JP2000009926A - Color paste for color filter and color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress and prevent display failures of a liquid crystal display by decreasing dissolution of impurities from a color filter to a liquid crystal. SOLUTION: The amt. of substances which dissolve from pigments to the liquid crystal to cause display failures is decreased. More particularly, pigments having <=3% weight reduction when extracted with methanol are used. Or, pigments having <=0.1% add. amt. of long-chain alkylamines are used. Or, pigments having <=0.1% add. amt. of long-chain alkylacetoamides are used. Or, pigments having <=0.1% add. amt. of phthalocyanine pigment derivs. are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color paste for a color filter and a color filter using the color paste. More specifically, the present invention relates to a color paste which is less likely to cause display unevenness in a liquid crystal display. The present invention relates to a color filter for a liquid crystal display using a color paste.

[0002]

2. Description of the Related Art In order to color a liquid crystal display, a color filter in which pixels of three colors of R (red), G (green) and B (blue) are arranged in a line or mosaic on a transparent substrate. Used. For example, a TFT (thin film transistor) color liquid crystal display, which is widely used at present, is a panel in which liquid crystal is sealed between a transparent glass substrate on which a color filter is formed and a transparent glass substrate on which a TFT is formed. Composed of light sources. When light emitted from the backlight passes through the liquid crystal panel, an image is displayed by controlling the transmittance of the light by the voltage applied to the liquid crystal. Since each pixel needs to be similar to the chromaticity characteristics of the CRT phosphor, the pigments are selected to match the light transmission characteristics of the backlight and the liquid crystal display element, and two or more pigments are toned at a fixed ratio. Often used. For example, the color filter R
The (red) pixel is used by selecting two or more kinds of red, orange, and yellow pigments and toning them at a fixed ratio. Similarly G
(Green) pixels are also used by selecting two or more kinds of green, orange, and yellow pigments and toning them. The pigment is selected in consideration of such required chromaticity characteristics, and ionic impurities are not considered. Generally, commercially available pigments contain many ionic impurities such as alkali metals such as sodium, potassium, calcium and barium, and halogens such as chlorine and bromine.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art. It is an object of the present invention to provide a color paste with reduced ionic impurities. An object of the present invention is to produce a color filter having excellent display performance.

[0004]

The object of the present invention is achieved by the following constitution. (1) a color paste for a color filter, which employs a pigment whose weight loss upon extraction with methanol is 3% or less, and (2) a long-chain alkylamine addition amount of 0.1% or less. (3) a color paste for a color filter, wherein the added amount of a long-chain alkylacetamide is 0.1% or less; and (4) an added amount of a phthalocyanine pigment derivative is 0.1%. A color paste for a color filter characterized by being 1% or less; (5) a color filter characterized in that the amount of long-chain alkylamine added is 0.05% or less relative to the colored film; and (6) a length. A color filter, wherein the addition amount of the chain alkylacetamide is 0.05% or less based on the colored film; 0.0 amount of body with respect to colored film
A color filter characterized by being 5% or less,
(8) The color paste for a color filter according to any one of the above (1) to (4), wherein the pigment is a green pigment or a blue pigment having a phthalocyanine skeleton. ), (2), (3),
(4) A color filter characterized by being a colored film comprising the color paste according to any one of (8) and (10) a green pigment or a blue pigment having a phthalocyanine skeleton as a pigment contained in at least one coloring layer. A color filter according to any one of the above (5), (6) and (7), which is a pigment;
(6) A liquid crystal display device using the color filter according to any one of (7), (9), and (10).

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The color layer of the color filter
Three layers of primary colors red, green and blue or cyan, magenta and yellow are provided. If multi-color is acceptable,
Color filters consisting of red and magenta are also possible.

As a coloring agent used in the coloring layer of the present invention, an organic pigment can be suitably used. Examples of pigments used include Pigment Red 9, 9 as red.
7, 122, 123, 149, 168, 177, 18
0, 192, 215, etc .; Pigment Green 7, 36 as green; and Pigment Blue 15, 2 as blue.
2, 60, 64 and the like are generally used. Addition of a yellow pigment or the like to adjust the color tone of green or red is appropriately permitted. Pigment Yellow 1 is an example of a yellow pigment.
3, 17, 20, 24, 83, 86, 93, 95, 10,
9, 110, 117, 125, 137, 138, 13
9, 147, 148, 153, 154, 166, 16
8, 185 and the like, but are not limited thereto.

It is important that the pigment used in the present invention has a weight loss of 3% or less when extracted with methanol. The details of the substance extracted with methanol are unknown, but are presumed to be a pigmentation additive for the purpose of preventing the binding of pigment powder, a dispersant for improving dispersibility, and impurities. Pigments are inherently insoluble in solvents, so substances extracted into solvents may not be fully pigmented or partially broken pigments or additives that are not strongly bonded to pigments. It is considered a dispersant. When a pigment whose weight loss upon extraction with methanol exceeds 3% is used, display unevenness due to abnormal threshold voltage is likely to occur. The reduction rate is more preferably 2.5% or less, and most preferably 2% or less.

[0008] Pigment Green 7, a green pigment in which hydrogen of copper phthalocyanine is replaced with chlorine, and Pigment Green 36, a green pigment in which hydrogen of copper phthalocyanine is replaced with chlorine and bromine, include chlorination or chlorination and bromine in the pigment production process. Once the pigment is formed, it is easy to decompose the formed pigment and easily form impurities other than the pigment.Furthermore, bromide and chlorinated compounds have strong dissolving power in the liquid crystal and are ionized in the liquid crystal to display on the liquid crystal display. Since the performance is easily adversely affected, the effect of the present invention is great. In addition, a decomposition product of copper phthalocyanine tends to adversely affect the liquid crystal, and a blue pigment having a copper phthalocyanine skeleton, Pigment Blue 1
5, the effect of the present invention is also large.

The pigment dispersing material is necessary for finely dispersing the pigment to form a color paste. The pigment dispersing agent is added to the pigment in advance and then formed into a color paste, or when the color paste is formed, the color paste is added to the color paste. Is added. Long-chain alkylamines, long-chain alkylacetamides, and phthalocyanine pigment derivatives have a large pigment dispersing effect. However, since these tend to cause display defects of the liquid crystal display device, it is preferable to use an alternative material or to minimize the amount of addition.

The long-chain alkylamine of the present invention has 5 carbon atoms.
From 30. Further, the long-chain alkylacetamide of the present invention has 5 to 30 carbon atoms. A long-chain alkylamine or a long-chain alkylacetamide may be used as a pigment dispersing material, but when these are dissolved in a liquid crystal, display abnormalities are likely to occur. Examples of long chain alkylamines having 5 to 30 carbon atoms include stearylamine, palmitoylamine, myristoylamine, lauroylamine, and the like. In the present invention, it is important that the addition amount of the long-chain alkylamine to the color paste for a color filter is 0.1% or less, and the addition amount is more preferably 0.05% or less, and more preferably 0.02% or less. % Is most preferred.

The long-chain alkylamine, long-chain alkylacetamide, and phthalocyanine pigment derivative contained in the colored layer that has been coated with the color paste and cured are eluted into the liquid crystal of the liquid crystal display element, causing display defects.

According to the present invention, in a color filter having pixels composed of colored layers provided in a desired pattern for each color in an arbitrary number of colors, the amount of long-chain alkylamine added is 0.05% with respect to the colored layers. It is important that the content is not more than 0.03%, more preferably not more than 0.03%, and most preferably not more than 0.01%.

Examples of the long-chain alkylacetamide having 5 to 30 carbon atoms include N-decylacetamide, N-stearylacetamide, N-palmitoylacetamide, N-myristoylacetamide, N-lauroylacetamide and the like. In the present invention, the amount of the long-chain alkylacetamide added to the color paste for a color filter is 0.1%.
It is important that the content is 1% or less.
%, And most preferably 0.02% or less.

According to the present invention, in a color filter having pixels composed of colored layers provided in a desired pattern for each color in an arbitrary number of colors, the amount of long-chain alkylacetamide added is 0.05% with respect to the colored layer. It is important that the content is not more than 0.03%, more preferably not more than 0.03%, and most preferably not more than 0.01%.

The phthalocyanine pigment derivative used as a dispersing material for a blue pigment or a green pigment itself or a coexisting impurity tends to cause a display abnormality of a liquid crystal display device. In particular, chlorinated copper phthalocyanine derivatives tend to cause display defects. As phthalocyanine pigment derivatives, copper phthalocyanine sulfonic acid long-chain alkyl amide,
Examples thereof include copper phthalocyanine sulfonic acid laurylamine salt and phthalimidomethyl copper phthalocyanine. It is important that the addition amount of the phthalocyanine pigment derivative to the color paste for a color filter is 0.1% or less, and the addition amount is more preferably 0.05% or less, and more preferably 0.02% or less. Is most preferred.

According to the present invention, in a color filter having a pixel composed of a colored layer provided in a desired pattern for each color in an arbitrary number of colors, the amount of the phthalocyanine pigment derivative to be added is 0.05% or less based on the colored layer. Is important, and the addition amount is more preferably 0.03% or less, and most preferably 0.01% or less.

The method for producing the pigment of the present invention having a weight reduction rate of 3% or less when extracted with methanol is not particularly limited, and examples thereof include the following. A method to wash pigment powder or crude before pulverization with water, acid, alkali or organic solvent to remove decomposed products and impurities contained in pigment, and to convert pigment powder or crude into strong acid such as sulfuric acid A method of dissolving and recrystallizing (acid paste method). For bromination of green pigment production, bromination using sodium bromide rather than bromination using high-temperature, high-pressure bromine gas is a preferable method because the decomposition of the pigment hardly occurs and the generation of impurities is small. .

Pigment dispersants other than long-chain alkylamines, long-chain alkylacetamides, and phthalocyanine pigment derivatives include EFKA-46, EFKA-47EA, and EFK.
A Polymer 100 (Morishita Sangyo), Disperse Aid 6, Disperse Aid 8, Disperse Aid 1
5, a polymer dispersing material such as Disperse Aid 9100 (all manufactured by San Nopco) can be used.

When the pigment of the present invention is formed into a color paste, various additives such as an ultraviolet absorber, a dispersant, and a leveling agent may be added. Examples of the dispersant include a surfactant,
A wide range of pigment intermediates, polymer dispersants and the like are used, but those containing a large amount of ionic impurities need to be careful because the effects of the present invention are reduced.

The resin used in the present invention is for dispersing and holding the pigment, and is not particularly limited as long as it is generally used for a color paste for a color filter. For example, various resins such as an acrylic resin, an alkyd resin, a melamine resin, a polyvinyl alcohol, a phenol resin, a polyamide, a polyamideimide, and a polyimide can be used. In particular, a resin dissolved in an alkaline aqueous solution is desirable because the equipment can be simplified in the developing or etching step. Among resins that dissolve in an alkaline aqueous solution, a resin having a carboxyl group is preferably used,
Specifically, acrylic resin and polyimide are preferable in terms of solvent resistance. In the case of polyimide, it is more preferable to use polyimide from the viewpoint that the precursors of polyimide function as a dispersant for the pigment and the heat resistance of the color filter.

In the present invention, the term "polyimide precursor" refers to a polyamic acid or a product obtained by esterifying a part thereof. Polyimide precursor, by heat or chemical treatment,
Form an imide ring. The polyamic acid referred to here is represented by the following general formula (1).

[0022]

Embedded image

Here, R1 is a tetravalent organic group having 2 to 22 carbon atoms, R2 is a divalent organic group having 1 to 22 carbon atoms, n is 1 and / or 2, and a weight having a weight average molecular weight of at least 2,000. It is united.

The polyamic acid can be obtained by reacting a tetracarboxylic dianhydride with a diamine. As the tetracarboxylic dianhydride, for example, aliphatic or alicyclic ones can be used, and specific examples thereof include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,5-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-bicyclohexenetetracarboxylic dianhydride, 1,2,
4,5-cyclohexanetetracarboxylic dianhydride,
1,3,3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-C] furan-1,3-dione and the like. When an aromatic compound is used, a polyimide precursor composition that can be converted into a polyimide having good heat resistance can be obtained.
4'-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride Anhydride, 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3, 3 ', 4,4'-
Paraterphenyltetracarboxylic dianhydride, 3,3
', 4,4'-metaphenylphenyltetracarboxylic dianhydride. Also, if a fluorine-based material is used,
A polyimide precursor composition which can be converted into a polyimide having good transparency in a short wavelength region can be obtained, and specific examples thereof include 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride and the like. Is mentioned. The present invention is not limited to these, and one or more tetracarboxylic dianhydrides are used.

In the present invention, for example, aliphatic or alicyclic diamines can be used as the diamine, and specific examples thereof include ethylenediamine, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane,
4,4'-diamino-3,3'-dimethyldicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexyl and the like can be mentioned. When an aromatic compound is used, a polyimide precursor composition that can be converted into a polyimide having good heat resistance can be obtained. Specific examples thereof include 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether. '-Diaminodiphenyl ether, 4,4'
-Diaminodiphenylmethane, 4,4'-diaminobenzanilide, 3,3'-diaminodiphenylmethane,
4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,5-
Diaminotoluene, 2,6-diaminotoluene, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, o-tolidine, 4,4 ″ -diaminoterphenyl, 1,5-diaminonaphthalene, 3, 3 '
-Dimethyl-4,4'-diaminodiphenylmethane,
4,4'-bis (4-aminophenoxy) biphenyl,
2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [ 4- (3-aminophenoxy) phenyl] sulfone and the like. Also,
When a fluorine-based material is used, a polyimide precursor composition that can be converted into a polyimide having good transparency in a short wavelength region can be obtained. As a specific example, 2,2-bis [4- ( 4-aminophenoxy) phenyl] hexafluoropropane and the like.

When siloxane diamine represented by bis-3- (aminopropyl) tetramethylsiloxane is used, the adhesion to an inorganic substrate can be improved. Siloxane diamine is usually 1 to 1 in all diamines.
Used in an amount of 20 mol%. If the amount of siloxane diamine is too small, the effect of improving the adhesiveness will not be exhibited, and if it is too large, the heat resistance will decrease. The present invention is not limited to these, and one or more diamines are used.

The synthesis of polyamic acid is generally carried out by reacting a diamine with a tetracarboxylic dianhydride in a polar organic solvent. At this time, the degree of polymerization of the obtained polyamic acid can be controlled by the mixing ratio of the diamine and the tetracarboxylic dianhydride. In addition, the present invention is also applicable to derivatives such as the above-mentioned esterified products of polyamic acid. Amide polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide and N, N-dimethylformamide are used as the solvent. Polyamic acid is preferably synthesized in a solvent containing lactones as a main component or lactones alone in order to enhance the dispersing effect of the pigment. Here, the solvent containing a lactone as a main component or a lactone alone means that the lactone is contained in 50% by weight or more. Examples of the solvent other than the lactones include methyl cellosolve, ethyl cellosolve, methyl carbitol, ethyl carbitol and the like in addition to the amide-based polar solvent.

Lactones are aliphatic cyclic esters having 3 to 12 carbon atoms. As specific examples, β-propiolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-
Examples include, but are not limited to, caprolactone. Particularly, γ-butyrolactone is preferred in view of the solubility of polyamic acid.

The color paste for a color filter of the present invention contains a pigment, an organic solvent and a resin.

The organic solvent used in the present invention is not particularly limited, and a general organic solvent can be used. When polyimide is used as a component of the pixel matrix, it is preferable to use a polyimide precursor for the resin of the color paste, and it is preferable that the solvent used is a solvent that dissolves the polyimide precursor. Solvents for dissolving the polyimide precursor include amides such as N, N-dimethylacetamide and N, N-dimethylformamide; lactones such as γ-butyrolactone;
And polar organic solvents such as pyrrolidones such as -pyrrolidone and N-methyl-2-pyrrolidone. In addition, usually, the polyimide precursor alone does not dissolve, an alcohol such as ethanol, butanol, isopropanol, cellosolves such as methyl cellosolve and ethyl cellosolve, and organic solvents such as propylene glycol derivatives such as propylene glycol monomethyl ether as a polyimide precursor. It can be used by mixing with a solvent that dissolves the body. In order to enhance the effect of dispersing the pigment, a solvent containing a lactone as a main component is preferable. The amount of the solvent used is not particularly limited, but is preferably an amount sufficient to dissolve the resin and an amount having an appropriate viscosity.

The color paste is prepared by directly dispersing the pigment in the resin solution using a disperser, or dispersing the pigment in water or an organic solvent using a disperser to prepare a pigment dispersion. Manufactured by a method of mixing with There is no particular limitation on the method of dispersing the pigment, and a ball mill,
Various methods such as a sand grinder, a three-roll mill, and a high-speed impact mill can be used.

The color paste of the present invention is usually made of a resin:
The pigment is produced in a range of 5: 5 to 8: 2 (weight ratio).

As a method of applying the color paste on the substrate, a method of applying the color paste to the substrate by a spin coater, a bar coater, a blade coater, a roll coater, a die coater, a screen printing method, etc., or a method of dipping the substrate in the color paste Various methods such as spraying a color paste on a substrate can be used. As the substrate, a transparent substrate such as soda glass, non-alkali glass, borosilicate glass, and quartz glass is usually used, but is not particularly limited thereto. In the case of applying a color paste on a substrate, if the surface of the substrate is treated with an adhesion aid such as a silane coupling agent, the adhesion between the colored film and the substrate can be improved.

The thickness of the colored film formed using the color paste is not particularly limited, but is usually 0.1 to 10 μm.
m, preferably 0.5 to 5 μm. If the film thickness is too small, light absorption will be too small, and the optical characteristics as a color filter will not be satisfied. If the film thickness is too large, on the contrary, problems such as excessive absorption of light may occur, and the optical characteristics as a color filter may not be satisfied.

Next, an example of a method for producing a color filter when polyimide is used as a resin component of a pixel matrix and polyamic acid is used as a precursor thereof will be described.
After applying the color paste on the transparent substrate by the method described above, a polyimide precursor colored film is formed by air drying, heating drying, vacuum drying, or the like. In the case of heating and drying, the drying is carried out at 50 to 180 ° C, more preferably at 80 to 120 ° C, for 30 seconds to 3 hours using an oven, a hot plate or the like. If the temperature is too low, the solvent will not evaporate easily,
Conversely, if the temperature is too high, the solubility in the developer decreases. A pattern is formed on the thus obtained polyimide precursor colored film by ordinary wet etching. First, a positive photoresist is applied on the polyimide precursor colored film to form a photoresist film. Subsequently, a mask is placed on the photoresist film, and ultraviolet light is irradiated using an exposure device. After the exposure, the photoresist coating and the polyimide precursor colored film are simultaneously etched with a positive photoresist alkaline developer. After the etching, the unnecessary photoresist film is removed.

Thereafter, the polyimide precursor colored film is converted into a polyimide colored film by performing a heat treatment. The heat treatment is usually performed at 150 to 450 ° C., preferably at 18 ° C. in air, in a nitrogen atmosphere, or in vacuum.
It is carried out continuously or stepwise at a temperature of 0 to 350C, more preferably 200 to 320C for 0.5 to 5 hours. The above steps are performed for R (red), G (green), and B
By performing the color paste of three colors (blue) and, if necessary, the black color paste, a color filter for a liquid crystal display can be manufactured.

The liquid crystal that can be employed in the present invention includes, but is not limited to, a nematic liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, and a thresholdless antiferroelectric liquid crystal.

The color filter of the present invention has the same effect not only in a transmissive liquid crystal display device provided with a backlight but also in a reflective liquid crystal display device which reflects and uses external light. Further, the present invention has an effect of reducing display defects even if a color filter is formed on either side of a transparent substrate sandwiching a liquid crystal. When a color filter is formed on the substrate side on which active elements such as TFTs are formed (color filter on array: COA), the active elements are provided under the colored layer in order to improve the aperture ratio and prevent a voltage drop due to the insulating film. And through the through hole formed in the colored layer,
In general, a transparent conductive film on a colored layer or a reflective electrode is electrically connected to an active element. In this configuration,
When a through hole is formed in a colored film, a pigment is easily formed on the inner wall of the through hole and exposed to the liquid crystal without being wrapped by the resin, and a voltage stress for driving the liquid crystal is applied, so that impurities are easily eluted. Further, the transparent conductive film serving as the pixel electrode is divided for each pixel, and a portion where the colored layer between the pixels is in direct contact with the liquid crystal is formed, so that the effect of the present invention is particularly large. Further, when a color filter is provided on the substrate on the side opposite to the substrate provided with the active elements, it is possible to cover the entire colored film with an overcoat made of a transparent resin and reduce elution of impurities from the pigment. However, in the case of COA, the fact that the above-mentioned through-hole portion cannot be covered with the overcoat is also one of the reasons why the effect of the present invention is great in COA.

The color liquid crystal display device of the present invention can be used for displaying personal computers, word processors, engineering workstations, navigation systems, televisions, videos and the like, and can also be used as a light modulation device.

[0040]

EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The specific method of the measurement method described in the examples is as follows. (Measurement method) (Weight reduction rate of pigment by methanol extraction) 250 g of methanol is put into a solvent reservoir of a Soxhlet continuous extractor. After measuring the weight of the timble filter containing 50 g of the pigment, the timble filter is set on the extraction part. The solvent reservoir is immersed in a thermostat set at 90 ° C. to evaporate the methanol. Methanol is liquefied in the liquefied part and dropped into the extracted part. After 8 hours of extraction,
After the tumbling filter is taken out and dried, the weight of the tumbling filter containing the pigment is measured, and the weight loss rate of the pigment (weight loss / weight of the pigment before extraction) is calculated. (Display quality) A color paste to be evaluated is applied on non-alkali glass, dried, and then cured. After a 0.1 μm thick ITO film is formed on the entire surface, holes having a diameter of 100 μm are formed in the ITO film by photosonography. That is, after a photoresist is applied on the ITO film and prebaked, the mask pattern is exposed, and the photoresist is immersed in a developer and developed. The sample is washed with water, post-baked, and immersed in an etching solution of ferric chloride: nitric acid = 1: 1 to form holes in the ITO film. The photoresist is stripped with a stripper, washed with water and dried. Separately, a substrate in which an ITO film is formed on the entire surface of non-alkali glass is prepared as a counter substrate. An alignment film is printed and rubbed on the substrate (colored layer substrate) to which the color paste is applied and the counter substrate to be aligned. These two substrates are bonded together with a sealing agent into which a micro rod is kneaded, and then a T voltage corresponding to 4 V driving is applied.
N liquid crystal is injected, and the liquid crystal injection port is closed with a sealing agent.

Instead of a single color paste evaluation, red,
When evaluating a substrate processed into a color filter by patterning blue and green, the ITO formed on the coloring layer
The positions of the holes having a diameter of 100 μm in the film are aligned at the time of exposure, or a large number of holes are prepared at random, so that each colored layer can be evaluated.

The liquid crystal cell thus obtained is kept at 60 ° C., and is driven by a rectangular wave of ± 4 V, 30 Hz for 100 hours. Then, the display is observed between polarizing films arranged orthogonally.

When impurities are eluted from the holes formed in the ITO film of the colored layer substrate and ionic impurities are generated, the threshold is lowered and the periphery of the holes appears darker in gray level display than other portions. It is desirable that the threshold voltage does not decrease due to ionic impurities. Reference Example 1 Synthesis of polymer dispersant 4,1.9 ′ g of 4,4′-diaminobenzanilide
3,3'-diaminodiphenyl sulfone 176.70
g, and 18.64 g of bis (3-aminopropyl) tetramethyldisiloxane with γ-butyrolactone 3266
g, N-methyl-2-pyrrolidone (622 g), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (439.09 g) was added, and the mixture was reacted at 70 ° C. for 3 hours. .22 g and then at 70 ° C.
For 1 hour and then a viscosity of 45 poise (25 ° C.)
A 17% solution (P-1) of a polymer dispersant was obtained. Reference Example 2 Synthesis of oligomer dispersant 204.79 g of 3,3′-diaminodiphenyl sulfone
And 13.62 g of bis (3-aminopropyl) tetramethyldisiloxane were charged together with 3809 g of γ-butyrolactone, 59.98 g of pyromellitic dihydrate, 3,
295.6 g of 3 ', 4,4'-diphenylsulfonetetracarboxylic acid dihydrate was added and reacted at 60 ° C for 3 hours, and 98.22 g of 2-aminoanthraquinone was added.
Further, the reaction was carried out at 60 ° C. for 1 hour.
% Solution (O-1) was obtained. Reference Example 3 Synthesis of polyamic acid 144.1 g of 3,3 ′, 4,4′-biphenyltetracarboxylic acid dihydrate was combined with 1095 g of γ-butyrolactone and N-
Charged with 209 g of methyl-2-pyrrolidone,
95.1 g of 4'-diaminodiphenyl ether and 6.20 g of bis (3-aminopropyl) tetramethyldisiloxane were added and reacted at 70 ° C. for 3 hours, and 2.96 g of phthalic anhydride was added. For 1 hour to obtain a 16% solution of polyamic acid (PAA1). Reference Example 4 Synthesis of polyamic acid 3,3′-diaminodiphenyl sulfone 372.4 g,
146.0 g of paraphenylenediamine and bis (3
-Aminopropyl) tetramethyldisiloxane 32.3
g in 5750 g of N-methyl-2-pyrrolidone,
After adding 873.9 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and reacting at 70 ° C. for 3 hours, adding 5.88 g of maleic anhydride and further adding 70 ° C.
For 1 hour, and a 20% solution of polyamic acid (PAA
2) was obtained. Examples 1 and 2, Comparative Example 1 Three pigments of Pigment Green 36 obtained by chlorinating and brominating copper phthalocyanine were prepared. Weight loss rate by methanol extraction is 2.3% (Pigment A: Example 1),
It was 1.7% (Pigment B: Example 2) and 3.5% (Pigment C: Comparative Example 1). Pigment A is obtained by washing Pigment C. 400 g of isopropanol and 4000 g of ion-exchanged water were added to 200 g of Pigment C and stirred for 30 minutes. After filtration by a centrifuge, a washing process of washing twice with 4000 g of ion-exchanged water was performed three times. 7 cakes obtained
Vacuum dried at 0 ° C. for 48 hours to obtain Pigment A. Pigment B is a pigment obtained by enhancing washing in the pigment production process.

83.79 g of pigments A, B and C were weighed, and γ
557 g of butyrolactone, 323 g of 3-methoxy-5-methyl-1-butanol, a polymer dispersant (P-
494 g of 1) was charged together with zirconia beads into a mill-type dispersing machine, and dispersed at 3000 rpm for 2 hours to obtain three kinds of dispersion liquids. 300 g of the dispersion and a polymer dispersant (P-1)
156.3 g of γ-butyrolactone 198.3 g, 3-
The mixture was mixed with a solution diluted with 185.3 g of methoxy-3-methyl-1-butanol to obtain three kinds of green color pastes.

The green color paste was applied on glass using a spinner so that the film thickness after curing was 1.5 μm, and dried at 120 ° C. for 20 minutes. Then at 240 ° C 3
After curing for 0 minutes, a colored layer was formed. When the display quality was examined by assembling a liquid crystal cell using the colored layer substrate, a portion darker than the periphery was observed around the ITO film hole of the colored layer substrate. The liquid crystal cells in which the periphery of the ITO hole was observed darker than the periphery when the gray level display was performed were 9 out of 10 liquid crystal cells using the pigment C having a large weight loss rate (Comparative Example). 1). On the other hand, in the liquid crystal cell using the pigment A whose weight loss rate was relatively small, when the gray level display was performed, the liquid crystal cell in which the periphery of the ITO hole was observed darker than the periphery was 1%.
3 cells out of 0 cells (Example 1). In a liquid crystal cell using pigment B, when gray level display is performed,
The liquid crystal cell where the periphery of the ITO hole was observed darker than the periphery was 2 out of 10 cells (Example 2). Example 3, Comparative Example 2 Two pigments of Pigment Green 7 obtained by chlorinating copper phthalocyanine were prepared. The weight loss by methanol extraction was 1.9% (Pigment D: Example 3) and 3.1% (Pigment E: Comparative Example 2). Pigment D is obtained by strengthening the washing of Pigment E in the pigment production process.

In the same manner as in Example 1, a color paste was formed, and a liquid crystal cell coated with the color paste was produced.

In the liquid crystal cell using the pigment D having a small weight loss rate, when the gray level display is performed, the periphery of the ITO hole is observed to be darker than the periphery of the ITO hole.
The number of cells was one (Example 3). On the other hand, with the pigment E having a large weight loss rate, when the gray level display was performed, the liquid crystal cells around the ITO hole were observed to be darker than that around 5 cells out of 10 cells (Comparative Example 2). . Example 4, Comparative Example 3 Pigment Blue 15: 6 consisting of copper phthalocyanine
Were prepared. The weight loss by methanol extraction was 1.5% (Pigment F: Example 4) and 3.4% (Pigment G: Comparative Example 3). Pigment F is obtained by enhancing the cleaning of Pigment G in the pigment production process.

In the same manner as in Example 1, a color paste was formed, and a liquid crystal cell coated with the color paste was produced.

In the liquid crystal cell using the pigment D having a small weight loss rate, when the gray level display is performed, the periphery of the ITO hole is observed to be darker than the periphery of the ITO cell.
The number of cells was 0 (Example 4). On the other hand, with the pigment G having a large weight loss rate, when the gray level display was performed, the periphery of the ITO hole was observed to be darker than the periphery of the liquid crystal cell in four out of ten cells (Comparative Example 3). . Example 5, Comparative Example 4 As a dispersing agent for Pigment B of Pigment Green 36, stearylamine, which is a long-chain alkylamine having 18 carbon atoms, containing 0.01% of pigment (Example 5) was added. A sample to which 3% was added (Comparative Example 4) was produced. A color paste was formed in the same manner as in Example 1, and a liquid crystal cell coated with the color paste was produced.

In the liquid crystal cell thus obtained, there was a liquid crystal cell in which the periphery of the ITO hole was observed to be brighter than the periphery when the gray level was displayed. This is due to a decrease in the voltage holding ratio due to ionic impurities in the liquid crystal cell. In Example 5, no display abnormality was observed in 10 liquid crystal cells. On the other hand, in Comparative Example 4, display abnormality was observed in 7 out of 10 liquid crystal cells. Example 6, Comparative Example 5 As a dispersant for Pigment B of Pigment Green 36, N-decylacetamide, which is a long-chain alkylacetamide having 10 carbon atoms, was added at 0.01% of the pigment (Example 6). (Comparative Example 5) was prepared. A color paste was formed in the same manner as in Example 1, and a liquid crystal cell coated with the color paste was produced.

In the obtained liquid crystal cell, there was a liquid crystal cell in which the periphery of the ITO hole was observed to be brighter than the periphery when gray level display was performed. In Example 6, no liquid crystal cell had display abnormality, while in Comparative Example 5, 10
Display failure was observed in 9 of the cells. Example 7, Comparative Example 6 As a dispersant for Pigment B of Pigment Green 36, copper phthalocyanine sulfonic acid, which is a phthalocyanine pigment derivative, to which 0.01% of pigment was added (Example 7) and 3%
A sample with the addition (Comparative Example 6) was prepared. A color paste was formed in the same manner as in Example 1, and a liquid crystal cell coated with the color paste was produced.

In the obtained liquid crystal cell, there was a liquid crystal cell in which the periphery of the ITO hole was observed brighter than the periphery when gray level display was performed. In Example 7, no display abnormality was observed, while in Comparative Example 6, display failure occurred in 6 out of 10 cells. Example 8 191.4 g of Pigment Orange 38, 138.6 g of Pigment Red 177 and γ-butyrolactone 3
267 g, 1266 g of 3-methoxy-3-methyl-1-butanol, 73.92 g of an oligomer dispersant (O-1),
562.95 g of the polymer dispersant (P-1) was charged into a mill-type disperser and dispersed at 4000 rpm for 5 hours. Thus, a red dispersion having a pigment concentration of 6% was obtained.

A polymer solution (PAA) was added to 450 g of the dispersion.
1) A solution obtained by diluting 156.3 g with 108.3 g of γ-butyrolactone and 185.3 g of 3-methoxy-3-methyl-1-butanol was added and mixed to obtain a red color paste.

Pigment Blue 15: 6 having a weight reduction rate of 1.5% when extracted with the same methanol as in Example 4.
157.5 g, and the polymer solution PAA2 was 337.5 g.
g, 637.5 g of γ-butyl lactone and 367.5 g of N-methyl-2-pyrrolidone were charged into a mill-type dispersing machine and dispersed at 3000 rpm for 2 hours. Thus, a blue dispersion having a pigment concentration of 10.5% was obtained.

The polymer solution PA was added to 624 g of the blue dispersion.
A2 702 g, γ-butyl lactone 374 g, N-methyl-2-pyrrolidone 836 g and 3-methoxy-3
-Methyl-butyl acetate (415 g) was added and mixed to obtain a blue color paste.

A chromium oxide film having a thickness of 0.1 μm was formed on the alkali-free glass by a sputtering method. A photoresist was applied on the chromium oxide film and dried at 90 ° C. for 10 minutes. The photoresist was exposed through a photomask and then developed by dipping in a developer. Potassium ferricyanide: sodium hydroxide: water = 1000: 35
After the chromium oxide film was etched with an etching solution mixed at a ratio of 0: 4365, the photoresist was stripped with acetone. Thus, a lattice black matrix having a pitch of 100 μm and a pitch of 300 μm in a direction perpendicular to the pitch of 100 μm and a line width of 20 μm was obtained.

A red color paste is applied on the glass substrate on which the black matrix is formed so as to have a thickness of 1.5 μm after the polyimide conversion, dried at 120 ° C. for 20 minutes, and a photoresist is applied thereon. Dry at 10 ° C. for 10 minutes. The photoresist was exposed through a photomask patterned so as to fill every other opening of the grid arranged at a pitch of 100 μm of the black matrix. After the exposure, the film was immersed in a developing solution composed of a 2.38% aqueous solution of tetramethylammonium hydroxide to simultaneously develop a photoresist and etch a colored film of a polyimide precursor. After the etching, the unnecessary photoresist layer was removed with acetone. Further, the red coating film of the polyimide precursor was heat-treated at 240 ° C. for 30 minutes to convert to a polyimide. Thus, a red pixel was formed.

A blue color paste was applied on a glass substrate on which a black matrix was formed so as to have a thickness of 1.5 μm after the conversion of the polyimide, and dried at 120 ° C. for 20 minutes. Thereafter, blue pixels were formed adjacent to the red pixels in the same manner as in the case of the red color paste.

A green color paste using the same green pigment B as in Example 2 was applied to a glass substrate on which a black matrix was formed so as to have a thickness of 1.5 μm after the conversion of polyimide, and dried at 120 ° C. for 20 minutes. . Thereafter, green pixels were formed adjacent to the red pixels in the same manner as in the case of the red color paste.

An ITO film having a thickness of 0.1 μm was formed on the colored layer by a sputtering method to obtain a color filter. As a counter electrode, an alkali-free glass having an ITO electrode formed on the entire surface was prepared, and a liquid crystal cell was assembled. When the display quality was examined, the liquid crystal cell in which the periphery of the hole portion of the ITO film was observed darker than the periphery was found. 0 cells out of 10 cells,
Good display was obtained. Comparative Example 7 Pigment Blue 15: 6 having a weight loss rate of 3.4% when methanol was extracted from Comparative Example 3 was adopted as a blue pigment, and weight loss rate when methanol was extracted from Comparative Example 1 as a green pigment. Was obtained in the same manner as in Example 8 except that Pigment Green 36 of 3.5% was used. As a counter electrode, an alkali-free glass having an ITO electrode formed on the entire surface was prepared, and a liquid crystal cell was assembled. When the display quality was examined, the liquid crystal cell in which the periphery of the hole portion of the ITO film was observed darker than the periphery was found. 4 out of 10 cells showed more display defects than Example 8.

[0061]

The object of the present invention is to provide a color paste using a pigment in which impurities causing display defects are reduced, and to produce a color filter having excellent display performance and a liquid crystal display device using the same. .

Claims (11)

[Claims] 1. The weight loss when extracted with methanol is 3
% Or less, a color paste for a color filter, wherein a pigment having a percentage of not more than 0.1% is used. 2. A color paste for a color filter, comprising at least a pigment, an organic solvent and a resin, wherein the amount of long-chain alkylamine added is 0.1% or less. 3. A color paste for a color filter containing at least a pigment, an organic solvent and a resin, wherein the amount of long-chain alkylacetamide added is 0.1% or less. 4. A color paste for a color filter, comprising at least a pigment, an organic solvent and a resin, wherein the amount of the phthalocyanine pigment derivative added is 0.1% or less. 5. A color filter having pixels of colored layers provided in a desired pattern for each color in an arbitrary number of colors, wherein the amount of long-chain alkylamine added is 0.05% or less of the colored layer. A color filter characterized by the following. 6. A color filter having pixels of a color layer provided in a desired pattern for each color in an arbitrary number of colors, wherein the amount of long-chain alkylacetamide added is 0.05% or less of the color layer. A color filter characterized by the following. 7. In a color filter having pixels of a color layer provided in a desired pattern for each color in an arbitrary number of colors, the amount of the phthalocyanine pigment derivative to be added is 0.05% or less based on the color layer. A color filter characterized by the following. 8. The pigment according to claim 1, wherein said pigment is a green pigment or a blue pigment having a phthalocyanine skeleton.
The color paste for a color filter according to any one of the above. 9. A color filter having pixels of a color layer provided in a desired pattern for each color in an arbitrary number of colors, wherein the color layer is any one of claims 1, 2, 3, 4, and 8. A color filter, which is a colored film made of the color paste described in the above. 10. The color filter according to claim 5, wherein the pigment contained in the at least one coloring layer is a green pigment or a blue pigment having a phthalocyanine skeleton. 11. A liquid crystal display device using the color filter according to claim 5, 6, 7, 9, 10.