Thermal stabilizer composition for halogen-containing vinyl polymers

1. A stabilized polymeric composition comprising a halogen-containing vinyl polymer; and a stabilizer composition comprising a mercaptoester, a reverse mercaptoester, and a Lewis acid; wherein the mercaptoester has a moiety having the formula HS—X—C(═O)O—, wherein the reverse mercaptoester has a moiety having the formula HS—X—OC(═O)—, wherein X is a substituted or unsubstituted hydrocarbyl group having a valency of at least two, and wherein the Lewis acid is zinc chloride.

2. The stabilized polymeric composition of claim 1 , wherein the mercaptoester is stearyl thioglycolate, 2-ethylhexyl thioglycolate, diethylene glycol bis(thioglycolate), or a mixture comprising one or more of the foregoing mercaptoesters.

3. The stabilized polymeric composition of claim 1 , wherein the reverse mercaptoester is 2-mercaptoethyl stearate, 2-mercaptoethyl caproate, 2-mercaptoethyl tallate, or a mixture comprising one or more of the foregoing reverse mercaptoesters.

4. The stabilized polymeric composition of claim 1 , wherein the stabilizer composition further comprises a polyol; a nitrogen-containing compound; a 2-mercaptoethanol of the formula R 20 S—CH 2 —CH 2 —OR 21 wherein R 20 and R 21 are H, or R 20 and R 21 together form a cyclic group of the formula —C(R 23 )—, wherein R 23 is a C 1 to C 12 straight chain or cyclic aliphatic group; an oligomer formed by the polymerization of R 20 S—CH 2 —CH 2 —OR 21 and having at least two units derived from R 20 S—CH 2 —CH 2 —OR 21 and a weight average molecular weight of up to 3000; or a mixture of one or more of the foregoing stabilizers.

5. The stabilized polymeric composition of claim 1 , wherein the composition comprises 0.05 phr to 5 phr of the mercaptoester; 0.05 phr to 5 phr of the reverse mercaptoester; and 0.01 phr to 0.5 phr of the Lewis acid, all based on 100 parts of the halogen-containing vinyl polymer.

6. A stabilizer composition comprising a mercaptoester, a reverse mercaptoester, and a Lewis acid; wherein the mercaptoester has a moiety having the formula HS—X—C(═O)O—, wherein the reverse mercaptoester has a moiety having the formula HS—X—OC(═O)—, and wherein X is a substituted or unsubstituted hydrocarbyl group having a valency of at least two.

7. A method of stabilizing a halogen-containing vinyl polymer comprising adding to the halogen-containing vinyl polymer the stabilizer composition of claim 6 .

8. An article comprising the composition of claim 1 .

9. The article of claim 8 , wherein the article is a pipe, a window casing, siding, a bottle, wall covering or packaging film.