| 摘要 |
Stable aqueous dispersions of copolymers of ethylene and vinyl esters are prepared by a process wherein a reaction vessel is charged with water, a peroxy compound, a surface-active agent and, if necessary, a protective colloid, and ethylene is introduced into the reaction vessel at a pressure of 10 to 100 atmospheres gauge, and a vinyl ester is added at a rate which is proportional to its consumption, at an elevated temperature while maintaining the ethylene pressure. Specified vinyl esters are vinyl acetate, propionate, butyrate and benzoate. Other monomers, e.g. acrylic, crotonic, maleic and fumaric acids and esters, and vinyl halides, may also be present. Specified peroxy compounds are potassium and ammonium persulphates. Specified protective colloids are polyvinyl alcohol and water-soluble cellulose derivatives. The dispersions may be used in paints and adhesives. Examples describe the copolymerization of ethylene with (1 to 4) vinyl acetate and (5) vinyl acetate and vinyl propionate in aqueous dispersion in the presence of ammonium persulphate, sodium hydrocarbon sulphonate, sodium dihydrogen phosphate, optionally together with (4) a mixed iso-octyl/polyglycol ester of maleic acid. Specifications 582,093 and 645,088 are referred to. |
