METHOD FOR PREPARING HYDROPHOBIC SILICA GELS

摘要

A method for the preparation of hydrophobic silica gels which are useful as reinforcing fillers in rubber compositions. The method comprises two steps, where in the first step a silica hydrosol is contacted with a sufficient concentration of a strong mineral acid at a pH less than pH 1 to form a silica hydrogel. In the second step the silica hydrogel is contacted with described organosilicon compounds in the presence of a catalytic amount of a strong acid to effect hydrophobic of the silica hydrogel thereby forming a hydrophobic silica gel having a surface area within a range of 100 m<2>/g to 750 m<2>/g as measured in the dry state. In a preferred method the hydrophobic silica hydrogel is contacted with a sufficient quantity of a water-immiscible organic solvent to convert the hydrophobic silica hydrogel into a hydrophobic silica organogel.