S-triazine derivatives having light-protecting action

Compounds of formula (I) ##STR26## in which R and R.sub.1, which are the same or different, are hydrogen or C.sub.1 -C.sub.8 straight or branched alkyl;

• R.sub.2 is hydrogen or C.sub.1 -C.sub.8 straight or branched alkoxy;
• R.sub.3 and R.sub.4, which are the same or different, are C.sub.1 -C.sub.18 straight or branched alkyl, C.sub.5 -C.sub.12 cycloalkyl optionally substituted with groups C.sub.1 -C.sub.8 alkyl, optionally substituted aryl groups or a group of formula (II) or (III) ##STR27## in which R, R.sub.1 and R.sub.2 have the meanings defined above, R.sub.5 has the same meaning as R.sub.3 and X is oxygen or the --NH-- group or when X is oxygen R.sub.5 can represent a group of formula (IV) ##STR28## in which A is C.sub.1 -C.sub.8 straight or branched alkyl, C.sub.5 -C.sub.8 cycloalkyl, optionally substituted aryl, R.sub.6 is hydrogen or methyl and n can be an integer from 1 to 10.