ANTIPERSPIRANTS

Abstract: Gelation of aqueous solutions and especially aqueous alcoholic solutions of the more active antiperspirant ac­ tive compounds described in German patent application 2 700 711 and comprising a basic aluminium chloride, bromide, iodide or nitrate having an aluminium to chloride, bromide, iodide or nitrate molar ratio of from 6.5 to 1.3:1 and which compound forms in water a solution contain­ ing polymeric species of a size greater than 100 Angstroms within which species there is contained from 2 to 80% by weight of the total aluminium, is inhibited by including urea in the solution.

Description: ANTIPERSPIRANTS This invention relates to antiperspirant compositions. For inhibiting perspiration, the application to the skin of many different antiperspirant active compounds has been described in the literature. However, those compounds most widely used in commercial products at the present time are basic aluminium halides, especially aluminium chlorhydrate, which has an Al/Cl molar ratio of about 2. These active compounds are applied to the skin from a variety of applicator types including aerosol sprays, pump sprays, squeeze packs, roll-ons and stick applicators. Thus aluminium chlorhydrate, for examples is employed as the active ingredient of various liquid, cream, stick or dry powder antiperspirant compositions. However, in spite of the popularity of aluminium chlorhydrate the presently available products are capable of producing only limited reduction in perspiration. In our German patent application P 27 00 711.0, incorporated herein by reference, and referred to hereinafter as the first application, there is described an improved antiperspirant active compound which comprises a basic aluminium chloride, bromide, iodide and nitrate having an aluminium to chloride, bromide, iodide or nitrate molar ratio of from 6.5 to 1.3:1, and which compound forms in water a solution containing polymeric species of a size greater than 100 Angstroms within which species there is contained at least 2% by weight of the total aluminium. Since in aqueous solutions of the basic aluminium compounds the halide or nitrate is in ionic form the polymeric species present are hydroxyaluminium species. The antiperspirant active compound may be employed in the form of an aqueous solution or the solution may be spray dried to give a hydrated compound of the empirical formula: Al2 (OH)aXaflHO where x is Cl, Br, I or N03, a is from about 0.3 to 1.5 and n is from about 0.3 to 8. As described in said first application, these special forms of basic aluminium compounds which in aqueous solution contain polymeric species having a size greater than 100 Angstroms within which at least 2% by weight of the total aluminium is contained, may be prepared by heating aqueous solutions of basic aluminium compounds at elevated temperature. The production of the desired species depends on the appropriate choice of the reaction conditions which are interrelated. It is preferred to use temperatures of from 800C to 1400C, The period of heating may be shorter as higher temperatures are used, ranging for example from 0.5 hour to 30 days. Of importance is the concentration of the basic aluminium compound starting material. The rate of production of the higher polymeric species of the basic aluminium compound decreases as the concentration of the solution is increased and at the above temperatures the concentration should be no more than about 35% by weight. In our German patent application P 28 18 321.3 and referred to herein as the second application, we have described an improvement in aqueous solutions of the antiperspirant agents bf the first application. This improvement consisted in the inclusion in the solution of a neutral amino acid, by which was meant an amino acid containing an equal number of unneutralised amino and acidic groups. By the inclusion of the amino acid reduction of solution viscosity is effected and gelling inhibited, particularly of aqueous alcoholic solutions. We have now found that these advantages can also be obtained through the inclusion of urea in the solution. According to the present invention therefore there is provided an antiperspirant composition comprising an aqueous solution of a basic aluminium chloride, bromide, iodide or nitrate having an aluminium to chloride, bromide, iodide or nitrate molar ratio of from 6.5 to 1.3:1 which solution contains polymeric hydroxyaluminium species of a size greater than 100 Angstroms within which there is contained from 2 to 80% by weight of the total aluminium, and which solution also contains urea as a gelation inhibitor. The amount of the urea included in the aqueous solution, which may be an aqueous alcoholic solution, of the basic aluminium compound is preferably such that the aluminium to urea molar ratio is from 20:1 to 1:10. The amount of urea necessary to substantially inhibit gelation will depend on the concentration of the basic aluminium compound in the solution and on the amount of any alcohol present, the higher concentrations of the basic aluminium compound and/or alcohol requiring the use of éater amounts of urea. The basic aluminium compound preferably has an aluminium to chloride, bromide, iodide or nitrate molar ratio of from 4 to 1.3:1, more particularly to 2.5 to 1.6:1. The weight of the aluminium in the species having an effective diameter above 100 Angstroms is preferably from 5 to 60% of the total aluminium, The aqueous solution of the active antiperspirant agent comprising the higher polymeric species as defined, may, if desired, be evaporated to concentrate the solution or it may be dried to give a solid hydrated material. As with ordinary aluminium chlorhydrate, for example, drying conditions which lead to both the loss of water of condensation and hydrochloric acid should be avoided as these may lead to irreversible degradation of the basic aluminium compound. Any suitable method of drying may be used, spray drying being a particularly useful method. The spray drying method described in US Patent No. 3,887,692 may be employed. The solid material may be ground or milled as required. Drying should be effected in such manner as to give a product having a water content consistent with the following empirical formula: A12(0H)6 aXa.nz2o. (Urea)m where X is C1, Br, I or NO3, a is from about 0.31 to 1.5, n is from about 0.3 to 8, preferably 0.3 to 4, and m indicates the amount of urea and is preferably about 0.1 to 20. The compositions of the invention may be made by dissolving the urea in the solution of the basic aluminium compound containing the polymeric species greater than 100 Angstroms prepared as described in the first application referred to above. Alternatively the urea may be included in a solution made up from the powder obtained by drying the solution prepared according to the said first application referred to above. A further method is by dissolving the solid, urea-containing antiperspirant compounds described in the preceding paragraph in water or a wateralcohol mixture. The compositions of the invention comprising the basic aluminium compound and urea may contain up to 75% by weight of a C1-C3 aliphatic alcohol. These aqueous alcoholic compositions preferably contain ethanol, propanol, isopropanol or a mixture thereof as the alcohol. The basic aluminium compound is desirably present in the aqueous or aqueous alcoholic solution in a concentration within the range 1 to 25% by weight. The antiperspirant composition of the invention may be applied to the skin in various known ways. Thus the aqueous solution may be applied from a pump spray applicator or from a roll-ball applicator. Conventional ingredients may be included in such compositions, for example, perfume (usually from 0.1 to 2% by weight) or thickener (usually 0.1 to 5% by weight). The following Examples illustrate the invention. Percentages are by weight. Examples 1 and 2 A spray dried antiperspirant powder was made according to Example 2 of the first application referred to above. Aqueous alcoholic solutions of this material and urea were made up. They were prepared by mixing ethanol with the powder to form a slurry to which was added the urea followed by the water. The amounts of the ingredients used are indicated below. Example 1 Example 2 % % Antiperspirant powder 10 15 Ethanol 40 30 Urea 15 10 Distilled water 35 45 In each case the urea prevented gelation of'the solution. Example 3 An aqueous solution of the antiperspirant material used in Examples 1 and 2 was made by dissolving 15 parts of urea in 65 parts of water after which 20 parts of the antiperspirant powder were stirred in. The urea prevented gelation of the solution. Example 4 120 g of urea were dissolved in 2 kg of the treated solution made according to Example 9 of the first application referred to above. The solution was dried in a cocurrent spray drier using inlet and outlet temperatures of 2500C and 95 G, respectively. The resulting powder had the following empirical formula: 2 (0R)5.l Cl0.9 (H20)0.4. (urrea) A further sample of the treated solution to which no urea had been added was similarly spray dried to give a powder having the empirical formula: A12 (OH)5.l Cl0.9 (H20)l.5 Solutions of these powders in aqueous alcohol having the same aluminium concentration were prepared from the following ingredients: : Powder containing urea 20 - Powder not containing urea - 15 Water 60 65 Ethanol 20 20 The solutions were prepared by mixing the ethanol with the respective powder to form a slurry to which was added -e fater. Stirring was nalntained throughout the process The solution obtained using the powder containing urea showed no sign of gel formation after 1 week whereas the other solution had gelled.

Claims: CLAIMS: 1. An antiperspirant composition comprising an aqueous solution of a basic aluminium chloride, bromide, iodide or nitrate having an aluminium to chloride, bromide, iodide or nitrate molar ratio of from 6.5 to 1.3:1 which solution contains polymeric hydroxyaluminium species of a size greater than 100 Angstroms within which there is contained from 2 to 80% by weight of the total aluminium, and which solution also contains urea as a gelation inhibitor. 2. An antiperspirant composition as claimed in claim 1 wherein the amount of urea is such that the aluminium to urea molar ratio is from 20:1 to 1:10. 3. An antiperspirant composition as claimed in claim 1 or claim 2 wherein the solution is an aqueous alcoholic solution comprising a C1- C3 aliphatic alcohol in an amount up to 75% by weight. 4. An antiperspirant composition as claimed in any of the preceding claims comprising from 1 to 25% by weight of the basic aluminium compound. 5. A solid antiperspirant composition produced by drying the aqueous composition claimed in claim 1 or claim 2 and having the empirical formula: A12(OH) aXa.nz2o. (Urea)m where X is C1, Br, I or NO3, a is from 0.31 to 1.5, n is from 0.3 to 8, and m indicates the amount of urea.

Inventors: PIKE, BARRY GRAHAM
Applicants: UNILEVER NV, UNILEVER PLC
Application year: 1979
Main classification: A61K7
IPC codes: A61K8, A61Q15