PREPARATION OF SIO2-TIO2 SPHERICAL-PARTICLES BY W O-TYPE EMULSION TECHNIQUE/

Factors affecting the characteristics of particles formed were investi gated in such cases where the emulsion type was the same, W/O, but par ticle-forming components were added to the O phase in method 1 and to the W phase in method 2. The theoretical composition of particles was 80SiO(2) . 20TiO(2). It was necessary to use a complex alkoxide soluti on to obtain single-type spherical particles. In general, the size dis tribution of particles was smaller and the yield was lower in method 1 than in method 2. The mean size and size distribution decreased with increasing ratio of [H2O]/[M(OR)(4)] in both methods. The size distrib ution was not greatly affected by the amount of surfactant in both met hods, The oxide composition was closer to the theoretical value but mo re organic materials tended to be contained in particles formed by met hod 2. TiO2 content was always higher than the theoretical value in pa rticles formed by method 1. In method 2, the mean size, size distribut ion, oxide composition and yield of particles were affected significan tly by the time from the preparation of gelling solution up to the beg inning of the particle-forming reaction.