Process for producing butene polymer

摘要

It is possible to produce butene polymer at high yield, which polymer contains 80 mol % or more of polymer molecules having terminal vinylidene structure and being low in the content of residual organic fluorine by a process comprising Step (I) to polymerize in liquid phase by adding complex catalyst composed of boron trifluoride, ether and alcohol and/or water in specified ratios to C4 fractions and Step (II) to reduce the content of trimer and lighter components contained in the obtained polymer to 0.2% by weight or less by distillation.