STABILIZER COMBINATION FOR HALOGEN-CONTAINING THERMOPLASTIC RESIN COMPOSITIONS

The invention relates to a stabilizer combination for halogen-containing thermoplastic resin compositions, comprising a) calcium oxide and/or calcium hydroxide that can be optionally surface-modified; b) at least one stannous compound of the general formula (I): RnSn(X-R')4-n, wherein n is 1 or 2; the groups R are the same or different and represent a straight-chain or branche d alkyl group with 1 to 22 C atoms; the groups X are the same or different and represent each -S- or -O-; and the groups R' are the same or different and represent each a straight-chain or branched alkyl group with 1 to 22 C atoms , a -[C(O)]m-L-C(O)-O-R'' group or a -[C(O)]m-L-O-C(O)-R'' group, wherein m is 0 or 1, -L- is a divalent linking group selected from alkylene groups with 1 t o 4 C atoms or a vinylene group, and R'' is an alkyl group with 1 to 22 C atom s; or two (X-R') groups can be linked forming a heterocyclic ring of the formul a (I') or (I''), wherein L is defined as above; and c) at least one zinc compound selected from liquid and solid zinc salts of saturated, unsaturated , straight-chain or branched, monofunctional or polyfunctional aromatic or aliphatic carbonic acids, zinc oxide and zinc hydroxide; with the proviso th at the stabilizer combination does not contain perchlorate. The inventive stabilizer combination is useful for stabilizing PVC, especially rigid PVC (PVC-U). PVC-U stabilized with the inventive stabilizer has a high thermostability and an excellent weathering stability and is especially suitable for outdoors.