PRODUCTION OF RANDOM CYCLOOLEFIN COPOLYMER

PURPOSE:To produce the title copolymer having a decreased PE content and improved transparency by copolymerizing ethylene with a specified cycloolefin and separating solid PE produced as a by-product in a small amount. CONSTITUTION:Ethylene is copolymerized with a cycloolefin of formula I (wherein (n) is 0 or 1; (m) is 0 or a positive integer; R to R are each H, halogen or a hydrocarbon group; R to R may be combined to form a monocyclic or polycyclic ring which may have a double bond; and R and R or R and R may be combined to form an alkylidene group) or formula II (wherein (l) is 0 or an integer of 1 or greater; (m) and (n) are each 0-2; R to R are each H, halogen, an aliphatic or aromatic hydrocarbon group or alkoxy; R or R and R or R may be combined directly or through a 1-3C alkylene group) in the presence of a catalyst comprising a soluble V compound and an organoaluminum compound in a hydrocarbon solvent to obtain a random cycloolefin copolymer solution of a concentration of 5-300g/l. This solution is filtered to separate solid PE produced as a by-product in a small amount, and the random cycloolefin copolymer is precipitated.