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US 4,228,273 AGranted
Process for the removal of vinyl chloride from aqueous dispersions of vinyl chloride resins
AssigneeTenneco Chemicals, Inc.
InventorWilliam G. Hughes
Life of this patent
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Abstract
Vinyl chloride is removed from an aqueous dispersion that contains 5%-50% by weight of a vinyl chloride resin and 1000-15,000 ppm of vinyl chloride by a process in which the aqueous dispersion is contacted first with steam and vinyl acetate to remove at least 90% of the vinyl chloride from it and then, after a short conditioning period, with steam to reduce its monomer content to less than 10 ppm.
Claims5
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.degree.-85.degree. 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.degree.-85.degree. 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.degree.-95.degree. 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.
3 more elements
Dependencies are inferred from the claim text.