JP2024073004A - Diketopyrrolopyrrole pigment fine particles - Google Patents

Abstract

[Problem] To provide diketopyrrolopyrrole pigment fine particles capable of producing a cured film for a color filter having a significantly low retardation value, a pigment dispersion and a coating film forming composition containing the diketopyrrolopyrrole pigment fine particles capable of producing a cured film for a color filter having a significantly low retardation value, and a color filter having a significantly low retardation value. [Solution] To provide diketopyrrolopyrrole pigment fine particles characterized by a degree of crystallinity of 50% or less and a crystallite size in the plane direction corresponding to the peak at 2θ=24.5°±0.3° of the crystal lattice planes calculated from an X-ray diffraction pattern exceeding 140 Å, and a pigment dispersion containing the diketopyrrolopyrrole pigment fine particles and a solvent. [Selected Figure] None

Description

The present invention relates to diketopyrrolopyrrole pigment fine particles for color filters. The present invention also relates to a pigment dispersion, a coating film forming composition, and a color filter that use the diketopyrrolopyrrole pigment fine particles.

In recent years, the demand for liquid crystal displays has increased with the development of personal computers. In addition, the penetration rate of mobile displays (cell phones, smartphones, tablet PCs) is also increasing, and the market for liquid crystal displays is expanding. Recently, organic light-emitting display devices such as organic EL displays, which are self-luminous and therefore highly visible, have been attracting attention as next-generation image display devices.

The color filter used in the liquid crystal display device generally has a transparent substrate, a colored layer formed on the transparent substrate and consisting of colored patterns of the three primary colors of red, green, and blue, and a light-shielding portion formed on the transparent substrate so as to partition each colored pattern. Methods for forming such a colored layer include pigment dispersion, dyeing, electrodeposition, and printing. Among these, the pigment dispersion method, which has excellent characteristics on average in terms of spectral characteristics, durability, pattern shape, and accuracy, is the most widely used.

On the other hand, liquid crystal display devices have a problem of viewing angle dependency caused by the refractive index anisotropy of the liquid crystal cell and polarizing plate. This viewing angle dependency problem is a problem in which the color and contrast of an image viewed when the liquid crystal display device is viewed from the front and from an oblique direction change.
In order to improve the problem of viewing angle dependency, a method of incorporating a retardation film into a liquid crystal display device has been widely used in the past. However, since the color filters used in liquid crystal display devices have different retardations depending on the coloring patterns of the respective colors of the colored layers, when the above-mentioned retardation film is used, there is a problem that the difference in retardation between the coloring patterns of the respective colors cannot be compensated for, and it has been difficult to completely solve the problem of viewing angle dependency.
Among these, many red color materials are easily crystallized due to their chemical structure, and therefore there has been a problem in that the red colored layer tends to have a larger retardation value in the thickness direction than the colored layers of other colors.
Furthermore, when a red pixel having a yellowish or bluish tinge and a high color density in the red chromaticity region is produced using a conventionally used red coloring material in order to widen the color reproduction range, there has been a problem that an increase in the pigment concentration reduces contrast and brightness and causes deterioration of plate-making properties.

Therefore, a colorant dispersion liquid containing a red colorant, a specific yellow colorant, a specific dispersant, and a solvent has been proposed (Patent Document 1). This colorant dispersion liquid is a colorant dispersion liquid for color filters that has excellent colorant dispersion stability and is capable of forming a colored layer with improved contrast while reducing the retardation value, but the degree of improvement in the retardation value is still insufficient, and there is room for improvement.

International Publication No. 2018/124087

An object of the present invention is to provide diketopyrrolopyrrole pigment fine particles capable of producing a cured film for a color filter having a significantly low retardation value, as well as a pigment dispersion and a coating film-forming composition containing the diketopyrrolopyrrole pigment fine particles capable of producing a cured film for a color filter having a significantly low retardation value.
Another object of the present invention is to provide a color filter having a significantly low retardation value.

The first aspect of the present invention relates to diketopyrrolopyrrole pigment fine particles having a degree of crystallinity of 50% or less and a crystallite size in the plane direction corresponding to the peak at 2θ = 24.5° ± 0.3° among the crystal lattice planes calculated from an X-ray diffraction pattern exceeding 140 Å.

The second aspect of the present invention relates to a pigment dispersion containing the diketopyrrolopyrrole pigment fine particles and a solvent.

The diketopyrrolopyrrole pigment constituting the diketopyrrolopyrrole pigment fine particles is represented by the formula (I):

It may be a compound represented by the formula:

The pigment dispersion may further contain a pigment derivative.

The third aspect of the present invention relates to a coating film-forming composition containing the pigment dispersion.

The fourth aspect of the present invention relates to a color filter containing the coating film forming composition or the diketopyrrolopyrrole pigment fine particles.

By producing a cured film of a color filter using a pigment dispersion containing the diketopyrrolopyrrole pigment fine particles and a coating film forming composition according to the present invention, it is possible to significantly reduce the retardation value, particularly the retardation value in the red colored layer, compared to conventional cured films of color filters.
The color filter according to the present invention has a significantly lower retardation value than conventional filters, and can improve the contrast of an image.

The following describes embodiments of the diketopyrrolopyrrole pigment fine particles, pigment dispersion, coating film forming composition, and color filter according to the present invention.

(Diketopyrrolopyrrole pigment fine particles)
The diketopyrrolopyrrole pigment fine particles according to an embodiment of the present invention (hereinafter also referred to as the pigment fine particles of the present invention) are characterized in that they have a degree of crystallinity of 50% or less, and that the crystallite size in the plane direction corresponding to the peak at 2θ=24.5°±0.3° among the crystal lattice planes calculated from an X-ray diffraction pattern exceeds 140 Å.

It is known that pigments, even if they have the same chemical structure, can have significant differences in color, density, fluidity, etc. if the particle size, shape, crystal structure, etc. are different.
In the pigment fine particles of the present invention, the diketopyrrolopyrrole pigment has the specific degree of crystallinity and the specific crystallite size, and therefore when a cured film of a color filter is produced, it is possible to significantly reduce the retardation value, particularly the retardation value in a red colored layer, compared to the cured films of conventional color filters.

In the present invention, the diketopyrrolopyrrole pigment fine particles are fine particles made of a diketopyrrolopyrrole pigment (hereinafter also referred to as a DPP pigment).
The DPP pigment is a solid pigment that exhibits a deep red color.
The DPP pigment used in the present invention includes a diketopyrrolopyrrole compound having a basic skeleton of 3,6-diphenyl-2,5-dihydro-pyrrolo[3,4-c]-pyrrole-1,4-dione (CAS registration number: 54660-00-3).

The DPP pigment may, for example, be represented by the formula (I):

Examples of the compound include compounds represented by the following formula:
In addition, in the formula (I), the two Br's may each be independently substituted with H, Cl, a phenyl group, a methyl group, or the like.

The DPP pigment may be a commercially available product, such as Pigment Red 254, Pigment Red 291, Pigment Red 255, Pigment Red 264, Pigment Red 272, etc.

In the present invention, the term "fine particles" refers to fine particles of a DPP pigment having an average particle size of 50 nm or less.
The average particle size can be determined as an arithmetic average by selecting 50 arbitrarily finely divided pigment particles from images taken with a transmission electron microscope (product name: JEM-1011, manufactured by JEOL Ltd.) at 50,000 and 100,000 magnifications, measuring the maximum particle size of each finely divided pigment particle based on the measuring scale shown in the images.

In the present invention, the degree of crystallinity refers to the proportion of crystalline portions among the crystalline portions and amorphous portions that constitute the DPP pigment fine particles.
The degree of crystallinity can be measured by a density method, an X-ray diffraction method, an infrared method, an NMR method, a thermal analysis method, etc., but in the present invention, the degree of crystallinity refers to a value measured by an X-ray diffraction method.
Specifically, the value is calculated by the following formula.
Crystallinity (%)=100×(sum of crystalline peak areas)/(sum of crystalline peak areas+sum of amorphous peak areas)

The pigment fine particles of the present invention have a crystallinity of 50% or less, and from the viewpoint of easily achieving the effects of the present invention, it is preferably 40% or less.
By using pigment fine particles having a degree of crystallinity within the above range, it becomes possible to prepare a cured film for a color filter having a significantly low retardation value.

When the present inventors investigated DPP pigment fine particles, they found that the crystallite size in the plane direction corresponding to the peak at 2θ=24.5°±0.3° among the crystal lattice planes calculated from the X-ray diffraction pattern exhibits a strong reddish color.
There is no particular upper limit to the crystallite size, but it is sufficient if it is 400 Å or less.

The X-ray diffraction pattern can be measured using an X-ray diffraction method commonly used in the pigment field, for example, by setting the measurement region (diffraction angle: 2θ) to 5° to 35° and adjusting the X-ray output to 40 kW and 30 mA.

The crystallite size (D) in the plane direction corresponding to the peak at 2θ = 24.5° ± 0.3° among the crystal lattice planes can be calculated from the half-width of the diffraction peak at 2θ = 24.5° ± 0.3° using the Scherrer formula shown below.

In the examples described below, the Scherrer constant (K) was set to 0.94, and the X-ray wavelength (λ) was set to 1.54184 Å. The half-width (β) was obtained by correcting the diffraction pattern using the software "Peak Search" (Rigaku Corporation).

The Bragg angle (θ) used was half the diffraction angle (2θ) of the diffraction peak at 2θ = 24.5° ± 0.3°.

The pigment fine particles of the present invention have an α-type crystal form, which shows a maximum peak at 27.8±0.3° but not at 18.3±0.3° within the diffraction angle (2θ) range of 5 to 35° in powder X-ray diffraction measurement using CuKα radiation. The fact that DPP pigments have the α-type crystal modification is described, for example, in JP-A-8-048908 and JP-A-2008-024873.

The pigment fine particles of the present invention can be prepared by precipitating fine particles from a solution of particle raw materials by a method such as crystallization (bottom-up method).
The method includes a flow method and a batch method.

The bottom-up method is a method in which pigment particles are precipitated by preparing a pigment solution (good solvent) by dissolving the pigment in a solvent that dissolves the pigment, and then mixing it with a solvent that does not dissolve the pigment (poor solvent).

The good solvent may be any solvent capable of dissolving the DPP pigment, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethylsulfoxide (DMSO), etc.

The poor solvent may be any solvent that does not dissolve the DPP pigment and is compatible with the good solvent, for example, water.

In addition, from the viewpoint of the solubility of the DPP pigment, it is preferable to use a base as the good solvent. Examples of bases that can be used preferably include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), and potassium tert-butoxide.

The flow method is a method using a microreactor, in which a pigment solution and a poor solvent are mixed in the flow path of the microreactor to form pigment particle nuclei, and then this mixture is poured into a discharged liquid (poor solvent) to cause the particle nuclei to aggregate together and precipitate as pigment fine particles.
As the microreactor, for example, one described in Japanese Patent No. 4191770 can be used.
The flow rates of the good solvent and the poor solvent when flowing through the flow path in the microreactor may be adjusted according to the configuration of the microreactor so that the flow path is not clogged with precipitated particles.
In the flow method, the discharge liquid may be the same solvent as the poor solvent.

The batch method refers to a method in which a pigment solution is dropped into a poor solvent to precipitate pigment fine particles.
The pigment solution and poor solvent may be the same as those used in the flow method.

In addition, since the pigment fine particles are dispersed in the mixed liquid immediately after precipitation, they can be separated from the liquid component by filtration or decantation, and then dried to obtain a powder of pigment fine particles. The drying method is not particularly limited, but examples include vacuum drying, hot air drying, and freeze drying.

The poor solvent or the good solvent may contain a dispersant or a pigment derivative.
The dispersant and the pigment derivative may be contained in either the poor solvent or the good solvent, or in only one of them.

The dispersant is not particularly limited, and examples thereof include polymer dispersants and surfactant-type dispersants. Among these, polymer dispersants are preferred from the viewpoint of viscosity stability. Examples of polymer dispersants include oil-based polymer dispersants and aqueous polymer dispersants.

Examples of oil-based polymer dispersants include polyurethanes, polyesters, unsaturated polyamides, phosphate esters, polycarboxylic acids and their amine salts, ammonium salts, alkylamine salts, polycarboxylate esters, hydroxyl-containing polycarboxylate esters, polysiloxanes, and modified polyacrylates.

Examples of aqueous polymer dispersants include water-soluble polymer compounds such as alginic acids, polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyvinylpyrrolidone, and gum arabic; ethylenic double bond-containing resins such as styrene-acrylic acid resin, styrene-methacrylic acid resin, styrene-acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid ester resin, methacrylic acid-methacrylic acid ester resin, acrylic acid-acrylic acid ester resin, isobutylene-maleic acid resin, vinyl-ester resin, and rosin-modified maleic acid resin; and amine-based resins such as polyallylamine, polyvinylamine, and polyethyleneimine.

Various polymer dispersants are commercially available, and specific examples thereof are as follows, but are not limited to these.
Lubrizol Japan Co., Ltd.: Solsperse (registered trademark) 3000, 9000, 13240, 17000, 20000, 24000, 26000, 27000, 28000, 32000, 32500, 38500, 39000, 55000, 41000; BYK Japan Co., Ltd.: Disperbyk (registered trademark) 108, 110, 112, 140, 142, 145, 161, 162, 163, 164, 166, 167, 171, 174, 182, 2000, 2001, 2050, 2070, 2150, BYK-LP N22956; BASF: EFKA (registered trademark) 4401, 4403, 4406, 4330, 4340, 4010, 4015, 4046, 4047, 4050, 4055, 4060, 4080, 5064, 5207, 5244, Ajinomoto Fine-Techno Co., Ltd.: Ajisper (registered trademark)-PB821(F), PB822, PB880, Kawaken Fine Chemical Co., Ltd.: Hinoact (registered trademark) T-8000, Kusumoto Chemicals Co., Ltd.: Disparlon (registered trademark) PW-36, Disparlon (registered trademark) DA-325, 375, 7301, etc.

There are no particular limitations on the molecular weight of the polymer dispersant, but a weight average molecular weight of approximately 5,000 to 100,000 is preferred.

The pigment fine particles of the present invention are preferably surface-treated using a polymeric dispersant. In this case, the polymeric dispersant quickly adsorbs to the surface of the precipitated pigment to form fine pigment particles and prevents these particles from re-aggregating.

When the polymer dispersant is used, the discharged liquid preferably contains a base in order to quickly precipitate the polymer dispersant on the surface of the pigment fine particles and suppress the aggregation of the pigment fine particles. Examples of the base include ammonium hydroxide and quaternary ammonium hydroxides (TMAH, TEAH, etc.). For example, the content of ammonium hydroxide, etc. contained in the discharged liquid is not particularly limited, but may be adjusted to 0.1 to 30% by weight from the viewpoint of suppressing aggregation and re-dissolving the DPP pigment fine particles.

The pigment derivative is a compound that controls the particle growth of the pigment fine particles, and examples thereof include (i) a compound having a pigment as a base skeleton and an acidic group, a basic group, or an aromatic group as a substituent in the side chain, (ii) a compound having an aromatic polycyclic compound such as a naphthalene-based, anthraquinone-based, or quinoline-based compound, which is not generally called a dye, as a base skeleton and an acidic group, a basic group, or an aromatic group as a substituent in the side chain, (iii) a compound having a triazine-based base skeleton and an acidic group, a basic group, or an aromatic group as a substituent in the side chain, etc. Examples of the pigment that serves as the base skeleton in (i) include quinacridone-based pigments, phthalocyanine-based pigments, azo-based pigments, quinophthalone-based pigments, isoindoline-based pigments, isoindolinone-based pigments, quinoline pigments, DPP pigments, benzimidazolone pigments, and dioxazine-based pigments.
Specific examples of the pigment derivatives include those described in Japanese Patent No. 6,894,641.

Among them, the most effective pigment derivatives are:

Derivative 1 represented by

Derivative 2 represented by

Derivative 3 represented by

Derivative 4 represented by the formula

The content of each component in the good solvent is not particularly limited as long as the DPP pigment is dissolved therein and the pigment fine particles are precipitated when the good solvent is mixed with the poor solvent. For example,
DPP pigment 5 to 15% by weight
30 to 45% by weight of a base,
0 to 5% by weight of pigment derivatives,
Solvent 40-60% by weight
Examples of adjustments include:

When the good solvent contains a base, the poor solvent preferably contains an acid such as acetic acid in order to adjust the pH and promote precipitation of pigment fine particles.
The content of the acid such as acetic acid in the poor solvent is not particularly limited, but may be adjusted to 0 to 50% by weight.

(Pigment Dispersion)
The pigment dispersion according to the present invention contains the pigment fine particles according to the present invention and a solvent.

From the viewpoint of color filter applications, the solvent used in the pigment dispersion is preferably an organic solvent, such as propylene glycol monomethyl ether acetate (PMA), propylene glycol monomethyl ether (PM), ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethyl acetate, butyl acetate, ethyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, n-propanol, 2-propanol, n-butanol, cyclohexanol, ethylene glycol, diethylene glycol, toluene, and xylene.
These solvents may be used alone or in combination of two or more.

The content of DPP pigment fine particles in the pigment dispersion according to the present invention is not particularly limited, but from the viewpoint of achieving the effects of the present invention, it is sufficient if it is 5 to 70% by weight.

The pigment dispersion according to the present invention may contain other pigments, such as DPP pigments and organic pigments of yellow, orange, red, etc.
In this case, the proportion of the pigment fine particles of the present invention can be arbitrarily changed depending on the desired hue, but in general, it is preferably from 0.1% by weight to less than 100% by weight, and more preferably from 40% by weight to 95% by weight, based on the total organic pigment.

The content of the solvent can be such that the solids concentration, including the DPP pigment fine particles, in the pigment dispersion according to the present invention is 5 to 50% by weight.

The pigment dispersion according to the present invention may further contain a pigment derivative, a dispersant, and the like.
The pigment derivative is not particularly limited as long as it can be used in the bottom-up method.
The dispersant is not particularly limited as long as it can be used in the bottom-up method.
The content of the pigment derivative is not particularly limited as long as it does not affect the desired hue, but from the viewpoints of high contrast and viscosity stability, it is preferably 5 to 35% by weight, more preferably 10 to 25% by weight, based on the total amount of the pigment and the pigment derivative. The content of the pigment derivative in the dispersion is the total amount including the pigment derivative contained in the DPP pigment fine particles.
The content of the dispersant is not particularly limited, but from the viewpoint of obtaining a pigment dispersion effect, it is preferably 10 to 80 parts by weight, more preferably 20 to 60 parts by weight, per 100 parts by weight of the pigment (including pigment derivatives). However, the optimal amount of the dispersant to be added may be appropriately adjusted depending on the combination of the type of pigment used, the type of solvent, and the like.

In addition to the dispersant, the pigment dispersion according to the present invention may contain a resin that can be added to a coating film-forming composition in advance in order to further improve the dispersibility of the pigment, etc., and thus further improve the contrast of the coating film. In the present invention, such a resin is called a dispersing resin. Examples of dispersing resins that can be used in the present invention include alkali-soluble resins, which will be described later. The dispersing resin may be the same as or different from the alkali-soluble resin added to the coating film-forming composition.
The content of the dispersing resin is preferably 5 to 50 parts by weight based on 100 parts by weight of the pigment (including pigment derivatives).

The pigment dispersion can be prepared by mixing and dispersing the DPP pigment and the like using various mixers and dispersers.
In this case, it is preferable to carry out a fine dispersion treatment subsequent to the kneading and dispersion, but it is also possible to omit the kneading and dispersion treatment.

Specifically, the constituents of the pigment dispersion as described above are mixed and pre-dispersed, and then a dispersion medium such as beads is further added to carry out the main dispersion and fine dispersion. Then, if necessary, a solvent is further added to carry out dilution dispersion. After dilution dispersion, if necessary, it is possible to filter using a filter, and use the filtrate as the pigment dispersion.

Specifically, in the preliminary dispersion, the pigments are dispersed using a dispersing machine such as a disperser or homogenizer. When using a disperser, it is preferable to process at 500 to 2000 rpm for 10 to 60 minutes. In the main dispersion, fine dispersion is performed using a bead dispersing machine or the like. When beads are used, it is preferable to add 2 to 6 times the weight of the pigment dispersion. As beads, glass beads, zirconia beads, etc. with a particle size of 0.01 to 1 mm can be used. When using a disperser, the main dispersion process is preferably performed at 1500 to 2500 rpm for about 1 to 12 hours. Examples of bead dispersing machines include vertical or horizontal sand grinders, pin mills, slit mills, ultrasonic dispersers, etc.

When the pigment dispersion of the present invention is applied to a coating film forming composition used in the manufacture of a color filter, it is preferable that the pigment dispersion is soluble in an alkaline aqueous solution.

(Film-forming composition)
The coating film forming composition of the present invention contains the above-mentioned pigment dispersion of the present invention and a coating film forming component. In this way, by containing the pigment dispersion of the present invention, it becomes possible to stably maintain the dispersion state of the DPP pigment even in the coating film forming composition, and the film forming property is good at the time of coating, and it becomes possible to improve the retardation value of the coating film, and further the color filter, more than before.

In the coating film forming composition of the present invention, at least one of the pigment dispersions described above can be used. The content of the pigment dispersion in the coating film forming composition is preferably 5 to 70% by weight, more preferably 15 to 60% by weight, of the pigment (including pigment derivatives) based on the total solid content (weight) of the coating film forming composition. If the content of the pigment dispersion is within this range, it is effective in ensuring sufficient color density and excellent color characteristics.

Examples of the coating film-forming component include polymerizable components, polymers, and mixtures thereof.
As the polymerizable component, a photopolymerizable component is preferred since it is easy to apply patterning by development (negative development).
Usable photopolymerizable components include photopolymerizable compounds and photopolymerization initiators. For example, those described in JP-A-2009-179789 can be used as such photopolymerizable compounds and photopolymerization initiators. The description therein is generally as follows:
That is, such a photopolymerizable compound is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one, preferably two or more, terminal ethylenically unsaturated bonds. Such compounds are widely known in the industrial field, and can be used in the present invention without any particular limitation. The photopolymerizable compound has a chemical form such as, for example, a monomer, a prepolymer, i.e., a dimer, a trimer, and an oligomer, or a mixture thereof and a copolymer thereof.

Examples of monomers and copolymers thereof include unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), their esters, and amides. Preferably, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and aliphatic polyvalent amine compounds are used. In addition, addition reaction products of unsaturated carboxylic acid esters or amides having nucleophilic substituents such as hydroxyl groups, amino groups, and mercapto groups with monofunctional or polyfunctional isocyanates or epoxy groups, and dehydration condensation reaction products of monofunctional or polyfunctional carboxylic acids are also preferably used. In addition, addition reaction products of unsaturated carboxylic acid esters or amides having electrophilic substituents such as isocyanate groups or epoxy groups with monofunctional or polyfunctional alcohols, amines, and thiols, and further substitution reaction products of unsaturated carboxylic acid esters or amides having eliminable substituents such as halogen groups or tosyloxy groups with monofunctional or polyfunctional alcohols, amines, and thiols are also suitable. As another example, it is also possible to use a compound group in which the above-mentioned unsaturated carboxylic acid is replaced with an unsaturated phosphonic acid, styrene, vinyl ether, or the like.
Specific examples of these are as described in JP-A-2009-179789. Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include, as acrylic esters, ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri(acryloyloxypropyl)ether, trimethylolethane triacrylate, hexane ...1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri(acryloyloxypropyl)ether, trimethylolethane triacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol Examples of the acrylates include aryl diacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri(acryloyloxyethyl)isocyanurate, polyester acrylate oligomer, and isocyanuric acid EO-modified triacrylate.

Details of the method of use of these addition polymerizable compounds, such as their structure, whether they are used alone or in combination, and the amount added, can be set arbitrarily in accordance with the performance design of the final coating film-forming composition.
For example, it is selected from the following viewpoints. In terms of sensitivity, a structure with a large content of unsaturated groups per molecule is preferred, and in many cases, bifunctional or more is preferred. In order to increase the strength of the cured film, trifunctional or more is preferred, and further, a method of adjusting both sensitivity and strength by using in combination compounds with different functionalities and different polymerizable groups (e.g., acrylic acid esters, methacrylic acid esters, styrene-based compounds, vinyl ether-based compounds) is also effective.

Furthermore, the selection and method of use of the addition-polymerizable compound are important factors for the compatibility and dispersibility with other components in the coating film-forming composition (e.g., binder polymers such as alkali-soluble resins, photopolymerization initiators, colorants (pigments)). For example, compatibility may be improved by using a low-purity compound or by using two or more types in combination.
A specific structure may be selected for the purpose of improving adhesion to a substrate or the like. The addition-polymerizable compound, which is a photopolymerizable compound, is preferably contained in an amount of 5 to 70% by weight, more preferably 10 to 60% by weight, based on the nonvolatile components in the coating film-forming composition. These may be used alone or in combination of two or more. In addition, the method of using the photopolymerizable compound may be selected from the viewpoints of the degree of polymerization inhibition by oxygen, resolution, fogging, refractive index change, surface adhesion, etc., by arbitrarily selecting an appropriate structure, blending, and amount added.

As the photopolymerization initiator, those described in JP-A-2009-179789 can also be used.
That is, examples of photopolymerization initiators that can be suitably used in the present invention include acetophenone-based, ketal-based, benzophenone-based, benzoin-based, benzoyl-based, xanthone-based, active halogen compounds (triazine-based, oxadiazole-based, coumarin-based), acridine-based, biimidazole-based, and oxime ester-based compounds.
Specific examples of these are as described in JP 2009-179789 A, and specific examples of the benzophenone-based photopolymerization initiator include benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, and 4,4'-dichlorobenzophenone.

The content of the photopolymerization initiator in the coating composition is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass, based on the total solid content of the coating composition. If the content of the photopolymerization initiator is within this range, the polymerization reaction can be smoothly advanced, making it possible to form a film with good strength.

Examples of the polymer include thermoplastic urethane resins, (meth)acrylic resins, polyamide resins, polyimide resins, styrene-maleic acid resins, polyester resins, silicone resins, and cardo resins.
Among the polymers as the coating film-forming component described above, alkali-soluble resins that are soluble in solutions in the alkaline range are preferred.
The weight average molecular weight of the alkali-soluble resin is preferably from 5,000 to 50,000 from the viewpoint of developability.

When the coating film-forming composition according to the present invention contains an alkali-soluble resin, the pattern formability can be further improved when the coating film-forming composition is applied to pattern formation in a photolithography process.

As such an alkali-soluble resin, the one described in JP 2009-179789 A can be used. The description therein is roughly as follows:

That is, the alkali-soluble resin that can be used in the present invention can be appropriately selected from, for example, linear organic polymers having at least one group that promotes alkali solubility (e.g., a carboxyl group, a phosphoric acid group, a sulfonic acid group, etc.) in the molecule (preferably a molecule having an acrylic copolymer or a styrene copolymer as the main chain). Among these, more preferable are those that are soluble in organic solvents and can be developed with a weakly alkaline aqueous solution.

In the present invention, the alkali-soluble resin is preferably a copolymer of (meth)acrylic acid and another monomer copolymerizable therewith. Here, (meth)acrylic acid is a general term for acrylic acid and methacrylic acid, and hereinafter, (meth)acrylate is a general term for acrylate and methacrylate.
Other monomers copolymerizable with (meth)acrylic acid include alkyl (meth)acrylates, aryl (meth)acrylates, vinyl compounds, etc. Here, the hydrogen atoms of the alkyl and aryl groups may be substituted with a substituent.
Specific examples of the alkyl (meth)acrylate and aryl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, tolyl (meth)acrylate, naphthyl (meth)acrylate, and cyclohexyl (meth)acrylate.
Examples of the vinyl compound include styrene, α-methylstyrene, vinyl toluene, glycidyl methacrylate, glycidyl acrylate, acrylonitrile, vinyl acetate, N-vinylpyrrolidone, tetrahydrofurfuryl methacrylate, polystyrene macromonomer, polymethyl methacrylate macromonomer, CH2═CR5R6, CH2═C(R5)(COOR7) (wherein R5 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R6 represents an aromatic hydrocarbon ring having 6 to 10 carbon atoms, and R7 represents an alkyl group having 1 to 8 carbon atoms or an aralkyl group having 6 to 12 carbon atoms).
These other copolymerizable monomers may be used alone or in combination of two or more.

Various alkali-soluble resins are commercially available, and specific examples thereof are as follows, but are not limited to these.
Showa Denko K.K.: Lipoxy (registered trademark) SPCN-100, SPC-2000,
Mitsubishi Chemical Corporation: Dianale (registered trademark) NR series,
Osaka Organic Chemical Industry Co., Ltd.: Viscoat R-264, KS Resist 106,
Daicel Corporation: Cyclomer (registered trademark) P series, Plaxel (registered trademark) CF200 series,
Daicel Allnex Corporation: Ebecryl (registered trademark) 3800;
FOLETT (registered trademark) ZAH110 manufactured by Soken Chemical Industries, Ltd.

The content of the alkali-soluble resin in the coating film-forming composition is preferably 5 to 60% by weight, more preferably 10 to 50% by weight, based on the total solid content of the coating film-forming composition. The content of the alkali-soluble resin in the coating film-forming composition is the total amount including the alkali-soluble resin contained in the pigment dispersion.

The coating forming composition of the present invention can be suitably prepared by using a solvent together with the above-mentioned components.
Examples of such solvents include esters, such as ethyl acetate, n-butyl acetate, isobutyl acetate, amyl formate, isoamyl acetate, butyl propionate, isopropyl butyrate, ethyl butyrate, butyl butyrate, methyl lactate, ethyl lactate, methyl oxyacetate, ethyl oxyacetate, butyl oxyacetate, methyl methoxyacetate, ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate; and 3-oxypropionate alkyl esters such as methyl 3-oxypropionate and ethyl 3-oxypropionate. methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 2-oxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, methyl 2-oxy-2-methylpropionate, 2-oxy-2-methylpropionate, ethyl phosphate, methyl 2-methoxy-2-methylpropionate, ethyl 2-ethoxy-2-methylpropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl 2-oxobutanoate, ethyl 2-oxobutanoate, and the like; ethers, for example, diethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, and the like; ketones, for example, methyl ethyl ketone, cyclohexanone, 2-heptanone, 3-heptanone, and the like; aromatic hydrocarbons, for example, toluene, xylene, and the like.
The solvent may be used alone or in combination of two or more kinds.
The content of the solvent in the coating film-forming composition is preferably such that the total solids (non-volatile components) content in the coating film-forming composition is 5 to 50% by weight, taking into consideration the type and content of the solvent in the pigment dispersion.

The coating film-forming composition of the present invention may contain various additives, such as sensitizing dyes, epoxy resins, fluorine-based organic compounds, thermal polymerization initiators, thermal polymerization components, thermal polymerization inhibitors, fillers, polymeric compounds other than the above-mentioned alkali-soluble resins (dispersion resins) and polymeric dispersants, surfactants, adhesion promoters, antioxidants, ultraviolet absorbers, and aggregation inhibitors, as necessary.

The coating film-forming composition can be obtained by adjusting the pigment dispersion and coating film-forming components according to the present invention, as well as the optional components described above, such as the solvent and various additives, to the desired component composition and stirring them in a mixing tank. By using a dispersing machine such as a disperser to stir in the mixing tank, the pigment and the like can be dispersed in the coating film-forming composition. The resulting mixture may be filtered as necessary.

The coating film-forming composition thus obtained can be suitably used to form a coating film having an excellent retardation value on a substrate such as glass. Therefore, it can be suitably used to manufacture a color filter having an excellent retardation value.

〔Color filter〕
The coating film-forming composition of the present invention can be applied onto a substrate, and then photocured and developed as necessary to obtain a coating film, thereby producing a color filter.
The coating film-forming composition may be the coating film-forming composition of the present invention, or may be a commercially available coating film-forming composition to which the pigment fine particles of the present invention have been added.

In the present invention, the method for applying the coating composition of the present invention to a substrate is not particularly limited, and a spin coating method, a slit method, etc. can be used.

When a coating film is formed on a substrate from the coating film forming composition of the present invention, the thickness of the coating film (after prebaking) is generally 0.3 to 5.0 μm, preferably 0.5 to 4.0 μm, and most preferably 0.5 to 3.0 μm.
In the case of a color filter for a solid-state image pickup device, the thickness of the coating film (after pre-baking) is preferably in the range of 0.5 to 5.0 μm.

[Pre-bake]
After the coating film of the coating film forming composition of the present invention is formed on the substrate as described above, pre-baking is carried out.
If necessary, a vacuum treatment may be carried out before the pre-baking.
The conditions for the vacuum drying are generally a degree of vacuum of about 0.1 to 1.0 torr (13 to 133 Pa), and preferably about 0.2 to 0.5 torr (27 to 67 Pa).
The pre-baking treatment can be carried out using a hot plate, an oven, or the like at a temperature range of 50 to 140° C., preferably about 70 to 110° C., for 10 to 300 seconds. The pre-baking treatment may be combined with a high-frequency treatment, or the high-frequency treatment may be used alone.

After the pre-baking, pattern exposure and development are performed as necessary, followed by a heat treatment (post-baking) usually at 100° C. to 250° C. This post-baking is heating after development to complete curing, and is preferably performed by heating at 200° C. to 250° C. (hard baking).
This post-baking can be carried out continuously or batchwise by using a heating means such as a hot plate, a convection oven (hot air circulation dryer), or a high-frequency heater so that the coating film after development satisfies the above conditions.

The color filter of the present invention can be produced by sequentially carrying out the above steps.
Furthermore, by sequentially repeating the above steps for each color (three or four colors) according to the desired number of hues, a color filter having a cured film colored in multiple colors (color pattern) can be produced.

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

The raw materials and equipment used in the examples and comparative examples are as follows. Commercially available raw materials were used for all other raw materials.

DPP pigment C.I. Pigment Red 291 (Cinilex DPP Red MT-CF, manufactured by Cinic Chemicals)

・Pigment derivative 1
To 100 parts by weight of water, 18.4 parts by weight of cyanuric chloride and 17.3 parts by weight of orthanilic acid (2-aminobenzenesulfonic acid) in an amount sufficient to react with one chlorine atom of cyanuric chloride were added, and the mixture was allowed to react at 10° C. for 1 hour. To the resulting reaction product, 29.8 parts by weight of 5-amino-2-benzimidazolinone in an amount sufficient to react with two chlorine atoms of the reaction product was added, and the mixture was allowed to react at 85° C. for 1 hour. The resulting reaction product was filtered, and the resulting residue was washed with water and then allowed to stand overnight in a thermostatic chamber at 100° C. and dried, to obtain 44.7 parts by weight of Pigment Derivative 1.

・Pigment derivative 2
740 parts by weight of sulfuric acid (primary, 95%) was placed in a reaction vessel and cooled to 15°C or lower. Subsequently, 4 parts by weight of paraformaldehyde (94%) and 20.3 parts by weight of 4-aminophthalimide were added in this order so as not to exceed 20°C, and then the temperature was raised to 22.5°C. The mixture was stirred at 22.5°C and 170 rpm for 1 hour to react. The reaction liquid was brown and transparent. After cooling to 15°C or lower, 40.1 parts by weight of C.I. Pigment Orange 73 (Cinilex DPP Orange SJ1C, manufactured by CINIC Chemicals) was added so as not to exceed 20°C, and then the temperature was raised to 30°C. The mixture was stirred at 30°C and 200 rpm for 3 hours to react. The reaction liquid was deep reddish purple. The reaction liquid was slowly poured into 8200 parts by weight of ice water (pure water: ice = 1: 1 (weight ratio)). After stirring for 30 minutes, the discharged liquid was filtered and washed with pure water to obtain a water paste of the intermediate compound.
685 parts by weight of the water paste of the intermediate compound (solid content 13.5%) and 3000 parts by weight of pure water were added to the diazotization tank and stirred at 60 rpm overnight. 590 parts by weight of 35% hydrochloric acid were added, and after stirring for 5 minutes or more, ice was added to adjust the liquid temperature to 0 to 2.5°C. 100 parts by weight of sodium nitrite was dissolved in 180 parts by weight of pure water and added, and the liquid temperature was kept at 0 to 2.5°C and stirred for 1 hour. 21 parts by weight of sulfamic acid was dissolved in 160 parts by weight of pure water and added, and the liquid temperature was kept at 0 to 2.5°C and stirred for 30 minutes. The pH of the diazotization liquid at this time was 0.88.
6000 parts by weight of pure water and 482 parts by weight of 30% caustic soda were charged into a coupler tank and stirred for 5 minutes or more, after which 400 parts by weight of 1-(3-sulfophenyl)-3-methyl-5(4H)-pyrazolone was added and stirred for 10 minutes or more. 610 parts by weight of sodium acetate was dissolved in 1200 parts by weight of 60°C pure water and added, and after stirring for 30 minutes or more, the liquid temperature was adjusted to 20°C. The pH at this time was 12.60.
Next, the diazotized liquid was added to the coupler tank. The temperature was raised to 20°C at a rate of 1°C/min, and after stirring for 1 hour, the temperature was raised to 60°C at a rate of 1°C/min, and further stirred for 1 hour. The pH after the reaction was 4.62. The pH was adjusted to 2.0 or less with 35% hydrochloric acid, and stirred for 30 minutes. The reaction product obtained was filtered, and the resulting residue was washed with water and then left to stand overnight in a thermostatic bath at 80°C to dry, obtaining 860 parts by weight of Pigment Derivative 2.
The obtained pigment derivative 2 was ground in a bantam mill before use.

Pigment derivative 3
C.I. Pigment Red 255 (BASF Corporation, Irgazin Scaret L 3550HD): 35.0 parts by weight, paraformaldehyde: 4.50 parts by weight, and 4-aminophthalimide: 24.7 parts by weight were added to 630 parts by weight of concentrated sulfuric acid (98%), and reacted at 30°C for 5 hours. Next, this reaction liquid was discharged into 3 L of cold water, filtered and washed with water to obtain an aqueous paste of 4-aminophthalimidomethyl diketopyrrolopyrrole pigment derivative having one 4-aminophthalimidomethyl group introduced therein: 400 parts by weight (solid content: 11.2%).
Next, 3.90 parts by weight of orthanilic acid and 1.20 parts by weight of sodium carbonate were added to 90.0 parts by weight of water and dissolved, and cooled to below 5°C. 4.20 parts by weight of cyanuric chloride was added thereto and reacted at 5°C for 1 hour. Next, 58.0 parts by weight (solid content: 11.2%) of the aqueous paste of the DPP pigment derivative having one 4-aminophthalimidomethyl group introduced therein was added and reacted at 85°C for 1 hour. After the reaction, the mixture was filtered by suction and washed with ion-exchanged water. 86.0 parts by weight of the obtained aqueous paste was dried at 100°C for 20 hours to obtain 8.03 parts by weight of pigment derivative 3.

Pigment derivative 4
20 parts by weight of C.I. Pigment Yellow 138 (BASF, Paliotol Gelb K0961HD) and 300 parts by weight of 98% sulfuric acid were placed in a 500 ml separable flask and reacted at 120 ° C for 5 hours to obtain a sulfonated phthalimidoquinophthalone compound. The reaction mixture was poured into 3000 parts of water while stirring to precipitate a sulfonated phthalimidoquinophthalone compound, and after stirring for 30 minutes, filtration and washing with water were repeated three times. The obtained wet cake was washed with 300 parts by weight of 1% diluted sulfuric acid, filtered, and washed with water. It was dried in a hot air dryer to obtain 54 parts by weight of pigment derivative 4.

・Dispersant "LP N22956"
BYK-LP N22956 (manufactured by BYK Japan Co., Ltd.)

・Dispersion resin "SPCN-100"
Lipoxy (registered trademark) SPCN-100 (manufactured by Showa Denko K.K.)

・Solvent "25% TMAH"
"TMAH 25%" (Showa Denko K.K.)

・Microreactor "Zigzag stripe type microreactor" (Mac Engineering Co., Ltd.)
It has two inlets and one outlet.

(Example 1: Production of Pigment Fine Particles 1)
Pigment fine particles were prepared using a microreactor according to the following procedure (flow method).
30 parts by weight of the DPP pigment, 98.08 parts by weight of 25% TMAH, and 121.92 parts by weight of NMP were mixed and stirred at room temperature at 2000 rpm for 60 minutes, and then cooled to 5° C. or less in an ice bath to prepare a good solvent.
Next, 250 parts by weight of a 40% aqueous acetic acid solution (poor solvent) cooled to 5° C. or below in an ice bath was prepared, and 2,500 parts by weight of pure water (discharge liquid) cooled to 5° C. or below in an ice bath was prepared.
While stirring the discharged liquid at 1000 rpm, the good solvent was started to be fed to the first inlet of the microreactor at a rate of 50 mL/min, and the poor solvent was started to be fed to the second inlet of the microreactor at a rate of 50 mL/min. The mixed liquid that passed through the flow path of the microreactor was discharged from the outlet to the discharged liquid.
After the entire amount of the good solvent and the poor solvent had been delivered and discharged from the discharge port, the discharged liquid was stirred at 1000 rpm for 30 minutes to precipitate the pigment fine particles.
The precipitated pigment fine particles were collected by filtration, washed with water, and then dried to obtain Pigment Fine Particles 1.

(Example 2: Production of Pigment Fine Particles 2)
Pigment fine particles 2 were obtained in the same manner as in Example 1, except that a mixed liquid of 11.51 parts by weight of a dispersant (LP N22956) and 238.49 parts by weight of a 40% aqueous acetic acid solution was used as the poor solvent, and 2,500 parts by weight of 1% aqueous ammonia (1% aqueous ammonium hydroxide solution) was used as the discharged liquid.

(Example 3: Production of Pigment Fine Particles 3)
Pigment fine particles 3 were obtained in the same manner as in Example 2, except that a mixed liquid containing twice the concentration of a dispersant (LP N22956) was used as the poor solvent.

(Example 4: Production of Pigment Fine Particles 4)
28.50 parts by weight of DPP pigment, 1.50 parts by weight of pigment derivative 1, 97.18 parts by weight of 25% TMAH, and 122.82 parts by weight of NMP were mixed and stirred at room temperature at 2000 rpm for 60 minutes, and then cooled to 5° C. or less in an ice bath to prepare a good solvent.
Pigment fine particles 4 were obtained in the same manner as in Example 1, except that this good solvent was used.

(Example 5: Production of Pigment Fine Particles 5)
27.00 parts by weight of DPP pigment, 3.00 parts by weight of pigment derivative 1, 96.28 parts by weight of 25% TMAH, and 123.72 parts by weight of NMP were mixed and stirred at room temperature at 2000 rpm for 60 minutes, and then cooled to 5° C. or less in an ice bath to prepare a good solvent.
Pigment fine particles 5 were obtained in the same manner as in Example 4, except that this good solvent was used.

(Example 6: Production of Pigment Fine Particles 6)
27.00 parts by weight of DPP pigment, 1.50 parts by weight of pigment derivative 1, 1.50 parts by weight of pigment derivative 2, 94.88 parts by weight of 25% TMAH, and 125.12 parts by weight of NMP were mixed and stirred at room temperature at 2000 rpm for 60 minutes, and then cooled to 5° C. or less in an ice bath to prepare a good solvent.
Pigment fine particles 6 were obtained in the same manner as in Example 1, except that this good solvent was used.

(Example 7: Production of Pigment Fine Particles 7)
Pigment fine particles 7 were obtained in the same manner as in Example 4, except that a mixed liquid of 11.51 parts by weight of LP N22956 and 238.49 parts by weight of a 40% aqueous acetic acid solution was used as the poor solvent, and 2,500 parts by weight of 1% aqueous ammonia was used as the discharged liquid.

(Example 8: Production of Pigment Fine Particles 8)
Pigment fine particles 8 were obtained in the same manner as in Example 7, except that a mixed liquid in which the concentration of LP N22956 was doubled was used as the poor solvent.

(Example 9: Production of Pigment Fine Particles 9)
Pigment fine particles were prepared by the following procedure (batch method).
28.50 parts by weight of DPP pigment, 1.50 parts by weight of pigment derivative 1, 97.18 parts by weight of 25% TMAH, and 122.82 parts by weight of NMP were mixed and stirred at room temperature at 2000 rpm for 60 minutes, and then cooled to 5° C. or less in an ice bath to prepare a good solvent.
Next, 2,500 parts by weight of a 4% aqueous acetic acid solution (discharge liquid) cooled to 5° C. in an ice bath was prepared.
While the discharged liquid was stirred at 1000 rpm, the good solvent was fed into the discharged liquid at a rate of 50 mL/min.
After the entire amount of the good solvent was transferred, the discharged liquid was stirred in an ice bath at 1000 rpm for 30 minutes to precipitate pigment fine particles.
The precipitated pigment fine particles were collected by filtration, washed with water, and then dried to obtain Pigment Fine Particles 9.

(Example 10: Production of pigment fine particles 10)
Pigment fine particles 10 were obtained in the same manner as in Example 9, except that the stirring condition of the discharged liquid while the good solvent was being fed was set to 2000 rpm.

(Comparative Example 1: Production of Comparative Pigment Fine Particles 1)
Pigment fine particles were prepared by the salt milling method according to the following procedure.
300 parts by weight of DPP pigment, 3,000 parts by weight of Glauber's salt, and 760 parts by weight of ethylene glycol were charged into a twin-arm kneader (Moriyama, 5 L kneader Σ type, hereinafter referred to as the kneader), and kneaded for 7 hours while controlling the temperature so that the temperature of the kneaded material in the kneader became 40° C.
Next, 115 parts by weight of LP N22956 was added to this mixture and mixed, followed by kneading for 1 hour.
The kneaded mixture was transferred into a tank, and 12,000 parts by weight of deionized water at 50 to 60° C. was added thereto, followed by stirring with a stirrer at a rotation speed of 200 rpm for 30 minutes to disperse the kneaded mixture.
The dispersion was filtered and washed with deionized water. The residue after washing was dried and the obtained dry block was pulverized to obtain comparative pigment fine particles 1.

(Comparative Example 2: Production of Comparative Pigment Fine Particles 2)
Comparative pigment fine particles 2 were obtained in the same manner as in Comparative Example 1, except that 285 parts by weight of DPP pigment and 15 parts by weight of pigment derivative 1 were used instead of 300 parts by weight of DPP pigment.

(Comparative Example 3: Production of Comparative Pigment Fine Particles 3)
Comparative pigment fine particles 3 were obtained in the same manner as in Comparative Example 1, except for the following differences.
Instead of 300 parts by weight of DPP pigment, 285 parts by weight of DPP pigment and 15 parts by weight of pigment derivative 1 were used.
- After 7 hours of kneading, "LP N22956 addition" and "subsequent 1 hour of kneading" are not performed.
The stirring speed in the tank was changed to 200 rpm for 15 minutes, after which the pH of the dispersion was adjusted to 2.3-2.5 using 35% hydrochloric acid, and the dispersion was stirred for a further 30 minutes.

(Comparative Example 4: Production of Comparative Pigment Fine Particles 4)
Comparative pigment fine particles 4 were obtained in the same manner as in Comparative Example 1, except for the following differences.
Instead of 300 parts by weight of DPP pigment, 270 parts by weight of DPP pigment, 15 parts by weight of pigment derivative 1, and 15 parts by weight of pigment derivative 2 were used.
- After 7 hours of kneading, "LP N22956 addition" and "subsequent 1 hour of kneading" are not performed.
The stirring speed in the tank was changed to 200 rpm for 15 minutes, after which the pH of the dispersion was adjusted to 2.3-2.5 using 35% hydrochloric acid, and the dispersion was stirred for a further 30 minutes.

(Test Example 1: Physical properties of pigment fine particles)
For Pigment Microparticles 1 to 10 and Comparative Pigment Microparticles 1 to 4, powder X-ray diffraction (XRD) measurement was carried out under the following conditions using a SmartLab manufactured by Rigaku Corporation, and the crystallinity and crystallite size were measured as follows. The obtained results are shown in Table 1.
(XRD measurement conditions)
Step size: 0.01°
Scan speed: 8°/min Measurement range (2θ): 5° to 35°
X-ray source: CuKα
X-ray output: 40kW 30mA
Detector: Semiconductor detector Entrance slit: 1/4 deg
Soller slit on entrance side: 5 deg
Length limit slit: 10 mm
Receiving slit 1: 15 mm
Receiving slit 2: Open
Receiving side solar slit: 5 deg
(Crystallization degree)
The crystallinity was calculated by a method for calculating the crystallinity by peak separation using the software attached to the powder X-ray diffractometer ("SmartLab Studio II"). Note that the symmetric pseudo-Voigt function was used for peak separation.
(Crystallite Size)
Using the software "Peak Search" (manufactured by Rigaku Corporation), the X-ray diffraction pattern was corrected under the following conditions, and the crystallite size was calculated according to the Scherrer formula based on the corrected data.
(X-ray diffraction pattern correction conditions)
Smoothing score: 99
Background removal search width: 0.01
Background subtraction intensity threshold: 0.10
_Kα2 removal ratio: 0.50
In the Scherrer formula, the Scherrer constant K was 0.94 and the X-ray wavelength λ was 1.54184 Å.

From the results shown in Table 1, all of the pigment fine particles 1 to 10 produced by the bottom-up method had a degree of crystallinity of 50% or less, and the crystallite size in the plane direction corresponding to the peak at 2θ=24.5°±0.3° among the crystal lattice planes calculated from the X-ray diffraction pattern exceeded 140 Å.
In contrast, the comparative pigment fine particles 1 to 4 produced by the salt milling method had a crystallinity of 60% or more.

(Example 11: Preparation of pigment dispersion)
Pigment dispersions were prepared using the pigment fine particles 1, 4, 5, 6, 9 and 10 as follows.
That is, 7.89 parts by weight of pigment fine particles,
Pigment derivative 3 0.38 parts by weight,
Pigment derivative 2 0.10 parts by weight,
Pigment derivative 4 1.14 parts by weight,
Dispersant (LP N22956) 7.29 parts by weight,
Dispersion resin (SPCN-100) 13.29 parts by weight,
4.75 parts by weight of solvent (PM), 15.17 parts by weight of solvent (PMA), and 200 parts by weight of zirconia beads having a diameter of 0.8 mm were placed in a container, and a dispersion treatment (pretreatment) was carried out for 30 minutes using a paint shaker.
Next, the dispersion treatment liquid was diluted with 9.38 parts by weight of PMA.
30 parts by weight of the mill base from which the 0.8 mm zirconia beads had been removed and 120 parts by weight of the 0.1 mm zirconia beads were placed in a separate container and subjected to a dispersion treatment (main dispersion treatment) for 60 minutes using a paint shaker.
The dispersion treatment liquid was diluted with 10 parts by weight of PMA, and the zirconia beads having a diameter of 0.1 mm were then removed to recover the pigment dispersion.
Dispersions prepared from pigment fine particles 1, 4, 5, 6, 9 and 10 were named pigment dispersions 1, 4, 5, 6, 9 and 10, respectively.

(Example 12: Preparation of pigment dispersion)
A pigment dispersion was prepared in the same manner as in Example 11, except that the following materials were used.
Pigment fine particles 2 and 7 were used.
The amount of PMA in the pretreatment was 9.38 parts by weight, and the amount of PMA in the main dispersion treatment was 10.00 parts by weight. The dispersions prepared from pigment fine particles 2 and 7 were named pigment dispersions 2 and 7, respectively.

(Example 13: Preparation of pigment dispersion)
A pigment dispersion was prepared in the same manner as in Example 11, except that the following materials were used.
Pigment fine particles 3 and 8 were used.
The amount of PMA in the pretreatment was 9.38 parts by weight, and the amount of PMA in the main dispersion treatment was 10.00 parts by weight. The dispersions prepared from pigment fine particles 3 and 8 were named pigment dispersions 3 and 8, respectively.

(Comparative Example 5: Production of Pigment Dispersion)
Comparative pigment dispersions 1 and 2 were prepared in the same manner as in Example 12, except that comparative pigment fine particles 1 and 2 were used.

(Comparative Example 6: Production of Pigment Dispersion)
Comparative pigment dispersions 3 and 4 were prepared in the same manner as in Example 11, except that comparative pigment fine particles 3 and 4 were used.

The total weight of the dispersant used for the surface treatment of the pigment particles was the same as that used for the dispersion treatment.

(Test Example 2: Retardation Value of Cured Film)
Pigment Dispersions 1 to 10 and Comparative Pigment Dispersions 1 to 4 were each filtered using a 5μ syringe, and then 1.26 parts by weight of SPCN-100 and 0.74 parts by weight of PMA were added to 10.00 parts by weight of the filtrate and mixed to prepare 14 types of coating film-forming compositions.
These coating film-forming compositions were used to prepare cured films according to the following procedure.

(Preparation of cured film)
Each coating composition was applied to a 1.1 mm thick, 100 mm square glass plate using a spin coater (Mikasa Co., Ltd., Spin Coater MS-150A). Three coated plates were prepared by applying each coating composition so that three coating films with different chromaticity x (value after post-baking, described later) were formed. That is, the rotation speed of the spin coater was changed to change the thickness, so that one of the three plates always had a chromaticity x smaller than 0.6500, and the other plate always had a chromaticity x larger than 0.6500.
These coated plates were dried at 90° C. for 2 minutes and 30 seconds (pre-baked), and then dried at 230° C. for 30 minutes (post-baked) to obtain a cured film formed on the glass plate.

For each of the glass plates (coated plates) on which the cured films were formed, the film thickness and refractive index were measured using a non-contact film thickness meter (F20-EXR, manufactured by Filmetrics Inc.).
Next, for each coated plate, the film thickness and refractive index were inputted into a retardation measurement device (KOBRA-WR, manufactured by Oji Scientific Instruments Co., Ltd.), and the retardation value (unit: nm) was measured at a measurement wavelength of 626.9 nm and an incident angle of 40°. An approximate straight line (calibration curve) was obtained from the measured values of the three coated plates, and the retardation value when the chromaticity x was 0.6500 was regarded as the retardation value of each cured film.

From the results shown in Table 2, it was found that the absolute value of the retardation value of the cured films made from Pigment Dispersions 1 to 10 was low at 12 or less, whereas the absolute value of the retardation value of the cured films made from Comparative Pigment Dispersions 1 to 4 exceeded 7.1, showing a significant difference in retardation value. Therefore, it was found that the cured films made from Pigment Dispersions 1 to 10 had significantly lower retardation values, particularly in the red colored layer, compared to the cured films of conventional color filters, making it possible to improve the contrast of the image.

Claims (7)

Diketopyrrolopyrrole pigment fine particles characterized in that the degree of crystallinity is 50% or less, and the crystallite size in the plane direction corresponding to the peak at 2θ = 24.5° ± 0.3° among the crystal lattice planes calculated from the X-ray diffraction pattern exceeds 140 Å. A pigment dispersion comprising the diketopyrrolopyrrole pigment fine particles according to claim 1 and a solvent. The diketopyrrolopyrrole pigment constituting the diketopyrrolopyrrole pigment fine particles is represented by the formula (I):

The pigment dispersion according to claim 2, wherein the compound is represented by the formula: The pigment dispersion according to claim 2 or 3, further comprising a pigment derivative. A coating film-forming composition containing the pigment dispersion according to claim 2 or 3. A color filter containing the coating film forming composition according to claim 5. A color filter containing the diketopyrrolopyrrole pigment fine particles according to claim 1.