Process for production of polymeric polyblends

Claim 1

In a polymerization process for preparing polyblends having the following steps of (a) dissolving a graftable rubbery polymer in a polymerizable monomer formulation comprising at least one monovinylidene aromatic monomer to form a polymerizable mixture, (b) mass polymerizing with agitation said mixture to a partially polymerized mixture having a grafted, inverted and dispersed rubber phase, (c) suspending said partially polymerized mixture in an inert liquid, (d) suspension polymerizing said partially polymerized mixture to higher conversions and (e) recovering the suspending polyblend from said suspension, the improvement which comprises utilizing a peroxide catalyst having a half life of less than one hour at a temperature of 130° C., and a 10 hour half life at a temperature of 95° to 115° C., in combination with a saturated aliphatic acid containing 12 to 20 carbon atoms and a hydrated salt in steps (b) and (d) wherein step (b) is carried out at a temperature of from 95° to 125° C., polymerizing said polymerizable mixture to a conversion of about 10 to 45 percent and step (d) at a temperaure of from 110° to 150° C., polymerizing said partially polymerized mixture to essentially complete conversion and wherein said hydrated salt is present in step (b) in an amount of from about 0.01 to 1.0 percent by weight based on said monomers and in step (d) from about 0.10 to 1.0 percent by weight based on said monomers.