Process for the continuous mass polymerization of polyblends

Abstract

The present invention relates to an improved process for the continuous mass polymerization of solutions comprising alkenyl aromatic monomers having about 1 to 10% by weight of a polybutadiene rubber dissolved therein, the steps comprising, (A) continuously charging said solution to a first reaction zone operating at about 10 to 40% conversion forming a first partially polymerized mixture, (B) continuously charging said first mixture to a second reaction zone operating at about 50-90% conversion forming a second partially polymerized mixture, and finally, (C) separating the residual monomer from said second mixture providing a polyblend of a matrix phase of said monomers having polybutadiene rubber particles grafted with said monomers dispersed therein, the improvement comprising: charging a monomer-polybutadiene solution in step (A) having in addition about 1 to 10% by weight of a diene block copolymer and about 1 to 20% by weight of a polymer of said monomers dissolved in said solution followed by carrying out steps (B) and (C) to provide a polyblend of a polymer of said monomers having dispersed therein rubber particles grafted with said monomers, said rubber particles containing said polybutadiene and diene block copolymer rubbers and forming a gel phase of said rubber particles containing grafted and occluded polymers of said monomers in an amount of about 0.5 to 5 parts per part of total rubber.