CA1082601A - Antiperspirant containing urea and aluminum salts - Google Patents

Abstract

ABSTRACT

An improved antiperspirant composition can be prepared by spray drying together a mixture of aluminum chloride, aluminum chlorhydrate, and urea. The spray drying technique produces an impalpable powder which may be incorporated into an antiperspirant formulation suit-able for aerosol application.

Description

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BACKGROUND OF THE INVENTION
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The present invention relates to an-tiperspirant compositions and, more particularly, to antiperspirant form-ulations suitable for aerosol application and methods of pro-ducing the same.
It is well known in the art to provide an antiper-spirant formulation in the form of a cream, a stick, or a roll-on. However, these products have certain disadvantages, as they may leave an undesirable feel on the skin and may contain an excessive quantity of alcohol and water. More recently, aerosols under pressure have become popular as a convenient form for application of antiperspirant formulations to the ski~l. Aerosol antiperspirant and deodorant products now occupy a majority of the market for antiperspirant and deodorant products.
An aerosol product which possesses the attractive cosmetic properties and convenience benefits of currently ~-available aerosol deodorant products and which additionally possess substantial antiperspirant effects without excessive skin irritation would be highly desirable. Since the known inorganic astringent salts possess far greater antiperspirant activity than the organic astringent salts heretofore suggested for aerosol use, the inorganic salts must be used, despite ~-the formulation problems involved, to provide such a product.
Among the most effective astringent inorganic salts are aluminum chloride and aluminum chlorhydrate.
Aluminum chlorhydrate, also known as aluminum chlorhydroxide - 1- ~ .' - - - . - - - - - . .

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complex or basic aluminum chloride, has an approximate atomic ratio of aluminum to chlorine of 2:1, e.g., 2.1:1 to 1.9~
and an empirical formula of AI2(OH)5Cl, existing as a hydrate in solid form.
The efficacy of an antiperspirant composition is largely dependent upon the relative activity of the astringent salt employed therein. However, skin irritation can result from the low pH of many conventional antiperspirant formulations.
It has been found that urea is very effective in reducing skin irritation caused by these formulations without reducing their efficacy. However, the large particle size and hygroscopicity of urea so far has prevented its use in dry aerosol antiper-spirant products.
Accordingly, it is an object of this invention to provide improved aerosol antiperspirant compositions.
It is another object of this invention to provide ;
a dry aerosol antiperspirant formulation which may be applied in powder form, exhibits a high degree of antiperspirant activity and minimizes skin irritation.
It is a furt~er object of this invention to provide a method for making an antiperspirant composition which can be effectively incorporated into an aerosol antiperspirant ormulation.
It is yet another object of this invention to pro-vide a method of incorporating urea in a "dry" powder aerosol antiperspirant formulation in which skin irritation and valve clogging are minimized.

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It is a more specific object of this invention to provide dry aerosol antiperspiran~ formulations having desirable spray characteristics, relative freedom from valve clogging, and which contain highly effective levels of inorganic astringent salts while minimizing skin irritation.
It has now been discovered that these and other objects are achieved by co-spray drying together urea and solutions of aluminum chloride and aluminum chlor-hydrate to form an impalpable powder. The optimum comp-ositions include by weight about 78% to about 92% aluminum chlorhydrate, about 6% to about 12% aluminum chloride, and about 1% to about 10% urea. It is preferred to use about 85% to about 90% aluminum chlorhydrate~ about 8% to about 12% aluminum chloride, and about 2% to about 7% urea.
Preferably, an aqueous solution of aluminum .. ..
chlorhydrate is co-spray dried wlth an aqueous solution of aluminum chloride and solid urea. In general, the alumlnu=
chloride is used as an aqueous solutlon of alu~inum chlorlde having the following general composition ln percentages by weight: Aluminum expressed as aluminum, 5.6-5.8%; Chlorine~ ;
20~23%~ and the balance waterO The final, dry compositlon may contain about 78% to about 92% aluminum chlorhydrate~ about ~ -6% to about 12% aluminum chloride, and about 1%~to about 10%
urea, Preferred final dry composltions may contain about 85% to 90% alumin ~ chlorhydrate, ~rom about 8% to 12%
aluminum chloride~ and from about 2% to 7% urea.
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Antiperspirant formulations can be readily prepared from the antiperspirant compositions of the present invention by adding to the antiperspirant composi~ions the usual cos-metically acceptable adjuvants and propellants. Typically, a suspending agent is used to keep the antiperspirant com-position from a~glomerating or settling out and packing tightly at the bottom of the aerosol container. A carrier is added so that the stream issuing from the aerosol container is a moist spray which effectively adheres to the skin rather than a dusty cloud which does not adhere as well. A pro-pellant is added to force the antiperspirant ~ormulation out of the container. The preferred propellants are n-butane and the "Freon"* series of hydrocarbons. Minor adjuncts such as antimicrobial compounds and perfumes are optional.
It has been found that the antiperspirant composi-tions of the present invention are particularly well suited for powder type antiperspirant formulations. In such cases it is sometimes desirable to add about 1% to about 5% by weight of talc or other suitable powder to the formulation.
In these formulations the antiperspirant composition is present in amounts of about 2% to about 15% by weight and most preferably in amounts of about 3% to about 8% by weight.
Below about 2%, the antiperspirant effectiveness falls off.
Amounts above about 15~ are not practical economically because the antiperspirant effectiveness does not increase commensurate with additional quantities used, in addition to causing han~ling and atomization problems.
An important component of the subject composition is a cosmetically acceptable non-volatile~ propellant~soluble vehicle. Examples of such compounds are fatty acid esters, .~. ;"" '.'':

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fatty alcohols, hydrocarbons such as mineral oil, lanolin and its derivatives, silicone oils such as dimethyl poly-siloxane, diesters of dibasic acids, and nonionic vehicles such as the esters and partial esters of fatty acids contain-ing about 6 to 22 carbon atoms. Useful vehicles include but are not limited to isopropyl palmitate, isopropyl myristate, ethylene glycol, butyl stearate, glyceryl trioleate, stearyl palmitate, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylol propane, propylene glycol, 1,4-hexanediol, 1,2,6-hexanetriol, dipropylene glycol, di-n-octyl-n-decyl phthalate, di-n-butyl phthalate, di-n-hexyl phthalate, di-n-octyl phthalate, diethyl sebacate, diisopropyl adipate, dimethyl phthalate, glycerine, ethoxylated lanolin, acetylated lanolin, propylene glycol dipelargonate, 1,3-butanediol,

2-methyl-2-ethyl-1,3-propanediol, ethylene glycol ethyl ether, ethylene glycol methyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, 2-methyl-2, 4-pentanediol, 1,4-butanediol, 1,2,4-butanethiol, diglycerol, oleyl alcohol, cetyl alcohol, lauryl alcohol, and mixtures of the above.
Another important component of the subject com-position is a suspending agent. Useful materials for inclusion in the subject composition are known bulking agent compounds such as: a colloidal silica such as "Cab-O-Sil"*, a pyrogenic silica having a particle diameter between about 0.001 and 0.03 microns; colloidal (fumed) alumina; finely divided hydrophobically treated clays such as a reaction product of a clay such as bentonite or hectorite with, for example, dimethyl-distearyl ammonium chloride; colloidal magnesium aluminum silicates: other montmorillonite clays; and hydrophobically i treated montmorillonite clays.

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The preferred suspending agents are the hydro-phobically treated montmorillonite or hectorite clays avail-able under the trademark "Bentone" which are prepared by reacting a clay such as bentonite or hectorite in a cation exchange system with a variety of amines. Different amines are reacted to obtain different Bentone suspending agents which may also differ in proportions of SiO2, MgO and A12O3.
Examples of useful Bentone suspending agents are sentone-27, which is stearaluminum hectorite; sentone-34, which is quaternium 18 bentonite; Bentone~38, which is quaternium 18 hectorite; and Bentone-14, which is a clay extended ~uaternium ~ . .. .
18 hectorite, all of which have a particle size of below about 5 microns and are commercially available from the NL
Industries, Inc.
The hydrophobic clays should be thoroughly dispersed.
Three forms of energy which aid in such dispersion are temper-ature increase, chemical energy and mechanical shearing action.
Chemical energy can be supplied in the form of a polar additive such as alcohol or a high boiling organic liquid such as propylene carbonate. Propylene carbonate, usua]ly in an amount of about 0.05 to about 0.5~, is also particularly helpful when the organic liquid has poor wetting properties, or when dispersion is unusually dif~icult. As taught by NL
Industries in their Data Sheet B-33 of April 1970, high mechanical shearing action is also an important factor.
Equipment such as homogenizers, shear pumps, and colloid mills ~ill give positive results. Examples of useful mixers include, among others, the Cowles Dissolver and the Eppenbach Homogenizer. :
The propellant used in connection with the subject ;~`

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invention may be any liquifiable propellant suitable for use in connection with the dispensing of the solid material. That is to say any non-toxic, volatile, organic material which exists as a gas at the temperature of use (and ambient or atmospheric pressure) and which exists as a liquid at the same temperature under superatmospheric pressures, can be used as the gas-producing agent. Especially suitable are the C3-C4 aliphatic hydrocarbons, namely, liquefied propane, n-butane, isobutane, isobutylene; halogenated aliphatic hydrocarbons which contain from 1 to 2 carbon atoms and include, by way of example, methylene chloride, "Freons" such as dichloro-difluoromethane, monochlorodifluoromethane, dichlorotetra-1uoroethane, trichlorofluoromethane, trichlorofluoroethane, difluoroethane, difluoromonochloroethane, trichlorotrifluoro-ethane, monofluorodichloromethane, monofluorodichloroethane, pentafluoromonochloroethane; cyclic hexafluorodichlorobutane, octafluoropropane; and cyclic octafluorobutane, and mixtures of the two or more thereof. Preferably the satu~ated hydro-carbons and halogenated saturated aliphatic hydrocarbons are employed in the subject composition. The preferred propellant for use in connection with the subject composition is a mixture of dichlorodifluoromethane and trichloromonofluoro-methane in a 35:65 blend.
In addition to the essential components of the sub- ;
ject composition one may also include therein components such as per~umes, colorings, and the like, so as to improve the -aesthetic value and consumer acceptability thereof.
Although not essential for this invention, it is desirable to add a non-irritating, non-toxic germicide or bactericide in amounts of about 0.02 to .5~ by weight of the ' ' .: ' "

~V8Z6()1 total composition. Suitable antiseptic agents include dichlorophene, 3, 4', 5-tribromosalicylanilide; 2, 2', 3, 4-tetrabromosalicylanilide, and other bacteriostats commonly known in the art as well as mixtures thereof.
The proportional amounts of each component herein is important to the acceptability of the final composition.
Therefore, one should incorporate said non-volatile, propellant-soluble vehicle in amounts of about 0.5 to about 15% with the preferred range being about 1.5 to about 8% of the total composition. The suspending agent is employed in amounts of about 0.1 to about 3~, desirably about 0.1 to 1% and, pre~er-ably incorporating about 0.25 to about 0O5% thereof with the remainder (normally about 65 to 95%, preferably about 80 to 95~) of the composition being comprised of the propellant therefore. As already mentioned, small amounts of perfume and of coloring may be added.
It will be understood that other ingredients may be added to the above composition in minor proportions without affecting the nature of the invention.

EXAMPLE I
A powdered antiperspirant is prepared from the following starting materials:
% by weight Aluminum chlorhydrate aqueous solution (50% A12(OH)5Cl) 87.7 Aluminum chloride aqueous solution ;
(29% AlC13, balance water) 9.8 Urea 2.5 The above ingredients are blended in a glass-].ined vessel in the order given with minimal mechanical agitation ,.

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needed to solubilize the urea. The liquid blend yielded an atomic ratio on a theoretical basis of Al:Cl of about 1.6:1.
The ingredients are spray dried together in a Komline-Sanderson "Little Giant~ spray dryer, which has a dry-ing chamber three feet in diameter with a three feet cylinder height and a 60~ conical bottom. Heat is supplied by three direct-fired gas burners. Atomization is accomplished with a two-fluid atomizer.
The liquid mixture can be fed into the spray dryer at any temperature, although the temperature preferably ranges of about 55F. to about 80F. The viscosity of the feed is less than 500 cps., and the feed rate can vary from about 50 ml/minute to about 200 ml/minute. The inlet air temperature ranges of about 350F. to about 410F., and outlet air temper-ature ranges of about 160F. to about 210F. The air pressure ranges of about 60 psi to about 200 psi; the feed pressure is less than about 10 psi.
Larger amounts of the antiperspirant composition can be prepared in a gas-fired, cone-bottom spray dryer having a diameter of twelve feet and a height of ten feet on the straight side. In this instance the inlet air temperature ranges of about 400-410F. and the outlet air temperature ranges of about 195-210F. The air pressure is about 70 psi, and the feed rate of liquid is approximately 125-150 gallons per hour.
The oven loss of the resulting product as measured at 105C. for 16 hours indicates a ratio of about 10-12~, and the product is micronized to a particle size of 100~ through 325 mesh using a rotor/stator micronizing mill.
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EXAMPLES II AND III
Additional antiperspirant compositions can be pre-pared in the manner of EXAMPLE I from the following starting ingredients, given in parts by weight:

II III

Aluminum chlorhydrate solution (50~ aqueous solution) 80 85 Aluminum chloride solution (28-30~ aqueous solution) 20 15 Urea 2.62.6 EXAMPLE IV
: The method of EXAMPLE I iS used to prepare a dry ; 10 powder having the following analysis expressed as percent by weight: .
A12(OH)5C1 88.93 ~lC13 5 93 ..
Urea 5.14 Al:Cl ratio 1.61:1 ;-All of the above spray dried powders are micronized :::
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to a particle size of 100~i through 325 mesh utilizing a rotor/ -stator micronizing mill.
EXAMPLE V ~:
A high-oil type aerosol antiperspirant formulation is prepared, using the powder produced by EXAMPLE IV. The resulting formulation contains the following ingredients:

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~ by weight Blend of Aluminum chlorhydrate, Aluminum chloride, and Urea 6.32 Isopropyl palmitate 6.42 Bentone 38* 0.29 Propylene carbonate 0.09 Zinc stearate 0.15 Perfume 0.20 Propellant - 18% Trichloromono-fluoromethane (Freon 11), 10%
Dichlorodifluoromethane (Freon 12), 50% Dichlorotetrafluoro-ethane (Freon 114), 22% n-butane 86.53 *National Lead Co. - organically modified montmorillonite clay (quaternium 18 bentonite) The Bentone 38 is dispersed in the isopropyl palmitate under mild stirring conditions. The stirring speed is increased to high shear, and the propylene carbonate is slowly added to form a gel. Slow stirring is resumed, and the remaining ingredients, e~cept for the propellant, are added. The propellant is added when the antiperspirant formulation is packaged in an aerosol container.
EXAMPLE VI
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Following the method of EXAMPLE V, an aerosol antiperspirant formulation is prepared from the following ingredients:
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~ by weight (Aluminum chlorhydrate 5.42 blend (Aluminum chloride 0.30 (Urea .30 Fluid E-370 (Union Carbide)*2.42 Bentone 38 0.25 Propylene carbonate 0.08 ~ `
Ceraphyl 41** 0.80 Zinc stearate 0.15 Perfume 0.15 Propellant (65~ Freon 11, 35~ Freon 12) 89.83 *di-2-ethyl hexyl adipate :.:
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In this example, the Bentone 38 is blended into the Fluid E-370 under mild stirring conditions before increasing . ~
the stirring speed to add the propylene carbonate. .
EXAMP~E VII :
A powder antiperspirant formulation is prepared using the impalpable powder of EXAMPLE I, and including the :.`
following ingredients:
~ by weight Blend of Aluminum chlorhydrate, Aluminum chloride, and Urea 6.32 Isopropyl palmitate 1.50 Bentone 38 0.29 Propylene carbonate 0.10 Zinc stearate 0.15 Perfume 0.20 Propellant (65~ Freon 11, 35% Freon 12) 91.44 ~`
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The above formulation is tested for sweat reduction as described supra, and the results tabulated below:
Days of Product UseSweat Reduction , .
7 45.51 14 45.20%
EXAMPLE VI I I
A powder type antiperspirant formulation is prepared using the following ingredients, including the impalpable powder of EXAMPLE I I I:
~ by weight (Aluminum chlorhydrate 5.42 blend (Aluminum chloride 0.60 (Urea ~.30 Dow Silicone 225** (dimethyl polysiloxane) 0. 75 Ceraphyl** 41 0.75 Zinc stearate 0.15 .:
Bentone 27* 0.16 Propylene carbonate 0.06 Perfume 0.20 Propellant ( 65~ Freon 11, 35% Freon 12) 91~ 61 *National Lead Co. - organically modified montmorillonite clay (stearaluminum hectorite) The Bentone 27 is.dispersed in the Dow Silicone 225 ``. `
under mild stirring conditions. Stirring speed is lncreased to high shear, and the propylene carbonate is added slowly to .
form a gel. The remaining ingredients, except the propellant, ~ ~:
are then combined with the gel, and the propellant is adde~
at the time the antiperspirant formulation is packaged in an .

aerosol container.
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EXAMPLE IX
, _ A powder type antiperspirant formulation is prepared, using the impalpable powder of EXAMP~E IV, according to the method of EXAMPLE VIII. The formulation included the following:
% by weight Blend of Aluminum chlorhydrate, Aluminum chloride, and Urea 5.00 Dow Silicone 225 0.75 Ceraphyl 41 0.75 Zinc Stearate 0.15 Bentone 27 0.16 .
Propylene carbonate 0.06 Perfume 0.20 Propellant (65~i Freon 11, 35% Freon 12) 92.93 ; EXAMPLE X
A powder type antiperspirant formulation is prepared including the following ingredi.ents:
% by weight ; (Aluminum chlorhydrate 5.62 blend (Aluminum chloride 0.38 (Urea 0.32 ~-;
Isopropyl palmitate 6.41 Bentone 38 0.29 Propylenè carbonate 0.10 Zinc stearate 0.15 Perfume 0.20 Propellant (18% Freon 11, 10% Freon 12, 50% Freon 114, 22% n-butane) 86.53 :
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The Bentone 38 is dispersed in the isopropyl palmit-ate under mild stirring conditions. The stirring rate is increased to high shear, and the propylene carbonate is added slowly to form a gel. The remaining ingredients, with the exception of the propellant, are added with slow stirring.
The propellant is added when the antiperspirant formulation is packaged into aerosol containers.
A sweat test is conducted to determine the efficacy of the antiperspirant of EXA~PLE X. Six weeks prior to the test, the panelists used a mild deodorant having no antiper-spirant activity in order to equilibrate the sweat activity of their armpits. During a one week control period during which the panelists use only a mild deodorant, the panelists are subjected to an emotional challenge to produce sweat, and the sweat is collected on sponges placed under the arms.
This is done four times during a one week period to obtain an average of the amount of sweat under each arm.
To test the antlperspirant, each panelist uses the product antiperspirant under one arm, and a mild deodorant under the other arm. Each product is applied daily, and the sweat reduction is measured 24 hours after seventh, eleventh, thirteenth and fourteenth days of application. After the sweat is measured, the ratio of the sweat of the test underarm -to the sweat of the control underarm is compared to the ratio of sweat under each underarm in the control period in order to measure sweat reduction.
The antiperspirant formulation of EXAMPLE X are tested for sweat reduction, and the results tabulated below:

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Days o~ Product UseSweat Reduction 7 45.6%
11 52.0%
13 50.4%
14 55.5%
EXAMPLE XI
:
A standard aerosol antiperspirant formulation is prepared from the following ingredients:
% by weight Aluminum chlorhydrate6.50 Isopropyl myristate 8.70 Colloidal silica (Cab-O-Sil M5)n. 43 Perfume 0.20 : Propellant (60% Fxeon 11, 40~ Freon 12) 84.37 ~:
This conventional antiperspirant formulation is : tested for sweat reduction as described supra, and the results tabulated below:
Days of Product Use Sweat Reduction :

7 29.9%
: 20 11 35.0% .~
13 34.4% : ~.
14 28.6%
Although the additives in the above formulation are ~`
not exactly the same as those in EXAMPLE X, it is obvious that ;~
the formulation of EXAMPLE X, using the co-spray dried antiperspirant composition of the present invention, gives superior sweat reduction when compared with a typical aerosol -. .
antiperspirant formulation. ` .

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~08Zi~01 Antiperspirant compositions prepared according to the method of the present invention are particularly well suited for incorporation into aerosol antiperspirant compositions, as valve clogging by the hygroscopic urea and aluminum salts is minimized by co-spray drying the ingredients into an impalpable powder. Antiperspirant formulations can readily be prepared from the antiperspirant compositions of the present invention by adding to the co-spray dried antiperspirant compositions the usual cosmetically acceptable adjuvants and propellants`. Typically, a suspending agent is used to keep the antiperspirant composition from agglomerating or settling out and packing tightly at the bottom of the aerosol container.
A carrier is added so that the stream issuing from the aerosol container is a moist spray which effectively adheres to the skin rather than a dusty cloud which does not adhere as well.
A non-toxic, normally gaseous, liquefied propellant is added to force the antiperspirant formulation out of the container. ;
Minor adjuvants such as antimicrobial compounds and perfumes are optional.
It has been found that antiperspirant compositions ~ ~ -prepared according to the method of the present invention are particularly well suited for powder type antiperspirant formulations, in which case talc or other suitable powder s may be added to the formulation.

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Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for making an antiperspirant composition comprising spray drying an aqueous solution of a mixture of about 1% to about 10% of urea, about 6% to about 12% of aluminum chloride, and about 78% to about 92% of aluminum chlorhydrate, by weight.

2. The method of claim 1 wherein said mixture has an Al:Cl atomic ratio of about 1.6:1.

3. The method of claim 1 wherein said mixture contains about 85% to about 90% by weight aluminum chlorhydrate, about 8% to about 12% by weight aluminum chloride, and about 2% to about 7% by weight urea.

4. The method of any of claims 1-3 wherein the resulting composition is micronized to a particle size passing through a 325 mesh screen.

5. An antiperspirant composition comprising a spray dried mixture of about 1 to 10% urea, about 6 to 12% aluminum chloride and about 78 to 92% of aluminum chlorhydrate by weight.

6. An aerosol antiperspirant formulation comprising the antiperspirant oomposition of claim 5 and a non-toxic, liquefied normally gaseous propellant.

7. An aerosol antiperspirant formulation containing the antiperspirant composition of claim 5 in amounts of about 2% to about 15% by weight and a non-toxic liquefied normally gaseous propellant.

8. An aerosol antiperspirant formulation containing a non-toxic lique-fied normally gaseous propellant in an amount of about 65 to 95% by weight, about 0.5 to 15% by weight of a vehicle about 0.1 to 3% by weight of a sus-pending agent, and about 2% to about 15% by weight of an antiperspirant com-position of claim 5.