Cabot Corporation

Vinayan C Menon

Douglas M Smith

Kenneth C Koehlert

Joanne Paul

Stephen C Wallace

Alok Maskara

The present invention provides a method of treating silica, wherein dry silica is contacted with a reaction medium consisting essentially of concentrated aqueous acid and a hydrophobing agent selected from the group consisting of organosiloxanes and organochlorosilanes. The silica is then reacted with the hydrophobing agent in the reaction medium for about 90 minutes or less at a temperature from about 10&deg; C. to about 40&deg; C. to provide a hydrophobic treated silica. The hydrophobic treated silica then is recovered.

Method of preparing hydrophobic silica

The present invention provides a method of preparing lipophilic silica in an aqueous medium in the absence of added acids, bases, or organic solvents. In particular, the present inventive method of preparing lipophilic silica comprises (a) providing a mixture consisting essentially of (i) at least one organically modified silica precursor which is a trifunctional silane, (ii) water, and (iii) at least one tetrafunctional silane, (b) allowing the organically modified silica to form in the mixture, and (c) removing the organically modified silica from the mixture.

Method of preparing organically modified silica

The present invention provides a method of treating silica wherein silica is reacted with a di- or tri-functional organosilane in an aqueous acid medium to provide a crude organosilane-capped silica product containing organosilicon impurities. The organosilicon impurities are extracted from the crude product with an organic liquid to provide a purified product consisting essentially of organosilane-capped silica. The purified product is dried to provide a dry organosilane-capped silica. The aqueous acid medium can include a displacing reagent which displaces at least one reactive functional group of the di- or tri-functional organosilane. The present invention further provides-continuous methods of treating silica with di- and tri-functional organosilanes, wherein the organic liquid and/or the organosilicon impurities are recycled and reused.

Polyfunctional organosilane treatment of silica

A method of preparing treated silica is described. The method comprises mixing a hydrolyzable silica precursor such as methyltrichlorosilane with water, an acid (e.g., hydrochloric acid) and a hydrophobing agent capable of rendering polar silanol groups hydrophobic, such as trimethylchlorosilane. The treated silica is then recovered from the mixture. The inventive method provides a number of mechanisms for controlling the physical properties (e.g., particle size, surface area, etc.) of the treated silica. For example, the rate of hydrolysis of the silica precursor, which impacts these physical properties, can be regulated by the nature and concentration of the acid used in the reaction.

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Albuquerque, NM, United States of America

Vinayan C Menon