Ink set

Abstract

An advantage of some aspects of the invention is to provide an ink set which can be printed on various printing substrates, in which bleeding of dots during printing is suppressed, and which has favorable gloss.SOLUTION: An ink set comprising at least a first ink and a second ink, wherein the first ink comprises a colorant (A), a resin (B), and a solvent (E), the second ink comprises a colorant (A), a resin (C), and a solvent (E), and the resin (B) comprises a hydrophobic monomer unit and an acid group-containing monomer unit, the resin (C) is a copolymer containing a monomer unit having hydrophobicity, a monomer unit having an acid group, and a monomer unit having a hydrophilic group other than an acid group, and the monomer unit having a hydrophilic group other than an acid group is a monomer unit containing one or more selected from a hydroxyl group and a (poly) alkyleneoxy group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink set for use in, for example, inkjet inks. [Background technology]

[0002] Inkjet recording is a method of printing characters and images by ejecting ink droplets directly from extremely fine nozzles onto a printing substrate. This method has become extremely popular due to its many advantages, including ease of full color printing, low cost, compatibility with a variety of substrate materials, and non-contact with the printing substrate. In recent years, the use of pigments as colorants has become mainstream due to the weather resistance and water resistance of printed materials.

[0003] For example, Patent Document 1 discloses an ink set having black ink and color ink, each of which is an aqueous ink in which a pigment is dispersed in an aqueous medium using a polymer, and the polymer used in the black ink is a crosslinked polymer (A) obtained by crosslinking a polymer having an acid value of 70 to 140 mgKOH / g, and the residual acid value a of the crosslinked polymer (A) is 30 to 60 mgKOH / g, while the polymer used in the color ink is a crosslinked polymer (B) obtained by crosslinking a polymer having an acid value of 180 to 250 mgKOH / g, and the residual acid value b of the crosslinked polymer (B) is 55 to 110 mgKOH / g. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-011515 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] However, the resin used in the ink set of Patent Document 1 is styrene-acrylic acid only. When an ink set is designed using a resin having only a specific structure, it may be incompatible with some printing substrates used during printing, and may cause dot bleeding (smearing or spreading of dots) particularly during inkjet printing, making it difficult to print good images.

[0006] An object of the present invention is to provide an ink set that can be printed on a variety of printing substrates, that suppresses bleeding of dots during printing, and that provides good gloss. [Means for solving the problem]

[0007] The ink set of the present invention comprises: An ink set having at least a first ink and a second ink, the first ink contains a colorant (A), a resin (B), and a solvent (E); the second ink contains a colorant (A), a resin (C), and a solvent (E); the resin (B) is a copolymer containing a hydrophobic monomer unit and a monomer unit having an acid group, but not containing a monomer unit having a hydrophilic group other than an acid group; the resin (C) is a copolymer containing a hydrophobic monomer unit, a monomer unit having an acid group, and a monomer unit having a hydrophilic group other than an acid group, The monomer unit having a hydrophilic group other than an acid group is a monomer unit containing at least one selected from a hydroxyl group and a (poly)alkyleneoxy group. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an ink set that can be printed on a variety of printing substrates, that suppresses bleeding of dots during printing, and that provides good gloss. DETAILED DESCRIPTION OF THE INVENTION

[0009] The terms used in the present invention are defined below. "CI" is the Color Index number. "(Meth)acrylate" includes acrylate and methacrylate. "(Meth)acrylic acid" includes acrylic acid and methacrylic acid. "(Maleic anhydride)" includes maleic anhydride and maleic acid. "(Poly)alkyleneoxy group" includes alkyleneoxy group and polyalkyleneoxy group. A monomer is an ethylenically unsaturated group-containing compound before polymerization, and is also called a monomer. A monomer unit is incorporated into a resin after polymerization of the monomer.

[0010] The ink set of the present invention comprises: An ink set having at least a first ink and a second ink, the first ink contains a colorant (A), a resin (B), and a solvent (E); the second ink contains a colorant (A), a resin (C), and a solvent (E); the resin (B) is a copolymer containing a hydrophobic monomer unit and a monomer unit having an acid group, but not containing a monomer unit having a hydrophilic group other than an acid group; the resin (C) is a copolymer containing a hydrophobic monomer unit, a monomer unit having an acid group, and a monomer unit having a hydrophilic group other than an acid group, The monomer unit having a hydrophilic group other than an acid group is a monomer unit containing at least one selected from a hydroxyl group and a (poly)alkyleneoxy group.

[0011] When the ink set of the present invention is used, printing can be performed on a variety of printing substrates, bleeding of dots during printing is suppressed, and good gloss is achieved. The reasons for these effects are thought to be as follows: The first ink contains a highly hydrophobic resin (B), which has good affinity with hydrophobic substrates, but tends to cause dots to bleed easily when applied to hydrophobic substrates. Furthermore, because it has a relatively low affinity with hydrophilic substrates, the dots tend not to bleed easily when applied to hydrophilic substrates. The second ink contains a highly hydrophilic resin (C), which has good affinity with hydrophilic substrates, but tends to cause dots to bleed easily when applied to hydrophilic substrates. Furthermore, its affinity with hydrophobic substrates is somewhat low, so dots tend not to bleed easily when applied to hydrophobic substrates. Therefore, by using the first ink and the second ink together, for example, when coated on a hydrophobic substrate, the first ink is hydrophobic and therefore the dots are likely to bleed, but when the hydrophilic second ink is coated on the adjacent area, the second ink acts like a breakwater to prevent the first ink from bleeding, thereby resulting in a clear printed image.In the case of a hydrophilic substrate, the relationship between the first ink and the second ink is reversed, and it is also presumed that a clear image can be obtained by suppressing bleeding. Furthermore, when the hydrophobic monomer units in resin (B) and resin (C) contain at least one monomer unit selected from the group consisting of (meth)acrylic acid alkyl ester monomer units, aromatic monomer units, heterocyclic monomer units, and α-olefin monomer units, it is presumed that resin (B) and resin (C) are effectively adsorbed to the colorant, and dispersion progresses to the primary particle level, thereby further improving gloss.

[0012] In this specification, examples of the hydrophobic substrate include plastic films, etc. Examples of the plastic film include polyethylene films, polypropylene films, polyethylene terephthalate films, polyester films, and ethylene vinyl acetate resin films. Examples of hydrophilic substrates include high-quality paper and the above-mentioned hydrophobic substrates that have been subjected to surface modification such as corona discharge treatment or plasma discharge treatment, or surface treatment with an organic low-molecular-weight treating agent, organic high-molecular-weight treating agent, inorganic treating agent, etc. Specific examples include corona discharge-treated polyethylene film, plasma discharge-treated polypropylene film, sorbitan monostearate-treated polyethylene vinyl acetate resin film, sucrose-alkylene oxide-fatty acid ester-treated polypropylene film, and polysilicate ceramic-treated polyester film.

[0013] <Colorant (A)> The ink set of the present invention contains a colorant (A). The colorant (A) is a pigment or dye that is insoluble in an aqueous medium. A water-soluble dye can also be used in combination with the colorant (A). Pigments include, for example, CI Pigment Red 3, 5, 19, 22, 31, 38, 42, 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, 147, 149, 150, 166, 168, 169, 170, 176, 177, 178, 179, 184, 185, 202, 208, 216, 226, 242, 254, 255, 257, 269, 291; CI Pigment Green 7,26,36,50,58,59,62,63; CI Pigment Blue 1,15,15:1,15:2,15:3,15:4,15:6,16,17,17:1,22,27,28,29,36,60; CI Pigment Orange 13,16,20,34,36,38,43,62,64,71,73; CI Pigment Yellow 1,3,12,13,14,17,34,35,37,55,74,81,83,93,94,95,97,108,109,110,120,128,137,138,139,150,153,154,155,157,166,167,168,174,180,185,193,213,234; CI Pigment Violet 3,19,23,29,30,37,50,88; CI Pigment Black 7,28,26; CI Pigment White 6, 18, 21; etc.

[0014] Disperse dyes include, for example, CI Disperse Red 11, 50, 53, 54, 55, 55:1, 59, 60, 65, 70, 72, 73, 75, 86, 88, 91, 92, 93, 111, 126, 127, 134, 135, 143, 145, 146, 152, 153, 154, 158, 159, 164, 167:1, 177, 181, 190, 190:1, 204, 206, 207, 221, 239, 240, 258, 277, 278, 283, 311, 323, 343, 348, 356, 362; CI Bat Red 41; CI Disperse Green 6:1,9; CI Disperse Blue 19,26,26:1,35,55,56,58,60,64,64:1,72,72:1,73,81,81:1,87,91,95,108,113,128,131,141,143,145,148,154,158,165,165:1,165:2,176,183,185,197,198,201,214,224,225,257,266,267,287,354,358,359,360,365,368; CI Disperse Orange 1,1:1,5,13,20,25,25:1,29,31:1,33,49,54,55,56,66,73,76,118,119,163; CI Disperse Yellow 3,5,7,8,23,39,42,51,54,60,64,71,79,82,83,86,93,99,100,119,122,124,126,160,184:1,186,198,199,201,204,224,237; CI Disperse Violet 8,17,23,27,28,29,33,36,57; CI Disperse Brown 2; etc.

[0015] Examples of water-soluble dyes include direct dyes, acid dyes, food dyes, basic dyes, and reactive dyes. For example, CI Direct Red 2, 4, 9, 23, 26, 31, 39, 62, 63, 72, 75, 76, 79, 80, 81, 83, 84, 89, 92, 95, 111, 173, 184, 207, 211, 212, 214, 218, 223, 224, 225, 226, 227, 232, 233, 240, 241, 242, 243, and 247; CI Direct Violet 7,9,47,48,51,66,90,93,94,95,98,100,101; CI Direct Yellow 8,9,11,12,27,28,29,33,35,39,41,44,50,53,58,59,68,86,87,93,95,96,98,100,106,108,109,110,130,132,142,144,161,163; CI Direct Blue 1,10,15,22,25,55,67,68,71,76,77,78,80,84,86,87,90,98,106,108,109,151,156,158,159,160,168,189,192,193,194,199,200,201,202,203,207,211,213,214,218,225,229,236,237,244,248,249,251,252,264,270,280,288,289,291; CI Direct Black 9,17,19,22,32,51,56,62,69,77,80,91,94,97,108,112,113,114,117,118,121,122,125,132,146,154,166,168,173,199 CI Acid Red 35,42,52,57,62,80,82,111,114,118,119,127,128,131,143,151,154,158,249,254,257,261,263,266,289,299,301,305,336,337,361,396,397; CI Acid Violet 5,34,43,47,48,90,103,126; CI Acid Yellow 17,19,23,25,39,40,42,44,49,50,61,64,76,79,110,127,135,143,151,159,169,174,190,195,196,197,199,218,219,222,227; CI Acid Blue 9, 25, 40, 41, 62, 72, 76, 78, 80, 82, 92, 106, 112, 113, 120, 127: 1, 129, 138, 143, 175, 181, 205, 207, 220, 221, 230, 232, 247, 258, 260, 264, 271, 277, 278, 279, 280, 288, 290, 326 CI Acid Black 7,24,29,48,52:1,172; CI Reactive Red 3,13,17,19,21,22,23,24,29,35,37,40,41,43,45,49,55; CI Reactive Violet 1,3,4,5,6,7,8,9,16,17,22,23,24,26,27,33,34; CI Reactive Yellow 2,3,13,14,15,17,18,23,24,25,26,27,29,35,37,41,42; CI Reactive Blue 2,3,5,8,10,13,14,15,17,18,19,21,25,26,27,28,29,38; CI Reactive Black 4,5,8,14,21,23,26,31,32,34; CI Basic Red 12,13,14,15,18,22,23,24,25,27,29,35,36,38,39,45,46; CI Basic Violet 1,2,3,7,10,15,16,20,21,25,27,28,35,37,39,40,48; CI Basic Yellow 1,2,4,11,13,14,15,19,21,23,24,25,28,29,32,36,39,40; CI Basic Blue 1,3,5,7,9,22,26,41,45,46,47,54,57,60,62,65,66,69,71; CI Basic Black 8; etc.

[0016] The colorant (A) can be used alone or in combination of two or more kinds.

[0017] <Resin (B)> The ink set of the present invention includes a first ink containing a resin (B). The resin (B) is a copolymer containing a hydrophobic monomer unit and a monomer unit having an acid group, but not a monomer unit having a hydrophilic group other than an acid group. The monomer unit having a hydrophilic group other than an acid group will be described later.

[0018] [Monomer unit having a hydrophobic group] The monomer unit having a hydrophobic group can be introduced into the resin (B) by polymerizing a monomer containing one or more selected from a (meth)acrylic acid alkyl ester monomer, an aromatic monomer, a heterocyclic monomer, and an α-olefin monomer.

[0019] Examples of the (meth)acrylic acid alkyl ester monomer include methyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexane (meth)acrylate, furfuryl (meth)acrylate, isobornyl (meth)acrylate, adamantane (meth)acrylate, and 2-methyladamantane (meth)acrylate. Examples of aromatic monomers include styrene, α-methylstyrene, styrene macromer, 2-methylstyrene, 4-methylstyrene, 4-n-octylstyrene, 4-methoxystyrene, 4-aminostyrene, 4-nitrostyrene, 4-vinylphenylacetate, 2-vinylquinoline, 2-vinylnaphthalene, 4-vinylbiphenyl, 9-vinylanthracene, 9-vinylphenanthrene, phenyl(meth)acrylate, benzyl(meth)acrylate, phenoxyethyl(meth)acrylate, phenoxydiethyleneglycol(meth)acrylate, and phenoxypolyethylene. Examples of the alkyl acrylate include ethylene glycol (meth)acrylate, pentafluorophenyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, neopentyl glycol (meth)acrylic acid benzoate, 4-[(6-(meth)acryloyloxy)hexyloxy]-4'-cyanobiphenyl, N-phenyl(meth)acrylamide, allyl phenyl acetate, allyl phenyl ether, and allyl phenoxy acetate. Examples of heterocyclic monomers include 4-vinylpyridine, vinylimidazole, 1-vinyl-1H-indole, etc. Examples of α-olefin monomers include 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, etc.

[0020] The inclusion of a monomer unit having a hydrophobic group allows the resin (B) to adsorb to the colorant (A), which facilitates dispersion of the colorant down to the primary particle level, improving gloss. Preferred examples of the monomer unit having a hydrophobic group include (meth)acrylic acid alkyl ester monomer units, aromatic monomer units, heterocyclic monomer units, and α-olefin monomer units, with α-olefin monomer units being more preferred.

[0021] The monomer units having a hydrophobic group can be used alone or in combination of two or more kinds.

[0022] [Monomer unit having an acid group] The monomer unit having an acid group can be introduced into the resin (B) by polymerizing, for example, a monomer having a carboxy group, a sulfo group, or a phosphoric acid group.

[0023] Examples of the monomer having a carboxy group include a (meth)acrylic acid monomer unit and a (maleic anhydride) monomer unit. Examples of the (meth)acrylic acid monomer include methacrylic acid, acrylic acid, methacrylic acid dimer, acrylic acid dimer, ethylene oxide-modified succinic acid (meth)acrylate, β-carboxyethyl (meth)acrylate, and ω-carboxypolycaprolactone (meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxypropyl hexahydrophthalate; and salts thereof. Examples of maleic acid (anhydride) monomers include maleic anhydride, maleic acid, maleic acid half esters (maleic acid mono-n-butyl ester, maleic acid monoisopropyl ester, etc.), maleic acid half amides (maleic acid monoamide, maleic acid monolaurylamide, maleic acid monostearylamide, etc.), and salts thereof. Examples of monomer units having a carboxy group other than those described above include carboxy group-containing monomers such as crotonic acid, fumaric acid, fumaric acid half ester, fumaric acid half amide, itaconic acid, itaconic acid half ester, itaconic acid half amide, tetrahydrophthalic acid, tetrahydrophthalic acid half ester, tetrahydrophthalic acid half amide, and compounds having a betaine structure; and salts thereof.

[0024] Examples of the monomer having a sulfo group include vinyl sulfonic acid, acrylamido-tertiary butyl sulfonic acid, 2-sulfoethyl (meth)acrylate, 3-sulfopropyl (meth)acrylate, styrene sulfonic acid, and salts thereof.

[0025] Examples of the monomer having a phosphoric acid group include bis(methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, and dibutyl-2-acryloyloxyethyl phosphate; and salts thereof.

[0026] When a monomer unit having an acid anhydride group such as maleic anhydride is used as the monomer unit having an acid group, it is also preferable to introduce COOH and / or COOR groups into resin (B) or resin (C) by reacting with water or alcohol. Here, R represents an alcohol residue. Appropriate reaction conditions must be selected for the reaction, such as carrying out the reaction in a polar organic solvent in the presence of a basic catalyst such as diazabicycloundecene. It is also preferable to introduce COOH and CONHR groups into resin (B) or resin (C) by reacting with an amine, where R is an amine residue. Appropriate reaction conditions must be selected for the reaction, such as in a protic polar solvent such as N,N-dimethylformamide.

[0027] Examples of alcohols include methanol, ethanol, propanol, butanol, pentanol, hexanol, decanol, and structural isomers thereof, cyclohexanol, phenol, and benzyl alcohol.

[0028] Examples of amines include ammonia, hydrazine, ethylenediamine, diethylenetriamine, methylamine, ethylamine, propylamine, isopropylamine, butylamine, amylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, laurylamine, myristylamine, cetylamine, stearylamine, oleylamine, aniline, o-toluidine, 2-ethylaniline, 2-fluoroaniline, o-anisidine, m-toluidine, m-anisidine, m-phenetidine, p-toluidine, 2,3-dimethylaniline, 5-aminoindan, aspartic acid, glutamic acid, and γ-aminobutyric acid.

[0029] Examples of compounds having an amino group and a hydroxyl group in one molecule include methanolamine, ethanolamine, propanolamine, hexanolamine, 2-aminophenol, 4-aminophenol, and aminocyclohexanol.

[0030] Alcohols, amines, and compounds having an amino group and a hydroxyl group in one molecule can be used alone or in combination of two or more kinds. Water can also be used in combination.

[0031] As the monomer unit having an acid group, a monomer unit having a carboxy group is preferred, a maleic anhydride monomer unit, a maleic acid monomer unit, a maleic acid half ester monomer unit, a maleic acid half amide monomer unit, or a (meth)acrylic acid monomer unit is more preferred, and a maleic anhydride monomer unit, a maleic acid monomer unit, a maleic acid half ester monomer unit, or a maleic acid half amide monomer unit is even more preferred.

[0032] The monomer units having an acid group can be used alone or in combination of two or more kinds.

[0033] The amount of the monomer having an acid group used in synthesizing the resin (B) is preferably 10 to 90 mass %, more preferably 20 to 80 mass %, and even more preferably 30 to 70 mass % of the total monomers used in synthesizing the resin (B). By setting the content of the monomer having a carboxy group, sulfo group, or phosphate group within the above range, viscosity stability is improved due to charge repulsion, which is preferable. Among these, the carboxy group is particularly preferable because viscosity stability is particularly improved due to charge repulsion.

[0034] Commercially available resins (B) include, for example, Joncryl 67, 586, 611, 678, 680, 682, 683, 690, 693, HPD671, and HPD696 (styrene-acrylic acid copolymers) manufactured by BASF Japan Ltd., Ceramer 67, 1608, and 1251 (α-olefin-maleic anhydride-maleic acid half ester polymers) manufactured by NUCERA, SMA1000, 2000, 3000, 3000H, EF30, EF40, EF60, EF80, 1400, 17352, 2625, and 3840 (styrene-maleic anhydride polymers) manufactured by Cray Valley, and Polyscope Polymers. Examples include XIRAN 1000, 2000, 2500, 3000, 3000P, 3500, 3600, 4000, 6000, and 9000 (styrene-maleic anhydride copolymers) manufactured by Polyscope Polymers BV; XIRAN 1440, 2625, 17352, and 3840 (styrene-maleic anhydride ester-modified polymers) manufactured by Polyscope Polymers BV; and the Arastar series (styrene-maleic anhydride half ester polymers) manufactured by Arakawa Chemical Industries, Ltd.

[0035] <Resin (C)> The second ink of the ink set of the present invention contains a resin (C), which is a copolymer containing a hydrophobic monomer unit, a monomer unit having an acid group, and a monomer unit having a hydrophilic group other than an acid group. The hydrophobic monomer unit and the acid group-containing monomer unit may be the same as those described above.

[0036] [Monomer units having hydrophilic groups other than acid groups] The monomer unit having a hydrophilic group other than an acid group can be introduced into the resin (C) by polymerizing a monomer having a hydroxyl group or a (poly)alkyleneoxy group.

[0037] [Monomer unit having a hydroxyl group] The monomer unit having a hydroxyl group can be introduced into the resin (C) by polymerizing a monomer having a hydroxyl group. Examples of the monomer having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2 (or 3)-hydroxypropyl (meth)acrylate, 2 (or 3 or 4)-hydroxybutyl (meth)acrylate, and cyclohexanedimethanol mono(meth)acrylate; (meth)acrylamide-based monomers having a hydroxyl group, such as N-(hydroxyalkyl) (meth)acrylamides such as N-(2-hydroxyethyl) (meth)acrylamide, N-(2-hydroxypropyl) (meth)acrylamide, and N-(2-hydroxybutyl) (meth)acrylamide; and vinyl ether-based monomers having a hydroxyl group, such as 2-hydroxyethyl vinyl ether, 2-(or hydroxyalkyl vinyl ethers such as 2-(3- or 4-)hydroxypropyl vinyl ether, 2-(or 3- or 4-)hydroxybutyl vinyl ether, or allyl ether monomers having a hydroxy group, for example, hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether, 2-(or 3-)hydroxypropyl allyl ether, 2-(or 3- or 4-)hydroxybutyl allyl ether, as well as hydroxy group-containing monomers such as ethylenically unsaturated monomers obtained by adding alkylene oxide and / or lactone to the above-mentioned hydroxyalkyl (meth)acrylates, N-(hydroxyalkyl)(meth)acrylamides, hydroxyalkyl vinyl ethers, or hydroxyalkyl allyl ethers;

[0038] [Monomer unit having a (poly)alkyleneoxy group] Monomer units having a (poly)alkyleneoxy group can be introduced into resin (C) by polymerizing a monomer having a (poly)alkyleneoxy group. Examples of monomers having a (poly)alkyleneoxy group include polyethylene glycol allyl ether, polyethylene glycol polypropylene glycol allyl ether, polypropylene glycol allyl ether, methoxy(poly)ethylene glycol (meth)acrylate, ethoxy(poly)ethylene glycol (meth)acrylate, 2-ethylhexyl(poly)ethylene glycol acrylate, methoxy(poly)propylene glycol (meth)acrylate, ethoxy(poly)propylene glycol (meth)acrylate, and ethoxy(poly)ethylene(poly)propylene glycol (meth)acrylate. Among these, polyethylene glycol allyl ether, polyethylene glycol polypropylene glycol allyl ether, and polypropylene glycol allyl ether represented by the following formula (1) are preferred.

[0039] Formula (1) [ka]

[0040] (In formula (1), m is an integer of 0 or 1 or more, n is an integer of 0 or 1 or more, and m+n≧1. R1 represents a hydrogen atom or a methyl group. R2 represents an alkyl group or an aryl group having 1 to 30 carbon atoms, which may have a substituent. Furthermore, when m≧1, n≧1, and m+n≧2, the bonding order of the CH2CHO groups (ethyleneoxy groups) and the CH(CH3)CHO groups (propyleneoxy groups) may be random, alternating, or block.)

[0041] In formula (1), m is preferably 0 to 20. n is preferably 0 to 20. m+n is preferably 1 to 40. R1 is preferably a hydrogen atom or a methyl group. R2 is preferably a methyl group, ethyl group, propyl group, isopropyl group, butyl group, hexyl group, cyclohexyl group, decyl group, phenyl group, phenylcarboxy group, or phenol group.

[0042] The monomer units having a hydroxyl group or an alkyleneoxy group can be used alone or in combination of two or more kinds.

[0043] The content of the monomer having a hydrophobic group used in synthesizing the resin (C) is preferably 20 to 90 mass %, more preferably 25 to 80 mass %, and even more preferably 30 to 70 mass %, of all the monomers used in synthesizing the resin (C). By setting the content of the monomer having a hydrophobic group within the above range, the resin (C) becomes more easily adsorbed to the colorant (A), and the colorant becomes more easily dispersed to the primary particle level, thereby improving gloss.

[0044] The amount of the monomer having an acid group used in synthesizing the resin (C) is preferably 10 to 90 mass %, more preferably 20 to 80 mass %, and even more preferably 30 to 70 mass %, of the total monomers used in synthesizing the resin (C). By setting the content of the monomer having an acid group within the above range, viscosity stability is improved due to charge repulsion, which is preferable. Among these, a carboxyl group is preferable because viscosity stability is particularly improved due to charge repulsion.

[0045] The amount of the monomer having a hydrophilic group other than an acid group used in synthesizing resin (C) is preferably 1 to 50 mass %, more preferably 2 to 30 mass %, and even more preferably 3 to 20 mass %, of all the monomers used in synthesizing resin (C). By keeping the amount of the monomer having a hydrophilic group other than an acid group within the above range, the difference in polarity with the first ink containing resin (B) becomes large, and when the inks are applied as an ink set and the first ink and the second ink are adjacent to each other, bleeding between the inks is suppressed, which is preferable, resulting in improved image quality.

[0046] The monomers used in the synthesis of resin (B) and resin (C) and the amounts thereof may be the same or different.

[0047] As the polymerization method for the resin (B) and the resin (C), any of the conventionally known polymerization methods such as random polymerization, block polymerization, living radical polymerization, and alternating copolymerization can be used.

[0048] The acid value of resin (B) and resin (C) is preferably 1 to 400 mgKOH / g, more preferably 50 to 350 mgKOH / g, and even more preferably 100 to 250 mgKOH / g. By setting the acid value within the above range, sufficient dispersion stability can be obtained due to charge repulsion.

[0049] The number average molecular weight (Mn) of resin (B) and resin (C) is preferably 1,000 to 1,000,000, more preferably 2,000 to 50,000, and even more preferably 3,000 to 20,000. The polydispersity (Mw / Mn) obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn) is preferably 5.0 or less, more preferably 3.0 or less, even more preferably 2.0 or less, and most preferably 1.5 or less.

[0050] Resin (B) and resin (C) preferably have a melting point. The melting point is preferably less than 100°C, more preferably 90°C or less, and even more preferably 80°C or less. If the melting point is 100°C or more, dispersion in an aqueous medium may need to be carried out at a high temperature, which may result in rapid evaporation of water and make it difficult to prepare a dispersion.

[0051] The amount of resin (B) and resin (C) added is preferably 1 to 200 parts by mass, more preferably 10 to 100 parts by mass, per 100 parts by mass of colorant (A). Resin (B) and resin (C) may be sufficient to cover part or all of colorant (A) to the extent that the object of the present application can be achieved.

[0052] <Solvent (E)> The ink set of the present invention contains a solvent (E). Examples of the solvent (E) include water, a water-soluble solvent, and a water-insoluble solvent.

[0053] [water] The water may be ordinary tap water, but ion-exchanged water, distilled water, or purified water is preferred. The total amount of metal ions contained in the water is preferably 10 ppm or less, more preferably 1 ppm or less, and even more preferably 100 ppb or less. In particular, divalent metal ions such as calcium and magnesium react with two acid groups such as carboxyl groups in resin (B) and resin (C) to form unintended crosslinked structures, so it is preferable to suppress their presence as much as possible.

[0054] [Water-soluble solvent] The water-soluble solvent may be a water-soluble organic solvent that is miscible with water, such as monoalcohols, polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, ethylene carbonate, and other water-soluble solvents.

[0055] Examples of monoalcohols include methanol, ethanol, propanol, butanol, pentanol, and 3-methoxy-3-methylbutanol.

[0056] Examples of polyhydric alcohols include glycerin, ethylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5- Hexanediol, 1,6-hexanediol, 3-methyl-1,3-butanediol, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, petriol, 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1,2-diol, 2-ethyl-1,3-hexanediol; and the like.

[0057] Examples of polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monobutyl ether.

[0058] Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, tetraethylene glycol chlorophenyl ether, ethylene glycol monobenzyl ether, and ethylene glycol monoallyl ether.

[0059] Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, and γ-butyrolactone.

[0060] Examples of amides include formamide, N-methylformamide, and N,N-dimethylformamide.

[0061] Examples of amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine.

[0062] Examples of sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol.

[0063] [Water-insoluble solvent] Examples of water-insoluble solvents include solvents that are immiscible or almost immiscible with water, such as hexane, dichloromethane, chloroform, diethyl ether, ethyl acetate, butyl acetate, methyl ethyl ketone, toluene, xylene, and propylene glycol monomethyl ether acetate.

[0064] The solvent (E) can be used alone or in combination of two or more kinds.

[0065] <Other additives> The ink set of the present invention may contain other additives, such as acidic compounds, basic compounds, resin modifiers, binder resins other than resin (B), surfactants, antiseptics and antifungals, chelating agents, rust inhibitors, antioxidants, ultraviolet absorbers, oxygen absorbers, light stabilizers, and dye derivatives.

[0066] [Basic compounds] The basic compound is a compound capable of neutralizing acid groups such as carboxyl groups, sulfo groups, and phosphate groups contained in resin (B) and resin (C). The basic compound is not particularly limited as long as it is a compound capable of neutralizing the acid groups of resin (B) and resin (C). Examples of the basic compound include inorganic bases and organic bases. Examples of inorganic bases include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal salts of silicates such as sodium orthosilicate, sodium metasilicate, and sodium sesquisilicate; alkali metal salts of phosphoric acid such as trisodium phosphate; alkali metal salts of carbonates such as disodium carbonate, sodium bicarbonate, and dipotassium carbonate; alkali metal salts of boric acid such as sodium borate; and ammonia; Examples of the organic base include primary amines such as methylamine, ethylamine, and aniline; primary amino alcohols such as ethanolamine; Secondary amines such as dimethylamine, diethylamine, and dipropylamine; Secondary amino alcohols such as butylaminoethanol and diethanolamine; Tertiary amines such as trimethylamine, triethylamine, and triphenylamine; Examples of suitable tertiary amino alcohols include trimethanolamine, triethanolamine, tributanolamine, dimethylaminoethanol, diethylaminoethanol, dibutylaminoethanol, dimethylaminopropanol, dibutylaminopropanol, methoxypoly(oxyethylene / oxypropylene)-2-propylamine, N-methyldiethanolamine, N-ethyldiethanolamine, and N-pentyldibutanolamine. Among these, inorganic bases or tertiary amino alcohols are preferred. Specifically, sodium hydroxide, potassium hydroxide, dimethylaminoethanol, diethylaminoethanol, dibutylaminoethanol, N-methyldiethanolamine, N-butyldiethanolamine, and triethanolamine are preferred.

[0067] [Acidic compounds] Acidic compounds can be used to adjust the pH of the ink, and examples of acidic compounds include inorganic acids and organic acids. Examples of inorganic acids include hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, phosphonous acid, phosphinous acid, phosphine, and nitric acid. Examples of organic acids include formic acid, acetic acid, butyric acid, lactic acid, citric acid, oxalic acid, malic acid, and benzenesulfonic acid.

[0068] [Resin modifier (F)] In the ink set of the present invention, it is preferable that either or both of the resin (B) contained in the first ink and the resin (C) contained in the second ink are modified with a resin modifier (F). The resin modifier (F) is a compound having a functional group that can react with the functional group of the resin (B) or the resin (C). By adding such a compound, it reacts with the resin (B) or the resin (C) to change the polarity and modify it.

[0069] The functional group of the resin (B) or (C) capable of reacting with the functional group of the resin modifier (F) may be, for example, an acid group such as a carboxy group.

[0070] The resin modifier (F) may be any known compound, such as a compound having an epoxy group, an oxetanyl group, an isocyanate group, ammonia, an amino group, a quaternary ammonium salt, a thiol group, an aziridinyl group, a carbodiimide group, or an oxazoline group.

[0071] The number of functional groups capable of reacting with the functional groups of the resin (B) or the resin (C) contained in one molecule of the resin modifier (F) is preferably one or two or more. When the compound has only one reactive functional group, it is also called an end-capping agent. For example, by reacting the carboxyl group of resin (B) or (C) with an end-capping agent containing a hydrophobic group (such as an alkyl or aromatic group) and an epoxy group, the carboxyl group of resin (B) or (C) reacts with the epoxy group, reducing the number of moles of carboxyl groups. At the same time, by introducing a hydrophobic group (such as an alkyl or aromatic group), resin (B) or (C) can be modified to be hydrophobic. Similarly, by reacting a hydrophilic group with an end-capping agent containing an epoxy group, resin (B) or (C) can be modified to be hydrophilic. If the number of reactive functional groups is two or more, the compound is also called a crosslinker. For example, by reacting the carboxyl groups of resin (B) or resin (C) with a crosslinker containing two or more epoxy groups and hydrophobic groups such as alkyl or aromatic groups, the carboxyl groups of resin (B) or resin (C) react with the epoxy groups, reducing the number of moles of carboxyl groups. At the same time, by introducing hydrophobic groups such as alkyl or aromatic groups, resin (B) or resin (C) can be modified to be hydrophobic. Similarly, by reacting a crosslinker containing two or more epoxy groups with hydrophilic groups, resin (B) or resin (C) can be modified to be hydrophilic. Furthermore, when a crosslinker is used, some or all of the functional groups contained in one molecule of the crosslinker can react with two or more functional groups of resin (B) or resin (C), forming inter- or intramolecular crosslinks between resin (B) or resin (C) and forming a strong three-dimensional structure. A crosslinking agent is preferred as the resin modifier (F). Resin (B) or resin (C) is preferably modified to be hydrophobic. In particular, it is more preferred to use a crosslinking agent as the resin modifier (F) to modify resin (B) to be hydrophobic. By modifying resin (B) to be hydrophobic and crosslinking it, resin (B) is more strongly adsorbed to colorant (A), not only improving the gloss when made into a colorant dispersion, ink, or ink set, but also increasing the polarity difference between resin (B) and resin (C), thereby further improving the bleeding suppression effect when printed on various substrates. The weight average molecular weight or formula weight of the resin modifier (F) is preferably from 100 to 2,000, more preferably from 120 to 1,500, and even more preferably from 150 to 1,000.

[0072] The amount of resin modifier added is preferably 0.1 to 1.5 equivalents, more preferably 0.4 to 1.2 equivalents, of the functional groups in the resin relative to the number of moles of functional groups in the resin. By adding the resin modifier in the above range, part or all of the resin adsorbed on the surface of the colorant particles is modified. Furthermore, using a crosslinking agent is preferable because it results in coating with a resin that forms a strong three-dimensional structure.

[0073] Examples of the resin modifier (F) include compounds having one epoxy group, such as trimethylolpropane monoglycidyl ether, 2-ethylhexyl glycidyl ether, p-tert-butylphenyl glycidyl ether, lauryl alcohol (EO)15 glycidyl ether, phenyl glycidyl ether, phenol (EO)5 glycidyl ether, dibromophenyl glycidyl ether, C12-C13 mixed alcohol glycidyl ether, and N-glycidylphthalimide; Compounds having two or more epoxy groups, such as polyglycidyl ethers such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin triglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, diglycidyl orthophthalate, and hydrogenated bisphenol A diglycidyl ether; Compounds having an oxetanyl group, such as 4,4'-(3-ethyloxetan-3-ylmethyloxymethyl)biphenyl (OXBP), 3-ethyl-3-hydroxymethyloxetane (EHO), 1,4-bis[{(3-ethyl-3-oxetanyl)methoxy}methyl]benzene (XDO), di[1-ethyl(3-oxetanyl)]methyl ether (DOX), di[1-ethyl(3-oxetanyl)]methyl ether (DOE), 1,6-bis[(3-ethyl-3-oxetanyl)methoxy]hexane (HDB), 9,9-bis[2-methyl-4-{2-(3-oxetanyl)}butoxyphenyl]fluorene, and 9,9-bis[4-[2-{2-(3-oxetanyl)}butoxy]ethoxyphenyl]fluorene; Organic polyisocyanates or isocyanate group-terminated prepolymers, organic polyisocyanates include, for example, aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate; aromatic diisocyanates such as tolylene-2,4-diisocyanate and phenylene diisocyanate; alicyclic diisocyanates; aromatic triisocyanates; and other compounds having a (blocked) isocyanate group, or urethane-modified products thereof; Diamines such as hydrazides, carbodihydrazides, thiocarbohydrazides, and oxalyldihydrazides; Ethylenediamine, 1,3-propanediamine, 1,2-propanediamine, 1,4-butanediamine, 1,6-hexamethylenediamine, 1,8-octamethylenediamine, 1,11-diaminoundecane, 1,12-diaminododecane, 2-butyl-2-ethyl-1,5-pentanediamine, 1,5-diamino-2-methylpentane, 2,2-dimethyl-1,3-propanediamine, 2,4,4-trimethyl-1,6-diaminohexane, laurylpropylenediamine, ethylene glycol bis(2-aminoethyl) ether , 1,4-butanediol bis(3-aminopropyl) ether, 1,13-diamino-4,7,10-trioxatridecane, polyoxypropylenediamine, methanetriamine, 1,2,3-propanetriamine, 1,8-diamino-4-aminomethyloctane, 3-(2-aminoethyl)pentane-1,5-diamine, 1,4,7-triaminocyclononane-1,4,7-triide, butane-1,1,4,4-tetraamine, 2,4-dimethyl-4-ethylamino-2,3,5-triaminohexane, 2,3-bis(diamino (methyl)butane-1,1,4,4-tetraamine, 1,2-bis(methylamino)ethane, 2,5-diamino-2,5-dimethylhexane, butane-1,1,4-trimethylamine, butane-1,1,4,4-tetramethylamine, 1,2-bis(dimethylamino)ethane, butane-1,1,4-tridimethylamine, butane-1,1,4,4-tetradimethylamine, hexamethylenetetramine, diethylenetriamine, dipropylenetriamine, bishexamethylenetriamine, triethylenetetraamine, adipic acid dihydriodide alkylenediamines such as azide, succinic acid dihydrazide, sebacic acid dihydrazide, eicosanedioic acid dihydrazide, valine dihydrazide, tetraethylenepentamine, 3,3'-diamino-N-methyldipropylamine, tris(2-aminoethyl)amine, tris(4-aminoethyl)amine, 3,3'-diamino-N-methyldipropylamine, tris(2-aminoethyl)amine, tris(4-aminoethyl)amine, 1-methylamino-2-dimethylaminoethane, linear polyethyleneimine, branched polyethyleneimine, etc.; Alicyclic diamines such as 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.02,6]decane (TCD diamine), isopropyl-2,4-diaminocyclohexane, isopropyl-2,6-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), adamantane-1,3-diamine, cyclohexane-1,3,5-triamine, 2,3,5-triaminobicyclo[2.2.1]heptane, piperazine, 2,5-dimethylpiperazine, and N-cyclohexyl-1,3-propanediamine; aromatic ring diamines such as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,4-toluenediamine, 2,6-toluenediamine, 2,2'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, xylylenediamine, tris(4-aminophenyl)methane, 1,2,4-benzenetriamine, melamine, benzene-1,2,4,5-tetraamine, pyrimidine-2,4,5,6-tetraamine, 3,3'-diaminobenzidine, tetraaminophthalocyanine, and isophthalic acid dihydrazide; Compounds having an amino group or a quaternary ammonium salt, such as butane-1,4-bisammonium chloride; Compounds having a thiol group, such as methanethiol, ethanethiol, and thiophenol; compounds having an aziridinyl group, such as N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxite), N,N'-toluene-2,4-bis(1-aziridinecarboxite), bisisophthaloyl-1-(2-methylaziridine), tri-1-aziridinylphosphine oxide, N,N'-hexamethylene-1,6-bis(1-aziridinecarboxite), 2,2'-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate], trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethane tri-β-aziridinylpropionate, tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, and 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane; a compound having a carbodiimide group, such as a high molecular weight polycarbodiimide produced by subjecting a diisocyanate compound to a decarboxylation condensation reaction in the presence of a carbodiimide catalyst; Examples of compounds having an oxazoline group include compounds in which two or more, preferably two to three, oxazoline groups are bonded to an aliphatic group or an aromatic group; bisoxazoline compounds such as 2,2-bis(2-oxazoline), 1,3-phenylenebisoxazoline, and 1,3-benzobisoxazoline; and compounds containing a terminal oxazoline group obtained by reacting such compounds with a polybasic carboxylic acid.

[0074] Among these, compounds having two or more epoxy groups are preferred, and examples thereof include trimethylolpropane monoglycidyl ether, 2-ethylhexyl glycidyl ether, p-tert-butylphenyl glycidyl ether, lauryl alcohol (EO)15 glycidyl ether, phenyl glycidyl ether, phenol (EO)5 glycidyl ether, dibromophenyl glycidyl ether, C12-C13 mixed alcohol glycidyl ether, N-glycidyl phthalimide, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, trimethylolpropane diglycidyl ether, and trimethylolpropane triglycidyl ether. Glycidyl ether, trimethylolpropane polyglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, diglycidyl orthophthalate, sorbitol polyglycidyl ether, resorcinol diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether are preferred, and trimethylolpropane monoglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether, ethylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether are more preferred. These can be used alone or in combination of two or more. From the viewpoint of treatment efficiency, it is preferable that the resin modifier (F) is moderately soluble in water. Commercially available products include Denacol EX321, EX321L, EX810, EX811, EX850, and EX850L manufactured by Nagase ChemteX Corporation, and Adeka Glycirol ED-505 manufactured by ADEKA Corporation.

[0075] The resin modifier (F) can be used alone or in combination of two or more kinds.

[0076] [Binder resin] Examples of binder resins include acrylic resins, olefin resins, ester resins, ether resins, urethane resins, and urea resins. In terms of solubility in water, binder resins include water-soluble resins and water-insoluble resins. Water-insoluble resins include emulsions and resin particles.

[0077] The content of the binder resin is preferably from 2 to 30% by mass, more preferably from 3 to 20% by mass, based on 100% by mass of the nonvolatile content of the composition.

[0078] [Sugars] Various conventionally known sugars can be used as the sugar. Because sugars have polar groups, they can be adsorbed to the surface of the colorant and suppress aggregation of the colorant. In addition, in the case of polysaccharides, in addition to the effect of the polar groups, the steric hindrance effect of the three-dimensional structure can suppress aggregation of the colorant.

[0079] Examples of sugars include monosaccharides such as glyceryl aldehyde, threose, xylose, glucose, mannose, and galactose; disaccharides such as sucrose, lactulose, lactose, maltose, trehalose, cellobiose, etc.; Examples of polysaccharides include amylose, amylopectin, glycogen, cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methylhydroxyethyl cellulose, methylhydroxypropyl cellulose, cellulose nanofibers, cellulose nanocrystals, cellulose nanowhiskers, TEMPO-oxidized cellulose nanofibers, chitin, carrageenan, alginic acid, heparin, hyaluronic acid, pectin, xanthan gum, tamarind seed gum, locust bean gum, gellan gum, guar gum, gum arabic, agar, karaya gum, succinoglycan, and dextrin; and the like.

[0080] Examples of commercially available products include Sunrose APP-84, A02SH, A01MC, F04HC, A20SH, SN30C, F120MC, F350HC, and F1000LC (carboxymethyl cellulose) manufactured by Nippon Paper Industries Co., Ltd.; Heatgel Kyoku, Ultra, Ultra CL, Hard, and Hard SL (methyl cellulose) manufactured by Unitec Foods Co., Ltd.; Ethocel STD and MED (ethyl cellulose) manufactured by Nisshin Chemical Industry Co., Ltd.; Heatgel Soft, Soft L, Soft SL, Soft, Soft L, and Soft MH (methylhydroxypropyl cellulose) manufactured by Unitec Foods Co., Ltd.; and AL-15, AL-15F, A-15F, AH-15F, AV-15F, AW-15F, AX-15, SW-25F, SZ-25F, CF-G, CF-V, CF-W, CF-X, and CF-Y (hydroxyethyl cellulose) manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0081] [Surfactants] Examples of the surfactant include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants.

[0082] [Anionic surfactants] Anionic surfactants include fatty acid salts, alkyl sulfate ester salts, alkylaryl sulfonates, alkylnaphthalenesulfonates, dialkylsulfonates, dialkylsulfosuccinates, alkyldiaryletherdisulfonates, alkylphosphates, polyoxyethylene alkylether sulfates, polyoxyethylene alkylarylether sulfates, polyoxyethylene alkylether acetates, alkylbenzenesulfonates (e.g., NH4, Na, Ca, etc.), alkyldiphenyletherdisulfonates (e.g., NH4, Na, Ca, etc.), naphthalenesulfonic acid formalin condensates and their salts, dialkylsuccinate sulfonate Na salts, polyoxyethylene alkylphosphate ester salts, glycerol borate fatty acid esters, polyoxyethylene alkyl ... naphthalenesulfonic acid formalin condensates and their salts, dialkylsuccinate sulfonate Na salts, polyoxyethylene alkylphosphate ester salts, glycerol borate fatty acid esters, polyoxyethylene alkyl ether acetates, alkylbenzenesulfonates (e.g., NH4, Na, Ca, etc.), naphthalenesulfonic acid formalin condensates and their salts, dialkylsuccinate sulfonate Na salts, polyoxyethylene alkylphosphate ester salts, glycerol borate fatty acid esters, polyoxyethylene alkyl ether acetates, alkylbenzenesulfonates (e.g., NH4, Na, Ca, etc.), naphthalenesulfonic acid formalin condensates and their salt Examples of suitable fluorine-containing surfactants include ethylene glycerol fatty acid esters, polyoxyethylene polycyclic phenyl ether sulfates (e.g., NH4, Na), laurates, polyoxyethylene alkyl ether sulfates, oleates, perfluoroalkyl sulfonic acids, perfluoroalkyl sulfonates, perfluoroalkyl carboxylic acids, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, salts of perfluoroalkyl phosphates, polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chains, sulfate salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chains, and salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chains. Examples of counter ions in the salts of these fluorine-containing surfactants include Li, Na, K, NH4, NH3CH2CH2OH, NH2(CH2CH2OH)2, and NH(CH2CH2OH)3.

[0083] [Cationic surfactant] Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, and alkylimidazolium salts.

[0084] [Nonionic surfactant] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyalkylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethyleneoxypropylene block copolymers, polyoxyethylene polycyclic phenyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene fatty acid esters, acetylene glycol, polyoxyethylene alkylamines, fluorine-based, silicone-based nonionic surfactants, etc. In particular, examples of acetylene glycol-based surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyn-3-ol. Commercially available acetylene glycol surfactants include, for example, Surfynol 104, 82, 465, 485, TG, and DF110D manufactured by Air Products (USA).

[0085] Fluorine-based surfactants can also be used, such as Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by AGC), Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, and FC-431 (all manufactured by Sumitomo 3M), Megafac F-470, F1405, Examples include F-474 (all manufactured by DIC), ZonylTBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont), FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos), and PF-151N (manufactured by Omnova).

[0086] [Zwitterionic surfactants] Examples of the amphoteric surfactant include alkyl betaine, alkyl amine oxide, phosphatidyl choline, etc. Examples include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, lauryl dimethyl amine oxide, myristyl dimethyl amine oxide, stearyl dimethyl amine oxide, dihydroxyethyl lauryl amine oxide, polyoxyethylene coconut oil alkyl dimethyl amine oxide, coconut oil alkyl betaine, dimethyl lauryl betaine, etc.

[0087] [Preservative and fungicide] Examples of antiseptic and antifungal agents include sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, methylisothiazolinone, benzisothiazolinone, and octylisothiazolinone.

[0088] [Chelating agent] Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate.

[0089] [Rust inhibitor] Examples of the rust inhibitor include acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and benzotriazole.

[0090] [Antioxidants] Examples of the antioxidant include phenol-based antioxidants (including hindered phenol-based antioxidants), amine-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. Examples of phenolic antioxidants include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,2-methylenebis(4-methyl-6-tert-butylphenol), 2,2-methylenebis(4-ethyl-6-tert-butylphenol), 4,4-butylidenebis(3-methyl-6-tert-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3- tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraixaspiro[5,5]undecane, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, and the like. Examples of amine antioxidants include phenyl-β-naphthylamine, α-naphthylamine, N,N-di-sec-butyl-p-phenylenediamine, phenothiazine, N,N-diphenyl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol, butylhydroxyanisole, 2,2-methylenebis(4-methyl-6-tert-butylphenol), 4,4-butylidenebis(3-methyl-6-tert-butylphenol), 4,4-thiobis(3-methyl-6-tert-butylphenol), tetrakis[methylene-3(3,5-di-tert-butyl-4-dihydroxyphenyl)propionate]methane, and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane. Examples of sulfur-based antioxidants include dilauryl 3,3-thiodipropionate, distearyl thiodipropionate, laurylstearyl thiodipropionate, dimyristyl-3,3-thiodipropionate, distearyl-β,β-thiodipropionate, 2-mercaptobenzimidazole, and dilauryl sulfide. Examples of the phosphorus-based antioxidant include triphenyl phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl trithiophosphite, and trinonylphenyl phosphite.

[0091] [UV absorber] Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and nickel complex salt-based ultraviolet absorbers. Examples of benzophenone-based ultraviolet absorbers include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2,2,4,4-tetrahydroxybenzophenone. Examples of benzotriazole-based ultraviolet absorbers include 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, and 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole. Examples of salicylate-based ultraviolet absorbers include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate. Examples of cyanoacrylate ultraviolet absorbers include ethyl-2-cyano-3,3'-diphenylacrylate, methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate, and butyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate. Examples of nickel complex salt-based ultraviolet absorbers include nickel bis(octylphenyl) sulfide, 2,2-thiobis(4-tert-octylferrate)-n-butylamine nickel(II), 2,2-thiobis(4-tert-octylferrate)-2-ethylhexylamine nickel(II), and 2,2-thiobis(4-tert-octylferrate)triethanolamine nickel(II).

[0092] [Dye derivatives] If necessary, a dye derivative may be added to the ink used in the present invention.

[0093] The dye derivative is a compound having an acidic group, a basic group, a neutral group, etc. in an organic dye residue. Examples of the dye derivative include compounds having an acidic substituent such as a sulfo group, a carboxy group, or a phosphate group, and amine salts thereof, compounds having a basic substituent such as a sulfonamide group or a terminal tertiary amino group, and compounds having a neutral substituent such as a phenyl group or a phthalimidoalkyl group. Examples of organic pigments include diketopyrrolopyrrole pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thiazine indigo pigments, triazine pigments, benzimidazolone pigments, indole pigments such as benzoisoindole, isoindoline pigments, isoindolinone pigments, quinophthalone pigments, naphthol pigments, threne pigments, metal complex pigments, and azo pigments such as azo, disazo, and polyazo.

[0094] The other additives may be used alone or in combination of two or more.

[0095] <Ink manufacturing> The method for producing the ink of the present invention will be explained using the first ink as an example. In the case of the second ink, resin (B) can be read as resin (C). Step I: A step of coating the surface of particles containing a colorant (A) with a resin (B) Step II: Adding solvent (E) and mixing / stirring

[0096] [Process I] As the step of coating the surface of the particles containing the colorant (A) with the resin (B), a conventionally known manufacturing method can be used, but among them, the salt milling method, which can firmly coat the resin (B) with the colorant (A), is preferred.

[0097] [Salt milling method] The salt milling method preferably comprises the following steps: Step I-1: A step of adding at least a water-soluble inorganic salt and a water-soluble organic solvent to a colorant (A) and a resin (B) and grinding and kneading them. Step I-2: Step of removing water-soluble inorganic salts and water-soluble organic solvents

[0098] The above-described manufacturing method is particularly effective when the colorant is an organic pigment.

[0099] First, it is preferable to carry out a step (salt milling treatment) of mixing the colorant (A), the resin (B), the water-soluble inorganic salt, and the water-soluble organic solvent in a kneader (step I-1), and then a step (washing treatment) of removing the water-soluble inorganic salt and the water-soluble organic solvent by washing (step I-2).

[0100] Salt milling is a process in which a mixture of a pigment, a water-soluble inorganic salt, and a water-soluble organic solvent is mechanically kneaded under heating using a batch or continuous mixer, such as a kneader, trimix, two-roll mill, three-roll mill, ball mill, attritor, sand mill, or planetary mixer, followed by rinsing with water to remove the water-soluble inorganic salt and water-soluble organic solvent. The water-soluble inorganic salt acts as a crushing aid, and the water-soluble organic solvent acts as a particle growth agent. During salt milling, the high hardness of the inorganic salt is utilized to crush the primary particles of the pigment. Furthermore, the primary particles grow upon contact with the water-soluble organic solvent. By optimizing the conditions for salt milling, this repeated crushing and growth process can be achieved, resulting in pigments with extremely fine primary particle diameters, a narrow distribution, and a sharp particle size distribution. Furthermore, the repeated uniform crushing and growth from all directions of the primary particles results in near-spherical primary particles, rather than flattened particles.

[0101] The kneading temperature during salt milling is preferably −10° C. to 300° C., more preferably 30° C. to 90° C. By carrying out salt milling at an appropriate temperature, the primary particles of the colorant (A) are made finer, and the resin (B) can coat the colorant particles.

[0102] The kneading time during salt milling is preferably 0.1 to 100 hours, more preferably 3 to 24 hours. By performing salt milling for an appropriate kneading time, the primary particles of the pigment are refined and the resin (B) can coat the colorant (A) particles. The instantaneous power, which represents the load applied during kneading, can be set as desired by adjusting the kneading speed of the kneader and the viscosity of the mixture of the colorant (A), water-soluble inorganic salt, and water-soluble organic solvent.

[0103] [Water-soluble inorganic salts] Examples of water-soluble inorganic salts include sodium chloride, barium chloride, potassium chloride, and sodium sulfate. Sodium chloride (table salt) is preferred from the standpoint of cost. The amount of water-soluble inorganic salt (X) used is preferably 50 to 2,000 parts by mass, and more preferably 300 to 1,000 parts by mass, per 100 parts by mass of pigment, from the standpoints of both treatment efficiency and production efficiency. The particle size of the water-soluble inorganic salt is preferably 0.001 to 100 μm, and more preferably 0.1 to 10 μm. Note that industrially used sodium chloride is sometimes produced from natural products such as seawater, and may therefore contain approximately 0.01 to 30% by mass of impurities such as potassium chloride, calcium chloride, magnesium chloride, calcium sulfate, and magnesium sulfate.

[0104] [Water-soluble organic solvent] The water-soluble organic solvent is preferably a polyhydric alcohol as described above. The amount of the water-soluble organic solvent used is preferably 5 to 1,000 parts by mass, more preferably 50 to 500 parts by mass, per 100 parts by mass of the pigment. By appropriately selecting the amount of the water-soluble organic solvent used, the viscosity of the kneaded product can be adjusted to a level suitable for salt milling.

[0105] The washing process involves removing the mixture containing the colorant (A), resin (B), water-soluble inorganic salt, and water-soluble organic solvent from the kneader, adding a solvent, and stirring to obtain a suspension. The type of solvent added is not particularly limited as long as it can dissolve the water-soluble inorganic salt and the water-soluble organic solvent; however, tap water, an aqueous acid solution such as hydrochloric acid, or ion-exchanged water is preferred. The amount of solvent added is not particularly limited, as long as it is sufficient to obtain a suspension. For example, a 10 to 10,000-fold increase in mass of solvent is added, followed by mixing and stirring. Heating may be performed as necessary. The mixing and stirring conditions are not particularly limited, but a temperature of 5 to 100°C is preferred. The filtrate is then removed by filtration or other procedures to remove the water-soluble inorganic salt and water-soluble organic solvent used in the kneader, yielding a pigment composition containing the colorant (A) and resin (B).

[0106] After the washing treatment, a step of removing the solvent may be carried out. A suitable method is, for example, a method of carrying out a drying treatment. Drying conditions include, for example, a method of drying under normal pressure at a temperature in the range of 80 to 120°C for about 12 to 48 hours, and a method of drying under reduced pressure at a temperature in the range of -180 to 80°C for about 12 to 60 hours. The drying treatment is not particularly limited, but may also include a method using a spray dryer. A pulverization treatment may be carried out simultaneously with or after the drying treatment.

[0107] The average primary particle size of the colorant (A) is preferably approximately 10 nm to 10,000 nm before salt milling, and approximately 5 nm to 200 nm after salt milling. It is preferable that the average primary particle size of the pigment before salt milling is greater than the average primary particle size of the pigment after salt milling. A smaller average primary particle size is preferable because it improves coloring power and transparency. The average primary particle size can be determined by arithmetically averaging the major axes of 100 primary particles extracted from multiple photographs taken with a transmission electron microscope at a magnification of 10,000x. The aspect ratio, calculated by dividing the major axis by the minor axis of the primary particles, is preferably 1.0 to 5.0, more preferably 1.0 to 3.0. When used as an inkjet ink, the average primary particle size after salt milling is preferably 100 nm or less, and more preferably 60 nm or less.

[0108] [Process II] Next, a solvent (E) and, optionally, a basic compound are added to the washed pigment composition, and the mixture is mixed while heating or cooling as necessary (Step II). Conventional mixing methods can be used, including, for example, a high-speed mixer, a homogenizer, a high-pressure homogenizer, a Silverson mixer, a planetary mixer, a Trimix, a kneader, an extruder, a horizontal sand mill, a vertical sand mill and / or an annular bead mill, a paint shaker, a ball mill, a disperser equipped with an ultrasonic oscillator, a high-pressure disperser, a counter-impingement type disperser, an oblique-impingement type disperser, a batch-type rotor stator, an in-line rotor stator, a two-roll mill, and a three-roll mill. These steps break down pigment particle agglomerates to the primary particle level, allowing the preparation of an aqueous pigment dispersion.

[0109] Specific examples include the Microfluidizer (interaction chamber: Z type, Y type) manufactured by Powrex Corporation, the Starburst (chamber shape: oblique collision chamber, ball collision chamber, separation chamber, single nozzle chamber, slit chamber, circulating cooling chamber, multi-liquid injection reaction chamber) manufactured by Sugino Machine, the Starmill LMZ (bead mill) manufactured by Ashizawa Finetech, the Picomill manufactured by Asada Iron Works, an in-line high shear mixer (rotor stator) manufactured by Silverson, and a batch mixer (rotor stator) manufactured by Silverson, and can be selected appropriately depending on the desired physical properties.

[0110] Step II may be carried out using a combination of multiple devices. Using multiple devices is preferred because it reduces the number of coarse particles and allows for the production of ink with a sharper particle size distribution. For example, the following combinations are preferred: Mixing is performed using a Silverson in-line high shear mixer (rotor-stator), followed by further mixing using a Sugino Machine Starburst (oblique impingement chamber). Mixing using a Silverson batch mixer (rotor-stator) and further mixing using a Sugino Machine Starburst (oblique impingement chamber), A method of mixing using Ashizawa Finetech's Star Mill LMZ (bead mill) and then further mixing using Sugino Machine's Star Burst (oblique collision chamber). A method of mixing using a Starburst (oblique collision chamber) manufactured by Sugino Machine Co., Ltd., followed by further mixing using a Starmill LMZ (bead mill) manufactured by Ashizawa Finetech Co., Ltd.

[0111] When the resin (B) or the resin (C) is modified with a resin modifier, it is preferable to further carry out the following step III.

[0112] [Step III: Step of modifying resin with resin modifier] Step III is a step of adding a resin modifier to the mixture obtained in Step II to modify the resin, and is preferably carried out when producing the first ink. The resin modifier is preferably added with stirring. The resin modifier may be added at a temperature equal to or higher than the reaction temperature of the resin and the resin modifier, or at a temperature lower than the reaction temperature. When the resin modifier is added at a temperature lower than the reaction temperature, it is preferable to subsequently raise the temperature to a temperature higher than the reaction temperature. The resin modifier may be added all at once, may be added in 2 to 100 divided portions, or may be added intermittently. When the resin and the resin modifier are reacted, the pH of the mixture may fluctuate, so the pH may be adjusted by adding the above-mentioned basic compound or acidic compound. Step II may be performed again before, during, or after the reaction between the resin and resin modifier after mixing. In this case, it is preferable to use some or all of the same equipment as used in Step II. For example, if Step II uses an Ashizawa Finetech Star Mill LMZ (bead mill) and a Sugino Machine Star Burst (oblique impingement chamber), the resin and resin modifier may be stirred and mixed using the Ashizawa Finetech Star Mill LMZ (bead mill) before, during, or after the reaction between the resin and resin modifier after mixing. Alternatively, the resin and resin may be stirred and mixed using both the Ashizawa Finetech Star Mill LMZ (bead mill) and the Sugino Machine Star Burst (oblique impingement chamber).

[0113] [Post-processing process] If pH adjustment is necessary after mixing and stirring, the aforementioned acidic or basic compounds can be added to adjust the pH to the desired level. Specific examples of acidic compounds include inorganic acids such as phosphoric acid, hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as acetic acid and citric acid. Specific examples of basic compounds include inorganic bases such as sodium hydroxide and potassium hydroxide, and organic bases such as dimethylaminoethanol, diethylaminoethanol, dibutylaminopropanol, N-methyldiethanolamine, and triethanolamine. A solvent (E) may be added to adjust the nonvolatile content. Other additives such as those listed above may also be added to improve quality.

[0114] The pH of the ink after pH adjustment is preferably 7 to 10, and more preferably 7.1 to 9.5.

[0115] The resulting ink is preferably subjected to filtration, centrifugation, or magnetic filter removal to remove magnetic contaminants, and removal of impurity ions using cation exchange resins, anion exchange resins, chelating agents, or the like. Filtration or centrifugation can remove coarse particles, magnetic contaminants are removed using magnetic filters, and impurity ions such as calcium ions and magnesium ions are removed using ion exchange resins, resulting in improved ejection properties when the ink is made into an inkjet ink. Any conventionally known method can be used for removing magnetic contaminants using filtration, centrifugation, or magnetic filters, and for removing impurity ions using ion exchange resins, but for example, membrane filters, depth filters, ultrafiltration filters, and the like can be used for filtration. The filter mesh size is preferably 0.1 μm to 10 μm. For centrifugation, a cylindrical centrifuge, a basket centrifuge, or the like can be used. Examples of magnetic filters that can be used include the high gradient magnetic separator CS-X manufactured by Nippon Magnetics Co., Ltd., the mag catch filters MGCF-100 and MGCF-125 manufactured by Maeda Shell Services Co., Ltd., and the high-efficiency mag filter (1.0T to 1.35T) and high-magnetic force mag filter (1.7T) manufactured by Eishin Co., Ltd. Impurity ions can be removed by methods such as those described in Japanese Patent Application Laid-Open Nos. 2002-179961 and 2003-277672.

[0116] The volume average particle diameter D50 of the colorant (A) contained in the ink is preferably 5 nm to 200 nm. This range is preferable because the colorant (A) in the ink has less aggregation and is dispersed to the primary particle level, improving coloring power and transparency. The volume average particle diameter D50 of the colorant (A) in the ink is determined from the volume-based particle size distribution measured using an FPAR-1000 manufactured by Otsuka Electronics Co., Ltd. For inkjet inks, the volume average particle diameter D50 is preferably 10 to 150 nm, more preferably 30 to 90 nm.

[0117] The average circularity of the particles containing colorant (A) in the resulting ink is preferably about 0.60 to 1.00. A higher average circularity value results in a particle shape closer to a perfect sphere, which is preferable because when the ink is made, the primary particles of the colorant tend to come into point contact with each other, reducing the contact area and thereby reducing the viscosity. The average circularity can be determined by calculating the perimeter and area of ​​100 primary particles of the colorant extracted from multiple photographs taken with a transmission electron microscope at 10,000x magnification, and then arithmetically averaging the circularities calculated using the following formula: Note that because the average circularity represents the shape of the pigment particles when viewed from above, the three-dimensional shape of the colorant particles was not directly observed; however, the pigment particles were facing in various directions at the time of measurement, and as mentioned above, in the salt milling method, the pigment particles are repeatedly crushed and grown uniformly from all directions, so that they do not become flattened, and primary particles that are close to perfect spheres are obtained. Therefore, the three-dimensional shape of the pigment particles can be approximately determined by taking the arithmetic average of 100 colorant particles. Circularity = 4π x (area) ÷ (perimeter)^2

[0118] In addition to the above-mentioned manufacturing method, the ink may be manufactured by any of the following methods as long as they can solve the problems of the present application: a dispersion method using a bead disperser or the like as described in paragraphs

[0034] to

[0048] of the specification of JP 2018-028080 A; a phase inversion emulsification method in which a colorant is dispersed in a mixed solution of water and an organic solvent and then the organic solvent is distilled off as described in paragraphs

[0025] to

[0029] of the specification of JP 2020-143201 A;

[0119] The colorant (A) can be coated with the resin (B) by the kneading method described in 1. above, which does not use a water-soluble inorganic salt.

[0119] <Ink set> The ink set of the present invention is an ink set having a first ink and a second ink. The first ink and the second ink each contain a different type of colorant (A). Therefore, the ink set of the present invention can be an ink set containing inks of two or more colors. Specifically, a three-color ink set including cyan, magenta, and yellow inks is included. Other examples include a four-color process color ink set that adds black ink, and an ink set that expands the color reproduction range by adding special color inks such as red, orange, and green inks. Furthermore, examples include ink sets that include a white ink as an undercoat layer, or a pretreatment liquid containing a component that aggregates the ink, such as calcium ions, an acidic compound, or a polymer flocculant.

[0120] <Ink set applications> Examples of the ink set of the present invention include letterpress printing inks used in letterpress printing, flexographic printing, etc., intaglio printing inks used in gravure printing, etc., lithographic printing inks used in offset printing, etc., stencil printing inks used in screen printing, etc., inkjet printing, and on-demand printing inks used in electrostatic charge developing toner printing, etc. Other applications include paints for building materials and automobiles, inks for writing instruments, color filters, solid-state imaging devices, sensors such as LiDAR, etc. Among these, inkjet inks used in inkjet printing are preferred.

[0121] [Inkjet ink] Inkjet inks preferably contain water-soluble solvents that are miscible with water, such as polyhydric alcohols and polyhydric alcohol alkyl ethers. These solvents penetrate substrates very quickly, even into low-absorbency substrates such as coated paper and art paper. This allows for fast drying during printing, enabling accurate printing. Furthermore, due to their high boiling points, they function adequately as wetting agents.

[0122] The water-soluble solvent may be any of the solvents already described above. Among these, polyhydric alcohols or polyhydric alcohol alkyl ethers are preferred.

[0123] The water-soluble solvents can be used alone or in combination of two or more kinds.

[0124] The content of the water-soluble solvent in the inkjet ink is preferably 3 to 60% by mass, more preferably 3 to 50% by mass, and the total content of the water-soluble solvent and water in the inkjet ink is preferably 10 to 95% by mass, more preferably 30 to 80% by mass.

[0125] The ink-jet ink of the present invention may contain other additives such as the binder resin described above.

[0126] It is preferable to remove impurity ions from inkjet ink by filtering, centrifuging, magnetically separating using a magnetic filter, or using cation exchange resin, anion exchange resin, chelating agent, etc. This improves the ejection properties from the inkjet printer. The materials already explained can be used for filtering, centrifuging, magnetic filtering, cation exchange resin, anion exchange resin, chelating agent, etc.

[0127] Inkjet inks can be suitably used in various inkjet printers. Examples of ink ejection methods for inkjet printers include charge control types, continuous jet types such as spray types, piezo types, thermal types, and electrostatic suction types. Examples of printing methods for inkjet printers include a multi-pass method (serial head method) in which an inkjet head is moved back and forth from side to side to print on a substrate, and a single-pass method (line head method) in which an inkjet head is fixed and printed.

[0128] <Image formation> The image-formed product of the present invention has a substrate and a print layer formed from the ink set of the present invention. For example, when the inkjet ink set of the present invention is installed in various inkjet printers, it can be installed as a set with, for example, cyan ink, magenta ink, yellow ink, and black ink. By installing it together with a set of four inks known as process colors and adjusting the printing amount of each color, printed areas (images) of various hues can be formed on the substrate (printed material). Furthermore, by installing inks other than the process colors, such as red ink and green ink, as needed, printed areas (images) with higher color reproducibility can be formed. The pigment concentration, viscosity, dynamic viscoelasticity, surface tension, printing order, and evaporation rate of volatile components of each ink are design factors and can be adjusted appropriately depending on the desired characteristics. The thickness of the printed layer is preferably 0.01 μm to 1 cm. Furthermore, printing on the substrate may be performed by coating the substrate horizontally or vertically.

[0129] [Base material] The composition and ink of the present invention can be printed on various conventionally known hydrophilic and hydrophobic substrates. The substrates already exemplified can be used. The substrate surface may be smooth or may have irregularities, and may be flat or curved. The thickness of the substrate is preferably 0.01 mm to 1 cm. For substrates used for building materials, etc., the thickness is preferably 1 cm to 1 m. [Example]

[0130] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. Unless otherwise specified, "parts" means parts by mass, "%" means mass%, NV means non-volatile content, Mw means weight-average molecular weight, Mn means number-average molecular weight, and Tg means glass transition temperature.

[0131] The abbreviations and product names in the examples have the following meanings. MALAH: Maleic anhydride MAA: methacrylic acid MMA: methyl methacrylate 2-HEA: 2-hydroxyethyl acrylate St: styrene AS-6: Styrene macromer (number average molecular weight 6,000) manufactured by Toagosei Co., Ltd. PEMA: Phenoxyethyl methacrylate LA: Lauryl acrylate VI: Vinylimidazole Light Acrylate 130A: Methoxy polyethylene glycol acrylate manufactured by Kyoeisha Chemical Co., Ltd. Monomer 1: Formula (1), m = 6 to 14 (average 10), n = 0, R1 = H, R2 = methyl group Monomer 2: Formula (1), m = 0, n = 6 to 14 (average 10), R1 = methyl group, R2 = methyl group Monomer 3: Formula (1), m = 4 to 12 (average 8), n = 0 to 6 (average 2), R1 = H, R2 = methyl group Monomer 4: Formula (1), m = 10 to 20 (average 15), n = 0, R1 = methyl group, R2 = n-butyl group Monomer 5: Formula (1), m = 0, n = 10 to 20 (average 15), R1 = H, R2 = n-butyl group Monomer 6: Formula (1), m = 0 to 8 (average 3), n = 6 to 18 (average 12), R1 = methyl group, R2 = n-butyl group Monomer 7: Formula (1), m = 15 to 25 (average 20), n = 0, R1 = H, R2 = n-hexyl group Monomer 8: Formula (1), m = 0, n = 15 to 25 (average 20), R1 = methyl group, R2 = n-hexyl group Monomer 9: Formula (1), m = 5 to 15 (average 10), n = 5 to 10 (average 10), R1 = H, R2 = n-hexyl group

[0132] Formula (1) [ka]

[0133] Resin modifier: ADEKA ADEKA Glycirol ED-505 (a mixture of trimethylolpropane triglycidyl ether, trimethylolpropane diglycidyl ether, and trimethylolpropane monoglycidyl ether) MEK: Methyl ethyl ketone MeOH: Methanol IPA: Isopropyl alcohol Resin (B-1): NUCERA Ceramer 1608 (maleic anhydride-maleic acid monoisopropyl ester-olefin copolymer, acid value 160 mg KOH / g) Resin (B-2): Joncryl 611 manufactured by BASF (styrene-acrylic acid copolymer, acid value 53 mg KOH / g, Mw 8,100, Tg 50°C) Resin (B-3): BASF Joncryl 683 (styrene-acrylic acid copolymer, acid value 165 mg KOH / g, Mw 8,000, Tg 75°C) Resin (B-4): BASF Joncryl 690 (styrene-acrylic acid copolymer, acid value 240 mg KOH / g, Mw 16,500, Tg 84°C) Resin (B-5): XIRAN3000P (styrene-maleic anhydride copolymer, styrene:maleic anhydride = 75:25 (mass ratio), acid value 285 mg KOH / g, Mw 10,000, Tg 125°C) manufactured by Polyscope Polymers BV Resin (B-6): Cray Valley SMA3000H (styrene-maleic acid copolymer ammonium salt aqueous solution, acid value 265-305 mg KOH / g, Mw 9,500, Tg 125°C) Resin (B-7): Arakawa Chemical Industry Co., Ltd., Marquid No. 32 (maleic rosin resin, acid value 120-140 mg KOH / g, softening point 130-140°C) J-780: Joncryl 780 (polyacrylic emulsion, NV 48%) manufactured by BASF Japan W-5030: Mitsui Chemicals Takelac W-5030 (polyurethane emulsion, NV30%) W400S: Mitsui Chemicals Chemipearl W400S (olefin wax, NV40%) S-DF110D: Surfynol DF110D (acetylene surfactant) manufactured by Evonik Industries Proxel GXL: Lonza preservative (1,2-benzisothiazolin-3-one) PB15:3: CI Pigment Blue 15:3 (Ramafast Blue WP / L-143 manufactured by RAMDEV CHEMICAL INDUSTRIES) PY74: CI Pigment Yellow 74 (Sanyo Pigment Fast Yellow 7416) PY12: CI Pigment Yellow 12 (Toyocolor Lionol Yellow TCH1205) PY14: CI Pigment Yellow 14 (DIC SYMULER FAST Yellow 4400) PY138: CI Pigment Yellow 138 (BASF Paliotol Yellow L0960HD) PY155: CI Pigment Yellow 155 (LYSOPAC YELLOW 5513P manufactured by Cappelle Pigments NV) PY180: CI Pigment Yellow 180 (Novoperm Yellow P-HG manufactured by Clariant Chemicals) PR122: CI Pigment Red 122 (BASF Japan Cinquasia Pink K4410) PV19: CI Pigment Violet 19 (Clariant Chemicals Inkjet Magenta E5B02) PR122+PV19: Solid solution of CI Pigment Red 122 and CI Pigment Violet 19 (Ciba Japan Chromophthal Jet Magenta 2BC) PR31: CI Pigment Red 31 (Toshiki Red 31N, manufactured by Tokyo Color Materials Co., Ltd.) PR150: CI Pigment Red 150 (Toshiki Red 150TR manufactured by Tokyo Color Materials Co., Ltd.) PR150+PR31: A mixture of PR150 and PR31 (mixing ratio 75:25) (mass ratio) PR254: CI Pigment Red 254 (CINIC Chemicals Cinilex DPP Red SR2P) PG36: CI Pigment Green 36 (Toyocolor LIONOL GREEN 8390) PO34: CI Pigment Orange 34 (Clariant Chemicals Permanent Orange RL01-MX) PO43: CI Pigment Orange 43 (PV Fast Orange GRL manufactured by Clariant Chemicals) PBk7: CI Pigment Black 7 (Orion Engineered Carbons PRINTEX 85)

[0134] The physical properties were determined according to the following methods.

[0135] (Number average molecular weight (Mn), weight average molecular weight (Mw)) Measurements were performed using gel permeation chromatography (GPC) equipped with an RI detector. The instrument used was an HLC-8220GPC (Tosoh Corporation), with two separation columns connected in series, both packed with "TSK-GEL SUPER HZM-N" in series. The oven temperature was 40°C, and the eluent was a THF solution at a flow rate of 0.35 ml / min. The sample was dissolved in a solvent consisting of 1% of the above eluent, and 20 microliters was injected. The molecular weight is expressed in terms of polystyrene.

[0136] (acid number) The number of moles of acid groups contained in 1 g of resin was calculated from the monomer composition. The theoretical acid value (mgKOH / g) was calculated assuming that this number of moles of acid groups was equal to the number of moles of potassium hydroxide (molecular weight 56.1) required for neutralization. The theoretical value was calculated assuming that all maleic anhydride was hydrolyzed to maleic acid.

[0137] (NV measurement) NV was calculated from the loss on drying when 0.5 g of the sample was weighed out and placed in a 180°C dryer for 20 minutes.

[0138] Synthesis of resin (B-8) 100 parts of XIRAN3000P (manufactured by Polyscope Polymers BV), 200 parts of MEK, 15 parts of IPA, and 0.1 parts of diazabicycloundecene as a catalyst were added. The mixture was stirred at reflux for 6 hours while maintaining the temperature at 85°C, resulting in a reaction in which 96 mol% of the maleic anhydride was ring-opened to form a half ester with IPA. Subsequently, 20 parts of ion-exchanged water was added, and the remaining maleic anhydride was hydrolyzed to maleic acid. The resulting product was concentrated under reduced pressure to obtain Resin (B-8) (weight average molecular weight (Mw) 10,000, acid value 125 mgKOH / g).

[0139] Synthesis of resin (B-9) 100 parts of XIRAN3000P (manufactured by Polyscope Polymers BV), 200 parts of N,N-dimethylformamide, and 46 parts of laurylamine were added and stirred at 85°C for 6 hours to allow the reaction to proceed. 96 mol% of the maleic anhydride was ring-opened to form laurylamine and a half amide. 20 parts of ion-exchanged water was then added, and the remaining maleic anhydride was hydrolyzed to maleic acid. The resulting product was concentrated under reduced pressure to obtain Resin (B-9) (weight average molecular weight (Mw) 10,000, acid value 100 mgKOH / g).

[0140] Synthesis of resin (B-10) [First reaction] A reaction vessel equipped with a gas inlet tube, thermometer, condenser, dropping funnel, and stirrer was charged with 49 parts (50 mol%) of MALAH as a monomer mixture, 126 parts (50 mol%) of 1-octadecene as an α-olefin, 100 parts of MEK, and 0.5 parts of octyl thioglycolate as a chain transfer agent. After purging with nitrogen, the mixture was heated to 105°C with stirring. A mixture of 2.0 parts of dimethyl isobutyrate (Fujifilm Wako Pure Chemical Industries, Ltd., trade name: V-601) as a radical polymerization initiator and 5 parts of MEK was added dropwise over 1 hour. Subsequently, a mixture of 5 parts of V-601 and 12 parts of MEK was added dropwise over 6 hours with stirring at reflux at 85°C. The mixture was allowed to react for 1 hour while maintaining the temperature at 85°C, yielding a polymer having maleic anhydride as an acid anhydride group. [Second reaction] Next, 16 parts (50 mol%) of methanol and 0.1 parts of diazabicycloundecene as a catalyst were added, and the mixture was stirred under reflux for 6 hours while maintaining the temperature at 85°C to allow the reaction to proceed, resulting in ring-opening of the maleic anhydride and the formation of a half ester with methanol. The resulting product was concentrated under reduced pressure to obtain Resin (B-10) (number average molecular weight (Mn): 4,500, weight average molecular weight (Mw): 11,000, acid value: 147 mgKOH / g).

[0141] Synthesis of resins (B-11) to (B-18) Resins (B-11) to (B-18) were obtained in the same manner as for Resin (B-10), except that the monomer composition, number average molecular weight, and weight average molecular weight were changed as shown in Table 1. The molecular weight was adjusted appropriately by changing the amount of V-601 added. Furthermore, the resins that did not use maleic anhydride did not undergo the second reaction.

[0142] [Table 1]

[0143] Synthesis of resin (C-1) [First reaction] A reaction vessel equipped with a gas inlet tube, thermometer, condenser, dropping funnel, and stirrer was charged with 59 parts (60 mol%) of MALAH as a monomer mixture, 81 parts (36 mol%) of 1-hexadecene as an α-olefin, 21 parts (4 mol%) of Monomer 1, 100 parts of MEK, and 0.5 parts of octyl thioglycolate as a chain transfer agent. After nitrogen substitution, the mixture was heated to 105°C with stirring. A mixture of 2.0 parts of dimethyl isobutyrate (Fujifilm Wako Pure Chemical Industries, Ltd., trade name: V-601) as a radical polymerization initiator and 5 parts of MEK was added dropwise over 1 hour. Subsequently, a mixture of 5 parts of V-601 and 12 parts of MEK was added dropwise over 6 hours with stirring at 85°C. The mixture was allowed to react under reflux for 1 hour while maintaining the temperature at 85°C, yielding a polymer having maleic anhydride as an acid anhydride group. [Second reaction] Next, 19 parts (60 mol%) of methanol and 0.1 parts of diazabicycloundecene as a catalyst were added, and the mixture was stirred under reflux for 6 hours while maintaining the temperature at 85°C to allow the reaction to proceed, resulting in ring-opening of the maleic anhydride and formation of a half ester with methanol. The resulting product was concentrated under reduced pressure to obtain Resin (C-1) (number average molecular weight (Mn): 4,400, weight average molecular weight (Mw): 10,500, acid value: 188 mgKOH / g).

[0144] Synthesis of resins (C-2) to (C-17) Resins (C-2) to (C-17) were obtained in the same manner as for Resin (C-1), except that the monomer composition, number average molecular weight, and weight average molecular weight were changed as shown in Tables 2-1 and 2-2. The molecular weight was adjusted appropriately by changing the amount of V-601 added. In addition, the resins that did not use maleic anhydride did not undergo the second reaction.

[0145] [Table 2-1]

[0146] [Table 2-2]

[0147] <Preparation of Colorant Dispersion> [Manufacturing Example 1] Manufacture of colorant dispersion (1) 80 parts of PB15:3, 20 parts of resin (B-1) as nonvolatile matter, 450 parts of sodium chloride, and 180 parts of diethylene glycol were charged into a stainless steel 1-gallon kneader (manufactured by Inoue Seisakusho Co., Ltd.) and kneaded at 75°C for 3 hours to obtain a kneaded mixture. The obtained kneaded material was added to 2,000 parts of ion-exchanged water, stirred, filtered, and washed with water. This process was repeated to remove sodium chloride and diethylene glycol, thereby obtaining a wet cake containing a colorant in which PB15:3 particles were coated with resin (B-1). Dimethylaminoethanol was added as a basic compound to the obtained wet cake so that the amount was 80 mol % of the carboxy groups of the resin (B-1), and ion-exchanged water was further added to adjust the NV to 34 mass %, and the mixture was stirred and mixed using a disper to obtain a mixture. The resulting mixture was dispersed using Star Mill LMZ (0.5 mmφ zirconia beads, 90% filled) manufactured by Ashizawa Finetech Co., Ltd. at 40°C for a residence time of 15 minutes to obtain a pre-dispersion. The obtained pre-dispersion was subjected to circulation dispersion for 5 hours using a high-pressure homogenizer (Starburst Lab HJP-25005 manufactured by Sugino Machine Co., Ltd., equipped with an oblique collision chamber, processing pressure 200 MPa) with 100 kg of the mixture at a liquid temperature of 30 to 80°C during dispersion (the temperature at the outlet of the device was 60 to 80°C, and cooled to 30 to 50°C in a circulation tank). As a post-treatment step, magnetic foreign matter was removed from the dispersion using a MagCatch Filter MGCF-125 manufactured by Maeda Shell Services Co., Ltd. Subsequently, the dispersion was fed into a cylindrical centrifuge (ultracentrifuge ASM260FH, rotor volume 7.7 L, manufactured by Tomoe Engineering Co., Ltd.) at a temperature range of 30 to 70°C at a liquid feed rate of 1.0 L / min, and continuously centrifuged at a centrifugal acceleration of 20,000 G. 1.0 parts of Proxel GXL was added as a preservative, and the pH was adjusted to 9.0±0.5 using 48 wt% aqueous potassium hydroxide solution and 35% aqueous hydrochloric acid solution as pH adjusters. Ion-exchanged water was added to make the NV 27% by mass, and the mixture was stirred to make it uniform. The mixture was then filtered using a polypropylene roll depth filter 750L-SLS-050 (filtration accuracy: 5 μm) manufactured by Roki Techno Co., Ltd., to obtain colorant dispersion (1).

[0148] [Manufacturing Examples 2-34, 69-101] Production of colorant dispersions (2) to (34), (69) to (101) Colorant dispersions (2) to (34) and (69) to (101) were obtained in the same manner as in Production Example 1, except that the colorants and resins used were changed as shown in Table 3.

[0149] [Manufacturing Example 35] ·Production of colorant dispersions (35) 80 parts of PB15:3, 20 parts of resin (B-1) as nonvolatile matter, 450 parts of sodium chloride, and 180 parts of diethylene glycol were charged into a stainless steel 1-gallon kneader (manufactured by Inoue Seisakusho Co., Ltd.) and kneaded at 80°C for 3 hours to obtain a kneaded mixture. The obtained kneaded material was added to 2,000 parts of ion-exchanged water, stirred, filtered, and washed with water. This process was repeated to remove sodium chloride and diethylene glycol, thereby obtaining a wet cake containing a colorant in which PB15:3 particles were coated with resin (B-1). To the obtained wet cake, a 48 wt% aqueous solution of potassium hydroxide was added as a basic compound so that the amount was 80 mol% of the carboxy groups of the resin (B-1), and ion-exchanged water was further added to adjust the NV to 34 mass%, and the mixture was stirred and mixed using a disper to obtain a mixture. The resulting mixture was dispersed using Star Mill LMZ (0.5 mmφ zirconia beads, 90% filled) manufactured by Ashizawa Finetech Co., Ltd. at 40°C for a residence time of 15 minutes to obtain a pre-dispersion. The obtained pre-dispersion was subjected to circulation dispersion for 5 hours using a high-pressure homogenizer (Starburst Lab HJP-25005 manufactured by Sugino Machine Co., Ltd., equipped with an oblique collision chamber, processing pressure 200 MPa) with 100 kg of the mixture at a liquid temperature of 30 to 80°C during dispersion (the temperature at the outlet of the device was 60 to 80°C, and cooled to 30 to 50°C in a circulation tank), to obtain a dispersion. After cooling the resulting dispersion to 45°C, a resin modifier was added and stirred so that the number of moles of functional groups in the resin modifier was 0.9 equivalents relative to the number of moles of carboxy groups in resin (B-1). The mixture was then heated to 75°C and stirred for 2 hours to modify the carboxy groups in resin (B-1) with the resin modifier. As a post-treatment step, magnetic foreign matter was removed from the dispersion using a MagCatch Filter MGCF-125 manufactured by Maeda Shell Services Co., Ltd. Subsequently, the dispersion was fed into a cylindrical centrifuge (ultracentrifuge ASM260FH, rotor volume 7.7 L, manufactured by Tomoe Engineering Co., Ltd.) at a temperature range of 30 to 70°C at a liquid feed rate of 1.0 L / min, and continuously centrifuged at a centrifugal acceleration of 20,000 G. 1.0 parts of Proxel GXL was added as a preservative, and the pH was adjusted to 9.0±0.5 using 48 wt% aqueous potassium hydroxide solution and 35% aqueous hydrochloric acid solution as pH adjusters. Ion-exchanged water was added so that the NV was 27% by mass, and the mixture was filtered using a polypropylene roll depth filter 750L-SLS-050 (filtration accuracy: 5 μm) manufactured by Roki Techno Co., Ltd., to obtain colorant dispersion (35).

[0150] [Manufacturing Examples 36-68, 102-134] Production of colorant dispersions (36) to (68), (102) to (134) Colorant dispersions (36) to (68) and (102) to (134) were obtained in the same manner as in Production Example 35, except that the colorants and resins used were changed as shown in Table 3.

[0151] [Table 3-1]

[0152] [Table 3-2]

[0153] [Table 3-3]

[0154] [Table 3-4]

[0155] [Manufacturing Example 201] Ink (1) manufacturing The materials other than colorant dispersion (1) were stirred and mixed in a disperser until uniform. This mixture was added dropwise to colorant dispersion (1) being stirred in a disperser, and stirred until sufficiently uniform. After that, the mixture was filtered through a membrane filter with a pore size of 1 μm to obtain ink (1). Colorant Dispersion (1) 20 parts J-780 8 copies W-5030 5 copies W400S 3 parts S-DF110D 0.5 part Triethanolamine 0.2 parts Butyldiethanolamine 0.3 parts Diethylaminoethanol 1 part 1-dibutylamino-2-propanol 0.4 parts Triethylamine 0.1 parts 0.1 parts sodium hydroxide Potassium hydroxide 0.1 parts 1,2-Hexanediol 1 part Ethylene glycol 0.01 parts Diethylene glycol 0.5 parts 10 parts propylene glycol Dipropylene glycol 0.1 parts Butyl diglycol 2 parts 1 part glycerin Proxel GXL 0.05 parts Ion-exchanged water 47.64 parts

[0156] [Manufacturing Examples 202-334] Manufacture of inks (2) to (134) Inks (2) to (134) were obtained in the same manner as in Production Example 201, except that the colorant dispersion was changed as shown in Tables 4-1 to 4-4.

[0157] [Table 4-1]

[0158] [Table 4-2]

[0159] [Example 1] Preparation of ink set (1) Ink set (1) was obtained by filling inks (1), (2), (8), and (118) into inkjet ink containers that could be mounted on a Seiko Epson PX-105 (piezo inkjet printer).

[0160] [Examples 2 to 169] Preparation of ink sets (2) to (169) Ink sets (2) to (169) were obtained in the same manner as in Example 1, except that the ink combinations were changed as shown in Tables 5-1 to 5-4.

[0161] [Comparative Examples 1 to 10] Preparation of ink sets (211) to (220) Ink sets (211) to (220) were obtained in the same manner as in Example 1, except that the ink combinations were changed as shown in Tables 5-1 to 5-4.

[0162] [Table 5-1]

[0163] [Table 5-2]

[0164] [Table 5-3]

[0165] [Table 5-4]

[0166] <Bleeding evaluation (hydrophilic substrate)> Each ink set was loaded into a Seiko Epson PX-105 (piezo inkjet printer), and a hydrophilic polyester film #9901P manufactured by 3M was attached to A4 plain paper as a hydrophilic substrate and loaded, and a color image (Test Chart No. 7 (2008 edition) published by the Imaging Society of Japan (containing a solid image and an image of a person)) was printed, and hot air was blown onto the printed surface, while a heated roller was simultaneously applied to the backside of the print to dry it. The dots in the printed part of the image of the person were visually magnified using a magnifying glass and observed, and bleeding was evaluated using the following four-point scale. ◎: Almost no bleeding between dots (excellent) ○: There are some areas where dots bleed (good) △: Bleeding between dots occurs in about half or less of the areas (no practical problems) ×: Bleeding between dots occurs in the majority of areas (poor)

[0167] <Bleeding evaluation (hydrophobic substrate)> The substrate used was changed to Torayfan #30-2500H (a polypropylene film manufactured by Toray Industries, Inc.) as a hydrophobic substrate, and the bleeding property was evaluated in the same manner as in the bleeding property evaluation (hydrophilic substrate). ◎: Almost no bleeding between dots (excellent) ○: There are some areas where dots bleed (good) △: Bleeding between dots occurs in about half or less of the areas (no practical problems) ×: Bleeding between dots occurs in the majority of areas (poor)

[0168] <Gloss test> The 60° gloss of the solid image printed with each ink was measured for the solid image printed in the bleeding evaluation (hydrophobic substrate), and the gloss of the ink with the lowest gloss was evaluated according to the following criteria. ◎: Glossiness 70 or higher (excellent) ○: Glossiness 50 or more and less than 70 (good) △: Glossiness of 30 or more and less than 50 (no practical problems) ×: Glossiness less than 30 (poor)

[0169] The evaluation results are shown in Table 6.

[0170] [Table 6-1]

[0171] [Table 6-2]

[0172] [Table 6-3]

[0173] [Table 6-4]

[0174] The results in Table 6 show that the ink set using the first ink containing colorant (A), resin (B), and solvent (E), where resin (B) is a copolymer containing hydrophobic group-containing monomer units and acid group-containing monomer units but no hydrophilic group-containing monomer units other than acid groups, and the second ink containing colorant (A), resin (C), and solvent (E), where resin (C) is a copolymer containing hydrophobic group-containing monomer units, acid group-containing monomer units, and hydrophilic group-containing monomer units other than acid groups, suppresses dot-to-dot bleeding and has high gloss, regardless of the hydrophilicity or hydrophobicity of the printing substrate, making it a good ink set. In particular, the ink set using α-olefins as the hydrophobic group-containing monomers in resins (B) and (C) showed particularly good evaluation results. Furthermore, when these ink sets were loaded into a Canon MAXIFYMB5430 (thermal inkjet printer), printed, dried, and evaluated in the same manner, similar results were obtained. In addition, when these inkjet inks were loaded into an EFI Nozomi C18000 Plus (single-pass inkjet printer) manufactured by EFI and printed and dried in the same manner, and evaluated, similar results were obtained.

Claims

1. An ink set having at least a first ink and a second ink, the first ink contains a colorant (A), a resin (B), and a solvent (E); the second ink contains a colorant (A), a resin (C), and a solvent (E); the resin (B) is a copolymer containing a hydrophobic monomer unit and a monomer unit having an acid group, but not containing a monomer unit having a hydrophilic group other than an acid group; the resin (C) is a copolymer containing a hydrophobic monomer unit, a monomer unit having an acid group, and a monomer unit having a hydrophilic group other than an acid group, an ink set, wherein the monomer unit having a hydrophilic group other than an acid group in the resin (C) is a monomer unit containing one or more groups selected from a hydroxyl group and a (poly)alkyleneoxy group.

2. The ink set according to claim 1, wherein in resin (B) and resin (C), the hydrophobic monomer unit is a monomer unit containing one or more monomer units selected from the group consisting of a (meth)acrylic acid alkyl ester monomer unit, an aromatic monomer unit, a heterocyclic monomer unit, and an α-olefin monomer unit.

3. 3. The ink set according to claim 1 or 2, wherein in resin (B) and resin (C), the monomer units having an acid group are each independently monomer units containing one or more monomer units selected from the group consisting of maleic anhydride monomer units, maleic acid monomer units, maleic ester monomer units, maleic acid amide monomer units, and (meth)acrylic acid monomer units.

4. The ink set according to any one of claims 1 to 3, wherein the acid values ​​of the resin (B) and the resin (C) are 1 to 400 mgKOH / g.

5. The ink set according to any one of claims 1 to 4, wherein one or both of the resin (B) and the resin (C) are modified resins with a resin modifier (F).

6. The ink set according to any one of claims 1 to 5, wherein in the resin (B) and the resin (C), the hydrophobic monomer unit is an α-olefin monomer unit.

7. An image-formed product comprising a substrate and an image formed from the ink set according to claim 6.

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