W. R. Grace Co.-conn.

Sandra Joan Kempske

Michael V Ernest

Michael Bruce Thomas

James George Miller

Cristian Libanati

A silica gel abrasive having good cleaning and low abrasion is prepared by combining at least two silica gels before adjusting the pH of the abrasive to a pH in the range of 3-6. One of the gels is washed at relatively lower temperature compared to the wash temperature of a second gel. The two gels are then milled and dried to a median particle size in the range of 5 to 12 microns. The volatiles content of the gel combination is in the range of 20-40% by weight. The resulting mixtures have low abrasion as measured by Einlehner, e.g., in the range of 0.5 to 3 when measured using a brass screen. A dentifrice composition comprising 10 to 25% of the abrasive has a PCR of at least 80 and can obtain PCR's greater than 100.

High cleaning silica gel dental abrasive, dentifrices prepared therefrom, and a method for preparing the dental abrasive

Silica compositions for abrasive systems in dentifrice formulations are disclosed. The silica abrasive system comprises (a) silica gels having a median particle size below 7 microns, a pH of from about 6 to about 11 and powder RDA's of from 100 to about 200 and (b) silica gels or precipitates having a median particle size of 7 microns or greater and powder RDA's of from 50 to about 180. Silica (a) is preferably prepared by contacting a hydrous silica gel with an alkaline medium. Dentifrice compositions comprising the abrasive system has an RDA of 150 or less and PCR's of at least 80 and up to about 150, and an REA of less than about 30 (as measured on the IU scale).

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Baltimore, MD, United States of America

Sandra Joan Kempske