JP2006232893A - Curable resin composition for column spacer, column spacer, and liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable resin composition which can give a column spacer capable of effectively reducing color unevenness due to gravitational defect, to provide a column spacer using the curable resin composition, and to provide a liquid crystal display element. <P>SOLUTION: The curable resin composition for the column spacer is one comprising an alkali-soluble (meth)acrylic copolymer prepared by copolymerizing an unsaturated carboxylic acid and/or an unsaturated carboxylic acid anhydride with other unsaturated compounds, an ethylenically unsaturated polymerizable compound, a polyfunctional epoxy compound, and a photoreaction initiator, wherein a cured product of the composition has an elastic modulus of 0.2 to 1.0 GPa after 15% compression at 25°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a column spacer curable resin composition capable of producing a column spacer capable of effectively suppressing the occurrence of color unevenness due to poor gravity, a column spacer formed using the column spacer curable resin composition, and The present invention relates to a liquid crystal display element.

In general, a liquid crystal display element includes a spacer for maintaining a constant gap between two glass substrates, and includes a transparent electrode, a polarizing plate, an alignment layer for aligning a liquid crystal substance, and the like. At present, fine particle spacers having a particle diameter of about several μm are mainly used as spacers. However, in the conventional method for manufacturing a liquid crystal display element, since the fine particle spacers are randomly distributed on the glass substrate, the fine particle spacers may be disposed in the pixel portion. If there is a fine particle spacer in the pixel portion, there is a problem that image quality may be deteriorated, for example, light leaks from disturbance of liquid crystal alignment around the spacer and image contrast is lowered. On the other hand, various arrangement methods of the fine particle spacer in which the fine particle spacer is not arranged in the pixel portion have been studied. However, all of them are complicated and impractical.

In recent years, one drop fill technology (ODF method) has been proposed in order to increase the productivity of liquid crystal display elements. In this method, a predetermined amount of liquid crystal is dropped on the liquid crystal sealing surface of a glass substrate, and the other liquid crystal panel substrate is held in a state where a predetermined cell gap can be maintained under vacuum, and bonded together to display a liquid crystal display. This is a method of manufacturing an element. According to this method, even when the liquid crystal display element has a larger area than the conventional method and the cell gap is narrowed, it is easy to enclose the liquid crystal. It will be mainstream.
However, when fine particle spacers are used in the ODF method, the fine particle spacers scattered when the liquid crystal is dropped or bonded to the counter substrate are flowed along with the flow of the liquid crystal, resulting in a non-uniform distribution of the fine particle spacers on the substrate. Occurs. If the distribution of the fine particle spacers is non-uniform, there is a problem that the cell gap of the liquid crystal cell varies and color unevenness occurs in the liquid crystal display.

On the other hand, instead of the conventional fine particle spacer, a column spacer in which a convex pattern for holding the cell gap uniformly on a liquid crystal substrate by a photolithographic technique is proposed and put into practical use. (For example, Patent Document 1, Patent Document 2, etc.). If the column spacer is used, the problem that the spacer is arranged in the pixel portion and the problem that the spacer unevenness occurs in the ODF method can be solved.

However, in a large liquid crystal display element manufactured by the ODF method using a column spacer, the liquid crystal in the liquid crystal cell flows downward during use of the display device, resulting in color unevenness in the lower part of the display panel. ”Has been a big problem.
JP-A-10-319592 JP 2001-91954 A

In view of the present situation, the present invention uses a curable resin composition for a column spacer that can effectively produce a column spacer that can effectively suppress the occurrence of color unevenness due to poor gravity, and the curable resin composition for a column spacer. It is an object to provide a column spacer and a liquid crystal display element.

The present invention relates to an alkali-soluble (meth) acrylic copolymer obtained by copolymerizing an unsaturated carboxylic acid and / or an unsaturated carboxylic acid anhydride and another unsaturated compound, and a polymerizable compound having an ethylenically unsaturated bond. A curable resin composition for a column spacer containing a compound, a polyfunctional epoxy compound, and a photoreaction initiator, and the cured product after curing has an elastic modulus of 0.2 to 25% at 25 ° C. It is a curable resin composition for column spacers of 1.0 GPa.
The present invention is described in detail below.

Gravity failure occurs when the liquid crystal in the liquid crystal cell expands due to the heat generated from the backlight and widens the cell gap. At that time, the substrate on which the column spacer is not directly bonded is lifted away from the column spacer. It is considered that the volume of liquid crystal that is no longer held by the column spacer flows due to gravity flowing downward. As a result of intensive studies, the present inventors have used a column spacer that is excellent in elasticity and excellent in a recovery rate from compression deformation, and a liquid crystal display element designed so that the height of the column spacer is slightly higher than the cell gap Then, it discovered that the gravity defect phenomenon did not occur. In the liquid crystal display element thus designed, the column spacers between the substrates are always in a state of being elastically recovered from the compressed state, so that the liquid crystal in the liquid crystal cell expands and the cell gap is increased. This is considered to be because the substrate does not float away from the column spacer even when trying to spread. As a result of further investigation, if a curable resin composition having a specific elastic property as a cured product when cured by light irradiation and heating is used, a column spacer satisfying such properties can be easily produced. The headline and the present invention were completed.

The curable resin composition for column spacers of the present invention contains an alkali-soluble (meth) acrylic copolymer, a polymerizable compound having an ethylenically unsaturated bond, a polyfunctional epoxy compound, and a photoreaction initiator.

The alkali-soluble (meth) acrylic copolymer is a copolymer obtained by copolymerizing an unsaturated carboxylic acid and / or an unsaturated carboxylic acid anhydride and another unsaturated compound.
The unsaturated carboxylic acid and / or unsaturated carboxylic acid anhydride is not particularly limited, and examples thereof include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; maleic acid, fumaric acid, citraconic acid, mesaconic acid, and itacone. Dicarboxylic acids such as acids; methacrylic acid derivatives having a carboxyl group and an ester bond such as 2-succinyloxyethyl methacrylate, 2-maleoyloxyethyl methacrylate, 2-hexahydrophthaloyloxyethyl methacrylate, and anhydrides thereof Is mentioned. These may be used alone or in combination of two or more. Of these, acrylic acid, methacrylic acid, and 2-hexahydrophthaloyloxyethyl methacrylate are preferable.

The amount of the unsaturated carboxylic acid and / or unsaturated carboxylic anhydride in the alkali-soluble (meth) acrylic copolymer is not particularly limited, but the preferred lower limit is 10% by weight and the preferred upper limit is 40% by weight. . If it is less than 10% by weight, the alkali-soluble (meth) acrylic copolymer becomes difficult to dissolve in an alkali developer, and a film residue may be generated after development, and sufficient resolution may not be obtained. If it exceeds 40% by weight, the solubility of the alkali-soluble (meth) acrylic copolymer in the alkali developer becomes too high, and the dissolution of the exposed area, that is, the reduction of the film may be increased. A more preferred lower limit is 20% by weight, and a more preferred upper limit is 35% by weight.

The other unsaturated compound mainly controls the mechanical strength, polymerization rate and the like of the alkali-soluble (meth) acrylic copolymer, and “other” refers to the above-mentioned “unsaturated carboxylic acid and It means an unsaturated compound other than “/ or unsaturated carboxylic acid anhydride”.

The other unsaturated compound is not particularly limited. For example, methyl methacrylate, ethyl methacrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate (Meth) acrylic acid alkyl esters such as phenyl (meth) acrylate, benzyl (meth) acrylate and the like (meth) acrylic acid aryl esters; dimethyl maleate, diethyl maleate, dimethyl fumarate, diethyl fumarate, itacon Dicarboxylic acid diesters (or unsaturated carboxylic acid diesters) such as dimethyl acid and diethyl itaconate; aromatics such as styrene, α-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene and p-methoxystyrene Nyls; Conjugated diolefins such as 1,3-butadiene, isoprene and 1,4-dimethylbutadiene; Nitrile group-containing polymerizable compounds such as acrylonitrile and methacrylonitrile; Chlorine-containing polymerizable compounds such as vinyl chloride and vinylidene chloride Amide bond-containing polymerizable compounds such as acrylamide and methacrylamide; fatty acid vinyls such as vinyl acetate, cyclohexyl (meth) acrylate, 2-methylcyclohexyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, isobornyl ( And (meth) acrylate and dicyclopentanyl (meth) acrylate. These may be used alone or in combination of two.

The amount of the other unsaturated compound in the alkali-soluble (meth) acrylic copolymer is not particularly limited, but a preferable lower limit is 60% by weight and a preferable upper limit is 90% by weight. If it is less than 60% by weight, the mechanical strength, polymerization rate, etc. of the alkali-soluble (meth) acrylic copolymer may not be sufficiently controlled. It may be difficult to dissolve in an alkali developer of a (meth) acrylic copolymer, and a film residue may be generated after development, and sufficient resolution may not be obtained.

The polymerization solvent used for synthesizing the alkali-soluble (meth) acrylic copolymer is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, ethylene glycol, diethylene glycol, and propylene glycol; cyclics such as tetrahydrofuran and dioxane. Ethers: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene Glycol Alkyl ethers of polyhydric alcohols such as noethyl ether; alkyl ether acetates of polyhydric alcohols such as ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate and propylene glycol methyl ether acetate; aromatic hydrocarbons such as toluene and xylene Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol; ethyl acetate, butyl acetate, ethyl 2-hydroxypropionate, 2- Methyl hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-3-methyl Methyl Tan acid, methyl 3-methoxypropionate, 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl esters such as 3-ethoxy-methylpropionic acid. Of these, cyclic ethers, polyhydric alcohol alkyl ethers, polyhydric alcohol alkyl ether acetates, ketones, and esters are preferred.

In addition, the radical polymerization initiator used when copolymerizing the unsaturated carboxylic acid and / or unsaturated carboxylic acid anhydride and another unsaturated compound is not particularly limited, and examples thereof include conventionally known ones. For example, 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobis- (4-methoxy-2, -dimethylvalero) Azo compounds such as nitrile); organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butylperoxypivalate, 1,1′-bis- (t-butylperoxy) cyclohexane, and hydrogen peroxide. Moreover, when using a peroxide for a radical polymerization initiator, it is good also as a redox type initiator combining a reducing agent. Examples of the reducing agent in this case include ferrous sulfate, sodium hydrogen sulfite, cuprous naphthenate, dimethylaniline, and the like.

Although it does not specifically limit as a polymeric compound which has the said ethylenically unsaturated bond, For example, a polyfunctional (meth) acrylate compound is suitable.

Examples of the bifunctional monomer of the polyfunctional (meth) acrylate compound include neopentyl glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, and 1,6-hexanediol diene. (Meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, tritetramethylene glycol di (meth) acrylate and the like. .

Examples of the trifunctional monomer of the polyfunctional (meth) acrylate compound include pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane (meth) acrylate di (meth) acrylate, and dipenta Examples include erythritol tri (meth) acrylate.

Examples of the tetrafunctional or higher monomer of the polyfunctional (meth) acrylate compound include ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and dipentaerythritol. Examples include penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate.

Moreover, a polyfunctional epoxy acrylate compound and a urethane acrylate compound are also suitable as the polymerizable compound having an ethylenically unsaturated bond.

The polymerizable compound having an ethylenically unsaturated bond is preferably a caprolactone-modified (meth) acrylate compound. By using the caprolactone-modified (meth) acrylate compound, the column spacer using the curable resin composition for a column spacer of the present invention has high recoverability from compression deformation and is flexible and has a low elastic modulus. Both.
The caprolactone modification means that a caprolactone ring-opening polymer or a ring-opening polymer is introduced between the alcohol-derived site of the (meth) acrylate compound and the (meth) acryloyloxy group. The caprolactone-modified product means a compound that has been subjected to such caprolactone modification.

The specific method for modifying the (meth) acrylate compound with caprolactone is not particularly limited. For example, the caprolactone-modified alcohol is synthesized after reacting alcohol with caprolactone at high temperature in the presence of a catalyst to synthesize the caprolactone-modified alcohol. And (meth) acrylic acid after the esterification reaction using a dehydrating solvent in the presence of an acidic catalyst or (meth) acrylic acid and caprolactone are reacted to synthesize caprolactone-modified (meth) acrylic acid, Examples include a method of esterifying with alcohol.

In the curable resin composition for a column spacer of the present invention, the polymerizable compound having an ethylenically unsaturated bond is preferably a caprolactone-modified trifunctional or higher functional (meth) acrylate compound. By containing such a compound, the column spacer formed by curing the curable resin composition for a column spacer of the present invention has high recoverability from compression deformation and is flexible and has a low elastic modulus. Resist sensitivity can be improved.

The degree of modification of the caprolactone-modified trifunctional or higher functional (meth) acrylate compound is defined as trifunctional or higher functional (meth) acrylate compound 1 where n is the number of functional groups of the trifunctional or higher functional (meth) acrylate compound. It is preferable to modify by introducing 0.5 n to 5 nmole of caprolactone with respect to mol. If the amount of caprolactone introduced is less than 0.5 nmol, the flexibility of the resulting column spacer may be insufficient, and if it exceeds 5 nmol, the reactivity decreases during exposure and spacer patterning is difficult. May be. More preferably, it is 1n-3nmol.

The trifunctional or higher functional (meth) acrylate compound modified with caprolactone is not particularly limited. Examples of the trifunctional compound include pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, and trimethylolethane. Caprolactone-modified products such as (meth) acrylate di (meth) acrylate and dipentaerythritol tri (meth) acrylate are preferred.
In addition, examples of the above-mentioned caprolactone-modified trifunctional or higher functional (meth) acrylate compound having a tetrafunctional or higher functionality include pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and dipentaerythritol (meth). Caprolactone-modified products such as tetraacrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate are preferred.
These caprolactone-modified trifunctional or higher functional (meth) acrylate compounds may be used alone or in combination of two or more.

The above-mentioned caprolactone-modified trifunctional or higher functional (meth) acrylate compound may be used after the (meth) acrylate compound is caprolactone-modified by the above-mentioned method, or “KAYARAD DPCA-60” manufactured by Nippon Kayaku Co., Ltd. Commercially available products such as “KAYARAD DPCA-30”, “KAYARAD DPCA-120” (caprolactone-modified dipentaerythritol hexaacrylate), “NK ester AD-TMP-4CL” (caprolactone-modified ditrimethylolpropane tetraacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. You may use goods.

In the curable resin composition for a column spacer of the present invention, the mixing ratio of the alkali-soluble (meth) acrylic copolymer and the polymerizable compound having an ethylenically unsaturated bond is not particularly limited, but the alkali-soluble ( The minimum with the preferable compounding quantity of the said polymeric compound which has the said ethylenically unsaturated bond with respect to 100 weight part of (meth) acryl copolymers is 25 weight part, and a preferable upper limit is 900 weight part. If the amount is less than 25 parts by weight, the pattern of the column spacer may not be formed by photolithography without sufficient photocuring. If the amount exceeds 900 parts by weight, the alkaline developer may be used for producing the column spacer. Insufficient developability may result. A more preferred lower limit is 100 parts by weight, and a more preferred upper limit is 500 parts by weight.

The polyfunctional epoxy compound is not particularly limited, but those having an epoxy equivalent of 250 or less are suitable. When the epoxy equivalent exceeds 250, the developability of the curable resin composition for a column spacer of the present invention may deteriorate, and it may be difficult to obtain a good pattern shape.
In addition, the said epoxy equivalent means the gram number of the epoxy compound containing an epoxy group of 1 gram equivalent. Such a polyfunctional epoxy compound plays the role which improves the recoverability from the compression deformation of the curable resin composition for column spacers of this invention.

Such a polyfunctional epoxy compound is not particularly limited, for example, a condensation product of epichlorohydrin and bisphenol F, bisphenol A, phenol novolak, cresol novolak or other novolak, a cyclic aliphatic epoxy compound, a glycidyl ester epoxy compound, Examples thereof include epoxy compounds obtained by (co) polymerization of glycidylamine-based epoxy compounds and glycidyl methacrylate and having an epoxy equivalent of 250 or less. As a commercial item of the said polyfunctional epoxy compound, for example, Epicoat 801 (bisphenol F type epoxy compound, epoxy equivalent: 205-225) made by Yuka Shell Epoxy Co., Ltd., 802 (bisphenol F type epoxy compound, epoxy equivalent: 190-200) 205), 807 (bisphenol F type epoxy compound, epoxy equivalent: 160 to 175), 815 (bisphenol F type epoxy compound, epoxy equivalent: 181 to 191), 827 (bisphenol A type epoxy compound, epoxy equivalent: 180 to 190) , 828 (bisphenol A type epoxy compound, epoxy equivalent: 184 to 194), 152 (phenol novolac type epoxy resin, epoxy equivalent: 172 to 178 g), 154 (phenol novolac type epoxy resin, epoxy equivalent: 1) 6-180), 180S65 (orthocresol novolac type epoxy resin, epoxy equivalent: 205-220), EP4100 (bisphenol A type epoxy compound, epoxy equivalent: 180-200) manufactured by Asahi Denka Kogyo Co., Ltd., 4340 (bisphenol A type epoxy) Compound, epoxy equivalent: 205-230) and the like. Of these, Epicoats 815 and 828 are preferably used.
These polyfunctional epoxy compounds may be used independently and may use 2 or more types together.

As a compounding quantity of the polyfunctional epoxy compound in the curable resin composition for column spacers of this invention, a preferable minimum is 3 weight part with respect to 100 weight part of said alkali-soluble (meth) acryl copolymers, and a preferable upper limit is 50. Parts by weight. If it is less than 3 parts by weight, the curable resin composition for column spacers of the present invention may not be sufficiently heat-cured. If it exceeds 50 parts by weight, the degree of crosslinking of the resulting cured product will be too high and will be described later. May not meet elastic properties. A more preferred lower limit is 5 parts by weight, and a more preferred upper limit is 40 parts by weight.

The photoinitiator is not particularly limited, and conventionally known photoinitiators such as benzoin, benzophenone, benzyl, thioxanthone, and derivatives thereof can be used. Specifically, for example, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, Michler ketone, (4- (methylphenylthio) phenyl) failmethanone, 2,2-dimethoxy-1,2-diphenylethane-1- ON, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4- (2-hydroxyethoxy) -phenyl) -2-hydroxy-2 -Methyl-1-propan-1-one, 2-methyl-1 (4-methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholino Phenyl) -butanone-1, bis (2,4,6-trimethylbenzoyl) -phenylphospho Oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4-diethylthioxanthone, 2-chloro Examples include thioxanthone. These photoinitiators may be used independently and 2 or more types may be used together.

As a compounding quantity of the said photoinitiator in the curable resin composition for column spacers of this invention, a preferable minimum is 0.01 weight part with respect to 100 weight part of polymeric compounds which have the said ethylenically unsaturated bond, Preferably The upper limit is 50 parts by weight. If it is less than 0.01 part by weight, the curable resin composition for a column spacer of the present invention may not be photocured. If it exceeds 50 parts by weight, the curable resin composition for a column spacer of the present invention is used. When manufacturing column spacers, alkali development may not be possible in photolithography. A more preferred lower limit is 0.05 parts by weight, and a more preferred upper limit is 20 parts by weight.

The curable resin composition for column spacers of the present invention may contain a reaction aid in order to reduce reaction disturbance due to oxygen. By using such a reaction aid and a hydrogen abstraction type photoreaction initiator in combination, the curing rate when irradiated with light can be improved.

The reaction aid is not particularly limited, and examples thereof include amines such as n-butylamine, di-n-butylamine, triethylamine, triethylenetetramine, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate; Phosphines such as -n-butylphosphine; sulfonic acids such as s-benzylisothiuronium-p-toluenesulfinate. These reaction aids may be used alone or in combination of two or more.

The curable resin composition for column spacers of the present invention may further contain a compound having two or more blocked isocyanate groups. The compound having two or more blocked isocyanate groups works as a thermal crosslinking agent, and contains such a compound having two or more blocked isocyanate groups, thereby using the curable resin composition for column spacers of the present invention. Thus, the cross-linking structure of the column spacer can be made stronger, and recovery from compression deformation and chemical resistance can be improved.

The compound having two or more blocked isocyanate groups is not particularly limited. For example, tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate), trimethyl. Examples include those obtained by blocking hexamethylene diisocyanate and polyfunctional isocyanates composed of these oligomers with a blocking agent compound such as active methylene, oxime, lactam, and alcohol. These compounds having two or more blocked isocyanate groups may be used alone or in combination of two or more.

Examples of commercially available compounds having two or more blocked isocyanate groups include Duranate 17B-60PX, Duranate E-402-B80T (manufactured by Asahi Kasei Chemicals Corporation) and the like.

When the curable resin composition for column spacers of the present invention contains a compound having two or more blocked isocyanate groups, the blending amount thereof is 100 parts by weight of the alkali-soluble (meth) acrylic copolymer. The preferred lower limit is 0.01 parts by weight and the preferred upper limit is 50 parts by weight. If it is less than 0.01 part by weight, the curable resin composition for a column spacer of the present invention may not be sufficiently cured by heat, and if it exceeds 50 parts by weight, the degree of crosslinking of the resulting cured product becomes too high. The elastic characteristics described later may not be satisfied. A more preferred lower limit is 0.05 parts by weight, and a more preferred upper limit is 20 parts by weight.

The curable resin composition for column spacers of the present invention may further contain a compound having a polymerizable unsaturated bond and a polyethylene glycol skeleton. The developability can be improved without impairing the high recovery property and flexibility from the compression deformation of the column spacer using the curable resin composition for a column spacer of the present invention.

The compound having a polymerizable unsaturated bond and a polyethylene glycol skeleton is not particularly limited. For example, diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, tetraethylene glycol (meth) acrylate, hexaethylene glycol ( Polyethylene glycol (meth) acrylates such as (meth) acrylate and nonaethylene glycol (meth) acrylate; diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, hexaethylene glycol di ( And polyethylene glycol di (meth) acrylates such as (meth) acrylate and nonaethylene glycol di (meth) acrylate. Trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra as compounds having a polymerizable unsaturated bond having a tri- or higher functional polyethylene glycol skeleton. Polyethylene glycol modified products of polyfunctional (meth) acrylate compounds such as (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate can also be used. . Among these, those having two or more polymerizable unsaturated bonds are preferred because they have a small influence on the compression property derived from the crosslinked structure of the column spacer obtained by curing the curable resin composition for column spacers of the present invention. It is.

When the curable resin composition for a column spacer of the present invention contains a compound having a polymerizable unsaturated bond and a polyethylene glycol skeleton, the blending amount is not particularly limited, but the alkali-soluble polymer compound is 100 weights. The preferred lower limit is 10 parts by weight and the preferred upper limit is 300 parts by weight with respect to parts. If the amount is less than 10 parts by weight, a sufficient effect of improving developability cannot be obtained. If the amount exceeds 300 parts by weight, the adhesion durability against an alkaline developer may be reduced, making it difficult to obtain a pattern. A more preferred lower limit is 50 parts by weight, and a more preferred upper limit is 200 parts by weight.

The curable resin composition for column spacers of the present invention may be diluted with a diluent in order to adjust the viscosity.
The diluent is not particularly limited, and may be selected in consideration of compatibility with the curable resin group for a column spacer of the present invention, coating method, film uniformity during drying, drying efficiency, etc. When coating the column spacer curable resin set of the present invention using a spin coater, slit coater, etc., methyl cellosolve, ethyl cellosolve, ethyl cellosolve acetate, diethylene glycol dimethyl ether, propylene glycol monoethyl ether acetate, An organic solvent such as isopropyl alcohol is preferred. These diluents may be used independently and 2 or more types may be used together.

Moreover, the curable resin composition for column spacers of this invention may contain conventionally well-known additives, such as a silane coupling agent, in order to improve adhesiveness with a board | substrate as needed.

If the curable resin composition for column spacers of the present invention is used, a cured product having excellent elastic properties against compression can be obtained by photocuring (and thermosetting), and if a column spacer using this is used, A liquid crystal display element free from color unevenness due to gravity failure can be manufactured.

In such a curable resin composition for a column spacer of the present invention, the lower limit of the elastic modulus at 15% compression at 25 ° C. of the cured product when cured is 0.2 GPa, and the upper limit is 1.0 GPa. If it is less than 0.2 GPa, the column spacer using the above curable resin composition for column spacers according to the present invention is too soft and it becomes difficult to maintain the cell gap, and if it exceeds 1.0 GPa, it is too hard. When the substrates are bonded, the color filter layer may be plunged or sufficient elastic deformation necessary for recovery may not be obtained. The preferred lower limit is 0.3 GPa, the preferred upper limit is 0.9 GPa, the more preferred lower limit is 0.5 GPa, and the more preferred upper limit is 0.7 GPa.

In the present specification, the cured product means a cured product (column spacer) when the curable resin composition for a column spacer of the present invention is almost completely cured by light irradiation (and heating). As a condition for almost complete curing, for example, it is possible to cure almost completely by irradiating ultraviolet rays of 50 to 300 mJ / cm ² and further applying a heat treatment at a temperature of 200 to 250 ° C. for about 20 minutes.

Further, in this specification, 15% compression means compression so that the deformation rate of the height of the column spacer is 15%. The elastic modulus is measured by the following method.
That is, first, the column spacer formed on the substrate is compressed at a load application speed of 10 mN / s, and is compressed to a height corresponding to 85% of the initial height H ₀ . Here, the column spacer height when a load of 1 mN is applied is H ₁ , the column spacer height corresponding to 85% of H ₀ is H ₂ , and the load when F ₂ reaches H ₂ is F. Next, the load F is held for 5 seconds, and after being deformed at a constant load, the load is removed at a load application speed of 10 mN / sec, and the elastic modulus E is calculated by the following equation (1).

    Elastic modulus E = F / (D × S) (1)

In Formula (1), F represents the load (N), D represents the column spacer height deformation ratio = (H ₀ −H ₂ ) / H ₀ , and S represents the cross-sectional area of the column spacer (m ² ).

Moreover, the liquid crystal display element manufactured using the column spacer which consists of curable resin composition for column spacers of this invention is about 60 degreeC in a liquid crystal cell with the heat | fever which generate | occur | produces from a backlight on normal use conditions. When the temperature is applied, the liquid crystal expands and a force is generated to push the cell gap. At this time, the column spacer made of the curable resin composition for column spacers of the present invention has a preferable lower limit of the elastic modulus of 0.1% when compressed at 60 ° C. so that the liquid crystal display element does not have poor gravity. 13 GPa, and a preferable upper limit is 0.65 GPa. If it is less than 0.13 GPa, it may be too soft to hold the cell gap, and if it exceeds 0.65 GPa, it may be too hard to obtain sufficient elastic deformation necessary for recovery. Since the elastic modulus at 15% compression at 60 ° C. is within this range, the temperature inside the liquid crystal cell becomes about 60 ° C. due to heat generated from the backlight, and the liquid crystal expands and tries to widen the cell gap. Even when a force is generated, the substrate is not lifted away from the column spacer, and the occurrence of a gravity defect can be prevented. A more preferable lower limit is 0.2 GPa, and a more preferable upper limit is 0.6 GPa.

In addition, in a liquid crystal display device manufactured using a column spacer comprising the curable resin composition for a column spacer of the present invention, stress may be repeatedly applied by daily use. However, it is preferable that the compression characteristics (elastic coefficient) of the column spacer hardly change. Specifically, the column spacer using the curable resin composition for a column spacer of the present invention is repeatedly subjected to a compression test of compressing 15% at 25 ° C., with respect to the elastic modulus during the first compression, It is preferable that the elastic modulus change rate during the fifth compression is 5% or less. If it exceeds 5%, when a stress is repeatedly applied to the column spacer due to daily use of the liquid crystal display element, the elastic coefficient thereof may change greatly, and color unevenness may occur due to poor gravity. More preferably, it is 4% or less.

Note that the rate of change of the elastic modulus is measured by the following method.
That is, when the compression test of 15% compression at 25 ° C. was repeated, the elastic modulus at the first compression was E ₁ and the elastic modulus at the fifth compression was E ₅ ,
2).

Rate of change C = {(E ₅ −E ₁ ) / E ₁ } × 100 (2)

Further, the cured product of the curable resin composition for column spacers of the present invention, it is preferable the lower limit of the recovery rate of the elastic coefficient E ₅ at the fifth compression is 70%. If it is less than 70%, the column spacer between the substrates of the obtained liquid crystal display element is too weak to recover, and a sufficient gravity defect suppressing effect may not be obtained. A more preferred lower limit is 80%. The upper limit of the recovery rate is not particularly limited.
The recovery rate can be measured by the following method.

That is, in the compression test of the fifth, to compress the column spacer formed on the substrate is compressed at a load application rate of 10 mN / s, until the height corresponding to 85% of the initial height H _0. Here, the column spacer height when a load of 10 mN is applied is H ₁ , and the column spacer height corresponding to 85% of H ₀ is H ₂ , and the load when the load reaches H ₂ is F. Next, the load F is held for 5 seconds, and after deformation at a constant load, the load is removed at a load application speed of 10 mN / sec, and the recovery deformation of the column spacer height due to elastic recovery is measured. The column spacer height at the time when the compression deformation during this period becomes maximum is H _3, and the column spacer height when a load of 10 mN is applied in the process of recovering the deformation of the column spacer is H ₄ . The recovery rate R can be calculated by the following formula (3).

Recovery rate R = (H ₄ −H ₃ ) / (H ₁ −H ₃ ) × 100 (3)

Further, the column spacer is thermocompression bonded at a high temperature of about 120 ° C. in order to cure the sealant when the liquid crystal is sealed between two glass substrates during the production of a normal liquid crystal display element. Therefore, in order to reliably prevent a gravity defect or the like in the liquid crystal display element to be manufactured, it is important to use a column spacer that has a small change in elastic characteristics even by thermocompression bonding at such a high temperature. Therefore, the curable resin composition for a column spacer of the present invention has an initial compression elastic modulus E ₀ when the cured product is compressed 15% at 25 ° C., and 15% compression at 25 ° C. after 15% compression at 120 ° C. it is preferred that the compression elastic modulus E ₁ upon satisfies the following formula (3).
Here, “initial” means a state where there is no thermocompression history of about 120 ° C.

{(E ₁ −E ₀ ) / E ₀ } × 100 ≦ 10 (4)

When the cured product of the curable resin composition for a column spacer of the present invention does not satisfy the above formula (4), that is, when the value of the left side of the above formula (4) exceeds 10, the seal at the time of manufacturing the liquid crystal display element Due to heating by thermocompression bonding for curing the agent, the elastic properties of the obtained column spacers may change greatly, and gravity defects may occur in the liquid crystal display elements to be manufactured.

Moreover, it is preferable that the linear expansion coefficient of the hardened | cured material of the curable resin composition for column spacers of this invention exists in the predetermined range close | similar to the linear expansion coefficient of the liquid crystal used for a liquid crystal display element. The phenomenon of “gravity failure” of the liquid crystal display element occurs because the column spacer cannot expand following the expansion when the liquid crystal is heated, and as a result, the substrate floats from the column spacer. It is considered a thing. On the other hand, by setting the linear expansion coefficient of the column spacer within a predetermined range close to the linear expansion coefficient of the liquid crystal, when the liquid crystal is heated and expanded by the heat generated from the backlight, the column spacer is Since the expansion follows the expansion, it is considered that the substrate does not lift from the column spacer, and the color unevenness due to “gravity failure” does not occur.

That is, since the liquid crystal conventionally used for the liquid crystal display element has a linear expansion coefficient of about 7 × 10 ⁻⁴ / ° C. in the temperature range of 25 to 100 ° C., the curable resin composition for column spacers of the present invention. The preferable lower limit of the linear expansion coefficient in a temperature range of 25 to 100 ° C. is 1 × 10 ⁻⁴ / ° C., and the preferable upper limit is 5 × 10 ⁻⁴ / ° C. When the temperature is less than 1 × 10 ⁻⁴ / ° C., there is a difference between the linear expansion coefficient of the column spacer using the curable resin composition for a column spacer of the present invention and the linear expansion coefficient of the liquid crystal used in the liquid crystal display element. As the column spacer becomes larger, the followability to expansion or contraction due to heating or cooling of the liquid crystal becomes insufficient, and color unevenness due to poor gravity may occur. ^Exceeding 5 × 10 ⁻⁴ / ° C. is unrealistic as a column spacer using the curable resin composition for column spacers of the present invention. A more preferable lower limit is 2 × 10 ⁻⁴ / ° C., and a more preferable upper limit is 4 × 10 ⁻⁴ / ° C.

The method for producing the curable resin composition for a column spacer of the present invention is not particularly limited. For example, the alkali-soluble (meth) acrylic copolymer, a polymerizable compound having an ethylenically unsaturated bond, a polyfunctional epoxy compound And a method of mixing a photoinitiator and a compound having two or more blocked isocyanate groups, a diluent and the like, which are added as necessary, by a conventionally known method.

The method for producing the column spacer using the curable resin composition for a column spacer of the present invention is not particularly limited. For example, the curable resin composition for a column spacer of the present invention is coated on a glass substrate and applied. A coating film forming step for forming a film, and irradiation of actinic rays through a mask having a predetermined pattern formed on the obtained coating film, the polymerizable compound having the ethylenically unsaturated bond, and a photoreaction initiator, A method comprising a photocuring step of reacting photocuring to obtain a photocured product and a developing step of forming a predetermined pattern by alkali development of the photocured product after the photocuring step is preferable.

In the method for producing a column spacer, first, a coating film forming step is performed in which the curable resin composition for a column spacer of the present invention is applied onto a glass substrate to form a coating film. The coating method is not particularly limited, and for example, conventionally known coating methods such as spin coating, slit coating, spray coating, dip coating, and bar coating can be used. After coating, a coating film is formed by drying for a certain period of time.

Next, the obtained coating film is irradiated with an actinic ray such as ultraviolet rays through a mask in which a predetermined pattern is formed, and photoreaction starts with the polymerizable compound having the ethylenically unsaturated bond in the light irradiation part. A photocuring step is carried out to obtain a photocured product by reacting with the agent.
The irradiation amount of the active light is preferably at least 50 mJ / cm ^{2 in} the case of ultraviolet rays. If it is less than 50 mJ / cm ² , the photocuring is insufficient, and when exposed to an alkali treatment in the development step, the exposed portion may be dissolved and a pattern may not be formed.

Subsequently, the photocured product after the photocuring step is subjected to an alkali development to form a predetermined pattern. The developing method is not particularly limited, and a conventionally known method such as washing with an pure solution after dissolving an unexposed portion with an alkali solution such as calcium hydroxide can be used.

When the curable resin composition for a column spacer of the present invention contains a compound having two or more blocked isocyanate groups, the alkali-soluble composition is further heated by heating the patterned photocured product after the development step. The (meth) acrylic copolymer reacts with a compound having two or more blocked isocyanate groups.
The heating condition may be appropriately determined in consideration of the size and thickness of the pattern, but is preferably at least 200 ° C. for 20 minutes or more.
A column spacer using the curable resin composition for a column spacer of the present invention is also one aspect of the present invention.

The column spacer of the present invention is designed so that its height is slightly higher than the cell gap, and manufactured by a conventionally known method such as the ODF method, thereby effectively suppressing the occurrence of color unevenness due to gravity failure. The liquid crystal display element which can be obtained can be obtained.
The curable resin composition for column spacers of the present invention or a liquid crystal display device using the column spacers of the present invention is also one aspect of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the column spacer which uses the curable resin composition for column spacers which can manufacture the column spacer which can suppress effectively generation | occurrence | production of the color nonuniformity by a gravity defect, and this curable resin composition for column spacers Spacers and liquid crystal display elements can be provided.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
(1) Synthesis of alkali-soluble (meth) acrylic copolymer A 3 L separable flask was charged with 60 parts by weight of diethylene glycol dimethyl ether as a solvent, heated to 90 ° C. in a nitrogen atmosphere, and then 10 parts by weight of methyl methacrylate. A mixture of 8 parts by weight of methacrylic acid, 22 parts by weight of n-butyl methacrylate, 0.4 parts by weight of azobisvaleronitrile, and 0.1 parts by weight of n-dodecyl mercaptan was dropwise added over 3 hours. Then, after hold | maintaining at 90 degreeC for 30 minutes, it heated up at 105 degreeC and superposition | polymerization was continued for 3 hours and the polymer solution was obtained.

(2) Preparation of curable resin composition for column spacer 100 parts by weight of alkali-soluble (meth) acrylic copolymer solution prepared, caprolactone-modified dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., “KAYARAD DPCA-120”) 80 parts by weight, 15 parts by weight of a polyfunctional epoxy compound (manufactured by Yuka Shell Epoxy, “Epicoat 815”) and 15 parts by weight of a photoinitiator (manufactured by Ciba Specialty Chemicals, “Irgacure 369”) are mixed. Further, 120 parts by weight of diethylene glycol dimethyl ether as a diluent was added and mixed to prepare a curable resin composition for column spacers.

(3) Manufacture of column spacer On the glass substrate on which the transparent conductive film is formed, the obtained curable resin composition for column spacer is applied by spin coating, and dried at 80 ° C. for 3 minutes to form a coating film. did. The obtained coating film was irradiated with ultraviolet rays with an intensity of 200 mJ / cm ² through a 30 μm square dot pattern mask. After developing with 0.04% KOH solution for 60 seconds, it was washed with pure water for 30 seconds to form a column spacer pattern. Subsequently, baking was performed at 220 ° C. for 1 hour. Thereby, a column spacer having a cross-sectional shape of 30 μm × 30 μm (cross-sectional area 900 μm ² ) and a height of 5.0 μm was obtained.

(4) Manufacture of liquid crystal display element The sealing agent (made by Sekisui Chemical Co., Ltd.) was apply | coated with the dispenser so that the rectangular frame might be drawn on the glass substrate in which the column spacer obtained was formed. Subsequently, fine droplets of liquid crystal (manufactured by Chisso Co., Ltd., JC-5004LA) are dropped on the entire surface of the glass substrate, and the other glass substrate is immediately overlaid, and a high-pressure mercury lamp is used as a seal portion to apply ultraviolet light at 50 mW / Irradiated with cm ² for 60 seconds. Thereafter, liquid crystal annealing was performed at 120 ° C. for 1 hour for thermosetting to produce a liquid crystal display element.

(Example 2)
100 parts by weight of the alkali-soluble (meth) acrylic copolymer solution obtained in Example 1, 80 parts by weight of caprolactone-modified ditrimethylolpropane tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., “NK Ester AD-TMP-4CL”), many 15 parts by weight of a functional epoxy compound (manufactured by Yuka Shell Epoxy, “Epicoat 815”), 15 parts by weight of a photoinitiator (manufactured by Ciba Specialty Chemicals, “Irgacure 369”), and 120 parts by weight of diethylene glycol dimethyl ether as a solvent Were mixed to prepare a curable resin composition for column spacers, and a liquid crystal display device was produced in the same manner as in Example 1.

(Example 3)
100 parts by weight of the alkali-soluble (meth) acrylic copolymer solution obtained in Example 1, 60 parts by weight of caprolactone-modified dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., “KAYARAD DPCA-120”), 1,9- 20 parts by weight of nonaethylene glycol diacrylate (“Light acrylate 9EG-A” manufactured by Kyoeisha Chemical Co., Ltd.), 15 parts by weight of a polyfunctional epoxy compound (“Epicoat 815” manufactured by Yuka Shell Epoxy Co., Ltd.), photoinitiator (Ciba Specialty) A curable resin composition for column spacers was prepared by mixing 15 parts by weight of “Irgacure 369” manufactured by Chemicals Co., Ltd. and 120 parts by weight of diethylene glycol dimethyl ether as a solvent. A device was manufactured.

Example 4
100 parts by weight of the alkali-soluble (meth) acrylic copolymer solution obtained in Example 1, 80 parts by weight of caprolactone-modified dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., “KAYARAD DPCA-120”), polyfunctional epoxy compound 15 parts by weight (manufactured by Yuka Shell Epoxy, “Epicoat 815”), 15 parts by weight of photoreaction initiator (manufactured by Ciba Specialty Chemicals, “Irgacure 369”), and thermal crosslinking agent (manufactured by Asahi Kasei Chemicals, “ DURANATE 17B-60PX ") 8 parts by weight, and further 120 parts by weight of diethylene glycol dimethyl ether as a diluent were added and mixed to prepare a curable resin composition for column spacers. A liquid crystal display device was manufactured.

(Comparative Example 1)
100 parts by weight of the copolymer solution prepared in Example 1, 80 parts by weight of caprolactone-modified dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., “KAYARAD DPCA-120”), photoinitiator (manufactured by Ciba Specialty Chemicals, “Irgacure 369”) 15 parts by weight and 120 parts by weight of diethylene glycol dimethyl ether as a diluent were added and mixed to prepare a curable resin composition for a column spacer. Further, in the same manner as in Example 1, a liquid crystal display device Manufactured.

(Comparative Example 2)
100 parts by weight of the copolymer solution prepared in Example 1, 80 parts by weight of dipentaerythritol hexaacrylate (manufactured by Kyoeisha Kayaku Co., Ltd., “Light acrylate DPE-6A”), polyfunctional epoxy compound (manufactured by Yuka Shell Epoxy Co., Ltd.) "Epicoat 815") 15 parts by weight, photoreaction initiator (Ciba Specialty Chemicals, "Irgacure 369") 15 parts by weight, and diethylene glycol dimethyl ether 120 parts by weight as a diluent are added and mixed to cure column spacers A liquid crystal display element was produced in the same manner as in Example 1.

(Evaluation of column spacer)
In a room adjusted to a temperature of 25 ° C., the column spacers obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were compressed at a load application rate of 10 mN / s, and the height corresponding to 85% of the initial height H ₀ was obtained. Compressed until Here, the column spacer height when a load of 10 mN was applied was H ₁ , the column spacer height corresponding to 85% of H ₀ was H ₂ , and the load when the load reached H ₂ was F. Next, the load F was held for 5 seconds and subjected to deformation at a constant load. Then, the load was removed at a load application speed of 10 mN / sec, and the recovery deformation of the column spacer height due to elastic recovery was measured. The height of the column spacer at the time when the compression deformation during this period reached the maximum was H _3, and the height of the column spacer when a load of 10 mN was applied in the process of recovering the deformation of the column spacer was H ₄ . Using the obtained values, the elastic modulus at the time of 15% compression and the recovery rate at the time of 15% compression deformation were calculated by the formulas (1) and (2).

Elastic modulus E = F / (D × S) (1)
Recovery rate R = (H ₄ −H ₃ ) / (H ₁ −H ₃ ) × 100 (2)

(Evaluation of liquid crystal display elements)
The liquid crystal display elements obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were turned on, and the uniformity of the cell gap was visually observed on the display screen and evaluated according to the following criteria. Next, each liquid crystal display element was left standing at 60 ° C. for 2 days with the liquid crystal display element standing vertically. After standing, the display image was visually observed, and the occurrence of poor gravity was evaluated according to the following criteria.
Furthermore, after the liquid crystal display element was allowed to stand at −20 ° C. for 24 hours, the liquid crystal display element was placed between crossed Nicols and visually observed to evaluate the occurrence of low temperature foaming according to the following criteria.
Evaluation of cell gap ○: Uniform ×: Color unevenness Evaluation of gravity failure ○: Uniform ×: Color unevenness Evaluation of low-temperature foaming ○: No foaming ×: With foaming

ADVANTAGE OF THE INVENTION According to this invention, the column spacer which uses the curable resin composition for column spacers which can manufacture the column spacer which can suppress effectively generation | occurrence | production of the color nonuniformity by a gravity defect, and this curable resin composition for column spacers Spacers and liquid crystal display elements can be provided.

Claims (6)

Alkali-soluble (meth) acrylic copolymer obtained by copolymerizing unsaturated carboxylic acid and / or unsaturated carboxylic acid anhydride and other unsaturated compound, polymerizable compound having ethylenically unsaturated bond, polyfunctional A curable resin composition for a column spacer containing an epoxy compound and a photoreaction initiator, wherein the cured product has an elastic modulus of 0.2 to 1.0 GPa at 15% compression at 25 ° C. A curable resin composition for column spacers, characterized in that it is present. The curable resin composition for a column spacer according to claim 1, wherein the polymerizable compound having an ethylenically unsaturated bond is a caprolactone-modified trifunctional or higher functional (meth) acrylate compound. The photothermosetting resin composition for column spacers according to claim 1 or 2, comprising a compound having two or more blocked isocyanate groups. A curable resin fine particle for a column spacer, comprising a compound having a polymerizable unsaturated bond and a polyethylene glycol skeleton. A column spacer comprising the curable resin composition for a column spacer according to claim 1, 2, 3 or 4. A curable resin composition for a column spacer according to claim 1, 2, 3, or 4, or a column spacer according to claim 5 is used.