A process for preparing a polyethylene composition comprising contacting ethylene with a first salan catalyst precursor and an activator to form branched vinyl/vinylidene-terminated high density polyethylene having a number average molecular weight (Mn) of at least 5,000 g/mole; and contacting the branched vinyl/vinylidene-terminated high density polyethylene with ethylene and a second metallocene catalyst precursor and an activator to form a comb-block HDPE. The polyethylene composition comprises a polyethylene backbone, and one or more branched high density polyethylene combs pendant to the backbone, the combs having an Mn of at least 5,000 g/mole, where the polyethylene has a branching index (g′) of less than 0.9.

A process for preparing a polyethylene composition comprising contacting ethylene with a first salan catalyst precursor and an activator to form branched vinyl/vinylidene-terminated high density polyethylene having a number average molecular weight (Mn) of at least 5,000 g/mole; and contacting the branched vinyl/vinylidene-terminated high density polyethylene with ethylene and a second metallocene catalyst precursor and an activator to form a comb-block HDPE. The polyethylene composition comprises a polyethylene backbone, and one or more branched high density polyethylene combs pendant to the backbone, the combs having an Mn of at least 5,000 g/mole, where the polyethylene has a branching index (g′) of less than 0.9.

This invention relates to a supported catalyst system comprising: (i) at least one first catalyst component comprising a group 4 bis(phenolate) complex; (ii) at least one second catalyst component comprising a 2,6-bis(imino)pyridyl iron complex; (iii) activator; and (iv) support. The catalyst system may be used for preparing polyolefins, such a bimodal polyethylene, typically in a gas phase polymerization.

This invention relates to a supported catalyst system comprising: (i) at least one first catalyst component comprising a group 4 bis(phenolate) complex; (ii) at least one second catalyst component comprising a 2,6-bis(imino)pyridyl iron complex; (iii) activator; and (iv) support. The catalyst system may be used for preparing polyolefins, such a bimodal polyethylene, typically in a gas phase polymerization.

A polymer composition and a process for the production of this composition comprising a base resin is disclosed herein. The base resin includes a very high molecular weight component, a low molecular weight component, and a high molecular weight component having a weight average molecular weight higher than the weight average molecular weight of the low molecular weight component but lower than the weight average molecular weight of the very high molecular weight component. An amount of the very high molecular weight component in the base resin is 0.5 to 8 wt %. The very high molecular weight component has a viscosity average molecular weight of greater than 1100 kg/mol. The composition has FRR.sub.21/5 of equal to or greater than 38, a melt flow rate MFR.sub.21 of equal to or greater than 6.5 g/10 min and a viscosity at a shear stress of 747 Pa (eta747) of 450 to 3000 kPas.

A polymer composition and a process for the production of this composition comprising a base resin is disclosed herein. The base resin includes a very high molecular weight component, a low molecular weight component, and a high molecular weight component having a weight average molecular weight higher than the weight average molecular weight of the low molecular weight component but lower than the weight average molecular weight of the very high molecular weight component. An amount of the very high molecular weight component in the base resin is 0.5 to 8 wt %. The very high molecular weight component has a viscosity average molecular weight of greater than 1100 kg/mol. The composition has FRR.sub.21/5 of equal to or greater than 38, a melt flow rate MFR.sub.21 of equal to or greater than 6.5 g/10 min and a viscosity at a shear stress of 747 Pa (eta747) of 450 to 3000 kPas.

The present invention relates to an ethylene/alpha-olefin copolymer having excellent processability. The ethylene/alpha-olefin copolymer according to the present invention has excellent processability and is therefore suitable for producing products by an injection molding method.

The present invention relates to an ethylene/alpha-olefin copolymer having excellent processability. The ethylene/alpha-olefin copolymer according to the present invention has excellent processability and is therefore suitable for producing products by an injection molding method.

Disclosed are ethylene polymer compositions containing a homogeneously-branched first ethylene polymer component and 15-35 wt. % of a homogeneously-branched second ethylene polymer component of higher density than the first ethylene polymer component. The ethylene polymer composition can be characterized by a density from 0.912 to 0.925 g/cm.sup.3, a ratio of Mw/Mn from 2 to 5, a melt index less than 2 g/10 min, and a CY-a parameter at 190° C. from 0.35 to 0.7. These polymer compositions have the excellent dart impact strength and optical properties of a metallocene-catalyzed LLDPE, but with improved machine direction tear resistance, and can be used in blown film and other end-use applications. Further, methods for improving film Elmendorf tear strength also are described.

Disclosed are ethylene polymer compositions containing a homogeneously-branched first ethylene polymer component and 15-35 wt. % of a homogeneously-branched second ethylene polymer component of higher density than the first ethylene polymer component. The ethylene polymer composition can be characterized by a density from 0.912 to 0.925 g/cm.sup.3, a ratio of Mw/Mn from 2 to 5, a melt index less than 2 g/10 min, and a CY-a parameter at 190° C. from 0.35 to 0.7. These polymer compositions have the excellent dart impact strength and optical properties of a metallocene-catalyzed LLDPE, but with improved machine direction tear resistance, and can be used in blown film and other end-use applications. Further, methods for improving film Elmendorf tear strength also are described.