents an integer of 3 to 11.) (6) The ink according to any one of (1) to (5) above, further comprising silicone oil. (7) The ink according to any one of (1) to (6) above, wherein the mass ratio (R / P) of the amount of coloring material (P) to the total amount of resin (R) in the ink is 0.10 or more and 2.00 or less. (8) An ink set including a pretreatment liquid, a black ink, a cyan ink, a magenta ink, a yellow ink, and a white ink, for use in an inkjet printing device having an inkjet head equipped with a nozzle plate having a nozzle for ejecting ink and further having an ink-repellent layer containing a silicone resin or a fluororesin on the surface of the ink ejection surface side, the pretreatment liquid contains a flocculant, an organic solvent, resin particles, and water; the ink contains a colorant, an organic solvent, resin particles, and water; The resin particles in the ink contain urethane resin particles, and the volume-based cumulative 90% particle diameter (D90) of the resin particles in the ink is 50 nm or less, the number of particles of 0.5 μm or more of the resin particles is 50,000 particles / 5 μL or less, and the resin particles have a FT-IR spectrum of 1700 cm -1 More than 1750cm -1 An ink set characterized in that the maximum absorbance in the following region is 0.10 or more and 0.40 or less. (9) The ink set according to (8) above, wherein the flocculant in the pretreatment liquid is a calcium metal salt. (10) An inkjet printing device having an inkjet head with a nozzle for ejecting ink and a nozzle plate having an ink-repellent layer containing a silicone resin or a fluororesin on the surface of the ink ejection surface side, and a pretreatment liquid and ink ejected from the inkjet head, An inkjet printing apparatus, wherein the pretreatment liquid and the ink are the pretreatment liquid and the ink in the ink set according to (8) or (9) above. (11) An inkjet printing method comprising: a pretreatment liquid applying step of applying a pretreatment liquid to a recording medium from an inkjet head having a nozzle for ejecting ink and further including a nozzle plate having an ink-repellent layer containing a silicone resin or a fluororesin on a surface on the ink ejection surface side; and an ink applying step of applying ink from the inkjet head to an area of the recording medium to which the pretreatment liquid has been applied, An inkjet printing method, wherein the pretreatment liquid and the ink are the pretreatment liquid and the ink in the ink set according to (8) or (9) above. [Explanation of symbols]

[0099] 10, 32 nozzle plate 11 nozzles 11a Edge 20 Nozzle base material 21 holes, nozzle 21a Cylindrical part 21b frustum-shaped part 30 Middle Class 31, 40 Ink-repellent layer 34 Dispenser 35 Needle 41 Slope area 41a Slope 101 Device body 102 Paper tray 103 Paper output tray 104 Ink cartridge loading section 105 Operation section 111 Upper cover 112 Front of front cover 115 Front cover 131 Guide rod 132 Stay 133 Carriage 134 Recording head 135 Subtank 141 Paper stacking section 142 Paper 143 Paper feed roller 144 Separation Pad 145 Guide 151 Conveyor belt 152 Counter Roller 153 Transport guide 154 Retaining member 155 Tip pressure roller 156 Charging roller 157 Transport roller 158 Tension Roller 161 Guide member 171 Separation claw 172 Paper ejection roller 173 Paper ejection roller 181 Duplex paper feed unit 182 Manual paper feed unit [Prior art documents] [Patent documents]

[0100] [Patent Document 1] Patent No. 7274908 [Patent Document 2] Patent Publication No. 2021-095552 [Patent Document 3] Patent No. 5958788

Claims

1. An ink for use in an inkjet printing device having an inkjet head equipped with a nozzle plate having a nozzle for ejecting ink and an ink-repellent layer containing a silicone resin or a fluororesin on the surface of the ink ejection surface side, the ink contains a colorant, an organic solvent, resin particles, and water; the resin particles include urethane resin particles, The resin particles have a volume-based cumulative 90% particle diameter (D90) of 50 nm or less, the number of particles of 0.5 μm or more of the resin particles is 50,000 particles / 5 μL or less, and the resin particles have a FT-IR of 1700 cm －１ 1750cm or more －１ The maximum absorbance in the following region is 0.10 or more and 0.40 or less: An ink characterized by:

2. The ink according to claim 1 , wherein the content of the urethane resin particles is 1% by mass or more and 20% by mass or less.

3. 3. The ink according to claim 1, wherein the surface tension of the ink is 30.0 mN / m or more and 40.0 mN / m or less.

4. The ink according to claim 1 or 2, comprising a compound represented by the following general formula (1) or the following general formula (2): 【Chemical 1】 (In general formula (1), m represents an integer of 1 to 4.) 【Chemistry 2】 (In general formula (2), R １ represents an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 8 carbon atoms, or an allyl group, 1 represents an integer of 0 to 7, and n represents an integer of 20 to 200.

5. The ink according to claim 1 or 2, further comprising any one of a silicon-based compound represented by the following general formula (3), an acetylene-based compound represented by the following general formula (4), and a polyoxyethylene alkyl ether-based compound represented by the following general formula (5): 【Chemistry 3】 (In general formula (3), a represents an integer of 1 to 8, and R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) 【Chemistry 4】 (In general formula (4), R １ ~R ４ represents an alkyl group, m+n represents an integer of 1 to 20, and Y represents an acetylene group. 【Chemistry 5】 (In general formula (5), n represents an integer of 3 to 11.)

6. The ink according to claim 1 or 2, further comprising a silicone oil.

7. 3. The ink according to claim 1, wherein the mass ratio (R / P) of the amount of coloring material (P) to the total amount of resin (R) in the ink is 0.10 or more and 2.00 or less.

8. An ink set including a pretreatment liquid, a black ink, a cyan ink, a magenta ink, a yellow ink, and a white ink, for use in an inkjet printing apparatus having an inkjet head equipped with a nozzle plate having nozzles for ejecting ink and further having an ink-repellent layer containing a silicone resin or a fluororesin on a surface on the ink ejection surface side, the pretreatment liquid contains a flocculant, an organic solvent, resin particles, and water; the ink contains a colorant, an organic solvent, resin particles, and water; The resin particles in the ink include urethane resin particles, and the volume-based cumulative 90% particle diameter (D90) of the resin particles in the ink is 50 nm or less, the number of particles of 0.5 μm or more among the resin particles is 50,000 particles / 5 μL or less, and the FT-IR of the resin particles is 1700 cm －１ 1750cm or more －１ An ink set characterized in that the maximum absorbance in the following region is 0.10 or more and 0.40 or less.

9. 9. The ink set according to claim 8, wherein the aggregating agent in the pretreatment liquid is a calcium metal salt.

10. An inkjet printing apparatus comprising: an inkjet head having nozzles for ejecting ink, the nozzle plate having an ink-repellent layer containing a silicone resin or a fluororesin on a surface of the ink ejection surface side; and a pretreatment liquid and ink ejected from the inkjet head, An inkjet printing apparatus, wherein the pretreatment liquid and the ink are the pretreatment liquid and the ink in the ink set according to claim 8 or 9.

11. An inkjet printing method comprising: a pretreatment liquid applying step of applying a pretreatment liquid to a recording medium from an inkjet head having nozzles for ejecting ink and further including a nozzle plate having an ink-repellent layer containing a silicone resin or a fluororesin on a surface on an ink ejection surface side; and an ink applying step of applying ink from the inkjet head to an area of the recording medium to which the pretreatment liquid has been applied, An inkjet printing method, wherein the pretreatment liquid and the ink are the pretreatment liquid and the ink in the ink set according to claim 8 or 9.

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