METHOD FOR POLYMERIZATION AND COPOLYMERIZATION OF ALPHA-CLEFIN

PROBLEM TO BE SOLVED: To provide a polymerization and copolymerization method for an olefin obtaining an olefin polymer having a high bulk density and a broad mol. wt. distribution, while maintaining high stereospecificity and activity of a polymer. SOLUTION: In this method an olefin is polymerized or copolymerized in the presence of a catalyst system contg. two outer electron donors, i.e., a catalyst comprising a solid complex titanic catalyst comprising magnesium, a halogen-contg. titanium compd., and an internal electron donor (a), an organometallic compd. of a metal belonging to the group consisting of Groups I and III on the periodic table of elements (b), and an outer electron donor (1) and an outer electron donor (2) (c), wherein the ratio of MFR(1) to MHR(2) is 2-10, the MFR(1) being that of homopolymer (1) obtd. by using the outer electron donor (1) with the solid complex titanic catalyst (a) and organometallic compd. (b) and the MHR(2) being that of homopolymer (2) obtd. by using the outer electron donor (2) under the identical polymerization reaction condition used with the case of the outer electron donor (1), and wherein the NMR pentads of the homopolymer (1) and the homopolymer (2), respectively, are not lower than 95.5%.