abstract |
PURPOSE: To obtain a water-repellent silica sol which can be dispersed in a nonpolar org. solvent and shows excellent dispersion stability by making the surface of colloidal silica particles water-repellent with alkyl-substd. silane and specifying the particle size of the water-repellent colloid particles. n CONSTITUTION: The surface of colloidal silica particles is made water-repellent with alkyl-substd. silane by effecting the reaction of silica colloid dispersed in a nonpolar org. solvent with alkyl-substd. silane. Thus, water-repellent silica sol containing colloidal silica particles with water-repellent surface and ≤100nm particle diameter can be obtained. The silica colloid dispersed in a nonpolar org. solvent is prepared, for example, by adding a pH controller to a water- dispersed silica colloid to obtain pH1-5, adding a nonpolar org. solvent and a surfactant to make an emulsion, and then effecting azeotropic dehydration. n COPYRIGHT: (C)1992,JPO&Japio |