ZA200109935B

ZA200109935B - Antiperspirant compositions.

Info

Publication number: ZA200109935B
Application number: ZA200109935A
Authority: ZA
Inventors: Bruce Steven Emslie; Lara Dimitrova Stoimenof; Graham Andrew Tumer
Original assignee: Unilever Plc
Priority date: 1999-06-03
Filing date: 2001-12-03
Publication date: 2002-12-03
Also published as: GB9912924D0

Description

ANTIPERSPIRANT COMPOSITIONS

Field of the Invention :

The present invention relates to cosmetic compositions containing a thickened or structured liquid and in particular to such compositions containing an antiperspirant and/or deodorant active.

Background and Prior Art

Topically applied antiperspirant compositions are in widespread use throughout much of the world, in order to enable their users to avoid or minimise visible wet patches on their skin, especially in axillary regions. )

Antiperspirant formulations have been applied using a range ” of different applicators, including aerosols, roll-ons, iE pump sprays, sticks and mushroom applicators, in accordance with the individual preferences of consumers. In some ) parts of the world, sticks are especially popular. The © term stick traditionally indicates a bar of solid material which was usually housed within a dispensing container and which retains its integrity whilst being applied, ie a firm stick. When a portion of a firm stick is drawn across the skin surface, a film of the stick composition is transferred onto the skin surface. Although the stick has the appearance of a solid article, the material forming the stick usually comprises a structured liquid phase such that a film of the material is readily transferred onto another surface upon contact under pressure.

More recently, the term has been applied to soft solids, which have an apparent solid form during storage, but which

- 2 - k flow under mild pressure or shear, so that in use they can be extruded through an aperture or apertures onto a dispensing surface. Soft solids retain their shape for at least 30 seconds after extrusion under such non-shear/low stress conditions from a container, but if subjected to high shear or stress, their structure is destroyed and no more than a minor fraction of the structure can be reformed within a period of about 24 hours when the shear/stress is removed.

There are typically three classes of antiperspirant sticks, namely suspension sticks, emulsion sticks and solution sticks. Suspension sticks contain a particulate antiperspirant active material suspended in a structured carrier. Emulsion sticks normally comprise an emulsion of an oil phase and a hydrophilic phase containing the antiperspirant active in solution, the continuous phase . being structured. In some emulsion sticks, the continuous phase is an oil phase. In solution sticks, the . antiperspirant is typically dissolved in the liquid carrier phase which is structured. The liquid phase in a solution stick can comprise water and/or a water-miscible organic solvent. The three categories can be applied to sticks of both firm and soft solids compositions.

Conventionally, many sticks have been structured using naturally occurring or synthetic waxes, of which typical examples include stearyl alcohol, and hydrocarbon waxes or silicone waxes. Waxes are widely available, and by : suitable selection of the waxes themselves and their concentrations in the formulation can effectively obtain either a soft solid or a firm solid. Thus, for example, wax-structured sticks are described in an article in

Cosmetics and Toiletries, 1990, vol. 105, p75-78. Wax- thickened creams are described in USP 5102656 (Kasat.)

However, and although the disadvantage is not mentioned in either of the above-identified references, it has been observed that wax structured compositions tend to leave visible white deposits on application tec human skin, and } the deposits can also be transferred onto clothing by physical contact with the skin. A significant, and possibly growing, proportion of consumers of antiperspirants have indicated displeasure at visible deposits. Accordingly, the antiperspirant industry, including the instant inventors, is devoting considerable time and resources to finding means to ameliorate or overcome the customer perception of white deposits.

Amongst the class of naturally occurring waxes which have been used or contemplated for use in thickening or } structuring an oily liquid phase of an antiperspirant or. deodorant composition, animal-derived waxes include beeswax, and vegetable-derived waxes include candelilla wax and carnauba wax. Each of these waxes comprises in general . terms a mixture of a) esters, often including an alkyl moiety of at least 8 carbons length derivable from a fatty acid or fatty alcohol, and/or an aromatic hydrocarbon moiety, b) non-esterified fatty acids, c) non-esterified fatty alcohols, d) non-gaseous hydrocarbons and e) resins.

The proportions of the wax constituents varies-depending on the particular wax selected, and to a lesser extent on their geographical location where they are produced and the — time of year.

Various disadvantages have been attributed to the incorporation of naturally occurring waxes, including in particular beeswaxes, such as the disadvantage of variation in properties of the waxes arising from their natural variation in constitution and also the disadvantage arising from the presence of the non-esterified acids and/or alcohols in the wax mixtures. Accordingly, in a number of disclosures, some waxes have been subjected to chemical processes to increase their esters content, prior to their incorporation in a cosmetic formulation.

For example, in USP 5176902, a coloured cosmetic stick is obtained by incorporating a wax which had been esterified : with a C1-60 mono or polyhydric alcohol to convert all naturally present C12-60 fatty acids into their respective esters. In J Kokai 58-092605 there is described the production of a modified beeswax in which free acids are esterified. The product was stated to have excellent pigment dispersibility, e.g. in a massage cream. In EPA- 319062 and USP 4948584, Koster Keunen describe a process for modifying beeswax by removing free acids. The : resultant product has self-emulsifying characteristics.

None of those publications mention the visible white residue of structured or thickened antiperspirant or deodorant compositions and in consequence give no teaching on how to ameliorate or solve the problem.

However, the principle reason for incorporating a wax in a formulation is often to structure or thicken a carrier fluid forming a firm or soft solid. It is advantageous to identify waxes which have a superior ability to structure or thicken a carrier fluid. For example, only a smaller proportion of the wax is needed to achieve a desired extent of thickening or structuring, thereby increasing the options on the producer of cosmetic compositions to vary the remaining constituents. Moreover, the inventors recognised that waxes can be now implicated in at least contributing to the visibility of deposits on skin, and so they concluded that visible deposits may be observable to a lesser extent if less wax were needed.

Cosmetic compositions thickened or structured using : polysiliconyl modified beeswaxes have been described in WO 98/09609 and using hexanediol-behenyl beeswaxes in WO : 98/09712. However, in the course of their present investigations, the present inventors have found that the capability of derivatives of beeswax to thicken or - structure an antiperspirant or deodorant carrier fluid varies, depending on the nature of the modification. Thus, for example, polysiliconyl-modified beeswaxes and fatty acid esterification of free fatty acids in beeswaxes (as in the production of hexanediol-behenyl beeswaxes) have both - been observed to produce materials having a relatively poor structuring capability. Consequently, a pre-treatment of beeswaxes does not necessarily result in the modified beeswax having an effective structuring capability.

One class of stick which has been contemplated for antiperspirant or deodorant application comprises an emulsion stick. Such sticks comprise a continuous phase in which droplets of a second liquid phase are dispersed,

normally referred to as a disperse phase. The continuous phase is one of hydrophobic or aqueous, and the disperse phase constitutes the other. The antiperspirant or deodorant active is conveniently incorporated within the aqueous phase. The hydrophobic phase can be structured by incorporation of wax structurants, these being materials which typically are solid at ambient temperatures, but which melt or dissolve or disperse into the oils constituting the hydrophobic phase at elevated temperatures, for example selected between 60 and 1200C, depending on the choice of oil and wax. When the mixture of wax structurant and oil cools to below its setting temperature, the oil phase solidifies. :

When formulating emulsion sticks, there are a number of factors to be taken into account. Some of the factors are . antagonistic. One of the first and very important factor : relates to the respective proportions of the two phases.

The antiperspirant salts have finite solubility in the . 20 aqueous phase, so that antiperspirant efficacy potentially increases as the proportion of the aqueous phase increases.

However, any increase in the proportion of aqueous phase in the formulation results in a corresponding decrease in the space available to the hydrophobic phase. In conjunction with the choice of its constituent oil or oils, this affects the ability of the hydrophobic phase to provide a strong supporting continuous phase, and hence the strength and integrity of the stick. Moreover, it affects the ability of that phase to contain beneficial hydrophobic constituents.

Waxes have been commonly used or proposed for use in structuring anhydrous formulations, in which a particulate antiperspirant is suspended in an oil phase, but much less attention has been given to their use to structure emulsion sticks.

The market for underarm products is constantly evolving as consumers’ tastes and lifestyles change. One attribute of underarm formulations to which consumers have paid considerable attention in recent years is the extent to which the formulation is visible on the skin, either shortly after application or subsequently throughout the following day. This is commonly referred to as visible deposits. Waxes and antiperspirant salts can give rise to visible deposits on human skin, so that in line with current consumer preferences, it would be desirable to be . able to reduce or ideally eliminate them. A related attribute relates to the visibility of the formulation on any clothing, either occurring in the course of its application to the skin or by subsequent transfer by contact of the skin with the clothing. Likewise, it would be desirable to reduce or ideally eliminate visible deposits on clothing.

Some oils are effective carriers for distributing antiperspirant or deodorant actives on the skin, but have little effect on visible deposits. Various other oils can ameliorate the appearance of visible deposits, but the space available for such oils in emulsions is constrained : by the proportion occupied by the aqueous phase.

- 8g - }

The effect of the oils on the ease with which a firm emulsion stick can be formulated has been mentioned herein before. A further factor relates to the variation in sensory attribute of emulsion sticks made using different oils. Thus, for example, the formulation have a high drag on passage across the skin or they can show a filmy deposit on the skin. They can appear tc be sticky when in the dispensing container or on application to the skin, or they feel greasy.

The prior art contains various publications disclosing sticks containing an aqueous component. Thus, for example

US-A-4265878 exemplifies a formulation containing : substantially no non-volatile oil. The formulation exhibits high visible deposits. US-A-5162378 discloses emulsions containing an aqueous phase, but without a non- volatile oil. Like ‘878, it provides no teaching on the problems associated with formulations containing non- volatile oils and how to solve them. US-A-4704271 discloses formulations containing a high proportion of disperse aqueous phase, a continuous phase containing a low proportion of non-volatile oil and a high ratio of volatile to non-volatile oils, structured with stearyl alcohol.

This formulation has an intrinsically high level of visible deposits from its active and structurant which is reduced <0 to only a limited extent.

WO 98/17238 exemplifies emulsion formulations containing non-volatile oils that are free from volatile silicones.

Consequently, it is silent as to the constraints relating

. to formulations which desire to contain both such constituents and the benefits from containing both of them in selected proportions.

S EP-A-0291334 circumvents the use of waxes by employing a liquid crystal phase to structure the product. accordingly, it provides no teaching concerning the provision of wax-structured emulsions containing both a volatile silicone and a non-volatile oil.

EP-A-0281288 exemplifies an antiperspirant formulation in - which an oil phase containing only a small proportion of a } non-volatile oil is structured with stearyl alcohol. Such a formulation exhibits a high drag and indeed also has a . relatively high visible deposit. Accordingly, it does not ) provide teaching on how to address such issues. EP-A- 0295071 discloses emulsion sticks employing a disperse phase based on a polyhydric alcohol, which can also contain a minor proportion of water. Propylene glycol is exemplified in a 4:1 weight ratio to water in the disperse phase. Sticks which are based on propylene glycol as the principal lipophobic constituent typically exhibit stickiness.

Objects of the present invention

It is an object of the present invention to provide a oo thickened or structured antiperspirant composition which ameliorates or overcomes simultaneously the disadvantage of visible deposits whilst employing a wax having superior structuring capability.

It is a further object of certain preferred embodiments to provide an emulsion stick formulated employing a wax having superior structuring capability and exhibiting a desirable combination of sensory attributes, stick integrity and reduction of visible deposits.

Summary of the Present Invention

According to a first aspect of the present invention, there is provided an antiperspirant composition comprising an antiperspirant active, a liquid carrier and a structurant or thickener for the carrier characterised in that the structurant or thickener comprises an organic wax having a melting point of from 40 to 90°C of which at least 60% of the weight of the wax is provided by at least one aliphatic ester satisfying the formula:- }

CH. (CH;) ,-0-CO- (CH;) n-CHs in which n is from 9 to 39 and m is from 0 to 35.

By the employment of a wax meeting the criteria of selection of the chemical constituticn of the specified constituent and its employment as the greater part of the wax, the goal can be attained of employing a wax which ameliorates the disadvantage of visible deposits whilst offering effective structuring capability.

] Detailed Description of the Invention

In compositions according to the present invention, an essential constituent of the thickening/structuring wax is an ester in accordance with the general formula:

CH;. (CH;) -0-CO- (CH;) n~ CH, in which n is from 9 to 39 and m is from 0 to 35.

The selected ester, or, more normally, mixtures of esters satisfying the general formula, can comprise, if desired, up to 100% of the wax, with the remainder of the wax being satisfied by beeswax or one or more constituents thereof or by a secondary waxy structurant or thickener. In many embodiments, the proportion of the selected ester is at least 70% by weight, preferably at least 80% by weight and most desirably at least 90% by weight of the wax.

It is desirable that the wax employed herein comprises at most no more than a small proportion of free carboxylic : © © 20 acid and hydrocarbons. Preferably, the wax contains no more than about 4% and particularly no more than about 2% by weight non-esterified carboxylic acid. It is highly - desirable that the content of hydrocarbons in the wax is less, and indeed much less than in a conventional beeswax, particularly is less than 5% by weight and especially from 0 to 2% by weight of the wax. .

Within the general formula for the ester, a range of preferred esters comprises those in which n is selected within the range of 14 to 24 and especially 16-20 together with m being selected in the range of 14 to 24 and especially 16 to 20. In second range of preferred esters within the general formula, n is selected in the range of 18 to 38 and m is either 0 or 1. It will be understood that mixtures of esters within each preferred range or

S mixtures of one preferred range of esters with the other can be employed. Convenient mixtures include a mixture of a wax comprising esters of n = 14 to 20 and m = 14 to 20 with a wax comprising esters of n = 16 to 20 and m = 14 to 20 or preferably 16 to 20.

Esters in accordance with the formula given herein can be obtained by a conventional esterification reaction carried under conventional reaction conditions described in the literature for reaction between an alcohol having the chain length appropriate to provide “n” in the ranges specified

E above and a carboxylic acid having a chain length appropriate to yield “m” in the ranges specified above.

The wax is employed herein normally within the range of from 2 to 25% by weight, based on the composition. Where a firm solid composition is desired, the wax proportion is normally at least 5% by weight, and is often selected in the range of from 6 to 15% by weight of the composition.

Where a soft solid composition is desired, the wax proportion is normally below 5%, and particularly from 2 to 4% by weight. It will be understood that when the wax is employed at or near the boundary, i.e. in-the region of 5%, the resultant material may be a scft solid or a firm solid having relatively low hardness in a standard sphere indentation test.

An essential constituent of antiperspirant compositions is an antiperspirant active. Antiperspirant actives, are preferably incorporated in an amount of from 0.5-60%, particularly from 5 to 30 or 40% and especially from 10 to 30 or 35%.

Antiperspirant actives for use herein are often selected from astringent active salts, including in particular aluminium salts, zirconium salts and mixed aluminium- zirconium salts, including for each both inorganic salts and organic salts and complexes. Preferred astringent salts include aluminium, zirconium and aluminium-zirconium halides and halohydrate salts, such as chlorohydrates.

Preferred aluminium salts include aluminium halohydrates : having the general formula Al, (OH) xQy.wH,0 in which Q represents chlorine, bromine or iodine, x is from 2 to 5 and Xx + y = 6, x and y being either integers or non- : integers and w represents a variable amount of hydration, which may be zero. Some especially preferred halohydrate ) salts comprise activated aluminium chlorohydrates such as those described in EP-A-6739 (Unilever NV et al), the contents of which specification is incorporated herein by reference. Activated salts retain their enhanced activity and are advantageously employed in substantially anhydrous formulations, i.e. formulations which do not contain a distinct aqueous phase. Some activated salts can also retain their enhanced activity in hydrous formulations too.

A range of zirconium salts which can be employed desirably in antiperspirant compositions herein is represented by the following empirical general formula: ZrO (OH) 27-nzBz.WH,O in which z is an integer or non-integer in the range of from 0.9 to 2.0, n is the valency of B, 2 - nZ is at least 0, B is selected from the group consisting of halides, including chloride, sulphamate, sulphate and mixtures thereof and w represents a variable amount of hydration, which may be zero. In preferred zirconium salts B represents chloride

S and z lies in the range of from 1.5 to 1.87. In practice, such zirconium salts are usually not employed by themselves, but as a component of a combined aluminium and zirconium-based antiperspirant, the aluminium component normally being selected in accordance with the above- mentioned formula for halohydrates. Especially desirable salts comprise mixed aluminium-zirconium chlorchydrates, optionally activated.

It will be recognised that the above-identified formulae for aluminium and zirconium salts are empirical and encompass compounds having co-ordinated and/or bound water in various quantities as well as polymeric species and ] mixtures and complexes. In particular, zirconium hydroxy salts often represent a range of salts having various amounts of the hydroxy group.

Antiperspirant complexes based on the above-mentioned ’ astringent aluminium, zirconium and aluminium/zirconium salts can desirably be employed in the present invention.

Preferably, aluminium halohydrate and/or zirconium chlorohydrate materials are complexed. The complex often employs a carboxylic acid or carboxylate group, and advantageously an aminoacid. Examples of suitable aminoacids include dl-tryptophane, dl-PB-phenylaniline, dl- valine, dl-methionine and f-aniline, and preferably glycine which satisfies the formula CHE: (NH:)CO:H.

It is highly desirable to employ complexes of a combination of aluminium halohydrates and zirconium chlorohydrates together with aminoacids such as glycine, such as those disclosed in US-A3792068 (Luedders et al). Certain of those Al/Zr complexes are commonly called ZAG in the literature. ZAG actives generally contain aluminium, zirconium and chloride with an Al/Zr ratio in the range of 2 to 10, especially 2 to 6, a ratio of (Al-Zr) / Cl in the range of 2.1 to 0.9 and a variable amount of an amino acid, particularly glycine. Actives of this preferred type are available from Westwood, Summit and

Reheis. LL .

In some formulations, it is particularly preferably to employ activated ZAG complexes which can be produced by the process disclosed in USP 5486347 (Callaghan et al).

Other actives which can be utilised comprise aluminium lactates, borate cross-linked aluminium salts, and astringent titanium salts, for example those described in .

GB 2299506A. Yet other actives includes chlorlinergenics, antihistamines and antiandrenerics.

The proportion of solid aatiperspirant salt in the composition normally includes the weight of any water of hydration and any complexing agent that may also be ’ present. However, when the antiperspirant salt is dissolved in aqueous solution, its weight excludes any water present. : .

In some embodiments of the present invention, the antiperspirant salts is employed herein in particulate form, and particularly in compositions which do not ) comprise an aqueous or hydrophilic phase. Such compositions are conveniently referred to as anhydrous or™ substantially anhydrous. The particle size of - -

antiperspirant salts in such compositions often falls within the range of 1 to 200 pm with a mean particle sizes often from 3 to 20um, such as when conventional. barrels are filled using conventional cast processes. Both larger and smaller mean particle sizes can also be contemplated such as from 20 to 50 pm cx 0.1 to 3 um. }

In other embodiments, the antiperspirant active can be employed in solution form, for example where the composition comprises a polar phase, normally comprising water and/or a water-miscible solvent. In such embodiments, the concentration of antiperspirant active in solution (in the disperse polar phase) is often in the range of from 3 to 60%, based on solely the polar phase, particularly from 10% or 20% up to 55% or 60% of that phase. . The third essential constituent of the composition is a liquid carrier, often in a proportion of from 30 to 95% of the composition, and particularly from 40 to 90%.

The carrier that is incorporated in compositions herein comprises one or more materials that is liquid at which the ~ composition is used and can be gelled or otherwise structured by the structurant to provide a firm or extrudable solid at that use temperature, which conventionally is residential ambient, which is usually below 40°C and in many instances below 30°C and often at least 15°C. The carrier can be hydrophobic or a mixture of both hydrophobic and hydrophilic, the latter normally being in the form of an emulsion. It is particularly desirable that the carrier herein contains sufficient hydrophobic material to produce a continuous phase in which a discontinuous hydrophilic phase or particulate phase can be dispersed. The twin gellant system of the present invention is suited especially to gelling a hydrophobic medium and can also structure a dispersed oil phase, should that be present. -

The hydrophobic carrier liquid may have some volatility or contain volatile constituents but generally its vapour pressure will be less than 4 kPa at 25°C, so that it can be described as an oil or mixture of oils. More specifically, it is desirable that at least 80% by weight of the hydrophobic carrier liquid should consist of materials having a vapour pressure not above 4 kPa at 25°C.

One class of carriers that is particularly desirable herein is hydrophobic and comprises liquid silicones, in order to promote good sensory properties at the time of use of the formulation. Preferably at least a major fraction of the silicone carrier is constituted by at least one volatile : polyorganosiloxane, i.e. liquid materials having a measurable vapour pressure at ambient conditions (about 20 to 25°C). Typically the vapour pressure of volatile silicones lies in the range of from 1 or 10Pa to 2kPa at 25°C. Volatile polyorganosiloxanes can be linear or cyclic or mixtures thereof. Preferred cyclic siloxanes include polydimethylsiloxanes and particularly those containing from 3 to 9 silicon atoms and preferably not more than 7 silicon atoms and most preferably from 4 to 6 silicon atoms, otherwise often referred to as cyclomethicones.

Preferred linear siloxanes include polydimethylsiloxanes containing from 3 to 9 silicon atoms. The volatile - siloxanes normally by themselves exhibit viscosities of below 1 x 107° m?’/sec (10 centistokes), and particularly above 1 x 10°’ m?/sec (0.1 centistokes), the linear siloxanes normally exhibiting a viscosity of below 5 x 107° m’/sec (5 centistokes). The volatile silicones can also comprise branched linear or cyclic siloxanes such as the aforementioned linear or cyclic siloxanes substituted by one or more pendant -0-Si(CHj3); groups. Examples of commercially available silicone oils include oils having grade designations 344, 345 244, 245 and 246, (from Dow

Corning Corporation) Silicone 7207 and Silicone 7158 (from

Union Carbide Corporation) and SF1202 (from General

Electric [US]). Volatile silicones are often present in the composition in a proportion of up to 80% particularly from 10 to 70% and in a number of instances from 20 to 60%.

The hydrophobic carrier employed in compositions herein can alternatively or additionally comprise non-volatile silicone oils, which include polyalkyl siloxanes, polyalkylaryl siloxanes and polyethersiloxane copolymers.

These can suitably be selected from dimethicone and dimethicone copolyols. Commercially available non- volatile silicone oils include Dow Corning 556 and Dow

Corning 200 series having a viscosity of at least 50 centistokes. Non-volatile silicones are often present in not more than about 30% by weight of the composition, and preferably from 1 to 15% by weight. In many instances, when a non-volatile silicone o0il is present, its weight ratio to volatile silicone oil is chosen in the range of from 1:3 to 1:40.

Silicon-free hydrophobic organic carriers can be incorporated in the invention compositions in addition to or instead of liquid silicones, i.e. from 0 to 100% of the hydrophobic carrier liquids. Such silicon-free hydrophobic organic carrier materials can include liquid aliphatic hydrocarbons such as mineral oils or hydrogenated polyisobutene, often selected to exhibit a low viscosity.

Further examples of liquid hydrocarbons comprise polydecene and isoparaffins containing at least 10 carbon atoms and —_— often in the region of up to 30 carbons.

Other suitable hydrophobic carriers comprise liquid aliphatic or aromatic esters, as a fraction of the water- immiscible carrier, desirably not more than 20% and in many instances less than 10% of the weight of the water- immiscible carrier.

Suitable aliphatic esters contains at least one long chain alkyl group, such as esters derivable from C;-Cyq alkanols esterified with a Cs to C;; alkanoic acid or Cg to Cio alkanedioic acid. The alkanol and acid moieties or mixtures thereof are preferably selected such that they have a melting point of below 20°C. Suitable esters include isopropyl myristate, lauryl myristate, isopropyl palmitate, diisopropyl sebacate and diisopropyl adipate. .

Suitable liquid aromatic esters, preferably have a melting point of below 20°C, including fatty alkyl benzoates. ’

Examples of such esters include suitable C8 to C18 alkyl : benzoates or mixtures thereof. )

Further instances of suitable hydrophobic carriers comprise liquid aliphatic ethers derivable from at least one fatty . alcohol, such as myristyl ether derivatives e.g. PPG-3 myristyl ether or lower alkyl ethers of polyglycols such as

PPG-14 butyl ether. The proportion of ether in a formulation according to the present invention is often selected in the range of from 0 to 40% w/w and in some formulations particularly from 1 to 30% w/w.

Yet other suitable hydrophobic carriers comprise liquid aliphatic alcohols containing at least 10 carbon atoms .. which are liquid at 20°C. Examples of such alcohols include branched chain alcohols such as ethylhexyl alcohol, octyldodecanol and isostearyl alcohol. The proportion of the alcohol in a formulation according to the present invention is often selected in the range of from 0 to 40% w/w and particularly from 1 to 30% w/w.

The total proportion of non-silicone hydrophobic carrier (s) is often chosen in the range of from 0 to 80% and particularly from 5 to 70% by weight of the carrier.

Mixtures of hydrophobic non-silicone organic carriers can be employed. If oxygen-containing silicon-free hydrophobic organic liquids are employed, they desirably constitute not more than 70% by weight of the hydrophobic carrier. Lower precportions of the hydrophobic phase, ranging up to for example 20, 30 or 35% in total by weight are more likely.

Mixtures of silicone and non-silicone carriers can suitably be employed herein, in any weight ratio, and in a number of tested embodiments the ratio lies in the range of from 20:1 to 1:20.

The carrier or mixture of carrier employed in the present invention can be and in many effective compositions is anhydrous, i.e. contain no free water, by employing solely one or more hydrophobic carriers. Alternatively, if desired, the composition can comprise a hydrophilic carrier, such as in particular water and/or a water- miscible organic solvent such as an alcoholic water- miscible solvent, in addition to a hydrophobic carrier, such as those indicated hereinbefore. Compositions containing both a hydrophobic and a hydrophylic carrier normally have one of them as a disperse phase.

Formulations containing a disperse phase in practice would often further comprise an emulsifying surfactant, such as an anionic, cationic, zwitterionic and/or nonionic surfactant.

In emulsions herein, the disperse phase, including any material dissolved therein, normally constitutes from 5 to 80% of the weight of the composition and in many embodiments up to 65% by weight and in such or other embodiments preferably at least 25% by weight by weight.

The continuous phase containing structurant therefor provides the weight balance of the composition, such as from 20 to 95% by weight. The emulsions herein normally comprises a water in oil emulsion, i.e. the disperse phase : is the hydrophylic phase . Where an emulsion is employed, it can be convenient to prepare an emulsion as a separate step before it is mixed with the remaining constituents of . the composition.

The emulsion in many instances incorporates one or more emulsifiers, which often are non-ionic. The proportion of emulsifier or emulsifier system, i.e. combination of emulsifiers, in the emulsion is often selected in the range i of from 0.1 to 10% w/w, and in many instances from 0.25 to 5% w/w. Most preferred is an amount of from 0.1 or 0.25% . up to 3% w/w. It is desirable to employ an emulsifier or emulsifier system providing an overall HLB value in a range of from 2 to 10 and preferably from 3 to 8.

It may be convenient to employ an emulsifier system employing in combination an emulsifier having an HLB value above a desired overall value and one having an HLB value below the desired value. By employing the two emulsifiers

- 2 2 - together in appropriate ratios, it is readily feasible to attain a weighted average HLB value that promotes the formation of an emulsion.

Many suitable emulsifiers are nonionic ester or ether emulsifiers comprising a polyoxyalkylene moiety, especially a polyoxyethylene moiety, often containing from about 2 to 80, and especially 5 to 60 oxyethylene units, and/or contain a polyhydroxy compound such as glycerol or sorbitol or other alditols as hydrophilic moiety. The hydrophilic moiety can contain polyoxypropylene. The emulsifiers additionally contain a hydrophobic alkyl, alkenyl or aralkyl moiety, normally containing from about 8 to 50 carbons and particularly from 10 to 30 carbons. The hydrophobic moiety can be either linear or branched and is often saturated, though it can be unsaturated, and is optionally fluorinated. The hydrophobic moiety can . comprise a mixture of chain lengths, for example those deriving from tallow, lard, palm oil sunflower seed oil or soya bean oil. Such non-ionic surfactants can also be derived from a polyhydroxy compound such as glycerol or sorbitol or other alditols. Examples of emulsifiers include ceteareth-10 to -25, ceteth-10-25, steareth-10-25, - and PEG-15-25 stearate or distearate. Other suitable examples include C10-C20 fatty acid mono, di or tri- glycerides. Further examples include C18-C22 fatty alcohol ethers of polyethylene oxides (8 to 12 EO).

The co-emulsifiers, which typically have a low HLB value, and often of from 2 to often comprise mono or possibly : fatty acid diesters of polyhydric alcohols such as glycerol, sorbitol, erythriteol or trimethylolpropane. The fatty moiety is often from Cl4 to C22 and is saturated in many instances, including cetyl, stearyl arachidyl and behenyl. Examples include monoglycerides of palmitic or

Claims

1. An antiperspirant active, a liquid carrier and a structurant or thickener for the carrier characterised in that the structurant or thickener comprises an organic wax having a melting point of from 40 to 90°C of which at least 60% of the weight of the wax is provided by at least one aliphatic ester satisfying the formula: -

CHj. (CHz) n-0-CO- (CH;) n-CHs in which n is from 9 to 29 and m is from 0 to 35.

2. An antiperspirant composition according to claim 1 characterised in that at least 90% of the weight of the wax is provided by the said aliphatic ester.

) 3. An antiperspirant composition according to claim 1 characterised in that the wax contains less than 2% hy weight free carboxylic acid.

4. An antiperspirant composition according to claim 1 characterised in that the wax contains less than 2% by weight hydrocarbons.

5. An antiperspirant composition according to any preceding claim characterised in that in accordance with the general formula for the aliphatic ester, n is selected in the range of from 14 to 20 and m is selected within the range of 14 to 20.

6. An antiperspirant composition according to claim 5 characterised in that in accordance with the general formula for the aliphatic ester, m is selected within the range of 16 to 20.

7. An antiperspirant composition according to any of claims 1 to 4 characterised in that in accordance with the general formula for the aliphatic ester, n is selected in the range of from 18 to 38 and m is selected within the range of 0 or 1.

8. A composition according to any preceding claim characterised in that the antiperspirant active comprises an aluminium, zirconium or aluminium/zirconium halohydrate, an activated aluminium, zirconium or aluminium/zirconium halohydrate, or an aluminium, zirconium or aluminium/zirconium complex or an activated aluminium, zirconium or aluminium/zirconium complex. :

9. A composition according to claim 8 characterised in that the antiperspirant active is a mixed zirconium - aluminium chlorohydrate, an activated aluminium . chlorohydrate or a complex of aluminium plus zirconium chlorohydrate and glycine, optionally activated.

10. A composition according to any preceding claim characterised in that the proportion of antiperspirant - active is from 5 to 40% by weight.

11. A composition according to any preceding claim characterised in that contains a volatile silicone and optionally a non-volatile silicone and/or a liquid non- silicone hydrophobic organic carrier selected from hydrocarbons, hydrophobic aliphatic esters, aromatic esters, hydrophobic alcohols and hydrophobic ethers.

12. A composition according to any preceding claim characterised in that it is anhydrous and contains suspended particulate antiperspirant active.

13. A composition according to any of claims 1 to 11 characterised in that the carrier comprises an aqueous phase containing at least a fraction of the antiperspirant active.

14. A composition according to claim 13 characterised in that it is in the form of an emulsion.

15. A composition according to claim 14 characterised in that the dispersed phase in the emulsion is from 5 to 80% by weight and the continuous phase from 95 to 20% by weight.

16. A composition according to any of claims 13 to 16 characterised in that it contains from 0.1 to 10% by weight of an emulsifier. i 17. A composition according to claim 14 characterised in that the continuous phase comprises from 10 to 35% volatile silicone ¢il, and from 5 to 15% non-volatile hydrophobic oil, the disperse phase comprises from 40 to 75%, the antiperspirant or deodorant active comprises from

0.5 to 35%, the wax structurant comprises from 7 to 25%, the emulsifier comprises from 0.1 to 10%, and the composition preferably contains up to 5% insoluble particulate materials %¥s being by weight.

18. A composition according to claim 17 characterised in that the disperse phase comprises from 40 to 65% and preferably from 45 to 60%.

19. A composition according to either of claims 17 or 18 characterised by containing from 8 to 20% and preferably from 10 to 15% by weight wax structurant.

20. A composition according to any prof claims 17 to 19 characterised by containing not more than 2% of a C12 to C24 saturated linear aliphatic alcohol.

21. A composition according to any of claims 17 to 20 characterised by containing from 10 to 20% volatile silicone.

22. A composition according to any of claims 17 to 21 characterised in that the non-volatile oil is selected from aliphatic esters, aromatic esters and hydrocarbons which are liquid at 25°C.

23. A composition according to any of claims 17 to 22 - characterised by containing the volatile silicone oil and non-volatile oil in a weight ratio of from 1:1 to 3:1 and preferably from 5:4 to 2:1.

24. A composition according to any of claims 17 to 23 characterised by containing from 10 to 30% and preferably from 20 to 25% of a water-soluble antiperspirant active.

25. A composition according to any preceding claim characterised by containing the volatile silicone oil and non-volatile oil in a weight ratio of from 1:1 to 3:1 and preferably from 5:4 to 2:1.

26. A composition according to any of claims 17 to 25characterised by containing from 10 to 30% and preferably from 20 to 25% of a water-soluble antiperspirant active.

27. A composition according to claim 26 characterised in that the weight ratio of antiperspirant active to non- volatile oil is from 1:1 to 4:1, preferably 2:1 to 10:3.

28. A composition according to any of claims 17 to 27 characterised by containing from 1 to 5% by weight of a particulate insoluble material.

29. A composition according to claim 28 characterised by containing a particulate insoluble material selected from talc, finely divided silica, clay, and particulate polyethylene. } i

30. A composition according to any of claims 16 to 29 characterised by containing from 0.5 to 2% emulsifier.

31. A composition according to any of claims 14 to 30 characterised by further containing up to 15% and preferably from 3 to 12% by weight of a polyhydric alcohol.

32. A composition according to claim 31 characterised in that the polyhydric alcohol is selected from glycerol, and propylene glycol.

33. A process for the production of an antiperspirant stick comprising the steps of:

1. incorporating into a liquid carrier a structurant comprising an effective concentration of an organic wax having a melting point of from 40 to 85°C of which at least 60% of the weight of the wax is provided by at least one aliphatic ester satisfying the formula:-

CHj. (CHz) n-0-CO- (CHz) n-CH; in which n is from 9 to 39 and m is from 0 to 35. in an amount sufficient to thicken or structure the carrier to produce an extrudable solid or a solid,

2. rendering the structurant-containing mixture mobile at an elevated temperature

3. mixing the liquid carrier with an antiperspirant active step 2 or 3 being conducted either before after or simultaneously with step 1 to form a structurant- containing mixture

4. introducing the mobile mixture into a applicator ’ container and

5S. cooling or permitting the mixture to cool to a temperature at which it is thickened or structured.

34. A process according to claim 33 characterised by the steps of the steps of forming a hydrophobic mixture by mixing a volatile silicone oil, a non-volatile oil and the wax structurant at an elevated temperature or bringing the mixture to the elevated temperature at which the structurant melts or is dissolved or dispersed in the oils, thereby forming a mobile hydrophobic mixture, simultaneously or sequentially forming an aqueous phase containing water soluble or miscible constituents, shear mixing the mobile hydrophobic mixture with the aqueous phase in the presence of an emulsifier, and

- 6 6 - . any insolble particulate materials thereby forming an emulsion comprising a hydrophobic continuous phase and a disperse aqueous phase, cecoling or permitting the emulsion to cool to a temperature at which a solid is formed by the structurant structuring the continuous phase, characterised in that the continuous phase comprises from 10 to 35% volatile silicone oil, and from 5 to 15% non-volatile hydrophobic oil, the disperse phase comprises from 40 to 75%, the antiperspirant or deodorant active comprises from

0.5 to 35%, the wax structurant comprises from 7 to 25%, } the emulsifier comprises from 0.1 to 10%, the composition preferably contains up to 5% insoluble particulate materials, %¥s being by weight based on the composition.

35. A method for preventing or reducing perspiration on : human skin comprising topically applying to the skin an Co. antiperspirant composition comprising an antiperspirant active, a liquid carrier and a structurant which comprises an organic wax having a melting point of from 40 to 90°C of which at least 60% of the weight of the wax 1s provided by at least one aliphatic ester satisfying the formula:-

CH;. (CH;) ,-0-CO- (CH) n-CH3; in which n is from 9 to 39 and m is from 0 to 35. ’

36. A method according to claim 35 characterised in that the composition in that the continuous phase comprises : from 10 to 35% volatile silicone oil, and from 5 to 15% non-volatile hydrophobic oil, the disperse phase comprises from 40 to 75%, the antiperspirant or deodorant active comprises from

0.5 to 35%, . the wax structurant comprises from 7 to 25%, the emulsifier comprises from 0.1 to 10%, and the composition preferably contains up to 5% insoluble particulate materials %s being by weight.