Process for making graft copolymers of vinyl aromatic compounds and stereospecific rubbers

Claim 1

IN A METHOD FOR MAKING A THERMOPLASTIC POLYMER COMPOSITION COMPRISING A GRAFT COPOLYMER WHEREIN A LIQUID COMPRISING AT LEAST ONE POLYMERIZABLE MONOMERIC VINYLIDENE AROMATIC COMPOUND HAVING A MINOR PROPORTION OF A RUBBERY SYNTHETIC BUTADIENE POLYMER CONTAINED THEREIN, IS HEATED AT ELEVATED TEMPERATURES TO POLYMERIZE THE MONOMER, THE STEPS OF: (A) HEATING A MIXTURE OF SAID RUBBER AND VINYLIDENE AROMATIC COMPOUND CONTAINING (1) ABOUT 80 TO ABOUT 99.5 WEIGHT PERCENT OF A MONOETHYLENICALLY UNSATURATED VINYLIDENE MONOMER SELECTED FROM THE CLASS CONSISTING OF AROMATIC VINYLIDENE MONOMERS AND ACRYLONITRILE, SAID MONOETHYLENICALLY UNSATURATED VINYLIDENE MONOMER CONTAINING AT LEAST 50 WEIGHT PERCENT OF AT LEAST ONE MONOVINYL AROMATIC MONOMER HAVING THE VINYL RADICAL DIRECTLY ATTACHED TO THE AROMATIC NUCLEUS, SAID MONOETHYLENICALLY UNSATURATED VINYLIDENE MONOMER BEING THE SOLE POLYMERIZABLE MONOMER IN SAID MIXTURE AND (2) ABOUT 0.5 TO ABOUT 20 WEIGHT PERCENT OF A RUBBERY STEREOSPECIFIC BUTADIENE POLYMER COMPRISING AT LEAST A MAJOR PROPORTION BY WEIGHT OF BUTADIENE-1,3 CHEMICALLY COMBINED WITH NOT MORE THAN A MINOR PROPORTION OF A MONOETHYLENICALLY UNSATURATED VINYLIDENE AROMATIC COMPOUND COPOLYMERIZABLE THEREWITH, AT POLYMERIZATION TEMPERATURES BETWEEN ABOUT 50-175*C., WHILE SUBJECTING THE LIQUID TO SUFFICIENT AGITATION TO MAINTAIN THE BUTADIENE POLYMER DISPERSED THROUGHOUT THE POLYMERIZING MASS IN THE FORM OF FINE PARTICLES OF SIZES BETWEEN 2-25 MICRONS WHILE POLYMERIZING FROM 1-35 PERCENT BY WEIGHT OF THE MONOMER; THEN (B) DISCONTINUING SUCH AGITATION OF THE LIQUID MIXTURE AS RESULTS IN APPRECIABLE SHEAR IN THE LIQUID, (C) CONTINUING POLYMERIZATION OF THE MONOMER AT TEMPERATURES BETWEEN 85-250*C. UNTIL THE MONOMER IS SUBSTANTIALLY POLYMERIZED; THEN, (D) CROSSLINKING TO THE RESULTING POLYMER BY HEATING AT TEMPERATURES OF ABOUT 220-285*C. UNTIL THE TOLUENEINSOLUBLE GEL OF THE POLYMER PRODUCT IS FROM 3.5 TO 6.5 TIMES THE WEIGHT OF SAID RUBBER, SAID GEL CONSTITUTING LESS THAN 70 PERCVENT BY WEIGHT OF THE POLYMER PRODUCT, AND HAVING A SWELLING INDEX OF 4-20; AND FINALLY, (E) SEPARATING THE RESULTING POLYMER PRODUCT FROM VOLATILE INGREDIENTS.