JP2014081456A - Photosensitive resin composition, cured product and spacer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition showing excellent elastic recovery characteristics and developability.SOLUTION: The photosensitive resin composition comprises, as essential components, a hydrophilic resin (A), a polyfunctional (meth)acrylate (B), a radical trapping agent (C), a photopolymerization initiator (D), and a metal element-containing compound (E). The composition is alkali-developable and shows, as a pure composition thereof, a viscosity of 4,000 mPa s to 10,000 mPa s at 25°C.

Description

  The present invention relates to a photosensitive resin composition suitable for forming a spacer, and a cured product and a spacer formed from the composition.

  In recent years, liquid crystal display devices have attracted attention, and photosensitive resins are frequently used in the manufacturing process. For example, a photosensitive resin in which a color pigment is dispersed is used for a portion corresponding to a pixel on a color filter, and a photosensitive resin is also used for a black matrix.

  Conventionally, in a liquid crystal display panel, beads having a predetermined particle diameter are used as spacers and a space is provided between two substrates. However, since these beads are dispersed randomly, there is a problem that light leakage, scattering of incident light, etc. occur due to distribution on the color display pixels, and the contrast of the liquid crystal panel is lowered.

  In order to solve these problems, a method has been proposed in which a columnar resinous spacer is formed on a black matrix located between pixels by a photolithographic method of partial pattern exposure and development using a photosensitive resin. . Such a spacer is hereinafter referred to as a photo spacer. Since the photo spacer can be arranged at a position avoiding the pixels, it does not adversely affect the display quality as described above, and the display quality can be improved. To further improve the display quality, miniaturization of the photo spacer is desired, but due to the miniaturization, the shape of the photo spacer becomes a taper shape (a triangular shape in which the side of the film surface is shorter than the side on the substrate side) A high elastic recovery rate as a photospacer cannot be obtained. Therefore, a method of cutting long wavelengths and adjusting the shape for fine pattern formation (for example, Patent Document 1) has been disclosed, but since the curability is low, adhesion is significantly reduced when a fine photospacer is formed. .

On the other hand, in recent years, a drop method (ODF: One Drop Fill) has been proposed in place of the conventional liquid crystal inflow method (vacuum suction method) as the mother glass for manufacturing a liquid crystal display (LCD) becomes larger. ing. In this ODF method, since a predetermined amount of liquid crystal is dropped and then liquid crystal is injected by being sandwiched between two substrates, the number of steps and the process time can be reduced as compared with the conventional vacuum suction method.
However, in the ODF system, a predetermined amount of liquid crystal calculated from the cell gap is dropped and held, so that a pressure change is applied to the spacer disposed on the glass substrate. It is desired for the photo spacer to have a high elastic recovery characteristic so that the shape does not plastically deform with respect to this pressure change.

In order to obtain such high elastic recovery characteristics, a method of nano-dispersing fine particles such as organosilica sol (for example, Patent Document 2), or the content ratio of a polyfunctional monomer such as dipentaerythritol hexaacrylate is set to 50% or more. A method (for example, Patent Document 3) that obtains high elasticity by increasing is known.
However, none of the methods has yielded a photosensitive resin composition for forming a photospacer having excellent elastic recovery characteristics. Moreover, when a large amount of fine particles are added, the viscosity of the pure component increases, and there is a problem that developability is not good.

JP 2010-15025 A Japanese Patent Laid-Open No. 2007-10885 JP 2002-174812 A

  An object of this invention is to provide the photosensitive resin composition which expresses the outstanding elastic recovery characteristic and developability.

The inventors of the present invention have reached the present invention as a result of studies to achieve the above object.
That is, the present invention contains hydrophilic resin (A), polyfunctional (meth) acrylate (B), radical trap agent (C), photopolymerization initiator (D) and metal element-containing compound (E) as essential components. And an alkali-developable photosensitive resin composition having a pure viscosity at 25 ° C. of 4,000 mPa · s to 10,000 mPa · s; formed by photocuring the photosensitive resin composition Cured product; and a spacer formed on the liquid crystal display element by curing the photosensitive resin composition.

  The photosensitive resin composition of the present invention can exhibit excellent alkali developability, and the spacer obtained from the photosensitive resin composition of the present invention has the effect of exhibiting excellent elastic recovery characteristics.

The photosensitive resin composition of the present invention comprises a hydrophilic resin (A), a polyfunctional (meth) acrylate (B), a radical trap agent (C), a photopolymerization initiator (D), and a metal element-containing compound (E). Contains as an essential component.
In the present specification, “(meth) acrylate” means “acrylate or methacrylate”.

The viscosity at 25 ° C. of the photosensitive resin composition of the present invention is usually 4,000 mPa · s to 10,000 mPa · s, preferably 4,200 mPa · s to 9,000 mPa · s, more preferably 4, 500 mPa · s to 8,000 mPa · s.
If the viscosity of the pure component is less than 4,000 mPa · s, the yield is poor, and if it exceeds 10,000 mPa · s, the developability is extremely deteriorated.
Here, the viscosity of the pure component means the viscosity of all components constituting the photosensitive resin composition excluding components having a boiling point of 200 ° C. or less at normal pressure such as a solvent. The viscosity in the present invention is measured by a Brookfield type rotational viscometer (BL type viscometer) (rotor: No. 3, rotational speed: 12 rpm).

  Below, (A)-(E) which is an essential structural component of the photosensitive resin composition of this invention is demonstrated in order.

The hydrophilicity index in the hydrophilic resin (A), which is the first essential component of the present invention, is defined by HLB. Generally, the larger this value, the higher the hydrophilicity.
The HLB value of (A) is preferably 4 to 19, more preferably 5 to 18, and particularly preferably 6 to 17. When it is 4 or more, the developing property is further improved when developing the photospacer, and when it is 19 or less, the water resistance of the cured product is further improved.

Here, “HLB” is an index indicating a balance between hydrophilicity and lipophilicity, and is described in, for example, “Introduction to Surfactants” (published by Sanyo Chemical Industries, Ltd., 2007, Takehiko Fujimoto), page 212. It is known as the calculated value by the Oda method, not the calculated value by the Griffin method.
The HLB value can be calculated from the ratio between the organic value and the inorganic value of the organic compound.
HLB≈10 × inorganic / organic The organic value and the inorganic value for deriving HLB can be calculated by using the values in the table described in “Introduction of Surfactant” on page 213.

Further, the solubility parameter (hereinafter referred to as SP value) [(unit is (cal / cm ³ ) ^1/2 ]) of the hydrophilic resin (A) is preferably 7 to 14, more preferably 8 to 13, particularly preferably. Is from 9 to 13. If it is 7 or more, the developability can be further improved, and if it is 14 or less, the water resistance of the cured product is further improved.

The SP value in the present invention is calculated by the method described in the following document proposed by Fedors et al.
"POLYMER ENGINEERING AND SCIENCE, February, 1974, Vol. 14, No. 2, Robert F. Fedors (pp. 147-154)"
Those with close SP values are likely to mix with each other (highly dispersible), and those with a distant numerical value are difficult to mix.

The hydrophilic functional group contained in the molecule of the hydrophilic resin (A) used in the present invention includes a carboxyl group, an epoxy group, a sulfonic acid group, a hydroxyl group, an amino group, an amide group, a urethane group, a urea group, and a polyether. Group, sulfate group, phosphate group and phosphate group.
Of these hydrophilic groups, a carboxyl group, an epoxy group, a sulfonic acid group, and a phosphoric acid group are preferable from the viewpoint of developability, and a carboxyl group is more preferable.

  Specific examples of the hydrophilic resin (A) that can be used in the present invention include a hydrophilic epoxy resin (A1) and a hydrophilic (meth) acrylic resin (A2).

A commercially available product can be obtained and used as the hydrophilic epoxy resin (A1).
Examples of commercially available hydrophilic epoxy resins include Epototo YH-300, PG-202, and PG-207 (all manufactured by Tohto Kasei Co., Ltd.), CY-179, CY-177, and CY-175 (all manufactured by Asahi Kasei Epoxy Co., Ltd.). Novolak type (phenol novolak type, cresol novolak type, etc.) epoxy resins such as EOCN-102S (manufactured by Nippon Kayaku Co., Ltd.) can be used.

The hydrophilic epoxy resin (A1) may be the normal novolac type epoxy resin described above, and may further contain a (meth) acryloyl group or a carboxyl group in the molecule.
For example, in order to further introduce a (meth) acryloyl group into a molecule, a novolac type epoxy resin having an epoxy group in the molecule may be reacted with acrylic acid or methacrylic acid, while a carboxyl group is introduced. For this, a novolac type epoxy resin may be reacted with a polycarboxylic acid having 4 to 30 carbon atoms such as phthalic acid or phthalic anhydride, or a polycarboxylic acid anhydride. Hydrophilic epoxy resins containing both (meth) acryloyl and carboxyl groups are reacted with (meth) acrylic acid first on a novolak-type epoxy resin, and then added with a polyvalent carboxylic acid or polyvalent carboxylic acid anhydride. It is obtained by the method of making it.

  The hydrophilic (meth) acrylic resin (A2) used in the present invention can be obtained by polymerizing a (meth) acrylic acid derivative by an existing method.

  As a method for producing the hydrophilic (meth) acrylic resin (A2), radical polymerization is preferable, and a solution polymerization method is preferable because the molecular weight can be easily adjusted.

  Examples of the monomer constituting the hydrophilic (meth) acrylic resin (A2) include (meth) acrylic acid (a21) and (meth) acrylic acid ester (a22) (C1-C30 alkyl ester and hydroxyalkyl ester). can give.

  (A22) is preferably methyl (meth) acrylate or hydroxyethyl (meth) acrylate.

  As a monomer constituting the hydrophilic (meth) acrylic resin (A2), from the viewpoint of elastic recovery characteristics of the photosensitive resin composition, an aromatic ring-containing vinyl compound (a23) having 8 to 30 carbon atoms, (a21), You may use together with (a22). Examples of such (a23) include styrene.

  In the hydrophilic (meth) acrylic resin (A2), it is preferable to introduce a (meth) acryloyl group into a side chain or a terminal as necessary for the purpose of further improving the elastic recovery property of the photospacer.

  Examples of the method for introducing a (meth) acryloyl group into the side chain include the following methods (1) and (2).

(1) A polymer is produced using a monomer having a group capable of reacting with an isocyanate group (such as a hydroxyl group or a primary or secondary amino group) in at least a part of (a21) or (a22); A method of reacting a compound having a (meth) acryloyl group and an isocyanate group (such as (meth) acryloyloxyethyl isocyanate).

(2) A polymer is produced using a monomer having a group capable of reacting with an epoxy group (such as a hydroxyl group, a carboxyl group, or a primary or secondary amino group) in at least a part of (a21) or (a22). And then reacting a compound having a (meth) acryloyl group and an epoxy group (such as glycidyl (meth) acrylate).

  Among these, a hydrophilic epoxy resin (A1) is preferable, and a novolak-type epoxy resin that may contain a (meth) acryloyl group and / or a carboxyl group in the molecule is particularly preferable. Since it is excellent in developability, it is a novolak type epoxy resin containing (meth) acryloyl group and / or carboxyl group in the molecule.

The number average molecular weight by the gel permeation chromatography (GPC) method of the hydrophilic resin (A) is preferably 1000 to 30000, more preferably 1500 to 10000.
The number average molecular weight in the present invention uses HLC-8320GPC (manufactured by Tosoh Corp.) as a GPC device, THF solvent, TSK standard polystyrene (manufactured by Tosoh Corp.) as a reference substance, measurement temperature: 40 ° C., Column: measured with Alliance (manufactured by Waters). Moreover, GPC workstation EcoSEC-WS (made by Tosoh Corporation) is used as analysis software.

The content of the hydrophilic resin (A) in the photosensitive resin composition of the present invention is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total weight of (A) to (E). %, Particularly preferably 30 to 65% by weight.
If it is 20% by weight or more, the alkali developability of the photosensitive resin composition is improved, so that it is easy to form a photospacer. If it is 80% by weight or less, the elastic recovery property of the photospacer is better.

The polyfunctional (meth) acrylate (B) as the second essential component of the present invention is not particularly limited as long as it is a known polyfunctional (meth) acrylate.
As such polyfunctional (meth) acrylate (B), bifunctional (meth) acrylate (B1), trifunctional (meth) acrylate (B2), 4-6 functional (meth) acrylate (B3) and 7-10 A functional (meth) acrylate (B4) is mentioned.

  The bifunctional (meth) acrylate (B1) is an esterified product of a polyhydric (preferably 2 to 8 valent) alcohol having 2 to 30 carbon atoms and (meth) acrylic acid [for example, di (meth) acrylate of glycerin, trimethylol. Propane di (meth) acrylate, 3-hydroxy-1,5-pentanediol di (meth) acrylate, 2-hydroxy-2-ethyl-1,3-propanediol di (meth) acrylate]; Alkylene oxide of 2 to 30 polyhydric (preferably 2 to 8 valent) alcohol (2 to 4 carbon atoms of alkylene group) 1 to 30 mol adduct and esterified product of (meth) acrylic acid [for example, ethylene oxide of trimethylolpropane Di (meth) acrylate of adduct, di (meth) acrylate of ethylene oxide adduct of glycerin And OH group-containing both-end epoxy acrylate; esterified product of polyhydric alcohol having 2 to 30 carbon atoms, (meth) acrylic acid and hydroxycarboxylic acid having 3 to 30 carbon atoms [for example, neopentyl glycol di (meth) hydroxypivalate Acrylate] and the like.

  The trifunctional (meth) acrylate (B2) may be an ester of an alcohol and (meth) acrylic acid having 3 to 30 carbon atoms (preferably 3 to 8) having 3 to 30 carbon atoms [for example, tri (meth) acrylate of glycerin, tri A tri (meth) acrylate of methylolpropane, a tri (meth) acrylate of pentaerythritol]; and an alkylene oxide of a trivalent or higher (preferably 3-8) valent alcohol having 3 to 30 carbon atoms (the number of carbon atoms of the alkylene group is 2 to 2). 4) 1-30 mol adduct and esterified product of (meth) acrylic acid [for example, tri (meth) acrylate of ethylene oxide adduct of trimethylolpropane] and the like.

  As the tetra- to hexa-functional (meth) acrylate (B3), an esterified product of an alcohol and (meth) acrylic acid having 4 to 30 carbon atoms (preferably 4 to 8) having 5 to 30 carbon atoms [for example, tetra (meth) of pentaerythritol Acrylate, tetra (meth) acrylate of ditrimethylolpropane, penta (meth) acrylate of dipentaerythritol, hexa (meth) acrylate of dipentaerythritol]; and tetravalent or more having 5 to 30 carbon atoms (preferably 4 to 8 valences) ) Alkylene oxide (2 to 4 carbon atoms of an alkylene group) 1-30 mol adduct and esterified product of (meth) acrylic acid [for example, tetra (meth) acrylate, dipenta of ethylene oxide adduct of dipentaerythritol Penta of erythritol ethylene oxide adduct Meth) acrylate, penta (meth) acrylate], etc. propylene oxide adduct of dipentaerythritol.

  As the (meth) acrylate compound having 7 or more functional groups, for example, a compound obtained by reacting dipentaerythritol penta (meth) acrylate with hexamethylene diisocyanate, a reaction of the diisocyanate compound with the above hydroxyl group-containing polyfunctional (meth) acrylate compound Can be obtained.

  The viscosity at 25 ° C. of the polyfunctional (meth) acrylate (B) used in the photosensitive resin composition of the present invention is preferably 800 mPa · s to 10,000 mPa · s, more preferably 1,000 mPa · s to 8,000 mPa. -S. When it is 800 mPa · s or more, the yield is improved, and when it is 10,000 mPa · s or less, the developability is further improved.

  Of these polyfunctional (meth) acrylates (B), (B2) and (B3) are preferred, and (B3) is more preferred from the viewpoint of elastic recovery properties.

The content of the polyfunctional (meth) acrylate (B) in the photosensitive resin composition of the present invention is preferably 5 to 60% by weight, more preferably 10 based on the total weight of (A) to (E). -50% by weight, particularly preferably 15-50% by weight.
If it is 5% by weight or more, the elastic recovery property of the photospacer is better, and if it is 60% by weight or less, the developability of the photosensitive resin composition is improved and the formation of the photospacer becomes easy.

As the radical trapping agent (C), which is the third essential component of the present invention, known ones are used. For example, 2,6-di-t-butyl-4-methylphenol, 2-t-butyl-6- (3 -T-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di -T-pentylphenyl acrylate, 6- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,6,10-tetra-butyldibenz [d, f] [1, 3,2] dioxaphosphepine, 3-4′-hydroxy-3′-5′-di-t-butylphenyl) propionic acid-n-octadecyl, octadecyl-3- (3,5-di-t- Butyl-4-hydroxy Enyl) -propionate, 3,9-bis [2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1dimethylethyl] -2,4,8,10 -Tetraoxaspiro [5 · 5] undecane, 2,2'-methylenebis (6-tert-butyl-4-methylphenol), 4,4'butylidenebis (6-tert-butyl-3-methylphenol), 3, 6-dioxaoctamethylene = bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], 4,4′-thiobis (2-tert-butyl-5-methylphenol), 4 , 4′-thiobis (6-t-butyl-3-methylphenol), thiodiethylene bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3, -Tris (3 ', 5'-di-t-butyl-4'-hydroxybenzyl) isocyanuric acid, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, penta Erythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,3,5-trimethyl-2,4,6-tris (3,5-di-t- Butyl-4-hydroxybenzyl), p-methoxyphenol, hydroquinone, naphthylamine, tert-butylcatechol, 2,3-di-tert-butyl-p-cresol, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2- And mercaptobenzoselenazole.
Of these, a compound containing a mercapto group and a condensed heterocyclic ring containing a nitrogen atom, an oxygen atom, etc. and an aromatic ring such as a benzene ring (mercapto group-containing heterocyclic condensed aromatic compound) is more preferable. Is a compound represented by the following general formula (2), particularly preferably 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzoselenazole, and most preferably 2-mercaptobenzothiazole.

[In Formula (2), X is an oxygen atom, a sulfur atom, or a selenium atom. ]

The content of the radical trapping agent (C) in the photosensitive resin composition of the present invention is preferably 1 to 15% by weight, more preferably 3 to 10% by weight, based on the total weight of (A) to (E). %.
If it is 1% by weight or more, the resolution of the formed photospacer is better, and if it is 15% by weight or less, the photocurability is improved and the elastic recovery property is better.

Examples of the photopolymerization initiator (D) that is the fourth essential component of the present invention include known photoradical polymerization initiators.
This may be any component as long as it generates a radical capable of initiating polymerization of the polymerizable unsaturated compound by exposure to radiation such as visible light, ultraviolet light, far infrared light, charged particle beam, and X-ray.

  Examples of the photopolymerization initiator (D) include an acetophenone derivative (D1), an acyl phosphine oxide derivative (D2), and a titanocene derivative (D3).

  Examples of the acetophenone derivative (D1) include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, benzyldimethyl ketal, 2-hydroxy-2-methylpropiophenone, 4-isopropyl-2-hydroxy-2-methylpropiophenone, 2 -Methyl-1- (4- (methylthio) phenyl) -2-morpholino-1-propanone, dimethylbenzyl ketal, methylbenzoylformate, 2-benzyl-2-dimethylamino-1- (4-morpholino Eniru) - butan-1-one] and the like.

  Examples of the acylphosphine oxide derivative (D2) include trimethylbenzoyl diphenylphosphine oxide.

  Examples of the titanocene derivative (D3) include bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium. .

  Of these (D1) to (D3), (D1) is preferable from the viewpoint of ease of synthesis, and 2-methyl-1- (4- (methylthio) phenyl) -2-morpholino-1-propanone and 2- Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one is more preferred, and 2-methyl-1- (4- (methylthio) phenyl) -2-morpholino- from the viewpoint of reactivity 1-propanone is particularly preferred.

  As the radical photopolymerization initiator (D1), a commercially available product can be easily obtained. For example, as 2-methyl-1- (4- (methylthio) phenyl) -2-morpholino-1-propanone, Irgacure 907 is available. Examples of 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one include Irgacure 369 (manufactured by BASF).

The content of the photopolymerization initiator (D) in the photosensitive resin composition of the present invention is preferably 1 to 20% by weight, more preferably 3 to 15 based on the total weight of (A) to (E). % By weight.
If it is 1% by weight or more, photocurability is improved, and if it is 20% by weight or less, the resolution and elastic recovery properties of the photospacer are better.

The metal element-containing compound (E), which is the fifth essential component of the present invention, preferably improves the elastic recovery characteristics of the spacer by forming clusters of 1 nm to 100 nm in the resin after curing.
The size of the cluster is more preferably 10 to 80 nm, particularly preferably 12 to 70 nm. If it is 1 nm or more, the elastic recovery property of the spacer can be expressed more favorably, and if it is 100 nm or less, developability and transparency are better.

In addition, as a measuring method of the cluster size in this invention, it can measure with the following conditions with a scanning probe microscope (SII nanotechnology Co., Ltd. product E-sweep SPI4000) Measurement mode: DFM mode Cantilever model number: SI-DF40 (Spring constant 42N / m)
Scanning distance: 150 μm

  The metal element-containing compound (E) is not particularly limited as long as it is a known metal element-containing compound. Examples of such a metal element-containing compound include a metal oxide (E1) and an organometallic compound (E2). Any of the above compounds may contain a (meth) acryloyl group.

  Examples of the metal oxide (E1) include titanium oxide, aluminum oxide, silica, barium titanate, calcium zirconate, niobium oxide, and lead zirconate titanate.

  Examples of the organometallic compound (E2) include alkoxy titanium, alkoxy silane, alkoxy aluminum, alkoxy zirconia, and the like, and alkoxy-containing metal compounds such as a compound represented by the following general formula (1). Of these, from the viewpoint of compatibility with the resin, compounds represented by the following general formula are preferred.

[In formula (1), M is a metal element, and R ¹ and R ² are each independently an alkyl group, a (meth) acryloyl group, a (meth) acryloyloxyalkyl group, or hydrogen. R ³ and R ⁴ are each independently an alkyl group, alkoxy group, aryl group, mercaptoalkyl group, aminoalkyl group, (meth) acryloyloxyalkyl group, (meth) acryloyloxyalkoxy group or (meth) acryloyloxy group When a plurality of R ³ and R ⁴ are contained in one molecule due to repeating units, they may be the same or different groups. However, at least one of n R ³ and n R ⁴ is an alkoxy group. n is an integer of 2-20. ]

  In the formula (1), the metal element M is an element selected from titanium, zirconium, aluminum, silicon, boron, vanadium, manganese, iron, cobalt, germanium, yttrium, niobium, lanthanum, cerium, tantalum, tungsten, and magnesium. Is mentioned. Among these, silicon, zirconium, aluminum, and titanium are preferable, and silicon is particularly preferable.

In formula (1), R ¹ and R ² are each independently an alkyl group, a (meth) acryloyl group, a (meth) acryloyloxyalkyl group, or hydrogen.
Examples of the alkyl group used for R ¹ and R ² include a linear alkyl group and a branched alkyl group. Examples of the linear alkyl group include a methyl group, an ethyl group, a butyl group, and an octyl group, and examples of the branched alkyl chain include an isopropyl group, an isobutyl group, and a 2-ethylhexyl group.

Examples of the (meth) acryloyl group used for R ¹ and R ² include an acryloyl group and a methacryloyl group.

Examples of the (meth) acryloyloxyalkyl group used for R ¹ and R ² include a 1-acryloyloxypropyl group and a 1-methacryloyloxypropyl group.

In the formula (1), R ³ and R ⁴ are each independently an alkyl group, alkoxy group, aryl group, mercaptoalkyl group, aminoalkyl group, (meth) acryloyloxyalkyl group, (meth) acryloyloxyalkoxy group or It is a (meth) acryloyloxy group, and when a plurality of R ³ and R ⁴ are contained in one molecule by repeating units, they may be the same or different groups. However, at least one of n R ³ and n R ⁴ is an alkoxy group.
The alkyl group used for R ³ and R ⁴ is the same as that described for R ¹ and R ² above.

Examples of the alkoxy group used for R ³ and R ⁴ include a methoxy group, an ethoxy group, a butoxy group, and an octoxy group. Of these, a methoxy group is preferably used from the viewpoint of curability.

Examples of the aryl group used for R ³ and R ⁴ include a phenyl group, a biphenyl group, and a naphthyl group. Of these, a phenyl group is preferably used from the viewpoint of reactivity.

Examples of the mercaptoalkyl group used for R ³ and R ⁴ include a mercaptomethyl group, a mercaptoethyl group, and a mercaptobutyl group.

Examples of the aminoalkyl group used for R ³ and R ⁴ include an aminomethyl group, an aminoethyl group, and an aminobutyl group.

The (meth) acryloyloxyalkyl group used for R ³ and R ⁴ is the same as that described for R ¹ and R ² above.

Examples of the (meth) acryloyloxyalkoxy group used for R ³ and R ⁴ include a 1-acryloyloxypropoxy group and a 1-methacryloyloxypropoxy group.

Examples of the (meth) acryloyloxy group used for R ³ and R ⁴ include an acryloyloxy group and a methacryloyloxy group.

  The repeating unit n of the formula (1) is 2 to 20 and preferably 3 to 15 from the viewpoint of the reactivity and storage stability of the compound.

  From the viewpoint of curability of the photosensitive resin composition, the organometallic compound (E2) preferably contains a (meth) acryloyloxy group or a (meth) acryloyloxyalkoxy group.

The content of the metal element-containing compound (E) in the photosensitive resin composition of the present invention is preferably 1 to 40% by weight, more preferably 5 to 30 based on the total weight of (A) to (E). % By weight.
If it is 1% by weight or more, the elastic recovery property of the photospacer is better, and if it is 40% by weight or less, the developability of the photosensitive resin composition is further improved, and the formation of the photospacer becomes easy.

  The photosensitive resin composition according to the present invention may further contain other components as necessary. Other components include inorganic fine particles, photosensitizers, polymerization inhibitors, solvents, thickeners, surface conditioners, and other additives (for example, inorganic pigments, silane coupling agents, dyes, fluorescent whitening agents) , Yellowing inhibitors, antioxidants, antifoaming agents, deodorants, fragrances, bactericides, antibacterial agents, fungicides, and the like.

Hereinafter, the photospacer provided in the liquid crystal cell on the liquid crystal display element of the present invention will be described.
The photospacer of the present invention is a member provided for forming a gap in the liquid crystal cell, and the above photosensitive resin composition is thermally cured at 200 ° C. or higher after polymerization by light irradiation and development with an aqueous alkali solution. It is formed.

A preferable formation step of the photospacer of the present invention is a step in which after light irradiation, alkali development is performed to form a pattern, and post baking, that is, thermosetting is performed at 200 to 260 ° C. for 5 to 90 minutes. From the viewpoints of curability and transparency, it is preferably 210 ° C. to 250 ° C. for 20 minutes to 40 minutes, and more preferably 230 ° C. for 30 minutes.
The formation of the photospacer is usually performed in the following steps (1) to (5).

(1) The process of apply | coating the photosensitive resin composition of this invention on a transparent common electrode As a coating method, a roll coat, a spin coat, a spray coat, a slit coat, etc. are mentioned. Examples of the coating apparatus include a spin coater, an air knife coater, a roll coater, a bar coater, a curtain coater, a gravure coater, and a comma coater. The film thickness is preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

(2) Step of drying the applied photosensitive resin composition layer by applying heat as necessary (prebaking) The drying temperature is preferably 10 to 100 ° C., more preferably 12 to 90 ° C., particularly 15 ~ 80 ° C.
The drying time is preferably 0.5 to 10 minutes, more preferably 1 to 8 minutes, and particularly preferably 2 to 5 minutes.
Drying may be performed under reduced pressure or normal pressure, but reduced pressure is preferred. Moreover, although it may carry out in air or in an inert gas, it is preferably in an inert gas.

(3) Step of exposing the photosensitive resin composition layer with actinic rays through a predetermined photomask The size of the opening of the photomask used is preferably 4 to 15 μm in diameter (area 20 to 100 μm ^2). ) More preferably, the diameter is 6 to 12 μm, and if it is 4 to 15 μm, the pattern can be formed with high accuracy. For example, if the opening has a diameter of 4 to 15 μm, a pattern with a diameter of about 6 to 18 μm can be obtained.
Examples of the active light include visible light, ultraviolet light, and laser light. Examples of the light source include sunlight, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, and a semiconductor laser.
Although it does not specifically limit as an exposure amount, Preferably it is 20-300 mJ / cm < ² >.
In the step of performing exposure, a component having a (meth) acryloyl group in the photosensitive resin composition reacts to undergo photocuring reaction.

(4) Subsequently, the step of removing the unexposed portion with a developer and performing development. Usually, an alkaline aqueous solution is used as the developer.
Examples of the alkaline aqueous solution include aqueous solutions of alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; aqueous solutions of carbonates such as sodium carbonate, potassium carbonate and sodium hydrogencarbonate; hydroxytetramethylammonium and hydroxytetraethylammonium. An aqueous solution of organic alkali can be mentioned. These can be used alone or in combination of two or more kinds, and a surfactant such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant and a nonionic surfactant can be added and used.
As a developing method, there are a dip method and a shower method, but the shower method is preferable.
The temperature of the developer is preferably 25 to 40 ° C. The development time is appropriately determined according to the film thickness and the solubility of the photosensitive resin composition.

(5) Post-heating (post-baking) step This is a step of performing post-baking, that is, thermosetting, at 200 to 260 ° C for 5 to 90 minutes. From the viewpoints of curability and transparency, it is preferably 210 ° C. to 250 ° C. for 20 minutes to 40 minutes, and more preferably 230 ° C. for 30 minutes.
The post-baking may be performed under reduced pressure or normal pressure, but normal pressure is preferred. Moreover, although it may carry out in air or in an inert gas, the air is preferable.
By performing post-baking, the shape of the pattern tends to be a preferable shape or size (for example, a height of 1.0 to 6.0 μm and a bottom diameter of 8.0 to 40.0 μm) as a photospacer.
In the post-heating step, it is presumed that a component having a thermosetting functional group in the photosensitive resin composition reacts and is thermoset. By this reaction, clusters of 1 nm to 100 nm can be formed in the cured product.

  The height of the photo spacer formed by the above process is preferably 1.0 to 6.0 μm, more preferably 1.5 to 5.5 μm, and particularly preferably 2.0 to 5.0 μm.

  The above process makes it easy to control the shape and size (height, upper base diameter, lower base diameter), and provides a stable and highly productive photo spacer with excellent pattern shape, heat resistance, solvent resistance, and transparency. Can be formed.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

[Manufacture of hydrophilic resin]
Production Example 1
In a glass container equipped with a heating / cooling / stirring device, a reflux condenser, a dropping funnel, and a nitrogen introduction pipe, 200 parts of cresol novolac type epoxy resin “EOCN-102S” (epoxy equivalent 200 manufactured by Nippon Kayaku Co., Ltd.) and propylene 245 parts of glycol monomethyl ether acetate was charged and heated to 110 ° C. to dissolve uniformly. Subsequently, 76 parts of acrylic acid (1.07 mol part), 2 parts of triphenylphosphine and 0.2 part of p-methoxyphenol were charged and reacted at 110 ° C. for 10 hours. The reaction product was further charged with 91 parts (0.60 mol part) of tetrahydrophthalic anhydride and further reacted at 90 ° C. for 5 hours, and then the content of hydrophilic epoxy resin with propylene glycol monomethyl ether acetate was 50% by weight. As a hydrophilic resin having an acryloyl group and a carboxyl group, a 50% solution (A-1) of an acryloyl group and a carboxyl group-containing cresol novolac type epoxy resin was obtained.
In addition, the number average molecular weight (Mn) by GPC of this resin was 2,200, SP value: 11.3, and HLB value: 9.8.

[Production of siloxane compound (E-2) having two or more hydrolyzable alkoxy groups]
Production Example 2
In a glass container equipped with a heating / cooling / stirring device, a reflux condenser, a dropping funnel, and a nitrogen introduction tube, 46 parts (0.2 mol part) of 3-acryloyloxypropyltrimethoxysilane, 160 parts of diphenyldimethoxysilane (0 .65 mol parts), 45 g (2.5 mol parts) of ion-exchanged water, and 0.1 part (0.001 mol parts) of oxalic acid, and heated and stirred at 60 ° C. for 6 hours. Using, methanol by-produced by hydrolysis was removed under reduced pressure over 2 hours to obtain acrylic-modified polysiloxane (E-2) (Mn: 2,100).

[Production of titanium oxide compound (E-3) having two or more hydrolyzable alkoxy groups]
Production Example 3
In a glass container equipped with a heating / cooling / stirring device, a reflux condenser, a dropping funnel, and a nitrogen introduction tube, 46 parts (0.2 mol part) of 3-acryloyloxypropyltrimethoxytitanium, 160 parts of diphenyldimethoxytitanium (0 .65 mol parts), 45 g (2.5 mol parts) of ion-exchanged water, and 0.1 part (0.001 mol parts) of oxalic acid, and heated and stirred at 60 ° C. for 6 hours. The methanol by-produced by hydrolysis was removed under reduced pressure over 2 hours to obtain acrylic modified titanium oxide (E-3) (Mn: 2,100).

[Production of photosensitive resin composition]
Examples 1-3 and Comparative Examples 1-2
Into a glass container, the hydrophilic resin solution (A-1) produced in Production Example 1 was charged in accordance with the number of parts shown in Table 1, and the metal element-containing compound (E-2) produced in Production Examples 2 and 3 and ( E-3) and other compounds were added according to the number of parts in Table 1, stirred until uniform, and additional solvent (propylene glycol monomethyl ether acetate and, if necessary, methoxybutyl acetate) was added. The photosensitive resin composition of 1-3 and the photosensitive resin composition of Comparative Examples 1-2 were obtained.

The details of the abbreviated chemicals in Table 1 are as follows.
(B-1): “A-DPH” (dipentaerythritol hexaacrylate; manufactured by Shin-Nakamura Chemical Co., Ltd., viscosity: 6,600 mPa · s / 25 ° C.)
(B-2): “AD-TMP” (ditrimethylolpropane tetraacrylate; manufactured by Shin-Nakamura Chemical Co., Ltd., viscosity: 1,000 mPa · s / 25 ° C.)
(D-1): “Irgacure 907” (2-methyl-1- (4- (methylthio) phenyl) -2-morpholino-1-propanone; manufactured by BASF)
(D-2): “Irgacure 369” (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1; manufactured by BASF)
(F): “Kayacure DETX-S” (2,4-diethylthioxanthen-9-one: manufactured by Nippon Kayaku Co., Ltd.)

  The performance evaluation method will be described below. [Cluster size measurement] was performed according to the method described above.

[Measurement of viscosity of pure component of resin composition]
After adjusting the temperature to 25 ° C., the viscosity of the resin composition (excluding the solvent) was measured using a BL type viscometer (manufactured by Toki Sangyo Co., Ltd.) (rotor: No. 3, rotation speed: 12 rpm).

[Production of photo spacer]
The photosensitive resin composition was applied on a 10 cm × 10 cm square glass substrate by a spin coater and dried to form a coating film having a dry film thickness of 5 μm. This coating film was heated on a hot plate at 80 ° C. for 3 minutes.
The resulting coating film was irradiated with 60 mJ / cm ^{2 of} light from an ultrahigh pressure mercury lamp through a mask for forming a photospacer having 10,000 openings per cm ² and a diameter of 9 μm (illuminance 22 mW / cm ² in i-line conversion). ).
In addition, it exposed with the space | interval (exposure gap) of a mask and a board | substrate 100 micrometers.
Thereafter, alkali development was performed using a 0.05% aqueous KOH solution. After washing with water, post-baking was performed at 230 ° C. for 30 minutes to form 10,000 photospacers per 1 cm ² on the glass substrate.
Note that a photo spacer having a desired lower base diameter can be formed by adjusting the mask opening diameter.

[Evaluation of developability]
In the production of the photospacer, after developing for 60 seconds in a 0.05% KOH aqueous solution, the area of the resin composition remaining on the glass substrate was confirmed.
Judgment criteria are as follows.
○: The area of the remaining resin composition with respect to the area of the glass substrate other than the photo spacer is less than 10%. X: The area of the remaining resin composition with respect to the area of the glass substrate other than the photo spacer is 10% or more.

[Evaluation of elastic recovery characteristics]
The elastic recovery characteristic of the photospacer can be evaluated by the “elastic recovery rate” when a certain pressure defined by the following formula (1) is applied. The higher the elastic recovery rate (%), the better the elastic recovery characteristics.
The elastic recovery characteristic was evaluated by measuring the elastic recovery rate under a pressure condition of 0.5 mN / μm ² .

(1) A micro hardness tester (Fischer Instruments, Inc .; “Fischer Scope H-100”) and a planar indenter having a square cross section for one photo spacer selected arbitrarily from among photo spacers formed on a glass substrate. (50 μm × 50 μm) was used to measure the amount of deformation when a load was applied and when the load was returned.
At this time, a load was applied to 0.5 mN / μm ² over 30 seconds at a load speed of 0.017 mN / μm ² · sec and held for 5 seconds.
The amount of deformation from the initial position of the photospacer in a state where a load was applied was measured. The amount of change at this time is defined as a total deformation amount T ₀ (μm).
(2) Next, the load was released to 0 over 30 seconds at an unloading speed of 0.017 mN / μm ² · sec, and the state was maintained for 5 seconds. The deformation amount of the photo spacer at this time is defined as a plastic deformation amount T ₁ (μm).
(3) From the T ₀ and T ₁ measured as described above, the elastic recovery rate was calculated using the following formula (1).

Elastic recovery rate (%) = [(T ₀ −T ₁ ) / T ₀ ] × 100 (1)

From the value of the elastic recovery rate, the elastic recovery characteristics were determined as follows according to the following criteria.
○: 70% or more ×: less than 70%

The photosensitive resin compositions of Examples 1 to 3 of the present invention are excellent in all points of elastic recovery characteristics and developability as shown in Table 1.
On the other hand, the viscosity at 25 ° C. is 10,000 mPa.s. In Comparative Example 1 exceeding s, the developability is not satisfied. Further, Comparative Example 2 not containing the metal element-containing compound (E) does not satisfy the elastic recovery characteristics.

  The photosensitive resin composition of this invention can be used conveniently for photospacers. Furthermore, it is also suitable as a photosensitive resin composition for various other resist materials such as a photo solder resist, a photosensitive resist film, a photosensitive resin relief plate, a screen plate, a photoadhesive or a hard coat material.

Claims (9)

  It contains a hydrophilic resin (A), a polyfunctional (meth) acrylate (B), a radical trap agent (C), a photopolymerization initiator (D), and a metal element-containing compound (E) as essential components. A photosensitive resin composition capable of alkali development, having a viscosity at 4,000 ° C. of 4,000 mPa · s to 10,000 mPa · s.   The photosensitive resin composition according to claim 1, wherein the polyfunctional (meth) acrylate (B) has a viscosity at 25 ° C. of 800 mPa · s to 10,000 mPa · s. The metal element-containing compound (E) is a polymer compound containing at least one alkoxy group in the molecule and having an alkoxy group-containing monomer represented by the following general formula (1) as a constituent component: 2. The photosensitive resin composition according to 2.

[In formula (1), M is a metal element, and R ¹ and R ² are each independently an alkyl group, a (meth) acryloyl group, a (meth) acryloyloxyalkyl group, or hydrogen. R ³ and R ⁴ are each independently an alkyl group, alkoxy group, aryl group, mercaptoalkyl group, aminoalkyl group, (meth) acryloyloxyalkyl group, (meth) acryloyloxyalkoxy group or (meth) acryloyloxy group When a plurality of R ³ and R ⁴ are contained in one molecule due to repeating units, they may be the same or different groups. However, at least one of n R ³ and n R ⁴ is an alkoxy group. n is an integer of 2-20. ]   The photosensitive resin composition according to claim 1, wherein the radical trapping agent (C) is a mercapto group-containing heterocyclic condensed aromatic compound.   Based on the total weight of the photosensitive resin composition (A) to (E), the hydrophilic resin (A) is 20 to 80% by weight, and the polyfunctional (meth) acrylate (B) is 5 to 60% by weight. 1 to 15% by weight of the radical trapping material (C), 1 to 20% by weight of the photopolymerization initiator (D), and 1 to 40% by weight of the metal element-containing compound (E). The photosensitive resin composition in any one of -4.   Hardened | cured material formed by photocuring the photosensitive resin composition in any one of Claims 1-5.   The cured product according to claim 6, wherein a cluster of 1 nm to 100 nm of the metal element-containing compound (E) is formed.   The cured product according to claim 6 or 7, which is a resist formed by thermal curing at 200 ° C or higher after polymerization by light irradiation and development with an aqueous alkali solution.   A spacer formed on the liquid crystal display element by curing the photosensitive resin composition according to claim 1.