GB1589229A

GB1589229A - Aerosol antiperspirant compositions delivering high active concentration of astringent salt at a low delivery rate with good adherence to the skin

Info

Publication number: GB1589229A
Application number: GB38102/77A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-09-17
Filing date: 1977-09-13
Publication date: 1981-05-07
Also published as: NL7710216A; FR2364650A1; DE2741818A1; MX148219A; BE858828A; AU2846577A; ZA775249B; LU78134A1

Description

(54) AEROSOL ANTIPERSPIRANT COMPOSITIONS DELIVERING HIGH ACTIVE CONCENTRATION OF ASTRINGENT SALT AT A LOW DELIVERY RATE WITH GOOD ADHERENCE TO THE SKIN (71) WE, JOSEPH GEORGE SPiTZER. 44 Coconut Row, Palm Beach. Florida, United States of America: MARVIN SMALL. 1100 Park Avenue. New York. New York, United States of America; LLOYD I. OSIPOW. 2 Fifth Avenue. New York. New York, United States of America; DOROTHEA C. MARRA, 107 Fernwood Road, Summit, New Jersey, United States of America; all are citizens of the United States of America do hereby declare the invention. for which we pray that a patent may be granted to us. and the method by which it is to be performed. to be particularly described in and by the following statement: This invention relates to aerosol antiperspirant compositions delivering high active concentration of astringent salt at a low delivery rate with good adherence to the skin.

Aerosol sprays are now widelv used. particularly in the cosmetic, topical pharmaceutical and detergent fields for delivery of an additive. such as a cosmetic. pharmaceutical, or cleaning composition to a substrate. such as the skin. Aerosol compositions are widely used as antiperspirants to direct the antiperspirant to the skin in the form of a finely divided spray.

The delivery of antiperspirants to the skin in a fine spray poses a difficult aerosol packaging problem. Aerosol antiperspirant compositions based on anhydrous propellant systems normally include antiperspirant. filler and other said particles dispersed in a liquid vehicle, and the solid particles readily clog small valve orifices. On the other hand, if the orifices are large enough to avoid clogging. a coarse liquid spray with large droplets is formed, and there may be excessive drip at the nozzle. The material may even be squirted out in the form of a liquid stream, which rapidly runs off the surface on which it is deposited.

Much effort has accordingly been directed to the design of valves and valve delivery ports, nozzles or orifices which are capable of delivering finely-divided sprays, of which U.S. Patent Nos. 3.083.917: 3,(1X3(318; and 3..544.258 are exemplary; The lattermost reference describes a type of valve which is now rather common, giving a finely atomized spray, and having a vapour tap. which includes a mixing chamber provided with separate openings for the vapour phase and the liquid phase to be dispensed into the chamber, in combination with a valve actuator or button of the mechanical breakup type. Such valves provide a soft spray with a swirling motion. Another design of valves of this type is described in U.S. Patent No, 2.77.023. Valves with vapour taps are generally used where the spray is to be applied directly to the skin. since the spray is less cold.

U.S. Patent No. 3,14on127 describes a pressurized self-dispensing package of ingredients for use as a hair spray and comprising a propellint. such as isobutane, in one phase and an aqueous phase including the hair setting ingredient. The isobutane is in a relatively high proportion to the aqueous phase. and is exhausted slightly before the water phase has been entirely dispensed. A vapour tap type of valve is used having a ().()3() inch vapour tap orifice, a ().()3() inch liquid tap orifice. and a ().()1X inch valve stem orifice. with a mechanical breakup button. There is no disclosure of the relative proportions of propellant gas to liquid phase being dispensed.

U.S. Patent No. 3.26().421 describes an aerosol container for expelling an aqueous phase and a propellant phase, fitted with a vapour tap valve, and capillary dip tube. To achieve better blending of the phases before expulsion. the capillary dip tube is provided with a plurality of perforations from () ()l to I 1.2 mm in diameter over its entire length. so that the two phases are admitted together in the valve chamber from the capillary dip tube, instead of the gas being admitted only through a vapour tap orifice, and the liquid through a dip tube as is normal. The propellant is blended in the liquid phase in an indeterminate volume in proportion to the aqueous phase in the capillary dip tube.

U.S. Patent No. 3,544,258 discloses a vapour tap valve having a stem orifice 0.018 inch in diameter, a vapour tap 0.023 inch in diameter with a capillary dip tube 0.050 inch in diameter. The button orifice diameter was 0.016 inch. The composition dispensed is an aluminium antiperspirant comprising aluminium chlorhydroxide, water, alcohol and dimethyl ether. The aluminium chlorhydroxide is in solution in the water, and there is therefore only one liquid phase. The dimensions of the orifices provided for this composition are too small to avoid clogging, in dispensing an aluminium antiperspirant composition containing dispersed astringent salt particles.

The vapour tap type of valve is effective in providing fine sprays. However, it requires a high proportion of propellant, relative to the amount of active ingredients dispensed per unit time. A vapour tap requires a large amount of propellant gas, because the tap introduces more propellant gas into each squirt of liquid. Such values therefore require aerosol compositions having a rather high proportion of propellant. A high propellant proportion is undesirable, however. The fluorocarbon propellants are thought to be deleterious, in that they are believed to accumulate in the stratosphere, where they may possible interfere with the protective ozone layer there. The hydrocarbon propellants are flammable, and the proportion thereof must be restricted to avoid a flame hazard.

Moreover, both these types of propellants, and especially the fluorocarbons, have become rather expensive.

Another problem with such valves is that since they deliver a liquid propellant-aerosol composition mixture, and have valve passages in which a residue of liquid remains following the squirt, evaporation of the liquid in the valve passages after the squirt may lead to deposition of solid materials upon evaporation of liquids, and valve clogging. This problem has given rise to a number of expedients, to prevent the deposition of solid materials in a form which may result in clogging.

Consequently. it has long been the practice to employ large amounts of liquefied propellant, say 50%, by weight, or more, to obtain fine droplets of liquid sprays or fine powder sprays, and a rather small solids content, certainly less than 10%, and normally less than 5%. The fine sprays result from the violent boiling of the liquefied propellant after it has left the container. A case in point is exemplified by the dispersion-type aerosol antiperspirants, which contain 5% or less of astringent powder dispersed in liquefied propellant. It has not been possible to use substantially higher concentrations of astringents without encountering severe clogging problems.

There is considerable current interest in the substitution of compressed gases for fluorocarbons and hydrocarbons as propellants to obtain fine aerosol sprays. The reasons include the low cost of compressed gases, the flammability of liquefied hydrocarbon propellants, and the theorized hazard to the ozone layer of liquefied fluorocarbon propellants. Reasonably fine sprays of alcoholic solutions have been obtained using carbon dioxide at 90 psig and valving systems with very fine orifices. These orifices are so small that dispersed solids cannot be tolerated, and even inadvertent contamination with dust will cause clogging. Thus, a typical system will employ a 0.014 inch capillary dip tube, a 0.010 inch valve stem orifice, and a 0.()()8 inch orifice in a mechanical break-up actuator button.

Only limited variations in delivery rates are possible, since the use of significantly larger orifices will coarsen the spray droplets.

Thus far, the art has not succeeded in obtaining fine aerosol sprays using aqueous solutions with compressed gases. The reasons for this are that water has a higher surface tension and a higher viscosity than alcohol (e.g. ethanol or isopropanol) and is also a poorer solvent for the compressed gases, particularly carbon dioxide, which is preferred. All of these factors adversely affect the break-up of droplets to form a fine spray.

Specialised designs of the delivery port and valve passages have been proposed, to prevent the deposit of solid materials in a manner such that clogging may result. U.S.

Patent No. 3,544,258 provides a structure which is especially designed to avoid this difficulty, for example. Such designs result however in a container and valve system which is rather expensive to produce. complicated to assemble because of the numerous parts, and more prone to failure because of its complexity.

In accordance with U.S. Patent No. 3,970,219, aerosol containers are provided that are capable of delivering a foamed aerosol composition. The aerosol composition is foamed inside the aerosol container. and delivered through the valve of the aerosol container, as a foam or collapsed foam. Fine droplets are formed from the foamed aerosol compositions, due at least in part to collapse of thin foam cell walls into fine droplets. The propellant serves to foam the liquid within the container, forming a foamed aerosol composition, and propels from the container through the valve and delivery port both any foam and any droplets that form when the foam collapses.

With conventional aerosol containers, a substantial proportion of the propellant is in liquid form as the aerosol composition passes through the valve and delivery port.

Propellant evaporates as the spray travels through the air, and it continues to evaporate after the spray has landed on a surface, The heat of vaporization is taken from the surface, and the spray consequently feels cold. This is wasteful of propellant, as is readily evidenced by the coldness of sprays from conventional aerosol containers. In contrast, according to U.S. Patent No. 3,970,219, the propellant is in gaseous form when expelled with the liquid.

The propellant is not wasted, therefore, and since there is substantially no liquid propellant to take up heat upon vaporization, the spray is not cold.

The aerosol containers in accordance with U.S. Patent No. 3,970,219 accordingly foam an aerosol composition therein prior to expulsion from the container, and then expel the resulting foamed aerosol composition. These aerosol containers comprise, in combination, a pressurizable container having a valve movable between open and closed positions, with a valve stem, and a foam-conveying passage therethrough, in flow connection with a delivery port; bias means for holding the valve in a closed position; and means for manipulating the valve against the bias means to an open position, for expulsion of aerosol composition foamed within the container via the valve passage and delivery port; means defining at least two separate compartments in the container, of which a first compartment is in direct flow connection with the valve passage, and a second compartment is in flow connection with the valve passage only via the first compartment; and porous bubbler means having through pores interposed between the first and second compartments with the through pores communicating the compartments, the pores being of sufficiently small dimensions to restrict flow of propellant gas from the second compartment therethrough and form bubbles of such gas in liquid aerosol composition across the line of flow from the bubbler to the valve, thereby to foam the aerosol composition upon opening of the valve to atmospheric pressure, and to expel foamed aerosol composition through the open valve.

U.K. Patent No. 1,543,966 provides another form of foam-type aerosol container, in which the aerosol composition therein is foamed prior to expulsion from the container, and then the resulting foamed aerosol composition is expelled. These aerosol containers comprise, in combination, a pressurizable container having a valve movable between open and closed positions, with a valve stem, and a foam-conveying passage therethrough, in flow connection with a delivery port; bias means for holding the valve in a closed position; and means for manipulating the valve against the bias means to an open position for expulsion via the valve passage and delivery port of aerosol composition foamed within the container; means defining at least two separate compartments in the container, of which a first compartment has a volume of at least 0.5 cc and is in direct flow connection with the valve passage, and a second compartment is in flow connection with the valve passage only via the first compartment; at least one first liquid tap orifice having a diameter of from 0.012 to 0.2 cm and communicating the first and another compartment for flow of liquid aerosol composition into the first compartment, and of sufficiently small dimensions to restrict flow of liquid aerosol composition therethrough; the ratio of first compartment volumelfirst orifice diameter being from about 10/x and preferably from 20/x to 400/x, and move preferably about 200/x, wherein x is I when the orifice length is less than 1 cm, and 2 when the orifice length is 1 cm or more; at least one second gas tap orifice having a total cross-sectional open area of from 7 x 10-6 to 20 x 10-4 (from 4 x 10-5 to 1.3 x 10-2 cm2), a single orifice having a diameter of from 0.003 to 0.05 inch (from 0.007 to 0.13 cm) and communicating the first and second compartments for flow of propellant gas into the first compartment from the second com,eartment therethrough, and of sufficiently small dimensions to restrict flow of propellant gas and form bubbles of such gas in liquid aerosol composition across the line of flow thereof to the valve, thereby to foam the aerosol composition upon opening of the valve to atmospheric pressure, and to expel the foamed aerosol composition through the open valve.

The advantages of foaming the aerosol composition within the container are twofold.

Because the propellant is in gaseous form (having been converted to gas in the foaming) there is no liquid propellant to expel, so all propellant is usefully converted into gas, for propulsion and foaming, before being expelled. Because the foamed liquid aerosol composition has a higher volume than the liquid composition, and the expulsion rate is in terms of volume per unit time, less liquid is expelled per unit time. Thus, in effect, the liquid is expelled at a lower delivery rate, which conserves propellant per unit squirt, and means a higher active concentration must be used, to obtain an equivalent delivery rate of active ingredient. Also, since there is less liquid, there is a negligible clogging problem.

even at a two or three times higher active concentration.

The disadvantage of foaming, however, is the need to provide space for the foaming to take place, which requires either a larger container or a smaller unit volume of composition per container.

U.K. Patent No. 1,555,044 shows that a low delivery rate may be achieved without the necessity of providing a foam chamber or space within the aerosol container, if the volume proportion of gas to liquid in the blend dispensed from the container is from 10:1 to 40:1, and preferably from 15:1 to 30:1. the gas volume being calculated at its pressure within the container. This is a sufficient proportion of gas to liquid to form a foam, such as is formed and dispensed from the foam-type aerosol containers of U.S. Patent No. 3,970,219 and U.K. Patent No. 1,543,966, referred to above, and a very much higher proportion of gas to liquid than has previously been blended with the liquid for expulsion purposes in conventional aerosol containers, such as the vapour tap containers of the U.S. Patent No.

3,544,258 referred to above. At such high proportions of gas to liquid, the formation of foam is possible, and even probable, despite the small volume of the blending space providd, but foam formation, if it occurs. is so fleeting, having a life of at most a fraction of a second, that a foam cannot be detected by ordinary means, due to the small dimensions of the open spaces in which it may exist, i.e., the blending space and valve passages, and the shortness of the delivery time from blending of gas and liquid to expulsion. However, the proprtion of gas to liquid in the blend that is expelled may be determined, and when the proportion is in excess of 10:1, the delivery rate of liquid from the aerosol container is very low, and thus, the desired objective is achieved. Whether or not a foam is formed is therefore of no significance, except as a possible theoretical explanation of the phenomenon.

Accordingly, U.K. Patent No. 1.555,044 provides a process for dispensing a spray containing a low proportion of liquid, with a high proportion of propellant in gaseous form, by blending gas and liquid within the aerosol container prior to expulsion at a ratio of gas: liquid of from 10:1 to 40:1, and preferably from 15:1 to 30:1, with the result that a blend containing this low proportion of liquid and high proportion of gas is expelled from the container, and the proportion of liquid composition expelled per unit time correspondingly reduced.

The aerosol container disclosed in U.K. Patent No. 1,555.044 comprises, in combination, a pressurizable container having a valve movable between open and closed positions, a valve stem, and a delviery port; a valve stem orifice in the valve stem in flow connection at one end with a blending space and at the other end with an aerosol-conveying valve stem passage leading to the delivery port; the valve stem orifice having a diameter of from 0.50 to 0.65 mm; bias means for holding the valve in a closed position; means for manipulating the valve against the bias means to an open position for expulsion of aerosol composition via the valve stem orifice to the delivery port; wall means defining the blending space and separating the blending space from liquid aerosol composition and propellant within the container; at least one liquid tap orifice through the wall means, having a cross-sectional open area of from 0.4 to 0.8 mm2 for flow of liquid aerosol composition into the blending space; at least one vapour tap orifice through the wall means, having a cross-sectional open area of from 0.3 to 0.5 mm2 for flow of propellant into the blending space; the ratio of liquid tap orifice to vapour tap orifice cross-sectional open area being from 1.4 to 2.3; the open areas of the liquid tap orifice and vapour tap orifice being selected within the stated ranges to provide a volume ratio of propellant gas:liquid aerosol composition of from 10:1 to 40:1, thereby limiting the delivery of liquid aerosol composition from the container when the valve is opened.

In the case where the liquid tap orifice is a capillary dip tube the cross-sectional open area thereof is from 0.8 to 1.8 mm2, for flow of liquid aerosol composition into the blending space, and at least one vapour tap orifice through the wall means has a cross-sectional open area of from 0.3 to 0.6 mm2 for flow of propellant gas into the blending space; and the ratio of capillary dip tube to vapour tap orifice cross-sectional open area is from 1.2 to 3.2.

The controlling orifices to achieve the desired proportion of gas and liquid in the blend dispensed from the container are the vapour tap orifice, the liquid tap orifice (or in the case of a capillary dip tube, the capillary dip tube). and the valve stem orifice. The open areas of these orifices and the ratio of liquid tap orifice to vapour tap orifice open area should be controlled within the stated ranges.

The valve delivery system normally includes, in addition to the valve stem orifice, an actuator orifice at the end of the passage through the actuator of the valve. The valve delivery system from the blending chamber through the valve stem and actuator to the delivery port thus includes, in flow sequence towards the delivery end, the valve stem orifice, the valve stem passage. the actuator passage, and the actuator orifice. The controlling orifice in this sequence is the valve stem orifice, and the actuator orifice will normally have a diameter the same as or greater than the valve stem orifice.

Because of the high proportion of propellant gas to liquid in the compositions dispensed trom these types of aerosol containers, particular problems arise in the formulation of aerosol compositions that may be fully expelled from the aerosol container before the supply of propellant gas is exhausted, without undue mistiness or dustiness, and deposit on the skin a compositon which adheres well, and has good antiperspirant efficiency. For delivery of the same amount of astringent salt per unit time or squirt, these containers require that the aerosol formulation contain an unusually high proportion of astringent salt, in excess of 8%, and ranging as high as from 10 to 20%, and more. Since the conventional anhydrous dispersion-type aerosol antiperspirant compositions contain dispersed solids, the resulting high proportion of solid to liquid poses particular problems of dustiness and adherence to the skin, since the proportion of solid material is greatly in excess of the normal proportion, when the astringent salt is in the conventional low concentration of less than 5%.

Moreover, the expulsion of such a large proportion of gas to liquid tends to reduce the liquid to very fine droplets, which form relatively stable aerosols in the air, and tend not to be deposited on the skin, but instead remain suspended in the vicinity of the aerosol can applicator. This not only wastes astringent salt, but also poses a hazard to the user, who may inhale such aerosols, as well as leading to deposits of the material later on, in other parts of the room.

The expulsion of the aerosol composition from the container with a high proportion of gas requires a sufficient quantity of low molecular weight propellant at a sufficiently high vapour pressure to provide both the requisite volume of gas and a sufficient pressure to forcibly expel all of the contents of the container.

A conventional dispersion-type antiperspirant composition in a conventional aerosol container usually contains. by weight, about 10% non-volatile components, comprising finely divided solids and oils, and about 45% each of Propellants 11 and 12. Since the proportion of gas to liquid expelled is quite low, the proportions of the ingredients remaining in the container and the internal pressure remain fairly constant as the container is used, and all of the contents may be expelled.

However, if from 10 to 40 volumes of gas were expelled, per volume of liquid, the high vapour pressure Propellant 12 would be used up first, since it would provide practically all of the gas expelled. After it was all gone. about one-third of the original weight of the contents of the container would remain, and could not be expelled by the remaining Propellant 11. The individual propellants of the propellant mixture are as important as the mixture itself.

In order to expel from 10 to 40 volumes of gas per volume of liquid, propellants are employed with a vapour pressure at 210C of at least 2.4 atmospheres absolute, in an amount of at least 0.15 moles, and preferably at least 0.25 mole, per atmosphere absolute pressure in the container at 210C, per 100 g of composition.

The importance of this low volatility is illustrated by the following Examples. In these Examples, the compositions consist of 20 g of finely divided solids, and non-volatile oils, and 80 g of propellant. The vapour-pressure depression due to the oils is small, and is ignored.

A propellant mixture of 40 g each of Propellants 11 and 12 has a pressure of 3.6 atmospheres absolute at 21"C. Only Propellant 12 has a vapour pressure at 21"C of at least 2.4 atmospheres absolute, and 40 g of this propellant equals 0.33 mole. This value divided by 3.6 atmospheres equals 0.09 mole per atmosphere absolute per 100 g of composition.

This amount is insufficient to expel 20 g of solids and oils from the container.

If the propellant consisted entirely of XO g of Propellant 12, it would comprise 0.66 mole of propellant, with a vapour pressure at 21"C of 5.8 atmospheres absolute. This corresponds to 0.11 mole per atmosphere absolute per 100 g of composition, which is also insufficient to expel all of the solids and oils of the composition.

If the propellant consisted of 80 g of isobutane, it would comprise 1.38 moles of propellant at a pressure of 3.1 atmospheres absolute at 210C, corresponding to 0.45 mole per atmosphere absolute per 100 g of composition. This is sufficient to expel the 20 g of solids and oils.

If a propellant mixture is used consisting of 40 g of isobutane and 20 g each of Propellants 11 and 12, the calculated internal pressure is 3.23 atmospheres absolute at 21 C. The propellant mixture comprised 0.69 mole of isobutane plus 0.165 mole of Propellant 12 for a total of 0.855 mole of propellants having a vapour pressure of at least 2.4 atmosphere absolute. Then 0.855/3.23 equals 0.26 mole propellant per atmosphere absolute pressure per 100 g of composition.

The following Table shows the number of moles of propellant per atmosphere absolute pressure of the propellant at 21"C for 80 g of propellant. All of the propellants shown in the Table have a vapour pressure of at least 2.4 atmospheres absolute at 21"C.

TABLE 1 Molelatmosphere absolute Propane 0.22 Cyclopropane 0.31 Isobutane 0.45 Dimethyl ether 0.34 Chlorodifluoromethane 0.10 Dichlorodifluoroethane 0.11 1-Chloro-1,1-difluoroethane 0.26 1,1-Difluoroethane 0.23 It will be noted that the maximum vapour pressure for the liquefied propellant is limited by the requirement concerning the moles of propellant per atmosphere absolute pressure.

Thus, propane, with a lower molecular weight than isobutane, provides less than half the number of moles per unit pressure. The same quantity of ethane, with a molecular weight of only 30, and a vapour pressure of 38 atmospheres absolute, provides only 0.07 mole per atmosphere absolute.

In accordance with the present invention, aerosol antiperspirant compositions are provided that are highly concentrated with respect to the active antiperspirant, and capable of being dispensed from aerosol containers of the foam type at a low delivery rate in a propellant gas: liquid ratio, by volume, of from 10:1 to 40:1, comprising, in combination, a liquid phase comprising a non-volatile misible organic liquid in an amount of from 0.1 to 30%, by weight of the composition; and an antiperspirant salt in an amount of from 8 to 30% by weight of the composition having at least one liquefied propellant having a vapour pressure of at least 2.4 atmospheres absolute at 210C in an amount of at least 0.15 mole per atmosphere absolute pressure at 2 10C per 100 g of composition to generate an expelled gas: liquid ratio, by volume, of from 10:1 to 40:1 and a solid saturated straight-chain aliphatic carboxylic acid having from fourteen to twenty-two carbon atoms in an amount of from 0.1 to 5%, by weight of the composition, to improve adherence of the antiperspirant salt to the skin. The composition may optionally comprise a synthetic polymer gum having a viscosity of from 500,000 to 100 million centistokes at 250C in an amount from 0.05 to 5%, by weight of the composition, to inhibit mistiness and dustiness.

Dispersion-type aerosol antiperspirant compositions in general are composed of an astringent salt in combination with a non-volatile miscible organic liquid, such as isopropyl myristate, to improve adherence of the astringent salt to the skin. This type of formulation is described in many references including, for example, U.S. Patent Nos. 3.968,203; 3,725,540; 3,903,258; and 3,959,459. These liquids are frequently referred as non-volatile oils, as liquid carriers, and as emollients, and they are generally used in an amount of from 1 to 10% of the composition.

The function of the non-volatile liquid is to adhere the astringent salt to the skin.

However, these oils have an insufficient bonding capacity to be more than moderately effective in adhering the astringent salt to the skin.

Accordingly, as an adherence-promoting agent more effective for this purpose, there is included in the compositions according to the present invention a solid saturated aliphatic carboxylic acid having from fourteen to twenty-two carbon atoms in a straight chain. The acid may have more than one carboxylic acid group, and it may also contain other groups, such as hydroxyl, amido, ether and carboxylic acid ester groups.

Thus, the class of carboxylic acids which may be employed as adherence the amount of astringent salt present, and the particle size of the astringent salt.

In general, the amount of non-volatile liquid should not exceed 200%, by weight of the astringent salt.

The term "non-volatile" means that the liquid will not volatilize during the time the composition is on the skin and before it is adsorbed. This usually requires only a few minutes. Thus, the term "non-volatile" does not exclude materials that are slowly volatile and require a long time to evaporate fully, such as the volatile silicones. These are generally poly dimethyl siloxanes of low viscosity, 2 or 3 centistokes at 250C.

Other suitable examples include:fatty acid esters of polyalkylene glycols wherein the fatty acid contains from two to twenty carbon atoms, and from two to two hundred alkylene glycol units per fatty acid molecule; fatty acid esters of aliphatic alcohols where the esters contain from twelve to twenty-six carbon atoms, such as ethyl laurate, isopropyl myristate, isopropyl palmitate, isopropyl behenate, decyl acetate, behenyl butyrate, hexadecyl acetate, decyl decanoate, methyl oleate, lauryl laurate, and oleyl acetate; esters containing multiple ester groups, such as those disclosed in U.K. Patent No. 1,353,914, that is, multiple ester organic compounds of from twelve to sixteen carbon atoms having a ratio of ester groups to carbon atoms of from 0.125 to 0.214 and having a solubility in water of from 0.0005 to 0.1% at 30"C, examples being di-n-octyl-n-decyl phthalate, di-n-octyl phthalate, d-n-hexyl phthalate, di-n-butyl phthalate, diethyl sebacate, diisopropyl adipate, and ethyl ethoxycarbonyl phthalate.

Liquids more hydrophilic than these esters include polyethylene glycol monolaurate and "Fluid AP", a product of the Union Carbide Company.

Among these various liquid carboxylic acid esters, those having from twelve to twenty-six carbon atoms are preferred. As described above, they may be either aliphatic or aromatic and may contain either one or more ester groups. Especially preferred are the esters, e.g.

di-n-butyl phthalate, diethyl sebacate, diisopropyl adipate, ethyl ethoxycarbonyl phthalate, and "Fluid AP".

The propellant may be a hydrocarbon. a halocarbon, or a mixture thereof, having a vapour pressure of at least 2.4 atmospheres absolute at 210C.

Exemplary hydrocarbon propellants include; isobutane, cyclopropane, and propane.

Isobutane is particularly preferred, because a given weight will provide a large number of moles of propellant per unit vapour pressure. It is generally preferred that the propellant mixture in the compositions according to the present invention contain at least 20%, by weight, of isobutane, and that the proportion of isobutane, by weight, of the entire composition be at least 15%. Mixtures of isobutane with propane or cyclopropane are preferred.

Exemplary halocarbon propellants include: 1, 1-difluoroethane and 1-chloro- 1,1- difluoroethane. These may be used alone or admixed with hydrocarbon propellants or other halocarbon propellants. The latter include chlorodifluoromethane and dichlorodifluoromethane. Combinations of one or more of the latter halocarbon propellants with isobutane are especially preferred.

Dimethylether may also be used, alone or in admixture with hydrocarbon or halocarbon propellants. However, it has a greater toxicity than the propellants mentioned above.

Non-flammable halocarbons with a low vapour pressure may be employed to reduce the flammability of hydrocarbon and halocarbon propellants. Examples of such halocarbons include: methylene chloride, 1,1,1 -trichloromethane, trichlorofluoromethane, dichlorofluoromethane, and 1,2-dichlorotetrafluoroethane.

As an optional feature of the present invention, excessive dustiness or mistiness may be avoided by including in the composition a synthetic polymer gum that is soluble in the liquid phase of the composition. (See, for example, U.K. Patent No. (Application No. 38103/77).) (Serial No. 1589230).

The term "gum" is used to refer to a material that has a viscosity of from 500,000 to 100,000,000 centistokes at 250C, because it is either a rubbery or soft solid or is slowly flowable, as opposed to a rigid solid, which is not flowable, or a liquid, which is too flowable.

The polymer gums are either soft or rubbery solids, or highly viscous materials, flowable under stress, but are too slowly flowable to be properly described as oils or liquids. Various synthetic polymers having a viscosity within this range may be used provided they are soluble in the liquid phase (including the propellant and non-volatile liquid). The function of the polymer gum is to increase the viscosity of the liquid phase. Silicone gums, and especially silicone polymers of the dimethyl polysiloxane type, and acrylic polymers are available within this range, and are preferred. Hydrocarbon polymer gums may also be used.

An approximate empirical relationship between the viscosity of linear silicone gum polymers and the average molecular weights thereof is given in Kirk-Othmer, E;ncyclopedia of Chemical Technology, Interscience Publishers 18 226 (Second Edition, 1969): log (viscosity in centistokes at 250C) = (1.00 + 0.0123 Mnl/2) where Mn is average molecular weight.

This relationship suggests that useful linear silicone gums fall within the molecular weight range of from 140,000 to 350,000. However, branched-chain silicone gums are also useful, and have higher molecular weights at the same viscosity, depending on the degree of branching. Highly branched silicone gums have molecular weights extending to about 2 million.

Particularly useful are silicone gums of the dimethyl polysiloxane type. These may have other groups attached, such as phenyl, vinyl, cyano, or acrylic, but the methyl groups should be in a major proportion.

Silicone polymers having a viscosity below 100.000 centistokes (molecular weight below 100,000) at 25"C are not gums; they are oils, and are ineffective in reducing a tendency towards stable aerosol formation. i.e. mistiness and dustiness at from 10:1 to 40:1 gas:liquid ratios.

Acrylic polymer gums which may be used include: octyl methacrylate, octadecyl methacrylate, butyl acrylate, isobutyl acrylate, copolymers of butyl methacrylate and isobutyl acryalte; and copolymers of one or more of these with acrylonitrile, isoprene, isobutylene or butadiene. These gums may have a molecular weight of from 30,000 to 2,000,000, but the molecular weight is not critical.

Hydrocarbon polymer gums that may be used include: polyisobutylene, polyisoprene, isobutylene-isoprene copolymers, and chloroisobutylene-isoprene copolymers and polybutadiene. Hydrocarbon polymer gums may have a molecular weight of from 30,000 to 2,000,000, but the molecular weight is not critical.

The amount of polymer gum is from 0.05 to 5% and preferably from 0.1to 2%, by weight of the composition. The higher the molecular weight or viscosity of the polymer, the less of it is required to reduce mistiness.

It is important that the polymer gum be soluble in the liquid phase of the composition. It is advantageous, but not essential, that the polymer be soluble in the non-volatile oil component of the composition. If the polymer is not soluble, and is of a rubbery or soft solid consistency, residues in the valve or actuator button may have a tendency to cause clogging. This may be avoided by adding a lubricant. Various conventional lubricants may be used. Silicone oils are lubricants with silicone gums, for example. Some non-volatile organic liquids are lubricants.

As the astringent salt, various antiperspirant aluminium or zirconium salts may be employed in the antiperspirant compositions according to the present invention.

Suitable antiperspirant aluminium and/or zirconium salts are those well known in the art, whether soluble or insoluble in the present antiperspirant compositions. Generally, these are acidic inorganic salts of aluminium and zirconium. Examples of aluminium and zirconium salts are aluminium chlorhydroxide, aluminium chloride, aluminium sulfate, aluminium oxychloride, aluminium oxysulphate, zirconyl chloride, zirconyl hydroxychloride, and zirconium oxychloride.

Many inorganic-organic mixtures and complexes are also known astringent salts, such as zirconium salt/amine/and amino acid complexes. U.S. Patent No. 3,407,254; zirconium salt/aluminium chlorhydroxide/glycol complexes, U.S. Patent No. 3,405,153; aluminium chlorhydroxide/glycol complexes. U.S. Patent No. 3,402,932; aluminium chlorhydroxide/ zirconyl hydroxychloride complexes; and aluminium hydroxide/zirconyl hydroxychloride/ amino acid complexes. Also useful are the aluminium and zirconium salts complexed with polyols, such as propylene glycol.

As the antiperspirant aluminium and/or zirconium salt, in accordance with the present invention, aluminium chlorhydroxide and zirconium chlorhydroxide, and mixtures of aluminium chlorhydroxide and zirconium chlorhydroxide, with or without aluminium chloride or sulphate, are preferred. Aluminium chloride and sulphate may also be used, but these are less preferred.

In order to prevent caking or settling out of the astringent salt in the present compositions, so that it cannot be dispensed from the aerosol container, a bulking agent may be incorporated. This is a finely divided particulate material, inert and insoluble in the liquids present, having a particle size below 10 microns in diameter, and includes colloidal silica and hydrophobic clays.

The colloidal silica is preferably a pyrogenic silica, but other types of silica particles of colloidal sizes may be employed. The colloidal silica will normally be of particle size less than 100 mF, preferably averaging less than 50 m in diameter. Among the more preferred pyrogenic silicas the diameters will be in the 2 to 20 mF range. A preferred pyrogenic silica, sold by Cabot Corporation. Boston, Massachusetts. as "Cab-O-Sil (Registered Trade Mark) M-5", has an ultimate particle diameter of about 11 mu while the corresponding H-5 grade has a diameter of about 7 mu. The surface areas of the pyrogenic colloidal silicas and other colloidal silicas having an average particle size less than one micron are exceptionally great, often resulting from 50 to 500 square metres per gram, leading to desirable thickening, suspending and covering properties. The particles are also of generally spherical shape.

Examples of hydrophobic treated clays that swell in inorganic solvents include hydrophobic bentonite, e.g. "Bentone (Registered Trade Mark) 38", and the other "Bentones", which are bentonite treated with a hydrophobic cationic material, such as ditallowalkyldimethylammonium chloride.

In addition to the propellant, an organic solvent may be added; the solvent reduces the vapour pressure and the viscosity of the composition, as well as the oiliness of the deposit on the skin. Suitable solvents for this purpose are pentane, hexane, trichlorotrifluoroethylene, trichlorofluoromethane, dichlorofluoromethane, and methylene chloride.

Many hydrocarbon and halocarbon liquefied propellants also serve the same purpose, however, if they remain in the deposit on the skin.

In addition to the above-mentioned ingredients, there may be employed the customary adjuncts of aerosol antiperspirant compositions, such as perfumes, bactericides, fungicides, emollients, and skin-treating materials.

The aerosol compositions in accordance with the present invention may be defined by the following general formulation ranges: Parts Overall, Preferred Parts, By Weight By Weight Antiperspirant Salt 8 to 30 8 to 15 Bulking agent 0.1 to 5 0.2 to 2 Non-volatile liquid 1 to 30 1.2 to 20 Carboxylic acid 0.1 to 30 0.1 to 15 Polymer gum 0.05 to 5 0.1 to 2 Propellant > 2.4 atmos. abs. 30 to 90 45 to 89 Other liquefied propellants 0 to 60 0 to 44 or volatile solvents 1The carboxylic acid is part or all of the non-volatile liquid.

2The preferred polymer gum is a silicone gum with a viscosity of from 500,000 to 100 million centipoise at 250C, corresponding to a molecular weight of from 140,000 to 2 million.

The following Examples represent preferred embodiments of the present invention. In the Examples, in addition to the formulations, the dimensions of the important components and the type of aerosol container in which such a composition is preferably used are also given.

Example 1 An aerosol antiperspirant composition was prepared having the following formulation: Parts by Weight Aluminium chlorohydroxide 10.3 Oleic acid 2.5 Isopropyl myristate 7.8 Silicone gum, 2 million centistokes at 25"C 1.4 (polydimethyl siloxane) Cab-O-Sil silica 1.0 Isobutane 65.0 Propane 12.0 The colloidal silica, oleic acid, and isopropyl myristate were placed in a Waring Blendor, and mixed at high speed for 5 minutes. The dispersion was then mixed with the aluminium chlorhydroxide and silicone gun., and homogenized.

The composition was then filled into an aerosol container of the type shown in Figures 1, 1A, and 2 of U.K. Patent No. 1,555,044 having the dimensions shown below, and pressurized with the isobutanepropane mixture.

Internal Diameter Inch mm Valve stem orifice 0.020 0.51 Bubbler orifice 0.030 0.76 Capillary dip tube 0.040 1.0 Actuator orifice 0.020 0.51 In a two-second spray application, there was expelled 0.8 g of antiperspirant composition, which deposited on the skin 0.060 g of astringent salt. The composition was quite effective in inhibiting perspiration for one day.

Example 2 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorohydroxide 8.4 Stearic acid, triple pressed 0.2 Decyl oleate 8.1 Butyl 077' 1.0 Bentone 38 bentonite clay 0.3 Isobutane 18.0 Trichlorofluoromethane 32.0 Dichlorofluoromethane 32.0 'Exxon Chemicals, isobutylene-isoprene copolymer gum, viscosity average molecular weight 425,000 (Flory) The hydrophobic bentonite clay was combined with the decyl oleate, in which the stearic acid had been dissolved, and mixed in a Waring Blendor at high speed for 5 minutes, then combined with the aluminium chlorhydroxide and homogenized. The polymer gum was dissolved in the trichlorofluoromethane at OOC by stirring in a closed container for 2 hours.

The dispersion was cooled and combined with the polymer colution.

The composition was then poured into an aerosol container of the type shown in Figures 1, IA, and 2 of U.K. Patent No. 1,555,044. The composition was then pressurized by the addition of the isobutane, and dichlorofluoromethane.

The aerosol container has the following dimensions: Internal Diameter Inch mm Valve stem orifice 0.020 0.51 Bubbler orifice 0.025 0.64 Capillary dip tube 0.040 1.0 Actuator orifice 0.020 0.51 A two-second application from the container expelled 1.3 g of antiperspirant composition, and deposited 0.10 g of aluminium chlorhydroxide on the skin. The composition was effective for one day in inhibiting perspiration.

Example 3 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorohydroxide 13.0 Palmitic acid 0.3 Diisopropyl adipate 5.1 Isopropyl myristate 5.4 Silicone gum 2 million centistokes 2.0 (polydimethyl siloxane) Cab-O-Sil silica 1.2 Isobutane 73.0 The palmitic acid was dissolved in the mixture of dissopropyl adipate and isopropyl myristate. The collodial silica was added and mixed in a Waring Blendor at high speed for 5 minutes. The dispersion was then combined with the aluminium chlorhydroxide and silicone gum and homogenized. The composition was filled into an aerosol container of the type shown in Figures I and 2 of U.K. Patent No. 1,543,966 having the dimensions shown below and pressurized with isobutane.

Internal Diameter Inch mm Valve stem orifice 0.025 0.64 Foam chamber, height x diameter 1.0 x 0.3 25 x 8 Bubbler orifice 0.040 1.0 Capillary dip tube 0.040 1.0 Actuator orifice 0.025 0.64 A two-second application of the composition expelled 1.0 g of spray, and deposited on the skin 0.065 g aluminium chlorhydroxide. This was effective to inhibit perspiration for one day.

Example 4 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorohydroxide 8.0 Oleic acid 3.0 Isopropyl myristate 9.6 Butyl 077' 1.0 Bentone 38 bentonite clay 0.4 1-chloro-1, 1-difluoroethane 70.0 Chlorodifluoromethane 8.0 'Exxon Chemicals, isobutylene-isoprene copolymer gum, viscosity average molecular weight 425,000 (Flory) The hydrophobic bentonite clay "Bentone 38" was mixed with the isopropyl myristate and oleic acid in a Waring Blendor at high speed for 5 minutes. The dispersion was then combined with the aluminium chlorhydroxide, and homogenized.

The dispersion was then cooled to 15"C and combined with the Butyl 077 gum and 20 parts of 1,chloro-1-1-difluoroethane at the same temperature in a closed container, and stirred for 2 hours to dissolve the gum.

The composition was then filled into aerosols containers of the type shown in Figures 1, 1A, and 2 of U.K. Patent No. 1,555,044. The composition was then pressurized by the addition of the remainder of the l-chloro-l,l-difluoroethane and the chlorodifluoromethane.

The aerosol container had the following dimensions: Internal Diameter Inch mm Valve stem orifice 0.020 0.51 Bubbler orifice 0.035 0.89 Capillary dip tube 0.040 1.0 Actuator orifice 0025 0.64 In a two-second application of the composition there was expelled 1.1 g of composition, which deposited on the skin 0.()8() g aluminium chlorhydroxide. This was effective to inhibit the development of perspiration odour for one day.

Example 5 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorohydroxide 9.0 Trimer acid' 2.0 Decyl oleate 6.1 Silicone gum, 20-50 million centistokes (polydimethyl siloxane) 0.3 Silicone fluid, plasticizer. 100 centistokes 1.6 Cab-O-Sil silica 1.0 Propane 13.0 Isobutane 67.0 'Emery Industries, "Empol (Registered Trade Mark) 1041", a 54 carbon, cyclic tribasic acid.

The colloidal silica, trimer acid and decyl oleate were placed in a Warning Blendor and mixed at high speed for 5 minutes. The dispersion was then mixed with the aluminium chlorhydroxide, and the silicone gum plasticized by the silicone oil, and homogenized.

The composition was then filled into an aerosol container of the type shown in Figures 1 and 2 of U.K. Patent No. 1,543,966, having the dimensions shown below, and pressurized with the isobutane-propane mixture.

Internal Diameter Inch mm Valve stem orifice 0.025 0.64 Foam chamber, height x diameter 1.0 x 0.3 25 x 8 Bubbler orifice 0.040 1.0 Capillary dip tube 0.040 1.0 Actuator orifice 0.025 0.64 In a two-second spray application, there was expelled 1.1 g of antiperspirant composition, which deposited on the skin 0.080 g of astringent salt. The composition was quite effective in inhibiting perspiration for one day.

Example 6 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorhydroxide 8.0 Lauric acid 0.8 Isopropyl myristate 12.0 Silicone gum 10-20 million centistokes (polydimethyl siloxane) 0.4 Cab-O-Sil silica 0.8 Propane 12.0 Isobutane 66.0 The silicone gum was dissolved in 2 parts of the isopropyl myristate by heating while stirring. The colloidal silica was added to a solution of lauric acid in the remainder of the isopropyl myristate and the dispersion was mixed in a Waring Blendor at high speed for 5 minutes, then combined with the aluminium chlorhydroxide and the gum solution and homogenized.

The composition was then poured into an aerosol container of the type shown in Figures 3 and 4 of U.K. Patent No. 1,555.044. The composition was then pressurized by the addition of the isobutane and propane.

The aerosol container had the following dimensions: Internal Diameter Inch mm Valve stem orifice 0.025 0.64 Valve body housing orifice 0.035 0.89 Bubbler orifice 0.030 0.76 Dip tube 0.15 3.8 Actuator orifice 0.025 0.64 A two-second application from the container expelled 0.8 g of antiperspirant composition, and delivered 0.060 g of aluminium chlorhydroxide to the skin. The composition was effective for one day to inhibit perspiration.

Example 7 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorhydroxide 10.0 Isostearic acid 4.5 Isopropyl myristate 5.6 Silicone gum, 10-20 million centistokes 0.4 Silicone fluid, 500 centistokes 1.5 Cab-O-Sil silica 1.0 Propane 10.0 Isobutane 67.0 The colloidal silica was combined with the isopropyl myristate and isostearic acid, and mixed in a Waring Blendor at high speed for 5 minutes. The silicone gum was dissolved in the silicone fluid by heating with stirring. The dispersion was then combined with the silicone solution and aluminium chlorhydroxide, and homogenized. The composition was filled into an aerosol container of the type shown in Figures I and 2 of U.K. Patent No.

1,543,966 having the following dimensions: Internal Diameter Inch mm Valve stem orifice 0.025 0.64 Foam chamber, height x diameter 1.0 x 0.3 25 x 8 Bubbler orifice 0.040 1.0 Capillary dip tube 0.040 1.0 Actuator orifice 0.025 0.64 The contents of the container was then pressurized with the isobutane and propane.

A two-second application expelled 1.0 g of the composition, and delivered to the skin 0.060 g aluminium chlorhydroxide. This was effective to inhibit perspiration for one day.

Example 8 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorhydroxide 10.0 Isostearic acid 9.5 Cab-O-Sil silica 0.5 1 ,1-Difluoroethane 70.0 1,1,2-Trichlorotrifluoroethane 10.0 The colloidal silica was combined with the isostearic acid and mixed in a Waring Blendor at high speed for 5 minutes. The composition was filled into an aerosol container of the type shown in Figures 1 and 2 of U.K. Patent No. 1,543,966, having the dimensions shown below, and then pressurized with a mixture of 1,1-difluoroethane and 1,1,2trichlorotrifluoroethane.

Internal Diameter Inch mm Valve stem orifice 0.020 0.51 Foam chamber, height x diameter 1.0 x 0.3 25 x 8 Bubbler orifice 0.040 1.0 Capillary dip tube 0.040 1.0 Actuator orifice 0.025 0.64 A two-second application from the container expelled 1.0 g of antiperspirant composition, and deposited 0.065 g of aluminium chlorhydroxide on the skin. The composition was effective for one day in inhibiting perspiration.

Example 9 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorhydroxide 12.0 Linoleic acid 4.0 Butyl stearate 3.5 Cab-O-Sil silica 0.5 Cyclopropane 56.0 Trichlorofluoromethane 24.0 The colloidal silica was combined with the linoleic acid and butyl stearate and mixed in a Waring Blendor at high speed for 5 minutes. The composition was then filled into aerosol containers of the type shown in Figures 1, 1A and 2 of U.K. Patent No. 1,555,044. The composition was then pressurized by the addition of a mixture of trichlorofluoromethane and cyclopropane.

The aerosol container had the following dimensions: Internal Diameter Inch mm Valve stem orifice 0.020 0.51 Bubbler orifice 0.035 0.89 Capillary dip tube 0.040 1.0 Actuator orifice 0.020 0.51 A two-second application from the container expelled 1.1 g of antiperspirant composition, and deposited 0.080 g of aluminium chlorhydroxide on the skin. The composition was effective for one day in inhibiting perspiration.

WHAT WE CLAIM IS: 1. An aerosol antiperspirant composition that is highly concentrated with respect to the active antiperspirant, and capable of being dispensed from aerosol containers of the foam type at a low delivery rate in a propellant gas: liquid ratio, by volume, of from 10:1 to 40:1 comprising, in combination. a liquid phase comprising a non-volatile miscible organic liquid in an amount of from 0.1 to 30%. by weight of the composition; and an antiperspirant salt in an amount of from 8 to 30% by weight of the composition; at least one liquefied propellant having a vapour pressure of at least 2.4 atmospheres absolute at 21"C in an amount of at least 0.15 mole per atmosphere absolute pressure at 21"C per 100 g of composition to generate an expelled gas: liquid ratio. by volume, of from 10:1 to 40:1 and a solid saturated straight-chain aliphatic carboxylic acid having from fourteen to twenty-two carbon atoms in an amount of from 0.1 to 5%, by weight of the composition to improve adherence of the antiperspirant salt to the skin.

2. An antiperspirant composition as claimed in claim 1 in which the antiperspirant salt is an aluminium salt.

3. An antiperspirant composition as claimed in claim 2 in which the antiperspirant salt is aluminium chlorhydroxide.

4. An antiperspirant composition as claimed in claim 2 in which the antiperspirant salt is aluminium chloride.

5. An antiperspirant composition as claimed in claim 1 in which the antiperspirant salt is a zironcium salt.

6. An antiperspirant composition as claimed in claim 5 in which the antiperspirant salt is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Internal Diameter Inch mm Valve stem orifice 0.020 0.51 Foam chamber, height x diameter 1.0 x 0.3 25 x 8 Bubbler orifice 0.040 1.0 Capillary dip tube 0.040 1.0 Actuator orifice 0.025 0.64 A two-second application from the container expelled 1.0 g of antiperspirant composition, and deposited 0.065 g of aluminium chlorhydroxide on the skin. The composition was effective for one day in inhibiting perspiration. Example 9 An aerosol antiperspirant composition was prepared having the following formulation: Parts, By Weight Aluminium chlorhydroxide 12.0 Linoleic acid 4.0 Butyl stearate 3.5 Cab-O-Sil silica 0.5 Cyclopropane 56.0 Trichlorofluoromethane 24.0 The colloidal silica was combined with the linoleic acid and butyl stearate and mixed in a Waring Blendor at high speed for 5 minutes. The composition was then filled into aerosol containers of the type shown in Figures 1, 1A and 2 of U.K. Patent No. 1,555,044. The composition was then pressurized by the addition of a mixture of trichlorofluoromethane and cyclopropane. The aerosol container had the following dimensions: Internal Diameter Inch mm Valve stem orifice 0.020 0.51 Bubbler orifice 0.035 0.89 Capillary dip tube 0.040 1.0 Actuator orifice 0.020 0.51 A two-second application from the container expelled 1.1 g of antiperspirant composition, and deposited 0.080 g of aluminium chlorhydroxide on the skin. The composition was effective for one day in inhibiting perspiration. WHAT WE CLAIM IS:

1. An aerosol antiperspirant composition that is highly concentrated with respect to the active antiperspirant, and capable of being dispensed from aerosol containers of the foam type at a low delivery rate in a propellant gas: liquid ratio, by volume, of from 10:1 to 40:1 comprising, in combination. a liquid phase comprising a non-volatile miscible organic liquid in an amount of from 0.1 to 30%. by weight of the composition; and an antiperspirant salt in an amount of from 8 to 30% by weight of the composition; at least one liquefied propellant having a vapour pressure of at least 2.4 atmospheres absolute at 21"C in an amount of at least 0.15 mole per atmosphere absolute pressure at 21"C per 100 g of composition to generate an expelled gas: liquid ratio. by volume, of from 10:1 to 40:1 and a solid saturated straight-chain aliphatic carboxylic acid having from fourteen to twenty-two carbon atoms in an amount of from 0.1 to 5%, by weight of the composition to improve adherence of the antiperspirant salt to the skin.

a mixture or aluminium chlorhydroxide and zirconium chlorhydroxide.

7. An antiperspirant composition as claimed in any of claims 1 to 6 in which the non-volatile liquid is a carboxylic acid ester of an alcohol, the ester having from twelve to twenty-six carbon atoms.

8. An antiperspirant composition as claimed in claim 7 in which the ester is isopropyl myristate.

9. An antiperspirant composition as claimed in any of claims 1 to 8 which comprises colloidal silica having a particle size of below 10 microns.

10. An antiperspirant composition as claimed in any of claims 1 to 8 which comprises a hydrophobic clay having a particle size of below 10 microns.

11. An antiperspirant composition as claimed in any of claims 1 to 10 in which the propellant is a hydrocarbon propellant.

12. An antiperspirant composition as claimed in any of claims 1 to 10 in which the propellant is a halocarbon propellant.

13. An antiperspirant composition as claimed in claim 1 in which the propellant is isobutane.

14. An antiperspirant compositions as claimed in claim 13 comprising a mixture of isobutane and another hydrocarbon or halocarbon propellant as claimed in claim 1.

15. An antiperspirant composition as claimed in claim 1 substantially as herein described with reference to any of the Examples.