JP2023103095A - Silica sol containing long-chain alkylene group-containing epoxy compound - Google Patents

Abstract

To provide a silica sol with high dispersion stability which comprises a long-chain alkylene group-containing epoxy compound as a dispersion medium, which is in liquid form and has high handleability, and exhibits high heat resistance and tenacity when cured, and silica particles as a dispersoid, dispersed therein, a method for producing the same, and a cured body-forming composition, and a cured body thereof.SOLUTION: A silica sol comprises a dispersion medium comprising an epoxy compound (A) represented by the formula (1), and a dispersoid comprising silica particles (B) with an average particle size of 5-500 nm by dynamic light scattering (where L1-L3 each represent a C2 to 7 hydrocarbon group, and R1-R3 each represent a hydrogen atom or a methyl group).SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a silica sol in which silica particles are dispersed in a long-chain alkylene group-containing epoxy compound, a method for producing the same, a composition for forming a cured product for curing the silica sol, and a cured product thereof.

Epoxy resins have characteristics such as high adhesiveness, high electrical insulation, and high heat resistance, and attempts have been made to add silica particles to improve abrasion resistance, volumetric contraction rate, and expansion rate.

In addition, tris-(2,3-epoxypropyl)-isocyanurate, which is an isocyanuric acid-based epoxy resin, is an epoxy resin having isocyanuric acid as a core and three glycidyl groups in one molecule, and is a non-aromatic epoxy resin, so it has high transparency and high weather resistance derived from the triazinetrione skeleton, so it is used for LED materials and the like. Inorganic oxide particles such as silica are also added to these tris-(2,3-epoxypropyl)-isocyanurates.
For example, disclosed is a liquid epoxy resin composition containing a modified liquid epoxy resin compound, inorganic oxide particles such as silica, and a curing agent (see Patent Document 1).

On the other hand, tris-(2,3-epoxypropyl)-isocyanurate with high crystallinity has high heat resistance and is excellent in application to fields using high temperatures, but molding methods such as casting need to be devised. Epoxy compounds in which the alkylene chain from the triazinetrione ring to the epoxy ring is extended in order to impart high handleability, high heat resistance, and toughness have also been produced (see Patent Documents 2 and 3).

Further, addition of metal oxides such as titanium oxide, aluminum oxide and zirconium oxide to these epoxy compounds for improving the refractive index is disclosed (see Patent Document 4).

International publication pamphlet WO2009/008509 International pamphlet WO2010/092947 International pamphlet WO2017/082356 JP 2008-007782

The present invention provides a silica sol having high dispersion stability in which silica particles are dispersed as a dispersoid in an epoxy compound containing a long-chain alkylene group, which is liquid and has high handleability, high heat resistance and toughness when cured, as a dispersion medium, a method for producing the same, a composition for forming a cured body, and a cured body thereof.

As a first aspect of the present invention, a silica sol containing a dispersion medium containing an epoxy compound (A) represented by the following formula (1) and a dispersoid containing silica particles (B) having an average particle size of 5 to 500 nm by a dynamic light scattering method,

(In Formula (1), L ¹ to L ³ each represent a hydrocarbon group having 2 to 7 carbon atoms, and R ¹ to R ³ each represent a hydrogen atom or a methyl group.),
As a second aspect, the epoxy compound (A) of formula (1) is the silica sol according to the first aspect, wherein each of L ¹ to L ³ has a hydrocarbon group having 3 to 7 carbon atoms and is a liquid epoxy compound;
As a third aspect, the silica sol according to the first aspect or the second aspect, wherein the silica particles (B) contain alkoxy groups consisting of methoxy groups or ethoxy groups on their surfaces, and the alkoxy groups are bonded at a rate of 0.6 to 3.0 pieces/ ^nm2 ;
As a fourth aspect, formulas (2) to (4) in which the silica particles (B) are silane compounds having an organic group directly bonded to a silicon atom:

(In the formula (2), each R ¹ is an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, or cyano group and is bonded to a silicon atom via a Si—C bond, each R ² represents an alkoxy group, an acyloxy group, or a halogen group, a represents an integer of 1 to 3,
In formulas (3) and (4), R ³ and R ⁵ are each an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms and are bonded to a silicon atom via a Si—C bond; R ⁴ and R ⁶ each represent an alkoxy group, an acyloxy group, or a halogen group; Y represents an alkylene group, an NH group, or an oxygen atom; b is an integer of 1 to 3; is. )
The silica sol according to any one of the first to third aspects, which is coated with at least one silane compound selected from the group consisting of
As a fifth aspect, the silica sol according to any one of the first aspect to the fourth aspect, which has a silica concentration of 60% by mass and a viscosity after storage at 50° C. for 14 days in a range of 1.0 to 30 times the value of the viscosity at 25° C. of only the dispersion medium used in the silica sol;
As a sixth aspect, the silica sol according to any one of the first to fifth aspects, wherein the dispersion medium further contains a liquid epoxy compound other than formula (1);
As a seventh aspect, the silica sol according to the sixth aspect, wherein the liquid epoxy other than formula (1) is a non-cyanuric acid liquid epoxy compound;
As an eighth aspect, the silica sol according to the seventh aspect, wherein the non-cyanuric acid-based liquid epoxy compound is a bisphenol-based epoxy compound or an alicyclic epoxy compound;
As a ninth aspect, the silica sol according to any one of the first aspect to the eighth aspect, further containing a basic substance consisting of amine, ammonia, an inorganic alkali compound, or a quaternary ammonium compound;
As a tenth aspect, a cured body-forming composition containing the silica sol and a curing agent according to any one of the first to ninth aspects,
As an eleventh aspect, the cured body-forming composition according to the tenth aspect, wherein the curing agent is an acid anhydride, an amine, or an acid generator;
As a twelfth aspect, a cured product formed from the cured product-forming composition according to the tenth aspect,
As a thirteenth aspect, the following steps (I) to (III):
(I) step: step (I) of producing a silica sol using methanol or ethanol as a dispersion medium;
(II) step: step (II) of mixing the silica sol obtained in step (I) and epoxy compound (A) represented by formula (1) to obtain silica sol;
(III) Step: The method for producing a silica sol according to any one of the first to ninth aspects, including the step of removing methanol or ethanol from the silica sol obtained in the (II) step,
As a fourteenth aspect, the method for producing a silica sol according to the thirteenth aspect, further comprising the step of adding a basic substance selected from amines, ammonia, inorganic alkali compounds, or quaternary ammonium compounds when step (I) uses methanol or ethanol as a dispersion medium for the silica sol.
As a fifteenth aspect, the method for producing a silica sol according to the thirteenth aspect, wherein step (I) further comprises a step of coating the silica particles with at least one silane compound selected from the group consisting of formulas (2) to (4) when the dispersion medium of the silica sol is methanol or ethanol; The method for producing a silica sol according to the thirteenth aspect, further comprising the step of replacing the sol with an organic solvent having a carbonyl structure, an ether structure, or a carbon-carbon bond structure.

A cured product of a long-chain alkylene group-containing epoxy compound is liquid, has high handling properties, and has high heat resistance and toughness (large bending change rate) when cured, compared to alicyclic epoxy resins, aromatic epoxy resins, and short-chain alkylene group-containing epoxy compounds.
The above properties can be obtained by introducing a long-chain alkylene group between the triazinetrione ring and the epoxy ring. However, when adding inorganic oxide particles such as silica to further improve physical properties (bending elastic modulus improvement), it is necessary to devise silica particles due to changes in the properties of the epoxy compound due to the long-chain alkylene group.

The present invention provides a silica sol having high dispersion stability in which silica particles are dispersed as a dispersoid in an epoxy compound containing a long-chain alkylene group, which is liquid and has high handleability, high heat resistance and toughness when cured, as a dispersion medium. The silica sol of the present invention is characterized by high stability and low rate of change in viscosity even after long-term storage at high temperatures.

For example, in tris-(2,3-epoxypropyl)-isocyanurate, the ethylene group having one carbon atom extends from the triazinetrione ring to the epoxy ring. On the other hand, the long-chain alkylene group-containing epoxy compounds used in the present invention have different physical properties because the alkylene chain from the triazinetrione ring to the epoxy ring has 2 to 7 carbon atoms.

In the present invention, by devising the silica particles, a stable silica sol having a high dispersion stability in which silica particles are dispersed as dispersoids in an epoxy compound containing a long-chain alkylene group as a dispersion medium and has an average particle size of 5 to 500 nm due to dynamic light scattering properties was obtained. Silica particles have methoxy groups or ethoxy groups on their surfaces, and the presence of these alkoxy groups in a specific proportion on the surfaces of the silica particles improves the compatibility between the epoxy compound and the silica particles. Therefore, even when stored at a high concentration and at a high temperature, the viscosity change is small and stable. By using these stable silica sols, the cured body-forming composition has high handleability, and the cured body has high heat resistance, toughness (large bending change rate), and improved bending elastic modulus.

In the long-chain alkylene group-containing epoxy compound, since the epoxy ring is separated from the triazinetrione ring, the degree of freedom of the epoxy ring is increased, and the curability and cationic polymerizability of the epoxy ring are improved. Therefore, not only curing with an acid or amine but also cationic polymerization with an acid generator (thermal acid generator or photoacid generator) is possible. An organic-inorganic hybrid material having high heat resistance and toughness can be obtained by incorporating silica particles.

The present invention is a silica sol containing a dispersion medium containing an epoxy compound (A) represented by the following formula (1) and a dispersoid containing silica particles (B) having an average particle size of 5 to 500 nm as determined by a dynamic light scattering method.
In formula (1), L ¹ to L ³ each represent a hydrocarbon group having 2 to 7 carbon atoms, and R ¹ to R ³ each represent a hydrogen atom or a methyl group.
The epoxy compound (A) of formula (1) is preferably a liquid epoxy compound in which each of L ¹ to L ³ has a hydrocarbon group of 3 to 7 carbon atoms. These epoxy compounds preferably have curability and polymerizability (especially cationic polymerizability).

式（１）においてＬ ^１ ～Ｌ ^３はそれぞれ炭素原子数２～７の炭化水素基とは、炭素原子数２～７の直鎖又は分岐を有するアルキレン基であり、例えば、エチレン基、ｎ－プロピレン基、イソプロピレン基、シクロプロピレン基、ｎ－ブチレン基、イソブチレン基、ｓ－ブチレン基、t－ブチレン基、シクロブチレン基、１－メチル－シクロプロピレン基、２－メチル－シクロプロピレン基、ｎ－ペンチレン基、ｎ－ヘキシレン基、ｎ－ヘプチレン基、１－メチル－ｎ－ブチレン基、２－メチル－ｎ－ブチレン基、３－メチル－ｎ－ブチレン基、１,１－ジメチル－ｎ－プロピレン基、１,２－ジメチル－ｎ－プロピレン基、２,２－ジメチル－ｎ－プロピレン基、１－エチル－ｎ－プロピレン基、シクロペンチレン基、１－メチル－シクロブチレン基、２－メチル－シクロブチレン基、３－メチル－シクロブチレン基、１,２－ジメチル－シクロプロピレン基、２,３－ジメチル－シクロプロピレン基、１－エチル－シクロプロピレン基、２－エチル－シクロプロピレン基、ｎ－ヘキシレン基、１－メチル－ｎ－ペンチレン基、２－メチル－ｎ－ペンチレン基、３－メチル－ｎ－ペンチレン基、４－メチル－ｎ－ペンチレン基、１,１－ジメチル－ｎ－ブチレン基、１,２－ジメチル－ｎ－ブチレン基、１,３－ジメチル－ｎ－ブチレン基、２,２－ジメチル－ｎ－ブチレン基、２,３－ジメチル－ｎ－ブチレン基、３,３－ジメチル－ｎ－ブチレン基、１－エチル－ｎ－ブチレン基、２－エチル－ｎ－ブチレン基、１,１,２－トリメチル－ｎ－プロピレン基、１,２,２－トリメチル－ｎ－プロピレン基、１－エチル－１－メチル－ｎ－プロピレン基、１－エチル－２－メチル－ｎ－プロピレン基、シクロヘキシレン基、１－メチル－シクロペンチレン基、２－メチル－シクロペンチレン基、３－メチル－シクロペンチレン基、１－エチル－シクロブチレン基、２－エチル－シクロブチレン基、３－エチル－シクロブチレン基、１,２－ジメチル－シクロブチレン基、１,３－ジメチル－シクロブチレン基、２,２－ジメチル－シクロブチレン基、２,３－ジメチル－シクロブチレン基、２,４－ジメチル－シクロブチレン基、３,３－ジメチル－シクロブチレン基、１－ｎ－プロピル－シクロプロピレン基、２－ｎ－プロピル－シクロプロピレン基、１－イソプロピル－シクロプロピレン基、２－イソプロピル－シクロプロピレン基、１,２,２－トリメチル－シクロプロピレン基、１,２,３－トリメチル－シクロプロピレン基、２,２,３－トリメチル－シクロプロピレン基、１－エチル－２－メチル－シクロプロピレン基、２－エチル－１－メチル－シクロプロピレン基、２－エチル－２－メチル－シクロプロピレン基及び２－エチル－３－メチル－シクロプロピレン基等が挙げられる。 An alkylene group having 3 to 6 carbon atoms is particularly preferred.

The compounds of the above formula (1) can be exemplified below.

The epoxy compound (A) of the present invention can be further mixed with other liquid epoxy compounds.
For example, a liquid epoxy compound (formula (1-9), manufactured by Nissan Chemical Industries, Ltd.) modified by adding 0.8 mol of propionic anhydride to 1 mol of tris-(2,3-epoxypropyl)-isocyanurate can be mentioned.

Formula (1-9) contains (1-9-1):(1-9-2):(1-9-3):(1-9-4) in a molar ratio of about 35%:45%:17%:3%. The viscosity at the time of manufacture is 1800 mPas at 60° C., and after 90 days the viscosity is 1900 mPas at 60° C. and is stable.

A liquid epoxy compound (formula (1-10), manufactured by Nissan Chemical Industries, Ltd.) modified by adding 0.4 mol of propionic anhydride to 1 mol of tris-(2,3-epoxypropyl)-isocyanurate can be mentioned.

Formula (1-10) has a molar ratio of (1-10-1):(1-10-2):(1-10-3) of about 60%:32%:8%. The viscosity at the time of manufacture is 2800 mPas at 60°C, and after 90 days the viscosity is still stable at 3000 mPas at 60°C.

As other epoxy compounds, non-cyanuric acid-based liquid epoxy compounds can be preferably exemplified.
Non-cyanuric acid-based liquid epoxy compounds include bisphenol-based epoxy compounds and alicyclic epoxy compounds.
A liquid epoxy compound, trade name Epicoat 828 (formula (1-11), manufactured by Mitsubishi Chemical Corporation) can be mentioned.

A liquid epoxy compound, trade name YX8000 (formula (1-12), manufactured by Mitsubishi Chemical Corporation) can be mentioned.

A liquid epoxy compound, trade name DME100 (formula (1-13), manufactured by Shin Nippon Rika Co., Ltd.) can be mentioned.

A liquid epoxy compound, trade name CE-2021P (formula (1-14), manufactured by Daicel Corporation) can be mentioned.

The silica particles (B) used in the present invention are dispersed as dispersoids in a dispersion medium containing an epoxy compound (A) represented by the following formula (1),
The silica particles (B) used in the present invention have an average particle size of 5 to 500 nm, 5 to 150 nm, or 5 to 100 nm as determined by the dynamic light scattering method (DLS method). Silica particles are obtained with an average primary particle size of 5 to 500 nm, 5 to 150 nm, or 5 to 100 nm as determined by the nitrogen gas adsorption method (BET method).

The silica particles (B) contain alkoxy groups consisting of methoxy groups or ethoxy groups on their surfaces, and the alkoxy groups can be bonded at a ratio of 0.6 to 3.0/nm ² .
In the present invention, silica particles can be coated with a silane compound having organic groups directly bonded to silicon atoms.
The silane compound can be coated with a silane compound selected from the group consisting of formulas (2) to (4). Hydrolyzates of these silane compounds can bond with silanol groups of silica particles by dehydration condensation.
In formula (2), each R ¹ is an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, or cyano group and is bonded to a silicon atom via a Si—C bond, R ² each represents an alkoxy group, an acyloxy group, or a halogen group, a represents an integer of 1 to 3;

In formulas (3) and (4), R ³ and R ⁵ are each an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms and are bonded to a silicon atom via a Si—C bond; R ⁴ and R ⁶ each represent an alkoxy group, an acyloxy group, or a halogen group; Y represents an alkylene group, an NH group, or an oxygen atom; b is an integer of 1 to 3; is.

The above alkyl group is an alkyl group having 1 to 18 carbon atoms, such as methyl group, ethyl group, n-propyl group, i-propyl group, cyclopropyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, cyclobutyl group, 1-methyl-cyclopropyl group, 2-methyl-cyclopropyl group, n-pentyl group, 1-methyl-n-butyl group, 2-methyl-n-butyl group, 3-methyl-n-butyl group, 1,1-dimethyl-n-propyl group, 1,2-dimethyl-n-propyl group, 2,2-dimethyl-n-propyl group, 1-ethyl-n-propyl group, cyclopentyl group, 1-methyl-cyclobutyl group, 2-methyl-cyclobutyl group, 3-methyl-cyclobutyl group, 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2 -trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2 , 3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,3-trimethyl-cyclopropyl group, 1-ethyl-2-methyl-cyclopropyl group, 2-ethyl -1-methyl-cyclopropyl group, 2-ethyl-2-methyl-cyclopropyl group and 2-ethyl-3-methyl-cyclopropyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like, but are not limited thereto.
Further, examples of the alkylene group include alkylene groups derived from the above alkyl groups.

The aryl group is an aryl group having 6 to 30 carbon atoms, and examples thereof include phenyl group, naphthyl group, anthracene group, pyrene group and the like.
The alkenyl group is an alkenyl group having 2 to 10 carbon atoms, ethenyl group, 1-propenyl group, 2-propenyl group, 1-methyl-1-ethenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, 1-methyl-1-propenyl group and 1-methyl-2-propenyl group. , 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-n-propylethenyl group, 1-methyl-1-butenyl group, 1-methyl-2-butenyl group, 1-methyl-3-butenyl group, 2-ethyl-2-propenyl group, 2-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2-methyl-3-butenyl group, 3-methyl-1-butenyl group thenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl-2-propenyl group, 1-i-propylethenyl group, 1,2-dimethyl-1-propenyl group, 1,2-dimethyl-2-propenyl group, 1-cyclopentenyl group, 2-cyclopentenyl group, 3-cyclopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl-1-pentenyl group, 1-methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, 2-methyl-2-pentenyl group and the like, but are not limited thereto.

Examples of the alkoxy group include those having 1 to 10 carbon atoms, such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, n-pentyloxy, 1-methyl-n-butoxy, 2-methyl-n-butoxy, 3-methyl-n-butoxy and 1,1-dimethyl-n-propoxy. , 1,2-dimethyl-n-propoxy group, 2,2-dimethyl-n-propoxy group, 1-ethyl-n-propoxy group, n-hexyloxy group and the like, but are not limited thereto.

The acyloxy group having 2 to 10 carbon atoms is, for example, methylcarbonyloxy group, ethylcarbonyloxy group, n-propylcarbonyloxy group, i-propylcarbonyloxy group, n-butylcarbonyloxy group, i-butylcarbonyloxy group, s-butylcarbonyloxy group, t-butylcarbonyloxy group, n-pentylcarbonyloxy group, 1-methyl-n-butylcarbonyloxy group, 2-methyl-n-butylcarbonyloxy group, 3-methyl-n-butylcarbonyloxy group, 1,1-dimethyl-n- Examples include, but are not limited to, propylcarbonyloxy group, 1,2-dimethyl-n-propylcarbonyloxy group, 2,2-dimethyl-n-propylcarbonyloxy group, 1-ethyl-n-propylcarbonyloxy group, n-hexylcarbonyloxy group, 1-methyl-n-pentylcarbonyloxy group, 2-methyl-n-pentylcarbonyloxy group and the like.
Examples of the halogen group include fluorine, chlorine, bromine and iodine.

Organic groups having epoxy groups include, for example, 2-(3,4-epoxycyclohexyl)ethyl groups and 3-glycidoxypropyl groups.
The (meth)acryloyl group means both an acryloyl group and a methacryloyl group. Organic groups having a (meth)acryloyl group include, for example, a 3-methacryloxypropyl group and a 3-acryloxypropyl group.
Organic groups having a mercapto group include, for example, a 3-mercaptopropyl group.
Examples of organic groups having an amino group include 2-aminoethyl group, 3-aminopropyl group, N-2-(aminoethyl)-3-aminopropyl group, N-(1,3-dimethyl-butylidene)aminopropyl group, N-phenyl-3-aminopropyl group, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyl group and the like.
Organic groups having a ureido group include, for example, a 3-ureidopropyl group.
An organic group having a cyano group includes, for example, a 3-cyanopropyl group.
Formulas (3) and (4) above are preferably compounds capable of forming trimethylsilyl groups on the surfaces of silica particles.
Examples of these compounds are given below.

In the above formula, ^R12 is an alkoxy group such as a methoxy group and an ethoxy group. A silane compound manufactured by Shin-Etsu Chemical Co., Ltd. can be used as the silane compound.
In this step, hydroxyl groups on the surfaces of silica particles, for example, silanol groups in the case of silica particles, react with the silane compound to coat the surfaces of the silica particles with the silane compound through siloxane bonds. The reaction temperature can be in the range of 20°C to the boiling point of the dispersion medium, for example, 20°C to 100°C. The reaction time can be about 0.1 to 6 hours.

The silica particle surface can be coated with the above silane compound by adding a silane compound to the silica sol in a coating amount corresponding to the number of silicon atoms in the silane compound being 0.6/nm ² to 5.0/nm ² .
Water is necessary for the hydrolysis of the silane compound, and if it is a sol of an aqueous solvent, such an aqueous solvent is used. Moisture remaining in the solvent when the aqueous medium is replaced with an organic solvent such as methanol or ethanol can be used. For example, water present in 0.01 to 1% by weight can be used. Also, the hydrolysis can be carried out with or without a catalyst.

When it is carried out without a catalyst, the silica particle surface exists on the acidic side, and when a catalyst is used, metal chelate compounds, organic acids, inorganic acids, organic bases, and inorganic bases can be mentioned as hydrolysis catalysts. Metal chelate compounds as hydrolysis catalysts include, for example, triethoxy-mono(acetylacetonato)titanium and triethoxy-mono(acetylacetonato)zirconium. Organic acids as hydrolysis catalysts include, for example, acetic acid and oxalic acid. Inorganic acids as hydrolysis catalysts include, for example, hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, and phosphoric acid. Examples of organic bases as hydrolysis catalysts include pyridine, pyrrole, piperazine and quaternary ammonium salts. Inorganic bases as hydrolysis catalysts include, for example, ammonia, sodium hydroxide, and potassium hydroxide.
The sol of the present invention has a solid content of 0.1 to 70% by mass, or 1 to 60% by mass, or 10 to 60% by mass. Here, the solid content is the total components of the sol excluding the solvent component.
The silica sol of the present invention has high stability, for example, the viscosity after storage at 50° C. for 14 days at a silica concentration of 60% by mass is 1.0 to 30 times the value of the viscosity at 25° C. of the dispersion medium used for the silica sol.

The silica sol of the present invention is produced by the following steps (I) to (III):
(I) step: step (I) of producing a silica sol using methanol or ethanol as a dispersion medium;
(II) step: step (II) of mixing the silica sol obtained in step (I) and epoxy compound (A) represented by formula (1) to obtain silica sol;
(III) step: can be produced including a step of removing methanol or ethanol from the silica sol obtained in step (II).
Step (I) can further include the step of adding a basic substance selected from amines, ammonia, inorganic alkali compounds, or quaternary ammonium compounds when the dispersion medium of the silica sol is methanol or ethanol.
The amount of alkali to be added is preferably such that the silica sol has a pH of 4.0 to 10.0. The amount of alkali added is present in the silica sol as the amount added. The pH of the hydrophobic organic solvent silica sol of the present invention is measured by mixing silica sol, methanol and pure water at a mass ratio of 1:1:1 or 1:2:1.

Examples of amines include secondary amines and tertiary amines having 5 to 35 carbon atoms in total.
Examples of the secondary amine include ethyl n-propylamine, ethylisopropylamine, dipropylamine, diisopropylamine, ethylbutylamine, n-propylbutylamine, dibutylamine, ethylpentylamine, n-propylpentylamine, isopropylpentylamine, dipentylamine, ethyloctylamine, i-propyloctylamine, butyloctylamine, dioctylamine and the like.

Examples of the tertiary amine include triethylamine, ethyldi-n-propylamine, diethyl-n-propylamine, tri-n-propylamine, triisopropylamine, ethyldibutylamine, diethylbutylamine, isopropyldibutylamine, diisopropylethylamine, diisopropylbutylamine, tributylamine, ethyldipentylamine, diethylpentylamine, tripentylamine, methyldioctylamine, dimethyloctylamine, ethyldioctylamine, diethyloctylamine, trioctylamine, benzyldibutylamine, diazabi cycloundecene and the like.
Among the above amines, secondary amines and tertiary amines having an alkyl group having a total number of carbon atoms of 6 to 35 are preferred, such as diisopropylamine, tripentylamine, triisopropylamine, dimethyloctylamine and trioctylamine.

The quaternary ammonium hydroxide is preferably a tetraalkylammonium hydroxide having 4 to 40 carbon atoms in total. Examples thereof include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-i-propylammonium hydroxide, tetrabutylammonium hydroxide, and ethyltrimethylammonium hydroxide.
Alkali metal hydroxides include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like.

Alkali metal alkoxides include sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide and the like.
Alkali metal salts of aliphatic carboxylic acids include alkali metal salts of saturated aliphatic carboxylic acids having 2 to 30 carbon atoms and alkali metal salts of unsaturated aliphatic carboxylic acids. Alkali metals include sodium and potassium. Examples of the saturated aliphatic carboxylic acid alkali metal salt include alkali metal laurate, alkali metal myristate, alkali metal palmitate, alkali metal stearate and the like.

Examples of the unsaturated aliphatic carboxylic acid alkali metal salt include alkali metal oleate, alkali metal linoleate and alkali metal linolenate.
In particular, unsaturated aliphatic carboxylic acid alkali metal salts such as potassium oleate can be preferably used.
Alkali metal salts of aromatic carboxylic acids include benzoates, salicylates, phthalates and the like.
Step (I) may further include the step of coating the silica particles with at least one silane compound selected from the group consisting of formulas (2) to (4) when the dispersion medium of the silica sol is methanol or ethanol.
Before step (II) mixes the silica sol obtained in step (I) with the epoxy compound (A) represented by formula (1), the silica sol obtained in step (I) can further include a step of solvent substitution with an organic solvent having a carbonyl structure, an ether structure, or a carbon-carbon bonding structure.

Organic substances having a carbonyl structure can be exemplified by ketones, esters, aldehydes, or amides.
Ketones are linear or cyclic aliphatic ketones having 3 to 30 carbon atoms, such as methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diisopropyl ketone, diisobutyl ketone, methyl amyl ketone and cyclohexanone.

Ethers are linear or cyclic aliphatic ethers having 3 to 30 carbon atoms, such as diethyl ether and tetrahydrofuran.
The ester is a linear or cyclic ester having 2 to 30 carbon atoms, and examples thereof include ethyl acetate, n-butyl acetate, sec-butyl acetate, methoxybutyl acetate, amyl acetate, n-propyl acetate, isopropyl acetate, ethyl lactate, butyl lactate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, phenyl acetate, phenyl lactate, and phenyl propionate.
Amide is an aliphatic amide having 3 to 30 carbon atoms, such as dimethylacetamide, dimethylformamide, N-methylpyrrolidone, N-ethylpyrrolidone and the like.
The organic solvent having a carbon-carbon bond structure is a hydrocarbon, a linear or cyclic aliphatic or aromatic hydrocarbon having 6 to 30 carbon atoms, such as hexane, heptane, octane, nonane, decane, benzene, toluene, and xylene.

In the present invention, it is possible to obtain a cured product-forming composition containing the above silica sol and a curing agent.
Curing agents include acid anhydrides, amines, or acid generators.
A coating composition containing a silica sol and a curing agent can be applied to a substrate and cured by heating, light irradiation, or a combination thereof.
In the case of a thermosetting coating composition, the thermosetting agent can be contained in an amount of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, relative to the epoxy groups. The equivalent weight of the thermosetting agent to the epoxy compound is indicated by the equivalent ratio of the curable groups of the thermosetting agent to the epoxy groups.

Thermal curing agents include phenol resins, amine-based curing agents, polyamide resins, imidazoles, polymercaptans, acid anhydrides, thermal acid generators, and the like. Acid anhydride-based curing agents and amine-based curing agents are particularly preferred.
These thermosetting agents can be used by dissolving them in a solvent even if they are solid. However, the evaporation of the solvent lowers the density of the cured product and the formation of pores, resulting in a decrease in strength and water resistance.

Examples of phenol resins include phenol novolak resins and cresol novolak resins.
Examples of amine curing agents include piperidine, N,N-dimethylpiperazine, triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, menzenediamine, isophoronediamine, and diaminodicyclohexylmethane. , 1,3-diaminomethylcyclohexane, xylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, 3,3′-diethyl-4,4′-diaminodiphenylmethane, diethyltoluenediamine and the like. Among these, liquid diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, menzenediamine, isophoronediamine, diaminodicyclohexylmethane, 3,3′-diethyl-4,4′-diaminodiphenylmethane, diethyltoluenediamine and the like can be preferably used.

The polyamide resin is produced by condensation of a dimer acid and a polyamine, and is a polyamidoamine having a primary amine and a secondary amine in the molecule.

Examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, and epoxyimidazole adducts.

The polymercaptan is, for example, one having a mercaptan group at the end of a polypropylene glycol chain or one having a mercaptan group at the end of a polyethylene glycol chain, and is preferably liquid.
As the acid anhydride-based curing agent, an anhydride of a compound having a plurality of carboxyl groups in one molecule is preferred. Examples of these acid anhydride curing agents include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimmellitate, glycerol tristrimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, hexahydrophthalic anhydride, and methyl hexahydrophthalic anhydride. Examples include hydrophthalic anhydride, succinic anhydride, methylcyclohexenedicarboxylic anhydride, and chlorendic anhydride.
The thermal acid generator includes sulfonium salts and phosphonium salts, with sulfonium salts being preferred. For example, the following compounds can be exemplified.

R includes an alkyl group having 1 to 12 carbon atoms and an aryl group having 6 to 20 carbon atoms, and an alkyl group having 1 to 12 carbon atoms is particularly preferable.
Among these, preferred are methyltetrahydrophthalic anhydride, methyl-5-norbornene-2,3-dicarboxylic anhydride (methylnadic anhydride, methylhimic anhydride), hydrogenated methylnadic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, methylhexahydrophthalic anhydride, and a mixture of methylhexahydrophthalic anhydride and hexahydrophthalic anhydride, which are liquid at normal temperature and pressure. These liquid acid anhydrides have viscosities of the order of 10 mPas to 1000 mPas as measured at 25°C.

Moreover, when obtaining the said hardened|cured material, a hardening|curing auxiliary agent may be used together suitably. Curing aids include organic phosphorus compounds such as triphenylphosphine and tributylphosphine, quaternary phosphonium salts such as ethyltriphenylphosphonium bromide and diethyl methyltriphenylphosphonium phosphate, salts of 1,8-diazabicyclo(5,4,0)undecane-7-ene, 1,8-diazabicyclo(5,4,0)undecane-7-ene and octylic acid, and quaternary ammonium salts such as zinc octylate and tetrabutylammonium bromide. mentioned. These curing aids can be contained at a ratio of 0.001 to 0.1 parts by mass with respect to 1 part by mass of the curing agent.

The composition is obtained by mixing a curing agent and optionally a curing aid to obtain a thermosetting composition. These can be mixed in a reaction vessel using a stirring blade or a kneader.
Mixing is performed by a heat mixing method at a temperature of 60° C. to 100° C. for 0.5 to 1 hour.
The resulting liquid epoxy resin composition (thermosetting composition) is a thermosetting coating composition and has a suitable viscosity for use as, for example, a liquid encapsulant. The liquid thermosetting composition can be prepared to have any viscosity, and can be used as a transparent encapsulant for LEDs or the like by casting, potting, dispenser, printing, or the like, so that it can be partially sealed at any location. After the liquid thermosetting composition is directly mounted on an LED or the like in the liquid state by the method described above, it is dried and cured to obtain a cured epoxy resin.
A thermosetting composition (thermosetting coating composition) is applied to a substrate and heated at a temperature of 80 to 200° C. to obtain a cured product.
In the case of a photocurable coating composition, a photocuring agent (photoacid generator) can be contained in an amount of 0.5 to 20% by mass, preferably 0.8 to 10% by mass, based on epoxy groups.

The photoacid generator is not particularly limited as long as it directly or indirectly generates an acid upon irradiation with light.
Specific examples of the photoacid generator include triazine-based compounds, acetophenone derivative compounds, disulfone-based compounds, diazomethane-based compounds, sulfonic acid derivative compounds, onium salts such as iodonium salts, sulfonium salts, phosphonium salts, and selenium salts, metallocene complexes, iron arene complexes, and the like.

Onium salts used as photoacid generators include iodonium salts such as diphenyliodonium chloride, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium mesylate, diphenyliodonium tosylate, diphenyliodonium bromide, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluoroarsenate, bis(p-tert-butylphenyl)iodonium hexafluorophosphate, and bis(p-tert-butyl). Phenyl)iodonium mesylate, bis(p-tert-butylphenyl)iodonium tosylate, bis(p-tert-butylphenyl)iodonium trifluoromethanesulfonate, bis(p-tert-butylphenyl)iodonium tetrafluoroborate, bis(p-tert-butylphenyl)iodonium chloride, bis(p-chlorophenyl)iodonium chloride, bis(p-chlorophenyl)iodonium tetrafluoroborate, further bis(4-t-butylphenyl)iodonium hexafluoro Bis(alkylphenyl)iodonium salts such as phosphates, alkoxycarbonylalkoxy-trialkylaryliodonium salts (e.g., 4-[(1-ethoxycarbonyl-ethoxy)phenyl]-(2,4,6-trimethylphenyl)-iodonium hexafluorophosphate), bis(alkoxyaryl)iodonium salts (e.g., bis(alkoxyphenyl)iodonium salts such as (4-methoxyphenyl)phenyliodonium hexafluoroantimonate).
As sulfonium salts, triphenylsulfonium salts such as triphenylsulfonium chloride, triphenylsulfonium bromide, tri(p-methoxyphenyl)sulfonium tetrafluoroborate, tri(p-methoxyphenyl)sulfonium hexafluorophosphonate, tri(p-ethoxyphenyl)sulfonium tetrafluoroborate, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl) diphenylsulfonium hexafluoroantimonate, (4-phenylthio phenyl)diphenylsulfonium hexafluorophosphate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluoroantimonate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluorophosphate, (4-methoxyphenyl)diphenylsulfonium hexafluoroantimonate) and other sulfonium salts.

Examples of phosphonium salts include phosphonium salts such as triphenylphosphonium chloride, triphenylphosphonium bromide, tri(p-methoxyphenyl)phosphonium tetrafluoroborate, tri(p-methoxyphenyl)phosphonium hexafluorophosphonate, tri(p-ethoxyphenyl)phosphonium tetrafluoroborate, 4-chlorobenzenediazonium hexafluorophosphate, and benzyltriphenylphosphonium hexafluoroantimonate.
Selenium salts such as triphenylselenium hexafluorophosphate, and metallocene complexes such as (η5 or η6-isopropylbenzene)(η5-cyclopentadienyl)iron(II) hexafluorophosphate.

Moreover, the following compounds can also be used as a photo-acid generator.

A sulfonium salt compound and an iodonium salt compound are preferable as the photoacid generator. These anionic species include CF ₃ SO ₃ ^- , C ₄ F ₉ SO ₃ ^- , C ₈ F ₁₇ SO ₃ ^- , camphorsulfonate anion, tosylate anion, BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- and SbF ₆ ^- . Anion species such as phosphorus hexafluoride and antimony hexafluoride, which are particularly strongly acidic, are preferred.

The composition of the present invention may contain conventional additives as required. Examples of such additives include pigments, colorants, thickeners, sensitizers, antifoaming agents, leveling agents, coatability improvers, lubricants, stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), plasticizers, surfactants, dissolution accelerators, fillers, antistatic agents, curing agents, and the like. These additives may be used alone or in combination of two or more.
Examples of coating methods include flow coating, spin coating, spray coating, screen printing, casting, bar coating, curtain coating, roll coating, gravure coating, dipping, and slitting.

In the present invention, the optical coating composition can be applied onto a substrate and cured by light irradiation. Moreover, it can also be heated before and after light irradiation.
The thickness of the coating can be selected from a range of about 0.01 μm to 10 mm, depending on the use of cured materials. M) can be as high as 0.1 to 100 μm (especially 0.3 to 50 μm) when used for optical thin film.
The light for irradiation or exposure when a photoacid generator is used may be, for example, gamma rays, X-rays, ultraviolet rays, visible rays, etc., and usually visible light or ultraviolet rays, particularly ultraviolet rays, in many cases. The wavelength of the light is, for example, 150 to 800 nm, preferably 150 to 600 nm, more preferably 200 to 400 nm, especially 300 to 400 nm. The amount of irradiation light varies depending on the thickness of the coating film, but can be, for example, about 2 to 20,000 mJ/cm ² , preferably about 5 to 5,000 mJ/cm ² . The light source can be selected according to the type of light beam to be exposed. For example, in the case of ultraviolet rays, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, deuterium lamps, halogen lamps, laser light (helium-cadmium laser, excimer laser, etc.) can be used. Such light irradiation promotes the curing reaction of the composition.

When a thermal acid generator is used, or when a photoacid generator is used, the coating film is optionally heated after irradiation with light, for example, at 60 to 250°C, preferably about 100 to 200°C. The heating time can be selected from a range of 3 seconds or more (for example, about 3 seconds to 5 hours), for example, 5 seconds to 2 hours, preferably about 20 seconds to 30 minutes, and usually 1 minute to 3 hours (for example, 5 minutes to 2.5 hours).
Furthermore, when forming a pattern or image (for example, when manufacturing a printed wiring board, etc.), the coating film formed on the base material may be pattern-exposed, and this pattern exposure may be performed by scanning with laser light, or may be performed by light irradiation through a photomask. A pattern or image can be formed by developing (or dissolving) the non-irradiated area (unexposed area) generated by such pattern exposure with a developer.
An alkaline aqueous solution or an organic solvent can be used as the developer.

Examples of alkaline aqueous solutions include aqueous solutions of alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, potassium carbonate and sodium carbonate, aqueous solutions of tetramethylammonium hydroxide, tetraethylammonium hydroxide, quaternary ammonium hydroxides such as choline, and aqueous solutions of amines such as ethanolamine, propylamine and ethylenediamine.

The alkaline developer is generally an aqueous solution of 10% by mass or less, preferably an aqueous solution of 0.1 to 3.0% by mass. Furthermore, alcohols and surfactants can be added to the developer and used, and the amount of each of these is preferably 0.05 to 10 parts by weight per 100 parts by weight of the developer.
Among these, 0.1 to 2.38% by mass aqueous solution of tetramethylammonium hydroxide can be used.

As the organic solvent for the developer, it is possible to use common organic solvents, for example, acetone, acetonitrile, toluene, dimethylformamide, methanol, ethanol, isopropanol, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, propylene glycol butyl ether acetate, ethyl lactate, cyclohexanone, etc., and a mixture of one or more of these. can be used. In particular, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl lactate and the like can be preferably used.

In the present invention, a surfactant may be added for the purpose of improving coatability. Such surfactants are not particularly limited and may be fluorosurfactants, silicone surfactants, nonionic surfactants, or the like. One or a combination of two or more of the surfactants can be used.
Among these surfactants, fluorine-based surfactants are preferred because of their high coatability-improving effect. Specific examples of fluorosurfactants include F-Top EF301, EF303, and EF352 (manufactured by Tochem Products Co., Ltd.), Megafac F171, F173, R-30, R-08, R-90, BL-20, and F-482 (manufactured by Dainippon Ink and Chemicals, Inc.), Florard FC430, and FC431 (Sumitomo Susumu). Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), etc., but not limited thereto.
The amount of the surfactant added to the curable composition of the present invention is 0.0008 to 4.5% by mass, preferably 0.0008 to 2.7% by mass, more preferably 0.0008 to 1.8% by mass based on the solid content.

In the present invention, an adhesion promoter can be added for the purpose of improving adhesion to the substrate after development. These adhesion promoters include chlorosilanes such as trimethylchlorosilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane and chloromethyldimethylchlorosilane; alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylvinylethoxysilane, diphenyldimethoxysilane and phenyltriethoxysilane; and silazanes such as hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine and trimethylsilylimidazole. silanes such as vinyltrichlorosilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-(N-piperidinyl)propyltrimethoxysilane, benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole, urazole, thiooxauracil, Heterocyclic compounds such as mercaptoimidazole and mercaptopyrimidine, urea compounds such as 1,1-dimethylurea and 1,3-dimethylurea, and thiourea compounds can be mentioned. One or a combination of two or more of the adhesion promoters may be used. The amount of these adhesion promoters added is usually 18% by mass or less, preferably 0.0008 to 9% by mass, more preferably 0.04 to 9% by mass, based on the solid content.

The present invention may contain a sensitizer. Sensitizers that can be used include anthracene, phenothiazene, perylene, thioxanthone, benzophenonethioxanthone, and the like. Examples of sensitizing dyes include thiopyrylium salt dyes, merocyanine dyes, quinoline dyes, styrylquinoline dyes, ketocoumarin dyes, thioxanthene dyes, xanthene dyes, oxonol dyes, cyanine dyes, rhodamine dyes, and pyrylium salt dyes. Particularly preferred is an anthracene-based sensitizer, which, when used in combination with a cationic curing catalyst (radiation-sensitive cationic polymerization initiator), dramatically improves sensitivity and also has a function of initiating radical polymerization. In the hybrid type of the present invention, in which a cationic curing system and a radical curing system are used in combination, the catalyst species can be simplified. As specific anthracene compounds, dibutoxyanthracene, dipropoxyanthraquinone and the like are effective. The amount of the sensitizer added is 0.01 to 20% by mass, preferably 0.01 to 10% by mass, based on the solid content.

In the present invention, a composition containing an epoxy compound can be photo-cured or heat-cured using a photoacid generator or a thermal acid generator. Since a photoacid generator or a thermal acid generator is used, a commonly used epoxy curing agent (e.g., an amine or an acid anhydride) is not used, or even if they are used, the content thereof is extremely small, so that the storage stability of the composition containing the epoxy composition is improved.

It was found that the composition containing the above liquid epoxy compound has photocationic polymerizability. It has a higher curing rate than conventional liquid epoxy compounds (for example, alicyclic epoxy compounds having an epoxycyclohexyl ring). Since the curing speed is fast, it is possible to reduce the amount of acid generator to be added and to use a weak acid type acid generator. Reducing the amount of acid generators is important for preventing metal corrosion since acid active species may remain even after UV irradiation. High curing speed enables thick film curing.
Curing by UV irradiation can be applied to heat-sensitive materials (equipment).

Thermosetting materials and photocurable materials using the composition containing the epoxy compound of the present invention are characterized by rapid curing, transparency, and small curing shrinkage, and can be used for coating and adhesion of electronic parts, optical parts, and precision mechanical parts. For example, mobile phone and camera lenses, optical elements such as light emitting diodes (LED) and semiconductor lasers (LD), liquid crystal panels, biochips, parts such as camera lenses and prisms, magnetic parts of hard disks such as personal computers, CD, DVD player pickups (parts that capture light information reflected from the disc), speaker cones and coils, motor magnets, circuit boards, electronic parts, parts inside the engine of automobiles, etc. It can be used for adhesion.

For hard coating materials for surface protection of automobile bodies, lamps, electrical appliances, building materials, plastics, etc., for example, automobiles, motorcycle bodies, headlight lenses and mirrors, plastic lenses for glasses, mobile phones, game machines, optical films, ID cards, etc.

Examples of ink materials for printing on metals such as aluminum and plastics include credit cards, cards such as membership cards, switches for electrical appliances and OA equipment, ink for printing on keyboards, and ink for inkjet printers on CDs, DVDs, etc.

Technologies for creating complex three-dimensional objects by curing resin in combination with 3D CAD, applications for optical modeling such as model production of industrial products, optical fiber coatings, adhesion, optical waveguides, thick film resists, etc.
In addition, the cured body-forming composition containing the epoxy compound of the present invention can be suitably used as an insulating resin for electronic materials such as a semiconductor encapsulating material, an adhesive for electronic materials, a printed wiring board material, an interlayer insulating film material, and a power module encapsulant, or as an insulating resin used in high-voltage equipment such as generator coils, transformer coils, and gas-insulated switchgears.

[Measurement of SiO ₂ concentration]
Silica sol was placed in a crucible, dried at 130° C. and fired at 1000° C., and the firing residue was weighed and calculated.
[Measurement of average primary particle size (nitrogen adsorption method particle size)]
The specific surface area of the 300° C. dry powder of silica sol was measured using a specific surface area measuring device Monosorb (registered trademark) MS-16 (manufactured by Yuasa Ionics Co., Ltd.).

[Measurement of viscosity]
The viscosity of the organic solvent-dispersed silica sol was measured using an Ostwald viscometer. The viscosity of the resin monomer dispersed sol was measured using a B-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd.). When the B-type rotational viscometer could not be used, the E-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd.) was used for measurement.
[Measurement of average particle size by dynamic light scattering method] The average particle size of the epoxy compound-containing resin monomer dispersion sol was measured by the dynamic light scattering method. The sol was diluted with methyl ethyl ketone to a predetermined concentration, and the average particle size was measured using a dynamic light scattering particle size measuring device (ZETASIZER Nano series manufactured by Malvern Instruments LTD).
[Method for analyzing amount of alkoxy group bound to particle surface]
After adding 4 ml of methyl ethyl ketone to 4 ml of silica sol, 20 ml of n-hexane was added, and after centrifugation (centrifugal force 2770 G), the supernatant was discarded to separate the sediment. Further, after re-dissolving the sediment by adding 2 to 4 ml of acetone, an operation of adding n-hexane again until flocculation and separating the sediment by centrifugation (centrifugal force 2770 G) was repeated twice. The resulting sediment was vacuum dried at 150° C. to obtain a dry powder.
0.2 g of the powder obtained above was mixed with 10 mL of a 0.05 N sodium hydroxide aqueous solution, dispersed for 20 minutes with an ultrasonic cleaner (40 kHz), left at room temperature for one day, and then the solution portion was measured by gas chromatography to measure the amount of alkoxy group bonding per unit area of the silica surface (number/nm ² ).

[Measurement of pH]
pH (1+1): A solution obtained by mixing silica sol and pure water at a mass ratio of 1:1 was measured with a pH meter.
pH (1+1+1): A liquid obtained by mixing silica sol, methanol and pure water at a mass ratio of 1:1:1 was measured with a pH meter.
[Measurement of organic solvent content in sol]
Measured by gas chromatography.
[Measurement of epoxy equivalent]
0.3 g of the epoxy resin monomer dispersion sol was weighed and put into a glass beaker, 10 mL of chloroform was further added, and the mixture was stirred using a magnetic stirrer. To the solution, 20 mL of acetic acid was added, followed by 20 mL of tetraethylammonium bromide acetic acid solution (0.25 g/mL acetic acid) and stirred. Using an automatic titrator COM-1700A (manufactured by HIRANUMA Co., Ltd.), the solution was subjected to potentiometric titration with perchloric acid-acetic acid standard solution (0.1 mol / L), and the epoxy equivalent was calculated according to JIS K7236 (2001).

[Measurement of flexural modulus and displacement of cured epoxy resin]
Based on JIS K-6911, it was measured using a tensile tester. More specifically, the bending strength was measured in the same manner, and the bending elastic modulus (E) was calculated from the load-deflection curve obtained by the measurement according to the following formula.

E = (L3/4Wh3) x (ΔF/Δs)
In the above formula,
E: Flexural modulus (MPa) {kgf/mm ² }
L: Distance between fulcrums (mm)
W: Width of test piece (mm)
h: thickness of test piece (mm)
ΔF: Amount of change in bending load (N) {kgf}
Δs: Amount of deflection change (mm)
[Calculation of Bending Strain of Cured Epoxy Resin]
Bending strain (ε) was calculated from the amount of change in deflection, the distance between fulcrums, and the thickness of the test piece measured above.

ε=(600×Δs×h)/L ²
[Measurement of coefficient of linear expansion (CTE) of cured epoxy resin]
Measurement of linear expansion coefficient was measured based on JIS K 6911. The thickness of the test piece was accurately measured by TMA (Thermal Mechanical Analysis) at a load of 0.05 N and a heating rate of 2° C./min. The coefficient of linear expansion (α) was calculated by the following formula, with α1 representing the coefficient of linear expansion below the glass transition temperature and α2 representing the coefficient of linear expansion above the glass transition temperature.

α=ΔL/(L×ΔT)
In the above formula,
ΔL: Amount of change in thickness
L: initial thickness ΔT: temperature change [measurement of transmittance of cured epoxy resin]
The transmittance at a wavelength of 520 nm was measured using a spectrophotometer (model UV-3600: manufactured by Shimadzu Corporation) on a test piece with a thickness of 3 mm.

(Example 1)
A water-dispersed silica sol 1 (average primary particle size 12 nm, pH 3, silica concentration 33% by mass, manufactured by Nissan Chemical Industries, Ltd.) was prepared.
850 g of the above water-dispersed silica sol 1 was charged into a glass reactor having an internal volume of 2 L equipped with a stirrer, a condenser, a thermometer, and two inlets. While the sol in the reactor was kept boiling, methanol vapor generated in another boiler was continuously blown into the silica sol in the reactor to replace water with methanol. When the volume of the distillate reached 8 L, replacement was terminated to obtain 850 g of methanol-dispersed silica sol 1. The resulting methanol-dispersed silica sol 1 had a SiO ₂ concentration of 33.0% by mass, a water content of 1.6% by mass, and a pH of (1+1)3.
800 g of methanol-dispersed silica sol 1 was charged into a 2 L eggplant flask, and while stirring the sol using a magnetic stirrer, 65.3 g of phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-103) (: 3.3 particles per unit area (nm ² ) of silica particle surface) was added, and then the liquid temperature was maintained at 60° C. for 2 hours. After that, diisopropylethylamine was added to adjust the silica sol pH=(1+1+1) to 6.7, and then distillation was performed using a rotary evaporator at a bath temperature of 80° C. under a reduced pressure of 500 to 350 Torr while supplying methyl ethyl ketone to obtain a methyl ethyl ketone-dispersed silica sol 1. The resulting methyl ethyl ketone-dispersed silica sol ₁ had a SiO concentration of 30.5% by mass, a viscosity (20° C.) of 1.0 mPa s, a water content of 0.1% by mass, methanol of 0.1% by mass, a pH of (1+1+1) of 6.7, and the organic group directly bonded to the silicon atom by Si—C bonding on the silica particle surface was a phenyl group, and the number of methoxy groups bonded to the silica particle surface was 2.0/nm ² .
To 60 g of the obtained methyl ethyl ketone dispersed silica sol 1 was added 38.8 g of a nitrogen-containing trifunctional epoxy resin monomer, trade name TEPIC-VL (manufactured by Nissan Chemical Industries, Ltd., component tris-(4,5-epoxypentyl)-isocyanurate), and the solvent was removed at a bath temperature of 80° C. and 300 to 30 Torr to obtain a nitrogen-containing epoxy monomer dispersed sol 1. The resulting silica sol had _a SiO concentration of 31.2% by mass, a methanol content of less than 0.1% by mass, a methyl ethyl ketone content of less than 0.5% by mass, a B-type viscosity at 25°C of 75,900 mPa s, an average particle size determined by a dynamic light scattering method of 19 nm, and an epoxy equivalent of 202 g/eq.

(Example 2)
In Example 1, the procedure was carried out in the same manner as in Example 1, except that the amine added to the methanol _- dispersed silica sol 1 was changed to tri-n-pentylamine. The number of bonded methoxy groups was 2.1/ ^nm2 .
To 54.3 g of methyl ethyl ketone-dispersed silica sol 2, 38.9 g of a nitrogen-containing trifunctional epoxy resin monomer, trade name TEPIC-VL (manufactured by Nissan Chemical Industries, Ltd., component: tris-(4,5-epoxypentyl)-isocyanurate) was added, and a nitrogen-containing epoxy monomer dispersed sol 2 was obtained in the same manner as in Example 1. The resulting silica sol had _a SiO concentration of 30.8% by mass, a methanol content of less than 0.1% by mass, a methyl ethyl ketone content of less than 0.5% by mass, a B-type viscosity at 25°C of 61,500 mPa s, an average particle size determined by a dynamic light scattering method of 18 nm, and an epoxy equivalent of 199 g/eq.

(Example 3)
A nitrogen-containing trifunctional epoxy resin monomer dispersion sol 3 was obtained in the same manner as in Example 1, except that the nitrogen-containing trifunctional epoxy resin monomer trade name TEPIC-FL (manufactured by Nissan Chemical Industries, Ltd., component tris-(7,8-epoxyoctyl)-isocyanurate) was used. The obtained silica sol had _a SiO concentration of 31.2% by mass, a methanol content of less than 0.1% by mass, a methyl ethyl ketone content of less than 0.5% by mass, a B-type viscosity at 25°C of 6,890 mPa s, an average particle size determined by a dynamic light scattering method of 18 nm, and a number of methoxy groups bonded to the silica particle surface of 2.0/ ^nm2 . Epoxy equivalent weight was 289 g/eq.

(Example 4)
A nitrogen-containing epoxy monomer dispersion sol 4 was obtained in the same manner as in Example 2, except that in Example 2, the nitrogen-containing trifunctional epoxy resin monomer, trade name TEPIC-FL (manufactured by Nissan Chemical Industries, Ltd., component: tris-(7,8-epoxyoctyl)-isocyanurate) was changed. The resulting silica sol had a _SiO concentration of 30.7% by mass, a methanol content of less than 0.1% by mass, a methyl ethyl ketone content of less than 0.5% by mass, a B-type viscosity at 25°C of 7,250 mPa s, an average particle size determined by a dynamic light scattering method of 21 nm, and a methoxy group bonded to the silica particle surface of 2.1/ ^nm2 . Epoxy equivalent weight was 287 g/eq.

(Example 5)
Water-dispersed silica sol 2 (average primary particle size 85 nm, pH 3, silica concentration 34.5% by mass, manufactured by Nissan Chemical Co., Ltd.) and water-dispersed silica sol 1 (average primary particle size 12 nm, pH 3, silica concentration 33% by mass, manufactured by Nissan Chemical Co., Ltd.) were prepared.
800 g of the water-dispersed silica sol 2 and 93 g of the water-dispersed silica sol 1 were charged into a glass reactor having an internal volume of 2 L equipped with a stirrer, a condenser, a thermometer and two inlets. While the sol in the reactor was kept boiling, methanol vapor generated in a separate boiler was continuously blown into the silica sol in the reactor to replace water with methanol. When the volume of the distillate reached 9 L, the replacement was terminated, and 870 g of methanol-dispersed silica sol 2 was obtained. The resulting methanol-dispersed silica sol 2 had a SiO ₂ concentration of 35.0% by mass, a water content of 1.6% by mass, and a pH of (1+1)3.

Tri-n-pentylamine was added to 800 g of methanol-dispersed silica sol 2 to adjust the pH (1+1+1) to 7.0. After adding 5.9 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KBM-303, manufactured by Shin-Etsu Chemical Co., Ltd.) (one per unit area (nm ² ) of silica particle surface) and heating at 60° C. for 2 hours, 14.2 g of phenyltrimethoxysilane (3 per unit area (nm ² ) of silica particle surface) was added and heated at 60° C. for 2 hours. Then, the solvent was replaced with methyl ethyl ketone, and methyl ethyl ketone-dispersed silica sol 3 (SiO ₂ concentration 30.5% by mass, viscosity (20° C.) 1 mPa s, water content 0.1% by mass, methanol 0.1% by mass, pH (1+1+1) 7.4, the organic groups directly bonded to silicon atoms by Si—C bonds on the silica particle surface were 2-(3,4-epoxycyclohexyl)ethyl groups and phenyl groups, and 1.7 methoxy groups/groups bonded to the silica particle surface. nm ^2. ) was obtained.

To 150 g of methyl ethyl ketone-dispersed silica sol 3, 14.1 g of a nitrogen-containing trifunctional epoxy resin monomer under the trade name TEPIC-VL (manufactured by Nissan Chemical Industries, Ltd., the component is tris-(4,5-epoxypentyl)-isocyanurate) and 14.1 g of a nitrogen-containing trifunctional epoxy resin monomer under the trade name of TEPIC-FL (manufactured by Nissan Chemical Industries, Ltd., the component is tris-(7,8-epoxyoctyl)-isocyanurate) were added, and the bath temperature was 80. C. and 300 to 30 Torr to remove the solvent to obtain a nitrogen-containing epoxy monomer dispersion sol 5. The resulting silica sol had _a SiO concentration of 63.4% by mass, a methanol content of less than 0.1% by mass, a methyl ethyl ketone content of less than 0.1% by mass, an E-type viscosity at 25°C of 95 Pa s, an average particle size determined by dynamic light scattering, and an epoxy equivalent of 469 g/eq.

(Example 6)
To 400 g of the above methyl ethyl ketone-dispersed silica sol 3, 54 g of nitrogen-containing trifunctional epoxy resin monomers under the trade name TEPIC-VL (manufactured by Nissan Chemical Industries, Ltd., the component is tris-(4,5-epoxypentyl)-isocyanurate) and 23 g of the trade name TEPIC-FL (manufactured by Nissan Chemical Industries, Ltd., the component is tris-(7,8-epoxyoctyl)-isocyanurate) are added, and desorption is performed at a bath temperature of 100° C. and 200 to 30 Torr. A solvent was removed to obtain a nitrogen-containing epoxy monomer dispersed sol. The silica sol obtained had a SiO ₂ concentration of 60.0% by weight and a methanol content of less than 0.1% by weight. The methyl ethyl ketone content was less than 0.1% by mass, the average particle size by dynamic light scattering was 137 nm, the B-type viscosity was 34,000 mPa s at 25°C, the viscosity was 35,000 mPa s after storage at 50°C for 14 days, and the viscosity was 35,000 mPa s after storage at 50°C for 28 days, indicating low viscosity and stability. The viscosity after storage for 14 days at 50 ° C. with a silica concentration of 60 mass% was 10 times the viscosity at 25 ° C. of only the dispersion medium (trade name TEPIC-VL (manufactured by Nissan Chemical Co., Ltd.) and trade name TEPIC-FL (manufactured by Nissan Chemical Co., Ltd.), which are nitrogen-containing trifunctional epoxy resin monomers). The viscosity was low and stable.
The B-type viscosity at 25° C. of a resin monomer obtained by mixing 54 g of TEPIC-VL (manufactured by Nissan Chemical Industries, Ltd.) and 23 g of TEPIC-FL was 3660 mPa·s.

(Example 7)
A water-dispersed silica sol 3 (average primary particle size 45 nm, pH 3, silica concentration 20.5% by mass, manufactured by Nissan Chemical Industries, Ltd.) was prepared.
Methanol-dispersed silica sol 7 (SiO ₂ concentration 35.0% by mass, water content 1.6% by mass, pH (1+1) 3) was obtained in the same manner as in Example 6, except that 1346 g of water-dispersed silica sol 3 was used instead of 800 g of water-dispersed silica sol 1. Thereafter, using methanol-dispersed silica sol 7, pH was adjusted with tri-n-pentylamine and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (addition amount: 1 per unit area (nm ² ) of silica particle surface) and phenyltrimethoxysilane (addition amount: 3 per unit area (nm ² ) of silica particle surface) were added and a heating reaction was carried out. After that, the solvent was replaced with methyl ethyl ketone, and methyl ethyl ketone-dispersed silica sol 4 (SiO ₂ concentration 30.5 mass%, viscosity (20 ° C.) 1 mPa s, water content 0.1 mass%, methanol 0.1 mass%, pH (1 + 1 + 1) 7.1. nm ^2. ) was obtained.

A nitrogen-containing epoxy monomer-dispersed sol was obtained in the same manner as in Example 5 using methyl ethyl ketone-dispersed silica sol 9. The resulting silica sol had _a SiO concentration of 60.0% by mass, a methanol content of less than 0.1% by mass, a methyl ethyl ketone content of less than 0.1% by mass, an average particle size determined by dynamic light scattering of 90 nm, a B-type viscosity of 64000 mPa s at 25°C, a viscosity of 68000 mPa s after storage at 50°C for 14 days, and a viscosity of 72000 mPa s after storage at 50°C for 28 days. The viscosity after storage for 14 days at 50 ° C. with a silica concentration of 60 mass% was 19 times the viscosity at 25 ° C. of only the dispersion medium (trade name TEPIC-VL (manufactured by Nissan Chemical Co., Ltd.) and trade name TEPIC-FL (manufactured by Nissan Chemical Co., Ltd.), which are nitrogen-containing trifunctional epoxy resin monomers). The viscosity was low and stable.

(Comparative example 1)
An alicyclic epoxy monomer dispersion sol 1 was obtained in the same manner as in Example 1, except that the nitrogen-containing trifunctional epoxy resin monomer was changed to an alicyclic epoxy resin (manufactured by Daicel Co., Ltd., product name Celoxide 2021P). The obtained silica sol had a _SiO concentration of 31.2% by mass, a methanol content of less than 0.1% by mass, a methyl ethyl ketone content of less than 0.5% by mass, an average particle size determined by dynamic light scattering method of 30 nm, an epoxy equivalent of 227 g/eq, the number of methoxy groups bonded to the silica particle surface was 2.0/ ^nm2 , and the B-type viscosity at 25°C was 14,980 mPa s.

(Preparation of epoxy cured product)
The epoxy monomer dispersion sol of Examples 1 to 5 and Comparative Example 1 was mixed with an acid anhydride (trade name MH-700, manufactured by Shin Nippon Rika Co., Ltd.) as a curing agent and Hishikorin PX-4ET (trade name, manufactured by Nippon Kagaku Kogyo Co., Ltd.) as a reaction accelerator in the amounts shown in Table 1, and homogenized using a vacuum defoaming mixer (V-mini300, manufactured by EME) to obtain an epoxy resin curing composition. The epoxy resin curing composition thus obtained was poured into a casting plate (a glass plate treated with a fluorine-based release agent, the distance between the two glass plates being 3 mm thick) and heat-treated at 100°C for 2 hours, followed by heat treatment at 150°C for 5 hours to obtain an epoxy resin thermoset.

Further, as a reference example, an epoxy resin containing no silica was used, and the same operation as described above was performed to obtain an epoxy resin thermoset.
Reference example 1: TEPIC-VL
Reference example 2: TEPIC-FL
Reference Example 3: Celoxide 2021P
Reference Example 4: TEPIC-VL/TEPIC-FL = 50/50 mixture Physical properties of the obtained cured product are shown in Tables 3 and 4. The epoxy resin cured product of the present invention can achieve both high flexibility, high transparency and low CTE.

In the table below,
Nitrogen-containing epoxy monomer dispersion sol 1 obtained in Example 1 is abbreviated as sol N1.
Nitrogen-containing epoxy monomer dispersion sol 2 obtained in Example 2 is abbreviated as sol N2.
Nitrogen-containing epoxy monomer dispersion sol 3 obtained in Example 3 is abbreviated as sol N3.
Nitrogen-containing epoxy monomer dispersion sol 4 obtained in Example 4 was abbreviated as sol N4.
Nitrogen-containing epoxy monomer dispersion sol 5 obtained in Example 5 is abbreviated as sol N5.
Alicyclic epoxy monomer dispersion sol 1 obtained in Comparative Example 1 was abbreviated as sol S1.
The trade name TEPIC-VL, which is an epoxy monomer, is abbreviated as Epoxy 1.
An epoxy monomer mixture obtained by mixing epoxy monomers TEPIC-VL (trade name) and TEPIC-FL (trade name) at a mass ratio of 1:1 is abbreviated as Epoxy 2.
The trade name Celoxide 2021P, which is an epoxy monomer, is abbreviated as Epoxy 3.

[Table 1]
Table 1 Epoxy resin composition ――――――――――――――――――――――――――――――――――――――――
Example 1 Example 2 Example 3 Example 4 Example 5
Epoxy monomer sol Sol N1 Sol N2 Sol N3 Sol N4 Sol N5
Amount added (g) 40 40 40 40 40
Epoxy monomer -- -- -- -- --
Amount added (g) 0 0 0 0 0
MH-700 (g) 32.8 33.1 22.8 23.0 14.1
PX-4ET (g) 0.28 0.28 0.28 0.28 0.25
_SiO2 content (%) 17.1 16.8 19.8 19.4 46.7
――――――――――――――――――――――――――――――――――――――――

[Table 2]
Table 2 Epoxy resin composition ――――――――――――――――――――――――――――――――――――――――
Reference Example 1 Reference Example 2 Reference Example 3 Reference Example 4 Comparative Example 1
Epoxy Monomer Sol -- -- -- -- Sol S1
Amount added (g) 0 0 0 0 40
Epoxy monomer Epoxy 1 Epoxy 1 Epoxy 3 Epoxy 2 ---
Amount added (g) 25 25 25 20 0
MH-700 (g) 31.5 22.2 31.7 14.1 29.1
PX-4ET (g) 0.25 0.25 0.25 0.25 0.40
_SiO2 content (%) 0 0 0 0 18.0
――――――――――――――――――――――――――――――――――――――――

[Table 3]
Table 3 Physical properties of thermosets of epoxy resin compositions――――――――――――――――――――――――――――――――――――――
Example 1 Example 2 Example 3 Example 4 Example 5
Flexural modulus (MPa) 3705 3708 3035 3034 5785
Displacement (mm) 11.1 13.9 16.7 20.2 9.4
Bending strain (%) 5.0 6.4 7.5 9.1 4.2
Transmittance (%) 90.0 84.6 87.9 85.8 3.9
CTEα1 (ppm/K) 64 62 74 77 46
CTEα2 (ppm/K) 150 151 163 166 117
――――――――――――――――――――――――――――――――――――――――

[Table 4]
Table 4 Physical properties of the thermoset of the epoxy resin composition ――――――――――――――――――――――――――――――――――――――
Reference Example 1 Reference Example 2 Reference Example 3 Reference Example 4 Comparative Example 1
Flexural modulus (MPa) 3077 2371 3290 2723 3977
Displacement (mm) 17.3 16.7 10.8 20.8 7.2
Bending strain (%) 7.8 7.5 4.9 9.2 3.3
Transmittance (%) 91.1 87.9 91.9 90.5 91.1
CTEα1 (ppm/K) 66 88 68 81 63
CTEα2 (ppm/K) 163 181 162 172 151
――――――――――――――――――――――――――――――――――――――――

It is possible to provide a silica sol with high dispersion stability in which silica particles are dispersed as a dispersoid in an epoxy compound containing a long-chain alkylene group, which is liquid and has high handleability, high heat resistance and toughness when cured, as a dispersion medium, a method for producing the same, a cured body-forming composition, and a cured body thereof.

Claims (16)

A silica sol containing a dispersion medium containing an epoxy compound (A) represented by the following formula (1) and a dispersoid containing silica particles (B) having an average particle size of 5 to 500 nm as determined by a dynamic light scattering method.

(In Formula (1), L ¹ to L ³ each represent a hydrocarbon group having 2 to 7 carbon atoms, and R ¹ to R ³ each represent a hydrogen atom or a methyl group.) 2. The silica sol according to claim 1, wherein the epoxy compound (A) of formula (1) is a liquid epoxy compound in which each of L ¹ to L ³ has a hydrocarbon group of 3 to 7 carbon atoms. The silica sol according to claim 1 or claim 2, wherein the silica particles (B) contain alkoxy groups consisting of methoxy groups or ethoxy groups on their surfaces, and the alkoxy groups are bonded at a ratio of 0.6 to 3.0/ ^nm2 . Formulas (2) to (4) in which the silica particles (B) are silane compounds having an organic group directly bonded to a silicon atom:

(In the formula (2), each R ¹ is an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, or cyano group and is bonded to a silicon atom via a Si—C bond, each R ² represents an alkoxy group, an acyloxy group, or a halogen group, a represents an integer of 1 to 3,
In formulas (3) and (4), R ³ and R ⁵ are each an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms and are bonded to a silicon atom via a Si—C bond; R ⁴ and R ⁶ each represent an alkoxy group, an acyloxy group, or a halogen group; Y represents an alkylene group, an NH group, or an oxygen atom; b is an integer of 1 to 3; is. )
4. The silica sol according to any one of claims 1 to 3, which is coated with at least one silane compound selected from the group consisting of: The silica sol according to any one of claims 1 to 4, wherein the viscosity after storage for 14 days at 50°C at a silica concentration of 60% by mass is in the range of 1.0 to 30 times the value of the viscosity at 25°C of only the dispersion medium used for the silica sol. 6. The silica sol according to any one of claims 1 to 5, wherein the dispersion medium further contains a liquid epoxy compound other than formula (1). 7. The silica sol according to claim 6, wherein the liquid epoxy other than formula (1) is a non-cyanuric acid liquid epoxy compound. The silica sol according to claim 7, wherein the non-cyanuric acid liquid epoxy compound is a bisphenol epoxy compound or an alicyclic epoxy compound. 9. The silica sol according to any one of claims 1 to 8, further comprising a basic substance consisting of an amine, ammonia, an inorganic alkali compound, or a quaternary ammonium compound. A cured body-forming composition comprising the silica sol according to any one of claims 1 to 9 and a curing agent. 11. The cured body-forming composition according to claim 10, wherein the curing agent is an acid anhydride, an amine, or an acid generator. A cured product formed from the cured product-forming composition according to claim 10 . The following steps (I) to (III):
(I) step: step (I) of producing a silica sol using methanol or ethanol as a dispersion medium;
(II) step: step (II) of mixing the silica sol obtained in step (I) and epoxy compound (A) represented by formula (1) to obtain silica sol;
10. The method for producing a silica sol according to any one of claims 1 to 9, comprising a step (III): removing methanol or ethanol from the silica sol obtained in step (II). The method for producing a silica sol according to claim 13, wherein step (I) further comprises adding a basic substance selected from amines, ammonia, inorganic alkaline compounds, or quaternary ammonium compounds when the dispersion medium of the silica sol is methanol or ethanol. The method for producing a silica sol according to claim 13, wherein step (I) further comprises a step of coating the silica particles with at least one silane compound selected from the group consisting of formulas (2) to (4) when the dispersion medium of the silica sol is methanol or ethanol. 14. The method for producing a silica sol according to claim 13, wherein step (II) further comprises a step of solvent-substituting the silica sol obtained in step (I) with an organic solvent having a carbonyl structure, an ether structure, or a carbon-carbon bonding structure before mixing the silica sol obtained in step (I) with the epoxy compound (A) represented by formula (1).