Stabilisation of polyolefins contg inorganic pigments - by adding cyclic di-tert alkylamines

Polyolefins which contain inorganic pigments are stabilised against light decompsn. by addn. of a cyclic ditert. alkylamine of the formula (I) in which q = 1 or 2; X = an organic gp. which completes the N-contg. ring to a 5,6 or 7-membered ring; R1 and R2 = CH3 or together -(CH2)5-, R3 = CH3 and R4 is C1-5 alkyl, or R3 and R4 together denote -(CH2)4-, -(CH2)5-, and when q = 1, Y = H, -O; OH, alkyl, opt. substd. alkenyl, alkynyl, aralkyl, opt. substd., or acyl; or when q = 2, Y =alkylene, alkenylene, alkynylene, cycloalkylene or aralkylene. A stabilised compsn. pref. contains polyolefin, 0.01-10 wt. %. pigment, and 0.05-2 wt. % of cpd. (I).