Personal care compositions with zinc phosphate active

Abstract

A personal care composition, comprising a soluble zinc polyphosphate complex made by combining ingredients comprising an inorganic zinc salt, a plurality of long chain polyphosphates having 6 or more phosphate polymer units, and an aqueous solvent; wherein the relative amount of inorganic zinc salt and long chain polyphosphates provides a phosphorus to zinc mole ratio of at least 6:1. Also, a method of using the composition for reducing at least one of perspiration or body odor.

Claims

1. A personal care composition, comprising: a soluble zinc polyphosphate complex made by combining ingredients comprising zinc chloride and sodium hexametaphosphate; wherein the relative amount of the zinc chloride and sodium hexametaphosphate provides a phosphorus to zinc mole ratio of 20:1, and wherein the composition is an antiperspirant for application to the skin; wherein upon use and contact with proteins in sweat, the soluble zinc polyphosphate complex forms a precipitate which occludes sweat ducts.

2. The personal care composition of claim 1, wherein the zinc polyphosphate complex has an average of about 1 zinc atom.

Description

EXAMPLES

Examples 1 to 4

(1) Soluble zinc polyphosphate complex was made by combining 1.277 grams of ZnCl.sub.2, 20.972 grams of SHMP and 82.906 grams of water in a batch solution. Four samples were made from the batch solution, which are numbered as examples 1 to 4 in Table 2.

(2) TABLE-US-00001 TABLE 2 Example ZnCl2 + SHMP BSA No. solution (g) (g) 1. (pH control) 5 0 2. (pH raised) 5 0 3. (1% BSA, 4.6769 0.0471 37° C.) 4. (1% BSA, 3.874 0.039 RT)

(3) The pH of Example 2 was carefully adjusted from a pH of 4.1 to a pH of 6.2 using dilute NaOH, at which point precipitate formed. However when the precipitated Example 2 had its pH lowered from 6.2 to 5.13 by adding HCl, the precipitates dissolved and the sample became clear again.

(4) BSA protein was added to the formulations of Examples 3 and 4. White precipitate formed immediately in both, Example 3 was then aged at 37° C. for 1 hour. Example 4 was aged at room temperature for 1 hour. Precipitate increased in both example formulations with aging. Based on the color of the solutions, the precipitate increased more in the heated Example 3. The formation of the precipitate indicates that the zinc polyphosphate made using the zinc chloride and SHMP would be suitable for treating dentinal hypersensitivity.

Example 5

(5) The acid resistance of the precipitates was tested by adding dilute HCL to the Example 3 formulation to lower the pH from 4.17 to 1.99. The extent of whiteness of the sample appeared to increase slightly, but overall the precipitate remained stable as the pH was lowered. Because the precipitate did not dissolve at low pH, the test showed that the zinc polyphosphate precipitate is acid resistant in the presence of the BSA protein.

Example 6

(6) A clear mixture of ZnCl.sub.2, SHMP and water from the same batch as Example 1 was freeze dried. A white powder resulted. The ability of the solution to be freeze dried into powder indicates that the complex can be used in both liquid and solid phase.

(7) The above data from the examples indicates that the soluble zinc phosphate mixture can potentially be used in formulations for sensitive teeth. At a certain molar ratio (approximately 20P:1Zn), soluble zinc polyphosphate solution can be obtained. When this soluble solution is mixed with BSA protein, it quickly starts to precipitate and is ready to treat dentinal tubules, in addition, Zn.sup.2+ will hydrolyze to amorphous zinc hydroxide at a pH of above 5.5, such as about 7.0 to about 7.4 to physically block the dentinal tubules. Increased precipitate may form at the higher pH range of 7.0 to 7.4 as compared with the lower pH range.

(8) Other experiments using an organic zinc reagent and SHMP showed that when a mole ratio of P:Zn is 6.1 or more, such as about 15:1 to about 25:1 or about 20:1 to about 23:1, a soluble zinc polyphosphate complex is formed and the solution becomes clear.

(9) In summary, the soluble zinc polyphosphate complex of the present disclosure can precipitate at high pH and/or in the presence of protein (e.g., such as found in saliva) and thus can be applied to occlude dentinal tubules to provide dentinal hypersensitivity relief. Further, BSA in the above experiments simulates sweat proteins. Based on the data, it is believed that the complexes of the present disclosure can diffuse into sweat glands and precipitate in combination with protein to block the sweat ducts of a user, thereby preventing or reducing the amount of sweat coming out of the skin when used as an active ingredient in antiperspirants. In essence, the solubility characteristics of the zinc complex allows it: to readily diffuse into dentin tubules or sweat glands and precipitate, thereby blocking the tubules or glands. The solubility can also allow formulation into liquid products, such as mouthwash. Additionally, the soluble Zinc complex can potentially be used to make transparent products.