TRANSPARENT ANTIPERSPIRANT COMPOSITIONS AND METHOD OF PREPARATION

Abstract: The invention relates to compositions for transparent or translucent antiperspirants comprising a polyol, the reaction product of an antiperspirant salt and a silane and an optional gelling agent, but no or substantially no water. When gelled, the composition is suitable for use as a stick antiperspirant. The invention also relates to the process by which compositions of the invention are prepared.

Description: This application relates to compositions of matter which contain antiperspirant salt materials, wherein the compositions are transparent or translucent in appearance, are relatively free of water and are optionally moldable or otherwise shapeable so as to form antiperspirant sticks. It is widely known in the industry that consumers place a high value on personal care materials which are clear or transparent. The perceived value is at least partially attributable to the aesthetic appearance of such materials and also the association in the mind of the consumer of transparency with purity of the product. As a consequence thereof, it is deemed very desirable in the personal care industry to formulate transparent or highly translucent antiperspirant compositions, especially those which can be formed into antiperspirant stick configurations. Forms of transparent antiperspirant salt containing compositions are known in the art. The present invention relates to antiperspirant compositions which contain no or substantially no water and are transparent or highly translucent in appearance. The invention also relates to antiperspirant compositions as described which may be gelled by the addition of a gellant material thereby giving the antiperspirant composition a consistency suitable for forming or molding into a stick configuration. Furthermore, the invention also relates to the method of making the antiperspirant composition of the invention. The antiperspirant composition of the invention comprises: (a) from 5 to 30 wt. percent of the reaction product of: 5 to 15 parts by weight of a conventional antiperspirant salt selected from the group consisting of the hydrated chlorine salts of aluminum, zirconium and zinc, the hydrated bromine salts of aluminum, zirconium and zinc and mixtures thereof and preferably, aluminum chlorhydrate, zirconium chlorhydrate and mixtures thereof; and 1 part by weight of a silane of the general formula: (i) R¹Si(OR²)₃ wherein R¹ represents a member of the group consisting of alkyl groups of from C₂ to C₅ and aryl groups of from C₆ to C₁₈, with a C₃ alkyl group being the most preferable form of R¹ and R² represents an alkyl group of from C₁ to C₅, with C₁ to C₃ being preferable and C₁ being most preferable; (b) from 60 to 95 wt. percent of a polyol having the general formula: (ii) R³ (OH)₂ wherein R³ represents an alkyl group of from C₂ to C₆, with propylene glycol being the most preferred polyol; and optionally (c) from 0.1 to 10 wt. percent of a gellant for said polyol, such as dibenzylidene sorbitol commercially available from Milliken & Co., New York, New York, under the tradename MILLITHIX. The process by which the composition of the invention is 15 prepared comprises the steps of: (i) preparing an aqueous antiperspirant salt solution by dissolving a conventional antiperspirant salt selected from the group consisting of the hydrated chlorine salts of aluminum, zirconium and zinc, the hydrated bromine salts of aluminum, zirconium and zinc and mixtures thereof and preferably aluminum chlorhydrate, zirconium chlorhydrate and mixtures thereof in water; (ii) heating said aqueous antiperspirant salt solution; (iii) adding to the heated aqueous antiperspirant salt solution a mixture of silane: (i) R¹Si(OR²)₃ and polyol: (ii) R³(OH)₂ and; (iv) heating the silane, polyol and antiperspirant salt solution mixture to drive the hydrolysis product of the silane and water and substantially all of the unreacted water therefrom. The resulting material is a thickened transparent antiperspirant fluid which may be used as is and would be highly suitable for use in conjunction with a roll-on applicator, spray applicator or other applicator means for applying a liquid to the human underarm. Optionally, the material may be processed further to thicken the fluid into a gel or gelled-solid consistency, so as to facilitate shaping or otherwise forming the material into a stick configuration. The optional gelling step comprises: (v) adding a gelling agent to the material produced by the previous step, in an amount necessary to achieve the desired gel consistency. If the antiperspirant material is gelled, as in step (v), the material may optionally be formed through conventional shaping, extruding or molding processes into a stick configuration for use as an under-arm stick antiperspirant. Shaping and gelling may even be carried out simultaneously, as in the case of adding the gelling agent while the antiperspirant composition is held in a mold for making antiperspirant sticks. The optional shaping step of the method is as follows: (vi) shaping the gelled antiperspirant material by conventional means for use as a stick antiperspirant. An example of the composition of the invention was prepared as follows: Example 1 25 g of aluminum chlorhydrate were dissolved in 75 g of distilled water. The aqueous aluminum chlorhydrate was then was heated at 70°C. for approximately one hour in a three-neck round-bottom flask, then a mixture of 2.5 g propyltrimethoxy-silane and 75.0 g propylene glycol was added thereto. The contents of the flask were then heated to a temperature of 110°C. for four hours. The vapors released by the heated mixture during this time were drawn off from the flask under vacuum and condensed in a dry-ice condenser tube. By collecting and measuring the output of the water from the condenser tube it was apparent that nearly all of the 75 g of water which made up the aqueous antiperspirant salt solution were driven off through heating. The material remaining in the vessel was a clear, somewhat viscous fluid which was found to be soluble in propylene glycol and apparently insoluble or at least only slightly soluble in water and insoluble in decamethylcyclopentasiloxane. Example 2 10 ml of the antiperspirant fluid obtained in Example 1 were withdrawn from the flask and mixed with 0.2 g of dibenzylidene sorbitol, (MILLITHIX) to form a loose, highly translucent gel. Example 3 To obtain material suitable for forming in a stick configuration, about 5.0 g of a 10 wt. percent solution of MILLITHIX in propylene glycol was mixed with 10 ml of the antiperspirant fluid obtained in Example 1. A very firm gelled stick was formed therefrom and the appearance of which was reported as translucent with a white haze. To test the efficacy of the antiperspirant salt in the stick of Example 3, the antiperspirant stick was rubbed on the inventor's left forearm and then the inventor exercised, to produce bodily perspiration. The inventor noted that during exercise the left forearm on which the antiperspirant stick had been applied was free of perspiration, whereas the right forearm appeared to perspire normally, indicating the efficacy of the antiperspirant material of the invention.

Claims: A transparent antiperspirant composition comprising: (a) from 5 to 30 wt. percent of the reaction product of: 5 to 15 parts by weight of an antiperspirant salt selected from the group consisting of the hydrated chlorine salts of aluminum, zirconium and zinc, the hydrated bromine salts of aluminum, zirconium and zinc and mixtures thereof; and 1 part by weight of a silane of the formula: (i) R¹Si(OR²)₃ wherein R¹ represents a member of the group consisting of alkyl groups of from C₂ to C ₅ and aryl groups of from C₆ to C₁₈ and R² represents an alkyl group of from C₁ to C₅; (b) from 60 to 95 wt. percent of a polyol having the formula: (ii) R³(OH)₂ wherein R³ represents an alkyl group of from C₂ to C₆. A transparent antiperspirant composition as claimed in claim 1, further comprising (c) from 0.1 to 10 wt. percent of a gellant for said polyol. The method of forming the antiperspirant composition as claimed in claim 1, comprising the steps of: (i) preparing an aqueous antiperspirant salt solution by dissolving said antiperspirant salt in water; (ii) heating said aqueous antiperspirant salt solution; (iii) adding to the heated aqueous antiperspirant salt solution a mixture of said silane and said polyol; and (iv) heating the silane, polyol and antiperspirant salt solution mixture to drive the hydrolysis product of the silane and water and substantially all of the unreacted water therefrom. The method of forming the antiperspirant composition as claimed in claim 2, further comprising the step of: (v) adding said gellant in an amount effective to achieve the desired gelled consistency of the composition.

Inventors: WARD, ANDREW HAMILTON
Applicants: DOW CORNING CORPORATION
Application year: 1990
Main classification: A61K7
IPC codes: A61K8, A61Q15