Process for the stabilization of polyolefins

Claim 1

A process for the stabilization of a polyolefin and olefin copolymer, which is prepared by low pressure polymerization on a solid catalyst, which is prepared by the reaction of an aluminium alkyl with a solid product of a magnesium dihalide in active form and a titanium compound, the stabilization being carried out by the addition of a sterically hindered piperidine derivative to the polymerization, wherein a piperidine derivative of formula I is used, ##STR12## in which n is 1-4, R 1 is methyl, R 2 is C 1 -C 18 alkyl, or is a group of formula II ##STR13## R 3 is a group ##STR14## R 4 has one of the meanings given for R 3 when n=1, or is one of the groups --X--R 8 --Y--, ##STR15## in which q is 2-6, when n=2, or is the group ##STR16## when n=3, or is a group ##STR17## when n=4, R 6 and R 7 are independently of one another hydrogen, C 1 -C 18 alkyl, C 5 -C 12 cycloalkyl, C 7 -C 12 phenylalkyl or a group of the formula II, or R 6 and R 7 are together C 4 -C 10 alkylene or C 5 -C 7 oxaalkylene, R 8 is C 2 -C 12 alkylene, X and Y are --N(R 6 )--, m is 2 or 3, and p is 2-10.