Process for preparing a water repellent silica sol

Abstract

A water repellent silica sol comprises colloidal silica particles of a size of 100 nm or less whose surfaces have been made water-repellent by an organic group-substituted silane. The water repellent silica sol is produced by a process which comprises reacting a silica colloid dispersed in a non-polar organic solvent with an organic group-substituted silane so that the surfaces of the colloidal silica particles are made water-repellent by the organic group-substituted silane. Alternatively, the water repellent silicate sol is prepared by a process which comprises adding a non-polar organic solvent, a cationic surface active agent and an organic group-substituted silane to a water-dispersed silica colloid, forming an emulsion therefrom, removing water from the emulsion by azeotropic dehydration and refluxing the emulsion under heating.

Dependencies are inferred from the claim text.