| 摘要 |
The invention provides a highly alkali resistant colloidal silica while retaining an excellent cocoon-shape and excellent performance as abrasive particles, and a process for the manufacture thereof. It is a cocoon-shaped colloidal silica prepared by hydrolyzing and condensing an alkoxysilane condensate in the presence of an ammonia or ammonium salt catalyst. It is also a cocoon-shaped colloidal silica prepared by adding continuously an alkoxysilane condensate or its solution in an aqueous solvent to an aqueous solution of ammonia or an ammonium salt or to an aqueous solution containing ammonia or an ammonium salt and an aqueous solvent, thereby hydrolyzing the alkoxysilane; and further heating under pressure. The temperature to which the foregoing colloidal silica is heated under pressure is preferably 105 to 374.1 ° C.; and the alkoxysilane condensate preferably has an average degree of condensation of 2 to 8.
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