Abstract: An uncompounded particulate metallocene-produced polyethylene can have a multimodal molecular weight distribution and particle size distribution measured by obtaining at least four fractions by sieving. A set of Mw values including an Mw value for each fraction can be obtained. A set of Mn values including an Mn value for each fraction can be obtained. A ratio between a standard deviation value of the Mw set and a mean value of the Mw set can be equal to or less than 0.15. A ratio between a standard deviation value of the Mn set and a mean value of the Mn set can be equal to or less than 0.15. The uncompounded particulate metallocene-produced polyethylene can be prepared by a process that includes polymerization in an apparatus. The apparatus can include at least three serially connected loop reactors.

Abstract: A method can include consecutively batch processing at least two different polyethylene grades in pellet form in a pellet handling unit. A ratio of a melt flow index (MI) of a first polyethylene in pellet form (MIf) to a MI of a later processed polyethylene in pellet form (MIl) can be smaller than 0.30. The method can include processing an intermediate polyethylene grade in pellet form. An amount of intermediate polyethylene grade processed can be at most 1/100th of a handling capacity of the pellet handling unit. The intermediate polyethylene grade can have the same MI as the later processed polyethylene in pellet form.

Abstract: A process for preparing a multimodal polyethylene product with at least two different polyethylene resins includes producing a first polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The Ziegler-Natta catalyst used for the production of the first polyethylene resin has an average particle size (D50) of at most 15 ?m. The process includes separately producing a second polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The process includes physically blending together the first and second polyethylene resins to produce a multimodal polyethylene product.

Abstract: The present invention relates to a method for consecutively producing at least two different polyethylene resins in one slurry loop reactor, comprising producing a first polyethylene resin in the presence of a Ziegler-Natta and/or a Chromium catalyst, and consecutively producing a second polyethylene resin in the presence of a metallocene catalyst, characterized in that the ratio of the melt flow index of the first produced polyethylene resin to the melt flow index of the second produced polyethylene resin is at least 0.3.

Abstract: A process for preparing a homogeneous polyethylene product can include producing a first polyethylene resin in the presence of a metallocene catalyst in a reactor. The first polyethylene resin can have a density of from 0.942 to 0.970 g/cm3 and an HLMI of from 0.5 to 150 g/10 min. The process can include separately producing a second polyethylene resin in the presence of a chromium catalyst in a reactor. The process can include physically blending together the first polyethylene resin and the second polyethylene resin to produce the homogeneous polyethylene product. The homogeneous polyethylene product can include at least 25% by weight of the first polyethylene resin.

Abstract: A process for preparing a polyolefin product can include providing a first high molecular weight (HMW) polyolefin resin having an HLMI of between 0.01 and 5 g/10 min, and separately providing a second low molecular weight (LMW) polyolefin resin having an MI2 of between 1 and 150 g/10 min. A device can be used to continuously physically melt and blend the first HMW polyolefin resin and the second LMW polyolefin resin to produce the polyolefin product. The device can include at least two feeding zones spatially separated and operably connected to each other. At least a art of the first HMW polyolefin resin is introduced in a first feeding zone, and at least a part of the second LMW polyolefin is introduced in a second feeding zone different from the first zone.

Abstract: A process of preparing a polyolefin in a loop reactor in the presence of antifouling agent can include feeding into the loop reactor diluent, monomers, optionally hydrogen, and optionally one or more co-monomers to produce a liquid phase. Antifouling agent and catalyst can be introduced into the loop reactor. The process can include polymerizing the monomers and optional co-monomers to form the polyolefin. The process can be characterized in that a time difference between introduction of the antifouling agent and introduction of the catalyst is at most 3 hours. The process can be characterized in that the catalyst is introduced into a liquid phase when a concentration of the antifouling agent ranges from 0 ppm to less than 0.3 ppm.

Abstract: The present invention relates the use of a pump in a loop reactor for the production of polyethylene, as well as a reactor comprising such pump and methods for producing polyolefin by means of such reactor. The pump according to the invention is characterized in that it is an axial flow impeller circulation pump, wherein the impeller comprises 6 blades and wherein the pump is fixed on a spring supported frame. Use of the pump according to the present invention allows for preparation of homogeneous polyethylene products that meet high quality standards from the complicated ethylene polymerization mixtures while at the same time being produced with low energy consumption.

Abstract: The present invention relates to a process of preparing a polyolefin in a loop reactor by introducing anti-fouling agent in by-pass pipes. Also, the invention relates to the use of anti-fouling agent to prevent blockage by feeding the anti-fouling agent into the by-pass pipes of the loop reactor.

Abstract: A process for preparing a homogeneous polyethylene product can include producing a first polyethylene resin in the presence of a metallocene catalyst in a reactor. The first polyethylene resin can have a density of from 0.940 to 0.970 g/cm3. The first polyethylene resin can have a Low Molecular Weight (LMW) with an MI2 of between 2 and 250 g/10 min. The process can include separately producing a second polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The second polyethylene resin can have a High Molecular Weight (HMW) with an MI2 of between 0.01 and 15 g/10 min. The process can include physically blending together the first polyethylene resin and the second polyethylene resin to produce the homogeneous polyethylene product.

Abstract: The present invention relates to a method for optimizing the sequential use of at least two ethylene polymerization catalysts to an ethylene polymerization loop reactor, comprising: transferring to a mixing vessel a first ethylene polymerization catalyst and a first diluent, thereby providing a first catalyst slurry, transferring said first catalyst slurry from said mixing vessel to an ethylene polymerization loop reactor at a concentration suitable for polymerizing ethylene, increasing the ratio of said diluent to said first ethylene polymerization catalyst in said first catalyst slurry, stopping the supply of said first catalyst slurry to said mixing vessel, stopping the supply of said first catalyst slurry to said ethylene polymerization loop reactor, stopping the supply of ethylene to said ethylene polymerization loop reactor, removing said first catalyst slurry from said ethylene polymerization loop reactor, emptying said mixing vessel, optionally rinsing said mixing vessel with fresh diluent, transfe

Abstract: A process for preparing a multimodal polyethylene product with at least two different polyethylene resins includes producing a first polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The Ziegler-Natta catalyst used for the production of the first polyethylene resin has an average particle size (D50) of at most 15 ?m. The process includes separately producing a second polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The process includes physically blending together the first and second polyethylene resins to produce a multimodal polyethylene product.

Abstract: The present invention relates to a process for improving the polymerization of ethylene and one or more optional co-monomer(s) in a polymerization loop reactor characterized in that said process comprises the step of controlling the hydrogen/monomer ratio along the path of the reactor by multiple, spatially separated, feeding of hydrogen along the path of the loop reactor. In particular, the invention provides a process for controlling, and preferably narrowing, the molecular weight distribution of the produced polymer particles. In another aspect, the invention relates to a polymerization loop reactor suitable for the polymerization process of ethylene and an optional olefin co-monomer, wherein the molecular weight distribution of the produced ethylene polymer can be controlled.

Abstract: The invention relates to a catalyst metering device with a valve formed of an iron-based alloy steel hardened to a Rockwell hardness C of at least 60. The device can be used for metering of a catalyst for an ethylene polymerization reaction. The invention further relates to ethylene polymerization wherein the catalyst is metered in a catalyst metering device with a iron-based alloy steel hardened valve, as well as to a ethylene polymerization reactor comprising such a catalyst metering device.

Abstract: A process for preparing a multimodal polyethylene product with at least two different polyethylene resins can include producing a first polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The Ziegler-Natta catalyst used for the production of the first polyethylene resin has an average particle size (D50) of at most 15 ?m. The HLMI of the first polyethylene resin is between 0.01 and 5 g/10 min. The process can include separately producing a second polyethylene resin in the presence of a Ziegler-Natta catalyst in a reactor. The MI2 of the second polyethylene resin is between 1 and 150 g/10 min. The process can include physically blending together the first and second polyethylene resins to produce a multimodal polyethylene product. The physical blending can be performed in a device for continuously melting and blending the first and second polyethylene resins.

Abstract: The present invention relates to a method for optimizing the sequential use of at least two ethylene polymerization catalysts to an ethylene polymerization loop reactor, comprising: transferring to a mixing vessel a first ethylene polymerization catalyst and a first diluent, thereby providing a first catalyst slurry, transferring said first catalyst slurry from said mixing vessel to an ethylene polymerization loop reactor at a concentration suitable for polymerizing ethylene, increasing the ratio of said diluent to said first ethylene polymerization catalyst in said first catalyst slurry, stopping the supply of said first catalyst slurry to said mixing vessel, stopping the supply of said first catalyst slurry to said ethylene polymerization loop reactor, stopping the supply of ethylene to said ethylene polymerization loop reactor, removing said first catalyst slurry from said ethylene polymerization loop reactor, emptying said mixing vessel, optionally rinsing said mixing vessel with fresh diluent, transfe

Abstract: The present invention relates to a method for optimizing the sequential use of at least two ethylene polymerization catalysts to an ethylene polymerization loop reactor, comprising: transferring to a mixing vessel a first ethylene polymerization catalyst and a first diluent, thereby providing a first catalyst slurry, transferring said first catalyst slurry from said mixing vessel to an ethylene polymerization loop reactor at a concentration suitable for polymerizing ethylene, increasing the ratio of said diluent to said first ethylene polymerization catalyst in said first catalyst slurry, stopping the supply of said first catalyst slurry to said mixing vessel, stopping the supply of said first catalyst slurry to said ethylene polymerization loop reactor, stopping the supply of ethylene to said ethylene polymerization loop reactor, removing said first catalyst slurry from said ethylene polymerization loop reactor, emptying said mixing vessel, optionally rinsing said mixing vessel with fresh diluent, transfe

Abstract: An uncompounded particulate metallocene-produced polyethylene can have a multimodal molecular weight distribution and particle size distribution measured by obtaining at least four fractions by sieving. A set of Mw values including an Mw value for each fraction can be obtained. A set of Mn values including an Mn value for each fraction can be obtained. A ratio between a standard deviation value of the Mw set and a mean value of the Mw set can be equal to or less than 0.15. A ratio between a standard deviation value of the Mn set and a mean value of the Mn set can be equal to or less than 0.15. The uncompounded particulate metallocene-produced polyethylene can be prepared by a process that includes polymerization in an apparatus. The apparatus can include at least three serially connected loop reactors.

Abstract: A process of preparing a polyolefin in a loop reactor in the presence of antifouling agent can include feeding into the loop reactor diluent, monomers, optionally hydrogen, and optionally one or more co-monomers to produce a liquid phase. Antifouling agent and catalyst can be introduced into the loop reactor. The process can include polymerizing the monomers and optional co-monomers to form the polyolefin. The process can be characterized in that a time difference between introduction of the antifouling agent and introduction of the catalyst is at most 3 hours. The process can be characterized in that the catalyst is introduced into a liquid phase when a concentration of the antifouling agent ranges from 0 ppm to less than 0.3 ppm.

Abstract: The present invention relates to a process of preparing a polyethylene in a loop reactor in the presence of antifouling agent comprising the steps of: a) feeding into said loop reactor diluent, monomers, optionally hydrogen, and optionally one or more co-monomers to produce a liquid phase; b) introducing antifouling agent into said loop reactor, c) introducing a catalyst into the liquid phase to produce a slurry; and d) polymerizing the monomers and optional co-monomers to form the polyethylene, characterized in that the time difference between introduction of the antifouling agent and introduction of the catalyst is at most 3 hours.