AMORPHOUS, FINE SILICA PARTICLES, AND METHOD FOR THEIR PRODUCTION AND THEIR USE

摘要

Amorphous silica particles produced by flame hydrolysis of a silicon compound, which has an average median diameter of 0.1 to 0.7 mu m, a BET specific surface area of 5 to 30 m<2>/g, a dispersion coefficient of 40 or less and an absolute value of frictional electrification charge of 20 mu C/m<2> or more; and a method for producing such silica particles which comprises introducing a gaseous silicon compound into a flame having a temperature not lower than the melting point of silica at an increased concentration of silica and growing the generated silica particles in this flame with a short residence time. The silica particles have a shape near to the true sphere and has a very narrow diameter distribution and thus suitable as a filler for a semiconductor sealant and other various materials, and further is suitably used as an external or internal additive for an elctrophotographic toner, a sensitive material and a charge transferring layer material for elctrophotography and the like due to its great capability of being electrified.