JPH03251819A - Color filter - Google Patents

Abstract

PURPOSE:To obtain sufficient strength of adhesion by forming colored layers on a transparent substrate and applying a resin mixture composed of a photopolymerizable acrylate and bi- and higher functional photopolymerizable acrylates thereon, then curing the coating with UV rays to form a protective film at the time of forming the color filter to be used for a color liquid crystal display device. CONSTITUTION:The plural colored layers 2 of R, G, B are formed sequentially at spaced intervals by using dyes, pigments, etc., on the transparent substrate 1 consisting of a synthetic resin, such as borosilicate glass or polycarbonate. The entire surface including these layers is then coated with the protective film 3. The photosensitive resin formed by adding the multifunctional photopolymerizable acrylate monomer to the photopolymerizable acrylate oligomer is used for the protective film 3 at this time. Further, benzophenone, etc., as an initiator is added into the photopolymerizable resin. A photomask 4 drawn with prescribed patterns is thereafter disposed apart a specified distance from the resin layer and is irradiated with UV rays to cure the resin. The protective film which is free from cracks and ruggedness is obtd. in such a manner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a color filter, and particularly to a color filter used in a color liquid crystal display device.

[Prior Art] In a liquid crystal display device, a liquid crystal substance is sealed between transparent substrates such as glass provided with transparent electrodes with an interval of about 1 to 10 μm, and the liquid crystal is heated at a certain level by a voltage applied between the electrodes. Images are displayed by oriented in the same direction to form transparent and opaque areas.

A color liquid crystal display device has three color filters of red (R), green (G), and blue (B) corresponding to the three primary colors of light on one of the transparent electrode substrates. By controlling the transmission of light through the liquid crystal by adjusting the voltage, R, G,
By controlling the amount of light passing through the three color filters of B,
Color display is performed by adding color to the primary colors.

Color LCD devices require transparent substrates, colored layers, and protective wind.
A transparent conductive film is laminated in this order.

The protective film protects the colored layer and also serves as a base material for the transparent conductive film. Many materials can be used as long as they are transparent and can withstand the heat treatment temperatures used in the subsequent color filter manufacturing process, but thermosetting urethane resins, acrylic resins, polyimide resins, and photocuring acrylic resins are particularly suitable. Resin, polyimide resin, etc. are used.

[Problem to be solved by the invention] When a thermosetting resin is used as a protective film for a color liquid crystal display device, the protective film is formed over the entire surface of the color filter, so it is necessary to limit the protective film to a predetermined area. It is difficult to do so.

If a protective film is formed on the entire surface of the color filter, sufficient adhesive strength may be required since the color filter and the counter electrode will be bonded to each other through the protective film when the color filter and the counter electrode are glued together. Something happens that you don't get. In addition, if there is a quality problem when inspecting the display quality after gluing the color filter and transparent electrode together and it is determined that the product is defective, the liquid crystal sealant can be removed in order to reuse the color filter. Furthermore, when removing the tab, if a protective film is applied to the entire outer periphery of the colored layer, the transparent electrode formed on the color filter will be removed along with the sealant or tab, making it impossible to reuse the color filter. There is also the problem.

Therefore, in order to limit the portions on which the protective film is formed to specific portions, photocurable resins are used, which can easily limit the portions to be cured using a mask. However, photosensitive polyimide resin, which has been conventionally used as a photocurable resin, has high hygroscopicity, lacks corrosion resistance to alkaline solutions used in forming electrodes, etc., and is expensive, making it undesirable for practical use. . Furthermore, conventional photosensitive acrylic resins have poor heat resistance, and furthermore, when a relatively thick transparent conductive film is formed on a protective film, there is a problem in that cranks and wrinkles occur on the color filter.

Further, in order to use it as a color filter for a color liquid crystal display device, transparent electrodes are provided on the protective film of the colored layer to drive the liquid crystal in portions corresponding to the R, G, and B positions of the colored layer. The issue of flatness of transparent electrodes is particularly important in driving active type liquid crystals in which a transparent electrode is formed on a protective film to act as a counter electrode to a thin film transistor (TPT) formed on a transparent substrate, such as in color television display devices. However, in the case of the STN method of driving the liquid crystal used in computer color displays,
The flatness of transparent electrodes is a major problem.

Furthermore, even when the protective film is limited to the colored layer, the protective film is formed on the wall surface around the colored layer and the transparent substrate adjacent to the wall surface to protect the colored layer. If the adhesive strength between the protective layer and the transparent substrate is not strong enough, the protective layer may peel off from the transparent substrate, or chemicals used in the process of forming transparent electrodes or assembling liquid crystal display devices may leak between the transparent substrate and the protective layer. Penetration may occur and adversely affect the colored layer.

The primary purpose of this invention is to provide a color filter that does not have a protective film in the areas that are problematic during assembly of the outer periphery of the colored layer, and does not cause cracks or wrinkles on the protective film. The purpose is to form a strong protective film.

A second object of the present invention is to obtain a protective film in which a flat transparent electrode with small irregularities is formed at the same time.

Furthermore, the third purpose is to increase the adhesive strength between the transparent substrate and the protective film to prevent the protective film from peeling off from the periphery and to prevent chemicals, etc. from penetrating between the transparent substrate and the protective film. It is.

[Means for Solving the Problems] As a result of research into means for solving the above problems, the present inventors have developed a multifunctional photopolymerizable acrylate having multiple functional groups in one molecule in a photopolymerizable acrylate oligomer. By using a photosensitive acrylic resin with added monomers, the degree of cross-linking of the resin is increased, resulting in a film with high rigidity and hardness. Even when a thick transparent electrode is formed on the protective film, no cracks or wrinkles occur. This is what I discovered.

At the same time, if a resin with such a composition is used as a protective film, even if a recess is formed between adjacent R, G, and 8 of the colored layer formed on a transparent substrate, the recess on the surface of the protective film at the position corresponding to the recess will be R becomes extremely small and is formed in the colored layer.
, G, and H, it has been found that a protective film with good flatness and very little unevenness on the surface of the protective film can be obtained.

Furthermore, before forming the protective film, the strength between the transparent substrate and the protective film is increased in the peripheral area of the protective film by applying a silane coupling agent on the transparent electrode or mixing the silane coupling agent into the resin. We have discovered that this is possible.

The above photopolymerizable acrylate oligomer that can be used for the purpose of the present invention preferably has a molecular weight of about 1000 to 2000, and polyester acrylate or
Epoxy acrylates such as phenol novolac epoxy acrylate and 0-cresol novolane epoxy acrylate, polyurethane acrylate, polyether acrylate, oligomer acrylate, alkyd acrylate, polyol acrylate, melamine acrylate, etc. can be mentioned as polyfunctional photopolymerizable acrylate monomers. Examples include 1,4-butanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, pentaerythritol acrylate, dipentaerythritol hexaacrylate, and the like.

The method for forming the protective film of the present invention is to apply a photosensitive resin prepared by adding a polymerization initiator to a photopolymerizable acrylate oligomer and a multifunctional photopolymerizable acrylate monomer onto a colored layer provided on a transparent substrate using a spinner method, a roll method, or a spray method. After coating by any coating method such as method or screen printing method, a mask with a predetermined pattern is placed on it and UV rays are irradiated to harden the necessary areas. By dissolving and removing the resin with a solvent that dissolves the resin, a protective film of the resin is formed in a predetermined region only in a rigid and hard film with an increased degree of cross-linking. The obtained protective film has sufficient strength, so even if a thick transparent electrode is formed on the protective film, no cranks or wrinkles occur, and the film is highly flat with few irregularities. Furthermore, since it has photosensitivity, it is possible to form a protective film only in a predetermined area by using a photomask.

[Function] The color filter of the present invention uses a photosensitive resin in which a polyfunctional photopolymerizable acrylate monomer is added to a photopolymerizable acrylate oligomer as a protective film formed on the surface of the colored film. Even if a thick transparent electrode is formed on the substrate, no cracks or wrinkles will occur, and at the same time, a protective film with excellent flatness with little unevenness and excellent adhesion to the transparent substrate can be obtained. A color filter in which a protective film is formed only in a predetermined area can be obtained by irradiating ultraviolet rays onto the surface coated with the resin and dissolving and removing the resin in the areas that have not been irradiated with ultraviolet rays.

[Example: To explain the color filter of the present invention with reference to drawings,
As shown in cross section in FIG. 1, colored layers 2 corresponding to the three primary colors of light are formed on a transparent substrate 1.

The transparent substrate is made of glass such as borosilicate glass, polycarbonate,
Synthetic resins such as polyethylene terephthalate can be used. Further, the colored layer is formed by using a coloring material such as a dye or a pigment by a printing method or a photolithography method.

A protective film 3 is provided on the surface of the colored layer 2 by a method such as spin coater roll coater 1 spraying or printing. In particular, the protective layer is formed by adding a polyfunctional photopolymerizable acrylate monomer to a photopolymerizable acrylate oligomer. It uses photosensitive resin.

Examples of photopolymerizable acrylate oligomers include polyester acrylate, epoxy acrylate such as phenol novolac epoxy acrylate, 0-cresol novolac epoxy acrylate, polyurethane acrylate, polyether acrylate,
Examples of polyfunctional photopolymerizable acrylate monomers include oligomer acrylate, alkyd acrylate, polyol acrylate, and melamine acrylate. Examples include erythritol triacrylate, trimethylolpropane triacrylate, pentaerythritol acrylate, and dipentaerythritol hexaacrylate.

In addition, when a photopolymerizable acrylate monomer or oligomer has an acidic group such as a carboxyl group, it becomes possible to develop it with an alkaline aqueous solution, which is easier to handle and waste liquid treatment than development with an organic solvent, and is economical and efficient. Favorable from the standpoint of safety.

Furthermore, as an initiator in the photopolymerizable resin, benzophenone, Irgacure 184, Irgacure 907
, Irgacar-651 (all brand names of Ciba Geigy), Darocure (trade name of Merck & Co.), etc. may be added in an amount of about 1 to 3% solid content.

A particularly suitable compounding ratio (wt%) of the photopolymerizable acrylate oligomer and the polyfunctional photopolymerizable monomer is 1: Phenol novolak epoxy acrylate: 60% Trimethylolpropane triacrylate: 17% Dipentaerythritol hexa Acrylate: 20% Irgacure 184: 3% blending ratio 2 0-Taresol Novolac Epoxy Acrylate: 60
% Dipentaerythritol hexaacrylate...38% IRGACURE 184...2% blending ratio 3 Polyurethane acrylate...50% dipentaerythritol hexaacrylate...48% IRGACURE 651...2% blending ratio 4 Melamine Acrylate: 70% Trimethylolpropane triacrylate: 27% Irgacure 184: 2%, etc.

After applying the photocurable resin formulation onto the colored layer, a second
As shown in the cross section in the figure, a photomask with a predetermined pattern drawn thereon was placed at a certain distance from the photosensitive resin layer, and ultraviolet rays were irradiated to cure the resin. After irradiation with ultraviolet rays, development is performed using an organic solvent such as methylene chloride, dichloroethane, tetrachloroethane, or methyl ethyl ketone, or an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide to dissolve and remove the uncured protective film on the outer periphery of the colored layer. As shown in cross section in FIG. 3, a color filter was able to be produced in which a protective film 3 of photocurable resin was formed only on the surface of the colored layer portion 2.

An electrode formed with a display pattern made of a transparent conductive film was provided on the protective film of the color filter thus prepared.

The unevenness of the lower portion is reflected on the upper protective film of the portion corresponding to the recess formed between the adjacent R, G, and B portions of the colored layer and the portion of the colored layer having a different thickness. FIG. 4(A) shows a cross-sectional view of a color filter with a colored layer formed thereon. There is a space 5 between the RlG and H portions of the colored layer, and there is a height difference in R, G, and B. A step 6 has occurred. When a protective film is formed on such a colored layer, the conventional protective film material has large surface irregularities corresponding to the unevenness of the lower part, as shown in FIG. However, in the protective film of the present invention, even if the lower part has large irregularities as shown in FIG. As a result, the flatness of the transparent electrode formed on the protective film also becomes good.

In addition, in the protective film made of the photosensitive resin of the present invention, the polyfunctional photopolymerizable polymer acts as a crosslinking agent, and as a result, the degree of crosslinking of the resin increases, and when the film has a hardness of only oligomer, the pencil hardness is HB ~ 2H improved to 4H to 9H. As a result, the heat resistance is about 250°C, and the protective film has a heat resistance of about 250°C. Even when a thick transparent conductive film of about 2 to 0.4 μm was formed, no cracks or wrinkles were generated in the color filter.

Furthermore, many commercially available silane coupling agents can be used as the silane coupling agent to be applied to the transparent substrate or added to the resin before applying the resin, but in particular, γ-(2-amino It is preferable to use ethyl)aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and the like.

Example 1 Red, green, and blue pigments are dispersed in a photosensitive resin at the composition ratios shown in Table 1, respectively, to produce red, green, and blue colored photosensitive resins.

[Margins below] Table 1 (Unit: Weight %) The substrate was a glass substrate with a thickness of 1.1 mm (A made by Asahi Glass).
L material) should be thoroughly washed before use.

On top of that, a red photosensitive resin was applied to a film thickness of 1.2 μm, then dried in an oven at a temperature of 70°C for 30 minutes, exposed using a mercury lamp, and spray developed with water for 1 minute. A red relief image was formed in the area where red pixels were to be formed, and further heated at 150°C for 30 minutes.
Cured by heating.

Similar steps were repeated to form a green relief pixel in the region where the green pixel was to be formed, and a blue relief pixel in the region where the blue pixel was to be formed, thereby forming a colored layer.

Next, as a photocurable acrylate oligomer, 0-talesol novolac epoxy acrylate (molecular weight 15
00-2000), 50 parts by weight, polyfunctional polymerizable polymer
as dipentaerythritol hexaacrylate (
50 parts by weight of D P HA manufactured by Nippon Kayaku ■ were mixed, and Irgacure (Ciba Geigy ■) was added as a polymerization initiator.
A mixture of 2 parts by weight of ethyl cellosolve acetate was dissolved in 200 parts by weight of ethyl cellosolve acetate, and 10 g of the solution was applied to the colored layer to a thickness of 2.0 μm using a spin coater. 2. By placing a photomask and using a proximity aligner. Only the colored layer was irradiated with ultraviolet rays for 10 seconds using an OKW ultra-high pressure mercury lamp. Subsequently, it was immersed for 1 minute in a developer consisting of 1.1.2.2 tetrachloroethane at a temperature of 25° C. to remove only the uncured portion of the coating film.

Next, sputtering is performed on the formed protective film.
It was coated with an IT○ film (composite film of indium oxide and tin oxide) having a thickness of 0.4 μm.

When the flatness of the transparent electrode layer was measured using a probe film thickness meter, the unevenness was as small as 0.01 μm −0.05 μm, and the flatness was good.

In addition, the obtained color filter showed sufficient heat resistance, with no abnormalities observed even when heated to 250°C.

Example 2 A membrane formed from a resin having the same composition as in Example 1. γ-(2-aminoethyl)aminopropyltrimethoxysilane (manufactured by Toshi Silicone SH6) as a silane cambling agent.
A trap formed by applying a 01 to 02% solution of 020) to a glass substrate and then applying the resin of Example 1.A film formed from the resin of Example 1 to which a silane coupling agent was added, the adhesive strength of the applied film When evaluated by the base test (JIS standard), the results were as shown in Table 2. In the same table, “
"Treatment of the substrate" and "addition to the resin" mean treatment of the substrate with silane coupling or addition to the resin of Example 1.

Further, the protective film of the present invention and the protective film treated with the silane coupling agent had excellent properties in terms of adhesive strength, and no change in properties occurred in terms of transparency or light transmission properties.

Table 2 Comparative Example 1 A protective film was formed in the same manner as in the example except that no polyfunctional photopolymerizable monomer was added.

The hardness of the obtained protective film corresponded to the pencil hardness of HB to 2H.

Subsequently, an ITO film was coated on the protective film in the same manner as in the example, but wrinkles occurred in the 0.15 μm IT○ film. Moreover, the unevenness was 0.1 μm to 05 μm, and the heat resistant temperature was 220°C.

Comparative Example 2 Thermosetting acrylate product name JS as protective film material
A protective film was formed in the same manner as in the example except that S181 (manufactured by Japan Synthetic Rubber Co., Ltd.) was used and the protective film was cured by heating at 180° C. for 1 hour.

The hardness of the obtained protective film corresponded to a pencil hardness of HB or 4H.

Subsequently, an ITO film was coated on the protective film in the same manner as in the example, but wrinkles occurred in the 01 μm ITO film. Moreover, the unevenness was 0.2 μm-0.7 μm, and the heat resistant temperature was 200°C.

Comparative Example 3 Thermosetting epoxy resin as material for protective film, trade name C
A protective film was formed in the same manner as in the example except that Z-003 (manufactured by Nissero Kagaku) was used and the protective film was cured by heating at 180° C. for 1 hour.

The hardness of the obtained protective film corresponded to a pencil hardness of HB or 2H.

Subsequently, an ITO film was coated on the protective film in the same manner as in the example, but wrinkles occurred in the 01 μm ITO film. In addition, the unevenness is 02 μm to 07 μm, and the heat resistant temperature is 200 μm.
It was below ℃.

Comparative Example 4 Silicone rubber, trade name TDAIH, as material for protective film
(manufactured by Catalysts Kasei Co., Ltd.) and the curing of the protective film was
A protective film was formed in the same manner as in the example except that heating was performed at 80° C. for 1 hour.

The hardness of the obtained protective film corresponded to the pencil hardness of 3H to 9H, and the heat resistance temperature was also good at 250°C or higher, but when the ITo film was coated on the protective film in the same manner as in the example,
Crank occurred in the ITO film with a thickness of 0.2 μm or more, and the unevenness was 0.2 μm to 0.7 μm.

[Effects of the Invention] Since the color filter of the present invention does not have a protective film on the outer periphery of the colored layer, sufficient adhesive strength can be obtained when the color filter and the counter electrode are bonded together. Furthermore, since the color filter is reused, the protective film is not peeled off together with the sealant and tab when the sealant and tab are peeled off.

Furthermore, since we use a photopolymerizable acrylate oligomer with a multifunctional photopolymerizable monomer added as the resin for the protective film, the resin has a high degree of cross-linking, making it possible to obtain a rigid and hard film. Even if a thick transparent conductive film is formed on the substrate, no wrinkles or cracks will occur, and a protective film with excellent flatness with few irregularities can be obtained, so the formed transparent conductive film has extremely excellent flatness. Since the periphery of the protective film does not peel off from the transparent substrate, a color filter of excellent quality can be manufactured.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the color filter of the present invention coated with uncured resin, Figure 2 is a cross-sectional view illustrating exposure to ultraviolet light with a photomask placed, and Figure 3 is the completed color filter. A cross-sectional view of the color filter of the present invention, FIG. 4 shows the unevenness of the protective film, and also shows the transparent substrate...1, the colored layer...2
, Protective film...3, Photomask...4, Space...5, Step 6 Output

Claims (5)

[Claims] (1) A colored layer is formed on a transparent substrate, and a resin made of a mixed system of a photopolymerizable acrylate oligomer and a multifunctional photopolymerizable acrylate monomer having two or more functionalities is applied onto the colored layer, and ultraviolet light is applied to the top surface of the colored layer. A color filter characterized by being cured to form a protective film. (2) In the resin, only the resin in a predetermined area of the color filter is cured with ultraviolet light through a mask, etc., and the uncured resin is dissolved and removed with a solution that is compatible with the resin in the uncured part, and the predetermined area is removed. Claim 1 in which a protective film is formed only on
Color filters listed. (3) The color according to claim 2, wherein the photopolymerizable acrylate oligomer or monomer contains an acid anhydride, and the uncured portion is dissolved and removed in an alkaline aqueous solution to form a protective film only in a predetermined area of the color filter. filter. (4) The color filter according to any one of claims 1 to 3, wherein the resin is applied after applying a silane coupling agent onto a transparent substrate. (5) Any one of claims 1 to 3, characterized in that the resin is coated with a silane coupling agent added thereto.
Color filters as described in section.