Resin dispersion for inkjet ink

Abstract

The present invention addresses the problem of providing a resin dispersion liquid before mixing a colorant, which can ensure the storage stability of the resin dispersion liquid before mixing the colorant as a characteristic that should be provided, and which can improve the droplet formability of an inkjet ink and further improve the texture of a printed material when actually applied to the inkjet ink. The problem is solved by a resin dispersion for an inkjet ink comprising: a polyurethane resin having a structural unit derived from (A) a polyisocyanate, a structural unit derived from (B) a polyol, and a structural unit derived from (C) a polyamine; and water. The polyol (B) includes: (B1) a polyether polyol; and (B2) a diol compound having a carboxyl group and / or a carboxylic acid ester group. The polyamine (C) includes: (C1) a first polyamine having two groups selected from the group consisting of an amino group, an imino group, and a hydrazide group; and (C2) a second polyamine having 3 or 4 groups selected from the group consisting of an amino group, an imino group, and a hydrazide group.

Description

Technical Field

[0001] This invention relates to resin dispersions for inkjet inks. Background Technology

[0002] In recent years, the uses of inkjet printers have expanded, from being used as printing presses for home and commercial printing to being used for textiles.

[0003] In inkjet printing methods, images are transferred onto fabric by spraying droplets of ink from a nozzle onto the fabric, thus obtaining printed materials.

[0004] As inks used for printing and dyeing to obtain printed and dyed products, there are dye inks and pigment inks. Pigment inks are more advantageous than dye inks in terms of high lightfastness and the fact that they do not require post-treatment such as washing. For pigment inks, in order to fix the pigment to the fiber, a binder resin is usually added. For example, in Patent Documents 1 and 2, inkjet ink compositions containing polyurethane polyurea resin particles are disclosed as binder resins.

[0005] Furthermore, inkjet printing methods also present unique challenges. In inkjet printing, the ejected ink is ejected as a jet and then travels as droplets. However, due to various reasons, this jet may separate midway, resulting in the formation of main droplets and satellite droplets. If this occurs, the image is transferred to unintended areas of the printed material, impairing the design (clarity) of the printed material. To improve droplet formation (suppression of satellite droplets), research was conducted on the printing system in Patent Document 2.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2020-84013

[0009] Patent Document 2: Japanese Patent No. 6776775

[0010] Patent Document 3: Japanese Patent Application Publication No. 2018-015974 Summary of the Invention

[0011] According to the technology in Patent Document 1, due to the hardness of the binder resin, the printed fabric has a rough feel (roughness) and the feel of the fibers is worse than that of dye ink. However, the technology in Patent Document 2, which studies the improvement of droplet formation using a different method, also helps to improve the designability (transparency) of the printed fabric.

[0012] Therefore, the research objective is to provide a resin dispersion before mixing colorants, which should possess the following characteristics: ensuring the preservation stability of the resin dispersion before mixing colorants, and improving the droplet formation properties of inkjet inks when actually applied to inkjet inks, thereby improving the hand feel of printed and dyed products.

[0013] The above-mentioned problems are solved by providing a resin dispersion for inkjet ink, wherein the resin dispersion for inkjet ink comprises: a polyurethane resin having structural units from (A) a polyisocyanate, structural units from (B) a polyol, and structural units from (C) a polyamine; and water, wherein the (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having carboxyl and / or carboxylic acid ester groups, and the (C) polyamine comprises (C1) a first polyamine having two groups selected from amino, imino, and hydrazide groups; and (C2) a second polyamine having three or four groups selected from amino, imino, and hydrazide groups. Detailed Implementation

[0014] In this specification, "X~Y" is used to mean the lower and upper limits of the values ​​(X and Y) included before and after it, indicating "above X and below Y". When multiple "X~Y" are specified, for example, as "X1~Y1" or "X2~Y2", all disclosures are made with each value as an upper limit, each value as a lower limit, and all combinations of these upper and lower limits (i.e., they become the legal basis for modification). Specifically, modifications of X1 or above, modifications of Y2 or below, modifications of X1 or below, modifications of Y2 or above, modifications of X1~X2, modifications of X1~Y2, etc., are all considered legal. Furthermore, unless otherwise specified, the operation and physical properties are measured at room temperature (20~25°C) and relative humidity 40~70%RH.

[0015] <Resin Dispersion>

[0016] The resin dispersion for inkjet ink of the present invention comprises: a polyurethane resin having structural units from (A) a polyisocyanate, structural units from (B) a polyol, and structural units from (C) a polyamine; and water, wherein the (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having carboxyl and / or carboxylic acid ester groups, and the (C) polyamine comprises (C1) a first polyamine having two groups selected from amino, imino, and hydrazide groups; and (C2) a second polyamine having three or four groups selected from amino, imino, and hydrazide groups. With this configuration, a resin dispersion prior to mixing with a colorant can be provided, which, as a desired property, ensures the storage stability of the resin dispersion prior to mixing with the colorant and, when actually applied to inkjet ink, improves the droplet formation properties of the inkjet ink, thereby improving the hand feel of the printed material. In this specification, inkjet ink is sometimes simply referred to as "ink".

[0017] (Polyurethane resin)

[0018] The polyurethane resin (also referred to as "polyurethane resin" in this specification) contained in the resin dispersion of the inkjet ink of the present invention can function as a binder resin for fixing colorants (especially pigments) contained in inkjet ink to fibers.

[0019] (A) Polyisocyanates

[0020] The polyurethane resin of the present invention has a structural unit derived from (A) a polyisocyanate. There are no particular limitations on the polyisocyanate; for example, aromatic polyisocyanate compounds, aliphatic polyisocyanate compounds, and alicyclic polyisocyanate compounds can be listed. Examples of aromatic polyisocyanate compounds include toluene diisocyanate (TDI), phenylenediamine diisocyanate (XDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), and tetramethylphenylenediamine diisocyanate. Examples of aliphatic polyisocyanate compounds include alkylene diisocyanates such as hexamethylene diisocyanate (HDI). Here, the number of carbon atoms 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 this dicycloalkyl alkane diisocyanate, the cycloalkyl group preferably has 5 to 8 carbon atoms, and the alkane preferably has 1 to 4 or 1 to 3 carbon atoms. Specific examples of alicyclic polyisocyanate compounds include 1,3-bis(isocyanate-methyl)cyclohexane, isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H12MDI), and norbornene diisocyanate. Therefore, according to one embodiment of the present invention, the polyisocyanate is one or more diisocyanate compounds selected from aromatic diisocyanate compounds, aliphatic diisocyanate compounds, and alicyclic diisocyanate compounds. These polyisocyanate compounds can be used alone or in combination of two or more.

[0021] (B) Polyols

[0022] The polyurethane resin of the present invention has structural units derived from (B) polyols, which include (B1) polyether polyols and (B2) diol compounds having carboxyl and / or carboxylic acid ester groups.

[0023] (B1) Polyether polyol

[0024] In one embodiment of the present invention, polyalkylene ether diols can be cited as (B1) polyether polyols. The alkylene groups in the polyalkylene ether diol preferably have 2 to 6, 2 to 5, 2 to 4, or 3 or 4 carbon atoms. The alkylene groups can be linear or branched. Specific examples of (B1) polyether polyols include polyols composed of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or polyols formed by block or random copolymerization of these.

[0025] In one embodiment of the present invention, the number-average molecular weight of the (B1) polyether polyol may be 500–5000, 1000–4000, or 1500–3000. The number-average molecular weight is calculated using the hydroxyl value of the (B1) polyether polyol by the following formula. The hydroxyl value is determined according to JIS K 1557-1:2007A. Note that the number-average molecular weight of the polyester polyol and polycarbonate polyol described later is also calculated using the same method.

[0026]

Number 1

[0027] Number average molecular weight = 56110 × number of functional groups in polyol / hydroxyl value

[0028] In one embodiment of the present invention, and with regard to (B) the polyol, without impairing the performance of the present invention, it may include at least one selected from polyester polyols, polycarbonate polyols, and low molecular weight polyols. The number average molecular weight (molecular weight) of the low molecular weight polyol may be less than 500 or less than 400.

[0029] In one embodiment of the present invention, examples of polycarbonate polyols include those obtained by means of 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, neopentanediol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, or ethylene oxide or propylene oxide adducts of bisphenol A, trimethylolpropane, glycerol, pentaerythritol, etc.; and products obtained by means of dealcoholization reactions, dealcophenolization reactions, etc., of one or more carbonates selected from diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, etc. The aforementioned polycarbonate polyols can be used alone or in combination of two or more.

[0030] In one embodiment of the present invention, the polyester polyol may be, for example, a product obtained by polycondensation reaction of one or more diacids 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 aforementioned polyester polyol can be used alone or in combination of two or more.

[0031] In one embodiment of the present invention, the number average molecular weights of the polycarbonate polyol and the polyester polyol can each be independently 500-5000, 1000-4000, or 1500-3000.

[0032] In one embodiment of the present invention, examples of low molecular weight polyols include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, sorbitol, etc.

[0033] In one embodiment of the invention, the mass of (B1) polyether polyol relative to the total mass of (B1) polyether polyol contained in (B) and the total mass of 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). By having such a lower limit, droplet formation is improved.

[0034] In one embodiment of the invention, the total number of low-molecular-weight polyols relative to the total number of moles of (B) polyol 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 (with a lower limit of 0 mol%). By having such an upper limit, the softness of the obtained polyurethane resin and the hand feel of the printed material are improved.

[0035] In one embodiment of the invention, the total mass of the low molecular weight polyol relative to the total mass of (B) polyol 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). By having such an upper limit, the softness of the obtained polyurethane resin and the feel of the printed material are improved.

[0036] It should be noted that the (B1) polyether polyol contained in (B) and the polycarbonate polyol and polyester polyol contained in (B) generally do not have either a carboxyl group or a carboxylic acid ester group.

[0037] (B2) Diol compounds having carboxyl and / or carboxylic acid ester groups

[0038] In one embodiment of the invention, the polyurethane resin of the invention has structural units derived from (B2) of a diol compound having a carboxyl group and / or a carboxyl ester group. Here, the polyurethane is generally hydrophobic (oleophilic), not aqueous (water-dispersible). In one embodiment of the invention, the polyurethane resin has a carboxyl ester group. By such an embodiment, the polyurethane resin contained in the resin dispersion of the invention can have aqueous (dispersible in water) properties. In one embodiment of the invention, (B2) contains one, two, or three groups selected from carboxyl and carboxyl ester groups per molecule.

[0039] In one embodiment of the invention, (B2) has one alkyl group in one molecule. The alkyl group preferably has 1 to 6 carbon atoms, or 1 or 2. The alkyl group is preferably linear. In one embodiment of the invention, examples of (B2) include 2,2-dimethylolpropionic acid (DMPA), 2,2-dimethylolbutyric acid (DMBA), or their neutralizations. Furthermore, such diol compounds having carboxyl and / or carboxylic acid ester groups can be used alone, or in combination of two or more.

[0040] In one embodiment of the present invention, the total number of moles of (B1) and (B2) above relative to the total number of moles of (B) polyol 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 (upper limit is 100 mol%).

[0041] 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. 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% and less than 70 mol%, more preferably 47 to 65 mol%, and particularly preferably 49 to 60 mol%.

[0042] In one embodiment of the present invention, the total number of moles of carboxylic acid ester groups relative to the total number of moles of carboxylic acid ester groups and carboxyl groups in the polyurethane resin (the so-called neutralization rate) is 40 mol% or more. In another embodiment of the present invention, the total number of moles of carboxylic acid ester groups relative to the total number of moles of carboxylic acid ester groups and carboxyl groups in the polyurethane resin is 40 to 100 mol%, or 50 to 80 mol%. To enable the polyurethane resin to have carboxylic acid ester groups, and further, to ensure that the total number of moles of carboxylic acid ester groups relative to the total number of moles of carboxylic acid ester groups and carboxyl groups in the polyurethane resin is at least a certain lower limit, examples include: a method (B2) using a diol compound having carboxylic acid ester groups as a raw material; a method (B2) using a diol compound having carboxyl groups as a raw material, obtaining a diol compound having at least a portion of carboxyl groups by neutralizing at least a portion of the carboxyl groups of a diol compound having carboxyl groups as a raw material, and then neutralizing it after obtaining the prepolymer described later, etc. It should be noted that, in the present invention, the method of neutralizing after obtaining the prepolymer is preferred. Therefore, in one embodiment of the invention, the polyurethane resin has structural units derived from a prepolymer having structural units from (A) and structural units from (B) and having isocyanate groups at the ends. Neutralization will be described in detail later.

[0043] In one embodiment of the present invention, (B) does not contain an aliphatic ring structure.

[0044] (C) Polyamines

[0045] In one embodiment of the invention, (C) polyamine can be used as a chain extender for the prepolymer described later. It should be noted that, as a chain extender, as a trivalent chain extender (the number of functional groups having active hydrogen), compounds having hydroxyl groups (e.g., trimethylolpropane, aminoethylethanolamine, etc.) are known. If used, chain extension becomes insufficient, and there is a tendency for droplet formation to deteriorate. While not limiting its use in combination with (C), it is preferable not to use it.

[0046] The polyurethane resin of the present invention has a structural unit derived from (C) polyamine, which includes (C1) a first polyamine having two groups selected from amino, imino and hydrazide groups; and (C2) a second polyamine having three or four groups selected from amino, imino and hydrazide groups.

[0047] In one embodiment of the present invention, (C1) may be at least one of an alkylene diamine, 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 alkylene diamine may have 1 to 12 carbon atoms. In one embodiment of the present invention, the diamine having a cycloalkane structure may be a diaminoalkylcycloalkane, wherein the alkyl group in the diaminoalkylcycloalkane has 1 to 4, 1 to 3, or 1 or 2 carbon atoms, and the cycloalkane in the diaminoalkylcycloalkane has 5 to 8, or 5 to 7 carbon atoms.

[0048] In one embodiment of the present invention, as (C1), for example, ethylenediamine, 1,3-propanediamine, propylenediamine, 1,3-butanediamine, 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, diaminodicyclohexylmethane, hydrazine, piperazine, 2-methylpiperazine, isophorone diamine, norbornane diamine (bis(aminomethyl)norbornane), 1,3-diaminocyclohexane, 1,3-diaminomethylcyclohexane, 1,4-diaminomethyl Diamines such as cyclohexane, diaminodiphenylmethane, toluenediamine, and phenylenediamine; amide amines derived from primary amines and monocarboxylic acids; water-soluble amine derivatives such as monoketene imines of primary amines; hydrazine derivatives such as oxalate dihydrazide, malonate dihydrazide, succinate dihydrazide, glutarate dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleate dihydrazide, fumarate dihydrazide, itaconic acid dihydrazide, 1,1'-ethylenedihydrazide, 1,1'-trimethylenedihydrazide, and 1,1'-(1,4-butylene)dihydrazide. Among these, ethylenediamine, hydrazine, piperazine, isophorone diamine, 1,3-diaminomethylcyclohexane, 1,4-diaminomethylcyclohexane, and norbornane diamine (bis(aminomethyl)norbornane) are particularly preferred. In one embodiment of the invention, hydrazine or hydrazine derivatives may be in the form of a hydrate.

[0049] In one embodiment of the invention, (C2) is preferably derived from the general formula: H2N((CH2) n NH) m H (where n is 2 to 6 and m is 2 or 3) represents, specifically, diethylenetriamine, triethylenetetramine, iminobispropylamine, etc. Among these, diethylenetriamine and triethylenetetramine are particularly preferred.

[0050] Regarding the polyurethane resin of the present invention, as described above, it comprises: a first polyamine structural unit (C1) having two groups selected from amino, imino, and hydrazide groups; and a second polyamine structural unit (C2) having three or four groups selected from amino, imino, and hydrazide groups. With this configuration, the resulting polyurethane resin dispersion exhibits good droplet-forming properties.

[0051] In one embodiment of the present invention, (C) may comprise a polyamine, polyethyleneimine, or the like having five or more groups selected from amino and imino groups. In one embodiment of the present invention, the total moles of (C1) and (C2) relative to the total moles of (C) are 80 mol% or more, 85 mol% or more, 90 mol% or more, 95 mol% or more, or 98 mol% or more (upper limit 100 mol%). Having this lower limit improves 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 wt% or more, 85 wt% or more, 90 wt% or more, 95 wt% or more, or 98 wt% or more (upper limit 100 wt%). Having this lower limit improves the flexibility of the printed material.

[0052] 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%. By including this range, a more effective balance between droplet formation and the tactile feel of the printed material can be achieved. 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 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. 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 preferably 4.0 to 65.0 mol%, more preferably 10.0 to 35.0 mol%.

[0053] 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. By using this range, a more effective balance between droplet formation and the tactile feel of the printed material can be achieved. In one embodiment of the present invention, the mass of (C2) relative to the total mass of (C1) and (C2) is 3.0% or more by mass, 5.0% or more by mass, 10.0% or more by mass, 15.0% or more by mass, 20.0% or more by mass, 25.0% or more by mass, 30.0% or more by mass, 50.0% or more by mass, 70.0% or more by mass, or 90.0% or more by mass. 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. In one embodiment of the present invention, the mass of (C2) relative to the total mass of (C1) and (C2) is preferably 2.0 to 98.0% by mass, more preferably 5.0 to 60.0% by mass, and even more preferably 15.0 to 40.0% by mass.

[0054] According to one embodiment of the present invention, the total number of moles of functional groups (amino, imino, and hydrazide groups) of (C) relative to the total number of moles of isocyanate groups in (A) is preferably 10 to 40 mol%, more preferably 15 to 30 mol%.

[0055] In one embodiment of the present invention, the polyurethane resin is composed of structural units from (A), (B1), (B2), (C1), and (C2) at least 65 mol%, 70 mol%, 80 mol%, or 90 mol% of the total number of moles of all structural units. In another embodiment of the present invention, the polyurethane resin is preferably composed of structural units from (A), (B1), (B2), (C1), and (C2) at least 65 to 100 mol%, more preferably 70 to 90 mol%, and even more preferably 75 to 85 mol% of the total number of moles of all structural units. According to one embodiment of the present invention, the polyurethane resin is preferably substantially free of crosslinking groups (e.g., isocyanate groups). According to one embodiment of the present invention, in order to produce a polyurethane resin that is substantially free of isocyanate groups, for example, when using a chain extender to extend the chain of a urethane prepolymer containing terminal isocyanate groups, the chain extender is used in such a way that no isocyanate groups remain.

[0056] In one embodiment of the present invention, the acid value of the polyurethane resin, from the viewpoints of storage stability, droplet formation, and the feel (softness) of the printed material, is 4 to 32 mg KOH / g, or 5 mg KOH / g or more but less than 30 mg KOH / g. It should be noted that the acid value can be determined by the carboxyl groups and carboxylic acid ester groups (COO-) in the polyurethane resin. - The acid value of polyurethane resin is calculated from its content. When the acid value of the polyurethane resin is less than 5 mg KOH / g, the storage stability of the polyurethane resin dispersion may decrease; when it is above 30 mg KOH / g, the feel of the printed material may deteriorate. It should be noted that the acid value of polyurethane resin can be calculated as follows: Prepare a sample by dissolving the polyurethane resin in N,N-dimethylformamide. Then, use an automatic potentiometric titration apparatus (trade name "AT510", manufactured by Kyoto Electronics Industry) to perform potentiometric titration with potassium hydroxide ethanol titrant, thereby determining the acid value of the polyurethane resin.

[0057] In one embodiment of the invention, the acid value of the polyurethane resin is 7–25 mg KOH / g, 10–24 mg KOH / g, 15–23 mg KOH / g, or 17–22 mg KOH / g. By achieving such a range, preservation stability, droplet formation properties, and the feel (softness) of the printed material are further improved.

[0058] (Method for manufacturing a resin dispersion containing polyurethane resin and water)

[0059] The resin dispersion comprising polyurethane resin and water according to the present invention can be manufactured, for example, as described below.

[0060] (Prepolymer Production)

[0061] For example, (A) and (B), which reacts with it and contains (B1) and (B2), are reacted with an increased amount of isocyanate groups, resulting in isocyanate groups at the ends, thus synthesizing a prepolymer. Here, the total molar percentage of hydroxyl groups in (B) relative to the total molar percentage of isocyanate groups in (A) is preferably 70-90 mol%. Within this range, the viscosity of the isocyanate-terminated prepolymer is appropriate, emulsification is facilitated, and the ratio of urethane bonds to urea bonds is appropriate, thus suppressing excessive hardening of the polyurethane and improving flexibility and film-forming properties. There are no particular limitations on the specific method for manufacturing such an isocyanate-terminated prepolymer; for example, it can be manufactured using conventionally known one-shot methods or multi-stage isocyanate addition polymerization reactions. The reaction temperature is preferably 40-150°C. The reaction time is preferably 60-500 minutes. It should be noted that a solvent that does not react with the isocyanate groups can be added during or after the reaction. As such solvents, acetone, methyl ethyl ketone, toluene, tetrahydrofuran, etc., can be used. At this time, reaction catalysts such as dibutyltin dilaurate, stannous octoate, dibutyltin di(2-ethylhexanoate), triethylamine, triethylenediamine, N-methylmorpholine, bismuth tris(2-ethylhexanoate), or reaction inhibitors such as phosphoric acid, sodium hydrogen phosphate, p-toluenesulfonic acid, adipic acid, benzoyl chloride, etc., can be added as needed.

[0062] (Neutralization)

[0063] Even when a diol compound with a carboxylic acid ester group is not used as (B2), and even if the polyurethane resin does not meet the specified neutralization rate at its usage amount when used, the carboxyl groups of the prepolymer can be neutralized using any neutralizing agent in a manner that ensures the polyurethane resin reaches the specified neutralization rate. Thus, the carboxyl-terminated isocyanate group prepolymer is neutralized by using a suitable, known method before or after the preparation of the carboxyl-terminated isocyanate group prepolymer. Examples of neutralizing agents used in such neutralization include, for example, amines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine, N-methyldiethanolamine, N,N-dimethylmonoethanolamine (2-(dimethylamino)ethanol), N,N-diethylmonoethanolamine, and triethanolamine, as well as potassium hydroxide, sodium hydroxide, and ammonia. Tertiary amines such as trimethylamine, triethylamine, tri-n-propylamine, N,N-dimethylmonoethanolamine (2-(dimethylamino)ethanol), and tributylamine are particularly preferred. Preferably, the total molar number of carboxylic acid ester groups relative to the total molar number of carboxylic acid ester groups and carboxyl groups in the obtained polyurethane resin is 40 mol% or more. In one embodiment of the present invention, the total molar number of carboxylic acid ester groups relative to the total molar number of carboxylic acid ester groups and carboxyl groups in the obtained polyurethane resin is 40 to 100 mol%, or 50 to 80 mol%.

[0064] (emulsification)

[0065] Next, the isocyanate-terminated prepolymer is preferably emulsified and dispersed in water. There are no particular limitations on the emulsification equipment used for emulsification and dispersion in water; examples include homogenizers, homogenizers, and dispersers. During emulsification and dispersion, it is preferable to emulsify and disperse the prepolymer in water within a temperature range of 0–40°C without the use of any special emulsifier, thereby strongly suppressing the reaction between the isocyanate groups and water. Furthermore, during such emulsification and dispersion, 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.

[0066] (Chain extension)

[0067] Next, chain extension and crosslinking reactions are carried out by contacting (C), which can function as a chain extender, with other crosslinking agents and prepolymers as needed. For example, a chain extender is used to extend the chain of a urethane prepolymer containing terminal isocyanate groups that has been emulsified and dispersed in water. The reaction between the urethane prepolymer containing terminal isocyanate groups and (C) is carried out at a reaction temperature of 20–50°C, typically for 30–120 minutes after mixing the urethane prepolymer containing terminal isocyanate groups and (C).

[0068] (Desolventization)

[0069] In cases where organic solvents are used, it is preferable to remove them. As for removal conditions, it is preferable to remove the solvent by distillation under reduced pressure at 30–80°C.

[0070] The resin dispersion of the present invention contains water, and according to one embodiment of the invention, the mass percentage of polyurethane resin (resin solids component) relative to the total mass of the resin dispersion is in the range of 20-60% by mass. It should be noted that the concentration of the resin solids component in the resin dispersion can also be adjusted by adding water or removing it by distillation. According to one embodiment of the invention, the resin dispersion does not contain organic solvents, or even if it does, the mass ratio of the organic solvent to the polyurethane resin is less than 1.0, preferably 0.5 or less, more preferably 0.1 or less. With this embodiment, the stability of the resin dispersion is improved.

[0071] According to the method of manufacturing such a prepolymer, it is possible to obtain: a prepolymer having isocyanate groups at the ends of a prepolymer having structural units from (A) and structural units from (B); and a polyurethane resin having structural units from (C).

[0072] There is no particular limitation on the glass transition temperature (Tg) of polyurethane resin, but a low Tg is preferred from the viewpoint that the texture will not harden even after the image is formed. The Tg of the aqueous dispersion of polyurethane resin is below 0°C, preferably -80°C to 0°C.

[0073] It should be noted that, in terms of Tg calculation, it can be obtained as the temperature at which the peak (maximum value) of the ratio of E' and loss modulus (E” / E’) (E” / E’), i.e., the loss tangent (tanδ), is determined by the dynamic viscoelasticity test of the dried film (film sample) of the polyurethane resin dispersion is located.

[0074] There is no particular limitation on the volume average particle size (d50) of the polyurethane resin, but from the viewpoint of minimizing nozzle clogging of the inkjet head, it is preferably 300 nm or less, more preferably 130 nm or less. The lower limit of d50 can be, for example, 10 nm. According to one embodiment of the invention, the volume average particle size (d50) of the polyurethane resin is 10 nm to 300 nm or less. It should be noted that the volume average particle size (d50) of the polyurethane resin is measured using a dynamic light scattering particle size distribution measuring device, and is the 50% particle size at which the cumulative volume in the cumulative volumetric particle size distribution reaches 50% from the smallest particle size side.

[0075] <Inkjet ink>

[0076] In one embodiment of the present invention, inkjet ink is provided by comprising the resin dispersion of the present invention and the colorant.

[0077] (Polyurethane resin)

[0078] The inkjet 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, calculated in terms of solid content, is 5 to 20% by mass, preferably 5 to 10% by mass.

[0079] (Water-soluble organic solvent)

[0080] Inkjet inks may contain water-soluble organic solvents. Regarding water-soluble organic solvents, there are no particular restrictions as long as they are compatible with water. Examples include: polyols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, etc., dihydric alcohols, glycerol, trimethylolpropane, hexanetriol, etc., trihydric alcohols with three or more nucleotides); polyol 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, propylene glycol monomethyl ether, propylene glycol monoethyl ether); monohydric... Alcohols (e.g., methanol, ethanol, n-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-oxazolidinone, 1,3-dimethyl-2-imidazoline); sulfoxides (e.g., dimethyl sulfoxide); and sulfones (e.g., sulfolane).

[0081] From the viewpoint of easily and moderately increasing the viscosity of the ink, the water-soluble organic solvent preferably includes polyols. Regarding polyols, from the viewpoint of easily increasing the viscosity of the ink, it is preferable to include alcohols with three or more nucleotides, and more preferably glycerol. Specifically, the mass of the polyol relative to the total mass of the ink is preferably 1 to 50% by mass, or 2 to 45% by mass.

[0082] Furthermore, the ink preferably contains heterocyclic compounds such as 2-pyrrolidone. Specifically, the mass percentage of the heterocyclic compounds relative to the total mass of the ink is preferably 1–20% by mass, 2–15% by mass, or 3–8% by mass.

[0083] (Coloring agent)

[0084] Pigments are preferred as colorants. There are no particular limitations on the type of pigment used; for example, it can be an organic or inorganic pigment listed in the color index. Additionally, the colorant can be a solid colorant.

[0085] 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.

[0086] 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.

[0087] In the example of green pigment, pigments 7, 26, 36, and 50 are included. In the example of yellow pigment, pigments 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 are included.

[0088] In the example of black pigments, pigments 7, 28, and 26 are included.

[0089] 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, and CHROMOFINE Blue. HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, CHROMOFINE Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, CHROMOFINE Black A-1103, SEIKAFAST Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400(B), 2500, 2600, ZAY-260, 2700(B), 2770, SEIKAFAST Red8040, C405(F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, SEIKAFAST Carmine 6B1476T-7, 1483LT, 3840, 3870, SEIKAFAST Bordeaux10B-430, SEIKALIGHT Rose R40, SEIKALIGHT Violet B800, 7805, SEIKAFAST Maroon460N, SEIKAFAST Orange 900, 2900, SEIKALIGHT Blue C718, A612, Cyanine blue 4933M, 4933GN-EP, 4940, 4973 (manufactured by Daihatsu 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, FinecolYellow T-13, T-05, Pigment Yellow 1705, Colortex Orange 202, Colortex Red 101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, USN, Colortex Maroon 601, Colortex Brown B610N, Colortex Violet 600, Pigment Red 122, Colortex Blue 516, 517, 518, 519, A818, P-908, 510, Color tex Green 402, 403, Color tex Black 702, U905 (Sanyo Pigment); Lionol Yellow 1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (Toyo Inki); Toner Magenta E02, Permanent Rubin F6B, Toner Yellow HG, Permanent Yellow GG-02, Hos tapeam Blue B2G (Hearst Industries); Novoperm P-HG, Hos tapeam PinkE, Hos tapeam Blue B2G (manufactured by ヘキストインダストリ); 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, CF9 (Made by Mitsubishi Mitsubishi). ;

[0090] Dyes can also be used as coloring agents. Solid dyes are preferred, such as disperse dyes.

[0091] Examples of disperse dyes include CI Disperse 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, 119, 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; CI Disperse 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, 54, 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142; CI Disperse Red: 1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 5 2, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 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, 153, 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; CI Disperse 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; CI Disperse Green 9; CI Disperse 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, 153 154, 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; CI Disperse Black 1, 3, 10, 24.

[0092] Among these, pigments are preferred as colorants because they have good dispersibility for the components of ink and excellent weather resistance.

[0093] There is no particular limitation on the content of the colorant. From the viewpoint of easily adjusting the ink viscosity to the above-mentioned range and being able to form a high-density image, it is preferably 1 to 15% by mass relative to the total mass of the ink. If the mass percentage of the colorant is 1% or more, not only can the ink viscosity be moderately increased, but it is also easy to form a high-density image. If the mass percentage of the colorant is 15% or less, the ink viscosity is not excessively increased, so nozzle clogging is less likely to occur. From the same viewpoint, regarding the content of the colorant, it 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.

[0094] (Other ingredients)

[0095] For inkjet inks, additional components may be included as needed. Examples of these additional components include solvents, surfactants, preservatives, fungicides, rust inhibitors, pH adjusters, etc.

[0096] surfactants

[0097] Examples of surfactants include anionic, cationic, amphoteric, and nonionic surfactants. Examples of anionic surfactants include fatty acid salts, alkyl sulfates, alkyl sulfate esters, alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate salts, formalin condensates of alkylnaphthalene sulfonate, and polyoxyethylene alkyl sulfate salts. Examples of cationic surfactants include amine salts, tetraalkyl quaternary ammonium salts, trialkyl quaternary ammonium salts, alkylpyridinium salts, and alkylquinolineium 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, alkynyl glycols, and ethylene oxide adducts of alkynyl glycols. Examples of surfactants also include polyethylene glycol-modified silicones.

[0098] The surfactant content relative to the total mass of the ink is more preferably 0.01 to 5% by mass, and more preferably 0.05 to 1% by mass.

[0099] Preservatives, mildew inhibitors

[0100] Examples of preservatives or fungicides include aromatic halogen compounds (e.g., Preventol CMK, a registered trademark), methylene dithiocyanate, halogenated nitrogen and sulfur compounds, and 1,2-benzisothiazolin-3-ones (e.g., Proxel GXL, a registered trademark).

[0101] pH adjuster

[0102] Examples of pH adjusters include urea and sodium hydroxide.

[0103] The present invention includes the following schemes and implementation methods.

[0104] [1] A resin dispersion for inkjet ink, comprising: a polyurethane resin having structural units from (A) a polyisocyanate, structural units from (B) a polyol and structural units from (C) a polyamine; and water, wherein the (B) polyol comprises (B1) a polyether polyol and (B2) a diol compound having a carboxyl group and / or a carboxyl ester group, and the (C) polyamine comprises (C1) a first polyamine having two groups selected from amino, imino and hydrazide groups and (C2) a second polyamine having three or four groups selected from amino, imino and hydrazide groups.

[0105] [2] According to the resin dispersion described in [1] above, wherein the polyurethane resin has: a structural unit of a prepolymer having an isocyanate group at the end having a structural unit from the structural unit from (A) above and a structural unit from the structural unit from (B) above; and a structural unit from (C) above.

[0106] [3] The resin dispersion according to [1] or [2] above, wherein the polyurethane resin contains a carboxylic acid ester group.

[0107] [4] The resin dispersion according to any one of [1] to [3] above, wherein the total number of carboxylic acid ester groups relative to the total number of moles of carboxylic acid ester groups and carboxyl groups in the polyurethane resin is 40 mol% or more.

[0108] [5] The 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%.

[0109] [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.

[0110] [7] The resin dispersion according to any one of [1] to [6] above, wherein the total number of hydroxyl groups contained in [B] above is 70 to 90 moles relative to the total number of isocyanate groups contained in [A] above.

[0111] [8] The resin dispersion according to any one of [1] to [7] above, wherein (B) above does not contain an aliphatic cyclic structure.

[0112] [9] The resin dispersion according to any one of [1] to [8] above, wherein the total number of moles of (B1) and (B2) above relative to the total number of moles of (B) above is 50 mol% or more.

[0113]

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

[0114]

[11] The resin dispersion according to any one of [1] to

[10] above, wherein the above (B1) polyether polyol is a polyalkylene ether diol, and the number of carbon atoms of the alkylene group in the polyalkylene ether diol is preferably 2 to 6, more preferably 2 to 5, further preferably 2 to 4, and particularly preferably 3 or 4.

[0115]

[12] The resin dispersion according to any one of [1] to

[11] above, wherein the mass of (B1) polyether polyol relative to the total mass of (B1) polyether polyol contained in (B) and polycarbonate polyol and polyester polyol contained in (B) is preferably 40 to 100% by mass, more preferably 50 to 100% by mass.

[0116]

[13] The resin dispersion according to any one of [1] to

[12] above, wherein the total number of low molecular weight polyols relative to the total number of moles of the polyols in (B) above is preferably 0 to 50 mol%, more preferably 0 to 40 mol%.

[0117]

[14] The resin dispersion according to any one of [1] to

[13] above, wherein the total mass of the low molecular weight polyol relative to the total mass of the polyol (B) above is preferably 0 to 5.0% by mass, more preferably 0 to 4.0% by mass.

[0118]

[15] The resin dispersion according to any one of [1] to

[14] above, wherein the total number of the above (B1) and above (B2) relative to the total number of the above (B) polyol is preferably 50 to 100 mol%, more preferably 60 to 100 mol%.

[0119]

[16] The resin dispersion according to any one of [1] to

[15] above, wherein the number of moles of (B2) above relative to the total number of moles of (B) above is preferably greater than 45 mol% and less than 70 mol%, more preferably 47 to 65 mol%, and particularly preferably 49 to 60 mol%.

[0120]

[17] In the resin dispersion according to any one of [1] to

[16] above, the total number of carboxylic acid ester groups relative to the total number of moles of carboxylic acid ester groups and carboxyl groups in the polyurethane resin is preferably 40 to 100 mol%, more preferably 50 to 80 mol%.

[0121]

[18] The resin dispersion according to any one of [1] to

[17] above, wherein the total number of moles of (C1) and (C2) relative to the total number of moles of (C) above is preferably 80 to 100 mol%, more preferably 85 to 100 mol%, and even more preferably 90 to 100 mol%.

[0122]

[19] The resin dispersion according to any one of [1] to

[18] above, wherein the total mass of (C1) and (C2) relative to the total mass of (C) above is preferably 80 to 100% by mass, more preferably 85 to 100% by mass, and even more preferably 90 to 100% by mass.

[0123]

[20] The resin dispersion according to any one of [1] to

[19] above, wherein the total number of moles of (C2) relative to the total number of moles of (C1) and (C2) above is preferably 4.0 to 65 mol%, more preferably 10 to 35 mol%.

[0124]

[21] The resin dispersion according to any one of [1] to

[20] above, wherein the mass of (C2) relative to the total mass of (C1) and (C2) is preferably 2.0 to 98.0% by mass, more preferably 5.0 to 60.0% by mass, and even more preferably 15.0 to 40.0% by mass.

[0125]

[22] The resin dispersion according to any one of [1] to

[21] above, wherein, relative to the total number of moles of all structural units of the polyurethane resin, preferably 65 to 100 mol%, more preferably 70 to 90 mol%, and even more preferably 75 to 85 mol% is composed of structural units from (A), structural units from (B1), structural units from (B2), structural units from (C1), and structural units from (C2).

[0126]

[23] The resin dispersion according to any one of [1] to

[22] above, wherein the resin dispersion does not contain organic solvent, or even if it does contain organic solvent, the mass ratio of organic solvent to polyurethane resin is preferably less than 1.0, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0127]

[24] The resin dispersion according to any one of [1] to

[23] above, wherein, relative to the total number of moles of all structural units of the polyurethane resin, 65 mol% or more is composed of structural units from (A), structural units from (B1), structural units from (B2), structural units from (C1), and structural units from (C2).

[0128] Example

[0129] The following describes specific embodiments of the present invention, but the present invention is not limited thereto.

[0130] <Synthesis of Polyurethane Resins>

[0131] (Example 1)

[0132] In a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen purging tube, 205.6 parts by mass of (B1) polytetramethylene glycol (number average molecular weight 2000) as (B), 14.9 parts by mass of (B2) dimethylolpropionic acid, and 123.4 parts by mass of methyl ethyl ketone (MEK) as solvent were measured and mixed evenly. Then, 67.3 parts by mass of dicyclohexylmethane diisocyanate as (A) were added, and the mixture was reacted at 85±5°C for 300 minutes to obtain a MEK solution of a urethane prepolymer containing terminal isocyanate groups with an isocyanate group content of 1.30% by mass. The solution was then cooled, and 9.9 parts by mass of dimethylaminoethanol were added at 40°C for neutralization. Next, 708.8 parts by mass of water were slowly added while stirring to emulsify and disperse the urethane prepolymer containing terminal isocyanate groups. In this emulsified dispersion, 1.6 parts by mass of (C1) hydrazine 1-hydrate and 0.6 parts by mass of (C2) diethylenetriamine were added. After stirring at 40±5℃ for 90 minutes, the mixture was desolventized (demethyl ethyl ketone treatment) at 40℃ under reduced pressure to obtain a polyurethane resin dispersion with a polyurethane resin solid content of 30.0% by mass.

[0133] (Examples 2-11, Comparative Examples 1-6)

[0134] Except for changing the types and amounts of (B), (A), and (C) as shown in Table 1, a polyurethane resin dispersion was obtained in the same manner as in Example 1. It should be noted that blank spaces in the table indicate that the component was not added.

[0135] <Preservation Stability>

[0136] 200g of the synthesized polyurethane resin dispersion was sealed in a transparent 200mL bottle and left to stand in an oven at 60°C for one month. The presence or absence of resin sedimentation was visually evaluated. It should be noted that if the evaluation is as described in B below, it is permissible in practical applications.

[0137] A: No resin components settle in the dispersion.

[0138] B: Water was observed floating on the surface of the dispersion, but no resin sedimentation was observed.

[0139] C: Resin components settle in the dispersion.

[0140] <Determination of Glass Transition Temperature>

[0141] A polyurethane resin dispersion was coated onto a release membrane to achieve a dry film thickness of 400 μm. After being placed at room temperature (20°C) and humidity (65% RH) for 48 hours, the membrane was heat-treated at 120°C for 45 minutes in a dryer to prepare a polyurethane resin film. This polyurethane resin film was then peeled off from the release membrane and cut into rectangular shapes suitable for dynamic viscoelasticity testing to prepare polyurethane resin samples. Dynamic viscoelasticity was measured using a dynamic viscoelasticity measuring apparatus (manufactured by Hitachi Hightech Co., Ltd., trade name "DMA7100") under tensile mode, frequency 10 Hz, temperature -120 to 180°C, and heating rate 5°C / min. A graph showing the temperature dependence of storage modulus (E'), loss modulus (E”), and loss tangent (tanδ) obtained from this measurement (horizontal axis: temperature) was created. The temperature of the peak representing the temperature dependence of tanδ was then set as the glass transition temperature (°C).

[0142] <Volume average particle size>

[0143] The polyurethane resin dispersion was diluted 60 times using ion-exchanged water, and the volume average particle size d50 of the diluted solution was determined using a dynamic light scattering particle size distribution measuring device (Zetasizer Nano ZS manufactured by Marine Corporation).

[0144] <The feel of printed materials>

[0145] (Ink preparation)

[0146] An ink was prepared by adding 3% by mass of solid colorant Pigment Black, 33.3% by mass of a polyurethane resin dispersion (30% by mass of solid components), 4% by mass of 2-pyrrolidone, 5% by mass of glycerin, 0.1% by mass of preservative Proxel GXL (1,2-benzisothiazolin-3-one), and 0.1% by mass of surfactant KF-351A (manufactured by Shin-Etsu Chemical Industry Co., Ltd., polyethylene glycol modified silicone), and then using water to make it 100% by mass. This ink contains 10% by mass of polyurethane resin on a solids basis.

[0147] (Methods for printing tests)

[0148] The prepared ink was ejected from the nozzle of the inkjet head of a simple printing test machine, forming a 100% solid image on fabric (cotton satin 60). Specifically, a 200mm × 200mm solid image was formed using a main scan of 540dpi × a sub-scan of 720dpi. DPI refers to the number of ink droplets per 2.54cm. The ink adhesion was calculated as 15g / m². 2The discharge rate was adjusted accordingly. Then, the image was dried at 150°C for 3 minutes using a belt conveyor dryer to obtain the image formation.

[0149] • Criteria for judging feel

[0150] The obtained image formation will be evaluated using the bending stress B value calculated by a Katotec pure bending tester (KES-FB2-A) as an indicator, based on the following criteria. It should be noted that the following B evaluation is practically permissible.

[0151] A: For images where the B value is less than 1.5 times before formation, sensory evaluation is used to determine the level of change in feel.

[0152] B: For images where the B value before image formation is greater than 1.5 but less than 3 times, the change in feel is assessed using sensory evaluation.

[0153] C: For images where the B value is more than 3 times the pre-image value, the sensory evaluation indicates a problem with the feel.

[0154] <Test Methods for Droplet Formation>

[0155] Using a droplet observation device equipped with a flash unit, camera, and Konica Minolta inkjet head KM1024, the droplet velocity was changed by adjusting the ejection drive voltage in an environment of 25°C and 50% RH. At the same time, the ink flight state at a position 1 mm away from the nozzle surface was observed by a high-speed camera, and the satellite point generation velocity was determined.

[0156] Evaluation Criteria

[0157] Based on measurements using a droplet observation device, if the satellite point generation velocity is 6.0 m / s or higher, the ink characteristics are deemed suitable for printing equipment. It should be noted that the following evaluation A is preferred in practical application.

[0158] A: The satellite point generation velocity is above 6.0 m / s.

[0159] C: The satellite point generation speed is less than 6.0 m / s.

[0160]

[0161]

[0162] This application is based on Japanese Patent Application Serial No. 2024-168275, filed on September 27, 2024, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A resin dispersion for inkjet ink, comprising: a polyurethane resin having structural units derived from (A) a polyisocyanate, structural units derived from (B) a polyol, and structural units derived from (C) a polyamine; and water, The (B) polyol comprises: (B1) a polyether polyol; and (B2) a diol compound having carboxyl and / or carboxylic acid ester groups. The (C) polyamine comprises: (C1) a first polyamine having two groups selected from amino, imino and hydrazide groups; and (C2) a second polyamine having three or four groups selected from amino, imino and hydrazide groups.

2. The resin dispersion according to claim 1, wherein, The polyurethane resin has the following characteristics: Structural units derived from a prepolymer having isocyanate groups at the ends of structural units having structural units from (A) and structural units from (B); and The structural unit derived from (C).

3. The resin dispersion according to claim 1, wherein, The polyurethane resin contains carboxylic acid ester groups.

4. The resin dispersion according to claim 1, wherein, The total number of carboxylic acid ester groups relative to the total number of moles of carboxylic acid ester 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 above 5 mg KOH / g and less than 30 mg KOH / g.

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

8. The resin dispersion according to claim 1, wherein, The (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, Relative to the total number of moles of all structural units in the polyurethane resin, 65 mol% or more are composed of structural units from (A), structural units from (B1), structural units from (B2), structural units from (C1), and structural units from (C2).

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