TW202428515A - Organic solvent sol of amine-containing hollow silica particles, and method for producing same - Google Patents

Abstract

To provide: an organic solvent sol of hollow silica particles, in which the sol contains an amine, the hollow silica particles have a specific surface charge, exhibit high dispersibility in a resin, and have a space inside an outer shell; a method for producing same; and a film-forming composition. Provided is an organic solvent sol of hollow silica particles, in which the sol contains an amine and the hollow silica particles have a space inside an outer shell. The amine is at least one type of amine selected from among a primary amine, secondary amine and tertiary amine having a total of 1-10 carbon atoms. The water solubility of the amine is 80 g/L or more. The content of the amine is 0.001-10 mass% relative to SiO2 in the hollow silica particles. The average particle diameter of the hollow silica particles, as measured using a dynamic light-scattering method, is 20-150 nm. The surface charge amount is 5-250 [mu]eq/g, as calculated per 1 g of SiO2 in the hollow silica particles. The organic solvent is an alcohol, ketone, ether or ester having 1-10 carbon atoms. Also provided is a film-forming composition that contains the organic solvent sol of hollow silica particles and an organic resin.

Description

Organic solvent sol of hollow silicon oxide particles containing amine and its production method

The present invention relates to a sol containing amine and hollow silicon oxide particles dispersed in an organic solvent, a method for preparing the sol, and a film forming composition containing the sol.

Hollow silica particles having a shell of silica and a space inside the shell have low refractive index, low thermal conductivity (thermal insulation), electrical insulation and other properties due to these characteristics. The hollow silica particles are composed of a core corresponding to a hollow portion and a shell forming the outer side of the core. An aqueous dispersion of the hollow silica particles is obtained by forming a silica layer on the outer side of the core in an aqueous medium and then removing the core. For example, a transparent coating forming composition containing hollow silica particles having a surface charge of 5 to 20 μeq/g- _SiO2 and a binder component has been disclosed (see patent document 1). Hollow silica particles whose surfaces are coated with a silane compound and whose thermal weight loss at 200°C to 500°C is 1% by mass or more have also been disclosed (see patent document 2). [Prior art literature] [Patent literature]

[Patent Document 1] International Publication No. 2007-060884 [Patent Document 2] Japanese Patent Publication No. 2013-014506

[Problems solved by the invention]

The present invention provides an organic solvent sol containing amine in the sol and hollow silicon oxide particles having a space inside the outer shell, a method for producing the sol, and a film-forming composition containing the sol. [Means for Solving the Problem]

As a first aspect of the present invention, an organic solvent sol containing an amine in the sol and having a hollow silica particle with a space inside the shell; as a second aspect, the sol described in the first aspect, wherein the amine is at least one amine selected from the group consisting of a first amine, a second amine, and a third amine having a carbon number of 1 to 10; as a third aspect, the sol described in the first aspect or the second aspect, wherein the amine is a water-soluble amine having a water solubility of 80 g/L or more; as a fourth aspect, the sol described in any one of the first to third aspects, wherein the amine content is 0.001 to 10 mass % relative to _SiO2 of the hollow silica particle; As a fifth aspect, the sol described in any one of the first to fourth aspects, wherein the average particle size of the hollow silica particles as measured by a dynamic light scattering method is 20 to 150 nm; As a sixth aspect, the sol described in any one of the first to fifth aspects, wherein the surface charge of _SiO2 per 1 g of the hollow silica particles is 5 to 250 μeq/g; As a seventh aspect, the sol described in any one of the first to sixth aspects, wherein the organic solvent is an alcohol, ketone, ether or ester having 1 to 10 carbon atoms; As an eighth aspect, the hollow silica particles are further coated with at least one silane compound selected from the group consisting of silane compounds represented by formula (1), formula (2) and formula (3); (In formula (1), ^R1 represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having an epoxy group, a (meth)acryl group, an alkyl group, an amine group, an ureido group, or a cyano group, and is bonded to the silicon atom via a Si-C bond, ^R2 represents an alkoxy group, an acyloxy group, or a halogen group, and a is an integer of 1 to 3. In formula (2) and formula (3), ^R3 and ^R5 represent an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms, and are bonded to the silicon atom via a Si-C bond, and ^R4 and R5 represent an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms, and are bonded to the silicon atom via a Si-C bond, ⁶ each represents 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, c is an integer of 0 or 1, and d is an integer of 1 to 3), as a 9th aspect, a film-forming composition comprising a sol as described in any one of the 1st to 8th aspects and an organic resin, as a 10th aspect, a film obtained from the film-forming composition having a visible light transmittance of 80% or more described in the 9th aspect, as an 11th aspect, a method for producing a sol as described in any one of the 1st to 8th aspects comprising the following steps (A) to (C), (A) step: a step of preparing a hollow silica aqueous sol, (B) step: adding at least one amine selected from the group consisting of first-class amines, second-class amines and third-class amines having a water solubility of 80 g/L or more and having a carbon number of 1 to 10 to the hollow silica aqueous sol in step (A) at a ratio of 0.001 to 10 mass % relative to _SiO2 of the hollow silica particles; (C) step: replacing the aqueous medium of the aqueous sol of the hollow silica particles obtained in step (B) with an alcohol, ketone, ether or ester having a carbon number of 1 to 10. As a twelfth aspect, the method for producing a sol according to the eleventh aspect further comprises the step (D) of adding at least one silane compound selected from the group consisting of the silane compounds represented by the above formula (1), formula (2) and formula (3) after the above step (C) is completed, and then heating. As a thirteenth aspect, the method for producing a sol according to the eleventh aspect or the twelfth aspect, wherein the above step (C) is the step of replacing the solvent of the above aqueous medium with an alcohol having 1 to 10 carbon atoms and then further replacing the solvent with a ketone, ether or ester having 1 to 10 carbon atoms. As a 14th aspect, step (C) is a step of replacing the aqueous medium with an alcohol having 1 to 10 carbon atoms as a solvent, and step (D) is a step of adding at least one silane compound selected from the group consisting of silane compounds represented by formula (1), formula (2) and formula (3) and further replacing the alcohol solvent with a ketone, ether or ester having 1 to 10 carbon atoms as a solvent after heating; and as a 15th aspect, a method for adjusting the surface charge of hollow silicon oxide particles using the production method described in any one of the 11th to 14th aspects. [Effects of the Invention]

The present invention relates to an organic solvent sol containing amine in the sol and hollow silica particles having spaces inside the outer shell. It is known that the surface of the hollow silica particles dispersed in the organic solvent has a charge. When the organic solvent sol of the hollow silica particles itself or the organic solvent sol of the hollow silica particles is mixed with an organic resin binder, the surface charge of the hollow silica particles has a great influence on the stability or dispersibility. For example, when the hollow silica particles are dispersed in a highly polar solvent or resin binder, stable dispersibility can be obtained when the surface charge of the hollow silica particles is within a specific range. Stable dispersion is required because when forming a film, the hollow silicon oxide particles are uniformly present in the hardened film, not locally, which is good for exerting their functions. In the hardened film, the hollow silicon oxide particles are non-locally present, so the entire film can be made uniform. This effect is better when preventing optical reflection because it can keep the entire film uniform.

It is also known that the surface charge of hollow silica particles in a dispersion medium is due to the silanol groups on the surface of the silica particles, but by adding amines, the surface charge can be arbitrarily adjusted to a specific range. The present invention is an organic solvent sol containing amines in the sol and hollow silica particles having spaces inside the outer shell, a method for producing such an organic solvent sol, and a film-forming composition using such an organic solvent sol.

[Type of implementation of the invention]

The present invention is an organic solvent sol containing amine in the sol and having hollow silica particles with spaces inside the shell (hereinafter also referred to as hollow silica organic solvent sol).

Hollow silica particles have a shell of silica and a space inside the shell. Hollow silica particles are obtained by forming a shell with silica as the main component on the surface of a core part called a so-called template in a dispersion medium, and removing the part corresponding to the core. The aqueous hollow silica sol (aqueous hollow silica sol) thus obtained can be substituted with an alcohol solvent as an organic solvent after adding amine. The above-mentioned alcohol solvent is preferably an alcohol having 1 to 5 carbon atoms and having an ether bond, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc. Afterwards, the hollow silicon oxide particles are coated with a silane compound as required, and the solvent can be further replaced by other organic solvents.

In the present invention, the organic solvent includes alcohols, ketones, ethers and esters having 1 to 10 carbon atoms.

Alcohols having 1 to 10 carbon atoms are aliphatic alcohols, and primary alcohols, secondary alcohols, and tertiary alcohols can be mentioned. Polyols can also be used as alcohols, for example, dihydric alcohols and trihydric alcohols can be mentioned. As monovalent primary alcohols, methanol, ethanol, 1-propanol, 1-butanol, 1-hexanol, etc. can be mentioned. As monovalent secondary alcohols, 2-propanol, 2-butanol, cyclohexanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc. can be mentioned. As monovalent tertiary alcohols, Tert-butyl alcohol, etc. can be mentioned. As dihydric alcohols, methanediol, ethylene glycol, propylene glycol, etc. can be mentioned. As trihydric alcohols, glycerol, etc. can be mentioned.

As the ketone having 1 to 10 carbon atoms, aliphatic ketones are preferably used, for example, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, methyl cyclopentanone and the like.

As the ether having 1 to 10 carbon atoms, aliphatic ethers are preferably used, and examples thereof include dimethyl ether, ethyl methyl ether, diethyl ether, tetrahydrofuran, and 1,4-dioxane.

As the ester having 1 to 10 carbon atoms, aliphatic esters are preferably used. For example, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate, dimethyl maleate, diethyl maleate, dipropyl maleate, dimethyl adipate, diethyl adipate, dipropyl adipate and the like can be cited.

In the hollow silica aqueous sol and hollow silica organic solvent sol as the above raw materials, the average particle size of the hollow silica particles obtained by dynamic light scattering (DLS) can be in the range of 20 to 150 nm, or 30 to 150 nm, or 40 to 150 nm, or 50 to 150 nm, or 60 to 150 nm, or 60 to 120 nm. In addition, the concentration of _SiO2 particles can be 1 to 50 mass % or 5 to 40 mass %, and generally can be 10 to 30 mass %.

In the above sol, the pH shows alkalinity, for example, 7.5 to 12 or 7.5 to 11, and generally the range of 7.5 to 10 can be used. The above pH is the pH when the organic solvent sol is mixed with pure water of the same mass at a ratio of 1:1. When an organic solvent that can be mixed with water is used as an organic solvent, the pH can be measured, but when the solvent is subsequently replaced by a hydrophobic organic solvent, it is better to measure the pH in advance at the stage of the methanol solvent sol. For example, for a hydrophilic organic solvent sol, such as a dispersing medium such as a methanol sol and a propylene glycol monomethyl ether sol, the pH of a solution in which pure water and the sol are mixed at a mass ratio of 1:1 can be measured. For hydrophobic organic solvent sols, such as dispersants such as methyl ethyl ketone sol, the pH of the solution can be measured by mixing pure water, methanol and methyl ethyl ketone sol in a mass ratio of 1:1:1.

In the hollow silica organic solvent sol, the aqueous medium of the aqueous sol can be replaced by an alcohol solvent with 1 to 5 carbon atoms, and can be further replaced by an organic solvent as needed. In the process, water can also be retained in the solvent. In the alcohol sol stage of the hollow silica particles, for example, 0.1 to 3.0% by mass of residual water can be contained in the sol. Then, in the organic solvent sol stage of the hollow silica particles, 0.01 to 0.5% by mass of residual water can be contained.

In addition, the viscosity of the hollow silica organic solvent sol can be set within the range of 1.0 to 10.0 mPa·s.

Amines can be added to the hollow silica organic solvent sol of the present invention. As the amines that can be used in the present invention, water-soluble amines with a water solubility of 80 g/L or more, or 100 g/L or more can be used.

The hollow silica aqueous sol as a raw material, the hollow silica organic solvent sol obtained by solvent substitution, may contain amine or amine and ammonia. For _SiO2 of the hollow silica particles, amine in the range of 0.001-10 mass%, or 0.01-10 mass%, or 0.1-10 mass% may be added. Then, the alkali component of the amine or amine and ammonia can be expressed as the total nitrogen content in the hollow silica particle organic solvent sol, for example, it can be contained in the range of 10-100000ppm, or 100-10000ppm, or 100-3000ppm, or 100-2000ppm, generally in the range of 200-2000ppm.

As the above-mentioned amine, aliphatic amine and aromatic amine can be cited, and aliphatic amine can be preferably used. As the amine, at least one amine selected from the group consisting of first-class amine, second-class amine and third-class amine having 1 to 10 carbon atoms can be used. These amines are water-soluble and are at least one amine selected from the group consisting of first-class amine, second-class amine and third-class amine having 1 to 10 carbon atoms.

For example, as the first-class amine, there can be cited monomethylamine, monoethylamine, monopropylamine, monoisopropylamine, monobutylamine, monoisobutylamine, monosec-butylamine, monotert-butylamine, monomethanolamine, monoethanolamine, monopropanolamine, monoisopropanolamine, monobutanolamine, monoisobutanolamine, monosec-butanolamine, monotert-butanolamine and the like.

Examples of the secondary amine include dimethylamine, diethylamine, dipropylamine, diisopropylamine, N-methylethylamine, N-ethylisobutylamine, dimethanolamine, diethanolamine, dipropanolamine, diisopropanolamine, N-methanolethylamine, N-methylethanolamine, N-ethanolisobutylamine, and N-ethylisobutanolamine.

As the tertiary amine, there can be cited trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, triisobutylamine, trisecbutylamine, tritertbutylamine, trimethanolamine, triethanolamine, tripropanolamine, triisopropanolamine, tributanolamine, triisobutanolamine, trisecbutanolamine, tritertbutanolamine and the like.

As the above-mentioned amine, an amine having a water solubility of 80 g/L or more or 100 g/L or more can be preferably used. As such amines, first-class amines and second-class amines are preferred, and second-class amines are preferred due to their low volatility and high solubility, such as diisopropylamine, diethanolamine, etc.

In the present invention, when the sol contains the above-mentioned amine, the surface charge amount per 1g of _SiO2 converted into hollow silicon oxide particles can be set to be above 5μeq/g, or above 25μeq/g. Generally, it can be set in the range of 5 to 250μeq/g, or 25 to 250μeq/g, or 25 to 100μeq/g, or 25 to 80μeq/g, or 25 to 50μeq/g. In the present invention, by adjusting the type or addition amount of the above-mentioned amine, the surface charge amount of the hollow silicon oxide particles can be adjusted to any surface charge amount.

In the present invention, the surface of the hollow silicon oxide particles can be coated with a silane compound. As the silane compound, a hydrolyzate of at least one silane compound selected from the group consisting of silane compounds represented by formula (1) to formula (3) can be used. In the above formula (1), ^R1 each represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having a polyether group, an epoxy group, a (meth)acryl group, an alkyl group, an amine group, an urea group, or a cyano group, and a group bonded to the silicon atom via a Si-C bond, ^R2 each represents an alkoxy group, an acyloxy group, or a halogen group, and a is an integer of 1 to 3. In the above formulas (2) and (3), ^R3 and ^R5 each represent an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms, and a group bonded to the silicon atom via a Si-C bond, ^R4 and ^R6 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, c is an integer of 0 or 1, and d is an integer of 1 to 3.

Examples of the alkyl group include an alkyl group having 1 to 18 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a cyclopropyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, a cyclobutyl group, a 1-methyl-cyclopropyl group, a 2-methyl-cyclopropyl group, an n-pentyl group, a 1-methyl-n-butyl group, a 2-methyl-n-butyl group, a 3-methyl-n-butyl group, a 1,1-dimethyl-n-propyl group, a 1,2-dimethyl-n-propyl group, a 2,2-dimethyl-n-propyl group, a 1-ethyl-n-propyl group, a cyclopentyl group, a 1-methyl-cyclobutyl group, a 2-methyl-cyclobutyl group, a 3-methyl-n-butyl group, -methyl-cyclobutyl, 1,2-dimethyl-cyclopropyl, 2,3-dimethyl-cyclopropyl, 1-ethyl-cyclopropyl, 2-ethyl-cyclopropyl, n-hexyl, 1-methyl-n-pentyl, 2-methyl-n-pentyl, 3-methyl-n-pentyl, 4-methyl-n-pentyl, 1,1-dimethyl-n-butyl, 1,2-dimethyl-n-butyl, 1,3-dimethyl-n-butyl, 2,2-dimethyl-n-butyl, 2,3-dimethyl-n-butyl, 3,3-dimethyl-n-butyl, 1-ethyl-n-butyl, 2-ethyl-n-butyl, 1,1, 2-Trimethyl-n-propyl, 1,2,2-trimethyl-n-propyl, 1-ethyl-1-methyl-n-propyl, 1-ethyl-2-methyl-n-propyl, cyclohexyl, 1-methyl-cyclopentyl, 2-methyl-cyclopentyl, 3-methyl-cyclopentyl, 1-ethyl-cyclobutyl, 2-ethyl-cyclobutyl, 3-ethyl-cyclobutyl, 1,2-dimethyl-cyclobutyl, 1,3-dimethyl-cyclobutyl, 2,2-dimethyl-cyclobutyl, 2,3-dimethyl-cyclobutyl, 2,4-dimethyl-cyclobutyl, 3,3-dimethyl-cyclobutyl, 1-n-propyl-cyclopropyl The invention also includes, but is not limited to, 2-n-propyl-cyclopropyl, 1-i-propyl-cyclopropyl, 2-i-propyl-cyclopropyl, 1,2,2-trimethyl-cyclopropyl, 1,2,3-trimethyl-cyclopropyl, 2,2,3-trimethyl-cyclopropyl, 1-ethyl-2-methyl-cyclopropyl, 2-ethyl-1-methyl-cyclopropyl, 2-ethyl-2-methyl-cyclopropyl and 2-ethyl-3-methyl-cyclopropyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl.

Furthermore, examples of the alkylene group include alkylene groups derived from the above-mentioned alkyl groups.

Examples of the aryl group include aryl groups having 6 to 30 carbon atoms, such as phenyl, naphthyl, anthracenyl, pyrenyl, etc., but are not limited thereto.

Examples of the alkenyl group include alkenyl groups having 2 to 10 carbon atoms, such as vinyl, 1-propenyl, 2-propenyl, 1-methyl-1-vinyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylvinyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-n-propylvinyl, 1-methyl-1-butenyl, 1-methyl-2-butenyl, 1-methyl-3-butenyl, 2-ethyl-2-propenyl, 2-methyl-1-butenyl, 2-methyl-2-butenyl, 2-methyl-3-butenyl, The present invention also includes, but is not limited to, 1-butylene group, 3-methyl-1-butenyl, 3-methyl-2-butenyl, 3-methyl-3-butenyl, 1,1-dimethyl-2-propenyl, 1-i-propylvinyl, 1,2-dimethyl-1-propenyl, 1,2-dimethyl-2-propenyl, 1-cyclopentenyl, 2-cyclopentenyl, 3-cyclopentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 1-methyl-1-pentenyl, 1-methyl-2-pentenyl, 1-methyl-3-pentenyl, 1-methyl-4-pentenyl, 1-n-butylvinyl, 2-methyl-1-pentenyl, 2-methyl-2-pentenyl, and the like.

Examples of the alkoxy group include alkoxy groups 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, 1,1-dimethyl-n-propoxy, 1,2-dimethyl-n-propoxy, 2,2-dimethyl-n-propoxy, 1-ethyl-n-propoxy, and n-hexyloxy.

Examples of the acyloxy group include acyloxy groups having 2 to 10 carbon atoms, such as methylcarbonyloxy, ethylcarbonyloxy, n-propylcarbonyloxy, i-propylcarbonyloxy, n-butylcarbonyloxy, i-butylcarbonyloxy, s-butylcarbonyloxy, t-butylcarbonyloxy, n-pentylcarbonyloxy, 1-methyl-n-butylcarbonyloxy, 2-methyl-n-butylcarbonyloxy, 3-methyl-n-butylcarbonyloxy, 1,1-dimethyl-n-propylcarbonyloxy, 1,2-dimethyl-n-propylcarbonyloxy, 2,2-dimethyl-n-propylcarbonyloxy, 1-ethyl-n-propylcarbonyloxy, n-hexylcarbonyloxy, 1-methyl-n-pentylcarbonyloxy, and 2-methyl-n-pentylcarbonyloxy.

Examples of the halogen group include fluorine, chlorine, bromine, iodine and the like.

As the organic group having a polyether group, there can be mentioned a polyether propyl group having an alkoxy group. For example, there can be mentioned (CH ₃ O) ₃ SiC ₃ H ₆ (OC ₂ H ₄ )nOCH ₃ . n can be 1-100, or in the range of 1-10.

Examples of the organic group having an epoxy group include 2-(3,4-epoxycyclohexyl)ethyl and 3-glycidoxypropyl.

The (meth)acryloyl group refers to both an acryl group and a methacryloyl group. Examples of the organic group having a (meth)acryloyl group include a 3-methacryloyloxypropyl group and a 3-acryloyloxypropyl group.

Examples of the organic group having a butyl group include a 3-butylpropyl group.

Examples of the organic group having an amino group include 2-aminoethyl, 3-aminopropyl, N-2-(aminoethyl)-3-aminopropyl, N-(1,3-dimethyl-butylene)aminopropyl, N-phenyl-3-aminopropyl, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyl.

As the organic group having a ureido group, for example, there can be mentioned a 3-ureidopropyl group.

Examples of the organic group having a cyano group include a 3-cyanopropyl group.

The silane compounds represented by the above formula (2) and formula (3) are preferably compounds that form trimethylsilyl groups on the surface of silicon oxide particles. Examples of such compounds include the following. In the above formula, R ¹² represents an alkoxy group, and examples thereof include methoxy and ethoxy. As the above silane compound, a silane compound manufactured by Shin-Etsu Chemical Co., Ltd. can be used.

The hydroxyl groups on the surface of the silicon oxide particles, for example, can be silicon oxide particles. After the silanol groups react with the above-mentioned silane compound, the surface of the silicon oxide particles can be coated with the above-mentioned silane compound through siloxane bonding. The reaction can be carried out at a temperature ranging from 20°C to the boiling point of the dispersion medium, for example, at a temperature ranging from 20°C to 100°C. The reaction can be carried out for about 0.1 to 6 hours.

For the surface of silicon oxide particles, a silane compound with a coating amount corresponding to 0.1 to ^6.0 silicon atoms/nm ² in the silane compound is added to the silicon oxide sol to coat the surface of the hollow silicon oxide particles.

Water is required for the hydrolysis of the above-mentioned silane compounds, but if it is a sol of an aqueous solvent, such an aqueous solvent can also be used. When the aqueous medium is replaced by an organic solvent, the water remaining in the solvent can also be used. For example, 0.01 to 1 mass % of water in the organic solvent can be used. In addition, the hydrolysis can be carried out using a catalyst or without a catalyst. The case where the hydrolysis is carried out without a catalyst is the case where there is an acidic surface on the surface of the silicon oxide particles. When a catalyst is used, metal chelate compounds, organic acids, inorganic acids, organic bases, and inorganic bases can be cited as hydrolysis catalysts. Examples of metal chelate compounds as hydrolysis catalysts include triethoxy mono(acetylacetonato)titanium and triethoxy mono(acetylacetonato)zirconium. Examples of organic acids as hydrolysis catalysts include acetic acid and oxalic acid. Examples of inorganic acids as hydrolysis catalysts include 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. Examples of inorganic bases as hydrolysis catalysts include ammonia, sodium hydroxide, and potassium hydroxide.

As the organic acid, at least one organic acid selected from the group consisting of divalent aliphatic carboxylic acids, aliphatic oxycarboxylic acids, amino acids and chelating agents can be cited. As the divalent aliphatic carboxylic acids, oxalic acid, malonic acid and succinic acid can be cited. As the aliphatic oxycarboxylic acids, glycolic acid, lactic acid, malic acid, tartaric acid and citric acid can be cited. As the amino acids, glycine, alanine, valine, leucine, serine and threonine can be cited. As the chelating agents, ethylenediaminetetraacetic acid, L-aspartic acid-N,N-diacetic acid and diethylenetriaminepentaacetic acid can be cited. As the organic acid salts, alkali metal salts, ammonium salts and amine salts of the above organic acids can be cited. As alkaline metals, sodium and potassium can be mentioned.

In the present invention, a film-forming composition containing the above-mentioned hollow silica organic solvent sol and organic resin can be obtained.

As the organic resin, a thermosetting or photocuring resin is selected and mixed to obtain a coating forming composition. Then, a hardener containing a hardener such as an amine hardener, an acid anhydride hardener, a free radical generator hardener (thermal free radical generator, photo free radical generator), or an acid generator hardener (thermal acid generator, or photo acid generator) may be prepared.

The film-forming composition of the present invention contains an organic resin and a hardener. After the film-forming composition is applied or filled on a substrate, it can be heated, irradiated with light or combined to form a hardened material. As the organic resin (hardening resin), resins having functional groups such as epoxy or (meth)acrylic groups, or isocyanate resins can be cited. For example, light-hardening multifunctional acrylates are preferably used.

Examples of the multifunctional acrylate include those having bifunctional, trifunctional, tetrafunctional, or higher functional groups in the molecule, such as neopentyl glycol di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. These multifunctional acrylates may be those listed below.

The film-forming composition of the present invention may contain a surfactant (leveling agent). As the surfactant (leveling agent), negative ionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants and silicone surfactants can be used. The surfactant (leveling agent) can be added to the organic resin in a range of 0.01 to 5 phr, or 0.01 to 1 phr.

As the negative ion surfactant used in the present invention, sodium and potassium salts of fatty acids, alkylbenzene sulfonates, higher alcohol sulfates, polyoxyethylene alkyl ether sulfates, α-sulfonic fatty acid esters, α-olefin sulfonates, monoalkyl phosphates and alkane sulfonates can be cited.

For example, as the alkylbenzenesulfonate salt, there can be mentioned a sodium salt, a potassium salt and a lithium salt, and there can be mentioned sodium C10-C16 alkylbenzenesulfonate, C10-C16 alkylbenzenesulfonic acid, sodium alkylnaphthalenesulfonate and the like.

As the higher alcohol sulfate ester salt, there can be cited sodium dodecyl sulfate (sodium lauryl sulfate) having 12 carbon atoms, triethanolamine lauryl sulfate, triethanolammonium lauryl sulfate, and the like.

Examples of the polyoxyethylene alkyl ether sulfates include polyoxyethylene styrenated phenyl ether sodium sulfate, polyoxyethylene styrenated phenyl ether ammonium sulfate, polyoxyethylene decyl ether sodium sulfate, polyoxyethylene decyl ether ammonium sulfate, polyoxyethylene lauryl ether sodium sulfate, polyoxyethylene lauryl ether ammonium sulfate, polyoxyethylene tridecyl ether sodium sulfate, and polyoxyethylene oleyl cetyl ether sodium sulfate.

As the α-olefin sulfonate, sodium α-olefin sulfonate and the like can be mentioned.

As the alkane sulfonate, sodium 2-ethylhexyl sulfate and the like can be mentioned.

Examples of the cationic surfactant used in the present invention include alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, alkyl dimethyl benzyl ammonium salts, and amine salt-based agents.

Alkyl trimethyl ammonium salts are quaternary ammonium salts, which have a counter ion of a chloride ion or a bromide ion. Examples include dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, coconut oil alkyl trimethyl ammonium chloride, and alkyl (C16-18) trimethyl ammonium chloride.

Dialkyl dimethyl ammonium salts have two main chains that are lipophilic, namely two methyl groups. Examples include bis(hydrogenated tallow) dimethyl ammonium chlorides, such as didecyl dimethyl ammonium chloride, dicocoalkyl dimethyl ammonium chloride, distearyl tallow alkyl dimethyl ammonium chloride, and dialkyl (C14-18) dimethyl ammonium chloride.

Examples of the alkyl dimethylbenzyl ammonium salt include benzalkonium chloride, which is a quaternary ammonium salt having a main chain that is lipophilic, two methyl groups, and one benzyl group, for example, alkyl (C8-18) dimethylbenzyl ammonium chloride.

As the amine salt-based agent, there can be mentioned those in which the hydrogen atom of ammonia is substituted with one or more alkyl groups, for example, N-methyldihydroxyethylamine fatty acid ester hydrochloride.

As the amphoteric surfactant used in the present invention, there can be mentioned alkylamino fatty acid salts of N-alkyl-β-alanine type, alkyl betaines of alkylcarboxy betaine type, and alkyl amine oxides of N,N-dimethyl dodecylamine oxide type. As examples thereof, there can be mentioned lauryl betaine, stearyl betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine, and lauryl dimethyl amine oxide.

The non-ionic surfactant used in the present invention may be selected from polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, alkyl glucosides, polyoxyethylene fatty acid esters, sucrose fatty acid esters, sorbitol fatty acid esters, polyoxyethylene sorbitol fatty acid esters, and fatty acid chain alkanolamides.

For example, as the polyoxyethylene alkyl ether, there can be cited polyoxyethylene dodecyl ether (polyoxyethylene lauryl ether), polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene behenyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene isodecyl ether and the like.

Examples of the polyoxyethylene alkylphenol ether include polyoxyethylene styrenated phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene distyrenated phenyl ether, and polyoxyethylene trityl phenyl ether.

As the alkyl glucoside, there can be mentioned decyl glucoside, lauryl glucoside and the like.

Examples of the polyoxyethylene fatty acid esters include polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, polyethylene glycol distearate, polyethylene glycol dioleate, polypropylene glycol dioleate, and the like.

As the sorbitan fatty acid ester, there can be mentioned sorbitan monocaprylate, sorbitan monolaurate, sorbitan monomyristate, sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan monosemioleate and ethylene oxide adducts thereof.

Examples of the polyoxyethylene sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan triisostearate, and the like.

Examples of fatty acid chain alkanolamides include coconut oil fatty acid diethanolamide, tallow fatty acid diethanolamide, lauric acid diethanolamide, oleic acid diethanolamide, and the like.

Further examples include polyoxyethylene polyoxypropylene glycol, polyoxyalkyl ethers or polyoxyalkyl glycols of polyoxyethylene fatty acid esters, polyoxyethylene hydrogenated castor oil ethers, sorbitan fatty acid ester alkyl ethers, alkyl polyglucosides, sorbitan monooleate, sucrose fatty acid esters, and the like.

The silicone surfactant used in the present invention is a compound having a repeating unit containing a siloxane bond in the main chain. As the silicone surfactant, those with a weight average molecular weight of 500 to 50,000 can be used. These can be modified silicone surfactants, or structures in which organic groups are introduced into the side chains and/or ends of polysiloxane. As organic groups, amino groups, epoxy groups, alicyclic epoxy groups, carbinol groups, hydroxyl groups, carboxyl groups, aliphatic ester groups, aliphatic amide groups, and polyether groups can be cited. As the silicone-based surfactant, there are trade names such as Toray Silicone DC3PA, Toray Silicone SH7PA, Toray Silicone DC11PA, Toray Silicone SH21PA, Toray Silicone SH28PA, Toray Silicone SH29PA, Toray Silicone SH30PA, and Toray Silicone SH8400 (all manufactured by Toray Dow Corning Co., Ltd.), Silwet L-77, L-7280, L-7001, L-7002, L-7200, L-7210, L-7220, L-7230, L7500, L-7600, L-7602, L-7604, L-7605, L-7622, L-7657, L-8500, and L-8610 (all manufactured by Momentive Performance Materials, Inc.), KP-341, KF-6001, KF-6002 (all manufactured by Shin-Etsu Silicone Co., Ltd.), BYK307, BYK323, BYK330 (all manufactured by BICCHEMY CO., LTD.), etc. For example, as the polyether modified silicone, the trade name L-7001 (manufactured by DOWSIL Corporation) is preferably used.

In the present invention, a coating-forming composition containing the above-mentioned organic solvent sol and organic resin is obtained. The coating-forming composition may be a coating-forming composition containing hollow silica particles and organic resin after removing the organic solvent from the organic solvent sol.

When the film-forming composition is a thermosetting film-forming composition, the range of the thermosetting agent contained is 0.01 to 50 phr or 0.01 to 10 phr relative to the resin containing the functional groups such as epoxy or (meth)acryl, for example, the thermosetting agent can be contained in a ratio of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents relative to the functional groups such as epoxy or (meth)acryl. The equivalent of the thermosetting agent relative to the curable resin is shown as the equivalent ratio of the thermosetting agent relative to the functional groups of the curable resin.

As the thermosetting agent, phenol resin, amine-based hardener, polyamide resin, imidazole, polymercaptan, acid anhydride, thermal free radical generator, thermal acid generator, etc. can be cited. In particular, free radical generator-based hardener, acid anhydride-based hardener, and amine-based hardener are preferred. When these thermosetting agents are solid, they can be used by dissolving them in a solvent, but the evaporation of the solvent will reduce the density of the hardened material or generate pores to reduce the strength and reduce water resistance, so the hardener itself is preferably liquid at room temperature and pressure.

Examples of the phenol resin include phenol novolac resin and cresol novolac resin.

Examples of the amine-based hardener 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, mensendiamine, isophoronediamine, diaminodicyclohexylmethane, 1,3-diaminomethylcyclohexane, xylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, 3,3′-diethyl-4,4′-diaminodiphenylmethane, and diethyltoluenediamine. Among these, liquid diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, mensendiamine, isophoronediamine, diaminodicyclohexylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, diethyltoluenediamine, etc. are preferred.

Examples of the polyamide resin include those produced by condensation of a dimer acid and a polyamine, and for example, polyamide amine having a primary amine and a secondary amine in the molecule.

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

Polythiol includes, for example, a thiol group at the end of a polypropylene glycol chain or a thiol group at the end of a polyethylene glycol chain, but preferably a liquid one.

As the acid anhydride hardener, an anhydride of a compound having a plurality of carboxyl groups in one molecule is preferred. Examples of such acid anhydride hardeners include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol trimellitate, glycerol trimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylene tetrahydrophthalic anhydride, methylendomethylene tetrahydrophthalic anhydride, methylbutenyl tetrahydrophthalic anhydride, dodecenyl succinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylcyclohexene dicarboxylic anhydride, and chlorendic anhydride.

Examples of the thermal acid generator include sulfonium salts and phosphonium salts, but sulfonium salts are preferably used. For example, the following compounds can be exemplified. In formula (C-1), R represents an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 20 carbon atoms, and an alkyl group having 1 to 12 carbon atoms is particularly preferred.

Among these, methyltetrahydrophthalic anhydride, methyl-5-norbornene-2,3-dicarboxylic anhydride (methylnadic anhydride, methylhumic anhydride), hydrogenated methylnadic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, methylhexahydrophthalic anhydride, and a mixture of methylhexahydrophthalic anhydride and hexahydrophthalic anhydride, which are liquid at room temperature and pressure, are preferred. The viscosity of these liquid anhydrides is about 10 mPas to 1000 mPas when measured at 25°C.

Examples of the thermal radical generator include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methylpropionic acid) dimethyl, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, tert - butyl hydroperoxide, isopropylbenzene hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, benzoyl peroxide, etc. These can be obtained from Tokyo Chemical Industry Co., Ltd.

When obtaining the above-mentioned hardened material, a hardening aid may be used in combination as appropriate. Examples of the hardening aid include organic phosphorus compounds such as triphenylphosphine or tributylphosphine, quaternary phosphonium salts such as ethyltriphenylphosphonium bromide and diethyl methyltriphenylphosphonium phosphate, 1,8-diazabicyclo(5,4,0)undec-7-ene, salt of 1,8-diazabicyclo(5,4,0)undec-7-ene and octyl acid, zinc octylate, and quaternary ammonium salts such as tetrabutylammonium bromide. The content of these hardening aids is 0.001 to 0.1 parts by mass relative to 1 part by mass of the hardener.

The composition can be obtained as a heat-hardening paint by mixing the resin and the hardener and, if necessary, a hardening auxiliary agent. Such mixing can be carried out in a reaction vessel using a stirring blade or a kneader.

The mixing can be carried out by a heat mixing method at a temperature of 60°C to 100°C for 0.5 to 1 hour.

The obtained curable film-forming composition is a thermosetting coating composition, and has an appropriate viscosity when used as a liquid sealing material, for example. The viscosity of the liquid thermosetting film-forming composition can be adjusted arbitrarily, and it can be used as a transparent sealing material for LEDs, etc. by casting methods, potting methods, dispensing methods, printing methods, etc., and can be partially sealed at any position. The liquid thermosetting composition can be directly installed on LEDs, etc. in a liquid state by the above method, and then dried and cured to obtain a cured body.

A thermosetting film-forming composition (thermosetting coating composition) is applied on a substrate and heated at a temperature of 80 to 200° C. to obtain a cured product.

When the film-forming composition is a photocurable resin composition, the photocuring agent (photoradical generator, photoacid generator) may be contained in a range of 0.01 to 50 phr, or 0.01 to 10 phr relative to the resin containing the functional groups such as epoxy or (meth)acrylic groups. For example, the photocuring agent (photoradical generator, photoacid generator) may be contained in a ratio of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents relative to the functional groups such as epoxy or (meth)acrylic groups. The equivalent of the photocuring agent relative to the curable resin is shown as the equivalent ratio of the photocuring agent relative to the functional groups of the resin.

The photoradical generator is not particularly limited as long as it can directly or indirectly generate radicals by light irradiation.

Examples of the photoradical polymerization initiator as the photoradical generator include imidazole compounds, diazo compounds, bisimidazole compounds, N-arylglycine compounds, organic aziride compounds, titanocene compounds, aluminate compounds, organic peroxides, N-alkoxypyridinium salt compounds, and thioxanthone compounds. Examples of the aziride compounds include p-aziride benzaldehyde, p-aziride acetophenone, p-aziride benzoic acid, p-aziride benzaldehyde acetophenone, 4,4'-aziride chalcone, 4,4'-aziride diphenyl sulfide, and 2,6-bis(4'-aziride benzaldehyde)-4-methylcyclohexanone. Examples of the diazo compound include 1-diazo-2,5-diethoxy-4-p-triphenylphenyl boron fluoride, 1-diazo-4-N,N-dimethylaminobenzene chloride, and 1-diazo-4-N,N-diethylaminobenzene boron fluoride. Examples of the diimidazole compound include 2,2'-bis(o-chlorophenyl)-4,5,4',5'-tetrakis(3,4,5-trimethoxyphenyl)1,2'-diimidazole and 2,2'-bis(o-chlorophenyl)4,5,4',5'-tetraphenyl-1,2'-diimidazole. As the titanocene compound, there can be cited dicyclopentadienyl-titanium-dichloride, dicyclopentadienyl-titanium-diphenyl, dicyclopentadienyl-titanium-bis(2,3,4,5,6-pentafluorophenyl), dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,4,6-trifluorophenyl), dicyclopentadienyl-titanium-bis(2,6-di ...3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,4,6-trifluorophenyl), dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), di bis(2,4-difluorophenyl), bis(methylcyclopentadienyl)-titanium-bis(2,3,4,5,6-pentafluorophenyl), bis(methylcyclopentadienyl)-titanium-bis(2,3,5,6-tetrafluorophenyl), bis(methylcyclopentadienyl)-titanium-bis(2,6-difluorophenyl) and dicyclopentadienyl-titanium-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl).

As photo-free radical generators, 1,3-di(tert-butyldioxycarbonyl)benzophenone, 3,3',4,4'-tetrakis(tert-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, 2-butylbenzimidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone can be cited.

Such photoradical polymerizers include, for example, Irgacure TPO manufactured by BASF (the ingredient is 2,4,6-trimethylbenzyldiphenylphosphine oxide) (c1-1-1), Omnirad819 manufactured by IGM RESINS (the ingredient is bis(2,4,6-trimethylbenzyl)phenylphosphine oxide) (c1-1-2), and Irgacure 184 manufactured by IGM RESINS (the ingredient is 1-hydroxycyclohexyl phenyl ketone) (c1-1-3).

The photoacid generator is not particularly limited as long as it can generate an acid directly or indirectly by light irradiation.

Specific examples of the photoacid generator include triazine compounds, acetophenone derivative compounds, disulfonium compounds, diazomethane compounds, sulfonic acid derivative compounds, onium salts such as iodonium salts, sulfonium salts, phosphonium salts, and selenium salts, metallocene complexes, and iron aromatic complexes.

Examples of the onium salt used as the photoacid generator include iodonium salts such as diphenyliodonium chloride, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium methanesulfonate, diphenyliodonium toluenesulfonate, diphenyliodonium bromide, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluoroarsenate, bis(p-tert-butylphenyl)iodonium hexafluorophosphate, bis(p-tert-butylphenyl)iodonium methanesulfonate, bis(p-tert-butylphenyl)iodonium toluenesulfonate, bis(p-tert-butylphenyl)iodonium trifluoromethanesulfonate, bis(p-tert-butylphenyl)iodonium trifluoromethanesulfonate, and bis(p-tert-butylphenyl)iodonium hexafluoroarsenate. Examples of the present invention include bis(alkylphenyl)iodonium salts such as bis((4-t-butylphenyl)iodonium hexafluorophosphate, bis((1-ethoxycarbonyl-ethoxy)phenyl]-(2,4,6-trimethylphenyl)-iodonium hexafluorophosphate, and bis(alkoxyaryl)iodonium salts such as bis((4-methoxyphenyl)phenyl)iodonium hexafluorosulfate.

Examples of the sulfonium salt include triphenylsulfonium chloride, triphenylsulfonium bromide, tri(p-methoxyphenyl)sulfonium tetrafluoroborate, tri(p-methoxyphenyl)sulfonium hexafluorophosphonate, tri(p-ethoxyphenyl)sulfonium tetrafluoroborate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, and the like. Sulfonium salts include (4-phenylthiophenyl)diphenylsulfonium hexafluoroantimonylate, (4-phenylthiophenyl)diphenylsulfonium hexafluorophosphate, bis[4-(diphenyldihydrothio)phenyl]sulfide-bis-hexafluoroantimonylate, bis[4-(diphenyldihydrothio)phenyl]sulfide-bis-hexafluorophosphate, and (4-methoxyphenyl)diphenylsulfonium hexafluoroantimonylate.

Examples of the phosphonium salt include triphenylphosphonium chloride, triphenylphosphonium bromide, tri(p-methoxyphenyl)phosphonium tetrafluoroborate, tri(p-methoxyphenyl)phosphonium hexafluorophosphonate, tri(p-ethoxyphenyl)phosphonium tetrafluoroborate, 4-chlorobenzenediazonium hexafluorophosphate, and benzyltriphenylphosphonium hexafluoroantibonate.

Examples include selenium salts such as triphenylselenium hexafluorophosphate and metallocene complexes such as (η5 or η6-isopropylbenzene)(η5-cyclopentadienyl)iron(II) hexafluorophosphate.

Furthermore, as the photoacid generator, the following compounds can also be used.

As the photoacid generator, sulfonium salt compounds and iodonium salt compounds are preferred. As such negative ion species, there can be cited CF ₃ SO ₃ ^- , C ₄ F ₉ SO ₃ ^- , C ₈ F ₁₇ SO ₃ ^- , camphorsulfonic acid negative ions, toluenesulfonic acid negative ions, BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- and SbF ₆ ^- . In particular, negative ion species such as hexafluorophosphate ions and hexafluoroantimony acid ions showing strong acidity are preferred.

The film-forming composition of the present invention may contain conventional additives as necessary. Examples of such additives include pigments, colorants, thickeners, sensitizers, defoamers, coating improvers, lubricants, stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), plasticizers, dissolution promoters, fillers, antistatic agents, etc. These additives may be used alone or in combination of two or more.

Examples of the coating method for the film-forming composition of the present invention include flow coating, spin coating, spray coating, screen printing, casting, rod coating, curtain coating, roll coating, gravure coating, immersion coating, and slit coating.

In the present invention, the photo-coating composition (film-forming composition) may be applied on a substrate and cured by light irradiation. In addition, heating may be performed before or after light irradiation.

The thickness of the coating can be selected from the range of 0.01μm to 10mm according to the purpose of the cured product. For example, when using a photoresist, it can be set to 0.05 to 10μm (especially 0.1 to 5μm), when used for a printed wiring board, it can be set to 5μm to 5mm (especially 100μm to 1mm), and when used for an optical film, it can be set to 0.1 to 100μm (especially 0.3 to 50μm).

When a transparent coating is obtained, the visible light transmittance of the coating can be set to be above 80% or above 90%, and generally can be set to 90-96%.

When a photoacid generator is used, the light used to irradiate or expose the film-forming composition may be, for example, gamma rays, X-rays, ultraviolet rays, visible light, etc., and is generally visible light or ultraviolet rays, particularly ultraviolet rays. The wavelength of the light may be, for example, 150 to 800 nm, preferably 150 to 600 nm, more preferably 200 to 400 nm, and particularly preferably about 300 to 400 nm. The amount of irradiation light may vary depending on the thickness of the coating, but may be, for example, 2 to 20,000 mJ/cm ² , and preferably 5 to 5,000 mJ/cm ² . As a light source, it is possible to select the type of light to be exposed. For example, when ultraviolet light is used, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a deuterium lamp, a halogen lamp, a laser light (helium-cadmium laser, excimer laser, etc.) etc. can be used. By such light irradiation, the curing reaction of the aforementioned composition can be carried out.

The coating of the film-forming composition containing a thermal acid generator or the coating of the film-forming composition containing a photoacid generator can be heated as necessary before or after light irradiation, for example, at 60 to 250° C., preferably at 100 to 200° C. The heating time can be selected from the range of 3 seconds or more (for example, 3 seconds to 5 hours), for example, 5 seconds to 2 hours, preferably 20 seconds to 30 minutes, and generally selected from the range of 1 minute to 3 hours (for example, 5 minutes to 2.5 hours).

When further forming a pattern or image (for example, when manufacturing a printed wiring board), the coating formed on the substrate can also be pattern-exposed. The pattern exposure can also be performed by scanning with laser light, or by irradiating light through a photomask. When the non-irradiated area (unexposed part) generated by such pattern exposure is developed (or dissolved) with a developer, a pattern or image can be formed.

As the developer, an alkaline aqueous solution or an organic solvent can be used. As the alkaline aqueous solution, there can be cited aqueous solutions of alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, choline, and aqueous solutions of amines such as ethanolamine, propylamine, and ethylenediamine.

The aforementioned alkaline developer is generally an aqueous solution with a concentration of 10 mass % or less, preferably an aqueous solution with a concentration of 0.1 to 3.0 mass %. The aforementioned developer can be further added with alcohol or surfactant, and the amount of these additions is preferably 0.05 to 10 mass parts for 100 mass parts of the developer. Among them, a 0.1 to 2.38 mass % aqueous solution of tetramethylammonium hydroxide can be used.

As the organic solvent of the developer, general organic solvents can be used, for example, acetone, acetonitrile, toluene, dimethylformamide, methanol, ethanol, isopropyl alcohol, 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 one or a mixture of two or more of these can be used. In particular, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl lactate, etc. are preferably used.

In the present invention, when the purpose is to improve the adhesion between the cured film after development and the substrate, an adhesion promoter may be added. Examples of such adhesion promoters include chlorosilanes such as trimethylchlorosilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane, and chloromethyldimethylchlorosilane, alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylvinylethoxysilane, diphenyldimethoxysilane, and phenyltriethoxysilane, hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, and trimethylsilylimidazole, and silazanes such as vinyltrichlorosilane, Silanes such as 3-chloropropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-(N-piperidyl)propyltrimethoxysilane, benzotriazole, benzimidazole, indazole, imidazole, 2-butylbenzimidazole, 2-butylbenzothiazole, 2-butylbenzooxazole, urea, thiouracil, butylimidazole, butylpyrimidine, or urea or thiourea compounds such as 1,1-dimethylurea and 1,3-dimethylurea. One or more of the above adhesion promoters may be used in combination. The amount of these adhesion promoters added is generally less than 18% by mass in the solid component, preferably 0.0008 to 9% by mass, and more preferably 0.04 to 9% by mass. In this specification, the so-called solid component refers to the component excluding the solvent component from the composition.

The composition of the present invention may also contain a sensitizer. Examples of the sensitizer include anthracene, phenothiazine, perylene, thioxanthine, benzophenonethioxanthine, and the like. Examples of sensitizing pigments include thiopyridinium salt pigments, merocyanine pigments, quinoline pigments, styrenequinoline pigments, ketocoumarin pigments, thioxanthine pigments, xanthone pigments, oxocyanine pigments, cyanine pigments, rhodamine pigments, and ammonium pyridinium salt pigments. Anthracene-based sensitizers are particularly preferred. By using them together with a cationic curing catalyst (radioactive cationic polymerization initiator), the sensitivity can be greatly improved. At the same time, they also have the function of initiating free radical polymerization. In the hybrid type of the cationic curing system and free radical curing system of the present invention, the types of catalysts can be simplified. As specific anthracene compounds, dibutoxyanthracene, dipropoxyanthraquinone, etc. are effective. The amount of the sensitizer added is 0.01 to 20% by mass in the solid component, preferably 0.01 to 10% by mass.

The composition of the present invention can be photocured or thermally cured using a photo radical generator, a thermal radical generator, a photoacid generator or a thermal acid generator. When a photoacid generator or a thermal acid generator is used, for example, a curing agent (such as amine or acid anhydride) commonly used for epoxy resins is not used, or even if used, the content of such is extremely small, so the storage stability of the composition becomes good.

It was found that the above composition has photocationic ion polymerization. The composition of the present invention has a higher curing speed than the liquid epoxy compound of the past (such as the aliphatic epoxy compound having an epoxide hexyl ring). When the curing speed is to be accelerated, the amount of acid generator added can be reduced, or a weak acid generator can be used. Since the acid active species remaining after UV irradiation will cause metal corrosion, it is important to reduce the amount of acid generator used in preventing metal corrosion. The composition of the present invention can cure thick films due to its fast curing speed.

Curing by UV irradiation can be applied to materials (machines) that are weak to heat. The thermosetting materials and light-curing materials formed by the coating composition of the present invention have the characteristics of rapid hardening, transparency, and small shrinkage after hardening, so they can be used for covering or bonding electronic parts, optical parts (anti-reflection film), and precision mechanism parts. For example, it can be used for bonding mobile phone or camera lenses, light-emitting diodes (LEDs), semiconductor lasers (LDs) and other optical components, liquid crystal panels, biochips, camera lenses or prisms and other parts, magnetic parts of hard disks of personal computers, pickups of CD and DVD players (the part that can read light information reflected from the disk), cones and coils of amplifiers, magnets of motors, circuit boards, electronic parts, and internal parts of automobile engines (engines).

The composition of the present invention can be used for hard coating materials to protect the surface of automobile bodies, lamps or electrical products, building materials, plastics, etc. For example, it can be applied to automobile and motorcycle bodies, lenses or mirrors of headlights, plastic lenses of glasses, mobile phones, game consoles, optical films, ID cards, etc.

The composition of the present invention can be used as ink material for printing on metals such as aluminum, plastics, etc., and is suitable for cards such as credit cards, membership cards, switches of electrical products or OA machines, printing ink for keyboards, and ink for inkjet printers such as CDs and DVDs.

The composition of the present invention can be used in the technology of manufacturing complex three-dimensional objects by combining with three-dimensional CAD to harden resin, or optical shaping such as model making of industrial products, and can also be applied to coating, bonding, optical waveguide, thick film resist, etc. of optical fibers.

Furthermore, the coating forming composition of the present invention can be used as an insulating resin for electronic materials such as anti-reflection films, semiconductor sealing materials, adhesives for electronic materials, printed wiring board materials, interlayer insulating film materials, and sealing materials for power modules, or as an insulating resin for high-voltage machines such as generator coils, transformer coils, and gas-insulated switch devices.

The organic solvent sol of the hollow silica particles of the present invention can be produced by a method comprising the following steps (A) to (C). (A) step: preparing an aqueous sol of hollow silica particles; (B) step: adding at least one amine selected from the group consisting of a first amine, a second amine and a third amine having a water solubility of 80 g/L or more and a carbon number of 1 to 10 to the aqueous sol of hollow silica particles in step (A) at a ratio of 0.001 to 10 mass % relative to _SiO2 of the hollow silica particles; (C) step: replacing the aqueous medium of the aqueous sol of hollow silica particles obtained in step (B) with an alcohol, ketone, ether or ester having a carbon number of 1 to 10.

The hollow silica particles used in step (A) have a shell of silica and a space inside the shell. The hollow silica is obtained by forming a shell with silica as the main component on the surface of the part corresponding to the core called the template in the water dispersion medium and removing the part corresponding to the core. There are methods using organic materials (such as hydrophilic organic resin particles such as polyethylene glycol, polystyrene, polyester, etc.) and inorganic materials (such as hydrophilic inorganic compound particles such as calcium carbonate and sodium aluminate, etc.) as the template.

In step (B), an amine is added to the hollow silica aqueous sol in step (A). The amine can be selected from at least one amine of the first to third class amines having a water solubility of 80 g/L or more or 100 g/L or more and a total carbon number of 1 to 10, and added at a ratio of 0.001 to 10 mass % relative to SiO ₂ of the hollow silica. The above-mentioned amines can be used as these amines.

Step (C) is a step of replacing the aqueous medium of the aqueous sol of hollow silica obtained in step (B) with an alcohol, ketone, ether or ester having 1 to 10 carbon atoms. The aqueous medium of the aqueous sol of hollow silica can be replaced with an organic solvent, or with a hydrophilic organic solvent, or further with a hydrophobic organic solvent. That is, step (C) is a step of replacing the aqueous medium of the aqueous sol with an alcohol having 1 to 10 carbon atoms, and then replacing the alcohol solvent with a ketone, ether or ester having 1 to 10 carbon atoms.

During or after the step (C), a step (D) of adding at least one silane compound selected from the group consisting of the silane compounds represented by formula (1), formula (2) and formula (3) and heating may be further performed.

In other words, the aqueous medium of the aqueous sol in step (C) is substituted with an alcohol having 1 to 10 carbon atoms by a solvent, and then at least one silane compound selected from the group consisting of the silane compounds represented by the above formula (1), formula (2) and formula (3) is added, and after the heating step (D), the alcohol solvent in step (C) is further substituted with a ketone, ether or ester having 1 to 10 carbon atoms by a solvent.

The heating temperature after adding the silane compound is 40°C or higher, preferably below the reflux temperature of the solvent used, and the heating time can be in the range of 0.1 to 10 hours.

In the present invention, the surface charge of the hollow silicon oxide particles can be arbitrarily adjusted by using the above-mentioned method for manufacturing the hollow silicon oxide organic solvent sol. [Example]

(Analytical method) [Determination of _SiO2 concentration] Place hollow silica sol in a crucible, heat and dry it on a hot plate at a temperature about 10°C higher than the boiling point of the dispersion medium. After removing the dispersion medium, calcine the obtained silica gel at 1000°C, weigh the calcined residue and calculate. [Determination of water content] Determine it by Karl Fischer titration. [Determination of viscosity] Use a BL type viscometer to measure at 25°C. [pH measurement] Use a pH meter (manufactured by Toa Dkk (Co., Ltd.)) to measure at 25°C. For methanol sol and propylene glycol monomethyl ether sol, the solution method was used to measure the content of pure water and sol in a mass ratio of 1:1. For methyl ethyl ketone sol, the solution method was used to measure the content of pure water, methanol and methyl ethyl ketone sol in a mass ratio of 1:1:1. [Measurement of total nitrogen content] The content of total nitrogen was measured using a micro total nitrogen analysis (TN) device (TN-2100V manufactured by Mitsubishi Chemical Analytech) under the following conditions. ･Thermolysis furnace inlet temperature: 800℃, outlet temperature: 900℃ Ar (argon) flow rate: 100mL/min, O ₂ (oxygen) flow rate: 500mL/min ･Detector (chemiluminescence detector) Low concentration mode O ₃ (ozone) flow rate: 600mL/min As the sample for measurement, hollow silica sol is diluted to a predetermined volume with methyl ethyl ketone in an eggplant-shaped flask and the total nitrogen content is prepared to be 1-10ppm. 20μL of the sample for measurement is injected into the device, and the area value is measured. The total nitrogen content of the sample for measurement is calculated from the standard curve prepared by the area values of the pre-prepared standard samples with total nitrogen content of 0ppm, 1ppm, and 10ppm. [Determination of particle size by dynamic light scattering] Determination by a particle size measuring device (Zetersizer Nano manufactured by Spectris Corporation) using a dynamic light scattering method. [Determination of surface charge] Add and dilute silica to a concentration of about 0.5% by mass in 10 mL of methanol as a sample for measurement. Using a particle charge meter (trade name PCD-06 manufactured by Voith Turbo Co., Ltd.), use N/1000 DADMAC solution (manufactured by Voith Turbo Co., Ltd.) as a standard cation titrant, and measure the titration value until the streaming potential of the sample for measurement becomes zero. Divide the obtained titration value by the mass of silica contained in the sample for measurement to obtain the surface charge (μeq/g) per 1g of _SiO2 converted to hollow silica particles. [Measurement of specific surface area by BET (nitrogen adsorption method)] The cationic components in the hollow silica sol were removed by H-type cation exchange resin, and the dried product after heat treatment to remove the solvent was pulverized in an emulsion jar and further treated at 250°C for 2 hours. The specific surface area of the dried pulverized product was measured by gas adsorption specific surface area measuring device (Monosorb TM MS-22 manufactured by Quantachrome INSTRUMENTS Co., Ltd.) using a mixed gas of 30% _N2 (nitrogen) and 70% He (helium) as the carrier gas, and the BET single-point method was used to measure the specific surface area. [Measurement of average primary particle size by TEM (transmission electron microscope)] The particles in the hollow silica sol were photographed by a transmission electron microscope (JEM-F200 manufactured by JEOL Ltd.), and about 300 randomly selected particles were binarized by an automatic image processing and analysis device (LUZEX' AP manufactured by Nireco Ltd.), and the projected area was converted into a circle and the diameter was measured as the average primary particle size (HEYWOOD diameter). [Calculation of specific surface area ratio] The value obtained by dividing the BET specific surface area value by the specific surface area value calculated by assuming that the average primary particle size through TEM is a true spherical particle with a true density of 2.2 g/ ^cm3 is defined as the specific surface area ratio.

(Example 1) (Preparation of hollow silica methanol sol (1)) 100.22 g of commercially available hollow silica aqueous sol (HKT-D20-225-1 manufactured by Ningbo Dilato Co., Ltd., _SiO2 concentration of 20.7 mass %, pH 9.0, particle size by dynamic light scattering method of 88 nm, specific surface area by BET method of 107 ^m2 /g, average primary particle size by TEM of 82 nm, specific surface area ratio of 3.2) was placed in a 500 mL eggplant flask, and 0.04 g of diisopropylamine was added while stirring with a magnetic stirrer, and the mixture was mixed for 2 hours. Thereafter, 38.09 g of methanol was added while stirring, and the mixture was mixed for 2 hours. Using a rotary evaporator, about 3000 mL of methanol was supplied under reduced pressure (pressure 150 Torr, bath temperature 80°C) while water was distilled off to obtain a hollow silica methanol sol (1). The obtained hollow silica methanol sol had a SiO ₂ concentration of 15.5 mass %, a water content of 1.7%, a viscosity of 1.8 mPa·sec, a pH of 8.2, a particle size of 99 nm by dynamic light scattering, a total nitrogen content of 438 ppm, and a surface charge of 26 μeq/g per 1 g of SiO ₂ converted to hollow silica particles.

(Preparation of film with addition of hollow silica methanol sol (1)) 18.33 g of dipentaerythritol hexaacrylate (KAYARAD DPHA, manufactured by Nippon Kayaku Co., Ltd.) as a UV curable resin was placed in a brown bottle, to which a UV curing agent (Omnirad 819) was added to 5 phr, and a leveling agent (L-7001, manufactured by DOWSIL Corporation) was added to 0.1 phr, and a UV curable resin liquid (concentration: 35 mass %) was prepared by dissolving the mixture in 34.99 g of propylene glycol monomethyl ether. 1.61 g of the hollow silica methanol sol (1) (SiO ₂ concentration 15.5 mass %) obtained in Example 1 was placed in a brown bottle, propylene glycol monomethyl ether and methanol were added to a total amount of 5.00 g, and the final solvent composition weight ratio was propylene glycol monomethyl ether/methanol = 6/4, and 0.71 g of the UV curable resin solution prepared above was added, and after mixing at room temperature for 1 hour, a hollow silica methanol sol (1)/UV curable resin mixed coating was prepared. The solid content concentration was 10 mass %, and the amount of hollow silica (SiO ₂ ) was 100 phr. About 2 mL of the obtained hollow silica methanol sol (1)/UV curing resin mixed paint was dripped onto a glass substrate, and a rotary coater (Opticoat MS-B100 manufactured by Mikasa Co., Ltd.) was used to evenly spread the coating on the glass substrate at 200 rpm × 5 sec and then increased to 1000 rpm after 3 sec. The coating was then uniformly spread on the glass substrate at 1000 rpm × 30 sec. Thereafter, the coating was baked at 100°C × 3 min on a hot plate, and UV light was irradiated at an integrated light intensity of 2000 mJ/cm ² to prepare a coating film containing the hollow silica methanol sol (1). The total light transmittance of the obtained composite film was measured by a spectroscopic haze meter (SH7000 manufactured by Nippon Denshoku Industries Co., Ltd.) and the result was 91.6%. The total light transmittance of the glass substrate is 91.0%, which is higher than the total light transmittance of 90.7% of the film prepared under the same conditions with only UV curing resin, indicating that it is a highly transparent composite film.

(Example 2) (Preparation of hollow silica methanol sol (2)) 100.01 g of commercially available hollow silica aqueous sol (HKT-D20-225-1 manufactured by Ningbo Dilato Co., Ltd., _SiO2 concentration 20.7%, pH 9.0, particle size by dynamic light scattering method: 88 nm, specific surface area by BET method: 107 ^m2 /g, average primary particle size by TEM: 82 nm, specific surface area ratio: 3.2) was placed in a 500 mL eggplant flask, and hollow silica methanol sol (2) was obtained by the same operation as in Example 1, except that the amount of diisopropylamine added was changed to 0.10 g and the amount of methanol was changed to 37.98 g. The obtained hollow silica methanol sol (2) had a _SiO2 concentration of 15.1 mass %, a water content of 0.9%, a viscosity of 1.6 mPa･sec, a pH of 8.7, a particle size of 108 nm as determined by dynamic light scattering, a total nitrogen content of 409 ppm, and a surface charge of 25 μeq/g per 1 g of _SiO2 in terms of hollow silica particles.

(Preparation of hollow silica propylene glycol monomethyl ether sol (1)) 42.66 g of the hollow silica methanol sol (2) ( _SiO2 concentration 18.2 mass%) before concentration adjustment obtained in Example 2 was placed in a 200 mL eggplant flask, and 7.36 g of propylene glycol monomethyl ether was added. Thereafter, a rotary evaporator was used, and the pressure was gradually reduced from 150 Torr to 80 Torr at a bath temperature of 60°C, while 60 g of propylene glycol monomethyl ether was supplied and methanol was distilled off to obtain a hollow silica propylene glycol monomethyl ether sol. The obtained hollow silicon oxide glycol monomethyl ether sol (1) had a _SiO2 concentration of 13.4 mass %, a water content of 0.2%, a viscosity of 3.5 mPa·sec, a pH of 8.1, a particle size of 103 nm as determined by dynamic light scattering, and a total nitrogen content of 330 ppm.

(Preparation of film with hollow silica methanol sol (2) added) A film formed by adding hollow silica methanol sol (2)/UV curing resin mixed paint and hollow silica methanol sol (2) paint was prepared by the same operation as in Example 1, except that 1.66 g of hollow silica methanol sol (2) ( _SiO2 concentration 15.1 mass%) was used. The total light transmittance of the obtained composite film was 92.8%, and it was a composite film with high transparency.

(Preparation of a film formed by adding a coating to which hollow silicon oxide propylene glycol monomethyl ether sol (1) is added) A film formed by adding a coating to which hollow silicon oxide propylene glycol monomethyl ether sol (1)/ _UV curable resin mixed coating and hollow silicon oxide propylene glycol monomethyl ether sol (1) is added was prepared by the same operation as in Example 1, except that 1.86 g of hollow silicon oxide propylene glycol monomethyl ether sol (1) (SiO2 concentration 13.4 mass%) was used. The total light transmittance of the obtained composite film was 92.2%, and it was a composite film with high transparency.

(Example 3) (Preparation of hollow silica methanol sol (3)) 100.15 g of commercially available hollow silica aqueous sol (HKT-D20-225-1 manufactured by Ningbo Dilato Co., Ltd., _SiO2 concentration 20.7%, pH 9.0, particle size of 88 nm by dynamic light scattering, specific surface area of 107 ^m2 /g by BET method, average primary particle size of 82 nm by TEM, specific surface area ratio of 3.2) was placed in a 500 mL eggplant flask, and hollow silica methanol sol (3) was obtained by the same operation as in Example 1, except that the amount of diisopropylamine added was changed to 0.21 g and the amount of methanol was changed to 38.02 g. The obtained hollow silica methanol sol (3) had a _SiO2 concentration of 15.5 mass %, a water content of 1.6%, a viscosity of 1.8 mPa·sec, a pH of 8.6, a particle size of 101 nm as determined by dynamic light scattering, a total nitrogen content of 410 ppm, and a surface charge of 25 μeq/g per 1 g of _SiO2 in terms of the hollow silica particles.

(Preparation of hollow silica methyl ethyl ketone sol (1)) 50.02 g of the hollow silica methanol sol (3) ( _SiO2 concentration 15.5 mass %) obtained in Example 3 was placed in a 200 mL eggplant flask, and 0.35 g of 3-methacryloyloxypropyltrimethoxysilane was added as a surface treatment agent. The surface was treated by heating for 5 hours while refluxed under stirring. Thereafter, a rotary evaporator was used to gradually reduce the pressure from 500 Torr to 400 Torr at a bath temperature of 75°C, and 150 mL of methyl ethyl ketone was supplied while methanol was distilled off to obtain hollow silica methyl ethyl ketone sol (1). The obtained hollow silica methyl ethyl ketone sol (1) had a _SiO2 concentration of 15.5 mass %, a water content of 0.1%, a viscosity of 3.1 mPa·sec, a pH of 7.8, a particle size of 106 nm as determined by dynamic light scattering, and a total nitrogen content of 360 ppm.

(Preparation of film with hollow silica methanol sol (3) added) A film formed by adding hollow silica methanol sol (3)/UV curing resin mixed paint and hollow silica methanol sol (3) paint was prepared by the same operation as in Example 1, except that 1.61 g of hollow silica methanol sol (3) ( _SiO2 concentration 15.5 mass%) was used. The total light transmittance of the obtained composite film was 92.1%, and it was a composite film with high transparency. (Preparation of film with addition of hollow silica methyl ethyl ketone sol (1)) 1.61 g of hollow silica methyl ethyl ketone sol (1) (SiO ₂ concentration 15.5 mass%) obtained in Example 3 was placed in a brown bottle, propylene glycol monomethyl ether and methyl ethyl ketone were added to make the total amount 5.00 g, and the weight ratio of the final solvent composition was propylene glycol monomethyl ether/methyl ethyl ketone = 6/4. After adding 0.71 g of the UV curable resin liquid prepared in Example 1, the mixture was mixed at room temperature for 1 hour to prepare hollow silica methyl ethyl ketone sol (1)/UV curable resin mixed coating. The solid content concentration was 10 mass%, and the amount of hollow silica (SiO ₂ ) was 100 phr. About 2 mL of the obtained hollow silica methyl ethyl ketone sol (1)/UV curing resin mixed paint was dripped onto a glass substrate, and a rotary coater (Opticoat MS-B100 manufactured by Mikasa Co., Ltd.) was used to uniformly spread the coating on the glass substrate at 200 rpm × 5 sec, then increased to 1000 rpm within 3 seconds, and continued at 1000 rpm × 30 sec. Thereafter, the coating was baked at 100°C × 3 min on a hot plate, and irradiated with UV light at an integrated light intensity of 2000 mJ/cm ² to prepare a coating film formed by adding hollow silica methyl ethyl ketone sol (1). The total light transmittance of the obtained composite film was measured by a spectroscopic haze meter (SH7000 manufactured by Nippon Denshoku Industries Co., Ltd.) and the result was 92.8%. The total light transmittance of the glass substrate is 91.0%, which is higher than the total light transmittance of 90.7% of the film prepared under the same conditions with only UV curing resin. It is a highly transparent composite film.

(Example 4) (Preparation of hollow silica methanol sol (4)) 100.05 g of commercially available hollow silica aqueous sol (HKT-D20-225-1 manufactured by Ningbo Dilato Co., Ltd., _SiO2 concentration 20.7%, pH 9.0, particle size of 88 nm by dynamic light scattering, specific surface area of 107 ^m2 /g by BET method, average primary particle size of 82 nm by TEM, specific surface area ratio of 3.2) was placed in a 500 mL eggplant flask, and hollow silica methanol sol (4) was obtained by the same operation as in Example 1, except that the amount of diisopropylamine added was changed to 0.50 g and the amount of methanol was changed to 38.06 g. The obtained hollow silica methanol sol (4) had a _SiO2 concentration of 15.5 mass %, a water content of 1.2%, a viscosity of 1.7 mPa･sec, a pH of 8.9, a particle size of 99 nm as determined by dynamic light scattering, a total nitrogen content of 458 ppm, and a surface charge of 30 μeq/g per 1 g of _SiO2 in terms of hollow silica particles.

(Preparation of hollow silica methyl ethyl ketone sol (2)) 50.03 g of the hollow silica methanol sol (4) ( _SiO2 concentration 15.5%) obtained in Example 4 was placed in a 200 mL eggplant flask, and the same operation as Example 3 was performed except that the amount of 3-methacryloxypropyltrimethoxysilane added as a surface treatment agent was changed to 0.35 g, thereby obtaining a hollow silica methyl ethyl ketone sol (2). The obtained hollow silica methyl ethyl ketone sol (2) had a _SiO2 concentration of 15.6 mass%, a water content of 0.2%, a viscosity of 3.3 mPa·sec, a pH of 8.3, a particle size of 102 nm as determined by dynamic light scattering, and a total nitrogen content of 387 ppm.

(Preparation of film with hollow silica methanol sol (4) added) A film formed by adding hollow silica methanol sol (4)/UV curing resin mixed paint and hollow silica methanol sol (4) paint was prepared by the same operation as in Example 1, except that 1.61 g of hollow silica methanol sol (4) ( _SiO2 concentration 15.5 mass%) was used. The total light transmittance of the obtained composite film was 92.4%, and it was a composite film with high transparency. (Preparation of film with hollow silica methyl ethyl ketone sol (2) added) A film formed by adding hollow silica methyl ethyl ketone sol (2)/UV curing resin mixed paint and hollow silica methyl ethyl ketone sol (2) paint was prepared by the same operation as in Example 3, except that 1.61 g of hollow silica methyl ethyl ketone sol (2) ( _SiO2 concentration 15.6 mass%) was used in Example 4. The total light transmittance of the obtained composite film was 92.3%, and it was a composite film with high transparency.

(Example 5) (Preparation of hollow silica methanol sol (5)) 100.15 g of commercially available hollow silica aqueous sol (HKT-D20-225-1 manufactured by Ningbo Dilato Co., Ltd., _SiO2 concentration 20.7 mass %, pH 9.0, particle size by dynamic light scattering method: 88 nm, specific surface area by BET method: 107 ^m2 /g, average primary particle size by TEM: 82 nm, specific surface area ratio: 3.2) was placed in a 500 mL eggplant flask, and hollow silica methanol sol (5) was obtained by the same operation as in Example 1, except that the amount of diisopropylamine added was changed to 1.00 g and the amount of methanol was changed to 38.07 g. The obtained hollow silica methanol sol (5) had a _SiO2 concentration of 15.5 mass %, a water content of 0.8%, a viscosity of 1.6 mPa･sec, a pH of 8.5, a particle size of 98 nm as determined by dynamic light scattering, a total nitrogen content of 414 ppm, and a surface charge of 27 μeq/g per 1 g of _SiO2 in terms of hollow silica particles.

(Preparation of hollow silica methyl ethyl ketone sol (3)) 50.05 g of the hollow silica methanol sol (5) ( _SiO2 concentration 15.5 mass%) obtained in Example 5 was placed in a 200 mL eggplant flask, and the same operation as in Example 3 was performed except that the amount of 3-methacryloxypropyltrimethoxysilane added as a surface treatment agent was changed to 0.35 g, thereby obtaining a hollow silica methyl ethyl ketone sol (3). The obtained hollow silica methyl ethyl ketone sol (3) had a _SiO2 concentration of 15.5 mass%, a water content of 0.0%, a viscosity of 2.7 mPa·sec, a pH of 7.9, a particle size of 103 nm as determined by a dynamic light scattering method, and a total nitrogen content of 359 ppm.

(Preparation of film with hollow silica methanol sol (5) added) A film formed by adding hollow silica methanol sol (5)/UV curing resin mixed paint and hollow silica methanol sol (5) paint was prepared by the same operation as in Example 1, except that 1.61 g of hollow silica methanol sol (5) ( _SiO2 concentration 15.5 mass%) was used. The total light transmittance of the obtained composite film was 92.7%, and it was a composite film with high transparency.

(Preparation of film with hollow silica methyl ethyl ketone sol (3) added) A film formed by adding hollow silica methyl ethyl ketone sol (3)/UV curing resin mixed paint and hollow silica methyl ethyl ketone sol (3) paint was prepared by the same operation as in Example 3, except that 1.61 g of hollow silica methyl ethyl ketone sol (3) ( _SiO2 concentration 15.5 mass%) was used. The total light transmittance of the obtained composite film was 92.8%, and it was a composite film with high transparency.

(Example 6) (Preparation of hollow silica methanol sol (6)) 100.06 g of commercially available hollow silica aqueous sol (HKT-D20-225-1 manufactured by Ningbo Dilato Co., Ltd., _SiO2 concentration 20.7%, pH 9.0, particle size by dynamic light scattering method: 88 nm, specific surface area by BET method: 107 ^m2 /g, average primary particle size by TEM: 82 nm, specific surface area ratio: 3.2) was placed in a 500 mL eggplant flask, and while the sol was stirred with a magnetic stirrer, 1.41 g of 28% ammonia water was added and mixed for 2 hours. Then, 0.04 g of diisopropylamine was added while stirring, and the mixture was mixed for 2 hours. Then, 38.01 g of methanol was added while stirring, and the mixture was mixed for 2 hours. Using a rotary evaporator, about 3000 mL of methanol was supplied under reduced pressure (pressure 150 Torr, bath temperature 80°C), and water was distilled off to obtain a hollow silica methanol sol (6). The obtained hollow silica methanol sol (6) had a SiO ₂ concentration of 15.7 mass %, a water content of 1.1%, a viscosity of 1.7 mPa·sec, a pH of 9.0, a particle size of 99 nm by dynamic light scattering, a total nitrogen content of 553 ppm, and a surface charge of 30 μeq/g per 1 g of SiO ₂ converted to hollow silica particles.

(Preparation of hollow silica methyl ethyl ketone sol (4)) 50.00 g of the hollow silica methanol sol (6) ( _SiO2 concentration 15.7 mass%) obtained in Example 6 was placed in a 200 mL eggplant flask, and the same operation as Example 3 was performed except that the amount of 3-methacryloxypropyltrimethoxysilane added as a surface treatment agent was changed to 0.35 g, thereby obtaining a hollow silica methyl ethyl ketone sol (4). The obtained hollow silica methyl ethyl ketone sol (4) had a _SiO2 concentration of 15.6 mass%, a water content of 0.3%, a viscosity of 4.2 mPa·sec, a pH of 8.5, a particle size of 103 nm as determined by dynamic light scattering, and a total nitrogen content of 436 ppm.

(Preparation of film with hollow silica methanol sol (6) added) A film formed by adding hollow silica methanol sol (6)/UV curing resin mixed paint and hollow silica methanol sol (6) paint was prepared by the same operation as in Example 1, except that 1.59 g of hollow silica methanol sol (6) ( _SiO2 concentration 15.7 mass%) was used. The total light transmittance of the obtained composite film was 92.7%, and it was a composite film with high transparency. (Preparation of film with hollow silica methyl ethyl ketone sol (4) added) A film formed by adding hollow silica methyl ethyl ketone sol (4)/UV curing resin mixed paint and hollow silica methyl ethyl ketone sol (4) paint was prepared by the same operation as in Example 3, except that 1.61 g of hollow silica methyl ethyl ketone sol (4) ( _SiO2 concentration 15.6 mass%) was used in Example 6. The total light transmittance of the obtained composite film was 92.1%, and it was a composite film with high transparency.

(Example 7) (Preparation of hollow silica methanol sol (7)) A commercially available hollow silica aqueous sol (HKT-D20-225-1 manufactured by Ningbo Dilato Co., Ltd., SiO ₂ concentration 20.7 mass %, pH 9.0, particle size of 88 nm by dynamic light scattering method, specific surface area of 107 m ² by BET method) was prepared. /g, the average primary particle size by TEM is 82nm, and the specific surface area ratio is 3.2) 105.47g was placed in a 500mL eggplant flask, and the amount of 28% ammonia water added was changed to 3.77g, the amount of diisopropylamine was changed to 0.05g, and the amount of methanol was changed to 40.07g. The hollow silica methanol sol (7) obtained was _SiO2 concentration of 15.5% by mass, water content of 1.1%, viscosity of 1.4mPa·sec, pH 9.3, particle size by dynamic light scattering method was 101nm, total nitrogen content was 1346ppm, and surface charge of _SiO2 per 1g of hollow silica particles was 36μeq/g.

(Preparation of hollow silica methyl ethyl ketone sol (5)) 50.02 g of the hollow silica methanol sol (7) ( _SiO2 concentration 15.5 mass%) obtained in Example 7 was placed in a 200 mL eggplant flask, and the same operation as Example 3 was performed except that the amount of 3-methacryloxypropyltrimethoxysilane added as a surface treatment agent was changed to 0.35 g, thereby obtaining a hollow silica methyl ethyl ketone sol (5). The obtained hollow silica methyl ethyl ketone sol (5) had a _SiO2 concentration of 15.5 mass%, a water content of 0.1%, a viscosity of 2.8 mPa·sec, a pH of 8.4, a particle size of 102 nm as determined by a dynamic light scattering method, and a total nitrogen content of 1043 ppm.

(Preparation of film with hollow silica methanol sol (7) added) A film formed by adding hollow silica methanol sol (7)/UV curing resin mixed paint and hollow silica methanol sol (7) paint was prepared by the same operation as in Example 1, except that 1.61 g of hollow silica methanol sol (7) ( _SiO2 concentration 15.5 mass%) was used. The total light transmittance of the obtained composite film was 92.7%, and it was a composite film with high transparency.

(Preparation of film with hollow silica methyl ethyl ketone sol (5) added) A film formed by adding hollow silica methyl ethyl ketone sol (5)/UV curing resin mixed paint and hollow silica methyl ethyl ketone sol (5) paint was prepared by the same operation as in Example 3, except that 1.61 g of hollow silica methyl ethyl ketone sol (5) ( _SiO2 concentration 15.5 mass%) was used in Example 7. The total light transmittance of the obtained composite film was 92.4%, and it was a composite film with high transparency.

(Example 8) (Preparation of hollow silica methanol sol (8)) 551.10 g of commercially available hollow silica aqueous sol (HKT-A20-40D manufactured by Ningbo Dilato Co., Ltd., _SiO2 concentration 20.0%, pH 9.3, particle size by dynamic light scattering method of 55 nm, specific surface area by BET method of 116 ^m2 /g, average primary particle size by TEM of 43 nm, specific surface area ratio of 1.8) was placed in a 2000 mL eggplant flask, and 0.55 g of diethanolamine was added while stirring with a magnetic stirrer, and the mixture was mixed for 2 h. Subsequently, 139.76 g of methanol was added while further stirring, and the mixture was mixed for 2 h. Using a rotary evaporator, about 12000 mL of methanol was supplied under reduced pressure (pressure 580 Torr, bath temperature 120°C), and water was distilled off to obtain a hollow silica methanol sol (8). The obtained hollow silica methanol sol (8) had a SiO ₂ concentration of 23.5%, a water content of 0.6%, a viscosity of 2.8 mPa·sec, a pH of 9.0, a particle size of 63 nm by dynamic light scattering, a total nitrogen content of 641 ppm, and a surface charge of 34 μeq/g per 1 g of SiO ₂ converted to hollow silica particles.

(Preparation of hollow silica methyl ethyl ketone sol (6)) 25.00 g of the raw material methanol sol of the hollow silica methanol sol (8) obtained in Example 8, in which the _SiO2 concentration was adjusted to 20.5% by mass, was placed in a 300 mL eggplant flask, 8.20 g of methanol and 0.26 g of pure water were added, and stirred with a magnetic stirrer. 0.25 g of γ-methacryloyloxypropyltrimethoxysilane was added as a surface treatment agent, and the surface was treated by heating for 5 h while refluxing. Thereafter, a rotary evaporator was used to gradually reduce the pressure from 500 Torr to 400 Torr at a bath temperature of 75°C, while supplying about 80 mL of methyl ethyl ketone and distilling off methanol to obtain a hollow silica methyl ethyl ketone sol (6). The obtained hollow silica methyl ethyl ketone sol (6) had a _SiO2 concentration of 22.4%, a water content of 0.4%, a pH of 9.3, and a particle size of 66 nm as determined by dynamic light scattering.

(Comparative Example 1) Preparation of hollow silica methanol sol containing no amine 100.04 g of commercially available hollow silica aqueous sol (HKT-D20-225-1 manufactured by Ningbo Dilato Co., Ltd., SiO ₂ concentration 20.7%, pH 9.0, particle size by dynamic light scattering method 88 nm) was placed in a 500 mL eggplant flask, and 38.02 g of methanol was further added. Using a rotary evaporator, about 3000 mL of methanol was supplied under reduced pressure (pressure 150 Torr, bath temperature 80°C) while distilling off water to try to prepare a hollow silica methanol sol, but the sol became thicker and gelled during the substitution with methanol, and the desired hollow silica methanol sol could not be obtained.

In the above Tables 1 and 2, (hollow silica methanol sol) represents a sol in which hollow silica particles are dispersed in methanol. MeOH in the column of (dispersant) represents methanol. (pH) represents the pH when the hollow silica methanol sol is mixed with pure water of the same mass at a ratio of 1:1. (Amine amount) represents the addition ratio (mass %) of SiO ₂ to the hollow silica particles, and is contained in the hollow silica methanol sol in accordance with the addition ratio. (DLS) represents the average particle size (nm) of the hollow silica particles obtained by dynamic light scattering. (Total nitrogen amount) represents the total nitrogen amount (ppm) in the hollow silica particle sol of the alkaline component composed of amine or amine and ammonia. (Surface charge amount) represents the surface charge amount (μeq/g) converted to SiO ₂ per 1g of the hollow silica particles. Furthermore, the term "gelled" means that the hollow silica sol is gelled and physical property values cannot be measured.

In the above Table 3, (Hollow silica organic solvent sol) indicates a sol in which hollow silica particles are dispersed in an organic solvent. PGME in the column of (Dispersant) indicates propylene glycol monomethyl ether, and MEK indicates methyl ethyl ketone. (pH) indicates the pH value measured by a solution in which pure water and the sol are mixed at a mass ratio of 1:1 for propylene glycol monomethyl ether sol, and the pH value measured by a solution in which pure water, methanol and methyl ethyl ketone sol are mixed at a mass ratio of 1:1:1 for methyl ethyl ketone sol. "None" in the column of (Surface treatment) indicates that the surface treatment of silica particles with a silane coupling agent cannot be performed, and MPS indicates that the surface treatment of silica particles is performed with 3-methacryloyloxypropyltrimethoxysilane. (DLS) represents the average particle size (nm) of hollow silica particles obtained by dynamic light scattering. (Total nitrogen content) represents the total nitrogen content (ppm) of the alkali component composed of amine or amine and ammonia in the hollow silica particle sol.

In Tables 4 and 5, (Hollow silica methanol sol-compounded film) indicates a film obtained by coating a substrate with a resin composition obtained by adding a sol in which hollow silica particles are dispersed in methanol to a UV curable resin. The column (UV curable resin) indicates the multifunctional acrylate used, and DPHA indicates KAYARAD DPHA (multifunctional acrylate: dipentaerythritol hexaacrylate), a trade name manufactured by Nippon Kayaku Co., Ltd. (compounded amount) indicates the compounding amount (phr) of the hollow silica particles in the UV curable resin. (Total light transmittance) indicates the total light transmittance (%) of the obtained coating.

In Tables 6 and 7, (Hollow silica organic solvent sol-gel film) indicates a film formed on a substrate coated with a resin composition in which a sol in which hollow silica particles are dispersed in an organic solvent is added to a UV curable resin and then cured by light. The column (UV curable resin) indicates the multifunctional acrylate used, and DPHA indicates KAYARAD DPHA (multifunctional acrylate: dipentaerythritol hexaacrylate), a trade name manufactured by Nippon Kayaku Co., Ltd. (compounding amount) indicates the compounding amount (phr) of the hollow silica particles in the UV curable resin. (Total light transmittance) indicates the total light transmittance (%) of the obtained coating.

From the above evaluation results, it can be seen that when no water-soluble amine is added to the hollow silica aqueous sol and the aqueous medium is replaced by methanol for solvent substitution, the desired hollow silica methanol sol cannot be obtained due to viscosity increase and gelation during the solvent substitution. In contrast, when a certain amount of diisopropylamine as a water-soluble amine is added to the hollow silica aqueous sol and the solvent substitution is performed, the viscosity increase and gelation are avoided, and the desired hollow silica methanol sol is obtained, and at the same time, it is confirmed that the sol of the hollow silica particles can be controlled to have a surface charge amount above a certain value. Furthermore, the obtained hollow silica methanol sol was added to the resin to prepare the compound film, and the hollow silica particles were dispersed evenly in the resin, and high transparency (total light transmittance) was also confirmed. And when the obtained hollow silica methanol sol was used as a raw material, it was confirmed that the solvent such as propylene glycol monomethyl ether or methyl ethyl ketone was replaced by other organic solvents. [Industrial Applicability]

The present invention provides hollow silica particles having a specific surface charge and high dispersibility in a resin, an organic solvent sol containing amines in the sol and hollow silica particles having spaces inside the shell, a production method thereof, and a coating forming composition.

Claims (15)

An organic solvent sol of hollow silicon oxide particles, wherein the sol contains amine and has space inside the outer shell. The sol of claim 1, wherein the amine is at least one amine selected from the group consisting of first-class amines, second-class amines and third-class amines having 1 to 10 carbon atoms. The sol of claim 1 or 2, wherein the amine is a water-soluble amine having a water solubility of 80 g/L or more. The sol of any one of claims 1 to 3, wherein the content of the amine is 0.001 to 10 mass % with respect to SiO ₂ of the hollow silicon oxide particles. The sol of any one of claims 1 to 4, wherein the average particle size of the hollow silica particles measured by dynamic light scattering is 20 to 150 nm. The sol of any one of claims 1 to 5, wherein the surface charge of _SiO2 per 1g of the hollow silicon oxide particles is 5 to 250 μeq/g. The sol of any one of claims 1 to 6, wherein the organic solvent is an alcohol, ketone, ether or ester having 1 to 10 carbon atoms. The sol of any one of claims 1 to 7, wherein the hollow silicon oxide particles are further coated with at least one silane compound selected from the group consisting of silane compounds represented by formula (1), formula (2) and formula (3), (In formula (1), ^R1 each represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, an alkyl group, an amine group, an ureido group, or a cyano group, and a group bonded to a silicon atom via a Si-C bond; ^R2 each represents an alkoxy group, an acyloxy group, or a halogenated group; a is an integer of 1 to 3; In formula (2) and formula (3), ^R3 and ^R5 each represent an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms, and a group bonded to a silicon atom via a Si-C bond; ^R4 and ^R6 each represent an alkoxy group, an acyloxy group, or a halogenated group; Y represents an alkylene group, an NH group, or an oxygen atom; b is an integer of 1 to 3; c is an integer of 0 or 1; and d is an integer of 1 to 3). A film-forming composition comprising the sol as described in any one of claims 1 to 8 and an organic resin. A film obtained from a coating forming composition, which is obtained from the coating forming composition as claimed in claim 9, wherein the visible light transmittance is 80% or more. A method for producing a sol as claimed in any one of claims 1 to 8, comprising the following steps (A) to (C), (A) step: preparing a hollow silica aqueous sol, (B) step: adding at least one amine selected from the group consisting of a first amine, a second amine and a third amine having a water solubility of 80 g/L or more and a carbon number of 1 to 10 to the hollow silica aqueous sol in a ratio of 0.001 to 10 mass % relative to _SiO2 of the hollow silica particles, Step (C): replacing the aqueous medium of the aqueous sol of the hollow silica particles obtained in step (B) with an alcohol, ketone, ether or ester having 1 to 10 carbon atoms. The method for preparing the sol of claim 11, wherein after the above step (C) is completed, the method further comprises a step (D) of adding at least one silane compound selected from the group consisting of the above formula (1), formula (2) and formula (3), and heating. The method for preparing a sol as claimed in claim 11 or 12, wherein the step (C) is a step of replacing the aqueous medium with an alcohol having 1 to 10 carbon atoms as a solvent and then further replacing the aqueous medium with a ketone, ether or ester having 1 to 10 carbon atoms as a solvent. A method for preparing a sol as claimed in claim 12, wherein step (C) is a step of replacing the aqueous medium with an alcohol having 1 to 10 carbon atoms as a solvent, and step (D) is a step of adding at least one silane compound selected from the group consisting of silane compounds represented by formula (1), formula (2) and formula (3) as above, and after heating, further replacing the alcohol solvent with a ketone, ether or ester having 1 to 10 carbon atoms as a solvent. A method for adjusting the surface charge of hollow silicon oxide particles, which is adjusted using the manufacturing method of any one of claims 11 to 14.