Cabot Corporation

Joanne Liu

Yakov E Kutsovsky

Michael D Morris

Steven E Brown

George P Fotou

The invention provides a process for the production of fumed silica. The process comprises providing a silicon halide feedstock comprising about 80% to 100% methyltrichlorosilane, combining the silicon halide feedstock with hydrogen gas and oxygen gas to form a reactant mixture, discharging the reactant mixture out of a burner, and combusting the hydrogen gas and the oxygen gas of the reactant mixture so as to hydrolyze the silicon halide feedstock to produce fumed silica. Hydrogen (H) is present in a mole fraction of about 0.11 or less based on the reactant mixture, and/or the velocity of the reactant mixture upon exiting the burner is about 25 m/s or more.

Process for the production of fumed silica

A method of preparing a dispersion of aggregate metal oxide particles having a pre-selected average aggregate particle diameter comprising pre-selecting a desired percent-reduction in the average aggregate particle diameter of the metal oxide particles, providing a dispersion standard pertaining to a dispersion of the aggregate metal oxide particles, wherein the dispersion standard correlates (i) the solids concentration of the dispersion with (ii) the percent-reduction in the aggregate particle diameter of the aggregate metal oxide particles that occurs when the dispersion is milled in a high-shear mixer, and preparing and milling a dispersion of the aggregate metal oxide particles in a high-shear milling device at a solids concentration that is within 10% of the solids concentration determined by the standard to provide a dispersion of aggregate metal oxide particles having the desired average aggregate particle diameter. Also provided is a method for reducing the average aggregate particle diameter of aggregate metal oxide particles, and a dispersion prepared by the method.

Method of preparing an aggregate metal oxide particle dispersion having a desired aggregate particle diameter

The invention provides an aqueous dispersion comprising fumed silica particles, colloidal silica particles, and water. The fumed silica particles have a BET surface area of about 70 to about 140 m/g, and the colloidal silica particles have a BET surface area of about 110 to about 150 m/g. Also, the total amount of silica in the dispersion is about 35% to about 60% by weight, and the fumed silica particles comprise about 25% to about 80% by weight of the total amount of silica in the dispersion. The invention also provides a coating composition and a recording medium incorporating the inventive dispersion.

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Reading, MA, United States of America

Joanne Liu