Inkjet clear ink liquid for textile printing, ink set, image forming apparatus, and image forming method

Abstract

To provide an inkjet clear ink liquid for textile printing capable of suppressing the occurrence of poor ejection and poor friction fastness while thickening the inkjet clear ink liquid.SOLUTION: An inkjet clear ink liquid for textile printing, comprising 3-methyl-1, 3-butanediol, wherein a content of the 3-methyl-1, 3-butanediol is 18% by mass or less relative to the inkjet clear ink liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inkjet clear ink liquid for textile printing, an ink set, an image forming apparatus, and an image forming method. [Background technology]

[0002] In recent years, ink-jet printing, which forms an image on a fabric by an ink-jet method, has become widely used as a textile printing method because it allows dyeing in a short time and has high production efficiency.

[0003] For example, Patent Document 1 discloses an inkjet textile printing method in which a pretreatment liquid is applied to fabric by an inkjet system, and then an ink having a pigment is applied onto the pretreatment liquid by an inkjet system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-8466 Summary of the Invention [Problem to be solved by the invention]

[0005] The pretreatment liquid disclosed in Patent Document 1 is a clear ink liquid that does not contain coloring materials such as pigments. Because this type of clear ink liquid does not contain coloring materials such as pigment dispersions, it has low viscosity, and when ejected using an inkjet method, satellites occur, in which part of the droplets break off, resulting in ejection failure. The occurrence of satellites can cause the droplets to land in a misaligned position, resulting in poor image quality, or the generation of mist, resulting in ejection failure.

[0006] Low-viscosity inks generally require the use of high-viscosity solvents to thicken and adjust the viscosity. Because high-viscosity solvents have a high boiling point, they do not evaporate during drying and remain on the fabric. Residual solvent on the fabric results in insufficient film formation during drying, resulting in the formation of voids and reduced abrasion resistance. Furthermore, due to their high viscosity, evaporation of water from the ink makes them prone to thickening, making them impossible to eject. While using large amounts of low-viscosity solvents allows for slight viscosity adjustments, significant viscosity adjustments are impossible. Furthermore, the need to use large amounts of solvent increases the overall solvent content of the clear ink, which can affect ejection performance. Therefore, it is difficult to raise low-viscosity clear inks to the appropriate viscosity range using low-viscosity solvents.

[0007] An object of the present invention is to provide an inkjet clear ink liquid for textile printing that can increase the viscosity of the inkjet clear ink liquid while suppressing the occurrence of ejection defects and poor rub fastness. Another object of the present invention is to provide an ink set including the inkjet clear ink liquid. Another object of the present invention is to provide an image forming apparatus that includes the inkjet clear ink liquid. Another object of the present invention is to provide an image forming method that uses the inkjet clear ink liquid. [Means for solving the problem]

[0008] The present invention relates to the following inkjet clear ink liquid for textile printing, an ink set, an image forming apparatus, and an image forming method.

[0009] [1] An inkjet clear ink liquid for textile printing, comprising 3-methyl-1,3-butanediol, the content of the 3-methyl-1,3-butanediol being 18% by mass or less relative to the inkjet clear ink liquid. [2] The inkjet clear ink liquid according to [1], which contains an organic solvent, and the content of the organic solvent is 40% by mass or less relative to the inkjet clear ink liquid. [3] The inkjet clear ink liquid according to [1] or [2], which has a viscosity at 25°C of 4.5 cp or more and 9 cp or less. [4] The inkjet clear ink liquid according to any one of [1] to [3], which contains a flocculating agent or a resin. [5] The inkjet clear ink liquid according to [4], wherein the resin is an anionic resin or a cationic resin. [6] The inkjet clear ink liquid according to any one of [1] to [5], wherein the total solid content is from 0% to 8% by mass based on the inkjet clear ink liquid. [7] An ink set comprising the inkjet clear ink liquid according to any one of [1] to [6] and a colored ink. [8] The ink set according to [7], wherein the color ink contains a pigment, a binder resin, water, and a water-soluble organic solvent. [9] An image forming apparatus comprising the ink set according to [7].

[10] An image forming method comprising applying the inkjet clear ink liquid according to any one of [1] to [6] onto a fabric by an inkjet system.

[11] The image forming method according to

[10] , comprising the steps of: applying an inkjet clear ink liquid containing a flocculant onto a fabric; applying a colored ink onto the inkjet clear ink liquid applied onto the fabric; and applying an inkjet clear ink liquid not containing a flocculant onto the colored ink applied onto the fabric. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an inkjet clear ink liquid for textile printing that can suppress the occurrence of ejection defects and poor rub fastness while increasing the viscosity of the inkjet clear ink liquid. Furthermore, according to the present invention, it is possible to provide an ink set including the inkjet clear ink liquid. Furthermore, according to the present invention, it is possible to provide an image forming apparatus including the inkjet clear ink liquid. Furthermore, according to the present invention, it is possible to provide an image forming method that uses the inkjet clear ink liquid. can be done. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an image forming apparatus according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes an inkjet clear ink liquid according to a preferred embodiment of the present invention.

[0013] 1. Inkjet clear ink Inkjet clear ink liquid does not contain colorants or components associated with colorants (e.g., pigments and pigment dispersions for dispersing pigments in the liquid), and has low viscosity. Therefore, when inkjet clear ink liquid is applied to fabric using an inkjet method, satellite droplets are formed, resulting in ejection defects. We found that adding 3-methyl-1,3-butanediol to such inkjet clear ink liquid suppresses ejection defects. On the other hand, if the inkjet clear ink contains too much 3-methyl-1,3-butanediol (isoprene glycol), ejection failure occurs and the abrasion resistance of the resulting image decreases. Therefore, by adding 3-methyl-1,3-butanediol to the inkjet clear ink at a content of 18% by mass or less, ejection failure can be suppressed and a decrease in the abrasion resistance of the resulting image can be suppressed.

[0014] In inkjet textile printing, a pretreatment liquid is generally applied to a fabric first, then a color ink containing a coloring material is applied onto the pretreatment liquid, and finally, an overcoat liquid, which is a posttreatment liquid, is applied onto the color ink containing the coloring material. The pretreatment liquid promotes aggregation of the color ink and promotes fixation of the color ink to the fabric. On the other hand, the overcoat liquid, which is a posttreatment liquid, serves to protect the color ink.

[0015] The inkjet clear ink liquid for textile printing may be used as the above-mentioned pretreatment liquid or as an overcoat liquid. The inkjet clear ink liquid may be substantially clear ink, containing substantially no coloring material (pigment, dye, etc.). "Substantially no" means, for example, that the coloring material is 0.1% by mass or less relative to the inkjet clear ink liquid. The inkjet clear ink liquid preferably contains no coloring material, and the coloring material is 0% by mass relative to the inkjet clear ink liquid.

[0016] The total solid content of the inkjet clear ink liquid is, for example, 0% by mass or more, or 1% by mass or more. The upper limit of this value is, for example, 7% by mass or less, or 8% by mass or less. The total solid content is the mass of solids remaining after the solvent of the inkjet clear ink liquid has been evaporated.

[0017] Hereinafter, the components of each of the inkjet clear ink liquid for textile printing according to one embodiment of the present invention will be described separately for the cases where it is used as a pre-treatment liquid and a post-treatment liquid (overcoat liquid).

[0018] 1-1. Pretreatment solution The inkjet clear ink liquid used as the pretreatment liquid contains a solvent, a flocculating agent, a surfactant, and an antiseptic (fungicide), each of which will be explained below.

[0019] (solvent) The solvent is preferably a water-soluble organic solvent. The water-soluble organic solvent is preferably selected appropriately from the viewpoint of improving ejection stability by inkjet. It is believed that by selecting the water-soluble organic solvent appropriately, the viscosity of the inkjet clear ink liquid can be adjusted appropriately, thereby improving the ejection stability.

[0020] The inkjet clear ink liquid according to this embodiment contains 3-methyl-1,3-butanediol as a water-soluble organic solvent. 3-methyl-1,3-butanediol has a thickening function and is thought to suppress the generation of satellites. From the viewpoint of suppressing a decrease in rub fastness, the content of 3-methyl-1,3-butanediol is preferably 18% by mass or less, and more preferably 15% by mass or less, relative to the inkjet clear ink liquid. On the other hand, from the viewpoint of improving ejection stability, the lower limit of the content of 3-methyl-1,3-butanediol is, for example, preferably 3% by mass or more, and more preferably 5% by mass or more, relative to the inkjet clear ink liquid.

[0021] The water-soluble organic solvent other than 3-methyl-1,3-butanediol is not particularly limited as long as it is compatible with water. Examples of such water-soluble organic solvents include polyhydric alcohols (e.g., dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol, and trihydric or higher alcohols such as glycerin, trimethylolpropane, and hexanetriol); polyhydric alcohol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, and propylene glycol); glycol monomethyl ether, propylene glycol monoethyl ether); monohydric alcohols (e.g., methanol, ethanol, propanol, pentanol, hexanol, cyclohexanol, benzyl alcohol); amines (e.g., ethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine); amides (e.g., formamide, N,N-dimethylformamide, N,N-dimethylacetamide); heterocycles (e.g., 2-pyrrolidone, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidine), sulfoxides (e.g., dimethyl sulfoxide); and sulfones (e.g., sulfolane).

[0022] Furthermore, from the viewpoint of further improving ejection stability by inkjet printing, the water-soluble organic solvent preferably contains a water-soluble organic solvent having a boiling point of 180° C. or higher, preferably 190° C. or higher, and more preferably 200° C. or higher. Examples of water-soluble organic solvents having a boiling point of 180° C. or higher include dihydric alcohols such as ethylene glycol (boiling point 197° C.), 1,3-butanediol (boiling point 208° C.), 1,6-hexanediol (boiling point 223° C.), and polypropylene glycol; and trihydric or higher alcohols such as glycerin (boiling point 290° C.) and trimethylolpropane (boiling point 295° C.).

[0023] The content of the water-soluble organic solvent is preferably, for example, 10% by mass or more and 65% by mass or less, and more preferably 20% by mass or more and 40% by mass or less, relative to the inkjet clear ink liquid.

[0024] The water content is 30% by mass or more and 85% by mass or less, and preferably 50% by mass or more and 75% by mass or less, based on the inkjet clear ink liquid.

[0025] (flocculant) The type of aggregating agent may be any agent that aggregates pigments contained in the colored ink, and may be one that utilizes a change in pH or one that utilizes an electrical effect.

[0026] Examples of flocculants that cause flocculation by changing the pH include organic acids, such as carboxylic acids having 6 or less carbon atoms, saturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, and hexanoic acid, and hydroxy acids such as lactic acid, malic acid, and citric acid.

[0027] The flocculant that causes aggregation by electrical action includes a polyvalent metal salt, or a compound having a cationic group or an anionic group. For example, when the pigment dispersant contained in the ink is anionic, the flocculant preferably contains a polyvalent metal salt or a compound having a cationic group.

[0028] Polyvalent metal salts can be water-soluble compounds having a divalent or higher polyvalent metal ion and an associated anion. Examples of polyvalent metal ions include Ca 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Zn 2+ , Ba 2+ Divalent metal ions such as Al 3+ , Fe 3+ , Cr 3+ Examples of anions include trivalent metal ions such as Cl - , I - , Br - , SO4 2- , ClO3 - , NO3 - , and HCOO - , CH3COO - Among these, calcium salts and magnesium salts are preferred, and calcium nitrate and calcium chloride are more preferred.

[0029] Examples of the cationic group in the compound having a cationic group include a secondary amino group, a tertiary amino group, and a quaternary ammonium salt group. Examples of the compound having a cationic group include the above-mentioned cationic urethane compounds. In addition, cationic resins such as cationic urethane resins, cationic olefin resins, and cationic allylamine resins may also be used.

[0030] Examples of commercially available cationic resins include PAS-H-1L manufactured by Nittobo Medical Co., Ltd., Catiomaster (registered trademark) PD-7, PD-30, and PE-30 manufactured by Yokkaichi Synthetic Co., Ltd., and Unisense KHE manufactured by Senka Corporation.

[0031] The content of the flocculant is preferably 0.1% by mass to 10% by mass, and more preferably 1% by mass to 3% by mass, relative to the total mass of the pretreatment liquid.

[0032] (surfactant) The surfactant can reduce the surface tension of the pretreatment liquid and increase the wettability of the pretreatment liquid to the fabric. The type of surfactant is not particularly limited, and may be, for example, an acetylene-based surfactant, an acetylene glycol-based surfactant, a silicone-based surfactant, a fluorine-based surfactant, or the like. An example of a commercially available surfactant is Olfine E1010 manufactured by Nissin Chemical Industry Co., Ltd.

[0033] (preservatives) Examples of the preservative or antifungal agent include aromatic halogen compounds (eg, Preventol CMK), methylene dithiocyanate, halogen-containing nitrogen-sulfur compounds, 1,2-benzisothiazolin-3-one (eg, PROXEL GXL), and the like.

[0034] (others) The pretreatment liquid may further contain a pH adjuster as necessary. The pretreatment liquid is applied to the fabric by an inkjet method. The applied pretreatment liquid may be heated and dried using hot air, a hot plate, or a heat roller.

[0035] 1-2. Post-processing liquid (overcoat liquid) The inkjet clear ink liquid used as the post-treatment liquid (overcoat liquid) contains a solvent, a resin, a surfactant, and a preservative (fungicide). The solvent, surfactant, and preservative (fungicide) may be the same as those contained in the inkjet clear ink liquid used as the above-mentioned pre-treatment liquid. The resin contained in the inkjet clear ink liquid used as the overcoat liquid will be described below.

[0036] Examples of resins contained in the inkjet clear ink liquid used as the overcoat liquid include water-dispersible silicone resins and (meth)acrylic resins, each of which will be explained below.

[0037] (Water-acidic silicone resin) A water-dispersible silicone resin is a silicone resin that exists in a dispersed state as resin particles in an aqueous medium. The overcoat liquid according to this embodiment is an aqueous overcoat liquid containing water and any water-soluble organic solvent. Therefore, the silicone resin is also contained as resin particles in the overcoat liquid. Whether the silicone resin exists as resin particles can be confirmed by determining whether a peak corresponding to the water-dispersible silicone resin is present when the dispersed particle size (Z average) of the overcoat liquid is measured using a particle size measuring device (e.g., Melvern's Zataizer Nano S90).

[0038] The silicone resin is a polymer containing structural units derived from polyorganosiloxane. The polymer may be a homopolymer consisting of structural units derived from polyorganosiloxane, or a copolymer containing structural units derived from polyorganosiloxane and structural units derived from other polymerizable monomers (including macromonomers) copolymerizable therewith.

[0039] The copolymer may be, for example, a graft copolymer in which structural units derived from polyorganosiloxane are graft polymerized with a polymerizable monomer such as a (meth)acrylic acid ester, or a copolymer in which the side chains or ends of a (meth)acrylic resin or the like are modified with a polyorganosiloxane. Among these, a graft copolymer in which a (meth)acrylic acid ester or the like is graft polymerized with a polymer containing structural units derived from polyorganosiloxane is preferred. Such a graft copolymer has a structure in which the polyorganosiloxane portion forms the trunk and the (meth)acrylic acid ester or the like forms the branches, making it more compatible with the binder resin contained in the colored ink, making it preferred. The form of copolymerization is not limited to graft copolymerization, and may be random copolymerization or block copolymerization.

[0040] The silicone resin may also have an ionic group. The ionic group of the silicone resin may be an ionic group that forms a pair with the ionic group of the fabric (or the ionic group of the flocculant attached to the fabric). For example, since flocculants usually have cationic groups, the silicone resin in the overcoat liquid may be an anionic silicone resin having an anionic group. Examples of the anionic group include a carboxyl group, a sulfonic acid group, and a phosphonic acid group.

[0041] The silicone resin preferably contains a structural unit derived from a polyorganosiloxane having a radical polymerizable group and a structural unit derived from another polymerizable monomer copolymerizable therewith.

[0042] Examples of polyorganosiloxanes having a radical polymerizable group include polyorganosiloxanes represented by the following formula (1). [ka]

[0043] In the above formula (1), R 1 , R 2 and R 3 are each independently a hydrocarbon group having 1 to 10 carbon atoms. Y is a radically polymerizable group selected from the group consisting of a vinyl group, an allyl group, and a γ-(meth)acryloxypropyl group. X 1 and X 2 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or SiR 4 R 5 R 6 (R 4 , R 5 each independently represents a hydrocarbon group having 1 to 10 carbon atoms, and R 6 represents a hydrocarbon group having 1 to 10 carbon atoms or a radical polymerizable group selected from the group consisting of a vinyl group, an allyl group, and a γ-(meth)acryloxypropyl group). m is an integer of 1 to 10000. n is an integer of 1 or greater. The siloxane chain may be branched.

[0044] Examples of other polymerizable monomers include (meth)acrylic acid esters, vinyl acetate, urethane compounds having a radical polymerizable group, etc. In this specification, (meth)acrylic refers to acrylic, methacrylic, or both.

[0045] The (meth)acrylic acid ester is an alkyl ester, a hydroxyalkyl ester, or an alkoxyalkyl ester of (meth)acrylic acid. Examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-methoxyethyl (meth)acrylate. Among these, methyl methacrylate and 2-hydroxyethyl methacrylate are preferred.

[0046] Examples of urethane compounds having a radical polymerizable group include compounds obtained by reacting a polyol, a polyisocyanate, a silicone compound having two hydroxy groups, and an isocyanate compound having a (meth)acryloyl group. The polyol and polyisocyanate may be the same as those used to obtain a urethane resin as a binder resin for colored inks, which will be described later.

[0047] The content of structural units derived from polyorganosiloxane in the silicone resin is preferably 50% by mass or more, and more preferably 60% by mass or more and 95% by mass or less, relative to the total amount of structural units constituting the silicone resin. When the content of structural units derived from polyorganosiloxane is 50% by mass or more, the effect of reducing the coefficient of friction derived from polysiloxane is more easily achieved, and wet rub fastness can be further improved. When the content of structural units derived from polyorganosiloxane is 95% by mass or less, the affinity between other compounds and the binder resin in the ink layer is more likely to improve adhesion between the ink layer and the overcoat layer.

[0048] The silicone resin may further contain structural units derived from other polymerizable monomers than those mentioned above. Examples of other polymerizable monomers than those mentioned above include ethylenically unsaturated carboxylic acids such as (meth)acrylic acid, styrenes, etc. For example, from the viewpoint of exhibiting anionic properties, the silicone resin may further contain structural units derived from ethylenically unsaturated carboxylic acids such as (meth)acrylic acid.

[0049] The graft copolymerization can be carried out by a known method, for example, by emulsifying and dispersing the polyorganosiloxane represented by the above formula (1) and a copolymerizable compound such as a (meth)acrylic acid ester in water, and polymerizing them in the presence of a radical polymerization initiator.

[0050] Commercially available examples of silicone-(meth)acrylic copolymers include Chaline LC190, Chaline R-170, R170S, Chaline FE-230N, FE-502, and R-170BX (manufactured by Nissin Chemical Industry Co., Ltd.). Commercially available examples of silicone-urethane copolymers include Chaline RU-911 (manufactured by Nissin Chemical Industry Co., Ltd.). Commercially available examples of silicone-vinyl acetate copolymers include Chaline 1827 (manufactured by Nissin Chemical Industry Co., Ltd.).

[0051] The glass transition temperature (Tg) of the silicone resin is preferably moderately low from the viewpoint of more easily maintaining texture and further improving wet rub fastness. Specifically, the Tg of the silicone resin is preferably less than 20°C, and more preferably 0°C or lower. Thus, silicone resins with low Tg, particularly silicone resins with Tg less than 20°C, are soft and therefore less likely to impair texture. Furthermore, such silicone resins are easily conformable to the colored ink layer and are less likely to cause peeling of the overcoat layer at the interface between the colored ink layer and the overcoat layer, thereby further improving wet rub fastness. The lower limit of the Tg of the silicone resin is not particularly limited, but can be, for example, -60°C or higher from the viewpoint of improving wet rub fastness. The Tg of the silicone resin can be measured by differential scanning calorimetry in accordance with JIS K 7121 at a heating rate of 10°C / min.

[0052] It is preferable that the difference between the Tg(OC) of the silicone resin in the overcoat liquid and the Tg(IN) of the binder resin in the ink is small. The Tg of the resin in the overcoat liquid can be set to be the same as or higher than the Tg of the binder resin in the color ink. In this embodiment, by reducing the difference between the Tg(OC) of the silicone resin in the overcoat liquid and the Tg(IN) of the binder resin in the color ink (Tg(OC) - Tg(IN)), the binder resin in the color ink layer and the silicone resin in the overcoat layer become more compatible, making it less likely that an interface will form between the color ink layer and the overcoat layer. This reduces the likelihood of peeling at the interface between the ink layer and the overcoat layer when the surface of the image-formed product is rubbed, thereby more effectively improving wet rub fastness. Specifically, the Tg difference is more preferably 55°C or less, and even more preferably 40°C or less.

[0053] The Tg of the silicone resin can be adjusted by the type and amount of modification, for example, the content of structural units derived from other compounds such as (meth)acrylic acid esters. If the content of structural units derived from such other compounds is high, the Tg tends to be low.

[0054] The average particle size of the silicone resin in the aqueous dispersion used to prepare the overcoat liquid is not particularly limited, but is preferably 150 nm or more and 300 nm or less, for example, from the viewpoint of ejection stability by inkjet printing. The average particle size is the average value of primary particle sizes. The average particle size can be measured as the dispersed particle size (Z average) using, for example, a Zataizer Nano S90 manufactured by Melvern.

[0055] The acid value of the silicone resin is not particularly limited, but is preferably low from the viewpoint of further improving wet rub fastness and water resistance. Specifically, the acid value of the silicone resin is preferably lower than the acid value of the binder resin contained in the colored ink, more preferably 100 mgKOH / g or less, and even more preferably 0.1 mgKOH / g or more and 50 mgKOH / g or less. The acid value of the silicone resin can be measured according to JIS K 0070.

[0056] The content of the silicone resin is preferably 0.01% by mass or more and less than 15% by mass relative to the overcoat liquid. When the content is 0.01% by mass or more, the silicone resin tends to be unevenly distributed on the surface, which makes it easier to improve wet rub fastness. When the content is less than 15% by mass, deterioration in texture and deterioration in injection stability due to excessive silicone resin adhesion can be further suppressed. From the same viewpoint, the content is more preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.2% by mass or more and 8% by mass or less.

[0057] ((Meth)acrylic resin) A (meth)acrylic resin is a polymer containing structural units derived from a (meth)acrylic monomer.

[0058] The (meth)acrylic monomer is a monomer having a (meth)acryloyl group, and examples thereof include (meth)acrylic acid, (meth)acrylic acid alkyl esters, (meth)acrylamides, etc. Among these, (meth)acrylic acid alkyl esters are preferred.

[0059] That is, the (meth)acrylic resin contains a structural unit (a) derived from a (meth)acrylic acid alkyl ester, and from the viewpoint of improving water dispersibility and coagulation properties, it is preferable that the (meth)acrylic resin further contains a structural unit (b) derived from an unsaturated compound having an anionic group.

[0060] The structural unit (a) is derived from a (meth)acrylic acid alkyl ester. From the viewpoint of lowering the Tg of the resin, the (meth)acrylic acid alkyl ester preferably contains an acrylic acid alkyl ester. The number of carbon atoms in the alkyl group of the acrylic acid alkyl ester is, for example, 1 to 20, preferably 4 to 12, and more preferably 4 to 8. Examples of the acrylic acid alkyl ester include butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, and 2-ethylhexyl acrylate, and butyl acrylate is preferred.

[0061] The (meth)acrylic acid alkyl ester may be used alone or in combination of two or more kinds, for example, an acrylic acid alkyl ester and a methacrylic acid alkyl ester may be used in combination.

[0062] The content of the structural unit (a) is not particularly limited, but is preferably 70 to 96% by mass relative to all structural units constituting the (meth)acrylic resin. When the content is 70% by mass or more, the Tg of the resin is likely to be lowered. When the content is 96% by mass or less, properties such as abrasion resistance are less likely to be impaired. From the same viewpoint, the content is more preferably 80 to 90% by mass relative to all structural units constituting the (meth)acrylic resin.

[0063] The structural unit (b) is derived from an unsaturated compound having an anionic group. Examples of unsaturated compounds having a carboxy group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and 2-acryloyloxyethyl succinic acid. Examples of unsaturated compounds having a sulfonic acid group include vinyl sulfonic acid, styrene sulfonic acid, and allyl sulfonic acid. Examples of unsaturated compounds having a phosphoric acid group include vinyl phosphonic acid and 2-((meth)acryloyloxy)ethyl phosphate. Among these, ethylenically unsaturated carboxylic acids are preferred.

[0064] The content of the structural unit (b) is not particularly limited, but is preferably 3 to 15% by mass relative to all structural units constituting the (meth)acrylic resin. When the content is 3% by mass or more, the dispersibility and coagulation of the water-dispersible resin in the ink are more likely to be improved. When the content is 15% by mass or less, the viscosity of the ink is less likely to increase, and the ejection stability is less likely to be impaired. From the same viewpoint, the content of the structural unit (b) is more preferably 3 to 10% by mass relative to all structural units constituting the (meth)acrylic resin.

[0065] The (meth)acrylic resin may further contain a structural unit (c) derived from a monomer other than those mentioned above. Examples of such other monomers include monofunctional monomers such as ethylenically unsaturated carboxylic acids (e.g., maleic acid, itaconic acid), styrenes (e.g., styrene, α-methylstyrene, vinyltoluene), saturated vinyl fatty acids (e.g., vinyl acetate, vinyl propionate), vinyl compounds (e.g., 1,4-divinyloxybutane, divinylbenzene, etc.), allyl compounds (e.g., diallyl phthalate, triallyl cyanurate, etc.), and acrylamide; and difunctional or higher functional monomers such as polyfunctional (meth)acrylates (e.g., diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, propylene glycol di(meth)acrylate, N,N'-methylenebis(acrylamide), etc.), and polyfunctional acrylamide.

[0066] Examples of commercially available (meth)acrylic resins include EMN-325 (Acrylate, manufactured by Nippon Shokubai Co., Ltd., acrylic elastomer, Tg: -50°C) and EMN-326 (Acrylate, manufactured by Nippon Shokubai Co., Ltd., acrylic elastomer, Tg: -50°C).

[0067] 1-3.Physical properties The viscosity of the inkjet clear ink liquid used as a pretreatment liquid or an overcoat liquid at 25°C is not particularly limited, but from the viewpoint of improving ejection stability, it is preferably 4.5 cp or more and 9 cp or less. The viscosity of the inkjet clear ink liquid can be measured using a TPE-100L viscometer (manufactured by Toki Sangyo Co., Ltd.) under conditions of 25°C, 50 rpm, and 60 s. The viscosity of the inkjet clear ink liquid can be adjusted by the composition of the above-mentioned solvent and resin (for example, the content of polyhydric alcohols).

[0068] The static surface tension of the inkjet clear ink liquid at 25°C is not particularly limited, but when the ink is applied by inkjet, for example, from the viewpoint of further enhancing the wettability to fabric, the static surface tension is preferably 20 mN / m or more and 50 mN / m or less, and more preferably 30 mN / m or more and 50 mN / m or less.

[0069] The static surface tension of the inkjet clear ink liquid can be measured by the Wilhelmy method at 25° C. Specifically, the static surface tension of the inkjet clear ink liquid can be measured using a DY-300 manufactured by Kyowa Interface Science Co., Ltd. in accordance with JIS K2241.

[0070] 2. Ink set An ink set according to one embodiment of the present invention comprises the above-described inkjet clear ink liquid and colored inks. The colored inks will be described below.

[0071] [Colored ink] The color ink contains a pigment, a binder resin, and water. The viscosity of the color ink at 25°C is not particularly limited as long as it provides good ejection properties using an inkjet method, but is preferably 3 mPa·s or more and 20 mPa·s or less, and more preferably 4 mPa·s or more and 12 mPa·s or less. The viscosity of the color ink can be measured at 25°C using an E-type viscometer. The pigment, binder resin, and water contained in the color ink will be described below.

[0072] (pigment) The pigment is not particularly limited, but may be, for example, an organic pigment or an inorganic pigment having the following numbers listed in the Color Index:

[0073] Examples of orange pigments include CI Pigment Orange 31 and 43.

[0074] Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, and Pigment Orange 13, 16, 20, and 36.

[0075] Examples of blue or cyan pigments include Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36, 60.

[0076] Examples of green or yellow pigments include Pigment Green 7, 26, 36, and 50. Examples of yellow pigments include Pigment Yellow 1, 3, 12, 13, 14, 15, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 128, 137, 138, 139, 151, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, and 213.

[0077] Examples of black pigments include Pigment Black 7, 28, and 26.

[0078] Examples of white pigments include titanium dioxide and the like.

[0079] From the viewpoint of improving dispersibility in the ink, the pigment is preferably further dispersed with a pigment dispersant, which will be described later.

[0080] The pigment may also be a self-dispersing pigment. A self-dispersing pigment is a pigment particle whose surface is modified with a group having a hydrophilic group, and has pigment particles and hydrophilic groups bonded to the surface of the pigment particles.

[0081] Examples of hydrophilic groups include carboxyl groups, sulfonic acid groups, and phosphorus-containing groups, and examples of phosphorus-containing groups include phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, phosphite groups, and phosphate groups.

[0082] Examples of commercially available self-dispersing pigments include Cabot Corporation's Cab-0-Jet (registered trademark) 200K, 250C, 260M, and 270V (sulfonic acid group-containing self-dispersing pigments), Cab-0-Jet (registered trademark) 300K (carboxylic acid group-containing self-dispersing pigments), and Cab-0-Jet (registered trademark) 400K, 450C, 465M, 470V, and 480V (phosphate group-containing self-dispersing pigments).

[0083] The pigment content is not particularly limited, but from the viewpoint of easily adjusting the viscosity of the color ink within the above range and enabling the formation of high-density images, it is preferably 0.3% by mass to 10% by mass, and more preferably 0.5% by mass to 6% by mass, of the ink. If the pigment content is equal to or greater than the lower limit, the color of the image tends to be more vivid. If the pigment content is equal to or less than the upper limit, the viscosity of the color ink does not become too high, and ejection stability is less likely to be impaired.

[0084] (binder resin) The binder resin can function to fix the pigment to the fabric. From the viewpoint of improving water resistance, the binder resin is preferably a water-dispersible resin. The water-dispersible resin is dispersed as resin particles in the color ink containing an aqueous medium.

[0085] Like the silicone resin, the water-dispersible resin may have an ionic group that forms a pair with the ionic group of the fabric (or the ionic group of the flocculant attached to the fabric), or may have an anionic group. The acid value of the water-dispersible resin is not particularly limited, but is preferably 15 mgKOH / g or more and 100 mgKOH / g or less, and more preferably 20 mgKOH / g or more and 80 mgKOH / g or less. The acid value of the water-dispersible resin may be the same as or higher than the acid value of the silicone resin contained in the inkjet clear ink liquid. The acid value of the water-dispersible resin can be measured according to JIS K 0070.

[0086] The acid value of the water-dispersible resin can be adjusted, for example, by the content of the structural unit (b) of the (meth)acrylic resin described below. Specifically, the acid value increases as the content of the structural unit (b) derived from an unsaturated compound having an acidic group increases.

[0087] The average particle size of the water-dispersible resin in the aqueous dispersion used to prepare the colored ink can be, for example, 100 nm or less. The average particle size can be measured in the same manner as above.

[0088] The weight-average molecular weight of the water-dispersible resin is not particularly limited, but from the viewpoint of improving wet rub fastness, it is preferable that it is high, for example, from 10,000 to 1,000,000. On the other hand, from the viewpoint of making it easier to improve the texture, it is preferable that the weight-average molecular weight of the water-dispersible resin is low, preferably not more than 10,000. The weight-average molecular weight of the water-dispersible resin can be measured by the same method as above.

[0089] The content of the binder resin is not particularly limited, but is preferably 1% by mass or more and 20% by mass or less relative to the ink. When the content of the binder resin is 1% by mass or more, the fixation of the ink to the fabric is more easily improved. When the content of the binder resin is 20% by mass or less, the texture is less likely to be impaired. From the same perspective, the content of the binder resin is more preferably 5% by mass or more and 15% by mass or less relative to the ink.

[0090] The Tg of the water-dispersible resin (binder resin) is not particularly limited, but is preferably low. This is because the fabric is less likely to become hard even after image formation, making it easier to maintain its texture. Specifically, the Tg of the water-dispersible resin is preferably 50°C or lower, more preferably 0°C or lower, and even more preferably -35°C or lower. The lower limit of the Tg of the water-dispersible resin is not particularly limited, but can be, for example, -70°C or higher. The Tg of the water-dispersible resin can be measured in the same manner as the Tg of the silicone resin.

[0091] The Tg of a water-dispersible resin can be adjusted by the type of water-dispersible resin and the monomer composition. For example, in the case of a (meth)acrylic resin, increasing the content of the structural unit (a) derived from alkyl acrylate tends to lower the Tg. In the case of a urethane resin, increasing the content of the soft unit tends to lower the Tg.

[0092] The type of water-dispersible resin is not particularly limited as long as its Tg satisfies the above range. Examples of water-dispersible resins include (meth)acrylic resins, polyurethane resins, polyester resins, etc. Among them, (meth)acrylic resins and polyurethane resins are preferred from the viewpoint of having good flexibility and being able to more easily maintain the texture of the fabric. Hereinafter, (meth)acrylic resins and polyurethane resins will be described.

[0093] (Meth)acrylic resin A (meth)acrylic resin is a polymer containing structural units derived from a (meth)acrylic monomer.

[0094] The (meth)acrylic monomer is a monomer having a (meth)acryloyl group, and examples thereof include (meth)acrylic acid, (meth)acrylic acid alkyl esters, (meth)acrylamides, etc. Among these, (meth)acrylic acid alkyl esters are preferred.

[0095] That is, the (meth)acrylic resin contains a structural unit (a) derived from a (meth)acrylic acid alkyl ester, and from the viewpoint of improving water dispersibility and coagulation properties, it is preferable that the (meth)acrylic resin further contains a structural unit (b) derived from an unsaturated compound having an anionic group.

[0096] The structural unit (a) is derived from a (meth)acrylic acid alkyl ester. From the viewpoint of lowering the Tg of the resin, the (meth)acrylic acid alkyl ester preferably contains an acrylic acid alkyl ester. The number of carbon atoms in the alkyl group of the acrylic acid alkyl ester is, for example, 1 to 20, preferably 4 to 12, and more preferably 4 to 8. Examples of the acrylic acid alkyl ester include butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, and 2-ethylhexyl acrylate, and butyl acrylate is preferred.

[0097] The (meth)acrylic acid alkyl ester may be used alone or in combination of two or more kinds, for example, an acrylic acid alkyl ester and a methacrylic acid alkyl ester may be used in combination.

[0098] The content of the structural unit (a) is not particularly limited, but is preferably 70 to 96% by mass relative to all structural units constituting the (meth)acrylic resin. When the content is 70% by mass or more, the Tg of the resin is likely to be lowered. When the content is 96% by mass or less, properties such as abrasion resistance are less likely to be impaired. From the same viewpoint, the content is more preferably 80 to 90% by mass relative to all structural units constituting the (meth)acrylic resin.

[0099] The structural unit (b) is derived from an unsaturated compound having an anionic group. Examples of unsaturated compounds having a carboxy group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and 2-acryloyloxyethyl succinic acid. Examples of unsaturated compounds having a sulfonic acid group include vinyl sulfonic acid, styrene sulfonic acid, and allyl sulfonic acid. Examples of unsaturated compounds having a phosphoric acid group include vinyl phosphonic acid and 2-((meth)acryloyloxy)ethyl phosphate. Among these, ethylenically unsaturated carboxylic acids are preferred.

[0100] The content of the structural unit (b) is not particularly limited, but is preferably 3 to 15% by mass relative to all structural units constituting the (meth)acrylic resin. When the content is 3% by mass or more, the dispersibility and coagulation of the water-dispersible resin in the ink are more likely to be improved. When the content is 15% by mass or less, the viscosity of the ink is less likely to increase, and the ejection stability is less likely to be impaired. From the same viewpoint, the content of the structural unit (b) is more preferably 3 to 10% by mass relative to all structural units constituting the (meth)acrylic resin.

[0101] The (meth)acrylic resin may further contain a structural unit (c) derived from a monomer other than those mentioned above. Examples of such other monomers include monofunctional monomers such as ethylenically unsaturated carboxylic acids (e.g., maleic acid, itaconic acid), styrenes (e.g., styrene, α-methylstyrene, vinyltoluene), saturated vinyl fatty acids (e.g., vinyl acetate, vinyl propionate), vinyl compounds (e.g., 1,4-divinyloxybutane, divinylbenzene, etc.), allyl compounds (e.g., diallyl phthalate, triallyl cyanurate, etc.), and acrylamide; and difunctional or higher functional monomers such as polyfunctional (meth)acrylates (e.g., diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, propylene glycol di(meth)acrylate, N,N'-methylenebis(acrylamide), etc.), and polyfunctional acrylamide.

[0102] Examples of commercially available (meth)acrylic resins include EMN-325 (Acrylate, manufactured by Nippon Shokubai Co., Ltd., acrylic elastomer, Tg: -50°C) and EMN-326 (Acrylate, manufactured by Nippon Shokubai Co., Ltd., acrylic elastomer, Tg: -50°C).

[0103] <Urethane resin> The urethane resin is a thermoplastic urethane resin. The thermoplastic urethane resin may be, for example, a reaction product of a low-molecular-weight diol as a chain extender, a polyisocyanate, and a polyol. The urethane resin is preferably a self-emulsifying type. The self-emulsifying urethane resin may be, for example, a reaction product of a low-molecular-weight diol as a chain extender, a polyisocyanate having an anionic group, and a polyol.

[0104] The low molecular weight diol is a difunctional aliphatic oligomer of glycol. Typical difunctional aliphatic oligomers of glycol include, for example, ethylene glycol, propylene glycol, 1,4 butanediol, and 1,6 hexanediol.

[0105] The polyisocyanate is preferably a diisocyanate, examples of which include aromatic diisocyanates such as diphenylmethane diisocyanate, for example, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate; Examples include aliphatic diisocyanates such as 4,4'-dicyclohexylmethane diisocyanate and 2,4'-dicyclohexylmethane diisocyanate.

[0106] The polyol may be a polyester polyol or a polyether polyol. Examples of polyester polyols include the reaction product of a polycarboxylic acid and a polyol. Examples of polycarboxylic acids include malonic acid, citric acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, terephthalic acid, and phthalic acid. Examples of polyols to be reacted with the polycarboxylic acid include trimethylolpropane, trimethylolethane, 2-methyl glucoside, sorbitol, and low-molecular-weight polyols such as polyoxyethylene glycol, polyoxypropylene glycol, and block heteropolyoxyethylene-polyoxypropylene glycol.

[0107] Thermoplastic polyurethanes contain hard and soft segments in their molecules. The hard segments are primarily formed by the reaction of polyisocyanate with low molecular weight diols; the soft segments are primarily formed by the reaction of polyols.

[0108] The mass ratio of the hard segment to the soft segment in the polymer chain of the thermoplastic polyurethane is, for example, 75 / 25 to 15 / 85 (mass ratio), preferably 60 / 40 to 25 / 75 (mass ratio). From the viewpoint of lowering Tg, the mass ratio of the soft segment may be increased, for example, the mass ratio of the soft segment may be higher than that of the hard segment.

[0109] An example of a commercially available thermoplastic polyurethane product is Elastollan 1185A (manufactured by BASF, thermoplastic polyurethane elastomer, Tg: -41°C).

[0110] <water> The water content is, for example, 20% by mass or more and 70% by mass or less, and preferably 30% by mass or more and 60% by mass or less, based on the ink.

[0111] (Other ingredients) The color ink may further contain other components as necessary. Examples of other components include a water-soluble organic solvent, a pigment dispersant, a surfactant, a preservative, an antiseptic, a pH adjuster, etc. The surfactants, preservatives, antiseptics, and pH adjusters that may be contained in the color ink may be the same as those contained in the inkjet clear ink liquid.

[0112] <Water-soluble organic solvent> The water-soluble organic solvent may be the same as that used in the inkjet clear ink liquid, and the content of the water-soluble organic solvent is, for example, 20% by mass or more and 70% by mass or less, and preferably 30% by mass or more and 60% by mass or less, based on the ink.

[0113] <Pigment dispersant> The pigment dispersant is present in the colored ink so as to surround the surface of the pigment particle or is adsorbed to the surface of the pigment particle to form a pigment dispersion, thereby dispersing the pigment well. The pigment dispersant is preferably a polymer dispersant, more preferably an anionic polymer dispersant.

[0114] The anionic polymer dispersant is a polymer dispersant having a hydrophilic group such as a carboxylic acid group, a phosphorus-containing group, or a sulfonic acid group, and is preferably a polymer dispersant having a carboxylic acid group.

[0115] The polymer dispersant having a carboxylic acid group may be a polycarboxylic acid or a salt thereof. Examples of polycarboxylic acids include (co)polymers of monomers selected from acrylic acid or its derivatives, maleic acid or its derivatives, itaconic acid or its derivatives, and fumaric acid or its derivatives, and salts thereof. Examples of other monomers that may form the copolymer include styrene and vinylnaphthalene.

[0116] From the viewpoint of sufficiently dispersing pigment particles, the anionic group equivalent of the anionic polymer dispersant is preferably, for example, 1.1 meq / g or more and 3.8 meq / g or less. When the anionic group equivalent is within the above range, high pigment dispersibility is easily obtained without increasing the molecular weight of the anionic polymer dispersant. The anionic group equivalent of the anionic polymer dispersant can be determined from the acid value. The acid value can be measured in accordance with JIS K0070.

[0117] The weight average molecular weight (Mw) of the polymer dispersant is not particularly limited, but is preferably 5,000 or more and 30,000 or less. When the Mw of the polymer dispersant is 5,000 or more, the pigment particles can be easily dispersed sufficiently, and when it is 30,000 or less, the ink does not thicken too much, so that the penetration into the fabric is less likely to be impaired. The Mw of the polymer dispersant can be measured by the same method as above.

[0118] The content of the polymer dispersant is not particularly limited as long as it is in a range that sufficiently disperses the pigment particles and has a viscosity that does not impair the permeability into the fabric, but it is preferably from 20% to 100% by mass, and more preferably from 25% to 60% by mass, relative to the pigment.

[0119] 3. Image forming device An image forming apparatus used to form a textile image according to the present invention will now be described in detail. The image forming apparatus has the ink set described above.

[0120] FIG. 1 is a schematic diagram showing an outline of an embodiment of an image forming apparatus 100 used to form a textile image. As shown in FIG. 1, the image forming apparatus 100 includes a pretreatment liquid storage section 110a, a color ink storage section 110b, an overcoat liquid storage section 110c, a recording head 120, a head carriage 130, a drying section 140, and a transport section 150.

[0121] The pretreatment liquid storage unit 110a, the color ink storage unit 110b, and the overcoat liquid storage unit 110c store the pretreatment liquid a, the color ink liquid b, and the overcoat liquid c, respectively, and are arranged in this order from the upstream to the downstream direction in the transport direction Y of the fabric 160. The fabric 160 is transported by the transport unit 150.

[0122] The pretreatment liquid storage section 110a, the color ink storage section 110b, and the overcoat liquid storage section 110c supply the pretreatment liquid a, the color ink b, and the overcoat liquid c to the recording heads 120 connected to them, and the recording heads 120 eject the pretreatment liquid a, the color ink b, and the overcoat liquid c onto the fabric 160 by an inkjet method, thereby forming a printed image. Examples of the inkjet method include a thermal method and a piezo method.

[0123] A plurality of color ink containers 110b and recording heads 120 may be arranged, for example, for each ink color.

[0124] The head carriage 130 carries the recording head 120 and scans the recording head 120 in a main scanning direction that is substantially perpendicular to the transport direction Y of the fabric 160. The recording head 120 may move integrally with the colored ink storage section 110b, or may move separately.

[0125] The drying unit 140 is disposed downstream of each storage unit and each recording head 120 in the transport direction Y. The drying unit 140 may be a heating unit such as a hot air dryer that blows hot air, a heater that irradiates infrared rays or ionizing radiation, or a heating roller. The drying unit 140 dries the printed image formed on the fabric 160. The drying temperature is preferably higher than the melting point of the wax particles in order to melt the wax particles contained in the overcoat layer forming liquid. The drying temperature may be, for example, about 85 to 160°C so as to be higher than the melting point of the wax particles. In the present embodiment, the drying temperature is 150°C.

[0126] 4. Image forming method In the image forming method according to the embodiment of the present invention, an inkjet clear ink liquid is applied onto a fabric by an inkjet method.

[0127] Specifically, the image forming method according to the present embodiment includes the steps of applying an inkjet clear ink liquid containing a coagulant onto a fabric, applying a colored ink onto the inkjet clear ink liquid applied onto the fabric, and applying an inkjet clear ink liquid not containing a coagulant onto the colored ink applied onto the fabric.

[0128] The inkjet clear ink liquid containing the aggregating agent is a pre-treatment liquid, and the inkjet clear ink liquid not containing the aggregating agent is a post-treatment liquid (overcoat liquid).

[0129] In the image forming method, first, a pretreatment liquid is applied to the fabric by an inkjet method. The aggregating agent in the pretreatment liquid aggregates the color ink, thereby accelerating the fixation of the color ink.

[0130] The fabric may have been previously coated with a pretreatment liquid, i.e., the image forming method does not need to include a step of applying an inkjet clear ink liquid containing a flocculant onto the fabric.

[0131] Next, the color ink is applied to the pretreated fabric. Although there are no particular limitations on the application method, an inkjet method is preferred. Fixation of the color ink is promoted by the coagulant in the pretreatment liquid.

[0132] Next, an overcoat liquid is applied onto the colored ink applied to the fabric. The overcoat liquid adheres to the fabric so as to cover the pigment in the colored ink, thereby improving the fixation of the pigment. If the overcoat liquid contains a silicone resin, it can reduce the coefficient of friction of the surface, improve slipperiness, and increase the abrasion resistance of the image. The overcoat liquid is applied by an inkjet method.

[0133] The amount of the overcoat liquid applied is preferably 0.03 g / m 2 More than 2.2g / m 2 or less, more preferably 0.03 g / m 2 More than 1.2g / m 2 When the amount of silicone resin attached is within the above range, the texture of the fabric can be further improved.

[0134] The overcoat liquid may be applied either after the color ink applied to the fabric has dried or before it has dried. If the overcoat liquid is applied before it has dried, it will be applied onto the color ink. This is the so-called wet-on-wet process of applying the overcoat liquid. Applying the overcoat liquid wet-on-wet means applying the overcoat liquid before most of the droplets of the previously applied color ink have completely dried. Specifically, this means that, per unit area of ​​the recording region, the ratio (amount of ink remaining when the overcoat liquid is applied) / (amount of color ink applied) is 0.40 or more and 1.0 or less, preferably 0.50 or more and 1.0 or less, more preferably 0.70 or more and 1.0 or less, and even more preferably 0.80 or more and 1.0 or less. The amount of ink applied is, for example, 15 g / m 2 Less than 15 g / m 2 It can be said that:

[0135] The overcoat liquid applied to the fabric may be dried. When drying the ink or overcoat liquid, the solvent contained in each liquid applied to the fabric is removed and the fabric is dried. The drying method is not particularly limited, and the drying may be performed at room temperature or by heating. The heating method may be a method using a heater, a hot air dryer, a heating roller, or the like, and is preferably a method in which the fabric is heated from both sides using a hot air dryer and a heater.

[0136] The drying temperature is not particularly limited as long as it is a temperature at which the water-soluble organic solvent and water in the color ink and overcoat liquid can be removed, and can be, for example, from 80° C. to 180° C. The drying time depends on the drying temperature, but can be, for example, from 1 minute to 10 minutes.

[0137] The fibers constituting the fabric are not particularly limited, but include natural fibers such as cotton (cellulose fibers), hemp, wool, and silk; chemical fibers such as rayon, vinylon, nylon, acrylic, polyurethane, polyester, and acetate; and blended fibers thereof. Of these, the fibers constituting the fabric may be hydrophilic fibers such as cotton, hydrophobic fibers such as polyester, or blended fibers thereof. Furthermore, the fabric may be in any form, such as woven fabric, nonwoven fabric, or knitted fabric, from these fibers. Furthermore, the fabric may be a blended woven fabric or blended nonwoven fabric of two or more types of fibers.

[0138] 5. Image formation The image-formed product according to this embodiment includes a fabric, a pretreatment layer, a colored ink layer, and an overcoat layer.

[0139] The pretreatment layer is a layer derived from the pretreatment liquid, and contains a component derived from the pretreatment liquid, i.e., a flocculant.

[0140] The color ink layer is a layer derived from the color ink, and contains components derived from the color ink, that is, a pigment and a binder resin.

[0141] The overcoat layer is a layer derived from the overcoat liquid. The overcoat layer contains a component derived from the overcoat liquid, i.e., the resin (e.g., silicone resin). It is preferable that there is no clear interface between the color ink layer and the overcoat layer, and that the composition changes continuously. This is because adhesion between the ink layer and the overcoat layer is improved, and interfacial peeling can be further suppressed.

[0142] As described above, the inkjet clear ink liquid according to this embodiment is suitable for image formation using the inkjet method. [Example]

[0143] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0144] Inkjet clear ink liquids Nos. 1 to 18 having the compositions shown in Tables 1 and 2 were obtained and subjected to ejection evaluation. In addition, the abrasion fastness of images obtained using the inkjet clear ink liquids Nos. 1 to 8 as pre-treatment liquids and the inkjet clear ink liquids Nos. 9 to 18 as post-treatment liquids was evaluated.

[0145] (Components of inkjet clear ink liquid for ejection evaluation) Inkjet clear ink liquids 1 to 18 were obtained using the following components so as to have the compositions shown in Tables 1 and 2.

[0146] <solvent> 3-methyl-1,3-butanediol ethylene glycol Propylene glycol glycerin

[0147] <Flocculant> Cationic resin: PAS-M-1L (manufactured by Nittobo Medical Co., Ltd.)

[0148] <resin> Acrylic resin: EMN-325E (manufactured by Nippon Shokubai Co., Ltd.) Silicone acrylic resin: Chaline FE-230 (manufactured by Nissin Chemical Industry Co., Ltd.)

[0149] <Surfactants> Acetylenic surfactant: Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.)

[0150] <Preservatives> Proxcel GXL (manufactured by Lonza)

[0151] (Injection evaluation 1: dryness, moisture retention) The prepared inkjet clear ink liquid was ejected under conditions of 25° C. and 50% RH using a fixed inkjet head (KM1024iMHE) manufactured by Konica Minolta, Inc., with a droplet ejection volume of 13 pL.

[0152] After confirming that the filled inkjet clear ink liquid was being ejected from all 60 nozzles at the start of ejection, ejection was stopped for 10 minutes. After the 10-minute ejection stop, the inkjet clear ink liquid was ejected from the nozzles again, and the number of nozzles that were able to eject without any problems was counted. The evaluation criteria were as follows. The evaluation results are shown in Tables 1 and 2. ○: 60 nozzles can be ejected again after 10 minutes of stopping ejection △: After stopping discharge for 10 minutes, the number of nozzles that can discharge again is 50 or more but less than 60 ×: The number of nozzles that can eject again after stopping ejection for 10 minutes is less than 50

[0153] (Ejection Evaluation 2: Satellite) The prepared inkjet clear ink liquid was ejected under conditions of 25° C. and 50% RH using a fixed inkjet head (KM1024iMHE) manufactured by Konica Minolta, Inc., with a droplet ejection volume of 13 pL.

[0154] After confirming that the filled inkjet clear ink liquid was being discharged from the nozzle at the start of discharge, the state of the droplets was observed. The length of the satellites was then measured. The evaluation criteria were as follows: ○: Satellite length is 0 μm △: Satellite length is less than 100 μm ×: Satellite length is 100 μm or more

[0155] (viscosity) The viscosity of the inkjet clear ink liquid was measured using a TPE-100L viscometer (manufactured by Toki Sangyo Co., Ltd.) at 25°C, 50 rpm, and 60 seconds. The measurement results are shown in Tables 1 and 2.

[0156] (Components and composition of colored ink liquid 1 used in dry rub fastness evaluation) A colored ink was obtained having the following composition:

[0157] <Pigment dispersion> Cab-0-Jet-400 (manufactured by CABOT) 5 parts by mass <resin> Acrylic resin: EMN-325 (manufactured by Nippon Shokubai Co., Ltd.) 10 parts by weight <solvent> Ethylene glycol 20 parts by mass Glycerin 10 parts by mass <Surfactants> Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 0.1 parts by mass <Preservatives> Proxcel GXL (Lonza) 0.1 parts by mass 〈Remainder〉 Water 54.8 parts by mass

[0158] As an image forming apparatus, a simple printing tester equipped with a KM1024iMHE head manufactured by Konica Minolta, Inc. was prepared. The pretreatment liquid, colored ink, and posttreatment liquid prepared above were each set in the head of the apparatus.

[0159] 1. Evaluation of pretreatment liquid (1) Applying pre-treatment liquid First, cotton satin (100% cotton) was prepared as a fabric. Each of the pretreatment liquids No. 1 to No. 8 having the composition shown in Table 1 was ejected from the head onto the fabric, and the amount of the pretreatment liquid applied was 15 g / m. 2 It was given so that

[0160] (2) Applying colored ink The pretreated fabric was then imaged using the colored ink prepared above. Specifically, the prepared ink was ejected from the head to form a solid image. The ink was ejected at 540 dpi in the main scanning direction and 720 dpi in the sub-scanning direction. dpi represents the number of ink droplets (dots) per 2.54 cm. The ejection frequency was 22.4 kHz. The amount of ink applied was 15 g / m. 2 It was decided.

[0161] (3) Applying post-processing liquid Before the ink layer formed on the fabric was completely dry, the overcoat liquid No. 10 having the composition shown in Table 1 was ejected from the head and applied wet-on-wet onto the solid image. The image was then dried at 150°C for 3 minutes in a belt-conveying dryer to obtain an image-formed product. The amount of the overcoat liquid applied was 15 g / m. 2 It was decided.

[0162] 2. Evaluation of post-processing liquid (1) Applying pre-treatment liquid Pretreatment liquid No. 1 having the composition shown in Table 1 was applied in the same manner as in the evaluation of the pretreatment liquid.

[0163] (2) Applying colored ink Colored ink was applied in the same manner as in the evaluation of the pretreatment.

[0164] (3) Applying post-processing liquid Before the ink layer formed on the fabric was completely dry, each of the overcoat liquids No. 8 to No. 18, having the composition shown in Table 1, was ejected from the head and applied wet-on-wet onto the solid image. The image was then dried at 150°C for 3 minutes in a belt-conveying dryer to obtain an image-formed product. The amount of the overcoat liquid applied was 15 g / m. 2 It was decided.

[0165] 3. Evaluation The resulting image-formed product was evaluated for abrasion resistance, texture, and ejection stability of the overcoat liquid by the following methods.

[0166] Abrasion resistance Dry and wet rubbing fastness evaluations were carried out using a crock meter (rubbing tester type I) in accordance with JIS L 0849. The fabrics to be evaluated were graded using a staining gray scale based on JIS 0805, and evaluated using the following indices. ○ Grade 4 or above △ Grade 3 or above but below grade 4 × Less than Grade 3

[0167] [Table 1]

[0168] [Table 2]

[0169] Inks Nos. 3 to 5 used as pretreatment liquids contain 3-methyl-1,3-butanediol, but inks Nos. 1, 6, and 7 do not contain 3-methyl-1,3-butanediol. As can be seen by comparing inks No. 3 to 5 with inks No. 1, 6, and 7, increasing the viscosity of the ink by adding 3-methyl-1,3-butanediol improved the ejection evaluations 1 and 2 and the rub fastness. This shows that 3-methyl-1,3-butanediol is an excellent solvent for increasing the viscosity of the inkjet clear ink liquid used as a pretreatment liquid.

[0170] On the other hand, as can be seen from ink No. 2, when too much 3-methyl-1,3-butanediol was added, the ejection rating of 1 and the rub fastness were poor. It was found that it is desirable to limit the amount of 18% by mass or less of the clear ink to 1,3-methyl-1,3-butanediol.

[0171] Similarly, inks Nos. 10, 11, 16, and 17 used as post-treatment liquids contain 3-methyl-1,3-butanediol, but inks Nos. 8, 12 to 15, and 18 do not contain 3-methyl-1,3-butanediol. As can be seen by comparing inks No. 10, 11, 16, and 17 with inks No. 8, 12 to 15, and 18, increasing the viscosity of the ink by adding 3-methyl-1,3-butanediol improved the ejection ratings 1 and 2 and rub fastness. This shows that 3-methyl-1,3-butanediol is an excellent solvent for increasing the viscosity of clear ink used as a post-treatment liquid.

[0172] On the other hand, as can be seen from ink No. 9, when too much 3-methyl-1,3-butanediol was added, the ejection rating of 1 and the rub fastness were poor. It was found that it is desirable to limit the amount of 18% by mass or less of the clear ink to 1,3-methyl-1,3-butanediol. [Industrial Applicability]

[0173] According to the present invention, it is possible to provide an inkjet clear ink liquid for textile printing that has ejection stability and high abrasion fastness. [Explanation of symbols]

[0174] 100 Image forming device 110a Pretreatment liquid storage section 110b Colored ink storage section 110c Overcoat liquid storage section 120 recording head 130 Head Carriage 140 Drying section 150 Conveyor 160 Fabric a Pretreatment solution b. Colored ink c Overcoat liquid Y conveying direction

Claims

1. An inkjet clear ink liquid for textile printing, the inkjet clear ink liquid contains 3-methyl-1,3-butanediol, and the content of the 3-methyl-1,3-butanediol is 18% by mass or less relative to the inkjet clear ink liquid; Inkjet clear ink liquid.

2. The inkjet clear ink liquid according to claim 1 , further comprising an organic solvent, the content of the organic solvent being 40% by mass or less relative to the inkjet clear ink liquid.

3. The inkjet clear ink liquid according to claim 1, wherein the viscosity at 25°C is 4.5 cp or more and 9 cp or less.

4. The inkjet clear ink liquid according to claim 1 , further comprising a flocculating agent or a resin.

5. The inkjet clear ink liquid according to claim 4 , wherein the resin is an anionic resin or a cationic resin.

6. The inkjet clear ink liquid according to claim 1, wherein the total solid content is from 0% to 8% by mass based on the inkjet clear ink liquid.

7. An ink set comprising the inkjet clear ink liquid according to any one of claims 1 to 6 and a colored ink.

8. 8. The ink set according to claim 7, wherein the color inks contain a pigment, a binder resin, water, and a water-soluble organic solvent.

9. An image forming apparatus comprising the ink set according to claim 7.

10. An image forming method comprising applying the inkjet clear ink liquid according to any one of claims 1 to 6 onto a fabric by an inkjet system.

11. The image forming method according to claim 10, applying an inkjet clear ink liquid containing a flocculant onto a fabric; applying a colored ink onto the inkjet clear ink liquid applied onto the fabric; applying an inkjet clear ink liquid containing no aggregating agent onto the colored ink applied to the fabric; having Image forming method.

Images