Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2000-10-23
2002-06-25
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S060000, C424S400000, C424S401000
Reexamination Certificate
active
06409998
ABSTRACT:
CROSS-REFERENCE TO PRIORITY APPLICATION
This application claims priority under 35 U.S.C. §119 of FR-99/13220, filed Oct. 22, 1999, hereby expressly incorporated by reference.
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to novel cosmetic/dermatological emulsions comprising at least one photoprotective system/agent suited for screening out UV-irradiation, containing at least one organic UV-screening agent insoluble in such emulsions, in micronized form or state, in which the mean size of the particles ranges from 0.01 to 2 &mgr;m, and also comprising at least one associative polymer characteristically different from, or other than a C
8
-C
16
alkyl polyglucoside.
The present invention also relates to cosmetic/dermatological compositions suited for the photoprotection of the skin or of the hair.
2. Description of the Prior Art
It is known to this art that light radiation of wavelengths of from 280 nm to 400 nm permits tanning of the human epidermis, and that radiation of wavelengths more particularly of from 280 nm to 320 nm, i.e., UV-B radiation, causes erythemas and skin burns which can hinder the development of natural tanning.
For these reasons as well as for aesthetic reasons, there is a constant demand to control this natural tanning such as to thereby control the color of the skin; it is therefore advisable to screen out UV-B radiation.
It is also known to this art that UV-A radiation of wavelengths of from 320 nm to 400 nm, which promotes tanning of the skin, also is capable of causing damage thereto, in particular in the case of a sensitive skin or of a skin continually exposed to solar radiation. UV-A radiation, causes, in particular, loss of elasticity of the skin and the appearance of wrinkles which promotes premature skin aging. UV-A radiation promotes the onset of the erythema reaction or amplifies this reaction in certain individuals and may even be responsible for phototoxic or photoallergic reactions. Thus, for aesthetic and cosmetic reasons such as the preservation of the natural elasticity of the skin for example, an increasing number of individuals seek to control the effect of UV-A radiation on their skin. It is therefore desirable to also screen out UV-A radiation.
A wide variety of cosmetic compositions intended for the photoprotection (UV-A and/or UV-B) of the skin are also known to this art.
These anti-sun or sunscreen compositions are quite often provided in the form of an emulsion, of the oil-in-water (O/W) type (namely, a cosmetically and/or dermatologically acceptable carrier comprising an aqueous dispersing continuous phase and a fatty dispersed discontinuous phase) or of the water-in-oil (W/O) type (dispersed aqueous phase in a continuous fatty phase), which contains, at various concentrations, one or more lipophilic conventional organic UV-screening agents and/or inorganic nanopigments of metal oxides, which are suited for selectively absorbing the harmful UV radiation, these screening agents (and the quantities thereof) being selected according to the desired sun protection factor (the sun protection factor (SPF) being mathematically expressed by the ratio of the irradiation time required to attain the erythematogenic threshold with the UV-screening agent to the time required to attain the erythematogenic threshold in the absence of UV-screening agent). In such emulsions, the hydrophilic screening agents are present in the aqueous phase and the lipophilic screening agents are present in the fatty phase.
The oil-in-water emulsions are, in general, more accepted by the consumer than the water-in-oil emulsions because, in particular, of their pleasant feel (similar to water) and their presentation in the form of a non-oily cream or milk; however, they also more readily lose their UV protection efficacy as soon as they come into contact with water. Indeed, the hydrophilic screening agents tend to disappear in water, upon washing in the sea or in a swimming pool, under the shower or when engaged in water sports; thus, anti-sun or sunscreen compositions containing same, whether alone or combined with lipophilic screening agents, no longer provide the desired initial protection as soon as the substrate (skin or hair) to which they have been applied is contacted with water.
Anti-sun (sunscreen) compositions exhibiting improved resistance to water have been formulated as water-in-oil emulsions. Indeed, a hydrophilic screening agent is more stable to water in a water-in-oil emulsion than in an oil-in-water emulsion. However, as indicated above, such compositions are not yet completely satisfactory since they promote, after application, a fat-like impression which is particularly unpleasant for the user.
Thus, serious need continues to exist for anti-sun or sunscreen compositions which impart to the skin and/or the hair effective solar protection which is stable over time and resistant to water (stability to water) and the cosmetic performance of which presents features that would be comparable to those obtained with conventional oil/water emulsions.
SUMMARY OF THE INVENTION
It has now surprisingly and unexpectedly been determined that specific emulsions containing at least one organic UV-screening agent insoluble in micronized form in the different phases of these emulsions and at least one associative polymer not only provide anti-sun compositions whose cosmetic performance features are comparable to those generally associated with a conventional sunscreen composition formulated as an oil/water emulsion, but also exhibit good stability as well as enhanced stability to water.
These discoveries constitute the basis of the present invention.
Briefly, the present invention features cosmetic/dermatological emulsions comprising at least one photoprotective system or agent adopted for screening out UV radiation, containing at least one organic UV-screening agent insoluble in such emulsions, in micronized form, in which the mean size of the particles ranges from 0.01 &mgr;m to 2 &mgr;m, but also comprising at least one associative polymer characteristically different from, or other than a C
8
-C
16
alkyl polyglucoside.
DETAILED DESCRIPTION OF BEST MODE AND SPECIFIC/PREFERRED EMBODIMENTS OF THE INVENTION
More particularly according to the present invention, by “cosmetic or dermatological emulsion” is intended any emulsion in which the aqueous phase and the fatty phase contain substances or substrates which are cosmetically or dermatologically acceptable for topical application onto human keratinous materials including the skin, the hair, the eyelashes, the eyebrows, the lips, the nails or the mucous membranes.
By “insoluble organic UV-screening agent” is intended according to the present invention organic UV-screening agents which are insoluble in the cosmetic media generally included in anti-sun formulations and more particularly whose solubility in water at 25° C. is less than 0.1% by weight and whose solubility in paraffin oil at 25° C. is less than 1% by weight.
By “photoprotective system suited for screening out UV radiation” is intended any system including one or more organic compounds and/or inorganic compounds screening out UV-A and/or UV-B radiation.
And by “associative polymer” is intended any amphiphilic polymer comprising in its structure at least one fatty chain and at least one hydrophilic moiety.
The present invention thus features formulating the subject emulsions into cosmetic compositions for the protection of the skin and/or of the hair against ultraviolet radiation, in particular solar radiation.
The insoluble organic screening agents according to the invention are provided in micronized form. The mean or average size of the particles ranges from 0.01 &mgr;m to 2 &mgr;m and more preferably from 0.02 &mgr;m to 1.5 &mgr;m and even more preferably from 0.05 &mgr;m to 1.0 &mgr;m.
The insoluble organic screening agents according to the invention may be provided in the desired particulate form by any appropriate means such as, in particular, grinding in the dry state or in solvent medium, sieving,
Candau Didier
Forestier Serge
Pisson Anne-Marie
Dodson Shelley A.
Societe L'Oreal
LandOfFree
UV-photoprotecting emulsions comprising micronized insoluble... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with UV-photoprotecting emulsions comprising micronized insoluble..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and UV-photoprotecting emulsions comprising micronized insoluble... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2891010