| 摘要 |
A colloidal silica which has excellent alkali resistance while retaining an excellent cocoon shape and excellent performance, which are required for use as abrasive grains. The silica is a cocoon-shaped colloidal silica obtained by hydrolyzing an alkoxysilane condensate in the presence of ammonia or an ammonium salt catalyst. Alternatively, the silica is a cocoon-shaped colloidal silica obtained by: dropping an alkoxysilane condensate or a solution thereof in an aqueous solvent into an aqueous solution of either ammonia or an ammonium salt or into an aqueous solution containing both ammonia or an ammonium salt and an aqueous solvent to hydrolyze the alkoxysilane; and heating the reaction mixture under pressure. The temperature at which the colloidal silica is heated under pressure is preferably from 105 to 374.1°C. The alkoxysilane condensate has an average degree of condensation of preferably 2 to 8.
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