Patent ID: 8039552

Claim:
A process for producing a propylene block copolymer, comprising the steps of: (I) homopolymerizing propylene or copolymerizing propylene with an olefin other than propylene, in the presence of a catalyst formed by contacting with one another a solid catalyst component containing titanium atoms, magnesium atoms and halogen atoms, an organoaluminum compound and an external electron donor compound, thereby forming a polymer component (1) containing 90% by weight or more of propylene units, the total of the polymer component (1) being 100% by weight; and (II) copolymerizing propylene with an olefin other than propylene in the presence of the polymer component (1), thereby forming a polymer component (2) containing 10 to 90% by weight of propylene units, the total of the polymer component (2) being 100% by weight; a combination of a transition metal compound represented by the following formula (ii) with an ether group-containing linear hydrocarbon compound and/or a Lewis base compound being added to the above polymerization system between the ending point of the step (I) and the starting point of the step (II), or during the step (II), M(OR 1 ) p X q (ii) wherein M is a zirconium atom or a hafnium atom; R 1 is a hydrocarbon group; X is a hydrogen atom, a halogen atom or a hydrocarbon group; p is a number satisfying 0≦p≦m; q is a number satisfying 0≦q≦m; p+q=m; and m is the valence of M.