| 摘要 |
PURPOSE:Two or more polymerizers are connected in series and the polymerization mixture is circulated under sepcific conditions to produce 2 or more products different in molecular weight at the same time in high productivity. CONSTITUTION:Ethylene, hydrogen, hexane and the catalyst are fed from line 2 to polymerizer 1 to produce low-molecular-weight polymer. The polymer mixture is sent to flash drum 3 where ethylene and hydrogen are removed and a part of the polymer is taken out through pipe 6 by pump 5 as a product. The rest of the polymer is sent to the second-stage polymerizer 7 to which ethylene, hexane and the catalyst are charged and high-molecular-weight polyethylene is produced. A part of the resultant polymer slurry is recycled to polymerizer 1 by pump 9. The ratio of the polymers formed at the first-stage polymerization to the second is adjusted to 6/4-4/6 preferably, the ratio of the circulation amount of the take-up amount is controlled to 2-50 preferably, thus producing polyethylenes having a molecular weight ratio of 5-100. |
