| 摘要 |
1,152,259. Ethylene-butene polymers. DOW CHEMICAL CO. 9 Dec., 1966 [15 Dec., 1965], No. 55286/66. Heading C3P. Ethylene polymers having improved stress crack resistance are prepared by (a) polymerizing ethylene at 30‹ to 100‹ C. in an inert liquid diluent in the presence of a molecular weight control agent until the resulting polymer slurry contains 5 to 40% by weight polymer solids, (b) separating the polymer slurry into major and minor portions, (c) introducing butene-1 into the minor portion of slurry in the absence of a molecular weight control agent and polymerizing the butene-1 at 30‹ to 100‹ C. so that the butene-1 polymerized ranges from 0À05 to 5% by weight of the total amount of ethylene polymerized in step (a), (d) mixing the major portion of slurry from step (a) with the polymer mixture of step (c) and (e) recovering the polymer. The molecular weight control agent used in step (a) is, e.g., H 2 or acetylene and the specified catalysts are combinations of an alkyl aluminium with a reducible compound of a metal of Group IVA, VA, VIA or VIII of the Periodic Table. In the examples the catalyst comprises tri-isobutyl aluminium and TiCl 4 , the inert medium is n-hexane and during step (c) the major portion of the polymer slurry is stored in a digester containing isopropyl alcohol, to which is subsequently added the slurry from step (c). The resulting polymer is blow-moulded into bottles.
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