Free radical initiator delivery system

摘要

This invention relates to a process for preparing an improved polymerization free radical initiator delivery system for the polymerization of a monomer containing olefinic unsaturation which comprises uniformly dispersing a water insoluble free radical initiator, an excess amount of the polymeric product of the reaction and between about 1.0 and about 100 wt. % of a surfactant based on initiator in water to form an aqueous mixture containing between about 5 and about 40 wt. % solids; subjecting the dispersion to treatment at a temperature of between about -25 DEG C. and about 0 DEG C. under from about 50 to about 400 milli Tort vacuum for a period of from about 5 to about 24 hours to remove water and to form uniform coprecipitated initiator/polymer microparticles having an average particle diameter of between about 0.001 and about 100 microns and then diluting the coprecipitated microparticles with water under vigorous agitation to form a microparticulate dispersion of low viscosity containing from about 5 to about 40 wt. % solids which is suitable as the initiator feed for contacting said monomer in a polymerization reaction.