Patent ID: 6303663
Filing Date: 2001-10-16
Classification: B01D,Y10T

Abstract:
A process for making a defoaming composition containing hydrophobic silica particles by the steps consisting essentially of the steps of:(a) contacting hydrophilic silica particles in the absence of an amine, diamine, or ammonium carbonate catalyst with a silicone oil hydrophobing agent in an inert liquid medium under vacuum and at a temperature within the range from about 100.degree.-180.degree. C. for a time within the range from 0.5 to 3 hrs to displace water or air within said silica particles by said hydrophobing agent and thereby form a dispersion of hydrophobic silica particles in an inert, hydrophobic medium; and(b) reducing the particle size of any oversized aggregates in said dispersion from step (a) and forming therefrom a substantially homogeneous dispersion of hydrophobic silica particles.