Patent ID: 7713626

Claim:
The process for producing the silanised, structurally modified silicas, comprising a) treating pyrogenically produced silicas with a surface-modifying agent(s) in either vapor or spray form, wherein the modifying agent(s) is suitable for fixing vinyl groups or vinyl silyl groups and hydrophobic groups selected from dimethyl silyl, dimethyl silyl, monomethyl silyl or mixtures thereof to the surface of the silica, b) heat treating the surface agent-modified silica, c) structurally modifying the heat treated surface agent modified silica by mechanical action to form low structured, surface agent-modified pyrogenic silica, d) post-grinding and heat treating the structurally modified silica and e) recovering the ground, heat treated, silanized, structurally modified pyrogenic silica, having surfaces fixed thereto vinyl groups or vinyl silyl groups, and hydrophobic groups selected from trimethyl silyl, dimethyl silyl, monomethyl silyl or mixtures thereof.