| 摘要 |
PROBLEM TO BE SOLVED: To produce an ethylene polymer having a wider molecular weight distribution and improved in impact resistance and environmental stress cracking resistance by (co)polymerizing ethylene in the presence of a catalyst made from an organomagnesium compound and a solid inorganic oxide carrying a chromium (III) amide compound. SOLUTION: A chromium (III) amide compound of the formula (wherein R<1> to R<18> are each H or a 1-18C hydrocarbon group; and M<1> to M<6> are each C and/or Si) is mixed with a solid inorganic oxide baked at 200-450 deg.C for 30 min to 24 hr and having a specific surface of 50-1,000 m<2> /g, a pore volume of 0.5-3.0 m<2> /g and a mean particle diameter of 10-200μm, and an organomagnesium compound so as to provide a molar ratio of Mg to Cr of (1 to 1,000):1, and the mixture is reacted in a solvent in a temperature range from -78 deg.C to the boiling point of the solvent for 10 min to 24 hr, thus giving a catalyst. Ethylene and, if necessary, anα-olefin are (co)polymerized in the presence of this catalyst to give an ethylene polymer having a number-average molecular weight (Mn) of 2,000 to 20,000, a weight-average molecular weight (Mw) of 200,000 to 600,000, and an Mw/Mn of 30 to 80.
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