Production of vinyl chloride polymers

Claim 1

IN A PROCESS FOR THE PRODUCTION OF AQUEOUS DISPERSIONS OF A POLYMER OF VINYL CHLORIDE BY POLYMERIZING A MEMBER OF THE GROUP CONSISTING OF VINYL CHLORIDE AND VINYL CHLORIDE TOGETHER WITH UP TO ITS OWN WEIGHT OF A COPOLYMERIZABLE ETHYLENICALLY UNSATURATED MATERIAL, THE IMPROVEMENT COMPRISING OBTAINING POLYMER PARTICLES OF LARGE UNIFORM SIZE BY INITIATING THE POLYMERIZATION IN THE ABSENCE OF AN EMULSIFYING AGENT AND IN AN AQUEOUS MEDIUM CONTAINING IN SOLUTION A POLYMERIZATION CATALYST AND AN ELECTROLYTE YIELDING POLYVALENT METALLIC CATIONS IN AN AQUEOUS SOLUTION, AND SUBSEQUENTLY INTRODUCING AN EMULSIFYING AGENT AFTER POLYMERIZATION HAS COMMENCED, BUT BEFORE THE POLYMER DISPERSION THUS FORMED BEGINS TO COAGULATE THE AMOUNT OF SAID ELECTROLYTE PRESENT AT ANY STAGE OF THE PROCESS BEING INSUFFICIENT TO CAUSE COAGULATION OF THE POLYMER DISPERSION, SAID EMULSIFYING AGENT BEING INTRODUCED IN AN AMOUNT SUFFICIENT TO PROVIDE MECHANICAL STABILITY BUT INSUFFICIENT TO IMPAIR THE PROPERTIES OF THE POLYMER CONTAINED IN THE DISPERSION PRODUCED.