Stabilised chlorine-containing polymer compositions

A stabilizing composition for a chlorine-containing polymer, which composition comprises

• (a) at least one organotin compound of formula I to IV ##STR34## wherein R.sub.1 is C.sub.1 -C.sub.12 alkyl or C.sub.1 -C.sub.8 alkoxycarbonylethyl,
• Q is --S-- or --O--CO--, and,
• if Q is --S--,
• R.sub.2 is C.sub.8 -C.sub.18 alkyl, a radical --R.sub.3 --COO--R.sub.4 or --(CH.sub.2).sub.2 --O--CO--R.sub.4, or,
• if Q is --O--CO--,
• R.sub.2 is phenyl which is unsubstituted or substituted by C.sub.1 -C.sub.4 alkyl;
• R.sub.3 is methylene, ethylene or o-phenylene,
• R.sub.4 is C.sub.5 -C.sub.18 alkyl,
• R.sub.5 is methylene, ethylene or o-phenylene,
• R.sub.6 is C.sub.2 -C.sub.4 alkylene or C.sub.4 -C.sub.8 alkylene which is interrupted by oxygen;
• i is 1 or 2,
• j is a number in the range from 1 to 6,
• k is a number in the range from 1 to 3, and
• b) at least one phosphorus compound of formula V wherein
• R.sub.7 is C.sub.4 -C.sub.18 alkyl, phenyl which is unsubstituted or substituted by C.sub.1 -C.sub.12 alkyl or --CO.sub.2 R.sub.8 ;
• C.sub.4 -C.sub.21 alkanoyloxyalkyl, C.sub.3 -C.sub.24 alkoxycarbonylalkyl;
• C.sub.3 -C.sub.24 alkoxycarbonylalkyl in which the alkoxycarbonyl moiety is interrupted by oxygen, sulfur, ##STR35## C.sub.9 -C.sub.24 phenylalkoxycarbonylalkyl which is unsubstituted or substituted in the phenyl ring by C.sub.1 -C.sub.12 alkyl;
• C.sub.9 -C.sub.24 phenylalkoxycarbonylalkyl which is unsubstituted or substituted in the phenyl ring by C.sub.1 -C.sub.12 alkyl, the bond between the phenyl ring and the alkoxycarbonylalkyl radical being interrupted by oxygen, sulfur, ##STR36## C.sub.7 -C.sub.20 cycloalkoxycarbonylalkyl or C.sub.5 -C.sub.15 cycloalkyl-C.sub.2 -C.sub.6 alkoxycarbonyl-C.sub.1 -C.sub.12 alkyl,
• R.sub.8 is C.sub.1 -C.sub.18 alkyl,
• R.sub.9 is hydrogen or C.sub.1 -C.sub.12 alkyl,
• R.sub.10 is hydrogen or C.sub.1 -C.sub.12 alkyl,
• R.sub.11 is hydrogen or C.sub.1 -C.sub.18 alkyl,
• X is oxygen or sulfur, and
• n is 0 or 1.