Abstract: This invention is a process for making modified silica filler comprising the steps of:
(A) contacting an acidic aqueous suspension of precipitated or colloidal silica, optionally in the presence of a surfactant and/or a water-miscible solvent, with a combination of
(a) a functionalizing coupling agent, and
(b) an organometallic hydrophobing compound in a weight ratio of (a) to (b) of at least 0.001 to 1 to form an acidic aqueous suspension of chemically treated silica filler having a pH of 2.0 or less
(B) treating the acidic aqueous suspension of the chemically treated filler with an acid-neutralizing agent to increase the pH of the suspension to a range of from greater than 2.0 to 10, and
(C) recovering the chemically treated filler.
This invention is also modified silica filler that has a pH of from about 5.0 to 10.0, where the silica filler is made by the method of this invention.
Type:
Grant
Filed:
August 11, 2000
Date of Patent:
May 7, 2002
Assignee:
Dow Corning Corporation
Inventors:
Debora Frances Bergstrom, Lisa Marie Boswell, Mark David Fisher, James Richard Hahn, Timothy A. Okel, Clifford Carlton Reese