Inkjet printing method

Abstract

To provide an inkjet printing method which can obtain a printed matter that is excellent in image quality and durability against external stress such as rubbing, even if the printed matter is a fabric having low permeability.SOLUTION: An inkjet printing method includes a printing step of printing an ink composition containing a pigment, a polycarbonate-based polyurethane resin, a block isocyanate compound, a water-soluble organic solvent and water onto a fabric having a temperature of a part where the ink composition impacts of 40°C or higher by inkjet, wherein the polycarbonate-based polyurethane resin does not have a block isocyanate structure in the molecule, and has a functional group reactive with an isocyanate group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an inkjet printing method.

Background Art

[0002] Printing is a coloring method of directly applying colors or patterns to fabrics. Screen printing method and roller printing method are widely used. In recent years, an inkjet printing method using inkjet printing has been studied. The printing method by inkjet printing has the advantage that by using a method of ejecting ink droplets and attaching them to the fabric for printing, a high-definition and high-quality image can be formed on the fabric without requiring skill. Also, unlike the conventional method, it does not require plate making, so it is easy to handle small-lot and multi-variety production. Furthermore, since only the amount of ink required for image formation is used, it also has the feature of having a minor impact on the environment.

[0003] As printing inks, there are dye inks and pigment inks. Pigment inks are advantageous compared to dye inks in that they have high light resistance and do not require post-treatment such as washing after printing. However, unlike dye inks that can be bound to fabrics by chemical bonding between dye molecules and fabrics, pigment inks have poor binding force between pigment particles and fabrics. Therefore, when the printed area is subjected to an external force, they have the demerit of having low resistance to it. Also, since the ink flows until it is fixed on the fabric, there are problems of image bleeding and color mixing.

[0004] Therefore, various proposals have been made as methods for improving the durability and the like of printed materials in inkjet printing using pigment inks. For example, in Patent Document 1, an inkjet ink composition for printing, which includes a pigment, a water-dispersible resin, a crosslinking agent, and water, is disclosed, with the problem of achieving both good washing fastness and texture. The water-dispersible resin has specific tensile properties, and the ratios of the water-dispersible resin to the pigment or the crosslinking agent are respectively within specific ranges. Furthermore, Patent Document 2 discloses a pigment printing inkjet recording method that uses a pigment printing inkjet ink composition containing a pigment, resin particles, an organic solvent, and water, wherein the organic solvent contains an amide compound, with the objective of providing a pigment printing inkjet recording method that exhibits excellent color development on various fabrics. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-31611 [Patent Document 2] Japanese Patent Publication No. 2019-167486 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Patent Document 1 describes an inkjet printing method for 100% cotton fabric into which the solvent components of the ink can penetrate. However, for fabrics other than cotton, the durability against external stresses such as abrasion was not sufficient. In the embodiment described in Patent Document 2, an impression is produced by inkjet printing on a low-permeability polyester fabric to which the solvent components of the ink do not easily penetrate. However, the durability against external stresses such as abrasion on a low-permeability fabric to which the solvent components of the ink do not easily penetrate was not sufficient. The present invention relates to an inkjet printing method that can produce printed materials with excellent image quality and superior durability against external stresses such as abrasion, even when the printing medium is a low-permeability fabric. [Means for solving the problem]

[0007] The present inventors have found that the above problem can be solved by using an ink composition containing a pigment, a polycarbonate-based polyurethane resin having a specific structure, a blocked isocyanate compound, a water-soluble organic solvent, and water, and printing the ink composition onto a fabric where the temperature of the area where the ink composition lands is 40°C or higher using an inkjet printer. The present invention relates to the following [1]. [1] An inkjet printing method comprising a printing step of printing an ink composition containing a pigment, a polycarbonate polyurethane resin, a blocked isocyanate compound, a water-soluble organic solvent, and water onto a fabric where the temperature of the area where the ink composition lands is 40°C or higher, wherein the polycarbonate polyurethane resin does not have a blocked isocyanate structure in its molecule and has functional groups that can react with isocyanate groups. [Effects of the Invention]

[0008] According to the present invention, an inkjet printing method is available that can produce printed materials with excellent image quality and superior durability against external stresses such as abrasion, even when the printing medium is a low-permeability fabric. [Modes for carrying out the invention]

[0009] [Inkjet Printing Method] The present invention provides an inkjet printing method comprising a printing step of printing an ink composition containing a pigment, a polycarbonate-based polyurethane resin, a blocked isocyanate compound, a water-soluble organic solvent, and water onto a fabric where the temperature of the area to which the ink composition lands is 40°C or higher, wherein the polycarbonate-based polyurethane resin does not have a blocked isocyanate structure in its molecule and has functional groups that can react with isocyanate groups. The ink composition used in this invention may be simply referred to as "ink composition" or "ink." In this specification, "impact" means that the ink composition adheres to the printing medium by inkjet printing. In this specification, "printed material" means a printed material on which an ink composition has been applied (printed) onto the surface of a fabric, which is a printing medium, to form an image.

[0010] According to the inkjet printing method of the present invention, even when the printing medium is a low-permeability fabric such as polyester, nylon, or polyurethane, it is possible to obtain printed materials with excellent image quality and excellent durability against external stress such as abrasion. The reason for this is not entirely clear, but it is thought to be as follows. In the inkjet printing method of the present invention, a blocked isocyanate compound is contained in the ink composition, and furthermore, the area where the ink lands on the fabric is at a temperature of 40°C or higher. Therefore, the crosslinking reaction of the polycarbonate-based polyurethane resin by the blocked isocyanate compound is rapidly initiated, and the ink composition rapidly thickens after landing, suppressing the mixing and bleeding of ink dots, thus improving the image quality of the resulting print. Furthermore, in the inkjet printing method of the present invention, the polycarbonate-based polyurethane resin does not have a blocked isocyanate structure within its molecule, and the polycarbonate-based polyurethane resin and the blocked isocyanate compound coexist as separate components. Therefore, the polycarbonate-based polyurethane resin can form intermolecular crosslinks with molecular chains other than its own, via components derived from the blocked isocyanate compound, thereby forming a larger resin structure. As a result, the effect of improving the durability of the coating film is enhanced, and it is believed that printed materials with superior resistance to external stresses such as abrasion can be obtained. Furthermore, the polycarbonate-based polyurethane resin contained in the ink composition of the present invention has carbonate groups in its structure that have high polarity comparable to that of urethane groups. Therefore, when a fabric containing polyurethane is used as the printing medium, the adhesion between the resin and the fabric is improved, and it is possible to obtain a print with high friction fastness compared to when polyether-based polyurethane resin or polyester-based polyurethane resin is used, resulting in a print with excellent durability.

[0011] Furthermore, according to the inkjet printing method of the present invention, when artificial leather or synthetic leather having a surface resin layer containing polyurethane is used as the printing medium, among fabrics containing polyurethane, a printed material with superior image quality and superior durability against external stress such as abrasion can be obtained. The reason for this is presumed to be as follows. Generally, in artificial leather and synthetic leather having a surface resin layer containing polyurethane, the solvent components of the ink hardly penetrate into the printing medium. Therefore, the entanglement of coloring agents and their binding components with the fibers, which can easily occur in ordinary fabrics, is not expected. Consequently, with conventional printing methods, the resulting prints tend to be susceptible to external forces. On the other hand, in the present invention, since the polycarbonate-based polyurethane resin contained in the ink composition forms a cross-linked structure with a blocked isocyanate compound on the fabric after inkjet printing, the durability of the coating film can be increased, and the durability against external stresses such as abrasion of the printed material can be improved.

[0012] Ink Composition In the inkjet printing method of the present invention, the ink composition contains a pigment, a polycarbonate-based polyurethane resin, a blocked isocyanate compound, a water-soluble organic solvent, and water.

[0013] <Pigments> In the present invention, the pigment may be either an inorganic pigment or an organic pigment. Examples of inorganic pigments include carbon black and metal oxides. For black inks, carbon black is preferred. Examples of carbon black include furnace black, thermal black, acetylene black, and channel black. For white inks, examples of metal oxides include titanium dioxide, zinc oxide, silica, alumina, and magnesium oxide, with titanium dioxide being preferred among these. Examples of organic pigments include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, and the like. The hue is not particularly limited, and in the case of colored inks, any of colored pigments such as yellow, magenta, cyan, red, blue, orange, and green can be used. The above pigments can be used alone or in combination of two or more.

[0014] In the present invention, the pigment may be in a form dispersed by a resin or a surfactant having pigment dispersibility as a dispersant, or in a form of a self-dispersing pigment dispersed without using a dispersant. Among these, from the viewpoint of improving the image quality of the printed matter and the durability against external stress, the pigment is preferably in the form of resin particles containing the pigment (hereinafter also referred to as "pigment-containing resin particles"). In the present invention, the resin particles containing a pigment are particles composed of the pigment and a resin having pigment dispersibility (hereinafter also referred to as "pigment-dispersing resin"), in which the pigment-dispersing resin contains the pigment, particles composed of the pigment-dispersing resin and the pigment, in which a part of the pigment is exposed on the surface of the particles, or particles in which the pigment-dispersing resin is adsorbed to a part of the pigment, or a mixture thereof.

[0015] (Pigment-dispersing resin) The pigment-dispersing resin is a resin having pigment dispersibility for dispersing a pigment in an aqueous medium mainly composed of water. Examples of the pigment-dispersing resin include vinyl-based polymers, polyester-based polymers, polyurethane-based polymers, and the like. Among these, from the viewpoint of improving the image quality of the printed matter and the durability against external stress, vinyl-based resins obtained by addition polymerization of vinyl monomers such as vinyl compounds, vinylidene compounds, and vinylene compounds are preferred. The pigment-dispersing resin preferably has an ionic group from the viewpoint of improving the image quality of the printed matter and the durability against external stress. When the pigment-dispersing resin is a vinyl resin, the ionic group is preferably introduced into the skeleton of the pigment-dispersing resin by an ionic vinyl monomer having an ionic group (hereinafter also referred to as "ionic monomer" or "(a-1) component"). In addition, the pigment-dispersing resin preferably has a hydrophobic group. When the pigment-dispersing resin is a vinyl resin, the hydrophobic group is preferably introduced into the skeleton of the pigment-dispersing resin by a hydrophobic vinyl monomer having a hydrophobic group (hereinafter also referred to as "hydrophobic monomer" or "(a-2) component") from the same viewpoint as above. That is, in the present invention, the pigment-dispersing resin is preferably a vinyl resin containing a structural unit derived from an (a-1) ionic monomer and a structural unit derived from an (a-2) hydrophobic monomer. From the same viewpoint as above, the pigment-dispersing resin can further have a nonionic group. When the pigment-dispersing resin is a vinyl resin, the nonionic group can be introduced into the skeleton of the pigment-dispersing resin by a nonionic vinyl monomer having a nonionic group (hereinafter also referred to as "nonionic monomer" or "(a-3) component").

[0016] [(a-1) component] Examples of the (a-1) component include both anionic and cationic ones, but an anionic one is preferable. As the ionic group that exhibits anionic properties, an acid group is preferable, and as the acid group, a carboxylic acid group is preferable. Specific examples of the (a-1) component include those described in paragraph

[0017] of JP-A-2018-80255. Among them, one or more selected from acrylic acid and methacrylic acid are preferable. In the present invention, it is preferable that part or all of the ionic groups introduced by the (a-1) component of the pigment-dispersing resin constituting the pigment-containing resin particles are neutralized by a basic compound or an acidic compound. If the pigment-dispersing resin is in a neutralized state, the pigment-dispersing resin is ionic and can disperse the pigment in an aqueous medium.

[0017] [(a-2) component] (a-2) The hydrophobicity of component (a-2) means that when the monomer is dissolved in 100g of ion-exchanged water at 25°C until saturated, the amount of dissolved monomer is less than 10g, preferably 5g or less, and more preferably 1g or less. (a-2) The hydrophobic group of component (a-2) is preferably one or more selected from the group consisting of alkyl groups, aromatic groups, and silicone groups. (a-2) The component is preferably one or more selected from the group consisting of alkyl (meth)acrylate, aromatic group-containing monomer, aromatic group-containing macromonomer, and silicone-based macromonomer, more preferably one or more selected from the group consisting of aromatic group-containing monomer and aromatic group-containing macromonomer, and even more preferably an aromatic group-containing monomer. (a-2) Specific examples of the component include those described in paragraph

[0018] of Japanese Patent Publication No. 2018-80255. Among these, one or more selected from the group consisting of styrene, α-methylstyrene and other styrene monomers, benzyl (meth)acrylate, and styrene macromers are preferred, styrene monomers are more preferred, and one or more selected from the group consisting of styrene and α-methylstyrene are even more preferred.

[0018] [(a-3) component] (a-3) Examples of nonionic groups in component (a-3) include hydroxyl groups and polyoxyalkylene groups. (a-3) The component is preferably one or more selected from the group consisting of hydroxyalkyl (meth)acrylate, polyalkylene glycol (meth)acrylate, alkoxy polyalkylene glycol (meth)acrylate, and phenoxy polyalkylene glycol (meth)acrylate. (a-3) Specific examples of the component include those described in paragraph

[0022] of Japanese Patent Publication No. 2018-80255. Among these, one or more selected from polyethylene glycol (n=2~30) (meth)acrylate and phenoxy (ethylene glycol / propylene glycol copolymer) (meth)acrylate are preferred. The above components (a-1) to (a-3) can each be used by using the monomer components contained in each component individually or in combination of two or more.

[0019] Furthermore, if the pigment dispersion resin has a functional group that can react with isocyanate groups, the pigment dispersion resin in the ink composition is also crosslinked, which can further improve the durability of the coating film and produce an impression with superior resistance to external stress. The functional group is preferably one or more selected from the group consisting of hydroxyl groups, carboxyl groups, and amino groups, and more preferably one or more selected from the group consisting of hydroxyl groups and carboxyl groups. The functional group is included in one or more selected from the group consisting of components (a-1) and (a-3), and can be introduced into the backbone of the pigment dispersion resin by these components.

[0020] (Content of each constituent unit in the pigment dispersion resin) The content of constituent units derived from components (a-1) to (a-3) in the pigment dispersion resin is as follows, from the viewpoint of improving the dispersion stability of pigment-containing resin particles. The content of component (a-1) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. The content of component (a-2) is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. (a-3) If component is present, its content is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less. The mass ratio of component (a-1) to component (a-2) [(a-1) / (a-2)] is preferably 0.1 or more, more preferably 0.2 or more, and preferably 1.2 or less, more preferably 1.0 or less, and even more preferably 0.8 or less.

[0021] In the present invention, the content of constituent units derived from components (a-1) to (a-3) in the pigment dispersion resin can be determined by measurement, or it can be substituted by the charging ratio of raw material monomers containing components (a-1) to (a-3) during the production of the pigment dispersion resin.

[0022] (Manufacturing of pigment-dispersing resins) When the pigment dispersion resin is a vinyl resin, it can be produced by polymerizing components (a-1) to (a-3) by known methods. Specifically, the manufacturing procedure described in paragraphs

[0027] to

[0028] of Japanese Patent Application Publication No. 2018-80255 is preferred.

[0023] The weight-average molecular weight of the pigment-dispersing resin is preferably 6,000 or more, more preferably 8,000 or more, even more preferably 10,000 or more, and preferably 300,000 or less, more preferably 100,000 or less, even more preferably 50,000 or less, and even more preferably 30,000 or less, from the viewpoint of improving the dispersion stability of the pigment-containing resin particles. The weight-average molecular weight of the pigment-dispersed resin is measured by the method described in the examples.

[0024] From the viewpoint of improving the dispersion stability of pigment-containing resin particles, the acid value of the pigment dispersion resin is preferably 100 mg KOH / g or more, more preferably 150 mg KOH / g or more, even more preferably 200 mg KOH / g or more, and preferably 350 mg KOH / g or less, more preferably 300 mg KOH / g or less, and even more preferably 270 mg KOH / g or less. The acid value of a pigment-dispersed resin can be calculated from the mass ratio of its constituent monomers.

[0025] Commercially available pigment dispersion resins may be used. Examples of commercially available pigment dispersion resins include styrene / acrylic resins such as "Joncryl 67," "Joncryl 611," "Joncryl 678," "Joncryl 680," "Joncryl 690," and "Joncryl 819" (all manufactured by BASF Japan Ltd.).

[0026] In the present invention, the pigment dispersion resin constituting the pigment-containing resin particles (pigment-containing resin particles) is preferably one that has a crosslinked structure in at least a portion of it. In the present invention, the pigment dispersion resin having a crosslinked structure is preferably one that further contains, in addition to the constituent units derived from component (a-1), component (a-2), and optionally component (a-3), a compound having two or more functional groups that can react with component (a-1), i.e., a component derived from a crosslinking agent. In the present invention, the amount of crosslinking agent-derived components in the pigment dispersion resin constituting the pigment-containing resin particles can be calculated from the amount of resin used during its production.

[0027] In the present invention, when the pigment dispersion resin constituting the pigment-containing resin particles has a crosslinked structure, it is preferable that the pigment-containing resin particles are prepared using the above-mentioned pigment, pigment dispersion resin, and crosslinking agent.

[0028] Specific examples of crosslinking agents include those described in paragraph

[0041] of Japanese Patent Publication No. 2018-80255. Among these, water-insoluble compounds are preferred, polyglycidyl ether compounds of polyhydric alcohols having hydrocarbon groups with 3 to 8 carbon atoms are more preferred, one or more selected from the group consisting of pentaerythritol polyglycidyl ether and trimethylolpropane polyglycidyl ether are even more preferred, and trimethylolpropane polyglycidyl ether is even more preferred.

[0029] In the present invention, the ratio of the molar equivalents of the crosslinking functional groups of the crosslinking agent to the molar equivalents of the ionic groups of the pigment dispersion resin, i.e., the crosslinking rate, is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less.

[0030] When the pigment dispersion resin constituting the pigment-containing resin particles has a cross-linked structure, the acid value of the pigment dispersion resin is preferably 50 mg KOH / g or more, more preferably 55 mg KOH / g or more, even more preferably 60 mg KOH / g or more, and preferably 175 mg KOH / g or less, more preferably 150 mg KOH / g or less, and even more preferably 135 mg KOH / g or less, from the viewpoint of improving the dispersion stability of the pigment-containing resin particles. When the pigment dispersion resin constituting the pigment-containing resin particles has a crosslinked structure, the acid value of the pigment dispersion resin can be calculated from the mass ratio of the pigment dispersion resin and the crosslinking agent used.

[0031] In the present invention, the mass ratio of the pigment dispersion resin to the pigment constituting the pigment-containing resin particles [content of pigment dispersion resin / content of pigment] is preferably 0.25 or higher, more preferably 0.30 or higher, even more preferably 0.35 or higher, and preferably 0.70 or lower, more preferably 0.60 or lower, and even more preferably 0.50 or lower, from the viewpoint of improving the dispersion stability of the pigment-containing resin particles.

[0032] [Manufacturing of resin particles containing pigments] Pigment-containing resin particles can be manufactured by any known method. Specifically, the manufacturing procedure described in paragraphs

[0030] to

[0039] of Japanese Patent Application Publication No. 2018-80255 is preferred.

[0033] <Polycarbonate-based polyurethane resin> In the present invention, the ink composition contains a polycarbonate-based polyurethane resin from the viewpoint of obtaining a printed product with excellent image quality and durability against external stress. Furthermore, from the viewpoint of obtaining a printed product with even greater durability against external stress, the polycarbonate-based polyurethane resin may be included as a pigment-dispersing resin constituting the aforementioned pigment-containing resin, or it may be included in the form of resin particles that do not contain pigment, but it is preferable that it be in the form of resin particles that do not contain pigment. In the present invention, "pigment-free resin particles" means that the resin has the function of maintaining a dispersed state in the ink by itself, but does not have the function of maintaining a dispersed state of pigment in the ink.

[0034] In the present invention, the polycarbonate-based polyurethane resin does not have a blocked isocyanate structure within its molecule. That is, in the present invention, the polycarbonate-based polyurethane resin is not self-crosslinkable. Furthermore, in the present invention, it is preferable that the polycarbonate-based polyurethane resin does not contain crosslinkable groups such as isocyanate groups within its molecule.

[0035] Furthermore, in the present invention, the polycarbonate-based polyurethane resin has a functional group that can react with an isocyanate group. Preferably, the functional group is one or more selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group, and more preferably, one or more selected from the group consisting of a hydroxyl group and a carboxyl group. Furthermore, in the present invention, it is preferable that the polycarbonate-based polyurethane resin has a functional group in its molecule that can react with an isocyanate group.

[0036] In the present invention, polycarbonate-based polyurethane resin means a polyurethane resin that contains a component having a polycarbonate structure. In the present invention, a polycarbonate-based polyurethane resin can be obtained by a polyaddition reaction between a polycarbonate polyol and a polyisocyanate. Alternatively, a commercially available polycarbonate-based polyurethane resin may be used in the present invention.

[0037] Polycarbonate polyols can be obtained by reacting a carbonate compound with a diol. Examples of carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, and diethylene carbonate. Examples of diols include aliphatic diols which may be substituted with lower alcohols; alicyclic diols such as cyclohexanediol and hydrogenated xylylene glycol; and aliphatic diols having aromatic rings such as xylylene glycol.

[0038] Examples of polyisocyanates include chain-like aliphatic diisocyanates such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate; cyclic aliphatic diisocyanates such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate; aromatic ring-containing aliphatic diisocyanates such as xylylene diisocyanate and tetramethylxylylene diisocyanate; aromatic diisocyanates such as tolylene diisoanate and diphenylmethane diisocyanate; and modified products of these diisocyanates (such as modified products containing carbodiimide, uretodione, and uretoimine). Among these, preferably one or more selected from aliphatic diisocyanates and aromatic diisocyanates, more preferably aliphatic diisocyanates, and among aliphatic diisocyanates, preferably 1,6-hexamethylene diisocyanate.

[0039] From the viewpoint of improving dispersion stability in the ink composition, the polycarbonate-based polyurethane resin is preferably an anionic polycarbonate-based polyurethane resin having anionic groups. Examples of anionic groups include carboxyl groups, sulfonic acid groups, and phosphate groups, but carboxyl groups are preferred. Polycarbonate-based polyurethane resins having carboxyl groups can be obtained by polyaddition reactions of polycarbonate, polyisocyanate, and dialkanolcarboxylic acid. Examples of such dialkanolcarboxylic acids include dimethylolbutanoic acid, dimethylolpropionic acid, and their salts.

[0040] When a polycarbonate-based polyurethane resin has anionic groups, it is preferable that at least a portion of these anionic groups are neutralized with a neutralizing agent. This increases the charge repulsion force that emerges after neutralization, thereby improving the dispersion stability in the ink. Both organic and inorganic bases can be used as the neutralizing agent. Examples of organic bases include alkylamines such as butylamine and triethylamine; alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine; and morpholine. Examples of inorganic bases include ammonia and sodium hydroxide.

[0041] Examples of reaction solvents for the polyaddition reaction include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, ethyl acetate, toluene, and xylene. In the polyaddition reaction, chain extenders and reaction stoppers may be used in combination as needed. The molecular weight can be further increased by using chain extenders. Examples of chain extenders include polyols and polyamines, and examples of reaction stoppers include monoalcohols and monoamines. Polycarbonate-based polyurethane resins are preferably used as emulsions, and these emulsions may optionally contain dispersants such as surfactants.

[0042] The weight-average molecular weight of the polycarbonate-based polyurethane resin is preferably 100,000 or more, more preferably 200,000 or more, even more preferably 300,000 or more, and preferably 2,500,000 or less, more preferably 1,000,000 or less, and even more preferably 600,000 or less, from the viewpoint of improving dispersion stability in the ink composition and improving durability of the printed material against external stress. The acid value of the polycarbonate-based polyurethane resin is preferably 5 mg KOH / g or more, more preferably 10 mg KOH / g or more, even more preferably 15 mg KOH / g or more, and preferably 60 mg KOH / g or less, more preferably 50 mg KOH / g or less, and even more preferably 40 mg KOH / g or less, from the viewpoint of improving dispersion stability in the ink composition and improving durability of the printed material against external stress.

[0043] Examples of commercially available polycarbonate-based polyurethane resins include Superflex 460, 420, 470, and 460S from Daiichi Kogyo Seiyaku Co., Ltd.; Takelac W-635, W-6010, and W-6110 from Mitsui Chemicals, Inc.; HUX-386 and HUX-561S from ADEKA Corporation; NeoRez R-986 from Kusumoto Kasei Co., Ltd.; and Impranil DLC-F, DL2077, DLV1, and DLU from Sumika Covestro Urethane Co., Ltd.

[0044] [Other resins] In the present invention, the ink composition may contain resins other than polycarbonate polyurethane resins (hereinafter also referred to as "other resins") to the extent that they do not impair the effects of the present invention. In the present invention, if the pigment is in the form of resin particles containing the pigment, the resin constituting the resin particles containing the pigment is not included in the other resins. Other resins include polyester-based polyurethane resins, polyether-based polyurethane resins, acrylic resins, and styrene-acrylic resins.

[0045] In the ink composition of the present invention, the mass ratio of the polycarbonate polyurethane resin content to the total content of the polycarbonate polyurethane resin and the other resins [polycarbonate polyurethane resin content / total content of polycarbonate polyurethane resin and other resins] is preferably 75% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass, from the viewpoint of not impairing the effects of the present invention.

[0046] <Blocked isocyanate compounds> In the present invention, the ink composition contains a blocked isocyanate compound from the viewpoint of obtaining a printed material with excellent durability against external stress. Blocked isocyanate compounds are compounds obtained by blocking the isocyanate groups in a polyisocyanate compound with a blocking agent. Blocked isocyanate compounds are stabilized at room temperature by the binding of the protecting group (blocking agent) to the highly reactive isocyanate group, preventing reaction. However, heating after inkjet printing dissociates this protecting group, allowing the isocyanate group to become reactive. This crosslinks the resin component having a functional group that can react with the isocyanate group in the ink composition, improving the durability of the coating film. As a result, printed materials with excellent resistance to external stress can be obtained.

[0047] Polyisocyanate compounds are compounds having two or more isocyanate groups in one molecule. Examples of polyisocyanate compounds include aliphatic polyisocyanates, alicyclic polyisocyanates, aliphatic polyisocyanates having aromatic rings, aromatic polyisocyanates, and modified versions thereof. Examples of modified polyisocyanate compounds include polymers such as isocyanurates; biuret compounds; and adduct compounds with polyhydric alcohols such as trimethylolpropane and pentaerythritol.

[0048] As the aliphatic polyisocyanate, diisocyanates having a linear or branched aliphatic hydrocarbon group between two isocyanate groups are preferred. The number of carbon atoms in the aliphatic hydrocarbon group is preferably 2 or more, more preferably 3 or more, and preferably 12 or less, more preferably 10 or less, even more preferably 9 or less, and even more preferably 8 or less. Specifically, examples include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), heptamethylene diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, and 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate. Examples of alicyclic polyisocyanates include hydrogenated xylylene diisocyanate (H6XDI), 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (H12MDI), isophorone diisocyanate (IPDI), and 2,5- or 2,6-norbornane diisocyanate. Examples of aliphatic polyisocyanates having an aromatic ring include m- or p-xylylene diisocyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI). Examples of aromatic polyisocyanates include 1,3- or 1,4-phenylenediisocyanate, 2,4- or 2,6-tolylenediisocyanate (TDI), 4,4'- or 2,4'-diphenylmethanediisocyanate (MDI), m- or p-isocyanatophenylsulfonyl isocyanate, 4,4'-diisocyanatobiphenyl, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 1,5-naphthylenediisocyanate, and 2,6-dimethylbenzene-1,4-diisocyanate. Among these, the polyisocyanate compound is preferably one or more selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates, and modified versions thereof; more preferably one or more selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates, and polymers thereof; and even more preferably a polymer of aliphatic polyisocyanate or alicyclic polyisocyanate.

[0049] While compounds such as 3,5-dimethylpyrazole, methyl ethyl ketoxime, and ε-caprolactam are used as blocking agents for blocked isocyanate compounds, 3,5-dimethylpyrazole is preferred from the viewpoint of stability at room temperature, reactivity at the coating film drying temperature, and the safety of the dissociated blocking agent.

[0050] The dissociation temperature of the blocked isocyanate compound is preferably 90°C or higher, more preferably 100°C or higher, from the viewpoint of improving the durability of the printed material against external stress, and preferably 200°C or lower, more preferably 180°C or lower, even more preferably 160°C or lower, even more preferably 140°C or lower, and even more preferably 130°C or lower, from the viewpoint of suppressing damage such as deformation of the fabric. The isocyanate group equivalent of the blocked isocyanate compound is preferably 300 or more, more preferably 500 or more, even more preferably 700 or more, and preferably 4,000 or less, more preferably 3,000 or less, even more preferably 2,000 or less, even more preferably 1,500 or less, and even more preferably 1,200 or less, from the viewpoint of improving the durability of the printed material against external stress. The isocyanate group equivalent refers to the mass of the blocked isocyanate compound per mole of isocyanate groups.

[0051] Commercially available blocked isocyanate compounds using 3,5-dimethylpyrazole as a blocking agent include Trixene Aqua BI200 and BI220 from GSI Creos Corporation, and Byhijur BL2867 and Byhijur BL xp 2706 from Sumika Covestro Urethane Co., Ltd.

[0052] <Water-soluble organic solvent> In the present invention, the ink composition contains a water-soluble organic solvent. In this invention, "water-soluble organic solvent" means an organic solvent that can be mixed with water in any proportion. Water-soluble organic solvents are used to improve the image quality and durability against external stress of the printed material by exhibiting appropriate affinity with the resin constituting the printed material, thereby promoting the formation of a resin film. From the above viewpoint, it is preferable that the water-soluble organic solvent contains one or more selected from the group consisting of alkylene glycols and polyalkylene glycols.

[0053] The alkylene glycol is preferably an aliphatic diol having 2 to 6 carbon atoms, more preferably one or more selected from the group consisting of propylene glycol, 1,2-butanediol, and 1,3-butanediol, and even more preferably propylene glycol. In the present invention, "polyalkylene glycol" means a compound having a structure in which alkylene glycols are condensed. Suitable examples of polyalkylene glycols include diethylene glycol, triethylene glycol, and dipropylene glycol, with dipropylene glycol being more preferred.

[0054] From the above viewpoint, the water-soluble organic solvent may contain alkylene glycol alkyl ethers. Examples of alkylene glycol alkyl ethers include alkylene glycol monoalkyl ethers, which have 1 to 6 carbon atoms in the alkyl group, preferably 3 to 6 carbon atoms. Suitable examples of alkylene glycol monoalkyl ethers include ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether. In the present invention, water-soluble organic solvents can be used alone or as a mixture of two or more.

[0055] <Water> In the present invention, the ink composition contains water. In the present invention, it is preferable that the ink composition is a so-called water-based ink in which water accounts for the largest proportion by mass.

[0056] <Surfactants> In the present invention, the ink composition preferably contains a surfactant from the viewpoint of ensuring good adhesion between the printing medium and the ink dots and improving the image quality of the printed material. As the surfactant, a nonionic surfactant is preferred, and one or more selected from the group consisting of silicone-based surfactants and acetylene glycol-based surfactants is more preferred.

[0057] As for the silicone-based surfactant, from the viewpoint of allowing the printing medium and ink dots to blend well and improving the image quality of the printed material, the HLB value is preferably 5 or higher, more preferably 6 or higher, and preferably 12 or lower, more preferably 11 or lower, and even more preferably 10 or lower. As for acetylene glycol-based surfactants, it is preferable to use in combination a surfactant with an HLB value of preferably 2 or higher, more preferably 3 or higher, and preferably 18 or lower, more preferably 16 or lower, and even more preferably 14 or lower, from the viewpoint of allowing the printing medium and ink dots to blend well and improving the image quality of the printed material, and a surfactant with an HLB value of preferably 3 or higher, more preferably 4 or higher, and preferably 7 or lower, and even more preferably 6 or lower, from the viewpoint of allowing ink droplets to be ejected well. Furthermore, it is more preferable to use a combination of at least two acetylene glycol-based surfactants, each with different HLB values, and at least one of the silicone-based surfactants mentioned above.

[0058] The HLB value is the Hydrodrophile-Lipophile Balance according to Griffin, and it represents the degree of affinity of a surfactant to water and oil. The definition of the HLB value is described in WCGriffin: J.Soc.Comestic Chemists, 1,311 (1949), and in "Surfactant Handbook," 3rd edition, published by Koshimi Takahashi, Yoshiro Nanba, Motoo Koike, and Masao Kobayashi, published November 25, 1972, pp. 179-182. It is also listed in surfactant catalogs.

[0059] Commercially available silicone-based surfactants include the "Silface" series from Nisshin Chemical Industry Co., Ltd., the "KF" series from Shin-Etsu Chemical Co., Ltd., and the "BYK" series from Big Chemie Inc. Commercially available acetylene glycol-based surfactants include the "Surfinol" series and "Orfin" series from Nisshin Chemical Industry Co., Ltd., and the "Acetylenel" series from Kawaken Fine Chemical Co., Ltd.

[0060] [Manufacturing of ink compositions] In the present invention, the ink composition can be efficiently produced by mixing a pigment, a polycarbonate-based polyurethane resin, a blocked isocyanate compound, a water-soluble organic solvent, water, and, if necessary, a surfactant. There are no particular restrictions on the method of mixing these components. The pigment is preferably mixed in the form of a pigment-dispersing resin or surfactant, or in the form of a self-dispersing pigment dispersed without the use of a dispersant, and more preferably in the form of resin particles containing the pigment.

[0061] [Content of each component in the ink composition] In the present invention, the content and mass ratio of each component of the ink composition are as follows, from the viewpoint of improving the image quality of the printed material and its durability against external stress.

[0062] (Pigment content) In the present invention, the pigment content in the ink composition is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and preferably 12% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less.

[0063] (Content of pigment-containing particles) In the present invention, when the pigment is in the form of pigment-containing resin particles, the content of pigment-containing resin particles in the ink composition is preferably 2% by mass or more, more preferably 3% by mass or more, even more preferably 4% by mass or more, and preferably 10% by mass or less, more preferably 9% by mass or less, and even more preferably 8% by mass or less.

[0064] (Polycarbonate polyurethane resin content) In the present invention, the content of polycarbonate-based polyurethane resin in the ink composition is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 4% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less.

[0065] In the present invention, when the pigment in the ink composition is in the form of pigment-containing resin particles, the mass ratio of pigment-containing resin particles to polycarbonate-based polyurethane resin [content of pigment-containing resin particles / content of polycarbonate-based polyurethane resin] is preferably 0.5 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and preferably 3 or less, more preferably 2.5 or less, even more preferably 2 or less, even more preferably 1.5 or less, and even more preferably 1 or less.

[0066] In the present invention, the mass ratio of the total amount of resin to the pigment in the ink composition [total resin content in the ink composition / pigment content] is preferably 1 or more, more preferably 1.2 or more, even more preferably 1.5 or more, and preferably 10 or less, more preferably 6 or less, even more preferably 4 or less, and even more preferably 3 or less.

[0067] (Content of blocked isocyanate compounds) In the present invention, the content of the blocked isocyanate compound in the ink composition is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.7% by mass or more, and even more preferably 0.9% by mass or more, and preferably 5% by mass or less, more preferably 4% by mass or less, even more preferably 3% by mass or less, and even more preferably 2% by mass or less.

[0068] (Mass ratio of blocked isocyanate compound to polycarbonate-based polyurethane resin) In the present invention, the mass ratio of the blocked isocyanate compound to the polycarbonate polyurethane resin in the ink composition [content of the blocked isocyanate compound / content of polycarbonate polyurethane resin particles] is preferably 0.03 or more, more preferably 0.05 or more, even more preferably 0.07 or more, even more preferably 0.13 or more, and preferably 0.60 or less, more preferably 0.40 or less, even more preferably 0.30 or less, and even more preferably 0.20 or less.

[0069] (Content of water-soluble organic solvents) In the present invention, the content of water-soluble organic solvent in the ink composition is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0070] When the water-soluble organic solvent contains alkylene glycol, the proportion of polyalkylene glycol to the total water-soluble organic solvent is preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more, and preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less. When the water-soluble organic solvent contains polyalkylene glycol, the proportion of polyalkylene glycol to the total water-soluble organic solvent is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less.

[0071] (Surfactant content) In the present invention, if the ink composition contains a surfactant, its content is preferably 0.5% by mass or more, more preferably 0.7% by mass or more, even more preferably 0.9% by mass or more, and preferably 2% by mass or less, more preferably 1.7% by mass or less, and even more preferably 1.5% by mass or less. In the present invention, if the ink composition contains a silicone-based surfactant, its content is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less. In the present invention, when the ink composition contains an acetylene glycol-based surfactant, its content is preferably 0.3% by mass or more, more preferably 0.4% by mass or more, even more preferably 0.5% by mass or more, and preferably 1.5% by mass or less, more preferably 1.3% by mass or less, and even more preferably 1.2% by mass or less.

[0072] (Water content) In the present invention, the water content in the ink composition is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 55% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0073] ≪Printing process≫ In the inkjet printing method of the present invention, there are no restrictions on the inkjet printing method, and any inkjet printing method can be used, but among them, drop-on-demand inkjet printing is preferred. Examples of drop-on-demand printing devices include piezo-type devices that use piezoelectric elements in the inkjet head, and thermal-type devices that use thermal energy from heaters or the like in the inkjet head. Among these, inkjet printing using a piezo-type inkjet printing device is more preferable. From the standpoint of improving image quality, the resolution of inkjet printing is preferably 600 dpi (Dots Per Inch) or higher, and more preferably 720 dpi or higher.

[0074] (fabric) The fabric used in the inkjet printing method of the present invention is not particularly limited. Examples include fabrics made from natural fibers such as cotton, linen, and silk; fabrics made from semi-synthetic fibers such as rayon and acetate; and fabrics made from synthetic fibers such as nylon, polyester, and polyurethane. Furthermore, blended fabrics containing two or more of these fibers are also acceptable. Among these, from the viewpoint of print quality and durability against external stress, a fabric containing one or more selected from the group consisting of nylon, polyester, polyurethane, and cotton is preferred, and a fabric containing one or more selected from the group consisting of nylon, polyester, and polyurethane is more preferred. In the case of a blended fabric consisting of two or more of the above-mentioned fibers, if one or more selected from the group consisting of nylon, polyester, and polyurethane is used, a print with superior print quality and durability against external stress can be obtained by the inkjet printing method of the present invention. Furthermore, from the viewpoint of durability against external stress in a humid environment, it is preferable to use a fabric containing polyurethane. As a fabric containing polyurethane, artificial leather or synthetic leather having a surface resin layer containing polyurethane is also preferable.

[0075] In the present invention, the temperature of the portion of the fabric where the ink composition lands by inkjet printing is 40°C or higher, preferably 45°C or higher, more preferably 50°C or higher, even more preferably 55°C or higher, and preferably 120°C or lower, more preferably 100°C or lower, even more preferably 95°C or lower, and even more preferably 70°C or lower, from the viewpoint of obtaining a printed product with excellent image quality. It is believed that when the temperature of the part of the ink composition that lands on the fabric is 40°C or higher, the evaporation of water and water-soluble organic solvents contained in the ink composition after landing is promoted, the ink composition rapidly thickens, bleeding is suppressed, and a print with superior image quality can be obtained.

[0076] In the inkjet printing method of the present invention, there are no restrictions on the method for measuring the temperature of the area where the ink composition lands on the fabric, and any known method can be used. Specifically, the temperature measured by placing a temperature sensor on the platen supporting the fabric located directly below the inkjet head may be taken as the temperature of the area where the ink lands, or the temperature measured using an infrared radiation thermometer at any point on the fabric within a distance of 30 cm from the area where the ink lands may be taken as the temperature of the area where the ink lands. Alternatively, the temperature of a surface different from the surface on which the inkjet head lands can be measured using an infrared radiation thermometer and taken as the temperature of the area where the ink lands.

[0077] In the inkjet printing method of the present invention, methods for raising the temperature of the area where the ink composition lands on the fabric to 40°C or higher include heating the fabric before ink is supplied from the inkjet head and heating the fabric directly below the inkjet head. Of these, the method of heating the fabric before ink is supplied from the inkjet head is preferred from the viewpoint of reliably raising the temperature of the fabric to 40°C or higher and improving the image quality of the printed material. Examples of heating equipment include infrared lamps, sheet heaters, and devices that blow heated air. These may be used individually or in combination. Of these, a sheet heater is preferred from the viewpoint of reliably raising the temperature of the fabric to 40°C or higher and improving the image quality of the printed material.

[0078] ≪Heating process≫ In the inkjet printing method of the present invention, it is preferable to include a heating step after the printing step in which the temperature of the inkjet-printed portion of the fabric is raised to 100°C or higher. After the printing process, a heating step is included to raise the surface temperature of the inkjet-printed portion of the fabric to 100°C or higher. When the polycarbonate-based polyurethane resin and pigment in the ink dots applied to the surface of the fabric are in the form of pigment-containing resin particles, and the pigment-dispersing resin constituting the pigment-containing resin particles has a functional group capable of reacting with isocyanate groups, this promotes the crosslinking reaction between the pigment-dispersing resin and the blocked isocyanate compound. The resulting crosslinked resin film firmly binds the pigment particles to the fabric, improving durability against external stress.

[0079] In the present invention, the temperature at which the inkjet-printed portion of the fabric is adjusted after inkjet printing is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, from the viewpoint of improving the image quality of the print and its durability against external stress. From the same viewpoint, it is preferably 200°C or lower, more preferably 180°C or lower, even more preferably 170°C or lower, and even more preferably 150°C or lower. In the present invention, when the fabric contains one or more selected from the group consisting of polyester and nylon, the temperature of the inkjet-printed portion of the fabric after inkjet printing is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 150°C or lower, from the same viewpoint as described above, and in particular from the viewpoint of improving the image quality of the print. Furthermore, in the present invention, when the fabric contains polyurethane, preferably one or more selected from the group consisting of artificial leather having a surface resin layer containing polyurethane and synthetic leather having a surface resin layer containing polyurethane is used as the fabric containing polyurethane, the temperature of the inkjet-printed portion of the fabric after inkjet printing is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and 200°C or lower, more preferably 180°C or lower, and even more preferably 170°C or lower, from the same viewpoint as above, and in particular from the viewpoint of improving the image quality of the printed material.

[0080] In the heating process, preferred equipment for raising the temperature of the fabric after the printing process to 100°C or higher includes infrared lamps, sheet heaters, devices for blowing heated air, and devices for maintaining the fabric in a heated air atmosphere. These may be used individually or in combination. There are no restrictions on the method for measuring the temperature of the fabric during the heating process, and any known method can be used. Specifically, this could be done by measuring the temperature using an infrared radiation thermometer at any point on the fabric that is more than 30 cm away from the area where the ink lands, or by measuring the temperature using a temperature sensor installed on the platen supporting the fabric. Alternatively, the temperature of a surface that is more than 30 cm away from the inkjet-printed area and is different from the inkjet-printed surface may be measured using an infrared radiation thermometer.

[0081] The time for heating the fabric to a temperature of 100°C or higher during the heating process is preferably 1 second or more, more preferably 10 seconds or more, even more preferably 30 seconds or more, and even more preferably 1 minute or more, from the viewpoint of improving the durability of the printed material against external stress, and from the viewpoint of productivity, preferably 40 minutes or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less. By raising the temperature of the fabric to 100°C or higher for at least one second during the heating process, if the polycarbonate-based polyurethane resin and pigment in the ink dots are in the form of pigment-containing resin particles, and the pigment-dispersing resin constituting the pigment-containing resin particles has a functional group capable of reacting with isocyanate groups, the pigment-dispersing resin and the blocked isocyanate compound are crosslinked. The resulting crosslinked resin coating firmly binds the pigment particles to the fabric, improving the durability of the resulting print against external stress.

[0082] <<Pre-treatment process>> In the present invention, a pretreatment step may be included in which a treatment solution containing a compound that chemically bonds pigments or polycarbonate-based polyurethane resins to the fabric is applied before the printing step. Examples of compounds that chemically bond pigments or polycarbonate-based polyurethane resins to the fabric include cationic compounds and polyvalent metal salts. Examples of cationic compounds include quaternary salts of alkylamines and polymers having amino groups. Examples of polyvalent metal salts include alkaline earth metal nitrates and halide salts. In the present invention, it is preferable that the aforementioned pretreatment step is omitted from the viewpoint of durability of the printed material against external stress and productivity. [Examples]

[0083] In the following manufacturing examples, preparation examples, examples, and comparative examples, "parts" and "%" refer to "parts by mass" and "mass%" unless otherwise specified. The measurement methods for each physical property are as follows.

[0084] (1) Measurement of the weight-average molecular weight of the pigment-dispersed resin The concentrations of phosphoric acid and lithium bromide were dissolved in N,N-dimethylformamide at concentrations of 60 mmol / L and 50 mmol / L, respectively. Using these solutions as eluents, the concentrations were measured by gel permeation chromatography [GPC instrument (HLC-8120GPC) manufactured by Tosoh Corporation, column (TSK-GEL, α-M x 2) manufactured by Tosoh Corporation, flow rate: 1 mL / min], with monodisperse polystyrene of known molecular weight used as the standard substance.

[0085] (2) Measurement of solid content concentration of aqueous dispersion 10.0 g of sodium sulfate, which had been stabilized in a desiccator, was weighed into a 30 ml polypropylene container (φ=40 mm, height=30 mm). Approximately 1.0 g of the sample was added and mixed. The mixture was then accurately weighed and maintained at 105°C and a gauge pressure of -0.08 MPa for 2 hours to remove volatile components. After leaving it in a desiccator at room temperature (25°C) for another 15 minutes, the mass was measured. The mass of the sample after removal of volatile components was taken as the solid content, and the solid content concentration was obtained by dividing it by the mass of the added sample.

[0086] (3) Measurement of the average particle size of resin particles containing pigment Using the "ELS-8000" laser particle analysis system (manufactured by Otsuka Electronics Co., Ltd.), the concentration of the particles to be measured is 5 × 10⁻⁶. -3 A solution diluted with water to a mass percent (converted to solid content concentration) was used. The measurement conditions were a temperature of 25°C, an angle of 90° between the incident light and the detector, and 100 integrations. The refractive index of water (1.333) was input as the refractive index of the dispersion solvent, and the average particle size obtained by the resulting cumulant analysis was taken as the average particle size of the resin particles containing the pigment.

[0087] [Manufacturing of pigment dispersion resins] Manufacturing example a1 (Manufacturing of resin a1) A monomer mixture was prepared by mixing 62 parts acrylic acid, 129 parts styrene, and 9 parts α-methylstyrene. In a reaction vessel, 20 parts methyl ethyl ketone, 0.3 parts 2-mercaptoethanol (polymerization chain transfer agent), and 10% of the monomer mixture were added and mixed, and the vessel was thoroughly purged with nitrogen gas. Separately, a dropping funnel was filled with a mixture of the remaining monomer mixture (i.e., 90% of the prepared monomer mixture), 0.27 parts of the polymerization chain transfer agent, 60 parts methyl ethyl ketone, and 2.2 parts azo radical polymerization initiator (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: V-65, 2,2'-azobis(2,4-dimethylvaleronitrile)). Under a nitrogen atmosphere, the monomer mixture in the reaction vessel was heated to 65°C while stirring, and the mixture in the dropping funnel was added dropwise over 3 hours. After 2 hours at 65°C following the completion of dropwise addition, a solution of 0.3 parts of the polymerization initiator dissolved in 5 parts of methyl ethyl ketone was added, and the mixture was further aged at 65°C for 2 hours and then at 70°C for 2 hours to obtain a solution of resin a1 (weight-average molecular weight: 12,500). The acid value of resin a1 is calculated to be 241 mg KOH / g based on the charging ratio of the raw material monomers.

[0088] <Preparation of an aqueous dispersion of resin particles containing pigments> Preparation Example I-1 (Preparation of aqueous dispersion I-1 of resin particles containing pigment) (1) 32 parts of resin a1 obtained by completely removing the solvent from the solution of resin a1 obtained in production example a1 by vacuum drying was mixed with 202 parts of ion-exchanged water. To this, 12.8 parts of 5N sodium hydroxide aqueous solution (sodium hydroxide solids content 16.9%) (degree of neutralization 40 mol%) was added, and after heating to 90°C using a warm bath, the mixture was stirred for 1 hour to disperse resin a1 in water, and then cooled to room temperature (25°C) to obtain a dispersion of resin a1 (solids content concentration: 12.8%). (2) 246.8 parts of the dispersion of resin a1 obtained in (1) above were mixed with 100 parts of cyanide pigment (CI Pigment Blue 15:3, copper phthalocyanine, manufactured by DIC Corporation, product name: TGR-SD) and stirred for 3 hours at 20°C with the disperser blades rotating at 6,000 rpm using a disperser (manufactured by Asada Iron Works Co., Ltd., product name: Ultra Disperser). Next, 124 parts of deionized water were added and dispersed in 15 passes at a pressure of 150 MPa using a microfluidizer (manufactured by MICROFLUIDICS, product name). The resulting dispersion was placed in a 500 mL angle rotor and centrifuged at 3,660 rpm for 20 minutes using a high-speed refrigerated centrifuge (manufactured by Hitachi Koki Co., Ltd., product name: himac CR22G, set temperature 20°C), after which the liquid phase was recovered. The recovered liquid phase was filtered through a 5 μm membrane filter (Sartorius, product name: Minisart) to obtain an aqueous dispersion of pigment-containing resin particles I'-1. At this time, the solid content concentration of the aqueous dispersion of pigment-containing resin particles I'-1 was 25%. (3) 100 parts of the aqueous dispersion I'-1 of the pigment-containing resin particles obtained in (2) above were placed in a screw-top glass bottle, 32 parts of deionized water and 1.78 parts of trimethylolpropane polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name: Denacol EX-321LT, epoxy value: 139) were added, the bottle was sealed tightly, and heated at 70°C for 5 hours while stirring with a stirrer. At this time, the crosslinking treatment was carried out with an amount of crosslinking agent that was sufficient to react with 50% of the total number of carboxyl groups contained in the resin (crosslinking rate 50 mol%). After 5 hours, the temperature was lowered to room temperature (25°C), and the mixture was filtered using a 25 mL needleless syringe (manufactured by Terumo Corporation) fitted with the aforementioned 5 μm filter to obtain the aqueous dispersion I-1 of the crosslinked pigment-containing resin particles (solid content concentration: 20%). The acid value of the crosslinked resin constituting the crosslinked pigment-containing resin particles was calculated to be 120.5 mg KOH / g. The average particle size of the crosslinked pigment-containing resin particles in aqueous dispersion I-1 was 105 nm. Furthermore, the mass ratio of the pigment-dispersed resin to the pigment constituting the crosslinked pigment-containing resin particles in aqueous dispersion I-1 was 0.41.

[0089] (Preparation of water-based inks II-1 to II-9) Preparation Examples 1-9 In a glass container, as shown in the ink formulation column of Table 1, an aqueous dispersion of pigment-containing resin particles I-1, a polycarbonate polyurethane resin emulsion, a dispersion of other resins (resins without pigments), a blocked isocyanate compound dispersion, a water-soluble organic solvent, a surfactant, and deionized water were added and the mixture was stirred for 1 hour. Deionized water was added so that the total amount was 100 parts by mass. After that, the mixture was filtered using a 5 μm disposable membrane filter (Sartorius, trade name "Minisart") to obtain aqueous inks II-1 to II-9.

[0090] Details of the polycarbonate polyurethane resin emulsions, dispersions of other resins (resins without pigments), water-soluble organic solvents, blocked isocyanate compound dispersions, and surfactants listed in Table 1 are as follows. (Emulsion of polycarbonate-based polyurethane resin) • Superflex 460 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polycarbonate-based polyurethane resin dispersion, ionic: anionic, solids content 38%) • Takelac WS-5100 (manufactured by Mitsui Chemicals, Inc., self-crosslinking polycarbonate-based polyurethane resin dispersion, solids content 30%) (Dispersion of other resins (resins that do not contain pigments)) • Superflex E-4800 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyether-based polyurethane resin dispersion, ionic properties: nonionic / weakly anionic, solids content 40%) • Superflex 300 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyester ether-based polyurethane resin dispersion, ionic; weakly anionic, solids content 30%) • Superflex 740 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyester-based polyurethane resin dispersion, ionic: anionic, solids content 40%) (Blocked isocyanate compound dispersion) • Trixene Aqua BI220 (manufactured by GSI Creos Corporation, HDI trimer, aqueous dispersion of 3,5-dimethylpyrazole-type blocked isocyanate compound, dissociation temperature: 120°C, isocyanate group equivalent: 1,000, solids content: 40%) (Water-soluble organic solvent) Propylene glycol • Dipropylene glycol (Surface activator) [Silicone-based surfactants] • Silface SAG005 (manufactured by Nisshin Chemical Industry Co., Ltd., polyether-modified silicone, 100% active ingredient) [Acetylene-based surfactants] • Surfinol 465 (manufactured by Nisshin Chemical Industry Co., Ltd., ethylene oxide (EO) adduct of 2,4,7,9-tetramethyl-5-decine-4,7-diol, average number of EO added moles: 10, effective content 100%) • Surfinol 420 (manufactured by Nisshin Chemical Industry Co., Ltd., EO adduct of 2,4,7,9-tetramethyl-5-decine-4,7-diol, average number of EO added moles: 1.3, effective content 100%)

[0091] <Preparation of printed materials> Examples 1-8, 10-13, Comparative Examples 1-6 Using the obtained water-based inks II-1 to II-8, printed materials were prepared and evaluated under the conditions shown in Table 1 and the procedure described below. The results are shown in Table 1. (Printing process) In an environment with a temperature of 25±1℃ and a relative humidity of 30±5%, the obtained water-based ink was filled into a printing evaluation device (manufactured by Trytech Co., Ltd.) equipped with an inkjet head (Kyocera Corporation, product name: KJ4B-HD06MHG-STDV, piezo type). The head voltage was set to 26V, frequency to 15kHz, head temperature to 32℃, ejection droplet volume to 5pL, resolution to 600×600dpi, number of pre-ejection flushes to 200, and negative pressure to -4.0kPa. At this time, one-pass printing was performed using two inkjet heads for one type of ink, and the total resolution was set to 1200dpi in the horizontal direction × 600dpi in the feed direction. An A4-sized film heater (manufactured by Kawai Electric Works Co., Ltd.) was fixed on the transport table, and the cloth shown in Table 1 was fixed on the heater as the printing medium with double-sided tape so that the longitudinal direction of the printing medium and the transport direction were the same. The heater intensity was adjusted so that the temperature of the area where the ink would land reached the temperatures shown in Table 1, as measured by an infrared radiation thermometer MT-4 (manufactured by Raytec). A print command was then transmitted to the print evaluation device. For image quality (bleeding) evaluation, a print pattern with 50 Japanese hiragana characters (MS Mincho), 24 alphabet characters (Times New Roman), and numbers 1-30 (Times New Roman) in a font size of 8pt was inkjet printed. For friction fastness evaluation, a print pattern with a duty cycle of 30% and a length of 2 cm in the transport direction was also inkjet printed to obtain inkjet printed materials. (Heating process) The obtained inkjet prints were placed in a constant-temperature dryer adjusted to 120°C for all but Examples 6, 7, and 10, 140°C for Example 6, and 160°C for Examples 7 and 10. The temperature of the inkjet-printed surface of the fabric was measured using the infrared radiation thermometer, and after confirming that the inkjet-printed surface of the fabric was maintained at the respective temperature for 20 minutes, it was returned to room temperature of 23±1°C to obtain the printed material. The obtained printed material was then subjected to each evaluation.

[0092] Example 9 The treatment solution containing the polyvalent metal salt prepared as described below was used to apply the polyvalent metal salt to the fabric at a rate of 5.0 g / m². 2The material was uniformly spray-coated with an appropriate coating amount, then heated and dried in a 100°C constant-temperature drying oven for 5 minutes, and after returning to room temperature (23±1°C), a print was obtained using water-based ink II-1 in the same manner as in Example 1. The obtained prints were subjected to each evaluation.

[0093] (Preparation of treatment solution containing polyvalent metal salts) In a glass container, 8% calcium nitrate tetrahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 100% solids), 0.1% silicone-based surfactant (manufactured by Big Chemie Japan Co., Ltd., product name: BYK-348, 100% active ingredient), 5.6% styrene / acrylic emulsion (manufactured by Japan Coating Resin Co., Ltd., product name: Movinyl 966A, 45% solids), and 86.3% deionized water were added and stirred with a magnetic stirrer for 10 minutes to obtain a treatment solution containing polyvalent metal salts.

[0094] The printing media shown in Table 1 are as follows. All fabrics were cut to A5 size for use. PES (Polyester): Polyester Tropical, Toray (120g / m²) 2 (Manufactured by Irozome Co., Ltd.) • Nylon: Nylon 6 Taffeta (70g / m²) 2 (Manufactured by Irozome Co., Ltd.) • PU (Polyurethane): Artificial leather with a polyurethane surface (manufactured by Ideatex Japan Co., Ltd., product name: Supplere PBZ13001) • Cotton: 40 count mercerized cotton broadcloth (122g / m²) 2 (Manufactured by Irozome Co., Ltd.)

[0095] <Rating> (1) Evaluation of image quality (blurring) The print patterns of the printed materials obtained for image quality (bleeding) evaluation in the examples and comparative examples were visually inspected and the image quality was evaluated. If the evaluation criteria are A or B, there are no practical problems. (Evaluation Criteria) A: There is no blurring or distortion in either the letters or numbers, and they are perfectly legible. B: Some blurring is visible in parts of the letters and numbers, and the sharpness is inferior to A, but it is not so bad that the letters and numbers cannot be identified. C: Some or all of the letters and numbers are illegible due to ink bleeding and cannot be used in practice.

[0096] (2) Evaluation of dry friction fastness The prints obtained for friction fastness evaluation in the examples and comparative examples were subjected to dry friction tests using a Type II friction tester in accordance with JIS L0849:2013, and evaluated using a grayscale of discoloration. Dry friction fastness of grade 3 or higher is considered acceptable, grades 3-4 or higher are excellent, and grade 4 or higher is even better. (3) Evaluation of wet friction fastness The friction fastness evaluation prints obtained in the examples and comparative examples were subjected to wet friction tests using a Type II friction tester in accordance with JIS L0849:2013, and evaluated using a grayscale of discoloration. A wet friction fastness of grade 3 or higher is considered acceptable, grades 3-4 or higher are excellent, and grade 4 or higher is even better.

[0097] [Table 1]

[0098] Table 1 shows that the prints obtained in Examples 1 to 13 are superior in image quality and durability against external stresses such as abrasion compared to the prints obtained in Comparative Examples 1 to 6. Furthermore, Comparative Example 3 uses a self-crosslinking polyurethane resin having a blocked isocyanate structure within its structure as the polycarbonate-based polyurethane resin. Therefore, in Comparative Example 3, the polycarbonate-based polyurethane resin mainly undergoes crosslinking reactions with parts of itself in its vicinity through intramolecular crosslinking. As a result, the effect of improving the durability of the coating film through crosslinking is small, and the durability of the printed object against external stress is inferior.

Claims

1. The printing process includes printing an ink composition containing a pigment, a polycarbonate-based polyurethane resin, a blocked isocyanate compound, a water-soluble organic solvent, and water onto a fabric where the temperature of the area where the ink composition lands is 40°C or higher using an inkjet printer. The polycarbonate-based polyurethane resin does not have a blocked isocyanate structure within its molecule, and has functional groups that can react with isocyanate groups. The aforementioned fabric is a fabric containing polyurethane, The aforementioned fabric is untreated. Inkjet printing method.

2. The inkjet printing method according to claim 1, further comprising a heating step after the printing step to raise the temperature of the inkjet-printed portion of the fabric to 100°C or higher.

3. The inkjet printing method according to claim 1 or 2, wherein the water-soluble organic solvent contains one or more selected from the group consisting of alkylene glycols and polyalkylene glycols.

4. The inkjet printing method according to claim 1 or 2, wherein the content of the blocked isocyanate compound in the ink composition is 0.9% by mass or more and 5% by mass or less.

5. The inkjet printing method according to claim 1 or 2, wherein the pigment is in the form of resin particles containing the pigment.

6. The inkjet printing method according to claim 1 or 2, wherein the content of polycarbonate-based polyurethane resin in the ink composition is 1% by mass or more and 15% by mass or less.

7. The inkjet printing method according to claim 1 or 2, wherein the mass ratio of the blocked isocyanate compound to the polycarbonate polyurethane resin in the ink composition [content of the blocked isocyanate compound / content of polycarbonate polyurethane resin particles] is 0.03 or more and 0.60 or less.

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