| abstract |
Disclosed are spherical particles of a polyorganosilsesquioxane resin have a unique optical properties when each particle has a core-cladding composite structure consisting of a core portion of, for example, a polymethylsilsesquioxane resin and a cladding layer of, for example, a polyphenylsilsesquioxane resin having refractive indices differing by at least 0.02, the diameter of the core portion being in a specified range relative to the diameter of the whole particle. Such particles of a core-cladding structure can be prepared by conducting the hydrolysis-condensation reaction of organotrialkoxysilanes, e.g., methyl trimethoxysilane and phenyl trimethoxysilane, in two successive steps by using different silane compounds or by using silane mixtures of different mixing proportion in the first and second step reactions. |