JP5576242B2 - Method for producing pigment dispersion for color filter - Google Patents

Description

  The present invention relates to a method for producing a pigment dispersion for a color filter, and a coloring composition for a color filter containing the pigment dispersion obtained by the method.

  A color filter used in a liquid crystal display device is manufactured by a photolithography method in which a coloring composition obtained by blending a pigment dispersion with a resin or the like is applied to a transparent substrate such as glass, and then exposed, cured, developed, and thermally cured. Yes. The pigment dispersion used here is a non-aqueous pigment dispersion in which a pigment is dispersed in an organic solvent. As a method for producing a non-aqueous pigment dispersion, a production method using a polymer dispersant such as a graft polymer is known. ing.

For example, Patent Document 1 contains a pigment, a pigment dispersion polymer, and an organic solvent for the purpose of improving storage stability and heat resistance, and the amount of the polymer not adsorbed on the pigment is 2% by weight or less in the pigment dispersion. A pigment dispersion for a color filter is disclosed.
Patent Document 2 contains a graft-type polymer obtained by copolymerizing 5 to 30% by mass of acrylic acid in the main chain, a pigment, and an organic solvent for the purpose of improving dispersion stability, developability, and the like. A pigment dispersion composition is disclosed.

JP 2009-161692 A JP 2009-227839 A

In the production of a color filter using a photolithography method, the colored composition used is excellent in developability for quickly forming a pattern with a developer, but the obtained photocured film is not peeled off from the substrate. It is necessary to have excellent adhesion to the resin, and it is necessary to satisfy this contradictory performance. Furthermore, in order to satisfy these multiple performances, when an additive or the like is used, there is a problem that the dispersion stability in the pigment dispersion is lowered, and in particular, the dispersion stability during storage is lowered.
The present invention provides a method for producing a pigment dispersion for a color filter that can form a cured film having excellent dispersion stability during storage, developability, and substrate adhesion, and a pigment dispersion obtained by the method. It is an object of the present invention to provide a coloring composition for a color filter to be contained.

In the method for producing a pigment dispersion for a color filter, the present inventors used a graft polymer containing a nitrogen atom at the time of pigment dispersion treatment, and then mixed a graft polymer containing a carboxy group to achieve uniform dispersion. It has been found that sufficient developability and substrate adhesion can be obtained while maintaining the state.
That is, the present invention provides the following [1] and [2].
[1] A method for producing a pigment dispersion for a color filter, comprising the following steps (1) and (2).
Step (1): Graft polymer (A) containing a nitrogen atom and an organic pigment are dispersed in an ester organic solvent to obtain a pigment dispersion Step (2): Pigment dispersion obtained in step (1) Step of mixing liquid and carboxy group-containing graft polymer (B) However, both side chains of graft polymer (A) and (B) contain structural units derived from (meth) acrylic acid esters, The absolute value of the difference in Sp value (solubility parameter) of the side chain is 0.5 to 2.5.
[2] A coloring composition for a color filter containing a pigment dispersion obtained by the production method of [1].

  According to the present invention, a method for producing a pigment dispersion for a color filter capable of forming a cured film having excellent dispersion stability during storage, developability, and substrate adhesion, and pigment dispersion obtained by the method. The coloring composition for color filters containing a body can be provided.

The manufacturing method of the pigment dispersion for color filters of this invention has the following process (1) and (2), It is characterized by the above-mentioned.
Step (1): Graft polymer (A) containing a nitrogen atom and an organic pigment are dispersed in an ester organic solvent to obtain a pigment dispersion Step (2): Pigment dispersion obtained in step (1) Step of mixing liquid and carboxy group-containing graft polymer (B) However, both side chains of graft polymer (A) and (B) contain structural units derived from (meth) acrylic acid esters, The absolute value of the difference in Sp value (solubility parameter) of the side chain is 0.5 to 2.5.

In the present invention, a color filter pigment dispersion having excellent dispersion stability during storage can be obtained by the above-described steps, and the color filter coloring composition containing the obtained pigment dispersion has developability and adhesion to the substrate. The reason why a cured film having excellent properties can be formed is not clear, but is considered as follows.
That is, first, the functional group containing a nitrogen atom of the graft polymer (A) containing a nitrogen atom is very easily adsorbed to an organic pigment, and a side chain containing a structural unit derived from (meth) acrylic acid ester (for example, poly Since (meth) acrylic acid ester) has a very high affinity with ester organic solvents, it is considered that the pigment is finely dispersed in the solvent. Next, the pigment dispersion obtained in this manner and the graft polymer (B) containing a carboxy group are mixed to obtain a pigment dispersion. Since the side chain of the graft polymer (B) has a certain difference in Sp value from the side chain of the graft polymer (A), the polymers are hardly compatible with each other, due to the interaction between the functional group containing a nitrogen atom and a carboxy group. Aggregation of pigment particles and gelation of the pigment dispersion hardly occur. Therefore, the side chain (for example, poly (meth) acrylic acid ester) containing the structural unit derived from the (meth) acrylic acid ester of the graft polymer (B) is appropriately adsorbed on the surface of the pigment dispersed particle. ) Is considered to enhance the dispersibility in ester organic solvents and the dispersion stability during storage.
In the pigment dispersion obtained by the method of the present invention, since the graft polymer (B) containing a carboxy group is mixed at the end of production of the dispersion, the graft polymer (B) containing a carboxy group is adsorbed on the outermost surface of the pigment. It is considered that the anionic group on the pigment surface is ionized by the alkali developer, so that the developability in the alkali solution is excellent. In addition, since the graft polymer (B) is more easily adsorbed and oriented on the pigment surface than the random polymer, it is less compatible with the alkali-soluble resin in the resist and does not deteriorate the resist performance. It is thought that the adhesiveness of the composition to the substrate is excellent.
Hereafter, each component, process, etc. used for this invention are demonstrated.

[Organic pigments]
The organic pigment used in the present invention (hereinafter also simply referred to as “pigment”) is not particularly limited as long as it is suitably used for a color filter, such as an azo pigment, a phthalocyanine pigment, a condensed polycyclic pigment, and a lake pigment. Is mentioned.
As the azo pigment, C.I. I. Insoluble azo pigments such as CI Pigment Red 3; I. Soluble red azo pigments such as CI Pigment Red 48: 1; I. And condensed azo pigments such as CI Pigment Red 144. Examples of the phthalocyanine pigment include C.I. I. And copper phthalocyanine pigments such as CI Pigment Blue 15: 6.
Examples of the condensed polycyclic pigment include C.I. I. Anthraquinone pigments such as CI Pigment Red 177; I. Perylene pigments such as CI Pigment Red 123; I. Perinone pigments such as C.I. Pigment Orange 43; I. Quinacridone pigments such as C.I. Pigment Red 122; I. Dioxazine pigments such as CI Pigment Violet 23, C.I. I. Pigment Yellow 109 and other isoindolinone pigments, C.I. I. Pigment Orange 66 and other isoindoline pigments, C.I. I. Quinophthalone pigments such as CI Pigment Yellow 138; I. Pigment azo complex pigments such as CI Pigment Yellow 150, C.I. I. Indigo pigments such as CI Pigment Red 88; I. Metal complex pigments such as C.I. Pigment Green 8; I. Pigment red 254, C.I. I. Pigment red 255, C.I. I. And diketopyrrolopyrrole pigments such as CI Pigment Orange 71.
Among these, a diketopyrrolopyrrole pigment represented by the following general formula (1) is preferable from the viewpoint of more effectively expressing the effects of the present invention.

In formula (1), X ¹ and X ² each independently represent a hydrogen atom or a halogen atom, and Y ¹ and Y ² each independently represent a hydrogen atom or a —SO ₃ H group. The halogen atom is preferably a fluorine atom or a chlorine atom.
Preferable examples of commercially available diketopyrrolopyrrole pigments include Ciba Specialty Chemicals, Inc., C.I. I. Pigment Red 254, trade names "Irgaphor Red B-CF", "Igaphor Red BK-CF", "Irgaphor Red BT-CF", "Irgazin DPP Red BO", "Irgazin DPP Red BL", "Cromophtal DPP Red BP" , “Cromophtal DPP Red BOC” and the like.
From the viewpoint of improving the lightness Y value, it is desirable to use an atomized product having an average primary particle diameter of preferably 100 nm or less, more preferably 20 to 60 nm. The average primary particle diameter of the organic pigment can be determined by a method of directly measuring the size of primary particles from an electron micrograph. Specifically, the short axis diameter and the long axis diameter of each primary particle are measured, and the average value thereof is defined as the particle diameter of the particle. For 100 or more particles, the volume of each particle is expressed as one side of the particle diameter. The volume average particle diameter is obtained by approximating to the cube as described above, and this is used as the average primary particle diameter.
Said organic pigment can be used individually or in combination of 2 or more types.

[Graft polymer containing nitrogen atom (A)]
The graft polymer (A) containing a nitrogen atom used in the present invention (hereinafter, also simply referred to as “graft polymer (A)”) has a side chain containing a structural unit derived from a (meth) acrylate ester, The absolute value of the difference between the Sp value of the chain and the Sp value of the side chain of the graft polymer (B) described later is 0.5 to 2.5.
The absolute value of the difference in the Sp value is preferably 0.65 to 2.3, more preferably 0.7 to 2.0, from the viewpoint of maintaining good pigment dispersibility and storage stability of the pigment dispersion. .8 to 1.8 is more preferable.
In the present specification, “(meth) acrylic acid” means “acrylic acid and / or methacrylic acid”.
Moreover, although the graft polymer (A) contains a nitrogen atom, it is preferable to contain a nitrogen atom in the main chain of the graft polymer (A) from the viewpoint of adsorptivity to an organic pigment.
Moreover, it is preferable that a graft polymer (A) has a hydroxyl group further from a viewpoint of the adsorptivity to an organic pigment.

The main chain of the graft polymer (A) preferably contains a structural unit derived from a vinyl monomer containing a nitrogen atom including a functional group such as an amide group or an amino group, from the viewpoint of adsorptivity to an organic pigment.
The side chain of the graft polymer (A) contains a structural unit derived from (meth) acrylic acid ester. From the viewpoint of enhancing the dispersibility of the organic pigment in the solvent, benzyl (meth) acrylate and / or ( It is preferable to contain a structural unit derived from alkyl (meth) acrylate, and it is more preferable to contain a structural unit derived from benzyl (meth) acrylate. Among these, the side chain is preferably poly (meth) acrylate benzyl.
The graft polymer (A) may be a copolymer obtained by copolymerizing another monomer copolymerizable with the monomer in any of the main chain and the side chain within a range not inhibiting the effects of the present invention.

The weight average molecular weight of the graft polymer (A) is preferably 1000 to 1,000,000, more preferably 2000 to 800,000, and still more preferably 5000, from the viewpoint of adsorptivity to the organic pigment and suppression of increase in viscosity. 700,000.
From the viewpoint of storage stability of the pigment dispersion of the present invention, the number average molecular weight of the main chain of the graft polymer (A) is preferably 500 to 50,000, more preferably 1000 to 30,000, still more preferably 2000 to 20,000. Further, the weight average molecular weight of the main chain is preferably 1500 to 150,000, more preferably 3000 to 90,000, and still more preferably 6000 to 60,000, from the same viewpoint.
From the viewpoint of storage stability of the pigment dispersion of the present invention, the number average molecular weight of the side chain of the graft polymer (A) is preferably 500 to 20,000, more preferably 700 to 10,000, still more preferably 700 to 6000.
In addition, the measurement of a weight average molecular weight and a number average molecular weight can be performed by the method of an Example description.

(Monomer that is a structural unit of the main chain of the graft polymer (A))
As the monomer that is a constituent unit of the main chain of the graft polymer (A), a vinyl monomer containing a nitrogen atom is preferably contained from the viewpoint of adsorptivity to the pigment.
As the vinyl monomer containing a nitrogen atom, a vinyl monomer containing an amide group is preferred.
Specific examples of the vinyl monomer containing an amide group include (meth) acrylamides and vinylpyrrolidones.
Specific examples of other vinyl monomers containing nitrogen atoms include vinylpyridines, nitrogen-containing styrene monomers, nitrogen-containing (meth) acrylic acid esters, and the like.
(Meth) acrylamides include (meth) acrylamide, N, N-dialkyl (meth) acrylamide (the alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms), and N-alkyl (meta). ) Acrylamide (the alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms), N, N-dialkyl (the alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms) Aminoalkyl (the alkyl group preferably has 1 to 6 carbon atoms) (meth) acrylamide, (meth) acrylamide 2-methylpropylsulfonic acid, morpholino (meth) acrylamide, piperidino (meth) acrylamide, N-methyl-2-pyrrolidyl (Meth) acrylamide, N, N-methylphenyl (meth) acrylamide and the like can be mentioned.
Examples of vinyl pyrrolidones include N-vinyl-2-pyrrolidone.

Examples of vinylpyridines include 2-vinylpyridine and 4-vinylpyridine, and examples of nitrogen-containing styrene monomers include p-styrenesulfonamide, p-aminostyrene, and aminomethylstyrene.
As the nitrogen-containing (meth) acrylic acid ester, N, N-dialkyl (the carbon number of the alkyl group is preferably 1 to 8, more preferably 1 to 4) aminoalkyl (the carbon number of the alkyl group is preferably 1 to 6). ) (Meth) acrylate, 1- (N, N-dialkylamino) -1,1-dimethylmethyl (meth) acrylate (the carbon number of the alkyl group is preferably 1-8, more preferably 1-4), Morpholinoethyl (meth) acrylate, piperidinoethyl (meth) acrylate, 1-pyrrolidinoethyl (meth) acrylate, N, N-dimethyl-2-pyrrolidylaminoethyl (meth) acrylate, N, N-methylphenylaminoethyl (meth) ) Acrylate and the like.
Among these vinyl monomers containing nitrogen atoms, (meth) acrylamides and vinylpyrrolidones are preferred, and N-vinylpyrrolidone is more preferred from the viewpoint of adsorptivity to organic pigments.
The content of the structural unit derived from the vinyl monomer containing nitrogen atoms in all the structural units of the graft polymer is from the viewpoint of adsorptivity to the organic pigment, and from the viewpoint of suppressing the increase in viscosity and optimizing the dispersed particle size. Preferably it is 1-30 weight%, More preferably, it is 2-25 weight%, More preferably, it is 5-20 weight%.

As a monomer that becomes a constituent unit of the main chain, it is preferable to use a vinyl monomer further containing a hydroxyl group.
Examples of the vinyl monomer containing a hydroxyl group include (meth) acrylic acid hydroxyalkyl such as 2-hydroxyethyl (meth) acrylate; glycerin mono (meth) acrylate; (meth) acrylic acid poly (meth) acrylate such as polyethylene glycol Examples include alkylene glycol.
Among these vinyl monomers containing a hydroxyl group, hydroxyalkyl (meth) acrylate is preferable and 2-hydroxyethyl (meth) acrylate is more preferable from the viewpoint of adsorptivity to an organic pigment.
The content of the structural unit derived from the vinyl monomer containing a hydroxyl group in all the structural units of the graft polymer (A) is the viewpoint of the adsorptivity to the organic pigment, and the viewpoint of suppressing the increase in viscosity and optimizing the dispersed particle size. Therefore, it is preferably 2 to 30% by weight, more preferably 5 to 20% by weight, and still more preferably 7 to 18% by weight.

(Monomer that is a constituent unit of the side chain of the graft polymer (A))
As a monomer which becomes a structural unit of the side chain of the graft polymer (A), it is preferable to contain a (meth) acrylic acid ester from the viewpoint of enhancing the dispersibility of the pigment in the solvent.
Examples of (meth) acrylic acid esters include: (meth) acrylic acid alkyl such as methyl (meth) acrylate, ethyl (meth) acrylate, stearyl (meth) acrylate; benzyl (meth) acrylate; (meth) acrylic acid Examples include isobornyl; 2-hydroxyethyl (meth) acrylate; glycerin mono (meth) acrylate; perfluorooctylethyl (meth) acrylate; methoxypolyethylene glycol (meth) acrylate. Among these, alkyl (meth) acrylate and benzyl (meth) acrylate are preferable, and benzyl (meth) acrylate is more preferable.
Among the alkyl (meth) acrylates, methyl (meth) acrylate and ethyl (meth) acrylate are preferable, and methyl (meth) acrylate is more preferable.
The (meth) acrylic acid ester can be used alone or in combination of two or more.
The content of the structural unit derived from the (meth) acrylic acid ester in the side chain of the graft polymer (A) is not particularly limited, but is preferably 5 to 100% by weight with respect to all the structural units in the side chain. More preferably, it is 50-100 weight%, More preferably, it is 80-100 weight%.

[Production of Graft Polymer (A)]
The method for producing the graft polymer (A) includes (i) a method of copolymerizing a monomer that is a constituent unit of the main chain and a macromonomer that constitutes a side chain (macromonomer method), and (ii) a constitution of the main chain. A method (coupling method) in which a polymer to be polymerized and a polymer constituting a side chain are subjected to a coupling reaction is mentioned. From the viewpoint of fine stabilization of the organic pigment, (ii) a coupling method is preferable.

(Production of graft polymer (A) by coupling method)
The polymer constituting the main chain used for the coupling reaction preferably contains a structural unit derived from a vinyl monomer containing a reactive functional group. The polymer can be obtained by copolymerizing a mixture of monomers that are constituent units of the main chain.
Examples of the vinyl monomer containing a reactive functional group include monomers containing an epoxy group, an isocyanate group, a carboxy group, a phosphoric acid group, a sulfonic acid group, and an amino group. Is preferable, (meth) acrylic acid esters containing a glycidyl group are preferable, and glycidyl (meth) acrylate is more preferable.
When the polymer constituting the main chain used for the coupling reaction contains an epoxy group as a reactive functional group, the epoxy value of the main chain is 45 to 125 mgKOH / g from the viewpoint of reactivity with the side chain and the like. Preferably, 55 to 115 mgKOH / g is more preferable, and 65 to 105 mgKOH / g is still more preferable.
The epoxy value can be measured by the method described in the examples.

The polymer constituting the side chain used in the coupling reaction may be a poly (meth) acrylate ester having a reactive functional group that reacts with the reactive functional group of the polymer constituting the main chain at one end. preferable.
When the reactive functional group of the polymer constituting the main chain is an epoxy group, one end of the polymer constituting the side chain is preferably a carboxy group or an amino group.
The polymer constituting the side chain used for the coupling reaction is preferably obtained by solution polymerization using, for example, a polymerization initiator or chain transfer agent containing a carboxy group or amino group which is a reactive functional group.
The coupling reaction between the polymer constituting the side chain and the polymer constituting the main chain may be performed under the condition that each reactive functional group sufficiently reacts, but each polymer is dissolved in an organic solvent in the presence of a catalyst. It is preferable to carry out.
Examples of the catalyst include quaternary ammonium salts such as quaternary ammonium halides, tertiary amines such as triethylamine, alkali metal hydroxides, inorganic acids, sulfonic acids, carboxylic acids, solid acids, solid bases, and the like. . In these, a quaternary ammonium halide is more preferable and tetrabutylammonium bromide is still more preferable.

[Graft polymer containing carboxyl group (B)]
The graft polymer (B) containing a carboxy group used in the present invention (hereinafter also simply referred to as “graft polymer (B)”) has a side chain containing a structural unit derived from a (meth) acrylate ester, The absolute value of the difference between the Sp value of the chain and the Sp value of the side chain of the graft polymer (A) is 0.5 to 2.5.
The absolute value of the difference in the Sp value is preferably 0.65 to 2.3, more preferably 0.7 to 2.0, from the viewpoint of maintaining good pigment dispersibility and storage stability of the pigment dispersion. .8 to 1.8 is more preferable.
The graft polymer (B) contains a carboxy group, but preferably contains a carboxy group in the main chain from the viewpoint of developability and adsorptivity to an organic pigment, and both the main chain and the side chain have a carboxy group. More preferably, it contains a group.

The main chain of the graft polymer (B) preferably contains a structural unit derived from a vinyl monomer containing a carboxy group, from the viewpoint of adsorptivity to an organic pigment and developability.
Further, the side chain of the graft polymer (B) contains a structural unit derived from (meth) acrylic acid ester. From the viewpoint of enhancing the dispersibility of the organic pigment in the solvent, benzyl (meth) acrylate and / or ( It is preferable to contain a structural unit derived from an alkyl (meth) acrylate, and it is more preferable to contain a structural unit derived from an alkyl (meth) acrylate. Of these, the side chain is preferably methyl poly (meth) acrylate.
The graft polymer (B) may be a copolymer obtained by copolymerizing another monomer copolymerizable with the monomer in any of the main chain and the side chain within the range not impairing the effects of the present invention.
The acid value of the graft polymer (B) is preferably 20 to 200 mgKOH / g, more preferably 30 to 160 mgKOH / g, and still more preferably 40 to 120 mgKOH / g, from the viewpoint of dispersion stability. Here, the acid value means the number of mg of KOH required to neutralize 1 g of the solid content of the dispersant, and can be measured by the method described in JIS K0070.

The weight average molecular weight of the graft polymer (B) is preferably 1000 to 1,000,000, more preferably 2000 to 800,000, and still more preferably 5000, from the viewpoint of adsorptivity to the organic pigment and suppression of increase in viscosity. 700,000.
The number average molecular weight of the main chain of the graft polymer (B) is preferably 500 to 50,000, more preferably 1000 to 30,000, and still more preferably 2000 to 20 from the viewpoint of storage stability of the dispersion of the present invention. , 000. Further, the weight average molecular weight of the main chain is preferably 1500 to 150,000, more preferably 3000 to 90,000, and still more preferably 6000 to 60,000, from the same viewpoint.
The number average molecular weight of the side chain of the graft polymer (B) is preferably 500 to 20,000, more preferably 700 to 10,000, and particularly preferably 700 to 6000, from the viewpoint of storage stability of the dispersion of the present invention. It is.
In addition, the measurement of a weight average molecular weight and a number average molecular weight can be performed by the method of an Example description.

(Monomer that is a structural unit of the main chain of the graft polymer (B))
From the viewpoint of improving the developability of the coloring composition, it is preferable to contain a monomer containing a carboxy group as the monomer that is a constituent unit of the main chain of the graft polymer (B).
Examples of the vinyl monomer containing a carboxy group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid.
Among the above-mentioned vinyl monomers containing a carboxy group, from the viewpoint of improving the copolymerizability with other monomers, particularly the macromonomer as a side chain, and thus improving the developability and substrate adhesion of the colored composition, Acid and methacrylic acid are more preferable, and acrylic acid is more preferable.
The content of the structural unit derived from the vinyl monomer containing a carboxy group in all the structural units of the graft polymer (B) is in view of the adsorptivity to the organic pigment, the suppression of increase in viscosity and the optimization of the dispersed particle size. From the viewpoint, it is preferably 1 to 30% by weight, more preferably 2 to 25% by weight, still more preferably 5 to 20% by weight.

(Monomer that is a structural unit of the side chain of the graft polymer (B))
As a monomer which becomes a structural unit of the side chain of the graft polymer (B), it is preferable to contain a (meth) acrylic acid ester from the viewpoint of enhancing the dispersibility of the pigment in the solvent.
Examples of (meth) acrylic acid esters include: (meth) acrylic acid alkyl such as methyl (meth) acrylate, ethyl (meth) acrylate, stearyl (meth) acrylate; benzyl (meth) acrylate; (meth) acrylic acid Examples include isobornyl; 2-hydroxyethyl (meth) acrylate; glycerin mono (meth) acrylate; perfluorooctylethyl (meth) acrylate; methoxypolyethylene glycol (meth) acrylate. Of these, benzyl (meth) acrylate and alkyl (meth) acrylate are preferred, alkyl (meth) acrylate is more preferred, methyl (meth) acrylate and ethyl (meth) acrylate are more preferred, ) Methyl acrylate is more preferred.
The (meth) acrylic acid ester can be used alone or in combination of two or more.
The content of the structural unit derived from the (meth) acrylic acid ester in the side chain of the graft polymer (B) is not particularly limited, but is preferably 5 to 100% by weight with respect to all the structural units in the side chain. More preferably, it is 50-100 weight%, More preferably, it is 80-100 weight%.

  Regarding the side chain of the graft polymer, one side chain of the graft polymer (A) or (B) contains a structural unit derived from benzyl (meth) acrylate, and the other side chain is (meth) acrylic acid. It is preferable to contain a structural unit derived from alkyl, and from the viewpoint of improving the developability of the colored composition, the side chain of the graft polymer (A) contains a structural unit derived from benzyl (meth) acrylate, and the graft polymer It is more preferable that the side chain of (B) contains the structural unit derived from alkyl (meth) acrylate. Further, from the viewpoint of improving the contrast of the coloring composition, the side chain of the graft polymer (A) contains a structural unit derived from an alkyl (meth) acrylate, and the side chain of the graft polymer (B) is (meth). More preferably, it contains a structural unit derived from benzyl acrylate. The reason for this is not clear, but the pigment dispersion of the present invention contains either the graft polymer (A) which mainly contributes to the dispersibility of the pigment or the graft polymer (B) which mainly contributes to the solubility in the developer. This is considered to be due to whether or not a structural unit derived from an alkyl (meth) acrylate having a high affinity for an organic solvent is contained.

[Production of Graft Polymer (B)]
As a method for producing the graft polymer (B), (i) a method in which a monomer that is a constituent unit of a main chain and a macromonomer that constitutes a side chain are copolymerized (macromonomer method), and (ii) the main chain is constituted. From the viewpoint of obtaining a graft polymer with less impurities and improving the developability of the colored composition and the substrate adhesion, although there is a method of coupling the polymer to be polymer and the polymer constituting the side chain (coupling method). (I) The macromonomer method is preferred.

(Production of graft polymer (B) by the macromonomer method)
The macromonomer constituting the side chain is preferably a (meth) acrylic acid ester macromonomer, having a structural unit derived from the alkyl (meth) acrylate, and having a polymerizable functional group at one end thereof.
The polymerizable functional group of the (meth) acrylic acid ester macromonomer is preferably an acryloyloxy group or a methacryloyloxy group.
In this method, a monomer mixture containing a monomer that is a constituent unit of the main chain and a macromonomer that constitutes a side chain (hereinafter referred to as “monomer mixture”) is copolymerized to obtain a graft polymer.
The monomer mixture can be copolymerized by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable from the viewpoint of using an organic solvent for the pigment dispersion.
As the organic solvent used in the solution polymerization method, an organic solvent having a high affinity with the graft polymer (B) is preferable, and the organic solvents described above can be used.

In the polymerization, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), tert-butyl peroxyoctoate, dibenzoyl peroxide, etc. Known radical polymerization initiators such as organic peroxides can be used.
The amount of the radical polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture.
In the polymerization, a known polymerization chain transfer agent such as mercaptans such as octyl mercaptan and 2-mercaptoethanol and thiuram disulfide can be further added.
The polymerization conditions of the monomer mixture vary depending on the type of polymerization initiator, monomer, and solvent used, but the polymerization temperature is usually 30 to 100 ° C., preferably 50 to 80 ° C., and the polymerization time is such as the polymerization temperature. Although it depends on conditions and cannot be determined in general, it is usually about 1 to 20 hours. The polymerization atmosphere is preferably an inert gas atmosphere such as nitrogen gas or argon.
After completion of the polymerization reaction, the produced polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained polymer can be purified by repeating reprecipitation or by removing unreacted monomers and the like by membrane separation, chromatography, extraction and the like.

  In addition, when graft polymer (B) has a carboxy group in a side chain, a suitable method can be selected with the synthesis method. When polymerizing the polymer constituting the side chain, a monomer having an anionic group may be copolymerized, or a monomer having a hydroxyl group is copolymerized first, and then a graft polymer is prepared, and then a polybasic acid anhydride is prepared. May be reacted with a hydroxyl group to generate a carboxyl group which is an anionic group.

[Ester organic solvent]
The ester organic solvent used in the present invention is not particularly limited, but it is preferable to use a high boiling organic solvent having a boiling point of 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher. Preferred examples of such a high boiling point organic solvent include (i) alkanediyl glycol monoalkyl ether propionate and (ii) alkanediyl glycol monoalkyl ether acetate.
(I) Alkanediyl glycol monoalkyl ether propionate includes ethylene glycol monomethyl ether propionate, ethylene glycol monoethyl ether propionate, propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether propionate, etc. Can be mentioned.
(Ii) Alkanediyl glycol monoalkyl ether acetate includes ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether An acetate (BCA) etc. are mentioned.
Among the ester organic solvents, (ii) alkanediyl glycol monoalkyl ether acetates from the viewpoints of the solubility of the graft polymers (A) and (B) and the dispersibility of the organic pigments, particularly diketopyrrolopyrrole pigments. Are more preferable, propylene glycol monomethyl ether acetate (PGMEA, boiling point: 146 ° C.) and diethylene glycol monobutyl ether acetate (BCA, boiling point: 247 ° C.) are more preferable, and propylene glycol monomethyl ether acetate (PGMEA) is particularly preferable.
Said ester organic solvent can be used individually or in combination of 2 or more types.

[Method for producing pigment dispersion]
The manufacturing method of the pigment dispersion for color filters of this invention has the following process (1) and (2), It is characterized by the above-mentioned.
Step (1): Graft polymer (A) containing a nitrogen atom and an organic pigment are dispersed in an ester organic solvent to obtain a pigment dispersion Step (2): Pigment dispersion obtained in step (1) Step of mixing liquid and carboxy group-containing graft polymer (B) However, both side chains of graft polymer (A) and (B) contain structural units derived from (meth) acrylic acid esters, The absolute value of the difference in Sp value (solubility parameter) of the side chain is 0.5 to 2.5.
Further, from the viewpoint of substrate adhesion and heat resistance, it is preferable to have a step of removing the graft polymer (A) not adsorbed to the pigment after the step (1) and before the step (2).

[Step (1)]
There is no restriction | limiting in particular in the dispersion method in process (1), Even if the target pigment dispersion liquid is obtained by the dispersion | distribution containing the graft polymer (A) containing a nitrogen atom, an organic pigment, and an ester organic solvent once. However, it is preferable from the viewpoint of obtaining a finer and more uniform pigment dispersion that the mixture is pre-dispersed and further dispersed.

(Preliminary dispersion)
In the preliminary dispersion in the step (1), all components composed of the graft polymer (A) containing a nitrogen atom, an organic pigment and an ester organic solvent may be mixed and dispersed at one time, but the graft polymer (A) and It is preferable that a premixture is prepared by premixing with an ester organic solvent, and an organic pigment is mixed and dispersed in the premixture obtained to obtain a final mixture.
In the preliminary dispersion step, the weight ratio of the graft polymer (A) to the organic pigment [graft polymer (A) / organic pigment] is selected from the viewpoint of adhering a required amount of the graft polymer (A) to the organic pigment. Polymer (A) / Organic pigment] is preferably 0.3 to 2.0, more preferably 0.4 to 1.5.
The proportion of the organic pigment in the pigment dispersion is preferably 3% by weight or more from the viewpoint of obtaining good colorability, preferably 3 to 30% by weight, and 5 to 20% from the viewpoint of obtaining good colorability and viscosity. % Is more preferable.
In the preliminary dispersion step, the content of the graft polymer (A) in the pigment dispersion is preferably 2 to 15% by weight from the viewpoint of lowering the viscosity of the dispersion and obtaining a cured film excellent in contrast. 10 to 10% by weight is more preferable.
The content of the ester organic solvent in this step is preferably 20 to 90% by weight, more preferably 40 to 80% by weight, from the viewpoint of uniform dispersion.
The dispersion time in the preliminary dispersion step is not particularly limited, but is preferably 0.1 to 10 hours, more preferably 0.5 to 4 hours, and still more preferably 1 to 3 hours.

There is no particular limitation on the mixing disperser used in the preliminary dispersion, and various known dispersers can be used. For example, a commonly used mixing and stirring apparatus equipped with anchor blades, etc., specific examples include a homomixer such as Ultratax (trade name, manufactured by IKA Japan Co., Ltd.), Ultra Disper, Desperm (Asada Tekko Co., Ltd., product) Name), Milder (Ebara Manufacturing Co., Ltd., Taiheiyo Kiko Co., Ltd., trade name), TK Homomixer, TK Pipeline Mixer, TK Homojetter, TK Homomic Line Flow, Filmix (and above, Primix Co., Ltd., trade name), etc. Kneading machines such as high-speed agitating and mixing equipment, roll mills, kneaders, extruders, etc., and high-pressure homogenizers such as high-pressure homogenizers (Izumi Food Machinery Co., Ltd., trade names), microfluidizers (Microfluidics, trade names) ), Nanomizer (Yoshida machine) Kogyo Co., Ltd., trade name), Optimizer, Starburst (Sugino Machine Co., Ltd.) and other chamber type high-pressure dispersers such as high-pressure homogenizers, paint shakers, bead mills, dyno mills (manufactured by Shinmaru Enterprises, Media-type dispersers such as trade name). A plurality of these devices can be combined.
Among these, from the viewpoint of uniformly mixing the organic pigment in the organic solvent, a high-speed stirring and mixing device such as a homomixer, and a media type dispersing machine such as a paint shaker or a bead mill are preferable, and these are more preferably used in combination.

(Distributed)
This dispersion is a step of dispersing the preliminary dispersion obtained in the preliminary dispersion, and is performed to further refine the mixture obtained in the preliminary dispersion step. From the viewpoint of miniaturizing the organic pigment, It is preferable to use a media-type disperser, and the above-described high-pressure disperser may be used in combination.
As the material of the media used in this dispersion step, ceramics such as zirconia and titania, polymer materials such as polyethylene and nylon, metals and the like are preferable, and zirconia is preferable from the viewpoint of wear. The particle size of the media is preferably 0.003 to 0.1 mm. From the viewpoint of refining the organic pigment, it is more preferably 0.07 mm or less, further preferably 0.05 mm or less, and from the viewpoint of separating the media from the pigment, 0.005 mm or more is more preferable, and 0.01 mm or more is more preferable.
As the media type disperser used in this dispersion step, a paint shaker, a bead mill or the like is preferable. As a commercially available media type disperser, Ultra Apex Mill (trade name, manufactured by Kotobuki Industries Co., Ltd.), Pico Mill (Asada Tekko Co., Ltd.) Company name, product name) and the like.

From the viewpoint of storage stability of the resulting pigment dispersion, it is preferable to maintain the temperature during dispersion at 10 to 35 ° C, more preferably 15 to 30 ° C, and still more preferably 18 to 27 ° C.
Since there is heat generation during dispersion, it is preferable to cool the dispersion appropriately. For example, when the disperser is a paint shaker, cooling is preferably performed using a spot cooler that blows cold air. When the disperser is a bead mill, kneader, or high-pressure disperser, cooling is preferably performed by flowing a coolant through a jacket.
The dispersion time of this dispersion is preferably 3 to 200 hours and more preferably 5 to 50 hours from the viewpoint of sufficiently miniaturizing the organic pigment.

Further, the graft polymer (A) may be added at the start or during the dispersion step. If the graft polymer (A) is added, the dispersibility of the organic pigment is improved, the viscosity is slightly lowered, and the stability of the pigment dispersion is also improved.
The content of the graft polymer (A) in the pigment dispersion is preferably 3 to 15% by weight from the viewpoint of lowering the viscosity of the pigment dispersion and obtaining a cured film excellent in contrast. Is more preferable.
In the present dispersion step, the ratio of the organic pigment in the pigment dispersion is preferably 3% by weight or more from the viewpoint of obtaining good colorability, and preferably 3 to 30% by weight from the viewpoint of obtaining good colorability and viscosity. 5 to 20% by weight is more preferable.
Further, in this step, the weight ratio of the graft polymer (A) to the organic pigment [graft polymer (A) / organic pigment] is 0.3 to from the viewpoint of reducing the viscosity of the dispersion and improving the contrast of the cured film. 1.5 is preferable, and 0.4 to 1.4 is more preferable.
The content of the ester organic solvent in this step is preferably 20 to 90% by weight, more preferably 40 to 80% by weight, from the viewpoint of uniform dispersion.

The viscosity of the pigment dispersion is preferably 1 to 100 mPa · s (20 ° C), more preferably 1 to 80 mPa · s (20 ° C), and still more preferably 1 to 50 mPa · s (20 ° C). The viscosity can be adjusted by adjusting the power of the disperser and the mixing ratio of the organic pigment, graft polymer (A), and ester organic solvent.
From the viewpoint of reducing the viscosity of the pigment dispersion, the pigment dispersion obtained by the preliminary dispersion may be ultrafiltered or centrifuged to remove the graft polymer (A) or the like that is not adsorbed on the organic pigment. . Furthermore, the dispersion or sediment obtained by ultrafiltration or centrifugation may be redispersed with a disperser.

[Step of removing graft polymer (A) not adsorbed to organic pigment]
In the method for producing a pigment dispersion for a color filter of the present invention, from the viewpoint of maintaining good storage stability, the graft polymer (A) not adsorbed to the organic pigment after step (1) and before step (2). It is preferable to have the process of removing.
The method for removing the graft polymer (A) not adsorbed on the organic pigment is not particularly limited, but a method using a centrifugal separation treatment is preferable.

Specific examples of the centrifugation treatment include the following methods.
First, the pigment dispersion obtained in the step (1) is centrifuged using a centrifuge, separated into a liquid and a solid, and the liquid is removed to recover the solid.
Next, since the polymer that is not adsorbed to the organic pigment exists in the organic solvent, the whole or a part of the upper layer part (supernatant liquid) is removed during or after the centrifugation. Can be removed properly. The recovered solid content mainly consists of particles in which the graft polymer (A) is adsorbed on the organic pigment, and after the centrifugal separation, it becomes a slurry or cake and remains on the side wall or bottom of the centrifuge. Can be easily recovered.
By removing the liquid and recovering the solid content, and reducing the amount of polymer not adsorbed to the organic pigment to 2% by weight or less, the storage stability and heat resistance of the resulting pigment dispersion can be greatly improved. .

The centrifuge that can be used is not particularly limited. For example, a basket-type centrifuge described in JP-A-2003-93911 is preferable. Examples of commercially available non-porous wall-type centrifuges include: And KBS type manufactured by Kansai Centrifugal Machinery Co., Ltd., S type centrifugal separator manufactured by Tanabe Wiltech Co., Ltd., and the like.
There is no particular limitation on the operation method of the centrifuge. Either (i) a continuous type in which the separation liquid layer is discharged while supplying the raw liquid dispersion, and (ii) a batch type in which the liquid layer is discharged when the separation liquid layer is formed after supplying the raw liquid dispersion. It may be a driving method.
The centrifugal acceleration in the centrifugal separation is preferably 5,000 to 50,000 G, more preferably 10,000 to 30,000 G, from the viewpoint of reducing the amount of polymer not adsorbed to the organic pigment contained in the stock dispersion. It is.

Furthermore, in the case of the centrifugation process, an organic solvent can be added to the solid content obtained by the centrifugation process and redispersed.
As the organic solvent, the above ester organic solvents can be used.
The redispersion method is not particularly limited, and the redispersion method can be mixed and dispersed using a dispersing machine such as the paint shaker or the high-pressure homogenizer.
Further, it can be redispersed using an ultrasonic homogenizer or the like.
Examples of commercially available high-power ultrasonic homogenizers include SILENTSON UT-204 manufactured by Sharp Corporation, ultrasonic homogenizers US-300T manufactured by Nippon Seiki Seisakusho, US-1200T, RUS-1200T, MUS-1200T, An ultrasonic processor UIP series manufactured by Heelscher is listed. Using these ultrasonic irradiation apparatuses, it is possible to finely disperse preferably at a frequency of 25 kHz or less.
Examples of the ultrasonic irradiation method include a batch method in which stirring means such as an agitator, a magnetic stirrer, and a disper are used in combination, and a flow method in which the dispersion is sent at a constant flow rate in a chamber equipped with an ultrasonic irradiation unit. An ultrasonic homogenizer may be used in combination with the above-described paint shaker, high-pressure homogenizer, or the like.
High-quality pigment dispersion in which the amount of unadsorbed polymer in the organic pigment is reduced by re-dispersing the pre-mixture obtained by adding the organic solvent to the solid content obtained by centrifugation in this process by ultrasonic irradiation treatment etc. The liquid can be produced efficiently.

  The amount of the polymer that is not adsorbed to the organic pigment in the pigment dispersion obtained in this step is preferably 2% by weight or less, more preferably from the viewpoint of obtaining a pigment dispersion for a color filter having excellent storage stability and heat resistance. It is preferably 1.5% by weight or less, more preferably 1% by weight or less, and ideally no unadsorbed polymer is present.

[Step (2)]
In step (2), the pigment dispersion obtained in step (1), or the pigment dispersion obtained in the step of removing the unadsorbed graft polymer (A) on the organic pigment and a graft polymer containing a carboxy group This is a step of mixing (B).
Although there is no restriction | limiting in the method of mixing a graft polymer (B), The method of diluting with a solvent and adding is preferable. From the viewpoint of dispersion stability of the pigment dispersion during mixing, the concentration of the graft polymer (B) in the solution diluted with the solvent is preferably 20% by weight or less, and more preferably 10% by weight or less.
The weight ratio [graft polymer (B) / graft polymer (A)] of the graft polymer (B) to the graft polymer (A) used in this step is 0.20 / 1.0-1. 0 / 1.0 is preferable, and 0.25 / 1.0 to 0.6 / 1.0 is more preferable.

[Pigment dispersion for color filter]
The pigment dispersion for a color filter obtained by the production method of the present invention contains a graft polymer (A) containing a nitrogen atom, an organic pigment, an ester organic solvent, and a graft polymer (B) containing a carboxy group.
The proportion of the organic pigment in the pigment dispersion is preferably 3% by weight or more from the viewpoint of obtaining good colorability, preferably 3 to 30% by weight, and 5 to 20% from the viewpoint of obtaining good colorability and viscosity. % Is more preferable.
The weight ratio of the graft polymer (A) to the organic pigment in the pigment dispersion [graft polymer (A) / organic pigment] is preferably 0.4 to 1.2 from the viewpoint of storage stability of the pigment dispersion. .5 to 0.8 is more preferable.
The weight ratio of the graft polymer (B) to the organic pigment in the pigment dispersion [graft polymer (B) / organic pigment] is preferably 0.4 to 1.2 from the viewpoint of storage stability of the pigment dispersion. .5 to 0.8 is more preferable.
The weight ratio of graft polymer (B) to graft polymer (A) in the pigment dispersion [graft polymer (B) / graft polymer (A)] is 0.2 / 1.0 to 1. 0 / 1.0 is preferable, and 0.25 / 1.0 to 0.6 / 1.0 is more preferable.
The content of the ester organic solvent in the pigment dispersion is preferably 20 to 90% by weight and more preferably 40 to 80% by weight from the viewpoints of good colorability and low viscosity of the dispersion.

The volume median particle size (D50) of the organic pigment in the pigment dispersion is preferably 80 nm or less, more preferably 20 to 70 nm, and still more preferably 20 to 60 nm in order to obtain a good contrast as a color filter color material. .
The volume median particle size (D50) means a particle size at which the cumulative volume frequency calculated by the volume fraction becomes 50% by accumulation from the small particle size side. The volume median particle size (D50) was determined by diluting the pigment dispersion immediately after production with propylene glycol monomethyl ether acetate (PGMEA) 300 times, and using a particle size analyzer (ZETASIZER Nano-ZS, manufactured by Sysmex Corporation). As the measurement conditions, for example, in the case of a diketopyrrolopyrrole pigment, pigment particle refractive index: 1.51, pigment density: 1.45 g / cm ³ , PGMEA refractive index: 1.400, PGMEA viscosity: 1.3 cps are input. And it can measure at 20 degreeC.
The viscosity (20 ° C.) at a solid content of 12% by weight of the pigment dispersion obtained by the production method of the present invention is preferably 1 to 200 mPa · s, and preferably 1 to 100 mPa · s in order to obtain a favorable viscosity as a color material for a color filter. -S is more preferable.
From the viewpoint of dispersion stability, the acid value of the whole polymer including the graft polymer (A) and the graft polymer (B) is preferably 10 to 80 mgKOH / g, more preferably 15 to 75 mgKOH / g, and 20 to 70 mgKOH / g. Is more preferable.

[Coloring composition for color filter]
The coloring composition for a color filter of the present invention contains the pigment dispersion for a color filter obtained by the above production method, but includes a graft polymer (A) containing a nitrogen atom, an organic pigment, an ester organic solvent, and a carboxy. In addition to the graft polymer (B) containing a group, a binder component or the like can be contained.
Examples of the binder component include a binder component containing an ionizing radiation curable component.
The binder component containing an ionizing radiation curable component contains an alkali-soluble resin, a polyfunctional monomer, a photopolymerization initiator activated by ionizing radiation, and further a polyfunctional oligomer, a monofunctional monomer, a sensitizer, etc. Can be blended. These resins, oligomers, monomers, additives and the like can be used alone or in combination of two or more.
The content of the binder component in the colored composition comprising the ionizing radiation curable component is preferably 20 to 80% by weight in the effective component excluding the solvent, and the content of the photopolymerization initiator is in the effective component excluding the solvent. 0.2 to 20% by weight is preferred.

As the alkali-soluble resin, those generally used for negative resists can be used, and those having solubility in an alkaline aqueous solution (0.05% by weight in a tetramethylammonium hydroxide aqueous solution at 1% by weight or more at 20 ° C. It is not particularly limited as long as it dissolves. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, n-decyl (meth) acrylate, benzyl ( One or more selected from (meth) acrylate, styrene, γ-methylstyrene, N-vinyl-2-pyrrolidone, glycidyl (meth) acrylate, and the like, (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, Fumaric acid, vinyl vinegar , A copolymer consisting of one or more selected from among these anhydrides can be exemplified, polymers obtained by adding an ethylenically unsaturated compound having a glycidyl group or hydroxyl group of the above copolymer, etc. may be exemplified. Among these, a polymer having an ethylenically unsaturated bond obtained by adding an ethylenically unsaturated compound having a glycidyl group or a hydroxyl group to a copolymer is polymerized with a polyfunctional monomer described later at the time of exposure. This is particularly suitable in that the colored layer becomes more stable.
The weight average molecular weight of the alkali-soluble resin is preferably 5,000 to 50,000.
The alkali-soluble resin used in the present invention is preferably a copolymer of (meth) acrylic acid ester and (meth) acrylic acid, more preferably a copolymer of benzyl (meth) acrylate and (meth) acrylic acid. preferable.
The copolymerization ratio (molar ratio) of acrylic acid ester and (meth) acrylic acid is preferably 90/10 to 50/50, and more preferably 80/20 to 70/30.

As polyfunctional monomers, (meth) acrylic acid esters (for example, dipentaerythritol hexaacrylate) having two or more ethylenically unsaturated double bonds, urethane (meth) acrylates, (meth) acrylic acid amides, allyl compounds And vinyl esters. The content of the polyfunctional monomer in the pigment dispersion of the present invention is preferably 10 to 60% by weight in the effective component excluding the solvent.
Examples of the photopolymerization initiator include aromatic ketones, lophine dimers, benzoin, benzoin ethers, polyhalogens and the like. For example, a combination of 4,4′-bis (diethylamino) benzophenone and 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 4- [pN, N-di (ethoxycarbonylmethyl) -2, 6-di (trichloromethyl) -s-triazine], 2-methyl-4 ′-(methylthio) -2-morpholinopropiophenone is preferred.

In the following production examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified. The measurement and evaluation of the molecular weight, non-volatile content, epoxy value, acid value, viscosity of the pigment dispersion, storage stability, developability of the cured film, substrate adhesion, and contrast ratio were performed by the following methods. .
(1) Measurement of number average molecular weight and weight average molecular weight of graft polymer, etc. Eluent obtained by dissolving phosphoric acid and lithium bromide in N, N-dimethylformamide so as to have concentrations of 60 mmol / L and 50 mmol / L, respectively. As a standard substance, the gel chromatography method [Tosoh Corporation GPC apparatus (HLC-8120GPC), Tosoh Corporation column (TSK-GEL, α-M × 2), flow rate: 1 mL / min] And measured.
(2) Measurement of non-volatile content of graft polymer Weigh 10 parts of glass rod and dry anhydrous sodium sulfate in a petri dish, add 2 parts of polymer solution (sample amount) to it, mix with glass rod, and dry at 105 ° C under reduced pressure. (Pressure 8 kPa) for 2 hours. The weight after drying was measured, and the non-volatile content was calculated from the following formula.
Nonvolatile content = [[sample amount− (weight after drying− (petri dish + glass rod + weight of anhydrous sodium sulfate)]] / sample amount] × 100
(3) Graft polymer (A) Measurement of epoxy value at the time of production This refers to a value obtained by adding hydrochloric acid to a polymer solution and expressing the amount consumed by chlorohydrin in mg of potassium hydroxide.
(4) Measurement of acid value of graft polymer It was measured according to JIS K0070.

(5) Measurement of viscosity of pigment dispersion After holding 2 mL of a dispersion adjusted to a pigment concentration of 10% at 20 ° C. for 5 minutes, using an E-type viscometer (rotor No. 2, 20 rpm, 20 ° C.), The viscosity of the pigment dispersion was measured.
(6) Storage stability of pigment dispersion The pigment dispersion obtained in Examples and Comparative Examples was filled in a glass sealed container, and the dispersion viscosity after storage at 40 ° C for 7 days was measured with an E-type viscometer (Toki The viscosity was measured at 25 ° C. using Sangyo Co., Ltd. (RE80L). The smaller the absolute value of the change rate, the better the storage stability.
Viscosity change rate (%) = (([viscosity after storage] − [viscosity before storage]) / [viscosity before storage]) × 100

(7) Evaluation of contrast (measurement of contrast ratio of cured film)
1.00 part of pigment dispersion adjusted to a pigment concentration of 10%, methacrylic acid / benzyl methacrylate copolymer (binder, molar ratio: 30/70, weight average molecular weight: 14000, solid content of 40% by weight of propylene glycol monomethyl ether Acetate (hereinafter referred to as “PGMEA” solution) 0.15 parts, dipentaerythritol hexaacrylate (polyfunctional monomer: Nippon Kayaku Co., Ltd., DPHA) 0.046 parts, 2-methyl-4 ′-(methylthio) 0.035 parts of -2-morpholinopropiophenone (photopolymerization initiator: Wako Pure Chemical Industries, Ltd.) and 0.474 parts of PGMEA were mixed until uniform to obtain a colored composition. The pigment dispersion composition was coated on a glass substrate with a spin coater, then allowed to stand for 6 minutes on a horizontal table, and dried on a hot plate at 80 ° C. for 3 minutes. Next, the obtained coating film was irradiated with ultraviolet rays up to 30 mJ / cm ² using an ultraviolet fiber spot irradiation device (MUV-202U, manufactured by Moritex Co., Ltd.) to obtain a cured film. The contrast ratio of the cured film was measured with a contrast ratio measuring instrument (CT-1 manufactured by Aisaka Electric Co., Ltd.).
The larger the contrast ratio value, the better the contrast.

(8) Evaluation of developability of cured film The coloring composition prepared for the contrast measurement of (7) above was applied on a glass substrate with a spin coater, and then allowed to stand for 6 minutes on a horizontal table, and 3 at 80 ° C. Dry on a hot plate for minutes. Next, a photomask was placed on the obtained coating film, and ultraviolet rays were irradiated up to 30 mJ / cm ² using an ultraviolet fiber spot irradiation device (MUV-202U, manufactured by Moritex Co., Ltd.) to obtain a cured film substrate.
Next, this cured film substrate was slowly swung in a 0.1% aqueous solution of tetramethylammonium hydroxide, pulled up from the aqueous solution every 30 seconds, and then rinsed with a water shower to remove uncured portions. The development time was defined as the immersion time of an aqueous tetramethylammonium hydroxide solution that provides the earliest exposure pattern. The shorter the development time, the better the developability.
(9) Evaluation of substrate adhesion The formability of the pattern of the cured film substrate obtained in (8) above was visually observed, and the substrate adhesion was evaluated according to the following criteria.
AA: A complete pattern is formed, and there is no disturbance at the end of the pattern.
A: A complete pattern is formed, but disorder is observed at the end of the pattern.
B: A part of the pattern is formed, but a part is missing.
C: Almost the entire pattern is missing.
The better the pattern formability, the better the substrate adhesion.

Production Example 1 [Synthesis of Graft Polymer (A-1) Containing Nitrogen Atom]
Production Example 1-1 [Synthesis of poly (glycidyl methacrylate / 2-hydroxyethyl methacrylate / N-vinylpyrrolidone) (poly (GMA-HEMA-VP)) (a1 component)]
15. N-vinyl-2-pyrrolidone (hereinafter referred to as “VP”) 100 g, glycidyl methacrylate (hereinafter referred to as “GMA”) in a separable flask equipped with a reflux condenser, a thermometer, a nitrogen inlet tube, and a stirring device. 2 g, 2-hydroxyethyl methacrylate (hereinafter referred to as “HEMA”) 24.0 g, mercaptoethanol (hereinafter referred to as “ME”) 3.0 g, and ethanol 178.0 g were charged, and nitrogen substitution was performed. While stirring at 77 ° C., 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., azo polymerization initiator, trade name: V-65. Hereinafter, “V-65” The solution which melt | dissolved 3.9g in ethanol 41.8g was added.
While stirring at 77 ° C., a solution in which 150.0 g of VP, 76.2 g of GMA, 120.2 g of HEMA, 6.4 g of the polymerization initiator, 445.3 g of ethanol, and 6.8 g of ME were added dropwise over 90 minutes. .
After completion of the dropwise addition, a solution prepared by mixing 60.9 g of GMA, 96.1 g of HEMA, 12.0 g of V-65, 167 g of ethanol, and 3.1 g of ME was added dropwise over 3 hours. After further stirring at 77 ° C. for 1 hour, 0.6 g of V-65 and 15.0 g of ethanol were added. After further stirring at 77 ° C. for 1 hour, 0.6 g of V-65 and 15.0 g of ethanol were added. The mixture was further stirred for 1 hour and then cooled to obtain an ethanol solution of poly (GMA-HEMA-VP).
The solid content of the solution was 40.5%, and the number average molecular weight of poly (GMA-HEMA-VP) was 3,900, the weight average molecular weight was 10,500, and the epoxy value was 84 mgKOH / g.

(2) Synthesis of single-terminal carboxylic acid type polybenzyl methacrylate (a2 component) 100 g of benzyl methacrylate and 3-mercaptopropionic acid were attached to a separable flask equipped with a reflux condenser, thermometer, nitrogen gas inlet tube and stirring device. (Chain transfer agent) 4.0 g and propylene glycol monomethyl ether acetate (hereinafter referred to as “PGMEA”) 50 g were charged, purged with nitrogen, and then stirred at 80 ° C., while stirring at 80 ° C., 400 g of benzyl methacrylate, 3-mercaptopropionic acid 16. 0 g, 200 g of PGMEA, and 4 g of V-65 were added dropwise over 3 hours. Further, after stirring at 80 ° C. for 1 hour, 4 g of V-65, 1.8 g of 3-mercaptopropionic acid, and 150 g of PGMEA were added. Furthermore, after stirring at 80 degreeC for 2 hours, it cooled, and the PGMEA solution of terminal carboxylic acid type polybenzyl methacrylate was obtained.
The solid content of the solution was 57.0%, the acid value of the obtained terminal carboxylic acid type polybenzyl methacrylate was 31.6 mgKOH / g, the number average molecular weight was 2400, and the weight average molecular weight was 4600.

(3) Production of Graft Polymer (A-1) by Coupling Reaction of Epoxy Group and Carboxylic Acid Obtained in Production Example 1 (1) on a separable flask equipped with a reflux condenser, a thermometer, and a stirrer ( a1) 100 g of solution (solid content 40.5 g), 196.4 g of solution (a2) obtained in (2) above (solid content 111.9 g), PGMEA 87 g, ethanol 87 g, tetrabutylammonium bromide (TBAB) (catalyst) 4.0 g was charged and stirred at 90 ° C. for 15 hours. As a result of measuring the acid value, the reaction rate was 96%. After cooling, ethanol was removed by an evaporator (bath temperature 63 ° C., pressure 92 kPa) to obtain a PGMEA solution of poly (HEMA-VP-g-MMA).
The solid content of the solution was 29%, and the resulting poly (HEMA-VP-g-MMA) had a number average molecular weight of 6300 and a weight average molecular weight of 28,000.

Production Example 2 [Synthesis of Graft Polymer (A-2) Containing Nitrogen Atom]
(1) Synthesis of single-terminal carboxylic acid type polymethyl methacrylate (a3 component) 100 g of methyl methacrylate and 3-mercaptopropionic acid were attached to a separable flask equipped with a reflux condenser, thermometer, nitrogen gas inlet tube and stirring device. (Chain transfer agent) 7.1 g and 50 g of PGMEA were charged, and after nitrogen substitution, while stirring at 80 ° C., 400 g of methyl methacrylate, 28.4 g of 3-mercaptopropionic acid, 200 g of PGMEA, and 4 g of V-65 were taken over 3 hours. And dripped. Further, after stirring at 80 ° C. for 1 hour, 4 g of V-65, 1.8 g of 3-mercaptopropionic acid, and 200 g of PGMEA were added. Furthermore, after stirring at 80 degreeC for 2 hours, it cooled and obtained the PGMEA solution of terminal carboxylic acid type polymethyl methacrylate.
The solid content of the solution was 57.0%, the acid value of the obtained terminal carboxylic acid type polymethyl methacrylate (a3) was 18 mgKOH / g, the number average molecular weight was 1600, and the weight average molecular weight was 3400. .

(2) Production of Graft Polymer (A-2) by Coupling Reaction of Epoxy Group and Carboxylic Acid Obtained in Production Example 1 (1) on a separable flask equipped with a reflux condenser, thermometer, and stirring device ( a1) Solution 100 g (solid content 40.5 g), (a3) solution 131.9 g (solid content 75.2 g) obtained in (1), PGMEA 53.7 g, ethanol 53.7 g, tetrabutylammonium bromide (TBAB) (Catalyst) 3.6 g was charged and stirred at 90 ° C. for 15 hours. As a result of measuring the acid value, the reaction rate was 96%. After cooling, ethanol was removed by an evaporator (bath temperature 63 ° C., pressure 92 kPa) to obtain a PGMEA solution of poly (HEMA-VP-g-MMA).
The solid content of the solution was 29%, and the resulting poly (HEMA-VP-g-MMA) had a number average molecular weight of 5800 and a weight average molecular weight of 28,000.

Production Example 3 [Synthesis of Graft Polymer (B-1) Containing Carboxy Group]
(1) Synthesis of a macromonomer having an unsaturated bond at one end (b1)
In a separable flask equipped with a reflux condenser, a thermometer, an air introduction tube and a stirring device,
A polymethyl methacrylate (a3) solution having a carboxyl group at one end (a3) 100 g (solid content 57 g), GMA 5.6 g, TBAB 1.7 g, methoxyphenol 0.17 g and PGMEA 2 g were charged, stirred at 90 ° C. for 6 hours and then cooled. A macromonomer (b1) PGMEA solution was obtained. As a result of measuring the acid value, the reaction rate was 96%.
The solid content of the solution was 60.5%, and the number average molecular weight of the obtained macromonomer (b1) was 1700, and the weight average molecular weight was 3,500.
(2) Synthesis of Graft Polymer (B-1) A separable flask equipped with a reflux condenser, a thermometer, a nitrogen gas introduction tube, and a stirrer was charged with 100 g of acrylic acid (hereinafter referred to as “AA”) and a macromonomer (b1). ) After adding 233 g of solution (solid content: 141 g), PGMEA 350 g, and ethanol 150, and purging with nitrogen, and stirring at 80 ° C., a mixed solution of PGMEA 67 g, V-65 7 g, and ME 1 g was added, and then AA 900 g, macromonomer (b1 ) A mixed solution of 2100 g of solution (solid content 1270.5 g), 3150 g of PGMEA, 1350 g of ethanol, 60 g of V-65, and 12 g of ME was added dropwise over 3 hours. Furthermore, V-65 3g and PGMEA 67g were added, and it stirred at 80 degreeC for 1 hour. After completion of the reaction, ethanol was removed to obtain a PGMEA solution of graft polymer (B-1).
The solid content of the solution was 35.1%, and the acid value of the graft polymer (B-1) was 125 mgKOH / g.

Production Example 4 [Synthesis of Graft Polymer (B-2) Containing Carboxy Group]
(1) Synthesis of a macromonomer having an unsaturated bond at one end (b2)
In a separable flask equipped with a reflux condenser, a thermometer, an air introduction tube and a stirring device,
100 g of a polybenzyl methacrylate (a2) solution having a carboxyl group at one end, 5.6 g of GMA, 1.7 g of TBAB, 0.17 g of methoxyphenol, and 2 g of PGMEA were charged, stirred at 90 ° C. for 6 hours, cooled, and then a macromonomer (b2 ) PGMEA solution was obtained. As a result of measuring the acid value, the reaction rate was 96%.
The solid content of the solution was 60.5%, and the obtained macromonomer (b2) had a number average molecular weight of 2500 and a weight average molecular weight of 4700.
(2) Synthesis of graft polymer (B-2) AA 100 g, macromonomer (b2) solution obtained in (1) above, in a separable flask equipped with a reflux condenser, a thermometer, a nitrogen gas inlet tube and a stirrer 250 g (solid content 151.3 g), PGMEA 350 g, and ethanol 150 g were charged. After purging with nitrogen, a mixed solution of PGMEA 67 g, V-65 7 g, and ME 1 g was added with stirring at 80 ° C., then AA 900 g, macromonomer (b2 ) A mixed solution of 2250 g of solution (solid content 1361 g), PGMEA 3150 g, ethanol 1350 g, V-65 60 g, and ME 12 g was added dropwise over 3 hours. Further, 3 g of V-65 and 134 g of PGMEA were added and stirred at 80 ° C. for 1 hour. After completion of the reaction, ethanol was removed to obtain a PGMEA solution of graft polymer (B-1).
The solid content of the solution was 35.8%, and the acid value of the graft polymer (B-1) was 122 mgKOH / g.

Production Example 5 [Synthesis of Polymer (C) (Random Polymer)]
A separable flask equipped with a reflux condenser, a thermometer, a nitrogen gas inlet tube and a stirrer was charged with 10 g of PGMEA, purged with nitrogen, and then stirred at 75 ° C., while AA 17.3 g, BzMA 82.7 g, PGMEA 100 g, V- The liquid which mixed 65 2.0g and ME0.3g was dripped in 3 hours. Further, 0.2 g of V-65 and 75 g of PGMEA were added and stirred at 80 ° C. for 1 hour, and then cooled to obtain a PGMEA solution of poly (AA-BzMA) random polymer.
The solid content of the solution was 35.6%, the number average molecular weight of the polymer (C) was 18000, and the weight average molecular weight was 38000.

Example 1 (Preparation of pigment dispersion (1))
93 g of PGMEA, 42 g of the graft polymer (A-1) solution obtained in Production Example 1 (effective amount: 12.2 g), diketopyrrolopyrrole pigment (manufactured by Ciba Specialty Chemicals, Inc., CI Pigment Red 254) , 15.0 g of trade name “IRGAPHOR BK-CF”, average primary particle size 30 nm (catalog value), and 300 g of 0.3 mmφ zirconia beads were placed in a 500 ml plastic container and stirred for 3 hours in a paint shaker. The beads were removed to obtain a preliminary dispersion.
Next, 100 g of this preliminary dispersion and 200 g of 0.05φ zirconia beads were placed in a 250 ml plastic container, stirred for 24 hours with a paint shaker to remove the zirconia beads, and a pigment dispersion was obtained. (Process (1))
40 g of the pigment dispersion obtained in the step (1) was diluted with 80 g of PGMEA, and centrifuged for 12 hours under the conditions of 26323 G using a centrifuge (manufactured by Hitachi Koki Co., Ltd., himac CP56G). After discarding, 9 g of sediment was obtained.
31 g of PGMEA was added to 9 g of the obtained sediment, and redispersion treatment was performed by ultrasonic irradiation using an ultrasonic cleaner (manufactured by Sharp Corporation, SILENTSONIC UT-204) to obtain a pigment dispersion. (Step of removing unadsorbed graft polymer (A))
While stirring 20 g of the pigment dispersion, 2.8 g of the graft polymer (B-1) solution was added and further mixed with the ultrasonic cleaner to obtain a pigment dispersion (1). (Process (2))
The acid value of the whole polymer present in the pigment dispersion (1) was 60 mgKOH / g. Table 1 shows the evaluation results of the obtained pigment dispersion (1) and the evaluation results of the coloring composition containing the pigment dispersion (1) (see the preparation example of [0055]).

Example 2 and Comparative Examples 1 to 3 (Preparation of pigment dispersions (2) to (5))
In Example 1, instead of the graft polymer (A-1) and the graft polymer (B-1), the graft polymer shown in Table 1 was used. In Example 2, 2.9 g of a polymer (B-2) solution (solid) In Comparative Example 2, 5 g of (B-1) solution (solid content 1.8 g) was added, and in Comparative Example 3, (C) solution (solid content 1.76 g) was added 5.0 g. did. Other than that was carried out similarly to Example 1, and obtained pigment dispersion (2)-(5). In Comparative Example 1, step (2) was not performed.
Table 1 shows the evaluation results of the obtained pigment dispersions (2) to (5) and the evaluation results of the coloring composition containing them.

Comparative Example 4
86.8 g of PGMEA, 26.9 g of the graft polymer (A-1) solution obtained in Production Example 1, 21.3 g of the graft polymer (B-1) solution obtained in Production Example 3 (solid content 7.65 g), 15.0 g of ketopyrrolopyrrole pigment (IRGAPHOR BK-CF) and 300 g of 0.3 mmφ zirconia beads are placed in a 500 ml plastic container and stirred for 3 hours in a paint shaker. Then, the zirconia beads are removed to prepare a preliminary dispersion. Obtained.
Next, 100 g of this preliminary dispersion and 200 g of 0.05φ zirconia beads were placed in a 250 ml plastic container, stirred for 24 hours with a paint shaker to remove the zirconia beads, and a pigment dispersion was obtained. (Process (1))
Using this dispersion, a step of removing the unadsorbed graft polymer (A) was carried out in the same manner as in Example 1, and a pigment dispersion (6) was obtained without carrying out step (2).
Table 1 shows the evaluation results of the obtained pigment dispersion (6) and the evaluation results of the coloring composition containing the pigment dispersion (6).

  From Table 1, the pigment dispersions of Examples 1 and 2 are superior in storage stability to the pigment dispersions of Comparative Examples 1 and 2, and the coloring composition containing the pigment dispersion has developability and substrate adhesion. It turns out that it is excellent in.

Claims (9)

The manufacturing method of the pigment dispersion for color filters which has the following process (1) and (2).
Step (1): Graft polymer (A) containing a nitrogen atom and an organic pigment are dispersed in an ester organic solvent to obtain a pigment dispersion Step (2): Pigment dispersion obtained in step (1) Step of mixing liquid and carboxy group-containing graft polymer (B) However, both side chains of graft polymer (A) and (B) contain structural units derived from (meth) acrylic acid esters, The absolute value of the difference in Sp value (solubility parameter) of the side chain is 0.5 to 2.5.   The method for producing a pigment dispersion for a color filter according to claim 1, wherein the nitrogen atom of the graft polymer (A) is derived from an amide group.   The method for producing a pigment dispersion for a color filter according to claim 1 or 2, wherein the graft polymer (A) has a hydroxyl group.   The manufacturing method of the pigment dispersion for color filters in any one of Claims 1-3 in which the side chain of a graft polymer (A) contains the structural unit derived from benzyl (meth) acrylate.   One side chain of the graft polymer (A) or (B) contains a structural unit derived from benzyl (meth) acrylate, and the other side chain contains a structural unit derived from alkyl (meth) acrylate. Item 5. A method for producing a pigment dispersion for a color filter according to any one of Items 1 to 4.   The method for producing a pigment dispersion for a color filter according to any one of claims 1 to 5, wherein the organic pigment is a diketopyrrolopyrrole pigment.   The pigment dispersion for a color filter according to any one of claims 1 to 6, further comprising a step of removing the graft polymer (A) not adsorbed to the pigment after the step (1) and before the step (2). Production method.   The method for producing a pigment dispersion for a color filter according to any one of claims 1 to 7, wherein the acid value of the whole polymer is from 10 to 80 KOHmg / g.   The coloring composition for color filters containing the pigment dispersion obtained by the method in any one of Claims 1-8.