TWI848918B - Transparent photosensitive resin composition, optical spacer, liquid crystal display device, method for manufacturing optical spacer, method for manufacturing liquid crystal display device, and use of transparent photosensitive resin composition in lens scanning exposure - Google Patents

Abstract

The purpose of the present invention is to provide a transparent photosensitive resin composition, a photospacer using the same, a liquid crystal display device, a method for manufacturing a photospacer, a method for manufacturing a liquid crystal display device, and the use of the transparent photosensitive resin composition in lens scanning exposure, wherein the transparent photosensitive resin composition can form a photospacer that suppresses height deviation of the photospacer and is difficult to plastically deform, i.e., has a high elastic recovery rate. The present invention is a transparent photosensitive resin composition, which contains at least an alkali-soluble resin, a photopolymerization initiator, and a polymerizable monomer, wherein the alkali-soluble resin in the transparent photosensitive resin composition has structural units represented by general formula (1), general formula (2), and general formula (3).

Description

Transparent photosensitive resin composition, optical spacer, liquid crystal display device, method for manufacturing optical spacer, method for manufacturing liquid crystal display device, and use of transparent photosensitive resin composition in lens scanning exposure

The present invention relates to a transparent photosensitive resin composition, a light spacer, a liquid crystal display device, a method for manufacturing the light spacer, a method for manufacturing the liquid crystal display device, and the use of the transparent photosensitive resin composition in lens scanning exposure.

Liquid crystal display devices effectively utilize the characteristics of light weight, thinness, and low power consumption, and can be used in various applications such as notebook personal computers, portable information terminals, smart phones, digital cameras, and desktop monitors.

Liquid crystal display devices include a liquid crystal layer between a color filter substrate and a thin film transistor (TFT) substrate that can display images through a specified orientation. Uniformly maintaining the spacing (cell gap) between these substrates is one of the important factors affecting image quality.

In the past, in order to maintain a uniform cell gap, spacer particles such as glass or alumina with a predetermined particle size were used. However, these spacer particles were randomly scattered on the substrate, which caused problems such as uneven display due to variations in film thickness.

In view of the above problem, a photosensitive film for forming a resin spacer used in forming a resin spacer for a liquid crystal display including a support film and a photosensitive resin layer with a film thickness of 1 μm to 10 μm is proposed (for example, refer to Patent Document 1). However, even when the resin spacer described in Patent Document 1 is used, plastic deformation occurs during the assembly (cell press bonding) of the color filter and the TFT array substrate, so there is a problem that display unevenness is still easily generated due to the height deviation of the spacer.

As a technology for suppressing the plastic deformation of the spacer, the following technologies have been proposed: a substrate for a liquid crystal panel, characterized in that a plurality of columnar spacers are provided in a non-display region on the substrate, and the columnar spacers have an elastic deformation rate of 60% or more relative to a compressive load of 2.0 GPa at room temperature (for example, refer to Patent Document 2); or a photosensitive resin composition for a spacer, characterized in that an alkali-soluble resin, a photopolymerization initiator, and a polymerizable monomer are used as main components, and the acrylic acid equivalent of the entire photosensitive resin composition is 200 or less (for example, refer to Patent Document 3), etc.

On the other hand, in order to increase the number of chamfers and improve the yield, the size of plain glass substrates has been continuously increased. As a technology for exposing a substrate having a wide exposure area using a small mask, the following scanning exposure method has been proposed: relative to the substrate being transported in a certain direction at a certain speed by a substrate transport mechanism, in the exposure section, exposure light from a continuous light source is passed through the opening of a mask provided on the optical path of the exposure optical system and irradiated, and the image of the opening is transferred to the substrate (for example, refer to Patent Document 4). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 11-174464 [Patent Document 2] Japanese Patent Publication No. 2003-241199 [Patent Document 3] Japanese Patent Publication No. 2005-292269 [Patent Document 4] Japanese Patent Publication No. 2006-292955

[Problems to be solved by the invention] As a method for improving the elastic deformation rate of the columnar spacers described in Patent Documents 2 and 3, a method of containing a large amount of monomers having a large number of functional groups in the photosensitive resin composition can be cited. However, the coating film of the photosensitive resin composition containing a large amount of monomers has high fluidity after drying, and the film thickness is easily uneven during the production process, so there is a problem that the height of the photospacer is easily varied.

On the other hand, in the scanning exposure method of Patent Document 4, in particular, in the lens scanning exposure in which a plurality of lenses are arranged in two rows, the joint portion between lenses where the exposure amount is lower than that of the normal portion is designed so that the exposure amount is the same as that of the normal portion by exposing twice, thereby enabling firing in a wide range.

However, when a photosensitive resin composition containing a large amount of monomers as described in Patent Documents 2 and 3 is exposed by lens scanning, there is a problem that the height deviation of the optical spacers formed at the joints between lenses becomes large. The height deviation of the optical spacers causes uneven display of liquid crystal display devices, so it is required to form the optical spacers with uniform height.

In the case of close exposure, which is a previous exposure method, if the distance between the photo spacers is less than about 15 μm, the photo spacers tend to be easily connected due to the influence of diffraction light. In order to avoid the connection, it is proposed to perform multi-patterning by staggering one plate and performing multiple exposures. However, in multi-patterning, there is also a problem that the film thickness of the next exposure part becomes thinner due to the flow of the pre-baked film after the initial exposure, and the height deviation of the photo spacers becomes larger.

Therefore, the purpose of the present invention is to provide a transparent photosensitive resin composition, a light spacer using the same, a liquid crystal display device, a method for manufacturing a light spacer, a method for manufacturing a liquid crystal display device, and the use of the transparent photosensitive resin composition in lens scanning exposure, wherein the transparent photosensitive resin composition can be formed to suppress the height deviation of the light spacer and is difficult to plastically deform, that is, a light spacer with a high elastic recovery rate. [Means for solving the problem]

In order to solve the above-mentioned problem, the present invention mainly has the following structure. A transparent photosensitive resin composition, which contains at least an alkali-soluble resin, a photopolymerization initiator and a polymerizable monomer, wherein the alkali-soluble resin has: A) a structural unit represented by the following general formula (1), B) a structural unit represented by the following general formula (2), and C) a structural unit represented by the following general formula (3), The alkali-soluble resin has an ethylene unsaturated group equivalent of 400 g/mol or less.

[Chemistry 1]

In the general formula (1), ^R1 represents a hydrogen atom or a methyl group.

[Chemistry 2]

In the general formula (2), ^R2 and ^R3 each independently represent _a hydrogen atom or a methyl group. X represents _-CH2CH (OH) _CH2O (C=O)-, -CH2CH2NH(C=O)O( _CH2 ) _mO (C=O ₎ - or -( _CH2 ) _nO (C=O _{) NHCH2CH2O} (C=O)-. m and n each independently represent an integer of 1 to 4.

[Chemistry 3]

In the general formula (3), Y represents an aryl group having 6 to 11 carbon atoms which may have a substituent, an arylalkyl group having 7 to 10 carbon atoms which may have a substituent, or a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent. [Effect of the invention]

According to the transparent photosensitive resin composition of the present invention, even when exposure is performed by a lens scanning method or a proximity method in which height deviation of the photospacer is likely to increase, a photospacer with suppressed height deviation and high elastic recovery rate can be formed.

The transparent photosensitive resin composition of the present invention (hereinafter, sometimes described as "photosensitive resin composition") contains at least an alkali-soluble resin, a photopolymerization initiator, and a polymerizable monomer. By containing the photopolymerization initiator and the polymerizable monomer, the exposed part can be photocured and made insoluble in an alkaline developer. By containing the alkali-soluble resin, the unexposed part can be removed using an alkaline developer, so that a desired pattern can be formed by exposure and development.

"Transparent" in the present invention means that when the photosensitive resin composition is photocured to form a cured film with a thickness of 3 μm, the light transmittance at a wavelength of 400 nm to 700 nm is 80% or more. In order to improve the light transmittance at a wavelength of 400 nm to 700 nm, the photosensitive resin composition of the present invention preferably does not substantially contain a coloring agent such as a pigment or dye.

The alkali-soluble resin in the present invention refers to a resin having a structural unit represented by the general formula (1) described below. By having a carboxyl group, the solubility in an alkaline developer can be improved.

The alkali-soluble resin of the present invention has: A) a structural unit represented by the following general formula (1), B) a structural unit represented by the following general formula (2), and C) a structural unit represented by the following general formula (3). By having the structural unit represented by the following general formula (1), the solubility of the resin relative to the alkaline developer can be improved. By having the structural unit represented by the following general formula (2), an ethylenic unsaturated group can be introduced into the side chain of the alkali-soluble resin, and the sensitivity during exposure and development and the elastic recovery rate of the photospacer can be improved. By having the structural unit represented by the following general formula (3), the height deviation of the photospacer can be suppressed.

[Chemistry 4]

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group. R ¹ is preferably a methyl group, which can increase the viscosity of the pre-baked film and further suppress height deviation.

[Chemistry 5]

In the general formula (2), ^R2 and ^R3 each independently represent _a hydrogen atom or a methyl group. X represents _-CH2CH (OH) _CH2O (C=O)-, -CH2CH2NH(C=O)O( _CH2 ) _mO (C=O ₎ - or -( _CH2 ) _nO (C=O _{) NHCH2CH2O} (C=O)-. m and n each independently represent an integer of 1 to 4.

[Chemistry 6]

In the general formula (3), Y represents an aryl group having 6 to 11 carbon atoms which may have a substituent, an aralkyl group having 7 to 10 carbon atoms which may have a substituent, or a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent. Y is preferably a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, and more preferably a cyclohexyl group, which can further increase the viscosity of the prebaked film and further suppress height variation.

The alkali-soluble resin of the present invention can be obtained, for example, by copolymerizing a copolymer component constituting a structural unit represented by the general formula (1), a copolymer component constituting a structural unit represented by the general formula (2), and a copolymer component constituting a structural unit represented by the general formula (3). Other copolymer components may also be copolymerized.

The structural unit represented by the general formula (2) can be introduced by allowing an ethylenically unsaturated compound having a glycidyl group to react with the carboxyl group of the acrylic polymer having the structural unit represented by the general formula (1) and the structural unit represented by the general formula (3). Similarly, the structural unit represented by the general formula (2) can be introduced by allowing an ethylenically unsaturated compound having a carboxyl group, an ethylenically unsaturated compound having an isocyanate group, and an ethylenically unsaturated compound having a hydroxyl group to react with the glycidyl group, hydroxyl group, and isocyanate group of the acrylic polymer having the structural unit represented by the general formula (1) and the structural unit represented by the general formula (3).

Examples of copolymer components constituting the structural unit represented by the general formula (1) include (meth)acrylic acid and the like. Two or more of these may be used. Among these, methacrylic acid is preferred because it can further increase the viscosity of the prebaked film and further suppress height deviation.

Examples of copolymer components constituting the structural unit represented by the general formula (2) include (meth)acrylic acid, glycidyl (meth)acrylate, 2-isocyanatoethyl methacrylate, or 2-hydroxyethyl (meth)acrylate. Two or more of these may be used. Among these, glycidyl (meth)acrylate is preferably added to (meth)acrylic acid.

As the copolymer component constituting the structural unit represented by the general formula (3), for example, N-benzylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, etc. can be listed. Two or more of these can be used. Among these, N-cyclohexylmaleimide is preferred, which can further increase the viscosity of the pre-baked film and further suppress the height deviation.

Examples of other copolymer components include: unsaturated carboxylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, benzyl (meth)acrylate, and isobornyl (meth)acrylate; unsaturated carboxylic acid aminoalkyl esters such as aminoethyl acrylate; polycarboxylic acid monoesters such as mono(2-(meth)acryloyloxyethyl) phthalate; styrene, p-methylstyrene, o-methyl Aromatic vinyl compounds such as styrene, m-methylstyrene, α-methylstyrene; carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate; vinyl cyanide compounds such as (meth)acrylonitrile and α-chloro(meth)acrylonitrile; aliphatic conjugated dienes such as 1,3-butadiene and isoprene; ethylenically unsaturated compounds having a tricyclodecane skeleton or a dicyclopentadiene skeleton such as dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tricyclodecyl (meth)acrylate, tricyclodecane dimethanol di(meth)acrylate; monocarboxylic acids such as crotonic acid and vinyl acetic acid or their anhydrides; dicarboxylic acids such as itaconic acid, maleic acid, fumaric acid or their anhydrides, etc.

When the total amount of the structural units of the alkali-soluble resin is 100 mol%, the amount of the structural units represented by the general formula (3) is preferably 10 mol% to 23 mol%. If the amount of the structural units represented by the general formula (3) is 10 mol% or more, the dry viscosity can be further increased, and if it is 15 mol% or more, the viscosity of the pre-baked film can be further increased. On the other hand, if the amount of the structural units represented by the general formula (3) is 23 mol% or less, the ethylenic unsaturated group equivalent and the acid value can be easily adjusted to the preferred range described below.

The ethylene unsaturated group equivalent of the alkali-soluble resin in the present invention is 400 g/mol or less. If the ethylene unsaturated group equivalent exceeds 400 g/mol, the crosslinking density of the photospacer will decrease and the elastic recovery rate will decrease. The ethylene unsaturated group equivalent of the alkali-soluble resin is preferably 360 g/mol or less, and more preferably 300 g/mol or less.

Here, the so-called ethylenic unsaturated group equivalent refers to the number of grams relative to 1 mol of ethylenic unsaturated groups, and the smaller the value, the greater the amount of ethylenic unsaturated groups contained. For example, the higher the content ratio of the structural unit represented by the general formula (2) in B) having ethylenic unsaturated groups, the smaller the ethylenic unsaturated group equivalent. The ethylenic unsaturated group equivalent of the alkali-soluble resin can be adjusted to the desired range by the copolymerization ratio of the compound having ethylenic unsaturated groups. Furthermore, the ethylenic unsaturated group equivalent can be calculated by measuring the iodine value using the method described in the test method 6.0 of JIS K 0070:1992.

The weight average molecular weight ("Mw") of the alkali-soluble resin in the present invention is preferably 10,000 to 100,000. By setting the Mw to 10,000 or more, the viscosity of the pre-baked film can be increased and the height deviation can be further suppressed. The Mw is more preferably 20,000 or more. On the other hand, by setting the Mw to 100,000 or less, the unevenness of the pattern surface can be suppressed and the surface shape of the pattern can be improved. The Mw is more preferably 80,000 or less. Here, the Mw of the alkali-soluble resin in the present invention is a conversion value by standard polystyrene and can be measured using gel permeation chromatography.

The acid value of the alkali-soluble resin in the present invention is preferably 60 mgKOH/g to 100 mgKOH/g. By setting the acid value to 60 mgKOH/g or more, the height deviation can be further reduced. The acid value is more preferably 65 mgKOH/g or more. On the other hand, by setting the acid value to 100 mgKOH/g or less, the unevenness of the pattern surface can be suppressed and the surface shape of the pattern can be improved. The acid value is more preferably 95 mgKOH/g or less. The acid value of the alkali-soluble resin can be adjusted to the desired range by the copolymerization ratio of the compound having a carboxyl group. Here, the acid value of the alkali-soluble resin in the present invention can be determined by the neutralization titration method in Item 3.1 of the test method of JIS K 0070:1992. Furthermore, when an alkali-soluble resin solution having a solid content of about 30% by mass is used for measurement, 5 g of the alkali-soluble resin solution is placed in an aluminum cup (f45 mm) and heated at 130°C for 1 hour to remove the solvent, thereby obtaining the amount of alkali-soluble resin solid content required for the measurement of the acid value.

When the alkali-soluble resin is obtained by adding glycidyl (meth)acrylate to (meth)acrylic acid, the alkali-soluble resin and unreacted glycidyl (meth)acrylate may remain together. The residual amount of glycidyl (meth)acrylate is preferably 0.001 mass % to 0.500 mass % relative to the solid content in the above-mentioned method. By setting the residual amount of glycidyl (meth)acrylate to 0.001 mass % or more, the heating time for removing glycidyl (meth)acrylate does not become longer, and gelation of the alkali-soluble resin caused by heating can be suppressed. On the other hand, by setting the residual amount of glycidyl (meth)acrylate to 0.500 mass % or less, it is possible to suppress the defect during development. It is more preferably 0.2 mass % or less, and further preferably 0.03 mass % or less. Here, the residual amount of glycidyl (meth)acrylate in the alkali-soluble resin can be obtained from the amount of glycidyl (meth)acrylate measured from the alkali-soluble resin solution using gas chromatography and the solid content concentration of the alkali resin solution.

The content of the alkali-soluble resin in the photosensitive resin composition of the present invention is preferably 25 to 82 parts by mass relative to 100 parts by mass of the polymerizable monomer described later. By setting the content of the alkali-soluble resin to 25 parts by mass or more, the height deviation can be further suppressed. The content of the alkali-soluble resin is more preferably 34 parts by mass or more. On the other hand, by setting the content of the alkali-soluble resin to 82 parts by mass or less, the elastic recovery rate can be further improved. The content of the alkali-soluble resin is more preferably 66 parts by mass or less, further preferably 62 parts by mass or less, further preferably 55 parts by mass or less, and particularly preferably 40 parts by mass or less.

The photopolymerization initiator in the present invention refers to a compound that decomposes and/or reacts by light (including ultraviolet rays or electron beams) and generates free radicals. The photosensitive resin composition of the present invention contains a photopolymerization initiator, thereby improving the sensitivity. Examples of photopolymerization initiators include oxime ester compounds, phenyl alkyl ketone compounds, benzophenone compounds, thioxanthrone compounds, imidazole compounds, benzothiazole compounds, benzoxazole compounds, acyl phosphine oxide compounds, and titanocene compounds. Two or more of these compounds may be contained.

Examples of the oxime ester compounds include 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyl oxime)], ethyl ketone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-, 1-(O-acetyl oxime), ethyl ketone, 1-[9-ethyl-6-(2-methyl-4-tetrahydrofuranylmethoxybenzoyl)-9H-carbazole-3-yl]-, 1-(O-acetyl oxime), ethyl ketone, 1-[9-ethyl-6-{2-methyl-4 -(2,2-dimethyl-1,3-dioxacyclopentyl)methoxybenzyl}-9H-carbazole-3-yl〕-, 1-(O-acetyl oxime), "Optomer" (trademark registration) N-1919, NCI-831, NCI-930 (all manufactured by ADEKA), "IRGACURE" (trademark registration) OXE01, OXE02, OXE03 (all manufactured by BASF Japan), etc.

Examples of phenyl alkyl ketone compounds include 2,2-diethoxyacetophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone, α-hydroxyisobutylbenzene, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and "IRGACURE" (trademark registration) 907 (manufactured by BASF Japan Co., Ltd.).

Examples of benzophenone compounds include benzophenone, N,N'-tetraethyl-4,4'-diaminobenzophenone, and 4-methoxy-4'-dimethylaminobenzophenone.

Examples of thioxanthrone compounds include thioxanthrone, 2-chlorothioxanthrone, 2-methylthioxanthrone, 2-isopropylthioxanthrone, 4-isopropylthioxanthrone, 2,4-dimethylthioxanthrone, 2,4-diethylthioxanthrone, 2,4-diisopropylthioxanthrone, 1-chloro-4-propylthioxanthrone, and 1-hydroxycyclohexyl phenyl ketone.

Examples of imidazole compounds include 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer.

Examples of the benzothiazole-based compound include 2-nitrobenzothiazole and the like.

Examples of the benzoxazole-based compound include 2-nitrobenzoxazole and the like.

Examples of the acylphosphine oxide-based compound include 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzyl)-phenylphosphine oxide.

Examples of the titanium cyclopentadienyl compound include bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium and the like.

Among these, oxime ester compounds and alkyl phenone compounds are preferred from the viewpoint of further improving sensitivity. Among oxime ester compounds, "ADEKA ARKLS" (trademark registration) N-1919 is more preferred, and among alkyl phenone compounds, "IRGACURE" (trademark registration) 907 is more preferred.

The content of the photopolymerization initiator in the photosensitive resin composition of the present invention is preferably 2 to 30 parts by mass, more preferably 5 to 25 parts by mass, relative to 100 parts by mass of the total content of the alkali-soluble resin and the polymerizable monomer.

The polymerizable monomer in the present invention refers to a monomer having at least one ethylenically unsaturated bond. Examples of polymerizable monomers include monofunctional or polyfunctional monomers or oligomers. Two or more of these monomers may be contained. In addition, polyfunctional monomers are preferred in terms of increased crosslinking density and increased elastic recovery rate.

Examples of the multifunctional polymerizable monomer include tripropylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, triacryl formal, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol octa(meth)acrylate, and dipentaerythritol octa(meth)acrylate. (Meth)acrylate, 9,9-bis[4-(3-acryloyloxy-2-hydroxypropoxy)phenyl]fluorene, 9,9-bis[3-methyl-4-(3-acryloyloxy-2-hydroxypropoxy)phenyl]fluorene, 9,9-bis[3-chloro-4-(3-acryloyloxy-2-hydroxypropoxy)phenyl]fluorene, bisphenoxyethanolfluorene diacrylate, bisphenoxyethanolfluorene dimethacrylate, a reaction product of dipentaerythritol pentaacrylate and succinic anhydride, etc. Two or more of these may be contained.

Among these, a combination of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate or a reaction product of these with succinic anhydride is preferred from the viewpoint of easily adjusting the viscosity, exposure sensitivity and processability of the prebaked film to a desired range.

The photosensitive resin composition of the present invention may also contain fillers, sensitizing aids, ultraviolet absorbers, adhesion improvers, surfactants, polymerization inhibitors, polymer compounds other than the above-mentioned alkali-soluble resins, organic acids, organic amine compounds, curing agents and other additives or solvents.

The photosensitive resin composition of the present invention contains a filler, which can further increase the viscosity of the pre-baked film after drying and further suppress height deviation. As fillers, for example: inorganic oxide particles such as silica, alumina, titanium dioxide, and barium sulfate; metal particles; resin particles such as acrylic acid, styrene, silicone, and fluorine-containing polymers, etc. can be listed. Two or more of these can be contained. Among these, from the perspective of particle size and dispersibility, silica particles are preferred. The average particle size converted to the specific surface area of the filler is preferably 4 nm to 120 nm. If the average particle size of the filler is 4 nm or more, the height deviation can be further suppressed. On the other hand, if the particle size is 120 nm or less, the unevenness of the pattern surface can be suppressed and the surface shape of the pattern can be improved.

The photosensitive resin composition of the present invention contains a sensitizing agent, thereby improving the sensitivity. Examples of the sensitizing agent include aromatic or aliphatic tertiary amines.

The photosensitive resin composition of the present invention contains an ultraviolet absorber, thereby making it easy to form a highly transparent, fine and short optical spacer. From the perspective of transparency and non-coloring, the ultraviolet absorber is preferably an organic compound ultraviolet absorber such as a benzotriazole compound, a benzophenone compound, and a triazine compound. Two or more of these may be contained. Among these, a benzotriazole compound is preferred.

Examples of the benzotriazole compounds include 2-(2H-benzotriazole-2-yl)-p-cresol, 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-[5-chloro(2H)-benzotriazole-2-yl]-4-methyl-6-(tert-butylphenol), 2,4-di-tert-butyl-6-(5-chlorobenzotriazole-2-yl)phenol, 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-tert-amylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimide-methyl)-5-methylphenyl]benzotriazole, etc.

Examples of the benzophenone compounds include octabenzophenone and 2-hydroxy-4-n-octyloxybenzophenone.

Examples of the triazine compound include 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol.

The content of the ultraviolet absorber in the photosensitive resin composition of the present invention is preferably 0.3 mass % to 10 mass % in the solid component. By setting the content of the ultraviolet absorber to 0.3 mass % or more, the cone can be made shorter. The content of the ultraviolet absorber is more preferably 2 mass % or more. On the other hand, by setting the content of the ultraviolet absorber to 10 mass % or less, the sensitivity can be maintained high. The content of the ultraviolet absorber is more preferably 8 mass % or less. Furthermore, the so-called solid component refers to the components other than the solvent contained in the photosensitive resin composition.

Examples of the adhesion improver include vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri(2-methoxyethoxy)silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glyceryloxypropyltrimethoxysilane, 3-hydroxyglyceryl-1-propoxysilane, and 3-hydroxyethyl-1-propoxysilane. Silane coupling agents such as glyceryloxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-butylpropyltrimethoxysilane may be used. Two or more of these may be contained.

The content of the adhesion improver in the photosensitive resin composition of the present invention is preferably 0.1 mass % to 20 mass % in the solid component. By setting the content of the adhesion improver to 0.1 mass % or more, the developing adhesion can be improved. The content of the adhesion improver is more preferably 0.5 mass % or more. On the other hand, by setting the content of the adhesion improver to 20 mass % or less, the aggregation of the alkali-soluble resin or the polymerizable monomer can be suppressed. The content of the adhesion improver is more preferably 10 mass % or less.

Examples of surfactants include anionic surfactants such as ammonium lauryl sulfate and triethanolamine polyoxyethylene alkyl ether sulfate; cationic surfactants such as stearylamine acetate and lauryl trimethyl ammonium chloride; amphoteric surfactants such as lauryl dimethylamine oxide and lauryl carboxyl methyl hydroxyethyl imidazolium betaine; nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether and sorbitan monostearate; perfluorobutyl sulfonate and perfluoro-containing Fluorine-based surfactants such as alkyl carboxylates, perfluoroalkyl-containing trimethylammonium salts, perfluoroalkyl-containing phosphates, or perfluoroalkyl ethylene oxide adducts; silicone-based surfactants such as polyether-modified polymethylalkylsiloxane, polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, polyester-modified methylalkylpolysiloxane, aralkyl-modified polymethylalkylsiloxane, polyether-modified hydroxyl-containing polydimethylsiloxane, and polyester-modified hydroxyl-containing polydimethylsiloxane. Two or more of these may be contained. Among these, polyether-modified polydimethylsiloxane "BYK" (registered trademark) 333 (manufactured by BYK Chemical Co., Ltd.) is preferred.

The content of the surfactant in the photosensitive resin composition of the present invention is preferably 0.001 mass % to 10 mass % in the solid component. By setting the content of the surfactant to 0.001 mass % or more, the coating property of the photosensitive resin composition can be improved. The content of the surfactant is more preferably 0.01 mass % or more. On the other hand, by setting the content of the surfactant to 10 mass % or less, the unevenness of the pattern surface can be suppressed and the surface shape of the pattern can be improved. The content of the surfactant is more preferably 1 mass % or less.

Examples of the polymerization inhibitor include hydroquinone-based polymerization inhibitors such as hydroquinone, tert-butylhydroquinone, 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone, and 2,5-bis(1,1-dimethylbutyl)hydroquinone; and o-catechol-based polymerization inhibitors such as o-catechol and tert-butyl o-catechol. Two or more of these may be contained.

The content of the polymerization inhibitor in the photosensitive resin composition of the present invention is preferably 0.01 mass % to 0.5 mass % in the solid component. By setting the content of the polymerization inhibitor to 0.01 mass % or more, the storage stability of the photosensitive resin composition over time can be improved. On the other hand, by setting the content of the polymerization inhibitor to 0.5 mass % or less, the erosion or generation of scars on the film surface caused by the decrease in sensitivity during immersion in a polar solvent can be suppressed.

Examples of polymer compounds other than the alkali-soluble resins include acrylic resins, alkyd resins, melamine resins, polyvinyl alcohols, polyesters, polyethers, polyamides, polyamide imides, polyimides, and polyimide precursors that do not have structural units represented by general formulae (1) to (3). Two or more of these may be contained.

Examples of the solvent include ether solvents, ester solvents, alcohol solvents, ketone solvents, xylene, ethylbenzene, solvent naphtha, etc. Two or more of these may be contained.

Examples of the ether solvent include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol tertiary butyl ether, diethylene glycol methyl ethyl ether, and dipropylene glycol monomethyl ether. Among these, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and diethylene glycol methyl ethyl ether are preferred.

Examples of the ester solvent include benzyl acetate, ethyl benzoate, γ-butyrolactone, methyl benzoate, diethyl malonate, 2-ethylhexyl acetate, 2-butoxyethyl acetate, 3-methoxy-butyl acetate, 3-methoxy-3-methyl-butyl acetate, diethyl oxalate, ethyl acetylacetate, methyl acetylacetate, ethyl 3-ethoxypropionate, 2-ethylbutyl acetate, isoamyl propionate, propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether acetate, amyl acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol tertiary butyl ether, dipropylene glycol monomethyl ether acetate, ethyl acetate, butyl acetate, isoamyl acetate, etc. Among these, 3-methoxy-butyl acetate, propylene glycol monoethyl ether acetate, propylene glycol monomethyl ether propionate, etc. are preferred.

Examples of the alcohol solvent include butanol, 3-methyl-2-butanol, and 3-methyl-3-methoxybutanol.

Examples of the ketone solvent include cyclopentanone and cyclohexanone.

The photosensitive resin composition of the present invention is preferably applied so that the film thickness after curing becomes 3 μm, and after reduced pressure drying at 25°C and 45 Pa for 200 seconds, and then heat-dried in an oven at 105°C for 10 minutes, the viscosity at 23°C becomes 1×10 ³ Pa·s to 1×10 ⁸ Pa·s. By having such a viscosity, it can be preferably used in the manufacturing method of the optical spacer described below. Here, the viscosity at 23°C after drying refers to the viscosity at 23°C when a sample of 90 mm3 ^or more of the dried photosensitive resin composition is collected and measured using a rheometer (MCR-302; manufactured by Anton Paar Co., Ltd.) and a plate of f15 mm, with the temperature increased from 20°C to 110°C at a rate of 0.083°C/sec under the conditions of measuring thickness: 0.5 mm, frequency: 1 Hz, strain: 0.5%.

The photosensitive resin composition of the present invention is preferably formed into a conical optical spacer with an upper bottom surface diameter of 6 μm, a lower bottom surface diameter of 9 μm, and a height of 3 μm, and the elastic recovery rate when a load of 50 mN is applied is 70% or more. If the elastic recovery rate is 70% or more, the height deviation of the optical spacer during unit crimping can be further suppressed, and the display unevenness caused by the plastic deformation of the optical spacer can be further reduced. The elastic recovery rate is more preferably 73% or more. The closer the elastic recovery rate is to 100%, the more the influence on the unit gap caused by the deformation of the optical spacer and the display unevenness caused by it can be suppressed. The shape is a representative shape of a photospacer, and the load is an example of a load that the photospacer bears during manufacturing or use. According to the method, the difficulty of plastic deformation of a photosensitive resin composition used to form a photospacer can be relatively evaluated.

FIG1 is a schematic diagram showing an example of a hysteresis curve representing the elastic characteristics of an optical spacer. When a load is applied to an optical spacer, a hysteresis curve showing the load L applied to the optical spacer and the deformation D of the optical spacer as shown in FIG1 can be obtained. The total deformation Ha [μm], plastic deformation Hb [μm], and elastic deformation of the optical spacer can be obtained from the hysteresis curve, and the elastic recovery rate of the optical spacer (((Ha-Hb)/Ha)×100) can be calculated. Here, the hysteresis curve can be obtained as follows: using a Fischer hardness tester (Fischerscope H100; manufactured by Helmut Fischer GmbH & Co.) and a Φ50μm flat indenter, applying pressure at a rate of 2.5mN/sec until the load reaches 50mN, and then releasing it at a rate of 2.5mN/sec.

In order to set the elastic recovery rate when forming the photospacer to the above range, it is preferred to use the photosensitive resin composition of the present invention, and in particular, it is more preferred to use a photosensitive resin composition having an ethylene unsaturated group equivalent within the above preferred range.

The photosensitive resin composition of the present invention can be obtained by mixing an alkali-soluble resin, a photopolymerization initiator, a polymerizable monomer, and other additives such as a surfactant, a polymerization inhibitor, a solvent, and an ultraviolet absorber in any proportion.

The photosensitive resin composition of the present invention can suppress height deviation, and therefore can be preferably used for exposure by lens scanning, and can be more preferably used for forming photospacers by lens scanning exposure.

In order to achieve high precision of the color filter, the shape of the optical spacer is preferably a cone shape, and the diameter of the upper base is preferably less than 15 μm. In addition, the ratio of the diameter of the upper base to the diameter of the lower base (upper base/lower base) is preferably 0.3 to 2.0.

Next, the method for manufacturing the optical spacer of the present invention is described by taking the case of forming on a substrate as an example. Preferably, the photosensitive resin composition of the present invention is coated on a substrate, dried to obtain a pre-baked film, and the pre-baked film is subjected to lens scanning, exposure and development to form the optical spacer. Preferably, the coated film pattern after development is further heated to harden it.

As the substrate, there can be mentioned transparent substrates such as glass and polymer films.

Examples of the method for applying the photosensitive resin composition include a dipping method, a roll coater method, a spinner method, a die coating method, and a wire rod coating method.

As drying methods, reduced pressure drying, heating drying (pre-baking) using an oven or a heating plate, etc. can be listed. In the case of reduced pressure drying, from the viewpoint of suppressing the re-condensation of the drying solvent on the inner wall of the reduced pressure chamber, the heating temperature is preferably below 100°C. The reduced pressure drying pressure is preferably below the vapor pressure of the solvent contained in the photosensitive resin composition, and is preferably 1 Pa to 1000 Pa. The reduced pressure drying time is preferably 10 seconds to 600 seconds. In the case of pre-baking, the heating temperature is generally 60°C to 200°C, and the heating time is 1 minute to 60 minutes.

In the present invention, the viscosity of the prebaked film at 23°C is preferably 1×10 ³ Pa·s to 1×10 ⁸ Pa·s. By exposing a prebaked film having a viscosity of 1×10 ³ Pa·s or more at 23°C, the fluidity of the prebaked film can be appropriately suppressed, and the generation of unevenness in the conveying step or exposure step and heat drying (post-baking) step of the prebaked film can be further suppressed. The viscosity at 23°C is more preferably 1×10 ⁵ Pa·s or more. On the other hand, by exposing a prebaked film having a viscosity of 1×10 ⁸ Pa·s or less at 23°C, the developability can be improved. Here, the viscosity of the pre-baked film at 23°C refers to the viscosity at 23°C when a pre-baked film of 90 mm3 ^or more is collected and measured using a rheometer (MCR-302; manufactured by Anton Paar Co., Ltd.) and a plate of f15 mm, and the temperature is raised from 20°C to 110°C at a rate of 0.083°C/sec under the conditions of measuring thickness: 0.5 mm, frequency: 1 Hz, and strain: 0.5%. Furthermore, in the manufacturing step of the optical spacer on the color filter substrate, the temperature of the pre-baked film is generally heated to about 100°C in the drying step, but becomes about room temperature (about 23°C) by cooling before exposure. Therefore, the present invention focuses on the viscosity at 23°C, which is the general temperature of the pre-baked film during exposure.

Preferably, the obtained pre-baked film interlayer mask is exposed to light to harden the exposed portion, and then developed with an alkaline developer to remove the unexposed portion to form a pattern.

Examples of exposure methods include close-up exposure, lens scanning exposure, mirror projection exposure, and step exposure. In the present invention, lens scanning exposure, which is excellent in high-precision pattern processing for large substrates, can be preferably used. The photosensitive resin composition of the present invention can suppress height deviation, so it can be preferably used for lens scanning exposure that is prone to height deviation. Examples of lens scanning exposure devices include FX-65S (manufactured by Nikon Corporation).

The developing step is preferably developed using an alkaline developer. Examples of the alkaline developer include organic alkaline developers, inorganic alkaline developers, and the like. The inorganic alkaline developer is preferably an aqueous solution of sodium carbonate, sodium hydroxide, potassium hydroxide, and the like. The organic alkaline developer is preferably an aqueous solution of tetramethylammonium hydroxide, methanolamine, and other amine-based aqueous solutions. From the viewpoint of the development solubility of the unexposed portion, the content of the alkaline substance in the alkaline developer is preferably 0.02% by mass or more. On the other hand, from the viewpoint of further improving the processability of the pattern of the exposed portion, it is preferably 2.0% by mass or less. In order to improve the uniformity of the development, the developer preferably contains a surfactant. The developing speed varies according to the temperature of the developer, so the developer temperature is preferably selected within the range of 18°C to 40°C.

As developing methods, for example, immersion developing, spray developing, and liquid coating developing can be listed. It is preferable to appropriately select the temperature, flow rate, and spraying pressure of the developer, and the temperature, flow rate, and spraying pressure of the water washing after developing. In order to remove the residue on the substrate, it is preferable to spray the developer or the washing water under high pressure, and the spraying pressure is preferably 0.01 MPa to 20 MPa.

As a heat treatment device for the developed coating film pattern, there can be listed a hot air oven, a heating plate, etc. The heating temperature is preferably 180°C to 300°C, and the heating time is preferably 5 minutes to 90 minutes.

Next, a color filter substrate and a liquid crystal display device having the optical spacer of the present invention are described.

The color filter substrate has the light spacer and pixels of the present invention on the substrate, and may also have a black matrix, a planarization film, a transparent electrode, an alignment film, etc. as needed.

As the color filter substrate, there can be exemplified a substrate for forming an optical spacer.

Examples of the pixel include red pixel, green pixel, blue pixel, etc. The pixel may contain a colorant, a resin, a polymerizable monomer, a photopolymerization initiator, other additives, etc., and may be formed by a cured product containing one or more of these compositions. Examples of the colorant include organic pigments, inorganic pigments, and dyes. Examples of the resin, the polymerizable monomer, the photopolymerization initiator, and other additives include those exemplified as components of the transparent photosensitive resin composition of the present invention.

Examples of pixel shapes include rectangles, stripes, squares, polygons, and waves. From the perspective of increasing the area of the opening and improving transmittance, the pixel width is preferably 1 μm or more. On the other hand, from the perspective of displaying a denser image, the pixel width is preferably 100 μm or less. The film thickness of the pixel is preferably about 1 μm to 5 μm.

It is preferred to have a black matrix (hereinafter referred to as "BM (black matrix)") between adjacent pixels. BM has the function of improving the contrast of the displayed image by shading the pixels. BM can be a color overlapping BM formed by overlapping a part of adjacent pixels, but in order to suppress the step difference of the pixels to further improve the displayed image and obtain high light-shielding properties, it is preferred to contain a resin and a light-shielding material. The resin is preferably a polyimide resin or an acrylic resin. Examples of light-shielding materials include: titanium black, titanium nitride, titanium carbide, carbon black, etc. It may further contain a close contact improver, a polymer dispersant, a polymerization initiator, an acid generator, a base generator, a surfactant, etc.

From the viewpoint of improving light shielding property and resistance value, the film thickness of BM is preferably 0.5 μm or more, more preferably 0.8 μm or more. On the other hand, from the viewpoint of improving flatness, the film thickness of BM is preferably 2.5 μm or less, more preferably 2.0 μm or less.

When the color filter substrate having pixels or BM has a step, it is preferred to have a planarization film. The planarization film may be formed on the entire surface of the pixel or BM, or may be selectively formed on a portion to be planarized. When the planarization film is formed on the entire surface of the pixel or BM, the planarization film is preferably a cured product containing a thermosetting resin composition, and when the planarization film is selectively formed, the planarization film is preferably a cured product containing a photosensitive resin composition.

The planarizing film preferably contains a resin, and may further contain a contact improver, a polymer dispersant, a polymerization initiator, an acid generator, a base generator, a surfactant, and the like.

From the viewpoint of flatness and suppression of elution of impurities from pixels, the thickness of the planarization film is preferably 0.5 μm or more, more preferably 1.0 μm or more. On the other hand, from the viewpoint of improving transparency, the thickness of the planarization film is preferably 3.0 μm or less, more preferably 2.0 μm or less.

The color filter substrate of the present invention can be obtained by forming the optical spacer and pixel of the present invention on a substrate, and optionally forming a black matrix or a planarization film. Examples of methods for forming the pixel or black matrix or the planarization film include photolithography, printing, and electro-deposition.

The liquid crystal display device of the present invention preferably has the color filter substrate, a driving element side substrate arranged opposite to the color filter substrate, liquid crystal alignment films respectively arranged on the color filter substrate and the driving element side substrate, optical spacers that uniformly maintain the unit gaps between the liquid crystal alignment films, and liquid crystal filled in the space. For example, when a color filter substrate having a black matrix is used, it is preferred to have an optical spacer in the non-display area, i.e., above the black matrix. Furthermore, an optical spacer may be provided on the driving element side substrate, in which case it is also preferred to have an optical spacer above the non-display area on the driving element side substrate. The liquid crystal alignment film is preferably a resin film such as polyimide.

Next, a method for manufacturing a liquid crystal display device using the color filter substrate is described. It is preferred to have a step of manufacturing an optical spacer on the color filter substrate and/or the driver element side substrate by the manufacturing method. Specifically, it is preferred to make the color filter substrate and the driver element side substrate face each other and bond them together via the optical spacer, inject liquid crystal from an injection port provided in the sealing portion, seal the injection port, and finally install an IC driver, etc. In the case where the liquid crystal display device has a liquid crystal alignment film, it is preferred to perform surface treatment by friction treatment or ultraviolet treatment after coating and heat treatment of the polyimide liquid. From the perspective of suppressing the generation of fine dust or static electricity and aligning the liquid crystal molecules uniformly and with high precision, it is preferable to perform surface treatment by ultraviolet treatment. [Example]

Hereinafter, the present invention will be described in detail with reference to embodiments and comparative examples, but the implementation of the present invention is not limited thereto.

The properties of alkali-soluble resins are evaluated by the following methods.

(Weight average molecular weight) For the alkali-soluble resins 1 to alkali-soluble resins 13 obtained in Production Examples 1 to 13, the values converted to standard polystyrene were determined by gel permeation chromatography.

(Ethylene unsaturated group equivalent) For the alkali-soluble resins 1 to 13 obtained in Production Examples 1 to 13, the iodine value was measured by the method described in Item 6.0 of the test method of JIS K 0070:1992 to calculate the ethylenic unsaturated group equivalent.

(Acid value) 5 g of the solution of alkali-soluble resin 1 to alkali-soluble resin 13 obtained by Production Example 1 to Production Example 13 was placed in an aluminum cup (f45 mm) and heated at 130°C for 1 hour to remove the solvent. The acid value of the obtained alkali-soluble resin was measured by the neutralization titration method in Item 3.1 of the test method of JIS K 0070:1992.

(Residual amount of (meth)acrylate glycidyl ester) The solution of alkali-soluble resin 1 to alkali-soluble resin 13 obtained by Production Example 1 to Production Example 13 was subjected to gas chromatography using GCMS-GP2010 manufactured by Shimadzu Corporation, DM-5MS as a column, He as a carrier gas, and the column temperature was maintained at 80°C for 4 minutes, then raised to 320°C over 16 minutes and maintained at 320°C for 5 minutes to measure the amount of (meth)acrylate glycidyl ester.

The solutions of alkali-soluble resins 1 to alkali-soluble resins 13 obtained in Production Examples 1 to 13 were heated at 130° C. for 1 hour, and the solid content concentrations were calculated from the masses before and after heating. The residual amount of glycidyl (meth)acrylate (residual GMA amount (mass %)) was calculated from the amount of glycidyl (meth)acrylate and the solid content concentration of the solutions of the alkali-soluble resins.

Preparation Example 1 (alkali-soluble resin 1) 72 g of methacrylic acid (MA), 40 g of N-cyclohexylmaleimide (CHMI), 30 g of methyl methacrylate (MMA), 3 g of 2,2'-azobis(2-methylbutyronitrile), 0.5 g of lauryl mercaptan and 220 g of propylene glycol monomethyl ether (PGME) were added to a polymerization container, stirred at 90°C for 2 hours under a nitrogen atmosphere, and then the liquid temperature was raised to 100°C and heated and stirred for 5 hours to react. Next, the air in the polymerization container was replaced, and 97 g of glycidyl methacrylate (GMA), 1.2 g of dimethylbenzylamine, and 0.2 g of p-methoxyphenol were added to the obtained reaction solution, and after stirring at 110°C for 6 hours, PGME was added to obtain a solution of alkali-soluble resin 1 having a solid content concentration of 29.5% by mass. The obtained alkali-soluble resin 1 had an Mw of 40,000, an ethylene unsaturated group equivalent of 350 g/mol, an acid value of 85 mgKOH/g, and a residual GMA content of 0.05% by mass. In the alkali-soluble resin 1, MA constitutes the structural unit represented by the general formula (1), GMA constitutes the structural unit represented by the general formula (2), and CHMI constitutes the structural unit represented by the general formula (3).

Production Example 2 (Alkali-soluble resin 2) The same method as Production Example 1 was followed except that the amount of MA, CHMI, MMA, and GMA were changed to 69 g, 25 g, 18 g, and 98 g, to obtain a solution of alkali-soluble resin 2 having a solid content concentration of 28.3% by mass. The obtained alkali-soluble resin 2 had an Mw of 43,000, an ethylene unsaturated group equivalent of 300 g/mol, an acid value of 63 mgKOH/g, and a residual GMA content of 0.05% by mass.

Production Example 3 (Alkali-soluble Resin 3) The same method as Production Example 1 was followed except that the amount of MA and GMA was changed to 32 g and 31 g, to obtain a solution of Alkali-soluble Resin 3 having a solid content concentration of 28.5% by mass. The obtained Alkali-soluble Resin 3 had an Mw of 39,000, an ethylene unsaturated group equivalent of 600 g/mol, an acid value of 85 mgKOH/g, and a residual GMA content of 0.05% by mass.

Production Example 4 (Alkali-soluble Resin 4) The same method as Production Example 1 was followed except that the amount of lauryl mercaptan was changed to 2.2 g to obtain a solution of Alkali-soluble Resin 4 having a solid content concentration of 31.8 mass %. The obtained Alkali-soluble Resin 4 had an Mw of 9,000, an ethylene unsaturated group equivalent of 350 g/mol, an acid value of 85 mgKOH/g, and a residual GMA content of 0.05 mass %.

Production Example 5 (Alkali-soluble Resin 5) The same method as Production Example 1 was followed except that the amount of MA, CHMI and GMA was changed to 66 g, 50 g and 96 g, to obtain a solution of Alkali-soluble Resin 5 having a solid content concentration of 31.0 mass %. The obtained Alkali-soluble Resin 5 had an Mw of 38,000, an ethylene unsaturated group equivalent of 350 g/mol, an acid value of 50 mgKOH/g, and a residual GMA content of 0.05 mass %.

Production Example 6 (Alkali-soluble Resin 6) The same method as Production Example 1 was followed except that the amount of MA, CHMI, MMA, and GMA were changed to 59 g, 28 g, 19 g, and 70 g, to obtain a solution of Alkali-soluble Resin 6 having a solid content concentration of 30.4% by mass. The obtained Alkali-soluble Resin 6 had an Mw of 35,000, an ethylene unsaturated group equivalent of 350 g/mol, an acid value of 110 mgKOH/g, and a residual GMA content of 0.05% by mass.

Preparation Example 7 (Alkali-soluble resin 7) 13 g of methacrylic acid (MA), 15 g of N-cyclohexylmaleimide (CHMI), 72 g of methyl methacrylate (MMA), 3 g of 2,2'-azobis(2-methylbutyronitrile), 0.5 g of lauryl mercaptan and 220 g of propylene glycol monomethyl ether (PGME) were placed in a polymerization container, stirred at 90°C for 2 hours under a nitrogen atmosphere, and then the liquid temperature was raised to 100°C and heated and stirred for 5 hours to react. 0.2 g of p-methoxyphenol was added, and after cooling to room temperature, PGME was added to obtain a solution of alkali-soluble resin 7 with a solid content concentration of 29.1 mass %. The obtained alkali-soluble resin 7 had a Mw of 37,000 and an acid value of 85 mgKOH/g.

Production Example 8 (Production of Alkali-soluble Resin 8) The same procedures as in Production Example 1 were followed except that the blending amounts of MA, MMA, and GMA were changed to 70 g, 12 g, and 98 g, and 15 g of styrene (St) was used instead of CHMI to obtain a solution of Alkali-soluble Resin 8 having a solid content concentration of 29.2% by mass. The obtained Alkali-soluble Resin 8 had an Mw of 35,000, an ethylene unsaturated group equivalent of 285 g/mol, an acid value of 67 mgKOH/g, and a residual GMA content of 0.05% by mass.

Preparation Example 9 (Alkali-soluble Resin 9) A solution of Alkali-soluble Resin 9 having a solid content of 29.5% by mass was obtained in the same manner as Preparation Example 1 except that 40 g of N-benzylmaleimide (BzMI) was used instead of CHMI. The obtained Alkali-soluble Resin 9 had an Mw of 40,000, an ethylene unsaturated group equivalent of 350 g/mol, an acid value of 64 mgKOH/g, and a residual GMA content of 0.05% by mass.

Preparation Example 10 (Preparation of Alkali-soluble Resin 10) A solution of Alkali-soluble Resin 10 having a solid content concentration of 29.5% by mass was obtained in the same manner as Preparation Example 1 except that 60 g of acrylic acid (AA) was used instead of MA. The obtained Alkali-soluble Resin 10 had an Mw of 40,000, an ethylene unsaturated group equivalent of 350 g/mol, an acid value of 62 mgKOH/g, and a residual GMA content of 0.05% by mass.

Production Example 11 (Alkali-soluble resin 11) The same procedures as in Production Example 1 were followed except that the stirring time at 110°C was changed to 8 hours, thereby obtaining a solution of alkali-soluble resin 11 having a solid content concentration of 29.5 mass %. The obtained alkali-soluble resin 11 had an Mw of 40,000, an ethylene unsaturated group equivalent of 350 g/mol, an acid value of 64 mgKOH/g, and a residual GMA content of 0.02 mass %.

Production Example 12 (Alkali-soluble resin 12) The same procedures as in Production Example 1 were followed except that the stirring time at 110°C was changed to 5 hours to obtain a solution of alkali-soluble resin 12. The obtained alkali-soluble resin 12 had an Mw of 40,000, an ethylene unsaturated group equivalent of 350 g/mol, an acid value of 64 mgKOH/g, and a residual GMA content of 0.30 mass %.

Production Example 13 (Alkali-soluble resin 13) The same method as Production Example 1 was followed except that the amount of MA, CHMI, MMA, and GMA were changed to 50 g, 30 g, 0 g, and 65 g, to obtain a solution of alkali-soluble resin 13 having a solid content concentration of 28.5% by mass. The obtained alkali-soluble resin 13 had an Mw of 36,000, an ethylene unsaturated group equivalent of 278 g/mol, an acid value of 93 mgKOH/g, and a residual GMA content of 0.05% by mass.

The compositions and evaluation results of Production Examples 1 to 13 are shown in Tables 1 and 2.

[Table 1]

[Table 2]

(Preparation of a substrate with a black matrix) A 1.0 μm thick black matrix composed of a composition containing a polyimide resin and carbon black was formed on the surface of an alkali-free glass substrate (OA-10; manufactured by Nippon Electric Glass Co., Ltd.; 50 mm×70 mm, thickness 0.7 mm) to prepare a substrate with a black matrix.

(Preparation of a substrate with a planarization film) The substrate with a black matrix prepared by the above method was exposed for 60 seconds using a UV/ozone device (SSP16-110; manufactured by SEN Special Light Source Co., Ltd.) to perform cleaning treatment, and then a planarization film material (NN901; manufactured by JSR Co., Ltd.) was applied and dried by spin coating to form a 1.5 μm thick transparent planarization film. It was heat-dried (pre-baked) at 90°C for 10 minutes and irradiated with ultraviolet light until the exposure reached saturation. Next, a 23°C aqueous solution containing 0.1% by mass of tetramethylammonium hydroxide (hereinafter referred to as "TMAH (tetramethyl ammonium hydroxide)") and 0.3% by mass of "Emulgen" (registered trademark) A-60 (hereinafter referred to as "A-60"; manufactured by Kao Corporation) was used for spray development, and then the unexposed portion of the planarization film was rinsed off by water washing. After that, heat drying (post-baking) was performed at 230°C for 30 minutes to prepare a substrate with a planarization film.

The evaluation in the embodiments and comparative examples was performed using the following method.

(Transparency of photosensitive resin composition) The photosensitive resin composition prepared in each embodiment and comparative example was applied on the surface of an alkali-free glass substrate (OA-10; manufactured by Nippon Electric Glass Co., Ltd.; 50 mm×70 mm, thickness 0.7 mm) using a spin coater (1HD2 model) manufactured by Mikasa Co., Ltd. After reduced pressure drying for 200 seconds at a temperature of 25°C and a pressure of 45 Pa, it was heated and dried (pre-baked) for 10 minutes in an oven set at 105°C (PERFECTOVEN PV-210; manufactured by Tabai Espec Co., Ltd.) to prepare a pre-baked film. The substrate with the planarized film formed with the pre-baked film was cooled to room temperature, and then exposed to ultraviolet rays of wavelengths including i-ray: 365 nm, h-ray: 405 nm, and g-ray: 436 nm at an exposure dose of 24 mJ/cm ² (i-ray conversion) using an ultraviolet exposure machine (PEM-6M; manufactured by Union Optical Co., Ltd., collimation angle θ: 2°, i-ray (365 nm) illuminance: 30 mW/cm ² ) equipped with a glass UV filter (UV-35; manufactured by Asahi Techno Glass Co., Ltd.) without using a negative mask.

Next, a 23°C aqueous solution containing 0.3% by mass of TMAH and 0.3% by mass of A-60 was used as a developer, and spray development was performed using an automatic developer (AD-2000; manufactured by Mikasa Co., Ltd.), followed by water washing and air drying. Next, heat drying (post-baking) was performed in an oven at 230°C for 30 minutes to prepare a substrate with a 3.00 μm thick photospacer film on the entire surface.

The light transmittance at a wavelength of 400 nm to 700 nm was measured at the center of the substrate with the photospacer film on the entire surface using a microspectrophotometer (LCF-100MA: manufactured by Otsuka Electronics Co., Ltd.) under light source C, and the transparency of the photosensitive resin composition was evaluated according to the following criteria. A was considered acceptable. A: The light transmittance at a wavelength of 400 nm to 700 nm was 80% or more. B: The light transmittance at a wavelength of 400 nm to 700 nm was less than 80%.

(Viscosity of pre-baked film) As a sample for reproducing the viscosity characteristics of the pre-baked film obtained by Examples 1 to 13 and Comparative Examples 1 to 3, a pre-baked film was prepared on an alkali-free glass substrate (OA-10; manufactured by Nippon Electric Glass Co., Ltd.; 50 mm×70 mm, thickness 0.7 mm) according to the conditions of each Example and Comparative Example. For the obtained pre-baked film, ^more than 90 mm3 was collected with a scraper, and the temperature was raised from 20°C to 110°C at a heating rate of 0.083°C/sec under the conditions of measuring thickness: 0.5 mm, frequency: 1 Hz, strain: 0.5%, and the viscosity at 23°C was measured.

(Surface shape of optical spacer) The conical pattern optical spacers formed in Examples 1 to 13 and Comparative Examples 1 to 3 were observed using FE-SEM (S-4800; manufactured by Hitachi High-Technologies Co., Ltd.) at a magnification of 7,000 times, and the surface shape of the optical spacers was evaluated according to the following criteria. A was considered acceptable. B: Concavities and convexities were observed. A: Concavities and convexities were not observed.

(Elastic recovery rate of optical spacer) For the conical pattern optical spacers formed in Examples 1 to 13 and Comparative Examples 1 to 3, a Fischer hardness tester (Fischerscope H100; manufactured by Helmut Fischer GmbH & Co.) and a flat punch of f50 μm were used to apply pressure at a rate of 2.5 mN/sec until the load reached 50 mN and maintained for 5 seconds, then released at a rate of 2.5 mN/sec until the load reached 0 mN and maintained for 5 seconds, to produce the hysteresis curve at that time. The total deformation Ha [μm] and plastic deformation Hb [μm] are obtained from the obtained hysteresis curve, and the elastic recovery rate of the optical spacer is calculated ((Ha-Hb/Ha) × 100). The average value of the measured values at 5 locations is calculated and evaluated according to the following criteria. AA, A, and B are considered acceptable. C: The elastic recovery rate is less than 70% B: The elastic recovery rate is 70% or more and less than 72% A: The elastic recovery rate is 72% or more and less than 73% AA: The elastic recovery rate is 73% or more.

(Evaluation of height deviation of optical spacers by lens scanning exposure) In Examples 1 to 13 and Comparative Examples 1 to 3, in the conical cone-shaped pattern optical spacers formed by lens scanning exposure, 20 optical spacers were selected at a certain interval in a direction orthogonal to the direction in which the multiple lenses were arranged in two rows in a 20 mm square range on the substrate surface corresponding to the joint between the lenses, and the height deviation (maximum height - minimum height) was measured using a step measuring device. The height deviation of the optical spacers was evaluated according to the following criteria. A and B were set as qualified. C: Height deviation is 0.04 μm or more B: Height deviation is 0.02 μm or more and less than 0.04 μm A: Height deviation is less than 0.02 μm.

(Evaluation of defects in optical spacers exposed by lens scanning) Use a microscope to magnify and observe 10,000 of the pyramidal pattern optical spacers formed in Example 1 to Example 13 and Comparative Example 1 to Comparative Example 3, and determine whether there are defects. The number of pyramidal pattern optical spacers with defects confirmed is evaluated according to the following criteria. AA, A, and B are considered acceptable. C: There are 11 or more defects in the optical spacer B: There are 6 to 10 defects in the optical spacer A: There are 1 to 5 defects in the optical spacer AA: There are 0 defects in the optical spacer.

(Evaluation of height deviation of photospacers formed by multi-patterning by proximity exposure) For the conical-shaped patterned photospacers formed by multi-patterning by proximity exposure in Examples 1 to 13 and Comparative Examples 1 to 3, the height deviation (maximum height - minimum height) of the photospacers formed in the initial exposure and the height of the photospacers formed in the subsequent exposure was measured using a step difference meter, and the height deviation of the photospacers was evaluated according to the following criteria. A and B were considered acceptable. C: Height deviation of 0.20 μm or more B: Height deviation of 0.10 μm or more and less than 0.20 μm A: Height deviation less than 0.10 μm.

(Example 1) (Preparation of photosensitive resin composition 1) The solution of alkali-soluble resin 1 with a solid content concentration of 29.5% by mass obtained by manufacturing example 1: 21.13 parts by mass, dipentaerythritol pentaacrylate ("KAYARAD" (registered trademark) DPHA; Nippon Kayaku; hereinafter referred to as "DPHA") (ethylene unsaturated group equivalent to 100): 11.58 parts by mass, photopolymerization initiator ("ADEKA ARKLS" (registered trademark) N-1919; hereinafter referred to as "N1919"): 0.36 parts by mass, "IRGACURE" (registered trademark) 907 (BASF Japan) Japan) (manufactured by the company); hereinafter referred to as "IC907": 0.89 parts by mass, 2,4-diethylthioxanthenone ("KAYACURE" (registered trademark) DETX-S; manufactured by Nippon Kayaku Co., Ltd.; hereinafter referred to as "DETX"): 0.89 parts by mass, surfactant "BYK" (registered trademark) -333 (BYK Chemie The reaction mixture was stirred at room temperature to obtain a photosensitive resin composition 1.

The substrate with the planarized film obtained by the above method was exposed to light for 60 seconds using a UV/ozone device (SSP16-110; manufactured by SEN Special Light Source Co., Ltd.) for cleaning, and then coated with the photosensitive resin composition 1 using a spin coater (1HD2 type; manufactured by Mikasa Co., Ltd.). After reduced pressure drying for 200 seconds at a temperature of 25°C and a pressure of 45 Pa, it was heated and dried (pre-baked) in an oven set at 105°C for 10 minutes, and then cooled to room temperature to form a pre-baked film.

Next, the substrate with the planarized film formed on which the pre-baked film was formed was exposed to ultraviolet light of wavelengths including i-ray: 365 nm, h-ray: 405 nm, and g-ray: 436 nm at an exposure dose of 30 mJ/ ^cm2 (i-ray conversion) using an FX-65S (Nikon Co., Ltd.) as a lens scanning exposure device through a circular mask with a diameter of 7 μm.

Next, a 23°C aqueous solution containing 0.3% by mass of TMAH and 0.3% by mass of A-60 was used as a developer, and spray development was performed using an automatic developer (AD-2000; manufactured by Mikasa Co., Ltd.), followed by water washing and air drying. Finally, heat drying (post-baking) was performed in an oven at 230°C for 30 minutes to produce an optical spacer with a top base of 6 μm, a bottom base of 9 μm, and a height of 3 μm.

In addition, for the substrate with the planarized film formed with the pre-baked film, the first exposure was performed using a UV exposure machine (PEM-6M; manufactured by Union Optical; collimation angle θ = 2°, i-ray (365 nm) illuminance = 30 mW/cm ² ) equipped with a glass UV filter (UV-35; manufactured by Asahi Techno Glass Co., Ltd.), using ultraviolet rays of wavelengths including i-ray: 365 nm, h-ray: 405 nm, and g-ray: 436 nm as irradiation light via a negative mask in which circular patterns with a diameter of 10 μm are arranged at a pitch of 15 μm. Then, the next exposure was performed by shifting the negative mask by only half the pitch (proximity exposure multi-patterning).

Next, a 23°C aqueous solution containing 0.3% by mass of TMAH and 0.3% by mass of A-60 was used as a developer, and spray development was performed using an automatic developer (AD-2000; manufactured by Mikasa Co., Ltd.), followed by water washing and air drying. Finally, heat drying (post-baking) was performed in an oven at 230°C for 30 minutes to produce an optical spacer with a top base of 6 μm, a bottom base of 9 μm, and a height of 3 μm.

(Example 2 to Example 13, Comparative Example 1 to Comparative Example 3) The photosensitive resin composition, pre-baked film and photo spacer were prepared in the same manner as in Example 1 except that the composition of the photosensitive resin composition was changed as shown in Table 2. The results of the evaluations in the same manner as in Example 1 are shown in Tables 3 to 5.

[table 3]

[Table 4]

[table 5]

Furthermore, "M520" in Tables 3 to 5 represents the reaction product of a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate and succinic anhydride (M520; manufactured by Toa Gosei Co., Ltd.; ethylene unsaturated group equivalent weight is 104 g/mol). [Industrial Availability]

The transparent photosensitive resin composition of the present invention can be preferably used as a material for forming a photospacer of a liquid crystal display device by lens scanning exposure.

L‧‧‧Load D‧‧‧Deformation Ha‧‧‧Total deformation Hb‧‧‧Plastic deformation

FIG. 1 is a schematic diagram showing an example of a hysteresis curve indicating the elastic characteristics of an optical spacer.

L‧‧‧Load

D‧‧‧Deformation

Ha‧‧‧Total deformation

Hb‧‧‧Plastic deformation

Claims (18)

A transparent photosensitive resin composition comprises at least an alkali-soluble resin, a photopolymerization initiator and a polymerizable monomer, wherein the alkali-soluble resin has: A) a structural unit represented by the following general formula (1), B) a structural unit represented by the following general formula (2), and C) a structural unit represented by the following general formula (3), wherein the alkali-soluble resin has an ethylene unsaturated group equivalent of 400 g/mol or less,

In the general formula (1), ^R1 represents a hydrogen atom or a methyl group,

In the general formula (2), ^R2 and ^R3 each independently represent _a hydrogen atom or a methyl group; X represents _-CH2CH (OH) _CH2O (C=O)-, -CH2CH2NH(C=O)O( _CH2 ) _mO (C=O)- or -( _CH2 ) _nO (C=O _{) NHCH2CH2O} (C=O)-; wherein m and n each independently represent an integer of ₁ to 4,

In the general formula (3), Y represents an aryl group having 6 to 11 carbon atoms which may have a substituent, an aralkyl group having 7 to 10 carbon atoms which may have a substituent, or a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, and the alkali-soluble resin is obtained by adding glycidyl (meth)acrylate to (meth)acrylic acid, wherein the solid content of the residual glycidyl (meth)acrylate in the alkali-soluble resin is 0.001 mass % to 0.500 mass %. The transparent photosensitive resin composition as described in Item 1 of the patent application, wherein in the general formula (3), Y is a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent. A transparent photosensitive resin composition as described in item 1 or 2 of the patent application, wherein in the general formula (3), Y is a cyclohexyl group. The transparent photosensitive resin composition as described in item 1 or 2 of the patent application, wherein in the general formula (1), R ¹ is a methyl group. A transparent photosensitive resin composition as described in item 1 or 2 of the patent application, wherein the amount of the structural unit represented by the general formula (3) when the total amount of the structural units of the alkali-soluble resin is set to 100 mol% is 10 mol% to 23 mol%. A transparent photosensitive resin composition as described in item 1 or 2 of the patent application, wherein the weight average molecular weight of the alkali-soluble resin is 10,000 to 100,000. A transparent photosensitive resin composition as described in item 1 or 2 of the patent application, wherein the acid value of the alkali-soluble resin is 60 mgKOH/g~100 mgKOH/g. The transparent photosensitive resin composition described in item 1 or 2 of the patent application contains 34 to 66 parts by mass of the alkali-soluble resin relative to 100 parts by mass of the polymerizable monomer. The transparent photosensitive resin composition as described in item 1 or 2 of the patent application scope is applied in a manner that the film thickness becomes 3 μm after curing, and after reduced pressure drying at 25°C and 45 Pa for 200 seconds, and after heat drying in an oven at 105°C for 10 minutes, the viscosity at 23°C becomes 1×10 ³ Pa. s~1×10 ⁸ Pa. s. The transparent photosensitive resin composition as described in item 1 or 2 of the patent application scope forms a conical optical spacer with an upper bottom diameter of 6μm, a lower bottom diameter of 9μm, and a height of 3μm, and the elastic recovery rate when a load of 50mN is applied becomes more than 70%. A transparent photosensitive resin composition as described in item 1 or 2 of the patent application scope, which is used for lens scanning exposure. The transparent photosensitive resin composition as described in item 1 or 2 of the patent application scope is used to stagger a plate and perform multiple exposures to form multiple patterns. A photospacer using a cured product of a transparent photosensitive resin composition as described in any one of items 1 to 12 of the patent application scope. A liquid crystal display device using the optical spacer as described in item 13 of the patent application scope. A method for manufacturing a photospacer, which comprises applying a transparent photosensitive resin composition as described in any one of items 1 to 12 of the patent application scope on a substrate, drying to obtain a pre-baked film, and performing lens scanning, exposure and development on the pre-baked film to form a photospacer. The method for manufacturing a photo spacer as described in claim 15, wherein the viscosity of the pre-baked film at 23° C. is 1×10 ³ Pa. s to 1×10 ⁸ Pa. s. A method for manufacturing a liquid crystal display device, which is to make a color filter substrate and a driving element side substrate face each other and seal a liquid crystal compound between the two, and the method for manufacturing a liquid crystal display device has a step of manufacturing an optical spacer on the color filter substrate and/or the driving element side substrate by the manufacturing method described in item 15 or 16 of the patent application scope. A transparent photosensitive resin composition is used in lens scanning exposure, wherein the transparent photosensitive resin composition contains at least an alkali-soluble resin, a photopolymerization initiator and a polymerizable monomer, and the alkali-soluble resin has: A) a structural unit represented by the following general formula (1), B) a structural unit represented by the following general formula (2), and C) a structural unit represented by the following general formula (3), and the alkali-soluble resin has an ethylene unsaturated group equivalent of 400 g/mol or less.

In the general formula (1), ^R1 represents a hydrogen atom or a methyl group,

In the general formula (2), ^R2 and ^R3 each independently represent _a hydrogen atom or a methyl group; X represents _-CH2CH (OH) _CH2O (C=O)-, -CH2CH2NH(C=O)O( _CH2 ) _mO (C=O)- or -( _CH2 ) _nO (C=O _{) NHCH2CH2O} (C=O)-; wherein m and n each independently represent an integer of ₁ to 4,

In the general formula (3), Y represents an aryl group having 6 to 11 carbon atoms which may have a substituent, an aralkyl group having 7 to 10 carbon atoms which may have a substituent, or a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, and the alkali-soluble resin is obtained by adding glycidyl (meth)acrylate to (meth)acrylic acid, wherein the solid content of the residual glycidyl (meth)acrylate in the alkali-soluble resin is 0.001 mass % to 0.500 mass %.