METHOD FOR MAKING POLYMODAL AQUEOUS SYNTHETIC RESIN DISPERSIONS

摘要

A method for making an aqueous polymodal synthetic resin dispersion by the emulsion polymerization of an ethylenically unsaturated monomer difficultly soluble in water, or a mixture of such monomers forming a polymer which is water insoluble under the conditions of polymerization, in an aqueous phase containing an emulsifier and a water soluble polymerization initiator, which method comprises adding a seed latex to the polymerization mixture in the course of the emulsion polymerization before more than 40 weight percent of said monomers have been polymerized, the particles of said seed latex being smaller by a factor ranging from 2 to 15 than are particles already formed by emulsion polymerization, the amount by weight of the particles in the seed latex being not greater than 10 percent by weight of the monomers and the ratio by weight of particles of said seed latex to the weight of the monomers already polymerized being from 1:4 to 1:500.