Mass polymerization process for ABS polyblends

Claim 1

A continuous mass polymerization process for preparing an ABS polymeric polyblend having a matrix phase copolymer of monoalkenyl aromatic and alkenyl nitrile monomers and a dispersed conjugated diene rubber phase grafted with said monomers, the steps, being in the order set forth and consisting essentially of: A. continuously charging a solution of a monomer mixture containing at least 20% by weight of the monalkemylaromatic monomer and at least 5% by weight of the alkenyl nutrile monomer having 2 to 15% of said rubber dissolved therein, to a first back mixed reaction zone, said first zone operating at 5 to 45% steady state conversion of said monomers, said rubber being dispersed as rubber particles having a particle size of about 0.5 to 10 microns, said particles having present about 1 to 5 parts of said monomers, wherein, at least a portion of said monomers is present as occluded and grafted copolymer of said monomers, forming a first partially polymerized mixture, B. continuously withdrawing and charging said first partially polymerized mixture to a second staged and stirred reaction zone, all said stages operating with common evaporative cooling by the evaporation of said monomers, said first mixture being progressively polymerized by substantially linear flow, steady state, polymerization through a plurality of stages in said second reaction zone forming a second partially polymerized mixture continuing 50 to 80% of ABS polyblend solids, C. continuously withdrawing said second mixture from said second reaction zone and separating said ABS polyblend solids from said partially polymerized mixture as said ABS polyblend having a matrix phase copolymer of said monomers with a dispersed diene rubber phase as rubber particles having present grafted and occluded copolymer of said monomers in an amount of about 1 to 5 parts per part of rubber, said rubber particles having an average particle size of about 0.5 to 10 microns.