Manufacture of polyethylene

Claim 1

IN A PROCESS FOR MAKING SOLID POLYETHYLENE HAVING AN AVERAGE MOLECULAR WEIGHT ABOVE ABOUT 10,000, WHEREIN ETHYLENE IS SUBJECTED TO POLYMERIZING CONDITIONS IN THE PRESENCE OF AN INERT LIQUID HYDROCARBON REACTION MEDIUM AND A POLYMERIZATION CATALYST OBTAINED BY REACTING A REDUCIBLE CCOMPOUND OF A METAL OF GROUPS IVB TO VIB, INCLUSIVE, OF THE PERIODIC TABLE WITH AN ORGANO-ALUMINUM COMPOUND SELECTED FROM THE CLASS CONSISTING OF ALUMINUM TRIALKYLS, ALUMINUM TRIARYLS, DIALKYL ALUMINUM HALIDES AND DIARYL ALUMINUM HALIDES, WHEREBY THERE IS OBTAINED A CRUDE POLYMERIZATE COMPRISING SAID POLYETHYLENE, ACTIVE CATALYST AND SAID REACTION MEDIUM, THE IMPROVED METHOD FOR RECOVERING SAID POLYETHYLENE WHICH COMPRISES: (1) ADMIXING AN ALIPHATIC ALCOHOL WITH SAID CRUDE POLYMERIZATE AND MAINTAINING THE MIXTURE SO OBTAINED AT A TEMPERATURE BETWEEN ABOUT 60*C. AND ABOUT 150*C. UNTIL THE ACTIVITY OF SAID CATALYST IS DESTROYED, (2) SEPARATING THE SOLID POLYETHYLENE FROM THE SO-TREATED POLYMERIZATE AT A TEMPERATURE BETWEEN ABOUT 60*C. AND ABOUT 150*C., (3) WASHING THE SEPARATED POLYETHYLENE WITH A LIQUID ALIPHATIC HYDROCARBON AND SEPARATING THE LATTER FROM THE WASHED POLYETHYLENE, AND (4) RE-WASHING THE POLYETHYLENE WITH A LIQUID SELECTED FROM THE CLASS CONSISTING OF LIQUID ALIPHATIC HYDROCARBONS AND MIXTURES OF METHANOL AND LIQUID ALIPHATIC HYDROCARBONS IN A VOLUME RATIO BETWEEN ABOUT 1:3 AND 2:1.