Ink set for textile printing, image forming apparatus, and image forming method

Abstract

To provide an ink set for a printed image, capable of forming a printed image having high rubbing fastness.SOLUTION: An ink set for textile printing comprises an inkjet ink and an overcoat layer-forming liquid, wherein the volume average particle diameter of wax particles contained in the overcoat layer-forming liquid is twice or more the volume average particle diameter of fixing resin particles contained in the inkjet ink.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As a conventional textile printing method, exhaustion printing, in which a fabric is immersed in a bath filled with a dye, has been known, but this method requires a long time for dyeing, resulting in low production efficiency.In recent years, so-called inkjet printing, in which an image is formed on a fabric by an inkjet method, has become widely used because it allows dyeing in a short time and has high production efficiency.

[0003] In inkjet printing, minute droplets of ink are ejected from an inkjet recording head and landed on a fabric to form an image. For example, Patent Document 1 discloses a method for producing a textile print by such inkjet printing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-31506 Summary of the Invention [Problem to be solved by the invention]

[0005] In inkjet printing, it is desirable for the printed image formed on the fabric to have high rubbing fastness (wet rubbing fastness). If the rubbing fastness of the printed image is low, the color of the printed image will transfer when rubbed, causing color migration. To solve this problem, we investigated adding wax to the inkjet ink used to form the fixing layer of the printed image, thereby reducing the surface friction coefficient of the printed image and improving rubbing fastness.

[0006] However, when wax (wax particles) was added to the inkjet ink, the effect of reducing the surface friction coefficient was insufficient, and the abrasion resistance was also insufficient. This is presumably because even when wax particles were added to the inkjet ink, the wax particles were covered with the resin particles and pigments in the inkjet ink, and the amount of wax remaining on the surface of the printed image after the drying process was insufficient.

[0007] Furthermore, when an attempt is made to reduce the surface friction coefficient by increasing the amount of wax particles added to the inkjet ink, the wax particles inhibit the adhesion of the fixing resin particles in the inkjet ink, and the ejection properties of the inkjet ink also deteriorate.

[0008] An object of the present invention is to provide an ink set for textile printing capable of forming textile images with high abrasion fastness, an image forming apparatus having the ink set, and an image forming method using the ink set. [Means for solving the problem]

[0009] The present invention relates to the following textile printing ink set, image forming apparatus, and image forming method.

[0010] [1] A textile printing ink set comprising an inkjet ink and an overcoat layer forming liquid, wherein the volume average particle diameter of wax particles contained in the overcoat layer forming liquid is at least twice the volume average particle diameter of fixer resin particles contained in the inkjet ink. [2] The textile printing ink set according to [1], wherein the fixing resin particles have a glass transition temperature Tg of −35° C. or lower. [3] The textile printing ink set according to [1] or [2], wherein the melting point of the wax particles is 80 to 140°C. [4] The textile printing ink set according to any one of [1] to [3], wherein the wax particles contained in the overcoat layer forming liquid are 0.1% by mass to 10% by mass with respect to the overcoat layer forming liquid. [5] The textile printing ink set according to any one of [1] to [4], further comprising a pretreatment liquid containing a cationic dispersant or a cationic resin. [6] The textile printing ink set according to any one of [1] to [5], wherein the overcoat layer forming liquid contains an anionic resin. [7] An image forming apparatus having an ink storage section that stores the ink set according to any one of [1] to [6]. [8] An image forming method using the ink set according to any one of [1] to [6], comprising a step of drying the wax particles at a temperature equal to or higher than the melting point of the wax particles. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an ink set for textile printing capable of forming textile images with high abrasion fastness, an image forming apparatus having the ink set, and an image forming method using the ink set. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an image forming apparatus according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] As described above, it is difficult to improve the rub fastness of printed images even if the inkjet ink contains wax.

[0014] A textile printing ink set according to an embodiment of the present invention includes an inkjet ink and an overcoat layer-forming liquid. The inkjet ink is applied to a fabric to form a fixing layer, and the overcoat layer-forming liquid is applied to the fixing layer to form an overcoat layer. In the ink set according to this embodiment, the overcoat layer-forming liquid contains wax particles, and the volume average particle diameter of the wax particles is at least twice the volume average particle diameter of the fixing resin particles contained in the inkjet ink, thereby improving the abrasion fastness of the printed image. This is presumably because the wax particles contained in the overcoat layer-forming liquid have the above-described size, forming a wax layer on the outermost surface of the printed image, thereby reducing the surface friction coefficient (μ). Details will be described later with reference to examples.

[0015] The textile printing ink set according to this embodiment includes an inkjet ink and an overcoat layer-forming liquid. The textile printing ink set may also include a pretreatment liquid. The inkjet ink is applied to the fabric and fixed to form a fixing layer. A pretreatment liquid may be applied to the fabric before the inkjet ink is applied to the fabric. When the inkjet ink is applied on the pretreatment liquid, the fixing of the fixing layer is promoted. The overcoat layer-forming liquid is applied on the inkjet ink to form an overcoat layer. The inkjet ink, the overcoat layer forming liquid, and the pretreatment liquid will be described below.

[0016] 1-1. Inkjet ink The inkjet ink (inkjet ink for textile printing) is applied to a fabric to form a fixing layer. The inkjet ink may be applied onto a pretreatment liquid that has been applied to the fabric to form a fixing layer. When the inkjet ink is applied onto the pretreatment liquid, aggregation of the fixing resin particles is promoted by the cationic resin contained in the pretreatment liquid. This further promotes fixing of the fixing layer.

[0017] In this embodiment, the inkjet ink contains a pigment, fixing resin particles, a surfactant, and an aqueous medium. Each component will be described below. The physical properties and preparation of the inkjet ink will also be described.

[0018] (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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] Examples of black pigments include Pigment Black 7, 28, and 26.

[0024] Examples of white pigments include titanium dioxide and the like.

[0025] From the viewpoint of improving dispersibility of the pigment in the ink, it is preferable that the pigment be further dispersed with a pigment dispersant, which will be described later.

[0026] 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.

[0027] 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.

[0028] 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).

[0029] The pigment content is not particularly limited, but from the viewpoint of easily adjusting the viscosity of the inkjet ink appropriately and enabling the formation of high-density images, it is preferably 0.3 to 10% by mass, and more preferably 0.5 to 3% by mass, of the inkjet ink. When the pigment content is equal to or greater than the lower limit, the color of the image tends to be more vivid. When the pigment content is equal to or less than the upper limit, the viscosity of the inkjet ink does not become too high, and ejection stability is less likely to be impaired.

[0030] (fixing resin particles) The fixing resin particles are contained for the purpose of fixing the fixing layer to the fabric, and the fixing layer fixes the pigment as well. The fixing resin particles may be, for example, a water-dispersible resin.

[0031] From the viewpoint of improving the abrasion fastness of printed images, the volume average particle diameter of the fixer resin particles is preferably as follows in relation to the volume average particle diameter of the wax particles contained in the overcoat layer forming liquid: That is, the volume average particle diameter of the fixer resin particles is preferably half or less of the volume average particle diameter of the wax particles contained in the overcoat layer forming liquid. The volume average particle diameter of the fixer resin particles can be measured using a Zataizer Nano S90 manufactured by Melvern.

[0032] More specifically, the volume average particle diameter of the fixing resin particles is, for example, about 30 to 40 nm, or about 35 nm.

[0033] The fixing resin particles preferably have a low glass transition temperature (Tg) so that the fabric does not harden even after image formation and maintains a good texture. Specifically, the Tg of the fixing resin particles is preferably −35° C. or lower, and more preferably −35 to −70° C. The Tg of the fixing resin particles can be measured by differential scanning calorimetry in accordance with JIS K 7121 at a temperature rise rate of 10° C. / min.

[0034] The Tg of the fixing resin particles can be adjusted by the type of fixing resin particles 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.

[0035] The type of fixing resin particles is not particularly limited as long as the Tg satisfies the above range. Examples of fixing resin particles include (meth)acrylic resin, polyurethane resin, polyester resin, etc. Among them, (meth)acrylic resin and polyurethane resin are preferred from the viewpoint of having good flexibility and being able to more easily maintain the texture of the fabric. In this specification, (meth)acrylic means acrylic, methacrylic, or both.

[0036] The fixer resin particles may also have an ionic group. The ionic group possessed by the fixer resin particles may be an ionic group that forms a pair with the ionic group of the pretreatment liquid attached to the fabric. For example, since the pretreatment liquid usually has a cationic group, the fixer resin particles contained in the inkjet ink may have an anionic group. Examples of the anionic group include a carboxyl group, a sulfonic acid group, and a phosphonic acid group.

[0037] A (meth)acrylic resin is a polymer containing structural units derived from a (meth)acrylic monomer.

[0038] 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. Note that (meth)acrylic is a concept that includes both methacryl and acrylic. Among them, (meth)acrylic acid alkyl esters are preferred.

[0039] 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.

[0040] 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 includes 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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 aggregation of the fixing resin particles 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.

[0045] 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.

[0046] 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).

[0047] 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.

[0048] 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.

[0049] The polyisocyanate is preferably a diisocyanate, and examples thereof include aromatic diisocyanates such as diphenylmethane diisocyanate, for example, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and aliphatic diisocyanates such as 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] An example of a commercially available thermoplastic polyurethane product is Elastollan 1185A (manufactured by BASF, thermoplastic polyurethane elastomer, Tg: -41°C).

[0054] The acid value of the fixing resin particles is not particularly limited, but from the viewpoint of further improving the friction resistance, it is preferably 15 to 100 mgKOH / g, and more preferably 20 to 80 mgKOH / g. The acid value of the fixing resin particles can be measured in accordance with JIS K 0070.

[0055] The acid value of the fixing resin particles can be adjusted by the content of the structural unit (b). For example, the acid value increases when the content of the structural unit (b) derived from an unsaturated compound having an acidic group increases.

[0056] The weight average molecular weight Mw of the fixing resin particles is preferably high from the viewpoint of improving the texture of the printed image while improving the friction fastness, and is preferably 6×10 5 That's it, 7 x 10 5 That's it, 8 x 10 5 That's it, 10 x 10 5 That's it, 11 x 10 5 The upper limit of the weight average molecular weight Mw of the fixing resin particles is, for example, 40×10 5 or less, or 30 x 10 5 The following is fine.

[0057] From the viewpoint of improving the ejection properties of the inkjet ink, the ratio Mw / Mn of the weight-average molecular weight Mw of the fixer resin particles is preferably 5 to 20, more preferably 5 to 15, and even more preferably 5 to 12. A small Mw / Mn means a narrow molecular weight distribution, and means that there are fewer low-molecular-weight fixer resin particles (for example, monomers or oligomers). Low-molecular-weight fixer resin particles are thought to adversely affect the ejection properties of the inkjet ink for textile printing.

[0058] The method for obtaining the above-described high-molecular-weight fixing resin particles is not particularly limited, and examples thereof include a method of polymerizing a monomer with a small amount of a polymerization initiator, polymerization using a reversible addition-fragmentation chain transfer agent (RAFT polymerization), etc. RAFT polymerization is particularly useful for increasing the weight-average molecular weight Mw of the fixing resin particles while decreasing Mw / Mn, and is therefore preferred.

[0059] Examples of RAFT agents include 2-cyano-2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 4-cyano-4-dodecylsulfanylthiocarbonylsulfanylpentanoic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), bisthiobenzoyl disulfide (manufactured by Tokyo Chemical Industry Co., Ltd.), and the like.

[0060] The weight average molecular weight Mw and number average molecular weight Mn of the fixing resin particles can both be measured by gel permeation chromatography in terms of polystyrene.

[0061] The content of the fixer resin particles is not particularly limited, but is preferably 1 to 20% by mass relative to the total mass of the inkjet ink for textile printing. When the content of the fixer resin particles is 1% by mass or more, the fixation of the inkjet ink for textile printing to fabrics is more easily improved. When the content of the fixer resin particles is 20% by mass or less, the texture is less likely to be impaired. From the same viewpoint, the content of the fixer resin particles is more preferably 5 to 15% by mass relative to the total mass of the inkjet ink for textile printing.

[0062] (surfactant) The surfactant may be added mainly for the purpose of suppressing adhesion of the fixing resin particles to the nozzle surface of the recording head from which the inkjet ink is ejected. There are no particular limitations on the surfactant as long as it has affinity with the fixing resin particles. Such a surfactant is preferably a nonionic surfactant.

[0063] Nonionic surfactants are surfactants that do not contain ionic groups. Examples of nonionic surfactants include: Acetylene glycol surfactants such as acetylene glycol and ethylene oxide and / or propylene oxide adducts of acetylene glycol (for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, etc., and their ethylene oxide and / or propylene oxide adducts); Acetylenic alcohol surfactants such as acetylene alcohol, ethylene oxide and / or propylene oxide adducts of acetylene alcohol (for example, 3,5-dimethyl-1-hexane-3-ol, etc., and its ethylene oxide and / or propylene oxide adducts): Ether surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, and polyoxyalkylene alkyl ether; Ester surfactants such as polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; polyether-modified siloxane surfactants such as dimethylpolysiloxane; Examples include fluorine-containing surfactants such as fluorine alkyl esters and perfluoroalkyl carboxylates.

[0064] These surfactants may be commercially available. For example, commercially available examples of polyether-modified siloxane compounds include TEGO Wet240, TEGO WetKL245, TEGO Wet250, TEGO Wet260, TEGO Wet265, and TEGO Wet280 manufactured by Evonik Corporation, and LPX23288, LPX23289, LPX23347, BYK-348, and BYK-349 manufactured by BYK. Commercially available examples of acetylene glycol surfactants and acetylene alcohol surfactants include Olfine E1010, Olfine EXP.4036, Olfine EXP.4123, Surfynol 465, and Surfynol 485 manufactured by Nissin Chemical Industry Co., Ltd. Examples of commercially available ether surfactants include Emulgen 106 (polyoxyethylene lauryl ether) and Emulgen 709 (polyoxyethylene higher alkyl ether) manufactured by Kao Corporation, and DYNWET800 and DYNWET800N (both alcohol alkoxylates) manufactured by BYK.

[0065] Among these, acetylene glycol surfactants and acetylene alcohol surfactants are preferred, and ethylene oxide adducts of acetylene glycol are more preferred, from the viewpoint of having better affinity with water-dispersible resins and being more likely to prevent the resin from adhering to the head.

[0066] The content of the surfactant is preferably 0.1 to 10% by mass relative to the inkjet ink. When the content of the surfactant is 0.1% by mass or more, adhesion of the resin to the head is more easily suppressed. When the content of the surfactant is 10% by mass or less, the abrasion resistance of the resulting image-formed product is less likely to be impaired. From this perspective, the content of the surfactant is more preferably 0.1 to 5% by mass relative to the ink.

[0067] (aqueous medium) The aqueous medium is not particularly limited, but preferably contains water and further contains a water-soluble organic solvent.

[0068] The water content is, for example, 20 to 70% by mass, and preferably 30 to 60% by mass, based on the inkjet ink.

[0069] The water-soluble organic solvent is not particularly limited as long as it is compatible with water, but from the viewpoint of facilitating penetration of the inkjet ink into the interior of the fabric and preventing loss of ejection stability in the inkjet method, it is preferable that the inkjet ink does not easily thicken upon drying. Therefore, it is preferable that the inkjet ink contains a high-boiling point solvent with a boiling point of 200°C or higher.

[0070] The high boiling point 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.

[0071] Examples of polyols with 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).

[0072] 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, as well as ethers of trihydric or higher alcohols such as glycerin (boiling point 290°C) and hexanetriol.

[0073] The aqueous medium may further contain a solvent other than the high-boiling point solvent. Examples of the other solvent 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 alcohol, etc.); 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).

[0074] The content of the water-soluble organic solvent is, for example, 20 to 70% by mass, and preferably 30 to 60% by mass, based on the inkjet ink.

[0075] (Other ingredients) The inkjet ink may further contain other components as necessary, such as pigment dispersants, preservatives, antifungal agents, and pH adjusters.

[0076] 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, thereby dispersing the pigment well. The pigment dispersant is preferably a polymer dispersant, more preferably an anionic polymer dispersant.

[0077] 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.

[0078] 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.

[0079] From the viewpoint of sufficiently dispersing pigment particles, the anionic group equivalent of the anionic polymer dispersant 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 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.

[0080] The weight average molecular weight Mw of the polymer dispersant is not particularly limited, but is preferably 5,000 to 30,000. When the polymer dispersant has an Mw of 5,000 or more, it is easy to sufficiently disperse pigment particles, and when it is 30,000 or less, the ink does not thicken too much, so that its permeability into fabrics is less likely to be impaired. The Mw of the polymer dispersant can be measured by the same method as above.

[0081] 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 20 to 100% by mass, and more preferably 25 to 60% by mass, relative to the pigment.

[0082] 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.

[0083] Examples of pH adjusters include citric acid, sodium citrate, hydrochloric acid, and sodium hydroxide.

[0084] (Physical Properties) The viscosity of the inkjet ink at 25°C is not particularly limited as long as it provides good ejection properties using an inkjet method, but is preferably 3 to 20 mPa·s, and more preferably 4 to 12 mPa·s. The viscosity of the ink can be measured at 25°C using an E-type viscometer.

[0085] (Preparation of Inkjet Ink) The inkjet ink can be produced by any method. For example, the inkjet ink 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 with a dispersion containing the water-dispersible resin (resin particle dispersion) and an aqueous medium. The amount of adhesion of the printed image is 1 g / m 2 ~10g / m 2 3g / m 2 ~10g / m 2 More preferably, it is 3 g / m 2 ~8g / m 2 It is more preferable that:

[0086] The fabric on which the printed image is formed is not particularly limited as long as it can form a printed image. Examples of the types of fiber material constituting this fabric include 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 made from these fibers in any form, such as woven fabric, nonwoven fabric, or knitted fabric. The fabric may also be a blended woven fabric or blended nonwoven fabric of two or more types of fibers. The fabric is preferably, for example, cotton satin.

[0087] As described above, the printed image product according to the present embodiment has a printed image formed on a fabric. The printed image may have a pretreatment layer, a fixing layer, and an overcoat layer.

[0088] 1-2. Pretreatment solution The pretreatment liquid can be used to further promote the fixation of the fixation layer formed by the inkjet ink. Specifically, the pretreatment liquid contains a cationic dispersant or a cationic resin, and the cationic dispersant or cationic resin promotes aggregation of fixation resin particles and pigment in the inkjet ink to promote the fixation of the fixation layer. When a pretreatment liquid is used, the pretreatment liquid is first applied to the fabric. The pretreatment liquid applied to the fabric becomes the pretreatment layer.

[0089] The weight-average molecular weight Mw of the cationic resin is preferably 1,000 or more from the viewpoint of suppressing stickiness of the printed image. On the other hand, the upper limit of the weight-average molecular weight of the cationic resin is preferably 10,000 or less from the viewpoint of dispersibility in the pretreatment liquid. In other words, the weight-average molecular weight of the cationic resin is preferably 1,000 to 10,000. The weight-average molecular weight Mw of the cationic resin can be measured by gel permeation chromatography in terms of polystyrene.

[0090] Examples of cationic resins include polyamines, diallylamine hydrochloride polymers, diallylamine polymers, methyldiallylamine hydrochloride polymers, methyldiallylamine amidosulfate polymers, methyldiallylamine acetate polymers, diallyldimethylammonium chloride polymers, diallylmethylethylammonium ethylsulfate polymers, amine-epichlorohydrin condensation polymers, poly-2-hydroxypropyldimethylammonium chloride, dimethylamine-ethylenediamine-epichlorohydrin condensates, dimethylamine-ammonia-epichlorohydrin condensates, and the like.

[0091] 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.

[0092] The content of the cationic resin is preferably 0.1% by mass to 10% by mass relative to the total mass of the pretreatment liquid.

[0093] The method for applying the pretreatment liquid is not particularly limited and may be, for example, a pad method, a coating method, a spray method, an inkjet method, etc. The pretreatment liquid applied to the fabric may be heated and dried using hot air, a hot plate, or a heat roller.

[0094] 1-3. Overcoat layer forming liquid The overcoat layer-forming liquid is applied onto the pretreatment liquid and inkjet ink applied to the fabric. The overcoat layer-forming liquid applied to the fabric forms an overcoat layer. The overcoat layer can reduce the surface friction coefficient of the printed image.

[0095] The overcoat layer-forming liquid contains wax particles. The volume-average particle diameter of the wax particles may be at least twice, but may also be at least 2.5 times, at least 3 times, or at least 3.5 times, the volume-average particle diameter of the fixer resin particles contained in the inkjet ink. The upper limit of the volume-average particle diameter of the wax particles is not particularly limited, but is, for example, 10 times or less, or 5 times or less. As described above, it is presumed that when the wax particles contained in the overcoat layer-forming liquid are larger than the fixer resin particles in the inkjet ink, a wax layer is formed on the outermost surface of the printed image, reducing the surface friction coefficient (μ) of the printed image and improving the abrasion fastness of the printed image. More specifically, the volume average particle diameter of the wax particles contained in the overcoat layer-forming liquid is, for example, 80 nm or more, 90 nm or more, or 100 nm or more. The upper limit of the volume average particle diameter of the wax particles is not particularly limited, but is, for example, 350 nm or less, 200 nm or less, 190 nm or less, or 180 nm or less.

[0096] The volume average particle size of the wax particles can be measured using a Zataizer Nano S90 manufactured by Melvern.

[0097] The melting point of the wax particles contained in the overcoat layer-forming liquid is preferably equal to or lower than the drying temperature described in the method for forming a printed image, which will be described later. When the melting point of the wax particles is equal to or lower than the drying temperature, the wax particles melt, forming a wax layer on the surface of the printed image, which is thought to reduce the surface friction coefficient of the printed image and improve the abrasion fastness. The melting point of the wax particles contained in the overcoat layer-forming liquid is, for example, about 80°C to 140°C, or 85°C to 135°C.

[0098] Examples of wax particles include polyolefin wax particles, polyethylene wax particles, modified polyethylene wax particles, and the like.

[0099] The overcoat layer forming liquid may contain anionic resin particles (anionic resin). The amount of anionic resin particles added to the overcoat layer forming liquid is, for example, 15% or less in terms of the total solid content of the overcoat layer forming liquid. The volume average particle diameter of the anionic resin particles can be measured using a Zataizer Nano S90 manufactured by Melvern.

[0100] The anionic resin particles preferably have a glass transition temperature Tg of 50° C. or higher, more preferably 100° C. or higher. The glass transition temperature Tg of the anionic resin particles can be measured by differential scanning calorimetry in accordance with JIS K 7121 at a temperature rise rate of 10° C. / min.

[0101] Examples of anionic resin particles include polymer particles having functional groups capable of carrying a negative charge, such as carboxyl groups, hydroxyl groups, and sulfate groups.

[0102] Examples of commercially available anionic resin particles include AQUACER 507 manufactured by BYK and Hitec E-4A manufactured by Toho Chemical Industry Co., Ltd.

[0103] The content of the anionic resin particles in the overcoat layer forming liquid is preferably 2% by mass to 6% by mass, and more preferably about 4% by mass.

[0104] The overcoat layer forming liquid may contain a fixing resin, which may be the same as the fixing resin contained in the inkjet ink.

[0105] The method for applying the overcoat layer forming liquid is not particularly limited and may be, for example, a pad method, a coating method, a spray method, an inkjet method, etc. The overcoat layer forming liquid applied to the fabric may be heated and dried using hot air, a hot plate, or a heat roller.

[0106] 2. Image forming apparatus and image forming method 2-1. Image forming device An image forming apparatus used to form a textile image according to the present invention will be outlined below.

[0107] 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, an ink storage section 110b, an overcoat layer forming liquid storage section 110c, a recording head 120, a head carriage 130, a drying section 140, and a transport section 150.

[0108] The pretreatment liquid storage section 110a, the ink storage section 110b, and the overcoat layer forming liquid storage section 110c store a pretreatment liquid a, an inkjet ink b, and an overcoat layer forming 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 a transport section 150.

[0109] The pretreatment liquid storage section 110a, the ink storage section 110b, and the overcoat layer forming liquid storage section 110c supply the pretreatment liquid a, the inkjet ink b, and the overcoat layer forming liquid c to the recording heads 120 connected to them, and the recording heads 120 eject the pretreatment liquid a, the inkjet ink b, and the overcoat layer forming liquid c onto the fabric 160, respectively, to form a printed image.

[0110] A plurality of ink containing sections 110b and recording heads 120 may be arranged, for example, for each ink color.

[0111] 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 ink containing section 110b or may move separately.

[0112] 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.

[0113] 2-2. Image forming method Next, a method for producing a printed image product will be specifically described with reference to Fig. 1. The method for producing a printed image product according to this embodiment includes the steps of: 1) ejecting a pretreatment liquid, an inkjet ink, and an overcoat layer-forming liquid onto a fabric in this order from the recording heads 120 to adhere them to the fabric; and 2) drying the fabric to which the liquids have been adhered at a temperature higher than the melting point of wax particles contained in the overcoat layer.

[0114] Step 1) First, a pretreatment liquid, an inkjet ink, and an overcoat layer forming liquid are ejected in this order from each recording head 120 to form a pretreatment on the fabric 160 moving in the transport direction Y, a fixing layer is formed thereon, and an overcoat layer is formed thereon to form a printed image.

[0115] Step 2) Next, the printed image formed on the fabric 160 is dried in the drying section 140 to remove the solvent component in the ink, thereby fixing the pigment to the fabric 160. In this way, a printed image is obtained.

[0116] The drying method is not particularly limited, and may be a method using a heater, a hot air dryer, a heated roller, etc. In this embodiment, it is preferable that the drying unit 140 uses a hot air dryer and a heater to heat and dry both sides of the fabric.

[0117] The drying temperature is preferably higher than the melting point of the wax particles in the overcoat layer-forming liquid in order to melt the wax particles. Furthermore, the drying temperature is preferably high enough to volatilize the solvents contained in each liquid to some extent. From these viewpoints, the drying temperature may be, for example, about 85 to 160°C. In the present embodiment, the drying temperature is 150°C. [Example]

[0118] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0119] Example 1 The pretreatment liquid, inkjet ink, and overcoat layer-forming liquid used to obtain the printed image of Example 1 were prepared as follows.

[0120] 1-1. Pretreatment solution The pre-treatment liquid was obtained by mixing the following components in the following proportions, with the mass of the pre-treatment liquid being 100 parts by mass. As a cationic resin, PAS-H-1L (manufactured by Nitto-Beau Medical Co., Ltd.): 4.7 parts by mass Ethylene glycol: 10 parts by mass Propylene glycol: 10 parts by mass Glycerin: 10 parts by mass: Surfactant E-1010: 0.1 parts by mass Proxel GXL (manufactured by Lonza Japan, 1,2-benzisothiazolin-3-one, antifungal agent): 0.10 parts by mass Ion-exchanged water: Remaining

[0121] 1-2. Inkjet ink The inkjet ink contains a pigment (pigment dispersion), fixing resin particles, a surfactant, a water-soluble organic solvent, and an antifungal agent. Each of these components was prepared as follows.

[0122] A neutralized pigment dispersant was prepared by mixing 7 parts of styrene-butyl acrylate-methacrylic acid copolymer (anionic dispersant, weight-average molecular weight 16,000, anionic group equivalent weight 3.5 meq / g) with 78 parts of water and warming and stirring. To this mixture was added 15 parts of CI Pigment Blue 15:3, premixed, and dispersed using a sand grinder filled with 50% 0.5 mm zirconia beads to obtain a cyan pigment dispersion with a pigment concentration of 15% by volume. As the surfactant, E-1010 (manufactured by Nissin Chemical Industry Co., Ltd.) was used. As the water-soluble organic solvents, ethylene glycol (boiling point 197°C), glycerin (boiling point 290°C), and propylene glycol (boiling point 188°C) were used. Proxel GXL (Lonza Japan, 1,2-benzisothiazolin-3-one) was used as the fungicide.

[0123] The fixing resin particles used were polyurethane resin (Takelac WS-5000, Tg: 65° C., manufactured by Mitsui Chemicals, Inc.) The volume average particle diameter of the polyurethane resin was measured with a Zataizer Nano S90 manufactured by Melvern and was found to be 35 nm.

[0124] The glass transition temperature Tg of the fixing resin particles can be measured by differential scanning calorimetry using a DSC600 manufactured by Hitachi High-Tech Corporation, in accordance with JIS K7121, at a temperature gradient of 10° C. / min.

[0125] The inkjet ink was obtained by mixing the above components in the following proportions, with the mass of the inkjet ink being 100 parts by mass. Pigment dispersion: 10 parts by weight (pigment concentration 15% by weight, solid content concentration 1.5 parts by weight) Fixing resin particles: 10 parts by mass Ethylene glycol: 10 parts by mass Propylene glycol: 10 parts by mass Glycerin: 10 parts by mass: Surfactant: 0.5 parts by mass Proxel GXL (manufactured by Lonza Japan, 1,2-benzisothiazolin-3-one, antifungal agent): 0.10 parts by mass Ion-exchanged water: Remaining

[0126] 1-3. Overcoat layer forming liquid The overcoat layer forming liquid was obtained by mixing the following components in the following proportions, with the mass of the overcoat layer forming liquid being 100 parts by mass. As a drug containing wax particles, AQUACER 531 (manufactured by BYK): 10 parts by mass Ethylene glycol: 10 parts by mass Propylene glycol: 10 parts by mass Glycerin: 10 parts by mass: Surfactant E-1010: 0.1 parts by mass Proxel GXL (manufactured by Lonza Japan, 1,2-benzisothiazolin-3-one, antifungal agent): 0.10 parts by mass Ion-exchanged water: Remaining

[0127] 2.Textile printing image formation Cotton satin (100% cotton: product name 60 Cotton Satin, manufactured by Okadaya Co., Ltd.) was prepared as the fabric. The above-mentioned pretreatment liquid, inkjet ink, and overcoat layer forming liquid were applied to this cotton satin by inkjet printing, and then dried to obtain a printed image. A Konica Minolta head #204 was used as the recording head. The pretreatment liquid, inkjet ink, and overcoat layer forming liquid were ejected from the recording head at a main scanning speed of 540 dpi and a sub-scanning speed of 720 dpi. dpi represents the number of ink droplets (dots) per 2.54 cm. The ejection frequency was 22.4 kHz. The fabric was then dried at 150°C for 5 minutes in a belt-conveying dryer to obtain a printed image. The deposition mass of the pretreatment layer, fixing layer, and overcoat layer was 1 g / m. 2 , 6g / m 2 , 3g / m 2 This amount of adhesion was calculated from the amount of ink ejected.

[0128] 3. Evaluation The rub fastness, texture, and ejection properties were evaluated as follows.

[0129] (Rubbing resistance) The resulting image-formed product was subjected to a dry rub fastness test using a Type II testing machine under the drying conditions of JIS L0849 (2013), and evaluated using a discoloration gray scale. Specifically, the image-formed area was rubbed 100 times with a cotton cloth over an area of ​​100 mm in both the horizontal and vertical directions with a load of 200 g. After rubbing, the color density of the cotton cloth was evaluated using a grade corresponding to the same density on the discoloration gray scale. Note that the higher the grade, the better the rub fastness. ○: 4-5 grade ~ 5 grade △:3-4 grade~4 grade ×: 2-3 grade ~ 3 grade

[0130] (Dischargeability) The textile inkjet ink was ejected using a line method on a fixed Konica Minolta KM1024iMHE printer under ejection conditions of a droplet volume of 13 pL. After confirming that the filled ink was being ejected from all 60 nozzles at the start of ejection, the ink was ejected continuously for 60 minutes. After the 60 minutes of continuous ejection was completed, the number of nozzles that had been able to eject to the end (the number of ejecting nozzles after 60 minutes of continuous ejection) was counted. The number of ejecting nozzles after 60 minutes of continuous ejection was applied to the following evaluation criteria to evaluate the ink ejection properties. ○: No white deposits on the inkjet head, and the number of ejecting nozzles after 60 minutes of continuous ejection is 60 or more △: There is no white deposit on the inkjet head, but the number of ejecting nozzles after 60 minutes of continuous ejection is 54 to 59 ×: White deposits are found on the inkjet head, and the number of ejecting nozzles after 60 minutes of continuous ejection is 53 or less.

[0131] The evaluation results are shown in Table 1.

[0132] (Examples 2 to 5, Comparative Examples 1 to 6) In Examples 2 to 5 and Comparative Examples 1 to 6, the overcoat layer forming liquid or inkjet ink was prepared in the same manner as in Example 1, except that the composition of the overcoat layer forming liquid or inkjet ink was changed as shown in Table 1.

[0133] In Example 2, AQUACER-531 was contained in an amount of 5 parts by mass (5% by mass) based on 100 parts by mass of the overcoat layer forming liquid, which was higher than in Example 1. In Example 3, 3% by mass of a polyurethane resin (Takelac WS-5000, manufactured by Mitsui Chemicals, Inc., Tg: 65° C.) was added as fixing resin particles to the overcoat layer forming liquid. In Example 4, Hitec E-6314 (manufactured by Toho Chemical Industry Co., Ltd., volume average particle size 180 nm, melting point 137° C.) was used in place of AQUACER-531. In Example 5, AQUACER-539 (manufactured by BYK, volume average particle size 90 nm, melting point 90° C.) was used instead of AQUACER-531.

[0134] In Comparative Example 1, the overcoat layer forming liquid did not contain wax particles. In Comparative Example 2, the inkjet ink did not contain fixing resin particles. In Comparative Example 3, the overcoat layer forming liquid did not contain wax particles, but instead the inkjet ink contained 1 part by mass (1% by mass) of AQUACER-531 per 100 parts by mass of the inkjet ink. In Comparative Example 4, the overcoat layer forming liquid did not contain wax particles, but instead the inkjet ink contained 10 parts by mass (10% by mass) of AQUARCER-531 per 100 parts by mass of the inkjet ink. In Comparative Example 5, the printed image was obtained by drying at 120°C for 5 minutes instead of at 150°C for 5 minutes. In Comparative Example 6, AQUACER-507 (manufactured by BYK, volume average particle size 50 nm, melting point 130° C.) was used instead of AQUACER-531.

[0135] [Table 1]

[0136] As shown in Table 1, both the rub fastness and the jetting property were good in Examples 1 to 5, whereas the rub fastness was poor in Comparative Example 6. This is because the volume average particle diameter of the wax particles contained in the overcoat layer-forming liquid in Examples 1 to 5 was at least twice the volume average particle diameter of the fixing resin particles contained in the inkjet ink, whereas it was less than twice that in Comparative Example 6. That is, it is presumed that the wax particles contained in the overcoat layer-forming liquid in Examples 1 to 5 were sufficiently large, which made it easy for a wax layer to be formed on the surface of the printed image after drying, resulting in good rub fastness.

[0137] Comparing Example 1 and Comparative Example 1, the overcoat layer-forming liquid in Comparative Example 1 did not contain wax particles and had poor rub fastness. This shows that in order to improve rub fastness, it is necessary to include wax particles in the overcoat layer-forming liquid.

[0138] Comparing Example 1 and Comparative Example 2, the inkjet ink in Comparative Example 2 did not contain fixing resin particles, and the abrasion fastness was poor. This shows that in order to improve the abrasion fastness, it is necessary for the inkjet ink to contain fixing resin particles.

[0139] Comparing Example 1 and Comparative Example 3, the overcoat layer-forming liquid in Comparative Example 3 did not contain wax particles, but instead the inkjet ink contained 1% by mass of wax particles. Comparative Example 3 had poor rub fastness. This shows that adding a small amount of wax particles to the inkjet ink in an attempt to improve rub fastness does not result in good rub fastness. This is presumably because even if a small amount of wax particles is added to the inkjet ink, the wax particles are covered with the resin particles and pigment in the inkjet ink, and the amount of wax present on the surface of the printed image after drying is insufficient.

[0140] Comparing Comparative Example 3 and Comparative Example 4, the inkjet ink in Comparative Example 4 contains 10% by mass of wax particles relative to the inkjet ink. Although the inkjet ink in Comparative Example 4 has good rub fastness, the ejection performance is poor. These findings demonstrate that adding wax to the inkjet ink to improve rub fastness results in poor ejection performance.

[0141] From the above, it was found that when wax particles are contained in the overcoat forming solution, even a small amount can improve the abrasion resistance.

[0142] Comparing Example 1 and Comparative Example 5, the drying temperature in the Comparative Example was low at 120°C, resulting in poor rub fastness. This is thought to be because the drying temperature in Comparative Example 5 was lower than the melting point of the wax particles, so a wax layer was not formed on the surface of the printed image. Therefore, it was found that the melting point of the wax particles contained in the overcoat layer-forming liquid is preferably equal to or lower than the drying temperature. It was also found that the drying temperature is preferably equal to or higher than the melting point of the wax particles. [Industrial Applicability]

[0143] According to the present invention, it is possible to obtain an ink set that has good rub fastness and good jetting properties. Therefore, the present invention is expected to broaden the scope of textile printing image formation technology and contribute to the advancement and spread of technology in this field. [Explanation of symbols]

[0144] 100 Image forming device 110a Pretreatment liquid storage section 110b Ink storage section 110c Overcoat layer forming liquid storage section 120 recording head 130 Head Carriage 140 Drying section 150 Conveyor 160 Fabric a Pretreatment solution b. Inkjet ink c. Overcoat layer forming liquid Y conveying direction

Claims

1. A textile printing ink set comprising an inkjet ink and an overcoat layer forming liquid, the volume average particle diameter of the wax particles contained in the overcoat layer forming liquid is at least twice the volume average particle diameter of the fixing resin particles contained in the inkjet ink; Ink set for textile printing.

2. 2. The textile printing ink set according to claim 1, wherein the fixing resin particles have a glass transition temperature of −35° C. or lower.

3. 2. The textile printing ink set according to claim 1, wherein the wax particles have a melting point of 80 to 140°C.

4. 2. The textile printing ink set according to claim 1, wherein the wax particles contained in the overcoat layer forming liquid are 0.1% by mass to 10% by mass with respect to the overcoat layer forming liquid.

5. The textile printing ink set according to claim 1 , further comprising a pretreatment liquid containing a cationic dispersant or a cationic resin.

6. The textile printing ink set according to claim 1 , wherein the overcoat layer forming liquid contains an anionic resin.

7. An image forming apparatus having an ink storage section that stores the textile printing ink set according to any one of claims 1 to 6.

8. 7. An image forming method using the ink set according to claim 1, comprising a step of drying at a temperature equal to or higher than the melting point of the wax particles.

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