JP6577746B2 - Photo-curable resin composition, liquid crystal display element sealant and touch panel interlayer filler - Google Patents

Description

The present invention uses a photocurable resin composition that can be reliably cured without dripping due to light irradiation and has excellent adhesion to an adherend, and the photocurable resin composition. The present invention relates to a liquid crystal display element sealing agent and a touch panel interlayer filler.

Photocurable resins are used in a wide range of fields including the electronic equipment field.
For example, in recent manufacturing methods of liquid crystal display elements, a dripping method using a sealant made of a photocurable resin composition is becoming mainstream. In the dropping method, first, a rectangular seal pattern is formed on one of two transparent substrates with electrodes by screen printing or the like. Next, fine droplets of liquid crystal are dropped and applied to the entire surface of the transparent substrate frame in an uncured state of the sealant, and the other transparent substrate is immediately overlaid, and the sealant is irradiated with ultraviolet rays for temporary curing. Then, if necessary, it is heated at the time of liquid crystal annealing and further cured to produce a liquid crystal display element. If the substrates are bonded together under reduced pressure, a liquid crystal display element can be manufactured with extremely high efficiency.

In addition, for example, touch panels used in various fields in recent years are arranged under a surface protection panel made of glass or the like, and subsequently, a polarizing film and a display are provided in this order. In the touch panel, the interlayer between the surface protection panel and the touch panel and the interlayer between the touch panel and the polarizing film are filled with a touch panel filler, and a photo-curable resin composition is also used as the touch panel interlayer filler.

As such a photocurable resin, for example, Patent Document 1 includes an aliphatic epoxy resin α having one or more hydroxyl groups and a total of three or more epoxy groups and (meth) acryl groups in one molecule, A liquid crystal sealing agent in which the aliphatic epoxy resin α has a mass average molecular weight of 0.3 × 10 ^{3 to} 1.0 × 10 ³ is disclosed. The liquid crystal sealant described in Patent Document 1 is said to be able to be cured in a short time without changing display characteristics even under high temperature and high humidity conditions when used in a liquid crystal display panel.
However, even if the photocurable resin described in Patent Document 1 is actually irradiated with light, there is a problem that a so-called sag occurs that a part of the pattern flows without being sufficiently cured. there were.

International Publication No. 2010/038431

The inventors of the present invention have studied the cause of the occurrence of liquid sag without curing sufficiently even with light irradiation of a conventional photocurable resin as described in Patent Document 1.
In Patent Document 1, an acrylic acid-modified epoxy resin obtained by reacting the epoxy group of an epoxy resin having two or more epoxy groups in one molecule with (meth) acrylic acid is used as a photocurable resin. Yes. However, the acrylic acid-modified epoxy resin obtained by such a reaction has a non-uniform introduction amount of (meth) acryloyl groups, and a resin in which all epoxy groups in one molecule are modified with acrylic acid, This is a mixture of resins in which all the epoxy groups in the molecule are not modified with acrylic acid (that is, resins containing no (meth) acryloyl groups). As a result, it was considered that the occurrence of dripping occurred due to non-uniform photocuring even when irradiated with light.
On the other hand, it was considered that the amount of (meth) acryloyl groups introduced could be increased by reacting an excess amount of (meth) acrylic acid, but in the case of a photo-curing resin introduced with a large amount of (meth) acryloyl groups. In addition, there is a problem that the shrinkage rate at the time of photocuring becomes large or the cured product becomes too hard, and the adhesion to the adherend is lowered.
In light of the above-mentioned present situation, the present invention is capable of being reliably cured without dripping by light irradiation, and having excellent adhesion to an adherend, and the photocurable resin composition It aims at providing the sealing compound for liquid crystal display elements which uses a thing, and the interlayer filler for touchscreens.

The present invention contains a living radical copolymer having 0.8 to 1.4 (meth) acryloyl groups in one molecule and a number average molecular weight of 500 to 10,000, and a photo radical polymerization initiator. It is a photocurable resin composition.
The present invention is described in detail below.

The photocurable resin composition of the present invention has 0.8 to 1.4 (meth) acryloyl groups in one molecule, and a living radical copolymer having a number average molecular weight of 500 to 10,000 (hereinafter, simply referred to as a “radical copolymer”). "Living radical copolymer").
The living radical copolymer is obtained by living radical polymerization using a monomer such as (meth) acrylic monomer as a raw material, preferably living radical polymerization using an organic tellurium polymerization initiator.
Living radical polymerization is polymerization in which molecular chains grow without the polymerization reaction being hindered by side reactions such as termination reactions or chain transfer reactions. According to living radical polymerization, for example, a polymer having a more uniform molecular weight and composition than that of free radical polymerization can be obtained, and generation of low molecular weight components and the like can be suppressed. Furthermore, by using a method for producing a living radical copolymer having a primary polymerization step and a secondary polymerization step, which will be described later, a (meth) acryloyl group can be introduced extremely uniformly and at the end of the molecule. Can exhibit high photocurability.

The lower limit of the number of (meth) acryloyl groups in one molecule of the living radical copolymer is 0.8, and the upper limit is 1.4. When the number of (meth) acryloyl groups in one molecule is within this range, the photocurable resin composition can be reliably cured without dripping due to light irradiation and has excellent adhesion to an adherend. You can get things. The preferable lower limit of the number of (meth) acryloyl groups in one molecule is 1.0, and the preferable upper limit is 1.2.

The living radical copolymer preferably further has a glycidyl group. If the living radical copolymer which has a glycidyl group is used, it can be set as the photothermosetting resin composition which hardens | cures not only by light irradiation but by heating.
When the living radical copolymer has a glycidyl group, the preferable lower limit of the epoxy equivalent of the living radical copolymer is 200, and the preferable upper limit is 2000. When the epoxy equivalent is within this range, high thermosetting properties can be obtained, and a cured product having no stickiness can be obtained by heating. The more preferable lower limit of the epoxy equivalent is 220, and the more preferable upper limit is 1800.
In addition, an epoxy equivalent means the numerical value which divided the molecular weight of the living radical copolymer by the number of glycidyl groups.

The lower limit of the number average molecular weight (Mn) of the living radical copolymer is 500, and the upper limit is 10,000. When the number average molecular weight (Mn) is within this range, when used as a sealant for a liquid crystal display element or an interlayer filler for a touch panel, high coatability can be exhibited and high adhesion to an adherend is exhibited. be able to. The preferable lower limit of the number average molecular weight (Mn) is 800, and the preferable upper limit is 9800.

The living radical copolymer has a preferred lower limit of the molecular weight distribution (Mw / Mn) of 1.05 and a preferred upper limit of 2.5. When the molecular weight distribution (Mw / Mn) is within this range, a photocurable resin composition that can be reliably cured without dripping due to light irradiation and has excellent adhesion to an adherend is obtained. be able to. A more preferable upper limit of the molecular weight distribution is 2.0.
The molecular weight distribution (Mw / Mn) is a ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
A weight average molecular weight (Mw) and a number average molecular weight (Mn) are measured as a polystyrene conversion molecular weight by a gel permeation chromatography (GPC) method. Specifically, the weight average molecular weight (Mw) and the number average molecular weight (Mn) were obtained by filtering a diluted solution obtained by diluting a living radical copolymer 50 times with tetrahydrofuran (THF) through a filter. It is measured as polystyrene-reduced molecular weight by the GPC method using the filtrate. In the GPC method, for example, 2690 Separations Model (manufactured by Waters) or the like can be used.

The living radical copolymer is obtained by, for example, subjecting a primary monomer mixture containing a living radical polymerization initiator represented by (meth) acrylic monomer, the following general formula (1) or the following general formula (2) to living radical polymerization. It can be produced by a primary polymerization step for obtaining a polymer and a production method comprising a secondary polymerization step for polymerizing a polymer produced by the primary polymerization step by adding a polyfunctional (meth) acrylic monomer.

In formula (1), R ¹ represents an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, or an aromatic heterocyclic group, and R ² and R ³ are a hydrogen atom or an alkyl having 1 to 8 carbon atoms. R ⁴ represents an alkyl group, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an acyl group, a carboxyl group, an alkoxycarbonyl group or a cyano group.

In formula (2), R ⁵ represents a divalent hydrocarbon group having 1 to 18 carbon atoms, R ⁶ represents an alkyl group or phenyl group having 1 to 18 carbon atoms, and R ⁷ represents a hydrogen atom or 1 carbon atom. represents ~ 18 alkyl group, R ⁸ is a phenyl group, a monovalent organic group containing an ester group, a monovalent organic group comprising an amide group, a monovalent organic group containing an imide group, nitrile group, a hydrogen atom or An alkyl group having 1 to 18 carbon atoms is represented.

In the method for producing a living radical copolymer, first, a primary monomer mixture containing a (meth) acrylic monomer, the living radical polymerization initiator represented by the general formula (1) or the general formula (2) is converted into a living radical. A primary polymerization step is carried out to obtain a polymer by polymerization.

The primary monomer mixture contains a (meth) acrylic monomer. The said (meth) acryl monomer is a raw material which comprises the principal chain of the living radical copolymer obtained.
Examples of the (meth) acrylic monomer include a methacrylic monomer and an acrylic monomer.
The methacrylic monomer is not particularly limited. For example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, isomyristyl. Examples include methacrylic acid alkyl esters such as methacrylate and stearyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, benzyl methacrylate, 2-butoxyethyl methacrylate, 2-phenoxyethyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, and polypropylene glycol monomethacrylate. It is done. These methacrylic monomers may be used alone or in combination of two or more.

The acrylic monomer is not particularly limited. For example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, isononyl acrylate, isomyristyl Examples include acrylic acid alkyl esters such as acrylate and stearyl acrylate, cyclohexyl acrylate, isobornyl acrylate, benzyl acrylate, 2-butoxyethyl acrylate, 2-phenoxyethyl acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, and polypropylene glycol monoacrylate. It is done. These acrylic monomers may be used independently and may use 2 or more types together.

Although the said (meth) acryl monomer may be a methacryl monomer or an acrylic monomer, since the ratio which has a (meth) acryloyl group at the terminal can be raised, the one where the ratio of a methacryl monomer is high is preferable.

When the living radical copolymer uses a glycidyl group, a (meth) acryl monomer having a glycidyl group is added to the primary monomer mixture.
Examples of the (meth) acrylic monomer having a glycidyl group include glycidyl methacrylate.

The primary monomer mixture may further contain a (meth) acrylic monomer having another functional group.
Examples of the (meth) acrylic monomer having other functional groups include a (meth) acrylic monomer having a hydroxyl group, a (meth) acrylic monomer having a carboxyl group, a (meth) acrylic monomer having an amino group, and an amide group. (Meth) acrylic monomers, (meth) acrylic monomers having a nitrile group, and the like can be given. These (meth) acrylic monomers having these functional groups may be used alone or in combination of two or more.

The primary monomer mixture contains a living radical polymerization initiator represented by the general formula (1) or the general formula (2). By using such a living radical polymerization initiator, the above (meth) acrylic monomer can be subjected to living radical polymerization.
In the living radical polymerization, the living radical polymerization using the living radical polymerization initiator represented by the general formula (1) or the general formula (2) is different from other living radical polymerizations in that a glycidyl group and a hydroxyl group are used. The polymer having a uniform molecular weight and composition can be obtained by polymerizing with the same initiator without protecting any methacrylic monomers having functional groups such as carboxyl group, amino group, amide group and nitrile group. For this reason, the methacryl monomer which has a functional group can be copolymerized easily.
In addition, when the living radical polymerization initiator represented by the general formula (1) is used, a living radical copolymer having a (meth) acryloyl group at one end can be mainly obtained. When a living radical polymerization initiator represented by () is used, a living radical copolymer having (meth) acryloyl groups at both ends can be obtained.

Specific examples of the living radical polymerization initiator represented by the general formula (1) include (methylterranyl-methyl) benzene, (1-methylterranyl-ethyl) benzene, (2-methylterranyl-propyl) benzene, 1- Chloro-4- (methylterranyl-methyl) benzene, 1-hydroxy-4- (methylterranyl-methyl) benzene, 1-methoxy-4- (methylterranyl-methyl) benzene, 1-amino-4- (methylterranyl-methyl) benzene, 1-nitro-4- (methylterranyl-methyl) benzene, 1-cyano-4- (methylterranyl-methyl) benzene, 1-methylcarbonyl-4- (methylterranyl-methyl) benzene, 1-phenylcarbonyl-4- (methylterranyl- Methyl) benzene, 1-methoxycarbonyl-4- ( Tilteranyl-methyl) benzene, 1-phenoxycarbonyl-4- (methylterranyl-methyl) benzene, 1-sulfonyl-4- (methylterranyl-methyl) benzene, 1-trifluoromethyl-4- (methylterranyl-methyl) benzene, 1- Chloro-4- (1-methylterranyl-ethyl) benzene, 1-hydroxy-4- (1-methylterranyl-ethyl) benzene, 1-methoxy-4- (1-methylterranyl-ethyl) benzene, 1-amino-4- ( 1-methylterranyl-ethyl) benzene, 1-nitro-4- (1-methylterranyl-ethyl) benzene, 1-cyano-4- (1-methylterranyl-ethyl) benzene, 1-methylcarbonyl-4- (1-methylterranyl- Ethyl) benzene, 1-phenylcarbonyl-4- (1-methyl) Terranyl-ethyl) benzene, 1-methoxycarbonyl-4- (1-methylterranyl-ethyl) benzene, 1-phenoxycarbonyl-4- (1-methylterranyl-ethyl) benzene, 1-sulfonyl-4- (1-methylterranyl-ethyl) ) Benzene, 1-trifluoromethyl-4- (1-methylterranyl-ethyl) benzene, 1-chloro-4- (2-methylterranyl-propyl) benzene, 1-hydroxy-4- (2-methylterranyl-propyl) benzene, 1-methoxy-4- (2-methylterranyl-propyl) benzene, 1-amino-4- (2-methylterranyl-propyl) benzene, 1-nitro-4- (2-methylterranyl-propyl) benzene, 1-cyano-4 -(2-Methylterranyl-propyl) benzene, 1-methylcarbonyl 4- (2-methylterranyl-propyl) benzene, 1-phenylcarbonyl-4- (2-methylterranyl-propyl) benzene, 1-methoxycarbonyl-4- (2-methylterranyl-propyl) benzene, 1-phenoxycarbonyl- 4- (2-methylterranyl-propyl) benzene, 1-sulfonyl-4- (2-methylterranyl-propyl) benzene, 1-trifluoromethyl-4- (2-methylterranyl-propyl) benzene, 2- (methylterranyl-methyl) Pyridine, 2- (1-methylteranyl-ethyl) pyridine, 2- (2-methylterranyl-propyl) pyridine, methyl 2-methylterranyl-ethanoate, methyl 2-methylterranyl-propionate, methyl 2-methylterranyl-2-methylpropionate 2-methylterani -Ethane ethanoate, 2-methyl terranyl-propionate, 2-methyl teranyl-2-methyl propionate, 2-methyl terranylacetonitrile, 2-methyl teranyl propionitrile, 2-methyl-2-methyl terranyl pro Examples include pionitrile. The methyl terranyl group in the living radical polymerization initiator represented by the general formula (1) is ethyl terranyl group, n-propyl terranyl group, isopropyl terranyl group, n-butyl terranyl group, isobutyl terranyl group, t-butyl terranyl group. The living radical polymerization initiator represented by the general formula (1) may be used alone or in combination of two or more thereof.

Specific examples of the living radical polymerization initiator represented by the general formula (2) include 1,4-diphenyl-1,4-dimethylteranylbutane and dimethylteranylxylene.

The preferable lower limit of the amount of the primary monomer mixture is 1 mol and the preferable upper limit is 70 mol with respect to 1 mol of the living radical polymerization initiator represented by the general formula (1) or the general formula (2). If it is in this range, in addition to being able to perform living radical polymerization satisfactorily, the obtained copolymer can exhibit excellent photocurability.

The primary monomer mixture preferably contains an azo polymerization initiator in addition to the living radical polymerization initiator represented by the general formula (1) or the general formula (2). By using an azo polymerization initiator in combination, highly efficient polymerization can be performed under a lower temperature condition.
Examples of the azo polymerization initiator include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethyl). Valeronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1-azobis (cyclohexane-1-carbonitrile), 1-[(1-cyano-1-methylethyl) Azo] formamide, 4,4′-azobis (4-cyanovaleric acid), dimethyl-2,2′-azobis (2-methylpropionate), dimethyl-1,1′-azobis (1-cyclohexanecarboxylate) ), 2,2′-azobis {2-methyl-N- [1,1′-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis [2-methyl-N -(2-hydroxyethyl) propionamide], 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2'-azobis (N-butyl-2-methylpropionamide) 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis { 2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2 '-Azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] tetrahydrate, 2,2'-azobis (1-imino -1-Pyro Gino-2-methyl propane) dihydrochloride, 2,2'-azobis (2,4,4-trimethylpentane), and the like. These azo polymerization initiators may be used alone or in combination of two or more.

The primary monomer mixture may contain a radical scavenger represented by the following general formula (3).

In formula (3), R ⁹ represents an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, or an aromatic heterocyclic group.

The radical scavenger represented by the general formula (3) has a role of capturing radicals generated in the polymerization reaction. By adding such a radical scavenger, when the polyfunctional (meth) acrylic monomer is added and polymerized in the secondary polymerization step, the polymerization reaction further proceeds from the polyfunctional (meth) acrylic monomer as a starting point. It is possible to obtain a living radical copolymer having a (meth) acryloyl group at substantially all terminals.
In addition, although the radical scavenger represented by the general formula (3) may be blended in the primary monomer mixture from the beginning, it may be added in the middle of the primary polymerization step, and during the secondary polymerization step. You may add with a polyfunctional (meth) acryl monomer.
In order to further increase the ratio of having a (meth) acryloyl group at the end of the copolymer, the radical scavenger represented by the general formula (3) may be blended in the primary monomer mixture from the beginning. preferable.

Specific examples of the radical scavenger represented by the general formula (3) include dimethyl ditelluride, diethyl ditelluride, di-n-propyl ditelluride, diisopropyl ditelluride, and dicyclopropyl ditelluride. Lido, di-n-butylditelluride, di-sec-butylditelluride, di-tert-butylditelluride, dicyclobutylditelluride, diphenylditelluride, bis- (p-methoxyphenyl) ditelluride, bis- (p-aminophenyl) Examples include ditelluride, bis- (p-nitrophenyl) ditelluride, bis- (p-cyanophenyl) ditelluride, bis- (p-sulfonylphenyl) ditelluride, dinaphthyl ditelluride, and dipyridylditelluride. These radical scavengers represented by the general formula (3) may be used alone or in combination of two or more.

The primary monomer mixture may contain a dispersion stabilizer.
Examples of the dispersion stabilizer include polyvinyl pyrrolidone, polyvinyl alcohol, methyl cellulose, ethyl cellulose, poly (meth) acrylic acid, poly (meth) acrylic acid ester, and polyethylene glycol.

In the primary polymerization step, the primary monomer mixture is subjected to living radical polymerization to obtain a polymer.
As the living radical polymerization method, conventionally known methods are used, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization and the like.
When a polymerization solvent is used in the living radical polymerization, the polymerization solvent is not particularly limited. For example, a nonpolar solvent such as hexane, cyclohexane, octane, toluene, xylene, water, methanol, ethanol, propanol, butanol, acetone, Highly polar solvents such as methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dioxane, N, N-dimethylformamide can be used. These polymerization solvents may be used alone or in combination of two or more.
The polymerization temperature is preferably 0 to 110 ° C. from the viewpoint of the polymerization rate.

Next, in the method for producing the living radical copolymer, a secondary polymerization step is performed in which a polyfunctional (meth) acrylic monomer is further added to the polymer produced by the primary polymerization step and polymerized.
By using the radical scavenger represented by the general formula (3) in combination, it is possible to prevent the polymerization reaction from proceeding further from the polyfunctional (meth) acrylic monomer, and substantially all A living radical copolymer having a (meth) acryloyl group at the terminal can be obtained.

The polyfunctional (meth) acryloyl monomer contains two or more (meth) acryloyl groups in one molecule.
For example, 2-hydroxy-3-acryloyloxypropyl methacrylate, polyethylene glycol # 200 diacrylate, polyethylene glycol # 400 diacrylate, 1,10-decanediol diacrylate, 1,6-hexanediol diacrylate, polypropylene glycol # 400 Examples include diacrylate. These polyfunctional (meth) acrylic monomers may be used alone or in combination of two or more.

The primary polymerization step and the secondary polymerization step can be performed continuously. The conditions such as the polymerization temperature in the secondary polymerization step can be the same as those in the primary polymerization step.

Since the manufacturing method of the living radical copolymer can continuously perform the primary polymerization step and the secondary polymerization step, a living radical copolymer having a (meth) acryloyl group at the terminal can be obtained very easily and easily. Obtainable. Moreover, there are few restrictions on selection of a raw material monomer, and various properties can be imparted to the resulting living radical copolymer by using a (meth) acrylic monomer having a functional group.

The photocurable resin composition of the present invention contains a photoradical polymerization initiator. By using a photoradical polymerization initiator in combination with the living radical copolymer, excellent photocurability can be exhibited.

Examples of the photo radical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, thioxanthones, and the like.
Examples of commercially available photo radical polymerization initiators include Irgacure 184, Irgacure 369, Irgacure 379, Irgacure 651, Irgacure 819, Irgacure 907, Irgacure 2959, Irgacure OXE01, DAROCUR TPO, and Lucyrin TPO (all BASF Japan), benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether (all manufactured by Tokyo Chemical Industry Co., Ltd.) and the like.

In the photocurable resin composition of the present invention, the content of the photopolymerization initiator is preferably 0.1 parts by weight and preferably 30 parts by weight with respect to 100 parts by weight of the living radical copolymer. . If the content of the photopolymerization initiator is less than 0.1 parts by weight, the resulting photocurable resin composition may not exhibit sufficient photocurability, and if it exceeds 30 parts by weight, unreacted The photopolymerization initiator may remain as a residue. The minimum with more preferable content of the said photoinitiator is 1 weight part, A more preferable upper limit is 10 weight part, Furthermore, a preferable upper limit is 5 weight part.

When the living radical copolymer has a glycidyl group, the photocurable resin composition preferably further contains a thermosetting agent. By using a thermosetting agent in combination, excellent thermosetting properties can be exhibited.

Examples of the thermosetting agent include organic acid hydrazides, imidazole derivatives, amine compounds, polyhydric phenol compounds, acid anhydrides, and the like. Among these, solid organic acid hydrazide is preferably used.
Examples of the solid organic acid hydrazide include 1,3-bis [hydrazinocarboethyl-5-isopropylhydantoin], sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, malonic acid dihydrazide, and the like. Examples of such products include Amicure PN23, Amicure VDH, Amicure UDH (all manufactured by Ajinomoto Fine Techno Co., Ltd.), SDH, IDH, ADH (all manufactured by Otsuka Chemical Co., Ltd.), MDH (manufactured by Nippon Finechem Co., Ltd.), and the like. It is done.

The content of the thermosetting agent in the photocurable resin composition of the present invention is preferably 1 part by weight with respect to 100 parts by weight of the living radical copolymer, and 50 parts by weight with respect to the preferred upper limit. If the content of the thermosetting agent is less than 1 part by weight, it may not be able to be sufficiently cured by heat, and if it exceeds 50 parts by weight, the viscosity of the resulting photocurable resin composition will increase, Workability may deteriorate. The upper limit with more preferable content of the said thermosetting agent is 30 weight part.

The photocurable resin composition preferably further contains a curing accelerator when the living radical copolymer has a glycidyl group. By using the above-mentioned curing accelerator, it can be sufficiently cured without being heated at a high temperature.

Examples of the curing accelerator include polyvalent carboxylic acids having an isocyanuric ring skeleton and epoxy resin amine adducts. Specific examples include tris (2-carboxymethyl) isocyanurate and tris (2-carboxyl). And ethyl) isocyanurate, tris (3-carboxypropyl) isocyanurate, and bis (2-carboxyethyl) isocyanurate.

The content of the curing accelerator in the photocurable resin composition of the present invention is preferably 0.1 parts by weight and preferably 10 parts by weight with respect to 100 parts by weight of the living radical copolymer. When the content of the curing accelerator is less than 0.1 parts by weight, a sufficient thermosetting acceleration effect may not be obtained, or heating at a high temperature may be required for thermosetting, When it exceeds 10 weight part, the adhesiveness with respect to the to-be-adhered body of the photocurable resin composition obtained may fall.

The photocurable resin composition of the present invention further contains conventionally known additives such as an inorganic filler, an organic filler, a silane coupling agent, a light shielding agent, a reactive diluent, a spacer, an antifoaming agent, and a leveling agent. May be.

The method for producing the photocurable resin composition of the present invention is not particularly limited. For example, the living radical is mixed using a mixer such as a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, or a three roll. Examples thereof include a method of mixing a copolymer, a photopolymerization initiator, and an additive such as a silane coupling agent added as necessary.

The photocurable resin composition of the present invention can be reliably cured without dripping by light irradiation, and has excellent adhesion to an adherend.
Although the use of the photocurable resin composition of this invention is not specifically limited, It is suitable for the use for electronic components, such as the sealing compound for liquid crystal display elements, and the interlayer filler for touchscreens especially.
The sealing agent for liquid crystal display elements which consists of the photocurable resin composition of this invention is also one of this invention.
An interlayer filler for a touch panel comprising the photocurable resin composition of the present invention is also one aspect of the present invention.

According to the present invention, a photocurable resin composition that can be reliably cured without dripping due to light irradiation and has excellent adhesion to an adherend, and the photocurable resin composition are used. The sealing agent for liquid crystal display elements and the interlayer filler for touch panels can be provided.

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

Example 1
(1) Preparation of living radical polymerization initiator represented by general formula (1) 6.38 g (50 mmol) of Tellurium (40 mesh, metal tellurium, manufactured by Aldrich) was suspended in 50 ml of tetrahydrofuran (THF). 34.4 ml (55 mmol) of a 1.6 mol / l n-butyllithium / hexane solution (manufactured by Aldrich) was slowly added dropwise at room temperature. The reaction solution was stirred until the metal tellurium disappeared completely. To this reaction solution, 10.7 g (55 mmol) of ethyl-2-bromo-isobutyrate was added at room temperature and stirred for 2 hours. After completion of the reaction, the solvent was concentrated under reduced pressure, followed by distillation under reduced pressure to obtain a yellow oily ethyl 2-methyl-2-n-butylteranyl-propionate (BTEE).

(2) Preparation of radical scavenger represented by general formula (3) 3.19 g (25 mmol) of Tellurium (40 mesh, metal tellurium, manufactured by Aldrich) was suspended in 25 ml of tetrahydrofuran (THF), and n-butyllithium was used. (Aldrich, 1.6M hexane solution) 17.2 ml (27.5 mmol) was slowly added over 10 minutes, keeping the reaction solution at 0 ° C. while cooling. The reaction solution was stirred until the metal tellurium disappeared completely.
To this reaction solution, 20 ml of ammonium chloride solution was added at room temperature and stirred for 1 hour. The organic layer was separated and the aqueous layer was extracted 3 times with diethyl ether. The organic layer separated and the extracted organic layer were combined, dried over sodium sulfate, and concentrated under reduced pressure to obtain black-purple oily di-n-butyl ditelluride (DBDT).

(3) Production of living radical copolymer 4.6 g of methacrylic monomer mixture deoxygenated by argon bubbling in advance (4.3 g of glycidyl methacrylate, 0.2 g of 2-hydroxyethyl methacrylate, 0.1 g of methyl methacrylate), argon bubbling in advance Then, 7.1 g of deoxygenated ethyl acetate was weighed into a reaction vessel in a glove box substituted with argon. Furthermore, in a glove box substituted with argon, the obtained BTEE 2100 μL, ADVN (manufactured by Wako Pure Chemical Industries) 230 mg as an azo polymerization initiator, and DBDT 940 μL as a radical scavenger were charged into the reaction container, Sealed and the reaction vessel was removed from the glove box. Thereafter, a polymerization reaction was carried out at 48 ° C. for 5 hours to obtain a living radical polymerization polymer-containing solution.
Next, 2.7 g of 1,6-hexanediol diacrylate (HDDA) previously bubbled with argon as a polyfunctional (meth) acrylic monomer was added, and a polymerization reaction was further performed at 48 ° C. for 19 hours to obtain a living radical copolymer. It was.

The obtained living radical copolymer was purified and dried with a hexane solvent, and then dissolved in a deuterated dimethyl sulfoxide solvent so as to be 5% by weight, and then it was dissolved in H-NMR (manufactured by Bruker). Measure the peak intensity of the protons of the glycidyl group proton and the double bond part of the (meth) acryloyl group. From the peak intensity ratio of the proton of the glycidyl group and the double bond part of the (meth) acryloyl group, one molecule When the number of introduced (meth) acryloyl groups was calculated, it was 1.2.

The resulting living radical copolymer was diluted 50-fold with tetrahydrofuran (THF), and the resulting diluted solution was filtered with a filter (material: polytetrafluoroethylene, pore size: 0.2 μm). The gel permeation chromatograph (manufactured by Waters, 2690 Separations Model) was supplied, and the gel permeation chromatography (GPC) measurement was performed under the conditions of a sample flow rate of 1 ml / min and a column temperature of 40 ° C. When measured, the number average molecular weight (Mn) was 800. In addition, GPC KF-806L (made by Showa Denko KK) was used as a column, and RI detector and UV detector were used as a detector.

(4) Production of photothermosetting resin composition 0.5 parts by weight of Irgacure 651 (manufactured by Tokyo Chemical Industry Co., Ltd.) as a photoradical initiator with respect to 100 parts by weight of the resulting living radical copolymer, thermal potential 20 parts by weight of Amicure PN23 (manufactured by Ajinomoto Fine Techno Co., Ltd.) as a curing agent and 1 part by weight of 1,6-hexanediol diacrylate as a photoreactive diluent are added, and a planetary stirrer (Shinky Corp. ) And then uniformly mixed with a ceramic three roll to obtain a photothermosetting resin composition.

( Examples 2, 3, 5, 6, 8, 9, Reference Examples 4 and 7 , Comparative Examples 1 to 4)
A living radical copolymer having the structure shown in Table 1 was prepared by adjusting the composition of the methacrylic monomer mixture, the addition amount of 6-hexanediol diacrylate, polymerization conditions, and the like, and Example 1 except that this was used. In the same manner as above, a photothermosetting resin composition was obtained.

(Comparative Example 5)
100 g of ethyl acetate as a polymerization solvent was added to the reaction vessel, and after bubbling with nitrogen, the reaction vessel was heated and refluxed while flowing nitrogen. Subsequently, a polymerization initiator solution in which 1.0 g of V-60 (2,2′-azobisisobutyronitrile, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator was diluted 10 times with ethyl acetate was placed in the reaction vessel. Then, 42 g of a methacrylic monomer mixture (6.5 g of glycidyl methacrylate, 19.5 g of 2-hydroxyethyl methacrylate, 16 g of methyl methacrylate) was added dropwise over 2 hours. After completion of the dropwise addition, the mixture was heated to reflux for 24 hours in order to complete the polymerization reaction and decompose the remaining polymerization initiator.
Thereafter, 1.1 g of acrylic acid and 0.01 g of triethylamine as a catalyst were added to the reaction solution, and the mixture was further heated under reflux for 2 hours to react a part of the glycidyl group in the polymer with the carboxyl group of acrylic acid. A free radical copolymer having an acryloyl group was obtained.
A photothermosetting resin composition was obtained in the same manner as in Example 1 except that the obtained free radical copolymer was used.

(Evaluation)
About the photothermosetting resin composition obtained by the Example, the reference example, and the comparative example, it evaluated by the following method.
The results are shown in Table 1.

(1) Photocurability evaluation The obtained photothermosetting resin composition was coated on glass so that the thickness after coating was 50 μm, and the irradiation dose of light having a wavelength of 405 nm was 3000 mJ / cm ² . It was irradiated with light.
Visual observation was performed after light irradiation, and the occurrence of dripping was evaluated according to the following criteria.
○: No dripping was observed even when the periphery of the coating film was observed.
X: Clear dripping was recognized in the peripheral part of the coating film.

Moreover, the adhesiveness of the coating film after photocuring was evaluated by the cross-cut method. That is, six grid-like (cross-cut) cuts reaching the glass at intervals of 1 mm were made in the coated film after photocuring. Then, it observed visually and evaluated by the following references | standards.
○: No peeling was observed in any lattice eye.
Δ: Although small peeling was observed at the intersection of the cuts, it was clearly 5% or less that was affected by the crosscut part.
X: Peeling was observed along the cut intersection and the edge of the cut, and the influence of the cross cut portion clearly exceeded 5%.

(2) Photothermosetting evaluation The obtained photothermosetting resin composition was applied onto glass so that the thickness after coating was 50 μm, and the irradiation dose of light having a wavelength of 405 nm was 3000 mJ / cm ² . After irradiating light so that it might become, it heated at 80 degreeC for 60 minutes further.
After the heat treatment, the surface of the coating was touched with a finger, and the presence or absence of stickiness was evaluated according to the following criteria.
○: There was no stickiness.
X: There was stickiness.

Moreover, the adhesiveness of the coating film after thermosetting was evaluated by the cross-cut method. That is, six grid-like (cross-cut) cuts reaching the glass at intervals of 1 mm were made in the coated film after photocuring. Then, it observed visually and evaluated by the following references | standards.
○: No peeling was observed in any lattice eye.
Δ: Although small peeling was observed at the intersection of the cuts, it was clearly 5% or less that was affected by the crosscut part.
X: Peeling was observed along the cut intersection and the edge of the cut, and the influence of the cross cut portion clearly exceeded 5%.

According to the present invention, a photocurable resin composition that can be reliably cured without dripping due to light irradiation and has excellent adhesion to an adherend, and the photocurable resin composition are used. The sealing agent for liquid crystal display elements and the interlayer filler for touch panels can be provided.

Claims (4)

A living radical copolymer having 0.8 to 1.4 (meth) acryloyl groups in one molecule and a number average molecular weight of 500 to 10,000, and a photoradical polymerization initiator ,
The living radical copolymer is composed of a (meth) acryl monomer and a polyfunctional (meth) acryl monomer, further has a glycidyl group, and has an epoxy equivalent of 200 to 2000. Curable resin composition. Furthermore, a thermosetting agent is contained, The photocurable resin composition of Claim 1 characterized by the above-mentioned . A sealant for a liquid crystal display element, comprising the photocurable resin composition according to claim 1 . An interlayer filler for a touch panel, comprising the photocurable resin composition according to claim 1 .