JP2009244368A - Curable resin composition for column spacers, column spacers and liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable resin composition for column spacers wherein the generation of uneven application is reduced when applied on a substrate with cells bonded on multiple faces, column spacers made by using the curable resin composition for column spacers, and a liquid crystal display element made by using the curable resin composition for column spacers. <P>SOLUTION: The curable resin composition for column spacers includes: alkali-soluble high-molecular compound (A); a compound having two or more polymerizable unsaturated bonds in the molecule (B); a photoreaction initiator (C); and a solvent (D), wherein the solvent (D) includes at least cyclohexanone. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a curable resin composition for a column spacer capable of reducing the occurrence of coating unevenness when applied on a substrate having a multifaceted cell, and a column spacer using the column spacer curable resin composition. The present invention relates to a column spacer and a liquid crystal display element using the column spacer curable resin composition.

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.).
By using such a column spacer, 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.

When a liquid crystal display device is manufactured using a substrate on which such column spacers are formed, usually, a curable resin composition is applied on a substrate on which cells are multifaceted, and then a convex pattern is formed by a photolithographic technique. Form. However, when a conventional curable resin composition is applied onto a substrate having a multifaceted cell, there is a problem that radial application unevenness may occur from the corner of each cell. Such coating unevenness is a cause of cell gap variation, and causes a reduction in display quality of the liquid crystal display element.

JP 2001-91954 A JP 2001-159707 A

In view of the above-mentioned present situation, the present invention provides a curable resin composition for a column spacer that can reduce the occurrence of coating unevenness when the cell is applied on a multifaceted substrate, and the column spacer curable resin composition. It is an object to provide a column spacer used, a column spacer using the column spacer curable resin composition, and a liquid crystal display element.

The present invention relates to a column spacer comprising an alkali-soluble polymer compound (A), a compound (B) having two or more polymerizable unsaturated bonds in the molecule, a photoreaction initiator (C), and a solvent (D). The solvent (D) is a curable resin composition for column spacers containing at least cyclohexanone.
The present invention is described in detail below.

The reason for the occurrence of coating unevenness is that the film thickness of the cell frame is about 1 to 3 μm thicker than the film thickness of the peripheral part. It is considered that when trying to spread on the part, the cell frame becomes a barrier and uniform coating cannot be performed.
As a result of intensive studies, the present inventors have found that coating unevenness can be remarkably reduced by adding cyclohexanone to the solvent of the curable resin composition for column spacers, and have completed the present invention.

The curable resin composition for column spacers of the present invention (hereinafter also simply referred to as “curable resin composition”) has an alkali-soluble polymer compound (A) and two or more polymerizable unsaturated bonds in the molecule. A compound (B), a photoinitiator (C), and a solvent (D) are contained.

The alkali-soluble polymer compound (A) used in the curable resin composition of the present invention has reactivity by light or heat and alkali solubility.
The alkali-soluble polymer compound (A) can be prepared using, for example, the following (A1), (A2), (A3), (A4), and (A5) as raw materials.

(A1): unsaturated carboxylic acid (A2): compound having tricyclodecane skeleton and / or dicyclopentadiene skeleton and unsaturated bond in one molecule (A3): copolymerized with (A1) and (A2) Compound (A4) having possible unsaturated bond: Glycidyl (meth) acrylate (A5): Acid anhydride In this specification, (meth) acrylate means acrylate and / or methacrylate.

Specific examples of (A1) include acrylic acid or methacrylic acid. Acrylic acid and methacrylic acid may be used alone or in combination.
In addition to the acrylic acid and methacrylic acid, other acids can be used. Examples of the other acid include crotonic acid, o-, m-, p-vinylbenzoic acid, itaconic acid, maleic acid, and fumaric acid. A monomer having a hydroxy group and a carboxyl group in the same molecule, such as α- (hydroxymethyl) acrylic acid, can also be used.

Examples of (A2) include dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. . These may be used alone or in combination of two or more.
As a commercial item among said (A2), Hitachi Chemical Co., Ltd. FA-512A, FA-512M, FA-513A, FA-513M etc. are mentioned, for example.

Examples of (A3) include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, n-propyl (meth) acrylate, and iso-propyl (meth). Acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, neopentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, Unsaturated cals such as 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate and aminoethyl (meth) acrylate Unsubstituted or substituted alkyl ester of acid; cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, menthyl (meth) acrylate, cyclo Pentenyl (meth) acrylate, cyclohexenyl (meth) acrylate, cycloheptenyl (meth) acrylate, cyclooctenyl (meth) acrylate, mentadienyl (meth) acrylate, isobornyl (meth) acrylate, pinanyl (meth) acrylate, adamantyl (meth) acrylate, norbornenyl Ester compound containing alicyclic group of unsaturated carboxylic acid such as (meth) acrylate and pinenyl (meth) acrylate; oligo Monosaturated carboxylic acid ester compounds of glycols such as tylene glycol monoalkyl (meth) acrylate; ester compounds containing an aromatic ring of unsaturated carboxylic acid such as benzyl (meth) acrylate and phenoxy (meth) acrylate; styrene, α- Aromatic vinyl compounds such as methylstyrene, p-methylstyrene, p-chlorostyrene and vinyltoluene; carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate; vinyl cyanide compounds such as (meth) acrylonitrile and α-chloroacrylonitrile Aromatic substituted maleimides such as N-cyclohexylmaleimide, N-phenylmaleimide, benzylmaleimide, naphthylmaleimide, o-chlorophenylmaleimide; methylmaleimide, ethylmaleimide, propylmaleimide Maleimide compounds such as alkyl-substituted maleimides such as isopropyl maleimide. These may be used alone or in combination of two or more.

As said (A4), commercially available glycidyl (meth) acrylate can be used.

Examples of (A5) include oxalic anhydride, maleic anhydride, succinic anhydride, tartaric anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydro Carboxylic anhydrides such as phthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, chlorendic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, biphenyltetracarboxylic anhydride Compounds. These acid anhydrides are added and reacted with the hydroxyl group of the unsaturated group-containing resin when (A1) is reacted with the copolymer obtained by copolymerizing (A2), (A3), and (A4). The

The alkali-soluble polymer compound (A) can be prepared by three methods (i) to (iii).
As the copolymerization method, for example, a conventionally known method such as bulk polymerization, solution polymerization, suspension polymerization, dispersion polymerization, emulsion polymerization using a radical polymerization initiator and a molecular weight regulator as necessary may be employed. Can do. Of these, solution polymerization is preferred.

(I) 5% of the carboxyl groups contained in the copolymer obtained by copolymerizing the above (A1), (A2) and (A3) (hereinafter also referred to as “copolymer having a carboxyl group”). A method of adding (A4) to ˜90%.

In the copolymer having a carboxyl group, the content of the component derived from (A1) is 2 to 95 mol%, the content of the component derived from (A2) is 0.02 to 95 mol%, (A3 The content of the component derived from () is preferably 2 to 95% by mole. If the composition ratio is outside this range, the balance between flexibility and heat resistance may be lost. More preferably, the component derived from (A1) is 20 to 80 mol%, the component derived from (A2) is 0.03 to 80 mol%, and the component derived from (A3) is 20 to 80 mol%.

The amount of (A4) added to the copolymer having a carboxyl group is 0.05 to 0.9 equivalent, preferably 0.2 to 0.8 equivalent, based on 1.0 equivalent of carboxyl group. React at a rate of

(Ii) 5 of the glycidyl group contained in the copolymer obtained by copolymerizing the above (A4), (A2) and (A3) (hereinafter also referred to as “copolymer having a glycidyl group”). A method of adding (A1) to ˜100%.

In the copolymer having a glycidyl group, the content of the component derived from (A4) is 2 to 95 mol%, the content of the component derived from (A2) is 0.02 to 95 mol%, (A3 The content of the component derived from () is preferably 2 to 95% by mole. More preferably, the component derived from (A4) is 20 to 80 mol%, the component derived from (A2) is 0.03 to 80 mol%, and the component derived from (A3) is 20 to 80 mol%.

The amount of (A1) added to the glycidyl group-containing copolymer is 0.05 to 1.0 equivalent, preferably 0.2 to 0.8 equivalent, based on 1.0 equivalent of glycidyl group. React at a rate of If it is less than 0.05 equivalent, sufficient curing may not be obtained.

(Iii) A method in which a copolymer having the glycidyl group is prepared, and (A5) is further reacted with a hydroxyl group obtained by adding the component (A1) to the total amount of glycidyl groups contained.

Furthermore, since the resin obtained by reacting (A5) reacts with a hydroxyl group generated by imparting a carboxyl group to the copolymer having the glycidyl group, an acid anhydride having an equivalent amount less than the equivalent amount of the hydroxyl group is added. Can be obtained. In addition, said addition reaction of a photosensitive group is performed by a conventional method.

As said alkali-soluble high molecular compound (A), commercially available things, such as "Lipoxy" by Showa High Polymer Co., Ltd., can also be used, for example.

Although it does not specifically limit as a weight average molecular weight of the said alkali-soluble high molecular compound (A), A preferable minimum is 3000 and a preferable upper limit is 100,000. If it is less than 3000, the developability when producing a column spacer using the curable resin composition of the present invention may be reduced, and if it exceeds 100,000, the curable resin composition of the present invention is used. The resolution at the time of manufacturing the column spacer may be lowered. A more preferred lower limit is 5000, and a more preferred upper limit is 50,000.

In the curable resin composition of the present invention, the content of the alkali-soluble polymer compound (A) is not particularly limited, but a preferred lower limit is 10% by weight and a preferred upper limit is 70% by weight. When it is less than 10% by weight, when the curable resin composition of the present invention is used for a column spacer, the solubility in an alkaline developer used for producing the column spacer is insufficient, and the column spacer to be produced The developability of the pattern may be insufficient, and if it exceeds 70% by weight, the curable resin composition of the present invention is not sufficiently photocured, and when used for column spacer applications, the column spacers are formed by photolithography. A pattern may not be formed. A more preferred lower limit is 15% by weight, and a more preferred upper limit is 60% by weight.

Although it does not specifically limit as a compound (B) which has two or more polymerizable unsaturated bonds in the said molecule | numerator, For example, at least 1 sort (s) of modification | denaturation selected from the group which consists of caprolatokun modification | denaturation, ethylene oxide modification, and propylene oxide modification | denaturation The polyfunctional (meth) acrylate compound (hereinafter also simply referred to as “modified polyfunctional (meth) acrylate compound”) and / or polyfunctional urethane (meth) acrylate compound is preferable.

In the curable resin composition containing the modified polyfunctional (meth) acrylate compound, the column spacer using the curable resin composition has excellent recovery from compression deformation. In the liquid crystal display element manufactured by using the liquid crystal display device, it is possible to simultaneously suppress “gravity failure” due to liquid crystal expansion during heating and “low temperature foaming” due to liquid crystal shrinkage at low temperatures. Further, when forming a pattern to be a column spacer by a photolithographic technique, sharp resolution can be obtained without generating a development residue. Further, since the solubility in the developer is high, when the developer is recycled and used, it is difficult to clog the collection filter of the developer, and high process suitability can be produced.
In the present specification, caprolactone modification means that a caprolactone ring-opening polymer or ring-opening polymer is introduced between the alcohol-derived site of the (meth) acrylate compound and the (meth) acryloyl group. . Moreover, ethylene oxide modification (propylene oxide modification) means that an ethylene oxide segment (propylene oxide segment) is introduced between the alcohol-derived site of the (meth) acrylate compound and the (meth) acryloyl group.

The caprolactone-modified polyfunctional (meth) acrylate compound is not particularly limited, and examples thereof include trimethylolpropane di (meth) acrylate, trimethylolethane di (meth) acrylate, pentaerythritol di (meth) acrylate, and ditrimethylolpropane. A compound obtained by modifying a bifunctional (meth) acrylate compound such as di (meth) acrylate and dipentaerythritol di (meth) acrylate with caprolactone; pentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ditrimethylolpropane tri ( Tri- or higher functional (meth) acrylates such as (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate Compound compound was caprolactone, and the like.
Among these, a compound obtained by modifying a trifunctional or higher-functional (meth) acrylate compound with caprolactone is particularly preferable because the polymerization reaction proceeds rapidly and the exposure sensitivity is easily improved.
These caprolactone-modified polyfunctional (meth) acrylates may be used alone or in combination of two or more.

The caprolactone-modified degree of modification of the above-mentioned caprolactone-modified polyfunctional (meth) acrylate is 2 or more polymerizable unsaturated bonds in the molecule, where n is the number of functional groups of the base polyfunctional (meth) acrylate compound. The preferable lower limit is 0.5 nmol and the preferable upper limit is 5 nmol with respect to 1 mol of the compound having azobenzene. If it is less than 0.5 nmol, the flexibility of the column spacer to be produced may be insufficient, and if it exceeds 5 nmol, the reactivity during exposure when producing the column spacer is reduced, and the column to be produced is produced. Spacer patterning may be difficult. A more preferable lower limit is 1 nmol, and a more preferable upper limit is 3 nmol.

A specific method for modifying the above-mentioned polyfunctional (meth) acrylate compound with caprolactone is not particularly limited. For example, a polyhydric alcohol and caprolactone are reacted to synthesize caprolactone-modified alcohol, and then (meth) acrylic acid is esterified. A method in which (meth) acrylic acid and caprolactone are reacted to synthesize caprolactone-modified (meth) acrylic acid, followed by an esterification reaction with alcohol; (meth) acrylic acid, caprolactone, and polyhydric alcohol The method of reacting all together is mentioned.

The polyfunctional (meth) acrylate compound modified with ethylene oxide (and / or propylene oxide) is not particularly limited. For example, the polyfunctional (meth) acrylate compound is modified with ethylene oxide (and / or propylene oxide). And the like.
Among these, a compound obtained by modifying a trifunctional or higher functional (meth) acrylate compound with ethylene oxide (and / or propylene oxide) is particularly preferable because the polymerization reaction proceeds rapidly and the exposure sensitivity is easily improved.
These ethylene oxide-modified (and / or propylene oxide-modified) polyfunctional (meth) acrylates may be used alone or in combination of two or more.

The degree of modification of the ethylene oxide-modified (and / or propylene oxide-modified) of the above-mentioned ethylene oxide-modified (and / or propylene oxide-modified) polyfunctional (meth) acrylate is the functionality of the base polyfunctional (meth) acrylate compound. When the number of groups is n, the preferable lower limit is 0.5 nmol and the preferable upper limit is 15 nmol with respect to 1 mol of the polyfunctional (meth) acrylate compound. If it is less than 0.5 nmol, the flexibility of the column spacer to be produced may be insufficient. If it exceeds 15 nmol, the affinity for an alkaline developer will be high, and the resolution will be lowered due to swelling. It tends to happen. A more preferable lower limit is 3 nmol, and a more preferable upper limit is 10 nmol.

The specific method for modifying the polyfunctional (meth) acrylate compound with ethylene oxide and / or propylene oxide is not particularly limited. For example, a polyhydric alcohol and ethylene oxide and / or propylene oxide are reacted to produce ethylene oxide. A method in which an ethylene oxide-modified and / or propylene oxide-modified alcohol is esterified with a (meth) acrylic acid after synthesizing a modified and / or propylene oxide-modified alcohol; (meth) acrylic acid and ethylene oxide and / or propylene A method in which an oxide is reacted to synthesize ethylene oxide-modified and / or propylene oxide-modified (meth) acrylic acid, followed by an esterification reaction with alcohol; (meth) acrylic acid, ethylene oxide Beauty / or propylene oxide, and a method such as to collectively reacting polyhydric alcohols.

Although it does not specifically limit as said polyfunctional urethane (meth) acrylate compound, The polyfunctional urethane (meth) acrylate compound more than hexafunctional is suitable. When it is polyfunctional, there are many crosslinking points and sufficient mechanical strength can be obtained. In particular, when a urethane (meth) acrylate compound having 6 or more functional groups is used, sufficient rubbing resistance is easily exhibited.
The polyfunctional urethane (meth) acrylate compound having 6 or more functional groups is not particularly limited. Product can be used.

The compound (B) having two or more polymerizable unsaturated bonds in the molecule preferably has a carboxyl group in the molecule. By containing the compound (B) having two or more polymerizable unsaturated bonds in the molecule having such a carboxyl group, the curable resin composition of the present invention is exposed during pattern formation by a photolithographic technique. It is excellent in rapid polymerization reactivity necessary for obtaining sensitivity and affinity for an alkali developer necessary for obtaining resolution during development. In particular, the above-mentioned polyfunctional urethane (meth) acrylate compound, which is generally available, has a problem of low solubility in an alkali developer, but by introducing a carboxyl group into the molecule, the solubility in an alkali developer is improved. Can be improved.

The compound (B) having two or more polymerizable unsaturated bonds in the molecule having the carboxyl group is, for example, a compound having a carboxyl group in a part of the (meth) acryl group of the (meth) acrylate compound having three or more functions. Can be obtained by addition reaction. Specifically, for example, a method of adding an acid anhydride such as succinic anhydride or tetrahydrophthalic anhydride to a hydroxyl group of a trifunctional or higher functional (meth) acrylate compound having a hydroxyl group; a trifunctional or higher functional (meth) acrylate compound Examples thereof include a method of adding a compound having a thiol group such as thiosalicylic acid and a carboxyl group to a (meth) acryl group by an ene-thiol reaction.

In the polyfunctional (meth) acrylate compound having a carboxyl group, the preferable upper limit of the number of carboxyl groups in the molecule is 2. If it exceeds 2, the solubility / swellability in the developer becomes high. For example, when the curable resin composition of the present invention is used for a column spacer, the development pattern is peeled off or the resolution is lowered due to swelling. It tends to happen.

It does not specifically limit as a polyfunctional urethane (meth) acrylate compound which introduce | transduced the carboxyl group in the said molecule | numerator, For example, commercial items, such as Art Resin UN-5507 and HCN-1 (made by Negami Kogyo Co., Ltd.), can be used. .

As the introduction amount of the carboxyl group with respect to the polyfunctional urethane (meth) acrylate, a preferable lower limit is an acid value of 5 KOHmg / g, and a preferable upper limit is an acid value of 50 KOHmg / g. If the acid value is less than 5 KOHmg / g, the developer waste liquid in the developing process may become turbid, which may cause foreign matter defects. If it exceeds 50 KOHmg / g, the solubility in alkali is too high, and the spacer pattern may disappear in the development process.
In this specification, the acid value of the polyfunctional urethane (meth) acrylate is neutralized when 1 g of polyfunctional urethane (meth) acrylate is dissolved in an organic solvent and titrated with potassium hydroxide using phenolphthalein as an indicator. It is shown by the number of mg of potassium hydroxide required up to.

As the compound (B) having two or more polymerizable unsaturated bonds in the molecule, in addition to the modified polyfunctional (meth) acrylate compound and polyfunctional urethane (meth) acrylate compound, reactivity, developability, etc. For the purpose of adjusting, other polyfunctional polymerizable unsaturated bond-containing compounds may be used in combination.

The other polyfunctional polymerizable unsaturated bond-containing compound is not particularly limited, and examples thereof include neopentyl glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth). ) Acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, hydroxypivalic acid neopentyl glycol ester diacrylate , Polyethylene glycols such as diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, tetraethylene glycol (meth) acrylate, hexaethylene glycol (meth) acrylate, nonaethylene glycol (meth) acrylate (Meth) acrylate; polyethylene glycol such as diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, hexaethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate Examples include di (meth) acrylate.

Examples of the tri- or higher functional group include trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol tetra. Examples thereof include polyfunctional (meth) acrylate compounds such as (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

When the compound (B) having two or more polymerizable unsaturated bonds in the molecule contains the other polyfunctional polymerizable unsaturated bond-containing compound, the amount of the compound is not particularly limited, It is preferably less than 40% by weight of the total amount of the compound (B) having two or more polymerizable unsaturated bonds. If it exceeds 40% by weight, when the curable resin composition of the present invention is used for a column spacer, the flexibility of the obtained column spacer may be impaired, and the effect of suppressing poor gravity and low-temperature foaming may be reduced. A more preferred upper limit is 30% by weight.

In the curable resin composition of the present invention, the content of the compound (B) having two or more polymerizable unsaturated bonds in the molecule is not particularly limited, but a preferable lower limit with respect to the total solid content is preferably 10% by weight. The upper limit is 70% by weight. If it is less than 10% by weight, recovery from compression deformation may be deteriorated. When it exceeds 70% by weight, when the curable resin composition of the present invention is used for a column spacer, the mechanical strength becomes insufficient, and pattern scraping may occur in the rubbing process. A more preferred lower limit is 20% by weight, and a more preferred upper limit is 60% by weight.

The photoinitiator (C) is not particularly limited, and examples thereof include conventionally known photoinitiators such as benzoin, benzophenone, benzyl, thioxanthone, and derivatives thereof. 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.

In the curable resin composition of the present invention, the content of the photoreaction initiator (C) is not particularly limited, but a preferred lower limit is 0.1% by weight and a preferred upper limit is 15% by weight. If it is less than 0.1% by weight, the curable resin composition of the present invention may not be photocured, and if it exceeds 15% by weight, alkali development may not be possible in photolithography. A more preferred lower limit is 0.3% by weight, and a more preferred upper limit is 10% by weight.

The solvent (D) adjusts the viscosity of the curable resin composition of the present invention.
Although the reason is unknown, each of the present inventors, when cyclohexanone is contained as the solvent (D), applies each of the curable resin compositions of the present invention on a substrate having a multifaceted cell. It has been found that the radial coating unevenness generated from the corner of the cell can be greatly reduced.

The total amount of the solvent (D) may be cyclohexanone or a mixed solvent of cyclohexanone and another organic solvent.
When the above mixed solvent is used, a preferable lower limit of the content of cyclohexanone in the mixed solvent is 5% by weight. If it is less than 5% by weight, uneven coating may not be sufficiently reduced. A more preferred lower limit is 8% by weight, and a more preferred upper limit is 80% by weight.

Although it does not specifically limit as organic solvents other than the said cyclohexanone, The thing whose vapor pressure in 20 degreeC is 0.01-0.60 kPa, and whose boiling point is 130-190 degreeC is suitable. Specifically, for example, 4-butyl-2-pentanol, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monotertiary butyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl Ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol diacetate, propylene glycol, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol Monoe Ether acetate, propylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, methyl lactate, ethyl lactate, butyl lactate, 3-methoxybutanol, Examples include 3-methoxybutyl acetate, 3-methoxy-3-methyl-1-butanol, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate, methyl acetoacetate, and ethyl acetoacetate. Of these, propylene glycol monomethyl ether acetate or diethylene glycol ethyl methyl ether is preferable.

In the curable resin composition of the present invention, the content of the solvent (D) is not particularly limited, but the preferable lower limit with respect to 100 parts by weight of the total solid content in the curable resin composition is 50 parts by weight, and the preferable upper limit is 85. Parts by weight. If it is less than 50 parts by weight, the viscosity of the curable resin composition will be high, and if the curable resin composition dripped at the center by spin coating such as spin coating is applied to the periphery of the substrate, it will not spread well. When the amount exceeds 85 parts by weight, the viscosity of the curable resin composition becomes too low, and when the curable resin composition is applied onto a substrate by spin coating, the in-plane variation in film thickness becomes large. There is. A more preferred lower limit is 45 parts by weight, and a more preferred upper limit is 80 parts by weight.

The curable resin composition of the present invention preferably contains 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.

Examples of the reaction aid include amines such as n-butylamine, di-n-butylamine, triethylamine, triethylenetetramine, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate; tri-n-butylphosphine, etc. Phosphinic compounds such as sulphonic acid such as s-benzylisothiouronium-p-toluenesulfinate can be used. These reaction aids may be used alone or in combination of two or more.

The curable resin composition of the present invention preferably further contains a compound having two or more blocked isocyanate groups. The compound having two or more blocked isocyanate groups acts as a thermal crosslinking agent, and imparts thermosetting to the curable resin composition of the present invention by containing such a compound having two or more blocked isocyanate groups. can do.

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 thereof include those obtained by blocking hexamethylene diisocyanate and polyfunctional isocyanates composed of these oligomers with blocking agents 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.

Moreover, as what is marketed among the compounds which have such a 2 or more block isocyanate group, Duranate 17B-60PX, Duranate E-402-B80T (above, Asahi Kasei Chemicals make) etc. are mentioned, for example.

When the compound having two or more blocked isocyanate groups is contained in the curable resin composition of the present invention, the blending amount thereof has a preferable lower limit with respect to 100 parts by weight of the alkali-soluble polymer compound (A). 0.01 parts by weight, and a preferred upper limit is 50 parts by weight. If it is less than 0.01 part by weight, the curable resin composition of the present invention may not be sufficiently cured by heat, and if it exceeds 50 parts by weight, the degree of cross-linking of the resulting cured product becomes too high and will be described later. May not meet the characteristics. 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 of this invention may contain conventionally well-known additives, such as a silane coupling agent for improving adhesiveness with a board | substrate as needed.

The method for producing the curable resin composition of the present invention is not particularly limited. For example, the alkali-soluble polymer compound (A), the compound having two or more polymerizable unsaturated bonds in the molecule (B), light It can manufacture by mixing a reaction initiator (C), a solvent (D), and the additive added as needed by a conventionally well-known method.
The curable resin composition thus produced can be used after being filtered using a Millipore filter or the like having a pore diameter of about 0.5 μm.

When the curable resin composition of the present invention has the above composition, it is possible to reduce the occurrence of coating unevenness when it is applied on a substrate with multiple cells.
Further, when the modified polyfunctional (meth) acrylate compound is used as the alkali-soluble polymer compound (A), the curable resin composition of the present invention has high recoverability from compression deformation and is flexible and has a low elastic modulus. It is possible to manufacture a column spacer that achieves both. By using such a column spacer, it is possible to obtain a liquid crystal display element that effectively suppresses the occurrence of color unevenness due to poor gravity without causing low-temperature foaming.

The curable resin composition of the present invention is a 15% compression at 25 ° C. of a cured product (that is, a column spacer using the curable resin composition of the present invention) when cured by light irradiation (and heating). The preferable lower limit of the elastic modulus is 0.2 GPa, and the preferable upper limit is 1.0 GPa. If it is less than 0.2 GPa, the column spacer using the curable resin composition for a column spacer of the present invention may be difficult to maintain a cell gap. Thus, the color filter layer may be plunged when the substrates are bonded using the curable resin composition for column spacers of the present invention, or sufficient elastic deformation necessary for recovery may not be obtained. A more preferred lower limit is 0.25 GPa, a more preferred upper limit is 0.9 GPa, a still more preferred lower limit is 0.3 GPa, and a still more preferred upper limit is 0.7 GPa.

In the present specification, the cured product means a cured product when the column spacer curable resin composition of the present invention is almost completely cured by light irradiation (and heating). The condition for almost complete curing is that at least 50 mJ / cm ² of ultraviolet light is irradiated, and further, when heating, it can be cured almost completely by applying a heat treatment at a temperature of 200 to 250 ° C. for about 30 minutes. .

In this specification, 15% compression means compression so that the deformation rate of the height of the column spacer is 15%. Further, the elastic modulus and the recovery rate are measured by the following methods.
That is, first, a column spacer formed on the substrate is compressed at a load application rate of 1 mN / s, 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 is removed at a load application speed of 1 mN / sec, and the recovery deformation of the column spacer height due to elastic recovery is measured. The height of the column spacer at the time when the compression deformation during this period becomes maximum is H _3, and the height of the column spacer when a load of 0.4 mN is applied in the process of recovering the deformation of the column spacer is H ₄ . The elastic modulus and the recovery rate can be calculated by the following formula (1) and the following formula (2). The column spacer having such an elastic modulus can be obtained by including the polyfunctional (meth) acrylate compound according to the present invention described above in the curable resin composition for a column spacer of the present invention.

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

In formula (1), F represents the load (N), D represents the deformation rate of the column spacer height, and S represents the cross-sectional area (m ² ) of the column spacer.

A method for producing a column spacer using the curable resin composition for a column spacer of the present invention will be described.
When producing a column spacer using the curable resin composition for a column spacer of the present invention, first, the curable resin composition for a column spacer of the present invention is applied onto a substrate so as to have a predetermined thickness. To form a film.
The coating method is not particularly limited, and conventionally known coating methods such as spin coating, slit and spin coating, slit coating, spray coating, dip coating, and bar coating can be used.

When coating by spin coating, slit and spin coating, the curable resin composition for column spacers of the present invention contains at least cyclohexanone in the solvent, and therefore the curable resin composition is formed on the substrate on which the cells are multifaceted. Radial application unevenness generated from the corners of each cell during application can be reduced.

Next, actinic rays such as ultraviolet rays are irradiated on the formed film through a mask on which a predetermined pattern is formed. Thereby, in a light irradiation part, the alkali-soluble high molecular compound and photoinitiator which are contained in the curable resin composition for column spacers of this invention react and are photocured.
The irradiation amount of the active light is not particularly limited, but is preferably 30 mJ / cm ² or more in the case of ultraviolet rays. If it is less than 30 mJ / cm ² , the photocuring is insufficient and the subsequent alkali treatment may dissolve the exposed area and a pattern may not be formed.

Next, the photocured product after photocuring is alkali-developed to produce a column spacer having a predetermined pattern made of the photocured product of the curable resin composition for a column spacer of the present invention on the substrate.
Since the curable resin composition for a column spacer of the present invention contains the alkali-soluble polymer compound described above, it has excellent alkali developability, and also contains the polyfunctional urethane (meth) acrylate compound, The mechanical strength of the column spacer to be manufactured is excellent. Furthermore, when the polyfunctional (meth) acrylate compound according to the present invention described above is contained, the curable resin composition for a column spacer of the present invention has a high recoverability from compression deformation, and is flexible and has low elasticity. The column spacer can be formed with a sharp pattern that has almost no residue when a predetermined pattern is formed and has excellent resolution.

When the curable resin composition for column spacers of the present invention contains a compound having two or more blocked isocyanate groups, it is further contained by heating the patterned photocured product after the development treatment. An alkali-soluble polymer compound 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 is manufactured by a conventionally known method such as the ODF method, thereby generating color unevenness due to poor gravity without causing low-temperature foaming. It is possible to obtain a liquid crystal display element that can effectively suppress the above.
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, when apply | coating on the board | substrate with which the cell was multi-faced, it uses the curable resin composition for column spacers which can reduce generation | occurrence | production of a coating nonuniformity, and this column spacer curable resin composition. A column spacer, a column spacer using the column spacer curable resin composition, and a liquid crystal display element can be provided.

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

(Preparation of alkali-soluble polymer compound (A1))
145 parts by weight of propylene glycol monomethyl ether acetate (PGMEA) was placed in a flask equipped with a stirrer, a dropping funnel, a condenser, a thermometer, and a gas introduction tube, stirred while purging with nitrogen, and heated to 120 ° C.
Next, 30 parts by weight (0.185 mol) of benzyl methacrylate, 23.3 parts by weight (0.271 mol) of methacrylic acid, 35 parts by weight of isodecyl methacrylate (0.161 mol), and monomethacrylate having a tricyclodecane skeleton (Hitachi Chemical Co., Ltd., FA-513M) 1.7 parts by weight (0.008 mol) of a monomer mixture consisting of t-butyl hydroperoxide (Nippon Yushi Co., Ltd., Perbutyl O) 7.6 parts by weight (monomer 4.5 parts) to 100 parts of the mixture. This was dropped into the flask from the dropping funnel over 2 hours, and further stirred at 120 ° C. for 2 hours for aging.

Next, the inside of the flask was replaced with air, 15.6 parts by weight of glycidyl methacrylate (0.110 mol, 41% of the carboxyl group), 0.9 part by weight of trisdimethylaminomethylphenol (DMP-30) and 0. 145 parts by weight were charged into the aged, and when the reaction was continued at 120 ° C. for 6 hours, the reaction was terminated to obtain a PGMEA solution of an alkali-soluble polymer compound (A1) having a solid content of 40%.
The obtained alkali-soluble polymer compound was sampled and the molecular weight was measured by gel permeation chromatography (GPC). As a result, the weight average molecular weight was 13,000 and the solid content acid value was 90.

(Preparation of alkali-soluble polymer compound (A2))
145 parts by weight of cyclohexanone was placed in a flask equipped with a stirrer, a dropping funnel, a condenser, a thermometer, and a gas introduction tube, stirred while purging with nitrogen, and heated to 120 ° C.
Next, 30 parts by weight (0.185 mol) of benzyl methacrylate, 23.3 parts by weight (0.271 mol) of methacrylic acid, 35 parts by weight of isodecyl methacrylate (0.161 mol), and monomethacrylate having a tricyclodecane skeleton (Hitachi Chemical Co., Ltd., FA-513M) 1.7 parts by weight (0.008 mol) of a monomer mixture consisting of t-butyl hydroperoxide (Nippon Yushi Co., Ltd., Perbutyl O) 7.6 parts by weight (monomer 4.5 parts) to 100 parts of the mixture. This was dropped into the flask from the dropping funnel over 2 hours, and further stirred at 120 ° C. for 2 hours for aging.

Next, the inside of the flask was replaced with air, 15.6 parts by weight of glycidyl methacrylate (0.110 mol, 41% of the carboxyl group), 0.9 part by weight of trisdimethylaminomethylphenol (DMP-30) and 0. 145 parts by weight were charged into the aged, and when the reaction was continued at 120 ° C. for 6 hours, the reaction was terminated to obtain a cyclohexanone solution of an alkali-soluble polymer compound (A2) having a solid content of 40%.
The obtained alkali-soluble polymer compound was sampled and the molecular weight was measured by gel permeation chromatography (GPC). As a result, the weight average molecular weight was 14,000 and the solid content acid value was 90.

(Examples 1-6 and Comparative Examples 1-9)
The raw materials shown in Table 1 were mixed to prepare column spacer curable resin compositions according to Examples 1 to 6 and Comparative Examples 1 to 9.
In addition, each material shown in Table 1 is as follows.

Compound (B) having two or more polymerizable unsaturated bonds in the molecule
A-SA-TMM: Carboxylic acid-added caprolactone-modified tetramethylolmethane triacrylate (1 mol of a compound obtained by reacting 8 mol of caprolactone with 1 mol of tetramethylolmethane, and the hydroxyl group of a compound obtained by reacting 3 mol of acrylic acid by esterification) , A compound added with 1 mol of tetrahydrocarboxylic anhydride)
DPHA-40H: KAYARAD DPHA-40H (9 or more functional urethane acrylate oligomer, no carboxyl group, manufactured by Nippon Kayaku Co., Ltd.)
Carboxyl group-introduced urethane acrylate oligomer: 10-functional urethane acrylate oligomer, carboxyl group-introduced product, acid value 12 KOH / mg

Photoinitiator (C)
I-907: Irgacure 907 (Ciba Specialty Chemicals)
I-819: Irgacure 819 (Ciba Specialty Chemicals)

Solvent (D)
Cyclohexanone EDM: Diethylene glycol ethyl ethyl ether PGMEA: Propylene glycol monomethyl ether acetate Propylene glycol monomethyl ether 3-methoxybutanol EEP: Ethyl-3-ethoxypropionate 3-methoxy 3-methyl-1-butanol 3-methyl-3 methoxybutyl acetate Butyl lactate diethylene glycol diethyl ether MFDG: Dipropylene glycol monomethyl ether

(Evaluation)
The column spacer curable resin compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 9 were applied by spin coating on a 370 mm × 470 mm substrate on which a large number of cells were arranged. Next, the film was dried under reduced pressure to a vacuum pressure of 27 Pa, and dried in an oven at 80 ° C. for 2 minutes to obtain a coating film.
About the obtained coating film, it observed by visual observation under sodium reflected light, and the coating nonuniformity was evaluated by the following references | standards. The results are shown in Tables 1 and 2.
○: Radial coating unevenness cannot be confirmed Δ: Radial coating unevenness can be slightly confirmed ×: Radial coating unevenness can be clearly confirmed

ADVANTAGE OF THE INVENTION According to this invention, when apply | coating on the board | substrate with which the cell was multi-faced, it uses the curable resin composition for column spacers which can reduce generation | occurrence | production of application | coating unevenness, and this column spacer curable resin composition. A column spacer, a column spacer using the column spacer curable resin composition, and a liquid crystal display element can be provided.

Claims (9)

Curable resin for column spacers containing an alkali-soluble polymer compound (A), a compound (B) having two or more polymerizable unsaturated bonds in the molecule, a photoreaction initiator (C), and a solvent (D) A curable resin composition for column spacers, wherein the solvent (D) contains at least cyclohexanone. The solvent (D) is a mixed solvent of cyclohexanone and an organic solvent having a vapor pressure of 0.01 to 0.60 kPa at 20 ° C and a boiling point of 130 to 190 ° C. The curable resin composition for column spacers according to 1. 3. The organic solvent having a vapor pressure at 20 ° C. of 0.01 to 0.60 kPa and a boiling point of 130 to 190 ° C. is propylene glycol monomethyl ether acetate or diethylene glycol ethyl methyl ether. The curable resin composition for column spacers as described. The alkali-soluble polymer compound (A) is an unsaturated group-containing resin obtained by reacting (A4) with a copolymer obtained by copolymerizing the following (A1), (A2), (A3), or The following (A2), (A3), and (A4) copolymer obtained by copolymerizing an unsaturated group-containing resin obtained by reacting (A1), or the following (A2), (A3) A copolymer obtained by copolymerizing (A4) and then reacting (A1) with an unsaturated group-containing resin obtained by further reacting (A5). The curable resin composition for column spacers according to 1, 2 or 3.
(A1): unsaturated carboxylic acid (A2): compound having tricyclodecane skeleton and / or dicyclopentadiene skeleton and unsaturated bond in one molecule (A3): copolymerized with (A1) and (A2) Compound (A4) having possible unsaturated bond: Glycidyl (meth) acrylate (A5): Acid anhydride The compound (B) having two or more polymerizable unsaturated bonds in the molecule is a polyfunctional (meth) acrylate having at least one modification selected from the group consisting of caprolatokun modification, ethylene oxide modification and propylene oxide modification The curable resin composition for a column spacer according to claim 1, 2, 3, or 4, wherein the curable resin composition is a compound and / or a polyfunctional urethane (meth) acrylate compound having 6 or more functional groups. 6. The curable resin for a column spacer according to claim 1, wherein the compound (B) having two or more polymerizable unsaturated bonds in the molecule has a carboxyl group in the molecule. Composition. A column spacer comprising the curable resin composition for a column spacer according to claim 1, 2, 3, 4, 5 or 6. The column spacer according to claim 7, wherein an elastic modulus at 15% compression at 25 ° C. is 0.2 to 1.0 GPa. A curable resin composition for a column spacer according to claim 1, 2, 3, 4, 5 or 6, or a column spacer according to claim 8, wherein the liquid crystal display element is used.