JP2003107703A - Photosensitive resin composition for spacer of liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition for a spacer of a liquid crystal display which has preferable stability with time, excellent surface flatness, heat resistance and solvent resistance and small undercut after being developed and which can be developed with an alkali developer solution. SOLUTION: The photosensitive resin composition for a spacer of a liquid crystal display contains [A] a copolymer composed of (a1) 5 to 50 mass% of a structural unit derived from an unsaturated carboxylic acid monomer, (a2) 10 to 70 mass% of a structural unit derived from an unsaturated monomer containing an epoxy group, and (a3) 0 to 70 mass% of a structural unit derived from an olefin unsaturated monomer except for the monomers (a1) and (a2), [B] a polymerizable compound having an ethylenic unsaturated bond, [C] a photopolymerization initiator and [D] a solvent. The copolymer [A] has specified molecular weight distribution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition for a spacer of a liquid crystal display which can be applied to a liquid crystal display (including a touch panel, etc.) and, in particular, has good stability over time and, after being developed, The present invention relates to a photosensitive resin composition for a spacer of a liquid crystal display, which has excellent surface flatness, heat resistance and solvent resistance, has a small undercut, and can be developed using an alkaline developer.

[0002]

2. Description of the Related Art Conventionally, in manufacturing a liquid crystal display, it has been known that spacer beads such as glass beads or plastic beads are scattered between substrates in order to keep a fixed spacing between two substrates. Since these spacer beads are randomly dispersed on the glass substrate, they tend to be biased toward the red (R), green (G), and blue (B) pixel areas all the time, and the incident light is scattered and the contrast of the liquid crystal display is increased. There was a problem that it decreased.

In order to improve these problems, a method of forming spacers by photolithography has been proposed. According to this method, the photosensitive resin spacers can be formed on the substrate after being formed into dot-shaped or stripe-shaped spacers, and can also be spread over the areas other than the R, G, and B pixels, thus solving the above problems. it can. Further, according to this method, the cell gap can be controlled by the coating thickness of the photosensitive resin, so that the cell gap width can be easily controlled, and a liquid crystal display (LCD) with high resolution can be obtained.

There are the following three methods for forming a spacer made of a photosensitive resin on a substrate and providing a rubbed alignment film in a process of manufacturing a liquid crystal display.

Method 1. After forming a photosensitive resin spacer on the substrate, an alignment film is applied and a rubbing process is performed.

Method 2. A photosensitive resin spacer is formed after applying the alignment film and rubbing.

Method 3. After the alignment film is applied to form a photosensitive resin spacer, the alignment film is rubbed.

In the above methods 1 and 3, since the rubbing step is performed after the photosensitive resin spacer is formed, the spacer is liable to be peeled off from the substrate by the rubbing treatment to cause a display defect. In the above method 2, since the spacer is formed after applying the alignment film, if the alignment film is dissolved and swelled in the spacer formation process, or if there is a residue on the alignment film, the liquid crystal alignment property becomes abnormal. Further, in the above-mentioned manufacturing process, the surface flatness of the spacer is poor, the undercut is large, the heat resistance and the solvent resistance are poor, the spacer is likely to be deformed, and there is a drawback that the display of the display is poor. On the other hand, since the photosensitive resin composition has poor stability over time, viscosity is likely to increase, which may cause inconvenience in production, which is also a problem to be solved.

[0009]

The object of the present invention is to have good stability over time, and also to obtain surface flatness after development,
Another object of the present invention is to provide a photosensitive resin composition for a spacer of a liquid crystal display which has excellent heat resistance and solvent resistance, has a small undercut, and can be developed using an alkaline developer.

[0010]

The photosensitive resin composition for a spacer of a liquid crystal display (LCD) according to the present invention is [A]
(A1) 5% by mass to 50% by mass of a structural unit derived from an unsaturated carboxylic acid monomer, (a2) 10% by mass to 70% by mass of a structural unit derived from an unsaturated monomer containing an epoxy group, (a3) 0% by mass of structural units derived from olefinically unsaturated monomers other than (a1) and (a2)
To 70% by mass of the copolymer, [B] a polymerizable compound having an ethylenically unsaturated bond, [C] a photopolymerization initiator, and [D] a solvent. The molecular weight distribution is 10 mass% of the integrated total area of the polymer having a molecular weight of 800 to 7,000 when the integrated total area of the polymer having a molecular weight of 800 to 2,000,000 measured by gel permeation chromatography is 100% by mass. % To 23% by mass, molecular weight 70,0
A polymer of 00 or more occupies 5% by mass or less of the integrated total area.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The photosensitive resin composition of the present invention will be described in detail below.

<Copolymer [A]> The copolymer [A] used in the present invention contains an unsaturated carboxylic acid monomer forming the structural unit (a1) and an epoxy group-containing monomer forming the structural unit (a2). Saturated monomer and optionally a structural unit (a
It can be produced by radical polymerization of the olefinically unsaturated monomer forming 3) in a solvent in the presence of a polymerization initiator.

This copolymer [A] contains 5% by mass to 5% by mass of the structural unit (a1) derived from an unsaturated carboxylic acid monomer.
The content is 0% by mass, preferably 15% by mass to 40% by mass. When the content of the structural unit (a1) is less than 5% by mass, the copolymer [A] becomes difficult to dissolve in an alkaline aqueous solution, and the developability of the photosensitive resin composition deteriorates. On the other hand, when the constituent unit (a1) is contained in an amount of more than 50% by mass, the copolymer [A] becomes too soluble in an alkaline aqueous solution, resulting in poor developability.

Examples of the unsaturated carboxylic acid monomer forming the structural unit (a1) include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, α-chloroacrylic acid, ethylacrylic acid and cinnamic acid; maleic acid. ,
Examples thereof include unsaturated dicarboxylic acids (anhydrides) such as maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, and citraconic anhydride; or trivalent or more unsaturated carboxylic acids (anhydrides). Of these, acrylic acid and methacrylic acid are preferred. These unsaturated carboxylic acid type monomers are used alone or in combination.

The copolymer [A] contains the structural unit (a2) derived from an epoxy group-containing unsaturated monomer in an amount of 10% by mass to 70% by mass, preferably 20% by mass to 50% by mass. When the content of the structural unit (a2) is less than 10% by mass, the spacer has poor heat resistance and solvent resistance. On the other hand, when the constituent unit (a2) is contained in an amount of more than 70% by mass, it becomes difficult to dissolve in the alkaline aqueous solution and the developability is deteriorated.

As the epoxy group-containing unsaturated monomer forming the structural unit (a2), glycidyl acrylate, glycidyl methacrylate, glycidyl α-ethyl acrylate, 3,4-epoxybutyl acrylate, methacrylic acid-6,
7-epoxyheptyl, α-ethylacrylic acid-6,7-epoxyheptyl, o-vinylbenzyl glycidyl ether, m-
Examples thereof include vinylbenzyl glycidyl ether p-vinylbenzyl glycidyl ether. Of these, glycidyl methacrylate, -6,7-epoxyheptyl methacrylate, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether and p-vinylbenzyl glycidyl ether are preferred.

Further, the copolymer [A] contains 0 to 70% by mass, preferably 10% by mass, of the structural unit (a3) derived from an olefinically unsaturated monomer other than the above-mentioned (a1) and (a2). ˜60% by mass, particularly preferably 15% by mass to 50% by mass. The content of this structural unit (a3) is 70
If it exceeds the mass%, it becomes difficult to dissolve in an alkaline aqueous solution,
Developability deteriorates.

Examples of the olefinically unsaturated monomer forming the structural unit (a3) include methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate and t-butyl methacrylate; methyl acrylate and isopropyl. Acrylic alkyl ester such as acrylate; cyclohexyl methacrylate, 2-methylcyclohexyl methacrylate, dicyclopentanyl methacrylate, dicyclopentanyloxyethyl methacrylate, isomethanyl methacrylate, etc. cyclic alkyl ester; cyclohexyl acrylate, 2-methylcyclohexyl Acrylic acid ring such as acrylate, dicyclopentanyl acrylate, dicyclopentanyloxyethyl acrylate Alkyl ester; Dicarboxylic acid diester such as diethyl maleate, diethyl fumarate and diethyl itaconic acid; Hydroxyalkyl ester such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate; or styrene, α-methylstyrene, m-methylstyrene, Examples thereof include p-methylstyrene and p-methoxystyrene. Of these, styrene, t-butyl methacrylate, dicyclopentanyl methacrylate, dicyclopentanyloxyethyl acrylate and p-methoxystyrene are preferable. These unsaturated monomers may be used alone or in combination.

Solvents used for producing the copolymer [A] include benzene, toluene, xylene, methanol,
Ethanol, ethylene glycol monopropyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether,
Examples include ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, methyl ethyl ketone and acetone. To be Of these, diethylene glycol dimethyl ether and propylene glycol methyl ether acetate are preferable. These solvents may be used alone or in combination.

The polymerization initiator used for producing the copolymer [A] is a general radical polymerization initiator, and is 2,2'-azobisisobutyronitrile or 2,2'-azobis- (2 , 4-Dimethylvaleronitrile), 2,2'-azobis- (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis-2-methylbutyronitrile and other azo compounds, benzoyl peroxide And the like.

The copolymer [A] of the present invention has a specific molecular weight distribution. That is, when the molecular weight distribution of the copolymer [A] is measured by gel permeation chromatography (GPC) and the integrated total area of the polymers having a molecular weight of 800 to 2,000,000 is 100% by mass, the molecular weight is 800 to 7,000. The polymer in the range of 10 to 23% by mass, preferably 13 to 20% by mass of the total integrated area. When the polymer having a molecular weight in the range of 800 to 7,000 is less than 10 mass% of the integrated total area, the stability of the resin composition over time becomes poor, while when it exceeds 23 mass%, the heat resistance and solvent resistance of the resin composition are increased. Becomes worse. A polymer having a molecular weight of 70,000 or more occupies 5% by mass or less, preferably 3% by mass or less of the integrated total area. The molecular weight is
When the amount of the polymer of 70,000 or more exceeds 5% by mass of the integrated total area, the stability of the resin composition with time deteriorates and the developability also deteriorates.

<Polymerizable Compound [B] Having Ethylenically Unsaturated Bond> The polymerizable compound [B] having an ethylenically unsaturated bond used in the present invention comprises 100 parts by mass of the copolymer [A]. Based on the standard, it is preferable to add 5 to 220 parts by mass, more preferably 50 to 140 parts by mass.

As the polymerizable compound [B] having an ethylenically unsaturated bond, examples of the ethylenically unsaturated compound having one ethylenically unsaturated group include acrylamide, (meth) acryloylmorpholine and 7-amino-3. , 7-
Dimethyloctyl (meth) acrylate, isobutoxymethyl (meth) acrylamide, isobornyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethyldiethylene glycol (meth) acrylate, te
rt-octyl (meth) acrylamide, diacetone (meth) acrylamide, dimethylaminoethyl (meth) acrylate, dodecyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyl (Meth) acrylate, N, N-dimethyl (meth) acrylamide, tetrachlorophenyl (meth) acrylate, 2-tetrachlorophenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, tetrabromophenyl (meth) acrylate, 2 -Tetrabromophenoxyethyl (meth) acrylate, 2-trichlorophenoxyethyl (meth) acrylate, tribromophenyl (meth) acrylate,
2-tribromophenoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, vinylcaprolactam, N-vinylpyrrolidone, phenoxyethyl (meth) acrylate, pentachlorophenyl (meth)
Examples thereof include acrylate, pentabromophenyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and bornyl (meth) acrylate. Examples of the ethylenically unsaturated compound having two or more ethylenically unsaturated groups include ethylene glycol di (meth)
Acrylate, dicyclopentenyl di (meth) acrylate, triethylene glycol diacrylate, tetraethylene glycol di (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth)
Acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, caprolactone-modified tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide (hereinafter,
Abbreviated as “EO”. ) Modified trimethylolpropane tri (meth) acrylate, propylene oxide (hereinafter,
Abbreviated as “PO”. ) Modified trimethylolpropane tri (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol di (meth)
Acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, polyester di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipentaerythritol hexa ( (Meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol tetra (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol penta (meth) acrylate, ditrimethylolpropane tetra (meth) ) Acrylate, EO modified bisphenol A
Di (meth) acrylate, PO modified bisphenol A Di (meth) acrylate, EO modified hydrogenated bisphenol A
Di (meth) acrylate, PO modified hydrogenated bisphenol A Di (meth) acrylate, EO modified bisphenol F
Examples thereof include di (meth) acrylate and (meth) acrylate of phenol novolac polyglycidyl ether.

Of the above-mentioned ethylenically unsaturated compounds, trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, PO-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and diethyl styrene are particularly preferable. Examples thereof include pentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, dipentaerythritol tetraacrylate, caprolactone-modified dipentaerythritol hexaacrylate, and ditrimethylolpropane tetraacrylate.

<Photopolymerization Initiator [C]> The photopolymerization initiator [C] used in the present invention is 0.02 based on 100 parts by mass of the polymerizable compound [B] having an ethylenically unsaturated bond.
It is preferably blended in an amount of -60 parts by mass, more preferably 0.5-30 parts by mass.

The photopolymerization initiator [C] is a combination of an acetophenone compound and a biimidazole compound. Among them, the acetophenone compound is, for example, p-dimethylaminoacetophenone, α, α ′.
-Dimethoxyazoxyacetophenone, 2,2'-dimethyl-2-phenylacetophenone, p-methoxyacetophenone, 2-methyl- [4- (methylthio) phenol],
2-morpholino-1-propanone, 2-benzyl-2-N,
N-dimethylamino-1- (4-morpholinophenyl)-
1-butanone is mentioned. Examples of the biimidazole compound include 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-fluorophenyl) -4,5, -diphenylimidazole dimer, 2- (O−
Methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (2,4-dimethoxyphenyl)
Examples include -4,5-diphenylimidazole dimer and 2- (2-chlorophenyl) -4,5-diphenylimidazole dimer. Among these, 2-benzyl-2-N, N-
Dimethylamino-1- (4-morpholinophenyl) -1-
The effect of the photopolymerization initiator in combination with butanone and 2- (2-chlorophenyl) -4,5-diphenylimidazole dimer is relatively preferable.

The photosensitive resin composition of the present invention may further contain a photopolymerization initiator of a benzophenone compound, and specific examples of the photopolymerization initiator of the benzophenone compound include thioxanthone and 2,4-diethyl. Thioxanthone, thioxanthone-4-sulfone, benzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,
4'-bis (diethylamino) benzophenone and the like. In addition, α-diketones such as benzyl and acetyl, acyloins such as benzoin, acyloin ethers such as benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether, 2,4,6-
Trimethyl-benzoyldiphenylphosphine oxide,
Acylphosphine oxides such as bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylbenzylphosphine oxide, quinones such as anthraquinone and 1,4-naphthoquinone, phenacyl chloride, tribromomethylphenylsulfone , Halogen compounds such as tris (trichloromethyl) -s-triazine, and peroxides such as di-t-butyl peroxide. Of these, benzophenone compounds are preferable, and 4,4'-bis (diethylamino) benzophenone is particularly effective.

<Solvent [D]> The solvent [D] used in the present invention is 5 parts by weight based on 100 parts by mass of the copolymer [A].
It is preferable to add 0 to 4,000 parts by mass, more preferably 150 to 3,000 parts by mass.

This solvent [D] is used mainly for the purpose of adjusting fluidity and viscosity, can completely dissolve other organic components, and has a volatility under normal pressure. It is desirable that it is so high that it evaporates from the dispersion with a little heat energy. Therefore, the boiling point under normal pressure is 150
Solvents below ° C are most often used. If the organic solvent is selected improperly, the temporal stability of the photosensitive resin composition will deteriorate.

Examples of the solvent [D] include aromatics such as benzene, toluene, xylene; alcohols such as methanol and ethanol; ethylene glycol monopropyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol mono. Ethyl ether,
Ether systems such as diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether; esters such as methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate; methyl ethyl ketone and acetone And the like.
Among these, diethylene glycol dimethyl ether,
The use of propylene glycol methyl ether acetate alone or in combination of both is most preferable from the viewpoint of temporal stability of the photosensitive resin composition.

The content of the unreacted unsaturated carboxylic acid monomer in the photosensitive resin composition for spacers of the liquid crystal display of the present invention is preferably 8000 ppm or less on a mass basis, more preferably 6000 ppm or less, Most preferably, it is 3000 ppm or less. The content of this monomer is 800
This is because when the content is 0 ppm or less, the surface flatness is good and the undercut defect after development is improved.

A surfactant may be added to the photosensitive resin composition for spacers of the liquid crystal display of the present invention in order to improve the coating property. This surfactant is 100
The amount can be preferably 6 parts by mass or less, more preferably 3 parts by mass or less, based on parts by mass of the copolymer [A].

Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and other polyoxyethylene alkyl ethers; polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether. And polyoxyethylene aryl ethers; polyethylene glycol dialkyl esters such as polyethylene glycol dilaurate and polyethylene glycol distearate; sorbitan fatty acid esters, fatty acid-modified polyesters, tertiary amine-modified polyurethanes, and the like. KP (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow (manufactured by Kyoeisha Oil and Fat Chemical Co., Ltd.), F-top (manufactured by Shin-Akita Kasei Co., Ltd.), Megafac (manufactured by Dainippon Ink and Chemicals Co., Ltd.), Florard (manufactured by Sumitomo 3M) ), Asahi Guard, and Surflon (made by Asahi Glass). The respective surfactants can be used alone or in combination.

In the composition of the present invention, if necessary, various additives such as a filler, a polymer compound other than the copolymer [A] of the present invention, an adhesion promoter, an antioxidant, an ultraviolet absorber, an anti-aggregation agent. Agents and the like can be added.

Specific examples of these additives include fillers such as glass and alumina, polymers other than copolymer [A] such as polyvinyl alcohol, polyacrylic acid, polyethylene glycol monoalkyl ether and polyfluoroalkyl acrylate. Compounds, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-
Aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3
-Aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, Adhesion promoters such as 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 2,2-thiobis (4-methyl-6-
Antioxidants such as t-butylphenol, 2,6-di-t-butylphenol, and UV absorption of 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, alkoxybenzophenone, etc. Agents and anti-aggregation agents such as sodium polyacrylate.

The photosensitive resin composition for the spacer of the liquid crystal display of the present invention is prepared by mixing the above components [A] to [C] with the solvent [D] and dispersing them by using various mixers and dispersers. It can be prepared.

The photosensitive resin composition layer is formed by applying the obtained composition to a substrate by a coating method such as spin coating, hanging coating, or roll coating, and removing the solvent by prebaking. The pre-baking conditions vary depending on the type and blending ratio of each component, but are usually 1 to 70 ℃ ~ 90 ℃.
Minutes to 15 minutes. After prebaking, the photosensitive resin composition layer is exposed through a predetermined pattern mask, and for example, it is usually developed with a developer at 23 ° C. for 30 seconds to 5 minutes to remove unnecessary portions to form a predetermined pattern. Form. Ultraviolet rays such as g rays, h rays, and i rays are preferable as light rays used at this time. As the ultraviolet irradiation device, a high pressure mercury or metal halide lamp can be used.

As the substrate, for example, non-alkali glass used for liquid crystal displays, soda glass, Pyrex (registered trademark) glass, quartz glass, those having a transparent conductive film adhered to them, and solid-state image pickup devices are used. A photoelectric conversion element substrate, such as a silicon substrate, can be used. These substrates are generally formed with a black matrix that isolates each pixel.

As the developing solution, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, diethylamine, dimethylethanol. Alkaline compounds such as amine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, choline, pyrrole, piperidine and 1,8-diazabicyclo- [5,4,0] -7-undecene at a concentration of 0.001 to 10% by mass, It is preferable to use an alkaline aqueous solution which is dissolved so as to be 0.01 to 1% by mass. When a developer containing such an alkaline aqueous solution is used, the pattern is generally formed by washing with water after development and further drying with compressed air or compressed nitrogen. Then, this pattern, a hot plate, a heating device such as an oven, a predetermined temperature, for example, 150 ℃ ~ 250 ℃, for a predetermined time,
For example, the desired spacer can be obtained by performing heat treatment (post-baking) on a hot plate for 5 to 60 minutes and in an oven for 30 to 90 minutes.

[0040]

Examples (Synthesis Example of Copolymer [A]) Synthesis Example a 1000 ml 4-neck flask equipped with a nitrogen gas inlet, a stirrer, a heater, a cooling tube and a thermometer under a nitrogen gas atmosphere. In addition, 45 g of methacrylic acid monomer (MAA), 37.5 g of glycidyl methacrylate monomer (GMA), 37.5 g of t-butyl methacrylate monomer (TBMA), styrene monomer (ST) 26
g and diethylene glycol dimethyl ether (Diglym
e) 320g was fed. The feed system of each monomer was batch addition. With the contents of this four-necked flask being stirred, raise the temperature of the oil bath to 86 ° C, and then 2,2'-azobis-2-methylbutyronitrile (AMB
4 g of N) was dissolved in a solution of 30 g of diethylene glycol dimethyl ether (Diglyme), and 5 equal parts of the solution was added every hour to a 4-necked flask. The temperature of the solution
The temperature was raised to 70 ° C., this temperature was maintained for 6 hours, and after completion of the polymerization, the polymer was taken out from the 4-necked flask. That is, a resin solution a was thus obtained.

The solid content of the resin solution a is 30% by mass.
Met. The molecular weight distribution of the generated resin solution a is
Measured by C. The results and the raw material composition are shown in Table 1.

Synthetic Examples b and c In Synthetic Example b, the feed amount of the polymerization initiator was changed to prepare Synthetic Example c.
Then, a resin solution b or c was obtained by the same operation method as in Synthesis Example a except that the kind of the polymerization initiator was changed, and its molecular weight distribution was evaluated. Table 1 shows the production conditions and the results of the molecular weight distribution of the resin solution.

Synthesis Example d A resin solution d was obtained in the same manner as in Synthesis Example a, except that the feeding system of each monomer was a continuous addition system and the kind of the olefinically unsaturated monomer (a3) was changed. The molecular weight distribution was evaluated. Table 1 shows the production conditions and the results of the molecular weight distribution of the resin solution.

Synthesis Example e A resin solution e was obtained in the same manner as in Synthesis Example d except that the reaction temperature was lowered to 55 ° C. and the kind of the olefinically unsaturated monomer (a3) was changed. evaluated. Table 1 shows the production conditions and the results of the molecular weight distribution of the resin solution.

Synthesis Example f The reaction temperature was 60 ° C. by changing the feed amount and kind of the polymerization initiator.
And the polymerization time was shortened to 5.5 hours, a resin solution f was obtained by the same operation method as in Synthesis Example a, and its molecular weight distribution was evaluated. Table 1 shows the production conditions and the results of the molecular weight distribution of the resin solution.

Synthesis Example g The feed amount of the polymerization initiator was changed, and the feed method was batch addition. The reaction temperature was initially 65 ° C, and was linearly increased to the final temperature of 80 ° C. Furthermore, the polymerization time was shortened to 5.5 hours. Other than these, a resin solution g was obtained by the same operation method as in Synthesis Example a, and its molecular weight distribution was evaluated. Table 1 shows the production conditions and the results of the molecular weight distribution of the resin solution.

Synthesis Example h A resin solution h was obtained by the same operation method as in Synthesis Example a except that the feed amount and type of the polymerization initiator were changed and the polymerization time was changed to 5 hours, and the molecular weight distribution was evaluated. . The polymerization initiator was prepared by dissolving 1 g of AMBN in a solution of 15 g of diethylene glycol dimethyl ether and adding it all at once at the beginning of the polymerization. At 2 hours after the polymerization, the polymerization initiator 2,2'-azobis-
1 g of (2,4-dimethylvaleronitrile) (ADVN) was dissolved in 15 g of diethylene glycol dimethyl ether solution and added all at once. Table 1 shows the production conditions and the results of the molecular weight distribution of the resin solution.

Synthetic Examples i and j Resin solutions i and j were obtained by the same operation method as in Synthetic Example a except that the ratios of the monomers (a1) to (a3) were changed, and their molecular weight distributions were evaluated. Table 1 shows the production conditions and the results of the molecular weight distribution of the resin solution. Synthesis Examples k, l, m Resin solutions k, l, m were obtained by the same operation method as in Synthesis Example d except that the ratios of the monomers a1 to a3 were changed, and the molecular weight distribution thereof was evaluated. Table 1 shows the results of the test formulation and the molecular weight distribution of the resin solution.

The molecular weight distribution of the copolymer [A] was measured by the following method. <Measurement of Molecular Weight Distribution> The measurement was carried out under the following conditions using a gel permeation chromatography (GPC) device manufactured by Waters.

Column: KD-806M Detector: Water RI-2410 Mobile phase: THF (flow rate 1.0 cc / min) Standard molecular weight polystyrene is used as a measurement standard.

The molecular weight of the copolymer [A] of the present invention is 80.
The proportion (mass%) of the polymer in the range of 0 to 7,000 and the polymer having a molecular weight of 70,000 or more was measured by GPC. Regarding the molecular weight distribution, in the GPC measurement chart obtained under the above conditions, the integral total area of the molecular weight of 800 to 2,000,000 shall be 100%, and the ratio of the molecular weight of 800 to 7,000 and the integral area of the molecular weight of 70,000 or more shall be measured. Obtained by.

[0052]

[Table 1]

The abbreviations in Table 1 are as follows. MAA: Methacrylic acid GMA: Glycidyl methacrylate TBMA: t-butyl methacrylate DCPMA: dicyclopentanyl methacrylate ST: Styrene AMBN: 2,2'-azobis-2-methylbutyronitrile ADVN: 2,2'-azobis (2,4-dimethylvaleronitrile) Diglyme: Diethylene glycol dimethyl ether.

Examples 1 to 5 and Comparative Examples 1 to 8 (1) Preparation of Photosensitive Resin Composition Using the resin solution [A] (that is, the resin solutions a to m) obtained in the above-mentioned synthesis example, The component [B] and the component [C] shown in Table 2 were mixed and dissolved in the solvent [D] to prepare a solution of the photosensitive resin composition. The content of unreacted unsaturated carboxylic acid monomer (methacrylic acid monomer) in the photosensitive resin composition was analyzed by gas chromatography (GC). The obtained results are shown in Table 2.

The content of unreacted methacrylic acid monomer was measured by the following method.

<Measurement of Content of Unreacted Methacrylic Acid Monomer> The photosensitive resin composition was dissolved in tetrahydrofuran, and the solution was analyzed by gas chromatography (series number-5890A) manufactured by Hewlett-Packard Company.
The unit of the measured numerical value is ppm (based on mass).

[0057]

[Table 2]

In Table 2, the resin solution of the copolymer [A] all had a solid content concentration of 30% by mass. Therefore, 4.2 g of the resin solution of the copolymer [A] contains 1.26 g of solid content.

The abbreviations in Table 2 are as follows. DPHA: dipentaerythritol hexaacrylate C-1: 2-benzyl-2-N, N-dimethylamino-1- (4-morpholinophenyl) -1-butanone C-2: 4,4'-bis (diethylamino) benzophenone C-3: 2- (2-chlorophenyl) -4,5-diphenylimidazole dimer Diglyme: diethylene glycol dimethyl ether.

(2) Evaluation Various photosensitive resin compositions shown in Table 2 were mixed with a vibration stirrer, and then a 2 μm coating film was applied on a glass substrate by spin coating, and prebaking was performed at 85 ° C. for 5 minutes. did.
Then, ultraviolet rays (exposure machine Canon PLA-501F) 300 mJ / cm were applied to this photosensitive resin composition layer through a predetermined pattern mask.
After irradiating it with ² and immersing it in a developing solution at 23 ° C. for 2 minutes, it was rinsed with pure water. By these operations, unnecessary portions were removed, and post-baking was performed at 200 ° C. for 40 minutes to obtain a spacer film on the glass substrate.

The above-mentioned spacer film was evaluated for its temporal stability, developability, undercut, surface flatness, heat resistance and chemical resistance by the following methods.

Evaluation method 1. The aging-stable photosensitive resin composition was allowed to stand for one week, and the change in its viscosity was observed and evaluated according to the following criteria. : No change in viscosity. X: There is a change in viscosity and gelation occurs.

2. The completeness of patterning on the developable glass substrate was observed and evaluated according to the following criteria. : The line width of the pattern is perfect. Δ: The line width of the pattern is incomplete, and there are few wrinkles. X: The line width of the pattern is incomplete, and there are many wrinkles.

3. The edge of the patterning on the glass substrate was observed with an undercut scanning electron microscope (SEM), and evaluated according to the following criteria. ○: No undercut. Δ: There is undercut.

4. Surface flatness The surface condition was scanned with a film thickness measuring device (α-step 500) manufactured by Tencor Co., and based on the change of the surface flatness, the following criteria were evaluated. ◯: Change in surface flatness is less than 20Å. Δ: The change in surface flatness is 20 Å or more and less than 50 Å. X: Change in surface flatness is 50 Å or more.

5. Heat resistance The thickness of the spacer on the above glass substrate is measured by a film thickness measuring device (α-step 500) of Tencor Co., and after leaving it at 250 ° C. for 60 minutes, the film thickness is further measured. The following criteria were evaluated based on the change in film thickness. : The change in film thickness is less than 1%. Δ: The change in film thickness is 1% or more and less than 3%. X: The change in film thickness is 3% or more.

6. Solvent resistance The thickness of the above spacer on the glass substrate was measured with a film thickness measuring device (α-step 500) manufactured by Tencor, and subsequently, N-methyl 2-pyrrolidone (NM) was measured at room temperature (23 ° C ± 2 ° C).
After being immersed in P) for 30 minutes, it was further dried at 120 ° C. for 30 minutes to measure the film thickness, and based on the change in the film thickness, the following criteria were evaluated. : The change in film thickness is less than 1%. Δ: The change in film thickness is 1% or more and less than 3%. X: The change in film thickness is 3% or more.

[0068]

[Table 3]

[0069]

EFFECTS OF THE INVENTION According to the present invention, it has good stability over time and is excellent in surface flatness after development, heat resistance and solvent resistance, and has a small undercut and an alkaline developer. A photosensitive resin composition for a spacer of a liquid crystal display, which can be used for development, can be provided.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H025 AA03 AA06 AA10 AA11 AA18                       AB14 AB17 AC01 AD01 BC13                       BC42 BC74 BC85 BC92 BC93                       BD23 BD43 BD44 BD47 CA00                       FA17                 2H089 LA01 MA04X MA16 NA05                       NA14 PA06 PA07 PA09 QA02                       QA16 TA04

Claims (4)

[Claims] 1. [A]: (a1) 5% by mass to 50% by mass of a structural unit derived from an unsaturated carboxylic acid monomer, (a)
2) 10% by mass to 70% by mass of a structural unit derived from an epoxy group-containing unsaturated monomer, (a3) the above (a1) and (a)
A copolymer consisting of 0% by mass to 70% by mass of a structural unit derived from an olefinically unsaturated monomer other than 2),
[B]: a polymerizable compound having an ethylenically unsaturated bond,
[C]: a photopolymerization initiator, and [D]: a solvent are contained, and the molecular weight distribution of the copolymer [A] has a molecular weight of 800 to 2,000 measured by gel permeation chromatography.
When the integrated total area of the polymer in the range of 0,000 is 100% by mass, the polymer in the range of molecular weight of 800 to 7,000 is 10% by mass to 23% by mass of the integrated total area, and the polymer of the molecular weight of 70,000 or more is the integrated value. A photosensitive resin composition for a spacer of a liquid crystal display, which occupies 5% by mass or less of the total area. 2. The photosensitive resin composition according to claim 1, wherein the content of the unreacted unsaturated carboxylic acid monomer is 8,000 ppm or less on a mass basis. 3. The photosensitive resin composition according to claim 1, wherein the content of the unreacted unsaturated carboxylic acid monomer is 6,000 ppm or less on a mass basis. 4. The photosensitivity according to claim 1, wherein the content of the structural unit (a3) in the copolymer [A] is 10% by mass to 60% by mass. Resin composition.