The invention relates to a method for producing aerogels, in particular silica aerogels, by way of a sol-gel process.

The present invention relates to a process for preparing aqueous colloidal silica sols of high purity from silicate solutions, to aqueous colloidal silica sols with a specific profile of impurities, and to the use thereof. The invention further encompasses high-purity aqueous silica obtained as an intermediate in the course of the purification process, high-purity silicon dioxide obtainable by dewatering, and the use thereof.

A heat-insulation material does not cause deterioration in heat-insulation performance and any loss of components included therein, and possesses an excellent radiation-preventing function. The heat-insulation material includes: a first heat-insulation layer that includes a first silica xerogel and a first radiation-preventing material; and a third heat-insulation layer that includes a third silica xerogel and second fibers, wherein the first heat-insulation layer and the third heat-insulation layer are layered. An electronic device includes the heat-insulation material. Yet further disclosed is a method for producing the heat-insulation material.

The present application relates to a method for producing silica particles, and to the silica particles produced by such method. The present application further relates to compositions comprising the silica particles produced by such method as well as to uses of such silica particles and compositions comprising such silica particles.

Provided is a silica-based polishing particle, particularly suitable for primary polishing, which provides a high polishing rate on the surface of a substrate and which prevents particle residues on the substrate after polishing, and an abrasive including the silica-based polishing particle. A silica-based polishing particle with a three-dimensional polycondensation structure containing an alkoxy group, wherein the particle has an average particle diameter (d) of 5 to 300 nm, an aspect ratio of more than 1.20 and 5.00 or less, and a carbon content of 0.005% by mass or more and less than 0.50% by mass.

Disclosed are novel aqueous aluminum complex compositions and methods of making and using them. The novel compositions comprise very low halide content, even when made from aluminum chlorohydrate. The compositions find use in the production of zeolites, coatings, abrasives, binders, and refractories; and in the treatment of wastewater for example. The methods of making the novel compositions include passing a first aqueous aluminum complex composition through an anion exchange column or otherwise contacting the first composition with the anion exchange resin to provide a second aqueous aluminum complex composition that is different from the first aqueous aluminum complex composition. Also disclosed are methods of making zeolites and aqueous silica-alumina compositions from the novel aqueous aluminum complex compositions.

To provide a method for producing an alkali silicate aqueous solution containing a reduced amount of foreign substance of plate-like fine particles and a method for producing a silica sol containing a reduced amount of foreign substance of plate-like fine particles. A method for producing an alkali silicate aqueous solution fulfilling the following condition: the existing amount of plate-like fine particles having a length of one side of 0.2 to 4.0 m and a thickness of 1 to 100 nm is determined to be 0 to 30%. The method for producing an alkali silicate aqueous solution includes the steps of adjusting a silica concentration of an alkali silicate aqueous solution to 0.5 to 10.0% by mass and filtering the alkali silicate aqueous solution through a filter having a removal rate of particles with a primary particle size of 1.0 m of 50% or more.

A heat-insulation material does not cause deterioration in heat-insulation performance and any loss of components included therein, and possesses an excellent radiation-preventing function. The heat-insulation material includes: a first heat-insulation layer that includes a fist silica xerogel and a first radiation-preventing material; and a third heat-insulation layer that includes a third silica xerogel and second fibers, wherein the first heat-insulation layer and the third heat-insulation layer are layered. An electronic device includes the heat-insulation, material. Yet further disclosed is a method for producing the heat-insulation material.

A process for producing a charge-reversed aqueous silica sol includes: (a) providing a slurry of an acidic cation-exchange solid in an aqueous liquid; (b) providing a starting aqueous silica sol with an alkaline pH and including a monovalent cation(s); (c) contacting the slurry with the starting sol; (d) separating the acidic cation-exchange solid from the mixture (c) to leave a decationised aqueous silica sol with an acidic pH and a reduced monovalent cation(s) content compared to the starting sol; and (e) contacting the decationised sol with a compound(s) including a modifying element(s) that can adopt a +3 or +4 oxidation state to produce a charge-reversed aqueous silica sol whose silica particles include the modifying element(s) on their surface. The S-value of the starting sol is from about 10 to about 50%, and the surface area of colloidal silica particles in the starting sol is at least about 500 m.sup.2 g.sup.1.

A method for producing a high purity silica sol is provided. This method has enabled use of water glass for the starting material, and the resulting silica sol has a reduced metal impurity Cu and Ni content compared to conventional methods. The method comprises (1) ultrafiltration of an aqueous solution of an alkali silicate; (2) ion exchange process for removal of at least a part of cationic components in the purified aqueous solution of an alkali silicate; (3) another ion exchange process using a chelating ion exchange resin to obtain high purity silicate solution; and (4) adjustment of a part of the high purity silicate solution (seed solution) to alkaline pH and mixing of this solution with another part of the solution (feed solution) to produce a high purity silica sol having a Cu concentration and a Ni concentration (in relation to the dry silica) of up to 50 ppb.