Colloidal silica and method for producing same
AssigneeFuso Chemical Co., Ltd.
InventorsYuka Fujimura, Yoshiki Michiwaki
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Abstract
The present invention provides colloidal silica containing silica particles excellent in compactness and excellent in maintenance of the bumpy surface under basic conditions, and provides a method for producing the colloidal silica. The present invention provides colloidal silica containing silica particles having a bumpy surface, wherein (1) the silica particles have a content of alkoxy groups of 1000 ppm or more, and (2) the silica particles have a reduction in specific surface area of 15.0% or less when the silica particles are heated under basic conditions.
Claims4
A colloidal silica comprising silica particles, wherein
- (1) the colloidal silica contains metallic impurities, in an amount of 1 ppm or less,
- (2) the silica particles have a reduction in specific surface area of 15.0% or less when the silica particles are heated under basic conditions, and
- (3) the silica particles have a surface roughness of 1.1 or more, wherein the surface roughness is determined by dividing a BET specific surface area (B1) by a specific surface area (S1) calculated from a SEM minor diameter.
A method for producing colloidal silica containing silica particles having a bumpy surface, the method comprising in series
- (1) step 1 of preparing a mother liquor containing an alkaline catalyst and water,
- (2) step 2 of adding an alkoxysilane to the mother liquor to prepare a seed particle dispersion, and
- (3) step 3 of adding water, an alkaline catalyst, and an alkoxysilane to the seed particle dispersion,
- wherein the alkaline catalyst is at least one amine selected from the group consisting of a primary amine, a secondary amine, and a tertiary amine, wherein the amine contains no hydroxyl group as a substituent,
- in step 3, the molar ratio (s3/c3) of the amount of the alkoxysilane added s3 (mol) to the amount of the alkaline catalyst added c3 (mol) is more than 185 and 400 or less, and
- the silica particles have a surface roughness of 1.1 or more, wherein the surface roughness is determined by dividing a BET specific surface area (B1) by a specific surface area (S1) calculated from a SEM minor diameter.
Dependencies are inferred from the claim text.