JP2005275052A - Blue pigment composition for color filter and color filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color filter to obtain a liquid crystal display device having high contrast which results in a sharper display image and having high luminance which results in a brighter display screen, and to provide a blue pigment composition to obtain the color filter. <P>SOLUTION: The blue pigment composition for a color filter comprises a ε-copper phthalocyanine pigment having 30 to 70 nm average particle diameter of primary particles and a dioxazine violet pigment having 15 to 40 nm average particle diameter of primary particles. The color filter contains the above blue pigment composition for a color filter in the blue pixel part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a blue pigment composition suitable for producing a blue pixel portion of a color filter of a liquid crystal display device and a color filter having a blue pixel portion containing the blue pigment composition.

  The color filter of the liquid crystal display device has a red pixel portion (R), a green pixel portion (G), and a blue pixel portion (B). Each of these pixel portions has a structure in which a thin film of a synthetic resin in which an organic pigment is dispersed is provided on a substrate, and organic pigments of red, green, and blue are used as the organic pigment.

  Among these pixel portions, as the blue organic pigment for forming the blue pixel portion, ε-type copper phthalocyanine pigment (CI Pigment Blue 15: 6) is generally used, and the color is adjusted as necessary. Therefore, a small amount of purple organic pigment dioxazine violet pigment (CI Pigment Violet 23) is used in combination.

  The organic pigment used to create the color filter has characteristics that are completely different from those of conventional general-purpose applications. Specifically, it makes the display image of the liquid crystal display device clearer (higher contrast) or the same display screen. There is a demand for making the image brighter (higher brightness). In order to meet such demands, powdered organic pigments refined by various methods are frequently used.

  In Patent Document 1, as an organic pigment for forming a blue pixel portion of a color filter, a refined organic pigment excellent in various resistances, in which a pigment, a water-soluble inorganic salt, and a water-soluble organic solvent are mechanically kneaded is proposed. Has been. Here, first, a copper phthalocyanine pigment, a water-soluble inorganic salt, and a water-soluble organic solvent are mechanically kneaded to obtain a refined ε-type copper phthalocyanine pigment, which is separately dioxazine violet pigment, a water-soluble inorganic salt, and a water-soluble organic solvent. A color filter coloring composition is prepared by obtaining a finely divided dioxazine violet pigment obtained by mechanically kneading and using these together. However, in such mechanical kneading, it has been difficult to satisfy the above-described requirements with any powdered organic pigment.

  In Patent Document 2, α-type copper phthalocyanine pigment and dioxazine violet pigment are mechanically kneaded with a water-soluble inorganic salt and a water-soluble organic solvent in the presence of a small amount of ε-type copper phthalocyanine pigment (seed). A fine pigment mixture comprising an ε-type copper phthalocyanine pigment and a dioxazine violet pigment is obtained, and a color filter coloring composition is prepared therefrom. However, since this method is also mechanical kneading as in Patent Document 1, it was still difficult to satisfy the previous requirements with the obtained powdered organic pigment.

  Further, in Patent Document 3, after a mixture of crude copper phthalocyanine and dioxazine violet pigment is subjected to an acid slurry treatment, the mixture is treated with a water-soluble inorganic salt and a water-soluble organic solvent in the presence of a trace amount of ε-type copper phthalocyanine pigment (seed). And a finely divided pigment mixture composed of an ε-type copper phthalocyanine pigment and a dioxazine violet pigment, and a color filter coloring composition is prepared therefrom. However, even with this method, it was still difficult to satisfy the previous requirements with the obtained powdered organic pigment.

Japanese Patent Laid-Open No. 7-13016 (claims on the second page, paragraph number 0011 on the third page, paragraph number 0031 on the fifth page, etc.) JP 2001-288385 A (2nd page claims, third page paragraph numbers 0013 to 0014, fourth page paragraph numbers 0024 to fifth page paragraph numbers 0027, etc.) JP 2002-80745 A (page 2 claims, page 5 paragraph number 0017 to page 7 paragraph number 0029, page 8 paragraph numbers 0038 to 0039, page 9 paragraph numbers 0044 to 0045, page 10 Page paragraph number 0062 etc.)

  An object of the present invention is to obtain a color filter capable of obtaining a high-brightness liquid crystal display device with high contrast at which a display image can be clearly displayed and a brighter display screen, and a blue pigment composition from which the color filter is obtained.

  The present inventors diligently studied the composition of the refined pigment composition containing an ε-type copper phthalocyanine pigment and a dioxazine violet pigment from the viewpoint of the average particle diameter of each. As a result, the main ε-type copper phthalocyanine pigment is fixed, and for the dioxazine violet pigment used in a small amount, a primary pigment average particle size smaller than that of the ε-type copper phthalocyanine pigment is used. Thus, it has been found that a color filter with higher contrast and higher brightness than before can be obtained, and the present invention has been completed.

That is, the present invention provides a blue pigment composition for a color filter comprising an ε-type copper phthalocyanine pigment having an average primary particle diameter of 30 to 70 nm and a dioxazine violet pigment having an average primary particle diameter of 15 to 40 nm. To do.
The present invention also provides a color filter containing the above blue pigment composition for a color filter in a blue pixel portion.

  The blue pigment composition of the present invention has higher average contrast and higher particle size than the conventional one because the latter among the ε-type copper phthalocyanine pigment and dioxazine violet pigment has a smaller average particle size of primary particles than the conventional one. There is a particularly remarkable effect that a color filter capable of obtaining a liquid crystal display device with luminance can be provided.

  The blue pigment composition of the present invention is a mixture containing an ε-type copper phthalocyanine pigment and a dioxazine violet pigment as essential components. In the present invention, the ε-type copper phthalocyanine pigment has an average primary particle diameter of 30 to 70 nm, and the dioxazine violet pigment has an average primary particle diameter of 15 to 40 nm.

  Here, the average particle diameter of the primary particles of the pigment in the present invention is 50 of the primary particles of the pigment constituting the aggregate on the two-dimensional image obtained by photographing the particles in the field of view with a transmission electron microscope or a scanning electron microscope. For each piece, the longer diameter (major diameter) is obtained and averaged.

The greatest feature of the blue pigment composition of the present invention is that the dioxazine violet pigment contained therein is finer than the conventional level and that the dioxazine violet pigment is finer than the ε-type copper phthalocyanine pigment. is there. Hereinafter, a dioxazine violet pigment having an average primary particle size of 15 to 40 nm is referred to as a refined dioxazine violet pigment.

This refined dioxazine violet pigment can be obtained, for example, by refining a needle-shaped dioxazine violet pigment.

The acicular crystal dioxazine violet pigment can be obtained, for example, by crystallizing a crude dioxazine violet pigment or a dioxazine violet pigment that is not acicular crystal after dissolving and / or dispersing in a strong acid and taking it out in water. Such needle-shaped dioxazine violet pigments can be easily produced according to Japanese Patent Publication No. 39-16786, Japanese Patent Laid-Open No. 57-168952, and the like.

The crystal conversion operation with a strong acid can be performed by an acid paste method, an acid slurry method, or the like, but it is more preferable to employ the acid slurry method. The acid slurry method is a method of performing crystal conversion through a state in which the pigment is dispersed in sulfuric acid, similar to the method frequently used in the production of copper phthalocyanine pigments.
In such a crystal conversion operation with a strong acid, a crude dioxazine violet pigment or a dioxazine violet pigment that is not a needle crystal is added to a strong acid aqueous solution adjusted to 60 to 80% by mass, especially a strong acid aqueous solution adjusted to 65 to 75% by mass. The strong acid aqueous solution thus obtained can be poured into a large excess of water.

As the strong acid aqueous solution, polyphosphoric acid which is a strong acid can be used in addition to sulfuric acid. Furthermore, the same effect can be obtained in a strong acid system containing an aromatic hydrocarbon sulfonic acid derivative obtained by adding an aromatic hydrocarbon to a sulfuric acid aqueous solution and then once synthesizing an aromatic hydrocarbon sulfonic acid derivative. Can be obtained.

  As the aromatic hydrocarbon, for example, alkylbenzene such as xylene, toluene, trimethylbenzene and the like can be used. The amount of sulfonic acid in a strong acid system containing a sulfonic acid derivative of an aromatic organic solvent is preferably 10 to 30% in terms of mol%, and more preferably 15 to 25%.

The crystal conversion operation with a strong acid may be performed only for crude dioxazine violet pigments or dioxazine violet pigments that are not acicular crystals, but dioxazine violet for crude dioxazine violet pigments or dioxazine violet pigments that are not acicular crystals. A mixture in which a sulfonic acid derivative is used in combination can also be used. By doing so, a dioxazine violet pigment having a needle-like crystal different from the conventional one can be obtained more easily.

The needle-shaped dioxazine violet pigment can be made into a refined dioxazine violet pigment by further refinement by a refinement treatment described later, which is different from the crystal conversion operation with a strong acid. In this case, a well-known and commonly used refinement process can be performed, and among them, a solvent salt milling process is more preferable.

The finely dioxazine violet pigment obtained by this solvent salt milling treatment is more improved in the dispersibility and dispersion stability of the pigment than before the refinement treatment. Therefore, when a photocurable composition prepared from a pigment mixture containing this fine dioxazine violet pigment is used for a blue pixel portion, a color filter blue pixel portion having high brightness, contrast and light transmittance of the coating film is obtained. can get.

  In the present invention, the solvent salt milling treatment means kneading and grinding the acicular crystal dioxazine violet pigment, an inorganic salt, and an organic solvent in the absence of a copper phthalocyanine pigment. Specifically, the dioxazine violet pigment, an inorganic salt, and an organic solvent that does not dissolve the dioxazine violet pigment are charged into a kneader, and kneading and grinding can be performed therein. Examples of the kneading means at this time include kneaders such as a kneader and a mix muller.

  As the inorganic salt, a water-soluble inorganic salt can be suitably used, and examples thereof include sodium chloride, potassium chloride, sodium sulfate and the like. Moreover, it is more preferable to use an inorganic salt having an average particle size of 0.3 to 50 μm. Such an inorganic salt can be easily obtained by pulverizing a normal inorganic salt.

  In obtaining a fine dioxazine violet pigment, the amount of inorganic salt used is preferably 5 to 20 parts of inorganic salt per part of pigment in terms of mass with respect to the dioxazine violet pigment of needle-like crystals, Especially, it is more preferable to set it as 7-15 parts, and it is especially preferable to set it as 8-12 parts. The number of parts of the inorganic salt per part of the pigment is called salt magnification, and the unit is represented by double.

  As the organic solvent, an organic solvent that is water-soluble but does not dissolve the inorganic salt can be suitably used. For example, diethylene glycol, glycerin, ethylene glycol, propylene glycol, liquid polyethylene glycol, liquid polypropylene glycol, 2- (methoxymethoxy) ) Ethanol, 2-butoxyethanol, 2- (isopentyloxy) ethanol, 2- (hexyloxy) ethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether , Dipropylene glycol monomethyl ether, can be used dipropylene glycol or the like.

  The amount of the organic solvent used is not particularly limited, but is preferably 0.01 to 5 parts per part of the pigment in terms of mass.

  The conditions of the solvent salt milling treatment are not particularly limited, but it is preferably performed in a state where the object to be refined is heated, that is, when it is hot, and the temperature during the solvent salt milling treatment is 80 to 120, among others. ° C is more preferred. The time for the solvent salt milling treatment is preferably 3 hours to 20 hours, and more preferably 5 to 15 hours.

In the present invention, needle crystals are obtained by the acid slurry treatment, and the needle crystals are ground by a solvent salt milling treatment, whereby finer pigment particles can be obtained.

  In this way, a mixture containing a finely dioxazine violet pigment, an inorganic salt, and an organic solvent as main components is obtained. By removing the organic solvent and the inorganic salt from this mixture, the fine dioxazine violet pigment is mainly used. A solid product is obtained. Dioxazine violet pigment powder can be obtained by washing, filtering, drying, pulverizing, and the like. As the cleaning method, either water washing or hot water washing can be employed. When the solid is a mixture using a water-soluble inorganic salt and an organic solvent, the organic solvent and the inorganic salt can be easily removed by washing with water.

  As the drying method after the washing and filtration described above, for example, a method of drying in a batch system or a continuous system in which the pigment is dehydrated and / or removed by heating at 80 to 120 ° C. by a heating source installed in a dryer. Etc. Examples of the dryer used at that time include a box-type dryer, a band dryer, and a spray dryer.

Grinding after drying is not an operation to increase the specific surface area of the pigment or to reduce the average particle size of the primary particles, but to use a box dryer or a band dryer to dry the lamp shape, etc. This is done in order to break down the pigment that has become a powder and powder it. Examples of the pulverization method include pulverization methods using a mortar, hammer mill, disk mill, pin mill, jet mill, and the like.

  In this way, the powder of the refined dioxazine violet pigment for the blue pigment composition of the present invention that is optimal for color filters is obtained.

  By using this miniaturized dioxazine violet pigment as a blue pigment for complementary color (toning), the color filter blue pixel portion has a lower luminance (Y value) and contrast reduction rate than the conventional blue pixel portion, High transmittance can be maintained.

In the case where the fine dioxazine violet pigment is used in the color filter blue pixel portion, it is very difficult to cause a defect that a portion having the intended chromaticity and hue and a portion that does not occur are formed in the blue pixel portion. Furthermore, as a result of the visual evaluation, the hue is further reddish compared to the same blue pixel part prepared from a mixture of a conventional dioxazine violet pigment and an ε-type copper phthalocyanine pigment, and a blue color superior in sharpness and brightness is obtained. Present. The spectral transmittance spectrum shifts to the short wavelength side, the light transmittance in the target blue wavelength region of 420 to 500 nm is increased, and the color purity of the blue image is further improved.

  The refined dioxazine violet pigment has high dispersion and dispersion stability of the pigment in the liquid medium, and the blue pigment dispersion described later containing this is also low in viscosity and stable (dispersed in fine particles). In addition, the light-shielding property at 365 nm, which is frequently used when curing a photocurable composition (also referred to as a pigment-dispersed photoresist) for forming a blue pixel portion, which will be described later, containing this fine dioxazine violet pigment is reduced. (Ie, it is highly permeable). Further, it is preferable because the photocuring sensitivity does not decrease and film edge and pattern flow hardly occur during development. Therefore, when a blue pixel part of a color filter is produced using a blue pigment composition containing this fine dioxazine violet pigment, a uniform coating film is formed and all of brightness, contrast and light transmittance are A high color filter can be obtained.

Here, the contrast is the transmitted light intensity when the object to be measured is sandwiched with the polarization directions of the two polarizing plates parallel to each other and the object to be measured is sandwiched with the polarization direction of the two polarizers perpendicular to each other. This is divided by the transmitted light intensity and is also called depolarization.

If a dioxazine violet pigment deviating from the average particle diameter of the primary particles is used, the dispersibility and dispersion stability of the pigment are reduced, and a mixture of dioxazine violet pigment and blue pigment is used due to reaggregation of the pigment. The pigment dispersion prepared in this manner, the flowability of the photocurable composition containing the pigment dispersion, the storage stability, and the coating properties on the transparent substrate for forming the color filter blue pixel portion are reduced. Since all of brightness, contrast, and light transmittance are lowered, it is not preferable.

  On the other hand, an ε-type copper phthalocyanine pigment (CI Pigment Blue 15: 6) is used as a blue pigment in the present invention. When forming a color filter blue pixel portion, an ε-type copper phthalocyanine pigment is used from the viewpoint of heat resistance, light resistance and coloring power. In the present invention, an ε-type copper phthalocyanine pigment having an average primary particle diameter of 30 to 70 nm is used. Such an ε-type copper phthalocyanine pigment can be easily produced by a known and commonly used production method.

  The blue pigment composition for a color filter of the present invention can be prepared by including an ε-type copper phthalocyanine pigment having an average primary particle diameter of 30 to 70 nm and a fine dioxazine violet pigment so as to develop a blue color. As described above, it is preferable that the primary particles of the ε-type copper phthalocyanine pigment are used in combination so that the average particle diameter is larger than that of the dioxazine violet pigment used together.

  The blue pigment composition of the present invention may contain an ε-type copper phthalocyanine pigment and a refined dioxazine violet pigment, but for example, an ε-type copper phthalocyanine pigment and a refined dioxazine violet pigment so as to develop a blue color. And are mixed. ε-type copper phthalocyanine pigment: refined dioxazine violet pigment (mass ratio), which can be prepared by including both at 99: 1 to 50:50, preferably 99: 1 to 75:25.

  The blue pigment composition of the present invention containing both pigments in the preferred mass ratio effectively suppresses light transmission in the wavelength region of 500 to 550 nm without impairing light transmission in the blue wavelength region of 420 to 500 nm. This is preferable in that the color purity of the color filter blue pixel portion can be improved.

The color filter blue pixel portion prepared using the blue pigment composition of the present invention is more liquid crystal display than that prepared using a mixture of a conventional dioxazine violet pigment and an ε-type copper phthalocyanine pigment. The decrease in brightness is smaller, and the light transmittance in the target blue wavelength region of 420 to 500 nm is also higher.

Blue pigment compositions of the present invention is preferably as little as possible contain ionic ingredients, specific conductivity of the washing water is 50 [mu] S / cm ² or less, preferably at 20 [mu] S / cm ² or less.

The blue pigment composition of the present invention preferably has a BET specific surface area of 80 to 120 m ² / g in the nitrogen adsorption method. Within this range, the dispersibility and dispersion stability of the pigment will decrease, the stability of the pigment dispersion will decrease due to reaggregation of the pigment, and the brightness and contrast of the coating film in the color filter blue pixel area will decrease. It is preferable because it is difficult for harmful effects such as these to occur.

The BET specific surface area in this nitrogen adsorption method can be measured according to JIS Z 8830-1990 (Method for measuring specific surface area of powder by gas adsorption).

In addition, the ε-type copper phthalocyanine pigment and the refined dioxazine violet pigment are known and commonly used pigment derivatives, dispersants, surfactants and surfactants in any process from the stage of these raw materials to the preparation of the blue pigment composition of the present invention. It may be a surface-treated pigment in which the surface of pigment particles is coated with various surface treatment agents such as synthetic resins.

  Examples of the pigment derivative at this time include a sulfonic acid derivative or a metal salt thereof, a sulfonamide derivative, and a phthalimidomethyl derivative. Examples of the synthetic resin include an epoxy resin, an acrylic resin, and an amino resin.

  In addition, the blue pigment composition of the present invention may be used alone as a blue pigment for a color filter blue pixel portion, and if necessary, a blue organic pigment other than the above-described ε-type copper phthalocyanine pigment and dioxazine violet pigment. You may use together. When the blue organic pigment other than the ε-type copper phthalocyanine pigment and dioxazine violet pigment is used in combination with the blue pigment composition of the present invention, the blue pigment composition of the present invention is mainly used. This is preferable in that the color filter can have more excellent characteristics.

  The blue pigment composition of the present invention can be used for preparing a color filter blue pixel portion and a blue pigment for forming the blue pixel portion by a conventionally known method. In producing a color filter blue pixel portion using the blue pigment composition of the present invention, a pigment dispersion method can be suitably employed.

A typical method in this method is a photolithography method, in which a photocurable composition to be described later is applied to a surface of a transparent substrate for a color filter on which a black matrix is provided, followed by heat drying (prebaking). After that, pattern exposure is performed by irradiating ultraviolet rays through a photomask to cure the photo-curable compound at a location corresponding to the pixel portion, and then developing the unexposed portion with a developer to remove non-pixels. This is a method of removing the portion and fixing the pixel portion to the transparent substrate. In this method, a pixel portion made of a cured colored film of a photocurable composition is formed on a transparent substrate.

  A photocurable composition to be described later is prepared for each color of red, green, and blue, and a color filter having colored pixel portions of red, green, and blue at predetermined positions is manufactured by repeating the above-described operation. I can do it. As described above, a blue pixel portion and a blue pigment for forming the blue pixel portion are prepared from the blue pigment composition of the present invention. In addition, in order to prepare the photocurable composition for forming a red pixel part and a green pixel part, a well-known and usual red pigment and green pigment can be used.

  Examples of the pigment for forming the red pixel portion include C.I. I. Pigment Red 177, 209, 254, and the like are pigments for forming the green pixel portion, for example, C.I. I. Pigment Green 7, 10, 36, 47 and the like. A yellow pigment can be used in combination for forming the red pixel portion and the green pixel portion. Thereafter, if necessary, the entire color filter can be heat-treated (post-baked) in order to thermally cure the unreacted photocurable compound.

  Examples of a method for applying a photocurable composition described later on a transparent substrate such as glass include a spin coat method, a roll coat method, and an ink jet method.

  Although the drying conditions of the coating film of the photocurable composition apply | coated to the transparent substrate differ also with the kind of each component, a compounding ratio, etc., they are 50-150 degreeC and are about 1 to 15 minutes normally. This heat treatment is generally referred to as “pre-baking”. Moreover, as light used for photocuring of a photocurable composition, it is preferable to use the ultraviolet-ray of a wavelength range of 200-500 nm, or visible light. Various light sources that emit light in this wavelength range can be used.

  Examples of the developing method include a liquid piling method, a dipping method, and a spray method. After exposure and development of the photocurable composition, the transparent substrate on which the necessary color pixel portion is formed is washed with water and dried. The color filter thus obtained is subjected to heat treatment (post-baking) at 100 to 280 ° C. for a predetermined time by a heating device such as a hot plate or an oven to remove volatile components in the colored coating film, and at the same time, light The unreacted photocurable compound remaining in the cured colored film of the curable composition is thermally cured to complete the color filter.

  The photocurable composition for forming the blue pixel portion of the color filter includes the blue pigment composition of the present invention, a dispersant, a photocurable compound, and an organic solvent as essential components, and if necessary, heat It can prepare by mixing these using a plastic resin. When the colored resin film that forms the blue pixel portion requires toughness that can withstand baking, etc. performed in the actual production of a color filter, a photocurable compound is used in preparing the photocurable composition. In addition, it is essential to use this thermoplastic resin in combination. When a thermoplastic resin is used in combination, it is preferable to use an organic solvent that dissolves it.

  As a method for producing the photocurable composition, the blue pigment composition of the present invention, an organic solvent and a dispersant are used as essential components, and these are mixed and stirred and dispersed so as to be uniform. After preparing a pigment dispersion for forming the blue pixel portion of the color filter, the photocurable composition is added thereto by adding a photocurable compound and, if necessary, a thermoplastic resin or a photopolymerization initiator. The method of making a product is common.

  Examples of the dispersant include Dispervic 130, Dispersic 161, Dispersic 162, Dispersic 163, Dispersic 170 manufactured by Big Chemie, Fuka 46 and Fuka 47 manufactured by Efka, and the like. Further, a leveling agent, a coupling agent, a cationic surfactant, and the like can be used together.

  Examples of the organic solvent include aromatic solvents such as toluene, xylene and methoxybenzene, acetate solvents such as ethyl acetate and butyl acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, and ethoxyethyl propionate. Propionate solvents such as methanol, ethanol solvents such as ethanol, butyl cellosolve, ether solvents such as propylene glycol monomethyl ether, diethylene glycol ethyl ether, diethylene glycol dimethyl ether, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, hexane, etc. Aliphatic hydrocarbon solvents, N, N-dimethylformamide, γ-butyrolactam, N-methyl-2-pyrrolidone, a Phosphorus, nitrogen compound-based solvent such as pyridine, .gamma.-lactone solvents butyrolactone, carbamic acid esters such as a mixture of 48:52 of methyl carbamate and ethyl carbamate acid. As the organic solvent, polar solvents such as propionate-based, alcohol-based, ether-based, ketone-based, nitrogen compound-based, and lactone-based solvents that are water-soluble are particularly preferable. When a water-soluble organic solvent is used, water can be used in combination.

  Examples of the thermoplastic resin used for preparing the photocurable composition include urethane resins, acrylic resins, polyamic acid resins, polyimide resins, styrene maleic acid resins, styrene maleic anhydride resins, and the like. It is done.

Examples of the photocurable compound include 1,6-hexanediol diacrylate, ethylene glycol diacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, bis (acryloxyethoxy) bisphenol A, 3-methylpentanediol di Multifunctional with relatively low molecular weight such as bifunctional monomer such as acrylate, trimethylol propaton triacrylate, pentaerythritol triacrylate, tris (2-hydroxyethyl) isocyanate, dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate Monofunctional, polyester acrylate, polyurethane acrylate, polyether acrylate, etc. It is.

Examples of the photopolymerization initiator include acetophenone, benzophenone, benzyldimethylketanol, benzoyl peroxide, 2-chlorothioxanthone, 1,3-bis (4′-azidobenzal) -2-propane, 1,3-bis (4 '-Azidobenzal) -2-propane-2'-sulfonic acid, 4,4'-diazidostilbene-2,2'-disulfonic acid and the like.

Using each of the materials as described above, 300 to 1000 parts of an organic solvent and 0 to 100 parts of a dispersant are made uniform in terms of mass per 100 parts of the blue pigment composition of the present invention. The pigment dispersion can be obtained by stirring and dispersing. Next, in this pigment dispersion, the total amount of the thermoplastic resin and the photocurable compound is 3 to 20 parts per 1 part of the blue pigment composition of the present invention, and the photopolymerization is 0.05 to 3 parts per 1 part of the photocurable compound. A photocurable composition for forming a color filter blue pixel portion can be obtained by adding an initiator and, if necessary, further an organic solvent, and stirring and dispersing so as to be uniform.

As the developer, a publicly known and commonly used organic solvent or alkaline aqueous solution can be used. In particular, when the photocurable composition contains a thermoplastic resin or a photocurable compound, and at least one of them has an acid value and exhibits alkali solubility, the color filter can be washed with an alkaline aqueous solution. This is effective for forming the blue pixel portion.

Among the pigment dispersion methods, the method for producing the color filter blue pixel portion by the photolithography method has been described in detail, but the color filter blue pixel portion prepared using the blue pigment composition of the present invention is a different electrodeposition method. The color filter may be manufactured by forming a blue pixel portion by a method such as a transfer method, a micelle electrolysis method, or a PVED (Photovoltaic Electrodeposition) method.

  The color filter uses a red pigment, a green pigment, and a photocurable composition of each color obtained by using the blue pigment composition of the present invention, and encloses a liquid crystal material between a pair of parallel transparent electrodes, and is transparent. The electrode is divided into discontinuous fine sections, and any one of red (R), green (G), and blue (B) is assigned to each of the fine sections divided into a lattice by the black matrix on the transparent electrode. It can be obtained by providing a color filter coloring pixel portion selected from colors alternately in a pattern, or by forming a color filter coloring pixel portion on a substrate and then providing a transparent electrode.

  The blue pigment composition of the present invention is optimal for forming the blue pixel portion of the color filter as described above, but is excellent in sharpness and lightness, and further in storage stability and heat resistance due to the dioxazine violet pigment. In addition, it is a blue pigment composition having a more reddish hue, and for color filters, paints, plastics (resin molded products), printing inks, rubber, leather, textile printing, electrostatic charge image developing toners, and inkjet recording. The present invention can also be applied to coloring inks and thermal transfer inks.

  Hereinafter, the present invention will be described in detail with reference to production examples, examples, and comparative examples. The present invention is not limited to these examples. Unless otherwise specified, both “part” and “%” are based on mass.

Synthesis Example 1 (Production of dioxazine violet pigment by acid slurry treatment)
In a reaction vessel, 2,610 parts of 98% sulfuric acid, “Sumitone (registered trademark) Fast Violet RL-4R base” (dioxazine violet pigment manufactured by Sumitomo Chemical Co., Ltd., equivalent to CI Pigment Violet 23). 5 parts were added and reacted at 85 ° C. for 4 hours, and then about 950 parts of water was added to adjust the sulfuric acid concentration to 70%. Next, 450 parts of “Sumitone (registered trademark) Fast Violet RL-4R base” was gradually added under stirring of this 70% sulfuric acid solution, and after confirming that it was completely dissolved ( The reaction solution was taken out in 27,000 parts of water, filtered, washed, dried and pulverized to obtain a dioxazine violet pigment having needle-like crystals.

Synthesis Example 2 (Production of dioxazine violet pigment by acid slurry treatment)
A reaction vessel was charged with 4,000 parts of 98% sulfuric acid, 126 parts of water, and 195 parts of xylene and reacted at 80 ° C. for 3 hours to produce xylene sulfonic acid. After cooling, about 1,050 parts of water was added thereto. Was added to adjust the sulfuric acid concentration to 70%. Next, under stirring of this aqueous solution of xylene sulfonic acid, 400 parts of “Sumitone (registered trademark) Fast Violet RL-4R base” was gradually added, and after confirming that the solution was completely dissolved ( The reaction solution was taken out in 27,000 parts of water, filtered, washed, dried and pulverized to obtain a needle-shaped dioxazine violet pigment.

Synthesis Example 3 (Production of pigment composition containing dioxazine violet pigment and copper phthalocyanine pigment by acid slurry treatment)
10 parts of “Sumitone (registered trademark) Fast Violet RL-4R base”, 1000 parts of 70% sulfuric acid, “Fastogen (registered trademark) Blue EPC” (crude ε-type copper phthalocyanine pigment manufactured by Dainippon Ink & Chemicals, Inc. C.I. Pigment Blue 15: 6 equivalent, average particle diameter of primary particles is about 200 nm.) After gradually adding 75 parts of the mixture and confirming that it was completely dissolved (the one obtained here is referred to as a solution). The solution was taken out in 7000 parts of water, filtered, washed, dried and pulverized to obtain a pigment composition containing a dioxazine violet pigment and a copper phthalocyanine pigment. The washing was performed until the specific conductivity of the washing water became ²⁰ μS / cm ² or less.

Production Example 1 (Production of refined dioxazine violet pigment)
40 parts of the acicular crystal dioxazine violet pigment obtained in Synthesis Example 1, 400 parts of crushed sodium chloride, and 80 parts of diethylene glycol were charged into a double-arm kneader and kneaded at 100 to 110 ° C. for 8 hours. After kneading, the mixture was taken out in 100 parts of a 1% hydrochloric acid aqueous solution at 80 ° C., stirred for 1 hour, filtered, washed with hot water, dried and pulverized to obtain a fine dioxazine violet pigment. The washing was performed until the specific conductivity of the washing water became ²⁰ μS / cm ² or less.

  The average particle diameter of the primary particles of the fine dioxazine violet pigment was 20 nm when treated as described above based on the results measured with a transmission electron microscope JEM-2010 (manufactured by JEOL Ltd.). It was.

Production Example 2 (Production of refined dioxazine violet pigment)
Instead of the acicular crystal dioxazine violet pigment obtained in Synthesis Example 1, the same operation as in Production Example 1 was carried out except that the same amount of the acicular crystal dioxazine violet pigment obtained in Synthesis Example 2 was used. Thus, a refined dioxazine violet pigment was obtained. The washing was performed until the specific conductivity of the washing water became ²⁰ μS / cm ² or less. The average particle diameter of the primary particles of the fine pigment was 30 nm from the same measurement / treatment as described above.

9 parts of “Fastogen (registered trademark) Blue EP-CF” (ε-type copper phthalocyanine pigment manufactured by Dainippon Ink and Chemicals, Inc., CI Pigment Blue 15: 6, average particle diameter of primary particles of about 50 nm); One part of the refined dioxazine violet pigment obtained in Production Example 1 was mixed with powder to obtain a blue pigment composition (a). This blue pigment composition (a) had a specific conductivity of washing water of 20 μS / cm ² or less, and the average primary particle size of the blue pigment composition (a) was about 45 nm.

A blue pigment was prepared in the same manner as in Example 1 except that the same amount of the fine dioxazine violet pigment obtained in Production Example 2 was used instead of the fine dioxazine violet pigment obtained in Production Example 1. A composition (b) was obtained. The blue pigment composition (b) had a washing water specific conductivity of 20 μS / cm ² or less, and the average primary particle size of the blue pigment composition (b) was about 48 nm.

Comparative Example 1
90 parts of a pigment composition containing the dioxazine violet pigment obtained in Synthesis Example 3 and a copper phthalocyanine pigment, 10 parts of “Fastogen (registered trademark) Blue EP-CF” as a seed, phthalimidomethylated copper phthalocyanine (pigment derivative) 3 parts, 300 parts of crushed sodium chloride and 110 parts of diethylene glycol were charged into a double-arm kneader and kneaded at 100 to 110 ° C. for 8 hours. After kneading, the mixture was taken out in a 2% aqueous sulfuric acid solution at 80 ° C., stirred for 1 hour, filtered, washed with hot water, dried and pulverized to obtain a blue pigment composition (c). This blue pigment composition (b) had a specific conductivity of washing water of 20 μS / cm ² or less, and the average primary particle size of the blue pigment composition (c) was about 50 nm.

Comparative Example 2
Instead of the refined dioxazine violet pigment of Production Example 1, the same amount of “Hostaperm (registered trademark) Violet RL-NF” (Clariant dioxazine violet pigment, CI Pigment Violet 23) was used. Performed the same operation as in Example 1 to obtain a blue pigment composition (d).

Comparative Example 3
Instead of the refined dioxazine violet pigment of Production Example 1, “Fastogen (Registered Trademark) Super Blue 6070S” (Indanthrone Blue Pigment manufactured by Dainippon Ink and Chemicals, Inc., CI Pigment Blue 60) A blue pigment composition (e) was obtained in the same manner as in Example 1 except that the same amount was used.

In each of the blue pigment compositions of Examples 1-2 and Comparative Examples 1-3, the BET specific surface area in the nitrogen adsorption method was in the range of 80 to 120 m ² / g.

Using the blue pigment composition (a) obtained in Example 1 as a blue pigment, a color filter blue pixel portion was produced by a photolithography method.
As a method for producing a blue pixel portion of a color filter, 10 parts of a blue pigment, 2.5 parts of N, N′-dimethylformamide (organic solvent), 6.78 parts of Dispersic 161 (dispersant manufactured by BYK Chemie), Eucer ester EEP 80.80 parts (organic solvent manufactured by Union Carbide Co.) were added with 0.5 mmφ sepul beads and dispersed for 1 hour with a paint conditioner (manufactured by Toyo Seiki Co., Ltd.) to obtain a pigment dispersion (colored paste). 75.00 parts of this pigment dispersion and Aronix M7100 (polyester acrylate resin, manufactured by Toa Gosei Chemical Co., Ltd., corresponding to a photocurable compound) 5.50 parts, KAYARAD DPHA (dipentaerylate hexaacrylate, 5.00 parts by Nippon Kayaku Co., Ltd., corresponding to a photocurable compound.) 5.00 parts, KAYACURE BP-100 (benzophenone, Nippon Kayaku Co., Ltd., corresponding to a photopolymerization initiator) 1.00 parts. 13.5 parts of Euker ester EFP was stirred with a dispersion stirrer to obtain a photocurable composition for forming a blue pixel part of a color filter. The composition was applied to 1 mm thick glass so as to have a dry film thickness of 1 μm.
Next, pattern exposure with ultraviolet rays was performed through a photomask, and then the unexposed portion was washed with an organic solvent to produce a color filter blue pixel portion.

  The same operation as in Example 1 except that the same amount of the blue pigment composition (b) obtained in Example 2 was used as the blue pigment instead of the blue pigment composition (a) obtained in Example 1. To produce a color filter blue pixel portion.

Comparative Example 4
The same operation as in Example 1 except that the same amount of the blue pigment composition (c) obtained in Comparative Example 1 was used as the blue pigment instead of the blue pigment composition (a) obtained in Example 1. To produce a color filter blue pixel portion.

Comparative Example 5
The same operation as in Example 1 except that the same amount of the blue pigment composition (d) obtained in Comparative Example 2 was used as the blue pigment instead of the blue pigment composition (a) obtained in Example 1. To produce a color filter blue pixel portion.

Comparative Example 6
The same operation as in Example 1 except that the same amount of the blue pigment composition (e) obtained in Comparative Example 3 was used as the blue pigment instead of the blue pigment composition (a) obtained in Example 1. To produce a color filter blue pixel portion.

  The brightness | luminance of the coating film of the color filter blue pixel part of manufactured Examples 3-4 and Comparative Examples 4-6, contrast, and the light transmittance were evaluated, respectively. The results are shown in Tables 1 and 2.

Luminance (Y value) is calculated by calculating the chromaticity coordinate x value and the y value by F10 light source colorimetry using MCPD-3000 (manufactured by Otsuka Electronics Co., Ltd.). The Y value in CIE color development system chromaticity was measured by combining the values. Here, it was evaluated that the visual brightness was higher as the luminance (Y value) was higher.
In contrast, the color filter blue pixel portion was installed between two polarizing plates, a light source was installed on one side, and a CCD camera was installed on the opposite side, and luminance was measured. It was calculated from the ratio of luminance (transmitted light intensity) between when the polarization axis was parallel and when it was vertical.

The light transmittance is a wavelength at which the light transmittance of the spectral transmittance spectrum is maximized using the first-type spectrophotometer (the aforementioned spectrophotometer) defined in JIS Z 8722 for the color filter blue pixel portion ( The light transmittance (Tmax) at λmax = 463 nm was measured.

Table 1

          Table 2

  As is apparent from the results of Tables 1 and 2, using the blue pigment composition of the present invention, wherein the primary particles of copper phthalocyanine pigment and dioxazine violet pigment are different in average particle size and the latter is smaller. In the obtained color filter blue pixel portion of Examples 3 to 4, the photocurable composition having extremely weak pigment aggregation and excellent dispersibility and dispersion stability can be prepared in a shorter time, and the blue pixel obtained therefrom The part had high light transmittance as well as the brightness and contrast of the coating film.

  On the other hand, in the color filter blue pixel portion of Comparative Examples 4 to 5 obtained using a conventional blue pigment composition in which the average particle diameters of the copper phthalocyanine pigment, the dioxazine violet pigment, and the primary particles are the same, the aggregation of the pigment However, the blue pixel portion obtained therefrom was low not only in the brightness and contrast of the coating film but also in the light transmittance. In the blue pigment composition used in Comparative Example 3, the operation of “take out the mixture into a 2% aqueous sulfuric acid solution at 80 ° C. after kneading and stir for 1 hour” is performed by the operation “100% 1% aqueous hydrochloric acid solution at 80 ° C. after kneading”. The color filter blue pixel part was produced and evaluated in the same manner as in Comparative Example 4 using the blue pigment composition obtained in the same manner as in Comparative Example 2 except that the mixture was taken out into the part and replaced with “stirring for 1 hour”. However, it was equivalent to the result of Comparative Example 4.

From the above, it can be seen that when the blue pigment composition of the present invention is used, a color filter blue pixel portion having high brightness, contrast and light transmittance of the coating film can be obtained. In particular, the luminance was improved by about 3 points (high luminance value) compared with the conventional one, and the effect was remarkable.
Therefore, the blue pigment composition of the present invention is optimal for forming a color filter blue pixel portion.

Claims (5)

A blue pigment composition for a color filter comprising an ε-type copper phthalocyanine pigment having an average primary particle diameter of 30 to 70 nm and a dioxazine violet pigment having an average primary particle diameter of 15 to 40 nm. Dioxazine violet pigment obtained by subjecting dioxazine violet pigment having an average primary particle size of 15 to 40 nm to acid slurry treatment of crude dioxazine violet pigment and then hot solvent salt milling at a salt magnification of 7 to 15 times The blue pigment composition for a color filter according to claim 1. Dioxazine violet pigment obtained by subjecting crude dioxazine violet pigment to acid slurry treatment and then hot solvent salt milling at a salt magnification of 8 to 12 times, and ε-type copper phthalocyanine having an average primary particle size of 30 to 70 nm The blue pigment composition for a color filter according to claim 1 or 2, which is mixed with a pigment. The blue pigment composition for a color filter according to claim 1, wherein ε-type copper phthalocyanine pigment: dioxazine violet pigment (mass ratio) = 99: 1 to 75:25. The color filter which contains the blue pigment composition for color filters as described in any one of Claims 1-4 in a blue pixel part.