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

Factors affecting the characteristics of particles formed were investigated in such cases where the emulsion type was the same, W/O, but particle-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 solution to obtain single-type spherical particles. In general, the size distribution 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 distribution was not greatly affected by the amount of surfactant in both methods, The oxide composition was closer to the theoretical value but more organic materials tended to be contained in particles formed by method 2. TiO2 content was always higher than the theoretical value in particles formed by method 1. In method 2, the mean size, size distribution, oxide composition and yield of particles were affected significantly by the time from the preparation of gelling solution up to the beginning of the particle-forming reaction.