| 主权项 |
1. A process for improving the chemical stability towards UV radiation of at least one dibenzoylmethane derivative, which comprises combining the said dibenzoylmethane derivative is combined with an effective amount of at least one hydrophilic or water-soluble merocyanin UV-screening agent selected from the group formed by:(1) those corresponding to one of the formulae (I) and (II) and also the salts thereof and the E,E-, E,Z- or Z,Z-geometrical isomer forms thereof below:in which:
R1 and R2, which may be identical or different, represent H; a linear or branched C1-C22 alkyl radical optionally containing from 1 to 3 oxygen atoms; a C3-C8 cycloalkyl radical, which is unsubstituted or substituted with C1-C4 alkyl radicals; the said radicals R1 and R2 optionally containing an alkylsulfonate radical in its acid or salified form or one or two hydroxyl radicals; R1 and R2 may form, together with the nitrogen, a ring containing the group —(CH2)m—, which is uninterrupted or interrupted with one or more —O—, —S— or —NH—, R1 may form, with the carbon alpha to the nitrogen, a ring containing the group —(CH2)m—, which is uninterrupted or interrupted with one or more —O—, —S— or —NH—, R3 represents a carboxyl, —COOR5, —CONHR5, —COR5, —CONR5R1, SO2R5 or —CN group, R4 represents a carboxyl, —COOR6, —CONHR6, —COR6, —CONR6R2 or SO2R6 group, R5 and R6, which may be identical or different, represent a linear or branched C1-C22 alkyl radical optionally containing from 1 to 3 oxygen atoms; a C3-C8 cycloalkyl radical, which is unsubstituted or substituted with C1-C4 alkyl radicals; the said radicals R5 and R6 optionally containing an alkylsulfonate radical in its acid or salified form or one or two hydroxyl radicals, Z represents the group —(CH2)l—, which is uninterrupted or interrupted with —O—, —S— or —NR7—, and/or unsubstituted or substituted with one or two C1-C6 alkyl radicals, R7 is a C1-C5 alkyl radical optionally containing an alkylsulfonate radical in its acid or salified form or one or two hydroxyl radicals, n is 1-2; —m is 1-7; —l is 1-4;with at least one or two of the radicals R1, R2, R5, R6 and R7 containing
either an alkylsulfonate radical in its acid or salified form or one or two hydroxyl radicals;with the proviso that:(i) when n=2, one of the radicals R1, R5 or R6 is an alkyl diradical or R1 and R2 together with two nitrogen atoms form a cyclic divalent radical —(CH2)m—;(ii) R1 and R2 are not simultaneously a hydrogen atom;(iii) when R3 is —CN, then at least one of the radicals R1, R2 or R6 must contain an alkylsulfonate group in its acid or salified form;(2) the merocyanin compounds selected from the group formed by the following molecules, and also salts thereof and the E,E-, E,Z- or Z,Z-geometrical isomer forms thereof: |
