| 摘要 |
<p>Method for making a homopolymer of propylene or a copolymer of propylene with up to 20 mole percent of ethylene comprising: (a) in one stage producing a homopolymer or copolymer of propylene having a relatively high weight average molecular weight and comprising at least about 5 weight percent of the total amount of final propylene produced, and (b) in another stage producing a homopolymer or copolymer having a relatively low molecular weight and comprising at least about 10 weight percent of the total amount of final propylene produced; wherein the molecular weight of the final homopolymer or copolymer of propylene produced is in the range of from about 150,000 to about 1,500,000; wherein the products formed in steps (a) and (b) comprise at least about 50 weight percent of the total amount of final homopolymer or copolymer of propylene produced; wherein a molecular weight control agent is employed in at least one of stage (a) and stage (b) in a sufficient amount that a homopolymer or copolymer of propylene having a molecular weight in the respective molecular weight range for such stage is produced; and wherein the aforesaid catalyst system comprises a supported catalyst comprising a solid hydrocarbon-insoluble composite of a titanium-containing component supported on a magnesium-containing compound and a co-catalyst comprising a Group II or III metal alkyl.</p> |
