Copolymers of substituted piperidines, their manufacture and use

Copolymers, useful as light stabilizers for synthetic polymers, of one or several polyalkyl piperidines of the formula (I). ##STR7## and one or several comonomers of the formula (II) ##STR8## in which the molar ratio of (I) to (II) is about 1:1 and wherein the monomers of formula (I)

• R.sup.1 is hydrogen or C.sub.1 to C.sub.18 --alkyl,
• R.sup.2 and R.sup.3 are either the same and represent hydrogen
• or C.sub.1 to C.sub.5 --alkyl, in which case
• R.sup.4 is methyl, or
• R.sup.2 is hydrogen or C.sub.1 to C.sub.5 --alkyl, in which case
• R.sup.3 and R.sup.4, together with the carbon atoms to which they are bound, represent a C.sub.5 or C.sub.6 --cycloalkyl group or a group of the formula (III) ##STR9## R.sup.5 is hydrogen, C.sub.1 to C.sub.18 --alkyl or a group of the formula (IV) ##STR10## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are defined as above, and X stands for an oxygen atom or a group ##STR11## R.sup.6 being hydrogen, C.sub.1 to C.sub.18 --alkyl or a group of the formula (IV), whereas in the monomers of the formula (II)
• R.sup.7 is hydrogen or a group of formula COOR.sup.10 with
• R.sup.10 being C.sub.1 to C.sub.18 --alkyl,
• R.sup.8 is hydrogen or methyl, and
• R.sup.9 is hydrogen or C.sub.1 to C.sub.36 --alkyl, or phenyl, or chlorine, or acetyl, or a group of formula --OR.sup.11 with R.sup.11 being hydrogen or C.sub.1 to C.sub.18 --alkyl, or a group of the formula --COOR.sup.12 with R.sup.12 being alkyl or hydroxyalkyl with 1 to 18 carbon atoms or a radical of the formula (IV).