To appropriately and efficiently remove impurities derived from an organoaluminum compound component from a cyclic olefin-based polymer in the case of using a large amount of the organoaluminum compound as a co- catalyst.
In a purification procedure of a cyclic olefin-based polymer obtained by the polymerization of a cyclic olefin in the presence of a catalyst system comprising a transition metal component and an organoaluminum compound component having an aluminum content in a polymerization solution of 2 g/L or more, to a polymerization solution comprising the cyclic olefin-based polymer, a poor solvent with respect to the polymer which is a compound containing a carbonyl group is added to allow the polymer and the metal component residues to precipitate, followed by extracting the polymer with a good solvent with respect to the polymer.
TAKASAKI KENJI
ARITOMI MITSUTOSHI
