JPH107982A - Photocurable coating composition and method for producing substrate having light-shielding thin film on surface - Google Patents

Abstract

(57) [Problem] A photocurable coating material which is excellent in various characteristics required for a light-shielding thin film such as a color filter for LCD, capable of forming a fine shape, and excellent in storage stability and dispersion stability. Provided are a composition and a method for producing a high-quality substrate having a light-shielding thin film on the surface. SOLUTION: A carbon black pigment having a specific surface area of 50 m ² / g or less is used as a light-shielding material, and at least one epoxy resin having a polyalkylene oxide chain in a molecule and at least one α, β ethylenically unsaturated acid are used. To produce a photocurable coating composition containing, as a polymer material, a photocurable resin obtained by reacting the above with a light-curable resin, and a substrate is produced using the light-shielding coating composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a photocurable coating composition and its application. More specifically, the present invention particularly relates to a photocurable coating composition useful for forming a light-shielding thin film of a color filter used for a liquid crystal display device, an imaging device, and the like, and an application thereof.

[0002]

2. Description of the Related Art In a color filter used for a liquid crystal display device (LCD) or the like, for example, a color filter formed on a transparent substrate is used in order to improve contrast and color purity or to prevent light leakage to a switching device and the like. It is known to provide a light-shielding thin film called a black matrix in the gap between each of the transparent colored fine patterns of red, green, and blue, and to provide a light-shielding thin film that blocks unnecessary light on a substrate disposed on a switching element. ing.

In recent years, LCDs have rapidly increased in size and definition,
With the increase in production volume, etc., demands for various characteristics, productivity, and the like of the light-shielding thin film have been further strengthened. For example, in addition to having high light-shielding properties, the flatness and smoothness of a coating film, and better adhesion with a substrate or an overcoat (protective film), and more recently, heat resistance, water resistance, and moisture resistance There is an increasing demand for reliability such as alkali resistance, solvent resistance, and liquid crystal resistance.

As materials for forming such a light-shielding thin film, metal-based and resin-based materials are mainly used.
A chromium or the like is used as the metal-based material, and a coating composition containing a polymer material such as a resin and a light-shielding material such as carbon black is used as the resin-based material. However, metal materials such as chromium have problems such as environmental pollution, high light reflectance of the formed light-shielding thin film, and high production cost. Have been.

[0005] As the resin-based material, photosensitive paints, alkali- or solvent-soluble paints, electrodeposition paints, printing inks, etc., each containing a polymer material and a light-shielding material, are industrially used. . That is, the photosensitive paint is a method of performing predetermined exposure after application and developing.
Alkali or solvent-soluble paint, after application, form a photoresist layer on the coating film, after exposing through a photomask having a predetermined pattern, developing and removing the predetermined photoresist layer to form a predetermined pattern A method of exposing the surface of an alkali or solvent-soluble coating film and then developing with an alkali or a solvent, or a method of simultaneously developing a photoresist layer and an alkali or solvent-soluble coating film with an alkali or a solvent, an electrodeposition paint is optionally used. A light-shielding thin film can be formed by a method of forming a coating film on the patterned transparent conductive layer by an electrodeposition method, and a method of directly printing a printing ink using characters.

[0006] Among these resin-based materials, photosensitive coatings, especially photocurable coatings, are industrially advantageous. A light-shielding thin film can be formed industrially advantageously using a photocurable coating by a method described in, for example, JP-A-62-247331. That is, first, a desired transparent colored fine pattern is formed on a transparent substrate by an electrodeposition method, a photocurable paint is applied to the entire surface of the substrate so as to cover the formed transparent colored fine pattern, and then from the back surface of the substrate. This is a method well-known as a so-called backside exposure method in which exposure and development are performed.

However, in the case of such a back exposure method, a film-forming property is insufficient, a gap is formed between the transparent colored fine patterns, or a light-shielding thin film is formed on the transparent colored fine patterns. Are likely to occur, and it is desired to solve them.

[0008]

DISCLOSURE OF THE INVENTION The present inventors have satisfied various requirements for a light-shielding thin film of a color filter used for a liquid crystal display element without being affected by a method of forming a light-shielding thin film. The present inventors have conducted intensive studies on industrially advantageous resin materials having excellent storage stability and dispersion stability, and have found a specific photocurable coating composition to complete the present invention.

[0009]

According to the present invention, the specific surface area is 5
A carbon black pigment of 0 m ² / g or less is used as a light-shielding material, and is obtained by reacting at least one kind of epoxy resin having a polyalkylene oxide chain in the molecule with at least one kind of α, β ethylenically unsaturated acid. Provided is a photocurable coating composition comprising a photocurable resin as a polymer material, and a method for producing a substrate having a light-shielding thin film on the surface using the coating composition.

[0010]

Embodiments of the present invention will be described below in detail. The carbon black pigment used in the present invention may be any known one, and is commercially available as carbon black such as furnace black, channel black, thermal black, acetylene black, lamp black, bone black, graphite powder or graphite powder. And the like.

The carbon black pigment used in the present invention is:
It has a specific surface area of 50 m ² / g or less as measured by a nitrogen gas adsorption method. Among these carbon black pigments, 50 m ²
/ G～10m preferably has in the range of ² / g, more preferably is within the range of 30m ² / g~15m ² / g.

The amount of the carbon black pigment used is preferably
It is not less than 5% by weight, more preferably from 15% by weight to 60% by weight, based on the total solid content in the coating composition of the present invention.

The coating composition of the present invention contains the above-mentioned carbon black pigment as an essential light-shielding material. In addition, if desired, black pigments such as titanium black, black iron oxide, bismuth sulfide, and perylene black; Extender pigment,
Other light-shielding materials such as direct dyes, acid dyes, reactive dyes, disperse dyes, oil-soluble dyes, and vat dyes can be included as long as the effects of the present invention are not impaired.

The photocurable resin used as the polymer material in the present invention can be easily prepared by reacting at least one epoxy resin having a polyalkylene oxide chain in the molecule with at least one α, β ethylenically unsaturated acid. Can be manufactured.

Epoxy resins having a polyalkylene oxide chain in the molecule are known per se, and diglycidyls such as polyalkylene glycol diglycidyl ether and diglycidyl ether of a compound obtained by adding an alkylene oxide to a phenyl group of bisphenol. Etherified compounds can be exemplified. Here, bisphenols include bisphenol A, bisphenol F, bisphenol S, and the like. As alkylene oxides, ethylene oxide, propylene oxide,
Butylene oxide and the like. As the α and β ethylenically unsaturated acids, acrylic acid and methacrylic acid are typically exemplified.

The reaction between such an epoxy resin and an α, β ethylenically unsaturated acid is carried out at a temperature of about 80 to 150 ° C.
Preferably, the reaction can be carried out in the presence of an organic solvent inert to a reaction such as ethers and esters.

The amount of double bonds of the photocurable resin thus obtained is required for the photocurability at the time of forming the light-shielding thin film and the characteristics of the formed light-shielding thin film, especially for a color filter. In view of various characteristics, 1 to 5 mol / k
g resin is desirable. Further, in consideration of an industrially limited amount of ultraviolet irradiation at the time of photocuring, the amount of double bonds is more preferably 2 to 4 mol / kg resin.

The amount of such a double bond is usually about 0.5 to 2 parts per mole of an epoxy resin having a polyalkylene oxide chain in the molecule. It can be obtained by appropriately selecting from the molar range.

The weight (solid content) ratio of the photocurable resin used as the polymer material to the light-shielding material is preferably from 90 to 30:10 to 70 in consideration of various characteristics of the formed light-shielding thin film.

Further, the coating composition of the present invention may contain a commonly used photopolymerization initiator according to the conditions of ultraviolet irradiation. Benzoins such as benzoin, benzoin methyl ether, and the like,
Acetophenone, acetophenones such as 2,2-dimethkin-2-phenylacetophenone, anthraquinones such as 2-ethylanthraquinone, thioxanthones such as 2,4-dimethylthioxanthone, and ketals such as acetophenone dimethyl ketal are exemplified. The amount used is suitably from 0.1 to 10% by weight based on the weight (solid content) of the photocurable resin and the light-shielding material used as the polymer material.

The coating composition of the present invention may further contain a photoreactive diluent, an organic solvent, various coupling agents,
A polymerization inhibitor, a dispersing aid, a spreading agent, a thickening (low) viscosity agent, a filler, and the like may be appropriately used.

The coating composition of the present invention can be produced by uniformly dispersing and mixing these materials using a roll mill, a ball mill, a sand mill, a bead mill or the like according to a conventional method.

The photocurable coating composition of the present invention thus obtained is particularly useful for producing a substrate having a light-shielding thin film called a black matrix on the surface. Such a light-shielding thin film may be formed on a substrate on which a transparent colored fine pattern such as red, green, and blue may be formed.
It can be formed by a known method. That is,
The light-shielding thin film may be formed after or before the formation of the transparent colored fine pattern and may be formed in the gap between the transparent colored fine patterns, and may be formed on a separate substrate independently of the transparent colored fine pattern. Can also.

For example, a transparent colored fine pattern is formed on a transparent substrate such as glass by a known method such as a printing method, a photolithography method, and an electrodeposition method.
By using the coating composition of the present invention to form a light-shielding thin film by a known method, a substrate having a light-shielding thin film in a gap between transparent colored fine patterns can be manufactured.

Specifically, for example, Japanese Patent Application Laid-Open No. Sho 62-247
No. 331, a desired transparent colored fine pattern is formed on a transparent substrate by an electrodeposition method, and then the coating composition of the present invention is coated on the substrate so as to cover the formed transparent colored fine pattern. A desired substrate can be obtained by a method well-known as a so-called back exposure method, in which application is performed on the entire surface of the substrate, and then exposure and development are performed from the back surface of the substrate.

The coating composition of the present invention is characterized in that a desired substrate can be obtained without any problem even by such a back exposure method.

Alternatively, according to the method described in Japanese Patent Application Laid-Open No. 7-35920, a desired light-shielding thin film having a window frame shape is first formed, and then a transparent colored fine pattern having a window shape is formed. A substrate can be obtained.

[0028]

The present invention will be described in more detail with reference to the following examples. In the examples, parts and% represent parts by weight and% by weight, respectively, unless otherwise specified.

Reference Example (Production of photocurable resin) Diethylene glycol dimethyl ether 46.2 parts Epolite 3002 326.0 parts [Diglycidyl ether of propylene oxide-modified bisphenol A, epoxy equivalent 326 g / equivalent, Kyoeisha Yushi Kagaku Kogyo Co., Ltd. Acrylic acid 72.0 parts Methoxyhydroquinone 0.6 parts Triethylbenzylammonium chloride 1.2 parts

4 having a stirrer, a thermometer and a condenser
In a one-necked flask,,, and were charged into the flask, the temperature was increased with stirring, and maintained at 120 ° ± 3 ° C. for 6 hours until the acid value became 5 or less. In this way,
A viscous photocurable resin (nonvolatile resin content: 90%, double bond amount: 2.5 mol / kg resin) was obtained.

Examples Photocurable resin 75 parts Propylene glycol monomethyl ether 100 parts Raben 410 25 parts [Furness black having a specific surface area of 27 m ² / g, manufactured by Columbian Co.] A-1120 2 parts [Silane coupling agent, Japan Unicar Co., Ltd.] Irgacure 907 1 part [Photoinitiator, Ciba Geigy Co., Ltd.]

The mixture of and is mixed with glass beads [EGB-503MM, manufactured by Toshiba Barotini Co., Ltd.]
For 5 hours, and the dispersion was further subjected to a dispersion treatment with a roll mill. Then, was added to obtain a photocurable coating composition.

A transparent conductive film of an ITO film having a width of 80 μm is formed of 20
Glass substrates attached in strips at μm intervals were used. The surface resistivity of this conductive film was about 60 Ω / cm ² . On this transparent substrate, a red electrodeposition coating [Chromophtal Red A
25 parts by weight of 2B (made by Ciba-Geigy) and Sbeer # 30
00 clear (adjusted using 75 parts by weight of an electrophoretic thermosetting resin manufactured by Shinto Paint Co., Ltd.).
Electrodeposition at 0 V for 10 to 20 seconds, washing with water and 200 ° C
For 30 minutes to obtain a transparent colored fine pattern having a thickness of about 1.5 μm.

The photocurable coating composition obtained above was applied to the entire surface of the glass substrate by screen printing, and prebaked at 90 ° C. for 10 minutes to obtain a coating film having a thickness of about 8 μm. The substrate was exposed from the back side at 80 W / cm ² irradiance for 3 to 20 seconds using a high-pressure mercury lamp. Thereafter, the film was immersed in butyl cellosolve at room temperature for 2 minutes to remove the unexposed film, washed with ion-exchanged water, and heated at 200 ° C. for 30 minutes. Thus, the film thickness is about 1.5 μm
A substrate having on its surface a patterned light-shielding thin film was obtained.

The obtained substrate has no light leakage at the boundary between the light-shielding thin film and the colored pattern, has a flat surface and high uniformity, and can be used alone or sandwiched between polarizing plates from both sides. Even when the polarization axes of the two polarizing plates were orthogonal to each other, there was no light leakage, high light-shielding properties were obtained, and a good finish was obtained as a color filter. No deterioration was observed even after storing this photocurable coating composition in a cool and dark place for one month,
The stability was also good.

[0036]

As described above, according to the present invention, the film has high light-shielding properties, excellent flatness and smoothness of a coating film, excellent adhesion to a substrate and an overcoat (protective film), heat resistance, water resistance, moisture resistance, and water resistance. In particular, since a highly reliable light-shielding thin film having a predetermined shape can be formed irrespective of the forming method, the reliability is high, such as alkalinity, solvent resistance, and liquid crystal resistance.
Industrial Applicability A light-shielding coating composition useful for forming a light-shielding thin film of a color filter for use, and excellent in storage stability and dispersion stability is provided industrially.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location // C08F 290/06 C08F 290/06 299/02 MRV 299/02 MRV (72) Inventor Ki Nakatsuka 6-10-73 Minamitsukaguchicho, Amagasaki City, Hyogo Prefecture Shinto Paint Co., Ltd.

Claims (6)

[Claims] 1. A carbon black pigment having a specific surface area of 50 m ² / g or less is used as a light-shielding material, and at least one of an epoxy resin having a polyalkylene oxide chain in a molecule and at least one of α and β ethylenically unsaturated acids is used. A photocurable coating composition comprising, as a polymer material, a photocurable resin obtained by reacting with one kind. 2. The coating composition according to claim 1, wherein the carbon black pigment is carbon black or graphite. 3. The coating composition according to claim 1, wherein the content of the carbon-based black pigment is 5% by weight or more based on the total solids in the composition. 4. The coating composition according to claim 1, wherein the photocurable resin has a double bond amount of 1 to 5 mol / kg resin. 5. The coating composition according to claim 1, wherein the weight ratio of the photocurable resin to the carbon-based black pigment is from 90 to 30:10 to 70. 6. A method for producing a substrate having a light-shielding thin film on a surface thereof, comprising forming a light-shielding thin film on the surface of the substrate using the coating composition according to claim 1.