PRODUCTION OF ANHYDROUS SILICA FINE POWDER AND WATER-REPELLENT SILICA FINE POWDER

摘要

PURPOSE:To inexpensively provide anhydrous silica fine powder and water repellent silica fine powder having ultrafine particle diameter by a wet process. CONSTITUTION:Silica hydrogel is deflocculated and then subjected to azeotropic dehydration with an organic solvent capable of carrying out azeotropic dehydration and dried or burned to produce the objective anhydrous silica fine powder. Azeotropic dehydration is carried out in the presence of an acid catalyst and the treated material is dried to provide the objective water repellent silica fine powder, which is further burned to provide the anhydrous silica fine powder.