Preparation of high impact compositions from vinyl aromatic monomers and rubbery diolefin polymers

Claim 1

IN A PROCESS FOR PREPARING A RUBBER-MOFIFIED VINYL AROMATIC POLYMER WHICH COMPRISES DISSOLVING, IN THE ABSENCE OF AQUEOUS DILUENTS, FROM 2 TO 25 WEIGHT PERCENT OF A RUBBERY POLYMER OF A CONJUGATED DIOLEFIN IN A VINYL AROMATIC MONOMER SELECTED FROM THE GROUPS CONSISTING OF STYRENE, LOWER ALKYL NUCELAR SUBSTITUTED STYRENE, HALOGEN NUCLEAR SUBSTITUTED STYRENE AND MIXTURES THEROF, AND PARTIALLY POLYMERIZING THE RESLTING MONOMER-RUBBER SOLUTION TO AN EXTENT OF FROM 10 TO 45 PERCENT CONVERSION, THE IMPROVEMENT WHICH COMPRISES TRANSFERRING THE PARTIALLY POLYMERIZED MONOMER-RUBBER MIXTURE TO AN AGITATED AQUEOUS SUSPENSION CONTAINING THEREIN HYDROXYETHYL CELLULOSE AS THE SUSPENDING AGENT, THE PARTIALLY POLYMERIZED MONOMER-RUBBER MIXTURE BEING ADDED IN AN AMOUNT SUCH THAT ITS WEIGHT RATIO TO WATER IN THE AQUEOUS SUSPENSION IS ABOUT 1:2 TO 5:4, SAID HYDROXYETHYL CELLULOSE HAVING A VISCOSITY IN A 1% AQUEOUS SOLUTION AT 25*C. OF FROM 750 TO 10,000 CPS. (BROOKFIELD VISCOMETER) AND A PEROXIDE INITIATOR, CONTINUING AGITATION OF THE RESULTING SUSPENSION, POLYMERIZING TO SUBSTANTIAL COMPLETION AND RECOVERING FROM SAID POLYMERIZATION SAID RUBBER-MODIFIED VINYL AROMATIC POLYMER IN BEAD FORM.