PROCESS FOR THE PREPARATION OF POLYOLEFIN

• Main Authors: MIYAKE, YOSHIO, KAWASAKI, MASAAKI, SUEYOSHI, TOMOKO, KOBATA, ATSUO
• Format: Patent
• Language: English; French
• Published: 25.03.1997
• Edition: 6
• Subjects: CHEMISTRY; COMPOSITIONS BASED THEREON; COMPOSITIONS OF MACROMOLECULAR COMPOUNDS; MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVINGCARBON-TO-CARBON UNSATURATED BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP

A first process for the preparation of polyolefin according to the invention is a process comprising polymerizing or copolymerizing olefin in the presence of a catalyst for olefin polymerization comprising ¢A! a metallocene compound of a transition metal selected from Group IVB of the periodic table, and ¢B! an organoaluminum oxy-compound; wherein the organoaluminum oxy-compound ¢B! is added to the polymerization system in the form of a slurry of said organoaluminum oxy-compound ¢B! in an aliphatic hydrocarbon or alicyclic hydrocarbon, and the polymerization is carried out in the presence of an aliphatic hydrocarbon diluent or an alicyclic hydrocarbon diluent. A second process for the preparation of polyolefin according to the invention is a process comprising: (i) polymerizing or copolymerizing olefin in a liquid phase in the presence of the above-mentioned catalyst; and (ii) feeding a polymer solution containing the resulting polyolefin from a polymerization zone to a separation zone kept at a temperature of not lower than the upper cloud point of the polymer solution to separate the polymer solution into a lower phase portion containing the polyolefin in a high concentration and an upper phase portion, so as to recover the polyolefin from the lower phase portion in the separation zone and to recycle at least a part of the upper phase portion to the polymerization zone.