JP6748419B2 - Photosensitive resin composition - Google Patents

Description

The present invention relates to a photosensitive resin composition. Specifically, it relates to a photosensitive resin composition for a photo spacer or a color filter protective film.

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

Conventionally, in a liquid crystal display panel, beads having a predetermined particle size are used as a photo spacer and a space is provided between two substrates. However, since these beads are dispersed at random, there is a problem that when they are distributed on the color display pixels, light leakage, scattering of incident light, etc. occur and the contrast of the liquid crystal panel is lowered.

In order to solve these problems, a method has been proposed in which a photosensitive resin is used and a columnar resin spacer is formed on a black matrix located between pixels by a photolithography method of partial pattern exposure and development. .. Since this photo spacer can be arranged at a position avoiding pixels, it does not adversely affect the display quality as described above, and the display quality can be improved.

Further, in order to further improve the display quality, high definition of the photo spacer is desired. However, higher definition is required for higher sensitivity, but the sensitivity is low only with ordinary photopolymerization initiators, and the elastic recovery property of the formed high definition photo spacer is deteriorated. Then, there was a phenomenon that the adhesiveness was lowered and the photo spacer was peeled off.
A method of adding a sulfur atom-containing compound (for example, Patent Document 1) has been disclosed as a method of achieving high definition, but when a fine photo spacer is formed, the adhesiveness is significantly reduced.

On the other hand, in recent years, as a mother glass for manufacturing a liquid crystal display (LCD) has become larger, a dropping method (ODF method) (ODF: One Drop Fill) has been proposed instead of a conventional liquid crystal inflow method (vacuum suction method). ing. In this ODF method, a predetermined amount of liquid crystal is dropped and then sandwiched between two substrates to inject the liquid crystal, so that the number of processes and process time can be shortened as compared with the conventional vacuum suction method.
However, in the ODF method, a predetermined amount of liquid crystal, which is calculated from the cell gap and estimated, is dropped and held, so that a pressure change is applied to the photo spacers arranged on the glass substrate at that time. It is desired for the photo spacer to have a high elastic recovery property so that the shape is not plastically deformed due to this pressure change.

In order to obtain such high elastic recovery characteristics, a method of nano-dispersing inorganic fine particles such as an organosilica sol (for example, Patent Document 2) or a content ratio of a polyfunctional monomer such as dipentaerythritol hexaacrylate is 50% or more. There is known a method (for example, Patent Document 3) in which high elasticity is obtained by increasing the strength to 0.
However, in any of the methods, since the adhesiveness between the photospacer and the substrate such as glass is lowered, a photosensitive resin composition for forming a photospacer capable of achieving both high elasticity and high resolution and sufficient adhesiveness is Not obtained.

JP-A-10-274853 JP, 2007-10885, A JP-A-2002-174812

An object of the present invention is to provide a photosensitive resin composition having high resolution and capable of forming a highly precise spacer having excellent elastic recovery characteristics and adhesiveness.

The present inventors have arrived at the present invention as a result of studies to achieve the above object.
That is, the present invention provides a hydrophilic resin (A) having a radical-polymerizable organic group, a polyfunctional (meth)acrylate monomer (B), and a benzophenone type photopolymerization initiation having an absorption maximum wavelength in the range of at least 300 to 400 nm. Alkali-developable photosensitive resin composition containing agent (C) as an essential component; and photospacer and color filter formed on a liquid crystal display element by curing these photosensitive resin compositions It is a protective film.

The photosensitive resin composition of the present invention has the effects of being capable of forming a high-definition photo spacer having high sensitivity, high resolution, and excellent adhesion.

The alkali-developable photosensitive resin composition of the present invention comprises a hydrophilic resin (A) having a radical-polymerizable organic group, a polyfunctional (meth)acrylate monomer (B), and an absorption maximum within a range of at least 300 to 400 nm. Contains a benzophenone type photopolymerization initiator (C) having a wavelength as an essential component

In the present specification, "(meth)acrylate" means "acrylate or methacrylate", "(meth)acrylic acid" means "acrylic acid or methacrylic acid", and "(meth)acrylic resin" means " "Acrylic resin or methacrylic resin" means "(meth)acryloyl group" means "acryloyl group or methacryloyl group" and "(meth)acryloyloxy group" means "acryloyloxy group or methacryloyloxy group".

In addition, the term "developable with alkali" means that the uncured portion can be removed cleanly with an alkaline aqueous solution of the developer in the step of removing the uncured portion using the developer.

Below, (A)-(C) which is an essential structural component of the photosensitive resin composition of this invention is demonstrated in order.
The index of hydrophilicity in the hydrophilic resin (A) having a radically polymerizable organic group, which is the first essential component in the present invention, is defined by HLB, and 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 developability is better when developing the photo spacer, and when it is 19 or less, the water resistance of the cured product is further good.

The “HLB” here is an index showing the balance between hydrophilicity and lipophilicity, and is described in, for example, “Introduction to Surfactants” [2007, Sanyo Chemical Industry Co., Ltd., Takehiko Fujimoto], page 212. It is known as the value calculated by the Oda method, and is not the value calculated by the Griffin method.
The HLB value can be calculated from the ratio of 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 using the values in the table on page 213 of “Introduction to Surfactants”.

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

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 (147-154)"
Those with similar SP values are likely to mix with each other (high dispersibility), and those with different SP values are less likely to mix.

From the viewpoint of photocurability, the radical polymerizable group contained in the molecule of the hydrophilic resin (A) having a radical polymerizable organic group of the present invention is preferably a (meth)acryloyl group, a vinyl group and an allyl group, Preferred is a (meth)acryloyl group.

The hydrophilic functional group contained in the molecule of the hydrophilic resin (A) having a radically polymerizable organic group of the present invention is a carboxyl group, an epoxy group, a sulfonic acid group, a phosphoric acid from the viewpoint of alkali developability. A group is preferable, and a carboxyl group is more preferable.

Specific examples of the hydrophilic resin (A) having a radical polymerizable organic group that can be used in the present invention include a hydrophilic epoxy resin (A1) having a radical polymerizable organic group and a radical polymerizable organic group. Hydrophilic (meth)acrylic resin (A2) etc. are mentioned.

As the hydrophilic epoxy resin having a radical polymerizable organic group (A1) of the present invention, a commercially available epoxy resin is reacted with a compound having a radical polymerizable organic group, and further a compound having a hydrophilic functional group is reacted. Can be synthesized by.
For example, a novolac type epoxy resin having an epoxy group in the molecule is reacted with (meth)acrylic acid, and then a polyvalent carboxylic acid such as phthalic acid or phthalic anhydride or a polyvalent carboxylic acid anhydride is reacted.

The hydrophilic (meth)acrylic resin (A2) having a radically polymerizable organic group of the present invention is obtained by polymerizing a (meth)acrylic acid derivative by an existing method and further reacting a compound having a radically polymerizable group. You can

Radical polymerization is preferable as the method for producing the hydrophilic (meth)acrylic resin (A2), and solution polymerization is preferable because it is easy to control the molecular weight.

Examples of the monomer constituting the hydrophilic (meth)acrylic resin (A2) include (meth)acrylic acid (a21) and (meth)acrylic acid ester (a22).

Examples of (a22) include methyl (meth)acrylate, butyl (meth)acrylate, -2 ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, isobornyl (meth)acrylate, and the like. (Meth)methyl acrylate.

As the monomer constituting the hydrophilic (meth)acrylic resin (A2), the aromatic ring-containing vinyl compound (a23) is used in combination with (a21) and (a22) from the viewpoint of elastic recovery characteristics of the photosensitive resin composition. May be. Examples of such (a23) include styrene.

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

Examples of the method of 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), and then A method of reacting a compound having a (meth)acryloyl group and an isocyanate group [(meth)acryloyloxyethyl isocyanate or the like].

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

The hydrophilic resin (A) of the present invention has a number average molecular weight of 1,000 to 100,000, preferably 3,000 to 50,000.

The content of the hydrophilic resin (A) in the photosensitive resin composition of the present invention is preferably from 5 to 80% by weight, and more preferably from the viewpoint of developability, based on the total weight of (A) to (C). Is 15 to 70% by weight.

As the polyfunctional (meth)acrylate monomer (B) which is the second essential component of the present invention, any monomer having two or more (meth)acryloyl groups can be used without particular limitation.
As such a polyfunctional (meth)acrylate monomer (B), a bifunctional (meth)acrylate (B1), a trifunctional (meth)acrylate (B2), a 4 to 6 functional (meth)acrylate (B3) and a 7 to Examples include 10-functional (meth)acrylate (B4).

Examples of the bifunctional (meth)acrylate (B1) include esterification products of polyhydric alcohol and (meth)acrylic acid [eg, glycol di(meth)acrylate, glycerin di(meth)acrylate, trimethylolpropane diester. (Meth)acrylate, di(meth)acrylate of 3-hydroxy-1,5-pentanediol, di(meth)acrylate of 2-hydroxy-2-ethyl-1,3-propanediol]; alkylene oxide of polyhydric alcohol Esterification product of adduct and (meth)acrylic acid [eg di(meth)acrylate of ethylene oxide adduct of trimethylolpropane, di(meth)acrylate of ethylene oxide adduct of glycerin]; OH group-containing epoxy acrylate at both ends; Examples thereof include esterification products of polyhydric alcohol, (meth)acrylic acid and hydroxycarboxylic acid [eg, hydroxypivalic acid neopentyl glycol di(meth)acrylate].
It is not necessary to react all the hydroxyl groups of the polyhydric alcohol with (meth)acrylic acid, an alkylene oxide adduct, etc., and unreacted hydroxyl groups may remain.

Examples of the trifunctional (meth)acrylate (B2) include tri(meth)acrylate of glycerin, tri(meth)acrylate of trimethylolpropane, tri(meth)acrylate of pentaerythritol; and trioxide of ethylene oxide adduct of trimethylolpropane. (Meth)acrylate etc. are mentioned.

Examples of the 4- to 6-functional (meth)acrylate (B3) include pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; ethylene oxide addition of dipentaerythritol. Examples thereof include tetra(meth)acrylate, an ethylene oxide adduct of dipentaerythritol penta(meth)acrylate, and a propylene oxide adduct of dipentaerythritol penta(meth)acrylate.

Examples of the 7- to 10-functional (meth)acrylate compound include compounds obtained by reacting dipentaerythritol penta(meth)acrylate with hexamethylene diisocyanate, by reacting a diisocyanate compound with a hydroxyl group-containing polyfunctional (meth)acrylate compound. Obtainable.

The content of the polyfunctional (meth)acrylate monomer (B) in the photosensitive resin composition of the present invention is preferably 10 to 80 based on the total weight of (A) to (D) from the viewpoint of elastic recovery rate. %, more preferably 20 to 70% by weight.

The benzophenone type photopolymerization initiator (C) which is the third essential component of the present invention is required to have a maximum absorption wavelength at least at 300 to 400 nm, and the photospacer is formed in a vertical shape (upper diameter and lower diameter). A compound represented by the following general formula (1) that enables the ratio of the bottom diameter to be increased) is preferable.
In the case of a photopolymerization initiator having two or more maximum absorption wavelengths, one of them may fall within this range.
A polymerization initiator having a maximum absorption wavelength of less than 300 nm has poor curability and elastic recovery rate, and a polymerization initiator having a maximum absorption wavelength of only more than 400 nm has poor resolution.
In addition, the curability and the elastic recovery rate are insufficient only with the photopolymerization initiator (E) other than the benzophenone type described later [eg, α-hydroxyalkylphenone type (E1), α-aminoalkylphenone type (E2), etc.]. Will be enough.

[In the formula, X ¹ and X ² each independently represent a substituent or a hydrogen atom represented by the following general formula (2) or general formula (3). ]

[In General Formula (2), R ¹ and R ² represent an alkyl group having 1 to 6 carbon atoms. In formula (3), R ³ represents an alkyl group having 1 to 6 carbon atoms or an aromatic hydrocarbon group which may be substituted with an alkyl group having 1 to 6 carbon atoms. ]

Among the compounds represented by the general formula (1), from the viewpoints of improving photocurability, increasing sensitivity, and increasing resolution, compounds in which X ¹ and X ² are alkylamino groups or thioether groups are preferred. , And more preferably 4,4′-bis(diethylamino)benzophenone (maximum absorption wavelength at 374 nm; “SB-PI 701” manufactured by SHUANG-BANG), 4-benzoyl-4′-methyldiphenyl sulfide (maximum absorption at 320 nm). Wavelength; "SB-PI 705" manufactured by SHUANG-BANG), and the like.

The content of the benzophenone type photopolymerization initiator (C) in the photosensitive resin composition of the present invention is usually 1 to 20% by weight based on the total weight of (A) to (C) from the viewpoint of reaction rate. It is preferably 2 to 15% by weight.

From the viewpoint of elastic recovery rate, in addition to (A) to (C), the photosensitive resin composition of the present invention may further contain a polysiloxane compound (D) having two or more hydrolyzable alkoxy groups. preferable.
Examples of the hydrolyzable alkoxy group include methoxy group, ethoxy group, propoxy group and phenoxy group.

Among them, the compound (D) containing two or more alkoxy groups in the molecule is preferably an alkoxypolysiloxane for the purpose of improving the elastic recovery property of the photospacer. More preferably, it is an alkoxypolysiloxane represented by the following general formula (4).

In the formula, R ⁴ represents at least one organic group selected from the group consisting of a (meth)acryloyloxyalkyl group, a glycidoxyalkyl group, a mercaptoalkyl group and an aminoalkyl group.
R ⁵ represents an aliphatic saturated hydrocarbon group, an alicyclic saturated hydrocarbon group, or an aromatic hydrocarbon group. R ⁶ represents an alkyl group having 1 to 4 carbon atoms.
m is 0 or 1.

Among R ⁵ , examples of the aliphatic saturated hydrocarbon group include a straight chain alkyl group, a branched alkyl group and an alicyclic saturated hydrocarbon group.
Examples of the straight-chain alkyl group include methyl, ethyl, n-propyl, n-butyl, n-octyl and n-dodecyl groups, examples of the branched alkyl group include isopropyl, isobutyl, sec-butyl and 2-ethylhexyl groups, and cyclic groups. Examples of the saturated hydrocarbon group include cyclohexyl group, cyclooctyl group, cyclohexylmethyl group, cyclohexylethyl group and methylcyclohexyl group.

Among R ⁵ , examples of the aromatic hydrocarbon group include an optionally substituted aryl group, an aralkyl group and an alkylaryl group.
Aryl groups are phenyl, biphenyl, naphthyl groups and their fluorine or chlorine substituents; aralkyl groups are tolyl, xylyl, mesityl groups and their fluorine or chloride; and alkylaryl groups are methylphenyl and ethyl. Examples thereof include a phenyl group.

R ⁵ is preferably a linear alkyl group, a branched alkyl group or an aryl group from the viewpoint of curing reactivity, more preferably a linear alkyl group or an aryl group, particularly preferably a methyl group, an ethyl group or a phenyl group. And a combination of these.

Examples of R ⁶ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and a sec-butyl group, and a methyl group and an ethyl group are preferable from the viewpoint of thermosetting reactivity. ..

Examples of the silane compound having a (meth)acryloyloxyalkyl group as R ⁴ in the general formula (4) include the following compounds.
m is 0, that is, as a trifunctional silane compound having three alkoxy groups, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3- Acryloyloxy propyl triethoxysilane etc. are mentioned.

Examples of the trifunctional silane compound in which m is 1, that is, having two alkoxy groups include 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, and 3 -Acryloyloxypropylmethyldiethoxysilane and the like.

Examples of the silane compound having a glycidoxyalkyl group as R ⁴ include the following compounds.
m is 0, that is, as a trifunctional silane compound having three alkoxy groups, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.

3-glycidoxy is a trifunctional silane compound in which m is 1, that is, has two alkoxy groups. Examples thereof include propylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane.

Examples of the silane compound having a mercaptoalkyl group as R ⁴ include the following compounds.
Examples of the trifunctional silane compound in which m is 0, that is, having three alkoxy groups, include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.

Examples of the trifunctional silane compound in which m is 1, that is, two alkoxy groups include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropylmethyldiethoxysilane.

Examples of the silane compound having an aminoalkyl group as R ⁴ include the following compounds.
m is 0, that is, as a trifunctional silane compound having three alkoxy groups, N-2 aminoethyl γ-aminopropyltrimethoxysilane, N-2 aminoethyl γ-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane Examples thereof include silane and 3-aminopropyltriethoxysilane.

Examples of the trifunctional silane compound in which m is 1, that is, having two alkoxy groups are N-2 aminoethyl γ-aminopropylmethyldimethoxysilane, N-2 aminoethyl γ-aminopropylmethyldiethoxysilane, and 3-aminopropylmethyl. Examples thereof include dimethoxysilane and 3-aminopropylmethyldiethoxysilane.

Among the compounds (D), preferred are (meth)acryloyloxyalkyl group-containing trifunctional silane compounds having three alkoxy groups, and glycidoxyalkyl group-containing trifunctional silane compounds having three alkoxy groups, Even more preferred are 3-acryloyloxypropyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane.

The content of the polysiloxane compound (D) having two or more hydrolyzable alkoxy groups in the photosensitive resin composition of the present invention is the sum of (A) to (D) from the viewpoint of elastic recovery rate and adhesiveness. It is usually 0.2 to 15% by weight, preferably 0.5 to 12% by weight, based on the weight.

Furthermore, in the photosensitive resin composition of the present invention, it is preferable to use a photopolymerization initiator (E) other than the benzophenone-based photopolymerization initiator (C) together as a photopolymerization initiator.

As the photopolymerization initiator (E), α-hydroxyalkylphenone type (E1) (for example, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, etc.); α- Aminoalkylphenone type (E2) (for example, (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4- Morpholinophenyl)-butanone-1 etc.); thioxanthone compound type (E3) (eg (isopropylthioxanthone, diethylthioxanthone etc.); phosphate ester type (E4) (eg (2,4,6-trimethylbenzoyldiphenylphosphine Oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc.; acyloxime type (E5) (eg, 1,2-octanedione, 1-[4-(phenylthio)-,2- (O-benzoyl oxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), etc.); benzyl dimethyl ketal Examples include mold (E6).

Of these, α-aminoalkylphenone is preferred from the viewpoint of curability of the cured product, and more preferred is 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one. , 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1.

The amount of the photopolymerization initiator (E) other than (C) used is preferably 0.3 to 10% by weight based on the total of (A) to (E) from the viewpoint of curability and coloring of the cured product, and further, It is preferably 0.5 to 5% by weight.

The photosensitive resin composition according to the present invention may further contain other components, if necessary. Other components include leveling agents (F), inorganic fine particles (eg, titanium oxide, alumina, etc.), sensitizers, polymerization inhibitors, solvents, thickeners, and other additives (eg, silane coupling agents). , Fluorescent whitening agents, anti-yellowing agents, antioxidants, defoamers and deodorants, etc.).

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified,% means% by weight and part means part by weight. In the following, Examples 3, 6, and 7 are referred to as Reference Examples 1 to 3, respectively.

Production Example 1 [Production of hydrophilic epoxy resin (A-1)]
200 parts of cresol novolac type epoxy resin "EOCN-102S" (Epoxy equivalent 200 manufactured by Nippon Kayaku Co., Ltd.) was added to a glass Korben equipped with a heating/cooling/stirring device, a reflux condenser, a dropping funnel, and a nitrogen introducing tube. 245 parts of glycol monomethyl ether acetate was charged and heated to 110° C. to uniformly dissolve it. Subsequently, 76 parts (1.07 mol parts) of acrylic acid, 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 reacted at 90° C. for 5 hours, and then propylene glycol monomethyl ether acetate was added so that the hydrophilic resin content became 50% by weight. After dilution, a 50% solution of a carboxyl group-containing cresol novolac type epoxy resin (A-1) was obtained as a hydrophilic resin having an acryloyl group and a carboxyl group of the present invention.
The acid value of this resin in terms of pure content was 88.4. The number average molecular weight (Mn) by GPC was 2,200. The SP value was 11.3 and the HLB value was 6.4.

Production Example 2 [Production of hydrophilic acrylic resin (A-2)]
A glass flask equipped with a heating/cooling/stirring device, a reflux condenser, and a nitrogen inlet tube was charged with 6 parts of methyl methacrylate, 70 parts of methacrylic acid, 172 parts of cyclohexyl methacrylate and 454 parts of diethylene glycol dimethyl ether. After replacing the gas phase in the system with nitrogen, 175 parts of a solution prepared by dissolving 16 parts of 2,2′-azobis(2,4-dimethylvaleronitrile) in 159 parts of diethylene glycol dimethyl ether was added and heated to 90° C. Further, the reaction was carried out at the same temperature for 4 hours.
Further, 31 parts of glycidyl methacrylate, 10 parts of triethylamine, and 82 parts of propylene glycol monomethyl ether acetate were added to the obtained solution, and the mixture was reacted at 90° C. for 6 hours to obtain an acrylic resin having a methacryloyl group and a carboxyl group as an acrylic resin (A A 30% solution of -2) was obtained.
The acid value of the acrylic resin in terms of solid content was 112.9. The number average molecular weight (Mn) by GPC was 4,700. The SP value was 10.2 and the HLB value was 5.2.

Production Example 3 [Production of Polysiloxane Compound (D-1) Having Hydrolyzable Alkoxy Group]
A glass Kolben equipped with a heating/cooling/stirring device, a reflux condenser, a dropping funnel, and a nitrogen inlet tube was charged with 46 parts (0.2 mol parts) of 3-acryloyloxypropyltrimethoxysilane and 160 parts (0 parts of diphenyldimethoxysilane). .65 mol part), ion-exchanged water 45 g (2.5 mol part), and oxalic acid 0.1 part (0.001 mol part) were charged, and the mixture was heated with stirring at 60° C. for 6 hours, and then an evaporator was added. By using, methanol by-produced by hydrolysis was removed under reduced pressure over 2 hours to obtain an acrylic modified polysiloxane (D-1) (Mn: 2,100).

Examples 1-7 and Comparative Examples 1-3
According to the compounding number of Table 1, a 50% propylene glycol monomethyl ether acetate solution of the hydrophilic resin (A-1) produced in Production Example 1 in a glass container, (B-1), (C-1), (E -1), further charged with the siloxane compound (D-1) produced in Production Example 3, stirred until uniform, and further added with an additional solvent (propylene glycol monomethyl ether acetate) to obtain the photosensitivity of Example 1. A resin composition was obtained.
Moreover, the photosensitive resin composition of Examples 2-7 and Comparative Examples 1-3 was obtained using the same apparatus.

The details of the abbreviated chemicals in Table 1 are as follows.
(B-1): "Neomer DA-600" (dipentaerythritol pentaacrylate: manufactured by Sanyo Chemical Industry Co., Ltd.; 6 functional groups)
(B-2): "Neomer EA-300" (pentaerythritol tetraacrylate: manufactured by Sanyo Chemical Industry Co., Ltd.; the number of functional groups is 4)
(B-3): "Light acrylate PE-3A" (pentaerythritol triacrylate: manufactured by Kyoeisha Chemical Co., Ltd.; number of functional groups is 3)
(B'-1): "Light acrylate PO-A" (phenoxyethyl acrylate: manufactured by Kyoeisha Chemical Co., Ltd.; the number of functional groups is 1)
(C-1): "SP-PI 705"(4-benzoyl-4'-methyldiphenyl sulfide, maximum absorption wavelength 315 nm: manufactured by SHUANG-BANG)
(C-2): "SB-PI 701"(4,4'-bis(diethylamino)benzophenone, maximum absorption wavelength 374 nm: manufactured by SHUANG-BANG)
(C′-1): “SB-PI 712” (4-methylbenzophenone, maximum absorption wavelength 257 nm: manufactured by SHUANG-BANG).
(E-1): "Irgacure 369" (2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, maximum absorption wavelength 320 nm: manufactured by BASF Corporation)
(E-2): "Irgacure 907" (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, maximum absorption wavelength 305 nm: manufactured by BASF Corporation)
(F-1): "KF-352A" (polyether-modified polydimethylsiloxane: manufactured by Shin-Etsu Chemical Co., Ltd.)
(F-2): "Megafuck TF-2066" (polyether-modified fluorine compound: manufactured by DIC Corporation)

The method for evaluating the performance of adhesion, elastic recovery rate, and resolution will be described below.
[Production of photo spacers]
A 10 cm×10 cm square glass substrate was coated with 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 obtained coating film was irradiated with light of an ultra-high pressure mercury lamp at 60 mJ/cm ² through a mask for forming a plurality of photo spacers having 10,000 openings per 1 cm ² and having diameters of 7, 8, 9 and 10 μm (i Illuminance 22 mW/cm ^{2 in} line conversion).
The mask and the substrate were exposed at an interval (exposure gap) of 100 μm.
After that, alkali development was performed using a 0.05% KOH aqueous solution. After washing with water, post baking was performed at 230° C. for 30 minutes to form 10,000 photo spacers per 1 cm ² on the glass substrate.
A photo spacer having a desired bottom diameter can be formed by adjusting the mask opening diameter.

[Evaluation of adhesion]
With the miniaturization and high definition of LCDs, the size of the photo spacers formed on the substrate is required to be 10 μm or less. However, the smaller the contact area between the substrate and the photo spacer, the higher the degree of adhesion required.
That is, the higher the adhesiveness of the photo spacer, the more excellent the performance is that it is less likely to be peeled off by rubbing or the like even when the lower bottom diameter of the spacer is reduced.
Therefore, the adhesiveness was evaluated by the following cotton swab rub test with the bottom diameter of the spacer set to 8 μm.

From the photo spacers prepared by using the masks for forming a plurality of photo spacers having the above-mentioned diameters of 7, 8, 9 and 10 μm, only the mask having the lower bottom diameter of 8 μm was selected, and the following adhesiveness was selected. The test was conducted.
(1) A cross-shaped mark of 1 cm in length and 1 cm in width is made on the back side of the glass substrate on which the photo spacer is formed with an oil-based pen.
(2) Using a cotton swab soaked with acetone, first rub the front surface of the glass substrate with the cross-shaped mark 10 times downward from above the vertical line at a speed of 2 cm per second.
Then, from the left to the right of the horizontal line, rub 10 times at a speed of 2 cm per second.
(3) Count the number of photo spacers remaining without peeling the points where the rubbed portions intersect in (2) above with an optical microscope.
If there is no peeling, there are 100 (10×10) spacers per 1 mm ² on the glass substrate.

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

(1) With respect to one photo spacer arbitrarily selected from the photo spacers formed on the glass substrate, a micro hardness meter (manufactured by Fisher Instruments Co.; “Fisherscope H-100”) and a plane indenter having a square section (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 speed of 2 mN/sec was applied to 60 mN over 30 seconds, and the load was maintained for 5 seconds.
The amount of deformation of the photo spacer from the initial position under load was measured. The amount of change at this time is set as the total deformation amount T ₀ (μm).
(2) Next, the load was released to 0 over 30 seconds at an unloading speed of 2 mN/sec, and the state was maintained for 5 seconds. The deformation amount of the photo spacer at this time is defined as the 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 mathematical formula (1).
In addition, 70% or more is preferable under this evaluation condition.

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

[Resolution evaluation]
Since LCDs have become smaller and higher definition and the pixel size has become smaller, it is possible to form fine photo spacers, that is, patterning with a resolution of 10 μm or less is required. Has become.
That is, the higher the resolution, the better the performance of forming a photo spacer having the same size as the opening diameter of the mask, even if the opening diameter of the mask is small.
Therefore, the resolution was evaluated by setting the opening diameter of the mask to 10 μm and measuring the bottom diameter of the photo spacer when the photo spacer was formed by the above method. The smaller the bottom diameter, the higher the resolution.
In this evaluation condition, 12 μm or less is preferable.

The photosensitive resin compositions of Examples 1 to 7 of the present invention are excellent in all of the adhesiveness, elastic recovery rate and resolution as shown in Table 1.
On the other hand, Comparative Example 1 not containing the benzophenone type photopolymerization initiator of the present invention and Comparative Example 2 using the benzophenone type photopolymerization initiator having a maximum absorption wavelength of 300 nm or less do not satisfy the elastic recovery rate. Further, Comparative Example 3 using a monofunctional acrylate instead of the polyfunctional acrylate does not satisfy the elastic recovery rate and the resolution.

Since the photosensitive resin composition of the present invention is excellent in elastic recovery characteristics after curing and adhesion to a glass substrate, it can be suitably used as a photo spacer for a display element or a protective film for a color filter. Furthermore, in addition to these, insulating film forming resists for touch panels and other various resist materials such as photo solder resists, photosensitive resist films, photosensitive resin letterpress plates, screen plates, photo-adhesives or hard coat materials It is suitable as a resin composition.

Claims (8)

Hydrophilic resin (A) having a radical polymerizable organic group, polyfunctional (meth)acrylate monomer (B), benzophenone type photopolymerization initiator (C) having an absorption maximum wavelength in the range of at least 300 to 400 nm, and 2 -Methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 The polyfunctional (meth)acrylate monomer (B) comprises at least one photopolymerization initiator (E) selected from the group consisting of dipentaerythritol pentaacrylate, pentaerythritol tetraacrylate and pentaerythritol triacrylate. An alkali-developable photosensitive resin composition , which is at least one selected from the group consisting of (A) to (C) and has a content of (A) of 15 to 70% by weight based on the total weight of (A) to (C). The photosensitive resin composition according to claim 1, wherein the photopolymerization initiator (C) is a compound represented by the following general formula (1).
[In the formula, X ¹ and X ² each independently represent a substituent or a hydrogen atom represented by the following general formula (2) or general formula (3). ]
[In the general formula (2), R ¹ and R ² represent an alkyl group having 1 to 6 carbon atoms. In general formula (3), R ³ represents an alkyl group having 1 to 6 carbon atoms or an aromatic hydrocarbon group which may be substituted with an alkyl group having 1 to 6 carbon atoms. ] The photosensitive resin composition according to claim 1, which contains 1 to 15% by weight of the photopolymerization initiator (C) based on the total weight of (A) to (C). The photosensitive resin composition according to claim 1, further comprising a polysiloxane compound (D) having two or more hydrolyzable alkoxy groups. The photosensitive resin composition according to claim 4, which contains 0.2 to 15% by weight of the polysiloxane compound (D) based on the total weight of (A) to (D). The leveling agent (F) is further contained, and the leveling agent (F) is at least one selected from the group consisting of polyether-modified polydimethylsiloxane and polyether-modified polydimethylsiloxane. The photosensitive resin composition according to any one of claims. A photo spacer obtained by curing the photosensitive resin composition according to claim 1. A protective film for a color filter, which is obtained by curing the photosensitive resin composition according to claim 1.