Spherical SiO2 particles

摘要

The invention relates to highly monodisperse nonporous spherical SiO2 particles having average particle diameters between 0.05 and 10 mu m with a standard deviation of not more than 5 % and also a process for preparing such particles by hydrolytical polycondensation of tetraalkoxysilanes in an alkali aqueous/alcoholic ammonia medium, a sol of primary particles being first produced and the SiO2 particles obtained subsequently being brought to the desired particle size by continuous metered addition, controlled by the rate of reaction, of tetraalkoxysilane.