Inkjet printing ink and image forming method

Abstract

To provide an inkjet textile printing ink that can form an image having sufficient density without impairing the texture of fabric.SOLUTION: An inkjet textile printing ink of the present invention contains a pigment, a polymer particle having a glass transition temperature of 50°C or higher, and water, and the ratio M2 / M1 between the pigment content M1 and the polymer particle content M2 is 3 to 19 at mass ratio.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ink-jet textile printing ink and an image forming method. [Background technology]

[0002] Conventionally, as a textile printing method, exhaustion printing, in which a fabric is immersed in a bath filled with a dye, and the like has been known, but since dyeing requires a long time, production efficiency is low. In recent years, so-called inkjet printing, in which an image is formed on a fabric by an inkjet method, has been widely used because dyeing can be performed in a short time and production efficiency is high.

[0003] In inkjet textile printing, minute droplets of ink are ejected from an inkjet recording head and landed on a fabric to form an image. Dye inks are known as inks used in inkjet textile printing (inkjet textile printing inks). For example, inks containing reactive dyes are known for use on fabrics containing cotton, rayon fibers, hemp fibers, and the like.

[0004] In dye inks, the dye dissolves in or reacts with the fibers of the fabric, making it easy to form images with high fastness without losing the texture of the fibers. On the other hand, a washing step is required to wash away undissolved or unreacted dye, and therefore, from the viewpoint of further improving production efficiency, it is desirable to be able to omit such a step.

[0005] In response to this, pigment inks suitable for inkjet printing have been studied. For example, a pigment printing inkjet ink composition containing a pigment, urethane resin particles, a surfactant, and water is known (see, for example, Patent Document 1). In the examples, it is shown that the content of the urethane resin particles in the ink composition is 1.5 or less relative to the content of the pigment.

[0006] Also known is a colorant composition for preventing fabric from showing through, which contains a pigment, a polymer particle dispersion having a Tg of 20° C. or less, and water (see, for example, Patent Document 2). This document describes that after the colorant composition is applied to the back surface of the fabric, the solvent is evaporated and the polymer particles are made into a film, so that the pigment and the polymer particles are fixed to the fabric. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2019-163397 A [Patent Document 2] JP 2008-133461 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, even if an ink having a relatively low content of resin particles as disclosed in Patent Document 1 is applied onto a fabric, there is a problem that the density of the resulting image is low and color reproducibility cannot be obtained.

[0009] In addition, since the colorant composition of Patent Document 2 contains polymer particles with a low Tg, when the colorant composition applied to a fabric is dried, the polymer particles form a film and the fibers are easily bonded together, which makes the resulting image-formed product hard and easily damages the texture of the fabric.

[0010] The present invention has been made in consideration of the above circumstances, and has an object to provide an inkjet textile printing ink capable of forming an image having sufficient density without impairing the texture of the fabric, and an image forming method using the same. [Means for solving the problem]

[0011] The present invention relates to the following ink-jet textile printing ink and image forming method.

[0012] The inkjet textile printing ink of the present invention contains a pigment, polymer particles having a glass transition temperature of 50° C. or higher, and water, and the ratio M2 / M1 of the pigment content M1 to the polymer particle content M2 is 3 to 19 (mass ratio).

[0013] The image forming method of the present invention includes a step of applying droplets of the ink-jet textile printing ink of the present invention onto a fabric by an ink-jet system. Effect of the Invention

[0014] According to the present invention, it is possible to provide an ink-jet textile printing ink capable of forming an image of sufficient density without impairing the texture of the fabric, and an image forming method using the same. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1A is a cross-sectional view showing an image of the state of ink adhesion near the surface of a fabric when a conventional ink is applied to the fabric, and FIG. 1B is a cross-sectional view showing an image of the state of ink adhesion near the surface of a fabric when the ink of the present invention is applied to the fabric. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The inventors have found that by setting the Tg of the polymer particles contained in the pigment ink to 50° C. or higher and by appropriately increasing the polymer particle content M2 relative to the pigment content M1, it is possible to form a high-density image without impairing the texture of the fabric. The reason for this is unclear, but is presumed to be as follows.

[0017] Fig. 1A is a cross-sectional view showing an image of the state of adhesion of ink near the surface of a fabric when a conventional ink is applied to the fabric, and Fig. 1B is a cross-sectional view showing an image of the state of adhesion of ink near the surface of a fabric when the ink of the present invention is applied to the fabric. Note that Fig. 1A shows an example of the conventional ink in which an ink that does not contain polymer particles is used.

[0018] When a conventional pigment ink that does not contain polymer particles or has a relatively small content of polymer particles is applied to the surface of a fabric, the pigment particles 11 tend to gather in the gaps between the fibers 10 due to capillary action when the ink dries, and the pigment particles 11 are unlikely to be present on the surface of the fibers 10 (see FIG. 1A). Therefore, the obtained image tends to show the background color of the fibers 10, and the optical density (image density) of the pigment particles 11 is unlikely to be exhibited.

[0019] In contrast, the pigment ink of the present invention contains a larger amount of polymer particles 12 in addition to pigment particles 11. When such a pigment ink is applied to the surface of a fabric, a suitable amount of polymer particles 12 gathers in the gaps between fibers 10 when the ink dries, making it possible to reduce the proportion of pigment particles 11 gathering in the gaps between fibers 10 (see FIG. 1B). As a result, pigment particles 11 are more likely to be distributed on the surface of fibers 10, making the background color of fibers 10 less noticeable and making it easier to produce the optical density (image density) of pigment particles 11.

[0020] Furthermore, because pigment particles 11 usually have a high refractive index, when pigment particles 11 are concentrated in a specific area as in the past, light reflection from the surfaces of pigment particles 11 in the concentrated area increases, making colors appear dull. In contrast, by using the pigment ink of the present invention, the concentration of pigment particles 11 per volume can be lowered and light reflection per volume can be reduced, making colors less likely to appear dull and allowing beautiful colors to be reproduced.

[0021] In addition, when the Tg of the polymer particles 12 is as low as 20° C. or less as in Patent Document 1, the polymer particles 12 fuse together and form a film when the ink dries, and the fibers 10 are bonded together, so that the resulting image tends to become hard. In contrast, the Tg of the polymer particles 12 contained in the pigment ink of the present invention is as high as 50° C. or more, so that the polymer particles 12 are less likely to fuse together and form a film when the ink dries. As a result, the fibers 10 are less likely to be bonded together, so that the image tends to become hard and the texture of the fabric is less likely to be damaged. The composition of the ink of the present invention will be described below.

[0022] 1. Inkjet textile printing ink The inkjet textile printing ink contains a pigment, polymer particles, and water.

[0023] 1-1.Pigments The pigment is not particularly limited, but may be, for example, an organic or inorganic pigment having the following numbers as described in the Color Index:

[0024] Examples of orange or yellow pigments include CI Pigment Orange 31, CI Pigment Orange 43, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 83, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 128, CI Pigment Yellow 138, CI Pigment Yellow 151, CI Pigment Yellow 154, CI Pigment Yellow 155, CI Pigment Yellow 180, CI Pigment Yellow 185, CI Pigment Yellow 213, and the like.

[0025] 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, Pigment Orange 13, 16, 20, 36.

[0026] 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.

[0027] Examples of green pigments include Pigment Green 7, 26, 36, and 50. Examples of yellow pigments include Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, and 193.

[0028] Examples of black pigments include Pigment Black 7, 28, and 26.

[0029] Commercially available examples of pigments include: Chromofine Yellow 2080, 5900, 5930, AF-1300, 2700L, Chromofine Orange 3700L, 6730, Chromofine Scarlet 6750, Chromofine Magenta 6880, 6886, 6891N, 6790, 6887, Chromofine Violet RE, Chromofine Red 6820, 6830, Chromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P , Chrome Fine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Chrome Fine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400(B), 2500, 2600, ZAY-260, 2700(B), 2770 , Seika Fast Red 8040, C405(F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmine 6B1476T-7, 1483LT, 3840, 3870, Seika Fast Bordeaux 10B-430, Seika Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C718, A612, Cyanine Blue 4933M, 4933GN-EP, 4940, 4973 (Dainichi Seika Chemicals); KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (manufactured by Dainippon Ink & Chemicals);Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pigment Yellow1705, Colortex Orange 202, Colortex Red101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, USN, Colortex Maroon601, Colortex BrownB610N, Colortex Violet600, Pigment Red 122, Colortex Blue516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403, Colortex Black 702, U905 (Sanyo Pigment); Lionol Yellow 1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (Toyo Ink Co., Ltd.); Toner Magenta E02, Permanent Rubin F6B, Toner Yellow HG, Permanent Yellow GG-02, Hostapearm Blue B2G (Hoechst Industry); Novoperm P-HG, Hostaperm Pink E, Hostaperm Blue B2G (manufactured by Clariant); Carbon black #2600, #2400, #2350, #2200, #1000, #990, #980, #970, #960, #950, #850, MCF88, #750, #650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77, #52, #50, #47, #45, #45L, #40, #33, #32, #30, #25, #20, #10, #5, #44, CF9 (manufactured by Mitsubishi Chemical).

[0030] From the viewpoint of improving dispersibility in the ink, the pigment is preferably further dispersed with a pigment dispersant, which will be described later.

[0031] The pigment may 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.

[0032] Examples of hydrophilic groups include carboxyl groups, sulfonic acid groups, and phosphorus-containing groups. Examples of phosphorus-containing groups include phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, phosphite groups, and phosphate groups.

[0033] Commercially available examples of self-dispersing pigments include Cabot's Cab-0-Jet® 200K, 250C, 260M, and 270V (sulfonic acid group-containing self-dispersing pigments), Cab-0-Jet® 300K (carboxylic acid group-containing self-dispersing pigments), and Cab-0-Jet® 400K, 450C, 465M, 470V, and 480V (phosphate group-containing self-dispersing pigments).

[0034] The average particle diameter d1 of the pigment means the average particle diameter of the pigment dispersed in the ink, specifically, when the ink contains a pigment dispersant, the average dispersed particle diameter (Z average) of the pigment particles to which the pigment dispersant is adsorbed. The average particle diameter d1 of the pigment may be within a range that does not impair the ejection properties by the inkjet method, and is not particularly limited, but is preferably 50 to 350 nm, and more preferably 70 to 250 nm. The dispersed particle diameter of the pigment can be measured by a particle size distribution measuring device using dynamic scattering.

[0035] The average particle diameter d1 of the pigment can be adjusted mainly by the size of the pigment particles themselves, but can also be adjusted by the molecular weight and content of the pigment dispersant, the dispersion treatment conditions of the pigment particles, and the like.

[0036] The pigment content M1 is not particularly limited, but from the viewpoint of easily adjusting the viscosity of the ink within the above range and enabling the formation of a high-density image, it is preferably 0.3 to 10% by mass relative to the ink. If the pigment content M1 is 0.3% by mass or more, a large amount of polymer particles can be contained, so that the color of the obtained image tends to be vivid, and if it is 5% by mass or less, the viscosity of the ink does not become too high, so that ejection stability is not easily impaired. From the same viewpoint, it is more preferable that the pigment content M1 is 0.5 to 3% by mass relative to the ink.

[0037] 1-2.Polymer particles Polymer particles having a Tg of 50° C. or more are present together with pigment particles, and can reduce the volume density of the pigment particles while increasing the volume of the particles, making it difficult for the pigment particles to gather in the gaps between fibers. When the Tg of the polymer particles is 50° C. or more, it is possible to suppress the polymer particles from fusing and forming a film when the ink applied to the fabric is dried. This makes it difficult for the image-formed product to become hard, and makes it difficult for the texture of the fabric to be damaged. From the same viewpoint, it is more preferable that the Tg of the polymer particles is 80 to 150° C. When the Tg of the polymer particles is 150° C. or less, the fixability of the polymer particles and pigment particles to the fabric is further difficult to be damaged.

[0038] The Tg of the polymer particles can be measured by the following method. First, the polymer particles separated from the ink are dried to prepare a sample. This sample is subjected to differential scanning calorimetry in accordance with JIS K7121 at a temperature rise rate of 10° C. / min to determine the glass transition temperature.

[0039] The Tg of the polymer particles can be adjusted by the composition and degree of crosslinking of the resin that constitutes the polymer particles.

[0040] Moreover, from the viewpoint of reproducing the color of the pigment particles to a high degree, the polymer particles are preferably colorless. Specifically, the colorless polymer particles refer to polymer particles that do not have a UV absorption peak at a wavelength of 400 to 700 nm in an absorption spectrum obtained by UV-Vis spectrometry.

[0041] Furthermore, the polymer particles preferably have light-transmitting properties, and more preferably are transparent, that is, the polymer particles are particularly preferably colorless and transparent.

[0042] Such polymer particles are not particularly limited as long as they have at least a Tg that satisfies the above range, but preferably contain, for example, one or more resins selected from the group consisting of (meth)acrylic resins, polystyrene resins, acrylonitrile resins, urethane resins, polyester resins, and epoxy resins. Among these, from the viewpoint of having a moderately high Tg and being less likely to impair texture, the polymer particles preferably contain a resin selected from the group consisting of (meth)acrylic resins and polystyrene resins.

[0043] ((Meth)acrylic resin) The (meth)acrylic resin may be a homopolymer of at least one of a (meth)acrylic acid ester and (meth)acrylonitrile, or a copolymer of the homopolymer and another copolymerizable monomer.

[0044] The (meth)acrylic acid ester is a monofunctional (meth)acrylic acid ester, examples of which include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl (meth)acrylate, etc., and is preferably methyl methacrylate. The (meth)acrylonitrile is acrylotryl or methacryloylnitrile.

[0045] The total content of the structural units derived from a (meth)acrylic acid ester and the structural units derived from a (meth)acrylonitrile can be 50% by mass or more, and preferably 60% by mass or more, based on all the structural units constituting the resin.

[0046] The other copolymerizable monomer may be another monofunctional vinyl monomer or a polyfunctional vinyl monomer (crosslinkable vinyl monomer).

[0047] Examples of other monofunctional vinyl monomers include ethylenically unsaturated carboxylic acids (e.g., (meth)acrylic acid, maleic acid, itaconic acid, etc.), functional group-containing (meth)acrylates (e.g., quaternary ammonium group-containing (meth)acrylates such as trimethylammonium ethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, etc.), acrylamide, styrenes (e.g., styrene, α-methylstyrene, vinyl toluene, etc.), and saturated fatty acid vinyls (e.g., vinyl acetate, vinyl propionate, etc.). The content of structural units derived from other monofunctional vinyl monomers may be 50% by mass or less based on the total structural units constituting the resin.

[0048] Examples of polyfunctional vinyl monomers include vinyl compounds (e.g., 1,4-divinyloxybutane, divinylbenzene, etc.), allyl compounds (e.g., diallyl phthalate, triallyl cyanurate, etc.), and polyfunctional (meth)acrylates (e.g., ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc.). The content of the structural unit derived from the polyfunctional vinyl monomer can be 20% by mass or less, preferably 0.5 to 10% by mass, based on the total structural units constituting the resin.

[0049] In addition, from the viewpoint of making it more difficult for polymer particles to fuse together, the acrylic resin may be crosslinked (i.e., it may be a crosslinked acrylic resin). The crosslinked acrylic resin is a copolymer of a monofunctional vinyl monomer containing at least one of a (meth)acrylic acid ester and (meth)acrylonitrile, and a polyfunctional vinyl monomer. This is because such a crosslinked (meth)acrylic resin is difficult to fuse and difficult to form a film when the ink dries.

[0050] (Polystyrene resin) The polystyrene resin may be a homopolymer of a styrene or a copolymer of a styrene with another copolymerizable monomer.

[0051] The styrenes may be the same as those described above. The structural units derived from styrenes may be 50% by mass or more, preferably 60% by mass or more, based on the total structural units constituting the resin. The other copolymerization monomers may be the same as those described above.

[0052] The polystyrene resin may be a cross-linked polystyrene resin, which is a copolymer of a monofunctional vinyl monomer containing a styrene and a polyfunctional vinyl monomer.

[0053] Among these, the polymer particles are preferably particles containing polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), a methacrylate-acrylonitrile copolymer, polystyrene or a styrene copolymer.

[0054] (Common physical properties) The acid value of the resin (water-dispersible resin) constituting the polymer particles is not particularly limited as long as it can be well dispersed in an aqueous medium, but is, for example, 20 to 140 mgKOH / g, preferably 30 to 70 mgKOH / g. The acid value can be measured in accordance with JIS K 0070 or ISO 3961. Specifically, it can be measured as the number of mg of potassium hydroxide (KOH) required to neutralize 1 g of a sample.

[0055] The average particle diameter d2 of the polymer particles is not particularly limited, but from the viewpoint of preventing the pigment particles from gathering in the gaps between the fibers of the fabric, it is preferable that the average particle diameter d2 is not too small compared to the average particle diameter d1 of the pigment particles. Specifically, the ratio d2 / d1 of the average particle diameter d1 of the pigment to the average particle diameter d2 of the polymer particles is preferably 0.5 to 3, and more preferably 1.1 to 2.5.

[0056] The average particle diameter d2 of the polymer particles is, for example, preferably from 80 to 400 nm, and more preferably from 150 to 300 nm. The average particle diameter d2 of the polymer particles can be measured in the same manner as the average particle diameter d1 of the pigment particles.

[0057] The ratio M2 / M1 of the content M2 of the polymer particles in the ink to the content M1 of the pigment is preferably 3 to 19 (mass ratio). When M2 / M1 is 3 (mass ratio) or more, the ratio of pigment particles gathering in the gaps between the fibers of the fabric when the ink is applied to the fabric can be reduced. Therefore, the pigment particles can be easily distributed uniformly on the surface of the fibers, so that a sufficient image density can be easily obtained. On the other hand, when M2 / M1 is 19 (mass ratio) or less, the ratio of the pigment particles in the ink is not too small, so that not only the image density is not easily reduced, but also the texture is not easily impaired because the ratio of the polymer particles is not too high. From the same viewpoint, the ratio M2 / M1 is more preferably 5 to 17 (mass ratio), and even more preferably 8 to 14 (mass ratio).

[0058] Specifically, the content M2 of the polymer particles is preferably 1 to 10% by mass, and more preferably 3 to 8% by mass, relative to the ink. The polymer particles may be used alone or in combination of two or more types.

[0059] 1-3.Solvent The solvent is not particularly limited, but preferably contains water and further contains a water-soluble organic solvent.

[0060] The water-soluble organic solvent is not particularly limited as long as it is compatible with water, but from the viewpoint of making it easier for the ink to penetrate into the interior of the fabric and making it difficult for the ejection stability in the inkjet method to be impaired, it is preferable that the ink does not easily thicken due to drying. Therefore, it is preferable that the ink contains a high-boiling point solvent having a boiling point of 200° C. or more.

[0061] The high-boiling solvent having a boiling point of 200° C. or higher may be any water-soluble organic solvent having a boiling point of 200° C. or higher, and is preferably a polyol or a polyalkylene oxide.

[0062] Examples of polyols having a boiling point of 200°C or higher include dihydric alcohols such as 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).

[0063] Examples of polyalkylene oxides having a boiling point of 200° C. or higher include ethers of dihydric alcohols such as diethylene glycol monoethyl ether (boiling point 202° C.), triethylene glycol monomethyl ether (boiling point 245° C.), tetraethylene glycol monomethyl ether (boiling point 305° C.), tripropylene glycol monoethyl ether (boiling point 256° C.) and polypropylene glycol, and ethers of trihydric or higher alcohols such as glycerin (boiling point 290° C.) and hexanetriol.

[0064] The solvent may further include other solvents in addition to the high boiling point solvent. Examples of the other solvents include polyhydric alcohols having a boiling point of less than 200° C. (e.g., ethylene glycol, propylene glycol, hexanetriol, etc.); polyhydric alcohol ethers having a boiling point of less than 200° C. (e.g., ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether); monohydric alcohols (e.g., methanol, ethanol, propanol, pentanol, hexanol, cyclohexanol, butyl ether ... 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).

[0065] 1-4.Other ingredients The inkjet printing ink may further contain other components as necessary, such as a pigment dispersant, a surfactant, a preservative, an antifungal agent, and a pH adjuster.

[0066] (Pigment dispersant) The pigment dispersant is present in the 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 and disperse the pigment well. From the viewpoint of excellent pigment dispersibility, such a pigment dispersant is preferably a polymer dispersant.

[0067] Examples of the polymer dispersant include anionic dispersants and cationic dispersants.

[0068] The anionic dispersant may be a polymer dispersant having a hydrophilic group selected from the group consisting of a carboxylic acid group, a phosphorus-containing group, and a sulfonic acid group. Among these, a polymer dispersant having a carboxylic acid group is preferred.

[0069] Examples of polymeric dispersants having a carboxylic acid group include polycarboxylic acids or their salts. 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 constituting the copolymer include styrene and vinylnaphthalene.

[0070] The anionic group equivalent of the anionic dispersant is not particularly limited as long as it can disperse the pigment particles sufficiently, but is preferably, for example, 1.1 to 3.8 meq / g. When the anionic group equivalent is within the above range, high pigment dispersibility is easily obtained without increasing the molecular weight of the anionic dispersant. The anionic group equivalent can be measured by the same method as the method for measuring the acid value.

[0071] Examples of the cationic group contained in the cationic dispersant include a secondary amino group (imino group), a tertiary amino group, a quaternary ammonium group, etc. The cationic dispersant is not particularly limited as long as it can form the above-mentioned pigment dispersion, and may be, for example, a cationic polymer (polymer or prepolymer).

[0072] Examples of cationic polymers include (co)polymers of ethylenically unsaturated monomers having a cationic group (a tertiary amino group or a quaternary ammonium group).

[0073] Examples of ethylenically unsaturated monomers having a tertiary amino group include dialkylaminoalkyl (meth)acrylates such as dimethyl or diethylaminoethyl (meth)acrylate, dimethyl or diethylaminopropyl (meth)acrylate, etc.; dialkylaminoalkyl (meth)acrylamides such as dimethyl or diethylaminoethyl (meth)acrylamide, dimethyl or diethylaminopropyl (meth)acrylamide, etc.; (meth)acrylamides such as acrylamide, etc.

[0074] Examples of ethylenically unsaturated monomers having a quaternary ammonium group include (meth)acryloyloxyalkyltrialkylammonium salts such as 2-(meth)acryloyloxyethyltrimethylammonium chloride and 3-(meth)acryloyloxy-2-hydroxypropyltrimethylammonium chloride; (meth)acrylamidoalkyltrialkylammonium salts such as acrylamide-2-(acryloyloxy)methyltrimethylammonium chloride, (3-(meth)acrylamidopropyltrimethylammonium chloride and 3-(meth)acryloylamino-2-hydroxypropyltrimethylammonium chloride; 2-(meth)acryloyloxyethylbenzylammonium chloride and 2-(meth)acryloyloxyethyldimethylbenzylammonium chloride, and other 2-(meth)acryloyloxyalkylbenzylammonium salts; and dialkyldiallylammonium salts such as dimethyldiallylammonium chloride.

[0075] The ethylenically unsaturated monomer having a cationic group may be one type or two or more types. For example, an ethylenically unsaturated monomer having a tertiary amino group and an ethylenically unsaturated monomer having a quaternary ammonium group may be copolymerized.

[0076] These ethylenically unsaturated monomers having a cationic group may be copolymerized with other monomers, examples of which include (meth)acrylic acid and its esters, allyl ethers, vinyl ethers, aromatic vinyl monomers, vinyl ester monomers, olefin monomers, and diene monomers.

[0077] Examples of such cationic polymers include dimethylaminoethyl methacrylate polymer, methacrylic acid-2-dimethylaminoethyl methacrylate copolymer, butyl acrylate-dimethylaminoethyl methacrylate copolymer, acrylamide-2-(acryloyloxy)methyltrimethylammonium chloride polymer, dimethyldiallylammonium chloride-acrylamide copolymer, and the like.

[0078] The cationic group equivalent of the cationic dispersant is not particularly limited as long as it can disperse the pigment particles sufficiently, but is preferably, for example, 1 to 5 meq / g. When the cationic group equivalent is within the above range, high pigment dispersibility is easily obtained without increasing the molecular weight of the cationic dispersant. The cationic group equivalent can be measured by the same method as the method for measuring the amine value.

[0079] Among these, from the viewpoints of eliminating the need for cationic pretreatment, which is prone to causing stains, and making it easier to maintain color reproducibility for a longer period of time, it is preferable that the pigment dispersant contained in the pigment ink is a cationic dispersant.

[0080] The weight average molecular weight of the polymer dispersant is not particularly limited, but is preferably 5000 to 30000. When the weight average molecular weight of the polymer dispersant is 5000 or more, the pigment particles can be dispersed sufficiently, and when it is 30000 or less, the ink does not thicken too much, so that the permeability into the fabric is not easily impaired. The weight average molecular weight of the polymer dispersant can be measured in styrene equivalent terms by gel permeation chromatography.

[0081] The content of the polymer dispersant is not particularly limited as long as it is within a range in which the pigment particles can be sufficiently dispersed and the viscosity is such that the permeability into the fabric is not impaired. However, the content is preferably 20 to 100% by mass, and more preferably 25 to 60% by mass, relative to the pigment.

[0082] (Surfactant) The inkjet textile printing ink may further contain a surfactant, if necessary.

[0083] The surfactant can reduce the surface tension of the ink and increase the wettability of the ink to the fabric. The type of the surfactant is not particularly limited, and can be, for example, an acetylene glycol surfactant, a silicone surfactant, or a fluorine surfactant.

[0084] (Preservatives, antifungal agents) Examples of preservatives or antifungal agents 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.

[0085] (pH adjuster) Examples of pH adjusters include citric acid, sodium citrate, hydrochloric acid, sodium hydroxide, and the like.

[0086] 1-5.Physical properties The viscosity of the ink at 25°C is not particularly limited as long as it provides good ejection properties by the inkjet method, but is preferably 3 to 20 mPa s, and more preferably 4 to 12 mPa s. The ink viscosity can be measured at 25°C using an E-type viscometer.

[0087] 1-6. Preparation of ink The ink of the present invention can be produced by any method. For example, the ink of the present invention can be produced by 1) mixing a pigment, a pigment dispersant, and a solvent (such as water) to obtain a pigment dispersion, and 2) further mixing the obtained pigment dispersion, a dispersion containing polymer particles, and any other components (such as a surfactant, a high-boiling point solvent, etc.). This makes it easy to obtain an ink in which the pigment is well dispersed.

[0088] 2. Image forming method The image forming method of the present invention includes a step of applying droplets of the ink of the present invention onto a fabric by an ink-jet system.

[0089] Specifically, the image forming method of the present invention includes 1) a step of ejecting ink from an inkjet recording head and applying ink droplets onto a fabric (ink application step), and 2) a step of drying and fixing the ink applied to the fabric (drying and fixing step).

[0090] Regarding step 1 (ink application process) Ink is ejected from an inkjet recording head to deposit ink droplets onto the fabric.

[0091] The type of fiber material constituting the fabric is not particularly limited, and preferably includes natural fibers such as cotton (cellulose fiber), hemp, wool, and silk; and chemical fibers such as rayon, vinylon, nylon, acrylic, polyurethane, polyester, and acetate. The fabric may be any form of fabric made from these fibers, such as woven fabric, nonwoven fabric, knitted fabric, etc. The fabric may also be a blended woven fabric or blended nonwoven fabric of two or more types of fibers.

[0092] For example, when the ink contains an anionic dispersant, from the viewpoint of increasing the pigment adsorption speed and fixability, it is preferable that the fabric has cationic groups or acid groups at least on the surface. The fabric having cationic groups or acid groups at least on the surface may be pretreated or may not be pretreated.

[0093] Furthermore, when the ink contains a cationic dispersant, from the viewpoint of increasing the pigment adsorption speed and fixability, it is preferable that the fabric has anionic groups at least on the surface. That is, fabrics containing fibers having anionic groups (e.g., cotton or polyester having anionic groups) have anionic groups as they are, and therefore do not necessarily need to have anionic groups imparted thereto by pretreatment. On the other hand, fabrics not containing fibers having anionic groups do not have anionic groups as they are, and therefore it is preferable that anionic groups are imparted thereto by pretreatment.

[0094] In the present invention, when the ink is applied, the polymer particles contained in the ink gather to a certain extent in the gaps between the fibers, so that the pigment particles are less likely to gather excessively in the gaps between the fibers and are more likely to be distributed uniformly on the surface of the fibers (see Figure 1B).

[0095] Regarding step 2 (drying and fixing process) In the drying step, the ink applied to the fabric is dried to remove the solvent component in the ink, thereby fixing the pigment to the fabric.

[0096] The drying method is not particularly limited and may be a method using a heater, a hot air dryer, a heating roller, etc. Among them, it is preferable to use a hot air dryer and a heater to heat and dry both sides of the fabric.

[0097] The drying temperature and drying time are preferably set to a level that allows the solvent component in the ink to evaporate while preventing the polymer particles from forming a film. Specifically, the drying temperature is preferably (Tg+50)°C (Tg means the Tg of the polymer particles) or lower. The drying temperature may be room temperature. The drying time depends on the drying temperature, but may be, for example, about 0.5 to 30 minutes.

[0098] In the present invention, the Tg of the polymer particles applied to the fabric is appropriately high, so that when the ink dries, the polymer particles are unlikely to fuse together excessively and form a film. Therefore, the gaps between the fibers are not bonded, so that the image formed is unlikely to become hard (see FIG. 1B).

[0099] Furthermore, the image forming method of the present invention may further include 3) a step of pretreating the fabric (pretreatment step), if necessary.

[0100] Regarding step 3 (pre-treatment process) In the pretreatment step, a pretreatment agent is applied to the fabric.

[0101] The type of pretreatment agent is not particularly limited and can be selected according to the composition of the ink. For example, when the ink contains an anionic dispersant, the pretreatment agent is preferably a pretreatment agent containing a compound having an acid group or a cationic group. When the ink contains a cationic dispersant, the pretreatment agent is preferably an anionic pretreatment agent containing a compound having an anionic group.

[0102] The compound having an anionic group is not particularly limited, and may be the same as an anionic surfactant, or may be a polymer compound having an anionic group, etc. Examples of the polymer compound having an anionic group include plant skins such as pectinic acid, cellulose derivatives such as carboxymethyl cellulose, processed starches such as carboxymethyl starch and carboxyethyl starch, and synthetic glues such as acrylic polymers having acrylic acid as a copolymerization component, such as acrylic acid-acrylic acid ester copolymers and styrene-acrylic acid copolymers.

[0103] The pretreatment agent may further contain, as necessary, a pH adjuster, a preservative, etc. As the preservative, the same preservatives as those exemplified for the inkjet textile printing ink can be used.

[0104] The method for applying the pretreatment agent to the fabric is not particularly limited, and may be, for example, a pad method, a coating method, a spray method, or an inkjet method.

[0105] The pretreatment agent applied to the fabric can also be heated and dried using hot air, a hot plate, or a heat roller.

[0106] In order to facilitate obtaining a uniform image, natural impurities (such as fats and oils, waxes, pectins, and natural pigments) attached to the fabric fibers, residues of chemicals used in the fabric manufacturing process (such as glues), and dirt attached to the fabric may be washed away before the pretreatment agent is applied to the fabric.

[0107] The resulting image-formed product includes a fabric and an image layer disposed on the surface thereof. The image layer includes a dried product of an ink containing pigment particles and polymer particles. In the dried product of the ink, most of the polymer particles are not coated, at least a part of the polymer particles retain their particle shape, and the fibers of the fabric are not bonded together. As a result, the image-formed product is less likely to become hard, and the texture of the fabric can be well maintained. EXAMPLES

[0108] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these.

[0109] [Example 1] 1. Ink materials (1) Preparation of anionic pigment dispersion (Preparation of anionic pigment dispersion 1) As a pigment dispersant, 7 parts by mass of styrene-butyl acrylate-methacrylic acid copolymer (anionic dispersant, weight average molecular weight 16000, anionic group equivalent 3.5meq / g) was mixed with 78 parts by mass of water, and then heated and stirred to prepare a neutralized pigment dispersant. 15 parts by mass of CI Pigment Blue 15:3 was added to this mixture, premixed, and then dispersed using a sand grinder filled with 50% by volume of 0.5mm zirconia beads to obtain a cyan pigment dispersion with a pigment concentration of 15% by mass.

[0110] (Preparation of anionic pigment dispersion 2) A cyan pigment dispersion having a pigment concentration of 15% by mass was obtained in the same manner as above, except that the pigment was changed to CI Pigment Red 122.

[0111] The average particle diameter d1 of the pigment in the pigment dispersion was measured by the following method.

[0112] (Measurement of the average pigment particle diameter d1) The average dispersed particle size (Z average) of the pigment in the obtained pigment dispersion was measured by a Zataizer NanoS90 manufactured by Melvern, and was taken as the average particle size d1.

[0113] (2) Preparation of polymer particle dispersion (Preparation of PMMA particle dispersions A1 to A3) After dissolving 50g of methyl methacrylate, 5g of methacrylic acid, 1g of ethylene glycol dimethacrylate, and 0.5g of the polymerization initiator AIBN, 500mL of water was added to a three-neck flask, and the mixture was dispersed ultrasonically and then polymerized under a nitrogen stream. After that, the mixture was neutralized, concentrated by ultrafiltration, and coarse particles were removed by centrifugation to obtain a dispersion of PMMA particles (crosslinked particles) with a solid content of 20% by mass.

[0114] The Tg of the PMMA particles in the obtained PMMA particle dispersions A1 to A3 was 100° C., the average particle diameter of A1 was 210 nm, the average particle diameter of A2 was 430 nm, and the average particle diameter of A3 was 460 nm.

[0115] (Preparation of PMMA particle dispersion A4) Concentration was carried out by polymerization / ultrafiltration in the same manner as in the preparation of PMMA particle dispersion 1 above, except that ethylene glycol dimethacrylate was not added, to obtain a dispersion of PMMA particles (non-crosslinked particles) with a solid content of 20 mass %.

[0116] (PAN particle dispersion) Aqueous dispersion of polyacrylonitrile particles (Tg: 104°C, average particle size: 180 nm)

[0117] (Polystyrene particle dispersion 1) Polystyrene particle dispersion 1 (Tg: 95° C., average particle size: 280 nm) was obtained in the same manner as polymer dispersion A1, except that methyl methacrylate was changed to styrene.

[0118] (St-Ac copolymer (styrene-acrylic copolymer) dispersion) Aqueous dispersion of styrene-methyl methacrylate-butyl methacrylate copolymer (monomer ratio: 5 / 4 / 1 (mass ratio), Tg: 90°C, average particle size: 220 nm)

[0119] (Polyurethane particle dispersion 1) Daiichi Kogyo Seiyaku Co., Ltd. Superflex 860 (Tg: 36°C, average particle size: 200 nm)

[0120] (Polyurethane particle dispersion 2) Daiichi Kogyo Seiyaku Co., Ltd. Superflex 870 (Tg: 78°C, average particle size: 30 nm)

[0121] The Tg of the polymer particles was measured by the following method.

[0122] (Tg) The polymer particles were collected from the polymer particle dispersion and dried, and the sample was subjected to differential scanning calorimetry to determine the glass transition temperature. The glass transition temperature was measured under the same conditions as above.

[0123] (Average particle diameter d2) The dispersed particle size (Z average) of the polymer particles in the polymer particle dispersion was measured by Zataizer NanoS90 manufactured by Melvern, and was taken as the average particle size d2.

[0124] In addition, these polymer particles did not have a UV absorption peak at wavelengths of 400 to 700 nm in the absorption spectrum obtained by UV-Vis spectrometry.

[0125] (3) Other ingredients Olfin E1010 (manufactured by Nissin Chemical Co., Ltd., acetylene glycol surfactant)

[0126] Proxel GXL (manufactured by Lonza Japan, preservative)

[0127] Ethylene glycol Propylene Glycol Glycerin

[0128] 2. Ink Preparation and Evaluation <Preparation of Ink 1> (Ink Preparation) Next, the following components were mixed to a total of 100 parts by mass to obtain ink 1. Anionic pigment dispersion 1 (pigment concentration 15% by mass): 6.7 parts by mass (solid content 1 part by mass) PMMA particle dispersion liquid A1 (solid content concentration 20% by mass): 45 parts by mass (solid content 9 parts by mass) Ethylene glycol: 20 parts by weight Propylene glycol: 5 parts by mass Glycerin: 5 parts by weight Olfin E1010 (acetylene glycol surfactant manufactured by Nissin Chemical Industry): 0.1 parts by mass Proxel GXL (manufactured by Lonza Japan): 0.1 parts by weight Ion-exchanged water: Remainder

[0129] The dispersed particle sizes of the polymer particles and pigment particles in the obtained ink were approximately the same as the dispersed particle sizes of the polymer particles in the polymer particle dispersion and the dispersed particle sizes of the pigment particles in the pigment dispersion.

[0130] <Preparation of Inks 2 to 16> Next, the components were mixed so as to obtain the compositions shown in Table 1, thereby obtaining inks 2 to 16.

[0131] <Image formation test> Using the resulting inks 1 to 16, an image formation test was carried out. First, an inkjet head (Konica Minolta head #204) was prepared as an image forming apparatus. Next, the inks shown in Table 1 were ejected from the nozzles of the inkjet head of the image forming apparatus to form an image on a cotton cloth as a fabric. Specifically, the image was formed in the following manner.

[0132] (Ink application process) The obtained ink was set in an image forming apparatus. A solid image was formed on the above-mentioned fabric using the obtained ink at 540 dpi in the main scanning direction and 720 dpi in the sub-scanning direction. Note that dpi refers to the number of ink droplets (dots) per 2.54 cm. The ejection frequency was 22.4 kHz.

[0133] (drying process) The fabric to which the ink was applied was dried at 120° C. for 5 minutes in a belt conveyor dryer.

[0134] <Evaluation> When an image formation test was carried out using each ink, the ejection stability (ejection property), color reproducibility and texture of the obtained image-formed product were evaluated by the following methods.

[0135] (Output stability) The resulting image was visually observed and the ejection stability was evaluated according to the following criteria. ○: The image is not blurred and appears uniform. △: Part of the image is blurred ×: There is a lot of blurring in the image. If it was △ or higher, it was considered to be within the acceptable range.

[0136] (color reproducibility) The obtained image-formed product was visually evaluated for color reproducibility according to the following criteria. ◎: Excellent color density and vividness ○: The color density is slightly low or the color vividness is slightly inferior, but it is at a good level. △: The color density is a little thin or the color vividness is a little inferior, but there is no problem in practical use. ×: The color density is low or the color is dull, to a level that is problematic for practical use. If it was △ or higher, it was considered to be within the acceptable range.

[0137] (Texture) The texture of the image-formed product and the fabric obtained was evaluated sensorily by touching with the fingers, based on the following criteria. ◎: Maintains the original softness of the fabric ○: The fabric has lost some of its original softness and become hard, but the texture of the fabric is not lost. △: The original softness of the fabric has been lost and it has become hard, but the texture of the fabric is maintained. ×: The fabric is harder than it should be, and the texture of the fabric is lost. If it was △ or higher, it was considered to be within the acceptable range.

[0138] The evaluation results of inks 1 to 16 are shown in Table 1.

[0139] [Table 1]

[0140] As shown in Table 1, when inks 1 to 7, 9 to 11, and 13 to 15 are used, which use polymer particles with a Tg of 50° C. or more and have a ratio (M2 / M1) of the polymer particle content M2 to the pigment content M1 of 3 to 19 (mass ratio), a uniform, high-density image can be formed on the surface of the fabric without impairing the texture of the fabric, and good color reproducibility can be obtained. It is also found that ejection stability (ejection property) can be maintained.

[0141] In contrast, inks 12 and 16, in which the ratio of polymer particle content M2 to pigment content M1 (M2 / M1) is less than 3 (mass ratio), do not provide sufficient image density and show poor color reproducibility. In ink 8, in which M2 / M1 exceeds 19 (mass ratio), the polymer particle content is high and the pigment particle content is too low, resulting in a decrease in overall image density. Ink 7, which contains polymer particles with a Tg of less than 50°C, shows that the texture of the resulting image formation is poor. This is thought to be because polymer particles with a Tg of less than 50°C form a film when dried, causing the image formation to harden.

[0142] [Example 2] 1. Ink materials (1) Preparation of cationic pigment dispersion (Preparation of Cationic Pigment Dispersion 1) As a pigment dispersant, 7 parts by mass of butyl acrylate-dimethylaminoethyl methacrylate copolymer (cationic dispersant, weight average molecular weight 16000, cationic group equivalent weight 4.4 meq / g) was mixed with 78 parts by mass of water, and then heated and stirred to prepare a neutralized product of the pigment dispersant. 15 parts by mass of CI Pigment Blue 15:3 was added to this mixture, premixed, and then dispersed using a sand grinder filled with 50% by volume of 0.5 mm zirconia beads to obtain a cyan pigment dispersion with a pigment concentration of 15% by mass.

[0143] (Preparation of Cationic Pigment Dispersion 1) A cyan pigment dispersion having a pigment concentration of 15% by mass was obtained in the same manner as above, except that the pigment was changed to CI Pigment Red 122.

[0144] The average particle diameter d1 of the pigment in each of the obtained pigment dispersions was measured in the same manner as above.

[0145] (2) Preparation of polymer particle dispersion (Preparation of PMMA particle dispersions C1 to C3) After dissolving 50g of methyl methacrylate, 5g of trimethylammonium ethyl methacrylate, 1g of ethylene glycol dimethacrylate, and 0.5g of polymerization initiator AIBN, 500mL of water was added to a three-neck flask, dispersed by ultrasonic waves, and polymerized under a nitrogen stream. Then, the mixture was concentrated by ultrafiltration to obtain a dispersion of PMMA particles (crosslinked particles having cationic groups) with a solid content of 20% by mass. The polymerization time was adjusted to obtain the average particle diameter d2 shown in Table 2.

[0146] (Polystyrene particle dispersion 2) Aqueous dispersion 2 of polystyrene particles (Tg: 100° C., average particle size: 180 nm) was obtained in the same manner as in the preparation of PMMA particle dispersion C1, except that styrene was used instead of methyl methacrylate.

[0147] (Polyurethane particle dispersion 3) Daiichi Kogyo Seiyaku Co., Ltd. Superflex 620 (Tg: 43°C, average particle size: 20 nm)

[0148] (Polyurethane particle dispersion 4) Daiichi Kogyo Seiyaku Co., Ltd. Superflex E4800 (Tg: -65°C, average particle size: 300 nm)

[0149] 2. Ink Preparation <Preparation of Ink 17> The following components were mixed to a total of 100 parts by mass to obtain ink 1. Cationic pigment dispersion 1 (pigment concentration 15% by mass): 6.7 parts by mass (solid content 1 part by mass) PMMA particle dispersion C1 (solid content concentration 20% by mass): 45 parts by mass (solid content 9 parts by mass) Ethylene glycol: 20 parts by weight Propylene glycol: 5 parts by mass Glycerin: 5 parts by weight Olfin E1010 (acetylene glycol surfactant manufactured by Nissin Chemical Industry): 0.1 parts by mass Proxel GXL (manufactured by Lonza Japan): 0.1 parts by weight Ion-exchanged water: Remainder

[0150] <Preparation of inks 18 to 30> Next, the components were mixed so as to obtain the compositions shown in Table 2, thereby obtaining inks 18-30.

[0151] <Image formation test and evaluation> Using the resulting inks 17 to 30, image formation tests were carried out in the same manner as above, and the same evaluations (ejection stability (ejection performance), color reproducibility and texture of the image-formed product) were carried out in the same manner as above. The results are shown in Table 2.

[0152] [Table 2]

[0153] As shown in Table 2, when inks 17-19, 23-25, and 27-29, which use polymer particles with a Tg of 50° C. or more and have a ratio (M2 / M1) of the polymer particle content M2 to the pigment content M1 of 3 to 19 (mass ratio), are used, a uniform, high-density image can be formed on the surface of the fabric without impairing the texture of the fabric, and good color reproducibility can be obtained. It is also clear that ejection stability (ejection property) can be maintained.

[0154] In contrast, inks 26 and 30, in which the ratio of polymer particle content M2 to pigment content M1 (M2 / M1) is less than 3 (mass ratio), do not provide sufficient image density and show poor color reproducibility. Also, ink 22, in which M2 / M1 is more than 19 (mass ratio), has a high polymer particle content and a too low pigment particle content, resulting in a decrease in overall image density. [Industrial Applicability]

[0155] According to the present invention, it is possible to provide an inkjet textile printing ink capable of forming an image of sufficient density without impairing the texture of the fabric. [Explanation of symbols]

[0156] 10. (Fabric) Fiber 11 Pigment particles 12 Polymer particles

Claims

1. An inkjet textile printing ink comprising a pigment, polymer particles having a glass transition temperature of 50° C. or higher, and water, a ratio M2 / M1 of the content M1 of the pigment to the content M2 of the polymer particles is 8 to 19 (mass ratio); a ratio d2 / d1 of an average particle diameter d1 of the pigment to an average particle diameter d2 of the polymer particles is 0.5 to 1.9; Inkjet textile printing ink.

2. The polymer particles are colorless. The ink-jet printing ink according to claim 1 .

3. d2 / d1 is 1.1 to 1.9; The ink-jet printing ink according to claim 1 or 2.

4. The polymer particles contain a resin selected from the group consisting of a (meth)acrylic resin and a styrene resin. The ink-jet printing ink according to any one of claims 1 to 3.

5. A portion of the resin is crosslinked. The ink-jet printing ink according to claim 4.

6. The average particle diameter d2 of the polymer particles is 80 to 400 nm. The ink-jet printing ink according to any one of claims 1 to 5.

7. A method for producing a textile printing method comprising the steps of: applying droplets of the inkjet textile printing ink according to any one of claims 1 to 6 onto a fabric by an inkjet method; Image forming method.

8. The method further comprises a step of drying the inkjet printing ink applied to the fabric at a temperature of (Tg + 50) ° C. or lower, where Tg is the glass transition temperature of the polymer particles. The image forming method according to claim 7.

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