US Patent 7713626 Silanised silicas

Silanized, structurally modified silicas, characterised by vinyl groups or vinyl silyl groups fixed to the surface, hydrophobic groups such as trimethyl silyl and/or dimethyl silyl and/or monomethyl silyl additionally being fixed to the surface, having the following physico-chemical properties: BET surface area m2/g: 25-400 Average primary particle size nm: 5-50 pH: 3-10 Carbon content %: 0.1-10 DBP value %: <200 or not determinable are produced by treating silica with a surface-modifying agent, heat treating and then structurally modifying the mixture obtained. The silica can be used as a filler in silicone rubber.