The present application relates to a process for producing a multimodal polyethylene composition comprising the steps of polymerizing a polyethylene fraction (A-1) having a weight average molecular weight Mw of equal to or more than 500 kg/mol to equal to or less than 10,000 kg/mol and a density of equal to or more than 915 kg/m.sup.3 to equal to or less than 960 kg/m.sup.3 in one reaction step and polymerizing a polyethylene fraction (A-2) having a lower weight average molecular weight Mw as polyethylene fraction (A-1) and a density of equal to or more than 910 kg/m.sup.3 to equal to or less than 975 kg/m.sup.3 in a second reaction step of a sequential multistage process wherein one of said polyethylene fractions is polymerized in the presence of the other of said polyethylene fractions to form a first polyethylene resin (A) having a weight average molecular weight Mw of equal to or more than 150 kg/mol to equal to or less than 1,500 kg/mol, and a density of equal to or more than 910 kg/m.sup.3 to equal to or less than 975 kg/m.sup.3, wherein the weight average molecular weight Mw of the first polyethylene resin (A) is lower than the weight average molecular weight Mw of the polyethylene fraction (A-1), blending the first polyethylene resin (A) with a second polyethylene resin (B) having a weight average molecular weight Mw of equal to or more than 50 kg/mol to less than 500 kg/mol, and a density of equal to or more than 910 kg/m.sup.3 to equal to or less than 970 kg/m.sup.3 to form said multimodal polyethylene composition, wherein the multimodal polyethylene composition a melt flow rate MFR.sub.5 (190° C., 5 kg) of 0.01 to 10 g/10 min and a density of equal to or more than 910 kg/m.sup.3 to equal to or less than 970 kg/m.sup.3 a polyethylene composition obtainable by said process and the polyethylene resin of said first polymerization step.

The present invention relates to a process for producing a multimodal polyethylene composition in the reactor system according to the invention, comprising; (a) polymerizing ethylene in an inert hydrocarbon medium in the first reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and hydrogen in an amount of 0.1-95% by mol with respect to the total gas present in the vapor phase in the first reactor to obtain a low molecular weight polyethylene or a medium molecular weight polyethylene; (b) removing in the hydrogen removal unit 98.0 to 99.8% by weight of the hydrogen comprised in a slurry mixture obtained from the first reactor at a pressure in the range of 103-145 kPa (abs) and transferring the obtained residual mixture to the second reactor; (c) polymerizing ethylene and optionally C.sub.4 to C.sub.12 α-olefin comonomer in the second reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and in the presence of hydrogen in an amount obtained in step (b) to obtain a first high molecular weight polyethylene or a first ultra high molecular weight polyethylene in the form of a homopolymer or a copolymer and transferring a resultant mixture to the third reactor; and (d) polymerizing ethylene, and optionally α-olefin comonomer in the third reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and hydrogen, wherein the amount of hydrogen in the third reactor is in a range of 1-70% by mol, preferably 1-60% by mol with respect to the total gas present in the vapor phase in the third reactor or optionally substantial absence of hydrogen to obtain a second high molecular weight polyethylene or a second ultra high molecular weight polyethylene homopolymer or copolymer; and a multimodal polyethylene composition obtainable this way.

The present invention relates to a process for producing a multimodal polyethylene composition in the reactor system according to the invention, comprising; (a) polymerizing ethylene in an inert hydrocarbon medium in the first reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and hydrogen in an amount of 0.1-95% by mol with respect to the total gas present in the vapor phase in the first reactor to obtain a low molecular weight polyethylene or a medium molecular weight polyethylene; (b) removing in the hydrogen removal unit 98.0 to 99.8% by weight of the hydrogen comprised in a slurry mixture obtained from the first reactor at a pressure in the range of 103-145 kPa (abs) and transferring the obtained residual mixture to the second reactor; (c) polymerizing ethylene and optionally C.sub.4 to C.sub.12 α-olefin comonomer in the second reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and in the presence of hydrogen in an amount obtained in step (b) to obtain a first high molecular weight polyethylene or a first ultra high molecular weight polyethylene in the form of a homopolymer or a copolymer and transferring a resultant mixture to the third reactor; and (d) polymerizing ethylene, and optionally α-olefin comonomer in the third reactor in the presence of a catalyst system, selected from Ziegler-Natta catalyst or metallocene, and hydrogen, wherein the amount of hydrogen in the third reactor is in a range of 1-70% by mol, preferably 1-60% by mol with respect to the total gas present in the vapor phase in the third reactor or optionally substantial absence of hydrogen to obtain a second high molecular weight polyethylene or a second ultra high molecular weight polyethylene homopolymer or copolymer; and a multimodal polyethylene composition obtainable this way.

The present invention relates to a multimodal polymer of ethylene, to the use of the multimodal polymer of ethylene in film applications and to a film comprising the multimodal polymer of ethylene of the invention.

The present invention relates to a multimodal polymer of ethylene, to the use of the multimodal polymer of ethylene in film applications and to a film comprising the multimodal polymer of ethylene of the invention.

In various embodiments, a bimodal polyethylene composition may have a density (ρ) from 0.952 g/cm.sup.3 to 0.957 g/cm.sup.3, a high load melt index (I.sub.21) from 1 to 10 dg/min, and a z-average molecular weight (M.sub.z(GPC)) from 3,200,000 to 5,000,000 g/mol. The bimodal polyethylene composition may also have a peak molecular weight (M.sub.p(GPC)) defined by the equation: M.sub.p(GPC)<−2,805.3 MWD+102,688, wherein MWD is a molecular weight distribution defined by the equation: MWD=M.sub.w(GPC)/M.sub.n(GPC), M.sub.w(GPC) is a weight average molecular weight of the bimodal polyethylene composition, M.sub.n(GPC) is a number average molecular weight of the bimodal polyethylene composition. Additionally, the bimodal polyethylene composition has a ratio of the (Mz(GPC)) to the Mw(GPC) from 8.5 to 10.5. Articles made from the bimodal polyethylene composition, such as articles made by blow molding processes, are also provided.

In various embodiments, a bimodal polyethylene composition may have a density (ρ) from 0.952 g/cm.sup.3 to 0.957 g/cm.sup.3, a high load melt index (I.sub.21) from 1 to 10 dg/min, and a z-average molecular weight (M.sub.z(GPC)) from 3,200,000 to 5,000,000 g/mol. The bimodal polyethylene composition may also have a peak molecular weight (M.sub.p(GPC)) defined by the equation: M.sub.p(GPC)<−2,805.3 MWD+102,688, wherein MWD is a molecular weight distribution defined by the equation: MWD=M.sub.w(GPC)/M.sub.n(GPC), M.sub.w(GPC) is a weight average molecular weight of the bimodal polyethylene composition, M.sub.n(GPC) is a number average molecular weight of the bimodal polyethylene composition. Additionally, the bimodal polyethylene composition has a ratio of the (Mz(GPC)) to the Mw(GPC) from 8.5 to 10.5. Articles made from the bimodal polyethylene composition, such as articles made by blow molding processes, are also provided.

A first embodiment which is a bimodal polymer having a weight fraction of a lower molecular weight (LMW) component ranging from about 0.25 to about 0.45, a weight fraction of a higher molecular weight (HMW) component ranging from about 0.55 to about 0.75 and a density of from about 0.931 g/cc to about 0.955 g/cc which when tested in accordance with ASTM D1003 using a 1 mil test specimen displays a haze characterized by equation: % Haze=2145−2216*Fraction.sub.LMW−181*a molecular weight distribution of the LMW component (MWD.sub.LMW)−932*a molecular weight distribution of the HMW component (MWD.sub.HMW)+27*(Fraction.sub.LMW*MWD.sub.LMW)+1019*(Fraction.sub.LMW*MWD.sub.HMW)+73*(MWD.sub.LMW*MWD.sub.HMW) wherein fraction refers to the weight fraction of the component in the polymer as a whole.

A first embodiment which is a bimodal polymer having a weight fraction of a lower molecular weight (LMW) component ranging from about 0.25 to about 0.45, a weight fraction of a higher molecular weight (HMW) component ranging from about 0.55 to about 0.75 and a density of from about 0.931 g/cc to about 0.955 g/cc which when tested in accordance with ASTM D1003 using a 1 mil test specimen displays a haze characterized by equation: % Haze=2145−2216*Fraction.sub.LMW−181*a molecular weight distribution of the LMW component (MWD.sub.LMW)−932*a molecular weight distribution of the HMW component (MWD.sub.HMW)+27*(Fraction.sub.LMW*MWD.sub.LMW)+1019*(Fraction.sub.LMW*MWD.sub.HMW)+73*(MWD.sub.LMW*MWD.sub.HMW) wherein fraction refers to the weight fraction of the component in the polymer as a whole.

Catalyst compositions containing a metallocene compound, a solid activator, and a co-catalyst, in which the solid activator or the supported metallocene catalyst has a d50 average particle size of 15 to 50 μm and a particle size distribution of 0.5 to 1.5, can be contacted with an olefin in a loop slurry reactor to produce an olefin polymer. A representative ethylene-based polymer produced using the catalyst composition has excellent dart impact strength and low gels, and can be characterized by a HLMI from 4 to 10 g/10 min, a density from 0.944 to 0.955 g/cm.sup.3, a higher molecular weight component with a Mn from 280,000 to 440,000 g/mol, and a lower molecular weight component with a Mw from 30,000 to 45,000 g/mol and a ratio of Mz/Mw ranging from 2.3 to 3.4.