Process for preparing acrylonitrile/vinyl chloride copolymers having an increased viscosity which comprises using anionic/non-ionic emulsifier blends

Claim 1

A process for the preparation of chemically uniform copolymers having increased viscosity and increased molecular weight, comprising of from 20 to 50%, by weight, of acrylonitrile, from 80 to 50%, by weight, of vinyl chloride and, optionally, up to 15%, by weight, of other copolymerisable ethylenically unsaturated compounds, by the method of emulsion polymerisation which comprises carrying out the polymerisation at a pH of from 2 to 6 and a temperature of from 10° to 50° C in the presence of an anion active emulsifier selected from the group consisting of sulphuric acid derivatives, sulphonic acids, phosphoric acid derivatives and phosphonic acids and a non-ionic polyglycol ether emulsifier, such that: (a) the total amount of anion active and of non-ionic emulsifier is from 0.75 to 8%, by weight, based on the total quantity of monomer, and (b) the ratio, by weight, of anion active to non-ionic emulsifier is from 10:1 to 1.5:1.