Polymerization of vinyl aromatic compounds

Claim 1

A PROCESS FOR PREPARING A POLYVINYL-AROMATIC SUBSTANCE CONTAINING FROM ABOUT 75 TO ABOUT 95% OF A HIGH MOLECULAR WEIGHT POLYMER AND FROM ABOUT 5 TO ABOUT 25% OF A LOW MOLECULAR WEIGHT POLYMER, WHICH COMPRISES MIXING A MONOMERIC VINYL-AROMATIC COMPOUND OF THE GROUP CONSISTING OF STYRENE, ALPHA-METHYL STYRENE AND MIXTURES THEREOF WITH A CATALYST CAPABLE OF CATALYZING A CATIONIC POLYMERIZATION, CONTINOUSLY FEEDING THE THE MIXTURE TO AN ELONGATED REACTION ZONE IN THE FORM OF A CLOSED CIRCUIT RAPIDLY CIRCULATING THE MIXTURE IN SAID ZONE WHILE MAINTAINING THE TEMPERATURE OF THE MIXTURE BETWEEN ABOUT 50* C. AND 110*C. FOR TIME SUFFICIENT TO POLYMERIZE FROM ABOUT 5 TO ABOUT 50% OF THE MONOMER TO A MOLECULAR WEIGHT OF FROM 1500 TO 5000, WITHDRAWING POLYMERIZED REACTION MIXTURE FROM SAID ZONE, COOLING THE WITHDRAWN MIXTURE TO BELOW ABOUT 30*C., SEPARATING CATALYST FROM THE COOLED MIXTURE, ADDING SUFFICIENT MONOMERIC VINYLAROMATIC COMPOUND OF THE GROUP CONSISTING OF STYRENE ALPHA-METHYL STYRENE AND MIXTURES THEREOF TO SAID LOW MOLECULAR WEIGHT POLYVINYL AROMATIC COMPOUND TO PROVIDE A SOLUTION HAVING RELATIVELY PROPORTIONS OF FROM 75 TO 95 25 PARTS LOW MOLECULAR WEIGHT POLYMER AND FROM 75 TO 95 PARTS MONOMER, AND SUBJECTING THE SOLUTION TO A FREE RADICAL POLYMERIZATION FOR A TIME AND TEMPERATURE SUFFICIENT TO POLYMERIZE SUBSTANTIALLY ALL OF THE MONOMER TO A MOLECULAR WEIGHT ABOVE 60,000.