Prevention of cold flow in polybutadiene

Claim 1

IN A PROCESS WHEREIN A POLYMERIZATION REACTION MIXTURE IS FORMED BY POLYMERIZATION 1,3-BUTADIENE IN THE PRESENCE OF A HYDROCARBON DILUENT WITH A CATALYST SYSTEM SELECTED FROM THE GROUP CONSISTNG OF: (1) A CATALYST FORMED BY MIXING MATERIALS COMPRISING AN ORGANO-COMPOUND OF A GROUP I TO III METAL AS A FIRST COMPONENT AND AN IODINE CONTAINING SECOND COMPONENT INCLUDING A TITANIUM HALIDE AND (2) AN ORGANOLITHIUM CATALYST, SAID POLYMERIZING OCCURRING AT A TEMPERATURE IN THE RANGE OF -100 TO 250*F. AND AT A PRESSURE SUFFICIENT TO MAINTAIN SAID REACTION MIXTURE SUBSTANTIALLY IN THE LIQUID PHASE, THE IMPROVEMENT WHICH COMPRISES ADDING TO SAID REACTION MIXTURE A MEMBER SELECTED FROM THE GROUP CONSISTING A LIQUID XANTHATE-TELECHELIC POLYMER OF A CONJUGATED DIENE, A LIQUID THIOXANTHATE-TELECHELIC POLYMER OF A CONJUGATED DIENE, AND A LIQUID DITHIOCARBAMATE-TELECHELIC POLYMER OF A CONJUGATED DIENE, SAID MEMBER BEING ADDED BEFORE INACTIVATION OF SAID CATALYST SYSTEM IN AN AMOUNT OF FROM 0.1 TO ABOUT 50 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT OF POLYMERIZED 1,3-BUTADIENE, SAID CONJUGATED DIENES HAVING FROM 4 TO 12 CARBON ATOMS; MAINTAINING SAID MEMBER IN CONTACT WITH SAID POLYMERIZATION MIXTURE AT A TEMPERATURE OF -100 TO 250*F. FOR A PERIOD IN THE RANGE OF 5 MINUTES TO 50 HOURS; AND RECOVERING A POLYBUTADIENE PRODUCT HAVING A REDUCED TENDENCY TO COLD FLOW.