Resin dispersion for inkjet inks

Abstract

The objective is to provide a resin dispersion before the colorant is mixed in that, while ensuring the storage stability of the resin dispersion before the colorant is mixed in, improves the droplet formation properties of the inkjet ink when actually applied to inkjet ink, and further improves the texture of the printed material. [Solution] The above problem is solved by a resin dispersion for inkjet ink comprising (A) a polyurethane resin having structural units 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.

Description

Technical Field

[0001] The present invention relates to a resin dispersion for inkjet ink.

Background Art

[0002] In recent years, the applications of inkjet printers have expanded. In addition to being used as printers for home and commercial printing, they are also applied to fabrics (textiles) and the like.

[0003] In a dyeing method for fabrics using an inkjet method, by discharging liquid droplets of ink from a nozzle and spraying them onto the fabric, an image can be transferred onto the fabric to obtain a dyed product.

[0004] As the ink for dyeing to obtain a dyed product, there are dye inks and pigment inks. Pigment inks are advantageous compared to dye inks in that they have high lightfastness and do not require post-treatment such as washing. In order to fix the pigment to the fiber, it is usually necessary to add a binder resin. For example, Patent Documents 1 and 2 disclose an inkjet ink composition containing polyurethane polyurea resin particles as a binder resin.

[0005] In addition, there are also specific problems in the dyeing method using the inkjet method. In the inkjet method, the ejected ink is ejected as a liquid column and then flies as droplets. However, due to some reason, if this liquid column is separated or the like in the middle, 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 dyed product, and the design quality (clearness) of the dyed product is impaired. For the purpose of improving such droplet formation (suppressing satellite droplets), Patent Document 2 has made considerations from the aspect of the printing system.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-84013 [Patent Document 2] Patent No. 6776775 [Patent Document 3] Japanese Patent Publication No. 2018-015974 [Overview of the project] [Problems that the invention aims to solve]

[0007] According to the technology described in Patent Document 1, the hardness derived from the binder resin results in a rough texture for the printed material, which is inferior to the texture of dye inks. Furthermore, exploring ways to improve droplet formation using an approach different from that described in Patent Document 2 would also contribute to improving the design (clarity) of the printed material.

[0008] Therefore, the objective is to provide a resin dispersion before the coloring agent is mixed in that, while ensuring the storage stability of the resin dispersion before the coloring agent is mixed in, improves the droplet formation properties of the inkjet ink when actually applied to inkjet ink, and further improves the texture of the printed material. [Means for solving the problem]

[0009] The above problems are solved by providing a resin dispersion for inkjet ink comprising (A) a polyurethane resin having structural units derived from polyisocyanate, (B) structural units derived from polyol, and (C) structural units 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 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. [Effects of the Invention]

[0010] The resin dispersion, before the colorant is mixed in, has the necessary characteristics to ensure storage stability, and when actually applied to inkjet ink, it can improve the droplet formation properties of the inkjet ink and further improve the texture of the printed material. [Modes for carrying out the invention]

[0011] In this specification, "X~Y" is used to mean "X or greater and Y or less," including the numerical values ​​(X and Y) before and after it as the lower and upper limits, respectively. When multiple "X~Y" values ​​are listed, for example, "X1~Y1, or X2~Y2," the disclosure of each numerical value as the upper limit, the disclosure of each numerical value as the lower limit, and all combinations of these upper and lower limits are disclosed (i.e., they provide a legal basis for corrections). Specifically, corrections to X1 or greater, corrections to Y2 or less, corrections to X1 or less, corrections to Y2 or greater, corrections to X1~X2, corrections to X1~Y2, etc., must all be considered legal. Furthermore, unless otherwise specified, operations and measurements of physical properties, etc., shall be performed under conditions of room temperature (20~25°C) / relative humidity 40~70%RH.

[0012] <Resin dispersion> The resin dispersion for inkjet ink of the present invention comprises a polyurethane 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 water, 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 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. By having such a configuration, it is possible to provide a resin dispersion before the colorant is mixed that ensures the storage stability of the resin dispersion before the colorant is mixed, improves the droplet formation of the inkjet ink when it is actually applied to inkjet ink, and further improves the texture of the printed material. In this specification, inkjet ink may also be simply referred to as "ink".

[0013] (Polyurethane resin) The polyurethane resin contained in the resin dispersion for inkjet ink of the present invention (also referred to simply as "polyurethane resin" in this specification) can function as a binder resin for fixing colorants (especially pigments) that may be contained in inkjet ink to fibers.

[0014] (A) Polyisocyanate The polyurethane resin of the present invention 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.

[0015] (B) Polyol The polyurethane resin of the present invention has a structural unit derived from (B) polyol, and the (B) polyol includes (B1) polyether polyol and (B2) a diol compound having a carboxy group and / or a carboxylate group.

[0016] (B1) Polyether polyol In one embodiment of the present invention, examples of the (B1) polyether polyol include polyalkylene ether glycols. The number of carbon atoms of 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 the (B1) polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or a polyol composed of block or random copolymerization thereof.

[0017] In one embodiment of the present invention, the number average molecular weight of the (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 by the following formula using the hydroxyl value of the (B1) polyether polyol. The hydroxyl value was determined according to JIS K 1557-1:2007 Method A. The number average molecular weights of the polyester polyol and polycarbonate polyol described below are also calculated by the same method.

[0018]

Number

[0019] In one embodiment of the present invention, the (B) polyol may include at least one selected from polyester polyol, polycarbonate polyol, and low molecular weight polyhydric alcohol within a range that does not impair the performance of the present invention. Here, the number average molecular weight (molecular weight) of the low molecular weight polyhydric alcohol can be less than 500 or 400 or less.

[0020] In one embodiment of the present invention, examples of the polycarbonate polyol include 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 an ethylene oxide or propylene oxide adduct of bisphenol A, trimethylolpropane, glycerin, pentaerythritol, etc.; and those obtained by a dealcoholization reaction, a dephenolization reaction, etc. with one or more carbonates selected from diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, etc. The above polycarbonate polyol can be used alone or in combination of two or more kinds.

[0021] In one embodiment of the present invention, examples of the polyester polyol include those obtained by a polycondensation reaction of 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 above polycarbonate polyol. The above polyester polyol can be used alone or in combination of two or more kinds.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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 polyurethane resin and the texture of the printed material.

[0026] 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 polyurethane resin and the texture of the printed material.

[0027] 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.

[0028] (B2) Diol compounds having a carboxyl group and / or a carboxylate group In one embodiment of the present invention, the polyurethane resin of the present invention has constituent units derived from a diol compound having a carboxyl group and / or a carboxylate group (B2). Here, polyurethane is generally hydrophobic (lipophilic) and not aqueous (water-dispersible). In one embodiment of the present invention, the polyurethane resin has a carboxylate group. With such an embodiment, the polyurethane resin contained in the resin dispersion of the present invention 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 polyurethane 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 polyurethane resin is 40 to 100 mol%, or 50 to 80 mol%. In order for the polyurethane 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 polyurethane resin is above a certain lower limit, methods include using a diol compound having carboxylate groups as (B2) as a raw material, a method 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 a method in which a diol compound having carboxylate groups as (B2) is used as a raw material to obtain a prepolymer as described later and then neutralize. In the present invention, the method of neutralizing after obtaining the prepolymer is preferred. Therefore, in one embodiment of the present invention, the polyurethane 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. Details regarding neutralization will be described later.

[0033] In one embodiment of the present invention, (B) does not contain an aliphatic cyclic structure.

[0034] (C) Polyamine 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.

[0035] The polyurethane resin of the present invention has a constituent unit derived from (C) polyamine, wherein 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.

[0036] 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.

[0037] 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, 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 oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacate acid dihydrazide, maleic acid dihydrazide, fumarate dihydrazide, itaconic acid dihydrazide, 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.

[0038] In one embodiment of the present invention, (C2) is, for example, the general formula: H2N((CH2) n NH) m A substance represented by H (where n is 2 to 6 and m is 2 or 3) is preferred, and specific examples include diethylenetriamine, triethylenetetramine, and iminobispropylamine. Among these, diethylenetriamine and triethylenetetramine can be used particularly favorably.

[0039] As described above, the polyurethane resin of the present invention has a constituent unit derived from a first polyamine having two (C1) amino groups, imino groups, and hydrazide groups, and a constituent unit derived from a second polyamine having three or four (C2) amino groups, imino groups, and hydrazide groups. By having such a configuration, the resulting polyurethane resin dispersion has good droplet-forming properties.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] According to one embodiment of the present invention, the total number of moles of functional groups (amino group, imino group, and hydrazide group) of (C) relative to the total number of moles of isocyanate groups of (A) is preferably 10 to 40 mol%, more preferably 15 to 30 mol%.

[0044] 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 polyurethane 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.

[0045] In one embodiment of the present invention, the acid value of the polyurethane 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 polyurethane resin. - The acid value of polyurethane resin can be calculated from its content. If the acid value of polyurethane resin is less than 5 mg KOH / g, the storage stability of the polyurethane resin 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 polyurethane resin can be calculated as follows: A sample of polyurethane resin dissolved in N,N-dimethylformamide is prepared as the measurement sample. Then, the acid value of the polyurethane resin can be measured by potentiometric titration with potassium hydroxide ethanol titrant using a potentiometric automatic titrator (product name "AT510", manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

[0046] In one embodiment of the present invention, the acid value of the polyurethane resin is 7-25 mgKOH / g, 10-24 mgKOH / g, 15-23 mgKOH / g, or 17-22 mgKOH / g. This range improves storage stability, droplet formation, and the texture (flexibility) of the printed material.

[0047] (Method for producing a resin dispersion containing polyurethane resin and water) The resin dispersion liquid containing polyurethane resin and water according to the present invention can be manufactured, for example, as follows.

[0048] (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 polyurethane 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 conventionally known one-stage so-called one-shot method, 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.

[0049] (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 polyurethane resin, the carboxyl group of the prepolymer can be neutralized using any neutralizing agent so that the polyurethane 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 used for such neutralization include amines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine, N-methyl-diethanolamine, N,N-dimethylmonoethanolamine (2-(dimethylamino)ethanol), N,N-diethylmonoethanolamine, and triethanolamine, as well as potassium hydroxide, sodium hydroxide, and ammonia. 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 polyurethane 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 polyurethane resin is 40 to 100 mol%, or 50 to 80 mol%.

[0050] (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.

[0051] (Chain elongation) Next, chain extension and crosslinking reactions are 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).

[0052] (Solvent removal) If an organic solvent is used as described above, it is preferable to remove it. The desired removal conditions are under reduced pressure and at 30-80°C.

[0053] The resin dispersion of the present invention contains water, and according to one embodiment of the present invention, the mass of polyurethane resin (resin solids) relative to the total mass of the resin dispersion is in the range of 20 to 60% by mass. The concentration of resin solids in the resin dispersion can also be adjusted by adding or distilling off water.

[0054] According to this manufacturing method using a prepolymer, a polyurethane 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).

[0055] The glass transition temperature (Tg) of the polyurethane resin is not particularly limited, but a low Tg is preferable from the viewpoint of preventing the texture from hardening even after image formation. The Tg of the polyurethane resin aqueous dispersion is 0°C or lower, and preferably between -80°C and 0°C.

[0056] Furthermore, Tg can be determined by 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 the temperature dependence of the dynamic viscoelasticity measurement of a dried film (film-like sample) of a polyurethane resin dispersion, is observed.

[0057] The volume-average particle size (d50) of the polyurethane resin is not particularly limited, but from the viewpoint of reducing the likelihood of nozzle clogging of the inkjet head, it is preferably 300 nm or less, and more preferably 130 nm or less. The lower limit of d50 can be, for example, 10 nm. The volume-average particle size (d50) of the polyurethane resin 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.

[0058] <Inkjet ink> In one embodiment of the present invention, an inkjet ink is provided by comprising a resin dispersion of the present invention and a coloring agent.

[0059] (Polyurethane resin) The inkjet ink (ink) contains the polyurethane resin of the present invention. The total mass of the polyurethane resin relative to the total mass of the inkjet ink can be 5 to 20% by mass, preferably 5 to 10% by mass, in terms of solid content.

[0060] (Water-soluble organic solvent) Inkjet inks may contain water-soluble organic solvents. The water-soluble organic solvent is not particularly limited as long as it is miscible with water, but examples include polyhydric alcohols (e.g., dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol; trihydric or higher alcohols such as glycerin, trimethylolpropane, and hexanetriol); and polyhydric alcohol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether) This includes propylene glycol monomethyl ether, propylene glycol monoethyl ether; monohydric alcohols (e.g., methanol, ethanol, propanol, pentanol, hexanol, cyclohexanol, benzyl alcohol); amines (e.g., ethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine); amides (e.g., formamide, N,N-dimethylformamide, N,N-dimethylacetamide); heterocyclic compounds (e.g., 2-pyrrolidone, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidine); sulfoxides (e.g., dimethyl sulfoxide); and sulfones (e.g., sulfolane).

[0061] In particular, from the viewpoint of making it easier to moderately increase the viscosity of the ink, the water-soluble organic solvent preferably contains polyhydric alcohols. From the viewpoint of making it easier to increase the viscosity of the ink, the polyhydric alcohols preferably contain trihydric or higher alcohols, and more preferably contain glycerin. Specifically, the mass of the polyhydric alcohols is preferably 1 to 50% by mass, or 2 to 45% by mass, relative to the total mass of the ink.

[0062] Furthermore, it is preferable that the ink also contains heterocyclic compounds such as 2-pyrrolidone. Specifically, it is preferable that the mass of the heterocyclic compounds is 1 to 20% by mass, 2 to 15% by mass, or 3 to 8% by mass relative to the total mass of the ink.

[0063] (Coloring agent) Pigments are preferably used as colorants, and while the pigments are not particularly limited, they may be, for example, organic or inorganic pigments listed in the Color Index with the following numbers. The colorants may also be solid colorants.

[0064] Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257; Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88; and Pigment Orange 13, 16, 20, 36.

[0065] 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.

[0066] Examples of green pigments include Pigment Green 7, 26, 36, and 50. Examples of yellow pigments include Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, and 193.

[0067] Examples of black pigments include Pigment Black 7, 28, and 26.

[0068] 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 (manufactured by DIC);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, PigmentRed 122, ColortexBlue516, 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).

[0069] Dyes can also be used as colorants. The dyes are preferably solid dyes, such as disperse dyes.

[0070] 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.

[0071] Among these, pigments are preferred as colorants because they have good dispersibility with the components of the ink and excellent weather resistance.

[0072] The amount of colorant is not particularly limited, but from the viewpoint of easily adjusting the viscosity of the ink within the above range and enabling the formation of high-density images, it is preferably 1 to 15% by mass relative to the total mass of the ink. When the mass percentage of colorant is 1% or more, it is possible to moderately increase the viscosity of the ink and easily form high-density images. When the mass percentage of colorant is 15% or less, the viscosity of the ink does not become too high, so nozzle clogging is less likely to occur. From the same viewpoint, the amount of colorant is more preferably 1.5 to 15% by mass relative to the total mass of the ink, and even more preferably 2 to 12% by mass.

[0073] (Other ingredients) Inkjet inks may contain other components as needed. Examples of other components include solvents, surfactants, preservatives, fungicides, rust inhibitors, and pH adjusters.

[0074] surfactants Examples of surfactants include anionic, cationic, amphoteric, and nonionic types. Examples of anionic surfactants include fatty acid salts, alkyl sulfates, alkyl sulfate esters, alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate salts, alkylnaphthalene sulfonic acid formalin condensates, and polyoxyethylene alkyl sulfate salts. Examples of cationic surfactants include amine salts, tetraalkyl quaternary ammonium salts, trialkyl quaternary ammonium salts, alkylpyridinium salts, and alkylquinolinium salts. Examples of nonionic surfactants include polyethylene glycol alkyl ethers, polyethylene glycol alkylphenyl ethers, polyethylene glycol fatty acid esters, polyethylene glycol sorbitan fatty acid esters, polyethylene glycol alkylamines, ethylene oxide adducts of polypropylene glycol, acetylene glycol, and ethylene oxide adducts of acetylene glycol. Examples of surfactants include polyethylene glycol-modified silicones.

[0075] The surfactant content is more preferably 0.01 to 5% by mass, and even more preferably 0.05 to 1% by mass, relative to the total mass of the ink.

[0076] Preservatives, fungicides 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).

[0077] pH adjuster Examples of pH adjusters include urea and sodium hydroxide.

[0078] The present invention encompasses the following aspects and embodiments.

[0079] [1] A resin dispersion for inkjet ink comprising (A) a polyurethane resin having structural units 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 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.

[0080] [2] The resin dispersion according to [1], wherein the polyurethane resin comprises 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).

[0081] [3] The resin dispersion according to [1] or [2] above, wherein the polyurethane resin contains a carboxylate group.

[0082] [4] The resin 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 polyurethane resin is 40 mol% or more.

[0083] [5] A resin 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%.

[0084] [6] The resin dispersion according to any one of [1] to [5] above, wherein the acid value of the polyurethane resin is 5 mg KOH / g or more and less than 30 mg KOH / g.

[0085] [7] The resin dispersion according to any one of [1] to [6] above, wherein the total number of moles of hydroxyl groups contained in (B) relative to the total number of moles of isocyanate groups contained in (A) is 70 to 90 mol%.

[0086] [8] The resin dispersion according to any one of [1] to [7] above, wherein (B) does not contain an aliphatic cyclic structure.

[0087] [9] The resin dispersion according to any one of 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).

[0088]

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

[0089]

[11] A resin 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 polyurethane 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). [Examples]

[0090] The following describes specific embodiments of the present invention, but the present invention is not limited to these.

[0091] <Synthesis of polyurethane resin> (Example 1) In a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet, 205.6 parts by mass of (B1) polytetramethylene glycol (number average molecular weight 2,000) and 14.9 parts by mass of (B2) dimethylolpropionic acid were weighed out as (B), and 123.4 parts by mass of methyl ethyl ketone as a solvent were uniformly mixed. Then, 67.3 parts by mass of dicyclohexylmethane diisocyanate was added as (A), and the mixture was reacted at 85±5°C 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. The mixture was then cooled and neutralized by adding 9.9 parts by mass of dimethylaminoethanol at 40°C. Next, 708.8 parts by mass of water were gradually added while stirring to emulsify and disperse the urethane prepolymer containing terminal isocyanate groups. To this emulsified dispersion, 1.6 parts by mass of (C1) hydrazine monohydrate and 0.6 parts by mass of (C2) diethylenetriamine were added as (C), and the mixture was stirred at 40±5°C for 90 minutes. Then, a solvent removal treatment (demethyl ethyl ketone treatment) was performed under reduced pressure at 40°C to obtain a polyurethane resin dispersion with a polyurethane resin solid content of 30.0% by mass.

[0092] (Examples 2-11, Comparative Examples 1-6) A polyurethane resin dispersion was obtained in the same manner as in Example 1, except that the types and amounts of (B), (A), and (C) were changed as shown in Table 1. A blank space in the table indicates that the corresponding component was not added.

[0093] <Storage stability> 200 g of the synthesized polyurethane resin dispersion was sealed in a transparent 200 mL bottle and left to stand in a 60°C oven for one month. The presence or absence of resin sedimentation was visually evaluated. A rating of B below is considered practically acceptable.

[0094] A: No resin sedimentation in the dispersion. B: Water is visible on the surface of the dispersion, but there is no sedimentation of resin. C: Resin sedimentation was observed in the dispersion.

[0095] <Measurement of glass transition temperature> A polyurethane resin 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 polyurethane resin samples. Dynamic viscoelasticity measurements were performed on these polyurethane resin samples 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).

[0096] <Volume-average particle diameter> A polyurethane resin dispersion was diluted 60 times using deionized water, and the volume-average particle size d50 of the polyurethane resin was determined by measuring the diluted solution using a dynamic light scattering particle size distribution analyzer (Malvern's "Zetasizer Nano ZS").

[0097] <Texture of printed materials> (Ink preparation) A mixture of 3% by mass of the solid colorant Pigment Black 7, 33.3% by mass of a polyurethane resin dispersion with a solid content of 30% by mass, 4% by mass of 2-pyrrolidone, 5% by mass of glycerin, 0.1% by mass of the preservative Proxel GXL (1,2-benzisothiazolin-3-one), and 0.1% by mass of the surfactant KF-351A (manufactured by Shin-Etsu Chemical Co., Ltd., polyethylene glycol-modified silicone) was added and diluted with water to a total of 100% by mass to form an ink. This ink contains 10% by mass of polyurethane resin on a solid content basis.

[0098] (Printing test method) The prepared ink was ejected from the nozzle of the inkjet head of a simple printing test machine to form a 100% solid image on a fabric (cotton satin 60). Specifically, a 200mm x 200mm solid image was formed using a main scan of 540 dpi and a sub-scan of 720 dpi. dpi represents the number of ink droplets (dots) per 2.54 cm. The ink adhesion amount was 15 g / m². 2 The discharge rate was adjusted to achieve the desired result. The image-forming material was then obtained by drying it in a belt-type dryer at 150°C for 3 minutes.

[0099] Criteria for determining texture The resulting image formations were evaluated using the bending stress B value calculated with a Kato Tech pure bending tester (KES-FB2-A) as an indicator, according to the following criteria. A B rating below is considered practically acceptable.

[0100] A: The B value is less than 1.5 times that of the image before formation, and the change in texture is not discernible in sensory evaluation. B: The B value is 1.5 times or more but less than 3 times compared to before image formation, indicating a slight change in texture that can be detected by sensory evaluation. C: The B value is more than 3 times higher than before image formation, indicating a problem with the texture in sensory evaluation.

[0101] <Droplet Formation Test Method> Using a droplet observation system equipped with a strobe, camera, and Konica Minolta KM1024 inkjet head, the ink flight state at a position 1 mm from the nozzle surface was observed with a high-speed camera while changing the droplet velocity by adjusting the ejection drive voltage in a 25°C, 50% RH environment, and the satellite generation rate was measured.

[0102] • Evaluation criteria Based on the measurement results from the droplet observation device, it was determined that an ink characteristic suitable for a printing device is one in which the satellite generation speed is 6.0 m / s or higher. Furthermore, the following A rating is practically preferable.

[0103] A: Satellite generation speed is 6.0 m / s or higher C: Satellite generation speed is less than 6.0 m / s.

[0104] Table 1

[0105] Table 2

Claims

1. A polyurethane 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 water, The (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxylate group. A resin dispersion for inkjet ink, wherein 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.

2. The aforementioned polyurethane resin 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), A constituent unit derived from (C) above, A resin dispersion according to claim 1, having the following characteristics.

3. The resin dispersion according to claim 1, wherein the polyurethane resin contains a carboxylate group.

4. The resin dispersion according to claim 1, wherein the total number of moles of carboxylate groups relative to the total number of moles of carboxylate groups and carboxyl groups in the polyurethane resin is 40 mol% or more.

5. The resin dispersion according to claim 1, 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 resin dispersion according to claim 1, wherein the acid value of the polyurethane resin is 5 mg KOH / g or more and less than 30 mg KOH / g.

7. The resin dispersion according to claim 1, wherein the total number of moles of hydroxyl groups contained in (B) relative to the total number of moles of isocyanate groups contained in (A) is 70 to 90 mol%.

8. The resin dispersion according to claim 1, wherein (B) does not contain an aliphatic cyclic structure.

9. The resin dispersion according to claim 1, wherein the total number of moles of (B1) and (B2) relative to the total number of moles of (B) is 50 mol% or more.

10. The resin dispersion according to claim 1, 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. The resin dispersion according to claim 1, wherein 65 mol% or more of the total number of moles of all constituent units in the polyurethane 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).

Images