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US 5,651,958 AGranted
Dentifrice compositions
AssigneeThe Procter & Gamble Company
InventorDavid Earl Rice
Life of this patent
Estimating the term…
Abstract
Oral compositions, such as oral gels and toothpastes, containing a novel abrasive.
Claims18
An amorphous silica abrasive composition comprising:
- a. a precipitated silica, said precipitated silica being a low structure precipitated silica having a narrow particle size range distribution of soft particles and having a mean value (MV) particle size ranging from 8 to 14 microns, an oil absorption ranging from 60 to 120 cc/100 g, and a mercury intrusion (HGI) void volume of 1.0 to 4.0 cc/g;
- said precipitated silica, when formulated into a dentifrice, having a Pellicle Cleaning Ratio (PCR) of from 70 140 and a Radioactive Dentin Abrasion (RDA) value of from 60 to 130;
- and wherein the ratio of said PCR to said RDA is at least 1.1;
- and wherein, as the particle size in microns increases in said silica, the RDA value remains substantially constant;
- and
- b. a gel silica comprising particles wherein at least about 70% of all of said particles have a diameter of below about 25 microns and wherein the pellicle cleaning ratio is from about 90 to about 135 and the radioactive dentin abrasion is from about 60 to about 100 with a pellicle cleaning ratio/radioactive dentin abrasion ratio of from about 1.20 to about 1.60 and wherein the ratio of precipitated silica to gel silica is from about 90:10 to about 60:40, respectively.
3 more elements
A dentifrice composition comprising the steps of:
- a. a precipitated silica, wherein said silica is prepared by the following steps:
- i) providing an aqueous solution of sodium silicate having a concentration of about 8.0 to 35 weight percent, and an Na.sub.2 O:SiO.sub.2 ratio of about 1 to 3.5:1;
- ii) providing a sulfuric acid aqueous solution having a concentration of about 6 to 35 percent;
- iii) charging to a reactor about 1 to 5 percent of the stoichiometric amount of said sodium silicate solution with agitation;
- iv) heating said solution of said sodium silicate to a temperature in the range of about 80.degree. to 90.degree. C.;
- v) slowly adding to said reactor, sulfuric acid and the remainder of said sodium silicate solution, said addition being conducted over a period of time wherein the sodium silicate is metered into the reaction mixture at the rate of about 7 to 12 liters per minute and the sulfuric acid is metered into the reactor at the rate of about 1 to 4 liters per minute;
- vi) continuing the addition of sodium silicate and sulfuric acid to said reactor over an addition time of about 40 to 60 minutes;
- vii) stopping the sodium silicate solution addition but continuing the sulfuric acid solution addition with agitation until a final pH of 5.0 to 5.8 is obtained in the reactor to provide a precipitated silica in the reaction liquor;
- viii) raising the temperature of said reaction mixture to a temperature of about 90.degree. to 98.degree. C. for a time of about 10 minutes to 1 hour while continuing agitation;
- and
- ix) curing the reaction mixture by boiling said mixture for a period of at least about 30 minutes to two hours to cause formation of substantially uniform particle size precipitated silica;
- x) cooling the reaction mixture and recovering the precipitated silica;
- and
- b. from about 0.1% to about 99% of an orally-acceptable dentifrice carrier.
11 more elements
Dependencies are inferred from the claim text.