High-rigidity ethylene-propylene copolymer and process for producing same.

摘要

A high-rigidity, whitening-resistant ethylene-propylene copolymer is provided, which is obtained by copolymerizing propylene with ethylene at three successive stages wherein at the respective first, second and third stages, a copolymer fraction having a specified ethylene content is formed in a specified amount based on the total polymerization amount, in the presence of a catalyst obtained by reacting an organoaluminum compound (L) or a reaction product thereof with an electron donor (E) with TiCf<Sub>4</Sub>; reacting the resulting solid product (I) with an (E) and an electron acceptor; and combining the resulting solid product (II) with an (L) and an aromatic carboxylic acid ester (R), the molar ratio of (R) to (II) being specified, and in the presence of hydrogen.