| abstract |
The present invention provides a propylene/1-butene random copolymer (PBR) having excellent flexibility, impact resistance, heat resistance and low-temperature heat-seal properties, a polypropylene composition containg the copolymer, a sheet, film or stretched film comprising the composition and a composite film having a layer of the composition. The propylene/1-butene random copolymer contains 60 to 90 mol% of propylene units and 10 to 40 mol% of 1-butene units and has a triad isotacticity of not less than 85% and not more than 97.5 %, a molecular weight distribution (Mw/Mn) of from 1 to 3, an intrinsic viscosity of from 0.1 to 12 dl/g, a melting point (Tm) of from 40 to 120°C, and satisfies the following relation 146 exp - 0.022 ¢ M § Tm § 125 exp - 0.032 ¢ M nwherein Tm represents a melting point and M (mol%) represents a content of 1-butene constituent units. The invention, further, provides a transition metal compound useful as an olefin polymerization catalyst and an olefin polymerization catalyst containing the transition metal compound. The transition metal compound is represented by the following formula (2a): nwherein each of R 1 and R 3 is hydrogen, R 2 and R 4 are selected from a hydrocarbon group and silicon-containing group, R 5 to R 13 are selected from hydrogen, a hydrocarbon group and silicon-containing group, and adjacent substituent groups R 5 to R 12 may be linked to form a ring. R 14 is an aryl group, and R 13 and R 14 may be linked to form a ring. M is a Group 4 transition , metal, Y is a carbon atom, Q is halogen, etc, and j is an integer of 1 to 4. |