METHOD FOR PRODUCING POLYOLEFIN HAVING HIGH STIFFNESS

摘要

A method for preparing polyolefin is provided to produce polyolefin having high stiffness in a continuous polymerization reactor with high polymerization activity by using a pre-polymerization catalyst obtained from a Ziegler-Natta catalyst. A method for preparing polyolefin includes a step of polymerizing or copolymerizing olefins in a multi-stage continuous polymerization reactor in the presence of a catalyst system consisting of (a) a pre-polymerization catalyst, (b) an organometallic compound of a group 1 or 3 metal on the periodic table, and (c) an external electron donor. The pre-polymerization catalyst is obtained by reacting olefin monomers in the presence of a Ziegler-Natta based solid complex titanium catalyst, at least two aluminum compounds comprising alkylaluminum and halogenated aluminum, and an electron donor to polymerize a high-molecular-weight monomer on the surface of the catalyst.