inkjet ink

Abstract

The present invention provides an inkjet ink in which the colorant is stably and highly dispersed, has excellent injection stability (droplet formation and droplet recovery), and can improve the texture and friction fastness of printed materials. [Solution] An inkjet ink comprising a urethane resin having (A) a structural unit derived from polyisocyanate, (B) a structural unit derived from polyol, and (C) a structural unit derived from polyamine, and an organic solvent, wherein the (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group, and the (C) polyamine comprises (C1) a first polyamine having two groups selected from an amino group, an imino group, and a hydrazide group, and (C2) a second polyamine having three or four groups selected from an amino group, an imino group, and a hydrazide group, and the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is 1.0 or more.

Description

Technical Field

[0001] The present invention relates to an ink for inkjet.

Background Art

[0002] Conventionally, as a recording method for fabrics (woven fabrics and non-woven fabrics), screen printing, roller printing, etc. have been used. In recent years, inkjet printing, which can dye in a short time and has high production efficiency, has been widely used to form an image on a fabric by an inkjet recording method.

[0003] As the printing ink for inkjet printing, there are dyes and pigments as colorants. When using a pigment, it has high light resistance and is advantageous compared to a dye in that post-treatment such as washing is not required. In the case of printing with a pigment, it is important to physically fix (anchor) the pigment to the fibers of the fabric, etc. Therefore, as an inkjet ink composition for pigment printing, studies have been underway to blend a binder resin for fixing the pigment to the fabric. As the binder resin, it is required not to impair the texture in the fabric inkjet printed fabric (hereinafter, printed matter). For example, Patent Documents 1 and 2 disclose a printing inkjet ink composition using a relatively flexible urethane resin as the binder resin.

[0004] In addition, the printing method using the inkjet method also has problems peculiar to it. In the inkjet method, the ejected ink is ejected as a liquid column and then flies as droplets. However, due to some cause, this liquid column may be separated on the way, etc., and a phenomenon may occur in which it is divided into main droplets and satellite droplets. When this phenomenon occurs, an image is transferred to an unintended location on the printed matter, and the print quality of the printed matter, which is also related to the design (clarity) of the printed matter, is impaired. For the purpose of improving such droplet formation (suppressing satellite droplets), Patent Document 3 has considered from the aspect of the printing system.

Prior Art Documents

[0005] [Patent Document 1] Patent No. 6776775 specification [Patent Document 2] Japanese Patent Publication No. 2020-84013 [Patent Document 3] Japanese Patent Publication No. 2018-015974 [Overview of the project] [Problems that the invention aims to solve]

[0006] In inkjet printing, generally, using an inkjet ink composition containing urethane resin as a binder resin results in a flexible and good texture for the fabric. However, this flexibility leads to the problem of insufficient abrasion fastness. In other words, there is a trade-off between texture and abrasion fastness in printed materials. Even with the inkjet ink compositions proposed in Patent Documents 1 and 2, the texture and abrasion fastness in printed materials were not sufficient, and there was room for further improvement.

[0007] Furthermore, inkjet ink compositions for textile printing often contain water-soluble organic solvents, and urethane resins are easily soluble in water-soluble organic solvents. Therefore, inkjet ink compositions containing urethane resins tend to have poor stability against high shear forces during injection (injection stability). For example, in inkjet printing, if droplets ejected from the inkjet nozzle separate and satellite droplets are generated, the print quality of the printed material is impaired as described above. Also, if the drying of the inkjet ink composition is accelerated in the inkjet nozzle, the inkjet nozzle may become clogged, resulting in droplets not being ejected or droplets not being ejected uniformly, thus impairing print quality. Therefore, in order to improve print quality, injection stability of the inkjet ink composition (excellent droplet formation and droplet recovery) is required. Furthermore, we believe that exploring ways to improve droplet formation using an approach different from the technology described in Patent Document 3 will also contribute to improving the print quality of printed materials.

[0008] Furthermore, in inkjet ink compositions for pigment printing, the pigments exist in a dispersed state. Therefore, sedimentation due to pigment aggregation becomes a major problem. Sedimentation due to pigment aggregation causes clogging in inkjet nozzles. From the standpoint of ejection stability from inkjet nozzles, it is necessary that the pigments in the inkjet ink composition are stably and highly dispersed. Conventional inkjet ink compositions for pigment printing have not always been sufficient in terms of good ejection stability (excellent droplet formation and droplet recovery) and ejection stability from inkjet nozzles, and there was room for further improvement.

[0009] This invention has been made in view of the problems of the prior art, and aims to provide an inkjet ink in which the colorant is stably and highly dispersed, has excellent injection stability (droplet formation and droplet recovery), and can improve the texture and friction fastness of printed materials. [Means for solving the problem]

[0010] One aspect of the present invention for solving the above problems relates to the inkjet ink described in [1] to

[14] below.

[0011] [1] A urethane resin having (A) a structural unit derived from polyisocyanate, (B) a structural unit derived from polyol, and (C) a structural unit derived from polyamine, Organic solvents and Includes, The (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group. The (C) polyamine comprises a first polyamine having two groups selected from (C1) amino groups, imino groups, and hydrazide groups, and a second polyamine having three or four groups selected from (C2) amino groups, imino groups, and hydrazide groups. An inkjet ink in which the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is 1.0 or greater.

[0012] [2] The inkjet ink according to [1], wherein the content of the urethane resin is 5% by mass or more and 20% by mass or less with respect to the total mass of the ink.

[0013] [3] The inkjet ink according to [1] or [2], wherein the organic solvent comprises a glycol-based solvent.

[0014] [4] The inkjet ink according to any one of [1] to [3], wherein the organic solvent comprises a glycol-based solvent having an octanol / water partition coefficient of -1.80 or less.

[0015] [5] The inkjet ink according to any one of [1] to [4], wherein the content of the organic solvent is 10% by mass or more and 50% by mass or less with respect to the total mass of the ink.

[0016] [6] Further containing colorants, The mass ratio of the colorant to the urethane resin (mass of colorant / mass of urethane resin) is 0.05 to 2.0, and the ink for inkjet according to any one of [1] to [5].

[0017] [7] The acid value of the urethane resin is 5 mgKOH / g or more and less than 30 mgKOH / g, and the ink for inkjet according to any one of [1] to [6].

[0018] [8] The second polyamine contains diethylenetriamine or triethylenetetramine, and the ink for inkjet according to any one of [1] to [7].

[0019] [9] The polyether polyol contains polytetramethylene glycol, and the ink for inkjet according to any one of [1] to [8].

[0020]

[10] The glass transition temperature of the urethane resin is 0°C or lower, and the ink for inkjet according to any one of [1] to [9].

[0021]

[11] Used for printing on fabrics, and the ink for inkjet according to any one of [1] to

[10] . [Advantages of the Invention]

[0022] According to the present invention, there is provided an ink for inkjet in which the colorant is stably and highly dispersed, has excellent ejection stability (droplet formation property and droplet recovery property), and can improve the texture and rubbing fastness of the printed matter. [Modes for Carrying Out the Invention]

[0023] The embodiments for carrying out the present invention will be described in detail below. The embodiments shown herein are illustrative examples to embody the technical idea of ​​the present invention and do not limit the present invention. Therefore, all other implementable forms, methods of use, and operating techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included in the scope and spirit of the present invention, as well as in the scope of the invention described in the claims and its equivalents. The embodiments described herein can be arbitrarily combined to form other embodiments. In this specification, "X~Y" indicating a range means "X or more and Y or less," and "weight" and "mass," "weight%" and "mass%," and "parts by weight" and "parts by mass" are treated as synonyms. In this specification, "A and / or B" includes A or B, and forms of A and B. In this specification, the term "(meth)acrylic" includes both acrylic and methacrylic. Therefore, for example, the term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid. Similarly, the term "(meth)acrylate" encompasses both acrylate and methacrylate, and the term "(meth)acrylamide" encompasses both acrylamide and methacrylamide. Unless otherwise specified in this specification, operations and measurements of physical properties are performed under conditions of room temperature (20°C to 25°C) and relative humidity of 40% RH to 50% RH.

[0024] Inkjet ink One embodiment of the present invention is an inkjet ink comprising a urethane resin having (A) a structural unit derived from polyisocyanate, (B) a structural unit derived from polyol, and (C) a structural unit derived from polyamine, and an organic solvent, wherein the (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group, and the (C) polyamine comprises (C1) a first polyamine having two groups selected from an amino group, an imino group, and a hydrazide group, and (C2) a second polyamine having three or four groups selected from an amino group, an imino group, and a hydrazide group, and the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is 1.0 or more. Inkjet inks with such a configuration (hereinafter also referred to as "inkjet ink according to this embodiment," "ink according to this embodiment," or "ink") have a stable and highly dispersed colorant, excellent injection stability (droplet formation and droplet recovery), and can improve the texture and abrasion fastness of printed materials.

[0025] The mechanism by which the ink in this embodiment achieves the above effects is thought to be as follows. Since urethane resin is a relatively flexible resin, it can improve the texture when used as a binder in inkjet inks, but because of its flexibility, it tends to have poor friction fastness. Therefore, we have found that by using a combination of a first polyamine and a second polyamine as extenders, it is possible to achieve both texture and friction fastness in inkjet inks. Furthermore, in the ink in this embodiment, the urethane resin is produced by emulsion polymerization and is in the form of an aqueous dispersion. Therefore, the urethane resin is in particulate form (hereinafter, the urethane resin dispersed in particulate form will be referred to as "urethane resin particles" or "resin particles"), and maintains dispersibility by exposing dispersion groups on its surface. However, in urethane resin, some monomers may remain, or low molecular weight substances with insufficient polymerization reactions may be generated. Because these are easily soluble in organic solvents, they may dissolve from within the resin particles into the outer phase (the outer phase of the particles). Inkjet inks containing such urethane resin particles, even if they show good dispersibility under normal storage conditions, have the problem that dispersion stability decreases and viscosity fluctuations occur during long-term storage. Furthermore, high shear forces are easily applied to the inkjet ink during injection by the inkjet head. This high shear force easily deforms the shape of the urethane resin particles, exposing the hydrophobic parts of the urethane resin to the surface, reducing dispersibility, causing the urethane resin particles to aggregate, and resulting in a decrease in injection stability by the inkjet head. For example, the shape of the inkjet ink droplets formed during injection becomes unstable, and in use after intermittent use, the droplet ejection speed decreases significantly, or ejection becomes impossible, resulting in issues with injection stability.

[0026] In this invention, we have found that by setting the amount of organic solvent used in the inkjet ink to 1 or more relative to the urethane resin, the urethane resin particles can maintain a stable dispersion state during inkjet injection. In other words, we have found that by setting a specific relationship between the amount of organic solvent and the amount of urethane resin, it effectively acts to maintain the dispersion state of the urethane resin particles. In the ink according to this embodiment, setting the amount of organic solvent to 1 or more relative to the urethane resin improves the dispersion stability of the urethane resin in the inkjet ink. As a result, the dispersion state of the urethane resin in the inkjet ink is less likely to change, thus improving long-term stability. Furthermore, even when high shear forces are applied to the inkjet ink, aggregation of resin particles can be suppressed, and injection stability can be improved. As described above, the inkjet ink according to this embodiment has a stable and highly dispersed colorant and urethane resin particles, as well as excellent injection stability (droplet formation and droplet recovery), and can improve the texture and friction fastness of printed materials. Note that the above mechanism is speculative, and the technical scope of the present invention is not limited to the above mechanism.

[0027] In this specification, "inkjet ink" means a composition containing urethane resin or urethane resin particles (urethane resin aqueous dispersion), and is used to include compositions that have become liquid (ink-like) by containing organic solvents, etc.

[0028] The ink according to this embodiment may be an inkjet ink containing a coloring agent. The effects of the present invention are achieved by the inclusion of a coloring agent in the ink according to this embodiment. Furthermore, the effects of the present invention are further enhanced by the inclusion of a pigment as the coloring agent in the ink according to this embodiment.

[0029] [Urethane resin] The ink according to this embodiment contains a urethane resin. The urethane resin (also referred to as "polyurethane resin") can function as a binder resin for fixing colorants that may be contained in inkjet ink to fibers. Because the ink according to this embodiment contains a urethane resin, when applied to the surface of a substrate (recording medium) or recording material (for example, the surface of a cloth), it is possible to form a printed material (e.g., a textile print) with a good texture and excellent abrasion resistance.

[0030] In the ink according to this embodiment, the urethane resin has (A) a structural unit derived from polyisocyanate, (B) a structural unit derived from polyol, and (C) a structural unit derived from polyamine, wherein (B) the polyol includes (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group, and (C) the polyamine includes (C1) a first polyamine having two groups selected from an amino group, an imino group, and a hydrazide group, and (C2) a second polyamine having three or four groups selected from an amino group, an imino group, and a hydrazide group.

[0031] In this embodiment, the urethane resin is preferably a resin dispersion in which the urethane resin is dispersed in water (i.e., a urethane resin aqueous dispersion). The composition of the urethane resin and the urethane resin aqueous dispersion will be described in detail below.

[0032] As described above, the urethane resin according to this embodiment is preferably in a form dispersed in water. Therefore, the aqueous dispersion of urethane resin comprises (A) a urethane resin having constituent units derived from polyisocyanate, (B) a urethane resin having constituent units derived from polyol, and (C) a urethane resin having constituent units derived from polyamine, and water, wherein the (B) polyol includes (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group, and the (C) polyamine includes a first polyamine having two groups selected from (C1) an amino group, an imino group, and a hydrazide group, and a second polyamine having three or four groups selected from (C2) an amino group, an imino group, and a hydrazide group.

[0033] (A) Polyisocyanate The urethane resin according to this embodiment has a constituent unit derived from (A) polyisocyanate. There are no particular restrictions on the polyisocyanate, and examples include aromatic polyisocyanate compounds, aliphatic polyisocyanate compounds, and alicyclic polyisocyanate compounds. Examples of aromatic polyisocyanate compounds include toluene diisocyanate (TDI), xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), and tetramethylxylylene diisocyanate. Examples of aliphatic polyisocyanate compounds include alkylene diisocyanates such as hexamethylene diisocyanate (HDI). Here, the number of carbon atoms in the alkylene in the alkylene diisocyanate is preferably 2 to 10, 3 to 9, 4 to 8, or 5 to 7. Examples of alicyclic polyisocyanate compounds include cycloalkylene diisocyanates and dicycloalkylalkane diisocyanates. In dicycloalkylalkane diisocyanates, the number of carbon atoms in the cycloalkyl group is preferably 5 to 8, and in dicycloalkylalkane diisocyanates, the number of carbon atoms in the alkane group is preferably 1 to 4 or 1 to 3. Specific examples of alicyclic polyisocyanate compounds include, for example, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H12MDI), and norbornane diisocyanate. Therefore, according to one embodiment of the present invention, the polyisocyanate is one or more diisocyanate compounds selected from the group consisting of aromatic diisocyanate compounds, aliphatic diisocyanate compounds, and alicyclic diisocyanate compounds. These polyisocyanate compounds can be used individually or in combination of two or more.

[0034] (B) Polyol The urethane resin according to this embodiment has a constituent unit derived from (B) polyol, and the (B) polyol includes (B1) polyether polyol and (B2) a diol compound having a carboxyl group and / or carboxylate group.

[0035] (B1) Polyether polyol In one embodiment of the present invention, polyalkylene ether glycol is an example of (B1) polyether polyol. The number of carbon atoms in the alkylene in the polyalkylene ether glycol is preferably 2 to 6, 2 to 5, or 3 or 4. Such alkylene can be linear or branched. Specific examples of (B1) polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or polyols consisting of blocks or random copolymers thereof.

[0036] In one embodiment of the present invention, the number-average molecular weight of (B1) polyether polyol can be 500 to 5,000, 1,000 to 4,000, or 1,500 to 3,000. The number-average molecular weight was calculated using the hydroxyl value of (B1) polyether polyol by the following formula. The hydroxyl value was determined in accordance with JIS K 1557-1:2007 Method A. The number-average molecular weights of polyester polyols and polycarbonate polyols described later are calculated using the same method.

[0037]

number

[0038] In one embodiment of the present invention, (B) polyol may include at least one selected from polyester polyols, polycarbonate polyols, and low molecular weight polyhydric alcohols, as long as the performance of the present invention is not impaired. Here, the number average molecular weight (molecular weight) of the low molecular weight polyhydric alcohol may be less than 500 or 400 or less.

[0039] In one embodiment of the present invention, the polycarbonate polyol can be, for example, one or more polyols selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, or ethylene oxide or propylene oxide adducts of bisphenol A, trimethylolpropane, glycerin, pentaerythritol, etc., and obtained by a de-alcoholization reaction, de-phenolization reaction, etc., with one or more carbonates selected from diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, etc. The above polycarbonate polyols can be used individually or in combination of two or more types.

[0040] In one embodiment of the present invention, the polyester polyol can be, for example, one obtained by a polycondensation reaction between one or more dibasic acids selected from phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, malonic acid, adipic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, maleic acid, fumaric acid, etc., and one or more polyols used in the synthesis of the aforementioned polycarbonate polyol. The above polyester polyol can be used alone or in combination of two or more.

[0041] In one embodiment of the present invention, the number-average molecular weights of the polycarbonate polyol and the polyester polyol can be independently 500 to 5,000, 1,000 to 4,000, or 1,500 to 3,000, respectively.

[0042] In one embodiment of the present invention, examples of low molecular weight polyhydric alcohols include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, and sorbitol.

[0043] In one embodiment of the present invention, the mass of the (B1) polyether polyol relative to the total mass of the (B1) polyether polyol contained in (B) and the polycarbonate polyol and polyester polyol that may be contained in (B) is 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more (upper limit is 100% by mass). Having such a lower limit improves droplet formation.

[0044] In one embodiment of the present invention, the total number of moles of low molecular weight polyhydric alcohol relative to the total number of moles of polyol (B) is 50 mol% or less, 40 mol% or less, 38 mol% or less, 30 mol% or less, 20 mol% or less, 10 mol% or less, 5 mol% or less, or 1 mol% or less (the lower limit is 0 mol%). Having such an upper limit improves the flexibility of the resulting urethane resin and the texture of the printed material.

[0045] In one embodiment of the present invention, the total mass of the low molecular weight polyhydric alcohol relative to the total mass of the polyol (B) is 5.0% by mass or less, 4.0% by mass or less, 3.4% by mass or less, 3.0% by mass or less, or 1.0% by mass or less (the lower limit is 0% by mass). Having such an upper limit improves the flexibility of the resulting urethane resin and the texture of the printed material.

[0046] Furthermore, the (B1) polyether polyols included in (B), as well as the polycarbonate polyols and polyester polyols that may be included in (B), typically do not contain either carboxyl groups or carboxylate groups.

[0047] (B2) Diol compounds having a carboxyl group and / or a carboxylate group In one embodiment of the present invention, the urethane resin of the present invention has a constituent unit derived from a diol compound having a carboxyl group and / or a carboxylate group (B2). Here, the urethane resin is generally hydrophobic (lipophilic) and not aqueous (water-dispersible). In one embodiment of the present invention, the urethane resin has a carboxylate group. With such an embodiment, the urethane resin contained in the aqueous dispersion of the urethane resin according to this embodiment may have aqueous (water-dispersible) properties. In one embodiment of the present invention, the number of groups selected from carboxyl groups and carboxylate groups contained in one molecule of (B2) is one, two, or three.

[0048] In one embodiment of the present invention, (B2) has one alkyl group in one molecule. The alkyl group preferably has 1 to 6 carbon atoms, or 1 or 2 carbon atoms. The alkyl group preferably has a linear chain. In one embodiment of the present invention, (B2) can be, for example, 2,2-dimethylolpropionic acid (DMPA), 2,2-dimethylolbutanoic acid (DMBA), or their neutralized products. Furthermore, such diol compounds having a carboxyl group and / or carboxylate group can be used individually or in combination of two or more.

[0049] In one embodiment of the present invention, the total number of moles of (B1) and (B2) relative to the total number of moles of polyol (B) is 50 mol% or more, greater than 50 mol%, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more.

[0050] In one embodiment of the present invention, the number of moles of (B2) relative to the total number of moles of (B) is greater than 45 mol%, 47 mol% or more, or 49 mol% or more. In one embodiment of the present invention, the number of moles of (B2) relative to the total number of moles of (B) is 70 mol% or less, 65 mol% or less, or 60 mol% or less.

[0051] In one embodiment of the present invention, the total number of moles of carboxylate groups relative to the total number of moles of carboxylate groups in the urethane resin (so-called neutralization rate) is 40 mol% or more. In one embodiment of the present invention, the total number of moles of carboxylate groups relative to the total number of moles of carboxylate groups in the urethane resin is 40 to 100 mol%, or 50 to 80 mol%. In order for the urethane resin to have carboxylate groups, and to ensure that the total number of moles of carboxylate groups relative to the total number of moles of carboxylate groups in the urethane resin is above a certain lower limit, methods include using a diol compound having carboxylate groups as (B2) as a raw material, using a diol compound in which at least a portion is carboxylate groups obtained by neutralizing at least a portion of the carboxylate groups of a diol compound having carboxylate groups as (B2) as a raw material, or using a diol compound having carboxylate groups as (B2) as a raw material to obtain a prepolymer as described later and then performing neutralization. In the present invention, the method of performing neutralization after obtaining a prepolymer is preferred. Therefore, in one embodiment of the present invention, the urethane resin has structural units derived from (A) and structural units derived from (B), and structural units derived from a prepolymer having an isocyanate group at its terminal end. Details regarding neutralization will be described later.

[0052] In one embodiment of the present invention, (B) does not contain an aliphatic cyclic structure.

[0053] (C) Polyamine The urethane resin according to this embodiment has a constituent unit derived from (C) polyamine, and the (C) polyamine comprises a first polyamine having two groups selected from (C1) amino groups, imino groups, and hydrazide groups, and a second polyamine having three or four groups selected from (C2) amino groups, imino groups, and hydrazide groups.

[0054] In one embodiment of the present invention, (C) polyamine can be used as a chain elongator for the prepolymer described later. As chain elongators, compounds having a trivalent number of functional groups (number of functional groups with active hydrogen) and containing hydroxyl groups are known (for example, trimethylolpropane and aminoethylethanolamine, etc.). However, using these tends to result in insufficient chain elongation and deterioration of droplet formation properties. While this does not restrict their use in combination with (C), it is preferable not to use them.

[0055] The urethane resin according to this embodiment has a constituent unit derived from (C) polyamine, and the (C) polyamine comprises a first polyamine having two groups selected from (C1) amino groups, imino groups, and hydrazide groups, and a second polyamine having three or four groups selected from (C2) amino groups, imino groups, and hydrazide groups.

[0056] In one embodiment of the present invention, (C1) may be at least one of alkylenediamine, a diamine without carbon atoms, and a diamine having a cycloalkane structure with 5 to 8 carbon atoms. In one embodiment of the present invention, the alkyl group of the alkylenediamine may have 1 to 12 carbon atoms. In one embodiment of the present invention, the diamine having a cycloalkane structure may be a diaminoalkylcycloalkane, where the number of carbon atoms in the alkyl group of the diaminoalkylcycloalkane is 1 to 4, 1 to 3, or 1 or 2, and the number of carbon atoms in the cycloalkane of the diaminoalkylcycloalkane may be 5 to 8, or 5 to 7.

[0057] In one embodiment of the present invention, (C1) is, for example, ethylenediamine, 1,3-propanediamine, propylenediamine, 1,3-butanediamine, 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, diaminodicyclohexylmethane, hydrazine, piperazine, 2-methylpiperazine, isophoronediamine, norboranediamine, 1,3-bisaminocyclohexane, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, diaminodiphenylmethane, and tolylenediamine. Examples include diamines such as xylylenediamine; amideamines derived from diprimary amines and monocarboxylic acids; water-soluble amine derivatives such as monokethimine of diprimary amines; and hydrazine derivatives such as dihydrazide oxalate, dihydrazide malonate, dihydrazide succinate, dihydrazide glutarate, dihydrazide adipic acid, dihydrazide sebacate, dihydrazide maleate, dihydrazide fumarate, dihydrazide itaconic acid, 1,1'-ethylenehydrazine, 1,1'-trimethylenehydrazine, and 1,1'-(1,4-butylene)dihydrazine. Among these, ethylenediamine, hydrazine, piperazine, isophoronediamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, and norboranediamine can be used particularly favorably.

[0058] In one embodiment of the present invention, (C2) is, for example, the general formula: H2N((CH2) n NH) m A polyamine represented by H (where n is 2 to 6 and m is 2 or 3) is preferred, and specifically, diethylenetriamine, triethylenetetramine, iminobispropylamine, etc. can be mentioned. Among these, diethylenetriamine and triethylenetetramine can be used particularly favorably. According to one embodiment, the (C2) secondary polyamine comprises diethylenetriamine or triethylenetetramine.

[0059] As described above, the urethane resin according to this embodiment has a constituent unit derived from a first polyamine having two groups selected from (C1) amino groups, imino groups, and hydrazide groups, and a constituent unit derived from a second polyamine having three or four groups selected from (C2) amino groups, imino groups, and hydrazide groups. By having such a configuration, the resulting aqueous dispersion of the urethane resin has good droplet-forming properties.

[0060] In one embodiment of the present invention, (C) may include polyamines having five or more groups selected from amino groups and imino groups, polyethyleneimine, etc. In one embodiment of the present invention, the total number of moles of (C1) and (C2) relative to the total number of moles of (C) is 80 mol% or more, 85 mol% or more, 90 mol% or more, 95 mol% or more, or 98 mol% or more (upper limit is 100 mol%). Having such a lower limit can improve the flexibility of the printed material. In one embodiment of the present invention, the total mass of (C1) and (C2) relative to the total mass of (C) is 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, or 98% by mass or more (upper limit is 100% by mass). Having such a lower limit can improve the flexibility of the printed material.

[0061] In one embodiment of the present invention, the total number of moles of (C2) relative to the total number of moles of (C1) and (C2) is 1.0 to 96.0 mol%. This range allows for more efficient achievement of both droplet formation properties and the texture of the printed material. In another embodiment of the present invention, the total number of moles of (C2) relative to the total number of moles of (C1) and (C2) is 2.0 mol% or more, 4.0 mol% or more, 6.0 mol% or more, 8.0 mol% or more, 10.0 mol% or more, 12.0 mol% or more, 20.0 mol% or more, 40.0 mol% or more, 60.0 mol% or more, 80.0 mol% or more, or 90.0 mol% or more. In one embodiment of the present invention, the total number of moles of (C2) relative to the total number of moles of (C1) and (C2) is 95.0 mol% or less, 85.0 mol% or less, 65.0 mol% or less, 55.0 mol% or less, 35.0 mol% or less, 25.0 mol% or less, 23.0 mol% or less, 18.0 mol% or less, 16.0 mol% or less, 14.0 mol% or less, 8.0 mol% or less, or 3.0 mol% or less.

[0062] In one embodiment of the present invention, the mass of (C2) relative to the total mass of (C1) and (C2) is 2.0 to 98.0% by mass. This range allows for more efficient achievement of both droplet formation properties and the texture of the printed material. In another embodiment of the present invention, the mass of (C2) relative to the total mass of (C1) and (C2) is 3.0% by mass or more, 5.0% by mass or more, 10.0% by mass or more, 15.0% by mass or more, 20.0% by mass or more, 25.0% by mass or more, 30.0% by mass or more, 50.0% by mass or more, 70.0% by mass or more, or 90.0% by mass or more. In one embodiment of the present invention, the mass of (C2) relative to the total mass of (C1) and (C2) is 80.0% by mass or less, 60.0% by mass or less, 40.0% by mass or less, 30.0% by mass or less, 28.0% by mass or less, 20.0% by mass or less, 12.0% by mass or less, 8.0% by mass or less, or 4.0% by mass or less.

[0063] According to one embodiment, in the ink according to this embodiment, the total number of moles of the functional groups (amino group, imino group, and hydrazide group) of (C) relative to the total number of moles of the isocyanate groups of (A) is preferably 10 to 40 mol%, more preferably 15 to 30 mol%.

[0064] In one embodiment of the present invention, 65 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more of the total number of moles of all constituent units of the urethane resin consist of constituent units derived from (A), constituent units derived from (B1), constituent units derived from (B2), constituent units derived from (C1), and constituent units derived from (C2). According to one embodiment of the present invention, it is preferable that the polyurethane resin is substantially free of crosslinkable groups (e.g., isocyanate groups). According to one embodiment of the present invention, in order to obtain a polyurethane resin that is substantially free of isocyanate groups, for example, when extending the chains of a urethane prepolymer containing terminal isocyanate groups using a chain extender, the chain extender is used so that no isocyanate groups remain.

[0065] In one embodiment of the present invention, the acid value of the urethane resin is 4 to 32 mg KOH / g, or 5 mg KOH / g or more and less than 30 mg KOH / g, from the viewpoint of storage stability, droplet formation, and the texture (flexibility) of the printed material. The acid value is determined by the carboxyl groups and carboxylate groups (COO) in the urethane resin. - The acid value of urethane resin can be calculated from its content. If the acid value of urethane resin is less than 5 mg KOH / g, the storage stability of the urethane resin aqueous dispersion may decrease, and if it is 30 mg KOH / g or more, the texture of the printed material may deteriorate. The acid value of urethane resin can be calculated as follows: Prepare a sample by dissolving urethane resin in N,N-dimethylformamide. Then, using a potentiometric automatic titrator (product name "AT510", manufactured by Kyoto Electronics Manufacturing Co., Ltd.), the acid value of the urethane resin can be measured by potentiometric titration with potassium hydroxide ethanol titrant.

[0066] In one embodiment of the present invention, the acid value of the urethane resin is 7-25 mgKOH / g, 10-24 mgKOH / g, 15-23 mgKOH / g, or 17-22 mgKOH / g. Being within this range further improves storage stability, droplet formation, and the texture (flexibility) of the printed material.

[0067] (Method for producing an aqueous dispersion of urethane resin containing urethane resin and water) A urethane resin aqueous dispersion containing urethane resin and water according to this embodiment can be manufactured, for example, as follows.

[0068] (Prepolymer preparation) For example, (A) and (B), which contains (B1) and (B2) that react with it, are reacted in amounts that result in a high concentration of isocyanate groups to synthesize a prepolymer having isocyanate groups at the ends. Here, the total number of moles of hydroxyl groups in (B) relative to the total number of moles of isocyanate groups in (A) is preferably 70 to 90 mol%. This range allows for an appropriate viscosity of the isocyanate-terminated prepolymer, facilitating emulsification, and also allows for an appropriate ratio of urethane bonds to urea bonds, thereby suppressing excessive hardening of the urethane resin and improving flexibility and film-forming properties. There are no particular restrictions on the specific method for producing such an isocyanate-terminated prepolymer; for example, it can be produced by a conventionally known one-stage so-called one-shot method, a multi-stage isocyanate polyaddition reaction method, etc. The reaction temperature at this time is preferably 40 to 150°C. The reaction time at this time is preferably 60 to 500 minutes. Furthermore, a solvent that does not react with the isocyanate group may be added during or after the reaction. Examples of such solvents include acetone, methyl ethyl ketone, toluene, and tetrahydrofuran. In this case, a reaction catalyst such as dibutyltin dilaurate, stanus octoate, dibutyltin di-2-ethylhexoate, triethylamine, triethylenediamine, N-methylmorpholine, or bismastris (2-ethylhexanoate), or a reaction inhibitor such as phosphoric acid, sodium hydrogen phosphate, p-toluenesulfonic acid, adipic acid, or benzoyl chloride may be added as needed.

[0069] (neutralization) If a diol compound having a carboxylate group is not used as (B2), or if it is used but the amount used is insufficient to achieve the desired neutralization rate of the urethane resin, the carboxyl group of the prepolymer can be neutralized using any neutralizing agent so that the urethane resin achieves the desired neutralization rate. In this way, neutralization of the isocyanate-terminated prepolymer having a carboxylate group can be carried out using any known method before or after the preparation of the isocyanate-terminated prepolymer having a carboxylate group. Examples of neutralizing agents that can be used for such neutralization include amines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine, N-methyl-diethanolamine, dimethylaminoethanol (also known as N,N-dimethylmonoethanolamine, 2-(dimethylamino)ethanol), N,N-diethylmonoethanolamine, and triethanolamine, as well as potassium hydroxide, sodium hydroxide, ammonia, etc. Among these, tertiary amines such as trimethylamine, triethylamine, tri-n-propylamine, N,N-dimethylmonoethanolamine (2-(dimethylamino)ethanol), and tributylamine are particularly preferred. Preferably, the total number of moles of carboxylate groups relative to the total number of moles of carboxylate groups in the resulting urethane resin is 40 mol% or more. In one embodiment of the present invention, the total number of moles of carboxylate groups relative to the total number of moles of carboxylate groups in the resulting urethane resin is 40 to 100 mol%, or 50 to 80 mol%.

[0070] (emulsification) Next, it is preferable to emulsify and disperse the isocyanate group-terminated prepolymer in water. There are no particular restrictions on the emulsifying equipment used when emulsifying and dispersing in water; for example, homomixers, homogenizers, dispersers, etc., can be used. When emulsifying and dispersing, it is preferable to emulsify and disperse the prepolymer in water at a temperature range of 0 to 40°C without using any emulsifiers in particular, in order to minimize the reaction between the isocyanate group and water. Furthermore, when emulsifying and dispersing in this way, reaction inhibitors such as phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, p-toluenesulfonic acid, adipic acid, and benzoyl chloride can be added as needed.

[0071] (Chain elongation) Next, a chain extension reaction or crosslinking reaction is carried out by contacting the prepolymer with (C), which can function as a chain extender, and other crosslinking agents as needed. For example, a urethane prepolymer containing terminal isocyanate groups, which has been emulsified and dispersed in water, is chain-extended using a chain extender. The reaction between the urethane prepolymer containing terminal isocyanate groups and (C) is usually completed at a reaction temperature of 20 to 50°C, within 30 to 120 minutes after mixing the urethane prepolymer containing terminal isocyanate groups and (C).

[0072] (Solvent removal) If an organic solvent is used in the above process, it is preferable to remove it. The desired removal conditions are under reduced pressure and at 30-80°C.

[0073] The urethane resin aqueous dispersion according to this embodiment contains water, and according to one embodiment of the present invention, the mass of urethane resin (resin solids (non-volatile content)) relative to the total mass of the urethane resin aqueous dispersion is in the range of 20 to 60% by mass. The concentration of resin solids in the urethane resin aqueous dispersion can also be adjusted by adding or distilling off water.

[0074] According to this manufacturing method using a prepolymer, a urethane resin can be obtained that has a prepolymer having isocyanate groups at its terminals, which has a structural unit derived from (A) and a structural unit derived from (B), and a structural unit derived from (C).

[0075] The volume-average particle size (d50) of the resin particles in a urethane resin aqueous dispersion is not particularly limited, but from the viewpoint of reducing nozzle clogging of the inkjet head, it is preferably 300 nm or less, and more preferably 130 nm or less. The lower limit of the volume-average particle size (d50) of the resin particles in a urethane resin aqueous dispersion can be, for example, 10 nm. The volume-average particle size (d50) of the resin particles in a urethane resin aqueous dispersion is measured using a dynamic light scattering particle size distribution analyzer, and is the 50% particle size when the cumulative volume in the cumulative volume particle size distribution reaches 50% from the small particle size side.

[0076] In a urethane resin aqueous dispersion, the glass transition temperature (Tg) of the urethane resin is not particularly limited, but a lower Tg is preferable from the viewpoint of preventing the fabric from hardening easily after image formation and maintaining its texture. The Tg of the urethane resin is 0°C or lower, and preferably between -80°C and 0°C. The Tg can be calculated by dynamic viscoelasticity measurement of the dried film (film-like sample) of the urethane resin dispersion, and is determined as the temperature at which the peak (maximum value) of the loss loss tangent (tanδ), which is the ratio of E' to the loss modulus (E") (E'' / E'), is observed in its temperature dependence.

[0077] The urethane resin aqueous dispersion according to this embodiment includes the following aspects and embodiments.

[0078] [1] A urethane resin aqueous dispersion for inkjet ink comprising (A) a structural unit derived from polyisocyanate, (B) a structural unit derived from polyol, and (C) a structural unit derived from polyamine, and water, wherein the (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group, and the (C) polyamine comprises (C1) a first polyamine having two groups selected from amino groups, imino groups, and hydrazide groups, and (C2) a second polyamine having three or four groups selected from amino groups, imino groups, and hydrazide groups; [2] The urethane resin aqueous dispersion according to [1] above, comprising a structural unit derived from a prepolymer having an isocyanate group at its terminal, having a structural unit derived from (A) and a structural unit derived from (B), and a structural unit derived from (C); [3] The urethane resin aqueous dispersion according to [1] or [2] above, wherein the urethane resin contains a carboxylate group; [4] The urethane resin aqueous dispersion according to any one of [1] to [3] above, wherein the total number of moles of carboxylate groups relative to the total number of moles of carboxylate groups and carboxyl groups in the urethane resin is 40 mol% or more; [5] A urethane resin aqueous dispersion according to any one of [1] to [4] above, wherein the total number of moles of (C2) relative to the total number of moles of (C1) and (C2) is 1.0 to 96.0 mol%; [6] The urethane resin aqueous dispersion according to any one of [1] to [5] above, wherein the acid value of the urethane resin is 5 mg KOH / g or more and less than 30 mg KOH / g; [7] A urethane resin aqueous dispersion according to any one of [1] to [6] above, wherein the total number of moles of hydroxyl groups contained in (B) is 70 to 90 mol% relative to the total number of moles of isocyanate groups contained in (A); [8] A urethane resin aqueous dispersion according to any of [1] to [7] above, wherein (B) does not contain an aliphatic cyclic structure; [9] The urethane resin aqueous dispersion according to any one of the above claims [1] to [8], wherein the total number of moles of (B1) and (B2) is 50 mol% or more of the total number of moles of (B);

[10] A urethane resin aqueous dispersion according to any one of [1] to [9] above, wherein the total number of moles of (C1) and (C2) relative to the total number of moles of (C) is 80 mol% or more;

[11] A urethane resin aqueous dispersion according to any one of [1] to

[10] above, wherein 65 mol% or more of the total number of moles of all constituent units of the urethane resin consists of constituent units derived from (A), constituent units derived from (B1), constituent units derived from (B2), constituent units derived from (C1), and constituent units derived from (C2).

[0079] [organic solvent] The ink according to this embodiment contains an organic solvent. The organic solvent may be any organic compound that is liquid at room temperature and pressure (25°C, 1013 hPa), but it is preferably a water-soluble organic solvent. The water-soluble organic solvent functions not only as a humectant but also as a desiccant.

[0080] In the ink according to this embodiment, the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is 1.0 or greater. A ratio of 1.0 or greater ensures that the colorant and urethane resin particles are stably and highly dispersed, and that excellent injection stability (droplet formation and droplet recovery) is achieved. If the ratio of organic solvent to urethane resin is less than 1.0, the dispersibility of the colorant and urethane resin particles decreases during injection, reducing the stability of the ink. Furthermore, droplet formation and / or droplet recovery also decreases.

[0081] In the ink according to this embodiment, the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is preferably 1.5 or more, more preferably 1.8 or more, even more preferably 2.0 or more, particularly preferably 2.3 or more, and most preferably 2.5 or more. In the ink according to this embodiment, the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is preferably 10 or less, more preferably 8.0 or less, even more preferably 7.0 or less, particularly preferably 6.0 or less, and most preferably 5.0 or less. That is, in the ink according to this embodiment, the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is preferably 1.5 or more and 10 or less, more preferably 1.8 or more and 8.0 or less, even more preferably 2.0 or more and 7.0 or less, particularly preferably 2.3 or more and 6.0 or less, and most preferably 2.5 or more and 5.0 or less. According to one embodiment, in the ink according to this embodiment, the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is greater than 2.1, 2.2 or more, greater than 2.3, or 2.4 or more. According to one embodiment, in the ink according to this embodiment, the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is less than 5.0, 4.5 or less, 4.0 or less, 3.5 or less, or 3.0 or more. If the mass ratio of the organic solvent to the urethane resin is within the above range, the colorant and urethane resin particles can be dispersed more stably and highly, and better injection stability (droplet formation and droplet recovery) can be exhibited.

[0082] As for water-soluble organic solvents, Alcohol-based solvents such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, and n-pentanol; Alkoxy alcohol solvents such as 3-methoxy-3-methyl-1-butanol, 1-methoxy-2-propanol (propylene glycol monomethyl ether), and 3-methoxy-n-butanol; Diol solvents such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,3-propanediol, isobutylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,2-propanediol, 2-methyl-1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,2-hexanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, and 2-methyl-2,4-pentanediol; Triols such as glycerin, trimethylolethane, trimethylolpropane, and 1,2,6-hexanetriol: Tetrahydric alcohol solvents such as diglycerin, mesoerythritol, and pentaerythritol; Monoalkyl ether solvents of polyhydric alcohols such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether (3-methoxy-1-butanol), dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether; Dialkyl ether solvents of polyhydric alcohols such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol ethyl methyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol ethyl methyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol ethyl methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol ethyl methyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, and tripropylene glycol ethyl methyl ether; Ketone solvents or keto alcohol solvents such as acetone, methyl ethyl ketone, diacetone alcohol, and texanol (3-hydroxy-2,2,4-trimethylpentyl 2-methylpropanoate); Ether-based solvents such as tetrahydrofuran and dioxane (including 1,4-dioxane, etc.); Oxyethylene or oxypropylene (co)polymer solvents such as polyethylene glycol (e.g., polyethylene glycol with a mass-average molecular weight of 200) and polypropylene glycol; Amide solvents such as formamide, acetamide, propanamide, butanamide, isobutylamide, pentanamide, N-methylformamide, N-methylacetamide, N-methylpropanamide, N-methylbutanamide, N-methylisobutylamide, N-methylpentanamide, N-ethylformamide, and N-ethylacetamide; Amide solvents such as 2-pyrrolidone, N-methylpyrrolidone, 3-methoxy-N,N-dimethipropionamide, and 3-butoxy-N,N-dimethylpropionamide; Morpholine-based solvents such as N-methylmorpholine, N-ethylmorpholine, N-formylmorpholine, N-hydroxyethylmorpholine, 2-hydroxyethylmorpholine, and 4-acetylmorpholine; Urea-based solvents such as tetramethylurea and dimethylimidazolidinone; Carbonate solvents such as ethylene carbonate, 2,3-butylene carbonate, dimethyl carbonate, and propylene carbonate; Acetate solvents such as ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, tripropylene glycol monomethyl ether acetate, ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, and 3-methoxybutyl acetate; Lactone-based solvents such as γ-butyrolactone, α-methylene-γ-butyrolactone, ε-caprolactone, γ-valerolactone, γ-hexanolactone, γ-heptanolactone, δ-valerolactone, δ-hexanolactone, δ-heptalactone, δ-octaractone, δ-nonalactone, δ-decalactone, δ-undecalactone, γ,γ-dimethyl-γ-butyrolactone, α-methyl-γ-butyrolactone, γ-clotractone, α-methylene-γ-butyrolactone, β-methyl-γ-butyrolactone, and 6-methylvalerolactone; Examples include the following. The water-soluble organic solvent may be used alone or in combination of two or more.

[0083] According to one embodiment, the water-soluble organic solvent preferably contains a solvent with a boiling point of 200°C or lower from the viewpoint of moisturizing and preventing drying. Also according to one embodiment, the water-soluble organic solvent preferably contains a solvent with a boiling point of 250°C or higher in order to prevent complete drying in the inkjet head.

[0084] According to one embodiment, the water-soluble organic solvent preferably contains a glycol-based solvent from the viewpoint of moisturizing and preventing drying. When the water-soluble organic solvent is a glycol-based solvent, the dispersibility of the colorant can be further improved, resulting in a stable and highly dispersed ink. Here, the glycol-based solvent may mean a compound having two hydroxyl groups (glycol compound) or an ether compound in which one or both hydrogen atoms of the hydroxyl group are substituted with another group. The ether compound is preferably an aliphatic ether compound. Furthermore, an ether compound in which one hydrogen atom of the hydroxyl group of the glycol compound is substituted with another group is also preferred.

[0085] Examples of glycol-based solvents include alkoxy alcohol-based solvents such as 3-methoxy-3-methyl-1-butanol, 1-methoxy-2-propanol (propylene glycol monomethyl ether), and 3-methoxy-n-butanol; ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,3-propanediol, isobutylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,2-propanediol, and 2-methyl-1,2-propanediol. Diol-based solvents such as diols, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,2-hexanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, and 2-methyl-2,4-pentanediol; oxyethylene or oxypropylene (co)polymer-based solvents such as polyethylene glycol (e.g., polyethylene glycol with a mass-average molecular weight of 200) and polypropylene glycol;Ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether (3-methoxy-1-butanol), dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol mono-n-butyl ether, Monoalkyl ether solvents for polyhydric alcohols such as tetraethylene glycol mono-n-butyl ether; dialkyl ether solvents for polyhydric alcohols such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol ethyl methyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol ethyl methyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol ethyl methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol ethyl methyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, and tripropylene glycol ethyl methyl ether;These are some examples. Among these, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, isobutylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, and polyethylene glycol (for example, polyethylene glycol with a mass-average molecular weight of 200) are preferred.

[0086] According to one embodiment, the water-soluble organic solvent preferably contains a glycol-based solvent with an octanol / water partition coefficient of -1.80 or less. In this case, the stability of the droplets ejected during inkjet printing is high, and the ejection stability (droplet formation and droplet recovery) is even better. The octanol / water partition coefficient is the ratio of the concentration of the substance in the octanol when the substance is dissolved in a mixture of octanol and water, preferably containing a glycol-based solvent of -1.90 or less, preferably containing a glycol-based solvent of -1.95 or less, and preferably containing a glycol-based solvent of -2.00 or less, and is expressed in Kow or the common logarithm Log Kow. In this specification, the value of the common logarithm Log Kow is used. The "1-octanol / water partition coefficient" (hereinafter referred to as "partition coefficient") of the water-soluble organic solvent is measured by the method described in the examples. The glycol-based solvent is more preferably having an octanol / water partition coefficient of -1.90 or less, even more preferably -1.95 or less, and particularly preferably -2.00 or less. The octanol / water partition coefficient of the glycol-based solvent is preferably -15.0 or higher, more preferably -12.0 or higher, even more preferably -10.0 or higher, particularly preferably -8.00 or higher, and most preferably -5.00 or lower.

[0087] Examples of partition coefficients and boiling points for water-soluble organic solvents include, for example, glycerin (partition coefficient: -1.76, boiling point: 290°C), propylene glycol (partition coefficient: -0.92, boiling point: 188°C), dipropylene glycol (partition coefficient: -0.75, boiling point: 232°C), diethylene glycol (partition coefficient: -1.39, boiling point: 244°C), triethylene glycol (partition coefficient: -1.98, boiling point: 285°C), tetraethylene glycol (partition coefficient: -2.02, boiling point: 314°C), and polyethylene glycol with a mass-average molecular weight of 200 (partition coefficient: -2.02, boiling point: Examples include polyethylene glycol with a mass-average molecular weight of 400 (partition coefficient: -3.67, boiling point: >200°C), polyethylene glycol with a mass-average molecular weight of 1000 (partition coefficient: -7.13, boiling point: >200°C), polyethylene glycol with a mass-average molecular weight of 2000 (partition coefficient: -13.33, boiling point: >200°C), triethylene glycol monoethyl ether (partition coefficient: -2.79, boiling point: 255°C), ethylene glycol (partition coefficient: -1.36, boiling point: 197°C), and 1,2-hexanediol (partition coefficient: 0.58, boiling point: 170°C).

[0088] In the ink according to this embodiment, it is preferable to use a combination of two or more water-soluble organic solvents. According to one embodiment, in the ink according to this embodiment, it is preferable to use a combination of a solvent with a boiling point of 200°C or lower and a solvent with a boiling point of 250°C or higher. That is, according to one embodiment, in the ink according to this embodiment, the water-soluble organic solvent includes a solvent with a boiling point of 200°C or lower and a solvent with a boiling point of 250°C or higher. The solvent with a boiling point of 200°C or lower is preferably a glycol-based solvent. This makes it possible to further improve the dispersibility of the colorant and urethane resin particles, and to obtain a stable and highly dispersed ink. For example, the excellent dispersibility in the ink further improves droplet recovery in injection stability. Therefore, according to one embodiment, in the ink according to this embodiment, the water-soluble organic solvent includes a solvent with a boiling point of 250°C or higher and a glycol-based solvent with a boiling point of 200°C or lower.

[0089] In the ink according to this embodiment, it is preferable to use a combination of three or more water-soluble organic solvents. According to one embodiment, the ink according to this embodiment contains a solvent with a boiling point of 200°C or less; a solvent with a boiling point of 250°C or more; and a glycol-based solvent with an octanol / water partition coefficient greater than -1.80. That is, the water-soluble organic solvent contains, for example, a solvent with a boiling point of 200°C or less (preferably a glycol-based solvent with a boiling point of 200°C or less); a solvent with a boiling point of 250°C or more; and a glycol-based solvent with an octanol / water partition coefficient of -1.80 or less. This makes it possible to further improve the dispersibility of the colorant and urethane resin particles, and to obtain a stable and highly dispersed ink. For example, the excellent dispersibility of the ink further improves droplet formation in terms of injection stability.

[0090] In the ink according to this embodiment, it is preferable to use a combination of two or more glycol-based solvents as the water-soluble organic solvent. According to one embodiment, the ink according to this embodiment contains a solvent with a boiling point of 250°C or higher; a first glycol-based solvent with a boiling point of 200°C or lower; and a second glycol-based solvent with an octanol / water partition coefficient of -1.80 or lower. That is, in the ink according to this embodiment, it is preferable that the water-soluble organic solvent contains a solvent with a boiling point of 250°C or higher; a first glycol-based solvent with a boiling point of 200°C or lower; and a second glycol-based solvent with an octanol / water partition coefficient of -1.80 or lower. This makes it possible to further improve the dispersibility of the colorant and urethane resin particles, and to obtain a stable and highly dispersed ink. For example, the excellent dispersibility of the ink further improves droplet formation and droplet recovery in injection stability.

[0091] The octanol / water partition coefficient of the first glycol-based solvent is not particularly limited, but is preferably greater than -1.80, more preferably greater than -1.5, even more preferably greater than -1.2, and particularly preferably greater than -1.0. The second glycol-based solvent is more preferably less than or equal to -1.90, even more preferably less than or equal to -1.95, and particularly preferably less than or equal to -2.00. The boiling point of the second glycol-based solvent is not particularly limited, but is preferably greater than 200°C.

[0092] As a solvent with a boiling point of 250°C or higher, glycerin is preferably used, for example. As a first glycol-based solvent, propylene glycol, ethylene glycol, etc., are preferably used, and as a second glycol-based solvent, triethylene glycol, tetraethylene glycol, polyethylene glycol 200, etc., are preferably used. When the water-soluble organic solvent contains a solvent with a boiling point of 250°C or higher (hereinafter referred to as "solvent a1") and a glycol-based solvent (hereinafter referred to as "solvent a2"), the content ratio of solvent a1 to solvent a2 (solvent a1:solvent a2) (mass ratio) is preferably 1:99 to 95:5, more preferably 5:95 to 90:10, even more preferably 10:80 to 80:20, particularly preferably 20:80 to 70:30, and most preferably 30:70 to 60:40. By keeping the content ratio of solvent a1 to solvent a2 within the above range, it is possible to obtain printed materials with excellent friction fastness, prevent nozzle clogging caused by ink drying or thickening, and provide a recording method with excellent ejection stability over a wide temperature range.

[0093] When the aqueous organic solvent contains two glycol-based solvents, a first glycol-based solvent (hereinafter referred to as "solvent b1") having a boiling point of 200°C or less, and a second glycol-based solvent (hereinafter referred to as "solvent b2") having an octanol / water partition coefficient of -1.80 or less, the content ratio (solvent b1:solvent b2) (mass ratio) of solvent b1 to solvent b2 is preferably 1:99 to 95:5, more preferably 5:95 to 90:10, even more preferably 10:80 to 80:20, particularly preferably 20:80 to 60:40, and most preferably 25:75 to 50:50. By having the content ratio of solvent b1 to solvent b2 within the above range, it is possible to obtain printed materials with excellent friction fastness, prevent nozzle clogging due to ink drying or thickening, and provide a recording method with excellent discharge stability over a wide temperature range.

[0094] According to one embodiment, the organic solvent is one or more selected from the group consisting of glycerin, propylene glycol, ethylene glycol, 1,2-hexanediol, dipropylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and triethylene glycol monoethyl ether.

[0095] The organic solvent content is preferably, for example, 10% to 50% by mass, more preferably 15% to 45% by mass, even more preferably 18% to 42% by mass, particularly preferably 20% to 40% by mass, and most preferably 22% to 35% by mass, based on the total mass of the ink (100% by mass). If the organic solvent content is within the above range, the dispersibility of the colorant can be further improved, and a stable and highly dispersed ink can be obtained. If two or more organic solvents are included, the organic solvent content shall be the total amount of those solvents.

[0096] The content of the organic solvent is preferably such that the mass ratio of the organic solvent to the colorant (mass of organic solvent / mass of colorant) is 0.1 to 20.0, more preferably 0.5 to 15.0, even more preferably 1.0 to 12.0, particularly preferably 1.5 to 10.0, and most preferably 2.0 to 9.5. In one embodiment, the mass ratio of the organic solvent to the colorant (mass of organic solvent / mass of colorant) may be 3.0 to 10.0, 4.0 to 10.0, 5.0 to 10.0, or 5.5 to 9.0.

[0097] [water] The ink according to this embodiment may contain water. Preferably, the water used is deionized water, distilled water, or purified water.

[0098] The water content is preferably such that the mass ratio of water to organic solvent (mass of water / mass of organic solvent) is 0.1 to 20.0, more preferably 0.2 to 15.0, even more preferably 0.3 to 10.0, particularly preferably 0.5 to 8.0, and most preferably 1.2 to 7.0. According to one embodiment, the mass ratio of organic solvent to colorant (mass of organic solvent / mass of colorant) may be 1.0 to 6.0, 1.0 to 5.0, 1.0 to 4.0, 1.5 to 5.0, 2.0 to 5.0, or 2.0 to 4.0.

[0099] The water content is preferably, for example, 20% to 90% by mass, more preferably 25% to 88% by mass, even more preferably 30% to 85% by mass, particularly preferably 40% to 82% by mass, and most preferably 50% to 80% by mass, relative to the total mass of the ink (100% by mass).

[0100] [Coloring agent] The ink according to this embodiment may contain a coloring agent. Pigments or dyes can be used as the coloring agent. In the ink according to this embodiment, pigments are preferred as the coloring agent because they have good dispersibility with respect to the ink's components and excellent weather resistance. The coloring agent may also be a solid coloring agent.

[0101] The pigment contained in the ink according to this embodiment is not particularly limited, but is preferably an organic or inorganic pigment of the following numbers listed in the color index.

[0102] Examples of orange pigments include Pigment Orange 31 and 43.

[0103] Examples of red or magenta pigments include: Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257; Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88; Pigment Orange This includes 13, 16, 20, 34, 36, and 43. Mixed crystals may be used as the red or magenta pigment.

[0104] Examples of blue or cyan pigments include Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36, and 60.

[0105] Examples of green or yellow pigments include Pigment Green 7, 26, 36, and 50. Examples of yellow pigments include Pigment Yellow 1, 3, 12, 13, 14, 15, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 128, 137, 138, 139, 151, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, and 213.

[0106] Examples of black pigments include Pigment Black 7, 28, and 26.

[0107] Examples of commercially available pigments include Chromofine Yellow 2080, 5900, 5930, AF-1300, 2700L, Chromofine Orange 3700L, 6730, Chromofine Scarlet 6750, Chromofine Magenta 6880, 6886, 6891N, 6790, 6887, Chromofine Violet RE, Chromofine Red 6820, 6830, Chromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, and 5000P. Chromofine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Chromofine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400(B), 2500, 2600, ZAY-260, 2700(B), 2770 Seika Fast Red 8040, C405(F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmine 6B1476T-7, 1483LT, 3840, 3870, Seika Fast Bordeaux 10B-430, Seika Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C718, A612, Cyanine Blue 4933M, 4933GN-EP, 4940, 4973 (manufactured by Dainichi Seika Kogyo); KET Yellow 401, 402, 403, 404, 405, 406, 416, 424; KET Orange 501; KET Red 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346; KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124; KET Green 201; FirstGen Super Magenta RY (manufactured by DIC Corporation);Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pigment Yellow1705, Colortex Orange 202, Colortex Red101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, USN, Colortex Maroon601, Colortex BrownB610N, Colortex Violet600, Pigment Red 122, Colortex Blue516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403, Colortex Black 702, U905 (manufactured by Sanyo Pigment); Lionol Yellow 1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink), Toner Magenta E02, Permanent Rubin F6B, Toner Yellow HG, Permanent Yellow GG-02, Hostapean Blue B2G (manufactured by Hoechst Industries); Novoperm P-HG, Hostapean Pink E, Hostapean Blue B2G (Clarant); includes carbon black #2600, #2400, #2350, #2200, #1000, #990, #980, #970, #960, #950, #850, MCF88, #750, #650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77, #52, #50, #47, #45, #45L, #40, #33, #32, #30, #25, #20, #10, #5, #44, and CF9 (Mitsubishi Chemical).

[0108] From the viewpoint of improving dispersibility in the ink, it is preferable that the pigment is further dispersed with a pigment dispersant. Pigment dispersants will be described later.

[0109] Furthermore, the pigment may be a self-dispersing pigment. A self-dispersing pigment has a surface modified with a hydrophilic group, and comprises pigment particles and a hydrophilic group bonded to its surface. Examples of hydrophilic groups include carboxyl groups, sulfonic acid groups, and phosphorus-containing groups. Examples of phosphorus-containing groups include phosphate groups, phosphonic acid groups, phosphinic acid groups, phosphite groups, and phosphate groups.

[0110] Examples of commercially available self-dispersing pigments include: Cabot Corporation's Cab-0-Jet® 200K, 250C, 260M, 270V (self-dispersing pigment containing sulfonic acid groups), Cab-0-Jet(registered trademark) 300K (carboxylic acid group-containing self-dispersing pigment), Cab-0-Jet (registered trademark) 400K, 450C, 465M, 470V, 480V (phosphate-containing self-dispersing pigment) It includes.

[0111] The dye is preferably a solid dye, such as a disperse dye.

[0112] Examples of disperse dyes include CIDisperse Yellow: 3, 4, 5, 7, 9, 13, 23, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63, 64, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 108, 114, 116, 118, 1 19, 122, 124, 126, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 184 , 186, 192, 198, 199, 202, 204, 210, 211, 215, 216, 218, 224, 227, 231, 232;CIDisperse Orange:1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 46, 47, 48, 49, 50, 53, 5 4,55,56,57,58,59,61,66,71,73,76,78,80,89,90,91,93,96,97,119,127,130,139,142;CIDisperse Red:1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 9 3, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134,135, 137, 143, 145, 146, 151, 152, 1 53, 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221 ,224,225,227,229,239,240,257,258,277,278,279,281,288,298,302,303,310,311,312,320,324,328,337,343 Violet:1, 4, 8, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63, 69, 77;CIDisperse Green9;CIDisperse Brown:1, 2, 4, 9, 13, 19;CIDisperse Blue:3, 7, 9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 73, 75, 77, 79, 79:1, 79:2, 81, 82, 83 , 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 1 Includes 53, 154, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 281, 284, 285, 287, 288, 291, 291:1, 293, 295, 297, 301, 315, 330, 333, 373; and CID Disperse Black 1, 3, 10, 24.

[0113] The amount of colorant is not particularly limited, but from the viewpoint of easily adjusting the viscosity of the ink to the range described later and forming a higher density image, it is preferable that it be between 0.3% by mass and 12.0% by mass relative to the total mass of the ink. If the amount of colorant is 0.3% by mass or more relative to the total mass of the ink, the resulting image tends to have vivid colors, and if it is 12.0% by mass or less, the viscosity of the ink does not become too high, so the ejection stability is less likely to be impaired. From the same viewpoint, it is more preferable that the amount of colorant is between 0.5% by mass and 8.0% by mass relative to the total mass of the ink.

[0114] The content of the colorant is preferably such that the mass ratio of the colorant to the urethane resin (mass of colorant / mass of urethane resin) is 0.05 to 2.0, more preferably 0.06 to 1.5, even more preferably 0.08 to 1.2, particularly preferably 0.1 to 1.0, and most preferably 0.1 to 0.8. According to one embodiment, the mass ratio of the colorant to the urethane resin (mass of colorant / mass of urethane resin) may be 0.06 to 1.0 or 0.06 to 0.6. If the mass ratio of the colorant to the urethane resin is within the above range, the dispersibility of the colorant can be further improved, and a stable and highly dispersed ink can be obtained.

[0115] When a pigment is used as a coloring agent, the same mass ratio of pigment to urethane resin (mass of pigment / mass of urethane resin) as described above can be suitably applied. That is, the mass ratio of pigment to urethane resin (mass of pigment / mass of urethane resin) is preferably 0.05 to 2.0, more preferably 0.06 to 1.5, even more preferably 0.08 to 1.2, particularly preferably 0.1 to 1.0, and most preferably 0.1 to 0.8. According to one embodiment, the mass ratio of pigment to urethane resin (mass of pigment / mass of urethane resin) may be 0.06 to 1.0 or 0.06 to 0.6. If the mass ratio of pigment to urethane resin is within the above range, the dispersibility of the pigment can be further improved, and a stable and highly dispersed ink can be obtained.

[0116] [Pigment dispersant] In the present embodiment of the ink, when a pigment is used as a coloring agent, a pigment dispersant may be included. The pigment dispersant exists in the ink so as to surround the surface of the pigment particles, or is adsorbed onto the surface of the pigment particles to form a pigment dispersion, thereby effectively dispersing the pigment. The pigment dispersant included in the present embodiment of the ink is preferably a polymer dispersant, and more preferably an anionic polymer dispersant.

[0117] Anionic polymer dispersants are polymer dispersants having hydrophilic groups such as carboxylic acid groups, phosphorus-containing groups, and sulfonic acid groups, and are preferably polymer dispersants having carboxylic acid groups.

[0118] Polymeric dispersants having a carboxylic acid group may be polycarboxylic acids or salts thereof. Examples of polycarboxylic acids include (co)polymers of monomers selected from acrylic acid or its derivatives, maleic acid or its derivatives, itaconic acid or its derivatives, fumaric acid or its derivatives, and salts thereof. Examples of other monomers that make up copolymers include styrene and vinylnaphthalene.

[0119] From the viewpoint of sufficiently dispersing pigment particles, the anionic group equivalent of an anionic polymer dispersant is preferably, for example, 1.1 to 3.8 meq / g. When the anionic group equivalent is within the above range, high pigment dispersibility can be easily obtained without increasing the molecular weight of the anionic polymer dispersant. The anionic group equivalent of an anionic polymer dispersant can be determined from the acid value. The acid value can be measured in accordance with JIS K0070.

[0120] The weight-average molecular weight (Mw) of the polymeric dispersant is not particularly limited, but is preferably between 5,000 and 30,000. If the Mw of the polymeric dispersant is 5,000 or higher, the pigment particles are easily dispersed, and if it is 30,000 or lower, the ink does not become excessively thickened, so the penetration into the fabric is not easily impaired. The Mw of the polymeric dispersant can be measured by the same method as described above.

[0121] The content of the polymer dispersant is not particularly limited, as long as it is within a range that sufficiently disperses the pigment particles and has a viscosity that does not impair the penetration into the fabric. However, it is preferably 20 to 100% by mass relative to the pigment, and more preferably 25 to 60% by mass. These pigment dispersants may be used alone or in combination of two or more types.

[0122] [Other ingredients] The ink according to this embodiment may further contain other components as needed. Examples of other components include additives such as neutralizing agents. It is preferable that the ink according to this embodiment does not contain polyhydric alcohols and betaine, which are solid at room temperature, because these remain on the fabric after drying.

[0123] (Additives) Examples of additives include neutralizing agents, surfactants, preservatives, fungicides, and pH adjusters.

[0124] In the ink according to this embodiment, when the urethane resin has anionic groups such as carboxyl groups and sulfonic acid groups, the ink may further contain a neutralizing agent. The neutralizing agent can be a known basic compound, such as sodium hydroxide, potassium hydroxide, ammonia, or triethylamine. In the ink according to this embodiment, when a pigment is used as a coloring agent, the inclusion of a neutralizing agent in the pigment dispersion moderately promotes the dissociation of the anionic groups in the pigment dispersion, thereby improving dispersibility.

[0125] The amount of neutralizing agent is not particularly limited, but it is preferable to include an amount such that the neutralization rate is between 30% and 100%. The above neutralization rate can be calculated using the following formula (A).

[0126] Neutralization rate (%)= (Mass of basic compound [g] / (Equivalent weight of basic compound [g / mol] × Valency of basic compound)) ÷ ((Acid value of pigment dispersant [mgKOH / g] × Mass of pigment dispersant [g]) / (56 [g / mol] × 1000)) Formula (A) Surfactants can lower the surface tension of ink, thereby increasing its wettability to fabrics. The type of surfactant is not particularly limited, but examples include acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants. Examples of commercially available surfactants include Olphine E1010 (manufactured by Nisshin Chemical Industry Co., Ltd.).

[0127] Examples of preservatives or fungicides include aromatic halogen compounds (e.g., Preventol CMK), methylenedithiocyanates, halogenated nitrogen-sulfur compounds, and 1,2-benzisothiazolin-3-one (e.g., PROXEL GXL).

[0128] Examples of pH adjusters include citric acid, sodium citrate, potassium citrate, hydrochloric acid, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and organic amines.

[0129] Method for manufacturing inkjet ink The inkjet ink of this embodiment can be manufactured by any method. The urethane resin contained in the inkjet ink of this embodiment is preferably manufactured by solution polymerization using an organic solvent (preferably a water-soluble organic solvent), and more preferably by solution polymerization (emulsion polymerization) using water, as described above in the method for manufacturing a urethane resin aqueous dispersion containing urethane resin and water. When these organic solvents (preferably water-soluble organic solvents, more preferably water) are used as solvents, it is possible to prepare a colorant dispersion (e.g., a pigment dispersion) using the polymer solution obtained by polymerization (i.e., a urethane resin dispersion, preferably a urethane resin aqueous dispersion) as is, thereby simplifying the process. For example, the inkjet ink of this embodiment can be manufactured by (i) mixing a colorant, a colorant dispersant (e.g., a pigment dispersion), and a solvent (water, etc.) to obtain a colorant dispersion; and (ii) mixing the obtained colorant dispersion, the urethane resin aqueous dispersion according to this embodiment, an organic solvent, and water as needed.

[0130] Inkjet Printing Method The present invention also provides an inkjet printing method for recording by adhering inkjet ink according to this embodiment to a fabric. That is, the present invention also provides an image forming method that includes the step of applying droplets of inkjet ink according to this embodiment onto a fabric using an inkjet method. Hereinafter, the inkjet printing method (image forming method) will be referred to as the printing method according to this embodiment.

[0131] The printing method according to this embodiment specifically includes: (1) a step of ejecting inkjet ink from an inkjet recording head and applying droplets of inkjet ink onto the fabric (ink application step); and (2) a step of drying and fixing the inkjet ink applied to the fabric (drying and fixing step).

[0132] Furthermore, the printing method according to this embodiment may further include, if necessary, (3) a step of pre-treating the fabric (pre-treatment step) and (4) a step of applying a post-treatment solution (post-treatment step).

[0133] Ink application process (process (1)) This process involves ejecting inkjet ink from an inkjet recording head and applying droplets of inkjet ink onto a fabric.

[0134] The type of fiber material that makes up the fabric is not particularly limited and includes natural fibers such as cotton (cellulose fiber), linen, wool, and silk; synthetic fibers such as rayon, vinylon, nylon, acrylic, polyurethane, polypropylene, polyester, acetate, triacetate, polyamide, and polyurethane; and biodegradable fibers such as polylactic acid. Blends of these fibers are also acceptable. The fabric can be made from the fibers listed above in any form, such as woven, knitted, or nonwoven. Of these, the fabric used in the printing method according to this embodiment is more preferably made from cellulose-containing fibers such as cotton and linen. Using such a fabric allows for better fixation of the colorant.

[0135] In the present invention, the printing method is preferable in which the fabric has cationic groups or acidic groups on at least its surface, from the viewpoint of improving the adsorption rate and fixation of the colorant. The fabric having cationic groups or acidic groups on at least its surface may be pre-treated or not. For example, by going through the step of (3) pre-treating the fabric (pre-treatment step), a fabric having cationic groups or acidic groups on at least its surface can be obtained.

[0136] Drying and fixing process (process (2)) In the drying process, the inkjet ink applied to the fabric is dried to remove the solvent components from the inkjet ink. This fixes the colorant to the fabric.

[0137] The drying method is not particularly limited and may include methods using heaters, hot air dryers, heated rollers, etc. Among these, it is preferable to heat and dry both sides of the fabric using a hot air dryer and a heater.

[0138] The drying temperature should be set to evaporate the solvent components in the inkjet ink. Specifically, the drying temperature is preferably above the temperature at which the solvent components evaporate and below (Tg + 170)°C (where Tg refers to the Tg of the urethane resin particles). The drying temperature may also be room temperature.

[0139] In the printing method according to this embodiment, because the Tg of the resin particles applied to the fabric is low, even if the resin particles fuse together when the inkjet ink dries, they are less likely to form a hard film. As a result, the texture of the fabric is less likely to be damaged.

[0140] Pre-treatment process (step (3)) The printing method according to this embodiment may further include, if necessary, (3) a step of pre-treating the fabric (pre-treatment step). In the pre-treatment step, a pre-treatment solution is applied to the fabric. The type of pre-treatment solution is not particularly limited and can be selected according to the composition of the inkjet ink. For example, in the above inkjet ink, the pre-treatment solution preferably contains a compound having an acidic group or a cationic group. The compound having an acidic group or a cationic group contained in the pre-treatment solution agglomerates the urethane resin contained in the inkjet ink and the anionic component contained in the second treatment solution. Aggregation is preferably carried out using an electrical action.

[0141] Examples of cationic groups in compounds having acidic or cationic groups include secondary amino groups, tertiary amino groups, and quaternary ammonium bases. Examples of compounds having acidic or cationic groups include cationic resins and cationic surfactants, with cationic resins being preferred.

[0142] Examples of cationic resins include cationic urethane resins, cationic olefin resins, and cationic alkylamine resins. Examples of commercially available products include MPT-60 (manufactured by Mitsubishi Pencil Co., Ltd.), Unisense KHE100L (manufactured by Senka Co., Ltd.), and MZ477 (manufactured by Takamatsu Oil & Fat Co., Ltd., a urethane resin). Among these, cationic alkylamine resins MPT-60 and Unisense KHE100L (manufactured by Senka Co., Ltd.) are preferred from the viewpoint of being more likely to interact or react with the block copolymers mentioned above.

[0143] The method of applying the pretreatment solution is not particularly limited and may include, for example, a pad method, a coating method, a spray method, or an inkjet method. The pretreatment solution applied to the fabric can also be heated and dried using hot air, a hot plate, or a heat roller.

[0144] Post-processing steps (step (4)) The printing method according to this embodiment may further include, if necessary, a step of applying a post-treatment solution (post-treatment step). In the post-treatment step, the post-treatment solution is applied to the inkjet ink applied to the fabric. The second treatment solution preferably contains an anionic component. The anionic component can be the same as that of an anionic resin dispersion (i.e., urethane resin aqueous dispersion) contained in the inkjet ink. The preferred range of acid value, Tg and average particle size of the urethane resin aqueous dispersion contained in the second treatment solution is also the same as that of the urethane resin aqueous dispersion contained in the inkjet ink.

[0145] The post-treatment solution can be applied in the same manner as the pre-treatment solution. Among these, the spray method and the inkjet method are preferred.

[0146] As described above, the present invention also provides a method for producing an inkjet printed fabric, comprising the steps of: applying a pretreatment solution to the inkjet ink printing area of ​​a fabric; printing an inkjet ink containing a urethane resin and an organic solvent onto the inkjet ink printing area of ​​the fabric; and heating the fabric to which the treatment solution and ink have been applied and printed, wherein the urethane resin has (A) a structural unit derived from polyisocyanate, (B) a structural unit derived from polyol, and (C) a structural unit derived from polyamine, the (B) polyol includes (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group, and the (C) polyamine includes (C1) a first polyamine having two groups selected from an amino group, an imino group, and a hydrazide group, and (C2) a second polyamine having three or four groups selected from an amino group, an imino group, and a hydrazide group.

[0147] [Inkjet Ink Set] In the printing method according to this embodiment, the inkjet ink used is preferably used together with a pretreatment solution. Therefore, according to one embodiment, the present invention also provides an inkjet ink set including the inkjet ink and a pretreatment solution.

[0148] The inkjet ink set includes a pretreatment solution and the inkjet ink described above, and may further include a posttreatment solution. It is preferable that the inkjet ink set includes a posttreatment solution. Including a posttreatment solution in the inkjet ink set makes it easier to improve friction fastness.

[0149] Printed fabrics The resulting printed material (image-forming material) includes a fabric and an image layer placed on the fabric.

[0150] The image layer contains components derived from the inkjet ink described above, and may further contain components derived from other liquids such as post-processing solutions, if necessary. For example, the image layer contains an ink layer, and may further contain other layers such as a post-processing layer, if necessary.

[0151] Thus, the image layer contains a urethane resin derived from the inkjet ink mentioned above. Therefore, the resulting printed material (image-forming material) maintains a good texture while possessing good abrasion fastness.

[0152] 《Friction resistance》 Dry friction fastness can be measured by the following procedure. The resulting image-formed material is subjected to a dry friction fastness test using a Type I testing machine in accordance with JIS L0849:2013 and evaluated using a stain grayscale. Specifically, a load of approximately 9N is applied to the image-formed portion, and a 100mm length of cotton cloth is subjected to 10 back-and-forth frictions against the printed material (evaluation fabric). The cotton cloth is moistened to approximately 100% using the method described in the JIS standard. After applying friction to the printed material (evaluation fabric), the density of the color adhering to the cotton cloth is determined using the corresponding grade on the stain grayscale.

[0153] Texture The texture can be measured using the following procedure: Using a KES-FB2-A pure bending tester (manufactured by Kato Tech Co., Ltd.), the bending stress B-MEAN [gf × cm] can be measured. 2The width [ / cm] is measured and the difference ΔB from the unprocessed fabric is calculated. The width of the fabric is assumed to be 20cm. For the evaluation of texture, a ΔB of 0.12 or less is preferable, 0.09 or less is more preferable, and 0.06 or less is even preferable.

[0154] 《Droplet formation》 Droplet formation performance can be measured by the following procedure. After introducing ink into the KM1024i head in an environment with ambient temperature and humidity of 20°C and 40% RH, droplet formation performance (stability of droplet formation) is evaluated by continuous ejection evaluation. Droplet formation performance is preferably such that slight satellites and slight main droplet deviation occur (acceptable droplet formation performance), more preferably such that slight satellites occur (good droplet formation performance), and even more preferably no satellites occur (excellent droplet formation performance).

[0155] 《Droplet recovery property》 Droplet recovery performance can be measured by the following procedure. In a standard environment with ambient temperature and humidity of 20°C and 40% RH, droplet recovery performance is evaluated by the ejection recovery performance after introducing ink into the KM1024i head and leaving it in an unhumidified state for 10 minutes. Preferably, droplet recovery performance is such that all nozzles recover with simple maintenance (acceptable droplet recovery performance), more preferably that all nozzles recover with ejection operation (good droplet recovery performance), and even more preferably that all nozzles recover with a short ejection operation (excellent droplet recovery performance).

[0156] Ink storage stability The inkjet ink according to this embodiment exhibits excellent ink storage stability. Ink storage stability can be measured by the following procedure: The viscosity of the ink after being stored at 50°C for 14 days is measured using an E-type viscometer, and the difference in viscosity compared to ink stored at room temperature (25°C) for 14 days is calculated. Preferably, the ink viscosity fluctuation is ±0.3 mPa·s or more and less than ±0.5 mPa·s (acceptable ink storage stability), more preferably, the ink viscosity fluctuation is ±0.2 mPa·s or more and less than ±0.3 mPa·s (good ink storage stability), even more preferably, the ink viscosity fluctuation is ±0.1 mPa·s or more and less than ±0.2 mPa·s, and particularly preferably, the ink viscosity fluctuation is less than ±0.1 mPa·s (significantly superior ink storage stability). [Examples]

[0157] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively. In addition, in the following examples, unless otherwise specified, the operations were carried out under conditions of room temperature (20°C to 25°C) and relative humidity of 30%RH to 50%RH.

[0158] Manufacturing of binder resin dispersions (1) Preparation of urethane resin aqueous dispersion 1 (combination of difunctional and trifunctional chain extenders) 205.6 parts by mass (40.0 mol) of polytetramethylene glycol (number average molecular weight 2,000), 14.9 parts by mass (43.3 mol) of dimethylolpropionic acid, and 123.4 parts by mass of methyl ethyl ketone as a solvent were weighed into a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen blowing tube, and after being uniformly mixed, 67.3 parts by mass (100.0 mol) of dicyclohexylmethane diisocyanate were added, and the mixture was reacted at 85±5℃ for 300 minutes to obtain a methyl ethyl ketone solution of a urethane prepolymer containing terminal isocyanate groups with an isocyanate group content of 1.30% by mass (hereinafter referred to as urethane prepolymer solution).

[0159] Subsequently, the urethane prepolymer solution was cooled, and 9.9 parts by mass (43.3 mol) of dimethylaminoethanol was added at 40°C to carry out a neutralization reaction. Next, 708.8 parts by mass of water was gradually added to the urethane prepolymer solution while stirring to emulsify and disperse the urethane prepolymer containing terminal isocyanate groups. To this emulsified dispersion, 1.6 parts by mass (12.4 mol) of hydrazine monohydrate and 0.6 parts by mass (2.3 mol) of diethylenetriamine were added, and after stirring at 40±5°C for 90 minutes, desolvent removal (demethyl ethyl ketone removal) was carried out under reduced pressure at 40°C to obtain urethane resin aqueous dispersion 1 with a urethane resin solids content (non-volatile content): 30.0% by mass. In this extension reaction, the ratio of the second polyamine to the first polyamine (mol%) was 15.7 (i.e., mol%:C2 / (C1+C2)=15.7), and the ratio of the second polyamine to the first polyamine (mass%) was 27.7 (i.e., mass%:C2 / (C1+C2)=27.7). The acid value of the obtained urethane resin was 21.5 mg KOH / g, and the glass transition temperature was in the range of -65 to -75°C. Furthermore, the volume-average particle diameter (d50) of the resin particles in the urethane resin aqueous dispersion 1 was in the range of 30 to 50 nm. The glass transition temperature of the urethane resin and the volume-average particle diameter (d50) of the resin particles in the urethane resin aqueous dispersion 1 were calculated by the method described below.

[0160] (2) Production of urethane resin aqueous dispersion 2 (combination of difunctional and tetrafunctional chain extenders) Urethane resin aqueous dispersion 2 was produced in the same manner as urethane resin aqueous dispersion 1, except that 0.6 parts by mass (1.7 mol) of triethylenetetramine was used instead of 0.6 parts by mass (2.3 mol) of diethylenetriamine in the production of urethane resin aqueous dispersion 1. The acid value of the urethane resin in the obtained urethane resin aqueous dispersion 2 was 21.5 mg KOH / g, and the glass transition temperature was in the range of -65 to -75°C. In addition, the volume-average particle size (d50) of the resin particles in urethane resin aqueous dispersion 2 was in the range of 30 to 50 nm.

[0161] (3) Production of urethane resin aqueous dispersion 3 (only the chain extension agent difunctionality) Urethane resin aqueous dispersion 3 was produced in the same manner as urethane resin aqueous dispersion 1, except that 0.4 parts by mass (3.4 mol) of hydrazine monohydrate (total amount of hydrazine monohydrate: 2.0 parts by mass (15.8 mol)) was used instead of 0.6 parts by mass (2.3 mol) of diethylenetriamine in the production of urethane resin aqueous dispersion 1. The acid value of the urethane resin in the obtained urethane resin aqueous dispersion 3 was 21.5 mg KOH / g, and the glass transition temperature was in the range of -65 to -75°C. In addition, the volume-average particle size (d50) of the resin particles in urethane resin aqueous dispersion 3 was in the range of 30 to 50 nm.

[0162] (4) Production of urethane resin aqueous dispersion 4 (only the chain extension agent 4-functionality) Aqueous urethane resin dispersion 4 was prepared in the same manner as for aqueous urethane resin dispersion 1, except that 3.0 parts by mass (11.5 mol) of triethylenetetramine was used instead of 1.6 parts by mass (12.4 mol) of hydrazine monohydrate and 0.6 parts by mass (2.3 mol) of diethylenetriamine. The acid value of the urethane resin in the obtained aqueous urethane resin dispersion 4 was 21.5 mg KOH / g, and the glass transition temperature was in the range of -65 to -75°C. In addition, the volume-average particle size (d50) of the resin particles in aqueous urethane resin dispersion 4 was in the range of 30 to 50 nm.

[0163] <Measurement of glass transition temperature> A polyurethane resin aqueous dispersion was coated onto a release film to achieve a dry film thickness of 400 μm. After being left at room temperature (20°C) and humidity (65% RH) for 48 hours, the film was heat-treated in a dryer at 120°C for 45 minutes to produce a polyurethane resin film. This polyurethane resin film was peeled from the release film and cut into strips of a size suitable for dynamic viscoelasticity measurement to obtain a polyurethane resin sample. Dynamic viscoelasticity measurements were performed on this polyurethane resin sample using a dynamic viscoelasticity analyzer (Hitachi High-Tech Corporation, product name "DMA7100") under the conditions of tensile mode, frequency of 10 Hz, temperature of -120 to 180°C, and heating rate of 5°C / min. Graphs were created showing the temperature dependence (temperature on the horizontal axis) of the storage modulus (E'), loss modulus (E"), and loss tangent (tanδ) obtained from these measurements. The temperature at which the peak in the temperature dependence of tanδ was observed was defined as the glass transition temperature (°C).

[0164] <Volume-average particle size (d50)> A urethane resin aqueous dispersion was diluted 60 times using deionized water, and the diluted solution was measured using a dynamic light scattering particle size distribution analyzer (Malvern's "Zetasizer Nano ZS") to determine the volume-average particle size d50 of the resin particles in the urethane resin aqueous dispersion.

[0165] Manufacturing of Pigment Dispersions As a pigment dispersant, 7 parts by mass of styrene-butyl acrylate-methacrylic acid copolymer (anionic polymer dispersant, weight-average molecular weight 16000, anionic group equivalent 3.5 meq / g) was mixed with 63 parts by mass of water, then heated and stirred, and sodium hydroxide equivalent to a neutralization degree of 50% by mass was added to prepare a neutralized pigment dispersant. 30 parts by mass of Pigment Red 122 was added to this mixture, pre-mixed, and then dispersed using a sand grinder packed with 0.5 mm zirconia beads at a volume percentage of 50% to obtain a magenta pigment dispersion with a pigment concentration of 30% by mass.

[0166] 《Pre-treatment solution manufacturing》 A pre-treatment solution for inkjet printing was obtained by mixing 20% ​​by mass of propylene glycol and 10% by mass of glycerin as moisturizing solvents, 0.1% by mass of Surfinol E1010 as a surfactant, 0.1% by mass of Proxel GXL(S) as a preservative, 2% by mass of a quaternary salt of an alkylamine epichlorohydrin-containing compound having an acidic or cationic group, and ion-exchanged water for the remainder.

[0167] Manufacturing of post-treatment solutions A post-treatment solution for inkjet printing was obtained by mixing 20% ​​by mass of propylene glycol and 10% by mass of glycerin as moisturizing solvents, 0.1% by mass of Surfinol E1010 as a surfactant, 0.1% by mass of Proxel GXL(S) as a preservative, 33.3% by mass of an aqueous urethane resin dispersion as an anionic resin dispersion, and ion-exchanged water for the remainder.

[0168] Manufacturing of inkjet inks Inkjet inks (inks 1-13 and C1-C4) for Examples 1-13 and Comparative Examples 1-4 were prepared using the formulations described in Tables 1 and 2 below. Specifically, in the amounts corresponding to the composition ratios shown in Tables 1 and 2, an organic solvent, an activator (Orphine E1010), and a preservative (Proxel GXL(S)) were added sequentially to deionized water, and the mixture was stirred at room temperature for at least 15 minutes to obtain a solvent mixture. Next, in a separate container, the solvent mixture was slowly added to a urethane resin aqueous dispersion in the amounts corresponding to the composition ratios shown in Tables 1 and 2, and the mixture was stirred for at least 20 minutes to obtain a urethane resin mixture. Next, in a separate container, the urethane resin mixture was slowly added to a colorant dispersion in the amounts corresponding to the composition ratios shown in Tables 1 and 2, and the mixture was stirred for at least 20 minutes before filtration to obtain inkjet inks (inks 1-13 and C1-C4).

[0169] Evaluation of inkjet inks <Fabric for evaluation> Using a simple printing test machine equipped with a KM1024i print head, the pre-treatment solution, inkjet ink, and post-treatment solution prepared as described above were sequentially printed onto cotton satin. The image was a 200mm x 200mm 100% solid image printed onto the fabric. The treated fabric was dried at 150°C for 3 minutes.

[0170] <Abrasion resistance> The obtained evaluation fabrics were subjected to a wet abrasion fastness test using a Type I testing machine in accordance with JIS L0849, and evaluated as follows.

[0171] Specifically, the area of ​​the evaluation fabric on which the image was formed was rubbed back and forth 10 times with a cotton cloth over a length of 100 mm with a load of approximately 9 N. The cotton cloth was moistened to approximately 100% using the method described in the JIS standard. After applying friction to the evaluation fabric with the cotton cloth, the cotton cloth was dried, and the contamination of the cotton cloth was evaluated using a grayscale for contamination. The contamination was judged based on the following evaluation criteria, and a rating of 3 or higher was considered acceptable. The contamination evaluation results are shown in Table 3.

[0172] Evaluation criteria; 5: Equivalent to 3-4 grade or higher Equivalent to 4:3 grade 3: Equivalent to 2-3 grade 2: Equivalent to 2nd class 1: Below the equivalent of Grade 2.

[0173] <Texture> Using the KES-FB2-A pure bending tester (manufactured by Kato Tech Co., Ltd.), the bending stress B-MEAN [gf × cm] was measured. 2 The width [ / cm] was measured, and the difference ΔB compared to the unprocessed fabric was calculated. The width of the fabric was set to 20cm. The texture was evaluated based on the following evaluation criteria, and a rating of 3 or higher was considered acceptable. The results of the texture evaluation are shown in Table 3.

[0174] Evaluation criteria; 5:ΔB≦0.06 4:ΔB≦0.09 3:ΔB≦0.12 2:ΔB≦0.15 1:ΔB>0.15.

[0175] <Droplet formation> Under ambient temperature and humidity conditions of 20°C and 40% RH, the droplet formation performance (stability of droplet formation) was evaluated by continuous ejection after introducing ink into the KM1024i printhead. The droplet formation performance was judged based on the following evaluation criteria, and a score of 3 or higher was considered acceptable. In the criteria below, "main droplet wobble" refers to the phenomenon where the main droplet does not remain in a fixed position but oscillates up and down. The evaluation results for droplet formation performance are shown in Table 3.

[0176] Evaluation criteria; 5: Droplet formation is stable. 4: Minor satellite formation occurs, but droplet formation is stable. 3: Minor satellite and main droplet wobble occurs, but droplet formation is at an acceptable level. 2: Satellite and main droplet wobble occurs, resulting in somewhat unstable droplet formation. 1: Satellite and main droplet wobble occurs, resulting in unstable droplet formation.

[0177] <Droplet recovery> In a standard environment with ambient temperature and humidity of 20°C and 40% RH, droplet recovery was evaluated by measuring the ejection recovery after introducing ink into the KM1024i print head and leaving it in an unhumidified state for 10 minutes. The evaluation of droplet recovery was judged based on the following evaluation criteria, and a rating of 3 or higher was considered acceptable. In the criteria below, "ejection operation" refers to the ink ejection operation, which was performed by ejecting 200 shots x 10 times. Specifically, "short ejection operation" refers to less than 200 shots x 10 times. The evaluation results of droplet recovery are shown in Table 3.

[0178] Evaluation criteria; 5: All nozzles recover with a short dispensing motion. 4. All nozzles recover during the dispensing operation. 3: All nozzles can be restored with simple maintenance. 2: Purge maintenance restores all nozzles 1: Some nozzles do not recover after purge maintenance.

[0179] <Ink storage stability> The viscosity of the ink after 14 days of storage at 50°C was measured using an E-type viscometer, and the difference in viscosity compared to the ink stored at room temperature was calculated to evaluate the ink's shelf life. Ink storage stability was judged based on the following evaluation criteria, and a rating of B or higher was considered acceptable. The evaluation results for ink storage stability are shown in Table 3.

[0180] Evaluation criteria; A ++ Ink viscosity variation is less than ±0.1 mPa·s. A + Ink viscosity variation of ±0.1 mPa·s or more and less than ±0.2 mPa·s A: Ink viscosity variation of ±0.2 mPa·s or more and less than ±0.3 mPa·s B: Ink viscosity variation of ±0.3 mPa·s or more and less than ±0.5 mPa·s C: Ink viscosity fluctuation of ±0.5 mPa·s or more.

[0181] [Table 1]

[0182] [Table 2]

[0183] [Table 3]

Claims

1. A urethane resin having (A) a structural unit derived from polyisocyanate, (B) a structural unit derived from polyol, and (C) a structural unit derived from polyamine, Organic solvents and Includes, The (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group. The (C) polyamine comprises a first polyamine having two groups selected from (C1) amino groups, imino groups, and hydrazide groups, and a second polyamine having three or four groups selected from (C2) amino groups, imino groups, and hydrazide groups. An inkjet ink in which the mass ratio of the organic solvent to the urethane resin (mass of organic solvent / mass of urethane resin) is 1.0 or greater.

2. The inkjet ink according to claim 1, wherein the content of the urethane resin is 5% by mass or more and 20% by mass or less with respect to the total mass of the ink.

3. The inkjet ink according to claim 1 or 2, wherein the organic solvent comprises a glycol-based solvent.

4. The inkjet ink according to claim 1 or 2, wherein the organic solvent comprises a glycol-based solvent having an octanol / water partition coefficient of -1.80 or less.

5. The inkjet ink according to claim 1 or 2, wherein the content of the organic solvent is 10% by mass or more and 50% by mass or less with respect to the total mass of the ink.

6. It also contains coloring agents, The inkjet ink according to claim 1 or 2, wherein the mass ratio of the coloring agent to the urethane resin (mass of coloring agent / mass of urethane resin) is 0.05 to 2.

0.

7. The inkjet ink according to claim 1 or 2, wherein the acid value of the urethane resin is 5 mg KOH / g or more and less than 30 mg KOH / g.

8. The inkjet ink according to claim 1 or 2, wherein the second polyamine comprises diethylenetriamine or triethylenetetramine.

9. The inkjet ink according to claim 1 or 2, wherein the polyether polyol comprises polytetramethylene glycol.

10. The inkjet ink according to claim 1 or 2, wherein the glass transition temperature of the urethane resin is 0°C or lower.

11. An inkjet ink according to claim 1 or 2, used for printing on woven fabrics.

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