KR101617444B1 - Pigment dispersion aid, pigment dispersion and pigment-based resist composition for color filter - Google Patents

Abstract

assignment

Provided is a pigment dispersion auxiliary agent which can be produced efficiently by using concentrated sulfuric acid or fuming sulfuric acid and also exhibits excellent pigment dispersibility by being used in combination with a pigment dispersant.

Solution

A pigment dispersion auxiliary agent characterized by being a compound represented by the following general formula (1).

[Chemical Formula 1]

Wherein M is H, Na, K, NH ₄ or NR ¹ R ² R ³ R ^{4 wherein} R ¹ , R ² , R ³ and R ⁴ are the same or different, A saturated or unsaturated aliphatic hydrocarbon group of 1 to 10 carbon atoms or an aromatic hydrocarbon group of 6 to 10 carbon atoms which may be substituted with another substituent). and m represents an integer of 1 or more.

Description

TECHNICAL FIELD [0001] The present invention relates to a pigment dispersion assistant, a pigment dispersion auxiliary, a pigment dispersion, and a pigment dispersion resist composition for a color filter. BACKGROUND ART [0002] Pigment dispersing aids,

The present invention relates to a pigment dispersion auxiliary agent and a use thereof and, more particularly, to a pigment dispersion auxiliary agent for a printing ink, a coating material, a liquid crystal color filter, , A resist for a liquid crystal color filter or a resist composition for a liquid crystal color filter), a pigment dispersion suitable for a wide field such as an ink for ink jet, and particularly when used in a resist for a liquid crystal color filter, A pigment dispersing aid capable of raising the brightness or contrast ratio to a higher level, and a use thereof.

Organic pigments have been known as colorants for a long time and they are being used not only in various inks and paints but also in fields such as liquid crystal color filters and inkjet inks where high transparency and high contrast ratio are required. The dispersion technique of these organic pigments has made remarkable progress in recent years, and a method of dispersing the pigments at as high a concentration as possible for rationalization of production has also been studied. However, basically, when the concentration of the pigment is increased, there is a problem that the fluidity and dispersion stability are lowered.

In addition, in the field of liquid crystal color filters and inkjet recording, it is necessary to use high-quality dyed pigments because of their high fastness, and to disperse the dyed high-quality organic pigments to finer particle diameters need. However, it is difficult to obtain a stable dispersion product because the original high-grade organic pigment has poor dispersion stability as compared with other pigments, and as it becomes finer, it agglomerates easily.

In order to solve such a problem, dispersion stability of an organic pigment has been examined by development of a pigment dispersant and a surfactant which have conventionally been subjected to treatment (surface treatment and modification) of the pigment itself, and wettability (adsorption property) to the pigment , And many researches are still being carried out.

For example, a method has been disclosed in which a pigment dispersant having a basic group is used for dispersing an acidic pigment, and a pigment dispersant is adsorbed on the surface of the pigment by the affinity of an acid-base to obtain good dispersion stability (see, for example, 1 and 2). However, improvement of the pigment dispersion by the affinity of such an acid-base is not yet sufficient to realize the additional high transmittance and contrast required in the fields of liquid crystal color filters and inkjet printing.

In addition, from the viewpoint of obtaining a color or lightness suitable for a liquid crystal color filter, the use of a diketopyrrolopyrrole pigment as a red pigment among the above-mentioned high-grade pigments makes it possible to obtain 4,4'-diamino -1,1'-biantraquinone-based pigment is obtained. This is based on the fact that the spectral transmittance curve of diketopyrrolopyrrole exhibits a large increase in tilt near 550 to 600 nm, and it is particularly preferable to use the atomized product so that the effect of improving the brightness Y value becomes remarkable. However, the diketopyrrolopyrrole-based pigment exhibits extremely strong cohesive force from the highly symmetrical molecular structure, so that it is impossible to atomize it by a conventional dispersion technique.

Therefore, it is also considered to use a pigment dispersion auxiliary agent which improves the pigment dispersibility by being used in combination with the pigment dispersant. For example, there is disclosed a method of improving the dispersibility of diketopyrrolopyrrole pigment by using a pigment dispersion auxiliary containing a pigment dispersant and a diketopyrrolopyrrole compound having a sulfo group (see, for example, Patent Document 3 Reference). The use of such a pigment dispersion auxiliary improves the pigment dispersibility, so that the above constitution is considered as one means for achieving the high transmittance and contrast required in the liquid crystal color filter field.

Here, in order to obtain a diketopyrrolopyrrole compound having a sulfo group as specifically described in Patent Document 3, it is necessary to apply a concentrated sulfuric acid or fuming sulfuric acid to the diketopyrrolopyrrole pigment to perform sulfonation . However, since concentrated sulfuric acid or fuming sulfuric acid has strong oxidizing action, the diketopyrrolopyrrole-based pigment may be decomposed during this process. In this case, not only the yield of the desired diketopyrrolopyrrole compound is lowered but also the impurities generated by the decomposition are mixed in a large amount, whereby the crystallinity is deteriorated and the separation operation becomes difficult and the cost is greatly increased . Sulphonation using a more moderate drug will reduce the likelihood of such harm, but in that case it will take a lot of time for the sulfonation reaction and it is realistic to use expensive chemicals instead of inexpensive concentrated sulfuric acid or fuming sulfuric acid. not.

Patent Document 1: JP-A-54-037082

Patent Document 2: JP-A-2001-272524

Patent Document 3: JP-A-2000-160084

Therefore, the first object of the present invention is to obtain a pigment dispersion auxiliary agent which can be efficiently produced using concentrated sulfuric acid or fuming sulfuric acid, and which is used in combination with a pigment dispersant to exhibit excellent pigment dispersibility and dispersion stability. Secondly, it is an object to obtain a pigment dispersion excellent in pigment dispersibility and dispersion stability by using such a pigment dispersion auxiliary agent. Thirdly, it is an object to obtain a pigment-dispersed resist composition for a color filter which exhibits a high brightness Y value or a contrast value by using such a pigment dispersion. Other problems of the present invention will become clear from the later description of the present specification.

As a result of intensive studies, the present inventors have found that among the diketopyrrolopyrrole pigments, in particular, C.I. It has been found that the pigment dispersion auxiliary obtained by sulfonating Pigment Orange 71 can be obtained with satisfactory crystallinity at a good yield even when it is produced using concentrated sulfuric acid or fuming sulfuric acid. The present invention has been completed on the basis of such knowledge, and the above problems can be solved.

(1) The present invention relates to a pigment dispersion auxiliary agent characterized by being a compound represented by the following general formula (1).

[Chemical Formula 1]

Wherein M is H, Na, K, NH ₄ or NR ¹ R ² R ³ R ^{4 wherein} R ¹ , R ² , R ³ and R ⁴ are the same or different, A saturated or unsaturated aliphatic hydrocarbon group of 1 to 10 carbon atoms or an aromatic hydrocarbon group of 6 to 10 carbon atoms which may be substituted with another substituent). and m represents an integer of 1 or more.

(2) The present invention relates to a pigment dispersion characterized by containing an organic pigment, a pigment dispersant, the pigment dispersion auxiliary agent described in the above (1), and an organic solvent.

(3) The present invention relates to the pigment dispersion described in (2) above, wherein the pigment dispersant has a basic group.

(4) The present invention relates to the pigment dispersion described in (2) or (3), wherein the pigment dispersant is an acrylic block copolymer having a basic group.

(5) The present invention relates to the pigment dispersion according to any one of (2) to (4), wherein the organic pigment is a diketopyrrolopyrrole pigment.

(6) In the invention, it is preferable that the diketopyrrolopyrrole pigment is C.I. Pigment Red 254. < / RTI >

(7) The present invention relates to the pigment dispersion described in any one of (2) to (6) above, wherein the organic pigment is subjected to a microparticulation treatment.

(8) The present invention relates to the pigment dispersion according to the above item (7), wherein the microparticulation treatment is a salt milling treatment.

(9) The present invention is characterized in that the salt milling treatment is carried out in such a manner that the mixture containing the organic pigment, the water-soluble inorganic salt and the water-soluble dispersion medium which does not substantially dissolve the inorganic salt is rotated by three revolving blades, (8), which is carried out by a step of kneading the kneaded mixture with a kneading apparatus to remove the inorganic salt and the water-soluble dispersion medium.

(10) The present invention also relates to a pigment-dispersed resist composition for a color filter, which comprises the pigment dispersion according to any one of (2) to (9).

First, the pigment dispersion auxiliary agent of the present invention will be described in detail.

The pigment dispersion auxiliary agent of the present invention is a compound represented by the above general formula (1). In the formula, M represents H, Na, K, NH ₄ or NR ¹ R ² R ³ R ⁴ .

R ¹ , R ² , R ³ and R ^{4, which} may be the same or different, each represent an alkyl group having 1 to 20 carbon atoms which may be substituted with another substituent, with respect to "NR ¹ R ² R ³ R ⁴ " (M) A saturated or unsaturated aliphatic hydrocarbon group of 10 to 10 carbon atoms, or an aromatic hydrocarbon group of 6 to 10 carbon atoms which may be substituted with another substituent. Examples of the saturated or unsaturated aliphatic hydrocarbon group include a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, An alkyl group such as acyl group; Alkenyl groups such as a vinyl group, an allyl group and a 1-butenyl group; And alkynyl groups such as an ethynyl group and a propynyl group. Examples of the aromatic hydrocarbon group include a phenyl group and a naphthyl group. Examples of the other substituent include a hydroxyl group, a halogen, a carboxyl group, an amino group, and a lower alkyl group (having 1 to 5 carbon atoms).

In addition, ^{one of} R ¹ , R ² , R ³ and R ⁴ may be substituted with another substituent, or two or more substituents may be substituted with another substituent. Further, "m" in the general formula (1) is an integer of 1 or more.

Such a pigment dispersion auxiliary may be a pigment dispersion aid represented by the following formula (2): C.I. Pigment Orange 71 can be prepared by conducting conventionally known sulfonation treatment. For example, C.I. The pigment powder of Pigment Orange 71 is dissolved in concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid or a mixture thereof, heated from room temperature to 80 to 90 占 폚, and then diluted with a large amount of water. At this time, the sulfonated Pigment Orange 71 crystallizes and becomes a suspended state. The obtained suspension is filtered, washed with water, and then the filter cake is dried and pulverized to obtain a desired pigment dispersion auxiliary. The sulfonate obtained by the reaction may be neutralized with an inorganic basic compound such as sodium hydroxide or an aqueous ammonia solution or an organic basic compound such as an organic amine to give a sodium salt, a potassium salt, an ammonium salt or an organic ammonium salt Needless to say.

Further, there is no commercial product of such a pigment dispersion auxiliary agent.

(2)

C.I. Pigment Orange 71 can be any known one. As the amount of the drug used for sulfonation, for example, when concentrated sulfuric acid is used, an amount sufficient to stir the pigment and concentrated sulfuric acid in a slurry form is used.

As shown in the above formula (2), C.I. Pigment Orange 71 has a structure in which two 3-cyanophenyl groups are bonded to the diketopyrrolopyrrole skeleton. For example, when the substituent bonded to the diketopyrrolopyrrole skeleton is a phenyl group (the following formula (3)) or a tolyl group (the following formula (4)) or the like, The pigment dispersion auxiliary agent can not be satisfactorily obtained.

Further, for example, when C.I. carbon atoms in which a hydrogen atom is bonded to the diketopyrrolopyrrole skeleton, In the case of Pigment Red 264 (the following formula (5)), the sulfonation is terminated without decomposition, but the crystallinity is extremely poor. This is thought to be due to the generation of a plurality of chemical species. Because of this poor crystallinity, it is difficult to separate the product from the filtrate or wash it with water. In short, since the water can not be sufficiently washed, the sulfuric acid remains in the obtained pigment dispersion auxiliary agent, and when used, for example, in a resist for a liquid crystal color filter, there arises a problem that the contrast ratio is lowered.

(3)

CI. Wherein two 3-cyanophenyl groups are bonded to the diketopyrrolopyrrole skeleton. In the case of Pigment Orange 71 (in the case of the present invention), the problem of decomposition and crystallinity can be solved in particular, and by using this in a resist for a liquid crystal color filter, a color filter for liquid crystal having good contrast ratio and brightness Y value can be obtained .

Next, a pigment dispersion containing an organic pigment, a pigment dispersant, the pigment dispersing aid, and an organic solvent will be described.

The amount of the pigment dispersion auxiliary agent constituting the pigment dispersion of the present invention is usually 0.1 to 100 mass%, preferably 5 to 50 mass%, based on the organic pigment (100 mass%). Even if the amount of the pigment dispersion auxiliary used exceeds the above range, the pigment dispersion effect tends not to be further improved.

As organic pigments constituting the pigment dispersion of the present invention, conventionally used are printing inks, paints, resists for liquid crystal color filters, dianthraquinonyl pigments, diketopyrrolopyrrole pigments, condensed azo pigments, , Isoindoline pigments, perinone pigments, perylene pigments, azo pigments having heterocyclic rings, benzimidazolone pigments, anthraquinone pigments, quinacridone pigments and dibromoanthanthrone pigments At least one kind of red pigment, yellow pigment, orange color pigment and purple pigment can be used. As a specific example, when represented by the generic name of the color index, the red pigment includes C.I. Pigment Red 9, 19, 38, 43, 48, 49, 52, 53, 57, 88, 97, 122, 123, 144, 146, 149, 155, 166, 168, 177, 178, 179, 180, 185 , 188, 190, 202, 206, 207, 208, 209, 216, 217, 220, 221, 224, 226, 238, 242, 254, 255, Examples of the yellow pigment include Pigment Yellow 138, 139, 150 and the like; The orange color pigment includes C.I. Pigment Orange 38, 43, 71 and the like; As the violet pigment, C.I. Pigment Violet 23 and the like.

Of these, diketopyrrolopyrrole-based pigments are preferable from the viewpoint of obtaining a good color for a resist for a liquid crystal color filter. In particular, among diketopyrrolopyrrole pigments, a high brightness Y value is obtained, From the viewpoint that the CI Pigment Red 254 is particularly preferred.

In the present invention, the blending amount of the organic pigment is preferably 1 to 40% by mass in the pigment dispersion (100% by mass).

In order to increase the saturation of the ink jet printing and the brightness Y value and the contrast ratio of the liquid crystal color filter, it is preferable that the organic pigment is finely particulated. In addition, it is preferable to use a kneading apparatus or the like for revolving the kneader and rotating the three stirring blades, respectively, and subjecting the organic pigment to an inorganic salt and subjecting the organic pigment to a salt milling treatment so that the primary particle diameter of the organic pigment becomes finer desirable. Among them, it is preferable to use an organic pigment obtained by performing a salt milling process using a kneading apparatus which performs revolving motion while rotating three stirring blades. In this case, the salt milling treatment can be performed so that the primary particle diameter of the pigment becomes finer and uniform. The salt milling process using a kneading apparatus in which the three stirring blades are revolved while rotating each other is also referred to as a tri-mix process.

The tri-mix process is a process described in International Publication WO06 / 098261.

Specifically, the above-mentioned trimmix treatment is carried out in the presence of an organic pigment, a water-soluble inorganic salt (preferably an average particle diameter of 50 탆 or less such as sodium chloride) and an aqueous dispersion medium (alkoxy alcohols , Glycols, ethers, and the like) is kneaded by a kneading apparatus that performs revolving motion while rotating three stirring blades, and then the inorganic salt and the water-soluble dispersion medium are removed. In addition, when preparing the pigment dispersion of the present invention, a pigment dispersing agent, a pigment dispersion auxiliary agent and an organic solvent may be added to the organic pigment previously subjected to the tri-mixed treatment, and the tri-mixed treatment may be performed It may be performed.

As the pigment dispersing agent constituting the pigment dispersion of the present invention, for example, those having a basic group can be preferably used. By using such a pigment dispersant and the pigment dispersing aid in combination, the pigment dispersibility, dispersion stability, and fluidity can be greatly enhanced. In addition, when a pigment dispersion having such characteristics is used in a resist composition, high brightness and contrast can be exhibited.

As the pigment dispersant having a basic group, a basic polymer pigment dispersant conventionally used in printing inks, paints, resists for liquid crystal color filters, inks for inkjet printing, and the like can be used. The pigment dispersant is appropriately selected depending on the kind of the organic pigment to be used and the kind of the organic solvent to be described later.

(1) a polyester having a carboxyl group liberated with an amino group and / or an imino group of a polyamine compound (for example, polyallylamine, polyvinylamine, poly (lower alkyleneamine) such as polyethylene polyimine) And a polyester amide (JP-A-2001-59906), at least one reaction product selected from the group consisting of

(2) a carbodiimide compound having at least one side chain selected from the group consisting of a polyester side chain, a polyether side chain and a polyacrylic side chain and at least one basic nitrogen-containing group in the molecule / 000950),

(3) a reaction product of a low molecular weight amino compound such as poly (lower) alkyleneimine or methyliminobispropylamine and a polyester having a liberated carboxyl group (JP-A-54-37082, JP-A- -311177),

(4) A method for producing a polyisocyanate compound, which comprises adding to the isocyanate group of a polyisocyanate compound a polyester having one hydroxyl group such as an alcohol such as methoxypolyethylene glycol or caprolactone polyester, a compound having two or three isocyanate group- A reaction product obtained by sequentially reacting an aliphatic or heterocyclic hydrocarbon compound having a tertiary amino group (JP-A No. 02-612), a reaction product

(5) a reaction product in which a polyisocyanate compound and a hydrocarbon compound having an amino group are reacted with a polymer of an acrylate having an alcoholic hydroxyl group,

(6) a reaction product obtained by adding a polyether chain to a low molecular weight amino compound,

(7) a reaction product obtained by reacting a compound having an isocyanate group with a compound having an amino group (JP-A-04-210220),

(8) a reaction product obtained by reacting a linear polymer having a carboxyl group liberated in a polyepoxy compound and an organic amine compound having one secondary amino group (JP-A-09-87537)

(9) a reaction product of a polycarbonate compound having a functional group capable of reacting with an amino group and a polyamine compound at one end (JP-A-09-194585)

(10) A photopolymerizable composition comprising at least one compound selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, stearyl methacrylate, benzyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, Methacrylic acid esters such as stearyl acrylate and benzyl acrylate, and acrylic esters, and at least one member selected from the group consisting of acrylamide, methacrylamide, N-methylolamide, vinylimidazole, vinylpyridine, A copolymer of at least one of basic group-containing polymerizable monomers such as a monomer having a lactone skeleton and at least one of styrene, styrene derivatives and other polymerizable monomers (JP-A-01-164429)

(11) an acrylic block copolymer comprising a block having a basic group such as a tertiary amino group or a quaternary ammonium salt group and a block having no basic functional group, and the like (the description of the acrylic block copolymer described in JP-A-2005-55814 ),

(12) Pigment dispersants obtained by Michael addition reaction of a polycarbonate compound with polyallylamine (JP-A-09-194585),

(13) carbodiimide compounds each having at least one polybutadiene chain and a basic nitrogen-containing group (JP-A-2006-257243),

(14) carbodiimide compounds each having at least one side chain having an amide group in the molecule and at least one basic nitrogen-containing group (JP-A-2006-176657),

(15) A polyurethane-based compound having a structural unit having an ethylene oxide chain and a propylene oxide chain and having an amino group quaternized by a quaternizing agent (Japanese Patent Application No. 2008-16404).

(16) A compound obtained by reacting an isocyanate group of an isocyanate compound having an isocyanurate ring in a molecule with an active hydrogen of a compound having an active hydrogen and a carbazole ring in the molecule, wherein an isocyanurate ring Or a compound having a number of carbazole rings of 15 to 85% based on the total of three numbers of urethane bonds and urea bonds produced by the reaction between an isocyanate group and an active hydrogen group Application No. 2008-253235)

In the pigment dispersion of the present invention, the amount of the pigment dispersant to be used is usually 1 to 200 parts by mass, preferably 1 to 60 parts by mass, based on 100 parts by mass of the total organic pigments to be used. If the amount of the pigment dispersant is less than 1 part by mass, the pigment dispersibility may be lowered, which is not preferable. On the other hand, if it exceeds 200 parts by mass, there is a possibility that the developability is lowered, which is not preferable.

Examples of the organic solvent constituting the pigment dispersion of the present invention include organic solvents preferably used in the fields of ink, paint, liquid crystal color filter resist, and ink jet. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene Ether organic solvents such as glycol monoethyl ether, propylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol methyl ethyl ether; Ether ester type organic solvents such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate; Ketone-based organic solvents such as methyl isobutyl ketone, cyclohexanone, 2-heptanone, and? -Butyrolactone; Methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl 3-methoxybutyl propionate, methyl 3-methoxypropionate, 3-methoxypropionic acid Ester organic solvents such as ethyl, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, and n-amyl formate; Alcohol solvents such as methanol, ethanol, isopropyl alcohol and butanol; Nitrogen-containing organic solvents such as N-methylpyrrolidone, N, N-dimethylformamide and N, N-dimethylacetamide. These may be used alone or in combination of two or more.

The organic solvent is appropriately selected depending on the use of the pigment dispersion, desired physical properties, and the like.

To prepare the pigment dispersion of the present invention with the above-mentioned constituent materials, conventionally known production methods can be used. For example, the pigment dispersion can be produced by the following production method.

First, an organic pigment, a pigment dispersion auxiliary agent represented by the general formula (1), a pigment dispersant and an organic solvent are obtained. The obtained mixture is kneaded using various kinds of dispersing machines such as a roll mill, a kneader, a high-speed stirring device, a bead mill, a ball mill, a sand mill, an ultrasonic dispersing machine and a high pressure dispersing machine and dispersed to obtain a pigment dispersion.

In addition, a binder resin (alkali-soluble resin, photopolymerizable compound, etc.) may be previously contained in the pigment dispersion of the present invention.

The pigment dispersion thus obtained may contain various kinds of binder resins, surfactants and various other additives as necessary, and may be used as printing inks, paints, resists for liquid crystal color filters, ink jet inks, ink for writing utensils, It is preferably used for a developer or the like.

Next, the pigment dispersion resist composition for a color filter, which is an example of a preferable use of the pigment dispersion of the present invention, will be described in more detail.

The pigment-dispersed resist composition for color filter has an active energy ray curable property and is an alkali developable resist composition. In addition to the pigment dispersion, an alkali-soluble resin, a photopolymerizable compound, a photopolymerization initiator, Various additives such as a silane coupling agent, a titanate coupling agent, an ultraviolet absorber, and an antioxidant for improving the adhesion to the substrate are suitably contained.

The amount of the organic pigment constituting the pigment-dispersed resist composition for a color filter of the present invention is preferably 5 to 80 mass%, more preferably 5 to 80 mass%, as a total amount of the organic pigment to be used, as a mass fraction to the total solid content of the pigment- , And more preferably 20 to 50 mass%.

In the pigment dispersion resist composition for a color filter, the amount of the pigment dispersant to be used is usually 1 to 100 parts by mass, preferably 1 to 50 parts by mass, per 100 parts by mass of the organic pigment. If the amount is less than 1 part by mass, the pigment dispersibility may be lowered. On the other hand, if it exceeds 100 parts by mass, there is a fear that the developability is lowered.

In the pigment dispersion resist composition for a color filter, the amount of the pigment dispersion auxiliary to be used is usually 0.1 to 100 mass%, preferably 5 to 50 mass%, based on the colored pigment. Even if it exceeds 100% by mass, the pigment dispersion effect tends not to be further improved.

The alkali-soluble resin constituting the pigment-dispersed resist composition for a color filter of the present invention is not particularly limited as long as it is soluble in a developing solution used in the developing process, particularly preferably an alkali developing solution, But is not limited thereto. Among them, an alkali-soluble resin having a carboxyl group is preferable, and a copolymer of an ethylenically unsaturated monomer having at least one carboxyl group and another copolymerizable ethylenically unsaturated monomer is preferable.

Specific examples of the monomer include an ethylenically unsaturated monomer having a carboxyl group such as acrylic acid and methacrylic acid, a styrene copolymerizable with an ethylenically unsaturated monomer having a carboxyl group, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, Acrylate, allyl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, glycerol monoacrylate, glycerol methacrylate, N-phenylmaleimide, polystyrene macromonomers and poly And a methyl methacrylate macromonomer. The copolymer of the at least one ethylenically unsaturated monomer selected from the group consisting of methyl methacrylate macromonomers.

The acid value of the copolymer is preferably 50 to 300 mg KOH / g. In this case, when the acid value is less than 50 mg KOH / g, the solubility of the resist composition in an alkaline developer tends to be lowered. On the other hand, if it exceeds 300 mg KOH / g, the solubility in an alkali developing solution becomes excessive, and when developing with an alkali developing solution, the coloring layer tends to fall off from the substrate and tends to cause film roughness on the surface of the colored layer.

Further, in the present invention, the acid value is a value calculated arithmetically based on the amount of the ethylenically unsaturated monomer having a carboxyl group and a theoretical acid number and the amount of the ethylenically unsaturated monomer.

The weight average molecular weight of the alkali-soluble resin in the present invention is preferably 1,000 to 100,000. When the weight average molecular weight of the alkali-soluble resin is less than 1,000, the solubility of the alkali-soluble resin in the alkali developer is increased, and the development characteristics may be deteriorated. On the other hand, if it exceeds 100,000, the solubility in an organic solvent decreases, and the viscosity of the resist composition may increase.

In the present invention, the weight average molecular weight of the alkali-soluble resin is a weight average molecular weight in terms of polystyrene obtained based on GPC. In the present invention, Water 2690 (manufactured by Waters Corporation) is used as the apparatus and PLgel 5μ MIXED-D (manufactured by Polymer Laboratories) is used as the column.

In the pigment-dispersed resist composition for a color filter of the present invention, the alkali-soluble resin is used in an amount of usually 10 to 1,000 parts by mass, preferably 20 to 500 parts by mass, based on 100 parts by mass of the total organic pigment to be used. When the amount of the alkali-soluble resin used is less than 10 parts by mass, for example, there is a fear that the alkalinity developability is lowered, or dirt and film residue are formed on the substrate or the light-shielding layer of the unexposed portion. On the other hand, if it is more than 1,000 parts by mass, the concentration of the organic pigment relatively decreases, and therefore it may be difficult to achieve the intended color density as the thin film.

The photopolymerizable compound constituting the pigment dispersion resist composition for a color filter of the present invention will be described.

Examples of the photopolymerizable compound include monomers and oligomers having at least one photopolymerizable unsaturated bond in the molecule. The photopolymerizable unsaturated bond is an unsaturated bond that can be polymerized by the action of radicals or cations generated when a photopolymerization initiator described later is decomposed by an active energy ray such as ultraviolet rays or electron rays.

Examples of the monomer having one photopolymerizable unsaturated bond in the molecule include alkyl methacrylates such as methyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate Acrylates or acrylates; Aralkyl methacrylates or acrylates such as benzyl methacrylate and benzyl acrylate; Alkoxyalkyl methacrylates or acrylates such as butoxyethyl methacrylate and butoxy ethyl acrylate; Aminoalkyl methacrylates or acrylates such as N, N-dimethylaminoethyl methacrylate and N, N-dimethylaminoethyl acrylate; Methacrylic acid esters or acrylic acid esters of polyalkylene glycol alkyl ethers such as diethylene glycol ethyl ether, triethylene glycol butyl ether and dipropylene glycol methyl ether; Methacrylic acid esters or acrylic acid esters of polyalkylene glycol aryl ethers such as hexaethylene glycol phenyl ether; Isobornyl methacrylate or acrylate; Glycerol methacrylate or acrylate; 2-hydroxyethyl methacrylate, acrylate, and the like.

Examples of the monomer having two or more photopolymerizable unsaturated bonds in the molecule include bisphenol A dimethacrylate, 1,4-butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, diethylene glycol di Methacrylate, glycerol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, penta Diethylene glycol dimethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol penta methacrylate, bisphenol A diacrylate, diethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 4-butanediol diacrylate, 1,3-butylene glycol diacrylate, diethylene glycol diacrylate, But are not limited to, acrylonitrile, acrylonitrile, neopentyl glycol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, Acrylate, dipentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, and the like. These monomers may be used alone or in combination of two or more.

In the present invention, the amount of the photopolymerizable compound to be used is preferably in the range of 3 to 50 mass% with respect to the total solid content in the pigment dispersion resist composition for color filter.

The photopolymerization initiator constituting the pigment dispersion resist composition for a color filter of the present invention is not particularly limited as long as it is capable of generating radicals or cations by being irradiated with actinic energy rays such as ultraviolet rays or electron beams, N, N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, benzyl, 2,2-diethoxyacetophenone, benzoin, benzoin methyl Ether, benzoin isobutyl ether, benzyldimethyl ketal,? -Hydroxyisobutylphenone, thioxanthone, 2-chlorothioxanthone, 1-hydroxycyclohexyl phenyl ketone, t-butyl anthraquinone, 1- Quinone, 2,3-dichloroanthraquinone, 3-chlor-2-methyl anthraquinone, 2-ethyl anthraquinone, 1,4-naphthoquinone, 1,2-benzoanthraquinone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, triazine A photopolymerization initiator, and the like. These photopolymerization initiators may be used alone or in combination of two or more.

In the present invention, the amount of the photopolymerization initiator used is preferably in the range of 1 to 20% by mass based on the total solid content in the pigment dispersion resist composition for a color filter.

The organic solvent constituting the pigment dispersion resist composition for a color filter of the present invention is the same as the pigment dispersion listed above and preferably has a boiling point of 100 to 220 DEG C at normal pressure (1.013 x 10 ² KPa) Based organic solvents, ether-based organic solvents, ketone-based organic solvents, aromatic hydrocarbon solvents, and nitrogen-containing organic solvents.

Specific examples of these organic solvents include the same organic solvents as those mentioned above.

Among these organic solvents, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, cyclohexanone ether, and the like are preferable in terms of solubility, dispersibility, , 2-heptanone, ethyl 2-hydroxypropionate, 3-methyl-3-methoxybutyl propionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate and n-amyl formate are preferable And preferably propylene glycol monomethyl ether acetate.

These organic solvents are used in an amount of 50% by mass or more, more preferably 70% by mass or more, of the total organic solvent used in the pigment dispersion resist composition for a color filter of the present invention in terms of solubility, pigment dispersibility, .

Further, if the organic solvent containing a large amount of organic solvent having a boiling point exceeding 220 캜 is contained in the dried coating film without sufficiently evaporating the organic solvent at the time of prebaking the applied coating film, the heat resistance of the dried coating film may be lowered. If a large amount of the organic solvent having a boiling point of less than 100 캜 is contained, it is difficult to uniformly coat the organic solvent with no deviation, and there is a possibility that a coating film having excellent surface smoothness may not be obtained.

In the pigment dispersion resist composition for a color filter of the present invention, various additives such as other photopolymerizable compounds, heat polymerization inhibitors, ultraviolet absorbers, and antioxidants may be suitably used as needed.

A method for producing a pigment-dispersed resist composition for a color filter of the present invention using the above-mentioned constituent materials will be described.

The method for producing a pigment-dispersed resist composition for a color filter of the present invention is an example of a preferred embodiment of the present invention, and the present invention is not limited thereto.

In order to produce the pigment-dispersed resist composition for a color filter of the present invention with the above-described constituent materials, the photopolymerizable compound, the photopolymerization initiator, the alkali-soluble resin and, if necessary, the organic solvent, Adding an external additive, and stirring the mixture using a stirring device or the like.

The pigment dispersion auxiliary of the present invention having the above-described structure is produced efficiently using concentrated sulfuric acid or fuming sulfuric acid, and exhibits excellent pigment dispersibility by being used in combination with a pigment dispersant. Further, by using such a pigment dispersion auxiliary agent, a pigment dispersion having good flowability and dispersion stability can be obtained even when the organic pigment is finely dispersed. This pigment dispersion is excellent in lightness and color saturation, and thus can be suitably used in various inks for inkjet printers as well as various printing inks. Further, by using such a pigment dispersion in a resist for a liquid crystal color filter, it becomes possible to realize a liquid crystal color filter having a high brightness Y value and a contrast ratio.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise specified, "%" means "mass%" and "part" means "mass part". In the present specification, "Trimix" is a trademark of Inoue KK, "Irgacure" is a trademark of Chiba Specialty Chemicals Co., and "Disperbyk" is a trademark of Big Chemie.

<Pigment Dispersion Adjuster>

[Pigment Dispersion Adjuster 1]

30 ml of concentrated sulfuric acid was poured into a 100 ml Erlenmeyer flask, and while stirring with a magnetic stirrer, C.I. 10 g of Pigment Orange 71 (a compound represented by the above formula (2), trade name DPP Orange TR, manufactured by Ciba Specialty Chemicals) was added, and the mixture was stirred at room temperature for 30 minutes. A mixture of 50 g of water and 50 g of ice was put in a 1-liter beaker, the reaction product was poured into the ice water and stirred for 30 minutes by a magnetic stirrer. This was filtered and washed with reduced pressure, and the obtained solid was dried to obtain 12 g of pigment dispersion auxiliary agent 1 represented by the following formula (6).

[Chemical Formula 4]

[Pigment Dispersion Adjuster 2]

30 ml of concentrated sulfuric acid was poured into a 100 ml Erlenmeyer flask, and while stirring with a magnetic stirrer, C.I. 10 g of Pigment Red 255 (compound represented by the above formula (3)) was added, and the mixture was stirred at room temperature for 30 minutes. A mixture of 50 g of water and 50 g of ice was put in a 1-liter beaker, the reaction product was poured into the ice water and stirred for 30 minutes by a magnetic stirrer. This was filtered and washed with reduced pressure, and the obtained solid was dried to obtain 12 g of pigment dispersion auxiliary agent 2.

[Pigment Dispersion Adjuster 3]

30 ml of concentrated sulfuric acid was poured into a 100 ml Erlenmeyer flask, and while stirring with a magnetic stirrer, C.I. 10 g of Pigment Red 272 (compound represented by the above formula (4)) was added, and the mixture was stirred at room temperature for 30 minutes. A mixture of 50 g of water and 50 g of ice was put in a 1-liter beaker, the reaction product was poured into the ice water and stirred for 30 minutes by a magnetic stirrer. This was filtered and washed with water under reduced pressure, and the obtained solid was dried to obtain 12 g of Pigment Dispersion Adjuster 3.

[Pigment Dispersion Adjuster 4]

30 ml of concentrated sulfuric acid was poured into a 100 ml Erlenmeyer flask, and while stirring with a magnetic stirrer, C.I. 10 g of Pigment Red 264 (compound represented by the above formula (5)) was added, and the mixture was stirred at room temperature for 30 minutes. A mixture of 50 g of water and 50 g of ice was put in a 1-liter beaker, the reaction product was poured into the ice water and stirred for 30 minutes by a magnetic stirrer. This was filtered and washed with reduced pressure, but the crystallinity was poor and it was difficult to sufficiently wash the water. However, the obtained solid was dried to obtain 14 g of pigment dispersion auxiliary agent 4.

[Pigment Dispersion Adjuster 5]

30 ml of concentrated sulfuric acid was poured into a 100 ml Erlenmeyer flask, and while stirring with a magnetic stirrer, C.I. 10 g of Pigment Red 23 was added, and the mixture was stirred at room temperature for 30 minutes. A mixture of 50 g of water and 50 g of ice was put in a 1-liter beaker, the reaction product was poured into the ice water and stirred for 30 minutes by a magnetic stirrer. This was filtered and washed with water under reduced pressure, and the obtained solid was dried to obtain 12 g of the target compound (the compound represented by the following general formula (7)).

[Chemical Formula 6]

<Organic pigment>

[Preparation Example 1] (Trimix-treated Pigment Red 254)

A tank of Trimix TX-15 (manufactured by INOUE MFG. CO., LTD.) Was charged with C.I. 750 parts by mass of Pigment Red 254, 7500 parts by mass of sodium chloride having a particle diameter of 20 占 퐉 and 1800 parts by mass of diethylene glycol. Kneaded at 45 ° C for 3 hours in a range of 70% of the rated current value of 9.3 A, and subjected to salt milling. 1300 parts by mass of the obtained kneaded product was charged into 3 liters of hot water and stirred for 1 hour while heating at 70 DEG C to obtain a slurry. Filtration and washing were repeated to remove sodium chloride and diethylene glycol, followed by drying at 40 DEG C for one day and night to obtain 95 parts by mass of trimix-treated pigment red 254 (trimix-treated PR254).

[Preparation Example 2] (Salt milling treatment Pigment Red 254 using a kneader)

In a tank of Kidder (trade name: KHD-2, manufactured by INOUE MFG. CO., LTD.), C.I. 100 parts by mass of Particle Red 254, 1000 parts by mass of sodium chloride having a particle diameter of 20 占 퐉 and 240 parts by mass of diethylene glycol were charged and kneaded at 75 占 폚 for 10 hours for salt milling. 1300 parts by mass of the obtained kneaded product was charged into 3 liters of hot water and stirred for 1 hour while heating at 70 DEG C to obtain a slurry. Filtration and washing were repeated to remove sodium chloride and diethylene glycol, followed by drying at 40 DEG C to obtain 95 parts by mass of salt milled pigment red 254 (kneaded treatment PR254).

&Lt; Pigment dispersant having basic group >

Disperbyk-2001 (hereinafter also referred to as DB-2001, acrylic block copolymer having a basic group, manufactured by BICKEMISA)

Agisper 822 (hereinafter also referred to as PB-822, manufactured by Ajinomoto Fine Techno Co., Ltd., basic functional group-containing copolymer)

<Alkali-soluble resin>

BzMA / MAA copolymer (benzyl methacrylate / methacrylic acid copolymer, theoretical acid value: 120 mg KOH / g, weight average molecular weight: 25,000)

&Lt; Photopolymerizable compound >

DPEHA (dipentaerythritol hexaacrylate)

<Photopolymerization initiator>

Irgacure 907 (2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropane-1-one manufactured by Chiba Specialty Chemicals,

<Organic solvents>

PGMEA (propylene glycol monomethyl ether acetate)

<Pigment Dispersion>

In the composition shown in Table 1, the mixture was kneaded at a temperature of 40 to 50 캜 with a beads mill for 3 hours to obtain a pigment dispersion. The unit of the numerical value representing the composition is the mass part.

&Lt; Pigment-dispersed resist composition for color filter &

The pigment dispersion and other materials were uniformly mixed using a high-speed stirrer so as to have the composition shown in Table 1, and then filtered with a filter having a pore diameter of 3 탆 to obtain a pigment-dispersed resist composition for a color filter. The unit of the numerical value representing the composition is the mass part.

(Assessment Methods)

The following evaluation was carried out, and the results are shown in Table 2.

<Viscosity>

Each of the pigment-dispersed resist compositions for color filters of the examples and comparative examples was placed in a glass bottle, sealed with a stopper, and stored at room temperature for 1 day. Thereafter, an E-type viscometer (R100 type viscometer model ) Was used to measure the viscosity at 25 占 폚. The lower the viscosity, the better the fluidity, which means that it is excellent as a pigment dispersion. In Table 2, the term "measurement impossible" means that the viscosity is higher than the measurement limit of the E-type viscometer.

<Dispersion stability>

The pigment-dispersed resist compositions for color filters of the examples and comparative examples were each placed in a glass bottle, sealed with a stopper, and stored at room temperature for 1 day. The viscosity at 25 캜 and the viscosity after storage at 40 캜 for 7 days were measured with an E-type viscometer . The dispersion stability was evaluated by measuring (viscosity after storage at 40 占 폚 for 7 days) / (viscosity after storage at room temperature for 1 day). In Table 2, the term "gel" means that the dispersion stability was poor and gelation occurred during the evaluation.

<Contrast of Pigment-Dispersed Resist Composition for Color Filter>

The pigment-dispersed resist compositions for color filters in Examples and Comparative Examples were coated on a glass substrate to a film thickness of 1.0 mu m using a spin coater, pre-baked at 100 DEG C for 3 minutes, exposed with a high-pressure mercury lamp, Post-baked at 230 DEG C for 30 minutes.

Subsequently, the glass substrate coated with the resist composition was sandwiched between two polarizing plates (model number: SEG1224Du manufactured by Nitto Denko KK) and irradiated with a fluorescent lamp (wavelength range 380 to 780 nm) And the intensity of light transmitted when the polarizing planes of the polarizing plate on the front side and the polarizing plate on the rear side were parallel and at right angles was measured with an achromatic luminance meter (BM-5A manufactured by Topcon Corporation). The ratio of the brightness when the polarizing planes of the polarizing plate on the front side and the polarizing plate on the rear side were parallel and the ratio of the brightness when the polarizing planes of the front polarizing plate and the rear polarizing plate were perpendicular was evaluated as a contrast ratio.

The contrast ratio is the brightness when the polarizing planes of the polarizing plate on the front side and the polarizing plate on the rear side are parallel / the brightness when the polarizing planes of the front polarizing plate and the rear polarizing plate are at right angles). Further, the Bare Glass value, which is the contrast ratio in a state where the resist composition is not coated on the glass substrate, is set to 1000.

&Lt; Evaluation of color characteristics of pigment dispersion resist composition for color filter &

The color characteristics (x, y, and Y) of each resist of Example and Comparative Example in which the film thickness was 1.0 占 퐉 were measured by a spectrophotometer (UV-2500PC manufactured by Shimadzu Corporation; In Examples 1 and 2 and Comparative Examples 1 to 5, chromaticity y and brightness Y at chromaticity x = 0.600 were determined. The transmittance spectra of the coating films of the resist compositions of Example 1 and Comparative Example 5 were measured with a spectrophotometer (UV-2500PC, manufactured by Shimadzu Corporation) and are shown in Fig.

&Lt; Evaluation of Heat Resistance of Pigment-Dispersed Resist Composition for Color Filter >

The pigment-dispersed resist compositions for color filters in Examples and Comparative Examples were coated on a glass substrate to a film thickness of 1.0 mu m using a spin coater, pre-baked at 100 DEG C for 3 minutes, exposed with a high-pressure mercury lamp, Post-baked at 270 DEG C for 60 minutes. Thereafter, the surface of the obtained resist coating film was observed with a microscope (VHS-500, manufactured by KYOSEN CO., LTD., Magnification: 500 times), and the degree of surface roughness accompanying the pigment sublimation in the post-baking was observed. In Table 2, &quot; having a sublimated foreign substance &quot; means that the surface roughness accompanying the pigment sublimation in the postbake is large, and the heat resistance is bad. As an observation example, a microscope photograph of Example 1 and Comparative Example 5 is shown in Fig.

From Table 2, it was confirmed that in the examples using the pigment dispersion auxiliary agent of the present invention, excellent fluidity and dispersion stability were obtained, and contrast, color characteristics, and heat resistance were also excellent in Comparative Examples using different pigment dispersion auxiliary agents .

In Comparative Examples 2 and 3 in which a pigment dispersion auxiliary having a substituent different from that of the present invention was used in the diketopyrrolopyrrole skeleton, not only the viscosity at the time of producing the pigment dispersion was high but also gelled with time, . This is presumed to be due to the decomposition of the pigment in the process of sulfonating the pigment powder by the action of concentrated sulfuric acid. That is, among pigments having a diketopyrrolopyrrole skeleton, in particular, C.I. It can be seen that the pigment dispersion auxiliary agent can be stably obtained by using Pigment Orange 71 as a raw material.

Further, even when a compound (Comparative Example 4) in which a sulfo group is introduced into a diketopyrrolopyrrole skeleton without substituent (s) or a compound in which a sulfo group is introduced into an azo compound (Comparative Example 5) is used as a pigment dispersion auxiliary agent, , Not only the temporal stability is bad but also the contrast ratio or the brightness Y value is lower than that of the embodiment, which is not sufficient. Particularly, in the azo compound (Comparative Example 5), a sublimed foreign matter was identified and it was found that the heat resistance was poor.

However, Comparative Example 4 has the same diketopyrrolopyrrole skeleton as the present invention, but has a lower contrast ratio as compared with the case of using the pigment dispersion auxiliary agent of the present invention. This is because the crystallinity of the pigment dispersion auxiliary agent used in Comparative Example 4 is poor, so that it is impossible to sufficiently perform cleaning with sulfonation, so that a part of the sulfuric acid remains and adversely affects the pigment dispersion. At this point, C.I. It has been found that the pigment dispersion auxiliary of the present invention using Pigment Orange 71 as a raw material has good crystallinity and is particularly advantageous as a resist for a liquid crystal color filter.

Comparing the transmission spectra of Example 1 and Comparative Example 5 shows that the transmittance in the vicinity of 610 nm was high in Example 1 in addition to the sharp increase in the vicinity of 570 nm, (Fig. 1). Further, comparing the photographs of the surface of the resist coating film of Example 1 and Comparative Example 5 shown in Fig. 2, it can be seen that the surface roughening accompanied by the pigment sublimation in the post-baking of Example 1 is remarkably small. Also in this respect, it can be seen that the pigment dispersion auxiliary of the present invention is particularly advantageous for use as a resist for a liquid crystal color filter.

INDUSTRIAL APPLICABILITY The pigment dispersion auxiliary of the present invention can be applied not only to a liquid crystal color filter resist and an inkjet ink but also to various ink fields.

Fig. 1 is a graph showing the relationship between the pigment dispersion aid of Example 1 and Comparative Example 5, Pigment Red &lt; / RTI &gt; 254. The solid line is the transmission spectrum when the pigment dispersion auxiliary agent of Example 1 is used and the broken line is the transmission spectrum when the pigment dispersion auxiliary agent of Comparative Example 5 is used.

Fig. 2 is a surface state of the coating film after post-baking of the liquid crystal color filter resist using the pigment dispersion auxiliary agent of Example 1 or Comparative Example 5. Fig. On the left is the case of using the pigment dispersion auxiliary agent of Example 1 and on the right is the case of using the pigment dispersion auxiliary agent of Comparative Example 5.

Claims (10)

1. A pigment dispersion containing an organic pigment, a pigment dispersant, a pigment dispersion aid, and an organic solvent, The pigment dispersant is an acrylic block copolymer comprising a block having a basic group which is a tertiary amino group or a quaternary ammonium salt group and a block having no basic functional group, The pigment dispersion auxiliary is a compound represented by the following general formula (1). [Chemical Formula 1]

Wherein M is H, Na, K, NH ₄ or NR ¹ R ² R ³ R ^{4 wherein} R ¹ , R ² , R ³ and R ⁴ are the same or different, A saturated or unsaturated aliphatic hydrocarbon group of 1 to 10 carbon atoms, or an aromatic hydrocarbon group of 6 to 10 carbon atoms which may be substituted with another substituent. Here, the other substituent may be a hydroxyl group, a halogen, a carboxyl group, an amino group or a lower alkyl group having 1 to 5 carbon atoms . and m represents an integer of 1 or more. The method according to claim 1, Wherein the organic pigment is a diketopyrrolopyrrole pigment. 3. The method of claim 2, Wherein the diketopyrrolopyrrole pigment is C.I. Pigment Red 254 pigment dispersion. The method according to claim 1, Wherein the organic pigment is microparticulated. 5. The method of claim 4, A pigment dispersion wherein the atomization treatment is a salt milling treatment. 6. The method of claim 5, The salt milling treatment is carried out by kneading a mixture containing an organic pigment, a water-soluble inorganic salt and a water-soluble dispersion medium which does not substantially dissolve the inorganic salt in a kneading apparatus in which three agitating blades are revolved while rotating, A pigment, a salt, and a step of removing the water-soluble dispersion medium. A pigment dispersion resist composition for a color filter, comprising the pigment dispersion according to any one of claims 1 to 6. delete delete delete

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