Abstract: A compound of formula I ##STR1## in which R.sub.1 is selected from C.sub.9-32 alkyl, C.sub.9-32 alkenyl, C.sub.9-32 alkoxy, --CO--R.sub.4 and --(CH.sub.2).sub.1-6 --COOC.sub.6-18 alkyl, where R.sub.4 is C.sub.8-31 alkyl, C.sub.8-31 alkenyl or C.sub.8-31 alkoxy; the alkyl group of each significance of R.sub.1 being uninterrupted or interrupted by one --O--, --S-- --SO.sub.2 -- group and being unsubstituted or substituted by --N(R.sub.5).sub.2, OH or halogen, where each R.sub.5, independently, is selected from hydrogen, C.sub.1-6 alkyl, C.sub.2-6 alkenyl and C.sub.1-6 alkoxy;R.sub.2 has a significance of R.sub.1 independently, of R.sub.1 or is --COOH hydrogen, hydroxyC.sub.1-6 alkyl, hydroxyC.sub.1-6 alkoxy, --COOC.sub.1-6 alkyl, OCOC.sub.1-6 alkoxy; Cl, Br, I, OH, C.sub.1-8 alkyl, C.sub.1-8 alkoxy or C.sub.2-8 alkenyl; andR.sub.3 is C.sub.1-6 alkyl, Cl, Br, I, OH, COOH, hydroxyC.sub.1-6 alkyl, C.sub.2-6 alkenyl, hydroxyC.sub.1-6 alkoxy, COOC.sub.1-6 alkyl, --OCOC.sub.1-6 alkoxy or C.sub.