GB2296189A - Aerosol antiperspirants - Google Patents

Abstract

Antiperspirant aerosols comprise 10-35% by weight of an antiperspirant material 5-50% of a liquid emollient carrier, a propellant in amounts of no more than 60% by weight of the composition and 0.1% to 4% of particulate filler. Valve clogging of the aerosol dispenser is alleviated by presence of filler. Typical fillers are talcs, starches, micronised polyethylene, polyurethane and/or polyacrylates, NaHCO3, "Acumist" or "Dry Flo". Emollient is e.g. a volatile silicone such as cyclomethicone.

Description

ANTIPERSPIRANT AEROSOL COMPOSITION This invention relates to aerosol antiperspirant composition suitable for topical application to the human skin. In particular, the invention relates to an antiperspirant composition 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 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 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 is desirably 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. Of the examples quoted in this application, examples 1-5 exemplify a level of 9.09% by weight of the total composition of particulate filler.

Example 6 exemplifies a level of 4.5% by weight of the total composition of particulate filler.

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. Although the claims of this application cover compositions containing no particulate filler, no such compositions are exemplified.

We have surprisingly found that very low levels of particulate filler in an aerosol antiperspirant composition, generally within the broad ranges quoted in the Colgate patent, but below the levels of particulate filler exemplified, provide remarkably good prevention of valve clogging.

Thus, according to a first aspect of the invention, there is provided an antiperspirant aerosol composition suitable for topical application to the human skin, comprising 10-25% by weight of an antiperspirant active material, 5-50% by weight of a liquid emollient carrier, and a propellant for expelling these components from a container, wherein the propellant makes up no more than 60% by weight of the composition, the composition additionally comprising at least 0.1%, at most 4%, but preferably less than 4% by weight of the total composition of an inert particulate filler material.

Preferably, the particulate material is present in the composition at a level of 0.5-2.5% by weight, more preferably 1-2.5% by weight of the composition.

Compositions which comply with the general criteria recited above and containing less than 4% by weight of inert particulate filler have been found to have surprisingly good properties in terms of the prevention of aerosol blockage.

Indeed, and surprisingly in the light of EP 570085 discussed above, compositions containing 2.5% or less inert particulate filler have been found to be less prone to nozzle blockage than other compositions containing higher levels of inert filler, in the range 6-88 by weight of the total composition.

In a preferred embodiment of the invention, the inert filler material may comprise talc, chemically modified corn starch, non-reactive polymers such as micronized polyethylene (eg Acumist, ex. Allied Corporation), polyacrylates or crosslinked polyurethanes, or combinations thereof. Hydrophilic powders such as sodium bicarbonate, corn starch and vegetable derived starches can also be used. A preferred inert filler material is Dry Flo, aluminium starch octyenyl succinate, a modified corn starch, available from the National Starch and Chemical Corporation, USA.

It is a highly preferred aspect of the invention that the aerosol composition is packaged so as to have a flow rate of less than 0.8 g/s, more preferably less than 0.5 g/s, and in some embodiments preferably less than 0.3g/s. It is also highly preferred that the amount of solid in the composition totals less than 26% by weight of the total composition. It is also desirable that the package for the composition has a volume of less than 100ml, for example a volume in the region 65-85 ml, which allows the packaged composition to be small, light and convenient both to transport and use.

As is known in the art of aerosol antiperspirant compositions, the particulate material can be suspended in a hydrophobic emollient liquid carrier comprising one or more oils. 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. In accordance with the preferred embodiments of the present invention, the emollient liquid carrier may comprise a mixture comprising cyclomethicone, isopropyl palmitate and dibutyl phthalate. In particular, it is highly preferred that the emollient liquid carrier comprises a volatile silicone such as cyclomethicone. A preferred cyclomethicone is the cyclic pentamer of dimethyl siloxane having a molecular weight of about 370.

The amount of emollient liquid carrier in the composition according to the invention may vary from about 5 to about 50% by weight In order to prevent caking or settling out of the astringent salt in the hydrophobic emollient liquid carrier1 a bulking or suspending agent is 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. 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 vary from about 0.2 to about 5.0 wt%. 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 above 5%.

In accordance with the invention, the packaged antiperspirant composition contains no more than 60 wt% of an aerosol propellant. The propellant gas according to the invention can be any liquefiable gas known to the art for use in aerosol containers. Examples of suitable propellants are trichlorofluoromethane, trichlorotrifluoromethane, trichlorotetrafluoromethane, monochlorodifluoromethane, difluoroethane, propane, butane or isobutane used singly or in combination. The amount of propellant in the composition of the invention should be no more than 60 wt%.

The product may conveniently be manufactured by combining the major ingredients (excluding the propellant) to make a concentrated gel. This gel concentrate can then be combined with perfume and additional volatile silicone inside an aerosol can. The can can then be pressurized by adding the aerosol propellant, and sealed.

Ingredients which can optionally be present in packaged compositions according to the invention include: - cosmetically acceptable vehicles, such as straight and branched chain alcohols, for example, ethanol, isobutanol or isopropanol; - volatile and non-volatile silicones, such as dimethyl cyclosiloxanes or polydimethyl siloxane, eg, DOW CORNING fluids DC244, DC245, DC344, DC345, Q2 1465 and the 200 fluids; - deoperfumes and deodorant compounds which can act as antimicrobial agents; - hydrophobic oils, such as liquid paraffin oils, isopropyl palmitate, and other emollients; - thickeners such as clays, for example, Bentone 38, silicas, for example, Aerosil 200 and hydroxypropyl celluloses such as Klucel; - perfumes; - preservatives and antioxidants; - skin benefit agents, such as allantoin;; - other cosmetic adjuncts conventionally employed in propellant driven aerosol products.

Preferably, the composition according to the invention is essentially anhydrous; that is it contains no more than about 0.5% by weight of water.

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 not containing Bentone, it was sufficient simply to mix together the components of the mixture, and make the composition to the appropriate amount with liquid emollient carrier, such as cyclomethicone.

However, for the formulations containing Bentone, a preferred manufacturing method is to shear together the Bentone, perfume, and an aliquot of the emollient liquid carrier (e.g.

cyclomethicone), using 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. When the mixture is homogenous, the aluminium salt is slowly introduced into the composition, the shearing being maintained. Once this is done, the inert solid is sheared into the composition until it is homogenous, before cooling the mixture.

The remaining emollient liquid carrier is added to the composition, stirred and the composition is dosed into aerosol cans with the appropriate amount of liquifiable propellant.

Example 1 The following formulations (in Table 1) were prepared.The composition was then dosed into 75 ml cans, and the cans were sprayed until either they blocked or were empty, according to a regime by which each can was shaken for 5 seconds, sprayed for 5 seconds, shaken again for a further 5 seconds, and sprayed again for 5 seconds, twice a day.

Table 1 % W/W

Example AACH* Vol.** Ben- Acumist Dry- Per Silicone tone 38 B18 flo fume 1 18.0 24.03 1.8 - - 1.17 2 18.0 22.03 1.8 - 2.0 1.17 3 18.0 20.03 1.8 - 4.0 1.17 4 18.0 18.03 1.8 - 6.0 1.17 5 16.0 18.03 1.8 - 8.0 1.17 6 18.0 22.20 1.8 1.8 - 1.2 7 18.0 22.03 1.8 2.0 - 1.17 8 18.0 20.03 1.8 4.0 - 1.17 9 18.0 18.00 1.8 6.0 - 1.2 All formulations were made to 100% with CAP 30 liquifiable propellant.

* Activated aluminium chlorhydrate, prepared as for example described in EP 6739 (Unilever et al).

** Q2/1465, ex Dow Corning.

Results

Example Sample blocked/Samples number 1 3/10 2 1/10 3 6/10 4 4/10 5 5/10 6 0/10 7 0/10 8 1/10 9 4/10 These results show a reduced incidence of blocking when the composition comprises a small amount of an inert particulate filler, in particular when they contain less than about 4% of filler.

Claims (5)

1. An antiperspirant aerosol composition suitable for topical application to the human skin, comprising 10 35% by weight of an antiperspirant active material, 5 50% by weight of a liquid emollient carrier, and a propellant for expelling these components from the container, wherein the propellant makes up no more than 60% by weight of the composition, the composition additionally comprising at least 0.1% and less than 4% by weight of the total composition of an inert particulate filler material.

2. An antiperspirant aerosol composition according to claim 1, wherein the inert particulate material is present at a level of 0.5-2.5% by weight of the composition.

3. An antiperspirant aerosol composition according to claim 1 or claim 2, wherein the total solids content of the composition is less than 26% by weight of the composition.

4. An antiperspirant aerosol composition according to any of the preceding claims, wherein the liquid emollient carrier is a volatile silicone, in particular cyclomethicone.

5. An antiperspirant aerosol composition according to any of the preceding claims, additionally comprising 0.2-5% of a suspending agent.