Abstract: An insulating composition containing silica particles, a resin, and a curing agent, wherein: when an aqueous solution of the silica particles having an SiO2 concentration of 3.8% by mass is heated at 121° C. for 20 hours, the amount of Na ions eluted from the silica particles is 40 ppm/SiO2 or less, especially, wherein the amount of Na ions eluted from the silica particles after the heating may be 5-38 ppm/SiO2, and, the silica particles may contain a polyvalent metal oxide so the ratio by mole of a polyvalent metal M to Si is 0.001-0.02; the mass ratio of Na2O/SiO2 in the silica particles may be 700-1,300 ppm; and the silica particles may have, on the surfaces thereof, a layer having a thickness of 0.1-1.5 nm and an Na2O/SiO2 mass ratio of 10-400 ppm, and may have an average particle diameter of 5-40 nm.

Abstract: A silica sol dispersed in a nitrogen-containing solvent and a silica-containing resin composition containing a nitrogen atom-containing polymer. A silica sol including silica particles containing aluminum atoms and having an average primary particle diameter of 5 to 100 nm, the silica particles being dispersed in a nitrogen-containing solvent, wherein the aluminum atoms are bonded to the surfaces of the silica particles in an amount in terms of Al2O3 of 800 to 10,000 ppm/SiO2. The silica particles are bonded to a silane compound or a hydrolysate of the silane compound. The nitrogen-containing solvent is an amide solvent. The nitrogen-containing solvent is dimethylacetamide, dimethylformamide, N-methylpyrrolidone, or N-ethylpyrrolidone. The insulating resin composition includes the silica sol and a nitrogen-containing polymer. The nitrogen-containing polymer is polyimide, polyamide, polyamic acid, polyamideimide, polyetherimide, or polyesterimide.

Abstract: A silica sol dispersed in a nitrogen-containing solvent and a silica-containing resin composition containing a nitrogen atom-containing polymer. A silica sol including silica particles containing aluminum atoms and having an average primary particle diameter of 5 to 100 nm, the silica particles being dispersed in a nitrogen-containing solvent, wherein the aluminum atoms are bonded to the surfaces of the silica particles in an amount in terms of Al2O3 of 800 to 10,000 ppm/SiO2. The silica particles are bonded to a silane compound or a hydrolysate of the silane compound. The nitrogen-containing solvent is an amide solvent. The nitrogen-containing solvent is dimethylacetamide, dimethylformamide, N-methylpyrrolidone, or N-ethylpyrrolidone. The insulating resin composition includes the silica sol and a nitrogen-containing polymer. The nitrogen-containing polymer is polyimide, polyamide, polyamic acid, polyamideimide, polyetherimide, or polyesterimide.

Abstract: A sol of inorganic oxide particles is stably dispersed in a hydrophilic organic solvent containing a hydrocarbon such as a paraffinic hydrocarbon or a naphthenic hydrocarbon. The sol contains a dispersion medium containing an organic solvent containing a C6-18 paraffinic hydrocarbon, a C6-18 naphthenic hydrocarbon, or a mixture of these, a C4-8 alcohol having a carbon chain with a carbon-carbon bond in the molecule in an amount of 0.1 to 5% by mass in the entire dispersion medium, and inorganic oxide particles having an average particle diameter of 5 to 200 nm as measured by dynamic light scattering as a dispersoid, wherein the inorganic oxide particles contain a C1-3 alkyl group bonded to a silicon atom and a C4-18 alkyl group. The paraffinic hydrocarbon is a normal paraffinic hydrocarbon or an isoparaffinic hydrocarbon. The naphthenic hydrocarbon is a saturated aliphatic cyclic hydrocarbon substitutable with a C1-10 alkyl group.

Abstract: A sol of inorganic oxide particles is stably dispersed in a hydrophilic organic solvent containing a hydrocarbon such as a paraffinic hydrocarbon or a naphthenic hydrocarbon. The sol contains a dispersion medium containing an organic solvent containing a C6-18 paraffinic hydrocarbon, a C6-18 naphthenic hydrocarbon, or a mixture of these, a C4-8 alcohol having a carbon chain with a carbon-carbon bond in the molecule in an amount of 0.1 to 5% by mass in the entire dispersion medium, and inorganic oxide particles having an average particle diameter of 5 to 200 nm as measured by dynamic light scattering as a dispersoid, wherein the inorganic oxide particles contain a C1-3 alkyl group bonded to a silicon atom and a C4-18 alkyl group. The paraffinic hydrocarbon is a normal paraffinic hydrocarbon or an isoparaffinic hydrocarbon. The naphthenic hydrocarbon is a saturated aliphatic cyclic hydrocarbon substitutable with a C1-10 alkyl group.

Abstract: Provided is an inorganic oxide dispersion (sol) in which inorganic oxide particles are dispersed in silicone oil.

Abstract: A method for preventing occurrence of creeping electrical discharge at a resin surface, the method being characterized by including dispersing nanosized inorganic fine particles in a resin, thereby preventing occurrence of creeping electrical discharge at the surface of a cured product of the resin.

Abstract: A silica-blended resin varnish contains a silica sol with a high dispersibility that is dispersed in a ketone organic solvent, in a nitrogen atom-containing polymer. The particles have an average size of 5 to 100 nm and have a carbon-carbon unsaturated bond-containing organic group and an alkoxy group bonded to surfaces thereof. The carbon-carbon unsaturated bond-containing organic group is bonded at 0.5 to 2.0 groups per unit area (nm2) of the particle surfaces. The alkoxy group is bonded at 0.1 to 2.0 groups per unit area (nm2) of the particle surfaces. The molar ratio of {(the carbon-carbon unsaturated bond-containing organic group)/(the alkoxy group)} is 0.5 to 5.0. The carbon-carbon unsaturated bond-containing organic group may be a phenyl group-containing organic group or a (meth)acryloyl group-containing organic group.

Abstract: A silica-blended resin varnish contains a silica sol with a high dispersibility that is dispersed in a ketone organic solvent, in a nitrogen atom-containing polymer. The particles have an average size of 5 to 100 nm and have a carbon-carbon unsaturated bond-containing organic group and an alkoxy group bonded to surfaces thereof. The carbon-carbon unsaturated bond-containing organic group is bonded at 0.5 to 2.0 groups per unit area (nm2) of the particle surfaces. The alkoxy group is bonded at 0.1 to 2.0 groups per unit area (nm2) of the particle surfaces. The molar ratio of {(the carbon-carbon unsaturated bond-containing organic group)/(the alkoxy group)} is 0.5 to 5.0. The carbon-carbon unsaturated bond-containing organic group may be a phenyl group-containing organic group or a (meth)acryloyl group-containing organic group.

Abstract: An insulating composition containing silica particles, a resin, and a curing agent, wherein: when an aqueous solution of the silica particles having an SiO2 concentration of 3.8% by mass is heated at 121° C. for 20 hours, the amount of Na ions eluted from the silica particles is 40 ppm/SiO2 or less, especially, wherein the amount of Na ions eluted from the silica particles after the heating may be 5-38 ppm/SiO2, and, the silica particles may contain a polyvalent metal oxide so the ratio by mole of a polyvalent metal M to Si is 0.001-0.02; the mass ratio of Na2O/SiO2 in the silica particles may be 700-1,300 ppm; and the silica particles may have, on the surfaces thereof, a layer having a thickness of 0.1-1.5 nm and an Na2O/SiO2 mass ratio of 10-400 ppm, and may have an average particle diameter of 5-40 nm.

Abstract: A method for preventing occurrence of creeping electrical discharge at a resin surface, the method being characterized by including dispersing nanosized inorganic fine particles in a resin, thereby preventing occurrence of creeping electrical discharge at the surface of a cured product of the resin.

Abstract: A silica sol which has excellent moisture absorption resistance and stability as well as high purity and which does not cause coloring of a solvent or a resin to which the silica sol has been applied. The silica sol contains high-purity silica particles, water and/or a liquid organic medium serving as a dispersion medium, and an organic base compound, the silica particles being dispersed in the dispersion medium, wherein the silica particles satisfy the following requirements (a) to (c): (a) the silica particles have a specific surface area, as determined through a nitrogen absorption method, of 20 to 500 m2/g; (b) the silica particles have a moisture absorption amount per specific surface area thereof of 0.5 mg/m2 or less; and (c) the organic base compound is not substantially contained in the inside thereof.

Abstract: The silica sol of the invention contains silica particles having a mean primary particle size of 20 to 100 nm and which has a silica particle size/mean primary particle size ratio, determined through dynamic light scattering, of 3.0 or less, wherein the silica particles are surface-treated with an organic silane compound and have an ?-ray emission rate of 0.005 counts/cm2·hr or less and a moisture absorption coefficient, determined after allowing the silica particles to stand for 48 hours at 23° C. and a relative humidity of 50 RH %, of 0.5 mass % or lower.

Abstract: There is provided colloidal silica particles comprising at least one polyvalent metal element M selected from a group consisting of iron, aluminum, zinc, zirconium, titanium, tin, and lead in an average content of 0.001 to 0.02 in terms of an M/Si molar ratio, and having an average primary particle diameter of 5 to 40 nm, wherein the content of the polyvalent metal element M present in an outermost layer of the colloidal particles is 0 to 0.003 atom per square nanometer (nm2) of a surface area of the colloidal particles; and a silica sol that the colloidal silica particles are dispersed in an organic solvent, a silica sol that the colloidal silica particles are dispersed in a polymerizable compound, and a silica sol that the colloidal silica particles are dispersed in a dicarboxylic anhydride.

Abstract: There is provided colloidal silica particles comprising at least one polyvalent metal element M selected from a group consisting of iron, aluminum, zinc, zirconium, titanium, tin, and lead in an average content of 0.001 to 0.02 in terms of an M/Si molar ratio, and having an average primary particle diameter of 5 to 40 nm, wherein the content of the polyvalent metal element M present in an outermost layer of the colloidal particles is 0 to 0.003 atom per square nanometer (nm2) of a surface area of the colloidal particles; and a silica sol that the colloidal silica particles are dispersed in an organic solvent, a silica sol that the colloidal silica particles are dispersed in a polymerizable compound, and a silica sol that the colloidal silica particles are dispersed in a dicarboxylic anhydride.

Abstract: There is provided colloidal silica particles comprising at least one polyvalent metal element M selected from a group consisting of iron, aluminum, zinc, zirconium, titanium, tin, and lead in an average content of 0.001 to 0.02 in terms of an M/Si molar ratio, and having an average primary particle diameter of 5 to 40 nm, wherein the content of the polyvalent metal element M present in an outermost layer of the colloidal particles is 0 to 0.003 atom per square nanometer (nm2) of a surface area of the colloidal particles; and a silica sol that the colloidal silica particles are dispersed in an organic solvent, a silica sol that the colloidal silica particles are dispersed in a polymerizable compound, and a silica sol that the colloidal silica particles are dispersed in a dicarboxylic anhydride.

Abstract: A silica sol which has excellent moisture absorption resistance and stability as well as high purity and which does not cause coloring of a solvent or a resin to which the silica sol has been applied. The silica sol contains high-purity silica particles, water and/or a liquid organic medium serving as a dispersion medium, and an organic base compound, the silica particles being dispersed in the dispersion medium, wherein the silica particles satisfy the following requirements (a) to (c): (a) the silica particles have a specific surface area, as determined through a nitrogen absorption method, of 20 to 500 m2/g; (b) the silica particles have a moisture absorption amount per specific surface area thereof of 0.5 mg/m2 or less; and (c) the organic base compound is not substantially contained in the inside thereof.

Abstract: There is provided colloidal silica particles comprising at least one polyvalent metal element M selected from a group consisting of iron, aluminum, zinc, zirconium, titanium, tin, and lead in an average content of 0.001 to 0.02 in terms of an M/Si molar ratio, and having an average primary particle diameter of 5 to 40 nm, wherein the content of the polyvalent metal element M present in an outermost layer of the colloidal particles is 0 to 0.003 atom per square nanometer (nm2) of a surface area of the colloidal particles; and a silica sol that the colloidal silica particles are dispersed in an organic solvent, a silica sol that the colloidal silica particles are dispersed in a polymerizable compound, and a silica sol that the colloidal silica particles are dispersed in a dicarboxylic anhydride.

Abstract: The silica sol of the invention contains silica particles having a mean primary particle size of 20 to 100 nm and which has a silica particle size/mean primary particle size ratio, determined through dynamic light scattering, of 3.0 or less, wherein the silica particles are surface-treated with an organic silane compound and have an ?-ray emission rate of 0.005 counts/cm2·hr or less and a moisture absorption coefficient, determined after allowing the silica particles to stand for 48 hours at 23° C. and a relative humidity of 50 RH %, of 0.5 mass % or lower.

Abstract: There is provided colloidal silica particles comprising at least one polyvalent metal element M selected from a group consisting of iron, aluminum, zinc, zirconium, titanium, tin, and lead in an average content of 0.001 to 0.02 in terms of an M/Si molar ratio, and having an average primary particle diameter of 5 to 40 nm, wherein the content of the polyvalent metal element M present in an outermost layer of the colloidal particles is 0 to 0.003 atom per square nanometer (nm2) of a surface area of the colloidal particles; and a silica sol that the colloidal silica particles are dispersed in an organic solvent, a silica sol that the colloidal silica particles are dispersed in a polymerizable compound, and a silica sol that the colloidal silica particles are dispersed in a dicarboxylic anhydride.