Ethylene copolymers made in the gas phase using a phosphinimine based single site catalyst supported on a passivated inorganic oxide support. The ethylene copolymers have a relatively narrow molecular weight distribution and good rheological parameters.

A solution polymerization process uses a reactor system in which a first stage is operated in a non adiabatic (cooled) manner and is connected to a second stage containing a downstream reactor that is operated adiabatically. In an embodiment, the first reactor stage includes at least one loop reactor and the second stage includes a tubular reactor. In an embodiment, the first stage is operated with a single site catalyst and at least one downstream reactor uses a Ziegler Natta catalyst.

Embodiments of the invention described herein relate to a polyethylene polymer composition suitable for use in the manufacture of packaging articles, flexible films and/or sheets. In one embodiment, the copolymer comprises a polyethylene resin with density 0.918 g/cm.sup.3 to about 0.935 g/cm.sup.3, G at G.sub.(500 Pa) value, as determined from Dynamic Mechanical Analysis at 190? C., of less than 40 Pa, M.sub.z/M.sub.w of greater than 2, CDBI.sub.50 of greater than 60. Other embodiments relate to polymer compositions with defined molecular characteristics and formulations suitable for use in the manufacture of articles including films, sheets, bags and pouches with improved creep resistance and high toughness and a good balance of film stiffness and processability in monolayer and/or multi-layer film structures.

Organometallic complexes are described which are useful as pre-polymerization catalysts which may form part of olefin polymerization catalyst systems. The catalyst systems find use in the polymerization of ethylene, optionally with one or more C.sub.3-12 alpha-olefin comonomers. The organometallic complexes are broadly represented by formula I: ##STR00001##
wherein L is a bridging group containing a contiguous chain of atoms connecting P with Cy, wherein the contiguous chain contains 2 or 3 atoms and wherein Cy is a cyclopentadienyl-type ligand. The olefin polymerization catalyst system is effective at polymerizing ethylene with alpha-olefins in a solution phase polymerization process at high temperatures and produces ethylene copolymers with high molecular weight and high degrees of alpha-olefin incorporation. Pre-metallation compounds, metallation processes and synthetic methods to make the organometallic complexes as well as polymerization processes are also described.

Provided herein are VLDPE polymer compositions suitable for use in the manufacture of flexible films or sheets. In one embodiment, the copolymer comprises a polyethylene VLDPE resin with M.sub.z/M.sub.w of greater than 2, CDBI.sub.50 of greater than 55 and a single melting peak in DSC measurement. The polymer compositions disclosed herein may be suitable for use in the manufacture of films with improved balance of film toughness, processability and sealability in monolayer and multi-layer film structures.

Disclosed herein are ethylene-based polymers generally characterized by a density from 0.89 to 0.93 g/cm.sup.3, a ratio of Mw/Mn from 3 to 6.5, a Mz from 200,000 to 650,000 g/mol, a CY-a parameter at 190 C. from 0.2 to 0.4, and a reverse short chain branching distribution. The ATREF profile of these polymers can have a high temperature peak from 92 to 102 C., and a low temperature peak from 18 to 36 C. less than that of the high temperature peak. These polymers can have comparable physical properties to that of a metallocene-catalyzed LLDPE, but with improved processability, shear thinning, and melt strength, and can be used in blown film and other end-use applications.

The present disclosure provides high density polyethylene resins having good low temperature impact resistance. The resins are suitable for use in rotomolding application for large parts. The resin is a bi- or trimodal resin produced using solution phase polymerization in the presence of a single site catalyst.

Provided herein are VLDPE polymer compositions suitable for use in the manufacture of flexible films or sheets. In one embodiment, the copolymer comprises a polyethylene VLDPE resin with M.sub.z/M.sub.w of greater than 2, CDBI.sub.50 of greater than 55 and a single melting peak in DSC measurement. The polymer compositions disclosed herein may be suitable for use in the manufacture of films with improved balance of film toughness, processability and sealability in monolayer and multi-layer film structures.

Methods for determining the concentration of transition metal compounds in a solution containing more than one transition metal compound are described. Polymerization reactor systems providing real-time monitoring and control of the concentrations of the transition metal components of a multicomponent catalyst system are disclosed, as well as methods for operating such polymerization reactor systems and for improving methods of preparing the multicomponent catalyst system.

Processes for preparing a polyethylene in at least one continuously stirred tank reactor are described herein. The process may comprise the step of: polymerizing ethylene in the presence of at least one supported metallocene catalyst, a diluent, optionally one or more co-monomers, and optionally hydrogen, thereby obtaining the polyethylene, wherein the supported metallocene catalyst comprises a solid support, a co-catalyst and at least one metallocene, wherein the solid support has a surface area within the range of from 100 to 500 m2/g, and has a D50 value within the range of from 4 m to 18 m, with D50 being defined as the particle size for which fifty percent by weight of the particles has a size lower than the D50; and D50 being measured by laser diffraction analysis on a Malvern type analyzer. Polyethylene obtained by the disclosed process and articles comprising the polyethylene are also described.