Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Silicon containing doai
Patent
1993-04-23
1998-03-31
Chang, Ceila
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Silicon containing doai
514844, 424 59, 424 60, 424 63, 424 70, 424 81, 424401, 423 211, 423608, 423610, 423622, 556443, 556453, A61K 742, A61K 31695
Patent
active
057338957
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/FR92/0084 filed Aug. 25, 1992.
The subject of the present invention is a composition for screening out ultraviolet radiation, comprising, in association, at least one nanopigment of metallic oxide and at least one UV-screening fat-soluble polymer.
It is known that light radiation with wavelengths of between 280 and 400 nm permit the tanning of the human epidermis and that rays with wavelengths of between 280 and 320 nm, known by the name UV-B, also cause erythemas and skin burns which can hamper the development of the tan.
However, while UV-B rays with wavelengths of between 280 and 320 nm play a preponderant part in the production of solar erythema and must be screened out, it is nevertheless a fact that UV-A rays with wavelengths of between 320 and 400 nm which cause tanning of the skin are also capable of inducing its degradation especially in the case of a sensitive skin or a skin continuously exposed to solar radiation. UV-A rays cause in particular a loss of elasticity of the skin and the appearance of wrinkles which result in early ageing. They promote the onset of the erythemal reaction or amplify this reaction in certain subjects and may even be responsible for phototoxic or photoallergic reactions.
Compounds are known which have the property of absorbing ultraviolet radiation in the erythemal region while allowing the radiation responsible for tanning to pass through and it has already been proposed to use such compounds as "sunscreen" agents in cosmetic compositions which promote the acquisition of skin tan while avoiding skin burns and irritations.
Synthetic or natural carbon-containing polymers and siloxane polymers carrying an ultraviolet-absorbing group are also known which possess the advantage of reducing or even suppressing the penetration of the screening compound into the body.
Metallic oxides such as titanium oxide are useful because of their ultraviolet ray diffusion and reflection properties over a broad band. However, the effectiveness of the cosmetic compositions containing only metallic oxides, expressed by the solar protection factor which is generally called "protection index" or PI, is inadequate for very sensitive skins or skins continuously exposed to solar radiation, especially with respect to the UV-B protection index.
The protection index or PI may be expressed by the ratio of the irradiation time required to reach the erythematogenic threshold with the UV-screening agent to the time required to reach the erythematogenic threshold without a UV-screening agent.
Cosmetic compositions containing only "screening polymers" have the same disadvantage.
In the following text, a polymer of hydrocarbon or siloxane structure, carrying at least one ultraviolet-absorbing group, will be called "screening polymer".
Moreover, at the industrial level, it is of course advantageous to have UV-screening agents which make it possible, at low concentrations, to obtain anti-sun compositions with a high protection index.
The Applicant has just discovered that by combining at least one nanopigment of metallic oxide, having a particle size less than 100 nm, with at least one fat-soluble screening polymer, in a cosmetically acceptable carrier, there was surprisingly obtained, for a composition containing a given concentration of the nanopigment and the screening polymer taken together, a protection index, especially a UV-B protection index, substantially greater than the protection indices of compositions containing either a nanopigment, or a screening polymer, at the same concentration and in the same carrier.
The subject of the present invention is therefore a cosmetic composition for screening out ultraviolet radiation with wavelengths of between 280 and 400 nm, which contains at least one nanopigment of metallic oxide and at least one screening polymer chosen from fat-soluble polymers with a hydrocarbon structure and polymers with a siloxane structure, in a cosmetically acceptable carrier.
The subject of the present invention is also a process for protecting the
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Forestier Serge
Hansenne Isabelle
"L'Oreal"
Chang Ceila
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