Red pigment dispersion resist composition for color filter

Abstract

To provide a red pigment dispersion resist composition for a color filter which can suppress lowering of brightness, while achieving reduction in a contrast reduction amount before and after post-baking.SOLUTION: A red pigment dispersion resist composition for a color filter contains a red pigment, a basic group-containing pigment dispersant, an acidic group-containing pigment dispersion aid, an epoxy resin, an alkali-soluble resin, a photopolymerizable compound, a photopolymerization initiator, and a solvent, wherein the epoxy resin is an epoxy resin having constitutional units derived from a polyfunctional maleimide compound having two or more maleimide groups and a benzoxazine compound, and 0.5 to 7 pts.mass of the epoxy resin is contained with respect to 100 pts.mass of the red pigment.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a red pigment-dispersed resist composition for a color filter. [Background technology]

[0002] A technology for forming high-definition color filters is essential for realizing high image quality in liquid crystal display devices. Color filters include those in which fine stripes of two or more different hues are arranged in parallel on the surface of a transparent substrate such as glass, and those in which fine pixels are arranged in a fixed array vertically and horizontally. The pixel size is as minute as several tens to several hundreds of μm, but it is necessary to arrange the pixels in order in a predetermined order for each hue. Furthermore, the pixels of each hue are also required to have basic performances of high color purity and visible light transmittance, as well as high contrast.

[0003] 2. Description of the Related Art As the applications of liquid crystal display devices become more diverse, organic pigments are widely used as color materials for pixels from the standpoint of reliability, such as heat resistance and light resistance (Patent Document 1).

[0004] In recent years, there has been an increasing demand for higher definition, power saving and higher brightness of liquid crystal display devices, and there is a demand for higher brightness and higher contrast of color filters. In order to solve these problems, it has been proposed to add a multifunctional epoxy compound (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-162722 A [Patent Document 2] JP 2010-85770 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the polyfunctional epoxy compound described in Patent Document 2 is used, the crosslink density increases and the decrease in contrast before and after post-baking can be reduced, but the brightness may decrease due to yellowing. Therefore, a different red pigment dispersion resist composition for color filters has been desired.

[0007] Therefore, the present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a red pigment-dispersed resist composition for color filters that can suppress a decrease in luminance while realizing a reduction in the amount of contrast reduction before and after post-baking. [Means for solving the problem]

[0008] That is, the present invention relates to a red pigment-dispersed resist composition for color filters, which comprises a red pigment, a basic group-containing pigment dispersant, an acidic group-containing pigment dispersing aid, an epoxy resin, an alkali-soluble resin, a photopolymerizable compound, a photopolymerization initiator, and a solvent, wherein the epoxy resin is an epoxy resin having structural units derived from a polyfunctional maleimide compound having two or more maleimide groups, and a benzoxazine compound, and the epoxy resin is contained in an amount of 0.5 to 7 parts by mass relative to 100 parts by mass of the red pigment.

[0009] In the red pigment dispersion resist composition for color filters of the present invention, the acidic group-containing pigment dispersing aid is preferably a sulfonic acid group-containing pigment dispersing aid.

[0010] In addition, in the red pigment dispersion resist composition for color filters of the present invention, the basic group-containing pigment dispersant is preferably an acrylic block copolymer comprising a block having a basic group and a block not having a basic functional group. Effect of the Invention

[0011] The red pigment-dispersed resist composition for color filters of the present invention uses, as the epoxy resin, specific amounts of a polyfunctional maleimide compound having two or more maleimide groups, and an epoxy resin having a structural unit derived from a benzoxazine compound, thereby making it possible to suppress a decrease in brightness while realizing a reduction in the amount of decrease in contrast before and after post-baking. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Red pigment dispersion resist composition for color filters> The red pigment-dispersed resist composition for color filters of the present invention (hereinafter, also simply referred to as "resist composition") contains a red pigment, a basic group-containing pigment dispersant, an acidic group-containing pigment dispersing aid, an epoxy resin, an alkali-soluble resin, a photopolymerizable compound, a photopolymerization initiator, and a solvent, and the epoxy resin is an epoxy resin having structural units derived from a polyfunctional maleimide compound having two or more maleimide groups, and a benzoxazine compound.

[0013] <Red pigment> Examples of the red pigment include dianthraquinonyl pigments, diketopyrrolopyrrole pigments, condensed azo pigments, isoindoline pigments, perinone pigments, perylene pigments, azo pigments having a heterocycle, quinacridone pigments, dibromoanthanthrone pigments, and benzimidazolone pigments. From the viewpoint of use as a red pigment dispersion for a color filter for television applications, at least one red pigment selected from the group consisting of CI Pigment Red 166, CI Pigment Red 177, CI Pigment Red 242, and CI Pigment Red 254, as color index names, is preferred.

[0014] The content of the red pigment is preferably from 5 to 80 mass %, and more preferably from 20 to 50 mass %, of the total solid content of the red pigment dispersion resist composition for color filters.

[0015] <Basic group-containing pigment dispersant> The basic group-containing pigment dispersant may be any dispersible pigment capable of dispersing the red pigment, and any known basic group-containing pigment dispersant used in a red pigment-dispersed resist composition for color filters may be used. Examples of the basic group-containing pigment dispersant include the following. (1) A reaction product of an amino group and / or an imino group of a polyamine compound (e.g., a poly(lower) alkylene amine, such as polyallylamine, polyvinylamine, or polyethylene polyimine) with at least one member selected from the group consisting of polyesters, polyamides, and polyesteramides having a free carboxyl group. (2) A carbodiimide compound having, in the molecule, at least one side chain selected from the group consisting of a polyester side chain, a polyether side chain, and a polyacrylic side chain, and at least one basic nitrogen-containing group. (3) Reaction products of low molecular weight amino compounds such as poly(lower) alkyleneimines and methyliminobispropylamine with polyesters having free carboxyl groups. (4) A reaction product obtained by sequentially reacting an isocyanate group of a polyisocyanate compound with an alcohol such as methoxypolyethylene glycol, a polyester having one hydroxyl group such as caprolactone polyester, a compound having two to three isocyanate group-reactive functional groups, and an aliphatic or heterocyclic hydrocarbon compound having an isocyanate group-reactive functional group and a tertiary amino group. (5) A reaction product obtained by reacting an acrylate polymer having an alcoholic hydroxyl group with a polyisocyanate compound and a hydrocarbon compound having an amino group. (6) A reaction product obtained by adding a polyether chain to a low molecular weight amino compound. (7) A reaction product obtained by reacting a compound having an isocyanate group with a compound having an amino group. (8) A reaction product obtained by reacting a polyepoxy compound with a linear polymer having a free carboxyl group and an organic amine compound having one secondary amino group. (9) A reaction product between a polycarbonate compound having at one end a functional group capable of reacting with an amino group and a polyamine compound. (10) A copolymer of at least one selected from methacrylic acid esters or acrylic acid esters, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, stearyl methacrylate, benzyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, stearyl acrylate, and benzyl acrylate, at least one basic group-containing polymerizable monomer, such as acrylamide, methacrylamide, N-methylolamide, vinylimidazole, vinylpyridine, and a monomer having an amino group and a polycaprolactone skeleton, and at least one styrene, styrene derivative, and other polymerizable monomer. (11) Acrylic block copolymers comprising a block having a basic group such as a tertiary amino group or a quaternary ammonium base and a block having no basic functional group. (12) A pigment dispersant obtained by subjecting a polyallylamine to a Michael addition reaction with a polycarbonate compound. (13) A carbodiimide compound having at least one polybutadiene chain and at least one basic nitrogen-containing group. (14) A carbodiimide compound having at least one side chain having an amide group and at least one basic nitrogen-containing group in the molecule. (15) Polyurethane compounds having structural units having ethylene oxide chains and propylene oxide chains, and having amino groups quaternized with a quaternizing agent. (16) A compound obtained by reacting an isocyanate group of an isocyanate compound having an isocyanurate ring in the molecule with an active hydrogen group of a compound having an active hydrogen group in the molecule and having a carbazole ring and / or an azobenzene skeleton, wherein the number of carbazole rings and azobenzene skeletons in the molecule of the compound is 15 to 85% of the total number of isocyanate groups derived from the isocyanate compound having an isocyanurate ring and urethane bonds and urea bonds generated by the reaction of the isocyanate groups with the active hydrogen groups, and the like.

[0016] From the viewpoint of favorably exhibiting pigment dispersibility, the basic group-containing pigment dispersant is preferably an acrylic resin-based polymeric pigment dispersant containing nitrogen atoms, and more preferably an acrylic block copolymer consisting of a block having a basic group such as a tertiary amino group or a quaternary ammonium base and a block having no basic functional group. The acrylic resin-based polymeric pigment dispersant is more preferably at least one of an AB block copolymer and a BAB block copolymer consisting of an A block having at least one of a quaternary ammonium base and an amino group in the side chain and a B block having no quaternary ammonium base and no amino group. The basic group-containing pigment dispersant can be used alone or in combination of two or more kinds.

[0017] From the viewpoint of pigment dispersibility, the basic group-containing pigment dispersant preferably has an amine value of 5 to 50 mgKOH / g, more preferably 5 to 35 mgKOH / g. The amine value indicates the total amount of free base and base, and is expressed as mg of potassium hydroxide equivalent to hydrochloric acid required to neutralize 1 g of sample.

[0018] The content of the basic group-containing pigment dispersant is preferably 1 to 100 parts by mass, and more preferably 10 to 60 parts by mass, relative to 100 parts by mass of the red pigment. If the content of the basic group-containing pigment dispersant is less than 1 part by mass relative to 100 parts by mass of the red pigment, the pigment dispersion effect may decrease, whereas if the content exceeds 100 parts by mass relative to 100 parts by mass of the red pigment, the developability may decrease.

[0019] <Acidic group-containing pigment dispersing agent> The acidic group-containing pigment dispersion aid may be any agent capable of dispersing the red pigment, and examples of such agents include compounds (dye derivatives having acidic groups) in which acidic groups such as carboxyl groups and sulfonic acid groups have been introduced into dyes such as anthraquinone, naphthalene, acridone, or triazine, and compounds obtained by neutralizing such agents with organic amines. As the dye derivatives having acidic groups, anthraquinone-based (having an anthraquinone skeleton) dye derivatives having sulfonic acid groups are preferred from the viewpoint of good dispersibility of the red pigment. In particular, when CI Pigment Red 177 is used as the red pigment, it is preferred that the dye derivatives have at least one sulfonic acid group selected from a sulfonated pigment and / or a sulfonated dye having an anthraquinone skeleton having the same skeleton as CI Pigment Red 177 (sulfonated CI Pigment Red 149, anthraquinone derivatives described in JP-A-2002-22922), and a sulfonated CI Pigment Red 2. The acidic group-containing pigment dispersing aids can be used alone or in combination of two or more kinds.

[0020] The content of the acidic group-containing pigment dispersing aid is preferably 0.5 to 30 parts by mass, and more preferably 1 to 15 parts by mass, relative to 100 parts by mass of the red pigment. If the content of the acidic group-containing pigment dispersing aid is less than 0.5 parts by mass relative to 100 parts by mass of the red pigment, the pigment dispersion effect decreases, whereas if it exceeds 30 parts by mass, the pigment dispersion effect may not be improved any further.

[0021] <Epoxy resin> The epoxy resin is an epoxy resin having a structural unit derived from a polyfunctional maleimide compound having two or more maleimide groups and a benzoxazine compound. An example of a commercially available product of the epoxy resin is the product name "HR3070" (manufactured by Printec Co., Ltd.). The content of the epoxy resin is 0.5 to 7 parts by mass, preferably 1 to 3 parts by mass, relative to 100 parts by mass of the red pigment. If the content of the epoxy resin is less than 0.5 parts by mass, the contrast ratio before and after post-baking and the luminance at the time of post-baking decrease, and if the content is more than 7 parts by mass, the luminance at the time of post-baking decreases.

[0022] <Alkali-soluble resin> The alkali-soluble resin may be a known alkali-soluble resin used in a red pigment dispersion resist composition for color filters, preferably a resin having a carboxyl group, more preferably a copolymer consisting of an ethylenically unsaturated monomer having one or more carboxyl groups and another copolymerizable ethylenically unsaturated monomer. The copolymer may have a random copolymer or a block copolymer. The alkali-soluble resin may be used alone or in combination of two or more kinds.

[0023] Specifically, the copolymer may be a copolymer of an ethylenically unsaturated monomer having a carboxyl group, such as acrylic acid or methacrylic acid, and at least one ethylenically unsaturated monomer selected from the group of monomers and oligomers, such as styrene, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, allyl acrylate, allyl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, glycerol monoacrylate, glycerol methacrylate, N-phenylmaleimide, polystyrene macromonomer, polymethyl methacrylate macromonomer, and carboepoxy diacrylate, which are copolymerizable with the ethylenically unsaturated monomer having a carboxyl group. However, it is preferable not to use N-vinylpyrrolidone or a monomer containing a sulfur element. The copolymer may also have a photopolymerizable functional group.

[0024] The alkali-soluble resin has an acid value of preferably 5 to 250 mgKOH / g, more preferably 10 to 200 mgKOH / g, and even more preferably 60 to 150 mgKOH / g, from the viewpoint of development characteristics. The acid value is a theoretical acid value, and is a value calculated arithmetically based on the amount of ethylenically unsaturated monomer having a carboxyl group and its content.

[0025] The weight average molecular weight of the alkali-soluble resin is preferably 1,000 to 100,000, more preferably 3,000 to 50,000, and even more preferably 7,000 to 20,000, from the viewpoint of development characteristics and solubility in organic solvents. The weight average molecular weight is a weight average molecular weight calculated in terms of polystyrene obtained based on GPC. The measurement can be performed using a Water2690 (manufactured by Waters) as an apparatus and a PLgel 5 μm MIXED-D (manufactured by Agilent Technologies) as a column.

[0026] The content of the alkali-soluble resin is preferably 10 to 1,000 parts by mass, more preferably 20 to 500 parts by mass, based on 100 parts by mass of the red pigment. If the content of the alkali-soluble resin is less than 10 parts by mass, for example, the alkali developability may decrease, or background stains or film residue may occur on the substrate or light-shielding layer in unexposed areas. On the other hand, if the content exceeds 1,000 parts by mass, the concentration of the organic pigment is relatively decreased, so that it may be difficult to achieve the desired color density when formed into a thin film.

[0027] The alkali-soluble resin preferably does not contain any primary, secondary, or tertiary amino group, and more preferably does not contain any quaternary ammonium group.More preferably, the alkali-soluble resin does not contain any basic group.

[0028] <Photopolymerizable compound> The photopolymerizable compound may be a known photopolymerizable compound used in a red pigment dispersion resist composition for color filters, such as a monomer or oligomer having one or more photopolymerizable unsaturated bonds in the molecule. The photopolymerizable unsaturated bond is an unsaturated bond that can be polymerized by the action of radicals or cations generated when a photopolymerization initiator described later is decomposed by active energy rays such as ultraviolet rays or electron beams. The photopolymerizable compounds may be used alone or in combination of two or more kinds.

[0029] Examples of monomers having one photopolymerizable unsaturated bond in the molecule include alkyl methacrylates or acrylates such as methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl methacrylate, methyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; aralkyl methacrylates or acrylates such as benzyl methacrylate and benzyl acrylate; alkoxyalkyl methacrylates or acrylates such as butoxyethyl methacrylate and butoxyethyl acrylate; N,N-dimethylaminoethyl methacrylate and N,N-dimethylaminoethyl acrylate; Examples of the methacrylic acid ester include aminoalkyl methacrylates or acrylates such as acrylate; methacrylic acid esters or acrylic acid esters of polyalkylene glycol alkyl ethers such as diethylene glycol ethyl ether, triethylene glycol butyl ether, dipropylene glycol methyl ether; methacrylic acid esters or acrylic acid esters of polyalkylene glycol aryl ethers such as hexaethylene glycol phenyl ether; isobornyl methacrylate or acrylate; glycerol methacrylate or acrylate; 2-hydroxyethyl methacrylate or acrylate, etc. Incidentally, (meth)acrylate means acrylate and methacrylate.

[0030] Examples of monomers having two or more photopolymerizable unsaturated bonds in the molecule include bisphenol A dimethacrylate, 1,4-butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, diethylene glycol dimethacrylate, glycerol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, di Examples of the polyacrylate include pentaerythritol pentamethacrylate, bisphenol A diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, diethylene glycol diacrylate, glycerol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and dipentaerythritol pentaacrylate.

[0031] The content of the photopolymerizable compound is preferably in the range of 3 to 50% by mass based on the total solid content in the red pigment dispersion resist composition for color filters.

[0032] <Photopolymerization initiator> The photopolymerization initiator is not particularly limited as long as it can generate radicals or cations by being irradiated with active energy rays such as ultraviolet rays or electron beams. Examples of the photopolymerization initiator include benzophenone, N,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, benzil, 2,2-diethoxyacetophenone, benzoin, benzoin methyl ether, benzoin isobutyl ether, benzil dimethyl ketal, α-hydroxyisobutylphenone, thioxanthone, 2-chlorothioxanthone, 1-hydroxypropyl benzoate ... Examples of the photopolymerization initiator include hydroxycyclohexyl phenyl ketone, t-butyl anthraquinone, 1-chloro anthraquinone, 2,3-dichloro anthraquinone, 3-chloro-2-methyl anthraquinone, 2-ethyl anthraquinone, 1,4-naphthoquinone, 1,2-benzoanthraquinone, 1,4-dimethyl anthraquinone, 2-phenyl anthraquinone, 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone, and triazine-based photopolymerization initiators. The photopolymerization initiators may be used alone or in combination of two or more.

[0033] The content of the photopolymerization initiator is preferably in the range of 1 to 20% by mass based on the total solid content in the red pigment dispersion resist composition for color filters.

[0034] <Organic solvent> As the organic solvent, a known organic solvent used in a red pigment dispersion resist composition for color filters can be used, and specifically, ester-based organic solvents, ether-based organic solvents, ether ester-based organic solvents, ketone-based organic solvents, aromatic hydrocarbon-based organic solvents, nitrogen-containing organic solvents, etc., having a boiling point of 100 to 220°C at normal pressure (101.33 kPa) can be mentioned. If the organic solvent contains a large amount of an organic solvent having a boiling point of more than 220°C, when a coating film formed by applying the red pigment dispersion resist composition for color filters is prebaked, the organic solvent may not evaporate sufficiently and remain in the dried coating film, which may reduce the heat resistance of the dried coating film. In addition, if the organic solvent contains a large amount of an organic solvent having a boiling point of less than 100°C, it may be difficult to apply the composition uniformly without unevenness, and a coating film with excellent surface smoothness may not be obtained. The organic solvents can be used alone or in combination of two or more kinds.

[0035] Specific examples of the organic solvent include ether-based organic solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol methyl ethyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene ... ether ester organic solvents such as ethyl ether acetate; ketone organic solvents such as methyl isobutyl ketone, cyclohexanone, 2-heptanone, and δ-butyrolactone; ester organic solvents such as methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, 3-methyl-3-methoxybutylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, and n-amyl formate; alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol, and diacetone alcohol; and nitrogen-containing organic solvents such as N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0036] Among the organic solvents, in terms of solubility, dispersibility, coatability, and the like, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, cyclohexanone, 2-heptanone, ethyl 2-hydroxypropionate, 3-methyl-3-methoxybutylpropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, n-amyl formate, and the like are preferred, with propylene glycol monomethyl ether acetate being more preferred.

[0037] The content of the organic solvent in the red pigment-dispersed resist composition is preferably 50% by mass or more, and more preferably 70% by mass or more, from the standpoints of the solubility of the alkali-soluble resin, pigment dispersibility, coatability, and the like.

[0038] The red pigment dispersion resist composition for color filters of the present invention preferably further contains barium sulfate for the purpose of improving heat resistance and brightness. In the present invention, the content of barium sulfate is preferably 0.1 to 15 parts by mass, more preferably 5 to 12 parts by mass, relative to 100 parts by mass of the red pigment. If the barium sulfate exceeds 15 parts by mass, the coloring power is significantly reduced. The barium sulfate preferably has a primary particle diameter of 5 to 20 nm. If the barium sulfate has a primary particle diameter of more than 20 nm, the contrast may decrease and foreign matter may tend to be generated. The barium sulfate is used during or after dispersion of the finely-divided pigment.

[0039] In addition, the red pigment dispersion resist composition for color filters of the present invention may contain other resins within a range that does not impair the effects of the present invention. As the other resins, it is preferable to use a resin having a higher transmittance in the entire wavelength range of 400 to 700 nm in the visible light region. Examples of such resins include thermosetting resins and thermoplastic resins. Examples of the thermosetting resins and thermoplastic resins include butyral resins, styrene-maleic acid copolymers, chlorinated polyethylene, chlorinated polypropylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, polyvinyl acetate, polyurethane resins, phenolic resins, polyester resins, acrylic resins, alkyd resins, styrene resins, polyamide resins, rubber resins, cyclized rubbers, epoxy resins, celluloses, polybutadiene, polyimide resins, benzoguanamine resins, melamine resins, and urea resins.

[0040] The red pigment dispersion resist composition for color filters of the present invention may contain additives within the range that does not impair the effects of the present invention. Examples of the additives include various additives such as a thermal polymerization inhibitor, a silane coupling agent, a titanate coupling agent, an ultraviolet absorber, and an antioxidant.

[0041] In the red pigment-dispersed resist composition for color filters, the total content of the red pigment, the basic group-containing pigment dispersant, the acidic group-containing pigment dispersing aid, the epoxy resin, the alkali-soluble resin, the photopolymerizable compound, the photopolymerization initiator, and the solvent is preferably 70 mass % or more, more preferably 80 mass % or more, and even more preferably 90 mass % or more.

[0042] The method for producing the red pigment dispersion resist composition for color filters is not particularly limited, and the composition can be obtained by mixing the above-mentioned materials by a known method and grinding them. For example, the composition can be produced by the following method.

[0043] First, each untreated red pigment is subjected to a microparticulation treatment (salt milling treatment) to obtain a microparticulated red pigment. More preferably, an acidic group-containing pigment dispersing aid (sulfonic acid group-containing pigment dispersing aid) is mixed during microparticulation to obtain a mixture with the acidic group-containing pigment dispersing aid (sulfonic acid group-containing pigment dispersing aid). By performing the microparticulation treatment in the presence of the acidic group-containing pigment dispersing aid (sulfonic acid group-containing pigment dispersing aid), the red pigment can be uniformly microparticulated while suppressing crystallization. The particle size of the dispersion consisting of the microparticulated red pigment is about 50 to 70 nm. The above-mentioned microparticulation treatment includes a salt milling treatment in which a red pigment is ground with an inorganic salt in the presence of a red pigment and an acidic group-containing pigment dispersion aid (sulfonic acid group-containing pigment dispersion aid) using a kneader or a kneading device that rotates and revolves three stirring blades, thereby further reducing the primary particle size of the red pigment. The red pigment obtained by the salt milling treatment in the presence of such a red pigment and an acidic group-containing pigment dispersion aid (sulfonic acid group-containing pigment dispersion aid) is microparticulated so that the primary particle size of the untreated red pigment is further finer and more uniform. The salt milling treatment using a kneading device that rotates and revolves three stirring blades is also called a trimix treatment.

[0044] The trimix process will now be described in more detail. The above-mentioned trimix process is carried out by kneading a mixture containing a red pigment, a water-soluble inorganic salt (hereinafter also simply referred to as "inorganic salt"), and a water-soluble dispersion medium (hereinafter also simply referred to as "dispersion medium") that does not substantially dissolve the inorganic salt, in a kneading device that rotates and revolves three stirring blades, and then removing the inorganic salt and the dispersion medium. In this process, a kneading device in which three stirring blades perform planetary motion, that is, a kneading device that performs revolution while rotating, is used. This greatly reduces the dead space between the stirring blades and between the stirring blades and the inner surface of the device, and a stronger and more uniform shear force is obtained. The primary particle diameter of the red pigment that has been ground with the inorganic salt under this shear force becomes finer and more uniform than the primary particle diameter before the process, and a color filter with higher transparency and contrast ratio than conventional ones can be obtained. Here, "revolutionary motion" refers to the motion of the stirring blade revolving in a tank. In addition, "kneading device that revolves the stirring blade" originally refers to a kneading device that moves the stirring blade itself and performs revolutionary motion in a tank. However, in this specification, if the relative movement between the tank and the stirring blade is the same (for example, by rotating the tank), the kneading device is also included in the "kneading device that causes the stirring blade to revolve".

[0045] Furthermore, it is preferable that the structure of the kneading device satisfies the following conditions (1) and (2). (1) An equilateral triangle is a triangle whose vertices are the intersecting points of the three rotation axes of the three stirring blades in a plane perpendicular to the rotation axes of the three stirring blades. (2) The orbital axis intersects with the center of gravity of the equilateral triangle. In addition, it is preferable that the stirring blade has a length extending from the bottom of the tank to the liquid surface and a width extending from the inner wall of the tank to the center. An example of such a kneading device is Trimix (manufactured by Inoue Seisakusho Co., Ltd.). In this treatment, a wet treatment method can be used in which the red pigment, the pigment dispersion aid, the inorganic salt, and the dispersion medium are charged into a tank and kneaded.

[0046] The inorganic salt is not particularly limited as long as it is water-soluble, but it is preferable to use table salt (sodium chloride) from the viewpoint of cost. The particle size of the inorganic salt is preferably 200 μm or less, more preferably 50 μm or less. This allows the primary particle size of the red pigment to be made finer and more uniform than the primary particle size before treatment. In the present invention, the particle size of the inorganic salt refers to the volume average particle size measured by a laser diffraction particle size measurement method using a measuring device: Nanotrac (UPA-EX150, manufactured by Nikkiso Co., Ltd.).

[0047] The dispersion medium is not particularly limited as long as it is water-soluble and does not dissolve inorganic salts. Among them, the temperature rises during salt milling, and the solvent is easily evaporated, so a high-boiling point solvent with a boiling point of 120°C or more is preferable from the viewpoint of safety. Examples of such water-soluble dispersion media include alkoxy alcohols such as 2-methoxyethanol, 2-butoxyethanol, 2-(isopentyloxy)ethanol, 2-(hexyloxy)ethanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; glycols such as diethylene glycol, triethylene glycol, liquid polyethylene glycol, dipropylene glycol, and low molecular weight polypropylene glycol; and ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monoethyl ether.

[0048] The following methods can be mentioned as a method for carrying out the trimix process using the above materials and equipment. A red pigment, an acidic group-containing pigment dispersion aid (a sulfonic acid group-containing pigment dispersion aid), an inorganic salt, and a dispersion medium are charged into a tank. Next, the three stirring blades of the kneading device are rotated and revolved around the tank to grind the red pigment with the inorganic salt. After that, hot water is added to make a slurry, which is filtered and the remaining inorganic salt and dispersion medium are removed by washing with water. In this grinding process of the red pigment, it is preferable to appropriately adjust the amount of material charged (viscosity) and the inner diameter of the tank so that sufficient stress for kneading is applied. For example, when the above trimix is ​​used for the process, it is preferable to mix and process the materials so that the load ampere is in the range of 50% to 85% of the rated current value of the motor. Next, the basic group-containing pigment dispersant, the acidic group-containing pigment dispersing aid (sulfonic acid group-containing pigment dispersing aid), the alkali-soluble resin, the organic solvent, and optionally barium sulfate are added to the finely divided mixture, and the mixture is kneaded and dispersed using various dispersing machines such as a roll mill, a kneader, a high-speed stirring device, a bead mill, a ball mill, a sand mill, an ultrasonic dispersing machine, and a high-pressure dispersing machine to obtain a red pigment dispersion for color filters. Note that a photopolymerizable compound may be added in advance to the red pigment dispersion for color filters.

[0049] A method for obtaining the red pigment dispersion resist composition for color filters of the present invention from the red pigment dispersion will be described.

[0050] Regarding the method for obtaining the red pigment dispersion resist composition for color filters of the present invention from the red pigment dispersion for color filters, for example, in the case of obtaining a red pigment dispersion resist composition for color filters using a combination of CI Pigment Red 177 red pigment dispersion for color filters and another red pigment dispersion for red color filters, it can be obtained by the following (1) or (2), and in the case of obtaining a red pigment dispersion resist composition for CI Pigment Red 177 color filters, it can be obtained by the following (3). (1) A red pigment dispersion for CI Pigment Red 177 color filters and a red pigment dispersion for other red color filters are mixed to a predetermined pigment ratio, and then a photopolymerizable compound, a photopolymerization initiator, the remaining alkali-soluble resin, an organic solvent, and, if necessary, barium sulfate are added to obtain a red pigment dispersion resist composition for color filters of the present invention. (2) To each red pigment dispersion for a color filter, a photopolymerizable compound, a photopolymerization initiator, the remaining alkali-soluble resin, an organic solvent, and, if necessary, barium sulfate are added to obtain a red pigment dispersion resist composition for each color filter, and then the CI Pigment Red 177 pigment dispersion resist composition and other red pigment dispersion resist compositions for a color filter are mixed to obtain a predetermined pigment ratio, thereby obtaining the red pigment dispersion resist composition for a color filter of the present invention. (3) To the red pigment dispersion of CI Pigment Red 177 for color filters, a photopolymerizable compound, a photopolymerization initiator, the remaining alkali-soluble resin, an organic solvent, and optionally barium sulfate are added to obtain a red pigment dispersion resist composition for CI Pigment Red 177 color filters of the present invention.

[0051] The red pigment dispersion resist composition for color filters can be used to form a color filter. The color filter includes a red filter segment, a green filter segment, and a blue filter segment, and the red filter segment is formed from the red pigment dispersion resist composition for color filters of the present invention. The green filter segment and the blue filter segment can be formed by known materials and methods. The color filter formed from the red pigment dispersion resist composition for color filters of the present invention can be used by appropriately selecting a known method such as a printing method or a photolithography method. The color filter can be used as a display device. Examples of the display device include known liquid crystal display devices and touch panels. The light source of the display device preferably contains quantum dots. EXAMPLES

[0052] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass." In this specification, "Trimix" is a registered trademark of Inoue Seisakusho Co., Ltd., and "Irgacure" is a registered trademark of Chiba Specialty Chemicals Co., Ltd.

[0053] <Examples 1-2 and Comparative Examples 1-7> <Preparing red pigment> 800 parts of CI Pigment Red 177, 40 parts of sulfonated CI Pigment Red 2, 8000 parts of sodium chloride having a particle size of 20 μm, and 1920 parts of diethylene glycol were added to a tank of Trimix TX-15 (trade name, manufactured by Inoue Seisakusho Co., Ltd.). The mixture was kneaded for 3 hours at 45°C within a range of 70% of the rated current value of 9.3A, and salt milling was performed. Next, 1300 parts of the kneaded mixture obtained was added to 3 liters of warm water, and stirred for 1 hour while heating to 70°C to form a slurry. After repeatedly filtering and washing with water to remove sodium chloride and diethylene glycol, the mixture was dried at 40°C for a day and night to obtain 95 parts of microparticulated CI Pigment Red 177.

[0054] <Preparation of acidic group-containing pigment dispersing agent> 30ml of concentrated sulfuric acid was placed in a 100ml Erlenmeyer flask, and 10g of CI Pigment Red 2 was added while stirring with a magnetic stirrer, and stirred at room temperature for 30 minutes. A mixture of 50g of water and 50g of ice was placed in a 1L beaker, and the above reaction product was poured into the ice water and stirred with a magnetic stirrer for 30 minutes. This was filtered and washed under reduced pressure, and the obtained solid was dried to obtain 12g of sulfonated CI Pigment Red 2.

[0055] <Preparation of red pigment dispersion composition> The above-mentioned finely divided CI Pigment Red 177 was mixed with 14.00 parts by mass, BYK-LPN22102 (acrylic block copolymer having a tertiary amino group and / or a quaternary ammonium group, manufactured by BYK, solid content concentration 40% by mass) as a basic group-containing pigment dispersant, 5.60 parts by mass, 0.70 parts by mass of the above-mentioned sulfonated CI Pigment Red 2, 4.20 parts by mass of BzMA / MAA copolymer (benzyl methacrylate / methacrylic acid copolymer, theoretical acid value: 120 mgKOH / g, mass average molecular weight: 25,000) as an alkali-soluble resin, 0.98 parts by mass of barium sulfate (primary particle diameter 10 nm), and 74.52 parts by mass of PGMEA (propylene glycol monomethyl ether acetate), and the mixture was kneaded with a bead mill at a temperature of 40 to 50°C for 3 hours to obtain a red pigment dispersion composition.

[0056] <Production of Red Pigment Dispersed Resist Composition for Color Filter> 66.67 parts by mass of the above red pigment dispersion composition, 8.05 parts by mass of the above alkali-soluble resin, 4.31 parts by mass of DPEHA (dipentaerythritol hexaacrylate) as a photopolymerizable compound, 1.44 parts by mass of Irgacure 369 (manufactured by Ciba Specialty Chemicals, 2-benzyl 2-dimethylamino-1-(4-morpholinophenyl)-butanone-1) as a photopolymerization initiator, and 19.53 parts by mass of PGMEA (propylene glycol monomethyl ether acetate) were mixed uniformly using a high-speed stirrer, and then filtered through a filter with a pore size of 3 μm to obtain a composition. To 100 parts by mass of the obtained composition, epoxy resin HR3070 (an epoxy resin having a structural unit derived from a polyfunctional maleimide compound having two or more maleimide groups, and a benzoxazine compound, manufactured by Printec), jER1031s (a tetrafunctional epoxy resin, manufactured by Mitsubishi Chemical Corporation), TECHMORE VG3101L (a trifunctional epoxy resin, manufactured by Printec), or HR4770 (a difunctional dinaphthalene epoxy resin, manufactured by Printec) was added and stirred according to the formulation in Table 1, thereby obtaining a red pigment-dispersed resist composition for color filters of each Example and Comparative Example.

[0057] The following evaluations were carried out using the red pigment dispersion resist compositions for color filters of each of the Examples and Comparative Examples obtained above. The results are shown in Table 1.

[0058] <Contrast and brightness evaluation> The red pigment dispersion resist composition for color filters was applied on a glass substrate using a spin coater, and prebaked at 100°C for 3 minutes. At this time, two coated plates were prepared by applying each resist composition so that two coating films with different chromaticity x (value after post-baking described later) were formed. That is, the rotation speed of the spin coater was changed to change the thickness, so that the chromaticity x of one of the two plates was always smaller than 0.640, and the chromaticity x of the other plate was always larger than 0.640. Next, each coated plate was exposed to a high-pressure mercury lamp, and further post-baked at 230°C for 30 minutes. The contrast and brightness Y' of each of the above evaluation samples were measured at chromaticity x = 0.640 and y = 0.302 to 0.303 using a spectrophotometer (Shimadzu Corporation, UV-2500PC, C light source 2° field of view). Contrast was evaluated by measuring the contrast before post-bake (after pre-bake) and after post-bake, and then evaluating the rate of change (contrast after post-bake / contrast before post-bake). The acceptable standard for this rate of change is 90% or more. Brightness was evaluated by the difference in brightness before and after post-bake (YY´=ΔY). The acceptable standard for this difference in brightness is 0.023 or less. In contrast measurement, the blank was set to 10,000.

[0059] [Table 1]

[0060] The red pigment dispersion resist composition for color filters of the examples can suppress the decrease in brightness while reducing the amount of contrast loss before and after post-baking, and can also achieve a higher brightness after post-baking than the comparative examples.

Claims

1. The composition contains a red pigment, a basic group-containing pigment dispersant, an acidic group-containing pigment dispersant, an epoxy resin, an alkali-soluble resin, a photopolymerizable compound, a photopolymerization initiator, and a solvent, The epoxy resin is an epoxy resin having structural units derived from a polyfunctional maleimide compound having two or more maleimide groups and a benzoxazine compound, and is contained in an amount of 0.5 to 7 parts by mass relative to 100 parts by mass of the red pigment.

2. 2. The red pigment dispersion resist composition for color filters according to claim 1, wherein the acidic group-containing pigment dispersion aid is a sulfonic acid group-containing pigment dispersion aid.

3. 3. The red pigment dispersion resist composition for color filters according to claim 1, wherein the basic group-containing pigment dispersant is an acrylic block copolymer comprising a block having a basic group and a block not having a basic functional group.

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