Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Patent
1995-05-04
1997-04-08
Dodson, Shelley A.
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
424 63, 424 701, 514938, 528 12, 568331, A61K 742, C08G 7700, C07C 4982
Patent
active
056185200
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a photostable cosmetic composition intended to protect the skin and the hair from UV radiation, containing a UV-A filter and a filtering polymer of the benzotriazole silicone type, to its use for protection of the skin and the hair against UV rays and to a process for the stabilization of the UV-A filter by a benzotriazole silicone.
It is known that light radiation with wavelengths between 280 nm and 400 nm permit tanning of the human epidermis and that rays with wavelengths between 280 and 320 nm, which are known under the name UV-B, cause erythema and skin burns which may be harmful to the development of the tan; this UV-B radiation should thus be filtered out.
It is also known that UV-A rays, with wavelengths between 320 and 400 nm, which cause tanning of the skin, are liable to induce damage of the latter especially in the case of sensitive skin or skin which is continually exposed to solar radiation. UV-A rays in particular cause a loss in elasticity of the skin and the appearance of wrinkles, leading to premature ageing. They promote the triggering of the erythemal reaction or amplify this reaction in certain individuals and may even be the cause of phototoxic or photoallergic reactions. It is thus desirable also to filter out the UV-A radiation.
French Patent No. 2,440,933 describes 4-(tert-butyl)-4'-methoxydibenzoylmethane as a UV-A filter. It is proposed to combine this specific UV-A filter, sold under the name "PARSOL 1789" by the company Givaudan, with various UV-B filters for the purpose of absorbing all of the UV rays with wavelengths between 280 and 380 nm.
Unfortunately, when this UV-A filter is used alone or in combination with UV-B filters, it does not possess a photochemical stability which is satisfactory to guarantee constant protection of the skin during prolonged exposure to the sun, thereby necessitating repeated applications at close and regular intervals if it is desired to obtain effective protection of the skin against UV rays.
The Applicant has discovered that by combining, in defined proportions and in a defined weight ratio, 4-(tert-butyl)-4'-methoxydibenzoylmethane with a filtering polymer of the benzotriazole silicone type containing at least one unit of formula: ##STR1##
in which
R' denotes a saturated or unsaturated C.sub.1 -C.sub.30 hydrocarbon group, a C.sub.1 -C.sub.8 halogenated hydrocarbon group or a trimethylsilyloxy group;
a=1 or 2;
X=--A--Y containing at least 2 carbon atoms and optionally containing one or more oxygen atoms;
Y represents a 2-(2'-hydroxyphenyl)benzotriazole residue optionally bearing, on one or both of the aromatic rings, one or more C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, halogen, alkoxy, carboxyl, hydroxyl or amino substituents, satisfactory photochemical stability of the 4-(tert-butyl)-4'-methoxydibenzoylmethane was, surprisingly, obtained. A stabilized combination for protecting the human epidermis and hair against UV rays with wavelengths between 280 and 380 nm is thus available.
Furthermore, such a combination imparts to the filtering composition containing it, besides a good UV-A protection number and a good sun protection factor, enhanced cosmetic properties as regards the sticky effect on application and the final greasy appearance after penetration, as well as lasting properties in water, that is to say a good stability of the protection number over time, especially after showering or bathing.
The UV-A protection number and the sun protection factor (SPF) are determined using the in vitro method described by B. L. Diffey et al., in J. Soc. Cosmet. Chem. 40-127-133 (1989).
This method consists in determining the monochromatic protection factors every 5 nm over a wavelength range from 290 to 400 nm and in calculating, from these protection factors, the solar protection factor.
In addition to the units of formula (I), the filtering polymer may contain units of formula: ##STR2## in which R' has the same meaning as in formula (I);
b is an integer denoting 1, 2 or 3.
Hydrocarbon groups which may be men
REFERENCES:
patent: 4387089 (1983-07-01), De Polo
patent: 5089250 (1992-02-01), Forestier et al.
Deflandre Andre
Forestier Serge
Hansenne Isabelle
"L'Oreal"
Dodson Shelley A.
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