Patent ID: 7786022

Claim:
A method for preparing a silica sol, which comprises hydrolyzing and condensing a hydrolyzable silane compound in the presence of at least one hydrophilic basic catalyst selected from alkali metal hydroxides and quaternary ammonium hydroxides represented by the following formula (1): (R 1 ) 4 N + OH − (1) wherein, R 1 s may be the same or different and each independently represents a hydrocarbon group which may contain an oxygen atom and the cationic portion [(R 1 ) 4 N + ] satisfies the following relationship (2): (N+O)/(N+O+C)≧⅕ (2) in which, N, O and C are the numbers of nitrogen, oxygen and carbon atoms contained in the cationic portion, respectively, and at least one hydrophobic basic catalyst selected from quaternary ammonium hydroxides which do not satisfy the above-described relationship (2).