Patent ID: 8075862

Claim:
A hydrophobic fumed silica obtained by milling a fumed silica with a pinned-disk mill or an air-jet mill, which has fixed thereon at least one of dimethylsilyl and monomethylsilyl groups on a surface due to silanization, wherein said hydrophobic fumed silica has a grindometer value which is reduced by more than 60% compared with said fumed silica a tamped density of 10 to 80 g/l, a BET specific surface area of 150 to 200 m 2 /g, an average particle size according to Cilas of 3.0 to 20.0 μm, a pH in the range from 4.0 to 5.0, and a carbon content of 0.1 to 10% by weight.