| abstract |
A method for the preparation of hydrophobicnprecipitated silicas which are useful as reinforcing fillersnin rubber compositions. The method comprises a first stepnwherein an aqueous suspension of precipitated silica isncontacted with an organosilicon compound in the aqueousnphase in the presence of a catalytic amount of an acid toneffect hydrophobing of the precipitated silica therebynforming an aqueous suspension of a hydrophobic precipitatednsilica. In the subsequent step, the aqueous suspension ofnhydrophobic precipitated silica is contacted with a water-immisciblenorganic solvent at a solvent to silica weightnratio greater than 5:1 to effect separation of thenhydrophobic precipitated silica from the aqueous phase. |