Stabilizer system and its use for stabilizing styrene polymers

Claim 1

A stabilizer system consisting essentially of a) at least one sterically hindered cyclic amine selected from the group consisting of ##STR28## wherein Y 1 denotes hydrogen, --O·, is alkyl with 1-8 carbon atoms, halogenoalkyl with 1-5 carbon atoms, cyanoalkyl with 1-5 carbon atoms, epoxylalkyl with 3-4 carbon atoms, hydroxyaralkyl with 8-12 carbon atoms, acyloxyalkyl with 4-20 carbon atoms, aminoalkyl with 2-4 carbon atoms, acylamine with 2-18 carbon atoms, alkoxycarbonyalkyl with 3-21 carbon atoms, alkoxyalkyl with 3-20 carbon atoms, aralkyl with 7-20 carbon atoms, alkenyl with 3-6 carbon atoms or alkinyl with 3-6 carbon atoms, R 1 and R 2 represent methyl or together represent --(CH 2 ) 5 --, R 3 represents methyl, R 4 represents alkyl with 1-5 carbon atoms or together with R 3 represents the radicals --(CH 2 ) 4 --, --(CH 2 ) 5 , ##STR29## R 8 and R 9 independently of one another denote alkoxycarbonyl with 2-6 carbon atoms, benzoyl, nitrile or phenyl, R 16 denotes hydrogen or the radical of an acyl group which is derived from an aliphatic carboxylic acid with 2-18 carbon atoms, from an aromatic carboxylic acid with 7-10 carbon atoms or from a carbamic acid substituted at the nitrogen by alkyl with 1-12 carbon atoms, benzyl or phenyl, with the ring Z representing a benzene or cyclohexane ring which is not substituted further or is substituted further by 1-2 alkyl groups with 1-5 carbon atoms, R 23 denotes hydrogen, alkyl with 1-20 carbon atoms, benzyl, alkylene with 1-20 carbon atoms, or alkoxycarbonyalkyl with 2-26 carbon atoms, or an acyl group which is derived from an aliphatic carboxylic acid with 2-20 carbon atoms, from benzoic acid or from a carbamic acid substituted at the nitrogen by alkyl with 1-24 carbon atoms or phenyl, Y 2 denotes hydrogen, -- O· or methyl and p represents an integer of 1 to 3 and b) at least one co-stabilizer of the formulae ##STR30## in which L 1 denotes hydrogen alkyl with 1-18 carbon atoms, allyl, methallyl or benzyl, L 2 denotes hydrogen, L 3 denotes hydrogen or hydroxyl, L 4 denotes hydrogen, hydroxyl alkoxy with 1-20 carbon atoms, allyloxy, methallyloxy or benzyloxy, L 5 denotes hydrogen, alkyl with 1-12 carbon atoms, alkenyl with 3-12 carbon atoms, cyclohexyl, aralkyl with 7-11 carbon atoms, phenyl, acylamino with 2- 12 carbon atoms, acylaminomethyl with 3-13 carbon atoms, chlorine or bromine, L 6 denotes hydrogen, methyl, hydroxyl, alkoxy with 1-12 carbon atoms or acylamino with 2-12 carbon atoms, L 7 denotes hydrogen, alkyl with 1-12 carbon atoms, aralkyl with 7-11 carbon atoms, cyclohexyl, phenyl, alkoxycarbonylethyl with 4-15 carbon atoms, alkoxy with 1-12 carbon atoms, chlorine, bromine, carboxyl, alkoxycarbonyl with 2-13 carbon atoms or acylamino with 2-12 carbon atoms, L 8 denotes hydrogen, alkyl with 1-8 carbon atoms, alkoxy with 1-12 carbon atoms, chlorine, bromine, acylamino with 2-12 carbon atoms, carboxyl, alkoxycarbonyl with 2-13 carbon atoms, acyloxy with 2-12 carbon atoms, carbamoyl with 3-17 carbon atoms, alkoxysulphonyl with 1-12 carbon atoms, phenoxysulphonyl or sulphonamido with 2-16 carbon atoms, L 9 denotes hydrogen, methyl, chlorine or bromine, L 10 and L 12 independently of one another denote alkyl with 1-8 carbon atoms, alkoxy with 1-12 carbon atoms, allyloxy, methallyloxy, phenoxy, benzyloxy, chlorine, bromine or alkoxycarbonyl with 2-13 carbon atoms, L 11 and L 13 independently of one another denote hydrogen or alkyl with 1-8 carbon atoms, L 14 and L 15 independently of one another denote hydrogen or alkyl with 1-12 carbon atoms, L 16 denotes alkoxy with 1-12 carbon atoms, L 17 denotes alkyl with 1-3 carbon atoms or phenyl, L 18 denotes alkyl with 1-12 carbon atoms, L 19 denotes alkyl with 1-12 carbon atoms, L 20 denotes hydrogen, alkyl with 1-8 carbon atoms, alkoxy with 1-8 carbon atoms or chlorine, L 21 denotes nitrile or alkoxycarbonyl with 2-20 carbon atoms and L 22 denotes hydrogen or alkyl with 1-3 carbon atoms, the ratio of stabilizer (a) to co-stabilizer (b) being from 1:10 to 10:1.