This invention covers injection stretch blow molded articles prepared from polyethylene resin having a bimodal molecular weight distribution (MWD), defined by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), of from 2 to 20, comprising two polyethylene fractions A and B, fraction A being substantially free of comonomer and having a lower weight average molecular weight and a higher density than fraction B, each fraction prepared in different reactors of two reactors connected in series in the presence of a metallocene-containing catalyst system.

This invention relates to transition metal complexes of a dianionic, tridentate ligand that features a central neutral heterocyclic Lewis base and two phenolate donors, where the tridentate ligand coordinates to the metal center to form two eight-membered rings. Preferably the bis(phenolate) complexes are represented by Formula (I): ##STR00001##
where M, L, X, m, n, E, E′, Q, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.1′, R.sup.2′, R.sup.3′, R.sup.4′, A.sup.1, A.sup.1′, ##STR00002##
are as defined herein, where A.sup.1QA.sup.1′ are part of a heterocyclic Lewis base containing 4 to 40 non-hydrogen atoms that links A.sup.2 to A.sup.2′ via a 3-atom bridge with Q being the central atom of the 3-atom bridge.

This invention relates to transition metal complexes of a dianionic, tridentate ligand that features a central neutral heterocyclic Lewis base and two phenolate donors, where the tridentate ligand coordinates to the metal center to form two eight-membered rings. Preferably the bis(phenolate) complexes are represented by Formula (I): ##STR00001##
where M, L, X, m, n, E, E′, Q, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.1′, R.sup.2′, R.sup.3′, R.sup.4′, A.sup.1, A.sup.1′, ##STR00002##
are as defined herein, where A.sup.1QA.sup.1′ are part of a heterocyclic Lewis base containing 4 to 40 non-hydrogen atoms that links A.sup.2 to A.sup.2′ via a 3-atom bridge with Q being the central atom of the 3-atom bridge.

A pipe including polyethylene produced in the presence of a solid catalyst and a co-catalyst, wherein the solid catalyst is prepared by the steps of: (a) contacting a dehydrated support having hydroxyl groups with a compound of formula MgR.sup.1R.sup.2; (b) contacting the product of step (a) with modifying compounds (A), (B) and (C), wherein: (A) is carboxylic acid, carboxylic acid ester, ketone, acyl halide, aldehyde or alcohol; (B) is of formula R.sup.11.sub.f(R.sup.12O).sub.gSiX.sub.h wherein f, g and h 0 to 4 and the sum of f, g and h=4 provided that when h=4 then compound (A) is not an alcohol; (C) is a compound of formula (R.sup.13O).sub.4M, wherein M is a titanium atom, a zirconium atom or a vanadium atom; and (c) contacting the product of step (b) with a titanium halide TiX.sub.4, whereby the polyethylene has a molecular weight of 720,000 to less than 2,500,000 g/mol.

The invention relates to a continuous process for the production of ultra-high molecular weight polyethylene with an Elongational Stress of at least 0.43 N/mm.sup.2. The polymerisation of ethylene takes place in the presence of a catalyst and hydrogen. It is an advantage of the process according to the invention that the use of small amounts of hydrogen during the production of UHM-WPE reduces reactor fouling. Furthermore, the process according to the invention results in longer run times in polymerization reactors, less cleaning cycles to remove reactor fouling and in less need for other anti-fouling agents or anti-static agents.

The invention relates to a continuous process for the production of ultra-high molecular weight polyethylene with an Elongational Stress of at least 0.43 N/mm.sup.2. The polymerisation of ethylene takes place in the presence of a catalyst and hydrogen. It is an advantage of the process according to the invention that the use of small amounts of hydrogen during the production of UHM-WPE reduces reactor fouling. Furthermore, the process according to the invention results in longer run times in polymerization reactors, less cleaning cycles to remove reactor fouling and in less need for other anti-fouling agents or anti-static agents.

The present invention deals with a process for polymerising ethylene in the presence of an olefin polymerisation catalyst comprising titanium, magnesium and halogen in at least one polymerisation stage where ethylene is polymerised in slurry, the process comprising treating the polymerisation catalyst in a pre-treatment step by polymerising an olefin on the polymerisation catalyst so that the ratio of the weight of the olefin polymer to the weight of the original solid catalyst component is from 0.1 to 10 g/g and using the pre-treated catalyst in the production of ultra-high molecular weight polyethylene.

The present invention deals with a process for polymerising ethylene in the presence of an olefin polymerisation catalyst comprising titanium, magnesium and halogen in at least one polymerisation stage where ethylene is polymerised in slurry, the process comprising treating the polymerisation catalyst in a pre-treatment step by polymerising an olefin on the polymerisation catalyst so that the ratio of the weight of the olefin polymer to the weight of the original solid catalyst component is from 0.1 to 10 g/g and using the pre-treated catalyst in the production of ultra-high molecular weight polyethylene.

An UHMWPE film having a tensile strength of at least 2.0 GPa, a tensile energy to break of at least 30 J/g, an Mw of at least 500 000 gram/mole, and a Mw/Mn ratio of at most 6, and a film width of at least 5 mm. The film may be manufactured via a process which comprises subjecting a starting UHMWPE with a weight average molecular weight of at least 500 000 gram/mole, an elastic shear modulus determined directly after melting at 160° C. of at most 1.4 MPa, and a Mw/Mn ratio of at most 6 to a compacting step and a stretching step under such conditions that at no point during the processing of the polymer its temperature is raised to a value above its melting point. The film may be used as starting material in any applications where high tensile strength and high energy to break are important. Suitable applications include ballistic applications, ropes, cables, nets, fabrics, and protective applications.

An UHMWPE film having a tensile strength of at least 2.0 GPa, a tensile energy to break of at least 30 J/g, an Mw of at least 500 000 gram/mole, and a Mw/Mn ratio of at most 6, and a film width of at least 5 mm. The film may be manufactured via a process which comprises subjecting a starting UHMWPE with a weight average molecular weight of at least 500 000 gram/mole, an elastic shear modulus determined directly after melting at 160° C. of at most 1.4 MPa, and a Mw/Mn ratio of at most 6 to a compacting step and a stretching step under such conditions that at no point during the processing of the polymer its temperature is raised to a value above its melting point. The film may be used as starting material in any applications where high tensile strength and high energy to break are important. Suitable applications include ballistic applications, ropes, cables, nets, fabrics, and protective applications.