RESINOUS BUTADIENE/STYRENE REINFORCING COPOLYMERS

摘要

Inventors: Lloyd D. Hess William C. Mast IMPROVED RESINOUS BUTADIENE/STYRENE REINFORCING COPOLYMERS There is disclosed improved resinous butadiene/ styrene reinforcing copolymers prepared by a two step emulsion polymerization process comprising the steps of(A) polymerizing, under aqueous emulsion polymerization conditions, a first monomeric mixture of butadiene and styrene in the presence of water, polymerization initiator, molecular weight modifier and emulsifier to obtain a first butadiene/styrene copolymer latex and (B) adding to and polymerizing in said first copolymer latex a second monomer mixture of butadiene and styrene in the presence of water, polymerization initiator, molecular weight modifier and emulsifier wherein the monomeric mixture polymerized in step (A) ranges from 5 to 32 percent higher in styrene content than the monomeric mixture added and polymerized in step (B).