Abstract: The present invention provides a process for the preparation of a multimodal polyethylene comprising: (i) polymerising ethylene and optionally an ?-olefin comonomer in a first polymerisation stage to produce a first ethylene polymer; and (ii) polymerising ethylene and optionally an ?-olefin comonomer, in the presence of said first ethylene polymer, in a second polymerisation stage, wherein the first and second polymerisation stages are carried out in the presence of an unsupported metallocene catalyst and each polymerisation stage produces at least 5% wt of the multimodal polyethylene, and the multimodal polyethylene has a multimodal molecular weight distribution, a molecular weight of at least 50,000 g/mol and a bulk density of at least 250 g/dm3, and wherein a solution of the unsupported metallocene catalyst in a solvent is employed.

Abstract: The present invention provides a process for the preparation of a multimodal polyethylene comprising: (i) polymerising ethylene and optionally an ?-olefin comonomer in a first polymerisation stage to produce a first ethylene polymer; and (ii) polymerising ethylene and optionally an ?-olefin comonomer, in the presence of said first ethylene polymer, in a second polymerisation stage, wherein the first and second polymerisation stages are carried out in the presence of an unsupported metallocene catalyst and each polymerisation stage produces at least 5% wt of the multimodal polyethylene, and the multimodal polyethylene has a multimodal molecular weight distribution, a molecular weight of at least 50,000 g/mol and a bulk density of at least 250 g/dm3, and wherein a solution of the unsupported metallocene catalyst in a solvent is employed.

Abstract: The present invention provides a process for the preparation of a multimodal polyethylene comprising: (i) polymerizing ethylene and optionally an ?-olefin comonomer in a first polymerization stage to produce a first ethylene polymer; and (ii) polymerizing ethylene and optionally an ?-olefin comonomer, in the presence of said first ethylene polymer, in a second polymerization stage, wherein the first and second polymerization stages are carried out in the presence of an unsupported metallocene catalyst and each polymerization stage produces at least 5% wt of the multimodal polyethylene, and the multimodal polyethylene has a multimodal molecular weight distribution, a molecular weight of at least 50,000 g/mol and a bulk density of at least 250 g/dm3, and wherein a solution of the unsupported metallocene catalyst in a solvent is employed.

Abstract: The present invention provides a process for the preparation of a multimodal polyethylene, said multimodal polyethylene preferably having a bimodal or trimodal M.W. distribution, comprising: (i) polymerizing ethylene and optionally an ?-olefin comonomer in a first polymerization stage to produce a first ethylene polymer; and (ii) polymerizing ethylene and optionally an ?-olefin comonomer, in the presence of said first ethylene polymer, in a second polymerization stage, wherein said first and second polymerization stages are carried out in the presence of an unsupported metallocene catalyst, which is a complex of a group 4-10 metal having at least two ligands, wherein at least one of the ligands is persubstituted and comprises a delocalized pi system of electrons, each polymerization stage produces at least 5% wt of said multimodal polyethylene, and said multimodal polyethylene has a multimodal M.W. distribution, a M.W. of at least 50,000 g/mol and a bulk density of at least 250 g/dm3.

Abstract: The present invention provides a process for the preparation of a multimodal polyethylene comprising: (i) polymerising ethylene and optionally an ?-olefin comonomer in a first polymerisation stage to produce a first ethylene polymer; and (ii) polymerising ethylene and optionally an ?-olefin comonomer, in the presence of said first ethylene polymer, in a second polymerisation stage, wherein the first and second polymerisation stages are carried out in the presence of an unsupported metallocene catalyst and each polymerisation stage produces at least 5% wt of the multimodal polyethylene, and the multimodal polyethylene has a multimodal molecular weight distribution, a molecular weight of at least 50,000 g/mol and a bulk density of at least 250 g/dm3, and wherein a solution of the unsupported metallocene catalyst in a solvent is employed.

Abstract: A peroxide crosslinked ethylene polymer pressure pipe and a method for the preparation thereof are described. The pipe is characterized in that it comprises an ethylene polymer with a density of less than 950 kg/m3 obtained by polymerization with a single-site catalyst and having a shear thinning index, SHI5/300 of less than 20 and a MWD of <10. The method is characterized in that it comprises polymerizing ethylene, optionally together with at least one comonomer, with a single-site catalyst to provide the above defined ethylene polymer, forming the ethylene polymer into a pipe by extrusion and crosslinking it.

Abstract: A polyethylene moulding composition having a multimodal molecular weight distribution, having a density according to ISO 1183 at 23° C. in the range of 920 to 960 kg/m3 and an MFR190/2 according to ISO 1133 in the range of 0.

Abstract: An alkene interpolymer is prepared by polymerizing at least one 3-substituted C4-10 alkene and at least one C2-8 alkene in a gas phase polymerization using a Ziegler Natta polymerization catalyst system.

Abstract: An alkene interpolymer is prepared by polymerizing at least one 3-substituted C4-10 alkene and at least one C2-8 alkene in a gas phase polymerization using a polymerization catalyst system.

Abstract: A polyethylene moulding composition having a multimodal molecular weight distribution, having a density according to ISO 1183 at 23° C. in the range of 920 to 960 kg/m3 and an MFR190/2 according to ISO 1133 in the range of 0.

Abstract: An alkene interpolymer is prepared by polymerizing at least one 3-substituted C4-10 alkene and at least one C2-8 alkene in a gas phase polymerization using a polymerization catalyst system.

Abstract: A film, comprising: an interpolymer of ethylene; and a 3-substituted C4-10 alkene, wherein said interpolymer is prepared using a catalyst system comprising a single site catalyst.

Abstract: A multimodal medium density polyethylene polymer obtainable using single site catalysis which comprises at least: (A) a lower molecular weight (LMW) component which is a copolymer of ethylene with at least one comonomer, and (B) a higher molecular weight (HMW) component which is a copolymer of ethylene with at least one comonomer; wherein said multimodal medium density polyethylene polymer has a density of more than 925 kg/m3; and the ratio between the comonomer content in mol-% present in LMW component (A) and the total comonomer content in mol-% present in the multimodal medium density polyethylene polymer is more than 0.3.

Abstract: Use of a catalyst composition treated with a surface modifier in the polymerization of olefins for lowering the gel content in the resulting polyolefin, wherein the surface modifier has a polar residue capable of interacting with the surface of the catalyst composition and a lipophilic residue and is selected from carboxylate metal salts, nitrogen containing catalyst surface modifiers, phosphorus containing catalyst surface modifiers, oxygen containing catalyst surface modifiers, sulfur containing catalyst surface modifiers, fluoro containing polymeric catalyst surface modifiers or mixtures thereof and wherein the gel content is determined by using pressed plate gel analysis method.

Abstract: A peroxide crosslinked ethylene polymer pressure pipe and a method for the preparation thereof are described. The pipe is characterised in that it comprises an ethylene polymer with a density of less than 950 kg/m3 obtained by polymerisation with a single-site catalyst and having a shear thinning index, SHI5/300 of less than 20 and a MWD of <10. The method is characterised in that it comprises polymerising ethylene, optionally together with at least one comonomer, with a single-site catalyst to provide the above defined ethylene polymer, forming the ethylene polymer into a pipe by extrusion and crosslinking it.

Abstract: The invention provides a process for the preparation of a supported polymerization catalyst, said process comprising impregnating a porous particulate support in a mechanically fluidized state with a catalyst material.

Abstract: A polyethylene produced by the homopolymerisation of ethylene or copolymerisation of ethylene with &agr;-olefins in the presence of a catalyst, characterized in that the fraction of low molecular weight polymers having MW<5000 g/mole is lower than 12% by weight of the produced polymer, and that the produced polyethylene has a measured melt strength expressed by a haul-off (HO) value satisfying the expression: HO>K1·&eegr;0.05+K2, wherein K1 is 9.10−5 and K2 is 0.4.