Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1998-08-27
2001-05-08
Dudash, Diana (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S063000, C424S064000, C424S070100, C424S070700, C424S070130, C514S844000, C514S845000, C514S846000, C514S938000
Reexamination Certificate
active
06228377
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a water-in-oil emulsion and its use in the cosmetics, dermatological, veterinary and/or agrifood fields, particularly in the form of a white or colored cream to care for, make up, remove make-up from, and/or provide antisun protection to human skin and/or mucous membranes, as well as to prepare a cream for the treatment of skin diseases and/or mucous membrane diseases.
2. Discussion of the Background
In the cosmetics field, it is common to use creams consisting of a water-in-oil (W/O) emulsion containing an aqueous phase dispersed in a liquid fatty phase (generally referred to as the oily phase). These emulsions contain an oily continuous phase and thus allow a lipid film to be formed on the surface of the skin to prevent transepidermal water loss and protect the skin against external attack. The emulsions are particularly suitable for protecting and nourishing the skin, and in particular for treating dry skin.
These emulsions frequently have stability problems, making them difficult to manufacture. Various means have been proposed to overcome this drawback. One known means consists of incorporating into the emulsion a large amount of emulsifying surfactant, which can be up to 10% by weight relative to the total weight of the emulsion. However, it is known that emulsifiers used in large amounts can be irritating towards certain types of skin. Moreover, the creams obtained are often compact and heavy. In addition, the surfactants need to be chosen as a function of the polarity of the oils and are thus only compatible with a limited number of oils, limiting the variety of the formulations.
SUMMARY OF THE PRESENT INVENTION
Accordingly, one object of the present invention is to provide a water-in-oil emulsion which does not have the above mentioned drawbacks and which contains a reduced amount of emulsifying surfactant.
Thus, the Applicant has found, surprisingly, that it is possible to obtain a water-in-oil emulsion having good cosmetic properties and good stability by using a specific combination of thickener for the oily phase.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to a water-in-oil emulsion containing a liquid fatty phase, wherein the liquid fatty phase contains at least fumed silica and at least one polysaccharide alkyl ether formed of units containing at least two different saccharide rings, wherein each unit of the polysaccharide alkyl ether contains at least one hydroxyl group substituted with a saturated hydrocarbon-based alkyl chain, and from 0% to 5% by weight, relative to the total weight of the emulsion, of at least one emulsifying surfactant, wherein the liquid fatty phase contains at least one medium which is a solvent for the polysaccharide alkyl ether.
Due to the combination of fumed silica and polysaccharide alkyl ether, the emulsion according to the present invention is stable despite the low amount, or even absence, of emulsifying surfactant. In the present invention composition, the aqueous phase preferably disperses perfectly in the liquid fatty phase. The emulsion obtained is easy to apply to the skin or to mucous membranes and gives a soft, fresh and comfortable sensation when applied.
Depending on the percentage of thickener used, an emulsion of more or less fluid texture can be obtained. The expression “emulsion of fluid texture” is understood to mean an emulsion which flows under its own weight and has a viscosity of from about 2 to 15 poises, i.e. from 0.2 to 1.5 Pa.s. Conventional emulsions have a viscosity of about 20 to 80 poises, i.e. from 2 to 8 Pa.s. The emulsion according to the present invention has the advantage of being able to be fluid, creamy and comfortable while at the same time having good stability for one month at room temperature.
By comparison with the emulsion according to the present invention, it has been observed that an emulsion which is similar but comprises only one thickener (fumed silica or polysaccharide alkyl ether) has a coarser and less stable dispersed aqueous phase than the emulsion of the present invention.
The addition of polysaccharide alkyl ether makes it possible to reduce the coarse appearance of an emulsion whose oily phase is thickened with fumed silica alone.
Thus, another subject of the invention is the use of a polysaccharide alkyl ether formed of units containing at least two different saccharide rings, each unit containing at least one hydroxyl group substituted with a hydrocarbon-based chain and fumed silica, to stabilize a water-in-oil emulsion.
In the thickener combined with the fumed silica according to the invention, the term “hydrocarbon-based chain” is understood to refer to a linear or branched chain containing from 1 to 24, preferably from 1 to 10, better still from 1 to 6 and more especially from 1 to 3, carbon atoms optionally containing from 1 to 4 C=C bonds. Preferably, the hydrocarbon based chain includes methyl, ethyl, ethenyl, n-propyl, propenyl, isopropyl, n-butyl, isobutyl, tert-butyl and n-pentyl. These alkyl ethers can be manufactured as described in documents EP-A-281.360 and EP-A 708,114, the contents of which are hereby incorporated by reference.
According to a preferred embodiment of the invention, the polysaccharide alkyl ether has a weight-average molecular weight of greater than 100,000, and preferably greater than 200,000. This molecular weight can preferably be up to 1 million. This alkyl ether can contain from 1 to 6, and better still from 2 to 4, hydroxyl groups per unit, substituted with a saturated or unsaturated hydrocarbon-based chain.
The saccharide rings are preferably chosen from mannose, galactose, glucose, faranose, rhamnose and arabinose.
According to a preferred embodiment of the invention, the polysaccharide alkyl ether is an alkyl ether of a gum, and more preferably of a gum which is nonionic overall, i.e. one which contains few or no ionic groups. As appropriate gums, mention may be made, for example, of guar gum, in which the unit comprises a galactose and a mannose, carob gum, in which the unit comprises a galactose and a mannose, karaya gum, which is a complex mixture of rhamnose, galactose and galacturonic acid, and gum tragacanth, which is a complex mixture of arabinose, galactose and galacturonic acid.
According to a preferred embodiment of the invention, the polysaccharide alkyl ether is a guar gum derivative. Thus, preferably, the alkyl ether is an alkyl galactomannan with a C
1
to C
6
, and better still C
1
to C
3
, alkyl chain and more preferably ethyl guar having a degree of substitution of from 2 to 3, and most preferably from about 2.5 to 2.8, as described in the documents RD 95378007 (October 1995) and EP-A-708,114. This gum is sold in particular by the company Aqualon under the names N-Hance-AG 200® and N-Hance AG 50®.
Advantageously, the polysaccharide alkyl ether can be present in an amount such that the ratio (by weight) of the amount of oil to the amount of polysaccharide alkyl ether is chosen in the range from 5 to 1000.
Preferably, the polysaccharide alkyl ether is present in the liquid fatty phase of the emulsion at an active material concentration ranging from 0.1 to 16% by weight relative to the total weight of the emulsion, and more preferably from 0.2 to 5% by weight.
The fumed silica which can be used in the composition according to the present invention is preferably a fumed silica, which can be in the form of hydrophilic fumed silica or hydrophobic fumed silica.
The fumed silicas can be obtained, for example, by high-temperature hydrolysis of a volatile silicon compound in an oxyhydrogen flame, producing a fmely divided silica. This process makes it possible in particular to obtain hydrophilic silicas which have a large number of silanol groups at their surface. Such hydrophilic silicas are sold, for example, under the tradenames “Aerosil 130®”, “Aerosil 200®”, “Aerosil 255®”, “Aerosil 300®”, “Aerosil 380®” by the company Degussa and “CAB-O-SIL HS-5®”, “CAB-O-SIL EH-5®”, “CABO-SIL LM-130®”, “CAB-O-
Berman Alysia
Dudash Diana
L'Oreal
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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