Antiperspirant

Abstract: A substantially clear, anhydrous suspension-type antiperspirant product includes an effective amount of an active antiperspirant component in particulate form suspended in an anhydrous vehicle such that there is no significant dissolution of the active antiperspirant ingredient in the vehicle, and the refractive indices of the active antiperspirant component and the vehicle are matched.

Description: This invention relates to antiperspirant compositions and processes for forming antiperspirant compositions, the compositions being usable as antiperspirant products or for the preparation of such products. Antiperspirant products are well-known in the cosmetic art. Such antiperspirant products often contain an active antiperspirant ingredient, e.g., aluminum chlorohydrate and a liquid vehicle, Such an active antiperspirant ingredient is soluble in water and water-based antiperspirant products tend to have objectionable characteristics of wetness and tackiness A gelling agent may be used to provide the antiperspirant product with a solid character. Antiperspirant products of the solid-type are typically used by rubbing an area of the body such as the underarm to apply a layer of the antiperspirant to the skin, which reduces perspiration. It is desirable that antiperspirant products have aesthetic characteristics of smoothness, non-oiliness and non-tackiness, other desirable characteristics include clarity of the antiperspirant product and the absence of any readily visible residue as, e.g., a white layer, on the skin after the antiperspirant is applied. In accordance with the present invention there is provided a substantially clear essentially anhydrous antiperspirant composition comprising an antiperspirant effective amount of an aluminum chlorhydrate or aluminum-zirconium chlorhydrate antiperspirant salt in solid particulate form suspended in an essentially anhydrous vehicle, characterized by said antiperspirant salt being substantially free of opacifying contaminants and the refractive indices of said antiperspirant salt and said vehicle being between 1.46 and 1.56 and substantially matched such that the relative turbidity of said antiperspirant composition is less than 800 FTU. Preferably said refractive indices are matched such that the relative turbidity of the antiperspirant composition is less than 400 FTU. Also provided in accordance with the present invention is a process for making a substantially clear essentially anhydrous antiperspirant composition characterized by comprising the steps of providing an aluminum chlorohydrate or aluminum-zirconium chlorohydrate antiperspirant salt in solid particulate form, said antiperspirant salt being substantially free of opacifying contaminants and having a refractive index between 1.46 and 1.56, providing an essentially anhydrous vehicle with a refractive index between 1.46 and 1.56 that substantially matches the refractive index of said antiperspirant salt such that the relative turbidity of the resulting antiperspirant composition is less than 800 FTU, and suspending an antiperspirant effective amount of said antiperspirant salt in said vehicle. US-A-3 968 203 describes an antiperspirant aerosol comprising an astringent salt suspended in fine powder form in an anhydrous liquid vehicle comprising a propellant. US-A-4 065 564 describes a pump spray or roll-on antiperspirant solution comprising an alcohol soluble aluminum chlorhydroxide complex and a silicone dissolved in an alcohol. EP-A-0 135 315 concerns a cream comprising an antiperspirant and a gelling agent in a silicone carrier. In accordance with one aspect of the invention, there Is provided a substantially clear, essentially anhydrous suspension-type antiperspirant product that includes an effective amount of an active antiperspirant component in particulate form suspended in an anhydrous vehicle such that there is no significant dissolution of the active antiperspirant ingredient in the vehicle and the refractive indices of the active antiperspirant component and the vehicle are substantially matched. While particular antiperspirant products include a sufficient quantity of a gelling agent so that the antiperspirant product can be used as a solid, a reduced amount of, or no, gelling agent may be used if it is desirable to make a more liquid type product. A substantially clear antiperspirant product is one that is visually clear, with a minimal amount of haziness or cloudiness. A transparent antiperspirant solid, like glass, allows ready viewing of objects behind it. By contrast, a translucent antiperspirant solid, although allowing light to pass through, causes the light to be so scattered that it will be impossible to see clearly objects behind the translucent solid. In general, an acceptable translucent to clear antiperspirant product has a turbidity measurement expressed in Nephelometric (or Formazin) Turbidity Units in the range of between about 200 and about 800 FTU, and an antiperspirant product is substantially clear if its relative turbidity measurement is less than 400 FTU. Turbidity measurements discussed hereinafter were made with a Hellige #965 Direct-Reading Turbidimeter. Distilled water has a turbidity of 0 FTU and whole milk diluted one part in 350 parts of distilled water has a turbidity of about 200 FTU. In accordance with another aspect of the invention, the active antiperspirant component is processed prior to incorporation in the antiperspirant product by gentle removal of water without the formation of opacifying contaminants such as aluminum oxide. For example, if the active antiperspirant component contains a contaminant such as aluminum oxide, an insufficiently clear antiperspirant product can result. In one particular method of processing aluminum chlorohydrate without generating opacifying contaminants for use as the active antiperspirant component, water is removed from an aqueous solution of aluminum chlorohydrate by drying the aqueous solution of aluminum chlorohydrate at a temperature less than 40°C, more preferably less than 30°C. The drying preferably is carried out at atmospheric pressure. The resulting glass-like product is then ground into fine (impalpable) particles (typically less than about one hundred microns in size) for use in the antiperspirant product. In another particular method, a container is charged with an aluminum chlorohydrate (ACH) solution such as ACH-303 or Rehydrol II, and a surfactant, such as Oleth-10 or Procetyl AWS, is added. The resulting mixture is then agitated to make a clear solution. Ethanol may be added to facilitate dissolution of the surfactant. Solvent (water) or solvents (water and ethanol) are than removed under vacuum (p>10 mmHg) and elevated temperature (T<50°C). Removal of solvent or solvents continues until the mass of the dried solid indicates a predetermined (by calculation) quantity of solvent or solvents has been removed. The dried solid ACH/surfactant adduct is stored in a sealed container. Antiperspirant components for use in the antiperspirant compositions are well-known aluminum chlorohydrate and aluminum-zirconium chlorohyrate salts, such as are commercially-available as Dow Corning ACH-303 or Rehydrol II (supplied by Reheis Chemical Co.). Further examples of active antiperspirant ingredients that have application to this technology include aluminum sesquichlorohydrate, aluminum dichlorohydrate, aluminum zirconium trichlorohydrate, aluminum zirconium tetrachlorohydrate, aluminum zirconium pentachlorohdyrate and aluminum zirconium octachlorohydrate. The refractive index of the hydrated active ingredient is a function of the amount of associated water in the solid particulate active ingredient. For example, tray-dried aluminum chlorohydrate has a refractive index η D of about 1.51, and the refractive index of less dried aluminum chlorohydrate (alone or in adduct form) can vary to as low as about 1.46 depending upon the dryness (the amount of water associated with the hydrated salt or adduct). Another useful active ingredient is aluminum-zirconium chlorohydrate that has been dried to have a refractive index η D of about 1.56. The amount of associated water in the solid particulate active ingredient may be adjusted in various ways, including, for example, by controlled drying, by storage of the dried active ingredient in a high humidity atmosphere, or by addition of water to the adduct before addition of a gelling agent. The active antiperspirant component(s) should be present in an amount effective to reduce perspiration when applied to the skin. The precise limitt on the amount of active antiperspirant component that can be used will vary with the particular component and formula. As a general rule, however, the antiperspirant product should contain anywhere from about 5% to about 50% (more preferably about 10% to about 30%) of active antiperspirant component in solid particulate form. To provide a substantially clear antiperspirant product, the refractive index (η D ) of the vehicle should be matched to that of the active antiperspirant component. The vehicle generally is a blend of liquids having different refractive indexes. Liquids suitable for use include octylmethoxy cinnamate (η D 1.54), isopropyl myristate (η D 1.43), polyphenylmethylsiloxane liquids as Dow Corning DC-556 (η D 1.46), isoeicosane (Permethyl 102A) fluid (η D 1.44), cinnamic aldehyde (η D 1.62), SD-40 alcohol (η D 1.36), C₁₂₋₁₅ alcohols benzoate (Finsolv TN) (η D 1.48), isoamyl methoxy cinnamate (η D 1.56), and isopropyl palmitate (η D 1.48). The vehicle can also include a surfactant, such as Oleth-10 or PPG-5 Ceteth-20 which helps provide washability, provided it is compatible with other requirements of the system. The vehicle can also contain additional cosmetic ingredients such as emollients, colorants, fragrances, and preservatives, again provided that they are compatible and the resulting refractive index of the vehicle is appropriately adjusted. The components are blended together in appropriate quantities to give a vehicle with an appropriate η D . Most preferably, the η D of the vehicle is virtually identical to that of the active antiperspirant particles. Even when the refractive indices are not identical, however, a substantially clear antiperspirant can be obtained. For example, where the active antiperspirant component is aluminum chlorohydrate (η D is about 1.51), a substantially clear antiperspirant is obtained if the liquid vehicle has an η D between about 1.50 and 1.52; and where the active antiperspirant component is aluminum chlorohydrate (or adduct) with additional associated water (η D is about 1.495), a substantially clear antiperspirant is obtained if the liquid vehicle has an η D between about 1.49 and 1.51. The term "match", as used herein, means the refractive indices are close enough such that an antiperspirant product is obtained that has a turbidity value not in excess of 800 FTU. The gelling agent used in particular antiperspirant products is compatible with the other components, desirably forms a solution with other liquid components, and, in conjunction with other vehicle components, meets the η D requirements for a substantially clear antiperspirant. Examples of suitable gelling agents include polyethylene-vinyl acetate copolymers, polyethylene homopolymers and blends. Allied Corp's grade 6 and 6A homopolymers and 400 and 400A copolymers are preferred gelling agents. It will be apparent that other appropriate gelling agents with suitably matched refractive indices can be used. The amount of gelling agent in the solid antiperspirant product preferably is sufficient to cause the liquid vehicle to gel (i.e., become free-standing). In general, the solid antiperspirant product should include between about 2% and about 50% (more preferably between about 10% and about 35%, most preferably between about 15% and about 30%) of gelling agent. For liquid antiperspirant products, it may be desirable to use some gelling agent in the antiperspirant product for thickening, even though a sufficient quantity of gelling agent is not used to obtain a free-standing composition. In accordance with a further aspect of the invention, care is taken in the blending of components to achieve optimum clarity of a gel antiperspirant product. In making a substantially clear essentially anhydrous antiperspirant product, a gelling agent is dissolved in the vehicle component at a temperature of less than the cloud point of the gelling agent; an active antiperspirant component (directly or in adduct form) is added to the gelling agent-vehicle component, the refractive index of the active antiperspirant component matching that of the gelling agent-vehicle component; and the mixture of the gelling agent-vehicle component and the active antiperspirant component is cooled to provide an antiperspirant product that has a relative turbidity of less than 400 FTU. In preferred embodiments, the active antiperspirant component is aluminum chlorohydrate with a refractive index (depending on the amount of associated water) between about 1.46 and 1.53; and the refractive indices (η D ) of the active antiperspirant component and of the gelling agent-vehicle component are within about 0.02. The process may include the step of adding water to the aluminum salt in solid form to reduce its refractive index without significant dissolution of the solid aluminum salt. In a particular process, an antiperspirant product that includes a polyethylene-vinyl acetate copolymer (AC-400) as a gelling agent is processed as follows: (1) the active antiperspirant component and the polyethylene-vinyl acetate copolymer are added to other vehicle components; (2) the mixture is heated to a temperature below 80°C (preferably between 70°C and 80°C; and most preferably about 75°C) to dissolve the copolymer; and the mixture is cooled. Although the precise technical reason the above process provides an optimally clear solid antiperspirant product is undetermined, it is felt that keeping the highest processing temperature below the cloud point of the gelling agent (a polyethylene-vinyl) acetate copolymer (such as Allied Corp. AC-400A, which has a η D of about 1.497) generally has a cloud point above 80°C, and a polyethylene homopolymer (such as Allied Corp. AC-6A, which has a η D of about 1.51) generally has a cloud point above 95-100°C) provides the clearest antiperspirant product. Heating above the cloud point may cause a change in the structure of the gelling agent which may change the refractive index and result in a hazy antiperspirant product. The following Examples 1-12 illustrate representative antiperspirant products and are given by way of illustration only and are not to be considered as being limiting. The amounts in the Examples and the claims are in weight percent. The following Examples are made by combining and mechanically mixing all the liquid vehicle ingredients until homogeneous and refractive index is adjusted as necessary, for example to 1.5075 where dry aluminum chlorohydrate in adduct form is the antiperspirant product active; to 1.4955 where aluminum chlorohydrate in adduct form contains additional associated water is the antiperspirant product active; and to about 1.56 where aluminum-zirconium chlorohydrate is the antiperspirant product active. The active ingredient is then added, and the mixture is heated from room temperature to 60°C over a period of about one-quarter hour. At 60°C, a gellant (e.g., a polyethylene-vinyl acetate copolymer) (if used) is added and the mixture is continued to be heated to about 75°C (a temperature where the gellant has melted and the mixture appears to be homogeneous). The mixture is held at 75°C for about ten minutes and then deaerated as appropriate and poured into molds. Example 1 Ingredient Percentage Octylmethoxy Cinnamate 50.25 Isopropyl myristate 17.25 Ethanol - 200 proof 2.50 Aluminum chlorohydrate 10.00 Polyethylene/Vinyl Acetate Copolymer 20.00 The resulting composition of Example 1 was a solid and had a measured turbidity of 148 FTU. Example 2 Ingredient Percentage Octylmethoxy Cinnamate 43.50 Isopropyl myristate 14.50 Ethanol - 200 proof 2.50 Aluminum Chlorohydrate 30.00 adduct form Oleth-10 7.50 Polyethylene/Vinyl Acetate Copolymer 2.00 The resulting composition of Example 2 was a viscous fluid and had a measured turbidity of 45 FTU. Example 3 Ingredient Percentage Octylmethoxy Cinnamate 39.75 Isopropyl myristate 12.75 Ethanol - 200 proof 2.50 Aluminum Chlorohydrate 20.00 adduct form Oleth-10 5.0 Polyethylene/Vinyl Acetate Copolymer 20.00 The resulting composition of Example 3 was a solid and had a measured turbidity of 87 FTU. Example 4 Ingredient Percentage Octylmethoxy Cinnamate 34.33 Isopropyl myristate 10.67 Ethanol - 200 proof 2.50 Aluminum Chlorohydrate 30.00 adduct form Oleth-10 7.50 Polyethylene/Vinyl Acetate Copolymer 15.00 The resulting composition of Example 4 was a solid and had a turbidity of 102 FTU. Example 5 Ingredient Percentage Octylmethoxy Cinnamate 24.50 Finsolv TN 18.00 Ethanol - 200 proof 2.50 Aluminum Chlorohydrate 30.00 adduct form Procetyl AWS 10.00 Polyethylene/Vinyl Acetate Copolymer 15.00 The resulting composition of Example 5 was a solid and had a turbidity of 127 FTU. Example 6 Ingredient Percentage Octylmethoxy Cinnamate 13.53 Finsolv TN 44.47 Water (added to the adduct) 2.00 Aluminum Chlorohydrate 15.00 adduct form Procetyl AWS 5.00 Polyethylene/Vinyl Acetate Copolymer 20.00 The resulting composition of Example 6 was a substantially clear solid, had a refractive index of 1.4949, and had a turbidity of 234 FTU. Example 7 Ingredient Percentage Octylmethoxy Cinnamate 27.50 Finsolv TN 20.00 Ethanol - 200 proof 2.50 Aluminum Chlorohydrate 30.00 adduct form Procetyl AWS 5.00 Polyethylene/Vinyl Acetate Copolymer 15.00 The resulting composition of Example 7 was a solid and had a turbidity of 100 FTU. Example 8 Ingredient Percentage Isoamyl Methoxy Cinnamate 30.89 Isopropyl Myristate 11.61 Ethanol - 200 proof 2.50 Isoeicosane 5.00 Aluminum Chlorohydrate 20.00 adduct form Oleth-10 5.00 Stearyl Alcohol 2.00 Polyethylene/Vinyl Acetate Copolymer 23.00 The resulting composition of Example 8 was a solid and had a turbidity of 121 FTU. Example 9 Ingredient Percentage Isoamyl Methoxy Cinnamate 34.14 Isopropyl Myristate 8.36 Ethanol - 200 proof 2.50 Polyphenylmethylsiloxane (DC556) 5.00 Aluminum Chlorohydrate 20.00 adduct form Oleth-10 5.00 Stearyl Alcohol 2.00 Polyethylene/Vinyl Acetate Copolymer (AC400A) 23.00 The resulting composition of Example 9 was a solid and had a turbidity of 156 FTU. Example 10 Ingredient Percentage Octylmethoxy Cinnamate 33.6 Isopropyl Myristate 10.4 Ethanol - 200 proof 2.50 Rehydrol II 30.00 adduct form Oleth-10 7.50 Polyethylene/Vinyl Acetate Copolymer (AC 400A) 16.00 The resulting composition of Example 10 was a solid and had a turbidity Of 56 FTU. Example 11 Ingredient Percentage Isoamyl Methoxy Cinnamate 72.3 Cinnamic Aldehyde 7.7 Aluminum Zirconium Chlorohydrate 20.00 The resulting composition of Example 11 was a liquid and had a turbidity of 450 FTU. Example 12 Ingredient Percentage Octylmethoxy Cinnamate 43.10 Isopropyl Myristate 14.80 Alcohol SD-40 2.10 Aluminum Chlorohydrate 20.00 Polyethylene/Vinyl Acetate Copolymer AC400A 20.00 The resulting composition of Example 12 was a solid and had a turbidity of 290 FTU.

Claims: A substantially clear essentially anhydrous antiperspirant composition comprising an antiperspirant effective amount of an aluminum chlorhydrate or aluminum-zirconium chlorhydrate antiperspirant salt in solid particulate form suspended in an essentially anhydrous vehicle, characterized by said antiperspirant salt being substantially free of opacifying contaminants and the refractive indices of said antiperspirant salt and said vehicle being between 1.46 and 1.56 and substantially matching such that the relative turbidity of said antiperspirant composition is less than 800 FTU. The antiperspirant composition of claim 1 wherein the refractive indices (n D ) of said antiperspirant salt and of said vehicle are matched such that the relative turbidity of said antiperspirant composition is less than 400 FTU. The antiperspirant composition of claim 1 or 2 which includes from 10% to 30% of said antiperspirant salt. An antiperspirant composition according to any one of the preceding claims, wherein said vehicle includes a gelling agent having one or more of the following attributes: (a) said antiperspirant composition includes between 2% and 50% of said gelling agent; (b) said gelling agent is polyethylene polymer such as a polyethylene-vinyl acetate copolymer; (c) said gelling agent is present in sufficient quantity to cause said product to be a free-standing solid; (d) said antiperspirant product includes between 15% and 30% of said gelling agent. A process for making a substantially clear essentially anhydrous antiperspirant composition characterized by comprising the steps of providing an aluminum chlorohydrate or aluminum-zirconium chlorohydrate antiperspirant salt in solid particulate form, said antiperspirant salt being substantially free of opacifying contaminants and having a refractive index between 1.46 and 1.56, providing an essentially anhydrous vehicle with a refractive index between 1.46 and 1.56 that substantially matches the refractive index of said antiperspirant salt such that the relative turbidity of the resulting antiperspirant composition is less than 800 FTU, and suspending an antiperspirant effective amount of said antiperspirant salt in said vehicle. A process according to claim 5, further comprising adding a gelling agent and including one or more of the following: (a) said antiperspirant composition includes between 2% and 50% or between 10% and 35% of said gelling agent and is a free-standing solid; (b) said process comprises the further steps of dissolving said gelling agent in said vehicle at a temperature of less than the cloud point of said gelling agent; (c) the refractive indices (n D ) of said active antiperspirant salt and of said vehicle are matched within about 0.02 such that the relative turbidity of the resulting antiperspirant composition is less than 400 FTU; and/or (d) said gelling agent comprises a polyethylene-vinyl acetate copolymer, and said process further comprises the step of; dissolving said copolymer in said vehicle at a temperature of less than 80°C; adding said antiperspirant salt to said copolymer-vehicle solution, the refractive index of said active antiperspirant component matching that of said vehicle; and cooling the mixture of said vehicle and said antiperspirant salt to provide an antiperspirant composition that has a relative turbidity of less than 800 FTU. A process according to claim 5 or 6, wherein said antiperspirant salt is obtained by the steps of: providing a solution of said antiperspirant salt and a solvent; heating said solution at a low temperature, such as to a temperature of less than 50°C, to evaporate a predetermined amount of said solvent and provide said antiperspirant salt in solid form that is substantially free of opacifying contaminants; and further processing said active antiperspirant salt to provide said antiperspirant salt in solid particulate form. The Process of any one of claims 5 to 7, wherein said solution further contains a surfactant, and said heating step provides an adduct of said antiperspirant salt and said surfactant in solid form that is substantially free of opacifying contaminants. A process according to claim 6, 7 or 8 which comprises the steps of: dissolving a gelling agent in said vehicle at a temperature of less than the cloud point of said gelling agent; combining said antiperspirant salt in solid particulate form with said gelling agent and vehicle, the refractive index of said antiperspirant salt matching that of said gelling agent and vehicle; and cooling the mixture of said gelling agent and vehicle and said antiperspirant salt to provide an antiperspirant composition that has a relative turbidity of less than 400 FTU. A process according to any one of claims 5 to 9, including the step of adding water to said antiperspirant salt in solid form to reduce its refractive index without significant dissolution of said solid active antiperspirant salt.

Inventors: KRAFTON THOMAS J, PHIPPS ALAN M, VU TUAN M, KRAFTON, THOMAS J., PHIPPS, ALAN M., VU, TUAN M.
Applicants: GILLETTE CO, THE GILLETTE COMPANY
Application year: 1990
Main classification: A61K7
IPC codes: A61Q15, A61K8