There is provided a method for obtaining a purified aqueous solution of silicic acid containing less metal impurities such as Cu and Ni using water glass as a raw material with less number of purification steps than that in conventional methods without using any unnecessary additives. The method for producing a purified aqueous solution of silicic acid, the method comprising the steps of: (a) passing an aqueous solution of alkaline silicate having a silica concentration of 0.5% by mass or more and 10% by mass or less through a column filled with a polyamine-, iminodiacetic acid-, or aminophosphoric acid-type chelating resin, and (b) passing the aqueous solution passed in the step (a) through a column filled with a hydrogen-type cation exchange resin.

There is provided a method for obtaining a purified aqueous solution of silicic acid containing less metal impurities such as Cu and Ni using water glass as a raw material with less number of purification steps than that in conventional methods without using any unnecessary additives. The method for producing a purified aqueous solution of silicic acid, the method comprising the steps of: (a) passing an aqueous solution of alkaline silicate having a silica concentration of 0.5% by mass or more and 10% by mass or less through a column filled with a polyamine-, iminodiacetic acid-, or aminophosphoric acid-type chelating resin, and (b) passing the aqueous solution passed in the step (a) through a column filled with a hydrogen-type cation exchange resin.

Provided is a method for producing a silica sol. A gel-like material cannot be generated and highly associated silica particles can be obtained.

A method for producing a silica sol, comprising a step of making a reaction liquid by mixing liquid (A) comprising an alkaline catalyst, water, a first organic solvent and silica particles for association with liquid (B) comprising at least one of tetramethoxysilane and a condensate thereof and a second organic solvent, wherein during the mixing, an addition rate of the liquid (B) is 8.510.sup.4 to 5.610.sup.3 mol/min in terms of silicon atoms with respect to 1 mol of the water contained in the liquid (A).

A lost circulation material (LCM) is provided having an alkaline nanosilica dispersion and an ester activator. The alkaline nanosilica dispersion and the ester activator may form a gelled solid after interaction over a contact period. Methods of lost circulation control using the LCM are also provided.

The present invention relates to a method for manufacturing an aerogel sheet. The method for manufacturing an aerogel sheet includes: a step (a) of preparing silica sol; a step (b) of preparing a gelling catalyst; a step (c) of injecting the silica sol, which is prepared in the step (a), to a surface of a blanket to impregnate the silica sol; and a step (d) of injecting the gelling catalyst, which is prepared in the step (b), to the surface of the blanket, into which the silica sol is impregnated, to gelate the silica sol.

The present invention relates to a method for manufacturing an aerogel sheet. The method for manufacturing an aerogel sheet includes: a step (a) of preparing silica sol; a step (b) of preparing a gelling catalyst; a step (c) of injecting the silica sol, which is prepared in the step (a), to a surface of a blanket to impregnate the silica sol; and a step (d) of injecting the gelling catalyst, which is prepared in the step (b), to the surface of the blanket, into which the silica sol is impregnated, to gelate the silica sol.

Provided is a dispersion containing high-purity silica particles and a method for producing the same. A first solution containing a silane alkoxide and a second solution containing fine bubbles having an average bubble diameter of 40 nm to 10 m are mixed. Thus, the silane alkoxide is hydrolyzed without using an alkaline catalyst in a liquid phase containing the fine bubbles, so that uniform silica particles having an average particle size of 3 to 10 nm are produced. Further, hydrolysis is carried out by adding a hydrolyzable metal compound to the dispersion containing the silica particles in the presence of the fine bubbles and the alkaline catalyst. Thus, the silica particles are grown, so that a uniform silica-based particle dispersion containing particles having an average particle size of more than 10 nm and 300 nm or less is produced.

Provided is a dispersion containing high-purity silica particles and a method for producing the same. A first solution containing a silane alkoxide and a second solution containing fine bubbles having an average bubble diameter of 40 nm to 10 m are mixed. Thus, the silane alkoxide is hydrolyzed without using an alkaline catalyst in a liquid phase containing the fine bubbles, so that uniform silica particles having an average particle size of 3 to 10 nm are produced. Further, hydrolysis is carried out by adding a hydrolyzable metal compound to the dispersion containing the silica particles in the presence of the fine bubbles and the alkaline catalyst. Thus, the silica particles are grown, so that a uniform silica-based particle dispersion containing particles having an average particle size of more than 10 nm and 300 nm or less is produced.

A method for manufacturing an aerogel blanket, the method capable of simplifying manufacturing equipment by performing gelation while rotating a reaction vessel, improving manufacturing efficiency by controlling manufacturing time regardless of the thickness of an aerogel blanket and improving thermal conductivity by uniformly forming an aerogel in a substrate for blanket.

A method for manufacturing an aerogel blanket, the method capable of simplifying manufacturing equipment by performing gelation while rotating a reaction vessel, improving manufacturing efficiency by controlling manufacturing time regardless of the thickness of an aerogel blanket and improving thermal conductivity by uniformly forming an aerogel in a substrate for blanket.