| abstract |
There are herein disclosed a process for preparing an olefin polymer very economically advantageously by polymerizing an olefin in the presence of a polymerization catalyst having a high activity and an excellent copolymerizability, even if the amount of an expensive aluminum compound as a promotor to be used is small; and an ethylenic polymer having excellent molding properties, good mechanical properties, good heat-sealing properties and a good ESCR. n The process for preparing the olefin polymer of the present invention comprises the step of homopolymerizing an olefin or copolymerizing olefins in the presence of the polymerization catalyst containing (A) a transition metal compound represented by the general formula CpML X-1 wherein M is an element in the group 4 of the periodic table or the like, Cp is a cyclic compound group having a cyclopentadienyl skeleton, L is a σ ligand, and x is a valence number of M, and (B) an aluminum oxycompound in such a ratio that the molar ratio of the component (B)/the component (A) (in terms of a metallic atom) may be in the range of 2 to 500; and the ethylenic polymer of the present invention comprises an ethylene homopolymer or an ethylene copolymer in which (i) Mw/Mn is in the range of 1.5 to 4, and Mw is in the range of 3,000 to 1,000,000, (ii) a relation between a half value width (W) of a composition distribution curve and its temperature position (T) meets the equation W ≧ -24.9 + 2470/T , (iii) an activation energy (Ea) of melt flow is in the range of 7.5 to 20 kcal/mol, and (iv) a density is in the range of 0.85 to 0.97 g/cm 3 . |