JP5154808B2 - Organic pigment nanoparticle dispersion and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic pigment nanoparticle dispersion which excels in dispersibility and dispersion stability when organic nanoparticles are dispersed with a small amount of a dispersion auxiliary and at a high concentration in an aqueous medium, and furthermore is hard to agglomerate even at a high salt concentration, and its manufacturing method. <P>SOLUTION: The organic pigment nanoparticle dispersion contains at least one polymeric compound having a quaternary ammonium moiety. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an organic pigment nanoparticle dispersion and a method for producing the same, and more specifically, the present invention relates to dispersibility when the organic nanopigment is dispersed at a high concentration in an aqueous solvent with a small amount of a dispersion aid. The present invention also relates to an organic pigment nanoparticle dispersion that is excellent in dispersion stability and hardly aggregates even at a high salt concentration, and a method for producing the same.

  In recent years, efforts have been made to reduce the size of particles. In particular, research is being conducted to reduce the size to nanometer size (for example, in the range of 10 to 100 nm), which is difficult to produce by a pulverization method, a precipitation method, or the like.

  The size of such nanometer-sized fine particles is located in the middle of larger bulk particles, smaller molecules and atoms, and is an unprecedented size region, which can bring out new characteristics that could not be anticipated. It has been pointed out. The potential of such nanoparticles is expected in various fields, and research is being actively conducted in a wide range of fields such as biochemistry, new materials, electronic devices, light-emitting display devices, printing, and medicine.

  In particular, organic nanoparticles made of an organic compound have a high potential as a functional material because the organic compound itself has diversity. For example, polyimide is used in many fields because it is a chemically and mechanically stable material such as heat resistance, solvent resistance, and mechanical properties and has excellent electrical insulation. Then, polyimide is finely divided, and the characteristics and shape of polyimide are combined to be used in a wider field. For example, it has been proposed to use finely divided polyimide as an additive for powder toner for image formation (see, for example, Patent Document 1).

  Further, regarding organic pigments among organic nanoparticles, examples thereof include paints, printing inks, electrophotographic toners, inkjet inks, and color filters. Now it occupies an important position in life. Among them, high performance is required, and pigments for inkjet ink and pigments for color filters are particularly important in practical use.

  Conventionally, dyes have been used for ink-jet ink coloring materials. However, there are problems in terms of water resistance and light resistance, and pigments have been used to improve such problems. An image obtained with the pigment ink has an advantage of being excellent in water resistance and light resistance as compared with an image obtained with a dye ink. However, it is difficult to make a nanometer size that can penetrate into the voids on the paper surface, and the adhesion to paper is poor.

  In addition, with the increase in the number of pixels in a digital camera, it is desired to reduce the thickness of color filters used for optical elements such as CCD sensors and display elements. An organic pigment is used for the color filter. However, since the thickness of the filter greatly depends on the particle diameter of the organic pigment, it is desired to produce nanometer-sized stable fine particles.

  Regarding the method for producing organic particles, a gas phase method (a method in which a sample is sublimated in an inert gas atmosphere and the particles are collected on a substrate), a liquid phase method (for example, a sample dissolved in a good solvent under stirring conditions and temperature). A reprecipitation method in which fine particles are obtained by injecting into a poor solvent with controlled slag has been studied. In addition, an example of producing a desired size by these methods has been reported. Among these, the liquid phase method has attracted attention as a method for producing organic particles having excellent simplicity and productivity (see, for example, Patent Documents 2 to 4).

In the preparation of nanoparticles in the liquid phase method, a low molecular surfactant or a neutral water-soluble nonionic polymer compound is used in order to prevent aggregation of the nanoparticles. Therefore, even if the nanoparticles can be dispersed at a high concentration, there is a disadvantage that a large amount of the dispersion aid to be used is necessary. When the viscosity is low and the content of the polymer compound is extremely low as in the ink jet, those It is difficult to apply the technology as it is. In addition, for the requirement of phase conversion to a solvent system after preparing aqueous nanoparticles, an aqueous slurry or aqueous paste containing a high concentration of pigment is prepared, a resin or resin solution is added, mixed and stirred, and the pigment There is known a flushing method in which water around the resin is replaced with a resin or a resin solution. However, this method has a problem that the aqueous particles once go through a strongly aggregated form, so that the efficiency of coating with the resin is deteriorated and redispersion becomes difficult. Further, when a nonionic polymer compound is used, it is easily affected by the salt concentration, and when an aqueous paste is prepared by salting out, strong secondary aggregation occurs between particles. A low molecular weight anionic or cationic surfactant can also be used as a dispersant, but there is a problem of insufficient dispersion stability due to the low molecular weight. Therefore, a method of phase conversion to an ionic liquid without aggregating aqueous particles with a cationic polymer compound has also been attempted, but it is limited to low-concentration inorganic particles, and no mention is made of organic pigments (for example, (See Non-Patent Document 1.)
JP-A-11-237760 JP-A-6-79168 JP 2004-91560 A JP 2003-113341 A “Small”, 2006, Vol.2, No.7, p.879-883

  The present invention has been made in view of the above problems, and the object thereof is excellent in dispersibility and dispersion stability when the organic nano pigment is dispersed in a high concentration in an aqueous solvent with a small amount of a dispersion aid. An organic pigment nanoparticle dispersion that hardly aggregates even when the salt concentration is high, and a method for producing the same.

  As a result of intensive studies, the present inventor has used a specific cationic polymer compound as a dispersion aid to disperse the organic nano pigment in a small amount and in a high concentration in an aqueous solvent. It was also found that an organic pigment dispersion composition which is excellent in dispersion stability and hardly aggregates even when the salt concentration is high can be obtained. The present invention has been made based on such findings.

[1] An organic pigment nanoparticle dispersion containing organic pigment particles and at least one polymer compound having a quaternary ammonium moiety,
  The organic pigment is at least one selected from diketopyrrolopyrrole pigments, quinacridone pigments, phthalocyanine pigments, azo pigments, perylene pigments, anthraquinone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments,
  Organic pigment nanoparticles in which the polymer compound having a quaternary ammonium moiety comprises only a cationic repeating unit represented by the following general formula (1) or contains 0.1 to 0.7% by mass of a copolymer component Dispersion.

(Wherein R ₁ ~ R _Three Each independently represents an alkyl group, an aralkyl group, or an aryl group. R ₁ , R ₂ , R _Three Any two of these may be connected to each other, and may further form a 4- to 6-membered heterocyclic ring containing an oxygen atom, a nitrogen atom, and / or a sulfur atom. X represents a halogen atom or an organic or inorganic anion. n represents a natural number of 1 to 5. A represents a hydrogen atom or an alkyl group. L is a single bond or a divalent linking group, or R ₁ , R ₂ , R _Three Represents a tetravalent linking group bonded to any two of the above. At this time, the divalent linking group forming L is a linking group containing an aryl group or an aralkyl group. In addition, the tetravalent linking group forming L forms a heterocyclic group with the ammonium salt moiety in the general formula (1). )
[2] The organic pigment nanostructure according to [1], wherein the polymer compound having a quaternary ammonium moiety is a polymer compound having a cationic repeating unit represented by the following general formula (2): Particle dispersion.

(Wherein R ₁ ~ R _Three Each independently represents an alkyl group, an aralkyl group, or an aryl group. R ₁ , R ₂ , R _Three Any two of these may be connected to each other, and may further form a 4- to 6-membered heterocyclic ring containing an oxygen atom, a nitrogen atom, and / or a sulfur atom. X represents a halogen atom or an organic or inorganic anion. n represents a natural number of 1 to 5. )
[3] R ₁ ~ R ₃ The organic pigment nanoparticle dispersion according to [1] or [2], wherein the heterocyclic ring is an imidazolium ring, a pyridinium ring, an oxazolium ring, a thiazolium ring, an imidazolinium ring, an oxazolinium ring, or a thiazolinium ring.
[4] The organic pigment nanoparticle dispersion according to any one of [1] to [3], wherein the organic pigment is nanoparticles having an average particle diameter in the range of 10 to 100 nm.
[5] The organic pigment nanoparticle dispersion according to any one of [1] to [4], wherein the organic pigment has a dissociable group.
[6] The organic pigment nanoparticle dispersion according to any one of [1] to [5], wherein the polymer compound is contained in an amount of 10% by mass to 1000% by mass with respect to the organic pigment.
[7] Any one of [1] to [6], wherein the copolymerization component is a component derived from a compound selected from vinylpyrrolidone, styrene, naphthalene, styrylmethyl chloride, vinylimidazole, vinylpyridine, acrylamide, and vinylamide. The organic pigment nanoparticle dispersion according to Item.
[8] The organic pigment nanoparticle dispersion according to any one of [1] to [7], wherein the molecular weight of the polymer compound is 1,000 to 200,000 in terms of number average molecular weight.
[9] Organic pigment nanoparticle dispersion in which a solution in which an organic pigment and a polymer compound having a quaternary ammonium moiety are dissolved in an alkaline polar organic solvent is poured into the organic pigment insoluble solvent to crystallize the organic pigment nanoparticles A manufacturing method of
  The organic pigment is at least one selected from diketopyrrolopyrrole pigments, quinacridone pigments, phthalocyanine pigments, azo pigments, perylene pigments, anthraquinone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments,
  The method for producing an organic pigment nanoparticle dispersion, wherein the polymer compound having a quaternary ammonium moiety is a polymer compound having a cationic repeating unit represented by the following general formula (1).

(Wherein R ₁ ~ R _Three Each independently represents an alkyl group, an aralkyl group, or an aryl group. R ₁ , R ₂ , R _Three Any two of these may be connected to each other, and may further form a 4- to 6-membered heterocyclic ring containing an oxygen atom, a nitrogen atom, and / or a sulfur atom. X represents a halogen atom or an organic or inorganic anion. n represents a natural number of 1 to 5. A represents a hydrogen atom or an alkyl group. L is a single bond or a divalent linking group, or R ₁ , R ₂ , R _Three Represents a tetravalent linking group bonded to any two of the above. At this time, the divalent linking group forming L is a linking group containing an aryl group or an aralkyl group. In addition, the tetravalent linking group forming L forms a heterocyclic group with the ammonium salt moiety in the general formula (1). )
[10] The method for producing an organic pigment nanoparticle dispersion according to [9], wherein the polymer compound having a quaternary ammonium moiety is represented by the following general formula (2).

(Wherein R ₁ ~ R _Three Each independently represents an alkyl group, an aralkyl group, or an aryl group. R ₁ , R ₂ , R _Three Any two of these may be connected to each other, and may further form a 4- to 6-membered heterocyclic ring containing an oxygen atom, a nitrogen atom, and / or a sulfur atom. X represents a halogen atom or an organic or inorganic anion. n represents a natural number of 1 to 5. )
[11] The method for producing an organic pigment nanoparticle dispersion according to [9] or [10], wherein at least 90% by mass of the composition of the organic pigment insoluble solvent is water.

  The organic pigment nanoparticle dispersion of the present invention is excellent in dispersibility and dispersion stability when the organic nanopigment is dispersed in a small amount in an aqueous solvent at a high concentration, and hardly aggregates even when the salt concentration is high.

Hereinafter, the present invention will be described in detail.
The organic pigment nanoparticle dispersion of the present invention is not particularly limited except that the pigment is dispersed using a polymer compound having a quaternary ammonium moiety as a dispersion aid. It can be achieved by appropriately selecting, for example, mixing and crystallizing a solution in which the polymer compound is dissolved and the organic pigment insoluble medium, and using at least 90% by mass of the organic pigment insoluble medium as water. .
In the following, a solution in which an organic pigment and a polymer compound having a quaternary ammonium moiety are dissolved in an alkaline polar organic solvent is poured into an organic pigment insoluble solvent to crystallize organic pigment nanoparticles, and the organic of the present invention A method for producing a pigment nanoparticle dispersion will be described.

  In the present invention, preferably, in a reaction vessel, a pigment and a polymer compound are dissolved in an alkaline aprotic polar solvent, and pigment particles are crystallized in a pigment insoluble medium to obtain a pigment dispersion. The temperature at which the dissolved pigment solution is added to the pigment-insoluble medium is not particularly limited, but is preferably in the range of 0 ° C to 80 ° C, more preferably 0 ° C to 60 ° C. If it is less than 0 ° C., water in the hydrophilic medium may freeze, and if it exceeds 80 ° C., the growth of the pigment particles becomes remarkably fast and the desired particle size cannot be obtained.

The pigment according to the present invention will be described. The pigment used in the present invention refers to an organic pigment having a color, such as a diketopyrrolopyrrole pigment, a quinacridone pigment, a phthalocyanine pigment, an azo pigment, a perylene pigment, an anthraquinone pigment, a dioxazine pigment, a thioindigo pigment, and an isoindolinone pigment. And organic pigments selected from quinophthalone pigments.

The pigment used in the present invention preferably has a dissociable group. The pigment may have a dissociable group in the pigment mother nucleus or may have a substituent.
Specifically, the dissociable group preferably has at least one group selected from the group consisting of —NH—, —NHCO—, —SO ₃ H, —PO ₃ H and —COOH, more preferably , -NH-, -NHCO- or -COOH, more preferably -NH- or -NHCO-.

  Specific organic pigments are exemplified below. Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 222, C.I. I. And CI Pigment Red 254.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 138.

  Examples of green or cyan pigments include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of the solvent for dissolving these pigments include alkaline high-polar organic solvents, preferably alkaline aprotic polar solvents. The alkaline aprotic polar solvent refers to an aprotic polar solvent containing an alkaline substance (for example, sodium hydroxide, potassium hydroxide, sodium methoxide, potassium t-butoxide). Examples of the aprotic polar solvent include amides (for example, formamide, N, N-dimethylformamide, N, N-dimethylacetamide and the like), heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, N -Cyclohexyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (eg dimethyl sulfoxide etc.), sulfones (eg sulfolane etc.), acetonitrile and the like. Preferred are amides and sulfoxides.

  In the present invention, a polymer compound having a quaternary ammonium moiety is used as a dispersion aid. The polymer compound is entangled with the organic pigment nanoparticles and adsorbed to the pigment particles at a plurality of adsorption points. Therefore, even if the polymer compound is separated from the pigment particles at a certain site, it is adsorbed at other adsorption points. It is considered that the compound is stably adsorbed on the pigment particles and has excellent dispersibility and dispersion stability. Examples of the polymer compound having a quaternary ammonium moiety include poly (methacryloxyalkylammonium salt), poly (methacryloxyarylammonium salt), poly (acryloxyalkylammonium salt), poly (acryloxyarylammonium salt), poly ( Diallylammonium salt), etc., the polymer compound having a quaternary ammonium moiety used in the present invention is a polymer compound having a cationic repeating unit represented by the following general formula (1). preferable.

(In the formula, R _{1 to} R ₃ each independently represents an alkyl group, an aralkyl group, or an aryl group. Any _{two of} R ₁ , R ₂ , and R ₃ may be linked to each other, and oxygen A heterocycle containing an atom, a nitrogen atom, and / or a sulfur atom may be formed, X represents a halogen atom, or an organic or inorganic anion, n represents a natural number of 1 to 5, A represents a hydrogen atom or an alkyl L represents a single bond or a divalent linking group, or a tetravalent linking group further bonded to any _{two of} R ₁ , R ₂ and R ₃ .

In general formula (1), the alkyl group represented by R _{1 to} R ₃ is a substituted or unsubstituted, linear, branched or cyclic alkyl group, preferably an alkyl group having 1 to 12 carbon atoms. Preferably it is a C1-C4 alkyl group. The aralkyl group represented by R _{1 to} R ₃ is a substituted or unsubstituted aralkyl group, and preferably an aralkyl group having 7 to 10 carbon atoms. The aryl group represented by R _{1 to} R ₃ is a substituted or unsubstituted aryl group, preferably an aryl group having 6 to 10 carbon atoms. Each aralkyl group or aryl group may be monocyclic or condensed.

  As the alkyl group, specifically, methyl group, ethyl group, normal propyl group, isopropyl group, normal butyl group, isobutyl group, tertiary butyl group, pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, heptyl group, Octyl group, tertiary octyl group, 2-ethylhexyl group, decyl group and dodecyl group are preferred. Particularly preferred are methyl group, ethyl group, normal propyl group, isopropyl group, normal butyl group, isobutyl group and tertiary butyl group.

  Specifically, the aralkyl group is preferably a benzyl group, a 4-chlorobenzyl group, a 4-methylbenzyl group, a 4-butoxybenzyl group, a 4-methoxybenzylmethoxyphenyl group, or a 4-hydroxybenzyl group. Particularly preferred are a benzyl group, a 4-chlorobenzyl group, a 4-methylbenzyl group, and a 4-butoxybenzyl group.

  Specifically, the aryl group is preferably a phenyl group, a 4-chlorophenyl group, a 4-methylphenyl group, a 4-butoxyphenyl group, a 4-methoxyphenyl group, or a 4-hydroxyphenyl group. Particularly preferred are a phenyl group, a 4-chlorophenyl group, a 4-methylphenyl group, and a 4-butoxyphenyl group.

When any _{two of} R ₁ , R ₂ and R ₃ are connected to each other to form a nitrogen-containing heterocyclic ring having a quaternary ammonium moiety, the heterocyclic ring is preferably a 4 to 6-membered ring. The heterocyclic ring may further contain an oxygen atom, a nitrogen atom, and / or a sulfur atom. Examples of the heterocyclic ring include imidazolium, pyridinium, oxazolium, thiazolium, imidazolinium, oxazolinium, thiazolinium and the like. More preferred are imidazolium, pyridinium, oxazolium, and thiazolium.

  In general formula (1), X may be monovalent or polyvalent, and the halogen atom represented by X is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. Specific examples of the organic anion represented by X include a carboxylate anion, a sulfonate anion, an alkoxide, a benzenesulfonate anion, a naphthalenesulfonate anion, a naphthalenedisulfonate anion, and an anthracene disulfonate anion. Specific examples of the inorganic anion represented by X include a bromine tetrafluoride anion, a phosphorous hexafluoride anion, and a hydroxide. Particularly preferred is an organic or inorganic anion that satisfies the condition that n is a natural number of 1 to 2.

  In general formula (1), the alkyl group represented by A is specifically preferably a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, or a tertiary butyl group. Particularly preferred are a methyl group and an ethyl group.

In the general formula (1), L represents a single bond or a divalent linking group, or a tetravalent linking group further bonded to any _{two of} R ₁ , R ₂ and R ₃ . The divalent linking group represented by L is a linking group containing an aryl group and an aralkyl group. The aryl group and aralkyl group contained in the divalent linking group represented by L may be monocyclic or condensed. The tetravalent linking group bonded to any _{two of} R ₁ , R ₂ and R ₃ represented by L forms a heterocyclic group with the ammonium salt moiety in general formula (1).

Specific examples of the divalent linking group represented by L include phenylene and naphthylene as the aryl group, and phenylmethylene and naphthylmethylene as the aralkyl group. The heterocyclic ring formed by the tetravalent linking group bonded to any _{two of} R ₁ , R ₂ and R ₃ represented by L and the ammonium salt moiety in the general formula (1) includes imidazolium, pyridinium, oxazolium. , Thiazolium, imidazolinium, oxazolinium, thiazolinium and the like. More preferred are imidazolium, pyridinium, oxazolium, and thiazolium.

The following general formula (1) includes those in which any _{two of} R ₁ , R ₂ , and R ₃ are connected to each other, and specific examples of the heterocyclic ring containing oxygen, nitrogen, and sulfur atoms. The example of the high molecular compound which has a cationic repeating unit represented by this is shown. For example, polyvinyl imidazolinium salts, polyvinyl benzimidazolinium salts, polyvinyl pyridinium salts, polystyryl methylene imidazolium salts, polystyryl methylene imidazolinium salts, polystyryl methylene pyridinium salts, polystyryl methylene oxazolium salts, polystyryl Methylene oxazolinium salts, polystyryl methylene thiazolium salts, polystyryl methylene thiazolium salts, polystyryl methylene ammonium salts, polynaphthyl methylene imidazolium salts, polynaphthyl methylene imidazolinium salts, polynaphthyl methylene pyridinium salts, poly Naphthylmethyleneoxazolium salts, polynaphthylmethyleneoxazolinium salts, polynaphthylmethylenethiazolium salts, poly Borderless Le methylene thiazolium salts, poly-naphthyl methylene ammonium salts.
Among these, particularly preferred examples include polystyryl methylene imidazolium salts, polystyryl methylene imidazolinium salts, polystyryl methylene pyridinium salts, polystyryl methylene oxazolium salts, polystyryl methylene oxazolinium salts, polystyryl. Examples include methylene thiazolium salts, polystyryl methylene thiazolium salts, and polystyryl methylene ammonium salts.

  The polymer compound having a quaternary ammonium moiety used in the present invention is more preferably a polymer compound having a cationic repeating unit represented by the following general formula (2).

In the general formula (2), R ₁ to R _3, X and n have the same meanings as R ₁ to R _3, X and n in the general formula (1), and preferred ranges are also the same.

  The polymer compound having a quaternary ammonium moiety used in the present invention may be a random copolymer composed of the cationic repeating unit represented by the general formula (1) and other repeating units. The polymerization ratio is preferably 0.1 to 0.7% by mass, more preferably 0.1 to 0.5% by mass, based on the former polymer compound having a quaternary ammonium moiety. .

  Examples of the copolymer component include vinyl pyrrolidone, styrene, naphthalene, styryl methyl chloride, vinyl imidazole, vinyl pyridine, acrylamide, and vinyl amide. Particularly preferred are vinyl pyrrolidone, styrene, vinyl imidazole, vinyl pyridine, acrylamide, vinyl amide and the like. The copolymerization method may be block copolymerization, but is preferably random copolymerization from the viewpoints of dispersibility, dispersion stability, and synthesis cost.

  Specific examples of the polymer compound having a quaternary ammonium moiety used in the present invention are shown below, but the present invention is not limited thereto. In the following specific examples, the polymer compound used in the present invention is obtained by polymerizing the exemplified repeating units.

  The polymer compound having a quaternary ammonium moiety can be produced by a radical polymerization method with reference to “small”, 2006, Vol. 2, No. 7, p. 879-883.

  The molecular weight of the polymer compound having a quaternary ammonium moiety used in the present invention is preferably 1,000 to 200,000 in terms of number average molecular weight. Furthermore, 3,000 or more and 40,000 or less are more preferable. If it is less than 1,000, the effect of suppressing the growth and aggregation of pigment particles is reduced, and if it exceeds 200,000, problems such as increased viscosity and poor dissolution tend to occur. The polymer in the present invention refers to a polymer having a number average molecular weight of 1000 or more.

  The content of the polymer compound having a quaternary ammonium moiety in the organic pigment nanoparticle dispersion of the present invention is preferably 10% by mass to 1000% by mass with respect to the pigment. Furthermore, 50 mass% or more and 200 mass% or less are more preferable. If it is less than 10% by mass, the effect of suppressing the growth and aggregation of the pigment particles is reduced, and if it exceeds 1000% by mass, problems such as an increase in viscosity and poor dissolution tend to occur.

  In the present invention, preferably, after the pigment and the polymer compound are dissolved in an alkaline polar solvent in a reaction vessel, the solution is poured into an organic pigment insoluble solvent to crystallize the organic pigment nanoparticles, thereby dispersing the pigment nanoparticle dispersion. Get. Here, the organic pigment insoluble solvent is preferably an aqueous medium composed of at least 90% by mass of water. A water-soluble organic solvent that dissolves in water may be added to the aqueous medium. Specific examples of the water-soluble organic solvent include water-soluble alcohols (for example, methanol, ethanol, 1-propanol, 2-propanol, butanol, iso-butanol, sec-butanol, tert-butanol, pentanol, hexanol, Cyclohexanol, benzyl alcohol, etc.), water-soluble polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, Hexanetriol, thiodiglycol, etc.) and water-soluble ketones (acetone, etc.).

In the present invention, the nanoparticles refer to those having an average particle size of 1 nm or more and less than 1000 nm, and the average particle size of the organic pigment nanoparticles in the organic pigment nanoparticle dispersion of the present invention is preferably 10 to 100 nm, 40 nm is more preferable.
The density | concentration of the organic pigment nanoparticle dispersion of this invention becomes like this. Preferably it is 0.5-20 mass%, More preferably, it is 0.5-10 mass%.

  The organic pigment nanoparticle dispersion of the present invention can be suitably used for inkjet inks, color filters, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these.

Example 1
C. I. Pigment Red 254 (56.25 g) and polymer compound A-1 (56.25 g, number average molecular weight of about 20000) were added to dimethyl sulfoxide (DMSO) (100 mL) and stirred. To this solution, 28% by mass sodium methoxide methanol solution (7.5 mL) was added to prepare pigment solution A. On the other hand, water (1 L) to which concentrated hydrochloric acid (14 mL) was added was prepared as a pigment-insoluble solvent B.
While the pigment insoluble solvent B was stirred at 500 rpm with a GK-0222-10 type Lamond Stirrer (trade name) manufactured by Fujisawa Pharmaceutical Co., Ltd. at 30 ° C., the pigment solution A was added to the pigment insoluble solvent B by Nippon Precision Science Co., Ltd. An organic pigment nanoparticle was crystallized by injection at a flow rate of 10 mL / min with an NP-KX-500 large-capacity non-pulsating flow pump (trade name) to obtain a nanopigment dispersion C.
Further, a dispersion D was prepared in the same manner as above except that concentrated hydrochloric acid (14 mL) was not added to the pigment-insoluble solvent B described above.
For dispersion C, ultrasonic irradiation was performed for 30 minutes using an ultrasonic homogenizer US series (trade name) manufactured by Nippon Seimitsu Seisakusho, and dynamic light scattering using LB-400 (trade name) manufactured by Horiba, Ltd. The median diameter was defined as the average particle diameter, and was used as an index of dispersibility. When the dispersion C is partially taken out and allowed to stand at room temperature for 1 month as an indicator of dispersion stability, and when 0.5 volume of concentrated hydrochloric acid of the dispersion C is added as an indicator of resistance to salting-out visually. Observed. The dispersion D was directly evaluated by the dynamic light scattering method.

Example 2
The same operation as in Example 1 was carried out except that the polymer compound A-1 was replaced with polymer compound A-3 (number average molecular weight of about 20000).

Example 3
The same operation as in Example 1 was performed, except that the polymer compound A-1 was replaced with the polymer compound C-2 (number average molecular weight of about 20000).

Example 4
The same operation as in Example 1 was performed, except that the polymer compound A-1 was replaced with the polymer compound C-5 (number average molecular weight of about 20000).

Comparative Example 1
The same operation as in Example 1 was performed except that the polymer compound A-1 was replaced with polyvinylpyrrolidone (PVP) (K-30, trade name, manufactured by Wako Pure Chemical Industries, Ltd., weight average molecular weight of about 40000). It was.

Comparative Example 2
The same operation as in Comparative Example 1 was performed except that the amount of polyvinylpyrrolidone used was 112.5 g.

Comparative Example 3
The same operation as in Example 1 was performed except that the polymer compound A-1 was replaced with the following low molecular dispersant.

  The evaluation results are shown below.

As is apparent from the results in Table 1, Comparative Examples 1 and 2 using polyvinyl pyrrolidone which is a nonionic polymer compound as a dispersion aid are easily affected by the salt concentration, and concentrated hydrochloric acid is added to the pigment insoluble solvent. No dispersion D had a small particle size and no aggregation occurred, but dispersion C in which concentrated hydrochloric acid was added to the pigment-insoluble solvent had caused secondary aggregation between the pigment particles. Further, when Comparative Example 1 and Comparative Example 2 were compared, secondary aggregation was slightly reduced in Comparative Example 2 in which the amount of the dispersion aid used was doubled. From these facts, it was found that when a nonionic polymer compound is used as a dispersion aid, secondary aggregation tends to occur, and a large amount of dispersion aid needs to be used to prevent aggregation.
Further, in Comparative Example 3 using a cationic low molecular weight compound as a dispersion aid, the dispersion stability is inferior, and both dispersions C and D can obtain pigment particles having an average particle size smaller than about 90 nm. could not.

  On the other hand, all of Examples 1 to 4 of the present invention can obtain pigment particles having an average particle size of about 20 to 100 nm in the dispersion C, and the average particle size of the dispersion D is about 20 to 35 nm. Fine pigment particles could be obtained. In particular, in Examples 3 and 4 using the cationic polymer compound represented by the general formula (2) as a dispersion aid, fine pigment particles having an average particle diameter of 22 nm were obtained in both of the dispersions C and D. I was able to get it.

Claims (11)

A organic pigment nanoparticle dispersion you and at least one polymeric compound having an organic pigment particles and quaternary ammonium moieties,
The organic pigment is at least one selected from diketopyrrolopyrrole pigments, quinacridone pigments, phthalocyanine pigments, azo pigments, perylene pigments, anthraquinone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments,
Organic pigment nanoparticles in which the polymer compound having a quaternary ammonium moiety comprises only a cationic repeating unit represented by the following general formula (1) or contains 0.1 to 0.7% by mass of a copolymer component Dispersion.

(In the formula, R _{1 to} R ₃ each independently represents an alkyl group, an aralkyl group, or an aryl group. Any _{two of} R ₁ , R ₂ , and R ₃ may be linked to each other, and oxygen You may form the 4-6 membered heterocyclic ring containing an atom, a nitrogen atom, and / or a sulfur atom, X represents a halogen atom or an organic or inorganic anion, n represents the natural number of 1-5. the .L represents a hydrogen atom or an alkyl group represents a single bond or a divalent linking group or further R _1, R _2, 4 divalent linking group bonded even any two R _3, in. this case, L The divalent linking group forming an aryl group or an aralkyl group is a tetravalent linking group forming L and forms a heterocyclic group with the ammonium salt moiety in the general formula (1). ) 2. The organic pigment nanoparticle dispersion according to claim 1, wherein the polymer compound having a quaternary ammonium moiety is a polymer compound having a cationic repeating unit represented by the following general formula (2). object.

(In the formula, R _{1 to} R ₃ each independently represents an alkyl group, an aralkyl group, or an aryl group. Any _{two of} R ₁ , R ₂ , and R ₃ may be linked to each other, and oxygen A 4- to 6-membered heterocyclic ring containing an atom, a nitrogen atom, and / or a sulfur atom may be formed, X represents a halogen atom, or an organic or inorganic anion, and n represents a natural number of 1 to 5.   R ₁ ~ R ₃ 3. The organic pigment nanoparticle dispersion according to claim 1, wherein the heterocyclic ring is an imidazolium ring, a pyridinium ring, an oxazolium ring, a thiazolium ring, an imidazolinium ring, an oxazolinium ring, or a thiazolinium ring.   The organic pigment nanoparticle dispersion according to any one of claims 1 to 3, wherein the organic pigment is a nanoparticle having an average particle diameter of 10 to 100 nm.   The organic pigment nanoparticle dispersion according to any one of claims 1 to 4, wherein the organic pigment has a dissociable group.   The organic pigment nanoparticle dispersion according to any one of claims 1 to 5, comprising a polymer compound in an amount of 10% by mass to 1000% by mass with respect to the organic pigment.   The organic component according to any one of claims 1 to 6, wherein the copolymerization component is a component derived from a compound selected from vinylpyrrolidone, styrene, naphthalene, styrylmethyl chloride, vinylimidazole, vinylpyridine, acrylamide, and vinylamide. Pigment nanoparticle dispersion.   The molecular weight of the polymer compound is 1,000 to 200,000 in terms of number average molecular weight. The organic pigment nanoparticle dispersion according to any one of claims 1 to 7. A solution prepared by dissolving a polymer compound in an alkaline polar organic solvent having an organic pigment and quaternary ammonium moieties, the organic pigment nanoparticles dispersion Ru is crystallized organic pigment nanoparticles spent on organic pigments insoluble solvent A manufacturing method comprising :
The organic pigment is at least one selected from diketopyrrolopyrrole pigments, quinacridone pigments, phthalocyanine pigments, azo pigments, perylene pigments, anthraquinone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments,
The method for producing an organic pigment nanoparticle dispersion, wherein the polymer compound having a quaternary ammonium moiety is a polymer compound having a cationic repeating unit represented by the following general formula (1).

(In the formula, R _{1 to} R ₃ each independently represents an alkyl group, an aralkyl group, or an aryl group. Any _{two of} R ₁ , R ₂ , and R ₃ may be linked to each other, and oxygen You may form the 4-6 membered heterocyclic ring containing an atom, a nitrogen atom, and / or a sulfur atom, X represents a halogen atom or an organic or inorganic anion, n represents the natural number of 1-5. Represents a hydrogen atom or an alkyl group, L represents a single bond or a divalent linking group, or a tetravalent linking group further bonded to any _{two of} R ₁ , R ₂ and R ₃ . The divalent linking group forming an aryl group or an aralkyl group is a tetravalent linking group forming L and forms a heterocyclic group with the ammonium salt moiety in the general formula (1). )   The method for producing an organic pigment nanoparticle dispersion according to claim 9, wherein the polymer compound having a quaternary ammonium moiety is represented by the following general formula (2).

(Wherein R ₁ ~ R _Three Each independently represents an alkyl group, an aralkyl group, or an aryl group. R ₁ , R ₂ , R _Three Any two of these may be connected to each other, and may further form a 4- to 6-membered heterocyclic ring containing an oxygen atom, a nitrogen atom, and / or a sulfur atom. X represents a halogen atom or an organic or inorganic anion. n represents a natural number of 1 to 5. ) At least method of producing an organic pigment nanoparticle dispersion according to claim 9 or 10 that 90% by weight, characterized in that water the composition of the organic pigment insoluble solvent.