Red pigment dispersion

Abstract

To provide a red pigment dispersion capable of suppressing increase in viscosity after preparation and increase in coarse particle number.SOLUTION: A red pigment dispersion includes at least a red pigment, a derivative, a dispersant and a solvent. The derivative has a chemical structure shown by the chemical formula 1; the dispersant is a polymer dispersant having an acid value of 80-120 mgKOH / g and having a carboxyl group; the derivative is included at a ratio of 10-40 pts.wt. to 100 pts.wt. of the red pigment and the derivative in total; and the dispersant is included at a ratio of 30-50 pts.wt. to 100 pts.wt. of the total solid content. (In the chemical formula 1, R1 to R4 are H and a halogen atom; n is an integer of 1-5; at least one of X1 and X2 is C1-6-alkyl-NR5R6; and the other is a H and C1-6 alkyl group, etc.; and R5 and R6 are H, etc.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a red pigment dispersion containing a red pigment, a specific derivative, a specific dispersant, and a solvent. [Background technology]

[0002] Color filters are widely used as components of liquid crystal displays (LCDs). LCDs are widely used in display devices such as monitors, televisions, notebook computers, tablet computers, and smartphones, and high image quality is required for these display devices. Meanwhile, in recent years, there has been an increasing demand for reduced power consumption from the perspective of protecting the global environment, and color filters are now required to have high brightness and high contrast.

[0003] Color filters are commonly produced by forming a coating film by a photolithography process using a colored photosensitive composition, which is prepared by dissolving or dispersing colorants such as red, green, and blue dyes or pigments in a photosensitive resin. As mentioned above, one method for improving the image quality of color filters is to increase the concentration of the dye or pigment in the colored photosensitive composition to improve color purity. However, this reduces the transmittance of light from the LCD backlight, resulting in increased power consumption. Another method for achieving high contrast is to eliminate large pigment particles and disperse the pigment in the colored photosensitive composition as small particles with a diameter equal to or smaller than the wavelength of light. However, the smaller the pigment particle size, the more likely it is to aggregate, making it difficult to uniformly disperse the pigment in the colored photosensitive composition. Therefore, there is a need for the development of pigments that can realize high-brightness, high-contrast color filters that can achieve the same brightness with less light than conventional methods without increasing the concentration of the pigment.

[0004] For example, Patent Document 1 discloses a pigment dispersion that is easy to handle and can achieve both high coloration and high brightness, and that contains a halogenated zinc phthalocyanine green pigment containing 3.5% by weight or more of chlorine atoms and a specific dispersant. By using the pigment disclosed in Patent Document 1, it is expected that the brightness and contrast of color filters will increase to a certain extent. However, since it is generally not easy to uniformly disperse a pigment in a colored photosensitive composition, methods such as using a dispersant or pigment derivative as a component constituting the colored photosensitive composition, or using a surface-treated pigment, are generally adopted.

[0005] Patent Document 2 discloses the use of hydroxyamide derivatives to provide long standby times and long-term ejection stability when used in thermal inkjet printers, and gives a specific example of a phthalimide derivative as a hydroxyamide derivative. Patent Document 3 discloses the use of a substance having a pyrrolidone ring in a recording ink containing water and polyvinylpyrrolidone to prevent hydration between the water and polyvinylpyrrolidone, and gives a specific example of phthalimide.

[0006] Patent Document 4 discloses that by using a phthalocyanine pigment and an acid-type phthalimide derivative, it is possible to suppress an increase in viscosity after preparing a phthalocyanine pigment dispersion and to suppress a decrease in contrast of a coating film after preparing a colored composition containing the dispersion. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-38584 [Patent Document 2] Japanese Patent Application Publication No. 10-204359 [Patent Document 3] Japanese Patent Application Publication No. 7-331146 [Patent Document 4] Japanese Patent Application Laid-Open No. 2018-80217 Summary of the Invention [Problem to be solved by the invention]

[0008] The present inventors attempted to suppress the increase in viscosity after the preparation of a pigment dispersion by replacing the green or blue pigment disclosed in Patent Document 4 with a red pigment (CI Pigment Red 122 / quinacridone pigment) and using it in combination with a phthalimide derivative having an acidic group. However, although the resulting red pigment dispersion had good dispersibility, it had the problem of having a somewhat large number of coarse particles.

[0009] An object of the present invention is to provide a red pigment dispersion that can suppress an increase in viscosity after preparation and also suppress an increase in the number of coarse particles. [Means for solving the problem]

[0010] The present inventors conducted extensive research to solve the above problems and found that the use of a specific base-type phthalimide derivative in combination with a specific dispersant can suppress an increase in viscosity of a red pigment dispersion while also suppressing the number of coarse particles, thereby completing the present invention.

[0011] Specifically, the present invention provides: A red pigment dispersion containing at least a red pigment, a derivative, a dispersant, and a solvent, The derivative has a chemical structure represented by Chemical Formula 1: the dispersant is a polymer dispersant having an acid value of 80 mgKOH / g or more and 120 mgKOH / g or less and having a carboxyl group, The derivative is contained in an amount of 10 parts by weight or more and 40 parts by weight or less per 100 parts by weight of the total weight of the red pigment and the derivative, The dispersant is contained in an amount of 30 parts by weight or more and 50 parts by weight or less relative to 100 parts by weight of the total weight of all solids. This relates to a red pigment dispersion.

[0012] [ka]

[0013] (In Chemical Formula 1, R1 to R4 each independently represent a hydrogen atom or a halogen atom. n represents an integer of 1 to 5; X1 and X2 are each independently a hydrogen atom, C 1-6 Alkyl, benzyl, phenyl or C 1-6 alkyl-NR5R6 (R5 and R6 may be the same or different and are hydrogen atoms, phenyl or C 1-6 represents alkyl.) (However, at least one of X1 and X2 is C 1-6 It is a group represented by alkyl-NR5R6.

[0014] The red pigment dispersion of the present invention contains a basic phthalimide derivative represented by Chemical Formula 1 and a polymer dispersant having an acid value of 80 mgKOH / g or more and 120 mgKOH / g or less and having a carboxyl group as the acidic group, in specific ratios, thereby making it possible to suppress an increase in viscosity and also to suppress the number of coarse particles.

[0015] The red pigment is preferably one or more selected from the group consisting of CI Pigment Red 122, CI Pigment Red 177, and CI Pigment Red 254.

[0016] The dispersant preferably has an amine value of 0 mgKOH / g.

[0017] The red pigment dispersion of the present invention is preferably a pigment dispersion for a color filter used in a display device or an image sensor. [Effects of the Invention]

[0018] According to the present invention, it is possible to suppress an increase in viscosity of a red pigment dispersion suitable for use in a color filter used in a display device or an image sensor, and also to suppress the number of coarse particles. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described.

[0020] As the red pigment that can be used in the present invention, C.I.Pigment Red 1, C.I.Pigment Red 2, C.I.Pigment Red 3, C.I.Pigment Red 4, C.I.Pigment Red 5, C.I.Pigment Red 6, C.I.Pigment Red 7, C.I.Pigment Red 8, C.I.Pigment Red 9, C.I.Pigment Red 10, C.I.Pigment Red 11, C.I.Pigment Red 12, C.I.Pigment Red 14, C.I.Pigment Red 15, C.I.Pigment Red 16, C.I.Pigment Red 17, C.I.Pigment Red 18, C.I.Pigment Red 21, C.I.Pigment Red 22, C.I.Pigment Red 23, C.I.Pigment Red 31, C.I.Pigment Red 32, C.I.Pigment Red 38, C.I.Pigment Red 41, C.I.Pigment Red 48, C.I.Pigment Red 48:1, C.I.Pigment Red 48:2, C.I.Pigment Red 48:3, C.I.Pigment Red 48:4, C.I.Pigment Red 48:5, C.I.Pigment Red 49, C.I.Pigment Red 52, C.I.Pigment Red 52:1, C.I.Pigment Red 52:2, C.I.Pigment Red 53:1, C.I.Pigment Red 54, C.I.Pigment Red 57:1, C.I.Pigment Red 58, C.I.Pigment Red 60:1, C.I.Pigment Red 63, C.I.Pigment Red 64:1, C.I.Pigment Red 68, C.I.Pigment Red 81:1, C.I.Pigment Red 83, C.I.Pigment Red 88, C.I.Pigment Red 89, C.I.Pigment Red 95, C.I.Pigment Red 112, C.I.Pigment Red 114, C.I.Pigment Red 119, C.I.Pigment Red 122、C.I.Pigment Red 123、C.I.Pigment Red 129、C.I.Pigment Red 136、C.I.Pigment Red 144、C.I.Pigment Red 146、C.I.Pigment Red 147、C.I.Pigment Red 149、C.I.Pigment Red 150、C.I.Pigment Red 164、C.I.Pigment Red 166、C.I.Pigment Red 168、C.I.Pigment Red 169、C.I.Pigment Red 170、C.I.Pigment Red 171、C.I.Pigment Red 172、C.I.Pigment Red 175、C.I.Pigment Red 176、C.I.Pigment Red 177、C.I.Pigment Red 178、C.I.Pigment Red 179、C.I.Pigment Red 181、C.I.Pigment Red 183、C.I.Pigment Red 184、C.I.Pigment Red 185、C.I.Pigment Red 187、C.I.Pigment Red 188、C.I.Pigment Red 190、C.I.Pigment Red 193、C.I.Pigment Red 194、C.I.Pigment Red 200、C.I.Pigment Red 202、C.I.Pigment Red 206、C.I.Pigment Red 207、C.I.Pigment Red 208、C.I.Pigment Red 209、C.I.Pigment Red 210、C.I.Pigment Red 211、C.I.Pigment Red 213、C.I.Pigment Red 214、C.I.Pigment Red 216、C.I.Pigment Red 220、C.I.Pigment Red 221、C.I.Pigment Red 224、C.I.Pigment Red 226、C.I.Pigment Red 237、C.I.Pigment Red 238、C.I.Pigment Red 239、C.I.Pigment Red 242、C.I.Pigment Red 245、C.I.Examples of red pigments that can be used include, but are not limited to, CI Pigment Red 247, CI Pigment Red 248, CI Pigment Red 251, CI Pigment Red 253, CI Pigment Red 254, CI Pigment Red 255, CI Pigment Red 256, CI Pigment Red 257, CI Pigment Red 258, CI Pigment Red 260, CI Pigment Red 262, CI Pigment Red 263, CI Pigment Red 264, CI Pigment Red 266, CI Pigment Red 268, CI Pigment Red 269, CI Pigment Red 270, CI Pigment Red 271, CI Pigment Red 272, CI Pigment Red 279, and CI Pigment Red 291. These red pigments may be used alone or in combination of two or more. These red pigments may be milled in advance to improve contrast, adjust the average particle size, and so on. Milling can be carried out according to a standard method depending on the type of red pigment. Examples of such milling include solvent salt milling.

[0021] The derivative that can be used in the present invention is a base-type phthalimide derivative having a chemical structure represented by Chemical Formula 1. In Chemical Formula 1, examples of halogen atoms represented by R1 to R4 include chlorine atoms, bromine atoms, and iodine atoms. In Chemical Formula 1, C 1-6 The alkyl may be an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and the aliphatic hydrocarbon group may be linear, cyclic, or branched. The content of the derivative in the red pigment dispersion is 10 to 40 parts by weight, and more preferably 15 to 35 parts by weight, per 100 parts by weight of the total weight of the red pigment and the derivative.

[0022] Dispersants that can be used in the present invention are polymer dispersants having an acid value of 80 mgKOH / g or more and 120 mgKOH / g or less and having a carboxyl group as the acidic group. Various such dispersants are commercially available, including, but not limited to, Turplus (registered trademark) MD1100 (Otsuka Chemical Co., Ltd.), Turplus (registered trademark) MD1000 (Otsuka Chemical Co., Ltd.), and Disperbyk (registered trademark)-180 (BYK-Chemie). These dispersants may be used alone or in combination of two or more. Polymer dispersants having an acid value of 80 mgKOH / g or more and 100 mgKOH / g or less and an amine value of 0 mgKOH / g are more preferred for use in the present invention.

[0023] Here, the acid value refers to the acid value per 1 g of dispersant solid content, and can be determined by potentiometric titration in accordance with JIS K 0070 (1992) (unit: mgKOH / g). The amine value refers to the amine value per 1 g of dispersant solid content, and is determined by potentiometric titration using a 0.1 N hydrochloric acid aqueous solution, and then converted to the potassium hydroxide equivalent (unit: mgKOH / g).

[0024] In the red pigment dispersion of the present invention, the dispersant content (solid content or active ingredient) is preferably 30 to 50 parts by weight, and more preferably 33 to 45 parts by weight, per 100 parts by weight of the total solid content. Here, the "total weight of all solid content" in the red pigment dispersion of the present invention refers to the combined weight of the solid content or active ingredients of the red pigment, derivative, dispersant, and optional additives described below. From the viewpoint of dispersion stability, the ratio of (weight of solid content or active ingredient of dispersant) / (total weight of red pigment and derivative) is preferably 0.45 to 1.00, and more preferably 0.50 to 0.80. However, the optimal amount of dispersant to be added can be adjusted as appropriate, depending on the type of red pigment used and its combination.

[0025] The solvent that can be used in the present invention is not particularly limited, and examples thereof include various solvents such as aromatic, ketone, ester, glycol ether, alcohol, and aliphatic solvents. Among these, from the viewpoint of film-forming properties in color filter applications, solvents selected from aromatic, ketone, ester, and glycol ether solvents are preferred. The solvent may be used alone or in combination of two or more.

[0026] Examples of aromatic solvents include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene.

[0027] Examples of ketone solvents include methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, acetylacetone, isophorone, acetophenone, and cyclohexanone.

[0028] Examples of ester-based solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, isopropyl acetate, methyl propionate, 3-methoxybutyl acetate, ethyl glycol acetate, propylene glycol monomethyl ether acetate (PMA), propylene glycol monoethyl ether acetate, 3-methyl-3-methoxybutyl acetate, methyl monochloroacetate, ethyl monochloroacetate, butyl monochloroacetate, methyl acetoacetate, ethyl acetoacetate, butyl carbitol acetate, butyl lactate, ethyl 3-ethoxypropionate, ethylene glycol monobutyl ether acetate, ethylene glycol monomethyl ether acetate, propyl acetate, and 1,3-butylene glycol diacetate.

[0029] Examples of glycol ether solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, and diethylene glycol mono- water-soluble glycol ethers such as t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, and dipropylene glycol mono-n-butyl ether; Examples of the water-insoluble glycol ethers include ethylene glycol monohexyl ether, ethylene glycol-2-ethylhexyl ether, ethylene glycol phenyl ether, diethylene glycol-n-hexyl ether, diethylene glycol-2-ethylhexyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, dipropylene glycol propyl ether, and propylene glycol methyl ether propionate.

[0030] Examples of alcohol-based solvents include alkyl alcohols having 1 to 4 carbon atoms, such as ethanol, methanol, butanol, propanol, and isopropanol; Examples of the suitable glycol include ethylene glycol, propylene glycol, diethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, tripropylene glycol, polyethylene glycols with a molecular weight of 2000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, mesoerythritol, and pentaerythritol.

[0031] Examples of aliphatic solvents include aliphatic hydrocarbons such as n-pentane, n-hexane, and n-heptane.

[0032] The amount of solvent added can be adjusted so that the concentration of the total solids including the red pigment and the like is 15 to 50% by weight.

[0033] The red pigment dispersion of the present invention may contain other additives in addition to the above-mentioned components, as necessary, such as an antioxidant, an anti-aggregation agent, a surface conditioner (leveling agent), etc.

[0034] The red pigment dispersion of the present invention can be prepared, for example, by adding the above-mentioned components to a known dispersing machine such as a bead mill, a sand mill, a disperser, etc. The method of adding the components is not particularly limited, and the components may be mixed simultaneously and then subjected to a dispersion treatment. For example, when multiple types of pigments are used, dispersions may be prepared in advance for each pigment, and then the dispersions may be mixed and subjected to a dispersion treatment again.

[0035] As an example, the case of dispersion treatment using a sand mill will be described. First, a red pigment, a dispersant, and beads as a dispersion medium are charged into a sand mill. As beads, glass beads, zirconia beads, etc. with a particle diameter of 0.01 to 1 mm can be used. The amount of beads used is preferably 2 to 6 parts by weight per 1 part by weight of the red pigment dispersion. Then, the sand mill is operated to carry out the dispersion treatment. The dispersion treatment conditions are preferably approximately 1000 to 2000 rpm for 1 to 20 hours. After the dispersion treatment, the beads are removed by filtration or the like to obtain the red pigment dispersion.

[0036] The content of the red pigment in the red pigment dispersion of the present invention is preferably 0.01 to 30 parts by weight, more preferably 1 to 20 parts by weight, per 100 parts by weight of the red pigment dispersion.

[0037] <Study on derivatives and dispersants suitable for red pigment dispersion> To investigate the derivatives and dispersants suitable for red pigment dispersions, red pigment dispersions were produced using CI Pigment Red 122, with various combinations of derivatives and dispersants. CI Pigment Red 122 was micronized using the following process.

[0038] (Pigment Red 122 micronization process) 75 parts by weight of CI Pigment Red 122 (DIC Corporation, Fastogen® Super Magenta RG), 750 parts by weight of anhydrous sodium sulfate, 174 parts by weight of diethylene glycol, and 3.75 parts by weight of solid caustic soda (Tosoh Corporation, Toso Pearl®) were charged into a double-arm kneader (Inoue Seisakusho Co., Ltd., 5 L kneader) and kneaded for 6 hours while adjusting the temperature inside the kneader to 70°C. The kneaded mixture was transferred to a temperature-controllable tank containing 3,400 parts by weight of water and stirred at 70°C for 2 hours. The contents were filtered, washed with water, dried, and pulverized to obtain finely divided CI Pigment Red 122.

[0039] The derivatives used were derivative 1 represented by chemical formula 2, derivative 2 represented by chemical formula 3, derivative 3 represented by chemical formula 4, derivative 4 represented by chemical formula 5, and derivative 5 represented by chemical formula 6. The dispersants used were Turplus (registered trademark) MD1100 (Otsuka Chemical Co., Ltd. / acid value = 85 mg KOH / g, amine value = 0 mg KOH / g), Disperbyk (registered trademark)-111 (BYK-Chemie / acid value = 129 mg KOH / g, amine value = 0 mg KOH / g), Disperbyk (registered trademark)-140 (BYK-Chemie / acid value = 73 mg KOH / g, amine value = 76 mg KOH / g), Solsperse (registered trademark) 41000 (The Lubrizol Chemicals Japan Corporation / acid value = 50 mg KOH / g, amine value = 0 mg KOH / g), and HIPLAAD (registered trademark) ED-153 (Kusumoto Chemicals Co., Ltd. / acid value = 55 mg KOH / g, amine value = 0 mg KOH / g).

[0040] (Production of derivative 1) To 350 parts by weight of propylene glycol monomethyl ether, 42.9 parts by weight of tetrachlorophthalic anhydride and 16.1 parts by weight of benzylamine were added, and the mixture was reacted at 120°C for 6 hours. The mixture was then cooled to room temperature, filtered, washed with water, dried, and pulverized to obtain 52.8 parts by weight of N-benzyltetrachlorophthalimide. To 150 parts by weight of chlorosulfonic acid, 26.3 parts by weight of N-benzyltetrachlorophthalimide were added, and the mixture was reacted at 50°C for 3 hours. The reaction mixture was then poured into 1,250 parts by weight of cold water, filtered, and washed with water. The washed reaction mixture was dispersed in 580 parts by weight of water, and 27.4 parts by weight of diethylaminopropylamine was added. The mixture was reacted at 50°C for 30 minutes. The mixture was then filtered, washed with water, dried, and pulverized to obtain 34.2 parts by weight of Derivative 1 represented by Chemical Formula 2.

[0041] The chemical structure of the resulting pigment derivative was identified using an AXIMA Confidence® matrix-assisted laser desorption / ionization time-of-flight mass spectrometer (MALDI-TOF-MS, Shimadzu Corporation) in positive ion mode with α-cyano-4-hydroxycinnamic acid (CHCA) as the matrix. A molecular ion peak was observed at m / z 565. This value matched the monoisotopic mass corresponding to chemical formula 2 (n=1).

[0042] [ka]

[0043] (Production of derivative 2) To 900 parts by weight of chlorosulfonic acid, 205 parts by weight of CI Pigment Red 255 (BASF, Irgazin® Red L 3551 HD) and 252 parts by weight of thionyl chloride were added, and the mixture was allowed to react at 60°C for 5 hours. The reaction mixture was then poured into 25,000 parts by weight of cold water, filtered, and washed to obtain a chlorosulfonated product of CI Pigment Red 255. This product was dispersed in 6,000 parts by weight of water, and 296 parts by weight of diethylaminopropylamine was added. The mixture was allowed to react at 50°C for 30 minutes. The contents were then filtered, washed, dried, and pulverized to obtain 329 parts by weight of Derivative 2 (a mixture of n = 1 to 2) represented by Chemical Formula 3.

[0044] [ka]

[0045] (Production of derivative 3) 87 parts by weight of diethylaminopropylamine and 123 parts by weight of cyanuric chloride were added to 3,000 parts by weight of water and reacted at 20°C for 1 hour. Then, 35 parts by weight of sodium carbonate was added and stirred for 10 minutes to obtain reaction mixture a. 166 parts by weight of 4,4'-diaminodiphenyl sulfone (Seikacure S, Wakayama Seika Kogyo Co., Ltd.) and 140 parts by weight of 35% hydrochloric acid were added to 8,000 parts by weight of water and stirred to obtain reaction mixture b. After mixing reaction mixture a and reaction mixture b, the mixture was heated to 30°C and stirred for 30 minutes. Then, 87 parts by weight of diethylaminopropylamine was added, heated to 80°C, and stirred for 30 minutes to obtain reaction mixture c. After cooling reaction mixture c to below 5°C, 140 parts by weight of 35% hydrochloric acid was added, 60 parts by weight of sodium nitrite was added, and stirred for 30 minutes to obtain reaction mixture d. To 8,000 parts by weight of water, 260 parts by weight of 30% aqueous sodium hydroxide solution and 260 parts by weight of 5-acetoacetylaminobenzimidazolone (Samsung Chemical Co., Ltd., AABI) were added and stirred, followed by the addition of 140 parts by weight of sodium acetate, 17 parts by weight of dimethyllaurylamine, and 155 parts by weight of 80% acetic acid, yielding reaction mixture e. Reaction mixture d and reaction mixture e were mixed, heated to 25°C, and stirred for 30 minutes. The mixture was then heated to 80°C, 500 parts by weight of 30% aqueous sodium hydroxide solution was added, and stirred for 20 minutes. The reaction product was filtered, washed with water, dried, and pulverized to yield 400 parts by weight of derivative 3 represented by chemical formula 4.

[0046] [ka]

[0047] (Production of derivative 4) 195 parts by weight of diethylaminopropylamine and 234 parts by weight of 4-acetaminobenzenesulfonyl chloride were added to 5,000 parts by weight of cold water and stirred at 50°C for 30 minutes, then heated to 85°C. 350 parts by weight of 35% hydrochloric acid was then added and stirred for 3 hours to obtain reaction mixture a. 184 parts by weight of cyanuric chloride was added to the cooled reaction mixture a and stirred at 5°C for 1 hour to obtain reaction mixture b. 254 parts by weight of 4,4'-methylenedi-2,6-xylidine (Nippon Kayaku Co., Ltd., KAYABOND® C-200S) was added to 10,000 parts by weight of water and stirred to obtain reaction mixture c. Reaction mixture b and reaction mixture c were mixed, heated to 85°C, and stirred for 2 hours. The contents were filtered, washed with water, dried, and pulverized to obtain 567 parts by weight of derivative 4 represented by chemical formula 5.

[0048] [ka]

[0049] (Method for producing derivative 5) To 600 parts by weight of diethylene glycol dimethyl ether, 47.1 parts by weight of potassium t-butoxide, 68.1 parts by weight of CI Pigment Red 122 (BASF, Cinquasia® Pink K 4410), and 71.8 parts by weight of benzyl bromide were added, and the mixture was allowed to react at 80°C for 8 hours. The mixture was then cooled to below 40°C, and the contents were filtered, washed with water, dried, and pulverized to obtain 101 parts by weight of red powder a. To 192 parts by weight of chlorosulfonic acid, 52.1 parts by weight of red powder a was added, and the mixture was allowed to react at 40°C for 17 hours. The mixture was then poured into 2300 parts by weight of ice water, and the reaction mixture was filtered and washed with water. The washed product was dispersed in 1,100 parts by weight of water, and 39.1 parts by weight of diethylaminopropylamine was added and reacted at 50°C for 30 minutes. The content was then filtered, washed with water, dried and pulverized to obtain 75.1 parts by weight of Derivative 5 (a mixture of n = 1 to 2) represented by Chemical Formula 6.

[0050] [ka]

[0051] [Production of red pigment dispersion] (Dispersion No.1) A container was charged with 3.64 parts by weight of finely divided CI Pigment Red 122, 1.56 parts by weight of Derivative 1, 2.74 parts by weight of Disperbyk®-111 (solid content 95% by weight), and 32.06 parts by weight of PMA as a solvent. 160 parts by weight of 0.5 mm zirconia beads were added, and the mixture was dispersed for 60 minutes using a paint shaker. The 0.5 mm zirconia beads were then removed to obtain Dispersion No. 1.

[0052] (Dispersion No.2) Dispersion No. 2 was prepared in the same manner as Dispersion No. 1, except that 5.10 parts by weight of Disperbyk®-140 (solid content 51% by weight) and 29.70 parts by weight of PMA were used as dispersants.

[0053] (Dispersion No.3) Dispersion No. 3 was prepared in the same manner as Dispersion No. 1, except that 2.60 parts by weight of Solsperse (registered trademark) 41000 (solid content 100% by weight) and 32.20 parts by weight of PMA were used as dispersants.

[0054] (Dispersion No.4) Dispersion No. 4 was prepared in the same manner as Dispersion No. 1, except that 5.30 parts by weight of HIPLAAD® ED-153 (solids content 49.1 wt %) and 29.50 parts by weight of PMA were used as dispersants.

[0055] (Dispersion No.5) Dispersion No. 5 was prepared in the same manner as Dispersion No. 1, except that 6.34 parts by weight of Terplus (registered trademark) MD1100 (solid content 41% by weight) and 28.46 parts by weight of PMA were used as dispersants.

[0056] (Dispersion No.6) Dispersion No. 6 was prepared in the same manner as Dispersion No. 5, except that 8.24 parts by weight of Terplus® MD1100 and 26.56 parts by weight of PMA were used.

[0057] (Dispersion No.7) Dispersion No. 7 was prepared in the same manner as Dispersion No. 5, except that 10.15 parts by weight of Turplus® MD1100 and 24.65 parts by weight of PMA were used.

[0058] (Dispersion No.8) Dispersion No. 8 was prepared in the same manner as Dispersion No. 5, except that 4.16 parts by weight of finely divided CI Pigment Red 122 and 1.04 parts by weight of Derivative 1 were used as the derivative.

[0059] (Dispersion No.9) Dispersion No. 9 was prepared in the same manner as Dispersion No. 8, except that 8.24 parts by weight of Terplus (registered trademark) MD1100 (solid content 41% by weight) and 26.56 parts by weight of PMA were used.

[0060] (Dispersion No.10) Dispersion No. 10 was prepared in the same manner as Dispersion No. 5, except that 1.56 parts by weight of Derivative 2 was used as the derivative.

[0061] (Dispersion No.11) Dispersion No. 11 was prepared in the same manner as Dispersion No. 5, except that 1.56 parts by weight of Derivative 3 was used as the derivative.

[0062] (Dispersion No.12) Dispersion No. 12 was prepared in the same manner as Dispersion No. 5, except that 1.56 parts by weight of Derivative 4 was used as the derivative.

[0063] (Dispersion No.13) Dispersion No. 13 was prepared in the same manner as Dispersion No. 5, except that 1.56 parts by weight of Derivative 5 was used as the derivative.

[0064] [Viscosity measurement] The viscosity of the dispersions No. 1 to No. 13 (red pigment dispersions) was measured immediately after preparation and after three days of storage in a thermostatic chamber at 45°C. The viscosity was measured using an E-type viscometer (Toki Sangyo Co., Ltd., TVE-25L) after adjusting the dispersion to 25°C.

[0065] Table 1 shows the red pigment, derivative, and amount of derivative added (weight (wt%) of the derivative relative to the total weight of the red pigment and derivative), D / P ratio (ratio of the solid weight of the dispersant to the total weight of the red pigment and derivative), viscosity (initial viscosity, viscosity after 3 days of storage at 45°C, viscosity change rate after 3 days of storage), and practicality evaluation regarding viscosity stability for dispersions No. 1 to No. 13. Here, viscosity change rate means "viscosity after 3 days of storage / initial viscosity." Furthermore, the practicality evaluation regarding viscosity stability was given a "good" if the initial viscosity was 20 mPa·s or less and the viscosity change rate after 3 days of storage at 45°C was within the range of 0.80 to 1.20, and an "unsatisfactory" if not.

[0066] [Table 1]

[0067] Dispersions No. 1 to No. 4 gelled during preparation, so a 45°C storage test was not performed. Dispersions No. 5 to No. 9 and No. 13 had initial viscosities of 6.08 to 10.23 mPa·s, which is considered suitable, and were also rated as "Good" for their viscosity change rate after 3 days of storage at 45°C. Dispersions No. 10 and No. 11 were rated as "Poor" because their viscosity change rate after 3 days of storage at 45°C exceeded 1.20. Dispersion No. 12 had an initial viscosity of more than 20 mPa·s and gelled after 3 days of storage at 45°C, so it was rated as "Poor."

[0068] Thus, it was confirmed that when CI Pigment Red 122 was used as the red pigment, Derivative 1 or Derivative 5 was used as the derivative, and Turplus (registered trademark) MD1100 was used as the dispersant, there was little change in viscosity during the storage test.

[0069] [Measurement of viscosity, particle size and number of coarse particles] Next, for red pigment dispersions in which the derivative content was 30 wt%, the dispersant was Turplus (registered trademark) MD1100, the D / P ratio was fixed at 0.50, and the type of red pigment and derivative was varied, the viscosity and cumulant average particle size (nm) immediately after preparation, the viscosity after 3 days of storage at 45°C, and the number of coarse particles after 1 day of storage at 25°C were measured. The cumulant average particle size was measured by diluting the red pigment dispersion approximately 1000 times with PMA and using a particle size distribution analyzer (Otsuka Electronics Co., Ltd., nano SAQLA (registered trademark)). The number of coarse particles was measured using the following method.

[0070] The dispersion was diluted with PMA to a weight ratio of 1:1. The diluted solution was applied to a 100 mm square glass plate with a thickness of 1 mm using a spin coater (MS-150A, Mikasa Co., Ltd.), adjusting the rotation speed to achieve a film thickness of 0.4 ± 0.2 μm. The coated plate was dried in an air bath at 90°C for 2.5 minutes. The dried plate was observed at 500x magnification using an MX63 (Olympus Industrial Microscope) and photographed in reflection mode in five fields of view using WinRoof 2015 (Mitani Corporation, image analysis and measurement software). The photographs were processed using image processing software (Fiji) to determine the total number of coarse particles in the five fields of view. Fiji is a version of ImageJ, an image processing software provided by the National Institutes of Health (NIH).

[0071] (Dispersion No.14) A container was charged with 7.00 parts by weight of finely divided CI Pigment Red 122, 3.00 parts by weight of Derivative 1, 12.20 parts by weight of Turplus (registered trademark) MD1100 (solids content 41 wt%), and 17.80 parts by weight of PMA as a solvent. 160 parts by weight of φ0.8 mm zirconia beads were added, and the mixture was dispersed for 30 minutes using a paint shaker. This dispersion was then diluted with 10.00 parts by weight of PMA. 40.0 parts by weight of the dispersion from which the φ0.8 mm zirconia beads had been removed were placed in a separate container together with 160 parts by weight of φ0.1 mm zirconia beads, and the mixture was dispersed for 30 minutes using a paint shaker. 21.53 parts by weight of PMA was added for dilution, and the φ0.1 mm zirconia beads were removed to obtain Dispersion No. 14.

[0072] (Dispersion No.15) Dispersion No. 15 was prepared in the same manner as Dispersion No. 14, except that 3.00 parts by weight of Derivative 2 was used as the derivative.

[0073] (Dispersion No.16) Dispersion No. 16 was prepared in the same manner as Dispersion No. 14, except that 3.00 parts by weight of Derivative 5 was used as the derivative.

[0074] (Dispersion No.17) Dispersion No. 17 was prepared in the same manner as Dispersion No. 14, except that 7.00 parts by weight of CI Pigment Red 177 (CINIC, SR3C-CF) was used as the red pigment.

[0075] (Dispersion No.18) Dispersion No. 18 was prepared in the same manner as Dispersion No. 17, except that 3.00 parts by weight of Derivative 2 was used as the derivative.

[0076] (Dispersion No.19) Dispersion No. 19 was prepared in the same manner as Dispersion No. 14, except that 7.00 parts by weight of CI Pigment Red 254, which had been micronized by the following method, was used as the red pigment.

[0077] (Miniaturization of CI Pigment Red 254) 300 parts by weight of CI Pigment Red 254 (BASF, Irgazin® Red L 3630), 3,000 parts by weight of anhydrous sodium sulfate, and 805 parts by weight of diethylene glycol were charged into a twin-arm kneader (Inoue Seisakusho, 5L kneader) and kneaded for 6 hours while adjusting the temperature inside the kneader to 50°C. The kneaded mixture was transferred to a temperature-controllable tank containing 12,000 parts by weight of water and stirred at 60°C for 30 minutes. After that, the pH was adjusted to 2.3-2.5 with 35% hydrochloric acid and the mixture was dispersed for 1 hour. The contents were filtered, washed with water, dried, and pulverized to obtain finely divided CI Pigment Red 254.

[0078] (Dispersion No.20) Dispersion No. 20 was prepared in the same manner as Dispersion No. 19, except that 3.00 parts by weight of Derivative 2 was used as the derivative.

[0079] Table 2 shows the viscosity, viscosity change rate, cumulant average particle size (nm), number of coarse particles (number), and practicality evaluation for viscosity stability / number of coarse particles for dispersions No. 14 to No. 20. The practicality evaluation for viscosity stability / number of coarse particles was evaluated as "Good" if the viscosity change rate after 3 days of storage at 45°C was within the range of 0.80 to 1.20 and the number of coarse particles was less than 500, and evaluated as "Poor" if not. When a color filter is produced using a red pigment dispersion with a large number of coarse particles, problems such as reduced resolution or uneven color are likely to occur.

[0080] [Table 2]

[0081] As can be seen from Table 2, the red pigment dispersion containing three types of red pigments and Turplus (registered trademark) MD1100 as a dispersant at a D / P ratio of 0.50 was judged to be "Good" for practical use in terms of viscosity stability / number of coarse particles only when Derivative 1 was used as the derivative.

[0082] Turplus (registered trademark) MD1100 has an acid value of 85 mgKOH / g, an amine value of 0 mgKOH / g, and has a carboxyl group as the acidic group. Taking into account the results in Table 1, it was considered that a polymer dispersant having an acid value of 80 mgKOH / g or more and 120 mgKOH / g or less and having a carboxyl group as the acidic group is suitable as a dispersant for use in the red pigment dispersion of the present invention.

[0083] Regarding the derivatives, only the red pigment dispersion using Derivative 1 was judged to be practical in terms of viscosity stability and the number of coarse particles. It was confirmed that the dispersants that were judged to be "good" for practicality did not affect the practicality judgment as long as the D / P ratio was within the range of 0.45 or more and 1.0 or less, more preferably 0.5 or more and 0.8 or less. [Industrial Applicability]

[0084] The red pigment dispersion of the present invention is useful in the manufacture of color filters such as those used in displays or image sensors.

Claims

1. A red pigment dispersion containing at least a red pigment, a derivative, a dispersant, and a solvent, The red pigment is CIPigment Red 122, CIPigment Red 202, CIPigment Red 209; CIPigment Red 83, CIPigment Red 89, CIPigment Red 123, CIPigment Red 149, CIPigment Red 168, CIPigment Red 177, CIPigment Red 178, CIPigment Red 179, CIPigment Red 190, CIPigment Red194, CIPigment Red 216, CIPigment Red 224, CIPigment Red 226, CIPigment Red 263; CIPigment Red 254, CIPigment Red 255, CIPigment Red 264, CIPigment Red 270, CIPigment Red 272, CIPigment Red 291; One or more selected from The derivative has a chemical structure represented by Chemical Formula 1: the dispersant is a polymer dispersant having an acid value of 80 mgKOH / g or more and 120 mgKOH / g or less and having a carboxyl group, The derivative is contained in an amount of 10 parts by weight or more and 40 parts by weight or less per 100 parts by weight of the total weight of the red pigment and the derivative, The dispersant is contained in an amount of 30 parts by weight or more and 50 parts by weight or less relative to 100 parts by weight of the total weight of all solids. Red pigment dispersion; 【Chemistry 1】 (In chemical formula 1, R １ ~R ４ each independently represents a hydrogen atom or a halogen atom, n represents an integer of 1 to 5; X １ and X ２ are each independently a hydrogen atom, C １－６ Alkyl, benzyl, phenyl or C １－６ Alkyl-NR ５ R ６ (R ５ and R ６ are the same or different and represent a hydrogen atom, a phenyl or a C １－６ represents alkyl. １ and X ２ At least one of １－６ Alkyl-NR ５ R ６ It is a group represented by the following formula:

2. The dispersant has an amine value of 0 mg KOH / g. The red pigment dispersion according to claim 1 .

3. 3. The red pigment dispersion according to claim 1, which is a pigment dispersion for a color filter used in a display device or an image sensor.

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