GB2299507A - Antiperspirant aerosol composition - Google Patents

Abstract

A packaged suspension antiperspirant aerosol composition suitable for topical application to the human skin, the composition comprising 10-30% by weight of an antiperspirant active material, 5-50% of a liquid emollient carrier, and less than 60% by weight of a propellant for expelling the composition from a container, the package being adapted to spray at an initial spray rate of no more than 0.5g/s, the composition additionally comprising 0.1-3% of a non-volatile liquid comprising a non volatile silicone or an oil soluble emulsifier.

Description

ANTIPERSPIRANT AEROSOL COMPOSITION This invention relates to aerosol antiperspirant compositions suitable for topical application to the human skin. In particular, the invention relates to low flow rate propellant driven antiperspirant compositions of the powder suspension type suitable for spraying from a pressurized aerosol container.

Antiperspirant compositions suitable for topical application typically contain an astringent material, such as aluminum chlorhydrate, which acts to suppress the level of sweating on the area of the body to which it is applied. A popular form of application of such products is using a pressurised propellant driven aerosol spray.

Such aerosol antiperspirant compositions typically have the astringent material suspended in an anhydrous vehicle together with a propellant and usually with a suspending agent, along with other more minor ingredients, in a pressurised container.

However, conventional aerosol antiperspirant compositions have several problems associated with them. Firstly, they tend to utilise a large amount of propellant gas. This feature of them is undesirable, since fluorocarbon propellants are widely believed to have undesirable effects in the environment. Hydrocarbon propellants, which are commonly used as an alternative, are flammable, and as such their presence needs to be minimized to prevent fire risk.

Attempts have been made to reduce the amount of propellant used in aerosol antiperspirant compositions, by reducing the volume and flow rate of the product in use. By doing this, the amount of propellant released into the atmosphere is reduced. However, a problem with this approach is that by doing this, the effective concentration of the material being sprayed typically increases, for a given duration of spraying. Since aerosol antiperspirant compositions typically contain a dry powder solid (i.e. the antiperspirant astringent), there is a tendency for the antiperspirant astringent material to clog the aerosol valve or spray button used in the product.This problem is exaggerated for low flow rate products, as not only is there a higher concentration of powder being sprayed, but also the reduced flow rate leads to a lower volume of gas being discharged in a set period of time, thereby providing less energy to remove any constrictions in the product hardware.

EP 570 085 (Colgate Palmolive) addresses this same technical problem. It alleges to overcome the problem by providing an aerosol antiperspirant composition having a low level of volatile organic compounds (less than 60% by weight), in conjunction with a particulate antiperspirant material and an optional particulate filler, such as chemically modified corn starch, micronized polyethylene, cross-linked polyurethanes, polyacrylates, talc, sodium bicarbonate, corn starch, or combinations thereof. Along with other compositional restrictions, the composition comprises 10-35% of particulate material, of which 25-100% by weight is a particulate antiperspirant active material, and 0-75% by weight is the particulate filler material.The general teaching of this application is that in compositions containing low levels of volatile organic compounds (i.e. including low levels of propellant), a general increase in the level of solid material in the composition prevents or reduces valve clogging.

In the same technical field but addressing a different technical problem, US4,053,581, US4,073,880, and US4,065,565 all relate to a solution antiperspirant containing no suspended material, the composition comprising non-volatile siloxane liquid, volatile polydimethyl siloxane liquid, and an alcoholic solution of aluminium chlorhydroxide complex.

The siloxanes are alleged to reduce the tackiness of the aluminium complex during drying, and also reduce clogging of the pump spray valve.

We have surprisingly found that by including small amounts of certain non-volatile liquids, optionally in conjunction with certain levels of volatile liquids, in a formulation for use as a low flow rate propellant driven suspension aerosol composition, containing lower than normal levels of propellant gas, it may be possible to reduce the amount of blockage that is observed at the outlet nozzle of the propellant driven aerosol in use.

Thus, according to a first aspect of the invention, there is provided a packaged suspension antiperspirant aerosol composition suitable for topical application to the human skin, the composition comprising 10-30% by weight of an antiperspirant active material, 5-50% of a liquid emollient carrier, and less than 60% by weight of a propellant for expelling the composition from a container, the package being adapted to spray at an initial rate of no more than 0.5g/s, the composition additionally comprising 0.1-3% of a nonvolatile liquid comprising a non volatile silicone or an oil soluble emulsifier.

The initial flow rate of packaged compositions according to the invention is 0.2-0.5g/s, more preferably 0.4-0.5g/s.

According to a further aspect of the invention, there is provided a method of reducing the blockage of a dispensing nozzle on a propellant driven aerosol package containing an antiperspirant composition, comprising incorporating in the antiperspirant composition 0.1-38 by weight of a non-volatile liquid comprising a non-volatile silicone, or an oil soluble emulsifier.

The non-volatile fluids for use in compositions according to the invention include non-volatile silicones, such as polydimethyl siloxane (eg high molecular weight DC200, ex Dow Corning), polyalkyl siloxanes, polyether siloxane copolymers, and polyalkylaryl siloxanes. Preferred non-volatile silicones typically have viscosities in the region 5-2,500,000 cSt at 25 C. Alternatively the non volatile fluid may comprise oil soluble emulsifiers, such as Q2 5097 (ex. Dow Corning), DC193 (ex. Dow Corning), and Span 85 (ex. Atlas).

The inclusion of such fluids at the level taught has been found to be particularly effective at preventing nozzle blockage in propellant driven aerosol compositions, particularly those which have a relatively low propellant content (i.e. less than 60% by weight of the total composition), and also those where the flow rate of the composition from the package is also relatively low, i.e.

less than 0.5g/s.

As is known in the art of aerosol antiperspirant compositions, the particulate material can be suspended in a hydrophobic emollient liquid carrier. The emollient liquid carrier improves initial adhesion of the suspended powders to the skin, thus aiding in the capture of the antiperspirant material by the skin as it is dispensed in spray form. Also, the carrier serves as a diluent, lubricant or spreading agent to facilitate uniform distribution of the antiperspirant material on the skin. Suitable emollient liquid carriers are disclosed in US Patents Nos. 4,822,596 and 4,904,463, the disclosures of which are specifically incorporated by reference herein. The amount of emollient liquid carrier in the composition according to the invention may preferably vary from 5-50% by weight of the total composition.

In a further preferred aspect of the invention, the liquid emollient carrier element of the composition comprises 3-30% by weight of the total composition of a volatile silicone fluid. Preferred volatile fluids for use in compositions according to the invention include dimethyl cyclosiloxanes, such as DC244, DC245, DC344 and DC345 fluids (Dow Corning).

In order to prevent caking or settling out of the astringent salt in the hydrophobic emollient liquid carrier, a bulking or suspending agent may be incorporated in the composition of the invention. The suspending agent assists in filling the void space between suspended particles. The suspending agent is preferably a hydrophobically treated montmorillonite clays such as bentonites and hectorites. The hectorite and bentonite clays used in the invention have a layered clay structure which expands or swells on contact with water. One such commercially available clay is Bentone-38, which is a hectorite clay available from NL Industries, Inc. The amount of clay in the composition of the invention may preferably vary from 0.2-5.0% by weight of the total composition. At levels of clay above 5%, it is found that the composition is too thick to spray satisfactorily.In addition, the concentrate is too thick to conveniently manufacture at clay levels about 5%.

The propellant gas according to the invention can be any liquefiable gas known in the art for use in propellant driven aerosol containers. Examples of suitable propellants include trichlorofluoromethane, trichlorotrifluoromethane, trichlorotetrafluoromethane, monochlorodifluoromethane, difluoroethane, propane, butane or isobutane used singly or in combination. The amount of propellant in the composition of the invention is conveniently no more than 60 wt%.

Ingredients which can be present in compositions according to the invention include: - cosmetically acceptable vehicles, such as straight and branched chain alcohols, for example, ethanol, isobutanol or isopropanol; - deodorant active perfumes and deodorant compounds which can act as antimicrobial agents; - hydrophobic oils, such as liquid paraffin oils; - inorganic electrolytes, such as sodium chloride or sodium sulphate; - thickeners such as clays, for example, Bentone 38, silicas, for example, Aerosil 200 and hydroxypropyl celluloses such as Klucel; - skin feel improvers, such as talc and finely divided polyethylene, an example of which is Acumist B18; - humectants, such as polyols, for example glycerol; - water; - perfumes; - preservatives and antioxidants; - skin benefit agents, such as allantoin; - colours;; - other cosmetic adjuncts conventionally employed in propellant driven aerosol products.

Examples The invention will now be further described by way of example only. The following compositions were prepared, using standard techniques known in the art. For the formulations containing Bentone, it was necessary to shear the Bentone into an aliquot of the liquid emollient, at a high rate of shear (e.g. at approximately 75% of the maximum speed of an "Ultraturrax" mixer) for at least 5 minutes at a temperature of at least 450C, before cooling the mixture and adding the remainder of the components of the composition.

Comsosltlons Packaged propellant driven aerosol antiperspirant compositions were prepared which contained 55 by weight CAP 30 propellant, and 45% by weight of a base composition. The base composition in turn comprised 40% activated aluminium chlorohydrate (ex. Guilini), 4% by weight Bentone 38, 2.2% perfume, and varying amounts of non-volatile fluid for inclusion in the packaged composition. The balance of the base composition was volatile silicone (DC Q2/1465, ex. Dow Corning) The resulting packaged test compositions contained 1% by weight of the total packaged composition (including propellant) of Q2 5097 (ex. Dow Corning), 1% by weight DC 193 (silicone surfactant, ex. Dow Corning), 1% by weight Span 85 (sorbitan ester, ex. Atlas), and 0.1% Span 85. The control contained no non-volatile fluid.

The compositions were packaged in an aluminium can, ex.

Coster, having a volume of 75ml, and an initial flow rate of 0.5g/s.

The valve system used was made by Precision Valve, with key orifice dimensions of; inch x 10-3 stem orifice diameter 24 restricted tail piece 50 diameter vapour phase tap 40 terminal orifice (actuator) 18 The packaged compositions were subjected to a spray down routine which involved twice daily spraying of a number of samples of each packaged composition. The cans were sprayed either until they were empty, or they blocked.

At the end of the test, the control compositions had shown a 10% blockage rate whereas the compositions containing 1% of the volatile fluids described showed no incidence of blocking. The compositions containing 0.1% Span 85 showed a 10% incidence of blocking, but with an overall level of nozzle spray chamber residue which was lower than that found in the control compositions.

Claims (5)

1. A packaged suspension antiperspirant aerosol composition suitable for topical application to the human skin, the composition comprising 10-30% by weight of an antiperspirant active material, 5-50% of a liquid emollient carrier, and less than 60% by weight of a propellant for expelling the composition from a container, the package being adapted to spray at an initial spray rate of no more than 0.5g/s, the composition additionally comprising 0.1-3% of a non volatile liquid comprising a non volatile silicone or an oil soluble emulsifier.

2. A packaged suspension antiperspirant aerosol composition according to claim 1, wherein the liquid emollient carrier comprises 3-30% by weight of the total composition of a volatile silicone material.

3. A method of reducing the blockage of a dispensing nozzle on a propellant driven aerosol package containing an antiperspirant composition, comprising incorporating in the antiperspirant composition 0.1-3% by weight of a non-volatile liquid comprising a non-volatile silicone, or an oil soluble emulsifier.

4. A method according to claim 3, wherein the package has an initial flow rate of 0.4-0.5g/s.

5. A method according to claim 3 or claim 4, wherein the packaged antiperspirant aerosol composition contains less than 60% by weight of the packaged composition of a propellant gas.