WO1993008791A1

WO1993008791A1 - Depilatory compositions

Info

Publication number: WO1993008791A1
Application number: PCT/EP1992/002494
Authority: WO
Inventors: Susan Elizabeth Hunt; Helen Louise Linnington
Original assignee: The Boots Company Plc
Priority date: 1991-10-31
Filing date: 1992-10-27
Publication date: 1993-05-13
Also published as: GB9123076D0; AU2876892A

Abstract

A depilatory composition comprising a depilatory compound, in particular potassium thioglycolate, and one or more smectite or kaolin clay, for example bentonite. The composition has a pH of between 11.5 and 12.7. The clay acts to improve the feel of the depilatory composition on the skin and reduces the unpleasant smell associated with the depilatory compound. A tertiary amine of the general formula: NR1R2R3, in which R1 represents a long chain fatty moiety having 8 to 36 carbon atoms and R2 and R3 each independently represent a fatty moiety having 1 to 36 carbon atom or atoms, can be added to the depilatory composition to soften the stiff stubble left by the action of the depilatory compound. The tertiary amine does not reduce the efficacy of the depilatory compound.

Description

Depilatory Compositions

This invention relates to compositions useful for removing unwanted hair from the body.

Conventional depilatory compositions, usually in the form of a cream or a lotion, are applied to the skin of the body at an appropriate place and after 5 to 15 minutes the cream is removed by means of a spatula, cotton wool, sponge or some other suitable material which is wiped over the skin. The active .ingredient of such depilatory compositions is usually an alkali or alkaline earth metal salt of an alpha or beta mercaptocarboxylic acid, e.g. potassium or calcium thioglycolate. Such ingredients are associated with an unpleasant smell which is difficult to mask.

The active ingredient penetrates the hair and destroys the cysteine bonds between the hair molecules thus weakening the hair to such an extent that merely scraping or wiping the cream off the skin breaks the hair at skin level and thus removes it. The cream has to be used at a pH of 12 to 12.5 so that the active ingredient e.g. potassium thioglycolate can penetrate the hair and thus weaken the hair structure. High pH products are potentially irritant and may reduce the condition of the treated skin. However, the skin has a self-regulating system which restores the pH to the normal range of 5 to 7, usually 5.5 plus or minus 0.5 and any hair which is just below the surface of the skin which has been attacked by the active ingredient will then revert to its normal structure and strength as the cysteine bonds are reformed. Subsequent growth of the hair thus causes it to emerge as a stiff stubble shortly after treatment. The initial growth of such stubble can be uncomfortable in certain areas of the body particularly where the medical condition of Pseudofoliculitis exists and this discomfort is only relieved after a further day or so as the hair grows longer and more supple. The initial stiff stubble is also inconvenient because it can snag on fine fabric in clothing. ^~~~

We have now discovered a depilatory composition which, whilst successful in removing unwanted body hair, gives softness of regrowth without reducing the efficacy of the depilatory compound. Surprisingly, the composition has also been found to have a less unpleasant smell than is usually associated with depilatories.

Thus, according to the present invention, there is provided a depilatory composition comprising an effective amount of a depilatory compound and one or more smectite or kaolin clay, said composition having a pH of between about 11.5 and about 12.7. Preferably said composition has a pH of between about 12 and about 12.5.

Suitable clays include smectite clays, for example bentonite, montmorillonite and hectorite; or china (kaolin) clays . Bentonite clays are preferred, for example bentonite clays available commercially e.g. under the trade names Gelwhite L, Gelwhite HNF and Westone supplied by English China Clays. The clay may be incorporated into the depilatory composition at a concentration of, for example 1 to 10% by weight, preferably 2 to 10%, more preferably 5% by weight of the depilatory composition. Heavy metals particularly iron ions, are known to reduce the efficacy of depilatory compounds and are cosmetically unacceptable. The term 'heavy metal' as used herein denotes a metal with an atomic number greater than or equal to that of scandium, but excluding any group I or group II metals.

Thus, advantageously, the clays used in the depilatory composition have a low content of heavy metals, particularly a low content of heavy metal oxide or oxides, especially less than 1% w/w of heavy metal oxide or oxides.

Conveniently the clays comprise a low content of iron oxide and especially a low content of iron oxide in a form soluble in water. The clays may contain less than 1% w/w of Fe2C>3, preferably less than 0.8% w/w of

^Fe2°3' ^more preferably less than 0.3% w/w of Fe2C> .

The depilatory compound may be, for example, an alkali or alkaline earth metal salt of an alpha or beta mercaptocarboxylic acid, preferably potassium or calcium thioglycolate. Varying quantities of the depilatory compound may be used for example between 3% and 10% w/w.

The depilatory compositions of the present invention may take the form of any of the known depilatory compositions, for example creams, lotions or aerosols and may be prepared using conventional methods known in the art. In addition to a depilatory compound and a smectite or kaolin clay, compositions according to the invention may contain other components which will be well known to those skilled in the art, for example emollients such as cetyl alcohol, liquid paraffin or white soft paraffin, humectants such as urea or 1,3- butylene glycol, emulsifying agents such as ethoxylated cetyl or stearyl alcohol, antioxidants such as butylated hydroxytoluene, thickeners such as sodium magnesium silicate, seguestrants such as sodium heptonate, stabilisers such as sodium metasilicate, or perfumes.

Surprisingly, the addition of one or more smectite or kaolin clay to known conditioning depilatory compositions has been shown to improve the conditioning properties of the resultant compositions for example by improving the feel of the depilatory composition on the skin.

Accordingly, a preferred feature of the present invention provides a depilatory composition which comprises: a) an effective amount of a depilatory compound; b) one or more smectite or kaolin clay; and c) a tertiary amine of general formula I

in which R-_j_ represents a fatty moiety having 8 to 36 carbon atoms, and R2 and R each independently represent a fatty moiety having 1 to 36 carbon atoms.

The term "fatty moiety" as used herein denotes a hydrocarbon moiety which may be derived from a fatty acid. The hydrocarbon moiety may be a branched or unbranched aliphatic group, which may be saturated or unsaturated, or an aromatic group and may be optionally substituted for example with one or more hydroxy groups. Preferred fatty moieties are alkyl groups having 1 to 4 carbo atoms, for example methyl, or long chain fatty moieties which may be derived from naturally occurring fats and fatty acids, in particular straight chain saturated or unsaturated aliphatic groups having 8 to 36 carbon atoms, more particularly 16 to 24 carbon atoms. Particularly preferred amines of formula NR R2 3 are those wherein at least two of the groups R_, 2 and R each independently represent a straight chain aliphatic group having 16 to 24 carbon atoms, for example di(hardtallow)methyla ine, distearylmethylamine and tri (hardtallow)amine.

Thus, a depilatory composition according to the invention can be used in method of removing hair from the body which gives re-growth of hair following treatment without the formation of a stiff stubble. Such a method comprises applying a the depilatory composition to the skin at an appropriate part of the body, leaving the composition in contact with the skin until the hair is adequately penetrated, usually 5-15 Ihinutes, and then removing the composition from the surface of the skin.

The efficacy of the depilatory compositions described herein may be compared with conventional conditioning depilatories in controlled user trials. The applicants have found that ^' the compositions according to the^' invention are easy to formulate and have good stability on storage. Surprisingly, the compositions also have good efficacy and a reduced unpleasant smell in use, and give an excellent soft, smooth feel after use.

The invention is illustrated by the following Examples which are not intended to limit the invention in any way.

In the Examples, sodium magnesium silicate was obtained from Laporte Industries, England, under the registered trade mark Laponite XLS; di (hardtallow) methylamine from Akzo Chemie UK Ltd, England, under the registered trade mark Armeen M2HT; distearylmethylamine from S.A. Synfina Oleofina N.V. , Belgium, under the trade name Radiamine 6346; propellant from ICI, England, under the registered trade mark Arcton 12/114 40/60; Cetomacrogol 1000 BP (ethoxylated cetyl alcohol) from Croda, England; ethoxylated fatty alcohol from ICI under the registered trade mark Brij 76; smectite clays from English China Clays under the registered trade mark Gelwhite (L and HNF) and under the trade name Westone L; and Fe^3+" sequestrant from W R Grace Inc, USA, under the registered trade mark Detarex HM.

Example 1

Depilatory Cream % w/w

Sodium magnesium silicate (Laponite XLS]

Sodium heptonate Water

Cetyl alcohol )

Ethoxylated cetyl alcohol (Cetomacrogol 1000 BP)

Light liquid paraffin Wheatgerm oil

Ethoxylated fatty alcohol

(Brij 76)

Butylated hydroxytoluene

Di(hardtallow)methyla ine (Ar een M2HT)

Potassium thioglycolate (42%) soln.

Calcium hydroxide

Urea

Smectite clay (sold under the tradename

Gelwhite L)

Perfume 0.5

Method

a) disperse the calcium hydroxide, clay and sodium heptonate in water at 70°C, then add sodium magnesium silicate;

heat constituents of A to 70°C with mixing;

c) add b) to a) and homogenize;

d) cool to 30°C and add potassium thioglycolate;

e) add urea and perfume. Example 2

Depilatory Cream

The composition of Example 1 was prepared in which the 10% w/w smectite clay was replaced by 5% w/w smectite clay (sold under the tradename Gelwhite L) to give the depilatory cream of Example 2.

Example 3

Depilatory Lotion % w/w

Cetyl alcohol ) 5 20 mol ethoxylated stearyl ) alcohol ) 2

Light liquid paraffin ) A 1

Distearylmethylamine ) 5 (Radiamine 6346) ) 1,3-Butylene glycol ^' 1

Fe³⁺ sequestrant (Detarex HM) 0.1

Potassium thioglycolate soln. (42%) 14

Calcium hydroxide 0.5

Potassium hydroxide ^' to pH 12.5 Perfume 0.5

Smectite clay (sold under the tradename 10 Gelwhite HNF)

Water to 100%

Method

a) heat constituents of A to 70°C with mixing;

b) heat water, Fe³⁺ sequestrant, clay and 1,3-butylene -glycol to 7Q°C; c) add a) to b) with homogenisation;

d) disperse calcium hydroxide in a little water and add to c) .

e) cool to 30°C, add potassium thioglycolate soln. and adjust pH to 12.5 with potassium hydroxide;

f) add perfume.

Example 4

Depilatory (Aerosol Formulation;

Concentrate w/w

Water to 100%

^• Tri (hardtallow)amine 5

Liquid paraffin BP 3

20 ol ethoxylated cetyl alcohol A 1.5

Cetyl alcohol 0.5 White soft paraffin 3

Sodium metasilicate 0.5

Potassium thioglycolate (42%) soln. 14

Calcium hydroxide 0.5

Potassium hydroxide to pH 12.5 Smectite clay (sold under the trade 5 name Westone L)

Perfume 0.5

Method

a) disperse sodium metasilicate and clay in water at 70°C; b) heat constituents of A to 70°C with mixing;

c) add b) to a) and homogenise;

d) cool to 30°C and add potassium thioglycolate;

e) add calcium hydroxide and disperse;

f) add potassium hydroxide to pH 12.5;

g) add perfume.

Aerosol can fill:

Concentrate 90% w/w

Butane 40 10% w/w

Any suitable aerosol can, valve or actuator can be used.

The propellant may be replaced by any suitable chloro- fluorocarbon or hydrocarbon e.g. Arcton 12/114 40/60%, dimethyl ether or blends.

Example 5

The composition of Example 1 was prepared in which the 10% w/w smectite clay was replaced by 5% w/w kaolin clay (china clay) to give the depilatory cream of Example 5.

Claims

1. A depilatory composition comprising an effective amount of a depilatory compound and one or more smectite or kaolin clay, said composition having a pH of between about 11.5 and about 12.7.

2. A depilatory composition which comprises:

a) an effective amount of a depilatory compound;

b) one or more smectite or kaolin clay; and

c) a tertiary amine of general formula I:

in which R-_|_ represents a fatty moiety having 8 to 36 carbon atoms and R2 and R3 each independently represent a fatty moiety having 1 to 36 carbon atoms.

3. A depilatory composition as claimed in claim 2, in which R_]_ represents a straight chain aliphatic group having 8 to 36 carbon atoms and R2 and R each independently represent an alkyl group having 1 to 4 carbon atoms or a straight chain aliphatic group having 8 to 36 carbon atoms.

4. A depilatory composition as claimed in either of claims 2 and 3, in which at least two of the groups R-^, R2 and R3 each independently represent a straight chain aliphatic group having 16 to 24 carbon atoms.

5. A depilatory composition as claimed in claim 4, in which the tertiary amine of formula I is di(hardtallow) - ethylamine, distearylmethylamine or tri(hardtallow)- amine.

6. A depilatory composition as claimed in any of claims 2 to 5, containing from about 1% to about^{^}l0% w/w of a tertiary amine of formula I.

7. A depilatory composition as claimed in any preceding claim, which is in the form of a cream, lotion or aerosol.

8. A depilatory composition as claimed in any preceding claim, in which the depilatory compound is an alkali or alkaline earth metal salt of an alpha or beta- mercaptocarboxylic acid.

9. A depilatory composition as claimed in claim 8, in which the depilatory compound is potassium or calcium thioglycolate.

10. A depilatory composition as claimed in any preceding claim, containing from about 3% to about 10% w/w of depilatory compound.

11. A depilatory composition as claimed in any preceding claim, in which the smectite clay comprises one or more of bentonite, montmorillonite or hectorite.

12. A depilatory composition as claimed in any preceding claim, in which the smectite clay is bentonite.

13. A depilatory composition as claimed in any preceding claim, in which the clay contains less than about 1% w/w of heavy metal oxide or oxides.

14. A depilatory composition as claimed in Claim 13, in which the heavy metal oxide is iron oxide.

15. A depilatory composition as claimed in Claim 14, in which the iron oxide is in a form soluble in water.

16. A depilatory composition as claimed in any preceding claim, which contains from about 1% to about 10% w/w of clay.

17. A depilatory composition as claimed in any preceding claim, which contains 5% w/w of clay.