JP2009221266A - Method for producing pigment fine particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method by which approximately spherical pigment fine particles reduced in the difference between minor and major axes are efficiently obtained even when particles are finely divided to nm size, and to provided pigment fine particles and a pigment fine particle dispersion obtained by the method. <P>SOLUTION: In the method for producing pigment fine particles, when a protective group of a pigment precursor is eliminated to convert the precursor to a pigment and fine particles of the pigment are formed, the conversion to the pigment is carried out in the presence of a particle growth inhibitor to suppress the difference between minor and major axes of the formed fine particles. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing fine pigment particles and a pigment fine particle dispersion.

Conventionally, pigments as colorants have a clear color tone, high coloring power, and weather resistance, and have been widely used in many fields. Among these pigments, those that are practically important are generally those of fine particles, and a clear color tone and high coloring power can be obtained by preventing the pigment from agglomerating and making it finer.
Such fine organic pigments can be used as, for example, paints, printing inks, electrophotographic toners, inkjet inks, color filters, and the like, and are very important compounds. Among them, high performance is required, and particularly important in practical use include inkjet pigments and color filter pigments.
Conventionally, dyes have been used for coloring materials for ink jet inks, but there are problems in terms of water resistance and light resistance, and pigments having high water resistance and light resistance have been used. An image obtained with a pigment ink has the advantage of being excellent in light resistance and water resistance as compared with an image obtained with a dye-based ink. However, it is difficult to uniformly refine (ie, monodisperse) a nanometer size that can be infiltrated into the voids on the paper surface, and there is a problem of poor adhesion to paper.
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 fine particles having a nanometer size level and being monodispersed and stable.
However, when the pigment is further refined by a physical method such as salt milling (breakdown method), the pigment dispersion often exhibits high viscosity. For this reason, when this pigment dispersion is prepared on an industrial scale, it becomes difficult to take out the pigment dispersion from a disperser, it cannot be transported by a pipeline, and further, it is gelled during storage. There were problems such as being unusable.

Therefore, conventionally, in order to obtain a pigment dispersion or colored photosensitive composition having excellent fluidity and dispersibility, surface treatment of an organic pigment is performed (for example, see Patent Documents 1 and 2), and various dispersants. (For example, see Patent Documents 3 and 4). However, the organic pigments prepared by these methods have problems in dispersibility and fluidity, and the present condition is that they cannot supply satisfactory ones.
In addition, there is a method using a reprecipitation method for obtaining nanoparticles by injecting a sample dissolved in a good solvent into a poor solvent with controlled stirring conditions and temperature (see, for example, Patent Document 5). Particles produced by this method (build-up method) have good monodispersity (in the present invention, monodispersity means the degree of uniform particle size) and have been attracting attention in recent years. The manufacturing process is complicated and there are problems in productivity and the like.

In recent years, techniques have been developed to chemically modify specific organic pigments to make them soluble in organic solvents. A compound in which a nitrogen atom on a pigment such as quinacridone or indigo is modified with an oxycarbonyl group is known (see, for example, Patent Document 6), and the modified compound is regenerated to the original pigment by heat treatment. It has been known.
However, a large amount of energy is required to regenerate these chemically modified pigment precursors to the original pigments. Therefore, most of the obtained pigment particles are mostly coarse particles with particle growth, and it has been difficult to efficiently produce fine nanoparticles.
Further, it is already known that the addition of a particle growth inhibitor during the pigment synthesis stage or the dispersion process has an effect of suppressing particle growth (see, for example, Patent Documents 7 and 8). However, even with the particles obtained thereby, the particle size is still too large to be used as it is as an inkjet pigment and a color filter pigment, and further miniaturization has been demanded.
The shape of the primary particles of the pigment is determined by the chemical composition, characteristics, crystal structure, synthesis method, and the like, and is various, such as spherical, cubic, rod-like, needle-like, flat, and amorphous (see, for example, Non-Patent Document 1). . The shape and particle size of the primary particles have a great influence on the performance as a pigment powder. For example, it is known that the larger the particle size, the better the hiding power and weather resistance, but the lower the coloring power. Therefore, in order to adjust the shape of the pigment particles, a flushing process has been introduced in the paint industry, etc., but this process is to grow the fine pigment particles by crystal growth and align the particle diameter to the larger one. Yes. That is, there is currently no general method for aligning the particle size distribution on the minute side.

JP-A-11-269401 Japanese Patent Laid-Open No. 11-302553 JP-A-8-48890 JP 2000-239554 A JP 2004-123853 A Japanese Patent Laid-Open No. 7-150068 JP 2000-7777 A JP 2001-240780 A Seijiro Ito, General Editor “Encyclopedia of Pigments” Asakura Shoten, September 25, 2000

  The present invention relates to a production method for efficiently obtaining near-spherical pigment fine particles in which the difference between the major and minor diameters is reduced even when the particles are refined to a nanometer size, and pigment fine particles and pigment fine particle dispersions obtained thereby The purpose is to provide.

The above object has been achieved by the following means.
(1) When the protective group of the pigment precursor is removed to convert to a pigment and fine particles of the pigment are produced, the pigment is converted to the pigment in the presence of a particle growth inhibitor, and the major and minor diameters of the produced fine particles A method for producing pigment fine particles, which suppresses the difference between the two.
(2) The method for producing pigment fine particles according to claim 1, wherein the particle growth inhibitor comprises a compound having a pigment residue.
(3) The method for producing pigment fine particles according to (1) or (2), wherein the particle growth inhibitor has a site having a hydrogen bond forming ability.
(4) In any one of (1) to (3), the portion having the ability to form hydrogen bonds of the particle growth inhibitor is a urea group, a urethane group, a thiourea group, or an amide group. The manufacturing method of the pigment fine particle of description.
(5) The method for producing pigment fine particles according to any one of (1) to (4), wherein the pigment precursor is a compound represented by the following general formula (1).

(Wherein B represents quinacridone pigment, anthraquinone pigment, perylene pigment, benzimidazolone pigment, dioxazine pigment, disazo pigment, azo pigment, indigo pigment, quinophthalone pigment, indanthrone pigment, isoindoline pigment, isoindolinone pigment, phthalocyanine Represents a residue of a chromophore selected from a pigment and a diketopyrrolopyrrole pigment, C represents a protecting group bonded to a hetero atom in B, and is a silyl group, an acyl group, a carbamoyl group, an alkyloxycarbonyl group, an aryloxy group Represents a carbonyl group, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group, wherein the heteroatom is selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, and forms part of the group B; x is an integer of 1 to 8.)

(6) The pigment according to (5), wherein the pigment precursor in the general formula (1) is a pigment precursor in which an oxygen atom of a carbonyl group in the pigment molecule is enol-protected by a protecting group C A method for producing fine particles.
(7) The pigment fine particles according to any one of (1) to (36), wherein the protective group is further removed in the presence of a pigment dispersant, and the pigment precursor is converted into the pigment. Manufacturing method.
(8) The method for producing pigment fine particles according to any one of (1) to (7), wherein the step of removing the protective group of the pigment precursor is performed in a solvent.
(9) The solvent is water, alcohols, ketones, ethers, aromatic compounds, carbon disulfide, aliphatic compounds, nitrile compounds, esters, sulfoxide compounds, amide compounds, halogen-containing compounds, nitro compounds, and The method for producing fine pigment particles as described in (8), which is at least one selected from nitrogen-containing heterocyclic compounds, or a mixture thereof.
(10) The method includes (1) to (9) including a step of removing the protective group in the pigment precursor by at least one method selected from a chemical reaction method, a heating method, and a photolysis method. The method for producing pigment fine particles according to any one of the above.
(11) Pigment fine particles, wherein the particle size of the pigment fine particles obtained by the production method according to any one of (1) to (10) is 50 nm or less.
(12) A pigment fine particle dispersion, wherein an organic pigment produced by the method for producing pigment fine particles according to any one of (1) to (10) is dispersed in a medium.

  The “pigment precursor” in the present invention is an organic solvent-soluble substance in which a protecting group that promotes organic solvent solubility is introduced into at least one functional group in the pigment, and is insoluble by removing the protecting group. What can be converted to a pigment. The “protecting group” in the present invention is a group that protects the molecule by binding to at least one hetero atom in the insoluble pigment molecule, and the insoluble pigment is bonded to the organic solvent by the protective group being bonded. The solubilized product.

  According to the method for producing pigment fine particles of the present invention, even when the particles are refined to a nanometer size, it is possible to efficiently produce nearly spherical pigment fine particles in which the difference between the major axis and the minor axis is reduced. Moreover, according to this invention, the pigment microparticles | fine-particles and pigment fine particle dispersion which are obtained by the said manufacturing method can be provided.

Hereinafter, the present invention will be described in detail.
In the production method of the present invention, by removing the protective group of the pigment precursor in the presence of a particle growth inhibitor, the difference between the major axis and the minor axis of the fine pigment particles is made to be close to a spherical shape. The process of obtaining while reducing.

(A) Pigment precursor The pigment precursor used in the present invention has a structure in which the pigment is modified with a protective group, and a compound represented by the following general formula (1) is preferred.

  In the general formula, B represents quinacridone pigment, anthraquinone pigment, perylene pigment, benzimidazolone pigment, dioxazine pigment, disazo pigment, azo pigment, indigo pigment, quinophthalone pigment, indanthrone pigment, isoindoline pigment, isoindolinone pigment, phthalocyanine It represents the residue of a chromophore selected from pigments and diketopyrrolopyrrole pigments. Among them, a chromophore residue selected from a quinacridone pigment, an anthraquinone pigment, an azo pigment, an isoindoline pigment, and a diketopyrrolopyrrole pigment is preferable, and a chromophore residue selected from a quinacridone pigment, an azo pigment, and a diketopyrrolopyrrole pigment. Are particularly preferred, with chromophore residues comprising diketopyrrolopyrrole pigments being most preferred. C represents a protecting group bonded to a hetero atom in B, and represents a silyl group, an acyl group, a carbamoyl group, an alkyloxycarbonyl group, an aryloxycarbonyl group, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. Here, the heteroatom is selected from the group consisting of a nitrogen atom (N), an oxygen atom (O), and a sulfur atom (S), and constitutes a part of the group B. x is an integer of 1-8.

  The protecting group C is preferably a silyl group, an acyl group, an alkyloxycarbonyl group, or an aryloxycarbonyl group, and particularly preferably a silyl group or an alkyloxycarbonyl group. Also. When x is 2 to 8, the plurality of protecting groups C may be the same or different.

  The pigment precursor used in the present invention is more preferably a compound represented by any one of the following general formulas (2) to (6) described below. In the following general formulas (2) to (6), B ′ is a part of the chromophore group B represented by the general formula (1), Y represents a hetero atom, and B ′ and Y Represents chromophore residue B. Here, the group B′Y has the same meaning as the group B described in the general formula (1), and the preferred range is also the same. Moreover, x in General formula (2)-(6) is synonymous with x described in the said General formula (1), and its preferable range is also the same.

  First, the compound represented by the following general formula (2) will be described.

In the general formula (2), Y represents a hetero atom, and R ^a1 is a monovalent group that can be bonded to a silyl atom. Preferred examples include an aliphatic group, an aryl group, and a heterocyclic group. The plurality of R ^a1 may be the same or different.
In general formula (2), the aliphatic group represented by R ^a1 may be unsubstituted or substituted, may be a saturated group or an unsaturated group, and an aliphatic group having 1 to 15 carbon atoms in total. preferable. Examples thereof include a methyl group, an ethyl group, a vinyl group, an allyl group, an ethynyl group, a 2-ethylhexyl group, an isopropyl group, a t-butyl group, a cyclohexyl group, and a 3,3,3-trifluoropropyl group.
In general formula (2), the aryl group represented by R ^a1 may be unsubstituted or substituted, and is preferably an aryl group having 6 to 16 carbon atoms in total. For example, a phenyl group, 2-methylphenyl group, 4-nitrophenyl group, 2-chlorophenyl group, 2,3,4,5,6-pentafluorophenyl group and the like can be mentioned.
In the general formula (2), the heterocyclic group represented by R ^a1 may be a saturated cyclic group or an unsaturated cyclic group, and is preferably a heterocyclic group having 3 to 15 carbon atoms in total. For example, 2-pyridyl group, 2-pyrimidinyl group, etc. are mentioned.
In the general formula (2), the heteroatom represented by Y is selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, preferably a nitrogen atom or an oxygen atom, more preferably an oxygen atom. And most preferably an enol oxygen atom.

Here, the enol oxygen atom described in the present specification will be described. Normally, when a carbonyl group has a proton at the α-position, a keto-enol tautomer is formed, and the keto form and the enol form show an equilibrium state. In the present invention, the oxygen atom constituting the enol-type hydroxyl group is referred to as an enol oxygen atom. In general, the enol isomer is in a higher energy state than the keto isomer and is unstable. When a protective group is bonded to the enol oxygen atom, the protective group can be removed with low energy and in a short time, and as a result, fine nanoparticles can be formed. Therefore, the pigment precursor in the present invention preferably has a protective group bonded to the enol oxygen atom.
Further, in the present specification, the “aliphatic group” means that the aliphatic moiety is linear, branched or cyclic and may be either saturated or unsaturated, such as an alkyl group, an alkenyl group, It includes a cycloalkyl group and a cycloalkenyl group, and may be unsubstituted or substituted with a substituent. Further, the “aryl group” in this specification may be either a single ring or a condensed ring, and includes, for example, an aromatic group, which may be unsubstituted or substituted with a substituent. In the present specification, the “heterocyclic group” means that the heterocyclic moiety has a hetero atom (eg, nitrogen atom, sulfur atom, oxygen atom) in the ring, and is either a saturated ring or an unsaturated ring. It may be either a single ring or a condensed ring, and may be unsubstituted or substituted with a substituent.
Further, the “substituent” in the present specification may be any group that can be substituted, for example, an aliphatic group, an aryl group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aryl group. Oxy group, heterocyclic oxy group, aliphatic oxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group, aliphatic sulfonyl group, arylsulfonyl group, heterocyclic sulfonyl group, aliphatic sulfonyloxy group, arylsulfonyl Oxy group, heterocyclic sulfonyloxy group, sulfamoyl group, aliphatic sulfonamide group, aryl sulfonamide group, heterocyclic sulfonamide group, amino group, aliphatic amino group, arylamino group, heterocyclic amino group, aliphatic oxycarbonyl An amino group, an aryloxycarbonylamino group, Terrocyclic oxycarbonylamino group, aliphatic sulfinyl group, arylsulfinyl group, aliphatic thio group, arylthio group, hydroxy group, cyano group, sulfo group, carboxyl group, aliphatic oxyamino group, aryloxyamino group, carbamoylamino group And sulfamoylamino group, halogen atom, sulfamoylcarbamoyl group, carbamoylsulfamoyl group, dialiphatic oxyphosphinyl group, diaryloxyphosphinyl group and the like.

  Next, the compound represented by the following general formula (3) will be described.

In General Formula (3), Y represents a hetero atom, and R ^a2 is a monovalent group that can be bonded to the carbonyl carbon. Preferred examples include an aliphatic group, an aryl group, and a heterocyclic group.
In general formula (3), the aliphatic group represented by R ^a2 may be unsubstituted or substituted, may be a saturated group or an unsaturated group, and an aliphatic group having 1 to 15 carbon atoms in total preferable. Examples include a methyl group, an ethyl group, a vinyl group, an allyl group, an ethynyl group, a 2-ethylhexyl group, an isopropyl group, and a t-butyl group.
In the general formula (3), the aryl group represented by R ^a2 may be unsubstituted or substituted, and an aryl group having 6 to 16 carbon atoms is preferable. For example, a phenyl group, 2-methylphenyl group, 4-nitrophenyl group, 2-chlorophenyl group, etc. are mentioned.
In the general formula (3), the heterocyclic group represented by R ^a2 may be a saturated cyclic group or an unsaturated cyclic group, and is preferably a heterocyclic group having 3 to 15 carbon atoms in total. For example, 2-pyridyl group, 2-pyrimidinyl group, etc. are mentioned.
In the general formula (3), the heteroatom represented by Y is selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, preferably a nitrogen atom or an oxygen atom, more preferably an oxygen atom. And most preferably an enol oxygen atom.

  Next, the compound represented by the following general formula (4) will be described.

In General Formula (4), Y represents a hetero atom, and R ^a3 is a monovalent group that can be bonded to a nitrogen atom. Preferred examples include an aliphatic group, an aryl group, and a heterocyclic group. The plurality of R ^a3 may be the same or different.
In the general formula (4), the aliphatic group represented by R ^a3 may be unsubstituted or substituted, may be a saturated group or an unsaturated group, and an aliphatic group having 1 to 15 carbon atoms in total is preferable. Examples include a methyl group, an ethyl group, a vinyl group, an allyl group, an ethynyl group, a 2-ethylhexyl group, an isopropyl group, and a t-butyl group.
In the general formula (4), the aryl group represented by R ^a3 may be unsubstituted or substituted, and is preferably an aryl group having 6 to 16 carbon atoms in total. For example, a phenyl group, 2-methylphenyl group, 4-nitrophenyl group, 2-chlorophenyl group, etc. are mentioned.
In the general formula (4), the heterocyclic group represented by R ^a3 may be a saturated cyclic group or an unsaturated cyclic group, and is preferably a heterocyclic group having 3 to 15 carbon atoms in total. For example, 2-pyridyl group, 2-pyrimidinyl group, etc. are mentioned.
In general formula (4), the heteroatom represented by Y is selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, preferably a nitrogen atom or an oxygen atom, more preferably an oxygen atom. And most preferably an enol oxygen atom.

  Next, the compound represented by the following general formula (5) will be described.

In General Formula (5), Y represents a hetero atom, and R ^a4 is a monovalent group that can be bonded to an oxygen atom. Preferred examples include an aliphatic group, an aryl group, and a heterocyclic group.
In the general formula (5), the aliphatic group represented by R ^a4 may be unsubstituted or substituted, may be a saturated group or an unsaturated group, and an aliphatic group having 1 to 15 carbon atoms in total preferable. Examples thereof include a methyl group, an ethyl group, a vinyl group, an allyl group, an ethynyl group, an isopropyl group, and a t-butyl group.
In general formula (5), the aryl group represented by R ^a4 may be unsubstituted or substituted, and is preferably an aryl group having 6 to 16 carbon atoms in total. For example, a phenyl group, 4-nitrophenyl group, 2-chlorophenyl group, etc. are mentioned.
In the general formula (5), the heterocyclic group represented by R ^a4 may be a saturated cyclic group or an unsaturated cyclic group, and is preferably a heterocyclic group having 3 to 15 carbon atoms in total. For example, 2-pyridyl group, 2-pyrimidinyl group, etc. are mentioned.
In general formula (5), the heteroatom represented by Y is selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, preferably a nitrogen atom or an oxygen atom, more preferably an oxygen atom. And most preferably an enol oxygen atom.

  Next, the compound represented by the following general formula (6) will be described.

In General Formula (6), Y represents a hetero atom, and ^Ra5 is a monovalent group that can be bonded to the hetero atom. Preferred examples include an aliphatic group, an aryl group, and a heterocyclic group.
In general formula (6), the aliphatic group represented by R ^a5 may be unsubstituted or substituted, may be a saturated group or an unsaturated group, and an aliphatic group having 1 to 15 carbon atoms in total preferable. Examples thereof include a methyl group, an ethyl group, a vinyl group, an allyl group, an ethynyl group, an isopropyl group, and a t-butyl group.
In the general formula (6), the aryl group represented by R ^a5 may be unsubstituted or substituted, and is preferably an aryl group having 6 to 16 carbon atoms in total. For example, a phenyl group, 4-nitrophenyl group, 2-chlorophenyl group, etc. are mentioned.
In the general formula (6), the heterocyclic group represented by R ^a5 may be a saturated or unsaturated ring group, and is preferably a heterocyclic group having 3 to 15 carbon atoms in total. For example, 2-pyridyl group, 2-pyrimidinyl group, etc. are mentioned.
In general formula (6), the heteroatom represented by Y is selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, preferably a nitrogen atom or an oxygen atom, more preferably an oxygen atom. And most preferably an enol oxygen atom.

The pigment precursor represented by the general formula (1) is preferably a pigment precursor in which the oxygen atom of the carbonyl group of the pigment is enol protected by a protecting group. The pigment precursor represented by the general formula (1) may be used alone or in combination of two or more.
Below, the specific example is shown about the pigment precursor which can be converted into an insoluble pigment used for this invention. However, the present invention is not limited to these specific examples.

The pigment precursor used in the present invention can be obtained by bonding a protective group to at least one hetero atom in the pigment. For example, when a protective group is bonded to an enol oxygen atom in a pigment, it is obtained by introducing a protective group into an enol-type hydroxyl group in a pigment exhibiting keto-enol variability. Introduction of the protecting group can be carried out by any method, for example, Angew. Chem. Int. Ed. Engl., 1987, 26, 552.
The pigment precursor used in the present invention can also be directly synthesized according to the method described in Industrial Organic Pigments (Wiley, Third edition) and the like.

(b) Particle Growth Inhibitor Next, the particle growth inhibitor used in the present invention will be described. When the protective group of the pigment precursor is removed, the pigment molecules are insolubilized and precipitated, but the resulting pigment particles are coarse particles that have grown. However, when pigment particles are produced in the same manner by removing the protective group of the pigment precursor in the presence of certain additives, particle growth may be hindered to obtain fine particles.
In the present invention, the particle growth inhibitor refers to an agent that exhibits an effect (particle growth inhibitory effect) in which fine particles are obtained by preventing the particle growth of pigment particles that are insolubilized and precipitated. Any particle growth inhibitor may be used as long as it has a particle growth inhibitory effect, but because of its structure, it is a compound having a pigment residue or / and a hydrogen bond forming ability. In particular, those having a portion having a large effect of preventing particle growth are preferably used.
The reason why the particle growth is stopped by the particle growth inhibitor of the present invention is that, for example, the growth direction of the pigment crystal is a hydrogen bond generation direction and a π plane direction substantially perpendicular to the hydrogen bond generation direction. It is presumed that growth is inhibited by the inhibitor being bonded by, for example, hydrogen bonding.

A compound having a pigment residue is preferably used as a particle growth inhibitor, particularly when fine pigment particles having a small size are produced. As the compound having a pigment residue used as a particle growth inhibitor, a compound having a quinacridone pigment residue or a diketopyrrolopyrrole pigment residue, such as a sulfonic acid group, a phthalimidomethyl group, an imidazolylmethyl group, a pyrazolylmethyl group, N A quinacridone pigment having a-(dialkylaminoalkyl) sulfonic acid amide group or a compound having a diketopyrrolopyrrole pigment residue is preferred. Particle growth inhibitors composed of compounds having these pigment residues can be used for particle size control and particle shape control by coexisting with pigment precursors when pigment particles are produced by removing protective groups. Particularly preferably. In addition to the above, the pigment residues used include residues such as anthraquinone, perylene, benzimidazolone, dioxazine, disazo, azo, indigo, quinophthalone, indanthrone, isoindoline, isoindolinone, and phthalocyanine. A compound in which these pigment residues have a sulfonic acid group, a phthalimidomethyl group, an imidazolylmethyl group, a pyrazolylmethyl group, an N- (dialkylaminoalkyl) sulfonic acid amide group, or the like can be preferably used. Among these, pigment residues such as quinacridone, diketopyrrolopyrrole, anthraquinone, benzimidazolone, dioxazine, azo, or phthalocyanine are particularly preferable, and pigment residues such as quinacridone, diketopyrrolopyrrole, and anthraquinone are particularly preferable.
Below, the specific example is shown about the particle growth inhibitor which consists of a compound which has a pigment residue used for this invention. However, the present invention is not limited to these specific examples.

  In the present invention, when a pigment particle is produced by removing a protective group, a particle growth inhibitor composed of a compound having a site having a hydrogen bond forming ability is also allowed to coexist with the pigment precursor, It is effective for the particle shape control as well as the particle size control.

Hereinafter, the site having the ability to form a hydrogen bond (the following structure and functional group) with respect to the pigment during particle growth will be collectively referred to as a “site having a hydrogen bond-forming ability” as appropriate.
The site having the ability to form a hydrogen bond means a site containing an atom (negative atom) having a high electronegativity such as nitrogen, oxygen, sulfur or halogen. For example, the compound is an alcohol group, a thiol group or a carboxylic acid group. Examples thereof include those having at least one group selected from sulfonic acid group, amine group, urea group, urethane group, thiourea group, amide group and the like. Among these, a compound having a urea group, a urethane group, a thiourea group, and an amide group and capable of forming a hydrogen bond is preferable. In addition, the compound having a pigment residue may have a site having a hydrogen bond-forming ability in the structure of the compound having a pigment residue, or may not have the site. What has the site | part which has a hydrogen bond formation ability in the structure is more preferable.
Below, the specific example is shown about the particle growth inhibitor which has the site | part which has a hydrogen bond formation ability used for this invention. However, the present invention is not limited to these specific examples.

Such grain growth inhibitors also act as crystal phase directing agents under certain conditions.
The particle growth inhibitor needs to be added before the protective group is eliminated when the pigment precursor is produced by removing the protective group of the pigment precursor, and 0.05 to 15 based on the mass of the corresponding pigment. It is good to add in the quantity of mass%, Preferably it is 0.1-8 mass%, More preferably, it is 0.5-5 mass%. One kind of particle growth inhibitor may be used, or two or more kinds may be used in combination. When two or more types are used in combination, any combination may be used, but a particle growth inhibitor composed of a compound having a pigment residue and a particle growth inhibitor having a hydrogen bond-forming site are used in combination. More preferably, it is used.

According to the present invention, by generating fine particles from a pigment precursor in the presence of a particle growth inhibitor, the obtained particles are refined, and the particle shape is adjusted or controlled appropriately to control the major axis of the particle diameter. It is possible to produce pigment fine particles in which the difference in short diameter is reduced.
Here, the particle diameter of the pigment fine particles obtained by the present invention varies depending on the conditions such as the type of the particle growth inhibitor, but the particle diameter of the pigment fine particles (primary particles) is preferably 50 nm or less, preferably 5 nm. It is more preferably ˜40 nm, and particularly preferably 10 nm to 30 nm.
In the present invention, the difference between the minor axis and the major axis of the particle diameter is suppressed when the major axis is in the range of 5 to 50 nm and the minor axis is in the range of 5 to 50 nm. This refers to obtaining fine particles having a difference in the range of 0 to 30 nm. Furthermore, the fine particles obtained by the present invention may have a major axis in the range of 5 to 50 nm, a minor axis in the range of 5 to 50 nm, and a difference between the major axis and the minor axis in the range of 0 to 20 nm. More preferably, the major axis is in the range of 5 to 30 nm, the minor axis is in the range of 5 to 30 nm, and the difference between the major axis and the minor axis is particularly preferably in the range of 0 to 10 nm.
Here, the major axis and the minor axis are two straight lines perpendicular to an ellipse that is one section when approximating a single pigment particle as a spheroid particle, and the longest axis is the major axis. The shorter straight line perpendicular to the major axis is called the minor axis. However, the major axis and the minor axis may be the same value.

  Regarding the particle size of the organic nano pigment particles, there is a method of expressing the average size of the population by quantifying by a measurement method, but as a common use, the mode diameter indicating the maximum value of the distribution, the integral distribution curve There are median diameter corresponding to the median, various average diameters (number average, length average, area average, mass average, volume average, etc.). In the present invention, unless otherwise specified, the average particle diameter is Number average diameter. The pigment fine particles formed in the present invention are not limited to crystalline particles, and may be amorphous particles or a mixture thereof.

  In the present invention, the ratio (Mv / Mn) of the volume average particle diameter (Mv) and the number average particle diameter (Mn) is used as an index representing the monodispersity of the particles unless otherwise specified. The monodispersity, that is, Mv / Mn, of particles (primary particles) contained in the organic nanopigment particle dispersion used in the organic nanopigment particle concentration method is preferably 1.0 to 2.0. It is more preferably 0 to 1.8, and particularly preferably 1.0 to 1.5.

  Examples of methods for measuring the particle size of organic nano pigment particles include microscopy, weight method, light scattering method, light blocking method, electrical resistance method, acoustic method, and dynamic light scattering method. The method is particularly preferred. Examples of the microscope used for the microscopy include a scanning electron microscope and a transmission electron microscope. Examples of the particle measuring apparatus based on the dynamic light scattering method include Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd., Dynamic Light Scattering Photometer DLS-7000 series manufactured by Otsuka Electronics Co., Ltd., and LB-400 manufactured by Horiba, Ltd. Product name).

  In the present invention, by using such a particle growth inhibitor, pigment fine particles having a shape approximate to a spherical shape can be obtained with respect to pigment particles such as rods obtained by a conventional production method. By improving the particle shape closer to a true sphere in this way, the ink jet ink obtained from the pigment fine particles has a reduced viscosity and improved fluidity or dispersion stability, thereby preventing ink clogging and the like. The performance can be improved.

  The step of removing the protecting group of the pigment precursor in the present invention is preferably performed in a solvent. The solvent used in the present invention may be any solvent as long as it dissolves or disperses the pigment precursor and the particle growth inhibitor and does not react with these components. Further, in the method of the present invention, the pigment fine particles are produced in the form of a dispersion in which the protective group is removed in a state where the pigment precursor is dissolved in the solvent, and the formed insoluble pigment fine particles are dispersed in the solvent. can do. The dispersion solvent used at this time is not particularly limited as long as the pigment fine particles can be dispersed, but a solvent that can be a good solvent for the pigment precursor and a poor solvent for the pigment fine particles is preferable.

Examples of the solvent that can be a good solvent for the pigment precursor and a poor solvent for the pigment fine particles include water, alcohols, ketones, ethers, aromatic compounds, carbon disulfide, Examples include at least one solvent selected from aliphatic compounds, nitrile compounds, esters, sulfoxide compounds, amide compounds, halogen-containing compounds, nitro compounds, nitrogen-containing heterocyclic compounds, and one or several places in the solvent molecule May be an unsaturated bond or may be halogenated. Among these, water, alcohols, esters, or ketones are preferable, and water, alcohols, or esters are more preferable. These solvents may be used as a mixture of two or more liquids.
Specific examples include methanol, ethanol, isopropyl alcohol, t-butyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ether, dimethyl ether, tetrahydrofuran, benzene, toluene, hexane, acetonitrile, benzonitrile, ethyl acetate, ethyl lactate, 2 -(1-methoxy) propyl acetate, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, dichloromethane, trichloroethylene, chlorobenzene, nitrobenzene, pyridine, quinoline and the like. It is not limited.

  The amount of the solvent is not particularly limited, but when pigment fine particles formed by removing the protecting group of the pigment precursor are obtained, the concentration of the pigment fine particles with respect to the solvent is in the range of 0.1% by mass to 20% by mass. It is preferable that it is 0.3 to 15% by mass. When the amount of the solvent is too large, it takes time to take out the pigment fine particles from the solvent, and there is a problem that a concentration step is required when the pigment fine particles are used as a pigment dispersion. When the amount of the solvent is too small, problems such as easy aggregation and increased viscosity occur.

  When the protective group of the pigment precursor is deprotected in the solvent to form pigment particles, a dispersant may be added to the solvent. Here, the dispersant has an action of (1) quickly adsorbing on the surface of the deposited pigment and (2) preventing these particles from aggregating again. In contrast to the particle growth inhibitor used in the present invention, the dispersant can be referred to as a particle aggregation inhibitor.

Examples of the pigment dispersant that can be used in the present invention include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a salt of a long chain polyaminoamide and a polar acid ester, High molecular weight unsaturated acid ester, high molecular weight copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalenesulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl Examples thereof include phosphoric acid esters, polyoxyethylene nonylphenyl ether, stearylamine acetate, and compounds having a pigment residue. However, when the dispersant is a compound having a pigment residue, it is not the same as the particle growth inhibitor of the present invention.
As the polymer dispersant, for example, the weight average molecular weight (Mw) is preferably in the range of 1,000 to 200,000, and particularly preferably in the range of 10,000 to 100,000. This weight average molecular weight is a polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (carrier: tetrahydrofuran).

  Specific examples of the pigment dispersant include “Anti-Terra-U (polyaminoamide phosphate)”, “Anti-Terra-203 / 204 (high molecular weight polycarboxylate)” manufactured by BYK Chemie, “Disperbyk-101 ( Polyaminoamide phosphate and acid ester), 107 (hydroxyl group-containing carboxylic acid ester), 110 (copolymer containing an acid group), 130 (polyamide), 161, 162, 163, 164, 165, 166, 170, 2000 ( Polymer copolymer) ”,“ 400 ”,“ Bykumen ”(high molecular weight unsaturated acid ester),“ BYK-P104, P105 (high molecular weight unsaturated acid polycarboxylic acid) ”,“ P104S, 240S (high molecular weight unsaturated) Saturated acid polycarboxylic acid and silicon system "," Lactimon (long chain amine and unsaturated) Such as polycarboxylic acid and silicon) "and the like (all trade names).

  Further, “Fuka 44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71, 701, 764, 766, 6750” manufactured by Efka CHEMICALS, “Efka Polymer 100 (modified polyacrylate), 150 ( Aliphatic modified polymer), 400, 401, 402, 403, 450, 451, 452, 453 (modified polyacrylate), 745 (copper phthalocyanine-based) "," Floren TG-710 (urethane oligomer) "manufactured by Kyoeisha Chemical Co., Ltd. , “Flonon SH-290, SP-1000”, “Polyflow No. 50E, No. 300 (acrylic copolymer)”, “Disparon KS-860, 873SN, 874 (polymer dispersing agent) manufactured by Enomoto Kasei Co., Ltd. # 2150 (aliphatic polycarboxylic acid), # 7004 (polyetherester) ) "And the like (all trade names).

Further, “Demol RN, N (Naphthalenesulfonic acid formalin condensate sodium salt), MS, C, SN-B (aromatic sulfonic acid formalin condensate sodium salt), EP”, “Homogenol L-18 (poly) Carboxylic acid type polymer) ”,“ Emulgen 920, 930, 931, 935, 950, 985 (polyoxyethylene nonyl phenyl ether) ”,“ Acetamine 24 (coconut amine acetate), 86 (stearyl amine acetate) ”, Lubrizol “Solspers 5000 (phthalocyanine ammonium salt type), 13240, 13940 (polyesteramine type), 17000 (fatty acid amine type), 3000, 24000GR, 32000, 39000, 55000” manufactured by Nikko Chemical Co., Ltd. Alkoxy polyoxyethylene sorbitan monooleate), MYS-IEX (polyoxyethylene monostearate), Hexagline 4-0 (none hexaglyceryl ruthenate Huwei rate) "and the like (trade name).
The pigment dispersant is more preferably a polymer having a pigment residue. Here, the structure of the organic pigment constituted by the pigment residue may be the same as or different from the structure of the pigment obtained by conversion from the pigment precursor used in the present invention. It is preferable that it is the same or similar structure from the viewpoint of.

  The content of the dispersant is preferably in the range of 0.1 to 1000 parts by mass with respect to 100 parts by mass of the organic pigment fine particles in order to further improve the uniform dispersibility and storage stability of the organic pigment fine particles. More preferably, it is the range of 1-500 mass parts, More preferably, it is the range of 10-250 mass parts. If the amount is less than 0.1 parts by mass, the dispersion stability of the organic pigment fine particles may not be improved.

The pigment precursor can be converted into a pigment by removing the protective group by any method such as a chemical reaction method, a heating method, a photolysis method, or a combination of these methods. Which method is used differs depending on the structure of the pigment precursor.
The chemical reaction method means that a compound that initiates or accelerates the conversion of the pigment precursor to an insoluble pigment coexists with the pigment precursor in some way. At this time, the pigment precursor may be dissolved in the solution or may be present in a solid state (for example, in a state of being spin-coated on a glass substrate).

  As a method for adding a compound that promotes pigmentation, it may be added directly to the pigment precursor or may be diluted in a solvent capable of dissolving the compound. Further, the whole amount may be added at once, or may be added in divided portions at an appropriate time. Further, the addition amount is not particularly limited, but when there are x B groups in the pigment precursor represented by the general formula (1), the addition amount is preferably 0.01 x mol to 10 x mol, More preferably, it is 0.1xmol-2xmol. Depending on the addition method and amount of the compound that promotes pigmentation, the particle size of the pigment can be changed.

  Examples of the compound that promotes pigmentation include acids, bases, nucleophiles, electrophiles, oxidizing agents, reducing agents, coordination compounds, and the like, preferably acids or bases, and particularly preferably acids. . In particular, the pigment precursor represented by the general formula (2), in which Y represents an oxygen atom and an oxygen atom and a silyl atom are bonded, an acid or a fluorine anion is used. It is preferable to form a pigment using a compound such as tetrabutylammonium fluoride.

  As an appropriate acid that can be used, either an organic acid or an inorganic acid may be used. Examples of the organic acid include acetic acid, formic acid, propionic acid, trifluoroacetic acid, lauric acid, acrylic acid, ascorbic acid, benzoic acid, salicylic acid, Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and boric acid. Also included are latent acids that generate an acid by chemical reaction (for example, complex formation reaction), photoreaction, heating and the like. These may be used alone or in combination of two or more.

  As an appropriate base that can be used, either an organic base or an inorganic base may be used. Examples of the organic base include pyridine, triethylamine, aminoethanol, triethanol, dimethylaniline, lutidine, and the like. Examples of the inorganic base include Potassium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium hydroxide, potassium hydroxide, sodium acetate and the like. It also includes latent bases that generate bases by chemical reactions (for example, complex formation reactions), photoreactions, heating, and the like. These may be used alone or in combination of two or more.

  The heating method means that the pigment precursor is converted into an insoluble pigment by heating, and the pigment precursor remains in a solid state (for example, spin-coated on a glass substrate) even when dissolved in the solution. May exist). Although there is no restriction | limiting in particular in heating temperature, It is preferable that it is 50 to 250 degreeC, and it is more preferable that it is 70 to 190 degreeC.

  The photolysis method refers to conversion to an insoluble pigment by irradiating the pigment precursor with ultraviolet rays, visible light, infrared rays or the like. The pigment precursor may be dissolved in the solution or may be present as a solid (for example, in a state where it is spin-coated on a glass substrate).

Hereinafter, preferred embodiments of the present invention for obtaining pigment fine particles by converting a pigment precursor into an insoluble pigment will be described below. In addition, this is an example and this invention is not limited to this at all.
First, a pigment precursor and a particle growth inhibitor are coexistent and dissolved in a solvent. When a pigment dispersant is used, it is dissolved together with the pigment precursor and the particle growth inhibitor. Here, the types of the dispersant, the solvent, and the particle growth inhibitor are appropriately selected depending on the pigment precursor and the obtained pigment. By adding an appropriate acid or the like while stirring the pigment precursor solution, the pigment precursor is converted and an insoluble pigment is instantly formed.

  The stirring speed at the time of stirring is preferably 100 to 10000 rpm, more preferably 150 to 8000 rpm, and particularly preferably 200 to 6000 rpm. Although there is no restriction | limiting in particular about the temperature of the solvent at the time of particle | grain formation, It is preferable that it is -20 degreeC-100 degreeC, and it is more preferable that it is 0 degreeC-50 degreeC.

  In the pigment fine particle liquid produced by such a method, the pigment fine particles may cause aggregation. As a method of dispersing such agglomerated fine particles, for example, any method such as a dispersion method using ultrasonic waves or a method of applying physical energy can be used, and it can also be obtained in the form of a dispersion.

  The ultrasonic irradiation device used preferably has a function capable of applying an ultrasonic wave of 10 kHz or higher, and examples thereof include an ultrasonic homogenizer and an ultrasonic cleaner. When the liquid temperature rises during ultrasonic irradiation, thermal aggregation of the nanoparticles occurs (refer to “Latest Pigment Dispersion Technology” Technical Information Association, 1995, p166). Therefore, the liquid temperature is preferably 1 to 100 ° C. -60 degreeC is more preferable. The temperature control method can be performed by controlling the temperature of the dispersion, controlling the temperature of the temperature adjusting layer that controls the temperature of the dispersion, or the like.

  There are no particular restrictions on the dispersing machine used to disperse the concentrated organic nanoparticles by applying physical energy. For example, kneader, roll mill, atrider, super mill, dissolver, homomixer, sand mill, etc. Machine.

  The pigment dispersion obtained in the present invention and the pigment nanoparticles obtained therefrom can be used as a suitable inkjet ink or its raw material fine particles, or a color filter coating liquid or its raw material fine particles. As an advantage in inkjet applications, clogging at the nozzle head is unlikely to occur because of the fine pigment particles. As an advantage used in the color filter, since it is a fine pigment particle, it is expected that scattered light hardly occurs and the contrast is increased.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited at all by these. Unless otherwise specified, “%” and “parts” are based on mass.
<Synthesis of pigment precursor>
[Synthesis Example P-1]
To 100 parts of a tetrahydrone solution in which 5.0 parts of 1,4-diketo-3,6-bis (4-chlorophenyl) pyrrolo [3,4-c] pyrrole is dissolved, 0.9 part of dimethylaminopyridine is added and 25 ° C. Stir with. Thereto was added 3.7 parts of di-tert-butyl dicarbonate, and the mixture was stirred at 30 ° C. for 1 hour. After an additional hour, 3.7 parts of di-tert-butyl dicarbonate was added and stirred at 30 ° C. for 4 hours. After completion of the reaction, the mixture is filtered and the solvent is distilled off. The residual solid was washed with a 5% aqueous solution of sodium hydrogen carbonate and then with 1N hydrochloric acid to obtain 7.7 parts of pigment precursor P-1.

[Synthesis Example P-2]
To 60 parts of a tetrahydrofuran solution in which 2.9 parts of 1,4-diketo-3,6-bis (4-chlorophenyl) pyrrolo [3,4-c] pyrrole was dissolved, 0.7 part of sodium hydride was added and the mixture was heated at 60 ° C. Stir for 1 hour. Thereafter, 4.6 parts of t-butyldimethylsilyl chloride was added, and the mixture was heated and stirred for 5 hours, followed by suction filtration, and the filtrate was concentrated. The precipitated solid was dissolved in chloroform, washed with water and filtered repeatedly to obtain 4.4 parts of pigment precursor P-2.

[Synthesis Example P-3]
To 100 parts of a tetrahydrone solution in which 5.0 parts of 1,4-diketo-3,6-bis (4-chlorophenyl) pyrrolo [3,4-c] pyrrole is dissolved, 1.23 parts (60%) of sodium hydride And stirred at 60 ° C. for 1 hour. Thereafter, 5.5 parts of chloro (dimethyl) (1,1,2-trimethylpropyl) silane was added, and the mixture was heated and stirred for 5 hours, followed by suction filtration, and the filtrate was concentrated. The precipitated solid was dissolved in chloroform, washed with water, and filtered repeatedly to obtain 10.1 parts of pigment precursor P-3.

[Synthesis Example P-4]
To 200 parts of a tetrahydrone solution in which 6.1 parts of 1,4-diketo-3,6-bis (4-chlorophenyl) pyrrolo [3,4-c] pyrrole is dissolved, 1.0 part of dimethylaminopyridine is added and 25 ° C. Stir with. Thereto was added 5.0 parts of di-tert-amyl dicarbonate, and the mixture was stirred at 30 ° C. for 1 hour. After further 1 hour, 5.0 parts of di-tert-amyl dicarbonate was added and stirred at 30 ° C. for 4 hours. After completion of the reaction, the mixture is filtered and the solvent is distilled off. The residual solid was washed with a 5% aqueous solution of sodium hydrogen carbonate and subsequently with 1N hydrochloric acid to obtain 9.8 parts of pigment precursor P-4.

[Synthesis Example P-5]
To 50 parts of a tetrahydrone solution in which 2.8 parts of 1,4-diketo-3,6-bis (4-chlorophenyl) pyrrolo [3,4-c] pyrrole is dissolved, 0.7 part (60%) of sodium hydride And stirred at 60 ° C. for 1 hour. Thereafter, 4.8 parts of t-butyldiphenylsilyl chloride was added and the mixture was heated and stirred for 5 hours, followed by suction filtration, and the filtrate was concentrated. The precipitated solid was dissolved in chloroform, washed with water, and filtered repeatedly to obtain 4.4 parts of pigment precursor P-5.

  Other pigment precursors such as P-7 and P-18 can also be obtained by the same operation as described above.

<Synthesis of pigment dispersant>
D-1
Monomer that gives the following repeating unit M-1 10 parts by mass Polymethyl methacrylate 90 parts by mass having a methacryloyl group at the end (number average molecular weight 6000, AA-6, Toagosei Co., Ltd., trade name)

D-2
Monomer that gives the following repeating unit M-2: 10 parts by mass 90 parts by mass of polymethyl methacrylate having a methacryloyl group at its terminal (number average molecular weight 6000, AA-6, Toagosei Co., Ltd., trade name)

In addition, the following commercially available dispersants were used (D-3 to D-11 are trade names).
D-3: Solspers 24000GR (manufactured by Lubrizol)
D-4: Solspers 32000 (manufactured by Lubrizol)
D-5: Disperbyk-161 (manufactured by BYK Chemie)
D-6: Disperbyk-2000 (BYK Chemie)
D-7: Solspers 3000 (manufactured by Lubrizol)
D-8: EFKA6750 (manufactured by EFKA)
D-9: Solspers 5000 (manufactured by Lubrizol)
D-10: Solspers 39000 (manufactured by Lubrizol)
D-11: Solspers 55000 (manufactured by Lubrizol)
D-12: Polyacrylic acid (manufactured by aldrich)
D-13: Polyvinylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.)

  The polymer containing the repeating units represented by D-1 and D-2 can be obtained by any method, and for example, can be synthesized according to the method described in JP-A-2007-9117.

Example 1
The particle growth inhibitor H-1 (0.01 part), the pigment dispersant D-1 (0.5 part) and the pigment precursor P-3 (0.9 part) shown above were converted into 1-methoxy-2- The solution added to 100 parts of propyl acetate (hereinafter abbreviated as PGMEA) was stirred at 25 ° C. and 500 rpm using a GK-0222-10 type Lamond Stirrer (trade name) manufactured by Fujisawa Pharmaceutical Co., Ltd. 1,2-diketo-3,6-bis (4-chlorophenyl) pyrrolo [3,4-c] pyrrole pigment particles were prepared by adding 0.22 part of trifluoroacetic acid all at once. At this time, it was confirmed that the pigmentation was completely completed using an ultraviolet-visible spectrophotometer (UV-2400PC, trade name, manufactured by Shimadzu Corporation). Further, this solution was irradiated with ultrasonic waves for 30 minutes using an ultrasonic homogenizer US series (trade name) manufactured by Nippon Seimitsu Seisakusho Co., to prepare pigment particle dispersion R-1.

Examples 2-81
In Example 1, except that the composition of the material added to the solution was changed as shown in Table 1 below, pigment particle dispersions R-2 to R-81 were prepared in the same manner as in Example 1. Got.

Comparative Example 1
The particle growth inhibitor H-1 (0.01 part), the pigment dispersant D-1 (0.5 part) and the pigment precursor P-3 (0.9 part) shown above in Example 1 were The solution added to 100 parts of methoxy-2-propylacetate (PGMEA) was mixed with pigment dispersant D-1 (0.5 part) and the above-described pigment precursor P-3 (0.9 part) with 1-methoxy. A pigment particle dispersion W-1 was prepared by preparing a pigment in the same manner as in Example 1 except that the solution was added to 100 parts of 2-propyl acetate.

Comparative Examples 2-3
In Comparative Example 1, except that the composition of the material added to the solution was changed as shown in Table 2 below, pigment particle dispersions W-2 to W-3 were prepared by preparing pigment particles in the same manner as in Comparative Example 1. Got.

<Evaluation>
Each dispersion was evaluated as follows. The results are shown in Tables 3 and 4.

Particle size The particle size of the pigment particles thus obtained was determined as follows. First, using a transmission electron microscope (JEM-2010, trade name, manufactured by JEOL Ltd.) with a pigment particle dispersion dropped and dried on a mesh with a support film as a sample, observation was performed at an acceleration voltage of 100 kV. It was. Subsequently, 100 or more particles of the measured photograph were subjected to image processing one by one, and the average of the major axis and minor axis was obtained. The major axis and the minor axis are two long lines that are perpendicular to an elliptical shape of one section when a pigment particle is approximated as a spheroid particle. Was the major axis, and the shorter straight line perpendicular to the major axis was the minor axis.

As is apparent from the results of Tables 3 and 4, when a particle growth inhibitor is allowed to coexist at the time of particle formation according to the present invention, the particle size is clearly made finer, and the particle shape also has a minor axis and a major axis. It can be seen that the difference is significantly reduced.
When these fine pigment particles are used for inkjet applications, it is expected that clogging at the nozzle head is improved, and when they are used in a color filter, the contrast is increased by suppressing scattered light.

Claims (12)

  When the protective group of the pigment precursor is removed and converted to a pigment, and the fine particles of the pigment are produced, the pigment is converted to the pigment in the presence of a particle growth inhibitor, and the difference between the major axis and minor axis of the produced fine particle is determined. A method for producing pigment fine particles, which comprises suppressing the above.   The method for producing fine pigment particles according to claim 1, wherein the particle growth inhibitor comprises a compound having a pigment residue.   The method for producing fine pigment particles according to claim 1 or 2, wherein the particle growth inhibitor has a site having a hydrogen bond forming ability.   4. The pigment fine particle according to claim 1, wherein the part having the ability to form a hydrogen bond of the particle growth inhibitor is a urea group, a urethane group, a thiourea group, or an amide group. Production method. The method for producing pigment fine particles according to any one of claims 1 to 4, wherein the pigment precursor is a compound represented by the following general formula (1).

(Wherein B represents quinacridone pigment, anthraquinone pigment, perylene pigment, benzimidazolone pigment, dioxazine pigment, disazo pigment, azo pigment, indigo pigment, quinophthalone pigment, indanthrone pigment, isoindoline pigment, isoindolinone pigment, phthalocyanine Represents a residue of a chromophore selected from a pigment and a diketopyrrolopyrrole pigment, C represents a protecting group bonded to a hetero atom in B, and is a silyl group, an acyl group, a carbamoyl group, an alkyloxycarbonyl group, an aryloxy group Represents a carbonyl group, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group, wherein the heteroatom is selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, and forms part of the group B; x is an integer of 1 to 8.)   6. The method for producing fine pigment particles according to claim 5, wherein the pigment precursor in the general formula (1) is a pigment precursor in which an oxygen atom of a carbonyl group in the pigment molecule is enol-protected by a protecting group C. .   The method for producing fine pigment particles according to any one of claims 1 to 6, wherein the protective group is further removed in the presence of a pigment dispersant to convert the pigment precursor into the pigment.   The method for producing pigment fine particles according to any one of claims 1 to 7, wherein the step of removing the protective group of the pigment precursor is performed in a solvent.   The solvent is water, alcohols, ketones, ethers, aromatic compounds, carbon disulfide, aliphatic compounds, nitrile compounds, esters, sulfoxide compounds, amide compounds, halogen-containing compounds, nitro compounds, and nitrogen-containing complexes. 9. The method for producing pigment fine particles according to claim 8, which is at least one selected from ring compounds, or a mixture thereof.   10. The method according to claim 1, further comprising a step of desorbing the protecting group in the pigment precursor by at least one method selected from a chemical reaction method, a heating method, and a photolysis method. A method for producing pigment fine particles as described in 1. above.   Pigment fine particles obtained by the production method according to any one of claims 1 to 10, wherein the particle size of the pigment fine particles is 50 nm or less.   A pigment fine particle dispersion, wherein an organic pigment produced by the method for producing pigment fine particles according to any one of claims 1 to 10 is dispersed in a medium.