| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a colloidal silica capable of providing not only rapid grinding speed but also little grinding damage and hardly causing contamination on a grinding surface when used as a grinding abrasive grain for a silicon wafer or the like. SOLUTION: Methyl silicate or a mixture of methyl silicate and methanol is dripped in a mixed solvent comprising water, methanol, ammonia or the like under stirring within 10 to 40 min, reacting the methyl silicate with water for 10-40 min to provide the objective cocoon shaped colloidal silica having 10-200 nm minor axis and 1.4-2.2 ratio of major axis/minor axis in the method for producing the colloidal silica. The ammonium ion content in the solvent based on the whole weight of the solvent is 0.5-3 wt.%, and the reaction is carried out at 10-30 deg.C. |
