JP2011246548A - Curable resin composition and transparent film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable composition capable of forming a cured product excellent in hardness, flexibility, transparency, low birefringence and low linear expansion, and to provide a transparent film produced by curing the composition.SOLUTION: The curable resin composition comprises a reactive (meth)acrylate polymer (A) having a specific structure, a reactive monomer (B), silica fine particles (C) and a polymerization initiator (D), wherein the silica fine particles (C) are produced by surface-treating silica fine particles (C') free from surface-treatment with >50 pts.mass and ≤100 pts.mass of a silane compound (E) having a polymerizable unsaturated group based on 100 pts.mass of the silica fine particles (C').

Description

  The present invention relates to a curable composition that is cured by irradiation with active energy rays such as ultraviolet rays or heating, and a transparent film obtained by curing the composition. More specifically, the present invention relates to a curable composition capable of forming a cured product excellent in hardness, flexibility, transparency, low birefringence and low linear expansion coefficient, and a transparent film formed by curing the same. .

  In recent years, in applications such as protective coating materials, protective films, adhesives for various substrates, sealing materials, film-type liquid crystal elements, touch panels, and plastic optical components for preventing scratches and contamination of various substrate surfaces, hardness, There is a demand for a curable composition capable of forming a cured product excellent in flexibility, transparency, low birefringence and low linear expansion coefficient. Among these required performances, in recent years, compatibility between low linear expansion coefficient and low birefringence is particularly required.

  As a method for obtaining a cured film having good hardness and flexibility, for example, Patent Document 1 discloses a composition containing a reactive (meth) acrylate polymer having a specific structure, a reactive monomer, and surface-treated silica fine particles. It is disclosed that a cured film having good hardness, scratch resistance and flexibility can be produced by use. However, there is no disclosure about compatibility between low linear expansion coefficient and low birefringence.

WO2009 / 142237

  The present invention provides a curable composition capable of forming a cured product excellent in hardness, flexibility, transparency, low birefringence and low linear expansion coefficient, and a transparent film obtained by curing the curable composition. is there.

  As a result of intensive studies to solve the above problems, the present inventors have found that the reactive (meth) acrylate polymer (A) represented by the following general formula (1), the reactive monomer (B), the silica fine particles (C), And a polymerization initiator (D), wherein the silica fine particles (C) are treated with 50 parts by mass of silica fine particles (C ′) that are not surface-treated with respect to 100 parts by mass of the silica fine particles (C ′). The present invention was completed by finding that a curable resin composition obtained by surface treatment with a silane compound (E) having a polymerizable unsaturated group in an amount of more than 100 parts by mass and less than 100 parts by mass can solve the above problems. It came to do.

That is, the present invention is summarized as follows.
[1] The following general formula (1)

（Ｒ¹は水素原子、メチル基またはエチル基を表し、Ｒ²は素原子またはメチル基を表し、Ｘ¹は炭素数２〜１０の直鎖もしくは分岐の炭化水素基、炭素数２〜１０の直鎖もしくは分岐の炭化水素基の少なくとも２つをエステル結合で結合させて形成される原子団、または炭素数２〜１０の直鎖もしくは分岐の炭化水素基の少なくとも２つをエーテル結合で結合させて形成される原子団を表し、ｎは２から４の整数を表し、ｍは１〜５の整数を表す。）
で表されるモノマー単位を有する反応性（メタ）アクリレートポリマー（Ａ）、反応性モノマー（Ｂ）、シリカ微粒子（Ｃ）、及び重合開始剤（Ｄ）を含む組成物であって、
シリカ微粒子（Ｃ）が、表面処理されていないシリカ微粒子（Ｃ'）を、該シリカ微粒子（Ｃ'）１００質量部に対して５０質量部より多く１００質量部以下の、重合性不飽和基を有するシラン化合物（Ｅ）によって表面処理して得られたものである
ことを特徴とする硬化性樹脂組成物。
［２］前記一般式（１）で表されるモノマー単位が、下記一般式（２）

(R ¹ represents a hydrogen atom, a methyl group or an ethyl group, R ² represents an elementary atom or a methyl group, X ¹ represents a linear or branched hydrocarbon group having 2 to 10 carbon atoms, An atomic group formed by bonding at least two linear or branched hydrocarbon groups with an ester bond, or at least two linear or branched hydrocarbon groups having 2 to 10 carbon atoms with an ether bond. And n represents an integer of 2 to 4, and m represents an integer of 1 to 5.)
A composition comprising a reactive (meth) acrylate polymer (A) having a monomer unit represented by formula (A), a reactive monomer (B), silica fine particles (C), and a polymerization initiator (D),
Silica fine particles (C) are composed of silica fine particles (C ′) that have not been surface-treated with a polymerizable unsaturated group in an amount of more than 50 parts by mass and less than 100 parts by mass with respect to 100 parts by mass of the silica fine particles (C ′). A curable resin composition obtained by surface treatment with a silane compound (E).
[2] The monomer unit represented by the general formula (1) is represented by the following general formula (2):

（式（２）中、Ｒ¹、Ｒ²、Ｘ¹およびｍは、それぞれ前記式（１）におけるＲ¹、Ｒ²、Ｘ¹およびｍと同様の意味を示す。）
で表されるモノマー単位であることを特徴とする［１］に記載の硬化性組成物。
［３］前記一般式（２）で表されるモノマー単位が、下記一般式（３）、（４）または（５）で表されるモノマー単位であることを特徴とする［２］に記載の硬化性組成物。

(In the formula (2), R ¹ , R ² , X ¹ and m have the same meanings as R ¹ , R ² , X ¹ and m in the formula (1), respectively.)
The curable composition according to [1], which is a monomer unit represented by the formula:
[3] The monomer unit represented by the general formula (2) is a monomer unit represented by the following general formula (3), (4) or (5), Curable composition.

（式（３）中、Ｒ¹、Ｒ²は一般式（２）と同様の意味を示し、ｐは１〜３０の整数を表す。）

(In the formula ^{(3), R 1, R} 2 represents the same meaning as the general formula (2), p represents an integer of 1 to 30.)

（式（４）中、Ｒ¹およびＲ²は、それぞれ前記式（２）におけるＲ¹およびＲ²と同様の意味を示し、Ｒ³およびＲ⁴は、それぞれ独立してメチル基または水素原子であり、Ｒ³とＲ⁴とが同じ基になることはなく、ｐは１〜３０の整数を表す。）

(In formula (4), R ¹ and R ² have the same meanings as R ¹ and R ² in formula (2), respectively, and R ³ and R ⁴ are each independently a methyl group or a hydrogen atom. Yes, R ³ and R ⁴ are not the same group, and p represents an integer of 1 to 30.)

（式（５）中、Ｒ¹およびＲ²は、それぞれ一般式（２）におけるＲ¹およびＲ²と同様の意味を示し、Ｒ⁵は炭素数２〜４の直鎖または分岐のアルキレン基を表し、ｑは１〜３０の整数を表す。）

(In the formula (5), R ¹ and R ² have the same meanings as R ¹ and R ² in the general formula (2), respectively, and R ⁵ represents a linear or branched alkylene group having 2 to 4 carbon atoms. And q represents an integer of 1 to 30.)

[4] The reactive monomer (B) is trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta ( The curable resin composition according to any one of [1] to [3], which is at least one selected from the group consisting of (meth) acrylate and dipentaerythritol hexa (meth) acrylate.
[5] The silane compound (E) having a polymerizable unsaturated group is at least one selected from compounds represented by the following general formulas (13) and (14): [1] to [1] 4]. The curable composition according to any one of [4].

（式（１３）中、Ｒ¹²は水素原子又はメチル基を表し、Ｒ¹⁴は炭素数１〜３のアルキル基又はフェニル基を表し、Ｒ¹³は水素原子又は炭素数１〜１０の炭化水素基を表し、ｒは０〜２の整数であり、ｓは１〜６の整数である。）

(In the formula (13), R ¹² represents a hydrogen atom or a methyl group, R ¹⁴ represents an alkyl group having 1 to 3 carbon atoms or a phenyl group, and R ¹³ represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. Where r is an integer from 0 to 2 and s is an integer from 1 to 6.

（式（１４）中、Ｒ¹³、Ｒ¹⁴、ｒおよびｓは、それぞれ上記式（１３）におけるＲ¹³、Ｒ¹⁴、ｒおよびｓと同様の意味を表し、Ｒ¹⁵は（メタ）アクリロイルオキシ基含有アルコールのアルコール残基を表す。
［６］［１］〜［５］に記載の硬化性樹脂組成物を硬化させてなる透明フィルム。

(In the formula (14), R ¹³ , R ¹⁴ , r and s represent the same meaning as R ¹³ , R ¹⁴ , r and s in the formula (13), respectively, and R ¹⁵ represents a (meth) acryloyloxy group. The alcohol residue of the contained alcohol is represented.
[6] A transparent film obtained by curing the curable resin composition according to [1] to [5].

  According to the present invention, a composition comprising a specific reactive (meth) acrylate polymer (A), a reactive monomer (B), silica fine particles (C), and a polymerization initiator (D), comprising silica fine particles ( C) is a silane compound having a polymerizable unsaturated group in which the silica fine particles (C ′) that are not surface-treated are more than 50 parts by mass and less than 100 parts by mass with respect to 100 parts by mass of the silica fine particles (C ′). By using the curable resin composition obtained by surface treatment according to (E), a cured product excellent in hardness, flexibility, transparency, low birefringence and low linear expansion coefficient is formed. And a transparent film formed by curing the curable composition.

  Hereinafter, the present invention will be described in detail. In the present specification, expressions such as (meth) acrylate all mean methacrylate and / or acrylate. Further, the cis / trans relationship in describing the structure is not particularly distinguished, and any of them is meant. Further, “residue” used in the text refers to a partial structure excluding a specific structure. For example, a hydroxyl group residue of ethanol refers to an ethyl group portion obtained by removing a hydroxyl group from ethanol. Moreover, the ester bond residue which reacted with the acetic acid in ethanol shall represent the ethyl group remove | excluding the ester bond part from the skeleton derived from ethanol.

<Reactive (meth) acrylate polymer (A)>
The reactive (meth) acrylic polymer (A) of the present invention has at least a monomer unit represented by the general formula (1).

式（１）中、Ｒ¹は水素原子、メチル基またはエチル基を表し、Ｒ²は素原子またはメチル基を表し、Ｘ¹は炭素数２〜１０の直鎖もしくは分岐の炭化水素基、炭素数２〜１０の直鎖もしくは分岐の炭化水素基の少なくとも２つをエステル結合で結合させて形成される原子団、または炭素数２〜１０の直鎖もしくは分岐の炭化水素基の少なくとも２つをエーテル結合で結合させて形成される原子団を表し、ｎは２から４の整数を表し、ｍは１〜５の整数を表す。

In the formula (1), R ¹ represents a hydrogen atom, a methyl group or an ethyl group, R ² represents an elementary atom or a methyl group, X ¹ represents a linear or branched hydrocarbon group having 2 to 10 carbon atoms, carbon An atomic group formed by connecting at least two linear or branched hydrocarbon groups of 2 to 10 with an ester bond, or at least two of linear or branched hydrocarbon groups of 2 to 10 carbon atoms It represents an atomic group formed by bonding with an ether bond, n represents an integer of 2 to 4, and m represents an integer of 1 to 5.

  Of the above structure (1), the following formula (2) is preferred.

（式（２）中、Ｒ¹、Ｒ²、Ｘ¹およびｍは、それぞれ前記式（１）におけるＲ¹、Ｒ²、Ｘ¹およびｍと同様の意味を示す。）
の構造が挙げられ、更に好ましくは下記一般式（３）、（４）および（５）の構造が挙げられる。

(In the formula (2), R ¹ , R ² , X ¹ and m have the same meanings as R ¹ , R ² , X ¹ and m in the formula (1), respectively.)
More preferred are the structures of the following general formulas (3), (4) and (5).

（式（３）中、Ｒ¹およびＲ²は、それぞれ一般式（２）におけるＲ¹およびＲ²と同様の意味を示し、ｐは１〜３０の整数を表す。）

(In formula (3), R ¹ and R ² have the same meanings as R ¹ and R ² in general formula (2), respectively, and p represents an integer of 1 to 30.)

（式（４）中、Ｒ¹およびＲ²は、それぞれ前記式（２）におけるＲ¹およびＲ²と同様の意味を示し、Ｒ³およびＲ⁴は、それぞれ独立してメチル基または水素原子であり、Ｒ³とＲ⁴とが同じ基になることはなく、ｐは１〜３０の整数を表す。）

(In formula (4), R ¹ and R ² have the same meanings as R ¹ and R ² in formula (2), respectively, and R ³ and R ⁴ are each independently a methyl group or a hydrogen atom. Yes, R ³ and R ⁴ are not the same group, and p represents an integer of 1 to 30.)

（式（５）中、Ｒ¹およびＲ²は、それぞれ一般式（１）におけるＲ¹およびＲ²と同様の意味を示し、Ｒ⁵は炭素数２〜４の直鎖または分岐のアルキレン基を表し、ｑは１〜３０の整数を表す。）
また、下記一般式（６）または（７）で表される構造のモノマー単位を有する反応性（メタ）アクリルポリマー（Ａ）も使用することができる。

(In the formula (5), R ¹ and R ² each have the same meaning as R ¹ and R ² in the general formula (1), and R ⁵ represents a linear or branched alkylene group having 2 to 4 carbon atoms. And q represents an integer of 1 to 30.)
Moreover, the reactive (meth) acrylic polymer (A) which has a monomer unit of the structure represented by the following general formula (6) or (7) can also be used.

（式中、Ｒ¹およびＲ²は、それぞれ一般式（２）におけるＲ¹およびＲ²と同様の意味を示す。）

(In the formula, R ¹ and R ² have the same meanings as R ¹ and R ² in formula (2), respectively).

（式中、Ｒ¹およびＲ²は、それぞれ一般式（２）におけるＲ¹およびＲ²と同様の意味を示す。）

(In the formula, R ¹ and R ² have the same meanings as R ¹ and R ² in formula (2), respectively).

  The weight average molecular weight in terms of polystyrene measured by GPC of the reactive (meth) acrylic polymer (A) of the present invention is 1000 to 100,000, preferably 2000 to 70000, more preferably 2500 to 50000. If the weight average molecular weight is less than 1000, it is difficult to fully exhibit the toughness specific to the copolymer polymer, and if it exceeds 100,000, the viscosity is high, which may impair the coatability of the resin composition. .

  By containing the reactive (meth) acrylate polymer (A) in the curable composition, a cured product having an excellent balance between flexibility and surface hardness can be obtained. That is, high quality is achieved for various products made of the cured product of the present invention.

  The reactive (meth) acrylate polymer (A) is obtained by homopolymerizing an isocyanate compound represented by the following formula (8) with another compound having a carbon-carbon double bond using the carbon-carbon double bond. After polymerizing and synthesizing a (meth) acrylic homopolymer or (meth) acrylic copolymer, it can be obtained by reacting the polymer with an alcohol having a (meth) acryloyloxy group. The isocyanate compound of the following formula (8) is an unsaturated group-containing isocyanate compound having a polyethylene glycol skeleton, and among them, 2- (2-methacryloyloxy) ethoxyethyl isocyanate is preferable.

（式（８）中、Ｒ¹およびｎは、それぞれ式（１）におけるＲ¹およびｎと同様の意味を表す。）

(In Formula (8), R ¹ and n represent the same meaning as R ¹ and n in Formula (1), respectively).

  Therefore, the polymerization unit of the (meth) acrylic (co) polymer contains the compound of the general formula (8) as an essential component, and (a1) a (meth) acrylic compound having another isocyanate group, if necessary, (a2 A) a (meth) acrylic compound having an alicyclic skeleton or a heterocyclic skeleton, and (a3) a compound having another carbon-carbon double bond may be included as a copolymer unit. In the present specification, the (co) polymer means a copolymer or a homopolymer.

  Examples of the compound of (a1) include 2- (meth) acryloyloxyethyl isocyanate, 3- (meth) acryloyloxypropyl isocyanate, 4- (meth) acryloylbutyl isocyanate, 5- (meth) acryloyloxypentyl isocyanate, Examples include 6- (meth) acryloyloxyhexyl isocyanate, 3- (meth) acryloyloxyphenyl isocyanate, and 4- (meth) acryloyloxyphenyl isocyanate, but other (meth) acrylic compounds having an isocyanate group. These may be used alone, or these may be used alone or in combination of two or more.

  Examples of the compound (a2) include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) ) Acrylate, cycloalkyl (meth) acrylate such as morpholinyl (meth) acrylate, adamantyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  Of these, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, morpholinyl (meth) acrylate, and adamantyl (meth) acrylate are preferred from the viewpoint of high glass transition point and high strength, and tricyclodecanyl. (Meth) acrylate is most preferred.

  The copolymerization ratio of the compound (a1) is not particularly limited, but from the viewpoint of achieving both strength and flexibility, the total of the compound of the general formula (8) and the compound (a1) is (meta ) It is preferable that it is 40 mol% or more with respect to the whole monomer which comprises an acrylic (co) polymer, and also it is preferable that it is 80 mol% or more. When the total of the compound of Formula (8) and the compound of (a1) is less than 40 mol%, the crosslinking density of the cured product cannot be sufficiently obtained, and the strength may be insufficient.

  Regarding the ratio of the compound of general formula (8) to the compound of (a1), the ratio of the compound of (a1) to the compound of general formula (8) is preferably 80% by mass or less, and further 75 It is preferable that it is below mass%.

  Although it does not specifically limit as a copolymerization ratio of the compound of (a2), 60 mol% or less with respect to the whole monomer which comprises a (meth) acryl (co) polymer from a viewpoint of coexistence of intensity | strength and a softness | flexibility. Furthermore, it is preferable that it is 20 mol% or less. When the copolymerization ratio of the compound (a2) exceeds 60 mol%, there is a possibility that a sufficient crosslinking density may not be obtained, and further the solubility of the reactive (meth) acrylate polymer (A) is reduced, or the crystal May be improved and handling may be reduced.

  (A3) Examples of other compounds having a carbon-carbon double bond include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-tert-butylstyrene, and o-chloro. Styrene, m-chlorostyrene, p-chlorostyrene, 1,1-diphenylethylene, p-methoxystyrene, N, N-dimethyl-p-aminostyrene, N, N-diethyl-p-aminostyrene, ethylenically unsaturated Ethylenically unsaturated aromatic compounds such as pyridine and ethylenically unsaturated imidazole; carboxyl group-containing compounds such as (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid; methyl (meth) acrylate, ethyl (meta ) Acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate , Butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, amyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) Acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) Alkyl (meth) acrylates such as acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate; trifluoroethyl (meth) Fluoroalkyl (meth) acrylates such as acrylate, tetrafluoropropyl (meth) acrylate, hexafluoroisopropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate; hydroxyethyl (meth) acrylate , Hydroxyalkyl (meth) acrylates such as hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate; phenoxyalkyl (meth) such as phenoxyethyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate Acrylates: methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxye Alkoxyalkyl (meth) acrylates such as ru (meth) acrylate and methoxybutyl (meth) acrylate; polyethylene glycol mono (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meta ) Acrylate, polyethylene glycol (meth) acrylates such as nonylphenoxypolyethylene glycol (meth) acrylate; polypropylene glycol mono (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, nonylphenoxypolypropylene glycol ( Polypropylene glyco such as (meth) acrylate (Meth) acrylates; cyclohexyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentadienyl (meth) acrylate, bornyl (Meth) acrylate, isobornyl (meth) acrylate, cycloalkyl (meth) acrylates such as tricyclodecanyl (meth) acrylate; benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, etc. May be used alone, or two or more may be used in combination.

  Although it does not specifically limit as a copolymerization ratio of the compound of (a3), From the reason similar to the case of said (a2), with respect to the whole monomer which comprises a (meth) acryl (co) polymer. It is preferably 60 mol% or less, and more preferably 20 mol% or less.

  A chain transfer agent may be used in combination for the synthesis of the (meth) acrylic (co) polymer. Although there is no restriction | limiting in particular as a chain transfer agent to be used, It is preferable to use the compound which has a mercapto group from a viewpoint of the reactivity or the characteristic of resin. Specifically, monofunctional thiol compounds such as 2-mercaptoethanol, mercaptobenzene, dodecyl mercaptan, the following general formula (9)

（式（ＩＸ）中、Ｒ⁷は多官能アルコール化合物のアルコール残基を表し、Ｒ⁸、Ｒ⁹はそれぞれ独立して水素原子または炭素数１〜４のアルキル基を表し、好ましくは水素原子あるいはメチル基である。Ｘ³、Ｘ⁴はそれぞれ独立して単結合か炭素数１〜３の直鎖または分岐のアルキレン基であり、ｌは２〜１０の整数を表し、好ましくは２〜４である。）で表される多官能チオール化合物が挙げられる。

(In formula (IX), R ⁷ represents an alcohol residue of the polyfunctional alcohol compound, R ⁸ and R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a hydrogen atom or X ³ and X ⁴ each independently represents a single bond or a linear or branched alkylene group having 1 to 3 carbon atoms, and l represents an integer of 2 to 10, preferably 2 to 4. A polyfunctional thiol compound represented by:

  There is no restriction | limiting in particular as said polyfunctional alcohol, Arbitrary polyfunctional alcohol compounds can be used preferably. Specific examples include alkyl glycols such as ethylene glycol and 1,4-butanediol, trimethylolpropane, tris (2-hydroxyethyl) isocyanurate, pentaerythritol, ditrimethylolpropane, and dipentaerythritol. It is not limited.

  Moreover, the copolymer which has a branched structure can be obtained by using a tri- or more functional chain transfer agent. Since the viscosity of the resin decreases in the branched polymer, the handling property of the reactive (meth) acrylate polymer (A) can be improved.

  Solvents used for the synthesis of (meth) acrylic (co) polymers include ester solvents such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and ethylene glycol monobutyl ether acetate, toluene, xylene, etc. The aromatic hydrocarbon solvent can be preferably used.

  The reaction temperature during the synthesis of the (meth) acrylic (co) polymer is usually 60 ° C to 130 ° C, preferably 70 ° C to 125 ° C, more preferably 75 ° C to 120 ° C. If the reaction temperature is lower than 60 ° C, the polymerization initiator may not sufficiently perform its function, and if it is higher than 130 ° C, the isocyanate group may be destroyed.

  Examples of the polymerization initiator used for the synthesis of the (meth) acrylic (co) polymer include an azo initiator and a peroxide initiator. From the viewpoint of the stability of the isocyanate group, the azo initiator is used. And specifically azobisisobutyronitrile, 2,2-azobis- (2,4-dimethylvaleronitrile), and dimethyl-2,2-azobis- (2-methylpropionate). Etc.

  As an alcohol compound having a (meth) acryloyloxy group (hereinafter also referred to as “(meth) acryloyloxy group-containing alcohol”) used for introducing an unsaturated group into a (meth) acrylic (co) polymer, specifically, Are 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 4-hydroxy Butyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, caprolactone-modified diol mono (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate , Pentaerythritol triacrylate, and dipentaerythritol penta acrylate, not limited thereto. Moreover, you may use together alcohol which does not have unsaturated groups, such as butanol, in order to adjust content of an unsaturated group.

  Specific examples of the catalyst that can be used for the reaction of the isocyanate group in the isocyanate compound of the general formulas (8) and (a1) and the active hydrogen group in the alcohol compound having a (meth) acryloyloxy group include dibutyltin. Examples include dilaurate, copper naphthenate, cobalt naphthenate, lithium naphthenate, triethylamine, and 1,4-diazabicyclo [2.2.2] octane. These urethanization catalysts may be used individually by 1 type, and may be used in combination of 2 or more type.

  The addition amount of the catalyst is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 1 part by mass with respect to 100 parts by mass in total of the isocyanate compound of the general formula (8) and the isocyanate compound of (a1). It is. When the addition amount of the urethanization catalyst is less than 0.01 parts by mass, the reactivity may be significantly lowered. On the other hand, when the addition amount of the urethanization catalyst exceeds 5 parts by mass, a side reaction may occur during the reaction.

As the solvent used for the reaction between the isocyanate group and the active hydrogen group, the solvent used in the copolymerization reaction is preferably used from the economical viewpoint.
The reaction temperature suitable for the reaction between the isocyanate group and the active hydrogen group is 20 ° C to 100 ° C, preferably 25 ° C to 90 ° C, more preferably 30 ° C to 80 ° C. If the reaction temperature is lower than 20 ° C, unreacted isocyanate groups may remain, and if it exceeds 100 ° C, gelation or undesired coloring may occur.

The double bond equivalent of the reactive (meth) acrylate polymer (A) of the present invention is preferably 100 to 1000 g / mol, more preferably 120 to 850 g / mol, and 140 to 700 g / mol. Most preferred. When the double bond equivalent is greater than 1000 g / mol, the film strength may be reduced, and when it is less than 100 g / mol, the curing shrinkage may be increased. The double bond equivalent was defined as the following formula. The molecule of this formula corresponds to the mass of the reactive (meth) acrylate polymer (A).
Double bond equivalent = [mass of all monomers (g) + mass of polymerization initiator (g) + mass of all alcohol (g)] / [used for reaction with (meth) acrylic (co) polymer (meta ) Amount of acryloyloxy group-containing alcohol (mol) x number of unsaturated groups in (meth) acryloyloxy group-containing alcohol]

The urethane equivalent of the reactive (meth) acrylate polymer (A) of the present invention is preferably 100 to 1000 g / mol, more preferably 120 to 850 g / mol, and 140 to 700 g / mol. Is most preferred. When the urethane equivalent is larger than 1000 g / mol, the film strength may be lowered. When the urethane equivalent is smaller than 100 g / mol, the viscosity is increased or crystallization is likely to occur, and the handling property may be lowered. The urethane equivalent was defined as the following formula.
Urethane equivalent = [mass of all monomers (g) + mass of polymerization initiator (g) + mass of all alcohol (g)] / [(meth) acryloyl used for reaction with (meth) acrylic (co) polymer Amount of oxy group-containing alcohol (mol)]

  When a urethane (meth) acrylate compound is further used as a copolymerization component, the amount (mol) of the urethane (meth) acrylate compound is added to the denominator of the above urethane equivalent formula.

  The curable resin composition of the present invention becomes a curable composition suitable for a coating agent, for example, by blending other components than the (A) reactive (meth) acrylate polymer. Specific examples of each are shown below.

<Reactive monomer (B)>
The reactive monomer (B) is a compound that is polymerized or cross-linked by radicals generated from a photopolymerization initiator when irradiated with actinic rays, or a compound that is polymerized or cross-linked by heating. By copolymerizing the reactive (meth) acrylate polymer (A) and the reactive monomer (B), a crosslinked product is obtained, and the curable composition of the present invention is cured. The reactive monomer (B) is also called a reactive diluent, and has a role of adjusting the viscosity of the composition, adjusting the curability, and the like. Examples of the reactive monomer (B) include compounds having one or more carbon-carbon double bonds, and specifically, (meth) acrylic acid esters, epoxy (meth) acrylates, or urethane (meth). Acrylates are preferably used.

Specific examples of (meth) acrylic acid esters include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di ( (Meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di Diacrylates such as (meth) acrylate, tricyclodecane di (meth) acrylate, bisphenol A di (meth) acrylate;
Trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) Polyfunctional (meth) acrylates such as acrylate, tris (2- (meth) acryloyloxyethyl) isocyanurate,
And ethylene oxide-modified and propylene oxide-modified products thereof.

  Epoxy (meth) acrylates can be obtained by reacting a known epoxy compound with a carboxylic acid having an unsaturated group. Specific examples of the epoxy compound include glycidyl (meth) acrylate, glycidylpropyltrimethoxysilane, glycidyl ether at both ends of a linear alcohol having 1 to 12 carbon atoms, diethyleneglycol diglycidyl ether, and tripropylene glycol diglycidyl ether. Bisphenol A diglycidyl ether, ethylene oxide modified bisphenol A diglycidyl ether, propylene oxide modified bisphenol A diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, hydrogenated bisphenol A diglycidyl ether, glycerin diglycidyl ether Etc. Examples of the carboxylic acid having an unsaturated group include (meth) acrylic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and the like.

  The epoxy compound and the carboxylic acid having an unsaturated group can be easily reacted by a conventionally known method. For rapid progress of the reaction, a compound represented by phosphines such as triphenylphosphine is used as a catalyst. Can also be used.

  Particularly preferred epoxy (meth) acrylates include 2-hydroxy-3-methacryloyloxypropyl methacrylate and 2-hydroxy-3-acryloyloxypropyl which are reaction products of glycidyl (meth) acrylate and (meth) acrylic acid. A methacrylate etc. can be mentioned.

  Urethane (meth) acrylates can be reacted with known alcohol compounds, thiol compounds or amine compounds with unsaturated group-containing isocyanates, or with known polyols and polyisocyanates in excess of isocyanate groups. Is obtained by reacting an alcohol compound having an unsaturated group with respect to the terminal isocyanate, for example, a (meth) acryloyloxy group-containing alcohol.

  Examples of the reaction product of known alcohol compounds and unsaturated group-containing isocyanates include compounds represented by the following general formulas (10), (11) and (12).

（式中、Ｒ¹⁰は水素原子またはメチル基を表し、Ｒ¹¹は酸素原子、硫黄原子またはＮＨ基を表し、Ｘ⁵は脂肪族基および芳香族基から選ばれる一種の基を表し、ｍは一般式（１）におけるｍと同様の意味を示し、ｐは１または２を示す。）

(Wherein R ¹⁰ represents a hydrogen atom or a methyl group, R ¹¹ represents an oxygen atom, a sulfur atom or an NH group, X ⁵ represents a kind of group selected from an aliphatic group and an aromatic group, (It represents the same meaning as m in the general formula (1), and p represents 1 or 2.)

（式中、Ｒ¹⁰は炭素数１〜１０の直鎖または分岐のアルキル基であり、Ｒ¹¹は酸素原子、硫黄原子またはＮＨ基を表し、Ｘ⁵は脂肪族基、芳香族基および複素環基から選ばれる一種の基を表し、ｍは一般式（１）におけるｍと同様の意味を示す。）

(In the formula, R ¹⁰ represents a linear or branched alkyl group having 1 to ¹⁰ carbon atoms, R ¹¹ represents an oxygen atom, a sulfur atom or an NH group, and X ⁵ represents an aliphatic group, an aromatic group or a heterocyclic ring. Represents a kind of group selected from groups, and m represents the same meaning as m in formula (1).)

（式中、Ｒ¹⁰は炭素数１〜１０の直鎖または分岐のアルキル基であり、Ｒ¹¹は酸素原子、硫黄原子またはＮＨ基を表し、Ｘ⁵は脂肪族基、芳香族基および複素環基から選ばれる一種の基を表し、ｍは一般式（１）におけるｍと同様の意味を示す。）

(In the formula, R ¹⁰ represents a linear or branched alkyl group having 1 to ¹⁰ carbon atoms, R ¹¹ represents an oxygen atom, a sulfur atom or an NH group, and X ⁵ represents an aliphatic group, an aromatic group or a heterocyclic ring. Represents a kind of group selected from groups, and m represents the same meaning as m in formula (1).)

  Specific examples of known alcohol compounds include (meth) acryloyloxy group-containing alcohols such as 2-hydroxyethyl acrylate, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol. Glycerin, polyglycerin, tris (2-hydroxyethyl) isocyanurate, 1,3,5-trihydroxypentane, 1,4-dithian-2,5-dimethanoltricyclodecanediol, trimethylolpropane, pentaerythritol, Ditrimethylolpropane, dipentaerythritol, norbornanedimethanol, polycarbonate diol, polysiloxane diol, bisphenol A, purple olcoalcohol, and their EO-modified, PO-modified, caprolactone Gender body and the like.

  Moreover, as a well-known thiol compound, C1-C12 linear both-terminal dithiol, 2,4,6-mercapto-S-triazine, butanediol bis (3-mercaptopropionate), trimethylolpropane (3 -Mercaptopropionate), isocyanuric tris (3-mercaptopyropionate), pentaerythritol tetra (3-mercaptopropionate), butanediol bis (3-mercaptobutyrate), trimethylolpropane (3-mercaptobutyrate) ), Isocyanuryl tris (3-mercaptobutyrate), pentaerythritol tetra (3-mercaptobutyrate) and the like.

  On the other hand, as the unsaturated group-containing isocyanate compound, 2- (meth) acryloyloxyethyl isocyanate, 4- (meth) acryloyloxybutyl isocyanate, 5- (meth) acryloyloxypropyl isocyanate, 6- (meth) acryloyloxyhexyl isocyanate 2,2-bis (acryloyloxymethyl) ethyl isocyanate, 1,1-bis (acryloyloxymethyl) methyl isocyanate, 3-acryloyloxyphenyl isocyanate, 4-acryloyloxyphenyl isocyanate, 2- (2- (meth) acrylic Yloxyethoxy) ethyl isocyanate and the like.

  Moreover, as content of the reactive monomer (B) in curable resin composition, 1 mass part-300 mass parts are preferable with respect to 100 mass parts of reactive (meth) acrylate polymer (A), 10 mass parts -200 mass parts is still more preferable. If the reactive monomer is less than 1 part by mass, the crosslinking density may be lowered and the hardness may be insufficient. If it exceeds 300 parts by mass, flexibility may be impaired due to an increase in the crosslinking density.

<Silica fine particles (C)>
As the silica fine particles (C) used in the present invention, those having an average particle diameter of 1 to 100 nm can be suitably used. When the average particle diameter is less than 1 nm, the viscosity of the prepared curable composition increases, the content of the silica fine particles (C) in the curable composition is limited, and in the curable composition Dispersibility deteriorates, and a cured product obtained by curing a curable composition (hereinafter, also simply referred to as a cured product) tends not to have sufficient heat resistance. On the other hand, when the average particle diameter exceeds 100 nm, appearance performance and mechanical properties may be deteriorated.

  The average particle diameter of the silica fine particles (C) is more preferably 1 to 50 nm, further preferably 5 to 50 nm, and most preferably 5 to 40 nm from the viewpoint of adjusting the viscosity of the curable composition to a suitable value. The average particle diameter of the silica fine particles (C) was observed with a high-resolution transmission electron microscope (H-9000 type, manufactured by Hitachi, Ltd.), and 100 particle images were arbitrarily selected from the observed fine particle images. The number average particle diameter can be obtained by a known image data statistical processing method.

  The content of silica fine particles (C) in the curable composition is preferably 20 to 80% by mass, from the viewpoint of the balance between the heat resistance and environmental resistance of the cured product and the viscosity of the curable composition, More preferably, it is 50-80 mass%. If the content is 20% by mass or less, a cured product having a low coefficient of linear expansion may not be obtained, and if it exceeds 80% by mass, dispersibility may be impaired, and molding of the cured product may be difficult.

  Silica fine particles (C) are preferably used in a state of being dispersed in an organic solvent from the viewpoint of dispersibility in the curable composition. As the organic solvent, the reactive (meth) acrylate polymer (A), the reactive monomer (B), the silica fine particles (C), the polymerization initiator (D) and the like contained in the curable resin composition are dissolved or well dissolved. What can be dispersed is preferably used.

  Examples of the organic solvent include alcohols, ketones, esters, and glycol ethers. Alcohols such as methanol, ethanol, isopropyl alcohol, butyl alcohol, and n-propyl alcohol are preferable because of easy adjustment of the amount of solvent. Ketone-based organic solvents such as methacrylic acid, methyl ethyl ketone and methyl isobutyl ketone are preferred.

  Such silica fine particles (C) dispersed in an organic solvent can be produced by a conventionally known method, and are also commercially available, for example, under the trade name Snowtech IPA-ST (manufactured by Nissan Chemical Co., Ltd.). Can be synthesized as raw materials.

The silica fine particles (C) used in the present invention are obtained by surface-treating silica fine particles (C ′) that are not surface-treated with a silane compound (E) having a polymerizable unsaturated group. It is obtained by surface treatment with a silane compound having an aromatic ring as necessary.
Each of these silane compounds will be described below.

<Silane compound having polymerizable unsaturated group (E)>
The silane compound (E) having a polymerizable unsaturated group used in the present invention is a silane compound having a vinyl group, a (meth) acryloyl group or a (meth) acryloyloxy group. A silane compound (E1) having an unsaturated group represented or a silane compound (E2) having an unsaturated group and a urethane bond represented by the following general formula (14) can be suitably used.

[Silane compound (E1)]
The silane compound (E1) is represented by the following general formula (13).

上記式（１３）中、Ｒ¹²は水素原子又はメチル基を表し、Ｒ¹⁴は炭素数１〜３のアルキル基又はフェニル基を表し、Ｒ¹³は水素原子又は炭素数１〜１０の炭化水素基を表し、ｒは０〜２の整数であり、ｓは１〜６の整数である。

In the above formula (13), R ¹² represents a hydrogen atom or a methyl group, R ¹⁴ represents an alkyl group or phenyl group having 1 to 3 carbon atoms, R ¹³ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms , R is an integer of 0-2, and s is an integer of 1-6.

From the viewpoints of viscosity reduction and storage stability of the curable composition, preferred R ¹² is a methyl group, preferred R ¹⁴ is a methyl group, preferred s is 3, and preferred r is 0.
The silane compound (E1) reduces the viscosity of the curable composition and at the same time improves the dispersion stability of the silica fine particles (C) in the curable composition, and is cured when the curable composition is cured. It is used for reducing shrinkage and imparting moldability to the cured product. That is, when the silica fine particles (C ′) are not surface-treated with the silane compound (E1) having an unsaturated group, the viscosity of the curable composition is increased and the curing shrinkage at the time of curing is increased. Since it becomes brittle and cracks occur in the cured product, it is not preferable.

  Examples of the silane compound (E1) include γ-acryloxypropyldimethylmethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-acryloxypropyldiethylmethoxysilane, γ-acryloxypropylethyldimethoxysilane, and γ-acryloxy. Propyltrimethoxysilane, γ-acryloxypropyldimethylethoxysilane, γ-acryloxypropylmethyldiethoxysilane, γ-acryloxypropyldiethylethoxysilane, γ-acryloxypropylethyldiethoxysilane, γ-acryloxypropyltriethoxy Silane, γ-methacryloxypropyldimethylmethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyldiethylmethoxysilane, γ-methacryloxy Cypropylethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyldimethylethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyldiethylethoxysilane, γ-methacryloxypropylethyldi Examples thereof include ethoxysilane and γ-methacryloxypropyltriethoxysilane.

Among these, γ-acryloxypropyldimethylmethoxysilane, γ-acrylic silane, from the viewpoint of preventing aggregation of the silica fine particles (C) in the curable composition, reducing the viscosity of the curable composition, and improving storage stability. Roxypropylmethyldimethoxysilane, γ-methacryloxypropyldimethylmethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-acryloxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane are preferable, and γ- Methacryloxypropyltrimethoxysilane. Moreover, these can be used in combination of 2 or more types.
Moreover, such a silane compound (E1) can be manufactured by a well-known method, and is marketed.

[Silane compound (E2)]
The silane compound (E2) used in the present invention is represented by the following general formula (14).

上記の式（１４）中、Ｒ¹³、Ｒ¹⁴、ｒおよびｓは、それぞれ一般式（１３）におけるＲ¹³、Ｒ¹⁴、ｒおよびｓと同様の意味を表し、Ｒ¹⁵は、（メタ）アクリロイルオキシ基含有アルコールのアルコール残基を表す。

In the above formula ^{(14), R 13, R} 14, r and s each represent the same meaning as R ^13, R ^14, r and s in the general formula (13), R ¹⁵ is (meth) acryloyl It represents an alcohol residue of an oxy group-containing alcohol.

  The silane compound (E2) can be obtained by reacting an isocyanate compound having an alkoxysilyl group with the (meth) acryloyloxy group-containing alcohol. The silane compound (E2) is used to improve dispersion stability of the silica fine particles (C) in the curable composition and to reduce curing shrinkage when the curable composition is cured. Further, by using the silane compound (E2), the toughness of the cured product and the reactivity of the unsaturated group can be increased by the aggregation effect derived from the hydrogen bond of the urethane bond in the molecule.

  Examples of the isocyanate compound having an alkoxysilyl group used for the synthesis of the silane compound (E2) include trimethylsilylpropyl isocyanate and triethoxysilylpropyl isocyanate.

  The catalyst that can be used for the reaction of the isocyanate group of the isocyanate compound having an alkoxysilyl group and the active hydrogen group of the (meth) acryloyloxy group-containing alcohol, the addition amount of the catalyst, and the solvent that can be used are the above-mentioned general formula (8) And a catalyst that can be used in the reaction of an isocyanate group in the isocyanate compound of (a1) and an active hydrogen group in an alcohol compound having a (meth) acryloyloxy group, the addition amount of the catalyst, and a solvent that can be used Things can be used.

[Silane compound having an aromatic ring]
The silane compound having an aromatic ring used in the present invention is represented by the following general formula (15).

上記式（１５）中、Ｒ¹³、Ｒ¹⁴、ｒおよびｓは、それぞれ一般式（１３）におけるＲ¹³、Ｒ¹⁴、ｒおよびｓと同様の意味を表す。一般式（１５）に示す構造の左端に存在するフェニル基には、本発明の効果を損なわない範囲で置換基が結合していてもよい。

In the above formula (15), R ^13, R ^14, r and s each represent the same meaning as R ^13, R ^14, r and s in the general formula (13). A substituent may be bonded to the phenyl group present at the left end of the structure represented by the general formula (15) as long as the effects of the present invention are not impaired.

From the viewpoint of reducing the viscosity of the curable composition and storage stability, preferred R ¹⁴ is a methyl group, preferred s is 0 or 1, and preferred r is 0. When r is not 0, preferred R ¹³ is a methyl group. When the silica particles react with the silane compound having an aromatic ring, hydrophobicity is imparted to the surface of the silica particles, the dispersibility of the silica particles in the organic solvent is improved, the viscosity of the curable composition is reduced, and the curing is performed. The storage stability of the composition is improved.

  Examples of the silane compound having an aromatic ring include phenyldimethylmethoxysilane, phenylmethyldimethoxysilane, phenyldiethylmethoxysilane, phenylethyldimethoxysilane, phenyltrimethoxysilane, phenyldimethylethoxysilane, phenylmethyldiethoxysilane, and phenyldiethylethoxy. Silane, phenylethyldiethoxysilane, phenyltriethoxysilane, benzyldimethylmethoxysilane, benzylmethyldimethoxysilane, benzyldiethylmethoxysilane, benzylethyldimethoxysilane, benzyltrimethoxysilane, benzyldimethylethoxysilane, benzylmethyldiethoxysilane, benzyl Diethylethoxysilane, benzylethyldiethoxysilane, and benzyltriethoxy Run, and the like.

  From the viewpoint of improving the environmental resistance including the reduction of the viscosity of the curable composition, the improvement of storage stability, and the reduction of water absorption, phenyldimethylmethoxysilane, phenylmethyldimethoxysilane, phenyldiethylmethoxysilane, phenylethyldimethoxysilane Phenyltrimethoxysilane is preferred, and phenyltrimethoxysilane is more preferred. These silane compounds can be used in combination of two or more.

  The amount of the silane compound (E) having a polymerizable unsaturated group in the surface treatment of the silica fine particles is more than 50 parts by mass and 100 parts by mass with respect to 100 parts by mass of the silica fine particles (C ′) not subjected to the surface treatment. The following is preferable, more than 50 parts by mass and more preferably 85 parts by mass or less, and more preferably more than 50 parts by mass and 70 parts by mass or less. When the usage-amount of the silane compound (E) which has a polymerizable unsaturated group is 50 mass parts or less, the viscosity of a curable composition will become high and the dispersibility in the curable composition of a silica fine particle (C) will become. It may worsen and cause gelation. Moreover, when it exceeds 100 mass parts, aggregation of a silica fine particle (C) may be caused. The total amount of the silane compound (E) having a polymerizable unsaturated group and the silane compound having an aromatic ring is preferably more than 50 parts by mass and 100 parts by mass or less with respect to 100 parts by mass of the silica fine particles (C ′).

<Polymerization initiator (D)>
Examples of the polymerization initiator (D) used in the present invention include a photopolymerization initiator that generates radicals and a thermal polymerization initiator. These may be used alone or in combination.

  Examples of the photopolymerization initiator include benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxy-phenylphenyl ketone, 2,6-dimethylbenzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine. Oxides and diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide. Two or more of these photopolymerization initiators may be used in combination.

  The content of the photopolymerization initiator in the curable composition may be an amount that appropriately cures the curable composition, and is 0.01 to 10% by mass with respect to the entire curable composition. More preferably, it is 0.02-5 mass%, More preferably, it is 0.1-2 mass%. If the addition amount of the photopolymerization initiator is too large, the storage stability of the curable composition is lowered, colored, or the crosslinking at the time of crosslinking to obtain a cured product rapidly proceeds, such as cracks during curing. In addition to problems, there is a risk of increasing the outgas component during high temperature processing and contaminating the equipment. On the other hand, when there is too little addition amount of a photoinitiator, there exists a possibility that hardening of a curable composition may become inadequate.

  Examples of the thermal polymerization initiator include benzoyl peroxide, diisopropyl peroxycarbonate, t-butylperoxy (2-ethylhexanoate), 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di ( t-butylperoxy) cyclohexane, 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane, t-hexylperoxysopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy 3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxysopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl- 2,5-di ( Nzoylperoxy) hexane, t-butylperoxyacetate, 2,2-di (t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl-4,4-di (t-butylperoxy) valerate, di ( 2-t-butylperoxyisopropyl) benzene, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, di -T-hexyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetra Methylbutyl hydroperoxide, cumene hydroperoxide, t-butyl Hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile) ), Dimethyl-2,2′-azobis (2-methylpropionate), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2 2′-azobis (N- (2-propenyl) -2-methylpropionamide, 1-((1-cyano-1-methylethyl) azo) formamide, 2,2′-azobis (N-butyl-2) -Methylpropionamide), 2,2′-azobis (N-cyclohexyl-2-methylpropionamide) and the like.

The content of the thermal polymerization initiator in the curable resin composition is the same as in the case of the above-described photopolymerization initiator.
Moreover, you may use together a photoinitiator and a thermal-polymerization initiator.

<Other ingredients>
The curable composition of the present invention includes a reactive (meth) acrylate polymer (A), a reactive monomer (B), silica fine particles (C), a polymerization initiator (D), and components that are components of the curable resin composition. A silane compound (E) is dispersed. Moreover, a solvent can be added to these for the purpose of adjusting the viscosity of the composition.

  As the solvent to be used, an organic solvent is preferable, and examples thereof include alcohols, ketones, esters, and glycol ethers. Among them, alcohol-based solvents such as ethanol, isopropyl alcohol, butyl alcohol, and n-propyl alcohol, and ketone-based organic solvents such as methyl ethyl ketone and methyl isobutyl ketone are preferable because of the dispersion of the composition and the ease of adjusting the viscosity.

  The boiling point of the solvent is preferably 50 to 150 ° C, more preferably 70 to 120 ° C. Moreover, 2000 mass parts or less are preferable with respect to 100 mass parts of reactive (meth) acrylate polymers (A), and, as for content of the solvent in curable resin composition, 1000 mass parts or less are still more preferable. When the amount of the solvent is more than 2000 parts by mass, the viscosity is excessively lowered, and the handling property may be deteriorated.

  In addition, the curable resin composition of the present invention includes, as necessary, a fluorescent brightening agent, a surfactant, a plasticizer, a flame retardant, an antioxidant, an ultraviolet absorber, a foaming agent, an antifungal agent, and an antistatic agent. , Magnetic materials, conductive materials, antibacterial / bactericidal materials, porous adsorbents, fragrances, adhesion improvers such as silane coupling agents and acidic phosphate esters, curing accelerators, dyes, fillers, thixotropic agents, leveling An additive may be added, and preferred additives include antioxidants, ultraviolet absorbers, antistatic agents, leveling agents and the like.

  In particular, the antioxidant can suppress the thermal degradation of the cured product, can exhibit an effect of reducing outgas, and can contribute to heat resistance. Specifically, hindered phenolic antioxidants such as Sumilizer GM manufactured by Sumitomo Chemical Co., Ltd. and Irganox 1135 manufactured by Ciba Japan Co., Ltd. can be preferably used.

<Method for producing curable resin composition, curing method>
The curable composition of this invention can be mix | blended and prepared as follows.
Mix the reactive (meth) acrylate polymer (A), reactive monomer (B), silica fine particles (C), polymerization initiator (D) and silane compound (E) used in the present invention at room temperature or under heating conditions. They can be mixed with a mixer such as a ball mill or three rolls, or can be mixed and prepared by adding a solvent or the like as a diluent and dissolving.

  Although it does not restrict | limit especially as a hardening method of said curable resin composition, For example, after apply | coating said curable composition on a base material and forming a coating film, whether to irradiate with radiation or to heat Further, it can be cured by using a combination of irradiation and heating.

  Examples of the coating method include coating by a die coater, spin coater, spray coater, curtain coater, roll coater, etc., coating by screen printing, dipping, and the like.

The thickness of the coating film is preferably set to a value in the range of 1 to 200 μm, but can be appropriately set depending on the application.
The radiation used for curing is not particularly limited, but an electron beam or a light source in the range from ultraviolet to infrared is preferable. For example, an ultra-high pressure mercury or metal halide light source can be used for ultraviolet rays, a metal halide or halogen light source can be used for visible rays, and a halogen light source can be used for infrared rays, but other light sources such as lasers and LEDs can also be used. . If infrared rays are used, thermal curing can be performed. The radiation dose can also be appropriately set according to the type of light source, the film thickness of the coating film, and the like.

  Through such a curing process, a transparent film or a transparent sheet can be produced.

Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited by these examples.
(1) Preparation of components of curable resin composition
[Production Example 1]: Synthesis of Reactive (Meth) acrylate Polymer (A): (P-1) To a four-necked flask equipped with a dropping funnel, thermometer, condenser, and stirrer, propylene glycol monomethyl ether acetate ( (Hereinafter referred to as PGMAC) 210.1 g was charged, and the inside of the four-necked flask was purged with nitrogen for 1 hour. Furthermore, after heating to 100 ° C. in an oil bath, 24.9 g of 2- (2-methacrylyloxy) ethoxyethyl isocyanate, 19.4 g of 2-methacryloyloxyethyl isocyanate, dimethyl-2, 2-azobis (2- A mixed solution of 7.3 g of methyl propionate (hereinafter referred to as V-601) was dropped over 2 hours. After stirring for 30 minutes, a mixture of 0.9 g of V-601 and 2.7 g of PGMAC was added and stirred for 3 hours. The mixture was further heated to 120 ° C. and polymerized for 1 hour, and then up to 40 ° C. Cooled down. Here, after air substitution in the flask, 0.2 g of 3,5-tertiarybutyl-4-hydroxytoluene was added as a polymerization inhibitor. After stirring for 3 minutes, 0.4 g of dibutyltin dilaurate and 29.0 g of 2-hydroxyethyl acrylate were added to this solution and stirred for 1 hour. Here, a reactive (meth) acrylate polymer having an unsaturated group in the side chain (by confirming the disappearance of the 2250 cm ⁻¹ peak characteristic of isocyanate using an infrared spectrometer) A) was synthesized and designated as (P-1). The weight average molecular weight in terms of polystyrene measured by GPC was 8,000.

In this case, the double bond equivalent is
Double bond equivalent = [mass of all monomers (g) + mass of polymerization initiator (g) + mass of all alcohol (g)] / [used for reaction with (meth) acrylic (co) polymer (meta ) Amount of acryloyloxy group-containing alcohol (mol) x number of unsaturated groups in (meth) acryloyloxy group-containing alcohol]
= [[24.9 (g) +19.4 (g)] + [7.3 (g) +0.9 (g)] + [29.0 (g)]]
/[29.0(g)/116.12(g/mol)]
= 326
Urethane equivalent is
Urethane equivalent = [mass of all monomers (g) + mass of polymerization initiator (g) + mass of all alcohol (g)] / [(meth) acryloyl used for reaction with (meth) acrylic (co) polymer Amount of oxy group-containing alcohol (mol)]
= [[24.9 (g) +19.4 (g)] + [7.3 (g) +0.9 (g)] + [29.0 (g)]]
/[29.0(g)/116.12(g/mol)]
= 326
Met.

[Production Example 2]: Synthesis of reactive (meth) acrylate polymer (A): (P-2) 2- (2-methacrylyloxy) ethoxyethyl isocyanate 24.9 g in Production Example 1 was changed to 39.8 g. 2-methacryloyloxyethyl isocyanate 19.4 g was changed to 31.0 g, 2-hydroxyethyl acrylate 29.0 g was changed to 46.9 g, and solvent, polymerization initiator, polymerization inhibitor and catalyst dibutyl A reactive (meth) acrylate polymer (A) was synthesized in the same manner as in Production Example 1 except that the amount of tin dilaurate added was changed to the amount shown in Table 1, and this was designated as (P-2). The weight average molecular weight in terms of polystyrene measured by GPC was 20,000.
In this case, both the double bond equivalent and the urethane equivalent were 300.

[Production Example 3]: Synthesis of reactive (meth) acrylate polymer (A): (P-3) 24.9 g of 2- (2-methacrylyloxy) ethoxyethyl isocyanate in Production Example 1 was changed to 19.9 g. 2-methacryloyloxyethyl isocyanate 19.4 g was changed to 2-methacryloyloxyethyl isocyanate 15.5 g and tricyclodecanyl methacrylate 44.1 g, 2-hydroxyethyl acrylate 29.0 g was changed to 23.0 g Further, the reactive (meth) acrylate polymer (A) was prepared in the same manner as in Production Example 1 except that the amount of the solvent, polymerization initiator, polymerization inhibitor, and catalyst dibutyltin dilaurate was changed to the amount shown in Table 1. ) And synthesized as (P-3). The weight average molecular weight in terms of polystyrene measured by GPC was 15,000.

In this case, the double bond equivalent and the urethane equivalent were both 540.
Table 1 shows the production conditions of Production Examples 1, 2, and 3, and the molecular weight, double bond equivalent, and urethane equivalent of the synthesized reactive (meth) acrylate polymer (A).

[Production Example 4]: Surface treatment of silica fine particles (1): (M-1)
In a separable flask, 280.0 g (100 parts by mass) of isopropyl alcohol-dispersed colloidal silica (silica content 15% by mass, average particle size 9 to 15 nm, trade name Snowtech IPA-ST-UP; manufactured by Nissan Chemical Co., Ltd.) Of this, 42 g) of silica is added, 12.6 g (4.5 parts by mass) of γ-methacryloxypropyltrimethoxysilane is added to the separable flask, and the mixture is stirred and mixed. Further, 4.5 g of 0.1825% by mass HCl solution is added. (1.6 parts by mass) was added, and the mixture was stirred at room temperature for 24 hours, whereby surface treatment of the silica fine particles was performed to obtain a silica fine particle dispersion (M-1). The disappearance due to hydrolysis of γ-methacryloxypropyltrimethoxysilane was confirmed by gas chromatography (Model 6850, manufactured by Agilent). Using nonpolar column DB-1 (manufactured by J & W), temperature 50-300 ° C., heating rate 10 ° C./min, using He as carrier gas, flow rate 1.2 cc / min, for flame ionization detector The internal standard method was used. γ-Methacryloxypropyltrimethoxysilane disappeared 8 hours after the addition of the HCl solution.
Further, the solid content concentration of the obtained silica fine particle dispersion (M-1) was 18.7%.

[Production Example 5]: Surface treatment of silica fine particles (2): (M-2)
The same operation as in Production Example 4 was carried out except that 12.6 g of γ-methacryloxypropyltrimethoxysilane was changed to 25.2 g and 4.5 g of 0.1825 wt% HCl solution was changed to 9.0 g. The obtained silica fine particle dispersion was designated as (M-2). Further, the solid content concentration of the obtained silica fine particle dispersion (M-2) was 22.0%.

[Production Example 6]: Surface treatment of silica fine particles (3): (M-3)
Except that 12.6 g of γ-methacryloxypropyltrimethoxysilane was changed to 25.2 g of HEMA-TEPI obtained in Production Example 8 described later, and 4.5 g of 0.1825 mass% HCl solution was changed to 9.0 g. The same operation as in Production Example 4 was performed, and the resulting silica fine particle dispersion was designated as (M-3). Moreover, the obtained silica fine particle dispersion (solid content concentration of M-3) was 22.0%.
The production conditions of Production Examples 4 to 6 are shown in Table 2.

[Production Example 7]: Synthesis of reactive monomer (B): HEA-AOI
In a reaction vessel, 2-hydroxyethyl acrylate (Osaka Organic Chemical Co., Ltd.) 100 parts (31.3 g) and BHT (Pure Chemical Co., Ltd.) 200 ppm-containing hexane (Pure Chemical Co., Ltd.) 142 parts by mass (44.4 g) and 2.8 parts by mass (0.9 g) of dibutyltin dilaurate (Tokyo Chemical Industry Co., Ltd.) were added and stirred. Thereafter, 122 parts by mass (38.1 g) of 2-acryloyloxyethyl isocyanate (manufactured by Showa Denko KK) was gradually added dropwise and stirred at room temperature. The reaction was terminated after confirming that the raw materials were almost disappeared by high performance liquid chromatography, and then washed 4 times with 203 parts by mass (63.5 g) of hexane containing BHT 200 ppm to reactivities of urethane (meth) acrylates. A urethane compound (HEA-AOI) belonging to the monomer (B) was obtained.

[Production Example 8]: Synthesis of silane compound (E) having a polymerizable unsaturated group: HEMA-TEPI
In a reaction vessel filled with 100 g of methylene chloride solution, 13.8 parts by mass (50.0 g) of 2-hydroxyethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) and trimethoxysilylpropyl isocyanate (trade name: KBM-9007 Shin-Etsu Chemical Co., Ltd.) 23.5 parts by mass (85.1 g) and 0.3 parts by mass (1.1 g) of dibutyltin dilaurate (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and stirred at room temperature for 24 hours. Here, an infrared spectrometer is used to confirm that the 2250 cm ⁻¹ peak peculiar to the isocyanate has disappeared, and the reaction is terminated, whereby the urethane belonging to the silane compound (E2) having an unsaturated group and a urethane bond. A compound (HEMA-TEPI) was synthesized.

(2) Preparation of curable resin composition (Example 1)
10.3 parts by mass (0.16 g) of the reactive (meth) acrylate polymer (P-1) synthesized in Production Example 1, and 1310 parts by mass of silica fine particle dispersion (M-2) prepared in Production Example 4 (20. 0 g), 10.3 parts by mass (0.16 g) of the reactive monomer (B) (HEA-AOI) synthesized in Production Example 6, and trimethylolpropane triacrylate (trade name: Biscote) as the other reactive monomer (B) # 295; Osaka Organic Chemical Co., Ltd.) 100 parts by mass (1.53 g) and tricyclodecane diacrylate (product name: IRR-214K, manufactured by Daicel Chemical Industries, Ltd.) 20.2 parts (0.31 g) were mixed. Furthermore, 2-hydroxy-2-methyl-1-phenylpropan-1-one (product name: Darocur 1173 manufactured by Ciba Specialty Chemicals) 12.9 as a photopolymerization initiator 8.6 parts by mass (0.13 g) of phenylglyoxyc acid methyl ester (product name: Speed Cure MBF manufactured by LAMBSON) and stirring with a stirrer for 24 hours at room temperature during light shielding By doing this, the curable resin composition (C-1) was obtained.

(Examples 2 to 5, Comparative Example 1)
Table 3 shows the compositions of the curable resin compositions C-1 to C-5 and R-1 prepared in the same manner.

(3) Sample evaluation The sample evaluation method is described below. The evaluation results are shown in Table 3.

<Manufacture of cured film>
The curable composition solutions of Examples 1 to 5 and Comparative Example 1 were applied to separate glass substrates (50 mm × 50 mm) in a film form by dipping and rolling so that the thickness of the cured film was 100 μm, and 100 ° C. After removing the solvent completely by drying for 1 hour at 1 J / cm ² with an exposure device (trade name: UV-SYSTEM CSN2-40, manufactured by GS Yuasa Co., Ltd.) incorporating an ultra-high pressure mercury lamp, the coating film is cured. To make a film. The film thickness was 100 μm. The following evaluation was performed on these films.

<Pencil hardness>
Based on the method described in JIS K5600, pencil hardness was measured using a surface property measuring machine (manufactured by Shinto Kagaku Co., Ltd.).

<Average coefficient of linear expansion (CTE)>
Using a TMA / SS120C type thermal stress strain measuring device manufactured by Seiko Electronics Co., Ltd., in the presence of nitrogen, the temperature of the film is increased from 30 ° C. to 400 ° C. at a rate of 5 ° C. for 1 minute and held for 20 minutes. From the dimensional change between 30 ° C. and 230 ° C., the linear expansion coefficient at each temperature was obtained, and averaged to calculate the average linear expansion coefficient (CTE). The load was 5 g and the measurement was performed in the tensile mode. The measurement was performed by fixing both ends of the sample using a uniquely designed quartz tension chuck (material: quartz, coefficient of linear expansion of 0.5 ppm).

<Total light transmittance>
The total light transmittance was measured using a spectrophotometer U3200 (manufactured by Hitachi, Ltd.).

<Birefractive index (Retardation): Rth>
The birefringence (retardation) was measured using an automatic birefringence meter KOBRA-21H (manufactured by Oji Scientific Instruments) and the measurement method using the KOBRA method (parallel Nicol rotation method). The measurement was performed at room temperature.

<Flexibility>
A metal wire having a diameter of 6φ was prepared, and it was evaluated whether or not the film was broken when the film was wound around the metal wire by 180 ° at room temperature. This test was repeated 5 times for each film. If the number of breaks in 5 times was 0, “no break” (notation “◯”), and 1 to 2 times “slightly break” (notation (Triangle | delta)) If it was 3 times or more, it was set as "breaking" (notation x).

  From Table 3, the silica fine particles (C) obtained by surface treatment with 60 parts by mass of the silane compound (E) having a polymerizable unsaturated group, which is an amount larger than 50 parts by mass with respect to 100 parts by mass of the silica fine particles. The composition used is superior in low linear expansion coefficient compared to a composition using silica fine particles obtained by surface treatment with 30 parts by mass of a silane compound (E) having a polymerizable unsaturated group, hardness, It turns out that it is excellent also in the balance with a softness | flexibility, transparency, and low birefringence property.

Claims (6)

The following general formula (1)

(R ¹ represents a hydrogen atom, a methyl group or an ethyl group, R ² represents a hydrogen atom or a methyl group, X ¹ represents a linear or branched hydrocarbon group having 2 to 10 carbon atoms, or 2 to 10 carbon atoms. An atomic group formed by bonding at least two linear or branched hydrocarbon groups with an ester bond, or at least two linear or branched hydrocarbon groups having 2 to 10 carbon atoms with an ether bond. And n represents an integer of 2 to 4, and m represents an integer of 1 to 5.)
A composition comprising a reactive (meth) acrylate polymer (A) having a monomer unit represented by formula (A), a reactive monomer (B), silica fine particles (C), and a polymerization initiator (D),
Silica fine particles (C) are composed of silica fine particles (C ′) that have not been surface-treated with a polymerizable unsaturated group in an amount of more than 50 parts by mass and less than 100 parts by mass with respect to 100 parts by mass of the silica fine particles (C ′). A curable resin composition obtained by surface treatment with a silane compound (E). The monomer unit represented by the general formula (1) is represented by the following general formula (2)

(In the formula (2), R ¹ , R ² , X ¹ and m have the same meanings as R ¹ , R ² , X ¹ and m in the formula (1), respectively.)
The curable composition according to claim 1, wherein the curable composition is a monomer unit represented by the formula: The curable composition according to claim 2, wherein the monomer unit represented by the general formula (2) is a monomer unit represented by the following general formula (3), (4) or (5). object.

(In formula (3), R ¹ and R ² have the same meanings as R ¹ and R ² in general formula (2), respectively, and p represents an integer of 1 to 30.)

(In formula (4), R ¹ and R ² have the same meanings as R ¹ and R ² in formula (2), respectively, and R ³ and R ⁴ are each independently a methyl group or a hydrogen atom. Yes, R ³ and R ⁴ are not the same group, and p represents an integer of 1 to 30.)

(In the formula (5), R ¹ and R ² have the same meanings as R ¹ and R ² in the general formula (2), respectively, and R ⁵ represents a linear or branched alkylene group having 2 to 4 carbon atoms. And q represents an integer of 1 to 30.)   Reactive monomer (B) is trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate The curable resin composition according to claim 1, wherein the curable resin composition is at least one selected from the group consisting of dipentaerythritol hexa (meth) acrylate. The silane compound (E) having a polymerizable unsaturated group is at least one selected from the compounds represented by the following general formulas (13) and (14). The curable composition according to 1.

(In the formula (13), R ¹² represents a hydrogen atom or a methyl group, R ¹⁴ represents an alkyl group having 1 to 3 carbon atoms or a phenyl group, and R ¹³ represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. Where r is an integer from 0 to 2 and s is an integer from 1 to 6.

(In the formula (14), R ¹³ , R ¹⁴ , r and s represent the same meaning as R ¹³ , R ¹⁴ , r and s in the formula (13), respectively, and R ¹⁵ represents a (meth) acryloyloxy group. The alcohol residue of the contained alcohol is represented.   The transparent film formed by hardening the curable resin composition in any one of Claims 1-5.