Process for the removal of vinyl chloride from aqueous dispersions of vinyl chloride resins

Claim 1

The process for the removal of vinyl chloride from an aqueous dispersion that contains 5%-50% by weight of a vinyl chloride resin and 1000 ppm-15,000 ppm of vinyl chloride that comprises the steps of (a) feeding the aqueous dispersion into a first treatment zone having a series of surfaces each having therein perforations through which the dispersion can flow downward onto the next surface in the series; (b) contacting the aqueous dispersion in the first treatment zone with a countercurrent stream of steam and vinyl acetate at a temperature in the range of 65°-85° C. at a pressure in the range of 200 torr to 600 torr to strip at least 90% of the vinyl chloride from the dispersion; (c) passing the dispersion downward into a second treatment zone where it is maintained at a temperature in the range of 75°-85° C. at a pressure in the range of 200 torr to 400 torr for up to 30 minutes; (d) passing the dispersion downward through a third treatment zone where it is contacted with a countercurrent flow of steam at a temperature in the range of 75°-95° C. at a pressure in the range of 300 torr to 600 torr; and (e) recovering an aqueous dispersion that contains less than 10 ppm of vinyl chloride.