Dow Corning Corporation

David J Wilson

Brian Robert Harkness

Phillip Joseph Griffith

William Herron

Rosemary M Taylor

Eric Damme

Fabrice Lebecq

Jean De Habimana

A compound of formula (I) is disclosed for use as a silylating agent: ##STR1## wherein each R.sup.1 is independently a hydrogen atom, an alkyl group or an alkenyl group with at least one R.sup.1 being a hydrogen atom or alkenyl group, and R.sup.2 is a hydrogen atom or an alkyl group. Also disclosed is a method of making the compound, and a method of using the compound as a silylating agent.

Silylating agent

A method for the preparation of hydrophobic fumed silicas which are useful, for example, as reinforcing fillers in rubber compositions. The method comprises two steps, where in the first step an aqueous suspension of fumed silica is contacted with an organosilicon compound in the presence of a catalytic amount of an acid to effect hydrophobing of the fumed silica. In the preferred method the first step is conducted in the presence of a water miscible organic solvent which facilitates hydrophobing of the fumed silica with the organosilicon compound and the fumed silica has a BET surface area greater than 50 m.sup.2 /g. In the second step the aqueous suspension of the fumed silica is contacted with a water-immiscible organic solvent at a solvent to silica weight ratio greater than 0.1:1 to effect separation of the hydrophobic fumed silica from the aqueous phase. In a preferred process the hydrophobic fumed silica has a surface area within a range of about 100 m.sup.2 /g to 750 m.sup.2 /g.

Method for preparing hydrophobic fumed silica

A method for the preparation of hydrophobic precipitated silicas which are useful, for example, as reinforcing fillers in rubber compositions. The method comprises two steps, where in the first step an aqueous suspension of precipitated silica is contacted with an organosilicon compound in the presence of a catalytic amount of an acid to effect hydrophobing of the precipitated silica. In the second step the aqueous suspension of the hydrophobic precipitated silica is contacted with a water-immiscible organic solvent at a solvent to silica weight ratio greater than 5:1 to effect separation of the hydrophobic precipitated silica from the aqueous phase.

Method of preparing hydrophobic precipitated silica

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Penarth, United Kingdom

David J Wilson