Technique for stabilization of vinyl chloride polymers using organic thiols

Claim 1

In the method for the preparation of a stable vinyl chloride polymer which comprises reacting a polyvinyl chloride polymer having a number average molecular weight ranging from 30,000 to 100,000 with an organic compound, adding a solvent to the reaction mixture to effect polymer precipitation, and subjecting the polymer to solvent extraction to yield the desired polymer, the improvement which comprises effecting said reaction at a temperature within the range of 160°-185° C. for a time period ranging from 150 to 18 hours, the longer time periods corresponding with the lower temperatures and the converse, the organic compound being a thiol of the formula R 1 SH wherein R 1 is selected from the group consisting of (a) alkyl groups of 8-14 carbon atoms, (b) an α-naphthyl group, (c) a β-naphthyl group, (d) a substituted aryl group of the formula ##STR3## wherein R 2 is selected from the group consisting of hydrogen, alkyl groups of 1-4 carbon atoms, alkoxy groups of 1-4 carbon atoms, chlorine and bromine, and (e) HS(CH 2 ) n wherein n is an integer from 6-10, the resultant polymer being free of chemically bound and occluded sulfur.