Cosmetic Composition

The invention relates to skin treating compositions and in particular to compositions which exert a moisturising effect on the skin, thereby softening the stratum corneum.

A soft and supple skin has a marked cosmetic appeal and is an attribute of normal functioning epidermis. The outer layer of the epidermis, i.e. the stratum corneum, can however become dry and flaky following exposure to adverse conditions due to loss of water with the result that the skin loses its soft supple characteristics. Emollients such as fats, phospholipids and sterols have in the past been used to soften dry skin, but more recently it has become apparent that these emollients are only partially effective as a remedy for this type of condition.

It is therefore evident that there exists a need for an effective treatment for skin which is in a dry, flaky condition.

Application to the skin of classical humectants is unlikely to alleviate this problem since they are generally rinsed from the skin during washing and for this reason they are not particularly skin substantive.

Even so, it has been proposed that urea can have a softening and moisturising action on dry, flaky skin when applied to the skin, for example as an aqueous solution or in the form of a cream. It does however suffer from the drawback that it tends to be unstable in products of this sort since it decomposes during storage with the release of ammonia.

We have now shown that the relatively short-lived softening and moisturising benefits of urea can be prolonged by employing instead of urea a special derivative thereof which is furthermore stable under conditions of storage and use and in particular does not breakdown with the release of ammonia.

Accordingly, the invention provides a composition for skin treatment comprising from 1 to 99% by weight of monoacetyl urea, together with a cosmetically acceptable vehicle other than water.

The invention is thus based on the discovery that monoacetyl urea can be applied to the skin, together with a suitable vehicle, in order to effect an improvement in the skin or to prevent a deterioration in the condition of the skin, as described herein.

Mono-acetyl urea should be present in the composition according to the invention as a solution, suspension or dispersion in liquid or solid form, depending upon the nature of the composition, but in any case the quantity present will lie between about 1% and 95%. Usually, when the composition is in the form of a liquid, the quantity of mono-acetyl urea will normally be from 1 to 20%, whereas when the composition is a solid such as a cosmetic stick, the proportion of mono-acetyl urea present will normally be from about 1% to about 50%, or even higher. Finely-divided powdered compositions can contain from 1% to 99% by weight of mono-acetyl urea.

It should be explained that use of less than 1% of monoacetyl urea by weight of the composition will not enable the user to obtain any noticeable benefit, whereas the above defined upper limits, depending on the type of composition, are more dictated by the nature of the formulation than by any upper limit to the efficacy of monoacetyl urea as a skin benefit agent.

Following the initial discovery that when mono-acetyl urea was applied to human skin, particularly skin in a dry or flaky condition, it was capable of moisturising, softening and otherwise improving the condition of the skin over a prolonged period, it was apparent that many different composition types could be formulated. For example, and without implying any limitation on the scope of the invention, it was realised that mono-acetyl urea could be incorporated in skin creams designed for application to the skin, in make-up products, particularly for application to the face. All such products could be designed either for the treatment of skin which was already in a dry or flaky condition or for prophylactic use in preventing such conditions occuring. It was further realised that mono-acetyl urea could be employed beneficially in other cosmetic products such as sunscreen products, hair treatment products and oral hygiene products, including mouthwashes and dentifrices.

It follows from this original concept that the provision of a vehicle for mono-acetyl urea in the products of the invention presents a wide range of possibilities. Suitable vehicles can be classified as described hereinafter.

It should be explained that vehicles are substances which can act as diluents, dispersants or carriers for mono-acetyl urea and which therefore ensure that it can be applied to and distributed evenly over the skin at an appropriate concentration; in certain cases, the vehicle can aid its penetration through the stratum corneum into the epidermis, thus ensuring that the effectiveness of the applied mono-acetyl urea is prolonged. It is not intended that water, which can act as a vehicle, is to be excluded; water can certainly be present in many of the compositions according to the invention, but it is intended that these compositions should also contain at least one vehicle other than water.

The vehicles that can be used in compositions according to the invention can include powder absorbents, binders and carriers, and liquids such as emollients, propellants, solvents, humectants and thickeners. Examples of each of these types of vehicles are as follows:

Magnesium silicate

Lanolin absorption base

Amorphous silica powder

Microcrystalline cellulose

Isostearyl neopentanoate

Polyacrylamide

Lauryl lactate

Precipitated silica

Talc

Chalk

Stearyl alcohol

Glyceryl monoricinoleate

Glyceryl monostearate

Sulphated tallow

Propylene glycol

Mink oil

Cetyl alcohol

Stearyl stearate

Isopropyl isostearate

Dimethyl brassylate

Stearic acid

Isobutyl palmitate

Isocetyl stearate

Oleyl alcohol

Isopropyl laurate

Hexyl laurate

Decyl oleate

Di-isopropyl adipate

2-octadodecanol

Iso-cetyl alcohol

Myristyl ethoxymyristate

Cetyl palmitate

Dimethylpolysiloxane

Di-isopropyl adipate

Di-n-butyl sabacate

Di-isopropyl sebacate

Di-2-ethyl hexyl sebacate

2-ethyl hexyl palmitate

Isononyl isononanoate

Isodecyl isononanoate

Isotridecyl isononanoate

2-ethyl hexyl palmitate

2-ethyl hexyl stearate

Di-(2-ethyl hexyl) adipate

Di-(2-ethyl hexyl) succinate

Isopropyl myristate

Isopropyl palmitate

Isopropyl stearate

Butyl stearate

Glyceryl monostearate

Polyethylene glycols

Propylene glycol

Triethylene glycol

Lanolin

Castor oil

Acetylated lanolin alcohols

Acetylated lanolin

Petrolatum

Isopropyl ester of lanolin fatty acids

Mineral oils

Butyl myristate

Isostearic acid

Palmitic acid

Isopropyl linoleate

Cetyl lactate

Lauryl lactate

Myristyl lactate

Quaternised hydroxy alkyl aminogluconate

Decyl oleate

Isodecyl oleate

Di-isopropyl adipate

2-ethyl hexyl palmitate

Isostearyl neo pentanoate

Myristyl myristate

Di-isopropyl adipate

Oleyl ethoxy myristate

Diglycol stearate

Ethylene glycol monostearate

Myristyl stearate

Isopropyl lanolate

Trichlorofluoro methane

Dichloro difluoro methane

Dichloro tetrafluoro ethane

Monochloro difluoro methane

Trichloro trifluoro ethane

Propane

Butane

Isobutane

(used singly or in admixture)

Ethyl alcohol

2-ethylhexanol

Ethylene carbonate

Propylene carbonate

N-methyl glucamine

Castor oil

Linear ethoxylated polymer of methanol

Ethylene glycol monoethyl ether

Diethylene glycol monobutyl ether

Diethylene glycol monoethyl ether

Propoxylated butanol

Propoxylated oleyl alcohol

Butyl stearate

Butyl myristate

Glycerin

Sorbitol

Sodium 2-pyrrolidone-5-carboxylate

Soluble collagen

Dibutyl phthalate

Gelatin

Polyglycerogen

Ethoxylated (10-20 moles) glucose

Propoxylated (10-20 moles) glucose

Gums

Starch

Colloidal silicon dioxide

Sodium polyacrylate

Tetra alkyl and/or trialkyl aryl ammonium smectites

Chemically modified magnesium aluminium silicate

Organically modified montmorillonite clay

Hydrated aluminium silicate

Fumed silica

Carboxy vinyl polymer

Sodium carboxymethyl cellulose

Hydrocyethyl stearate amide

Ethylene glycol monostearate

The quantity of vehicle employed can constitute the balance of the product, or a smaller proportion than the balance, provided that the vehicle is capable of performing, if necessary in admixture with other vehicles, its function as herein defined.

The compositions according to the invention can contain ingredients other than those already mentioned, depending on the form of the intended product. It is, for example, possible to include moisturisers, antiseptics or preservatives, antioxidants, anti-caking agents, emulsifiers, perfumes and colouring agents. Examples of some of the ingredients are as follows:

Sodium pyrollidone carboxylate

Sodium lactate

Orotic acid,

Cetyl pyridinium chloride

Triboromosalicylanilide

Benzalkonium chloride

Dehydroacetic acid,

Tocopherol

Ascorbyl palmitate

Propyl gallate

Butylated hydroxy toluene

Butylated hydroxyanisole

Hydrophobic starch

Sulphonated formaldehyde

Silicone dioxide

Potassium stearate

Sodium stearate

Ammonium stearate

Triethanolamine stearate

Glyceryl monostearate containing either potassium or sodium soap

Sodium lauryl sulphate

Sodium cetyl sulphate

Glyceryl monostearate containing sodium lauryl sulphate

N(stearoyl colamino formylmethyl) pyridinium chloride

N-soya-N-ethyl morpholinium ethosulphate

Alkyl dimethyl benzyl ammonium chloride Di-isobutylphenoxyethoxy ethyl dimethyl benzyl ammonium chloride

Cetyl pyridinium chloride; and

Fatty acid esters of sorbitan anhydrides or ethylene oxide products of sorbitan fatty acid esters such as Span 80 or Tween 80; and pluronics which are addition products of hydrophilic polyoxy ethylene groups and a hydrophilic polyoxy propylene.

The amount of emulsifiers, if used, usually forms from 1 to 10%, preferably 1 to 5% by weight of the composition.

The benefit to the skin following topical application of the compositions can be assessed by measuring the impedence of the skin before and after application.

Thus, we have found that skin which has received a topical application of such a composition has a lower impedience than untreated skin, thus indicating that the treated skin has become moisturised by this treatment.

One method of measuring skin impedence that can be employed is that described by E J Clar, C P Her and C G Sturelle in the "Journal of the Society of Cosmetic Chemists" for July 1975, Volume 26, No 7 at pages 337-353.

An example illustrating the technique employed in this test and some sample results obtained is set out below.

The ability of a substance to moisturise the skin is assessed by impedence which occurs on the skin which has been treated by the substance.

In this experiment, impedence measurements were made under controlled atmospheric conditions of 66% relative humidity at a temperature of 23.degree. C. The test compared the effectiveness of three skin moisturisers each dissolved in N-methylglucamine against a control containing only this solvent.

The following solutions were compared:

Each of the solutions A to E was applied to a different area of skin; a further zone of skin (F) was demarcated as a control which received no treatment.

Rats were used as the test animals for evaluation of the efficacy of each solution. The experiments were statistically designed on the basis of a 6 .times. 6 latin square and Duncan Method (see Duncan DB, Biometrics, March 1975 page 1) was used to evaluate the results.

The mean impedence results obtained by using the method of Clar et al referred to above were as follows:

The analysis of variance can be summarised as follows:

The following table sets out an interpretation of the results according to Duncan.

Note that any two mean values underlined are not significantly different from each other.

From these results, it is accordingly possible to distinguish two groups of products, the first group comprising urea pyrollidone carboxylate (2%), the solvent, the untreated skin zone, the the second group comprising urea pyrollidone carboxylate (2%), urea (5%) and acetyl urea (2%). Only urea (5%) and acetyl urea (2%) as an aqueous solution in N-methyl glucamine produced a significant fall in impedence as compared with the controls.

It is also apparent that mono acetyl urea at a concentration of 2% has virtually the same effectiveness as a skin moisturiser as urea at a concentration of 5%.

The invention will now be illustrated by reference to the following examples.

This example illustrates the preparation of make-up powder.

A water phase was prepared by mixing together the following ingredients.

An oil phase was similarly prepared by mixing together the following ingredients.

To 100 parts of the water phase was added 9 parts by weight of the oil phase at a temperature of 10.degree. C. A white precipitate formed. The following ingredients were then added and the whole blended to form a make-up powder.

This example illustrates the preparation of an aerosol lotion.

The following ingredients were employed to form an aerosol lotion.

Add B to A at 75.degree. C. Cool with agitation to 45.degree. C then add alcohol. Pressure fill and add perfume to suit.

This example illustrates the preparation of a face cream.

The face cream was prepared from the following ingredients.

This example illustrates the formulation of a sunscreen cream.

The following ingredients were blended to form a sunscreen cream.

This example illustrates the preparation of the formulation of a handcream.

The following ingredients were blended to form a hand cream.

This example illustrates the formulation of a lipstick.

The following ingredients were blended to form a lipstick.

This example illustrates the formulation of an all-purpose mask.

The following ingredients were blended to form an all-purpose mask.

This example illustrates the formulation of a toothpaste.

The following ingredients were blended to form a toothpaste.

This example illustrates the formulation of a skin milk.

The following ingredients were blended in order to form a skin milk.