JPH09133805A - Color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color liquid crystal display device which is simple in production stages, has excellent flatness and has excellent display quality and high reliability. SOLUTION: This color filter is formed by forming a coloring layer 3 on a transparent substrate 2, applying a resin compd. prepd. by mixing a photopolymerizable acrylate polymer contg. an acidic group, a bi- or higher functional photopolymerizable acrylate monomer, an epoxy resin and an initiator on this coloring layer 3, subjecting this resin compd. film to exposing, alkaline developing and heat treatment and forming a protective film 5 on the coloring layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter, and more particularly to a color filter which enables a color liquid crystal display device having excellent display quality and high reliability.

[0002]

2. Description of the Related Art In recent years, color liquid crystal display devices have attracted attention as flat displays. Generally, a color liquid crystal display device has a structure in which a color filter and a counter electrode substrate are opposed to each other, and a liquid crystal layer is formed in a gap portion (1 to 10 μm) thereof. The color filter is provided with a black matrix on a transparent substrate and a colored layer composed of a plurality of colors (usually, three primary colors of red (R), green (G), and blue (B)), on which a protective film and a transparent electrode are provided. Are sequentially stacked.
The color image is obtained by controlling the light transmittance of the liquid crystal layer in a portion corresponding to each pixel of the colored layers R, G, and B of each color.

The protective film constituting the color filter plays a role of protecting the colored layer and flattening the color filter. Generally, in a color liquid crystal display device, gap unevenness due to the undulation of the transparent substrate surface of the color filter, R,
If there is a gap unevenness between the G and B pixels or a gap unevenness within each of the R, G and B pixels, color unevenness and contrast unevenness occur, resulting in deterioration of image quality.
In the STN type color liquid crystal display device, the flatness of the surface of the color filter has a great influence on the image quality, so that the function of flattening the protective film is extremely demanded.

The protective film takes into consideration the adhesiveness between the color filter substrate and the counter electrode substrate and the reusability of the color filter when it is judged as defective in the display quality inspection after the color filter and the counter electrode substrate are adhered. Then, it is preferable to form only on a specific region which covers the colored layer on the transparent substrate.
Therefore, the protective film is formed by using a photocurable resin, which is easy to limit the portion to be cured with a mask.

[0005]

However, the conventional resin for forming a protective film uses an organic solvent in the development after exposure, is complicated in terms of handling and waste liquid treatment, and is economical and stable. It lacked sex.

In order to solve such a problem, a photo-curable resin has been developed in which an acidic group is introduced into the photo-curable resin so that the development after exposure can be alkali development.

However, the surface of the protective film formed by using such an alkali-development type photo-curable resin is eroded by the resist stripping solution (concentrated alkaline solution) in the subsequent step of forming the transparent electrode, resulting in flatness. There is a problem that is damaged.

The present invention has been made in view of the above circumstances, has a simple manufacturing process, has excellent flatness, and has high display quality and high reliability. It is an object of the present invention to provide a color filter that enables

[0009]

In order to achieve such an object, a color filter of the present invention is formed so as to cover a transparent substrate, a colored layer formed on the transparent substrate, and the colored layer. The protective film is prepared by mixing a photopolymerizable acrylate polymer containing an acidic group, a polyfunctional photopolymerizable acrylate monomer having two or more functional groups, an epoxy resin, and an initiator. The resin composition was applied, exposed and alkali-developed, and heat-treated to form a structure.

Further, in the color filter of the present invention, the epoxy resin is contained in the resin composition in a solid content ratio of 10 to 30% by weight.
And the acidic group is a carboxyl group.

In the present invention as described above, the epoxy resin contained in the resin composition is mixed with an acidic group remaining in the protective film without reacting even after exposure and alkali development,
It reacts by the heat treatment and imparts excellent alkali resistance to the protective film.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an example of the color filter of the present invention. In FIG. 1, a color filter 1 of the present invention includes a colored layer 3 and a black matrix 4 formed on a transparent substrate 2 in a predetermined pattern, and a protective film 5 formed so as to cover the colored layer 3. A transparent electrode 6 for driving a liquid crystal is formed on the surface 5.

As the transparent substrate 2 constituting such a color filter 1, quartz glass, Pyrex glass,
A rigid material having no flexibility such as a synthetic quartz plate, or a flexible material having flexibility such as a transparent resin film and an optical resin plate can be used. Among them, Corning 7059 glass is a material having a small coefficient of thermal expansion and is excellent in dimensional stability and workability in high temperature heat treatment,
Further, since the glass is a non-alkali glass containing no alkali component, it is suitable for a color filter used in a color liquid crystal display device.

In the colored layer 3 constituting the color filter 1, the red pattern 3R, the green pattern 3G and the blue pattern 3B are mosaic type, stripe type, triangle type,
The black matrix 4 is arranged in a desired form such as a 4-pixel arrangement type, and the black matrix 4 is provided between the coloring patterns and in the coloring layer 3.
It is provided in a predetermined area outside the formation area.

The coloring layer 3 is formed by applying a dyeing base material, exposing and developing it through a photomask, and dyeing a pattern formed by dyeing. Pigment dispersion method of exposing and developing through, printing method of printing each color with printing ink, forming a transparent conductive layer in advance on a transparent substrate, forming a positive resist layer on this transparent conductive layer, and then through a photomask After exposing and developing by exposing the transparent conductive layer at a predetermined position, the transparent substrate is immersed in the electrodeposition liquid to energize the transparent conductive layer for electrodeposition to form a colored layer. Alternatively, any method may be used.

The black matrix 4 can also be formed by any of the dyeing method, pigment dispersion method, printing method and electrodeposition method described above, or may be formed by chromium vapor deposition or the like.

The protective film 5 constituting the color filter 1 is
A photopolymerizable acrylate polymer containing an acidic group and 2
A resin blend obtained by mixing a polyfunctional photopolymerizable acrylate monomer having a functionality or higher, an epoxy resin, and an initiator,
It is formed by coating on the transparent substrate 2 on which the coloring layer 3 and the black matrix 4 are formed, exposing it through a predetermined photomask, performing alkali development, and then performing heat treatment (post-baking). It is a thing. This protective film 5
Has a pencil hardness of 4H or more after being immersed in a 1% aqueous sodium hydroxide solution (liquid temperature = 25 ° C.) for 24 hours, does not cause peeling, and has extremely high alkali resistance. There is. Even after the resin composition is exposed to light and alkali-developed, unreacted acidic groups remain in the resin composition, but in the present invention, the epoxy resin contained in the resin composition is Since the group reacts with the group by heat treatment, there is no acidic group capable of reacting with the alkali in the formed protective film, and therefore the protective film has excellent alkali resistance.

Examples of the photopolymerizable acrylate polymer that can be used to form the protective film 5 include epoxy acrylates such as o-cresol novolac epoxy acrylate and phenol novolac epoxy acrylate, polyester acrylate, polyurethane acrylate, polyether acrylate, oligomer acrylate. , Alkyd acrylate, polyol acrylate and melamine acrylate. This photopolymerizable acrylate polymer has a solid content ratio of 2 in the resin blend.
It is preferably contained in the range of 0 to 70% by weight.

The acidic group introduced into such a photopolymerizable acrylate polymer is intended to make the development of the resin composition alkaline development. As the acidic group, a carboxyl group, a sulfone group, a salicyl group, a sulfine group, a sulfene group, a thiocarboxylic group and the like are preferable.
The introduction of such an acidic group can be carried out by reacting a hydroxyl group in the photopolymerizable acrylate polymer with an acid anhydride such as phthalic anhydride, maleic anhydride, succinic anhydride, etc. It is set to about 30 to 70%, preferably about 50%.

As the acrylate monomer that can be used to form the protective film 5, 1,4-butanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate. , Pentaerythritol acrylate and dipentaerythritol hexaacrylate. The acrylate monomer is preferably contained in the resin composition in a solid content ratio of 20 to 70% by weight.

Further, examples of the epoxy resin used together with the above-mentioned photopolymerizable acrylate polymer and photopolymerizable acrylate monomer include phenol novolac type epoxy resin and cresol novolac type epoxy resin. Such an epoxy resin is contained in the resin composition in a solid content ratio of 10 to 30% by weight. When the epoxy resin content is less than 10% by weight, sufficient alkali resistance cannot be imparted to the protective film. On the other hand, when the epoxy resin content exceeds 30% by weight, the amount of the epoxy resin not subjected to photocuring is increased. Is too large, and the storage stability and the developability of the resin formulation are deteriorated, which is not preferable.

As the initiator usable in the present invention, benzophenone or Irgacure 18 is used.
4, Irgacure 369, Irgacure 651, Irgacure 907 (all are trade names of Ciba-Geigy Co., Ltd.), and Darocur (trade name of Merck Co.). Such an initiator is preferably contained in the resin composition in a solid content ratio of 1 to 3% by weight.

The protective film 5 is formed by using the above-mentioned photopolymerizable acrylate polymer containing an acidic group, a polyfunctional photopolymerizable acrylate monomer having two or more functional groups, and an epoxy resin.
The resin composition prepared by mixing an initiator can be applied by a method such as spin coater, roll coater, spray, or printing. The heat treatment (post-baking) performed after completing the exposure and alkali development of the coating film of this resin compound is usually 120 to 250 ° C. and 5 to 9 ° C.
It can be performed under the condition of about 0 minutes. By this heat treatment, the epoxy resin contained in the resin composition reacts with the remaining acidic groups.

In the present invention, a resin mixture prepared by mixing the above-mentioned photopolymerizable acrylate polymer containing an acidic group, a polyfunctional photopolymerizable acrylate monomer having two or more functional groups, an epoxy resin, and an initiator. A silane coupling agent may be added to the product. Examples of the silane coupling agent used include vinylsilane, acrylsilane, epoxysilane, aminosilane and the like.

More specifically, vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane and the like can be used as the vinylsilane.

Examples of acrylsilanes include γ-methacryloxypropyltrimethoxysilane and γ-methacryloxypropylmethyldimethoxysilane.

As the epoxysilane, β- (3,4-
Epoxycyclohexyl) ethyltrimethoxysilane,
Examples thereof include γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldietoxylan.

Further, as aminosilane, N-β-
(Aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethylditrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane Etc. can be used. As other silane coupling agents, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane,
γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane and the like can be used.

The transparent electrode 6 on the protective film 5 constituting the color filter 1 is made of indium tin oxide (ITO),
Using zinc oxide (ZnO), tin oxide (SnO), etc., and their alloys, etc., sputtering method, vacuum deposition method, C
It is formed by a general film forming method such as the VD method, and is formed into a predetermined pattern by etching using a photoresist if necessary. The thickness of this transparent electrode 6 is 20
The thickness can be set to about 500 nm, preferably about 100 to 300 nm.

[0031]

Next, the present invention will be described in more detail with reference to examples. Preparation of Sample 1 1.1 mm thick glass substrate (AL material manufactured by Asahi Glass Co., Ltd.)
A red photosensitive resin having the following composition was applied thereon by a spin coating method (application thickness 1.5 μm), and then 7
Dry in an oven at 0 ° C. for 30 minutes. Next, the coated surface was exposed through a photomask having a predetermined pattern using a mercury lamp, and spray development with water was carried out for 1 minute to form a red relief pattern in a region where a red pixel should be formed. Further, thereafter, heating treatment was carried out by heating at 150 ° C. for 30 minutes.

Next, a green photosensitive resin having the following composition was used to form a green relief pattern in a region where a green pixel is to be formed, in the same process as that for forming a red relief pattern.

Further, a blue photosensitive resin having the following composition is used to form a blue relief pattern in an area where a blue pixel is to be formed in the same process as that for forming a red relief pattern, and red (R) and green are formed. A colored layer composed of three colors (G) and blue (B) was prepared.

(Composition of red photosensitive resin) Pyrazolone red (red pigment) 10 parts by weight Polyvinyl alcohol / 5% stilbazolium quinolium (photosensitive resin) 5 parts by weight Water 85 parts by weight ( Composition of green photosensitive resin) -Lionol green 2Y-301 (green pigment) ... 9 parts by weight-Polyvinyl alcohol / 5% stilbazolium quinolium (photosensitive resin) ... 5 parts by weight-Water ... 86 parts by weight ( Composition of blue photosensitive resin) -Fastgen blue (blue pigment) 3 parts by weight-Polyvinyl alcohol / 5% stilbazolium quinolium (photosensitive resin) 5 parts by weight Water 92 parts by weight The resin composition A-1 having the following composition was applied by a spin coating method (coating thickness: 1.2 μm) on the glass substrate on which the colored layer was formed.

(Composition of Resin Blend A-1) o-cresol novolac epoxy acrylate (50% of hydroxyl groups reacted with phthalic anhydride) 8.8 parts by weight Dipentaerythritol hexaacrylate 8.8 Parts by weight: Epoxy resin: 2.0 parts by weight Irgacure 369: 0.4 parts by weight: 3-Methoxybutyl alcohol acetate: 80 parts by weight In addition, in the above resin blend A-1, the epoxy resin is a solid content. The content is about 10% by weight.

Then, 100 μm from the coating film of the resin compound.
A photomask was arranged at a distance of m, and an ultraviolet ray was irradiated for 10 seconds only on a region corresponding to a region where the colored layer was formed by using a 2.0 kW ultra-high pressure mercury lamp with a proximity liner. Then, it was immersed in a 0.05% aqueous solution of potassium hydroxide (liquid temperature: 23 ° C.) for 1 minute for alkali development to remove only the uncured portion of the coating film of the resin formulation.

Then, the substrate is placed in an atmosphere of 180 ° C. for 30 minutes.
A heat treatment was performed by leaving it for a minute to form a protective film, and a color filter (Sample 1) was obtained. Preparation of sample 2 The content of epoxy resin in the resin formulation is about 2 in terms of solid content.
Color filter (Sample 2) in the same manner as in Sample 1 except that the resin composition A-2 having the following composition of 0% by weight was used.
Was prepared.

(Composition of Resin Blend A-2) o-cresol novolac epoxy acrylate (50% of hydroxyl groups reacted with phthalic anhydride) 7.8 parts by weight Dipentaerythritol hexaacrylate 7.8 Parts by weight-epoxy resin ... 4.0 parts by weight-Irgacure 369 ... 0.4 parts by weight-acetic acid 3-methoxybutyl alcohol ... 80 parts by weight Preparation of Sample 3 The content of the epoxy resin in the resin formulation is the solid content ratio. About 3
Color filter (Sample 3) in the same manner as in Sample 1 except that the resin composition A-3 having the following composition of 0% by weight was used.
Was prepared.

(Composition of Resin Blend A-3) o-cresol novolac epoxy acrylate (50% of hydroxyl groups reacted with phthalic anhydride) 6.8 parts by weight Dipentaerythritol hexaacrylate 6.8 Weight part-Epoxy resin-6.0 weight parts-Irgacure 369-0.4 weight parts-Acetic acid 3-methoxybutyl alcohol--80 weight parts Preparation of sample 4 The content of the epoxy resin in the resin formulation is the solid content ratio. A color filter (Sample 4) was prepared in the same manner as Sample 1 except that the resin composition A-4 having the following composition, which was 0% by weight, was used.

(Composition of resin blend A-4) o-cresol novolac epoxy acrylate (50% of hydroxyl groups reacted with phthalic anhydride) 9.8 parts by weight dipentaerythritol hexaacrylate 9.8 Parts by weight Irgacure 369 0.4 parts by weight 3-methoxybutyl alcohol acetate 80 parts by weight Preparation of sample 5 The content of the epoxy resin in the resin formulation is about 5 in terms of solid content.
A color filter (Sample 5) was prepared in the same manner as in Sample 1, except that the resin composition A-5 having the following composition, which was used in weight%, was used.

(Composition of Resin Blend A-5) o-cresol novolac epoxy acrylate (50% of hydroxyl groups reacted with phthalic anhydride) 9.3 parts by weight dipentaerythritol hexaacrylate 9.3 Parts by weight: Epoxy resin: 1.0 parts by weight Irgacure 369: 0.4 parts by weight: 3-Methoxybutyl alcohol acetate: 80 parts by weight Preparation of sample 6 The content of the epoxy resin in the resin composition is the solid content ratio. About 4
Color filter (Sample 6) in the same manner as in Sample 1 except that the resin composition A-6 having the following composition of 0% by weight was used.
Was prepared.

(Composition of Resin Blend A-6) o-cresol novolac epoxy acrylate (50% of hydroxyl groups reacted with phthalic anhydride) 5.8 parts by weight Dipentaerythritol hexaacrylate 5.8 Parts by weight-epoxy resin ... 8.0 parts by weight-Irgacure 369 ... 0.4 parts by weight 3-methoxybutyl alcohol acetate ... 80 parts by weight Preparation of sample 7 The content of the epoxy resin in the resin formulation is the solid content ratio. About 5
Color filter (Sample 7) in the same manner as in Sample 1 except that the resin composition A-7 having the following composition of 0% by weight was used.
Was prepared.

(Composition of Resin Blend A-7) o-cresol novolac epoxy acrylate (50% of hydroxyl groups reacted with phthalic anhydride) 4.8 parts by weight Dipentaerythritol hexaacrylate 4.8 Parts by weight: Epoxy resin: 10 parts by weight Irgacure 369: 0.4 parts by weight: 3-Methoxybutyl alcohol acetate: 80 parts by weight Preparation of sample 8 The content of the epoxy resin in the resin composition is 20 in terms of solid content.
A color filter (Sample 8) was prepared in the same manner as in Sample 1 except that the resin composition B having the following composition, which was in the weight%, was used.

(Composition of Resin Blend B) Phenol novolac epoxy acrylate (30% of hydroxyl groups reacted with phthalic anhydride) 7.8 parts by weight Dipentaerythritol hexaacrylate 7.8 parts by weight Epoxy Resin: 4.0 parts by weight Irgacure 369: 0.4 parts by weight Acetate: 3-methoxybutyl alcohol: 80 parts by weight Evaluation of each sample The protective film of each color filter (samples 1 to 8) under the following conditions. The alkali resistance was evaluated, and the developability and storage stability of the resin formulation used were evaluated, and the results are shown in Table 1 below.

(Alkali resistance) The sample was immersed in a 1% sodium hydroxide aqueous solution (solution temperature 23 ° C.) for 24 hours and then withdrawn, and the hardness of the protective film was measured according to the JIS pencil hardness measuring method. Was evaluated according to the following evaluation criteria.

Evaluation Criteria for Appearance ◯: No change is observed in the protective film Δ: Roughness and bubbles are generated on the surface of the protective film ×: Part or all of the protective film is peeled off (evaluation condition for developing suitability) The outer peripheral shape of the protective film pattern when immersed in a 05% aqueous potassium hydroxide solution (23 ° C.) for 1 minute to completely remove the unexposed portion was evaluated according to the following criteria.

Evaluation Criteria ◯: The outer peripheral shape maintains linearity, and no waviness, wrinkles, etc. ×: No linearity is observed in the outer peripheral shape, waviness, wrinkles, etc. (Evaluation condition for storage stability ) After allowing the resin formulation to stand at 23 ° C. for 2 weeks, the resin formulation was evaluated for viscosity, sensitivity, resolution, transparency and developability.

Evaluation Criteria ◯: No change in any of the characteristics x: At least one decrease in characteristics

[0049]

[Table 1] As shown in Table 1, in Samples 1 to 3 and Sample 8 in which the resin composition contained 10 to 30% by weight of the epoxy resin in the solid content ratio, the alkali resistance of the protective film was good, and It was confirmed that sufficient resistance can be exhibited even in contact with the resist stripping solution (concentrated alkaline solution) in the forming step. It was also confirmed that the resin composition used for forming the protective film has excellent developability and storage stability, and can form a stable protective film.

On the other hand, Samples 4 and 5 in which the epoxy resin content in the resin composition is less than 10% by weight in solid content are the developability and storage stability of the resin composition used for forming the protective film. Although it has excellent properties, the alkali resistance of the protective film is insufficient, and there is a risk of erosion of the protective film in contact with the resist stripping solution (concentrated alkaline solution) in the step of forming the transparent electrode.

Further, in Samples 6 and 7 in which the epoxy resin contained in the resin mixture exceeds 30% by weight in solid content ratio, although the alkali resistance of the protective film is sufficient, the resin mixture used for forming the protective film is The product lacked in developability and storage stability, and could not be put to practical use.

[0052]

As described in detail above, according to the present invention, a colored layer is formed on a transparent substrate, and the colored layer is covered with the colored layer.
A photopolymerizable acrylate polymer containing an acidic group and 2
Coating with a resin mixture prepared by mixing a polyfunctional photopolymerizable acrylate monomer having a functionality or higher, an epoxy resin, and an initiator, exposing the resin mixture film to exposure, alkali development, heat treatment, and coloring. Since the protective film is formed on the layer, the epoxy resin contained in the resin composition reacts with the acidic group remaining in the protective film after the exposure and the alkali development by the heat treatment, resulting in the alkali of the acidic group. The alkali resistance to the protective film is extinguished and excellent alkali resistance is imparted to the protective film. As a result, the protective film is eroded by the resist stripping solution (concentrated alkaline solution) in the process of forming the transparent electrode on the protective film, and the flatness is reduced. By using such a color filter, it is possible to provide a highly reliable color liquid crystal display device having excellent display quality.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a color filter of the present invention.

[Explanation of symbols]

 1 ... Color filter 2 ... Transparent substrate 3 ... Colored layer 4 ... Black matrix 5 ... Protective film 6 ... Transparent electrode

Claims (3)

[Claims] 1. A transparent substrate, a colored layer formed on the transparent substrate, and a protective film formed so as to cover the colored layer, wherein the protective film contains a photopolymerizable resin containing an acidic group. A resin mixture prepared by mixing an acrylate polymer, a polyfunctional photopolymerizable acrylate monomer having two or more functional groups, an epoxy resin, and an initiator is applied, exposed, and alkali-developed.
A color filter, which is formed by heat treatment. 2. The color filter according to claim 1, wherein the epoxy resin is contained in the resin composition in a solid content ratio of 10 to 30% by weight. 3. The color filter according to claim 1, wherein the acidic group is a carboxyl group.