| 摘要 |
<p>A process for producing high density polyethylene having a bimodal molecular weight distribution, the process comprising pre-contacting a chromium-based catalyst with an alkyl metal oxane, the chromium-based catalyst comprising chromium oxide on a silica-containing support, to form a catalyst system wherein the atomic ratio of the metal of the oxane to the chromium is less than 1, and polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms in the presence of the catalyst system. A catalyst system for polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms to produce high density polyethylene, the catalyst system comprising in combination a chromium-based catalyst comprising chromium oxide on a silica-containing support and an alkyl metal oxane with which the chromium-based catalyst has been precontacted whereby the atomic ratio of the metal of the oxane to the chromium is less than 1. A process for producing high density polyethylene having a bimodal molecular weight distribution, the process comprising polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms in the presence of a catalyst system comprising a chromium-based catalyst, comprising chromium oxide on a silica-containing support, and an alkyl metal oxane in an amount of around 0.45 wt.% based on the weight of the chromium-based catalyst.</p> |
