WO2004112739A1

WO2004112739A1 - Antiperspirant compositions

Info

Publication number: WO2004112739A1
Application number: PCT/GB2003/002644
Authority: WO
Inventors: Zarah Geron Del Rosario; Satish Kumar Goel; Renato Mallar; Katherine Miranda-Mendoza
Original assignee: Unilever Plc; Unilever Nv; Hindustan Lever Limited
Priority date: 2003-06-18
Filing date: 2003-06-18
Publication date: 2004-12-29
Also published as: AU2003241058A1

Abstract

For the provision of good efficacy, good sensory properties and the capability for ready employment in a sachet, the invention comprises an oil in water emulsion in which the continuous aqueous phase contains a dissolved antiperspirant active, and the dispersed organic phase comprises an emulsifier having an HLB value of at least 6, the emulsion having a viscosity of from 80,000 to 120,000 mPa. s. Preferably, the dispersed phase is solidified at ambient temperature. The invention also provides a sachet containing the emulsion.

Description

ANTIPERSPIRANT COMPOSITIONS

Technical field

The present invention relates to cosmetic compositions, particularly to antiperspirant compositions and more particularly to fluid compositions having an intermediate viscosity.

Background and Prior Art

It has been suggested that one of reasons why we humans have been so successful at colonising all four corners of the earth is that we are able to sweat over a wide fraction of our bodies and thereby avoid over-heating. However, perversely, in many societies, it is considered impolite or bad manners to allow sweat to be evident, particularly in regions such as the underarm where we enjoy a particularly high surface density of sweat glands (eccrine glands) . It is also considered undesirable to generate detectable body odour, that is to say the relatively volatile malodorous compounds formed when resident skin bacteria, e.g. coryne bacteria, transform the relatively odourless compounds present in freshly produced sweat. Whilst such malodours can be masked, it is beneficial for the source to be controlled by application of an antiperspirant. Thus, over the years, one branch of the cosmetics industry that has thrived is that relating to cosmetic use of antiperspirants. Antiperspirant formulations have been made or proposed for manufacture in many physical forms, and in particular as solids, and as fluids, the latter ranging from aerosols in which an active material is conveyed via a gas propellant out of an aerosol can, via liquids such as contact application from a roll on, to thickened creams that are commonly applied from a dedicated dispenser. Such dispensers can be very effective at applying an antiperspirant to a target area, such as under the arms, but inevitably the dispenser itself forms a significant fraction of the cost of making the product. In some parts of the world, the disposable income of a significant fraction of its population is quite low, so that it would be inherently desirable identify a means of producing an effective antiperspirant more cheaply, and one of achieving that aim would be to employ less expensive packaging.

Whatever the choice of packaging employed, it is necessary for the composition to be conveyed effectively to the chosen skin region, and particularly to the underarm and possibly to other localised regions of the body where sweat can accumulated. One distribution means that has been employed to only a limited extent comprises the fingers, especially the finger-tips of the user, or possibly those of a friend or partner. Although the use of fingers can enable less expensive packaging to be contemplated, such a use imposes constraints upon a fluid antiperspirant composition and upon any packaging intended to dispense its contents onto finger for application. One form of packaging that has been contemplated to only a limited extent for antiperspirant formulations comprises a sachet. This has potentially a number benefits in that it has no moving parts, can employ relatively thin sidewalls made from readily available plastics materials and therefore the product can be made relatively cheaply. However, there are potential interactive difficulties with a sachet. If the contents of the sachet have too low a viscosity, there is a distinct risk that product will run off fingers during application or squirt out of the container when an opening is made and be lost. However, if the contents are too thick, it is comparatively difficult to apply using fingers and also to remove the composition effectively from the sachet, with a risk of an increased pressure being applied, that once again can cause material to be expelled rapidly from the sachet .

In addition there are formulation considerations for antiperspirant compositions to make allowance for as well. It is inherently desirable for the composition to be efficacious. At the same time, it is also desirable for the product to have acceptable sensory characteristics on application to the skin. Water from some viewpoints represents a desirable vehicle for conveying an antiperspirant active onto the skin because it enables the active to be presented in dissolved form onto the skin, but thickened water systems as external phase can be sticky, i.e. demonstrate poor sensory characteristics. The sensory properties of systems containing significant proportions of water can be modified by emulsification. Good sensory properties can be attained in a number of instances by dispersing the aqueous phase within an external continuous organic phase, but that itself can carry the risk of impairing antiperspirant efficacy if the antiperspirant is trapped such that does not readily come into skin contact.

It is an object of the present invention to devise a product which overcomes or ameliorates one or more of the disadvantages identified above.

It is a further object of at least some preferred embodiments of the present invention to provide antiperspirant compositions that can be applied effectively by fingers.

It is a still further object of some or other embodiments of the present invention to provide a composition which enjoy an enhanced antiperspirant efficacy.

It is a yet further object of certain embodiments of the present invention to provide a product based on a sachet which overcomes or ameliorates one of more of the disadvantages identified above.

Summary of the invention

According to the present invention there is provided an oil in water emulsion comprising: a) a major proportion by weight of a continuous aqueous containing from 5% to 30% by weight of an antiperspirant active and b) a minor proportion of a disperse oil phase including an emulsifying proportion of an organic nonionic emulsifier system containing at least one emulsifier having an HLB value of at least 6,

proportions by weight herein being based on the total weight of the emulsion which emulsion has a viscosity of from 80,000 to 120,000 mPa.

By employing an antiperspirant composition in the form of an oil in water emulsion having a viscosity within the stated range, it is possible to meet simultaneously the objectives of produce a composition which retains efficacy, has acceptable sensory properties and is suitable for employment by fingers. Such compositions can readily be contained within and dispensed from a sachet .

In a second aspect of the present invention, there is provided a process for the preparation of a cosmetic antiperspirant emulsion in accordance with claim 24.

In a third aspect of the present invention, there is provided a cosmetic antiperspirant product in accordance with claim 28.

In a fourth aspect of the present invention there is provided a cosmetic method for controlling sweat and body odour in accordance with claim 30. Detailed Description of the Invention and preferred embodiments

The present invention provides an emulsion in which the external continuous phase is aqueous. The emulsifier system is so chosen that an oil in water emulsion is obtained and the contents of the emulsion are selected such that it has an intermediate viscosity.

Aqueous phase

The aqueous phase constitutes the major fraction of the emulsion, in many desirable embodiments from 75 to 95% by weight and in a number of very suitable embodiments from 85 to 90% by weight. Herein all percentages and proportions are based on the complete emulsion unless otherwise stated. The aqueous phase includes not only water, which usually is the main constituent, but also any water soluble co-solvent such as a low molecular weight aliphatic alcohol, e.g. ethanol, or a dihydric alcohol such as propylene glycol .. This latter, if present, can be contemplated in an amount of, for example, up to 20% by weight. The weight of the aqueous phase also includes the weight of the antiperspirant active which is dissolved therein, which is selected in the range of from 5 to 30%, in many instances at least 10% and especially is at least 12.5% of the emulsion. Commonly, the emulsion contains up to 25% by weight antiperspirant active. The antiperspirant can be introduced into the composition as a solid which is then dissolved in the liquid constituent or constituents or a fraction thereof, or, which in some ways is more convenient, as a pre-formed solution in the liquid constituent or constituents or a fraction thereof, at the discretion of the producer.

The antiperspirant active can be chosen from a wide range of actives. Antiperspirant actives for use herein are often selected from astringent active salts, including in particular aluminium, zirconium and mixed aluminium/zirconium salts, including both inorganic salts, salts with organic anions and complexes. Preferred astringent salts include aluminium, zirconium and aluminium/zirconium halides and halohydrate salts, such as chlorohydrates, including, particularly desirably, aluminium chlorohydrates .

Aluminium halohydrates are usually defined in their solid state by the general formula Al₂ (OH) _xQ_y.wH₂0 in which Q represents chlorine, bromine or iodine, x is variable from 2 to 5 and x + y = 6 while wH₂0 represents a variable amount of hydration. Most conveniently, the halohydrate is a chlorohydrate, and aluminium chlorohydrates are readily available commercially, e.g. from B K Giulini, either in solid or in dissolved form. The solutions, be they in water or in a dihydric alcohol such as propylene glycol, often contain the antiperspirant active at a concentration of from 30 to 60% by weight, excluding the weight of any water of hydration and based on the weight of the solution.

Zirconium actives can usually be represented in their solid state by the empirical general formula: ZrO (OH) 2n-n_ZB_z .wH₂0 in which z is a variable in the range of from 0.9 to 2.0 so that the value 2n-nz is zero or positive, n is the valency of B, and B is selected from the group consisting of chloride, other halide, sulphamate, sulphate and mixtures thereof. Possible hydration to a variable extent is represented by wH₂0. Preferable is that B represents chloride and the variable z lies in the range 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 above aluminium and zirconium salts may be present as polymeric species, mixtures or complexes. In particular, zirconium hydroxy salts often represent a range of salts having various amounts of the hydroxy group. Zirconium aluminium chlorohydrate in some embodiments is particularly preferred.

Antiperspirant complexes based on the above-mentioned astringent aluminium and/or zirconium salts can be employed. The complex often employs a compound with a carboxylate group, and advantageously this is an amino acid. Examples of suitable amino acids include dl- tryptophan, dl-/3-phenylalanine, dl-valine, dl-methionine and /3-alanine, and preferably glycine which has the formula CH₂(NH₂)COOH.

It is highly desirable in some embodiments to employ complexes of a combination of aluminium halohydrates and zirconium chlorohydrates together with amino acids such as glycine, which are disclosed in US-A-3792068 (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 a range from 2 to 10, especially 2 to 6, an Al/Cl ratio from 2.1 to 0.9 and a variable amount of glycine. Actives of this preferred type are available from Westwood, from Summit and from Reheis.

The disperse phase comprises the minor fraction of the emulsion, especially from 4 to 25% by weight and in a number of very suitable embodiments from 10 to 15% by weight. It normally comprises a plurality of compounds selected from hydrophobic organic compounds and emulsifiers. It is especially desirable for at least a fraction of such organic compounds to be self-emulsifying, and preferably a major weight proportion. Compounds are considered to be self- emulsifying if they have a very low HLB value. They tend to be dominated by an hydrophobic moiety, such a hydrocarbon group of at least 12 carbons, but contain also a small hydrophilic moiety, often comprising an hydroxyl, carboxylic acid or short polyhydric ester moiety. Preferably, the self-emulsifying compounds and emulsifiers together constitute the major weight fraction of the oil phase, more preferably at least 70% and in a number of valued compositions, at least 90% by weight. Herein, the term emulsion encompasses not only formulations in which the disperse phase is in the form of liquid droplets, but also formulations in which such droplets have solidified at ambient or storage temperatures. Indeed, in some especially preferred embodiments, the disperse phase comprises such solidified droplets. The disperse phase commonly contains one or more water- immiscible aliphatic alcohols and particularly alcohols having a melting point of below 20°C. Such alcohols include linear aliphatic alcohols containing from 12 to 25 carbon atoms, such as myristyl, cetyl, stearyl, eicosinyl and behenyl alcohols, or mixtures of any two or more of them, such as cetyl and stearyl , stearyl and behenyl or cetyl , stearyl and behenyl. The proportion of the aliphatic alcohol in the disperse phase is often chosen in the range of from 5 to 15% by weight based on the weight of the disperse phase. In many instances, the weight of the aliphatic alcohol in the emulsion is from 0.5 to 2%.

The disperse phase often contains one or more water- immiscible aliphatic acids, particularly aliphatic acids containing from 12 to 25 linear carbon atoms. Such compounds in practice have a melting point of above 20°C. Desirable aliphatic acids include myristic acid, cetic acid, stearic acid and behenic acid, of which steariuc acid is especially desirable. The proportion of the aliphatic acid in the disperse phase is often chosen in the range of from 10 to 30% by weight based on the weight of the disperse phase. In many instances, the weight of the aliphatic • alcohol in the emulsion is from 1 to 4%.

It is particularly desirable to employ a mixture of the afore-mentioned aliphatic alcohol and aliphatic acid, often in a weight ratio of acid to alcohol of from 1:1 to 3:1, especially in the region of 1.5:1 to 2.5:1. It is especially desirable to include an aliphatic ester of a polyhydric aliphatic alcohol. Such alcohol can desirably be dihydric or trihydric, and preferably contains from 3 to 6 carbons. Examples include propylene glycol and especially glycerol . A mono-ester is particularly suitable. The acid moiety in the ester is preferably derived from aliphatic acids containing from 12 to 25 linear carbons, including laurate, myristate, and stearate. It will be recognised that such esters can perform a dual function. Not only can they act as an emulsifier having a low HLB value

(hydrophylic/lypophylic balance value) , commonly in the region of 2.5 to 5 (sometimes considered to be a co- emulsifier) , but they also have emollient properties. In consequence, they can not only assist in the formation of an emulsion, but also can contribute to desirable sensory properties of the eventual composition. The proportion of said ester in the disperse phase is often chosen in the range of from 35 to 75% by weight based on the weight of the disperse phase. In many instances, the weight of the ester in the emulsion is from 5 to 10%.

In a number of desirable embodiments, the emulsion contains the aliphatic alcohol, the aliphatic acid and the aliphatic ester, for example in a weight selected in the range of 1:1:3.5 to 1:4:10.

A further essential constituent of the emulsion is a nonionic emulsifier having an HLB value of at least 6. Such an emulsifier is incorporated in an amount that can result in the eventual composition having the form of an oil-in- water emulsion at ambient/storage temperatures, often considered to be in the region of 20 to 30°C. Whilst the choice of such an emulsifier is at the discretion of the producer, it is especially desirable to choose an emulsifier having an HLB value of at least 10. Many desirable emulsifiers have an HLB value of up to 18. Especially desirable nonionic emulsifiers having such an HLB value are ethoxylated or optionally ethoxylated/propoxylated, that is to say comprise a hydrophylic moiety containing repeat units of - (C₂H₄0) - or -(C₃H₆0)-, and often selected in the range of at least 10 up to 150 repeat units.

The high HLB emulsifier contain a hydrophobic moiety which preferably is a hydrocarbon that comprises from 12 to 25 carbon atoms, desirably linear, of which convenient and suitable examples comprise moieties having 16 or especially 18 linear carbons. It is particularly suitable for such high HLB emulsifier to be an ether. Thus preferred high HLB value emulsifiers include ceteth-20, steareth-20, steareth- 21, steareth-100 and ceteareth-20. The proportion of high HLB emulsifier is often selected in the range of from 0.3 to 1.0% by weight .

Desirably, the emulsifier system present in the invention emulsions comprises at least one emulsifier having a low HLB value, i.e. having an HLB of below 6 and especially from 2.5 to 5 or 5.5. Such an emulsifier can comprise a polyhydric alcohol ester, such as glyceryl monostearate, but alternatively or additionally, it can comprise an ethoxylate or propoxylate nonionic surfactant containing a relatively low number or repeat - (C₂H₄0) - or - (C₃H₆0) - units such as from 2 to 4. The low HLB ethoxylate emulsifier contains a hydrophobic moiety which preferably is a hydrocarbon which comprises from 12 to 25 carbon atoms, desirably linear, of which convenient and suitable examples comprise moieties having 16 or especially 18 linear carbons. It is particularly suitable for such a low HLB emulsifier to be an ether. Preferred low HLB value ether emulsifiers include steareth-2 and oleth-2. The proportion of such ether emulsifiers is often selected in the range of from 1.0 to 3.0% by weight.

In some embodiments, the low HLB component of the emulsifier system comprises both an ester emulsifier such as has been described hereinabove and an ether emulsifier such as has been described hereinabove, conveniently in a weight ratio of from 10:1 to 25:1.

Most desirably emulsions according to the present invention comprise an aliphatic alcohol, an aliphatic acid, an aliphatic ester and an emulsifier system that includes an ether ethoxylate having an HLB value of from 10 to 18 and includes an ether ethoxylate having an HLB value of from 2.5 to 5.5.

An essential aspect of an emulsion according to present invention is its viscosity, which is within the range of from 80000 to 120000 mPa.s (which has previously been cps) . The viscosity quoted herein is that as measured at 25°C by Brookfield ™ RVT viscometer equipped with a spindle suitable for such a viscosity range, rotated at a suitable speed, , such as a TE bar rotated at 5 rpm. Herein viscosity measurements quoted are obtained using such apparatus or if obtained using other apparatus are converted to measurements made by the Brookfield viscometer. The viscosity within the range is obtained by appropriate selection of the proportions of the constituents and by controlling processing conditions, such as in particular the rate of shear of the emulsion as it cools towards ambient, for example controlling the rate of shear in the vicinity of the solidification temperature of the disperse phase.

In some especially desirable embodiments of the present invention, the oil in water emulsion comprises a combination of from 5 to 10% by weight aliphatic alcohols, aliphatic acids and self-emulsifying aliphatic esters which together solidify at a temperature above 40°C in the presence of an ethoxylated non-ionic emulsifier, and the emulsion is sheared at a temperature between the molten temperature of the oil constituents which is commonly at least 70°C or preferably at least 10°C lower and 50°C, (e.g. 50 to 60°C, the resultant emulsion having a viscosity in the range 80,000 to 120,000 mPa . s .

In a number of preferred embodiments, the emulsion contains a sensorially-enhancing proportion of a silicone elastomer, considered herein as part of the oil phase. Herein, the term elastomer indicates that polysiloxane chains are crosslinked to form a matrix, a three-dimensional molecular structure. Cross linking can be achieved conveniently by hydrosilation of vinyl silicone fluids by hydrosiloxane or MQ hydride fluids. In a number of highly desirable embodiments, the elastomer is non-emulsifying, which is to say that it lacks any hydrophilic substituents such as polyoxyethylene substituents. Silicone elastomers often have an average number molecular weight in excess of 10,000, preferably in excess of 1,000,000 and optimally will range from 10,000 to 20 million. Illustrative of the elastomer is a material with the CTFA name of crosslinked Stearyl Methyl- Dimethyl Siloxane Copolymer. Such materials are available, for example from Dow Corning as DC9040. Emulsifying elastomers from Dow Corning include DC9010 and DC9050. Other suitable elastomers are available from Shisitsu, for example under their grade designations KSG15, KSG16, KSG18, all non- emulsifying and as emulsifying elastomers KSDG21, KSG31 and KSG 32. Even a very small proportion of silicone elastomer can be beneficial, such as from 0.02 to 0.1% by weight, and particularly from 0.04 to 0.08% by weight.

The silicone elastomer is very conveniently introduced into the composition containing an absorbed compatible organic carrier fluid, such as advantageously a volatile silicone. Examples of suitable volatile fluids include cyclomethicones of empirical formula (SiMe₂0)_n in which n is 4 or preferably

5 or 6 methicone units or dimethicones of formula SiMe₃0- (SiMe₂0)_m -SiMe₃ in which m is preferably 3 or 4. Other compatible fluids include volatile hydrocarbons. Advantageously, the weight ratio of absorbed volatile fluid to elastomer is selected in the range of from 2:1 to 20:1, and in a number of highly desirable embodiments is from 3:1 to 15:1. The presence of the fluid within the elastomer causes it to swell. The weight of swollen elastomer plus fluid that is employed in the emulsions herein is advantageously from 0.2 to 1%. The incorporation the silicone elastomer has been found not only to form an oil in water emulsion that exhibits highly desirable sensory properties, but also exhibits superior antiperspirant efficacy.

In addition to the foregoing constituents, the invention compositions can optionally incorporate a particulate water- insoluble inorganic material, such as a clay, talc, silica or metal oxide pigment up to 3%, and often not more than 1%, for example from 0.1 to 0.4% by weight. A further optional constituent comprises a fragrance, typically at a concentration of up to 2.5% by weight, and in many instances from 0.1 to 1.5%, such as from 0.5 to 1%.

The oil phase in the invention compositions can optionally comprise a minor fraction of a water-insoluble organic oil. This oil can be a hydrocarbon oil or can comprise one or more natural water-insoluble oils, such as plant seed oils comprising one or more triglycerides of unsaturated fatty acids, including derivatives of petroselinic acid, linoleic acid and linolenic acid, such as, by way of example only coriander seed oil, sunflower oil, borage oil and evening primrose oil. Such oils or their hydrogenated derivatives can comprise, if desired from 0.1 to 4% by weight of the total formulation, or from 0.5 to 15%, in some instances 1 to 10% of the oil phase by weight.

The invention emulsions can be made by a process in which the constituents are mixed together in liquid or molten form. Conveniently, where one or more of the constituents of the disperse phase is solid at or around ambient temperature, the organic constituents are heated, desirably in the presence of any liquid oils, until a molten mixture is obtained, commonly at a temperature within the range of from 60 to 95°C, the precise temperature depending on the particular constituents selected. It is convenient to include all the emulsifiers into the molten phase. A solution of the constituents of the continuous phase can be prepared separately, either by dissolving solid antiperspirant active into an aqueous liquid or by diluting a pre-formed aqueous solution of antiperspirant with further aqueous liquid. It is desirable to heat the aqueous phase to a similar temperature to that of the molten organic phase prior to the mixing of the two phases .

Although it is possible to incorporate the antiperspirant active into the aqueous phase prior to the introduction of the oil phase, it is preferable to carry out the process in two stages. In the first stage, a fraction of the aqueous phase, such as from 40 to 60% by volume is employed and mixed with the oil phase and in the second stage, the remainder of the aqueous phase is mixed into the already formed oil/water mixture, the second stage preferably occurring at a temperature that is from 50 to 70°C. It is preferable for the second stage aqueous introduction to contain all or at least the major fraction of the antiperspirant active, such as from 80 to 100% of the active.

After the two phases have been mixed, it is preferable for the mixture to be subjected to an homogenisation step in which it is subjected to high shear. High shear apparatus is available commercially, for example a Silverson™ or Sonolator™ mixer. The term high shear is one that is well understood in the field of fluid cosmetics preparation. It is preferable to carry out homogenisation at a temperature of from 40 to 60°C, i.e. commonly at a temperatures that is from 10 to 30°C below that at which the oil phase was rendered molten.

The two liquid mixtures are then mixed together, for example by introducing the organic mixture progressively with agitation into the aqueous phase, advantageously avoiding excessive shear conditions. For convenience, it is often desirable to introduce any fragrance shortly before the product is dispensed into the eventual container, be it bottle, jar, or, especially, sachet, and at a temperature that is preferably in the range of from 35 to 50°C.

It will be recognised that the process for making the invention compositions preferably comprise heating the constituents that are mixed together to a temperature at which the oil phase constituents are molten and thereafter progressively lowering the temperature in a series of steps at which successive processing operations occur.

The choice of constituents of the invention compositions coupled with the choice of an oil in water emulsion brings together desirable physical attributes that are liked by consumers. Firstly, this not only always offers an efficacious composition (when compared at the same concentration and selection of antiperspirant active because the external phase contains the antiperspirant active, but also in the presence of silicone elastomer has exhibited enhanced efficacy at the same concentration and selection of active. Secondly, the presence of the organic constituents, and particularly self-emulsifying water-immiscible constituents such as monoglycerides, enhances the sensory feel of the product. Hence, such an emulsion combines efficacy with beneficial sensory attributes of smoothness of application.

Furthermore, compositions obtained herein are especially suitable for application by fingers, being of suitable viscosity not to run off the fingers, but not excessively viscous. This viscosity also renders then particularly suitable for incorporation into and dosing of an effective dosage from within a sachet. A dosage per arm pit is often in the region of 0.25 to lg, and in many instances from 0.35 to 0.75g. If the viscosity is outside the designated range, there is an increased risk that either the contents will pour too quickly out of the sachet because the viscosity is too low or that excess pressure will be needed because the viscosity is too high so that there is an increased risk that a much larger blob than is needed would be dispensed, wastefully.

A sachet herein is small pouch, commonly formed by sealing two sheets along their perimeter edges to enclose within a small volume of contents. The volume within the sachet is at the discretion of the producer, but often is selected in the range of from 2.5 to 25 mis, and in many instances from 4 to lOmls. The sheets conveniently are made from a thermoplastic such as polyethylene, often having a wall thickness in the region of about 0.05mm to 0.2mm. Such sheets can be sealed by heat welding, preferably initially leaving about l/6^h to l/3^rd of the perimeter unsealed to permit the sachet to be filled, and thereafter sealing the unsealed perimeter. Other suitable sheet materials include thin metal foil, optionally laminated with a thin thermoplastic sheet or water-proofed paper. Such sheets can be sealed by a continuous glue band adjacent to the perimeter of the sheet .

The shape of the sachet is at the discretion of the producer. Convenient shapes include circular, oval, a regular or irregular polygon having at least three sides, optionally with radiussed corners, including triangular, square, rectangular, rhombohedral, pentagonal or hexagonal. The shape can also resemble a well-known object, such as a dove. The sachet can be opened by cutting away a section of the perimeter seal, for example between about l/l0^th to % so as to permit the sachet contents to be squeezed out. Alternatively, the wall of the sachet adjacent to a similar length of the perimeter can be weakened, so that the section can be torn off.

The exterior faces of the sheets may conveniently carry a label to indicate the origin of the product and the contents of the sachet, or more conveniently the sheets themselves can be directly printed, thereby avoiding the need for a separate label . Having described the invention, including preferred embodiments, a number of suitable embodiments will now be described more fully by way of example only.

Examples 1 and 2

In each of these Examples, an emulsion having the composition summarised in Table 1 below was made by the following method: -

A main vessel was charged with demineralised water, and the pigment, titanium dioxide, and heated about 75°C. At the same time, all the organic/oil constituents, including any silicone elastomer, but excluding the fragrance, were charged into a second vessel, mixed continuously and heated until they formed a molten mass, in the region of 75 to 80°C, The molten oil mass was then mixed slowly into the aqueous phase and the mixture cooled to about 55 to 60°C. The antiperspirant active, aluminium chlorohydrate was then introduced, the resultant bulk mixture was homogenised by passage through a high shear mixer and then cooled to about 45°C, whereupon the fragrance mixed in and the mixture was cooled to about 30 to 35°C. The fragranced mixture was passed to a filling station for filling sachets, each with 5g product. Table 1

The formulations of Examples 1 and 2 each had a viscosity of 100,000 mPa.s measured at 25°C using a Brookfield RVT viscometer equipped with TE bar spindle at 5rpm.

The antiperspirant efficacy of the formulations was measured in a conventional test by comparing the sweat produced from a dosed armpit with an undosed armpit of a panel of ladies between the ages of 20 and 50, using a balanced left/right dosing regime in a temperature controlled room for a standard time period. The formulation Example 1 had an efficacy of 46% sweat removal which was the same using as an oil in water cream having the same concentration of the same antiperspirant active, but a substantially higher viscosity of around 140,000 mPa.s. The formulation of Example 2 had a significantly higher sweat reduction of 59%.

Claims

Claims :

1. An oil in water emulsion comprising: a) a major proportion by weight of a continuous aqueous phase containing from 5% to 30% by weight of an antiperspirant active c) a minor proportion of a disperse oil phase including an emulsifying proportion of an organic nonionic emulsifier or mixture of such emulsifiers, at least one of which has an HLB value of at least 6, proportions by weight herein being based on the total weight of the emulsion characterised in that the emulsion has a viscosity of from 80,000 to 120,000 mPa.s.

2. An emulsion according to claim 1 characterised in that the continuous phase represents from 75 to 95% by weight and the disperse phase from 4 to 25% by weight.

3. An emulsion according to claim 2 characterised in that the continuous phase represents from 82 to 87% by weight and the disperse phase from 12 to 16% by weight.

4. An emulsion according to any preceding claim characterised in that the disperse phase comprises solid particles at a temperature of 40°C or below.

5. An emulsion according to claim 4 characterised in that the disperse phase comprises at least one constituent selected from the group consisting of aliphatic alcohols, aliphatic acids and aliphatic esters, each having a melting point higher than 20°C.

6. An emulsion according to claim 5 characterised in that the aliphatic alcohols and aliphatic acids each contain from 16 to 22 linear carbon atoms and the aliphatic ester is a derivative of at least one of such aliphatic alcohols or aliphatic acids.

7. An emulsion according to claim 6 characterised in that the aliphatic ester is a derivative of a di or trihydric alcohol containing from 3 to 6 carbon atoms.

8. An emulsion according to claim 7 characterised in that the aliphatic ester is a derivative of glycerol .

9. An emulsion according to any of claims 6 to 8 characterised in that the aliphatic ester is a mono- ester.

10. An emulsion according to any of claims 5 to 9 characterised in that the disperse phase comprises the aliphatic alcohol, the aliphatic acid and the aliphatic ester.

11. An emulsion according to any of claims 5 to 8 characterised in that the aliphatic alcohol comprises cetyl and/or stearyl alcohol, the aliphatic acid comprises stearic acid and the aliphatic ester comprises glyceryl stearate.

12. An emulsion according to claim 9 or 10 characterised in that the weight ratios of the aliphatic alcohol, the aliphatic acid, acid and the aliphatic ester are selected in the range of 1:1:3.5 to 1:4:10.

13. An emulsion according to any preceding claim characterised in that the emulsifier system includes one or more ethoxylate derivative of an aliphatic alcohol containing from 16 to 22 linear carbon atoms.

14. An emulsion according to claim 12 characterised in that the emulsifier system comprises one or more ethoxylate derivatives of stearyl alcohol.

15. An emulsion according to claim 12 or 13 characterised in that the ethoxylate derivative contains from 2 to 120 ethoxylate units per molecule.

16. An emulsion according to any of claims 13 to 15 characterised in that the ethoxylate derivative is present at a concentration of from 1.5 to 3.5% by weight .

17. An emulsion according to any preceding claim characterised in that the emulsifier system is a mixture of an emulsifier having an HLB value of below 6 and an emulsifier having an HLB value of above 6.

18. An emulsion according to claim 17 characterised in that the emulsifier system comprises a mixture of an alcohol ethoxylate having an HLB value of below 5 and an alcohol ethoxylate having an HLB value of above 10.

19. An emulsion according to claim 17 or 18 characterised in that the emulsifier system comprises a mixture of an aliphatic ester of a polyhydric alcohol having an HLB value of below 5 and an alcohol ethoxylate having an HLB value of above 10.

20. An emulsion according to any one of claims 12 to 17 characterised in that the emulsifier system has an average HLB value of from 7 to 8.

21. An emulsion according to any preceding claim characterised in that the disperse phase comprises a silicone elastomer.

22. An emulsion according to claim 21 characterised in that the silicone elastomer contains at least 3 times its weight of a liquid silicone oil.

23. An emulsion according to claim 21 or 22 characterised in that the weight proportion of silicone elastomer and any silicone oil is from 0.1 to 2.5%.

24. A process for making an antiperspirant emulsion comprising the steps of in step i) heating a mixture of organic compounds, at least one of which is solid at ambient temperature, to a temperature in the range of 70 to 90°C at which a molten mixture is obtained; in step ii) mixing the product of step i) with water or an aqueous solution of an antiperspirant active within said temperature range in the presence of a nonionic emulsifier to form an emulsion, the water or aqueous solution optionally having previously been heated to within said temperature range; in step iii) cooling the resultant emulsion of step ii) and filling it into a container characterised in that the organic compounds together with the emulsifier constitute a dispersed oil phase which is minor proportion by weight of the emulsion; the aqueous phase constitutes a continuous phase which is a major proportion by weight of the emulsion and contains from 5 to 30% by weight of an antiperspirant active based on the emulsion; the emulsion contains at least one emulsifier having an HLB value of at least 6; the weight proportion of the organic compounds being selected together with subjecting the emulsion to shearing at such a rate that it has a viscosity of from 80,000 to 100,000 mPA.s.

25. A process according to claim 24 characterised in that weight proportion of the continuous phase is from 75 to 95% and of the disperse phase from 4 to 25% by weight.

26. A process according to claim 24 or 25 characterised in that the aqueous phase is divided into two fractions, a first fraction being mixed with the molten organic compounds in step ii) and a second fraction being introduced subsequently at a temperature of from 10 to 25°C below the temperature of step ii) and containing at least 80% of the antiperspirant active.

27. A process according to any one of claims 24 to 26 characterised in that the organic compounds are selected from aliphatic alcohols, aliphatic acids and aliphatic esters, each of which having a melting point of higher than 20°C.

28. A cosmetic product comprising a sachet containing an antiperspirant emulsion as described in any of preceding claims 1 to 23 or as produced in any one of claims 24 to 27.

29. A product according to claim 24 characterised in that the sachet is made from a thermoplastics material or a metal foil .

30. A cosmetic method for controlling perspiration and body odour which comprises topically applying to the body an antiperspirant composition according to any of claims 1 to 23.

31. A cosmetic method according to claim 30 characterised in that the antiperspirant composition is applied from a sachet by making an opening in the sachet and squeezing the sachet to eject at least a fraction of its contents.