Patent ID: 7868111

Claim:
A method for producing α-olefin polymer, comprising steps of: polymerizing α-olefins in a reaction mixture comprising a halogen atom-containing acid catalyst and an aliphatic hydrocarbon having 3-12 carbon atoms, which contains 5 to 95 mass % of α-olefin, as a raw material (polymerization step); removing adsorptively most of the catalyst residue and simultaneously removing adsorptively halogen-containing compounds by bringing the reaction mixture into contact with activated alumina without treating the reaction mixture with an aqueous treatment agent after the polymerization step (removal step); and separating the α-olefin polymer from the product of the removal step (separation step); wherein said halogen atom-containing acid catalyst comprises a compound according to either formula (1) or formula (2): AlRmXn (1) wherein R represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, m represents 1 or 2, and n represents 1 or 2, with the relation of m+n=3; Al 2 RpXq (2) wherein R represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, p represents an integer of 1 to 5,and q represents an integer of 1 to 5 with the relation of p+q=6.