Pretreatment agent for inkjet textile printing, ink set for inkjet textile printing, and inkjet textile printing method

Abstract

This pretreatment agent for inkjet textile printing contains an N-vinylformamide-based cationic polymer having, as a constituent unit, at least one selected from the group consisting of a constituent unit represented by formula (1), a constituent unit that is a salt thereof, and a constituent unit represented by formula (2). The weight average molecular weight of the N-vinylformamide-based cationic polymer is 100,000 or less.

Description

Pretreatment agent for inkjet textile printing, ink set for inkjet textile printing, and inkjet textile printing method

[0001] The present invention relates to a pretreatment agent for inkjet textile printing. The present invention also relates to an inkjet textile printing ink set containing the pretreatment agent for inkjet textile printing, and an inkjet textile printing method using the pretreatment agent for inkjet textile printing.

[0002] Compared to conventional methods using plates, inkjet printing has the advantages of eliminating the need for plate cleaning or storage, being easily applicable to a wide variety of products, and shortening delivery times. However, inkjet printing requires expensive equipment and ink, and a pretreatment process. Patent Documents 1 to 3 disclose techniques in which a pretreatment agent is applied to fabric and then dried, followed by inkjet printing. Patent Documents 4 and 5 disclose techniques in which a pretreatment agent is applied to fabric and then inkjet printing is performed without drying.

[0003] Japanese Patent Laid-Open No. 11-302987 Japanese Patent Laid-Open No. 2003-3385 ​​Japanese Patent Laid-Open No. 9-279487 Japanese Patent Laid-Open No. 2017-530269 Japanese Patent Laid-Open No. 2016-089288

[0004] In the methods of applying a pretreatment agent as described in Patent Documents 1 to 3, the viscosity of the pretreatment agent used must be high to prevent bleeding during printing, making inkjet application of the pretreatment agent difficult. Furthermore, in Patent Documents 1 to 3, the pretreatment agent is dried after application, but this requires space for installing a dryer, as well as the energy and cost required for drying, resulting in lower productivity compared to methods that do not involve drying. For this reason, there is a demand for inkjet printing (textile printing) that does not require drying after application of the pretreatment agent. However, methods such as those described in Patent Documents 4 and 5 that do not require drying after application have problems such as ink bleeding due to capillary action and poor ink penetration into the interior of the fabric.

[0005] As a result of investigations by the present inventors, it was found that by using a specific cationic polymer in a pretreatment agent, the cationic polymer attracts the negatively charged dye during printing without drying, allowing the dye to be fixed at the desired position and preventing bleeding. However, it was also found that in this case, the texture of the resulting printed textile may be insufficient.

[0006] An object of the present invention is to provide a pretreatment agent for inkjet textile printing that contains a cationic polymer and enables inkjet printing without drying after application of the pretreatment agent, thereby achieving improved productivity, cost reduction, energy savings, and space savings, and that enables printed textiles with a good texture to be obtained. Another object of the present invention is to provide an inkjet textile printing ink set that contains this pretreatment agent for inkjet textile printing, and an inkjet textile printing method that uses this pretreatment agent for inkjet textile printing.

[0007] The present inventors have investigated specific cationic polymers and found that when the polymer contains specific structural units and has a molecular weight of a predetermined value or less, inkjet printing can be performed on pretreated fabric without drying it, bleeding can be prevented, and printed fabrics with a good texture can be obtained.

[0008] The present invention has the following aspects.

[0009] [1] A pretreatment agent for inkjet textile printing, comprising an N-vinylformamide cationic polymer having, as a structural unit, at least one structural unit selected from the group consisting of a structural unit represented by the following formula (1) and a salt thereof, and a structural unit represented by the following formula (2), wherein the weight-average molecular weight of the N-vinylformamide cationic polymer is 100,000 or less.

[0010]

[0011] [2] The pretreatment agent for ink-jet textile printing according to [1], which satisfies the relationship of the following formula (I), where X is the weight-average molecular weight (Mw) of the N-vinylformamide cationic polymer and Y (meq / g) is the cationic degree of the N-vinylformamide cationic polymer: 150<(X×Y) / 1000<1200 (I)

[0012] [3] The pretreatment agent for inkjet textile printing according to [1] or [2], wherein the cationic degree of the N-vinylformamide cationic polymer is 2.0 meq / g or more and 15.0 meq / g or less.

[0013] [4] The pretreatment agent for inkjet textile printing according to any one of [1] to [3], wherein the cationic degree of the N-vinylformamide cationic polymer is 6.0 meq / g or less.

[0014] [5] The pretreatment agent for inkjet textile printing according to any one of [1] to [3], wherein the cationic degree of the N-vinylformamide cationic polymer is 7.0 meq / g or more.

[0015] [6] The pretreatment agent for inkjet textile printing according to any one of [1] to [5], wherein the N-vinylformamide cationic polymer contains the structural unit represented by formula (1) and the structural unit that is a salt thereof in an amount of 20 mol % to 80 mol %.

[0016] [7] The pretreatment agent for inkjet textile printing according to any one of [1] to [6], wherein the weight-average molecular weight of the N-vinylformamide cationic polymer is 90,000 or less.

[0017] [8] The pretreatment agent for inkjet textile printing according to any one of [1] to [7], wherein the weight-average molecular weight of the N-vinylformamide cationic polymer is 20,000 or more.

[0018] [9] The inkjet printing pretreatment agent according to any one of [1] to [8], further comprising a moisturizer.

[0019]

[10] The inkjet printing pretreatment agent according to any one of [1] to [9], further comprising a defoaming agent.

[0020]

[11] The pretreatment agent for inkjet textile printing according to any one of [1] to

[10] , wherein a content of the N-vinylformamide cationic polymer is 0.5% by mass or more and 3.0% by mass or less, based on 100% by mass of the total mass of the pretreatment agent for inkjet textile printing.

[0021]

[12] The pretreatment agent for inkjet textile printing according to any one of [1] to

[11] , wherein the N-vinylformamide cationic polymer contains at least one selected from the group consisting of polyamidines and polyvinylamines.

[0022]

[13] The pretreatment agent for inkjet textile printing according to any one of [1] to

[12] , wherein the N-vinylformamide cationic polymer further comprises, as a structural unit, a structural unit represented by the following formula (3) or a salt thereof:

[0023]

[0024]

[14] An ink set for inkjet textile printing, comprising the inkjet textile printing pretreatment agent according to any one of [1] to

[13] and a water-based ink.

[0025]

[15] The ink set for inkjet textile printing according to

[14] , wherein the water-based ink contains a disperse dye or a reactive dye.

[0026]

[16] An inkjet textile printing method comprising: a pretreatment step of pretreating a fabric with a pretreatment agent for inkjet textile printing, the pretreatment agent including an N-vinylformamide cationic polymer having a weight-average molecular weight of 100,000 or less, the N-vinylformamide cationic polymer having, as a structural unit, at least one structural unit selected from the group consisting of a structural unit represented by the following formula (1) and a salt thereof, and a structural unit represented by the following formula (2):

[0027]

[0028]

[17] The inkjet textile printing method according to

[16] , wherein in the pretreatment step, the inkjet textile printing pretreatment agent is ejected onto the fabric by inkjet printing.

[0029]

[18] The inkjet textile printing method according to

[16] or

[17] , wherein the printing step includes inkjet printing the aqueous ink by a wet-on-wet method onto the pretreated area of ​​the fabric pretreated in the pretreatment step.

[0030]

[19] The inkjet printing method according to any one of

[16] to

[18] , wherein the colorant is a disperse dye or a reactive dye.

[0031]

[20] The inkjet printing method according to any one of

[16] to

[19] , wherein the fabric is a fabric containing cotton or polyester fibers.

[0032] According to the pretreatment agent for inkjet textile printing and the ink set for inkjet textile printing of the present invention, in inkjet textile printing of fabric, the fabric that has been pretreated after application of the pretreatment agent can be inkjet printed without drying, thereby preventing bleeding and providing a printed textile with a good texture.

[0033] According to the inkjet printing method of the present invention, inkjet printing can be performed on a fabric that has been pretreated after application of a pretreatment agent without drying, thereby obtaining a printed fabric that is free from bleeding and has a good texture.

[0034] The inkjet printing pretreatment agent of the present invention (hereinafter also referred to simply as "pretreatment agent") will be described in detail below. The following explanation of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, when "X to Y" (X and Y are any numbers) is expressed, it means "X or more and Y or less" unless otherwise specified, and also includes the meaning "preferably larger than X" or "preferably smaller than Y." Furthermore, when "X or more" (X is any number) or "Y or less" (Y is any number) is expressed, it also includes the meaning "preferably larger than X" or "preferably smaller than Y."

[0035] [Pretreatment Agent] The pretreatment agent for inkjet textile printing of the present invention is characterized by having at least one structural unit selected from the group consisting of a structural unit represented by the following formula (1) and a structural unit that is a salt thereof (hereinafter, these may be referred to as "structural unit (1)") and a structural unit represented by the following formula (2) (hereinafter, may be referred to as "structural unit (2)"), and containing an N-vinylformamide-based cationic polymer having a weight-average molecular weight of 100,000 or less (hereinafter, may be referred to as the "N-vinylformamide-based cationic polymer of the present invention").

[0036]

[0037] In the pretreatment agent of the present invention, the N-vinylformamide-based cationic polymer attracts the negatively charged dye, allowing the dye to be fixed at the desired position and preventing bleeding. However, the N-vinylformamide-based cationic polymer is not washed away during the washing process and remains in the fibers, which causes the texture of the printed textile to deteriorate. The present inventors conducted various studies on the washability of N-vinylformamide-based cationic polymers and found that by adjusting the weight-average molecular weight of the N-vinylformamide-based cationic polymer to 100,000 or less, the polymer is washed away during the washing process, resulting in printed textiles with a good texture.

[0038] Furthermore, cationic polymers have the effect of enhancing the adhesion of ink to fabrics, and this effect of enhancing ink adhesion is related to the level of cationicity. Cationic polymers are typically polymers containing cationic nitrogen atoms in the molecule, and exhibit cationicity when the nitrogen atoms are quaternized and charged. The N-vinylformamide-based cationic polymer of the present invention has a structure in which nitrogen atoms are directly bonded to the main chain of the polymer by having either the structural unit (1) or the structural unit (2). As a result, the cationic functional groups resulting from the nitrogen atoms are close to the main chain, increasing the cation density, and the cationic polymers are more strongly attracted to each other, exhibiting a high coagulation effect. This is believed to enable the dye to be firmly fixed at the desired location and to efficiently suppress bleeding.

[0039] The pretreatment agent of the present invention may further contain a moisturizing agent and an antifoaming agent. The pretreatment agent of the present invention may contain optional components such as an organic solvent other than water and the moisturizing agent.

[0040] <Flocculant> The pretreatment agent of the present invention contains an N-vinylformamide cationic polymer. The N-vinylformamide cationic polymer acts as a flocculant, that is, has the ability to flocculate dyes.

[0041] The pretreatment agent of the present invention may contain a flocculant other than an N-vinylformamide-based cationic polymer. In this case, the flocculant is not particularly limited as long as it has the effect of flocculating the dye, and examples of the flocculant include organic acids, polyvalent metal salts, cationic low-molecular-weight compounds, and cationic polymers other than N-vinylformamide-based cationic polymers.

[0042] Examples of organic acids include formic acid, acetic acid, propionic acid, butyric acid, tartaric acid, citric acid, and lactic acid.

[0043] The polyvalent metal salt may be a compound composed of a divalent or higher metal ion and an anion. Examples of the divalent or higher metal ion include calcium, magnesium, aluminum, titanium, strontium, and iron ions. Examples of the anion include chloride ions, bromide ions, nitrate ions, sulfate ions, carbonate ions, and hydroxide ions.

[0044] Examples of cationic low molecular weight compounds include (2-hydroxyethyl)trimethylammonium chloride, benzoylcholine chloride, benzyltriethylammonium chloride, trimethylacetohydrazide ammonium chloride, 1-butyl-1-methylpyrrolidinium chloride, 3-hydroxy-4-(trimethylammonio)butyrate hydrochloride, glycidyltrimethylammonium chloride, and L-carnitine hydrochloride.

[0045] Examples of cationic polymers other than N-vinylformamide-based cationic polymers include polydiallyldimethylammonium chloride, polyallylamine or its derivatives, amine-epihalohydrin copolymers, and other quaternary ammonium salt-type cationic polymers.

[0046] (N-vinylformamide-Based Cationic Polymer) The N-vinylformamide-based cationic polymer of the present invention included in the pretreatment agent of the present invention is a cationic polymer obtained by polymerization using N-vinylformamide, and has, as an essential structural unit, at least one structural unit selected from the group consisting of a structural unit represented by the following formula (1) and a salt thereof (structural unit (1)), and a structural unit represented by the following formula (2) (structural unit (2)):

[0047]

[0048] In the N-vinylformamide-based cationic polymer of the present invention, the content of the structural unit (1) is preferably 1 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, and even more preferably 30 mol% or more, with 40 mol% or more being preferred, and 50 mol% or more being particularly preferred, when the total molar number of all structural units contained in the N-vinylformamide-based cationic polymer is taken as 100 mol%. Having a content of the structural unit (1) equal to or greater than the above-mentioned lower limit can efficiently suppress bleeding. On the other hand, having a content of the structural unit (1) of 95 mol% or less, when the total molar number of all structural units contained in the N-vinylformamide-based cationic polymer of the present invention is taken as 100 mol%, can facilitate removal from fabrics in the washing step described below, allowing for the production of printed textiles with excellent texture. Furthermore, the synthesis of the pretreatment agent is easily controlled, resulting in a highly stable product. From this viewpoint, the content of the structural unit (1) in the N-vinylformamide-based cationic polymer of the present invention is more preferably 93 mol % or less, even more preferably 90 mol % or less, even more preferably 88 mol % or less, and particularly preferably 86 mol % or less.

[0049] When this pretreatment agent is used in inkjet printing using a reactive dye, the active groups in the reactive dye neutralize the cationic functional groups in the cationic polymer, reducing the amount of cations and tending to result in insufficient dye agglomeration performance of the pretreatment agent. From the viewpoint of ensuring excellent performance of the pretreatment agent even with reactive dyes, the content of structural unit (1) is preferably 50 mol% or more, more preferably 60 mol% or more. The above-mentioned preferred upper and lower limits can be combined in any desired manner.

[0050] When two or more types of N-vinylformamide-based cationic polymers are used, the content of the structural unit (1) in a mixture of two or more types of N-vinylformamide-based cationic polymers is calculated as a proportion when the total number of moles of all structural units contained in the N-vinylformamide-based cationic polymer mixture is taken as 100 mol %.

[0051] In the N-vinylformamide cationic polymer of the present invention, the content of the structural unit (2) is preferably 5 mol% or more and 99 mol% or less, when the total molar number of all structural units contained in the N-vinylformamide cationic polymer is taken as 100 mol%. When the content of the structural unit (2) is equal to or more than the above-mentioned lower limit, the stability of the polymer in an aqueous medium is improved. Furthermore, when the content of the structural unit (2) is equal to or less than the above-mentioned upper limit, bleeding can be efficiently suppressed. From this viewpoint, the content of the structural unit (2) in the N-vinylformamide cationic polymer of the present invention is more preferably 7 mol% or more and 90 mol% or less, and even more preferably 10 mol% or more and 80 mol% or less. The above-mentioned preferred upper and lower limits can be combined in any desired manner.

[0052] When two or more types of N-vinylformamide-based cationic polymers are used, the content of the structural unit (2) in a mixture of two or more types of N-vinylformamide-based cationic polymers is calculated as a proportion when the total number of moles of all structural units contained in the N-vinylformamide-based cationic polymer mixture is taken as 100 mol %.

[0053] Furthermore, from the viewpoint of adjusting the cationic degree to an appropriate level, the N-vinylformamide-based cationic polymer of the present invention may contain, as a structural unit, a structural unit represented by the following formula (3) or a salt thereof (hereinafter, may be referred to as "structural unit (3)"). The structural unit (3) is compatible with both hydrophobic and hydrophilic fibers, and the inclusion of the structural unit (3) makes it possible to adjust properties such as affinity for fabrics. The nitrogen atom contained in the amidine structure represented by the following formula (3) may bond to or form a salt with an organic group or an inorganic acid.

[0054]

[0055] When the N-vinylformamide cationic polymer used in the present invention has the structural unit (3), its content is preferably 20 mol% to 80 mol%, preferably 30 mol% to 78 mol%, and preferably 40 mol% to 75 mol%, when the total molar number of all structural units contained in the N-vinylformamide cationic polymer is taken as 100 mol%. When the content of the structural unit (3) is equal to or greater than the above-mentioned lower limit, the polymer exhibits excellent affinity with a wide range of fabrics, particularly with fabrics containing hydrophobic synthetic fibers. On the other hand, when the content of the structural unit (3) is equal to or less than the above-mentioned upper limit, the anti-bleeding effect tends to be particularly remarkable. The above-mentioned preferred upper and lower limits can be combined arbitrarily.

[0056] The structural unit (3) can be obtained by combining structural units derived from two monomers (acrylonitrile and N-vinylformamide), but the content of the structural unit (3) is calculated by counting one amidine structure as one structural unit.

[0057] When two or more types of N-vinylformamide-based cationic polymers are used, the content of the structural unit (3) in a mixture of two or more types of N-vinylformamide-based cationic polymers is calculated as a proportion when the total number of moles of all structural units contained in the N-vinylformamide-based cationic polymer mixture is taken as 100 mol %.

[0058] The contents of the structural unit (1), the structural unit (2), and the structural unit (3) in the N-vinylformamide-based cationic polymer of the present invention can be calculated from the proportions of the raw material monomers used in the synthesis of the N-vinylformamide-based cationic polymer to introduce each structural unit into the polymer.

[0059] The N-vinylformamide-based cationic polymer of the present invention is not particularly limited, and examples thereof include polyamidine and polyvinylamine. The polyamidine can be obtained by copolymerizing acrylonitrile and N-vinylformamide. The N-vinylformamide-based cationic polymer of the present invention preferably contains one or more selected from the group consisting of polyamidine and polyvinylamine.

[0060] In the present invention, an N-vinylformamide-based cationic polymer having a weight-average molecular weight of 100,000 or less is used. If the weight-average molecular weight of the N-vinylformamide-based cationic polymer exceeds 100,000, the N-vinylformamide-based cationic polymer will not be washed away during the washing process and will remain in the fibers, impairing the texture of the resulting printed textile. An N-vinylformamide-based cationic polymer having a weight-average molecular weight of 100,000 or less is less likely to be washed away during the washing process and remain in the fibers, resulting in a printed textile with a good texture. From this viewpoint, the weight-average molecular weight of the N-vinylformamide-based cationic polymer is preferably 90,000 or less, more preferably 80,000 or less, and even more preferably 70,000 or less. On the other hand, from the viewpoint of keeping the addition amount within an appropriate range, the weight-average molecular weight of the N-vinylformamide-based cationic polymer is preferably 5,000 or more, more preferably 10,000 or more, and particularly preferably 20,000 or more. By ensuring that the weight-average molecular weight is equal to or greater than the above lower limit, the desired bleeding suppression effect can be achieved without excessively increasing the amount added. The above upper and lower limits can be combined in any manner. For example, the weight-average molecular weight of the N-vinylformamide cationic polymer of the present invention is preferably 5,000 to 100,000, more preferably 10,000 to 90,000, and particularly preferably 20,000 to 70,000.

[0061] In the present invention, the weight-average molecular weight of the N-vinylformamide-based cationic polymer can be measured by a conventionally known method. For example, a value measured as a pullulan-equivalent weight-average molecular weight using GPC (gel permeation chromatography) can be used. When the weight-average molecular weight is known, such as in the case of a commercially available product, the catalog value or the weight-average molecular weight measured using GPC can be used. When the weight-average molecular weight is unknown, it may be the weight-average molecular weight measured using the GPC apparatus. The measurement conditions for measuring the weight-average molecular weight by GPC are as described in the Examples section below.

[0062] As the N-vinylformamide-based cationic polymer, only one type may be used, or two or more types differing in polymer type or weight-average molecular weight may be used in combination. When two or more N-vinylformamide-based cationic polymers are used, the weight-average molecular weight of the mixture of two or more N-vinylformamide-based cationic polymers is calculated by proportional calculation of the weight-average molecular weight of each N-vinylformamide-based cationic polymer and its content. In this case, even if an N-vinylformamide-based cationic polymer having a weight-average molecular weight exceeding 100,000 is used, it is sufficient that the weight-average molecular weight of the mixture is 100,000 or less, preferably within the above-mentioned preferred range.

[0063] As the N-vinylformamide-based cationic polymers having different weight-average molecular weights, those having a weight-average molecular weight of 5,000 or more and 100,000 or less are preferred, and among these, those having a weight-average molecular weight of 10,000 or more are more preferred, those having a weight-average molecular weight of 15,000 or more are even more preferred, and those having a weight-average molecular weight of 20,000 or more are particularly preferred. On the other hand, those having a weight-average molecular weight of 90,000 or less are more preferred, those having a weight-average molecular weight of 80,000 or less are even more preferred, and those having a weight-average molecular weight of 70,000 or less are particularly preferred. The above upper and lower limits can be combined in any combination.

[0064] As the N-vinylformamide-based cationic polymer, a commercially available product may be used, such as SC700M (manufactured by Hymo Co., Ltd., weight average molecular weight: 60,000, polyvinylamidine-based cationic polymer).

[0065] From the viewpoint of enhancing the bleeding suppression effect, the cationic degree of the N-vinylformamide-based cationic polymer is preferably 2.0 meq / g or more, more preferably 3.0 meq / g or more. On the other hand, if the cationic degree is high, i.e., if the amount of cations is too large, the positive charges repel each other, resulting in increased repulsion between the cationic polymers. As a result, the dye that is attracted to the cationic polymer is more likely to diffuse in the fabric together with the cationic polymer, resulting in increased bleeding. From the viewpoint of keeping the amount of cations within an appropriate range and more effectively preventing bleeding due to diffusion, the upper limit of the cationic degree of the N-vinylformamide-based cationic polymer of the present invention is preferably 15.0 meq / g, more preferably 13.0 meq / g or less, even more preferably 11.0 meq / g or less, and particularly preferably 10.0 meq / g or less. The preferred upper and lower limits of the cationic degree can be arbitrarily combined. Note that, when two or more N-vinylformamide-based cationic polymers are used, the cationic degree refers to the cationic degree of the mixture of these polymers.

[0066] The optimal range of the cationic degree of the N-vinylformamide-based cationic polymer of the present invention varies depending on the type of ink and fabric used in inkjet printing. For example, in fabrics containing cellulose fibers such as cotton, linen, rayon, polynosic, cupra, and lyocell, the hydroxyl groups of the fiber polymer adsorb to the functional groups of the pretreatment agent through chemical interaction, making diffusion of the cationic polymer difficult. On the other hand, in fabrics containing hydrophobic synthetic fibers such as polyester, acetate, triacetate, and acrylic, diffusion of the cationic polymer occurs relatively easily. Therefore, in fabrics such as polyester, acetate, triacetate, nylon, and acrylic, the cationic degree is preferably 8.0 meq / g or less, more preferably 7.0 meq / g or less, even more preferably 6.0 meq / g or less, and particularly preferably 5.0 meq / g or less, which tends to result in a particularly remarkable bleeding prevention effect.

[0067] Examples of dyes used in aqueous inks include disperse dyes, reactive dyes, and direct dyes. Fabrics containing cellulose fibers such as cotton, linen, rayon, polynosic, cupra, and lyocell are generally dyed with reactive or direct dyes. However, when reactive dyes are used, the active groups in the reactive dye neutralize the cationic functional groups in the cationic polymer, reducing the amount of cations and tending to result in insufficient dye flocculation performance of the pretreatment agent. Therefore, in inkjet printing using reactive dyes on fabrics containing cellulose fibers such as cotton, linen, rayon, polynosic, cupra, and lyocell, the cation degree is preferably greater than 5.0 meq / g, more preferably 6.0 meq / g or more, even more preferably 7.0 meq / g or more, and particularly preferably 8.0 meq / g or more, so that the amount of cations falls within a sufficient range, thereby more effectively preventing bleeding due to the dispersion.

[0068] The cationic degree of the cationic polymer can be measured as follows. (Measurement of Cationic Degree of Cationic Polymer) Approximately 0.4 g (precisely weighed) of cationic polymer is sampled in a 100 mL measuring flask, and demineralized water is added to make up to 100 mL (solution A). 5 mL is sampled from solution A, and demineralized water is added to make up to 200 mL, and the pH is adjusted to 2.5 with a 0.1 N HCl aqueous solution. Three drops of toluidine blue are then added, and the pH-adjusted solution is titrated with a 1 / 400 N-PVSK (potassium polyvinyl sulfate) solution until the color of the solution changes from blue to red. A blank test is also performed in the same manner, and the cationic degree is calculated using the following formula: Cationic degree = {(1 / 400) x (PVSK solution factor) x (sample titration amount (mL) - blank titration amount (mL)) x (100 / 5)} / {(sample amount (g)) x (cationic polymer concentration)}

[0069] The N-vinylformamide cationic polymer of the present invention preferably satisfies the relationship of the following formula (I), where X is the weight average molecular weight (Mw) of the N-vinylformamide cationic polymer and Y (meq / g) is the cationic degree: 150<(X×Y) / 1000<1200 (I).

[0070] When the weight-average molecular weight (X) and cationic degree (Y) of the N-vinylformamide-based cationic polymer satisfy the relationship of formula (I), color transfer during the washing process can be reduced. Here, "color transfer" refers to a phenomenon in which, during the washing process in which a printed textile after inkjet printing is washed with a washing solution containing water and / or a detergent, the dye that has flowed out of the fabric into the washing solution re-adheres to areas other than the printed area, resulting in undesired staining. This color transfer phenomenon can be reduced by using a dye that is easily washed in the washing process, but using a dye that is easily washed limits the flexibility in the selection of dyes that can be used. Therefore, from the perspective of obtaining a variety of printed images using a wide range of dyes, improvement using a pretreatment agent has been strongly desired.

[0071] In the washing process, the smaller the weight-average molecular weight of the N-vinylformamide-based cationic polymer, the more quickly the pretreatment agent is removed from the fabric, resulting in less redeposition of the dye, i.e., less reactivity to color transfer. On the other hand, the smaller the weight-average molecular weight of the N-vinylformamide-based cationic polymer, the lower the coagulation action and the less effective it tends to be at suppressing bleeding during printing. Furthermore, the lower the cationic degree of the N-vinylformamide-based cationic polymer, the less likely it is to cause color transfer, but the less likely it is that the dye will be fixed during printing, making bleeding more likely to occur. Thus, there is a trade-off between the color transfer phenomenon during washing and the occurrence of bleeding during printing. The present inventors conducted research aimed at preventing both bleeding and color transfer, and found that by controlling the weight-average molecular weight (Mw) and cationic degree (Y) of the N-vinylformamide-based cationic polymer to fall within a range satisfying the above formula (I), it is possible to maintain the bleeding prevention effect while also sufficiently suppressing color transfer during the washing process. The above-mentioned color transfer phenomenon is particularly likely to occur when reactive dyes are used, and therefore the above-mentioned color transfer prevention effect is particularly effective for inks that use reactive dyes.

[0072] From the viewpoint of suppressing both bleeding and color transfer, the lower limit of the above formula (I), i.e., the value of (X × Y) / 1000, is preferably 200 or more, more preferably 250 or more, even more preferably 300 or more, and particularly preferably 400 or more. On the other hand, the upper limit of (X × Y) / 1000 is preferably 1000 or less, more preferably 800 or less. In this specification and claims, the value of (X × Y) / 1000 is limited to two significant digits, and the value is rounded to the nearest third digit. The weight average molecular weight may be limited to two significant digits.

[0073] The N-vinylformamide cationic polymer of the present invention preferably has a viscosity of 400 mPa·s or less in an aqueous solution containing a 30% by mass polymer. Having a viscosity of a 30% by mass aqueous solution of the polymer that is equal to or less than the above upper limit is preferable in terms of excellent application performance and impregnation of the pretreatment agent onto fabric. From this perspective, the viscosity is preferably 300 mPa·s or less, more preferably 200 mPa·s or less, and even more preferably 100 mPa·s or less. While the lower limit of the viscosity is not particularly limited, it is preferably 1 mPa·s or more, and more preferably 2 mPa·s or more. The viscosity can be determined by the method described in the Examples. The aqueous N-vinylformamide cationic polymer solution used for viscosity measurement may contain, in addition to the N-vinylformamide cationic polymer and water, additives such as a catalyst used during polymer polymerization.

[0074] <Aqueous Medium> The pretreatment agent of the present invention preferably contains at least water as the aqueous medium. The pretreatment agent of the present invention can contain water or an aqueous medium that is a mixed solvent of water and a humectant, which will be described later. As the water, deionized water or ion-exchanged water is preferably used. From the viewpoint of achieving inkjet ejection suitability, the content of water in the pretreatment agent of the present invention is preferably 50% by mass or more and 95% by mass or less, based on the total amount of the pretreatment agent.

[0075] <Moisturizing Agent> The pretreatment agent of the present invention may contain a moisturizing agent.

[0076] The humectant has the function of delaying the drying of the pretreatment agent (drying of water) in the inkjet head when not ejecting, and delaying an increase in the viscosity of the pretreatment agent (preventing a sudden increase in viscosity). However, because some common humectants are prone to bleeding, the present invention uses a humectant that is less likely to cause bleeding.

[0077] The boiling point of the moisturizer is preferably 180° C. or higher, and from the viewpoint of preventing bleeding, is more preferably 185° C. or higher, even more preferably 190° C. or higher, and particularly preferably 195° C. or higher. On the other hand, moisturizers with excessively high boiling points are less likely to volatilize, so the boiling point of the moisturizer is preferably 350° C. or lower, more preferably 320° C. or lower, and even more preferably 300° C. or lower.

[0078] The boiling point of the moisturizing agent can be measured, for example, by the equilibrium reflux boiling point method (JIS K2233).

[0079] The humectant used in the present invention is preferably an organic solvent, and more preferably a protic polar solvent, because it can be strongly solvated with the negatively charged dye through hydrogen bonding, thereby fixing the dye at a desired position and preventing bleeding; and it can also delay the drying of the pretreatment agent (drying of water) in the inkjet head when ejection is not being performed, thereby delaying an increase in the viscosity of the pretreatment agent (preventing a sudden increase in viscosity).

[0080] From the viewpoint of penetration and bleeding, the moisturizing agent used in the present invention may be a polyhydric alcohol, an ether, a nitrogen-containing heterocyclic compound, an amide, an amine, a sulfur-containing compound, etc. Among these, a polyhydric alcohol, an ether, an amide, and an amine are preferred, and a polyhydric alcohol is more preferred.

[0081] Examples of polyhydric alcohols include ethylene glycol (boiling point 197.6°C), diethylene glycol (boiling point 245°C), triethylene glycol (boiling point 287.4°C), tetraethylene glycol (boiling point 328°C), propylene glycol (boiling point 188°C), dipropylene glycol (boiling point 232.2°C), glycerin (boiling point 290°C), diglycerin (boiling point 265 to 270°C), etc. Among these, ethylene glycol and glycerin are preferred.

[0082] These moisturizing agents may be used alone or in combination of two or more.

[0083] <Antifoaming Agent> The pretreatment agent of the present invention may contain an antifoaming agent. By incorporating an antifoaming agent, color bleeding can be more reliably prevented and the texture can be improved.

[0084] As the defoaming agent, any of those used in ordinary fiber treatments can be used, for example, alcohol-based defoaming agents, fatty acid derivative-based defoaming agents, and silicone-based defoaming agents can be mentioned. Among them, from the viewpoint of cleanability when washing off unfixed dyes and auxiliaries from the fabric, it is preferable to contain one or more selected from the group consisting of alcohol-based defoaming agents and fatty acid derivative-based defoaming agents, and it is more preferable to contain an alcohol-based defoaming agent. As the defoaming agent, only one type may be used, or two or more types may be used in combination.

[0085] (Alcohol-Based Antifoaming Agent) The alcohol-based antifoaming agent preferably has an HLB value of 15 or less, more preferably 10 or less. As the alcohol-based antifoaming agent, a higher alcohol can be preferably used. The number of carbon atoms in the higher alcohol is preferably 12 or more, and is preferably 25 or less, more preferably 22 or less. For example, the number of carbon atoms in the higher alcohol is preferably 12 to 25, more preferably 12 to 22. Furthermore, the alcohol-based antifoaming agent may be any of primary alcohol, secondary alcohol, and tertiary alcohol. Among these, primary alcohol and secondary alcohol are preferred.

[0086] Furthermore, either a monohydric alcohol or a polyhydric alcohol can be used as the alcohol-based defoaming agent. The number of hydroxy groups in the alcohol is preferably 2 or more, and is preferably 4 or less, and more preferably 3 or less. For example, the number of hydroxy groups in the alcohol is preferably 2 to 4, and more preferably 2 to 3.

[0087] As the alcohol-based defoaming agent, alcohols having an ether group can also be preferably used. Examples of the alcohols having an ether group include polyalkylene glycol-based compounds and compounds obtained by addition polymerization of alkylene oxide with higher alcohols. In this case, ethylene oxide or propylene oxide can be used as the alkylene oxide. Among them, polyalkylene glycol-based compounds are preferred, and among them, polyethylene glycol-based compounds are more preferred. Furthermore, it is more preferred that the polyethylene glycol-based compounds have an alkyl group. In other words, alkyl-polyethylene glycol-based compounds are more preferred.

[0088] In addition to the above-mentioned alcohol-based antifoaming agents, examples thereof include diamylphenoxyethanol, 3-heptanol, 2-ethylhexanol, acetylene alcohol, acetylene glycol, isopropyl alcohol, and alkyl-polyethylene glycol compounds.

[0089] Among the above, higher alcohols and alcohols having an ether group are preferred, higher alcohols and polyalkylene glycol compounds are more preferred, higher alcohols and polyethylene glycol compounds are even more preferred, and higher alcohols and alkyl-polyethylene glycol compounds are particularly preferred.

[0090] Commercially available alcohol-based defoaming agents include, for example, Antifloss (registered trademark) F-102 and F-103 (both manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and Antifoaming Agent (manufactured by Furukawa Chemical Co., Ltd.).

[0091] (Fatty Acid Derivative Antifoaming Agent) The fatty acid derivative antifoaming agent preferably has an HLB value of 15 or less, more preferably 10 or less.

[0092] Examples of fatty acid derivative-based defoaming agents include mineral oil, sorbitan fatty acid ester, fatty acid ester, glycerin fatty acid ester, and sucrose fatty acid ester. Among these, mineral oil is preferred because of its immediate effect. Furthermore, the mineral oil is preferably a long-chain alkyl-based one.

[0093] The number of carbon atoms of the fatty acid used as a raw material for the fatty acid derivative of the fatty acid derivative-based defoaming agent is preferably 16 or more, more preferably 18 or more. On the other hand, it is preferably 24 or less, more preferably 22 or less. The above upper and lower limits can be combined arbitrarily. For example, the number of carbon atoms of the fatty acid is preferably 16 or more and 24 or less, more preferably 18 or more and 22 or less. Examples of fatty acids used as a raw material for the fatty acid derivative of the fatty acid derivative-based defoaming agent include stearic acid, oleic acid, erucic acid, and behenic acid. Among these, stearic acid is preferred.

[0094] Commercially available fatty acid derivative antifoaming agents include, for example, S-39H and S-49H (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and NK-2 (manufactured by Osaka Chemical Co., Ltd.).

[0095] (Silicone-based antifoaming agent) Silicone-based antifoaming agent is not particularly limited.For example, either aqueous or non-aqueous type can be used, and it can be oil type composed of silicone oil, oil compound type in which dispersant is added to silicone oil, emulsion type in which silicone oil is emulsified, or self-emulsifying type.Among them, emulsion type is preferred from the viewpoint of supplementing dispersibility in water.Among the emulsion types, O / W type is more preferred.

[0096] Specific examples of silicone-based antifoaming agents include polydimethylsiloxane, dimethylsilicone, and fluorosilicone, with polydimethylsiloxane being preferred.

[0097] Commercially available silicone antifoaming agents include, for example, TSA730, TSA732, TSA770, TSA772, TSA7341, YMA6509, TSA780 (all manufactured by GE Toshiba Silicones), M-6500, M-700 (all manufactured by Ichiro), Antifoam SS, Antifoam S-8 (all manufactured by Nissei Chemical Co., Ltd.), KM-70, KM-71, KM-73, KM-73A, KM-90, KM-89, KM-83A, KM-75, KS-502, KS-537, KM-98, KM-7750, and X-50-1041 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0098] <Sizing Agent> The pretreatment agent of the present invention may contain a sizing agent.

[0099] As the sizing agent, any of natural sizing agents, semi-synthetic sizing agents, and synthetic sizing agents can be used. Natural sizing agents include starch-based agents such as corn starch and British gum; gum-based agents such as guar gum and locust bean gum; seaweed-based agents such as alginate and agar; and inorganic agents such as montmorillonite and silica (silicon dioxide). Semi-synthetic sizing agents include cellulose-based agents such as carboxymethyl cellulose, methyl cellulose, and hydroxyethyl cellulose. Synthetic sizing agents include polyvinyl alcohol, polyacrylate, polyethylene oxide, polyvinyl acetate / maleic anhydride, and the like.

[0100] The sizing agent preferably contains a nonionic or anionic sizing agent that is compatible with the N-vinylformamide cationic polymer. The incorporation of a sizing agent allows the pretreatment agent to be adjusted to an appropriate viscosity. The phrase "the sizing agent is compatible with the N-vinylformamide cationic polymer" means that when 250 g each of a 1% by mass N-vinylformamide cationic polymer aqueous solution and a 1% by mass sizing agent aqueous solution are mixed, allowed to stand at 25°C for 24 hours, and then filtered through an 80-mesh sieve, the sieve residue is less than 10 g.

[0101] Examples of nonionic or anionic sizing agents compatible with N-vinylformamide-based cationic polymers include hydroxyethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, guar gum, and montmorillonite. One type of sizing agent may be used alone, or two or more types may be used in combination.

[0102] As the sizing agent, it is preferable to use a natural sizing agent and / or a semi-synthetic sizing agent, and more preferably to use one or more selected from the group consisting of methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, and guar gum. Furthermore, from the viewpoint of excellent detergency when washing off unfixed dyes and auxiliaries from the fabric, it is more preferable to use one or more selected from the group consisting of methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, and guar gum in combination with montmorillonite as the sizing agent.

[0103] Examples of commercially available adhesives include hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd.), guar gum (ESAFLOR (registered trademark) 4W, manufactured by Lamberti), montmorillonite (Kunipia (registered trademark) F, manufactured by Kunimine Industries Co., Ltd.), and montmorillonite (Sumecton (registered trademark), manufactured by Kunimine Industries Co., Ltd.).

[0104] <Dyeing Agent> The pretreatment agent of the present invention may contain a dyeing agent. The incorporation of a dyeing agent can further improve the penetration of the ink into the fabric.

[0105] The deep-dyeing agent is preferably one that is compatible with the N-vinylformamide cationic polymer among deep-dyeing agents used in ordinary fiber treatments. The phrase "the deep-dyeing agent is compatible with the N-vinylformamide cationic polymer" means that when 250 g each of a 1 mass % aqueous solution of the N-vinylformamide cationic polymer and a 1 mass % aqueous solution of the deep-dyeing agent are mixed, left to stand at 25°C for 24 hours, and then filtered through an 80-mesh sieve, the sieve residue is less than 10 g.

[0106] The deep-dyeing agent compatible with the N-vinylformamide cationic polymer is not particularly limited, and examples thereof include amides, glycol ethers, and polyethers. Among these, amides are preferred, and N-alkylolamides are even more preferred. As the deep-dyeing agent, only one type may be used, or two or more types may be used in combination.

[0107] Commercially available deep-dyeing agents include, for example, Sunflorene (registered trademark) SN (N-alkylolamide, manufactured by Nicca Chemical Co., Ltd.), Hiol 420 (glycol ether of higher alcohol, manufactured by Hayashi Chemical Co., Ltd.), and Cellopol (registered trademark) PA-19S (manufactured by Sanyo Chemical Industries, Ltd.).

[0108] <Optional Components> The pretreatment agent of the present invention may contain optional components such as organic solvents other than the above-mentioned humectants, polyvalent metal salts, organic acids, solubilizing agents, viscosity adjusters, pH adjusters, anti-reducing agents, preservatives, and surfactants, provided the effects of the present invention are not impaired.

[0109] <Composition> The composition of the pretreatment agent of the present invention will be described below. In the following description of the composition, "content" means "the proportion of the active ingredient contained in the agent in the pretreatment agent," and "blending ratio" means "the proportion of the blended amount (addition amount) of the agent itself, i.e., not only the active ingredient but also a solvent such as water, if present, in the pretreatment agent."

[0110] The content of the N-vinylformamide-based cationic polymer of the present invention in the pretreatment agent of the present invention varies depending on the type of fabric to be treated, the amount of pretreatment agent applied, etc., but is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 1.5% by mass or more, in terms of the solids content relative to 100% by mass of the total mass of the pretreatment agent. When the content of the N-vinylformamide-based cationic polymer is equal to or greater than the aforementioned lower limit, ink adhesion to the fabric is easily improved. The upper limit of the content of the N-vinylformamide-based cationic polymer is preferably 3.5% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.5% by mass or less, in terms of the solids content relative to 100% by mass of the total mass of the pretreatment agent. When the content of the N-vinylformamide-based cationic polymer is equal to or less than the aforementioned upper limit, the cleanability when washing off unfixed dyes and auxiliaries from the fabric is improved, and the texture is also improved. The above-mentioned upper and lower limits can be combined in any combination. For example, the content of the N-vinylformamide cationic polymer of the present invention in the pretreatment agent of the present invention, expressed as the solids content relative to the total mass of the pretreatment agent (100 mass%), is preferably from 0.5 to 3.5 mass%, more preferably from 1.0 to 3.0 mass%, and even more preferably from 1.5 to 2.5 mass%.

[0111] When the pretreatment agent of the present invention contains a humectant, the content of the humectant in the pretreatment agent is preferably 10% by mass or more, and more preferably 15% by mass or more, relative to the total mass of the pretreatment agent (100% by mass), from the viewpoint of drying of the inkjet nozzle surface. On the other hand, from the viewpoint of bleeding, the content of the humectant is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, relative to the total mass of the pretreatment agent (100% by mass). The above upper and lower limits can be combined in any manner. For example, the content of the humectant in the pretreatment agent of the present invention is preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 45% by mass or less, and even more preferably 15% by mass or more and 40% by mass or less, relative to the total mass of the pretreatment agent (100% by mass).

[0112] When the pretreatment agent of the present invention contains an antifoaming agent, the blending ratio of the antifoaming agent in the pretreatment agent is preferably 0.02% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.10% by mass or more, relative to the total mass (100% by mass) of the pretreatment agent, from the viewpoints of texture and cleanability. On the other hand, from the viewpoint of preventing bleeding, the blending ratio of the antifoaming agent is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, relative to the total mass (100% by mass) of the pretreatment agent. The above upper and lower limits can be combined arbitrarily. For example, the blending ratio of the antifoaming agent in the pretreatment agent of the present invention is preferably 0.02% by mass or more and 5.0% by mass or less, more preferably 0.03% by mass or more and 4.0% by mass or less, relative to the total mass (100% by mass) of the pretreatment agent.

[0113] When the pretreatment agent of the present invention contains a paste, the paste content in the pretreatment agent varies depending on the viscosity required for the application method. However, in order to facilitate increasing the viscosity of the pretreatment agent, the paste content is preferably 0.5% by mass or more, and more preferably 1.0% by mass or more, relative to the total mass (100% by mass) of the pretreatment agent. In order to achieve excellent cleanability when washing off unfixed dye and auxiliary agents from the fabric, the paste content is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, and even more preferably 2.0% by mass or less, relative to the total mass (100% by mass) of the pretreatment agent. The above upper and lower limits can be arbitrarily combined. For example, the paste content in the pretreatment agent of the present invention is preferably 0.5% by mass or more and 5.0% by mass or less, more preferably 1.0% by mass or more and 4.0% by mass or less, and even more preferably 1.0% by mass or more and 2.0% by mass or less, relative to the total mass (100% by mass) of the pretreatment agent.

[0114] When the pretreatment agent of the present invention contains a deep-dyeing agent, the blending ratio of the deep-dyeing agent in the pretreatment agent is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and even more preferably 4.0% by mass or more, relative to the total mass (100% by mass) of the pretreatment agent, from the viewpoint of excellent ink penetration into the fabric. On the other hand, from the viewpoint of ink bleeding resistance, the blending ratio of the deep-dyeing agent is preferably 15.0% by mass or less, more preferably 10.0% by mass or less, even more preferably 8.0% by mass or less, and particularly preferably 5.0% by mass or less, relative to the total mass (100% by mass) of the pretreatment agent. The above upper and lower limits can be combined as desired. For example, the blending ratio of the deep-dyeing agent in the pretreatment agent of the present invention, relative to the total mass of the pretreatment agent (100 mass%), is preferably from 1.0 mass% to 15.0 mass%, more preferably from 3.0 mass% to 10.0 mass%, even more preferably from 4.0 mass% to 8.0 mass%, and particularly preferably from 4.0 mass% to 5.0 mass%.

[0115] When the pretreatment agent of the present invention contains a deep-dyeing agent, the amount of the deep-dyeing agent in the pretreatment agent is preferably 400 parts by mass or more, more preferably 450 parts by mass or more, per 100 parts by mass of the total N-vinylformamide polymer, in order to achieve excellent ink penetration into fabric. In order to reduce ink bleeding, the upper limit of the amount of the deep-dyeing agent is preferably 2,000 parts by mass or less, more preferably 1,500 parts by mass or less, per 100 parts by mass of the total N-vinylformamide polymer. The above upper and lower limits can be combined in any manner. For example, the amount of the deep-dyeing agent in the pretreatment agent of the present invention is preferably 400 parts by mass or more and 2,000 parts by mass or less, more preferably 450 parts by mass or more and 1,500 parts by mass or less, per 100 parts by mass of the total N-vinylformamide polymer. When the pretreatment agent of the present invention contains a paste, the amount of the deep-dyeing agent in the pretreatment agent is preferably 200 parts by mass or more, more preferably 300 parts by mass or more, per 100 parts by mass of the total paste.

[0116] [Method for producing pretreatment agent] The method for producing the pretreatment agent for inkjet textile printing of the present invention is not particularly limited, but examples thereof include a method in which an N-vinylformamide cationic polymer and, if necessary, a moisturizing agent, an antifoaming agent, etc. are mixed and stirred. A known stirrer can be used for stirring.

[0117] [Inkjet Printing Ink Set] The inkjet printing ink set of the present invention contains the inkjet printing pretreatment agent of the present invention and a water-based ink.

[0118] The ink used in inkjet textile printing is preferably a water-based ink containing water and a colorant. Furthermore, it is preferable to use a dye as the colorant. Inkjet inks are mainly classified into pigment inks and dye inks. Pigment inks containing a pigment as a colorant are fixed near the surface of the fabric, and therefore tend to impair the soft texture of the fabric compared to dye inks that dye the fibers themselves. Therefore, it is preferable to use a dye as the colorant. Dyes used in aqueous inks vary depending on the type of fabric to be treated, but examples include disperse dyes, reactive dyes, and direct dyes.

[0119] [Inkjet Printing Method] The inkjet printing method of the present invention includes a pretreatment step of pretreating a fabric with the inkjet printing pretreatment agent of the present invention, and a printing step of inkjet printing an aqueous ink containing water and a colorant onto an area of ​​the fabric that has been pretreated (hereinafter, may be referred to as a "pretreated area").

[0120] <Pretreatment Agent Application Step> The material (type of fiber) of the fabric to be pretreated is not particularly limited as long as it is a fabric that is commonly used in inkjet printing, and examples thereof include cotton, nylon, silk, polyester, acetate, triacetate, acrylic linen, rayon, polynosic, cupra, and lyocell.

[0121] The fabric usable in the present invention may be made of only one type of fiber, or may be a blended woven fabric or blended nonwoven fabric of multiple fibers. These fibers may be in any form, such as woven fabric, nonwoven fabric, or knitted fabric. The thickness of the fibers constituting the fabric is preferably within the range of 10 to 100 d.

[0122] The pretreatment of fabric can be carried out, for example, by applying the pretreatment agent of the present invention to the fabric. Examples of methods for applying the pretreatment agent of the present invention include a method of inkjet-discharging the pretreatment agent, a method of immersing a fabric in the pretreatment agent, a method of applying the pretreatment agent with a roll coater, a method of applying the pretreatment agent with a squeegee, and a method of spraying the pretreatment agent with a spray device. The method of applying the pretreatment agent with a squeegee is preferred because it allows application only to the areas to which the inkjet ink is to be applied and can be operated with a simple device. The method of inkjet-discharging the pretreatment agent is also preferred because it reduces the amount of wastewater and allows for space-saving. Two or more of the above application methods may be combined.

[0123] <Inkjet Printing Step> In the inkjet printing method of the present invention, it is preferable to ink-jet print onto the pretreated area of ​​the fabric pretreated with the pretreatment agent of the present invention without drying it, that is, to apply ink by a so-called wet-on-wet method.

[0124] Conventional dye pretreatment agents require high viscosity to suppress bleeding, making inkjet application difficult, and since drying after application of the pretreatment agent is necessary, the printing process is complicated and productivity is poor. The pretreatment agent of the present invention not only has excellent inkjet ejection suitability and low viscosity, but also exhibits a sufficient bleeding suppression effect even when ink is applied to the pretreated fabric while it is still wet, without drying.

[0125] The mechanism by which the pretreatment agent and ink of the present invention exert an excellent bleeding suppression effect when applied by the wet-on-wet method is not clear, but is presumed to be as follows. When applied by the wet-on-wet method, the cationic polymer in the pretreatment agent and the dye in the ink easily flow with each other and come into contact with each other. It is thought that this allows the cationic polymer in the pretreatment agent and the dye component in the ink to interact with each other, allowing the dye to aggregate sufficiently.

[0126] "Inkjet printing is performed on the pretreated fabric without drying it" means that inkjet printing is performed on the area where the pretreatment agent is applied while the pretreatment agent on the fabric is still in a liquid state. In other words, it is preferable to apply the ink while the remaining amount of aqueous medium contained in the previously applied pretreatment agent per unit area of ​​the printing region is 10% by mass or more, preferably 50 to 100% by mass. The remaining amount of aqueous medium can be adjusted, for example, by the time between the application of the pretreatment agent and the application of the ink (application interval) and the surface temperature of the fabric. The application interval is optional, but can be, for example, 10 minutes or less, preferably 1 minute or less, and more preferably 30 seconds or less. The lower limit of the application interval can be, for example, 0.1 seconds or more. The environment between the pretreatment step and the printing step can be atmospheric pressure, with the surface temperature of the fabric being 40°C or less, preferably 10 to 40°C.

[0127] The ink used in inkjet printing is preferably a water-based ink containing water and a colorant. Furthermore, it is preferable to use a dye as the colorant. As mentioned above, inkjet inks are mainly classified into pigment inks and dye inks. However, pigment inks containing a pigment as a colorant are fixed near the surface of the fabric, and therefore tend to impair the soft texture of the fabric compared to dye inks, which dye the fibers themselves.

[0128] Examples of dyes used in aqueous inks include disperse dyes, reactive dyes, and direct dyes.

[0129] The combination of fabric and dye is not particularly limited, but examples include reactive dyes and fibers primarily composed of cellulose (cotton, linen, rayon, polynosic, cupra, lyocell, etc.), direct dyes and fibers primarily composed of cellulose (cotton, linen, rayon, polynosic, cupra, lyocell, etc.), and disperse dyes and hydrophobic synthetic fibers (polyester, acetate, triacetate, acrylic, etc.). Among these, combinations of reactive dyes and fibers primarily composed of cellulose (cotton, linen, rayon, polynosic, cupra, lyocell, etc.) and disperse dyes and hydrophobic synthetic fibers (polyester, acetate, triacetate, acrylic, etc.) are preferred. Furthermore, the pretreatment agent of the present invention is particularly suitable for inkjet printing of polyester fabrics with disperse dyes and inkjet printing of cotton fabrics with reactive dyes. Such combinations tend to enhance the effects of the present invention. However, the combination of fabrics and dyes is not limited to these.

[0130] The inkjet printing method of the present invention can employ any known method, except that inkjet printing is performed on a fabric pretreated with the inkjet printing pretreatment agent of the present invention without drying it. For example, after the printing step, the method may include a heat treatment step in which the ink is penetrated into the interior of the fabric by dry heat treatment (oven) or steaming, or a cleaning step in which unfixed dye, auxiliaries, pretreatment agents, etc. are washed away from the fabric by cleaning. As the cleaning treatment in the cleaning step, any known cleaning method can be employed, but reduction cleaning is preferred, and alkaline reduction treatment is more preferred.

[0131] As described above, the present invention uses a pretreatment agent of the present invention, which contains a specific structural unit and an N-vinylformamide-based cationic polymer having a weight-average molecular weight of a predetermined value or less. By using the pretreatment agent of the present invention, even when inkjet printing is performed without drying after application of the pretreatment agent, bleeding can be prevented and a printed textile with excellent texture can be obtained. Furthermore, not requiring drying after application of the pretreatment agent improves productivity, achieving cost reductions, energy savings, and space savings.

[0132] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following descriptions.

[0133] Test Example 1 In Test Example 1, the following raw materials were used.

[0134] [Synthesis Example 1 of N-vinylformamide-Based Cationic Polymer] <Synthesis of N-vinylformamide-Based Cationic Polymer: PVADL1> 70 g of N-vinylformamide, 48 g of acrylonitrile, 69 g of demineralized water, and 0.18 g of sodium hypophosphite as a chain transfer agent for molecular weight adjustment were added to prepare an aqueous monomer solution, which was then charged into a measuring vessel equipped with a nitrogen inlet tube. 173 g of demineralized water and 3 g of polyethylene glycol 20000 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were charged into a reaction apparatus equipped with a stirrer, a nitrogen inlet tube, and a condenser. The aqueous solution was heated to 70°C, and then 11.2 g of a 10% aqueous solution of azobis(2-amidinopropane) hydrochloride was added. The aqueous monomer solution was added dropwise for 3 hours, yielding a suspension in which an N-vinylformamide-acrylonitrile copolymer had precipitated in water. After the polymerization was completed, 3.7 g of hydroxylamine sulfate was added, and the mixture was kept at 55° C. for 1 hour to prevent insolubilization. 61 g of 35% hydrochloric acid was added, and the mixture was hydrolyzed at 70° C. for 20 minutes, followed by an amidinization reaction at 90° C. for 3 hours to obtain PVADL1 (an N-vinylformamide cationic polymer aqueous solution). PVADL1 is an N-vinylformamide cationic polymer having a structural unit represented by formula (1) or (2) and a structural unit represented by formula (3) as structural units. The content of structural unit (1) or (2), calculated from the amounts of raw material monomers used, was 21 mol %, and the content of structural unit (3) was 65 mol %.

[0135] <Synthesis of N-vinylformamide-based cationic polymer: PVADL2> PVADL2 was obtained in the same manner as in the production of PVADL1, except that the amount of sodium hypophosphite added was changed to 1.12 g.

[0136] <Synthesis of N-vinylformamide-based cationic polymer: PVADL3> PVADL3 was obtained in the same manner as in the production of PVADL1, except that the amount of sodium hypophosphite added was changed to 2.00 g.

[0137] <Synthesis of N-vinylformamide-based cationic polymer: PVADL4> PVADL4 was obtained in the same manner as in the production of PVADL1, except that the amount of sodium hypophosphite added was changed to 5.61 g.

[0138] The weight-average molecular weight, cationic degree, and (X×Y) / 1000 value of the resulting N-vinylformamide cationic polymers PVADL1 to PVADL4, as well as the viscosity of the N-vinylformamide cationic polymer aqueous solution, were measured by the following methods. The results are shown in Table 1 together with the content of the structural units of each cationic polymer.

[0139]

[0140] [Weight-average molecular weight] The weight-average molecular weight of the N-vinylformamide-based cationic polymer was measured using a GPC apparatus by the following method: GPC apparatus: HLC-8320GPC (manufactured by Tosoh Corporation) Column: TSKgel guard column PWxL-CP (6.0 mm I.D. × 4 cm) + TSKgel G6000 PWxL-CP + TSKgel G3000 PWxL-CP (7.8 mm I.D. × 30 cm each) (manufactured by Tosoh Corporation) Detector: RI detector, polarity (+) Eluent: 0.2 M NaNO ３ Aqueous solution: Flow rate: 1.0 mL / min; Concentration: 0.1 wt% (concentration based on the cationic polymer component); Injection volume: 100 μL; Column temperature: 40°C. As a pretreatment, the sample was weighed and diluted with a predetermined amount of eluent. After 2 hours, the sample solution was gently shaken and filtered through a 0.45 μm hydrophilic PTFE cartridge filter. The calibration curve was calculated using a third-order approximation equation using standard pullulan (manufactured by Shodex). Therefore, the obtained values ​​are pullulan-equivalent values. The values ​​were expressed to two significant digits.

[0141] [Cationic Degree] The cationic degree of the N-vinylformamide-based cationic polymer was measured by the following method. Approximately 0.4 g (precisely weighed) of cationic polymer was sampled in a 100 mL measuring flask, and demineralized water was added to make up to 100 mL (solution A). 5 mL was sampled from solution A, and demineralized water was added to make up to 200 mL, and the pH was adjusted to 2.5 with 0.1 N HCl aqueous solution. Thereafter, three drops of toluidine blue were added, and titration was performed using a 1 / 400 N-PVSK (potassium polyvinyl sulfate) solution until the color of the pH-adjusted solution changed from blue to red. A blank test was also conducted in the same manner, and the cationic degree was calculated using the following formula: Cationic degree = {(1 / 400) × (PVSK solution factor) × (sample titration amount (mL) - blank titration amount (mL)) × (100 / 5)} / {(sample amount (g)) × (cationic polymer concentration)}

[0142] [Viscosity of Aqueous Solution] The viscosity of the aqueous N-vinylformamide cationic polymer solution was measured by the following method: Each measurement sample, whose N-vinylformamide cationic polymer concentration was 30% by mass, was placed in a thermostatic bath at 25°C and the viscosity was measured using a Brookfield viscometer (No. 4 rotor, 60 rpm x 5 minutes).

[0143] [Materials] In addition to the above-mentioned PVADLs 1 to 4, the materials used in the examples and comparative examples of Test Example 1 are shown below.

[0144] <Cationic polymer> Polyallylamine 1: Trade name "PAA-HCL-10L", manufactured by Nittobo Medical Co., Ltd., weight average molecular weight: 100,000 (catalog value) Polyallylamine 2: Trade name "PAA-HCL-3L", manufactured by Nittobo Medical Co., Ltd., weight average molecular weight: 15,000 (catalog value)

[0145] <Moisturizing agent> Ethylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point: 197.6°C) Glycerin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point: 290°C)

[0146] <Antifoaming agent> Silicone type (product name "KM-90", manufactured by Shin-Etsu Chemical Co., Ltd., emulsion type, containing polydimethylsiloxane)

[0147] Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-3 Preparation of Pretreatment Agents Pretreatment agents were prepared according to the compositions shown in Table 1. Specifically, each component was placed in a container, stirred for two hours using a stirrer, and then left to mature overnight. The numerical values ​​representing the content of each component in Table 1 are expressed in units of mass%, and each component other than the humectant is expressed as the content of the active ingredient (solid content) relative to 100% by mass of the total mass of the pretreatment agent. The content of the humectant is the content relative to 100% by mass of the total mass of the pretreatment agent. Water was added in an amount adjusted so that the total amount of the pretreatment agent was 100% by mass.

[0148] <Pretreatment Step> The inkjet ejection test of the pretreatment agent was carried out using an inkjet device (Inkjet Lab, manufactured by Cluster Technology Co., Ltd.) as described below. The printing substrate was a woven fabric (polyester crepe, density: 221 threads / inch lengthwise, 108 threads / inch widthwise, basis weight: 91 g / m ２ A spray bottle (manufactured by Irozome Co., Ltd.) was used. During the print test for bleeding evaluation 1 described below, the pretreatment agent was applied using a commercially available cosmetic hand spray. The amount of pretreatment agent applied was the amount that would be dispensed with three pumps, although this amount was affected by the viscosity of the pretreatment agent composition, the basis weight of the fabric, and the print area.

[0149] <Inkjet Printing Step> The fabric pretreated in the pretreatment step was transferred to an inkjet device (Inkjet Lab, manufactured by Cluster Technology Co., Ltd.) within 5 seconds of application of the pretreatment agent, i.e., before the applied pretreatment agent had dried, and ink was applied to the pretreated area where the pretreatment agent had been applied. A water-based ink containing a black disperse dye was used as the ink. A grid pattern was used as the printed image pattern. In this pattern, the grid size was 2 mm square and the line thickness was 0.2 mm.

[0150] <Heat Treatment Step (Steaming Treatment)> The ink-coated fabric was subjected to a steaming treatment at 180° C. for 10 minutes using a HT steamer, HT-3-550 model, manufactured by Tsujii Senki Kogyo Co., Ltd.

[0151] <Cleaning Step> The fabric after the steaming treatment was washed with water for 5 minutes by rubbing twice per second. A surfactant (Amylazine D) of 1 g / L, sodium hydrosulfite of 1 g / L, and NaOH (granules) of 1 g / L were added to and dissolved in 80°C warm water, and the washed fabric was then added and subjected to reduction cleaning for 5 minutes to wash away the pretreatment agent and excess ink adhering to the fabric. After reduction cleaning, the fabric was washed again with water to wash away the reduction cleaning agent adhering to the fabric.

[0152] Reference Example 1-1 In Reference Example 1-1, a pretreatment agent containing no cationic polymer was prepared, and after application, the pretreatment agent was dried with a dryer for 10 minutes before inkjet printing. The composition of the pretreatment agent in Reference Example 1-1 is shown below. <Glue> Sodium alginate powder (manufactured by Tanaka Naosenten): 4.2% by mass <Dyeing agent> N-Alkylolamide (trade name "Sunflorene (registered trademark) SN", manufactured by Nicca Chemical Co., Ltd.): 4.5% by mass <Antifoaming agent> Alcohol-based (trade name "Antifoaming Agent", manufactured by Furukawa Chemical Co., Ltd., containing higher alcohol): 2.5% by mass <Preservative> Trade name "Neoguard" (manufactured by Furukawa Chemical Co., Ltd.): 0.5% by mass <Humectant> Glycerin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.): 0.5% by mass <Aqueous medium> Water: balance Furthermore, a water-based ink containing a black disperse dye was used. Except for drying for 10 minutes with a dryer after application of the pretreatment agent, the pretreatment, inkjet printing, steaming treatment after printing, and washing treatment were carried out in the same manner as in Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-3.

[0153] [Evaluation Test 1] The following evaluations were carried out on the evaluation fabrics that had been inkjet printed after the pretreatment of each example. The results are shown in Table 2.

[0154] <Bleeding Evaluation 1> The resistance to ink bleeding was evaluated as follows: The printed image pattern was visually observed from a position 30 cm away from the fabric, and a score of "Good" was given when the visibility of the grid intersections was as clear as in Reference Example 1-1, and a score of "Poor" was given when the visibility was inferior to Reference Example 1-1.

[0155] <Feel Evaluation 1> After the cleaning treatment, a color difference ΔE was measured for a portion of the fabric that had been coated with the pretreatment agent but not with ink, using a color difference meter (Spectro1, manufactured by Variable). A smaller ΔE value indicates less pretreatment agent remaining on the fabric after cleaning, and the absence of remaining pretreatment agent indicates that the fabric has a good feel. The way the fabric bent by hand was also checked. Specifically, whether creases were formed due to the presence of remaining pretreatment agent, or whether no creases were formed and the folded portion was rounded due to the absence of remaining pretreatment agent, was confirmed by using Reference Example 1-1 as a standard for determining whether creases were formed. From these experiments, whether the pretreatment agent had been washed away and the feel was good was determined using the following criteria. Good: ΔE is less than 2.0, and the folding is better than that of Reference Example 1-1. Bad: ΔE is 2.0 or more, and the folding is worse than that of Reference Example 1-1.

[0156]

[0157] As shown in Table 2, in Examples 1-1 to 1-8, even when inkjet printing was performed on the inkjet printouts that were not dried after pretreatment, there was no bleeding problem and the texture was good. On the other hand, in Comparative Example 1, in which the weight-average molecular weight of the N-vinylformamide-based cationic polymer was greater than 100,000, the texture was poor. Furthermore, in Comparative Examples 1-2 and 1-3, in which a cationic polymer that was not N-vinylformamide-based was used, bleeding or the texture was poor.

[0158] Test Example 2 In Test Example 2, the following raw materials were used.

[0159] [N-Vinylformamide-Based Cationic Polymer Synthesis Example 2] <Synthesis of N-Vinylformamide-Based Cationic Polymer: PVAM1> 100 g of N-vinylformamide, 23 g of demineralized water, and 1.38 g of sodium hypophosphite as a chain transfer agent for molecular weight control were added to prepare an aqueous monomer solution, which was then charged into a measuring vessel equipped with a nitrogen inlet tube. 169 g of demineralized water was charged into a reactor equipped with a stirrer, a nitrogen inlet tube, and a condenser. The aqueous solution was heated to 70°C, and then 13.8 mL of a 10% aqueous solution of 2,2'-azobis(2-methylpropionamidine) dihydrochloride was added and heated for 3 hours to obtain a poly(N-vinylformamide) polymer (PNVF). After polymerization was complete, the solution was cooled to room temperature and heated again to 60°C. 5.99 g of 35% aqueous hydrogen peroxide was added, and the mixture was allowed to stand for 1 hour to prevent insolubilization. To this solution, 0.005 mL of an antifoaming agent (SF-8417, amino-modified silicone oil, manufactured by Toray Industries, Inc.) and 66 g of a 48.5% aqueous solution of sodium hydroxide were added dropwise to modify some of the formamide groups to amino groups. Subsequently, 41.7 g of 35% hydrochloric acid was added to obtain PVAM1 (an N-vinylformamide-based cationic polymer aqueous solution). PVAM1 was an N-vinylformamide-based cationic polymer having the hydrochloride salt of the structural unit represented by formula (1) and the structural unit represented by formula (2). The content of structural unit (1), calculated from the amounts of raw material monomers used, was 55 mol%, and the content of structural unit (2) was 45 mol%.

[0160] <Synthesis of N-vinylformamide-based cationic polymer: PVAM2> PVAM2 was obtained in the same manner as in the production of PVAM1, except that the amount of sodium hypophosphite added was changed to 1.65 g.

[0161] <Synthesis of N-vinylformamide-based cationic polymer: PVAM3> PVAM3 was obtained in the same manner as in the production of PVAM1, except that the amount of sodium hypophosphite added was changed to 3.3 g.

[0162] <Synthesis of N-vinylformamide-based cationic polymer: PVAM4> PVAM4 was obtained in the same manner as in the production of PVAM1, except that the amount of sodium hypophosphite added was changed to 8.3 g.

[0163] <PNVF / PVAM Mixture 1> A mixture of poly-N-vinylformamide polymer (PNVF), which is an intermediate in the synthesis of the above-mentioned PVAM3, and PVAM4 was prepared in a weight ratio of 1:3.

[0164] <PNVF / PVAM Mixture 2> A mixture of poly-N-vinylformamide polymer (PNVF), which is an intermediate in the synthesis of the above-mentioned PVAM3, and PVAM4 was prepared in a 1 / 1 (weight ratio).

[0165] The weight average molecular weight and cationic degree were measured by the above-mentioned methods for the obtained PVAM1 to PVAM3 and PNVF / PVAM mixtures 1 and 2. The results are shown in Table 3 together with the value of (X × Y) / 1000 and the content of the structural unit of each cationic polymer.

[0166]

[0167] [Materials] In addition to the above-mentioned PVAMs 1 to 4 and PNVF / PVAM mixtures 1 and 2, the materials used in the examples and comparative examples of Test Example 2 are shown below.

[0168] <Moisturizing Agents> Ethylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point: 197.6°C) Dipropylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point: 231.8°C) Glycerin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point: 290°C)

[0169] <Antifoaming agent> Silicone type (product name "KM-90", manufactured by Shin-Etsu Chemical Co., Ltd., emulsion type, containing polydimethylsiloxane)

[0170] Examples 2-1 to 2-3 Preparation of Pretreatment Agents Pretreatment agents were prepared according to the compositions shown in Table 4. Specifically, each component was placed in a container, stirred for two hours using a stirrer, and then left to mature overnight. The numerical values ​​representing the content of each component in Table 4 are expressed in units of mass%, and each component other than the humectant is expressed as the content of the active ingredient (solid content) relative to 100% by mass of the total mass of the pretreatment agent. The content of the humectant is the content relative to 100% by mass of the total mass of the pretreatment agent. Water was added in an amount adjusted so that the total amount of the pretreatment agent was 100% by mass.

[0171] The pretreatment agent was applied to a cotton fabric using a commercially available cosmetic hand spray, and then smoothed with a squeegee to obtain a pretreated fabric. The amount of pretreatment agent applied was such that the amount dispensed with three pumps (approximately 0.37 g) would adhere to an area of ​​approximately 7 cm × 10 cm.

[0172] <Inkjet Printing Step> The fabric pretreated in the pretreatment step was transferred to an inkjet device (Inkjet Lab, manufactured by Cluster Technology Co., Ltd.) within 10 seconds of application of the pretreatment agent, i.e., before the applied pretreatment agent had dried, and ink was applied to the area where the pretreatment agent had been applied. A water-based ink containing a black reactive dye was used as the ink. A grid pattern was used as the printed image pattern. In the pattern, the grid size was 2 mm square and the line thickness was 0.2 mm.

[0173] <Heat Treatment Step> After the printing step, the fabric was subjected to a dry heat treatment at 100°C for 5 minutes, and then to a steam treatment at 105°C for 10 minutes using a HT steamer HT-3-550 manufactured by Tsujii Senki Kogyo Co., Ltd.

[0174] <Washing Step> The fabric after the heat treatment step was subjected to a soaping treatment at 100°C for 10 minutes using 1 g / L of a soaping agent (Senkanol TC Concentrate, manufactured by Senka Corporation) in water, and then rinsed with water to wash away the pretreatment agent and excess ink adhering to the fabric.

[0175] Examples 3-1 to 3-3 Preparation of Pretreatment Agents Pretreatment agents were prepared according to the compositions shown in Table 4. Specifically, each component was placed in a container, stirred for two hours using a stirrer, and then left to mature overnight. The numerical values ​​representing the content of each component in Table 4 are expressed in units of mass%, and each component other than the humectant is expressed as the content of the active ingredient (solid content) relative to 100% by mass of the total mass of the pretreatment agent. The content of the humectant is the content relative to 100% by mass of the total mass of the pretreatment agent. Water was added in an amount adjusted so that the total amount of the pretreatment agent was 100% by mass.

[0176] <Pretreatment Step> The pretreatment agent was applied to a cotton fabric using a micropipette and then smoothed with a squeegee to obtain a pretreated fabric. For the fabric used in the bleeding evaluation 2 described below, 100 μL of the pretreatment agent was applied to an area of ​​approximately 7 cm × 4 cm. For the texture evaluation 2 and color transfer test described below, 10 μL was applied to an area of ​​approximately 7 cm × 4 cm.

[0177] <Inkjet Printing Step> The fabric used for bleeding evaluation 2, which had been pretreated in the pretreatment step, was transferred to an inkjet device (Inkjet Lab, manufactured by Cluster Technology Co., Ltd.) within 10 seconds after application of the pretreatment agent, i.e., before the applied pretreatment agent had dried, and ink was applied to the area where the pretreatment agent had been applied. A water-based ink containing a reactive dye (cyan) was used as the ink. A grid pattern was used as the printed image pattern. In the pattern, the grid size was 2 mm square and the line thickness was 0.2 mm. For the fabric used for color transfer evaluation, 6 μL of the water-based ink was dropped using a micropipette onto the pretreated area of ​​the fabric pretreated in the pretreatment step in order to make the color transfer phenomenon more noticeable. Feeling evaluation 2 was performed using the fabric used for color transfer evaluation.

[0178] <Washing Step> The fabrics used in feel evaluation 2 and color transfer evaluation were washed with water for 6 minutes at 40 rpm using a mix rotor to wash away the pretreatment agent and excess ink adhering to the fabric.

[0179] [Evaluation Test 2] The following evaluations were carried out on the evaluation fabrics that had been inkjet printed after the pretreatment of each example. The results are shown in Table 4.

[0180] <Bleeding Evaluation 2> The resistance to ink bleeding was evaluated as follows. After the printing process, the printed image pattern was visually observed on the fabric from a distance of 30 cm. A clear appearance of the thin line portion was evaluated as "A", slight bleeding in the thin line portion was evaluated as "O", and significant bleeding in the thin line portion was evaluated as "X". A rating of "O" or higher was considered acceptable.

[0181] <Feel Evaluation 2> The way the fabric bent by hand after the washing step was checked. Specifically, if the pretreatment agent remained without being washed away, causing the fabric to become stiff and crease, it was rated as "X", and if the pretreatment agent did not remain, causing no crease and the folded part to become rounded, it was rated as "O".

[0182] <Color transfer evaluation> The fabric after the washing process was visually inspected to see if any dye was attached to areas where ink had not been applied in the printing process. For fabrics where dye was attached, the optical density (OD value) of the areas where dye was attached was measured using a spectrophotometer ("eXact Advanced" manufactured by X-rite). The higher the OD value, the more significant the color transfer. From the visual evaluation and the OD value, the resistance to color transfer was judged according to the following criteria: ◎: No dye attachment was observed in areas where ink had not been applied. ○: Dye attachment was observed in areas where ink had not been applied, but the OD value was 0.20 or less. △: Dye attachment was observed in areas where ink had not been applied, but the OD value was more than 0.20.

[0183] <Inkjet Discharge Properties of Pretreatment Agent> An inkjet discharge test of the pretreatment agent was conducted using the pretreatment agent of Example 3-1. An inkjet device (Inkjet Lab, manufactured by Cluster Technology Co., Ltd.) was used to fill the pretreatment agent, and continuous discharge was carried out for 20 minutes while adjusting the voltage so that the discharge speed was within the range of 4 m / s ± 5%. Observation of the droplets during discharge confirmed that there was no disturbance in the droplets, and that the inkjet discharge properties were excellent.

[0184]

[0185] As shown in Table 4, Examples 2-1 to 3-3, which are pretreatment agents of the present invention, were good in both bleeding and texture. Furthermore, it was found that by adjusting the relationship between the weight average molecular weight (X) and the cationic degree (Y) of the N-vinylformamide cationic polymer within a predetermined range, bleeding during printing and color transfer during washing can both be suppressed while maintaining the texture of the fabric.

[0186] According to the present invention, in inkjet printing of fabric using a dye ink, the ink is applied without drying after application of a pretreatment agent, thereby achieving improved productivity, reduced costs, energy savings, and space savings without impairing the texture.

[0187] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible within the scope of the invention. This application is based on Japanese Patent Application No. 2024-055830 filed on March 29, 2024, the entire contents of which are incorporated by reference.

Claims

1. A pretreatment agent for inkjet textile printing, comprising an N-vinylformamide cationic polymer having, as a structural unit, at least one structural unit selected from the group consisting of a structural unit represented by the following formula (1) and a salt thereof, and a structural unit represented by the following formula (2), wherein the weight-average molecular weight of the N-vinylformamide cationic polymer is 100,000 or less.

2. The ink-jet printing pretreatment agent according to claim 1, wherein the relationship of the following formula (I) is satisfied, where X is the weight-average molecular weight (Mw) of the N-vinylformamide cationic polymer and Y (meq / g) is the cationic degree of the N-vinylformamide cationic polymer: 150<(X×Y) / 1000<1200 (I).

3. The ink-jet printing pretreatment agent according to claim 1, wherein the cationic degree of the N-vinylformamide cationic polymer is 2.0 meq / g or more and 15.0 meq / g or less.

4. The ink-jet printing pretreatment agent according to claim 1, wherein the cationic degree of the N-vinylformamide cationic polymer is 6.0 meq / g or less.

5. The ink-jet printing pretreatment agent according to claim 1, wherein the cationic degree of the N-vinylformamide cationic polymer is 7.0 meq / g or more.

6. The inkjet textile printing pretreatment agent according to claim 1, wherein the content of the structural unit represented by formula (1) and the structural unit that is a salt thereof in the N-vinylformamide cationic polymer is 20 mol % or more and 80 mol % or less.

7. The ink-jet textile printing pretreatment agent according to claim 1, wherein the weight-average molecular weight of the N-vinylformamide cationic polymer is 90,000 or less.

8. The ink-jet printing pretreatment agent according to claim 1, wherein the weight-average molecular weight of the N-vinylformamide cationic polymer is 20,000 or more.

9. The ink-jet textile printing pretreatment agent according to claim 1, further comprising a moisturizing agent.

10. The ink-jet printing pretreatment agent according to claim 1, further comprising a defoaming agent.

11. The inkjet textile printing pretreatment agent according to claim 1, wherein the content of the N-vinylformamide cationic polymer is 0.5% by mass or more and 3.0% by mass or less, based on 100% by mass of the total mass of the inkjet textile printing pretreatment agent.

12. The ink-jet textile printing pretreatment agent according to claim 1, wherein the N-vinylformamide cationic polymer contains at least one member selected from the group consisting of polyamidines and polyvinylamines.

13. The ink-jet printing pretreatment agent according to claim 1, wherein the N-vinylformamide cationic polymer further comprises, as a structural unit, a structural unit represented by the following formula (3) or a salt thereof:

14. An ink set for inkjet textile printing, comprising the inkjet textile printing pretreatment agent according to any one of claims 1 to 13 and a water-based ink.

15. The ink set for ink-jet textile printing according to claim 14, wherein the water-based ink contains a disperse dye or a reactive dye.

16. An inkjet textile printing method comprising: a pretreatment step of pretreating a fabric with an inkjet textile printing pretreatment agent containing an N-vinylformamide-based cationic polymer having a weight-average molecular weight of 100,000 or less, the N-vinylformamide-based cationic polymer having at least one constituent unit selected from the group consisting of a constituent unit represented by the following formula (1) and a salt thereof, and a constituent unit represented by the following formula (2):

17. The ink-jet printing method according to claim 16, wherein in the pretreatment step, the ink-jet printing pretreatment agent is ejected onto the fabric by ink-jet printing.

18. The inkjet printing method according to claim 16, wherein the printing step includes inkjet printing the water-based ink in a wet-on-wet manner onto the pretreated area of ​​the fabric pretreated in the pretreatment step.

19. The ink-jet printing method according to claim 16, wherein the colorant is a disperse dye or a reactive dye.

20. The ink-jet printing method according to claim 16, wherein the fabric is a fabric containing cotton or polyester fibers.

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