摘要:
Ethylene copolymers having a relatively high melt flow ratio and a multimodal profile in a temperature rising elution fractionation (TREF) plot are disclosed. Such polymers are produced from a gas phase single reactor process where a phosphinimine-ligated group IV metallocene catalyst is used. The copolymers can be made into film having good dart impact values and good stiffness properties under decreased extruder pressures.
摘要:
Methods for dramatically altering the processability of ethylene copolymers made with a supported phosphinimine polymerization catalyst. The method involves changing the polymerization reactor temperature during the polymerization of ethylene and at least one alpha-olefin when a titanium-based phosphinimine catalyst which comprises a substituted or unsubstituted indenyl ligand and a phosphinimine type ligand is used. An increase in the polymerization temperature leads to a decrease in the copolymer stress exponent, and vice versa.
摘要:
Polyethylene is made by (co)polymerizing ethylene in a gas-phase reactor using a catalyst system comprising a chromium catalyst and a Group 4 transition metal catalyst, co-supported on an inorganic oxide support. The Group 4 transition metal catalyst is defined by the formula shown, wherein M is a Group 4 metal, PI is a phosphinimide or ketimide ligand (shown), L is a monoanionic ligand which is a cyclopentadienyl or a bulky heteroatom type ligand, m is 1 or 2, n is 0 or 1, and p is an integer. The co-supported catalyst system gives access to polyethylene having a broad or bimodal molecular weight distribution. In the copolymerization of ethylene, reversed or partially reversed comonomer distribution is achieved: the Group 4 component provides polymer segments having higher molecular weight and also higher comonomer incorporation than polymer segments produced at the chromium sites.
摘要:
A polymer blend comprising first and second polyethylene copolymers is presented which has good processability, and which when made into film shows good toughness-stiffness balance, reasonable MD tear, as well as good optical properties.
摘要:
A polymer blend comprising first and second polyethylene copolymers is presented which has good processability, and which when made into film shows good toughness-stiffness balance, reasonable MD tear, as well as good optical properties.
摘要:
Ethylene copolymers having a relatively high melt flow ratio, a multimodal profile in a temperature rising elution fractionation (TREF) plot, a reverse comonomer distribution profile, and a composition distribution breadth index CDBI 50 of from 35 wt% to 70 wt%, as determined by TREF, are disclosed. The copolymers can be made into films having good dart impact values and good stiffness properties under decreased extruder pressures. Preferably, the copolymers are prepared by a polymerization process involving a supported group 4 phosphinimine catalyst.
摘要:
Ethylene copolymers having a relatively high melt flow ratio and a multimodal profile in a temperature rising elution fractionation (TREF) plot are disclosed. The copolymers can be made into film having good dart impact values and good stiffness properties under decreased extruder pressures.