| 摘要 |
<p>Preparation of a polyethylene resin from two polyethylene copolymers using a chemically reduced chromium-based catalyst, gives a broader molecular weight distribution and a higher shear response. Preparation of a polyethylene resin comprises (i) polymerizing ethylene or copolymerizing ethylene and a comonomer comprising at least one 3-8C alpha -olefin, in a first polymerization reactor, in the presence of a chemically reduced chromium-based catalyst to give polyethylene homo- or copolymer; and (ii) copolymerizing, in a second polymerization reactor downstream of the first one, ethylene in the presence of the chromium-based catalyst and a cocatalyst from an ethylene monomer, a fed in comonomer comprising at least one 3-8C alpha -olefin and a comonomer generated in-situ to give polyethylene copolymer.</p> |
