Highly dispersible fine hydrophobic silica powder and process for producing the same

Abstract

A high dispersible hydrophobic fine silica powder can be made, wherein the silica powder has hydrophobicity of more than 50%, triboelectrostatic charge of more than −500 μC/g, decomposition rate of an organic group on the powder surface of less than 15%, transmittance of a 5% alcoholic dispersion liquid of more than 40% preferably, and a specific surface area of more than 200 m2/g. This high dispersible hydrophobic fine silica powder can be made by mixing a hydrophobic agent comprising a volatile organic silicon compound in the gas state with a fine silica powder in a fluidized bed type reaction vessel at the time of a hydrophobic treatment, and controlling a gas flow rate to more than 5.0 cm/sec at the time of this mixing.

Dependencies are inferred from the claim text.