IE42768B1 - Depilatory compositions - Google Patents

Abstract

1484792 Depilatory packs BEECHAM GROUP Ltd 22 Jan 1976 [30 Jan 1975] 4044/75 Heading A5B A depilatory pack comprises a first region containing a viscous, flowable, aqueous composition and a second region, separate from the first, containing a viscous, flowable, non- aqueous composition having finely divided calcium oxide dispersed therein, one or both of said aqueous and non-aqueous compositions containing an active depilatory agent or each of said aqueous and non-aqueous compositions containing reagents which, when brought into contact, react to produce an active depilatory agent, said aqueous and non-aqueous compositions being substantially miscible to produce a dermatologically acceptable depilatory composition, the pack comprising means for dispensing and mixing or bringing into contact the aqueous and non-aqueous compositions from said first and second regions.

Description

This invention relates to depilatory compositions, and in particul to compositions containing ingredients which, when mixed, generate heat, thereby increasing the temperature. of the entire depilatory composition and increasing the rate of depilation.

Many depilatory compositions ‘have been proposed in the literature and several are available commercially. One drawback of the majority of previously proposed compositions is their relatively slow rate of action. Xt is usually necessary to leave the composition in contact with the skin for many minutes, usually about 10 minutes, to attain good results.

The action of current depilatory compositions is based on the use of metal salts of thio compound such as thioglycollic acid and thioglycerol. .The speed of action of such compositions depends upon (a) the pH of the formulation (usually about 12) (b) the i concentration and identity of the thio compound (usually about ' t « 3-6%) (c) the identity of the metal ion (usually sodium, potassi; ’ I lithium, calcium, barium or strontium). The speed of the depilation can be increased (a) by raising the pH, (b) increasing the concentration of the thio compound or (c) using a sodium, potassium or lithium salt instead of a calcium, barium or stront salt. Unfortunately, it is not possible to proceed far in any o these directions without encountering serious skin irritation problems.

As might be expected, the speed of depilation of a thio compound increases with increasing temperature. This fact is exploited i compositions such as those proposed in British Patent Specificat - 2 42768 No. 1,329,029 which describes a self-heating depilatory ocmposition vhose action depends on the in situ generation of an active depilatory compound by the exothermic reaction of two ingredients, normally kept separate, but which are mixed prior to or during application to the skin. It is said that the exothermic reaction raises the temperature of the composition and thus increases depilation speed. Such compositions are not entirely satisfactory however, since the range of compounds which react to produce dermatologically acceptable depilatory compounds, with the evolution of sufficient heat to raise significantly the temperature of the entire formulation, is extremely limited. Additionally, the problem of accurate co-dispensing of the two separate parts of the formula necessary to produce optimum results is very critical. For example, an excess of free thio acid results in an inefficient depilatory and an excess of alkali gives rise to irritation problems.

In principle it would be much more satisfactory if the intended self-heating depilatory formulation could contain an active depilatory from the outset, as well as additional ingredients which when mixed react exothermically. In this way the most suitable depilatory agent and most suitable heat-producing reagents could be chosen without having to compromise on the properties of each. Additionally the problem of accurate co-dispensing would be much less critical.

Unfortunately, the only heat-producing systems proposed in the past for use in topical compositions are oxidation-reduction systems and acid-base neutralisation systems. The first of these is not appropriate for depilatory compositions since the depilatory thio compounds themselves are reducing agents and are consumed by the complementary oxidising agent. Acid-base neutralisation is also an unsatisfactory way of producing heat in a depilatory system since the temperature achieved with dermatologically acceptable acids and bases is usually not great enough to increase depilation speeds.

This invention is based on the use, in a depilatory formulation, .0 of a heat-producing reaction which has not previously been proposed for use'in topical toiletry and cosmetic compositions, namely the reaction of calcium oxide with water to produce calcium hydroxide, a dermatologically acceptable compound alreac present in most depilatory formulations as an auxiliary alkali •5 to control pH. We find that, provided precautions are taken to ensure adequate mixing of the calcium oxide and water, this system can give a very good temperature rise over a period of a minute or two, and significantly reduces depilation times.

Unlike the oxidation/reduction system and acid/base neutralisati iq system - accurate co-dispensing of the two components is not so critical as under no circumstances will the depilation time be slower that that of the existing depilatory component.

Accordingly, the present invention provides a pack comprising a first region containing a viscous, flowable, aqueous compositior !5 and a second region, separate from the first, containing a viscous, flowable, non-aqueous composition having finely dividec - 4 42768 calcium oxide dispersed therein, one or both of said aqueous and non-aqueous compositions containing an active depilatory agent or each of said aqueous and non-aqueous compositions containing reagents which, when brought into contact, react to produce an active depilatory agent, said aqueous and non-aqueous compositions being substantially miscible to produce a dermatologically acceptable depilatory composition, the pack comprising means for dispensing and mixing or bringing into contact the aqueous and non-aqueous compositions from said first and second regions.

The pack of this invention in its simplest form consists of two separate reservoirs such as collapsible tubes, one containing the aqueous liquid, the other containing the non-aqueous liquid.

Xn this case, the means for dispensing and bringing into contact would simply be the dispensing orifices of the two reservoirs. The user would simply dispense some of each composition from each reservoir and mix the two either in situ on the use area or in some mixing area prior to application to the use area. s A preferred form of pack according to this invention is the tubewithin-a-tube. This device consists of two collapsible tubes, one within the other with a common dispensing nozzle, partitioned so that one half of the common dispensing nozzle communicates only with the interior of the outer collapsible tube and the other half only with the interior of the inner collapsible tube.

When both tubes are filled, one with the aqueous, the other with the non-aqueous composition, pressure on the outer tube results in transmitted pressure through to the inner tube and the - 5 42768 simultaneous extrusion of both compositions through the common nozzle. In this case, it is clear that the means for dispensin and mixing or bringing into contact would be the common dispensing nozzle. The user would be encouraged to mix the aqueous and non-aqueous compositions in situ on the skin bygentle rubbing with the finger during the normal course of application.

The aqueous and non-aqueous compositions in. the pack of this invention must be substantially miscible. This is essential to achieve intimate contact of the calcium oxide suspended in th non-aqueous composition with the water present in the aqueous composition, so that the required degree of heating is achieved. Naturally, the degree of heating achieved will depend on several factors, notably the concentration of calcium oxide and the specific heat of the combined compositions. We have found that the self-heating characteristics of the mixed compositions varies widely with the identity of the liquid base of the nonaqueous composition. It is, of course, a fairly routine matter to test various organic liquids till one having the required properties is obtained. We find that mineral oil is a good base for the non-aqueous vehicle, but in this case it is necessary tc include an emulsifier in the oil/calcium oxide composition to improve the miscibility with the aqueous composition.

It is necessary that the aqueous and non-aqueous compositions should be viscous, but flowable. This requirement follows from the necessity to ensure the calcium oxide remains in suspension (requiring a· viscous liquid, preferably a gelled liquid) but als that the compositions are easily dispensed. If the non-aqueous composition is to be a viscous liquid, the aqueous composition should have approximately the same viscosity characteristics to ensure even mixing and dispensing. Hence, if the liquid base chosen for the non-aqueous composition is not sufficiently viscous to support a stable dispersion of the calcium oxide, a thickening agent such as finely divided silica may have to be added, and the viscosity of the aqueous composition may have to be adjusted to match that of the thickened non-aqueous composition.

An active depilatory agent may be present in one or both of the aqueous and non-aqueous compositions. Alternatively, each of the aqueous and non-aqueous compositions can contain reagents which when mixed, produce an active depilatory. Active depilatory agents include sulphides such as strontium sulphide, substituted mercaptans, particularly the metal salts of thioglycollic acid mentioned earlier, and keratinase enzyme. Examples of two reagents which react to produce an active depilatory compound include sodium hydroxide and thioglycollic acid. When a metal salt of thioglycollic acid is chosen as the active depilatory agent, it is of course well known that the pH of the resultant total depilatory composition must be in the range 10.0 to 12.5, since outside this range the metal thioglycollate is not noticably active. Since the end product of the reaction of water with calcium oxide is calcium hydroxide - a mild alkali the amount of additional alkali such as sodium hydroxide necessary for the required pH range will have to be adjusted accordingly.

The aqueous and non-aqueous compositions must be miscible to - 7 42768 produce a dermatologically acceptable depilatory composition. Thus, the ingredients of the agueous and non-aqueous composition other than those mentioned already (calcium oxide, non-aqueous viscous carrier, active depilatory and, if necessary, auxiliary alkali) must be chosen so as to be non-irritant and safe at tlie prevailing condition's, thus emulsifiers, humectants, perfumes, and other conventional depilatory additives may be present in either the aqueous or non-aqueous compositions, subject to compatability- of .course. .0 We find that generally satisfactory results in accordance with this invention are achieved when a standard aqueous-based depilatory formulation such as is known to most cosmetics formulations chemists is employed as the aqueous composition, an a dispersion of calcium oxide in a gelled mineral oil base -5 containing an emulsifier such as lauryl alcohol ethoxylate is employed as the non-aqueous composition, with the viscosities of the two compositions being as closely matched as possible.

The following Example illustrates the present invention:BXAHPLE: Non-aqueous component % w/w Light Mineral Oil 36.00 Calcium Oxide 60.00 Finely-divided silica 1.00 25 Lauryl·alcohol ethoxylate 3.00 100.00 - 8 42 7 68 Aqueous component % w/w Thioglycollie acid 4.50 Potassium hydroxide 3.30 Calcium hydroxide 3.70 Sodium silicate 3.50 Calcium carbonate 4.00 Cetyl alcohol 5.50 Lauryl alcohol ethoxylate 3.00 Cetomacrogol emulsifying wax 4.00 Perfume 1.00 Water 67.50 100.00 Using the Depilometer described in J.S.C.C. 25, p.367-377,we 15 have found that the time of depilation of the above compositions, when mixed, is about 3 minutes faster than that of the same compositions without the calcium oxide.

' The above non-aqueous and aqueous components were separately filled into the two compartments of a tube-within-a-tube where they remained stable and effective for several months.

Claims (2)

1. CLAIMS:1. A pack comprising a first region containing a viscous, flowable, aqueous composition and a second region, separate from the first, containing a viscous, flowable, non-aqueous composition having finely divided calcium oxide dispersed therein, one or 5 both of said aqueous and non-aqueous compositions containing an active depilatory agent or each of said aqueous and nonaqueous compositions containing reagents which, when brought into contact, react to produce an active depilatory agent, said aqueous and non-aqueous compositions being substantially miscible LO to produce a dermatologically acceptable depilatory composition, the pack comprising means for dispensing and mixing or bringing into contact the aqueous and non-aqueous compositions from said first and second regions.

2. A pack as claimed in claim 1 in the form of two collapsible 15 tubes, one within the other, having a common dispensing nozzle, partitioned so that one half communicates only with the interior of the outer collapsible tube and the other half communicates only with the interior of the inner collapsible tube.