Treatment of aqueous suspension of vinyl chloride polymers

Abstract

Treatment of aqueous suspensions of vinyl chloride polymers containing vinyl chloride monomer so as to inhibit wet-foaming therein, by adding a glyceride of an optionally substituted saturated or unsaturated carboxylic acid containing 6 to 20 carbon atoms (e.g. glycerol monoricinoleate). Solid-foaming can also be inhibited by adding a wetting agent (such as partially hydrolysed polyvinyl acetate PVA) and a preferred formulation for effecting the treatment comprises an aqueous emulsion of the glyceride having PVA as the emulsion stabilizer.

I claim: 
     
       1. Method of treating an aqueous suspension of a vinyl chloride polymer, produced by aqueous suspension polymerisation and containing residual vinyl chloride monomer, to inhibit wet-foaming .Iadd.and dry-foaming .Iaddend.therein, which method comprises adding to said aqueous suspension of a vinyl chloride polymer containing residual vinyl chloride monomer, a glyceride of a saturated or unsaturated carboxylic acid, containing 6 to 20 carbon atoms .Iadd.to inhibit wet-foaming and a wetting agent to inhibit dry-foaming, and wherein said glyceride is added to the suspension in the form of an oil-in-water emulsion and wherein at least part of the wetting agent used to inhibit dry-foaming is a water-soluble PVA or cellulosic compound which additionally serves as an emulsion stabilizer for the oil-in-water emulsion of the glyceride that is added to the suspension.Iaddend.. .[.2. Method of treating an aqueous suspension of a vinyl chloride polymer, produced by aqueous suspension polymerization and containing residual vinyl chloride monomer, to inhibit wet-foaming and dry-foaming therein, which method comprises adding to the aqueous suspension of polymer containing residual vinyl chloride monomer, a wetting agent for vinyl chloride polymer and a glyceride of a saturated or 
     
     
        unsaturated carboxylic acid containing 6 to 20 carbon atoms..]. 3. Method according to .[.either.]. claim 1 .[.or claim 2.]. wherein the carboxylic 
     
     
        acid component of the glyceride is unsaturated. 4. Method according to 
     
     
        claim 1 wherein the glyceride used is a glycerol monocarboxylate. 5. Method according to claim 1 wherein the carboxylic acid component of 
     
     
        the glyceride used is unsubstituted or hydroxy substituted. 6. Method according to claim 1 wherein the glyceride used is glycerol monoricinoleate or glycerol monooleate. .[.7. Method according to claim 1 wherein the glyceride is added to the suspension in the form of a solution 
     
     
        in an organic solvent or in the form of an oil-in-water emulsion..]. 8. Method according to claim 1 wherein 50 to 2000 parts per million, based on the weight of vinyl chloride polymer, of glyceride is added to the suspension. .[.9. Method according to claim 2 wherein the wetting agent 
     
     
        used is a water-soluble PVA or cellulosic compound..]. 10. Method according to claim .[.2.]. .Iadd.1 .Iaddend.wherein the PVA has a molar degree of hydrolysis of 65 to 90%. .[.11. Method according to claim 2 wherein at least part of the wetting agent used is a water-soluble PVA or cellulosic compound which additionally serves as an emulsion stabiliser for an oil-in-water emulsion of the glyceride that is added to the 
     
     
        suspension..]. 12. Method according to claim .[.2.]. .Iadd.1 .Iaddend.wherein 30 to 400 parts per million, based on the weight of vinyl chloride polymer, of wetting agent is added to the suspension.