Pigment dispersions and coating film-forming compositions

Abstract

To provide a pigment dispersion which has good storage stability and can suppress the change in a contrast ratio when formed into a cured film before and after storage, and a composition for film formation which contains the pigment dispersion.SOLUTION: A pigment dispersion contains a zinc halide phthalocyanine pigment, a dispersion agent, a dispersion resin, and at least two kinds of solvents, wherein 18 wt.% or more of the zinc halide phthalocyanine pigment is contained in the pigment dispersion based on the solid content, 0 wt.% or more and 10 wt.% or less of the dispersion agent is contained in the pigment dispersion based on the solid content, the dispersion agent is a resin type dispersion agent having an amine value of 140 mgKOH / g or more and having no acid value, and one kind of the solvent is cyclic ketone or cyclic ester.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a pigment dispersion and a composition for forming a coating film, and particularly to a pigment dispersion containing a zinc phthalocyanine halide pigment and a composition for forming a coating film.

Background Art

[0002] Conventionally, a composition for forming a coating film formed using a pigment dispersion in which a pigment is dispersed in a solvent has been applied to various uses such as a color filter applied to an image display device or a solid-state imaging device, an inkjet ink for recording or a color filter, a paint, and the like. Among these, particularly in the case of a color filter, due to the requirements of the market for high image quality in recent years, it has become necessary to increase the concentration and color purity of the pigment in the composition for forming a coating film. Therefore, it has also become necessary to increase the concentration of the pigment in the pigment dispersion.

[0003] A color filter generally includes pixels in which cured films having three primary colors of red, blue, and green are formed in regions partitioned by a black matrix on a transparent substrate. Among these, a copper phthalocyanine halide pigment is widely used as the pigment used for the green pixels. However, it has become difficult for the copper phthalocyanine halide pigment to cope with high image quality such as an improvement in the contrast ratio, and it has been proposed to use a zinc phthalocyanine halide pigment as an alternative pigment (Patent Document 1). <000​​​​​​​​​​​​[Patent Document 1] Japanese Patent Publication No. 2009-91551 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the inventors have found that even when zinc halide phthalocyanine pigment is dispersed in a predetermined solvent as described in Patent Document 1, storage stability may not be ensured if the pigment concentration in the pigment dispersion is 18% by weight or more. The pigment concentration in pigment dispersions for color filter applications is generally 16% by weight on a solids basis, so a pigment concentration of 18% by weight or more on a solids basis is a higher concentration than the conventional general case. Therefore, when alcohol-based solvents such as propylene glycol monomethyl ether were used in addition to solvents commonly used in color filter applications, it was found that while this contributed to storage stability, it promoted the crystal growth of zinc halide phthalocyanine pigment, and the contrast ratio of the cured film (color filter) finally obtained using the pigment dispersion after storage tended to deteriorate compared to before storage.

[0007] Therefore, the object of the present invention is to provide a pigment dispersion that has good storage stability and can suppress changes in the contrast ratio when it is cured before and after storage, and to provide a coating film-forming composition containing such a pigment dispersion. [Means for solving the problem]

[0008] The inventors diligently conducted research to solve the aforementioned problems. As a result, they found that by using a dispersion resin, a specific solvent, and a specific dispersant, and by adjusting the content of the dispersant in the pigment dispersion to a predetermined ratio range, the storage stability of the pigment dispersion is good even when the concentration of zinc halide phthalocyanine pigment in the pigment dispersion is 18% by weight or more, and the change in the contrast ratio when cured film is suppressed before and after storage. The gist of the present invention is as follows.

[0009] (1) A pigment dispersion comprising a zinc halide phthalocyanine pigment, a dispersant, a dispersion resin, and at least two solvents, wherein the zinc halide phthalocyanine pigment is present in the pigment dispersion in an amount of 18% by weight or more on a solid content basis, the dispersant is present in the pigment dispersion in an amount of more than 0% by weight and 10% by weight or less on a solid content basis, the dispersant is a resin-type dispersant with an amine value of 140 mgKOH / g or more and no acid value, and one of the solvents is a cyclic ketone or a cyclic ester. (2) The pigment dispersion according to item (1), wherein the cyclic ketone is at least one selected from cyclopentanone and cyclohexanone. (3) The pigment dispersion according to item (1) or (2), wherein the cyclic ester is at least one selected from γ-butyrolactone and δ-valerolactone. (4) The pigment dispersion according to any one of items (1) to (3), wherein the other solvent is propylene glycol monomethyl ether acetate. (5) The pigment dispersion according to any one of items (1) to (4), wherein the dispersion resin has an acid value of 100 mg KOH / g or more and 150 mg KOH / g or less, and is a resin that does not have an amine value. (6) A film-forming composition comprising a pigment dispersion and a film-forming component as described in any one of items (1) to (5). [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a pigment dispersion that has good storage stability and can suppress changes in the contrast ratio of the cured film before and after storage. Furthermore, it is possible to provide a coating film-forming composition containing such a pigment dispersion. [Modes for carrying out the invention]

[0011] (Pigment dispersion) A pigment dispersion according to an embodiment of the present invention comprises a zinc halide phthalocyanine pigment, a dispersant, a dispersion resin, and at least two solvents. The zinc halide phthalocyanine pigment is present in the pigment dispersion at a concentration of 18% by weight or more on a solids basis. The dispersant is a resin-type dispersant with an amine value of 140 mgKOH / g or more and no acid value, and is present in the pigment dispersion at a concentration of more than 0% by weight and no more than 10% by weight on a solids basis. The solvent includes a cyclic ketone or a cyclic ester. Note that "on a solids basis" means considering only the solids or non-volatile content, and not the volatile content.

[0012] Thus, by using a combination of a cyclic ketone or cyclic ester as a solvent and other solvents, even at high concentrations of 18% by weight or more based on the solid content of the pigment dispersion, by incorporating a specific dispersant within a predetermined concentration range and using it in combination with a dispersion resin, good storage stability can be achieved, and changes in the contrast ratio of the cured film can be suppressed before and after storage of the pigment dispersion. Although the reason for this is not entirely clear, it is thought that the specific solvent suppresses the association between the specific resin-type dispersant and the dispersion resin, preferentially binding the dispersant to the pigment surface, and that the dispersant on the pigment surface and the dispersion resin become compatible due to the presence of the specific solvent, thereby contributing to the stabilization of the viscosity of the pigment dispersion, i.e., good storage stability. Furthermore, as a result, it is thought that changes in the contrast ratio of the final cured film can be suppressed before and after storage of the pigment dispersion. In this way, changes in the contrast ratio can be suppressed, allowing the pigment dispersion to be stored for a predetermined period after preparation, enabling efficient use of raw materials without waste, and is effective in reducing environmental impact and manufacturing costs.

[0013] The zinc halide phthalocyanine pigment mentioned above only needs to satisfy the following formula (1).

[0014] [ka]

[0015] (In formula (1), the central metal element M is Zn, X is each independently an element selected from the group consisting of H, Cl, and Br, and at least one is Cl or Br.)

[0016] Examples of such zinc phthalocyanine halide pigments include C.I. Pigment Green (PG) 58 and 59 when indicated by the Color Index (C.I.) number.

[0017] The concentration of the zinc phthalocyanine halide pigment in the pigment dispersion is 18% by weight or more on a solid content basis. From the viewpoint of storage stability, the upper limit is preferably 25% by weight or less, more preferably 22% by weight or less. In the case of a pigment dispersion for a color filter, it is generally 16% by weight or less, and a concentration of 18% by weight or more of the pigment can be said to be a higher concentration than such a general concentration. Generally, when the pigment concentration is increased, the viscosity increases exponentially, so it can be said that even a 1% by weight difference in concentration has a very large impact on viscosity stability. However, even in such a high-concentration case, by combining a predetermined solvent, a predetermined resin-type dispersant within a predetermined concentration range, and a dispersion resin, it is possible to exhibit the characteristics of the pigment well and provide a pigment dispersion and a coating film-forming composition with good viscosity stability.

[0018] In addition to the above-mentioned zinc phthalocyanine halide pigment, pigments for color adjustment and complementary colors can be further used in the pigment dispersion. Specifically, examples include yellow pigments such as C.I. Pigment Yellow 14, 74, 83, 138, 139, 150, etc., blue pigments such as C.I. Pigment Blue 7, and green pigments such as C.I. Pigment Green 7, 36, etc. when indicated by the Color Index (C.I.) number. The concentrations of these pigments can be appropriately determined according to the use and the like, but for example, they can be 0.1 to 10.0% by weight in the pigment dispersion on a solid content basis.

[0019] The average primary particle diameter of the pigment contained in the pigment dispersion can be appropriately adjusted within a range that does not affect contrast or the like. The average primary particle diameter is preferably 10 to 100 nm, more preferably 10 to 50 nm, and even more preferably 10 to 30 nm. The primary particle diameter can be measured, for example, from an image obtained by photographing the pigment with a transmission electron microscope at a magnification of 100,000 times. Also, for the average primary particle diameter, for example, 100 particles can be measured and the average value thereof can be taken as the average primary particle diameter. Further, the pigment may be one that has been subjected to a conventionally known refinement treatment (for example, solvent salt milling treatment, etc.) as necessary.

[0020] The dispersant is a resin-type dispersant having an amine value of 140 mgKOH / g or more and no acid value. Since this resin-type dispersant has a high amine value, in the pigment dispersion, it generally tends to aggregate by associating with a group that promotes the alkali solubility of the dispersion resin described later, and as a result, the viscosity tends to increase. However, the coexistence of a specific solvent can suppress the association with the dispersion resin and realize good viscosity stability of the pigment dispersion. The amine value is more preferably 150 mgKOH / g or more. Also, from the viewpoint of developability, the upper limit is preferably 200 mgKOH / g or less. The amine value (amine value in terms of solid content) can be determined, for example, by a method conforming to DIN 16945. Incidentally, "having no acid value" means that the value obtained by a method conforming to DIN EN ISO 2114 for the acid value (acid value in terms of solid content) is 0 mgKOH / g.

[0021] Such resin-type dispersants can use commercially available ones. For example, manufactured by BYK Chemie Japan Co., Ltd.: DISPERBYK (registered trademark)-LPN23097, LPN22956, etc. can be cited.

[0022] The concentration of the dispersant in the pigment dispersion is more than 0% by weight and 10% by weight or less, based on solid content. From the viewpoint of viscosity stabilization (i.e., storage stability) and developability during color filter manufacturing, it is more preferably 1% by weight or more and 8% by weight or less, and even more preferably 2% by weight or more and 6% by weight or less. Furthermore, based on solid content, it is preferable that the dispersant is in amounts of 5% by weight or more and 50% by weight or less, relative to 100 parts by weight of zinc halide phthalocyanine pigment, or, if other pigments are included, the total content of all pigments, relative to 100 parts by weight.

[0023] As mentioned above, the dispersion resin is used to improve the dispersibility of the pigment in the pigment dispersion when a high concentration of zinc halide phthalocyanine pigment is included, and to improve the dispersibility of particles in the coating film-forming composition when a coating film-forming composition is formed using the pigment dispersion. The dispersion resin is not particularly limited as long as it can ensure the dispersibility and viscosity stability of the pigment and the like when combined with the predetermined resin-type dispersant mentioned above, but it is preferable that the resin has an acid value of 100 mg KOH / g or more and 150 mg KOH / g or less, and has no amine value. The acid value is more preferably 110 mg KOH / g or more and 140 mg KOH / g or less. The acid value (acid value when calculated on a solid content basis) can be determined, for example, by a method in accordance with DIN EN ISO 2114. "Having no amine value" means that the value of the amine value (amine value when calculated on a solid content basis) when determined, for example, by a method in accordance with DIN 16945, is 0 mg KOH / g.

[0024] Dispersion resins tend to contribute to the good dispersibility of particles in a coating composition when the coating-forming component used in the coating composition described later is a polymerizable component, particularly a photopolymerizable component. Examples of such dispersion resins include alkali-soluble resins having an acid value within a predetermined range and no amine value. Such alkali-soluble resins can be those described in Japanese Patent Application Publication No. 2009-179789. That is, alkali-soluble resins can be appropriately selected from among, for example, linear organic polymer polymers having at least one alkali-solubility-promoting group (e.g., a carboxyl group, a phosphate group, a sulfonic acid group, etc.) in the molecule. More preferably, these are soluble in organic solvents and developable with a weakly alkaline aqueous solution.

[0025] Suitable alkali-soluble resins include copolymers of (meth)acrylic acid and other monomers 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.

[0026] Other monomers copolymerizable with (meth)acrylic acid include alkyl (meth)acrylates, aryl (meth)acrylates, and vinyl compounds. Here, the hydrogen atoms of the alkyl and aryl groups may be substituted with substituents.

[0027] Specific examples of the alkyl (meth)acrylate and aryl (meth)acrylate mentioned above 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.

[0028] Examples of the vinyl compounds include styrene, α-methylstyrene, vinyltoluene, glycidyl methacrylate, glycidyl acrylate, acrylonitrile, vinyl acetate, N-vinylpyrrolidone, tetrahydrofurfuryl methacrylate, polystyrene macromonomer, polymethyl methacrylate macromonomer, CH2=CR 5 R 6 CH2=C(R 5 )(COOR 7 )(Here, R 5 R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. 6 R represents an aromatic hydrocarbon ring with 6 to 10 carbon atoms. 7 This represents an alkyl group having 1 to 8 carbon atoms or an aralkyl group having 6 to 12 carbon atoms. Examples include:

[0029] These copolymerizable monomers may be used individually or in combination of two or more.

[0030] The weight-average molecular weight of the dispersion resin is preferably 5,000 to 30,000, from the viewpoint of the dispersion stability of the pigment when used in combination with a dispersant.

[0031] Furthermore, the acid value of the dispersion resin can be controlled by appropriately adjusting the type and amount of monomer used, as mentioned above. The same applies to the amine value.

[0032] A commercially available dispersion resin can be used. For example, Banarezin PSY-C1 (acrylic resin, acid value: 131 mgKOH / g, amine value: 0 mgKOH / g) manufactured by Shin Nakamura Chemical Industry Co., Ltd. can be used.

[0033] The concentration of the dispersed resin in the pigment dispersion is preferably 1% to 10% by weight, and more preferably 3% to 8% by weight, based on solid content. Furthermore, based on solid content, it is preferable that the concentration is 5 to 50 parts by weight, relative to 100 parts by weight of zinc halide phthalocyanine pigment, or, if other pigments are included, relative to 100 parts by weight of the total content of all pigments.

[0034] The solvent is used in combination of two or more types, one of which is a cyclic ketone or cyclic ester. At least one cyclic ketone or cyclic ester is required. That is, the solvent should contain at least one selected from cyclic ketones and cyclic esters, and at least one selected from other solvents. Using a solvent containing cyclic ketones and / or cyclic esters in this way contributes to stabilizing the viscosity of the pigment dispersion and suppressing changes in the contrast ratio, as described above. Examples of cyclic ketones include cyclopentanone (XPN), cyclohexanone, isophorone, and their derivatives. Of these, at least one selected from cyclopentanone and cyclohexanone is preferred from the viewpoint of solvent viscosity. Examples of cyclic esters include γ-butyrolactone (GBL), δ-valerolactone, and their derivatives. Of these, at least one selected from γ-butyrolactone and δ-valerolactone is preferred from the viewpoint of solvent viscosity.

[0035] Other solvents besides cyclic ketones and cyclic esters are not particularly limited and can be appropriately selected depending on the application. For example, when applied to color filter applications, such other solvents can be appropriately selected depending on the type of film-forming component described later, and include various organic solvents such as aromatic, acyclic ketone, acyclic ester, and aliphatic solvents. Of these, from the viewpoint of film-forming properties, organic solvents selected from aromatic, acyclic ketone, and acyclic ester types are preferred, with acyclic esters being particularly preferred. These organic solvents may be used individually or in combination of two or more types.

[0036] Examples of aromatic organic solvents include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene.

[0037] Examples of acyclic ketone organic solvents include methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, acetylacetone, and acetophenone.

[0038] Examples of acyclic ester organic solvents include ethyl 3-ethoxypropionate, triacetin, n-amyl acetate, isoamyl acetate, isobutyl acetate, cyclohexyl acetate, propylene glycol monomethyl ether propionate, 1,3-butylene glycol diacetate, propylene glycol diacetate, dibasic acid esters, ethyl acetate, n-butyl acetate, propyl acetate, 3-methoxy-3-methylbutyl acetate, 3-methoxybutyl acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate (PMA). Of these, PMA is particularly preferred.

[0039] Examples of aliphatic organic solvents include aliphatic hydrocarbons such as n-pentane, n-hexane, and n-heptane.

[0040] When used in the preparation of the coating film-forming composition described later, the total amount of solvent added can be such that, from the viewpoint of handling, the concentration of solids including pigments, etc., is 20% by weight or more and 40% by weight or less. The amount of cyclic ketones and / or cyclic esters added is preferably 5 parts by weight or more and 40 parts by weight or less per 100 parts by weight of the total solvent.

[0041] In addition to the components mentioned above, the pigment dispersion may contain other components as needed. Examples of such components include antioxidants, pigment derivatives, adhesion promoters, anti-aggregation agents, and surface modifiers (leveling agents).

[0042] The pigment dispersion described above can be obtained by adding the aforementioned pigment, dispersant, dispersion resin, and solvent (and other components as needed) to a known dispersion machine such as a bead mill, sand mill, disperser, or paint conditioner, and dispersing them.

[0043] (Composition for coating film formation) A coating film-forming composition according to an embodiment of the present invention comprises the aforementioned pigment dispersion and coating film-forming component. Because it contains the aforementioned specific pigment dispersion, the cured film obtained using this coating film-forming composition exhibits suppressed changes in contrast ratio even before and after the pigment dispersion has been stored for a predetermined period.

[0044] Examples of film-forming components include polymerizable components, polymers, and mixtures thereof.

[0045] Examples of polymers include thermoplastic urethane resins, (meth)acrylic resins, polyamide resins, polyimide resins, styrene-maleic acid resins, polyester resins, silicone resins, and cardo resins.

[0046] The polymer content in the coating film-forming composition is preferably 10 to 60% by weight, and more preferably 20 to 55% by weight, based on the solid content of the composition. The polymer content in the coating film-forming composition is the total amount of polymer and the dispersed resin contained in the pigment dispersion, based on the solid content. The molecular weight of the polymer can be determined as appropriate.

[0047] Among the polymers used as film-forming components as described above, alkali-soluble resins that are soluble in alkaline solutions are preferred. The inclusion of an alkali-soluble resin can, for example, improve pattern formation when the pigment composition is applied to the photolithography process during the manufacture of color filters. The aforementioned alkali-soluble resins can be used. Furthermore, the dispersion resin used for the pigment dispersion and the film-forming component may be the same or different. From the viewpoint of developability, the weight-average molecular weight of the polymer is preferably 5000 to 50000.

[0048] Various alkali-soluble resins are commercially available that can be used as coating film-forming components. Specific examples are listed below, but the list is not limited to these. Showa Denko Corporation: Lipoxy (registered trademark) SPC-2000 Mitsubishi Chemical Corporation: Diana-L (registered trademark) NR series, Osaka Organic Chemical Industry Co., Ltd.: Viscoat R-264, KS Resist 106, SOP-005, Daicel Corporation: Cyclomer (registered trademark) P series, Plaxel (registered trademark) CF200 series, Daicel Ornex Co., Ltd.: Ebecryl (registered trademark) 3800, Soken Chemical Co., Ltd.: Follett (registered trademark) ZAH110, etc.

[0049] As for polymerizable components, photopolymerizable components are preferred because they can be easily patterned by developing (negative development).

[0050] The usable photopolymerizable components include photopolymerizable compounds and photopolymerization initiators. Such photopolymerizable compounds and photopolymerization initiators can be those described in, for example, Japanese Patent Application Publication No. 2009-179789. More specifically, such photopolymerizable compounds are addition polymerizable compounds having at least one ethylenically unsaturated double bond, and are 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 art and can be used without particular limitation. Photopolymerizable compounds can have chemical forms such as monomers, prepolymers, i.e., dimers, trimers and oligomers, or mixtures thereof, and copolymers thereof.

[0051] Examples of monomers and copolymers thereof include unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), their esters, and amides. Preferably, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and aliphatic polyhydric amine compounds are used. 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 epoxys, and dehydration condensation reaction products with monofunctional or polyfunctional carboxylic acids are also suitably used. 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. As another example, it is also possible to use a group of compounds in which the unsaturated carboxylic acids mentioned above are replaced with unsaturated phosphonic acids, styrene, vinyl ethers, etc.

[0052] The photopolymerizable compound is preferably present in the coating film-forming composition at a concentration of 5 to 70% by weight, more preferably 10 to 60% by weight, based on the solid content. These compounds may be used individually or in combination of two or more. Furthermore, the appropriate structure, formulation, and amount of the photopolymerizable compound can be arbitrarily selected from viewpoints such as the degree of polymerization inhibition by oxygen, resolution, coverage, refractive index change, and surface tackiness.

[0053] As the aforementioned photopolymerization initiator, one described in Japanese Patent Publication No. 2009-179789 can also be used. Examples include 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, and oxime ester-based compounds. Specific examples of benzophenone-based photopolymerization initiators include, for example, benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, and 4,4'-dichlorobenzophenone.

[0054] The content of the photopolymerization initiator in the coating film-forming composition is preferably 0.1 to 10% by weight, and more preferably 0.5 to 5% by weight, based on the solid content of the composition. When the content of the photopolymerization initiator is within this range, the polymerization reaction proceeds well, and it is possible to form a film with good strength.

[0055] The coating film-forming composition may also contain the aforementioned alkali-soluble resin if it includes a photopolymerizable component as a coating film-forming component.

[0056] The coating film-forming composition may contain various additives as needed, such as sensitizers (sensitizing dyes), chain transfer agents, fluorine-based organic compounds, thermal polymerization initiators, thermal polymerization components, fillers, dispersants, surfactants, adhesion promoters, antioxidants, anti-aggregation agents, and surface modifiers (leveling agents). In addition to the aforementioned dispersants, other dispersants such as phosphate ester-based dispersants may also be used.

[0057] The coating film-forming composition can be obtained, for example, by mixing and stirring the aforementioned components using a disperser, shaker, or the like. The resulting mixture may be filtered as needed. [Examples]

[0058] Embodiments of the present invention will be described in detail below based on examples.

[0059] The components used in the following examples and comparative examples are as shown in Table 1. (1) Pigments ·A110 Zinc halide phthalocyanine pigment, CIPG58, manufactured by DIC Corporation, Fastogen® Green A110, solids content 100% by weight (2) Dispersant LPN22956 Manufactured by Big Chemie Japan Co., Ltd., DISPERBYK (registered trademark) - LPN22956. Amine value: 160 mg KOH / g, Acid value: 0 mg KOH / g, Solids content: 40% by weight, Volatile content: PMA LPN6919 Manufactured by Big Chemie Japan Co., Ltd., DISPERBYK (registered trademark)-LPN6919. Amine value: 120 mg KOH / g, Acid value: 1 mg KOH / g, Solids content: 60% by weight, Volatile content: PMA BYK9077 Manufactured by BYK Chemie Japan Co., Ltd., BYK(registered trademark)-9077. Amine value: 46 mg KOH / g, Acid value: 0 mg KOH / g, Solids content: 100% by weight PB821-F Ajisper (registered trademark) PB821-F, manufactured by Ajinomoto Fine Techno Co., Ltd. Amine value: 10 mg KOH / g, Acid value: 17 mg KOH / g, Solids content: 100% by weight (3) Dispersion resin ·Dispersion resin A Acrylic resin, amine value: 0 mg KOH / g, acid value: 121 mg KOH / g, weight-average molecular weight: 19900, solids content: 35% by weight, volatile content: PMA (4) Solvent GBL BLO, γ-butyrolactone, manufactured by Ashland Japan Co., Ltd. ·XPN Cyclopentanone, manufactured by Nippon Zeon Co., Ltd. PM Methoxypropanol and propylene glycol monomethyl ether, manufactured by Daicel Corporation. PMA Propylene glycol monomethyl ether acetate, manufactured by KH Neochem Co., Ltd.

[0060] (Examples 1-5, Comparative Examples 1-8) Each component was added to a sand mill to achieve the composition shown in Table 1. 560 parts by weight of φ0.8 mm zirconia beads were added to 140 parts by weight of the resulting mixture, and the mixture was dispersed at 2000 rpm for 20 minutes. Next, the φ0.8 mm zirconia beads were removed, and 560 parts by weight of φ0.05 mm zirconia beads were added, and the mixture was dispersed at 2000 rpm for 20 minutes. After that, the zirconia beads were removed. Of Examples 1-5 and Comparative Examples 1-8, pigment dispersions were obtained in Examples 1-5 and Comparative Examples 1-5 and 8, but dispersion was impossible in Comparative Examples 6 and 7, and pigment dispersions could not be obtained. Comparative Example 4 is a pigment dispersion with a pigment concentration typical for color filter applications. The weight ratios of pigment, dispersant, and dispersion resin in Table 1 are shown on a solid content basis. The weight ratio of PMA, the solvent in Table 1, takes into account the amount contained in the dispersant and dispersion resin.

[0061] (evaluation) <Viscosity stability (storage stability) of pigment dispersions> The pigment dispersions obtained in Examples 1-5 and Comparative Examples 1-5 and 8 were used to measure the viscosity immediately after preparation (initial viscosity) and the viscosity after storage at 25°C for one month from immediately after preparation (1m viscosity) using an E-type viscometer "RE-80L" manufactured by Toki Sangyo Co., Ltd. From the obtained measurements, the ratio of the 1m viscosity to the initial viscosity was calculated as the 1m change rate (= 1m viscosity / initial viscosity × 100). The results are shown in Table 1.

[0062] <Contrast Ratio (CR) Stability> <<Preparation of coating film-forming composition>> For the pigment dispersions obtained in Examples 1 to 5, Comparative Examples 1 to 5, and 8, immediately after preparation and after storage at 25°C for 1 week after preparation, a coating film-forming composition was prepared as follows. That is, in the coating film-forming composition, based on the solid content, the concentration of the pigment was 11% by weight, and the total amount of the dispersion resin, dispersant, and coating film-forming component was 100% by weight with respect to 100% by weight of the pigment. A coating film-forming component (Forex (registered trademark) ZAH110, acrylic polymer, alkali-soluble, solid content 35.0% by weight, volatile component: PMA, manufactured by Soken Chemical & Engineering Co., Ltd.) and PMA were added to the pigment dispersion and stirred to prepare each coating film-forming composition.

[0063] <<Formation of cured film>> The obtained coating film-forming compositions were each applied to a glass plate with a thickness of 1 mm and a size of 100 mm square using a spin coater (Spin Coater MS-150A, manufactured by Mikasa Co., Ltd.). At this time, for each coating film-forming composition, three coated plates were prepared such that three coating films with different chromaticity y values were formed. That is, the rotation speed of the spin coater was changed to vary the thickness, and for one of the three plates, the chromaticity y was always less than 0.5600, and for another one, the chromaticity y was always greater than 0.5600. The obtained coated plates were pre-dried (Prebake) at 90°C for 2.5 minutes, and further dried (Postbake) at 230°C for 30 minutes to obtain a cured film.

[0064] <<Measurement of CR>> For the cured film obtained by Postbake, the chromaticity coordinates (x, y) were measured using a colorimeter (MCPD-6800, manufactured by Otsuka Electronics Co., Ltd.), and the contrast ratio was measured using a color luminance meter (BM-5AS, manufactured by Topcon Techno House Co., Ltd.). An approximate straight line (calibration curve) was obtained from the measured values of the three coated plates prepared as described above for each coating film, and the contrast ratio when the chromaticity y was 0.5600 was adopted as the result. The measured value of CR immediately after preparation (initial CR), the measured value of CR after storage at 25°C for 1 week after preparation (1wCR), and from the obtained measured values, the ratio of 1wCR to the initial CR was calculated as the CR retention rate (= 1wCR / initial CR × 100). The results are shown in Table 1.

[0065] <Developability> <<Preparation of coating film-forming composition>> Using the pigment dispersions obtained in Examples 1-5 and Comparative Examples 1-5 and 8, film-forming compositions were prepared immediately after their preparation as follows. Specifically, in the film-forming composition, the pigment concentration was 3.75% by weight on a solids basis, and the total amount of the dispersion resin, dispersant, and film-forming component was 300% by weight relative to 100% by weight of pigment. Film-forming components (manufactured by Soken Chemical Co., Ltd., Follett® ZAH110, acrylic polymer, alkali soluble, solids content 35.0% by weight, volatile content: PMA), a dispersant (manufactured by Nippon Lubrizol Co., Ltd., Solspers® 41000, phosphate ester dispersant, acid value 50 mg KOH / g, amine value 0 mg KOH / g, solids content 100% by weight) and PMA were added to the pigment dispersion and stirred to prepare each film-forming composition. Furthermore, Follett® ZAH110 and Solspers® 41000 were added in such a weight ratio of 8:2 for their solid content.

[0066] <<Measurement of Development Time (BT)>> A coating-forming composition was deposited onto a 0.5 mm thick, 100 mm square alkali-free glass substrate using a spin coater (Mikasa Corporation, Spin Coater MS-150A) to a film thickness of 0.7 μm. The film was then dried on a hot plate at 90°C for 90 seconds to obtain evaluation coated plates. Each evaluation coated plate was developed using a 100-fold diluted developer (Parker Corporation, PK-DEX1510) with a wide-angle nozzle at a liquid temperature of 25°C. The development time was defined as the time at which the coating film was completely removed. The measurement results are shown in Table 1.

[0067] [Table 1]

[0068] As shown in Table 1, even when zinc halide phthalocyanine pigment is present in an amount of 18% by weight or more on a solids basis, by combining a predetermined solvent, a predetermined resin-type dispersant, and a dispersion resin, the Examples show better viscosity stability of the pigment dispersion compared to the Comparative Example, and the change in contrast ratio before and after storage of the pigment dispersion for a predetermined period is suppressed. Furthermore, regarding development time, Examples 1 to 5 show comparable results to Comparative Example 4, which has a conventional general composition. As described above, the predetermined pigment dispersion and the coating film-forming composition containing it can be well applied to, for example, color filters.

Claims

1. A pigment dispersion comprising a zinc halide phthalocyanine pigment, a dispersant, a dispersion resin, and at least two solvents, The zinc halide phthalocyanine pigment is present in the pigment dispersion at a concentration of 18% by weight or more, based on solid content. The dispersant is contained in the pigment dispersion in an amount of 1% by weight or more and 8% by weight or less, based on the solid content. The aforementioned dispersant is limited to resin-type dispersants with an amine value of 140 mg KOH / g or higher and no acid value. The aforementioned dispersion resin has an acid value of 100 mg KOH / g or more and 150 mg KOH / g or less, and is a resin without an amine value, and is present in the pigment dispersion at a concentration of 1% to 10% by weight on a solid content basis. A pigment dispersion in which one of the aforementioned solvents is at least one cyclic ester selected from γ-butyrolactone and δ-valerolactone.

2. The pigment dispersion according to claim 1, wherein one of the solvents is propylene glycol monomethyl ether acetate.

3. A coating film-forming composition comprising the pigment dispersion and coating film-forming component described in claim 1 or 2.

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