Microparticulated pigment composition and method for producing the same

Abstract

To provide a microparticulated pigment composition and a method for producing the same, which enable formation of a cured film for a color filter with an improved red contrast ratio (CR); to provide a pigment dispersion and a film forming composition containing the microparticulated pigment composition capable of forming the cured film for the color filter with an improved red contrast ratio; and to provide the color filter with an improved red contrast ratio.SOLUTION: Provided are a microparticulated pigment composition containing C.I. Pigment Red 291 and C.I. Pigment Red 177, the microparticulated pigment composition being a milled product, which is mixed powder of C.I. Pigment Red 291 and C.I. Pigment Red 177, a pigment dispersion containing the microparticulated pigment composition and a solvent, a film forming composition containing the pigment dispersion, and a color filter containing the film forming composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a micronized pigment composition used for a color filter and the like, and a method for producing the same. The present invention also relates to a pigment dispersion, a film-forming composition, and a color filter using the micronized pigment composition.

Background Art

[0002] In recent years, with the development of personal computers, the demand for liquid crystal displays has been increasing. In addition, the penetration rate of mobile displays (mobile phones, smartphones, tablet PCs) has also been increasing, and the market for liquid crystal displays is expanding. Recently, organic light-emitting display devices such as organic EL displays with high visibility due to self-luminescence have also attracted attention as next-generation image display devices.

[0003] For example, a color filter used in the liquid crystal display device generally has a transparent substrate, a colored layer formed on the transparent substrate and composed of colored patterns of three primary colors of red, green, and blue, and a light-shielding portion formed on the transparent substrate so as to partition each colored pattern. As a method for forming such a colored layer, a pigment dispersion method, a dyeing method, an electrodeposition method, a printing method, etc. are known. Among them, from the viewpoints of spectral characteristics, durability, pattern shape and accuracy, etc., the pigment dispersion method having generally excellent characteristics is most widely adopted.

[0004] In the composition used for the pigment dispersion method, a colorant such as a pigment is contained in the form of uniformly dispersed particles in a liquid. For example, Patent Document 1 describes a red pigment produced by mixing synthesized C.I. Pigment Red 291 and micronized C.I. Pigment Red 177 in order to achieve a desired hue and a good contrast ratio. However, in Cited Document 2, although liquid crystal panel manufacturers require a dramatic increase in the contrast of color filters, it is described that it is difficult to achieve a dramatic improvement in contrast due to the micronization of pigments by using the salt milling method or co-grinding method of pigments, and there is a demand for further improvement in these (paragraph

[0011] ). Therefore, in the field of color filters and the like, the contrast was not sufficient, and further improvement was required.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a micronized pigment composition capable of producing a cured film for a color filter with an improved red contrast ratio (CR), a method for producing the same, a pigment dispersion containing the micronized pigment composition capable of producing a cured film for a color filter with an improved red contrast ratio, and a film-forming composition. Another object of the present invention is to provide a color filter with an improved red contrast ratio.

Means for Solving the Problems

[0007] A first aspect of the present invention is a micronized pigment composition containing C.I. Pigment Red 291 and C.I. Pigment Red 177, wherein the micronized pigment composition is a milled product of a mixed powder of C.I. Pigment Red 291 and C.I. Pigment Red 177, and relates to the micronized pigment composition.

[0008] In the micronized pigment composition, the weight ratio of C.I. Pigment Red 291 (PR291) to C.I. Pigment Red 177 (PR177) (PR291:PR177) may be 1:99 to 99:1.

[0009] A second aspect of the present invention relates to a pigment dispersion containing the micronized pigment composition and a solvent.

[0010] The pigment dispersion may further contain a pigment derivative.

[0011] A third aspect of the present invention relates to a film-forming composition containing the pigment dispersion.

[0012] A fourth aspect of the present invention relates to a color filter containing the film-forming composition.

[0013] A fifth aspect of the present invention relates to a method for producing a micronized pigment composition by mixing C.I. Pigment Red 291 and C.I. Pigment Red 177 and performing a milling process.

Advantages of the Invention

[0014] By using a pigment dispersion and a film-forming composition containing the micronized pigment composition according to the present invention to produce a cured film of a color filter, it becomes possible to improve the contrast ratio of an image.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the micronized pigment composition according to the present invention, a method for producing the same, a pigment dispersion, a film-forming composition, and a color filter will be described.

[0016] (Micronized Pigment Composition) The atomized pigment composition according to an embodiment of the present invention is an atomized pigment composition containing C.I. Pigment Red 291 and C.I. Pigment Red 177. Note that the C.I. Pigment Red 291 and C.I. Pigment Red 177 mean Color Index (C.I.) numbers.

[0017] C.I. Pigment Red 291 (PR291) has a chemical formula of C 18 H 10 N2O2Br2 and is a red pigment represented by the following structural formula (1):

[0018]

Chemical formula

[0019] It is a red pigment represented by As C.I. Pigment Red 291, a chemically synthesized product or a commercially available product may be used, and there is no particular limitation, and it can be used.

[0020] C.I. Pigment Red 177 (PR177) has a chemical formula of C 28 H 16 N2O4 and is a red pigment represented by the following structural formula (2):

[0021]

Chemical formula

[0022] It is a red pigment represented by As C.I. Pigment Red 177, a chemically synthesized product or a commercially available product may be used, and there is no particular limitation, and it can be used.

[0023] The atomized pigment composition of the present invention is characterized in that it is a milled product of a mixed powder of C.I. Pigment Red 291 and C.I. Pigment Red 177. By milling a mixed powder obtained by mixing a powder of C.I. Pigment Red 291 and a powder of C.I. Pigment Red 177, although the detailed reasons are unknown, the contrast ratio in the resulting film is significantly improved compared to a mixture of the milled product of C.I. Pigment Red 291 and the milled product of C.I. Pigment Red 177.

[0024] In the present invention, micronization refers to a process of making a pigment into fine particles by milling treatment. The particle size of the micronized milled product can be appropriately determined according to the use and the like, and it is generally preferable that the average particle diameter of primary particles, that is, the average primary particle diameter, is 20 to 200 nm. The average primary particle diameter can be calculated, for example, as the arithmetic mean of the maximum widths of a plurality (for example, 50) of primary particles during imaging by a transmission electron microscope (TEM).

[0025] In the present invention, the milling treatment includes dry milling in which mechanical grinding is performed using a ball mill or a vibration mill, and a solvent salt milling method in which mechanical grinding is performed together with an abrasive and an organic solvent. In the present invention, the milling treatment only needs to be able to make the C.I. Pigment Red 291 and the C.I. Pigment Red 177 into fine particles, and there is no particular limitation. From the viewpoint of easily achieving the effects of the present invention, the solvent salt milling method is preferable.

[0026] The solvent salt milling method is described as follows. Into a kneader such as a two-roll kneader (a kneader), a mixture of pigments containing C.I. Pigment Red 291 and C.I. Pigment Red 177, a water-soluble inorganic salt as an abrasive, and a water-soluble organic solvent that does not substantially dissolve the water-soluble inorganic salt are charged, and the temperature of the kneaded material in the kneader is controlled to be 30 to 60 °C while kneading for 3 to 24 hours. The kneaded material is mixed with deionized water and stirred using a stirring device to disperse the kneaded material in the deionized water. The stirring time at this time is 0.5 to 1 hour. The kneaded material dispersed in the deionized water is filtered, washed with deionized water, and made into a water-containing paste. At this time, in order to completely remove the water-soluble inorganic salt, it is preferably washed until the electrical conductivity of the washing wastewater becomes 3 μS / cm or less. Then, if necessary, it is dried at 40 to 110 °C for 3 to 15 hours. By pulverizing the dried block of the obtained kneaded material with a pulverizer, a powdery micronized pigment composition can be obtained. It is also possible to subject the water-containing paste to a so-called flushing treatment without drying to replace the water with a desired organic solvent for use. The water-soluble inorganic salt is not particularly limited as long as it dissolves in water. Examples include sodium chloride, barium chloride, potassium chloride, sodium sulfate (Glauber's salt), anhydrous sodium sulfate (anhydrous Glauber's salt), etc. Glauber's salt and anhydrous Glauber's salt are preferred from the viewpoints of the environment and price. The amount of the water-soluble inorganic salt used is not particularly limited, but it is preferably 100 to 3000 parts by weight based on 100 parts by weight of the pigment. The water-soluble organic solvent that does not substantially dissolve the water-soluble inorganic salt is not particularly limited as long as it dissolves (miscible) in water. However, from the viewpoint of safety, it is preferably one that does not evaporate during kneading, and it is preferable to use a high-boiling solvent with a boiling point of 120 °C or higher. Examples include glycols such as ethylene glycol (boiling point: about 198 °C), diethylene glycol (boiling point: about 245 °C), etc. The amount of the water-soluble organic solvent used is not particularly limited, but it is preferably 5 to 50 parts by weight based on 100 parts by weight of the water-soluble inorganic salt, more preferably 10 to 40 parts by weight, and particularly preferably 15 to 35 parts by weight. When the amount of the water-soluble organic solvent used is within the above range, uniform kneading can be performed, and furthermore, a shearing force is more likely to be applied to the kneaded material, so that a micronized pigment composition with little variation in particle size and sufficient micronization can be obtained.

[0027] The weight ratio (PR291:PR177) of C.I. Pigment Red 291 (PR291) to C.I. Pigment Red 177 (PR177) for preparing the mixed powder is preferably 1:99 to 99:1, more preferably 20:80 to 95:5, from the viewpoint that the effects of the present invention are likely to be achieved. The weight ratio of C.I. Pigment Red 291 to C.I. Pigment Red 177 contained in the micronized pigment composition of the present invention is the same as the weight ratio of C.I. Pigment Red 291 to C.I. Pigment Red 177 contained in the mixed powder.

[0028] Further, the micronized pigment composition according to the present invention may contain a pigment derivative. The pigment derivative is a compound that controls the particle growth of pigment fine particles. For example, (i) a compound in which a pigment is used as a parent skeleton and an acidic group, a basic group, or an aromatic group is introduced as a substituent into the side chain, (ii) an aromatic polycyclic compound such as a naphthalene-based, anthraquinone-based, or quinoline-based compound that is not generally called a dye is used as a parent skeleton, and an acidic group, a basic group, or an aromatic group is introduced as a substituent into the side chain, (iii) a compound in which triazine is used as a parent skeleton and an acidic group, a basic group, or an aromatic group is introduced as a substituent into the side chain, and the like can be mentioned. Examples of the pigment serving as the parent skeleton in (i) include pigments to which Color Index numbers are assigned, such as quinacridone-based pigments, phthalocyanine-based pigments, azo-based pigments, quinophthalone-based pigments, isoindoline-based pigments, isoindolinone-based pigments, quinoline-based pigments, quinophthalone-based pigments, diketopyrrolopyrrole-based pigments, benzimidazolone-based pigments, and dioxazine-based pigments. These pigment derivatives may be used alone or in combination of two or more. Specific examples of the pigment derivative include those described in Japanese Patent No. 6894641 and JP-A-04-285669.

[0029] Among them, as a pigment derivative having excellent effects, the following structural formula (3):

[0030]

Chemical formula

[0031] Pigment Derivative 1 represented by the following, and the following Structural Formula (4):

[0032] [Chemical Formula]

[0033] Pigment Derivative 2 represented by the following, and the following Structural Formula (5):

[0034] [Chemical Formula]

[0035] Pigment Derivative 3 represented by the following, and the following Structural Formula (6):

[0036] [Chemical Formula]

[0037] Examples include Pigment Derivative 4 represented by the following, etc.

[0038] Regarding the content of the pigment derivative in the micronized pigment composition, from the viewpoint of controlling the particle growth of the pigment fine particles and from the viewpoint of heat resistance in which the contrast ratio is difficult to decrease even by heating by post-baking and pre-baking, 0.1 to 20% by weight is preferable with respect to the total of the pigment and the pigment derivative, and 0.5 to 10% by weight is more preferable. The pigment derivative may be added in its entirety at the start of the milling process, or may be added in multiple portions after the start of the milling process.

[0039] Further, the micronized pigment composition according to the present invention may contain a dispersant. The dispersant is a compound that suppresses the aggregation of pigment fine particles, and a dispersant that can be used in the pigment dispersion described below can be preferably used. When using a polymer dispersant as the dispersant, a polymer dispersant having an acid value of 20 to 200 mgKOH / g and / or an amine value of 20 to 200 mgKOH / g is preferable, and a polymer dispersant having only one of the acid value or the amine value is more preferable. Here, the acid value (acid value in terms of solid content) can be determined by a method conforming to, for example, DIN EN ISO 2114, and the amine value (amine value in terms of solid content) can be determined by a method conforming to, for example, DIN 16945. As the content of the dispersant in the atomized pigment composition, 3 to 30% by weight is preferable based on the total of C.I. Pigment Red 291 and C.I. Pigment Red 177, or when including a pigment derivative, based on the total of C.I. Pigment Red 291, C.I. Pigment Red 177 and the pigment derivative. The dispersant may be added in its entirety at the start of the milling process, or may be added in multiple portions after the start of the milling process.

[0040] (Pigment dispersion) The pigment dispersion according to the present invention contains the atomized pigment composition of the present invention and a solvent.

[0041] As the solvent used in the pigment dispersion, from the viewpoint of color filter applications, an organic solvent is preferable. Examples of such organic solvents include propylene glycol monomethyl ether acetate (PMA), propylene glycol monomethyl ether (PM), ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethyl acetate, butyl acetate, ethyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, n-propanol, 2-propanol, n-butanol, cyclohexanol, ethylene glycol, diethylene glycol, toluene, xylene, and the like. These solvents may be used alone or in a mixture of two or more.

[0042] The content of the micronized pigment composition (pigment content) in the pigment dispersion according to the present invention is not particularly limited, but from the viewpoint of achieving the effects of the present invention, it may be 5 to 70% by weight.

[0043] Further, the pigment dispersion according to the present invention may contain other pigments. Examples of other pigments include red pigments other than PR291 and PR177, and organic pigments such as yellow, orange, and purple. In this case, the ratio of the micronized pigment composition of the present invention can be arbitrarily changed depending on the desired hue. Generally, it is preferably 0.1% by weight or more and less than 100% by weight, and more preferably 40% by weight or more and 95% by weight or less, based on the total organic pigments.

[0044] The content of the organic solvent can be added so that the solid content concentration including the micronized pigment composition and the like is 5 to 50% by weight in the pigment dispersion according to the present invention.

[0045] Further, the pigment dispersion according to the present invention may contain a pigment derivative or the like. The pigment derivative may be any one used in the micronized pigment composition.

[0046] The content of the pigment derivative in the pigment dispersion is not particularly limited as long as it does not affect the desired hue. However, from the viewpoint of high contrast, it is preferably 5 to 35% by weight, and more preferably 10 to 25% by weight, based on the total of the pigment and the pigment derivative. Note that the content of the pigment derivative is the amount including the pigment derivative contained in the micronized pigment composition.

[0047] Further, the pigment dispersion according to the present invention may contain a dispersant or the like. The dispersant is not particularly limited, and examples thereof include polymer dispersants and surfactant-type dispersants. Among these, polymer dispersants are preferred from the viewpoint of viscosity stability. Polymer dispersants include oil-based polymer dispersants and water-based polymer dispersants.

[0048] Examples of the oil-based polymer dispersants include polyurethane, polyester, unsaturated polyamide, phosphate ester, polycarboxylic acid and its amine salt, ammonium salt, alkylamine salt, polycarboxylic acid ester, hydroxyl group-containing polycarboxylic acid ester, polysiloxane, modified polyacrylate, and the like.

[0049] Examples of the water-based polymer dispersants include water-soluble polymer compounds such as alginic acids, polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyvinyl pyrrolidone, gum arabic; ethylene double bond-containing resins such as styrene-acrylic acid resin, styrene-methacrylic acid resin, styrene-acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid ester resin, methacrylic acid-methacrylic acid ester resin, acrylic acid-acrylic acid ester resin, isobutylene-maleic acid resin, vinyl-ester resin, rosin-modified maleic acid resin; amine-based resins such as polyallylamine, polyvinylamine, polyethyleneimine; and the like.

[0050] Various polymer dispersants are commercially available, and specific examples are as follows, but are not limited thereto. Manufactured by Lubrizol Japan Ltd.: Solsperse (registered trademark) 3000, 9000, 13240, 17000, 20000, 24000, 26000, 27000, 28000, 32000, 32500, 38500, 39000, 55000, 41000, manufactured by Big Chemie Japan Ltd.: Disperbyk (registered trademark) 108, 110, 112, 140, 142, 145, 161, 162, 163, 164, 166, 167, 171, 174, 182, 2000, 2001, 2050, 2070, 2150, manufactured by BASF: EFKA (registered trademark) 4401, 4403, 4406, 4330, 4340, 4010, 4015, 4046, 4047, 4050, 4055, 4060, 4080, 5064, 5207, 5244, manufactured by Ajinomoto Fine-Techno Co., Ltd.: Ajisper (registered trademark) -PB821(F), PB822, PB880, manufactured by Kawaken Fine Chemicals Co., Ltd.: Hinacto (registered trademark) T-8000, manufactured by Kusumoto Chemicals, Ltd.: Disparon (registered trademark) PW-36, Disparon (registered trademark) DA-325, 375, 7301, etc.

[0051] The molecular weight of the polymer dispersant is not particularly limited, but a weight average molecular weight of about 5,000 to 100,000 is preferable.

[0052] The content of the dispersant is not particularly limited, but from the viewpoint of obtaining a pigment dispersion effect, it is preferably 10 to 80 parts by weight, more preferably 20 to 60 parts by weight, per 100 parts by weight of the pigment (including pigment derivatives). However, the optimal addition amount of the dispersant may be appropriately adjusted according to combinations such as the types of pigments and pigment derivatives used in combination with the micronized pigment composition of the present invention, the type of solvent, etc.

[0053] In addition, in the pigment dispersion according to the present invention, in addition to the dispersant, in order to further improve the dispersibility of pigments and the like, and thus further improve the contrast of the film, a resin that can be added to the film-forming composition can be added in advance. In the present invention, such a resin is referred to as a dispersion resin. Examples of the dispersion resin that can be used in the present invention include alkali-soluble resins described later. The dispersion resin may be the same as or different from the alkali-soluble resin added to the film-forming composition. The content of the dispersion resin is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the pigment (including pigment derivatives).

[0054] The pigment dispersion can be prepared by mixing and dispersing each constituent component such as a micronized pigment composition using various mixers and dispersers.

[0055] Specifically, after mixing the constituent components of the pigment dispersion as described above to perform preliminary dispersion, a dispersion medium such as beads is further added for main dispersion to perform fine dispersion. Thereafter, if necessary, a method of further adding a solvent for dilution dispersion can be mentioned. After dilution dispersion, if necessary, filtration can be performed using a filter, and the filtrate may be used as the pigment dispersion.

[0056] In the preliminary dispersion, a disperser such as a disper or a homogenizer is used to disperse the pigment and the like. When using a disper, it is preferably treated at 500 to 2000 rpm for 10 to 60 minutes. In the main dispersion, fine dispersion is performed using a bead disperser or the like. When using beads, it is preferably added in an amount of 2 to 6 times the weight of the pigment dispersion. As the beads, glass beads, zirconia beads, etc. having a particle diameter of 0.01 to 1 mm can be used. The treatment of the main dispersion is preferably about 1 to 12 hours at 1500 to 2500 rpm when using a disper. Examples of the bead disperser include vertical or horizontal sand grinders, pin mills, slit mills, ultrasonic dispersers, etc.

[0057] When the pigment dispersion of the present invention is applied to a film-forming composition used in the production of a color filter, it is preferably soluble in an alkaline aqueous solution.

[0058] (Film-forming composition) The film-forming composition of the present invention contains the aforementioned pigment dispersion according to the present invention and a desired film-forming component. Thus, by including the pigment dispersion according to the present invention, even in the film-forming composition, the atomized pigment composition can stably maintain its dispersed state, resulting in good film-forming properties during film formation, and it becomes possible to improve the contrast ratio of the film and, thus, the color filter compared to the prior art.

[0059] The content of the pigment dispersion in the film-forming composition of the present invention is preferably 5 to 70% by weight, more preferably 15 to 60% by weight, based on the total solid content (weight) of the film-forming composition. (When the pigment dispersion contains a pigment derivative, the content of the pigment derivative is also included.) When the content of the pigment dispersion is within this range, it is effective for ensuring sufficient color density and excellent color characteristics.

[0060] Examples of the film-forming component include polymerizable components, polymers, and mixtures thereof. As the polymerizable component, a photopolymerizable component is preferred because patterning can be easily performed by development (negative development). Usable photopolymerizable components include a photopolymerizable compound and a photoinitiator. Such photopolymerizable compounds and photoinitiators can be, for example, those described in JP-A-2009-179789. Referring to the description therein, it is generally as follows. That is, such a photopolymerizable compound is an addition-polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one, preferably two or more terminal ethylenically unsaturated bonds. Such a group of compounds is widely known in the relevant industrial field, and in the present invention, these can be used without particular limitation. The photopolymerizable compound has, for example, chemical forms such as monomers, prepolymers, that is, dimers, trimers and oligomers, or mixtures thereof and copolymers thereof.

[0061] Examples of the monomer and its copolymer include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof. Preferably, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and aliphatic polyvalent amine compounds are used. In addition, addition reaction products of unsaturated carboxylic acid esters or amides having nucleophilic substituents such as hydroxyl groups, amino groups, and mercapto groups with monofunctional or polyfunctional isocyanates or epoxies, and dehydration condensation reaction products with monofunctional or polyfunctional carboxylic acids are also preferably used. Further, addition reaction products of unsaturated carboxylic acid esters or amides having electrophilic substituents such as isocyanate groups and epoxy groups with monofunctional or polyfunctional alcohols, amines, and thiols, and substitution reaction products of unsaturated carboxylic acid esters or amides having leaving substituents such as halogen groups and tosyloxy groups with monofunctional or polyfunctional alcohols, amines, and thiols are also suitable. Further, as another example, it is also possible to use a group of compounds in which the above unsaturated carboxylic acid is replaced with an unsaturated phosphonic acid, styrene, vinyl ether, or the like. Incidentally, these specific examples are as described in JP-A-2009-179789. Specific examples of monomers of esters of aliphatic polyhydric alcohol compounds and unsaturated carboxylic acids include, as acrylic acid esters, ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri(acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri(acryloyloxyethyl) isocyanurate, polyester acrylate oligomer, EO-modified triacrylate of isocyanuric acid, and the like.

[0062] Regarding these addition-polymerizable compounds, details of their structure, whether used alone or in combination, and the amount added and other usage methods can be arbitrarily set according to the performance design of the final film-forming composition. For example, they are selected from the following viewpoints. In terms of sensitivity, a structure with a high unsaturated group content per molecule is preferable, and in many cases, difunctional or higher is preferable. Also, in order to increase the strength of the cured film, trifunctional or higher is better. Furthermore, a method of adjusting both sensitivity and strength by using those with different functionality numbers and different polymerizable groups (for example, acrylic acid esters, methacrylic acid esters, styrene-based compounds, vinyl ether-based compounds) in combination is also effective.

[0063] In addition, with respect to the compatibility and dispersibility with other components in the film-forming composition (for example, binder polymers such as alkali-soluble resins, photoinitiators, colorants (pigments)), the selection and usage method of the addition-polymerizable compound are important factors. For example, the use of a low-purity compound or the combination of two or more kinds may improve the compatibility. Also, it may be possible to select a specific structure for the purpose of improving the adhesion to a substrate or the like. The addition-polymerizable compound, which is a photopolymerizable compound, is preferably contained in an amount of 5 to 70% by weight, more preferably 10 to 60% by weight, based on the non-volatile components in the film-forming composition. These may be used alone or in combination of two or more. In addition, the usage method of the photopolymerizable compound can arbitrarily select an appropriate structure, formulation, and addition amount from the viewpoints of the magnitude of polymerization inhibition against oxygen, resolution, fogging property, refractive index change, surface tackiness, etc.

[0064] As the photoinitiator, those described in JP-A-2009-179789 can also be used. That is, as the photoinitiator that can be preferably used in the present invention, for example, acetophenone-based, ketal-based, benzophenone-based, benzoin-based, benzoyl-based, xanthone-based, active halogen compounds (triazine-based, oxadiazole-based, coumarin-based), acridine-based, biimidazole-based, oxime ester-based, etc. These specific examples are as described in JP-A-2009-179789. Specific examples of the benzophenone-based photoinitiator include, for example, benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-dichlorobenzophenone, and the like.

[0065] The content of the photoinitiator in the film-forming composition is preferably 0.1 to 10.0% by weight, more preferably 0.5 to 5.0% by weight, based on the total solid content of the film-forming composition. When the content of the photoinitiator is within this range, the polymerization reaction can proceed favorably and a film with good strength can be formed.

[0066] Examples of the polymer include thermoplastic urethane resins, (meth)acrylic resins, polyamide resins, polyimide resins, styrene-maleic acid resins, polyester resins, silicone resins, and cardo resins. Among the polymers as the film-forming component as described above, an alkali-soluble resin that is soluble in an alkaline solution is preferable. From the viewpoint of developability, the weight average molecular weight of the alkali-soluble resin is preferably 5,000 to 50,000.

[0067] When the composition for film formation according to the present invention contains an alkali-soluble resin, when the composition for film formation is applied to pattern formation in a photolithography process, the pattern formability can be further improved.

[0068] As such an alkali-soluble resin, those described in JP-A-2009-179789 can be used. Referring to a part of the description, it is generally as follows.

[0069] That is, as the alkali-soluble resin that can be used in the present invention, for example, a linear organic polymer, and at least one group that promotes alkali solubility (for example, a carboxyl group, a phosphate group, a sulfonic acid group, etc.) in a molecule (preferably a molecule having an acrylic copolymer or a styrene copolymer as a main chain) It can be appropriately selected from among the alkali-soluble resins having. Among these, those that are more preferably soluble in an organic solvent and developable with a weakly alkaline aqueous solution are preferred.

[0070] Preferable examples of the alkali-soluble resin in the present invention include, in particular, a copolymer of (meth)acrylic acid and another monomer copolymerizable therewith. Here, (meth)acrylic acid is a general term for acrylic acid and methacrylic acid, and similarly, (meth)acrylate is a general term for acrylate and methacrylate. Examples of other monomers copolymerizable with (meth)acrylic acid include alkyl (meth)acrylates, aryl (meth)acrylates, vinyl compounds, etc. Here, the hydrogen atoms of the alkyl group and the aryl group may be substituted with substituents. Specific examples of the alkyl (meth)acrylate and aryl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, tolyl (meth)acrylate, naphthyl (meth)acrylate, cyclohexyl (meth)acrylate, and the like. Examples of the vinyl compound include styrene, α-methylstyrene, vinyltoluene, glycidyl methacrylate, glycidyl acrylate, acrylonitrile, vinyl acetate, N-vinylpyrrolidone, tetrahydrofurfuryl methacrylate, polystyrene macromonomer, polymethyl methacrylate macromonomer, CH2=C(R5)(R6), CH2=C(R5)(COOR7) (wherein R5 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R6 represents an aromatic hydrocarbon ring having 6 to 10 carbon atoms, and R7 represents an alkyl group having 1 to 8 carbon atoms or an aralkyl group having 6 to 12 carbon atoms), and the like. These other copolymerizable monomers may be used alone or in combination of two or more.

[0071] Various alkali-soluble resins are commercially available, and specific examples are as follows, but are not limited thereto. Manufactured by Resonac Co., Ltd.: Lipoxy (registered trademark) SPCN-100, SPC-2000, Manufactured by Mitsubishi Chemical Corporation: Dianal (registered trademark) NR series, Manufactured by Osaka Organic Chemical Industry Co., Ltd.: Biscoat R-264, KS Resist 106, Manufactured by Daicel Corporation: Cyclomer (registered trademark) P series, Placcel (registered trademark) CF200 series, Manufactured by Daicel Ornex Co., Ltd.: Ebecryl (registered trademark) 3800, Manufactured by Soken Chemical & Engineering Co., Ltd.: Forext (registered trademark) ZAH110, etc.

[0072] As the content in the composition for forming a film of the alkali-soluble resin, 5 to 60% by weight is preferable, and more preferably 10 to 50% by weight, in the total solid content of the composition for forming a film. The content of the alkali-soluble resin in the composition for forming a film is the total amount with the alkali-soluble resin contained in the pigment dispersion.

[0073] The composition for forming a film of the present invention can be suitably prepared by using a solvent together with the above-described respective components. Such solvents include esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, amyl formate, isoamyl acetate, butyl propionate, isopropyl butyrate, ethyl butyrate, butyl butyrate, methyl lactate, ethyl lactate, methyl oxyacetate, ethyl oxyacetate, butyl oxyacetate, methyl methoxyacetate, ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate; alkyl 3-oxypropionates such as methyl 3-oxypropionate, ethyl 3-oxypropionate; methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 2-oxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, methyl 2-oxy-2-methylpropionate, ethyl 2-oxy-2-methylpropionate, methyl 2-methoxy-2-methylpropionate, ethyl 2-ethoxy-2-methylpropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl 2-oxobutanoate, ethyl 2-oxobutanoate, etc.; ethers such as diethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, etc.; ketones such as methyl ethyl ketone, cyclohexanone, 2-heptanone, 3-heptanone, etc.; aromatic hydrocarbons such as toluene, xylene; and the like. The solvent may be used alone or in combination of two or more. As the content in the composition for film formation of the solvent, considering the type and content of the solvent in the pigment dispersion, it is preferably included so that the total solid content (non-volatile component) in the composition for film formation is 5 to 50% by weight.

[0074] In the composition for film formation of the present invention, if necessary, sensitizing dyes, epoxy resins, fluorine-based organic compounds, thermal polymerization initiators, thermal polymerization components, thermal polymerization inhibitors, fillers, surface modifiers, polymer compounds other than the aforementioned alkali-soluble resin (dispersion resin) and polymer dispersants, surfactants, adhesion promoters, antioxidants, ultraviolet absorbers, anti-aggregation agents, and various other additives can be contained.

[0075] The composition for film formation can be obtained by adjusting the pigment dispersion and film-forming components according to the present invention, as well as the solvent and various additives, which are the aforementioned optional components, to a desired component composition and stirring them in a mixing tank. By using a disperser such as a disper to perform the stirring in the mixing tank, pigments and the like can be dispersed in the composition for film formation. The obtained mixed liquid may be subjected to a filtration treatment if necessary.

[0076] The composition for film formation thus obtained can be suitably used for forming a film having an excellent contrast ratio on a substrate such as glass. Therefore, it can be suitably used for manufacturing a color filter having an excellent contrast ratio.

[0077] (Color Filter) After applying the composition for film formation of the present invention onto a substrate, if necessary, photocuring and development are performed to obtain a film, whereby a color filter can be manufactured. As the composition for film formation, it may be the composition for film formation of the present invention, or it may be a commercially available composition for film formation to which the atomized pigment composition of the present invention is added.

[0078] In the present invention, the method of applying the composition for film formation of the present invention onto a substrate is not particularly limited, and a spin coating method, a slit method, an inkjet method, etc. can be used.

[0079] When forming a film on a substrate using the film-forming composition of the present invention, the thickness of the film (after pre-baking) is generally 0.3 to 5.0 μm, preferably 0.5 to 4.0 μm, and most preferably 0.5 to 3.0 μm. In the case of a color filter for a solid-state imaging device, the thickness of the film (after pre-baking) is preferably in the range of 0.5 to 5.0 μm.

[0080] (Pre-baking) After the film of the film-forming composition of the present invention is formed on the substrate as described above, pre-baking is performed. If necessary, vacuum drying can also be performed before pre-baking. The conditions for vacuum drying are that the degree of vacuum is usually 0.1 to 1.0 torr (13 to 133 Pa), preferably about 0.2 to 0.5 torr (27 to 67 Pa). Also, pre-baking can be performed using a hot plate, an oven, etc. in a temperature range of 50 to 140 °C, preferably about 70 to 110 °C, and under the conditions of 10 to 300 seconds. Note that high-frequency treatment etc. may be used in combination with pre-baking. High-frequency treatment can also be used alone.

[0081] After pre-baking, if necessary, after pattern exposure and development processing, usually, heat treatment (post-baking) at 100 °C to 250 °C is performed. This post-baking is heating after development to make the curing complete, and it is preferably performed by heating at 200 °C to 250 °C (hard bake). This post-baking can be performed continuously or batchwise using heating means such as a hot plate, a convection oven (hot air circulation dryer), a high-frequency heater, etc. so that the film after development becomes the above conditions.

[0082] By sequentially performing the above steps, the color filter of the present invention can be manufactured. Further, by sequentially repeating the above steps for each color (three or four colors) according to the desired number of hue colors, a color filter in which a cured film (color pattern) colored with a plurality of colors is formed can be produced.

Examples

[0083] Examples and comparative examples are given below to specifically describe the present invention, but the invention of the present application is not limited to only these examples.

[0084] The raw materials and apparatuses used in the examples and comparative examples are as follows. Commercially available products were used for raw materials other than those listed below.

[0085] · Red pigment C.I. Pigment Red 291 (PR291) (manufactured by CINIC Chemicals, Cinilex (registered trademark) DPP Red MT-CF) C.I. Pigment Red 177 (PR177) (manufactured by CINIC Chemicals, Cinilex (registered trademark) Red SR3C)

[0086] · Pigment derivative 1 18.4 parts by weight of cyanuric chloride and 17.3 parts by weight of ortanyl acid (2-aminobenzenesulfonic acid) in an amount that reacts with one chlorine atom of cyanuric chloride were added to 100 parts by weight of water, and the mixture was reacted at 10°C for 1 hour. To the obtained reaction product, 29.8 parts by weight of 5-amino-2-benzimidazolinone in an amount that reacts with two chlorine atoms of this reaction product was added, and the mixture was reacted at 85°C for 1 hour. The obtained reaction product was collected by filtration, and the obtained residue was washed with water and then left standing in a constant temperature bath at 100°C overnight to be dried, obtaining 44.7 parts by weight of pigment derivative 1.

[0087] · Pigment derivative 2 740 parts by weight of sulfuric acid (primary, 95%) was placed in a reaction vessel and cooled to 15°C or lower. Subsequently, 4 parts by weight of paraformaldehyde (94%) and 20.3 parts by weight of 4-aminophthalimide were added in this order so that the temperature did not exceed 20°C, and then the temperature was raised to 22.5°C. Stirring was carried out at 22.5°C and 170 rpm for 1 hour to cause a reaction. The reaction solution was brown and transparent. After cooling to 15°C or lower, 40.1 parts by weight of C.I. Pigment Orange 73 (manufactured by CINIC Chemicals, Cinilex (registered trademark) DPP Orange SJ1C) was added so that the temperature did not exceed 20°C, and then the temperature was raised to 30°C. Stirring was carried out at 30°C and 200 rpm for 3 hours to cause a reaction. The reaction solution was dark red-violet. The reaction solution was slowly poured into 8200 parts by weight of ice water (pure water: ice = 1:1 (weight ratio)). After stirring for 30 minutes, the discharged liquid was filtered and washed with pure water to obtain an aqueous paste of the intermediate compound. 685 parts by weight (solid content 13.5%) of the aqueous paste of the intermediate compound and 3000 parts by weight of pure water were charged into a diazotization tank and stirred overnight at 60 rpm. 590 parts by weight of 35% hydrochloric acid was added, and after stirring for 5 minutes or more, ice was added to adjust the liquid temperature to 0 - 2.5°C. 100 parts by weight of sodium nitrite was dissolved in 180 parts by weight of pure water and added, and stirring was carried out for 1 hour while maintaining the liquid temperature at 0 - 2.5°C. 21 parts by weight of sulfamic acid was dissolved in 160 parts by weight of pure water and added, and stirring was carried out for 30 minutes while maintaining the liquid temperature at 0 - 2.5°C. The pH of the diazotization solution at this time was 0.88. 6000 parts by weight of pure water and 482 parts by weight of 30% caustic soda were charged into a coupler tank, and after stirring for 5 minutes or more, 400 parts by weight of 1-(3-sulfophenyl)-3-methyl-5(4H)-pyrazolone was added and stirred for 10 minutes or more. 610 parts by weight of sodium acetate was dissolved in 1200 parts by weight of pure water at 60°C and added, and after stirring for 30 minutes or more, the liquid temperature was adjusted to 20°C. The pH at this time was 12.60. Next, the above diazotization solution was added to this coupler tank. The temperature was raised to 20°C at a rate of 1°C / min, stirred for 1 hour, then the temperature was raised to 60°C at a rate of 1°C / min, and further stirred for 1 hour. The pH after the reaction was 4.62. It was adjusted to pH 2.0 or lower with 35% hydrochloric acid and stirred for 30 minutes. The obtained reaction product was collected by filtration, and the obtained residue was washed with water and then left standing in a constant temperature bath at 80°C overnight to be dried, obtaining 860 parts by weight of the pigment derivative. The obtained pigment derivative 2 was pulverized by a bantam mill and used.

[0088] · Pigment Derivative 3 2500 parts by weight of concentrated sulfuric acid was placed in a reaction vessel, and 192.26 parts by weight of 3,5-dimethylpyrazole and 65.28 parts by weight of paraformaldehyde were added so as not to exceed 30 °C. Then, the temperature was raised to 30 °C and reacted for 2 hours. Subsequently, 312.32 parts by weight of C.I. Pigment Violet 19 (manufactured by DIC Corporation, Pacific Red 2020) was added, and the temperature was raised to 60 °C and reacted for 5 hours. After allowing to cool to room temperature, the reaction product was poured into 12000 parts by weight of water containing ice to precipitate the reaction product. The obtained reaction product was collected by filtration, and the obtained residue was washed with water and then dried in a constant temperature bath at 80 °C to obtain 519 parts by weight of pigment derivative 3 (the structural formula (5), substitution number n = 2).

[0089] · Pigment Derivative 4 20 parts by weight of C.I. Pigment Yellow 138 (manufactured by BASF Corporation, Paliotol® Yellow K0961HD) and 300 parts by weight of 98% sulfuric acid were placed in a 500 ml separable flask and reacted at 120 °C for 5 hours to obtain a sulfonated product of a phthalimide quinophthalone compound. The reaction mixture was poured into 3000 parts of water while stirring to precipitate the sulfonated product of the phthalimide quinophthalone compound, and after stirring for 30 minutes, filtration and washing with water were repeated 3 times. The obtained wet cake was washed with 300 parts by weight of 1% dilute sulfuric acid, then filtered and washed with water. It was dried in a hot air dryer to obtain 54 parts by weight of pigment derivative 4.

[0090] · Dispersant 「BYK2001」(manufactured by BYK Chemie Japan Co., Ltd., Disperbyk® 2001)

[0091] · Organic Solvent 「PMA」Propylene Glycol Monomethyl Ether Acetate

[0092] (Example 1: Production of Atomized Pigment Composition 1) The micronized pigment composition 1 was prepared by the following procedure using the solvent-salt milling method. Into a twin-screw kneader (manufactured by Moriya, 5L kneader Σ type, hereinafter referred to as kneader), PR291, PR177 which are red pigments, pigment derivative 1, pigment derivative 2, and pigment derivative 3 were mixed so that the weight ratio was 83.7 / 9.3 / 5 / 1 / 1, making a total of 100 parts by weight. Then, 1000 parts by weight of sodium sulfate (Glauber's salt) and 275 parts by weight of ethylene glycol were added, and the mixture was kneaded for 7 hours while controlling the temperature so that the temperature of the kneaded material in the kneader became 40°C. Next, the kneaded material was transferred into a tank, deionized water was added, and the mixture was stirred for 60 minutes at a rotational speed of 200 rpm with a stirring device to disperse the kneaded material. The dispersion was filtered, washed with deionized water, the residue after washing was dried, and the obtained dried block was pulverized to obtain the micronized pigment composition 1 as a milled product.

[0093] (Examples 2 to 5: Production of micronized pigment compositions 2 to 5) Except that the pigment composition was changed as shown in Table 1, the micronized pigment compositions 2 to 5 were obtained in the same manner as in Example 1. In Table 1, the weight ratio of C.I. Pigment Red 291 (PR291) to C.I. Pigment Red 177 (PR177) (PR291:PR177) is described as "Red pigment ratio (weight ratio) PR291 / PR177". "PR291 / PR177 = 90 / 10" indicates that (PR291:PR177) is 90:10 (weight ratio). The same applies to Table 2 below.

[0094]

Table 1

[0095] (Comparative Examples 1 to 4: Production of micronized pigment compositions 6 to 9) Except that the pigment composition was changed as shown in Table 1, the micronized pigment compositions 6 to 9 were obtained in the same manner as in Example 1.

[0096] (Example 6: Production of pigment dispersion 1) The atomized pigment composition 1, pigment derivative 2, pigment derivative 4, dispersant (solid content), and organic solvent as red pigments were mixed at a weight ratio of 12.45 / 0.75 / 1.80 / 15.00 / 70.00. To 100 parts by weight of this mixture, 400 parts by weight (4-fold amount) of zirconia beads with a diameter of φ0.5 mm were added, and the mixture was dispersed for 2 hours using a paint shaker. The zirconia beads with a diameter of φ0.5 mm were removed to obtain pigment dispersion 1.

[0097] (Examples 7 - 10: Production of Pigment Dispersions 2 - 5) Except for using atomized pigment compositions 2 - 5 as red pigments, pigment dispersions 2 - 5 were obtained in the same manner as in Example 6.

[0098] (Comparative Examples 5 - 8: Production of Pigment Dispersions 6 - 9) Except for using atomized pigment compositions 6 - 9 as red pigments, pigment dispersions 6 - 9 were obtained in the same manner as in Example 6.

[0099] (Comparative Examples 9 - 12: Production of Pigment Dispersions 10 - 13) Also, as a control for pigment dispersions 1 - 4 obtained in Examples 6 - 9, except for using a mixture of atomized pigments prepared by adjusting and mixing atomized pigment composition 6 obtained in Comparative Example 1 and atomized pigment composition 7 obtained in Comparative Example 2 so that the mixing ratio of the red pigment is the same as that of pigment dispersions 1 - 4, pigment dispersions 10 - 13 were obtained in the same manner as in Example 6.

[0100] (Comparative Example 13: Production of Pigment Dispersion 14) As a control for pigment dispersion 5 obtained in Example 10, except for using a mixture of atomized pigments prepared by adjusting and mixing atomized pigment composition 8 obtained in Comparative Example 3 and atomized pigment composition 9 obtained in Comparative Example 4 so that the mixing ratio of the red pigment is the same as that of pigment dispersion 5, pigment dispersion 14 was obtained in the same manner as in Example 6.

[0101] The viscosities of the obtained pigment dispersions 1 - 14 were measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., TV-22). The obtained results are shown in Table 2. All of the obtained pigment dispersions 1 to 14 had viscosities suitable for producing the film-forming compositions.

[0102]

Table 2

[0103] (Test Example: Production of Film-Forming Composition) After diluting each of the pigment dispersions 1 to 14 by adding PMA so that the solid content became 26% by weight, 1 drop of a 20% by weight PMA solution of BYK-375 (manufactured by Big Chemie Japan Co., Ltd.) was added as a surface conditioner to prepare 14 types of film-forming compositions 1 to 14. Note that the film-forming compositions 1 to 5 correspond to Examples, and the film-forming compositions 6 to 14 correspond to Comparative Examples. Next, using these film-forming compositions 1 to 14, cured films were produced by the following procedure.

[0104] (Production of Cured Film) Each film-forming composition was applied to a glass plate with a thickness of 1.1 mm and a size of 100 mm square using a spin coater (manufactured by Mikasa Co., Ltd., Spin Coater MS-150A). At this time, for each film-forming composition, three coated plates were prepared so that three films with different chromaticity x (values 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 three films was always less than 0.6500, and the chromaticity x of the other one was always greater than 0.6500. These coated plates were subjected to a heat treatment (pre-bake) at 90°C for 2 minutes and 30 seconds and a heat treatment (post-bake) at 230°C for 30 minutes.

[0105] For the glass plate (coated plate) on which the cured film after pre-baking and the cured film after post-baking were formed, the chromaticity coordinates (x, y) and luminance (Y) were measured using a colorimeter (manufactured by Otsuka Electronics Co., Ltd., MCPD-6800). Next, the contrast ratio (CR) was measured using a color luminance meter (manufactured by Topcon Techno House Co., Ltd., BM-5AS). Then, an approximate straight line (calibration curve) was created from the measured values of three coated plates with different chromaticities, and the luminance (Y) and contrast ratio (CR) of each cured film after pre-baking and after post-baking were obtained from this calibration curve. For the luminance and contrast ratio of each cured film after pre-baking and after post-baking, the luminance and contrast ratio when the chromaticity x was 0.6500 were adopted. Also, the film thickness of each coated plate was measured using a non-contact film thickness meter (manufactured by FilmMetrics, Inc., F20-EXR). For each cured film after pre-baking and after post-baking of the film-forming compositions 1 to 5, the difference in the luminance correction value (SimΔY) and the contrast ratio (CR%) with respect to the cured films of the film-forming compositions 10 to 14 as a control were determined. Also, the CR retention rate indicating the heat resistance of the contrast ratio (=(CR after post-baking - CR after pre-baking) / CR after pre-baking × 100) was determined. The results obtained are shown in Table 3.

[0106]

Table 3

[0107] From the results shown in Table 3, it was found that the cured films obtained with the film-forming compositions 1 to 5 had significantly higher contrast ratios (values of CR and CR%) at both the pre-baked and post-baked times compared to the cured films obtained with the film-forming compositions 10 to 14 having the same composition ratio of the red pigment. Also, the cured films obtained with the film-forming compositions 1 to 5 had higher luminance (SimΔY was positive) at both the pre-baked and post-baked times compared to the cured films obtained with the film-forming compositions 10 to 14. Among them, the cured films obtained with the film-forming compositions 1 to 4 had significantly higher luminance (SimΔY was positive) after post-baking. In addition, it was found that the cured films obtained from the film-forming compositions 1 to 4 were significantly superior in heat resistance of the contrast ratio (value of CR retention rate) compared to the cured film obtained from the film-forming composition 5.

Claims

1. A micronized pigment composition containing C.I. Pigment Red 291 and C.I. Pigment Red 177, wherein the micronized pigment composition is a milled product of a mixed powder of C.I. Pigment Red 291 and C.I. Pigment Red 177.

2. The micronized pigment composition according to Claim 1, wherein the weight ratio (PR291:PR177) of C.I. Pigment Red 291 (PR291) to C.I. Pigment Red 177 (PR177) is 1:99 to 99:

1.

3. A pigment dispersion comprising the micronized pigment composition according to Claim 1 or 2 and a solvent.

4. The pigment dispersion according to Claim 3, further containing a pigment derivative.

5. A film-forming composition containing the pigment dispersion according to Claim 3.

6. A color filter containing the film-forming composition according to Claim 5.

7. A method for producing a micronized pigment composition, comprising mixing C.I. Pigment Red 291 and C.I. Pigment Red 177 and performing a milling treatment.

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