JPH0943836A - Color resist and color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color filter hardly affected by exposure in a green picture element by providing a colored transparent coating film obtained by photosetting a color resist composed of a water soluble resin, a pigment, a water soluble diazo resin and a polyaniline. SOLUTION: The color filter is formed by laminating a glass substrate, a transparent electrode and the colored transparent coating film in this order. The colored transparent coating film is obtained by applying the color resist on a transparent coating film and photosetting. The color resist is composed of the water soluble resin, the pigment, the water soluble diazo resin and the polyaniline. The water soluble resin preferably consists essentially of 2- hydroxyethyl(metha)acrylate. The water soluble resin is obtained by dissolving 2-hydroxyethyl(metha)acrylate monomer and a water soluble comonomer in an adequate solvent and copolymerizing with a polymerization initiator. As the water soluble comonomer, a water soluble vinyl monomer such as (metha) acrylic acid is mentioned.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a color resist and a color filter for a liquid crystal display device.

[0002]

2. Description of the Related Art Color filters are generally used as color filters for liquid crystal display devices, color separation filters for printing, and the like. Conventionally known as such a color filter is a dyed color filter which forms a colored transparent coating film by dyeing a hydrophilic polymer substance such as gelatin, casein, glue, and polyvinyl alcohol on a substrate with a dye or a pigment. There is.

Color filters for liquid crystal display devices include a lower electrode type color filter having a colored transparent coating film provided on a transparent electrode and an upper electrode type color filter having a colored transparent coating film provided under a transparent electrode. . The lower electrode type color filter has a colored transparent coating similar to an insulator between the electrodes, so the display quality is somewhat inferior, but the electrode formation is easier and the manufacturing cost is significantly higher than that of the upper electrode type color filter. cheap.

[0004]

However, the lower electrode type color filter including the transparent coating film of the three primary colors of red, green and blue is not affected by the voltage / voltage in the green pixel portion when exposed to backlight or outside light.
The phenomenon that the light transmission curve moves to the low voltage side is recognized. On the other hand, the red and blue pixel portions are hardly affected by the exposure, so that there is a problem that the balance of the entire color filter is lost and normal display cannot be performed.

Such an abnormal phenomenon is caused by a typical photoconductive substance such as a phthalocyanine which is a pigment used as a photoconductor for electrophotography, laser printers, etc., and therefore backlight, external light, etc. It is considered that this is caused by the electric charge generated in the pigment particles of the phthalocyanine compound by the exposure to, which affects the alignment of the liquid crystal molecules. Therefore, there is a demand for a colored transparent coating film that can reduce the density of charges generated by exposure and diffuse the charges.

As a method of diffusing the charge generated by exposure, a method of forming a colored transparent coating film by dispersing conductive fine particles such as tin oxide, antimony-doped tin oxide, indium tin oxide, etc. can be considered. However, these conductive fine particles have no effect unless added in high concentration,
Further, since it absorbs ultraviolet rays, there is a problem that the photosensitivity is lowered.

The present invention is intended to solve the above problems, and an object of the present invention is to diffuse charges generated by a backlight, external light, etc., so that a green pixel is not easily affected by exposure. It is to provide a color filter and a color resist used therefor.

[0008]

The above object is to provide a color filter comprising a glass substrate, a transparent electrode and a colored transparent coating laminated on each other, wherein the colored transparent coating is formed by applying a color resist to the transparent electrode. It is obtained by photo-curing and can be achieved by a color filter in which the color resist is composed of a water-soluble resin, a pigment, a water-soluble diazo resin and polyaniline. Hereinafter, the present invention will be described in detail.

The color filter of the present invention comprises a glass substrate, a transparent electrode and a colored transparent coating film, which are laminated in this order. The colored transparent coating film is obtained by applying a color resist to the transparent coating film and photocuring it. The method of applying the color resist to the transparent electrode is not particularly limited, and examples thereof include spin coating and roll coating. The photo-curing is not particularly limited, and examples thereof include those using ultraviolet light.

The color resist comprises a water-soluble resin, a pigment, a water-soluble diazo resin and polyaniline. The water-soluble resin preferably contains 2-hydroxyethyl (meth) acrylate as a main component. When the water-soluble resin has a hydroxyethyl group, when combined with a water-soluble diazo resin which will be described later, it is easily photocrosslinked and has excellent adhesiveness to a glass substrate. The water-soluble resin can be obtained, for example, by dissolving a 2-hydroxyethyl (meth) acrylate monomer and a water-soluble comonomer in an appropriate solvent and copolymerizing them with a polymerization initiator.

The above water-soluble comonomers are usually
(Meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, methoxymethyl ( Water-soluble vinyl monomers such as (meth) acrylamide, ethoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, N-vinylpyrrolidone, acrylamido-t-butylsulfonic acid, maleic acid, fumaric acid, and (meth) acrylic acid. And one or more of these are used.

Of the above water-soluble comonomer components, the (meth) acrylic acid component is preferred because it has the effect of improving the affinity for pigments, increasing the pigment concentration in the color resist, and reducing the thickness of the colored film. The content of the (meth) acrylic acid component is preferably 0 to 30% by weight in the water-soluble resin. If it exceeds 30% by weight, the water solubility of the resin is lowered, and an organic solvent such as alcohol must be used in combination.

As the solvent, an organic solvent such as methyl cellosolve or dimethylformamide can be used. However, since all the monomers used are water-soluble, it is preferable to use water or an aqueous acetic acid solution.

When the above-mentioned 2-hydroxyethyl (meth) acrylate and the water-soluble comonomer are copolymerized in water or an aqueous acetic acid solution, ammonium persulfate, 2,2'-azobis (N, N'-di) is used as a polymerization initiator. Methyleneisobutylamidine) hydrochloride, 2,2'-azobis (2-amidinopropane) hydrochloride,
4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis (2-methyl-N [1,1-
Bis (hydroxymethyl) -2-hydroxyethyl] propionamide) and the like are used.

As the copolymerization method, an aqueous solution or acetic acid solution in which the 2-hydroxyethyl (meth) acrylate, the water-soluble comonomer and the polymerization initiator are uniformly dissolved is prepared, and water or acetic acid water is added thereto. The reactor is heated under stirring while being added dropwise or dividedly into the reactor,
A method of carrying out the copolymerization while maintaining it at an appropriate temperature is preferably adopted. When all monomers are charged at once and copolymerized,
In many cases, the reaction solution rapidly gels during the polymerization process, resulting in gelation of the reaction solution. The polymerization temperature varies depending on the type of the polymerization initiator, but is usually preferably 50 to 90 ° C.
When the temperature is lower than 50 ° C, it is difficult to control the reaction temperature even if it is within the range of practical decomposition rate. 90 ° C
If it exceeds, the monomer may be azeotroped with water to change the composition of the charge, which is not preferable. The polymerization time is several hours.

The content of the 2-hydroxyethyl (meth) acrylate component which is a constituent of the water-soluble resin thus obtained is preferably 50 to 90% by weight in the above water-soluble resin. If it is less than 50% by weight, the polymerizability (crosslinking property) of the water-soluble resin is lowered, and if it exceeds 90% by weight, microgels are easily generated in the water-soluble resin and the dispersibility of the pigment is also lowered. Tend. More preferably, it is 60-8
0% by weight.

The amount of the water-soluble resin compounded is preferably 30 to 50% by weight based on the solid content in the color resist. When it is less than 30% by weight, the strength of the obtained colored transparent coating film is insufficient, and when it exceeds 50% by weight, the color density of the colored transparent coating film is lowered and it becomes difficult to form a thin film color filter.

The pigment used in the present invention may be either an organic pigment or an inorganic pigment. When making a color filter, it is preferable to use an organic pigment having a wide selection of transmitted light spectra. The organic pigment is not particularly limited,
For example, various known pigments such as phthalocyanine type, insoluble azo type, condensed azo type, azo lake type, anthraquinone type, quinacridone type, isoindolinone type, perylene type and dioxane type pigments can be used. The average particle size of the pigment particles is preferably 100 nm or less. If it exceeds 100 nm, the resulting colored transparent coating film may appear cloudy.

In the present invention, the pigment is used as a fine powder pigment dispersion. Such a pigment dispersion is, for example,
It can be prepared by the following method. A pigment, water, and a surfactant as necessary are mixed, and this is mixed with a bead mill,
Using a disperser such as an attritor or a paint conditioner, the mixture is stirred for several hours to several tens of hours and sufficiently mixed and dispersed to obtain a pigment dispersion. After that, a dispersant is added to this pigment liquid to stabilize the dispersion state to obtain a pigment dispersion liquid. At this time, since the viscosity of the dispersion liquid sharply increases, it is preferable to add the dispersant while stirring the pigment liquid. Coexisting coarse particles are removed by centrifugation or filtration.

The above surfactant is not particularly limited,
For example, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether and polyoxyethylene lauryl ether; nonionic surfactants such as polyoxyethylene alkylaryl ethers such as polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether. Is mentioned.

The amount of the above-mentioned surfactant compounded is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the pigment. If it is less than 1 part by weight, the dispersing effect may be insufficient, and if it exceeds 50 parts by weight, when a colored transparent coating film is prepared using the color resist of the present invention, stickiness of the coating film and water resistance are produced. In some cases, deterioration of heat resistance and heat resistance may occur.

The dispersant is not particularly limited, and examples thereof include vinyl acetate polymers, vinyl acetate-vinylpyrrolidone copolymers, vinyl acetate- (meth) acrylic acid copolymers,
Examples thereof include vinyl alcohol copolymers such as vinyl acetate-maleic acid copolymers and vinyl acetate-ethylene copolymers.

Generally, the amount of the pigment dispersion liquid is preferably 50 to 200 parts by weight with respect to 100 parts by weight of the water-soluble resin. If it is less than 50 parts by weight, the degree of coloring may be insufficient, and if it exceeds 200 parts by weight, the photosensitivity is lowered, and the film-forming ability is lowered due to the shortage of the water-soluble resin content, resulting in a fine image. It may be difficult to make.

The water-soluble diazo resin used in the present invention is
It is a resin with a low degree of polymerization obtained by condensation of an aromatic diazonium salt and formaldehyde. The aromatic diazonium salt is not particularly limited, and examples thereof include p-diazodiphenylamine sulfate and 2,5-dimethoxy-4-p-.
Trilmercaptobenzenediazonium sulfate, 2,5
-Dimethoxy-4-morpholinobenzenediazonium sulfate and the like can be mentioned. The content of the water-soluble diazo resin is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the water-soluble resin. If it is less than 5 parts by weight, the photocrosslinking property may be insufficient, and if it exceeds 30 parts by weight, the light absorption by diazo may be large and the photocrosslinking of the lower layer of the coating film may be insufficient.

In the present invention, polyaniline is used as a substitute for the inorganic conductive material for the purpose of imparting conductivity while maintaining the transparency of the colored transparent coating film. The polyaniline has good dispersion stability, can exhibit a conductive effect at a low concentration, and does not impair the photosensitivity of the pigment.

The above polyaniline is synthesized by, for example, an electrolytic polymerization method, an oxidative polymerization method or the like. The latter is often used industrially. Synthesis of polyaniline by the oxidative polymerization method, for example, organic sulfonic acid, a dopant such as sulfate, dichromate in an aqueous solution containing aniline,
It can be performed by adding an oxidizing agent such as hydrogen peroxide and stirring. The polyaniline has different polymer structure and solubility depending on the oxidation conditions during synthesis, but in the present invention, since the polyaniline is used in a dispersion system, the structure and solubility are not particularly limited.

The polyaniline content is preferably 0.5 to 20% by weight based on the solid content of the color resist solid content. If it is less than 0.5% by weight, the conductivity may not be improved, and if it exceeds 20% by weight, the color tone of the green color filter may be impaired. More preferably, 1
10 to 10% by weight.

The above-mentioned polyaniline is used as a dispersion liquid like the general organic pigments. The dispersion method is the same as in the case of the organic pigment described above, but since polyaniline is a polymer, it is necessary to increase the dispersion strength and the dispersion time as compared with the case of the organic pigment.

[0029]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Synthesis of Water-Soluble Resin 2-Hydroxyethyl Methacrylate 80 parts by weight Methacrylamide 10 parts by weight Acrylic acid 1 part by weight Dimethylacrylamide 9 parts by weight Polymerization initiator (Wako Pure Chemical Industries, Ltd., V -501) 1 part by weight-10% acetic acid water 200 parts by weight While feeding nitrogen into the reactor containing 10% acetic acid water 200 parts by weight, the above monomer mixture was added dropwise over 3 hours. The mixture was stirred at a temperature of 83 ° C. in the reactor and cooled to room temperature 8 hours after the start of dropping. The reaction mixture was diluted with an equal weight of deionized water and then filtered through a filter having a pore size of 0.45 μm.

Preparation of polyaniline solution : Polyaniline powder (Allied Signal Co., Versicon) 20 parts by weight Nonionic surfactant (Daiichi Kogyo Seiyaku Co., Neugen EA189) 4 parts by weight Deionized water 76 parts by weight The mixture was placed in a sand mill and stirred for 3 hours to obtain a dark green polyaniline solution. When measured with a light-scattering type particle size distribution analyzer, the average particle size was 210 nm.

Preparation of polyaniline dispersion liquid : 100 parts by weight of polyaniline solution: 8% by weight of Poval aqueous solution (KM-11, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 88 parts by weight of deionized water: 47 parts by weight 8% aqueous solution of povar in polyaniline solution Was added and stirred for 3 hours to obtain a stable dispersion liquid.

Preparation of green pigment liquid 20 parts by weight of cyanine green 4 parts by weight of nonionic surfactant (Neugen EA189 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 76 parts by weight of deionized water The above mixture was stirred with a sand mill for 3 hours. Then, a green pigment liquid was obtained. The average particle size was 105 nm. Preparation of yellow pigment liquid: Disazo yellow 20 parts by weight Nonionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neugen EA189) 4 parts by weight Deionized water 76 parts by weight The above mixture is stirred for 3 hours in a sand mill, A yellow pigment liquid was obtained. The average particle size was 110 nm.

Toning green pigment liquid and yellow pigment liquid are mixed in a weight ratio of 70/30,
After stirring for 2 hours to prepare a green liquid, it was mixed with a Poval aqueous solution and stirred for 3 hours to obtain a green pigment dispersion.・ Green liquid 100 parts by weight ・ 8% Poval aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., KM-11) 88 parts by weight ・ Deionized water 47 parts by weight

Preparation of green color resist : 100 parts by weight of green pigment dispersion; 10 parts by weight of polyaniline dispersion; 60 parts by weight of water-soluble resin; 14 parts by weight of deionized water. After stirring the above mixture for 5 hours, 10% diazo aqueous solution. 9 parts by weight (DO13, manufactured by Shinko Giken Co., Ltd.) was added, and the mixture was further stirred for 30 minutes to obtain a green color resist.

Preparation of Photocured Film A green color resist was spin-coated on a glass plate with ITO. It was irradiated with ultraviolet rays at 450 mJ / cm ² , developed and dried to obtain a 0.78 μm thick green transparent coating film. On the green transparent coating film, a thermosetting acrylic resin liquid was applied and cured to form a protective coat layer, and then a polyimide liquid was applied to form an alignment film. An alignment film treatment was performed on a homogenous glass plate, which was attached to a glass plate on which a green transparent coating film was formed, and liquid crystal was injected to prepare a liquid crystal cell.

The resulting liquid crystal cell was placed on an overhead projector and exposed for 12 hours. When the CIE chromaticity was measured, the y value was 0.585 and was 0.
It was almost the same as 594.

Comparative Example 1 Preparation of green color resist 100 parts by weight of green pigment dispersion 60 parts by weight of water-soluble resin 24 parts by weight of deionized water Except that the composition of the green color resist was changed as described above. A liquid crystal cell was obtained in the same manner as in Example 1. When an exposure test was conducted using the obtained liquid crystal cell in the same manner as in Example 1, the y value was 0.535, which was considerably lower than the value before exposure of 0.597.

[0039]

Since the color resist and the color filter of the present invention have the above-mentioned constitution, the color filter obtained can diffuse the charges generated by the backlight, external light, etc., and the green pixel is affected by the exposure. Without receiving
It can be suitably used as a color filter for a liquid crystal display device.

Claims (2)

[Claims] 1. A color resist comprising a water-soluble resin, a pigment, a water-soluble diazo resin and polyaniline. 2. A color filter formed by laminating a glass substrate, a transparent electrode and a colored transparent coating film, wherein the colored transparent coating film is obtained by applying a color resist to the transparent electrode and photocuring the resist. A color filter, wherein the color resist comprises a water-soluble resin, a pigment, a water-soluble diazo resin, and polyaniline.