Color stabilization of vinyl chloride resins

Claim 1

In the process for the removal of vinyl chloride from an aqueous slurry that contains 5% to 50% by weight of a vinyl chloride resin and 100 ppm to 15,000 ppm of vinyl chloride wherein the slurry is heated at a temperature between 70° C. and 100° C. until it contains less than 10 ppm of vinyl chloride, the improvement wherein discoloration of the vinyl chloride resin is inhibited by contacting the vinyl chloride resin in the slurry during the heat treatment with a monomer-miscible color stabilizer selected from the group consisting of (a) organic peroxides having the structural formula ##STR2## wherein R and R' each represents an alkyl group having 2 to 12 carbon atoms, a haloalkyl group having 2 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a haloaryl group having 6 to 10 carbon atoms; (b) an organic azo compound having the structural formula R"--N═N--R'" wherein R" and R'" each represents an aliphatic hydrocarbon group having 1 to 18 carbon atoms; a nitrile-substituted aliphatic hydrocarbon group having 1 to 18 carbon atoms; a cycloaliphatic hydrocarbon group having 3 to 18 carbon atoms; or a nitrile-substituted cycloaliphatic hydrocarbon group having 3 to 18 carbon atoms; and (c) mixtures thereof.