Composition containing a dibenzoylmethane derivative and an alpha-alkylstyrene dimer uv stabilising method

Cosmetic or dermatological composition, for topical use, characterized in that it comprises at least, in a cosmetically acceptable support:

• (a) from 0.1 to 20% by weight of a UV screening agent of the dibenzoylmethane-based type and
• (b) from 0.1 to 20% by weight of an α-alkylstyrene-based dimer of formula (I) below:
• 11
• in which
• R1 and R2, which may be identical or different, denote hydrogen, OH, NH2, a linear or branched C1-C12 alkyl radical;
• a linear or branched C1-C12 alkoxy radical;
• a linear or branched C1-C12 monoalkylamino radical;
• a linear or branched C1-C12 dialkylamino radical or a water-solubilizing substituent chosen from a carboxylate group, a sulphonate group and an ammonium residue;
• R3 and R4, which may be identical or different, denote a group COOR6, COR6, CONR6R7 or CN;
• R5 denotes a linear or branched C1-C12 alkyl radical;
• R6 and R7, which may be identical or different, denote hydrogen, a linear or branched C1-C12 alkyl radical;
• a linear or branched C2-C10 alkenyl radical;
• a branched or unbranched C3-C10 cycloalkyl radical;
• a branched or unbranched C3-C10 cycloalkenyl radical;
• a C6-C18 aryl or a C4-C7 heteroaryl;
• the said cycloalkyl, cycloalkenyl and aryl groups possibly comprising one or more substituents chosen from halogens, a cyano group, a nitro group, an amino group, a C1-C4 monoalkylamino radical, a C1-C4 dialkylamino radical, a hydroxyl group, a C1-C4 alkyl radical and a C1-C4 alkoxy radical;
• the said cycloalkyl and cycloalkenyl groups possibly comprising one or more hetero atoms (for example O, N or S);
• A denotes O, S or a group NR8;
• R8 denotes hydrogen or a linear or branched C1-C12 alkyl radical;
• B denotes a linear or branched C1-C12 alkylene radical which may comprise one or more substituents chosen from hydroxyl, OC1-C6-acyl, NH2, NH-C1-C6-alkyl, NH-C1-C6-acyl, CN, COOH and COO-C1-C6-acyl;
• a branched or unbranched C4-C12 cycloalkylene radical;
• a C8-C22 aralkylene radical;
• a C9-C21 monooxoaralkylene radical;
• or a group [X]n—Y—;
• at least two of the radicals R1, R2 and R8 may together form a 5- or 6-membered ring with the benzene nucleus to which they are attached;
• X denotes a group —CH2—CH2—Z—, —CH2CH2CH2Z—, —CH(CH3)—CH2—Z—, —CH2—CH2—CH2—CH2—Z— or CH2—CH(CH2CH3)—Z—;
• Y denotes a group —CH2—CH2—, —CH2CH2CH2—, —CH(CH3)—CH2—, —CH2—CH2—CH2—CH2— or —CH2—CH(CH2CH3)—;
• Z denotes O or S;
• n ranges from 1 to 150.