Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1999-09-15
2002-03-26
Dees, Jose′ G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S064000, C514S937000
Reexamination Certificate
active
06361781
ABSTRACT:
The present invention relates to a composition which is provided in the form of an emulsion capable of being used in the cosmetics and dermatological fields, in particular for caring for or treating the skin of the body or of the face, more particularly for caring for or treating dry or sensitive skin. The invention also relates to a cosmetic or dermatological composition comprising such an emulsion.
Current cosmetic or dermatological compositions are generally provided in the form of an emulsion of the oil-in-water type (that is to say, a vehicle composed of a continuous aqueous dispersing phase and of a non-continuous oily disperse phase) or of an emulsion of the water-in-oil type (that is to say, a vehicle composed of a continuous fatty dispersing phase and of a non-continuous aqueous disperse phase).
Water-in-oil emulsions therefore comprise a continuous oily phase and make possible the formation, at the surface of the skin, of a lipid film which prevents transepidermal water loss and protects the skin from external attacks. These emulsions are particularly appropriate for protecting and nourishing the skin and in particular for treating dry skin.
Oil-in-water emulsions, for their part, contribute to the skin, on application, a softer, less greasy and lighter feel than water-in-oil emulsions.
Emulsions are generally stabilized by incorporation of emulsifying surfactants of the oil-in-water (O/W) type or of the water-in-oil (W/O) type which, by virtue of their amphiphilic structure, become positioned at the oil/water interface and thus stabilize the dispersed droplets. It is generally necessary to introduce these surfactants in a large amount, which can range up to 10% by weight with respect to the total weight of the emulsion, in order to obtain adequate stability.
In point of fact, these amphiphilic surfactants, used in large amounts, can prove to be irritating to the skin, eyes and/or scalp of the user. Furthermore, their presence at high concentrations can result in non-cosmetic effects, such as a rough, clinging and/or sticky feel, or a compact and heavy final composition. Furthermore, the surfactants must be chosen according to the polarity of the oils and are therefore only compatible with a limited number of oils, thus limiting the variety of the formulations.
Formulators of emulsions are constantly seeking to reduce the content of surfactant in order to improve the harmlessness of the emulsions with regard to the skin, eyes and/or scalp and to improve their cosmetic properties. The main difficulty with which they are generally confronted is to obtain stable emulsions.
Application WO 96/37180 has thus provided a composition capable of applications in the pharmaceutical and/or cosmetics fields which is provided in the form of a “pseudoemulsion” and is devoid of surfactant. The composition comprises, on the one hand, in the aqueous phase, a gelling agent chosen in particular from polyoses or acrylic polymers and, on the other hand, in the fatty phase, a consistency factor chosen from waxy fatty substances and in particular glycerol esters. The consistency factor present in the fatty phase is a substance which is semisolid at 25° C. and has a melting point of greater than 50° C.; it is dissolved under warm conditions in the fatty phase and then recovers its starting semisolid consistency under cold conditions, conferring a degree of consistency and a degree of viscosity on the fatty phase. The composition thus obtained exhibits a microscopic structure different from that of an emulsion.
However, it has been found that, beyond a certain amount of fatty phase, the pseudoemulsion loses stability, under warm conditions and/or over time. This is particularly true for levels of fatty phase of greater than 20% by weight with respect to the total weight of the pseudoemulsion. In point of fact, a high level of fatty phase in an O/W emulsion can prove to be highly advantageous, in particular for cosmetic compositions intended for the care of dry skin. Furthermore, the cosmetic properties of this pseudoemulsion are inadequate: its texture is heterogeneous, its feel greasy, and uptake with the finger is found to be poor.
There therefore still remains the need to have available an O/W emulsion which is stable over time, although it does not comprise a surfactant, and which can comprise a large amount of fatty phase without losing its stability.
The aim of the present invention is to alleviate this need and to provide an emulsion, in particular an O/W emulsion, which can avoid the disadvantages mentioned above and which can be stable while comprising a reduced amount of surfactant and which can tolerate a large amount of fatty phase.
The inventor has found, surprisingly, that it is possible to obtain an emulsion having good cosmetic properties and good stability by using a specific combination of thickeners of the oily phase and of the aqueous phase.
The subject-matter of the present invention is therefore an emulsion comprising an aqueous phase and an oily phase and additionally comprising at least one hydrophilic thickening compound and at least one lipophilic thickening copolymer comprising at least one hydrophobic unit in an amount sufficient to obtain its partial or complete solubility in the oily phase and at least one hydrophilic unit in an amount sufficient to produce thickening of the oily phase; the hydrophilic unit being chosen from C
3
-C
6
monocarboxylic acids with &agr;,&bgr;-ethylenic unsaturation, C
4
-C
6
dicarboxylic acids with &agr;,&bgr;-ethylenic unsaturation, and the monoester or monoamide derivatives of the diacids.
Another subject-matter of the invention is a cosmetic or dermatological composition comprising, in a cosmetically or dermatologically acceptable medium, an emulsion as defined above.
Another subject-matter of the invention is the use of an emulsion as defined above for the cosmetic treatment of the skin, hair, eyelashes, eyebrows, nails, mucous membranes or scalp; in particular, for caring for the face and/or body, making up the face and/or body, removing make-up, or antisun protection.
Another subject-matter of the invention is the use of such an emulsion in the manufacture of a dermatological composition intended for the treatment of the skin, hair, eyelashes, eyebrows, nails, scalp and/or mucous membranes.
Another subject-matter of the invention is a process for the nontherapeutic treatment of the skin, in particular dry and/or sensitive skin, hair, eyelashes, eyebrows, nails, mucous membranes or scalp which comprises applying, to the substrate, such an emulsion or a composition comprising it.
Another subject-matter of the invention is the use of a hydrophilic thickening compound and of a lipophilic thickening copolymer as defined above for stabilizing an emulsion, in particular an oil-in-water emulsion, and more particularly an emulsion not comprising surfactant.
It has been found that the emulsion obtained according to the invention remains stable over time at room temperature or at higher temperatures, despite the low amount, indeed even the absence, of surfactant.
Furthermore, in the case of an oil-in-water emulsion, the fatty phase is completely dispersed in the aqueous phase and makes it possible to obtain a homogeneous composition having the microscopic structure of an emulsion.
The emulsion obtained is easy to apply to the skin, mucous membranes, scalp, hair, eyelashes, eyebrows or nails.
The textures obtained are particularly original: the emulsions are creamy and smooth and are entirely free from the gelled, indeed even gelatinous, appearance of some emulsions of the prior art, the external aqueous phase of which is thickened.
The cosmetic feel on the skin is also appreciated: on application, the emulsion provides a feeling of freshness and of comfort while being rich and nourishing; it is soft and comfortable and not in any way clinging.
The emulsion thus obtained is particularly suited to caring for and treating dry and/or sensitive skin, through the possibility of the presence of a large amount of fatty substance contributing car
Dees Jose′ G.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
George Konata M.
L'Oreal (S.A.)
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