The present invention relates to a process for preparing waterglass-based silica aerogels, wherein the process comprises (a) subjecting a certain amount of a vinyltrialcoxysilane to hydrolysis in the presence of water and an inorganic acid under stirring conditions to produce a hydrolyzed vinyltrialcoxysilane solution; (b) treating a waterglass solution with an acidic cationic-exchange resin to produce a silicic acid solution; (c) forming a sol phase by contacting the hydrolyzed vinylalcoxysilane solution with the silicic acid solution; (d) forming a gel phase by adjusting the pH of the sol phase to a value in the range of from 4 to 6; and (e) subjecting the gel phase to supercritical drying to produce an aerogel. The present invention is also related to waterglass-based silica aerogels obtained by the process according to the invention, which are functionalized with vinyl groups.

The present invention relates to a process for preparing waterglass-based silica aerogels, wherein the process comprises (a) subjecting a certain amount of a vinyltrialcoxysilane to hydrolysis in the presence of water and an inorganic acid under stirring conditions to produce a hydrolyzed vinyltrialcoxysilane solution; (b) treating a waterglass solution with an acidic cationic-exchange resin to produce a silicic acid solution; (c) forming a sol phase by contacting the hydrolyzed vinylalcoxysilane solution with the silicic acid solution; (d) forming a gel phase by adjusting the pH of the sol phase to a value in the range of from 4 to 6; and (e) subjecting the gel phase to supercritical drying to produce an aerogel. The present invention is also related to waterglass-based silica aerogels obtained by the process according to the invention, which are functionalized with vinyl groups.

A silica membrane filter 10 includes an ultrafiltration membrane 15, which is disposed on a support body 14 and which contains an element 14 as a primary component, and a silica membrane 18 which is disposed on the ultrafiltration membrane 15 and which has an aryl group. The ultrafiltration membrane 15 has a structure infiltrated by Si of the silica membrane 18, the atomic ratio A (=Si/M) of Si to the element M in a membrane-side region 16, which is a region corresponding to 25% of the ultrafiltration membrane 15 from the silica membrane 18, satisfies 0.01≤A≤0.5, and the ratio A/B of the atomic ratio A to the atomic ratio B (=Si/M) in a base-material-side region 17, which is a region corresponding to 25% from the support body 14, is within the range of 1.1 or more.

A silica membrane filter 10 includes an ultrafiltration membrane 15, which is disposed on a support body 14 and which contains an element 14 as a primary component, and a silica membrane 18 which is disposed on the ultrafiltration membrane 15 and which has an aryl group. The ultrafiltration membrane 15 has a structure infiltrated by Si of the silica membrane 18, the atomic ratio A (=Si/M) of Si to the element M in a membrane-side region 16, which is a region corresponding to 25% of the ultrafiltration membrane 15 from the silica membrane 18, satisfies 0.01≤A≤0.5, and the ratio A/B of the atomic ratio A to the atomic ratio B (=Si/M) in a base-material-side region 17, which is a region corresponding to 25% from the support body 14, is within the range of 1.1 or more.

Provided is a composition including colloidal silica particles; and a solvent, in which a viscosity at 25° C. is 4 mPa.Math.s or lower. The colloidal silica particles are a composition in which a plurality of spherical silica particles are linked in a beaded shape or a composition in which a plurality of spherical silica particles are linked in a planar shape. The solvent includes a solvent A1 having a boiling point of 190° C. to 280° C. Provided is also a film forming method using the above-described composition.

The present invention provides a silica aerogel powder, a preparation method and an application thereof, and belongs to the field of preparation of insulating materials. The silica aerogel powder provided by the present invention is prepared from the following components: 100 to 300 parts by weight of aqueous solution of silica source, 200 to 400 parts by weight of oil phase solvent, 4 to 40 parts by weight of cosolvent, 0.2 to 2 parts by weight of surfactant, 10 to 60 parts by weight of sodium methylsiliconate solution, 1 to 5 parts by weight of aqueous inorganic acid solution, 3 to 10 parts by weight of sodium trimethylsilanolate solution in tetrahydrofuran (THF), and 0.3 to 0.9 part by weight of organic fatty acid in petroleum ether. The silica aerogel powder provided by the present invention is structurally uniform and features good hydrophobicity, low thermal conductivity, and low density.

The present invention provides a silica aerogel powder, a preparation method and an application thereof, and belongs to the field of preparation of insulating materials. The silica aerogel powder provided by the present invention is prepared from the following components: 100 to 300 parts by weight of aqueous solution of silica source, 200 to 400 parts by weight of oil phase solvent, 4 to 40 parts by weight of cosolvent, 0.2 to 2 parts by weight of surfactant, 10 to 60 parts by weight of sodium methylsiliconate solution, 1 to 5 parts by weight of aqueous inorganic acid solution, 3 to 10 parts by weight of sodium trimethylsilanolate solution in tetrahydrofuran (THF), and 0.3 to 0.9 part by weight of organic fatty acid in petroleum ether. The silica aerogel powder provided by the present invention is structurally uniform and features good hydrophobicity, low thermal conductivity, and low density.

[Problem] Provided is a method for producing a silica sol capable of providing consistent production of the silica sol having a uniform particle size of silica particles in any particle size of the silica particles. [Solution] A method for producing a silica sol is a method including a step of mixing liquid (A) containing an alkaline catalyst, water, and a first organic solvent with liquid (B) containing an alkoxysilane or its condensate and a second organic solvent, and liquid (C1) having a pH of 5.0 or higher and lower than 8.0 and containing water or liquid (C2) containing water and being free of an alkaline catalyst to make a reaction liquid.

[Problem] Provided is a method for producing a silica sol capable of providing consistent production of the silica sol having a uniform particle size of silica particles in any particle size of the silica particles. [Solution] A method for producing a silica sol is a method including a step of mixing liquid (A) containing an alkaline catalyst, water, and a first organic solvent with liquid (B) containing an alkoxysilane or its condensate and a second organic solvent, and liquid (C1) having a pH of 5.0 or higher and lower than 8.0 and containing water or liquid (C2) containing water and being free of an alkaline catalyst to make a reaction liquid.

There is provided a method for producing a silica sol including: a first step of adding an organic acid to at least one of liquid (A) containing an alkaline catalyst, water, and a first organic solvent and liquid (C) containing water; and a second step of mixing the liquid (A) with liquid (B) containing an alkoxysilane or its condensate and a second organic solvent, and the liquid (C) to make a reaction liquid after the first step.