DE2639086

Polymers of olefins are stabilized against ultraviolet light by a synergistic combination of stabilizers including (1) a hydroxybenzophenone and (2) an organotin compound of the formula: (a) RnSn-SR1 COOR2) 4-n, (b) RnSn-S-R2) 4-n, (c) RnSn-S R1 OOCR2) 4-n, (d) ((R)3 Sn-S)x R4 -Z)y, or (e) where R is alkyl, alkenyl, aryl, aralkyl, alkaryl or cycloalkyl, R1 is alkylene, arylene, cycloalkylene, aralkylene or alkarylene, R2 is an alkyl, aryl, aralkyl, alkenyl, alkaryl or cycloalkyl, R5 is alkylene, R4 is aliphatic, aromatic, araliphatic, alkyl substituted aromatic or cycloaliphatic radical of at least 2 carbon atoms and having a free valence of x+y, Z is -OH, -COOH, -COOR2 or -OOCR2 or Z can be a mixture of these radicals if y is greater than 1, x is 1 to 4, y is 0 to 3, x+y is 1 to 4 and n is 1 to 3. Preferably the olefin is polyethylene or polypropylene. Preferably the hydroxybenzophenone also has at least one alkoxy group.