Patent ID: 6384125
Filing Date: 2002-05-07
Classification: B60C,B82Y,C01P,C08K,C09C

Abstract:
A process for making a modified silica filler having a pH from about 5 to 10 comprising:(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 of the general formula: RaRâ€²bSiX4âˆ’aâˆ’b, where each R is independently selected from the group consisting of organofunctional hydrocarbon radicals comprising 1 to about 12 carbon atoms, wherein the organofunctional group is selected from vinyl, allyl, hexenyl, epoxy, glycidoxy, or (meth)acryloxy; each Râ€² is independently selected from a hydrocarbon group of from 1 to 18 carbon atoms or hydrogen; each X is independently selected from the group consisting of halogen and alkoxy radicals comprising 1 to about 12 carbon atoms, a=0, 1, 2, or 3, b=0 or 1, a+b=1, 2, or 3, with the proviso that when b=1 then a+b=2 or 3, 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 modified silica filler having a pH of 2.0 or less; (B) treating the acidic aqueous suspension of the chemically modified filler with an acid-neutralizing agent to increase the pH of the suspension to a range of from greater than 2.0 to 10; (C) recovering the modified silica filler.