Pigment dispersions for inkjet inks, photosensitive compositions for inkjet inks, cured products, and image display devices.

Abstract

The present invention aims to provide a pigment dispersion for inkjet inks that can be used to create inkjet inks with good storage stability and excellent lightfastness. [Solution] A pigment dispersion for inkjet ink comprising a phthalocyanine pigment, a polymerizable compound, and a dispersant, wherein the dispersant comprises a first polymerized moiety, a second polymerized moiety, and an acid dianhydride residue, the first polymerized moiety comprising a cyclic ester polymer, and the second polymerized moiety comprising a vinyl polymer without an acid group.

Description

Technical Field

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

Background Art

[0002] In recent years, in the production of color filters, an inkjet recording method has been studied in place of the photolithography method from the viewpoint of reducing environmental load. Ink used in the inkjet recording method (hereinafter referred to as inkjet ink) needs to have ejection properties from an inkjet nozzle. Therefore, for the pigment dispersion, storage stability in which changes in viscosity and dispersed particle diameter hardly occur over time is important.

[0003] Patent Document 1 discloses an inkjet recording ink composition containing a pigment, a pigment dispersant, a polymerizable compound, and an ammonium phthalocyanine sulfonate salt, containing carbon black as the pigment, containing a basic polymer dispersant as the pigment dispersant, and containing N-vinylcaprolactam at 15% by weight or more of the whole ink composition and satisfying predetermined parameters. Patent Document 2 discloses an inkjet ink composition containing an organic pigment and a basic polymer dispersant, wherein the organic pigment includes a benzimidazolo-based pigment or a bisacetoacetalide-based pigment, and the basic polymer dispersant includes a polymer dispersant (dispersant A) having a weight average molecular weight of 10,000 to 80,000 and a polymer dispersant (dispersant B) having a weight average molecular weight of 100,000 to 200,000.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventional compositions lacked storage stability. Furthermore, the basic dispersants used in the compositions had reducing properties derived from their amine structure, and even highly durable pigments like phthalocyanine pigments suffered from lightfastness problems, where the pigments gradually faded in environments where they were used for long periods, such as color filters.

[0006] The present invention aims to provide a pigment dispersion for inkjet inks that can produce inkjet inks with good storage stability and excellent lightfastness. [Means for solving the problem]

[0007] The pigment dispersion for inkjet inks of the present invention comprises a phthalocyanine pigment, a polymerizable compound, and a dispersant. The dispersant comprises a first polymerized moiety, a second polymerized moiety, and an acidic dianhydride residue, wherein the first polymerized moiety comprises a cyclic ester polymer, and the second polymerized moiety comprises a vinyl polymer without an acid group. [Effects of the Invention]

[0008] The present invention provides a pigment dispersion for inkjet inks that has good storage stability and excellent lightfastness. Furthermore, the present invention provides a photosensitive composition for inkjet inks, a cured product, and an image display device. [Modes for carrying out the invention]

[0009] The following describes in detail embodiments for implementing the pigment dispersion for inkjet inks of the present invention. However, the present invention is not limited to the following embodiments and can be modified and implemented within the scope of solving the problem.

[0010] In this specification, "(meth)acryloyl," "(meth)acrylic," "(meth)acrylic acid," "(meth)acrylate," or "(meth)acrylamide" means, unless otherwise specified, "acryloyl and / or methacryloyl," "acrylic and / or methacrylic," "acrylic acid and / or methacrylic acid," "acrylate and / or methacrylate," or "acrylamide and / or methacrylamide," respectively. Also, "CI" means Color Index (CI; issued by The Society of Dyers and Colourists). The polymerizable unsaturated groups are vinyl, (meth)acryloyl, and (meth)allyl groups.

[0011] The pigment dispersion for inkjet inks of the present invention comprises a phthalocyanine pigment, a polymerizable compound, and a dispersant. The dispersant comprises a first polymerized moiety, a second polymerized moiety, and an acidic dianhydride residue, wherein the first polymerized moiety comprises a cyclic ester polymer, and the second polymerized moiety comprises a vinyl polymer without an acid group.

[0012] The mechanism by which the pigment dispersion for inkjet inks of the present invention can solve the problem is as follows. The acid dianhydride residues in the dispersant act as adsorption groups for the phthalocyanine pigment, while the first and second polymerized moieties act as steric repulsion sites. The first polymerizable site, the cyclic ester polymer, has low affinity for polymerizable compounds and high crystallinity, making it prone to dispersant segregation and relatively close to the phthalocyanine pigment. On the other hand, the second polymerizable site, the vinyl polymer, has high affinity for polymerizable compounds and is prone to causing the dispersant to detach from the phthalocyanine pigment. However, a dispersant having both a first polymerizable site and a second polymerizable site can reduce the crystallinity of the cyclic ester polymer while appropriately adjusting the affinity of the vinyl polymer, thereby improving the dispersion stability of the phthalocyanine pigment. Furthermore, it is hypothesized that, for example, in environments where the material is used for extended periods, such as in color filters, cured products formed from compositions containing the dispersion will exhibit improved lightfastness because the nearby cyclic ester polymer intercepts radicals generated over time before they can attack the phthalocyanine pigment, leading to molecular cleavage while reducing the attack on the phthalocyanine pigment.

[0013] <Phthalocyanine pigment> In this specification, phthalocyanine pigments include, for example, the following green and blue pigments. Pigments are exemplified by color indexes, etc.

[0014] Examples of green pigments include CI Pigment Green 7, 36, 37, 58, 59, 62, and 63. Among these, CI Pigment Green 36, 58, 59, and 63 are preferred in terms of coloring power and storage stability.

[0015] Examples of blue pigments include CI Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, and 79.

[0016] (Pigment refinement) Phthalocyanine pigments are preferably used after being finely milled. The milling method is not particularly limited, and for example, wet milling, dry milling, or dissolution milling can all be used. Among these, salt milling by the kneader method, which is a type of wet milling, is preferred. The average primary particle size of the finely milled pigment, as determined by TEM (transmission electron microscopy), is preferably 5 to 90 nm. From the viewpoint of dispersibility, an average primary particle size of 10 to 70 nm is more preferable.

[0017] For the salt milling process, for example, salt can be used and a resin can be added as needed. By adding the resin, the pigment is coated with the resin, and the stability, light resistance, etc. are improved. The type of the resin is not particularly limited, and examples include natural resins, modified natural resins, synthetic resins, synthetic resins modified with natural resins, etc. Among these, it is preferably solid at room temperature, water-insoluble, and partially soluble in an organic solvent. The addition amount of the resin is preferably 2 to 200 parts by mass with respect to 100 parts by mass of the pigment.

[0018] The content of the phthalocyanine pigment is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, in the non-volatile content of the pigment dispersion for inkjet ink.

[0019] <Polymerizable compound> The polymerizable compound is a monomer or oligomer having a polymerizable unsaturated group. The polymerizable compound is a compound containing 1 to 个数不明の数字(原文では不明)を含む重合性不飽和基である。The weight average molecular weight (or formula weight) of the polymerizable compound is 5000 or less, preferably 2000 or less. The polymerizable compound is preferably not a polymer.

[0020] 注:原文中“重合性不飽和基を1~15を含有する化合物である”里“1~15を含有する”部分的“を含有する”前的数字“15”后面的量词原文缺失,我按照原文格式保留了。你可根据实际情况补充完整后再看译文是否符合需求。Polymerizable compounds having one polymerizable unsaturated group include, for example, benzyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, (ethoxylated (or propoxylated)) 2-phenoxyethyl (meth)acrylate, dicyclopentenyl (oxyethyl) (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, methoxydipropylene glycol (meth)acrylate, dipropylene glycol (meth)acrylate, nonylphenol EO modified acrylate, nonylphenol PO modified acrylate, o-phenylphenol EO modified acrylate, 2-ethylhexyl EO modified acrylate, β-carboxyethyl (meth)acrylate, and trimethylolpropaneform Examples include monofunctional acrylic monomers such as ethyl(meth)acrylate, isoamyl(meth)acrylate, cyclohexyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, isobolonyl(meth)acrylate, norbornyl(meth)acrylate, dicyclopentanyl(meth)acrylate, isooctyl(meth)acrylate, lauryl(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, 1,4-cyclohexanedimethanol(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, acryloylmorpholine, and N-acryloyloxyethylhexahydrophthalimide; and monofunctional vinyl monomers such as N-vinylcaprolactam, N-vinylpyrrolidone, and N-vinylformamide. Note that "EO modified" refers to ethylene oxide modification, and "PO modified" refers to propylene oxide modification.

[0021] Polymeric compounds having two or more polymerizable unsaturated groups include, for example, dimethyloltricyclodecane di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (ethoxy(or propoxy)ylated) 1,6 - hexanediol di(meth)acrylate, 1,9 - nonanediol acrylate, 1,10 - decanediol diacrylate, (ethoxy(or propoxy)ylated) neopentyl glycol di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, dipropylene glycol di(meth)acrylate, 2-(2 - vinyloxyethoxy)ethyl acrylate, (neopentyl glycol modified) trimethylolpropane di(meth)acrylate, tripropylene glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, pentaerythritol tri(or tetra)(meth)acrylate, trimethylolpropane tri(or tetra)(meth)acrylate, tetramethylolmethane tri(or tetra)(meth)acrylate, and dipentaerythritol hexa(meth)acrylate, etc. Among these, 2-(2 - vinyloxyethoxy)ethyl acrylate is preferred.

[0022] In this specification, the polymeric compound is preferably a polymeric compound having two or more polymerizable unsaturated groups in terms of low viscosity and photocurability. Among the polymeric compounds having two or more polymerizable unsaturated groups, compounds having an ethyleneoxy moiety and a propyleneoxy moiety are preferred, and dipropylene glycol diacrylate is more preferred.

[0023] The polymeric compound can be used alone or in combination of two or more.

[0024] The content of the polymeric compound is preferably 10 - 80% by mass, more preferably 10 - 70% by mass, in the non - volatile matter of the pigment dispersion for inkjet ink.

[0025] <Dispersant> In this specification, the dispersant comprises a first polymerized moiety, a second polymerized moiety, and an acidic dianhydride residue. The first polymerized moiety includes a cyclic ester polymer, and the second polymerized moiety includes a vinyl polymer that does not contain an acid group. The dispersant will be described in detail below, but it goes without saying that the dispersant only needs to have the above configuration and is not limited to the following description.

[0026] (First polymerized portion) The cyclic ester polymer forming the first polymerized moiety preferably has a hydroxyl group at its terminal end that can react with an acidic dianhydride. For example, a cyclic ester polymer having a hydroxyl group at one end can be synthesized by using an active hydrogen compound as an initiator and performing ring-opening polymerization of the cyclic ester. Since the polymerization reaction of the cyclic ester is controlled by the use of the initiator, a cyclic ester polymer with a narrow molecular weight distribution can be obtained.

[0027] The cyclic ester polymer preferably contains a polymer of a lactone, which is a cyclic ester (polylactone). Examples of lactones include 3- to 16-membered cyclic esters such as α-acetolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, ζ-enanthlactone, η-capryloractone (=8-hydroxyoctanoic acid lactone), 12-hydroxydodecanoic acid lactone, 13-hydroxytridecanoic acid lactone, 14-hydroxytetradecanoic acid lactone, and 15-hydroxypentadecanoic acid lactone. Among these, δ-valerolactone and ε-caprolactone are preferred from the viewpoint of reaction control, and ε-caprolactone is more preferred. However, if the problems of the present invention can be solved, the cyclic ester polymer may use compounds other than lactones.

[0028] In addition to lactones, copolymerizable cyclic compounds can be used in the synthesis of cyclic ester polymers. Examples of cyclic compounds include lactides, trimethylene carbonates, glycolides, and lactams. Of the mass of the polymerizable cyclic ester polymer, polylactone is preferably 50% by mass or more, and more preferably 70% by mass or more. The mass of polylactone is preferably 90% by mass or more, and more preferably 100% by mass.

[0029] Cyclic esters can be used alone or in combination of two or more types.

[0030] (Synthesis of the first polymerized moiety) (Active hydrogen compounds) The active hydrogen compound used in the synthesis of cyclic ester polymers is not limited as long as it can provide active hydrogen to the polymerization site that contributes to the polymerization of the cyclic ester. In this specification, the active hydrogen compound is preferably a compound having at least one functional group selected from a hydroxyl group, a carboxyl group, a phosphate group, an amino group, and a thiol group. Among these, compounds having a hydroxyl group are preferred in terms of excellent reactivity, and monoalcohols are more preferred from the viewpoint of reaction control.

[0031] Monoalcohols include, for example, methanol, ethanol, 1-propanol, isopropanol, 1-butanol, isobutanol, tert-butanol, 1-pentanol, isopentanol, 1-hexanol, cyclohexanol, 4-methyl-2-pentanol, 1-heptanol, 1-octanol, isooctanol, 2-ethylhexanol, 1-nonanol, isononanol, 1-decanol, 1-dodecanol, 1-myristyl alcohol, cetyl alcohol, 1-stearyl alcohol, isostearyl alcohol, 2-octyl Aliphatic monoalcohols such as rudecanol, 2-octyldodecanol, 2-hexyldecanol, behenyl alcohol, and oleyl alcohol; aromatic ring-containing monoalcohols such as benzyl alcohol, phenoxyethyl alcohol, and paracumylphenoxyethyl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, propylene Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monohexyl ether, propylene glycol mono-2-ethylhexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monohexyl ether, dipropylene glycol mono-2-ethylhexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, triethylene glycol monohexyl ether,Examples include alkylene glycol monoalkyl ethers such as triethylene glycol mono-2-ethylhexyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monohexyl ether, tripropylene glycol mono-2-ethylhexyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monopropyl ether, tetraethylene glycol monobutyl ether, tetraethylene glycol monohexyl ether, tetraethylene glycol mono-2-ethylhexyl ether, tetrapropylene glycol monomethyl ether, tetrapropylene glycol monoethyl ether, tetrapropylene glycol monopropyl ether, tetrapropylene glycol monobutyl ether, tetrapropylene glycol monohexyl ether, tetrapropylene glycol mono-2-ethylhexyl ether, and tetradiethylene glycol monomethyl ether, as well as reactive alcohols such as 3-ethyl-3-oxetane methanol and 3-ethyl-3-(4-hydroxybutyloxymethyl)oxetane. Monoalcohols can be used alone or in combination of two or more types.

[0032] For ring-opening polymerization, it is preferable to use monoalcohols with a molecular weight of 100 to 300. Using a molecular weight of 300 or less allows for polymer regions with a narrow molecular weight distribution, improving the dispersibility of the dispersant. Using a molecular weight of 100 or more enables ring-opening polymerization of cyclic esters at high temperatures, improving the yield.

[0033] The amount of initiator used is preferably 0.1 to 100 moles, more preferably 0.5 to 100 moles, and even more preferably 1 to 100 moles, per 100 moles of cyclic ester. By controlling the molar ratio of cyclic ester to initiator, the molecular weight of the cyclic ester polymer can be adjusted.

[0034] Polymerization catalysts can be used for ring-opening polymerization. Using a polymerization catalyst can lower the reaction temperature and shorten the reaction time. Examples of polymerization catalysts include quaternary ammonium salts such as tetramethylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetrabutylammonium bromide, tetramethylammonium iodine, tetrabutylammonium iodine, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, and benzyltrimethylammonium iodine; and tetramethylphosphonium chloride, tetrabutylphosphonium chloride, tetramethylphosphonium bromide, tetrabutylphosphonium bromide, tetramethylphosphonium iodine, tetrabutylphosphonium iodine, benzyltrimethylphosphonium chloride, and benzyltrimethylphosphonium. Examples include quaternary phosphonium salts such as bromide, benzyltrimethylphosphonium iodine, tetraphenylphosphonium chloride, tetraphenylphosphonium bromide, and tetraphenylphosphonium iodine; phosphorus compounds such as triphenylphosphine; organotin compounds such as monomethyltin oxide, monobutyltin oxide, monooctyltin oxide, dibutyltin oxide, and dioctyltin dilaurate; organic carboxylates such as potassium acetate, sodium acetate, potassium benzoate, and sodium benzoate; sodium alkoxides; alkali metal alkoxides such as potassium alkoxide; tertiary amines, organoaluminum compounds, organotitanate compounds, and zinc compounds such as zinc chloride.

[0035] The amount of polymerization catalyst used is preferably 0.1 ppm to 3000 ppm per 100 units of cyclic ester, and more preferably 1 ppm to 1000 ppm. Using this range makes it easy to obtain a colorless cyclic ester polymer at a polymerization rate suitable for production.

[0036] The polymerization temperature for cyclic esters is preferably 100°C to 220°C, and more preferably 110°C to 210°C. Polymerization within this range allows for the easy acquisition of cyclic ester polymers with low by-products and a polymerization rate suitable for industrial production.

[0037] The weight-average molecular weight of the cyclic ester polymer is preferably 500 to 10,000, more preferably 1,000 to 8,000, and even more preferably 1,500 to 5,000. When the molecular weight is 500 or higher, the steric repulsion effect further improves the dispersibility stability of the phthalocyanine pigment in the pigment dispersion for inkjet inks. When the molecular weight is 10,000 or lower, appropriate solubility is obtained for the polymerizable compound, and dispersibility is further improved.

[0038] (Second polymerized part) The vinyl polymer forming the second polymer site does not have acid groups. This suppresses entanglement of the dispersant due to hydrogen bonding between polymer sites via acid groups. As a result, inkjet inks using the dispersion are less likely to exhibit localized thixotropy in viscosity, and can maintain long-term ejection stability when printed with an inkjet printer. Furthermore, it is preferable that the vinyl polymer without acid groups has, for example, a hydroxyl group at its terminal end that can react with an acidic dianhydride. By polymerizing a vinyl monomer without acid groups in the presence of a thiol group-containing alcohol compound, a vinyl polymer without acid groups but with a hydroxyl group at one end can be synthesized. Examples of acid groups include carboxyl groups, sulfo groups, phosphonic acid groups, and sulfonic acid amide groups.

[0039] Vinyl polymers without acid groups preferably contain thermocrosslinking group-containing monomer units such as tert-butyl group-containing vinyl monomers, oxetane group-containing vinyl monomers, epoxy group-containing vinyl monomers, and blocked isocyanate group-containing vinyl monomers. Examples of thermocrosslinking group-containing monomers include tert-butyl group-containing vinyl monomers such as tert-butyl methacrylate and tert-butyl acrylate; oxetane group-containing vinyl monomers such as 3-ethyl-3-methacryloyloxymethyl oxetane and 3-ethyl-3-acryloyloxymethyl oxetane; epoxy group-containing vinyl monomers such as glycidyl methacrylate; and blocked isocyanate group-containing vinyl monomers such as 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl (meth)acrylate and 2-[0-(1'-methylpropyleneneamino)carboxyamino]ethyl (meth)acrylate. The presence of these thermocrosslinking groups improves the heat resistance of the dispersant.

[0040] The content of thermocrosslinking group-containing monomer units is preferably 5 to 90% by weight, and more preferably 20 to 60% by weight, of the total monomer units of the vinyl polymer. When used in an appropriate amount, a crosslinking effect can be obtained without impairing polymerization stability.

[0041] Furthermore, vinyl polymers without acid groups may contain other vinyl monomer units. Examples of other vinyl monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, isoamyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cetyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, Linear or branched alkyl (meth)acrylates such as tridecyl (meth)acrylate, isomiristyl (meth)acrylate, stearyl (meth)acrylate, or isostearyl (meth)acrylate, methoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, methoxypolytetramethylene glycol (meth)acrylate, or methoxypolyethylene glycol polypropylene glycol (meth)acrylate; (meth)acrylates having aromatic rings, such as benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, paracumyl phenoxyethyl (meth)acrylate, paracumyl phenoxypolyethylene glycol (meth)acrylate, or nonyl phenoxypolyethylene glycol (meth)acrylate; Cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, or isobornyl (meth)acrylate, and other cyclic alkyl (meth)acrylates; Vinyl such as styrene, α-methylstyrene, vinyl acetate, vinyl (meth)acrylate, or allyl (meth)acrylate; (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, diacetone(meth)acrylamide, or N-substituted (meth)acrylamides such as acryloylmorpholine; Amino group-containing (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate or N,N-diethylaminoethyl (meth)acrylate; Nitriles such as (meth)acrylonitrile; Fluoroalkyl (meth)acrylates such as trifluoroethyl (meth)acrylate, octafluoropentyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, or tetrafluoropropyl (meth)acrylate; Examples include (meth)acryloxy-modified polydimethylsiloxane (silicone macromer);

[0042] <Thiol group-containing alcohol compounds> The thiol group-containing alcohol compound is preferably a compound having one or more hydroxyl groups and thiol groups in its molecule, and more preferably a compound having two hydroxyl groups and one thiol group in its molecule. This allows the vinyl polymer without acid groups to form a second polymer site through reaction with an acidic dianhydride.

[0043] Examples of compounds having two hydroxyl groups and one thiol group in their molecule include 1-mercapto-1,1-methanediol, 1-mercapto-1,1-ethanediol, 3-mercapto-1,2-propanediol (thioglycerol), 2-mercapto-1,2-propanediol, 2-mercapto-2-methyl-1,3-propanediol, 2-mercapto-2-ethyl-1,3-propanediol, 1-mercapto-2,2-propanediol, 2-mercaptoethyl-2-methyl-1,3-propanediol, or 2-mercaptoethyl-2-ethyl-1,3-propanediol. Compounds having one hydroxyl group and one thiol group in their molecule include mercaptomethanol, 2-mercaptoethanol, 3-mercapto-1-propanol, 1-mercapto-2-butanol, and 2-mercapto-3-butanol. Among these, compounds having two hydroxyl groups and one thiol group in their molecule are preferred, and 3-mercapto-1,2-propanediol is more preferred from the viewpoint of polymerization control and odor.

[0044] The amount of compound having two hydroxyl groups and one thiol group used is preferably 1 to 10 parts by mass, more preferably 2 to 9 parts by mass, and even more preferably 4 to 8 parts by mass, per 100 parts by mass of the total vinyl monomer. Using an appropriate amount makes it easier to obtain a vinyl polymer with a suitable molecular weight that functions as a steric repulsion site for the dispersant, further improving the storage stability of the pigment dispersion for inkjet inks.

[0045] The polymerization temperature is preferably 40 to 150°C, and more preferably 50 to 110°C. Polymerization at an appropriate temperature facilitates control of the polymerization reaction and adjustment of the molecular weight.

[0046] Polymerization of vinyl monomers without acid groups requires the use of a polymerization initiator. The amount of polymerization initiator used is preferably 0.001 to 5 parts by mass per 100 parts by mass of the monomer. Examples of polymerization initiators include azo compounds and organic peroxides.

[0047] Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane1-carbonitride), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), or 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

[0048] Examples of organic peroxides include benzoyl peroxide, tert-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, tert-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, or diacetyl peroxide.

[0049] Polymerization initiators can be used alone or in combination of two or more types.

[0050] (Acid dianhydride residue) The dispersant of the present invention has an acid dianhydride residue. The acid dianhydride residue is generated by reacting the terminal hydroxyl group of the first polymer site or the second polymer site with an acid dianhydride.

[0051] (acid dianhydride) Examples of acidic dianhydrides include aliphatic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, or polycyclic tetracarboxylic dianhydrides.

[0052] Examples of aliphatic tetracarboxylic dianhydrides include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,3,5,6-tetracarboxycyclohexane dianhydride, 2,3,5,6-tetracarboxynorbornane dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5-(2,5-dioxotetrahydrofural)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride, and bicyclo[2,2,2]-octo-7-ene-2,3,5,6-tetracarboxylic dianhydride.

[0053] Aromatic tetracarboxylic dianhydrides include, for example, pyromellitic dianhydride, ethylene glycol ditrimellitic anhydride, propylene glycol ditrimellitic anhydride, butylene glycol ditrimellitic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenylsulfone tetracarboxylic dianhydride, 2,2',3,3'-biphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-biphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3',4,4'-tetraphenylsilane tetracarboxylic dianhydride, and 1,2,3,4-furantetracarboxylic dianhydride. 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 3,3',4,4'-perfluoroisopropylidene diphthalic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, bis(phthalic acid)phenylphosphine oxide dianhydride Examples include p-phenylene-bis(triphenylphthalic acid) dianhydride, M-phenylene-bis(triphenylphthalic acid) dianhydride, bis(triphenylphthalic acid)-4,4'-diphenyl ether dianhydride, bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride.

[0054] Examples of polycyclic tetracarboxylic dianhydrides include 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinate dianhydride and 3,4-dicarboxy-1,2,3,4-tetrahydro-6-methyl-1-naphthalenesuccinate dianhydride.

[0055] Among these, aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides are more preferred from the viewpoint of adsorption to phthalocyanine pigments, and aromatic tetracarboxylic dianhydrides are even more preferred. In other words, acid anhydride residues having aromatic rings are preferred, which improves the storage stability of the pigment dispersion for inkjet inks.

[0056] (Method of manufacturing dispersant) As previously described, the dispersant in this specification only needs to have a first polymerized moiety, a second polymerized moiety, and an acid dianhydride residue, and its synthesis method is not limited. Dispersants can be synthesized by the following method: For example, in the step of synthesizing a vinyl polymer without acid groups having a hydroxyl group at one end by reacting a thiol-containing alcohol compound with a vinyl monomer without acid groups in the presence of a polymer containing a cyclic ester polymer having a hydroxyl group at one end (1), Preferably, the process then includes a step (2) of reacting the acid dianhydride with these polymers to synthesize a dispersant having a first polymer moiety containing a cyclic ester polymer, a second polymer moiety containing a vinyl polymer without acid groups, and an acid dianhydride residue.

[0057] Step (1) above involves reacting a thiol-containing alcohol compound with a vinyl monomer without acid groups in the presence of the cyclic ester polymer synthesized as described above, to synthesize a vinyl polymer without acid groups having a hydroxyl group at one end. The cyclic ester polymer functions as a reaction solvent during the polymerization of the vinyl monomer without acid groups, so polymerization can be carried out without the use of organic solvents. However, the above description does not exclude the use of organic solvents during polymerization. The synthesis of the vinyl polymer without acid groups is as described above.

[0058] The acidic dianhydride used in step (2) is as previously described.

[0059] The amount of acidic dianhydride used is preferably 0.5 to 1.5 moles, more preferably 0.6 to 1.2 moles, and even more preferably 0.7 to 1.0 moles, when the total amount of hydroxyl groups in the cyclic ester polymer and the vinyl polymer is considered as 1 mole. By reacting an appropriate amount, a dispersant is obtained in which the acidic dianhydride residues of the pigment adsorption sites and the first and second polymer sites of the steric repulsion sites are appropriately bound.

[0060] In step (2) above, an esterification catalyst can be used. A tertiary amine is preferred as the esterification catalyst. Examples of tertiary amines include triethylamine, triethylenediamine, N,N-dimethylbenzylamine, N-methylmorpholine, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene.

[0061] The reaction temperature in step (2) is preferably 40 to 150°C, and more preferably 50 to 120°C. The reaction is easier to control when carried out at a suitable temperature. When using compounds containing two hydroxyl groups and one thiol group in the synthesis of cyclic ester polymers or vinyl polymers without acid groups, two hydroxyl groups are present near one end of the cyclic ester polymer or vinyl polymer without acid groups. In this case, multiple acid dianhydrides form multiple ester bonds through reaction with the two hydroxyl groups. Therefore, during the reaction in step (2), when the ester bonds are formed, an end-sealing agent (e.g., monoalcohol, monoamine) can be reacted with the acid anhydride groups at the molecular ends to form sealed sites. This improves the storage stability of the dispersant.

[0062] The aforementioned encapsulated portion can be formed by adding and reacting an end-encapsulating material when 70-98% of the acid anhydride groups have reacted. It is more preferable to add the end-encapsulating material when 75-95% of the acid anhydride groups have reacted.

[0063] The amount of end-capturing agent used is preferably equivalent to 40-90 mol%, more preferably 50-90 mol%, and even more preferably 60-85 mol%, when the acid anhydride groups present at the time of adding the end-capturing agent are considered to be 100 mol%. Adding an appropriate amount suppresses unreacted acid anhydride groups, thereby improving the storage stability of the dispersant itself and the dispersion.

[0064] Monoalcohols include, for example, methanol, ethanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, isopentyl alcohol, tert-pentyl alcohol, cyclopentanol, 1-hexanol, cyclohexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, isononyl alcohol, 1-nonyl alcohol, amyl alcohol, lauryl alcohol, n-butyl alcohol, isobutyl alcohol, cyclohexanol, benzyl alcohol, methylcyclohexanol, and other monoalcohols. Monoalcohols having an ether group, such as 3-methoxy-3-methyl-1-butanol, 3-methoxybutanol, ethylene glycol monoisopropyl ether, ethylene glycol monoethyl ether, ethylene glycol monotertiary butyl ether, ethylene glycol monobutyl ether, ethylene glycol monopropyl ether, ethylene glycol monohexyl ether, ethylene glycol monomethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, propylene glycol monophenyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monomethyl ether, etc. Examples include monoalcohols having a carbonyl group, such as methyl lactate, ethyl lactate, and diacetone alcohol.

[0065] The monoalcohol is preferably a compound having an ether group or a carbonyl group. The dispersant can have an ether group or a carbonyl group at the acid dianhydride residue site, which improves its affinity with various solvents contained in the dispersion, such as acetate-based solvents such as propylene glycol monomethyl ether acetate, and improves the dispersibility of the dispersant. Among these, 3-methoxybutanol, propylene glycol monomethyl ether, and diacetone alcohol are preferred monoalcohols.

[0066] From the viewpoint of reaction control, secondary amines are preferred for the monoamine. By using a secondary amine, side reactions such as crosslinking reactions with acid dianhydrides can be suppressed. Secondary amines are aliphatic secondary amines such as dimethylamine, diethylamine, ethylmethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-s-butylamine, di-tert-butylamine, N-methylbutylamine, N-ethylbutylamine, di-n-pentylamine, di-n-hexylamine, di-n-heptylamine, di-n-octylamine, di-2-ethylhexylamine, di-n-decylamine, di-n-undecylamine, di-n-dodecylamine (dilaurylamine), di-n-tridecylamine, di-n-tetradecylamine (dimyristylamine), di-n-hexadecylamine (dipalmitylamine), di-n-stearylamine, and diisostearylamine; Alicyclic secondary amines such as N-methylcyclopentylamine, N-ethylcyclopentylamine, N-propylcyclopentylamine, N-methylcyclohexylamine, N-ethylcyclohexylamine, N-propylcyclohexylamine, and N-isopropylcyclohexylamine; Examples include aromatic secondary amines such as N-methylaniline, N-ethylaniline, N-propylaniline, N-isopropylaniline, N-butylaniline, N-isobutylaniline, N-methylbenzylamine, N-ethylbenzylamine, N-propylbenzylamine, N-isopropylbenzylamine, N-butylbenzylamine, 1-(methylaminomethyl)naphthalene, and 9-(methylamino)methylanthracene.

[0067] The mass ratio of the first polymerized moiety to the second polymerized moiety in the dispersant is preferably 0.3 to 5.0, more preferably 0.4 to 4.0, and even more preferably 0.5:1 to 3.0, with the second polymerized moiety being 1. By setting the ratio within the above range, the dispersant has appropriate solubility for the polymerizable compound, thereby improving the storage stability of the pigment dispersion for inkjet inks.

[0068] [Molecular weight] The weight-average molecular weight of the dispersant of the present invention is preferably 2,000 to 35,000, more preferably 2,000 to 30,000, and even more preferably 3,000 to 20,000. When the molecular weight is 2,000 or higher, the dispersion stability of the phthalocyanine pigment is further improved due to the steric repulsion effect between the first polymerized moiety and the second polymerized moiety, thereby improving the storage stability of the inkjet ink.

[0069] [Acid value] The acid value of the dispersant is preferably 10 to 200 mg KOH / g, more preferably 20 to 150 mg KOH / g, even more preferably 30 to 120 mg KOH / g, and particularly preferably 30 to 110 mg KOH / g. By adjusting the acid value to an appropriate range, the dispersion stability of the phthalocyanine pigment is further improved, and the storage stability of the inkjet ink is enhanced.

[0070] The pigment dispersion for inkjet inks of the present invention can be used in combination with other dispersants besides the aforementioned dispersant. Other dispersants are described in Japanese Patent Publication No. 2011-225848, etc. Commercially available other dispersants include, for example, the SOLSPERSE series from Lubrizol (e.g., SOLSPERSE 16000, 21000, 32000, 33000, 41000, J180, J200, etc.); the DISPERBYK series from Bic Chemie (e.g., DISPERBYK 102, 110, 111, 118, 165, 168, 190, etc.); and the TEGO Dispers series from Evonik (e.g., TEGO Dispers 610, 630, 651, 655, 750W, 755W, etc.).

[0071] The dispersant content is preferably 5 to 20% by weight, and more preferably 5 to 15% by weight, of the nonvolatile content of the pigment dispersion for inkjet inks.

[0072] <Pigment derivatives> The pigment dispersions for inkjet inks described herein may contain pigment derivatives. Pigment derivatives are compounds that have a basic substituent, such as a sulfonamide group or a tertiary amino group at the terminal end, introduced into a pigment skeleton that is a dispersion aid and has affinity for phthalocyanine pigments. For example, these are compounds having a structure in which part of the structure of pyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, dioxazine compounds, perinone compounds, perylene compounds, thiaidine indigo compounds, triazine compounds, benzimidazolon compounds, indole compounds such as benzoisoindole, isoindoline compounds, isoindolinone compounds, quinophthalone compounds, naphthol compounds, quinacridone compounds, surene compounds, metal complex compounds, azo compounds such as azo, disazo, and polyazo, and squarylium compounds is substituted with a basic group.

[0073] Pigment derivatives can be used alone or in combination of two or more types.

[0074] Furthermore, the pigment dispersion for inkjet inks of the present invention may also use a compound as a pigment derivative, in which an acidic substituent such as a sulfo group or carboxyl group is introduced into a skeleton that has affinity for pigments, such as a pigment skeleton.

[0075] The amount of pigment derivative used is preferably 1 to 100 parts by mass, more preferably 3 to 50 parts by mass, and even more preferably 5 to 30 parts by mass, per 100 parts by mass of phthalocyanine pigment.

[0076] Specific examples of pigment derivatives are shown below, with their compound numbers. However, this list is not limited to these examples.

[0077] compound 1 [ka] CuPc represents a copper phthalocyanine residue.

[0078] compound 2 [ka]

[0079] compound 3 [ka]

[0080] compound 4 [ka]

[0081] The inkjet ink compositions described herein (hereinafter sometimes referred to as photosensitive inkjet ink compositions) preferably contain the above-mentioned inkjet ink pigment dispersion and a photopolymerization initiator.

[0082] <Photopolymerization initiator> Photopolymerization initiators are, for example, photopolymerization initiators that generate radicals by molecular cleavage or hydrogen abstraction. Photopolymerization initiators may be used alone or in combination of two or more types. Alternatively, a photopolymerization initiator that generates radicals may be used in combination with a photopolymerization initiator that generates cations.

[0083] In this specification, oxime ester compounds are preferred as photopolymerization initiators.

[0084] (Oxime ester compounds) Oxime ester compounds undergo cleavage of the NO bond in the oxime upon absorption of ultraviolet light, generating iminyl radicals and alkyloxy radicals. These radicals further decompose to produce highly reactive radicals, allowing the ink to cure with less exposure. Oxime ester compounds have high quantum efficiency, resulting in a highly curable coating film with fewer impurities.

[0085] Examples of oxime ester compounds include 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyl oxime), and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyl oxime).

[0086] Commercially available oxime ester compounds include IRGACURE OXE-01, 02, 03, 04, 05 from BASF Japan; ADEKA Arcules N-1919, NCI-730, 831E, 930 from ADEKA Corporation; TRONLY TR-PBG-301, 304, 305, 309, 314, 345, 358, 380, 365, 610, 3054, 3057 from Changzhou Strong New Materials Co., Ltd.; Omnirad 1312, 1314, 1316 from IGM Resins; SPI-02, 03, 04, 05, 06, 07 from Samyang Corporation; and DFI-020, 306, EOX-01 from Daito Chemix Co., Ltd.

[0087] In addition to oxime ester compounds, the following compounds can be used as photopolymerization initiators: For example, α-hydroxyalkylphenone compounds such as 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]-phenyl}-2-methylpropan-1-one, and phenylglyoxylic acid methyl ester; 2-methyl-1-[4-(methylthio α-aminoalkylphenone compounds such as )phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butanone-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morphoryl)phenyl]-1-butanone; bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2, Acyl phosphine oxide compounds such as 4,6-trimethylbenzoyl-diphenyl-phosphine oxide, benzophenone compounds such as 4-phenylbenzophenone, isophthalphenone, and 4-benzoyl-4'-methyl-diphenyl sulfide; 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl) Examples include triazine compounds such as -s-triazine, 2-piperonyl-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, or 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine.

[0088] Commercially available examples include α-hydroxyalkylphenone compounds such as Omnirad 127, 184, 1173, and 2959 from IGM Resins; aminoalkylphenone compounds such as Omnirad 907, 369E, and 379EG from IGM Resins; and acylphosphine oxide compounds such as Omnirad 819 and TPO from IGM Resins.

[0089] The photopolymerization initiator content is preferably 0.5 to 20% by mass, and more preferably 1 to 10% by mass, in the photosensitive composition for inkjet inks. Adding an appropriate amount further improves photocurability.

[0090] <Solvent> The photosensitive composition for inkjet inks may contain a solvent to suppress viscosity and improve leveling during coating. The solvent content is preferably 0.1 to 5.0% by mass, more preferably 0.2 to 4.0% by mass, of the photosensitive composition for inkjet inks. Including an appropriate amount further improves discharge stability.

[0091] The boiling point of the solvent is preferably 120°C to 300°C, and more preferably 140°C to 270°C. The solvent is preferably a glycol compound, such as a monoacetate, monoalkyl ether, or dialkyl ether. Examples of solvents include tetraethylene glycol dialkyl ether, ethylene glycol monobutyl ether acetate, and diethylene glycol diethyl ether.

[0092] <Sensitizer> The photosensitive compositions for inkjet inks described herein may contain a sensitizer. Preferred sensitizers include thioxanthone derivatives, Michler ketone derivatives, and carbazole derivatives. Specifically, examples include 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 1-chloro-4-propoxythioxanthone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(ethylmethylamino)benzophenone, N-ethylcarbazole, 3-benzoyl-N-ethylcarbazole, and 3,6-dibenzoyl-N-ethylcarbazole. The sensitizer content is preferably 0.1 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the photopolymerization initiator.

[0093] <Polymerization inhibitors> The photosensitive compositions for inkjet inks described herein may contain polymerization inhibitors. This further improves storage stability over time, ejection stability after time, and storage stability within inkjet recording devices. Examples of polymerization inhibitors include hindered phenol compounds, phenothiazine compounds, hindered amine compounds, and phosphorus compounds. Examples of polymerization inhibitors include 4-methoxyphenol, hydroquinone, methylhydroquinone, t-butylhydroquinone, 2,6-di-t-butyl-4-methylphenol, phenothiazine, and aluminum salts of N-nitrosophenylhydroxylamine. The content of the polymerization inhibitor in the photosensitive composition for inkjet ink is preferably 0.01 to 2% by mass.

[0094] <Antioxidant> The photosensitive compositions for inkjet inks described herein may contain antioxidants. This suppresses yellowing of the coating film formed from the composition and improves its transmittance.

[0095] Examples of antioxidants include hindered phenol, hindered amine, phosphorus, sulfur, and hydroxylamine compounds. In this invention, it is preferable that the antioxidant is a compound that does not contain halogen atoms.

[0096] Among these, from the viewpoint of achieving both the transmittance and sensitivity of the coating film, antioxidants of hindered phenol, hindered amine, phosphorus, and sulfur compounds are preferred.

[0097] Antioxidants can be used alone or in combination of two or more types.

[0098] The antioxidant content is preferably 0.5 to 5.0% by mass of 100% by mass of the non-volatile content of the photosensitive composition for inkjet inks, which further improves transmittance.

[0099] <Surface modifier> In this specification, a surface modifier refers to a substance that, when added, reduces the surface tension of the ink. Examples of surface modifiers include silicone-based surface modifiers, fluorine-based surface modifiers, acrylic-based surface modifiers, and acetylene glycol-based surface modifiers. From the viewpoint of surface tension reduction ability and compatibility with photopolymerizable compounds, it is preferable to use a silicone-based surface modifier.

[0100] Specific examples of silicone-based surface modifiers include modified dimethylsiloxane skeletons. Among these, polyether-modified siloxane-based surface modifiers are preferred. The polyether may be, for example, polyethylene oxide and polypropylene oxide. In one embodiment of the present invention, commercially available polyether-modified silicone surfactants can be used. Examples of representative products that can be preferably used include polyether-modified siloxanes such as BYK378, 348, and 349 from Bic Chemie, and polyether-modified polydimethylsiloxanes such as BYK-UV3500 and UV3510. Also, polyether-modified siloxane copolymers such as TEGO® GLIDE450, 440, 435, 432, 410, 406, 130, 110, and 100 from Evonik Degussa can be mentioned. Among these, polyether-modified silicone surface modifiers such as BYK-331, 378, 348, UV3510, TEGO GLIDE 450, 440, 432, and 410 are preferred from the viewpoint of achieving good image quality.

[0101] The content of the silicone-based surface modifier is preferably 0.15.0% by mass in the photosensitive composition for inkjet inks. Including an appropriate amount further improves leveling properties and storage stability.

[0102] <Storage stabilizer> The photosensitive compositions for inkjet inks described herein may contain storage stabilizers. This suppresses changes in the viscosity of the composition over time. Examples of storage stabilizers include benzyl trimethyl chloride, quaternary ammonium chlorides such as diethylhydroxyamine, organic acids such as lactic acid and oxalic acid and their methyl ethers, organic phosphines such as t-butyl pyrocatechol, tetraethylphosphine, and tetraphenylphosphine, and phosphates. The content of the storage stabilizer is preferably 0.1 to 10% by mass per 100 parts by mass of the colorant containing phthalocyanine pigment.

[0103] <Other ingredients> The photosensitive composition for inkjet inks of the present invention may contain other components in addition to those mentioned above. Examples of other components include binder resins, thermal crosslinking agents, curing agents, curing accelerators, acid generators, curing catalysts, chain transfer agents, silane coupling agents, and near-infrared absorbers. The content of these other components can be appropriately set within a range that solves the problems of the present invention.

[0104] <Method for preparing pigment dispersions and photosensitive compositions for inkjet inks> This specification describes how to prepare an inkjet ink pigment dispersion by mixing a phthalocyanine pigment, a dispersant, and a polymerizable compound, and then performing a dispersion treatment. Next, a photopolymerization initiator and the like are added to the inkjet ink pigment dispersion and mixed. Furthermore, the viscosity can be adjusted by adding a polymerizable compound as needed. The timing of adding each material is arbitrary, and the dispersion treatment may be performed multiple times as required.

[0105] Examples of distributed processing machines include two-roll mills, three-roll mills, ball mills, horizontal sand mills, vertical sand mills, annular bead mills, or attritors.

[0106] <Average dispersed particle size> The average dispersed particle diameter (average secondary particle diameter) of pigment particles in pigment dispersions and photosensitive compositions is preferably 30 to 300 nm, and more preferably 40 to 250 nm. Having an appropriate particle diameter makes it easier to obtain pigment dispersions for inkjet inks with high storage stability.

[0107] The method for measuring the average dispersed particle diameter (secondary particle diameter) uses, for example, Nikkiso's Microtrac UPA-EX150, which employs dynamic light scattering (FFT power-spectrum method), with particle permeability set to absorption mode, particle shape to non-spherical, and D50 particle diameter as the average diameter. The diluent solvent used for measurement is the same solvent used for dispersion, and it is preferable to measure immediately after sample preparation of ultrasonically treated samples to obtain results with less variation.

[0108] <Removal of coarse particles> The pigment dispersion for inkjet ink is preferably processed by means of centrifugal separation, filtration using a sintered filter or membrane filter to remove coarse particles of 5 μm or larger, preferably coarse particles of 1 μm or larger, more preferably coarse particles of 0.5 μm or larger, and any mixed dust. The pigment dispersion for inkjet ink of the present invention preferably contains substantially no particles of 0.5 μm or larger, and more preferably contains no particles of 0.3 μm or smaller.

[0109] <Inkjet Ink> The photosensitive composition for inkjet inks of the present invention is preferably prepared by appropriately adjusting its composition to create an inkjet ink. Various applications for the inkjet ink are possible, but inkjet ink for color filters is preferred.

[0110] The inkjet ink of the present invention is preferably adjusted to have a viscosity of 5 to 50 mPa·s at 25°C. Within this viscosity range, excellent followability and stability of the ink ejection are achieved.

[0111] The film thickness of the inkjet ink is preferably 2 to 30 μm, more preferably 3 to 25 μm, and even more preferably 4 to 20 μm. An appropriate film thickness improves both color development and curing properties.

[0112] The active energy ray used to cure the inkjet ink can be any energy ray that can affect the electron orbitals of the irradiated object and induce polymerization reactions such as radicals, cations, and anions. While not particularly limited, specific examples include electron beams, ultraviolet light, and infrared light. In this invention, ultraviolet light is preferred.

[0113] Examples of ultraviolet light sources include high-pressure mercury lamps, metal halide lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, ultraviolet lasers, and LEDs. Among these, high-pressure mercury lamps, metal halide lamps, and LEDs are preferred in terms of convenience and cost. The emission maximum wavelength is preferably 200 to 600 nm, more preferably 300 to 450 nm, even more preferably 320 to 420 nm, and particularly preferably ultraviolet light in the range of 340 to 400 nm.

[0114] <Cured product> The cured product of the present invention is formed using the inkjet ink composition of the present invention.

[0115] <Color Filter> The color filter of the present invention comprises a substrate and a cured product of the present invention. The color filter of the present invention comprises, as an RGB system, at least one red filter segment, at least one green filter segment, and at least one blue filter segment. Furthermore, in addition to the above three color filter segments, a yellow filter segment may be included. In addition, as a CMY system, a cyan color filter, a magenta color filter, and a yellow color filter may be included.

[0116] <How to manufacture color filters> The color filter of the present invention can be manufactured by printing.

[0117] The formation of filter segments by printing is a low-cost and highly mass-producible method for manufacturing color filters, as it allows for patterning by printing a photosensitive composition prepared as an inkjet ink. Furthermore, advancements in printing technology enable the printing of fine patterns with high dimensional accuracy and smoothness. For printing, it is preferable to use a composition that prevents the ink from drying or solidifying on the printing plate or blanket.

[0118] <Solid-state image sensor> The solid-state image sensor of the present invention has the color filter. The form used for the solid-state image sensor is not particularly limited, but for example, it has a substrate on which a plurality of photodiodes constituting the light-receiving area of ​​the solid-state image sensor (CCD image sensor, CMOS image sensor, etc.) and transfer electrodes made of polysilicon or the like are provided, a light-shielding film with an opening only for the light-receiving portion of the photodiode is provided on the photodiode and transfer electrodes, a device protective film made of silicon nitride or the like is provided on the light-shielding film so as to cover the entire surface of the light-shielding film and the light-receiving portion of the photodiode, and a filter is provided on the device protective film. Furthermore, it may have a configuration in which a light-gathering means (for example, a microlens, etc.; the same applies hereinafter) is provided on the device protective film and below the filter (on the side closer to the substrate), or a configuration in which the light-gathering means is provided on the filter. In addition, the filter may have a structure in which a hardened film forming each colored pixel is embedded in a space partitioned by partitions, for example in a grid pattern. In this case, it is preferable that the partitions have a low refractive index with respect to each colored pixel. The imaging device equipped with the solid-state image sensor of the present invention can be used in a variety of applications, such as digital cameras, electronic devices with imaging functions (smartphones, tablet terminals, etc.), in-vehicle cameras, surveillance cameras, and optical sensors.

[0119] <Image display device> The image display device of the present invention has the color filter. Examples of image display devices include liquid crystal displays and organic EL displays. The form used in the image display device is not particularly limited, but it can be used as a color filter, black matrix, light-shielding filter, infrared cut filter, or infrared transmission filter. The form used in the image display device is not particularly limited, as long as it functions as an image display device. For example, the configuration described in "Next-Generation Liquid Crystal Display Technology" (by Tatsuo Uchida, published by Kogyo Chosakai Co., Ltd. in 1994) is one such example. For definitions of image display devices and details of various image display devices, see, for example, "Electronic Display Devices" (by Akio Sasaki, Kogyo Chosakai Co., Ltd., published in 1990) and "Display Devices" (by Junsho Ibuki, Sangyo Tosho Co., Ltd., published in 1989).

[0120] [Example of an embodiment] Examples of embodiments of the present invention are given below. The present invention is not limited to the following.

[0121] <1> The pigment dispersion for inkjet inks of the present invention comprises a phthalocyanine pigment, a polymerizable compound, and a dispersant. The dispersant comprises a first polymerized moiety, a second polymerized moiety, and an acid dianhydride residue, wherein the first polymerized moiety comprises a cyclic ester polymer, and the second polymerized moiety comprises a vinyl polymer without an acid group, in a pigment dispersion for inkjet inks. <2> The acid value of the aforementioned dispersant is 10-200 mgKOH / g. <1> Pigment dispersion for inkjet inks. <3> The aforementioned acid dihydrate residue is a residue having an aromatic ring. <1> or <2> Pigment dispersion for inkjet inks. <4> The aforementioned cyclic ester polymer is a polymer containing polylactone. <1> ~ <3> A pigment dispersion for any inkjet ink. <5> Furthermore, including pigment derivatives, <1> ~ <4> A pigment dispersion for any inkjet ink. <6> <1> ~ <5> A composition for inkjet inks comprising any inkjet ink pigment dispersion and a photopolymerization initiator. <7> <6> A cured product of an inkjet ink composition. <8> substrate, and <7> An image display device equipped with a cured product. <9> substrate, and <7> A solid-state image sensor comprising a cured material. [Examples]

[0122] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. Note that "parts" refers to "parts by mass" and "%" refers to "percentage by mass".

[0123] (Average molecular weight (Mw) of the resin during polymerization) Measurements were performed using gel permeation chromatography (GPC) equipped with an RI detector. An HLC-8220GPC (Tosoh Corporation) was used, with two separation columns connected in series. Both columns were packed with two TSK-GELSUPERHZM-N columns. Measurements were performed at an oven temperature of 40°C, using THF solution as the eluent, and a flow rate of 0.35 ml / min. The sample was dissolved in a 1 wt% solution of the above eluent and injected in 20 microliters. Molecular weights are all polystyrene equivalents.

[0124] (Acid value of resin) Approximately 1 g of the substance to be measured for acid value was weighed, 30 g of pyridine and 1 g of water were added, and the mixture was stirred for 10 minutes. Then, a 0.1 N potassium hydroxide ethanol solution was used as the titrant, and the mixture was titrated using a potentiometric titrator (Kyoto Electronics Manufacturing Co., Ltd., device name "Potentiometric Automatic Titrator AT-710M") to measure the acid value of the resin and calculate the acid value per unit of non-volatile content.

[0125] (Reaction rate of acid dianhydride group) 0.5-1.0 g of the sample was mixed with 30 ml of 1,4-dioxane and water (10:1) and stirred to dissolve uniformly. Then, 10 ml of the hexylamine preparation solution described below was added and stirred for 5 minutes to prepare the measurement sample solution. Next, a 0.02 mol / L perchloric acid (1,4-dioxane) solution was used as the titrant and the titration was performed using an automatic titrator ("COM-555," manufactured by Hiranuma Sangyo Co., Ltd.) to determine the titration volume (B ml). Similarly, 10 ml of the hexylamine preparation solution alone was titrated to determine the blank titration volume (C ml). Finally, the reaction rate of the acid dianhydride group of the resin was calculated using the formula below. Hexylamine preparation solution: A mixture of 0.79 g of hexylamine and 400 g of 1,4-dioxane. S: Sample volume (g) A: Amount of amine compound contained in the sample (mmol / g) = Amount of amine in the resin solids (%) / Molecular weight of amine The measured acid dianhydride value (mmol / g) of the resin = {(blank titration volume C × 0.02) - (sample titration volume B × 0.02 - S × non-volatile content concentration × A)} / (S × non-volatile content concentration) The value of dianhydride in the preparation (mmol / g) = Amount of dianhydride in the acidic dispersant (wt%) / Molecular weight of dianhydride × Number of dianhydride groups in the dianhydride Reaction rate of acid dianhydride group (mol%) = {1 - (measured acid dianhydride price / input acid dianhydride price)} × 100

[0126] [Manufacturing Example 1] Synthesis of Dispersant 1 In a reaction vessel equipped with a gas inlet tube, thermometer, condenser, and stirrer, 15.9 parts of benzyl alcohol, 84.1 parts of ε-caprolactone, and 0.1 parts of monobutyltin oxide as a catalyst were charged. After purging with nitrogen gas, the mixture was heated and stirred at 120°C for 4 hours. Non-volatile content measurement confirmed that more than 98% had reacted, yielding a cyclic ester polymer. Next, the reaction product was cooled to 40°C, and 100.0 parts of 2-methoxyethyl acrylate and 6.8 parts of 3-mercapto-1,2-propanediol (1-thioglycerol) were added and the mixture was thoroughly stirred. Furthermore, 0.10 g of dimethyl 2,2'-azobis(2-methylpropionate) was added as an initiator, the temperature was raised to 85°C, and the reaction was carried out for 7 hours. After confirming that the non-volatile content reached 95% or more, a vinyl polymer was obtained (however, it is a mixture with a cyclic ester polymer).

[0127] Next, while maintaining the internal temperature at 85°C, 22.3 parts of pyromellitic dianhydride were added to the above reaction product, and the temperature was raised to 100°C while stirring. Subsequently, 0.13 parts of N,N-dimethylbenzylamine were added, and the reaction was carried out at 120°C for 3 hours, followed by a further reaction at 100°C for 2 hours. By measuring the reaction rate of the acid dianhydride groups, it was confirmed that more than 95% of the acid anhydride had been half-esterified, and dispersant 1 was obtained. The obtained dispersant had a weight-average molecular weight of 4,400 and an acid value of 47 mgKOH / g.

[0128] [Manufacturing Examples 2-10] Synthesis of Dispersants 2-10 Dispersants 2 to 10 were obtained by synthesis in the same manner as the production example of dispersant 1, except that the raw materials and quantities listed in Table 1 were used.

[0129] [Table 1]

[0130] The abbreviations used in Table 1 are as follows: PMA... Pyromellitic dianhydride BTA···1,2,3,4-butanetetracarboxylic dianhydride BPDA···3,3',4,4'-biphenyltetracarboxylic acid dianhydride 2-MTA···2-methoxyethyl acrylate MMA... Methyl methacrylate OXMA···(3-ethyloxetan-3-yl)methyl methacrylate MAA... Methacrylic acid

[0131] <Preparation of pigment dispersions for inkjet inks> [Example 1] Pigment dispersion for inkjet inks (d-1) A pigment dispersion was prepared by uniformly stirring and mixing a mixture of the following compositions using a high-speed mixer or the like, and then dispersing the resulting mill base in a horizontal sand mill for approximately one hour. CI Pigment Green 36 13.5 parts Pigment derivative 1 1.5 parts Dispersant 1 7.5 parts Dipropylene glycol diacrylate (DPGDA) 47.5 parts

[0132] Pigment derivative 1 [ka]

[0133] [Examples 2-21, Comparative Examples 1-3] (Pigment dispersions (d-2) to (d-24)) Pigment dispersions (d-2) to (d-24) were prepared in the same manner as pigment dispersion (d-1), except that the phthalocyanine pigment, pigment derivative, dispersant, and polymerizable compound were changed to the compositions and amounts shown in Table 2. The abbreviations used in the table are as follows: • "SP32000"; Basic pigment dispersant "Solspers 32000" (manufactured by Lubrizol Japan Co., Ltd.) <Polymerizable compound (C)> • DPGDA: Dipropylene glycol diacrylate (BASF's "Laro") mer DPGDA」) • PEA: Phenoxyethyl acrylate (Sartomer "SR339")

[0134] Pigment derivative 2 [ka]

[0135] Pigment derivative 3 [ka]

[0136] Pigment derivative 4 [ka]

[0137] <Evaluation method for photosensitive compositions for inkjet inks> [Storage stability] The viscosity of the obtained photosensitive inkjet ink composition was measured using an E-type viscometer (ELD-type viscometer manufactured by Toki Sangyo Co., Ltd.) at 25°C and a rotation speed of 20 rpm, and this was defined as the initial viscosity. Furthermore, an accelerated aging test was performed at 60°C for 2 weeks, and the accelerated viscosity over time was measured. The rate of change due to accelerated aging was calculated as accelerated viscosity over time / initial viscosity, and evaluated according to the following criteria. ◎ Change rate less than 5% (Excellent) ○ Rate of change 5% or more but less than 10% (good) △ Change rate between 10% and less than 20% (practical) × Change rate of 20% or more (not practical)

[0138] [Particle size change rate] The obtained photosensitive compositions for inkjet inks were diluted 200 to 1000 times with methyl ethyl ketone, and the volume-based D50% average particle size (D1) was measured using a Microtrac UPA150 (Nikkiso, wet particle size distribution analyzer). Next, 100 ml of each photosensitive composition was placed in a sample bottle to prevent evaporation, sealed, and stored in a 60°C constant temperature bath for one week. After storage, the volume-based D50% average particle size (D2) was measured in the same manner as above, the rate of change in average particle size was calculated according to the formula below, and the rate of change in particle size was evaluated according to the evaluation criteria below. Particle size change rate = {(D2-D1) / D1} × 100%) ◎ Particle size change rate is less than 5% (Excellent) ○ Particle size change rate is 5% or more but less than 10% (good) △ Particle size change rate is 10% or more but less than 30% (suitable for practical use) × The particle size change rate is 30% or more (not practical).

[0139] [Table 2]

[0140] Next, a yellow pigment dispersion for inkjet inks was prepared in the same manner as in Example 1 for use in color matching of a photosensitive composition for inkjet inks. <Yellow pigment dispersion for inkjet ink (y-1)> CI Pigment Yellow 150 13.5 parts Pigment derivative 3 1.5 parts Dispersant 1 7.5 parts Dipropylene glycol diacrylate (DPGDA) 47.5 parts

[0141] <Yellow pigment dispersion for inkjet ink (y-2)> CI Pigment Yellow 139 13.5 parts Pigment derivative 3 1.5 parts Dispersant 1 7.5 parts Dipropylene glycol diacrylate (DPGDA) 47.5 parts

[0142] <Yellow pigment dispersion for inkjet ink (y-3)> CI Pigment Yellow 231 13.5 parts Pigment derivative 2 1.5 parts Dispersant 1 7.5 parts Dipropylene glycol diacrylate (DPGDA) 47.5 parts

[0143] [Example 22] Photosensitive composition for inkjet inks (D-1) A mixture of the following compositions was uniformly stirred and mixed using a high-speed mixer or the like. The composition was then filtered through a PTFE filter with a pore diameter of 0.5 microns to remove dust and coarse particles, thereby preparing a photosensitive composition (D-1) for inkjet ink. Pigment dispersion for inkjet ink (d-1) 9.0 parts Yellow pigment dispersion for inkjet ink (y-1) 6.0 parts VEEA 72.9 copies BHT 1.0 part Phenothiazine 1.0 part BYK-UV3510 0.1 part OMNIRAD TPO-L 2.5 parts OMNIRAD819 Part 2.5 KAYACURE BMS 2.5 parts IlgaCure OXE04 2.5 parts

[0144] [Examples 23-44, Comparative Examples 4-6] Photosensitive compositions for inkjet inks (D-2) to (D-23), (D-25) to (D-27) Except for changing the pigment dispersion for inkjet ink (d-1) and the yellow pigment dispersion for inkjet ink (y-1) as described in Tables 3-1 to 3-3, the photosensitive compositions for inkjet ink (D-2) to (D-23) and (D-25) to (D-27) were prepared in the same manner as the photosensitive composition for inkjet ink (D-1).

[0145] [Example 45] Photosensitive composition for inkjet inks (D-24) A mixture of the following components was uniformly stirred and mixed using a high-speed mixer or the like. The mixture was then filtered through a PTFE filter with a pore diameter of 0.5 microns to remove dust and coarse particles, thereby preparing a photosensitive composition for inkjet ink (D-24). Pigment dispersion for inkjet ink (d-1) 8.5 parts Pigment dispersion for inkjet ink (d-15) 0.5 parts Yellow pigment dispersion for inkjet ink (y-1) 6.0 parts VEEA 72.9 copies BHT 1.0 part Phenothiazine 1.0 part BYK-UV3510 0.1 part OMNIRAD TPO-L 2.5 parts OMNIRAD819 Part 2.5 KAYACURE BMS 2.5 parts IlgaCure OXE04 2.5 parts

[0146] <Evaluation method for photosensitive compositions for inkjet inks> The obtained photosensitive compositions for inkjet inks were printed using a single-pass inkjet printer (Trytech One Pass Jet) equipped with a Kyocera head (KJ4A), an inkjet ejection mechanism, a mechanism for transporting the ink-impregnated substrate at a desired speed, and a mechanism for subsequent irradiation with a UV lamp. The prints were conducted under conditions of 14 pl droplet size and 600 × 600 dpi, and various properties were evaluated. An experimental 385 nm UV-LED irradiator (CCS Corporation) was used as the exposure device, with an exposure energy of 1000 mJ / cm². 2 The material was cured by irradiation under the specified exposure conditions, and a sample of the cured material was prepared. The printing speed and printed image were adjusted as appropriate according to each evaluation.

[0147] [Storage stability] The viscosity of the obtained photosensitive composition was measured using an E-type viscometer (ELD-type viscometer manufactured by Toki Sangyo Co., Ltd.) at 25°C and a rotation speed of 20 rpm, and this was defined as the initial viscosity. Furthermore, an accelerated aging test was performed at 60°C for 2 weeks, and the accelerated viscosity over time was measured. The rate of change due to accelerated aging was calculated as accelerated viscosity over time / initial viscosity, and evaluated according to the following criteria. ◎ Change rate less than 5% (Excellent) ○ Rate of change 5% or more but less than 10% (good) △ Change rate between 10% and less than 20% (practical) × Change rate of 20% or more (not practical)

[0148] [Discharge stability] The prepared photosensitive composition was used to print a nozzle check pattern using an inkjet printer. After 100,000 prints, the nozzle check pattern was printed again, and the ejection performance was evaluated based on the number of nozzle failures. The evaluation criteria were as follows. The conveyor speed was set to 35 m / min. ◎ No nozzle clogging after 100,000 prints (Excellent) ○ After 100,000 prints, 1-2 nozzle failures occurred (good). △ After 100,000 prints, 3-5 nozzles were found to be missing (still usable). × More than 6 nozzle failures after 100,000 prints (unusable).

[0149] [Lightfastness test] The prepared photosensitive compositions for inkjet inks (D-1 to D-27) were coated onto a transparent glass substrate using a spin coater, dried at 70°C for 20 minutes, and then exposed to light at an integrated intensity of 150 mJ / cm² using an ultra-high pressure mercury lamp. 2 Ultraviolet exposure was performed. The cured material was prepared to have a film thickness of 5.0 μm. Subsequently, the initial chromaticity ([L*(1), a*(1), b*(1)]) of the obtained coating film under a C light source was measured using a micro-spectrophotometer (Olympus Optical Co., Ltd. "OSP-SP100"). An ultraviolet cut filter (HOYA Corporation "COLOREDOPTICALGLASSL38") was placed over the obtained cured surface and exposed to 470 W / m². 2After irradiating with ultraviolet light using a xenon lamp for 100 hours, the chromaticity ([L*(2), a*(2), b*(2)]) under the C light source was determined based on the following formula. The evaluation criteria are as follows. ΔEab*=√((L*(2)-L*(1))2+(a*(2)-a*(1))2+( b*(2)-b*(1))2) (Evaluation Criteria) ◎: ΔEab* is less than 3 (Excellent) ○: ΔEab* is 3 or greater and less than 5 (Good) △: ΔEab* is 5 or greater and less than 7 (practical) ×: ΔEab* is between 7 and 10 (not practical)

[0150] The abbreviations in Table 3 are as follows: <Polymerizable compound> • VEEA: 2-(2-vinyloxyethoxy)ethyl acrylate, manufactured by Nippon Shokubai Co., Ltd. <Antioxidant> ·BHT: “H-BHT” manufactured by Honshu Kagaku Co., Ltd. <Polymerization inhibitors> • Phenothiazine: "Phenothiazine" manufactured by Seiko Chemical Co., Ltd. <Leveling agent> • BYK-UV3510: Polyether-modified polydimethylsiloxane manufactured by BYK Chemie. <Photopolymerization initiator> • OmniradTPO-L: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by IGMresins. • Omnirad819: Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, manufactured by IGMresins. • KAYACUREBMS: 4-benzoyl-4'-methyl-diphenyl sulfide manufactured by Nippon Kayaku Co., Ltd. • Irgacure OXE04: Manufactured by BASF Japan, oxime ester-based photopolymerization initiator.

[0151] [Table 3]

[0152] As shown in Table 3, Examples 1-21 exhibited good viscosity change rates and particle size change rates. Furthermore, Examples 22-45 showed good storage stability, discharge stability, and lightfastness of the cured product. Thus, it was confirmed that the pigment dispersions for inkjet inks in these examples can solve the problems of the present invention.

Claims

1. A pigment dispersion for inkjet inks comprising a phthalocyanine pigment, a polymerizable compound, and a dispersant, The dispersant comprises a first polymerized moiety, a second polymerized moiety, and an acid dianhydride residue, wherein the first polymerized moiety comprises a cyclic ester polymer, and the second polymerized moiety comprises a vinyl polymer without an acid group, in a pigment dispersion for inkjet inks.

2. The pigment dispersion for inkjet ink according to claim 1, wherein the acid value of the dispersant is 10 to 200 mg KOH / g.

3. The pigment dispersion for inkjet ink according to claim 1, wherein the acidic dihydrate residue is a residue having an aromatic ring.

4. The pigment dispersion for inkjet ink according to claim 1, wherein the cyclic ester polymer is a polymer containing polylactone.

5. The pigment dispersion for inkjet ink according to claim 1, further comprising a pigment derivative.

6. A composition for inkjet ink comprising a pigment dispersion for inkjet ink according to any one of claims 1 to 5, and a photopolymerization initiator.

7. A cured product of the inkjet ink composition according to claim 6.

8. An image display device comprising a substrate and a cured product according to claim 7.

9. A solid-state image sensor comprising a substrate and a cured product according to claim 7.

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