# US 6,294,155 B1 · Abrasive silica compositions and dentifrice compositions prepared therefrom

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 6,294,155 B1
- Document ID: US6294155B1
- Status: Granted
- Kind: B1
- Application number: 09/056,688
- Filed: 1998-04-08
- Granted: 2001-09-25
- Earliest claimed: 1998-04-08
- Assignees: W. R. Grace & Co.-Conn.
- Inventors: Michael Bruce Thomas; Michael Vance Ernest; Sandra Joan Kempske
- Web page: https://patentgrep.com/patent/US6294155B1

## CPC

- A61K 8/25: Silicon; Compounds thereof
- A61Q 11/00: Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
- A61K 2800/412: Microsized, i.e. having sizes between 0.1 and 100 microns
- A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D)
- A61Q: SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS

## Abstract

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).

## Claims

### Claim 1

A dentifrice composition comprising humectant and a silica abrasive system, said abrasive system comprising
(a) silica gel (i) having a median particle size below about 7 micron, (ii) a pH of from about 6 to about 11, and (iii) a hardness defined by a powder RDA of 100 to 200, and a PCR of 100 to about 150 when said silica (a) is formulated by itself into a dentifrice paste; and
(b) silica gel or precipitate having a median particle size of about 7 microns or greater and having a hardness defined by a powder RDA of about 50 to 180 and a PCR of about 80 to about 105 when said silica (b) is formulated by itself into a dentifrice paste;
wherein particle sizes are determined by laser diffraction and further wherein the weight ratio of (b) to (a) is at least 1:1, and the dentifrice composition comprising (a) and (b) has an RDA of about 150 or below, and a PCR of at least 80, and up to about 150, and an REA of less than about 30, as measured on the IU scale.

### Claim 2 (depends on 1)

A dentifrice composition of claim 1 wherein silica gel (a) has a median particle size of less than 4 microns.

### Claim 3 (depends on 1)

A dentifrice composition of claim 1 wherein the composition has an REA of less than 10.

### Claim 4 (depends on 1)

A dentifrice composition of claim 1 wherein silica gel (a) is hydrous silica gel with a pH of from about 7.5 to about 10.5 as measured in an aqueous slurry containing 5% by weight silica.

### Claim 5 (depends on 1)

A dentifrice composition of claim 1 wherein the silica gel (a) is prepared by contacting a hydrous gel with an alkaline medium.

### Claim 6 (depends on 4)

A dentifrice composition of claim 4 wherein the silica gel (a) is prepared by contacting a hydrous gel with sodium carbonate.

### Claim 7 (depends on 2)

A dentifrice composition of claim 2 wherein silica gel or precipitate (b) has a median particle size of at least 12 microns.

### Claim 8 (depends on 7)

A dentifrice composition of claim 7 wherein the weight ratio of (b) to (a) is at least 2:1.

### Claim 9 (depends on 1)

A dentifrice composition of claim 1 wherein silica gel (a) has a total volatiles content in the range of about 5-30% by weight of silica gel (a).

### Claim 10 (depends on 4)

A dentifrice composition of claim 4 wherein the median particle size of silica gel (a) is less than 4 microns, the median particle size of silica gel or precipitate (b) is at least 12 microns and the weight ratio of (b) to (a) is at least 2:1.

### Claim 11 (depends on 1)

A dentifrice composition of claim 1 wherein the silica abrasive system comprises about 5 to about 50% by weight of the total dentifrice composition.