Multimodal polyethylene composition

Abstract

Provided herein are multimodal polyethylene compositions and geomembranes comprising the multimodal polyethylene compositions. The multimodal polyethylene composition comprises a first polyethylene component and a second polyethylene component, wherein the composition has a density of from 0.933 g / cm3 to 0.945 g / cm3; a high flow melt index (I21) from 7.5 g / 10 min to 18.0 g / 10 min; a molecular weight distribution (Mw / Mn) of less than 15.0 as measured by absolute GPC; and a strain hardening modulus of at least 50 MPa. The composition according to embodiments disclosed herein may form a geomembrane, and may exhibit desirable processability and slow crack growth performance, etc.

Description

Technical Field

[0001] The embodiments disclosed herein generally relate to multimodal polyethylene compositions and geomembranes comprising the multimodal polyethylene compositions. Background Technology

[0002] Polyethylene compositions can be formed into useful articles such as films, liners, and geomembranes. Polymer sheets, such as geomembranes, can be used as part of containment structures to provide a barrier against material migration into the environment. When extruding polyethylene compositions to form articles, it is generally desirable for the polyethylene composition to have a low molecular weight and low viscosity, especially under the shear conditions of articles such as geomembranes, so that the polyethylene composition can be more easily processed. However, lower molecular weight and viscosity may compromise properties against slow crack growth, such as environmental stress cracking resistance (ESCR) and notched constant tensile load (NCTL). These properties are particularly important in polyethylene compositions used to form articles such as geomembranes because long service life and leak-proof performance are required to address potential environmental protection issues. In addition to processability and slow crack growth properties, polyethylene compositions forming articles such as geomembranes must balance many other properties, including, for example, melt strength, tensile elongation, puncture resistance, low-temperature flexibility, strong corrosion resistance, and good weldability.

[0003] Attempts to achieve the desired balance of properties in polyethylene compositions include introducing narrow molecular weight distribution catalysts into two-reactor systems to produce multimodal polyethylene compositions. For multimodal compositions in two-reactor systems, stress cracking resistance can be increased by increasing the molecular weight or the content of comonomers in higher molecular weight fractions, which in turn reduces density. However, altering the properties of higher molecular weight fractions can lead to undesirable behaviors, such as increased viscosity. Furthermore, producing multimodal compositions in two- or multi-reactor systems can be costly and unsustainable due to the need for multiple reactors and multiple feeds. Therefore, there remains a need for polyethylene compositions that can be produced in a single reactor and exhibit the desired balance of properties, such as excellent resistance to slow crack growth, good processability, and maintained tensile elongation. Summary of the Invention

[0004] Embodiments of this disclosure satisfy one or more of the aforementioned requirements by providing a polyethylene composition that can be produced in a single reactor and achieves the desired processability and resistance to slow crack growth for applications such as geomembranes.

[0005] This document discloses a multimodal polyethylene composition. In a first aspect, the multimodal polyethylene composition comprises 20% to 45% by weight of a first polyethylene component and a second polyethylene component based on the total weight of the multimodal polyethylene composition, wherein the molecular weight of the first polyethylene component is greater than that of the second polyethylene component, and wherein the multimodal polyethylene composition has the following: 0.933 g / cm³. 3 Up to 0.945 g / cm 3 Density; high flowability solubility index (I) from 7.5 g / 10 min to 18.0 g / 10 min. 21 ); a molecular weight distribution (Mw / Mn) of less than 15.0 as measured by absolute GPC; and a strain hardening modulus of at least 50 MPa.

[0006] This document discloses a geomembrane. In a second aspect, the geomembrane comprises a multimodal composition according to the first aspect.

[0007] These and other implementation schemes are described in more detail in the specific embodiments. Attached Figure Description

[0008] Figure 1 GPC chromatograms of embodiments disclosed herein are depicted. Detailed Implementation

[0009] The disclosed multimodal polyethylene compositions are described in more detail below. These compositions are suitable for forming geomembranes and have a wide range of applications, including, for example, liners, hoses, etc.

[0010] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers of the same or different types. Therefore, the general term polymer encompasses the term homopolymer (used to refer to a polymer prepared from only one type of monomer) and the term copolymer or interpolymer. Trace amounts of impurities (e.g., catalyst residues) may be incorporated into and / or within a polymer. A polymer can be a single polymer, a polymer blend, or a mixture of polymers comprising a mixture of polymers formed in situ during polymerization.

[0011] As used herein, the term "copolymer" refers to a polymer formed by the polymerization of at least two monomers with different structures. The term "copolymer" includes terpolymers.

[0012] As used herein, the terms "polyethylene" or "ethylene-based polymer" should mean a polymer comprising a majority (>50 mol%) unit derived from ethylene monomers. This includes polyethylene homopolymers and copolymers (meaning units derived from two or more comonomers). The terms "ethylene-based polymer" and "polyethylene" are used interchangeably. Generally, polyethylene can be produced in gas-phase fluidized bed reactors, liquid-phase slurry reactors, or liquid-phase solution reactors using heterogeneous catalyst systems (such as Ziegler-Natta catalysts) and homogeneous catalyst systems containing Group 4 transition metals and ligand structures (such as metallocenes, non-metallocene metal centers, heteroaryl groups, isovalent aryloxy ethers, phosphine imides, etc.). Combinations of heterogeneous and / or homogeneous catalysts can also be used in single-reactor or dual-reactor configurations.

[0013] As used herein, the term "composition" refers to a mixture of materials comprising the composition, as well as reaction products and decomposition products formed from the materials of the composition. The composition disclosed herein is a composition because it has a first polyethylene component and a second polyethylene component.

[0014] The term "multimodal" refers to a composition having at least two (2) polyethylene components or sub-components with different molecular weights and / or different comonomer contents. The term "bimodal" refers to a composition having two (2) polyethylene components or sub-components with different molecular weights and / or different comonomer contents. All GPC measurements (e.g., Mw, Mn, Mz) described herein are absolute GPC measurements provided according to the test methods described below.

[0015] The terms “comprising,” “including,” “having,” and their derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether or not such components, steps, or procedures are specifically disclosed. For the avoidance of any doubt, unless otherwise stated, all compositions claimed using the term “comprising” may include any additional additives, auxiliaries, or compounds, whether in polymeric or other forms. In contrast, the term “consistently comprising” excludes any other components, steps, or procedures from any subsequently listed scope, except those that are not essential for operability. The term “consisting of” excludes any components, steps, or procedures not specifically described or listed.

[0016] This document discloses multimodal polyethylene compositions. The multimodal polyethylene compositions according to embodiments disclosed herein comprise a first polyethylene component and a second polyethylene component. The molecular weight of the first polyethylene component is greater than that of the second polyethylene component. In some embodiments, the multimodal composition is a bimodal polyethylene composition (i.e., it has only two polyethylene components). In other embodiments, the multimodal composition has two, three, or more polyethylene components with different molecular weights and / or different comonomer contents.

[0017] In some embodiments, the first polyethylene component is a copolymer of ethylene and one or more α-olefin comonomers. In some embodiments, the second polyethylene component is also a copolymer of ethylene and one or more α-olefin comonomers. The α-olefin comonomers may have 3 to 10 carbon atoms or 3 to 8 carbon atoms. Exemplary α-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. In some embodiments, the α-olefin comonomers may be selected from the group consisting of 1-butene, 1-hexene, and 1-octene, or from the group consisting of 1-butene and 1-hexene, or from the group consisting of 1-hexene or 1-octene. In some embodiments, the first polyethylene component is a non-metallocene-catalyzed ethylene copolymer. In some embodiments, the second polyethylene component is a metallocene-catalyzed ethylene copolymer. As described below, the first and second polyethylene components can be polymerized in a single reactor in the presence of a bimodal catalyst system. In some embodiments, the first polyethylene component is a copolymer comprising ethylene and 1-hexene. In some embodiments, the second polyethylene component is a copolymer comprising ethylene and 1-hexene. In some embodiments, the first and second polyethylene components comprise 1-hexene or do not contain comonomers other than 1-hexene, or do not contain comonomers other than 1-hexene or 1-octene.

[0018] The multimodal polyethylene composition comprises 20% to 45% by weight of a first polyethylene component based on the total weight of the multimodal polyethylene composition. This document discloses and includes all individual values ​​and sub-ranges of 20% to 45% by weight. For example, the multimodal polyethylene composition may comprise a first polyethylene component from the lower limit of 20%, 25%, 30%, 35%, or 40% by weight to the upper limit of 45%, 40%, 35%, 30%, or 25% by weight based on the total weight of the multimodal polyethylene composition. In some embodiments, the multimodal polyethylene composition comprises 55% to 80% by weight of a second polyethylene component based on the total weight of the multimodal polyethylene composition. For example, in some embodiments, the multimodal polyethylene composition may comprise 55%, 60%, 65%, 70%, or 75% to 80%, 75%, 70%, 65%, or 60% by weight of a second polyethylene component based on the total weight of the multimodal polyethylene composition.

[0019] The multimodal polyethylene composition has a content of 0.933 g / cm³. 3 Up to 0.945 g / cm 3 The density. In some embodiments, the multimodal polyethylene composition may have a density from 0.934 g / cm³. 3 0.935g / cm 3 0.936 g / cm 3 0.937g / cm 3 0.938g / cm 3 0.939 g / cm 3 0.940 g / cm 3 0.941 g / cm 3 0.942 g / cm 3 0.943 g / cm 3 Or 0.944 g / cm 3 The lower limit is 0.935 g / cm³. 3 0.936 g / cm 3 0.937g / cm 3 0.938g / cm 3 0.939 g / cm 3 0.940 g / cm 3 0.941 g / cm 3 0.942 g / cm 3 0.943 g / cm 3 0.944 g / cm 3 Or 0.945g / cm 3 The upper limit of density.

[0020] The multimodal polyethylene composition has a high melt flow index (I0) of 7.5 g / 10 min to 18.0 g / 10 min. 21 In some embodiments, the multimodal polyethylene composition may have a viscosity ranging from 7.5 g / 10 min, 8.0 g / 10 min, 8.5 g / 10 min, 9.0 g / 10 min, 9.5 g / 10 min, 10.0 g / 10 min, 11.0 g / 10 min, 12.0 g / 10 min, 13.0 g / 10 min, 14.0 g / 10 min, 15.0 g / 10 min, 16.0 g / 10 min, or 16.5 g / 10 min. The lower limit of the high flow melt index (I) is 8.0 g / 10 min, and the upper limit is 8.5 g / 10 min, 9.0 g / 10 min, 9.5 g / 10 min, 10.0 g / 10 min, 11.0 g / 10 min, 12.0 g / 10 min, 13.0 g / 10 min, 14.0 g / 10 min, 15.0 g / 10 min, 16.0 g / 10 min, 16.5 g / 10 min, or 18.0 g / 10 min. 21 ).

[0021] The multimodal polyethylene composition has a molecular weight distribution (Mw / Mn) of less than 15.0 as measured by absolute GPC. In some embodiments, the multimodal polyethylene composition has a molecular weight distribution of less than 14.0, or less than 13.0, or less than 10.0. In some embodiments, the multimodal polyethylene composition has a molecular weight distribution of greater than 4.0, greater than 5.0, greater than 7.0, or greater than 10.0.

[0022] The multimodal polyethylene composition has a strain hardening modulus of at least 50 MPa. In some embodiments, the multimodal polyethylene composition may have a strain hardening modulus of at least 51 MPa, 52 MPa, 53 MPa, 54 MPa, 55 MPa, 56 MPa, or 57 MPa. In some embodiments, the multimodal polyethylene composition may have a strain hardening modulus of no more than 75 MPa, 74 MPa, 73 MPa, 72 MPa, 71 MPa, or 70 MPa. Without being bound by theory, the combination of strain hardening modulus with other characteristics, including the weight percentage of the first polyethylene component, a high melt flow index, and molecular weight distribution, produces compositions with desired processability and resistance to slow crack growth suitable for geomembrane applications.

[0023] In some embodiments, the multimodal polyethylene composition has a PENT value of at least 5,000 hours as measured according to ASTM F1472. In some embodiments, the multimodal polyethylene composition may have a PENT value of at least 5,500 hours, at least 6,000 hours, or at least 6,300 hours as measured according to ASTM F1472.

[0024] In some embodiments, the multimodal polyethylene composition may have an I content greater than 15, or greater than 17, or greater than 19, or greater than 21, or greater than 23. 21 / I5. In some embodiments, the multimodal polyethylene composition may have an I value of less than 40, or less than 35, or less than 30. 21 / I5.

[0025] In some embodiments, the multimodal polyethylene composition may have an I value greater than 50, or greater than 55, or greater than 60, or greater than 70, or greater than 80, or greater than 100, or greater than 110, or greater than 120, or greater than 130, or greater than 140, or greater than 150. 21 / I2. In some embodiments, the multimodal polyethylene composition may have an I value not exceeding 200 or not exceeding 180. 21 / I2.

[0026] In some embodiments, the multimodal polyethylene composition may have an Mz greater than 1,600,000 g / mol, 1,700,000 g / mol, or 1,800,000 g / mol. In some embodiments, the multimodal polyethylene composition may have an Mz not exceeding 3,000,000 g / mol, 2,500,000 g / mol, or 2,000,000 g / mol.

[0027] In some embodiments, the multimodal polyethylene composition may have a melt strength greater than 12.0 cN, or greater than 12.5 cN, or greater than 13.0 cN. In some embodiments, the multimodal polyethylene composition may have a melt strength not exceeding 25.0 cN or not exceeding 20.0 cN.

[0028] In some embodiments, the multimodal polyethylene composition may have a molecular weight distribution from absolute GPC, wherein the absolute GPC molecular weight distribution has a first peak and a shoulder peak in the Log (molecular weight) range of 3.5 to 7.0, wherein the first peak corresponds to the second polyethylene component and the shoulder peak corresponds to the first polyethylene component. A “shoulder peak” is defined and identified herein as a portion of the GPC chromatogram following the first peak, whereby the slope increases to a point less than zero (i.e., the curve does not form a second peak, thus the slope reaches zero), and then decreases (i.e., so as to visually form a “shoulder peak” on the GPC chromatogram). Figure 1GPC chromatograms showing a first peak and a shoulder peak are disclosed. Those skilled in the art will understand that GPC chromatograms relate to the molecular structure of multimodal polyethylene compositions and are partly a result of the specific catalyst system used to form the composition. Without being bound by theory, it has been found that, according to the embodiments disclosed herein, specific types of catalysts are suitable for producing multimodal polyethylene compositions in a single reactor, and consequently, provide specific GPC chromatograms that prior art compositions with similar characteristics or different catalyst systems cannot produce in a single reactor system, provide specific GPC chromatograms, and / or provide the desired properties disclosed herein. Furthermore, without being bound by theory, multimodal polyethylene compositions have a first polyethylene component, as indicated by the shoulder peak in the GPC chromatogram, which contributes to the composition's balance in terms of desired resistance to slow crack growth, processability, and maintenance or improvement of mechanical and tensile properties. In some embodiments, the absolute GPC chromatogram has a first peak in the Log (molecular weight) range of 3.5 to 5.8 or 3.5 to 5.5.

[0029] In some embodiments, the multimodal polyethylene composition has a complex viscosity of less than 2,700 Pa·s, less than 2,500 Pa·s, or less than 2,300 Pa·s, or less than 2,100 Pa·s at 100 rad / s. The complex viscosity at 100 rad / s can be an indicator of the processability of the multimodal polyethylene composition for the applications described herein.

[0030] The first and second polyethylene components may have different Mw, Mn, Mz, and Mw / Mn values ​​from each other. In some embodiments, the first polyethylene component (i.e., the component having a higher molecular weight than the second polyethylene component or having an HMW) may have at least one of the following: a weight-average molecular weight (Mw) greater than 800,000 g / mol or greater than 900,000 g / mol and / or less than 100,000 g / mol; a number-average molecular weight (Mn) greater than 200,000 g / mol and / or less than 400,000 g / mol; an Mz value greater than 2,000,000 g / mol or greater than 2,200,000 g / mol and / or less than 3,000,000 g / mol or less than 2,800,000 g / mol; and a molecular weight distribution (Mw / Mn) in the range of 2.0 to 6.0, or 3.0 to 5.0, or 3.5 to 4.5. In some embodiments, the second polyethylene component (i.e., a component having a lower molecular weight than the first polyethylene component or having an LMW) may have at least one of the following: a weight-average molecular weight (Mw) of less than 100,000 g / mol, or less than 75,000 g / mol, and / or greater than 30,000 g / mol, or greater than 40,000 g / mol; a number-average molecular weight (Mn) of less than 50,000 g / mol, or less than 40,000 g / mol, or less than 30,000 g / mol, and / or greater than 10,000 g / mol or greater than 20,000 g / mol; an Mz value of less than 200,000 g / mol, or less than 150,000 g / mol, and / or greater than 50,000 g / mol or greater than 75,000 g / mol; and a molecular weight distribution (Mw / Mn) in the range of 1.0 to 3.0 or 1.5 to 3.0. The Mw, Mn, Mz, and Mw / Mn values ​​of each component are measured according to the test methods described below. In some embodiments, the first polyethylene component has a weight-average molecular weight distribution that is at least 600,000 g / mol, at least 700,000 g / mol, or at least 800,000 g / mol greater than that of the second polyethylene component. In some embodiments, the first polyethylene component has a Mw / Mn that is at least 1.0 greater than that of the second polyethylene component. In some embodiments, the first polyethylene component has a number-average molecular weight (Mn) that is at least 150,000 g / mol greater than that of the second polyethylene component.

[0031] In some embodiments, when the multi-peak polyethylene composition is used to form a geomembrane according to the geomembrane manufacturing method described below, the notched constant tensile load failure time of the geomembrane at 30% yield stress can be greater than 1,500 hours, or greater than 2,000 hours, or greater than 3,000 hours, as measured by ASTM D5397.

[0032] In some embodiments, in addition to the properties described above, when the multimodal polyethylene composition is used to form a geomembrane as described in the following geomembrane manufacturing method, the geomembrane may exhibit at least one of the following properties: a yield strength of at least 2,300 psi (or at least 2,400 psi); a tensile strength of at least 4,000 psi (or at least 4,500 psi or at least 49,000 psi); a yield elongation of at least 13% (or at least 14% or at least 14.5%); a tensile elongation of at least 700% (or at least 720%); and a puncture strength of at least 2,000 psi (or at least 2,100 psi).

[0033] The multi-peak polyethylene composition of this invention is suitable for manufacturing geomembranes. Geomembranes are low-permeability barrier polymer sheets used in any geotechnical application to regulate the migration of liquids or gases in industrial systems. Geomembranes can be used to receive or transport fluids, gases, or solids, and to protect water or the environment from impurities or contamination. Geomembranes can be used as hydraulic and gas barriers in purification processes. Geomembranes must generally meet certain regulatory or industrial thresholds regarding performance, such as the GM-13 standard of the Geosynthetics Research Institute.

[0034] In some embodiments, the multimodal polyethylene composition is formed into a geomembrane that meets or exceeds the GM-13 standard of the Geosynthetics Research Institute. The characteristics of the multimodal high-density polyethylene composition, including its density, melt flow properties, elongation properties, and modulus properties, contribute to its particular suitability for geomembranes. The geomembrane can be extruded by methods known to those skilled in the art and can be formed by methods known to those skilled in the art. For example, a geomembrane can be formed by sealing a polymer sheet formed from a polyethylene composition along one or more overlapping seams via heat or other means to create a long, wide sheet with fused overlaps. The geomembrane can also be formed from polymer sheets welded together.

[0035] The geomembrane according to the embodiments disclosed herein may be a single-layer geomembrane and may contain suitable additives for extrusion or geomembrane applications. Such additives include colorants and materials suitable for protecting the composition from adverse environmental effects, such as oxidation during extrusion or degradation under use conditions. Suitable additives include processing stabilizers, antioxidants, and pigments. In some embodiments, the geomembrane may comprise multiple layers, wherein at least one layer contains the composition according to the invention. Additional polyolefins may be co-extruded with other polymers such as polyamides, ethylene-vinyl alcohol copolymers, and polyesters.

[0036] A method for manufacturing a geomembrane includes forming a multimodal high-density polyethylene composition according to embodiments disclosed herein and extruding the multimodal polyethylene composition to form a geomembrane, wherein the multimodal polyethylene is formed by polymerizing ethylene monomers and α-olefin comonomers in a single-gas-phase polymerization (GPP) in the presence of a bimodal catalyst system; wherein the bimodal catalyst system comprises substantially a metallocene catalyst, a single-point non-metallocene catalyst as a bis((alkyl-substituted phenylamido)ethyl)amine catalyst, an optional host material, and an optional activator; wherein the host material, when present, is selected from at least one of inert hydrocarbon liquids and solid supports; wherein the metallocene catalyst is used to react the activator with formula (R 1-2 Cp)((alkyl) 1-3 The activation reaction product of the metal-ligand complex of indenyl(MX2), wherein R is hydrogen, methyl, or ethyl; each alkyl group is independently (C1-C4)alkyl; M is titanium, zirconium, or hafnium; and each X is independently a halide, (C1 to C4)alkyl group. 20 )alkyl, (C7 to C 20 Aryl, (C1 to C6)alkyl-substituted (C6 to C6) 12 )aryl or (C1 to C6)alkyl-substituted benzyl; and wherein the bis((alkyl-substituted phenylamido)ethyl)amine catalyst is a catalyst that reacts the activator with bis((alkyl-substituted phenylamido)ethyl)amine ZrR 1 2. Activation reaction products of contact, wherein each R 1 Independently selected from F, Cl, Br, I, benzyl, -CH2Si(CH3)3, (C1-C5)alkyl, and (C2-C5)alkenyl. In some embodiments, the metal-ligand complex of formula (I) is a compound in which M is zirconium (Zr); R is H, or methyl, or ethyl; and each X is Cl, methyl, or benzyl; and bis((alkyl-substituted phenylamido)ethyl)amine MR12 is the bis(2-(pentamethylphenylamido)ethyl)amine zirconium complex of formula (II): (II), where M is Zr, and each R 1 Independently, they are Cl, Br, (C1 to C) 20 )alkyl, (C1 to C6)alkyl-substituted (C6-C 12)Aryl, benzyl, or (C1 to C6)alkyl-substituted benzyl. In some aspects, the compound of formula (II) is dibenzylbis(2-(pentamethylphenylamido)ethyl)-amine zirconium. In some embodiments, each X and R1 is independently C1, methyl, 2,2-dimethylpropyl, -CH2Si(CH3)3, or benzyl. In some embodiments, the metal-ligand complex of formula (I) is (cyclopentadienyl)(1,5-dimethylindenyl)dimethylzirconium. In some embodiments, the metal-ligand complex of formula (I) is (methylcyclopentadienyl)(1,3-dimethyl-4,5,6,7-tetrahydroindenyl)dimethylzirconium.

[0037] Process for preparing multimodal compositions

[0038] In some embodiments, the multimodal polyethylene composition is prepared by polymerizing ethylene and α-olefins in a single-gas phase polymerization (GPP) in the presence of a bimodal catalyst system; wherein the bimodal catalyst system consists essentially of a metallocene catalyst, a single-site non-metallocene catalyst as a bis((alkyl-substituted phenylamido)ethyl)amine catalyst, an optional host material, and an optional activator; wherein the host material, when present, is selected from at least one of inert hydrocarbon liquids and solid supports; wherein the metallocene catalyst is used to react the activator with formula (R 1-2 Cp)((alkyl) 1-3 The activation reaction product of the metal-ligand complex of indenyl(MX2), wherein R is hydrogen, methyl, or ethyl; each alkyl group is independently (C1-C4)alkyl; M is titanium, zirconium, or hafnium; and each X is independently a halide, (C1 to C4)alkyl group. 20 )alkyl, (C7 to C 20 Aryl, (C1 to C6)alkyl-substituted (C6 to C6) 12 )aryl or (C1 to C6)alkyl-substituted benzyl; and said bis((alkyl-substituted phenylamido)ethyl)amine catalyst is a catalyst that reacts the activator with bis((alkyl-substituted phenylamido)ethyl)amine ZrR 1 2. Activation reaction products of contact, wherein each R 1 It is independently selected from F, Cl, Br, I, benzyl, -CH2Si(CH3)3, (C1-C5)alkyl and (C2-C5)alkenyl.

[0039] In some embodiments, the multimodal polyethylene composition may be an ethylene monomer and at least one C3-C 12The polymerization product of α-olefin comonomers. For example, embodiments of the composition may be polymerization products of ethylene monomers and 1-butene, 1-hexene, or both. Alternatively, embodiments of the polyethylene composition may be polymerization products of ethylene monomers and 1-butene, 1-octene, or both. Embodiments of the polyethylene composition may also be polymerization products of ethylene monomers and 1-hexene, 1-octene, or both. In some embodiments, C3-C 12 The α-olefin comonomer does not have to be propylene.

[0040] In some embodiments, a multimodal polyethylene composition can be produced in a single reactor using a catalyst system. As used herein, a “catalyst system” may comprise a main catalyst, a trim catalyst, and optionally at least one activator. The catalyst system may also include other components, such as a support, and is not limited to a main catalyst, a trim catalyst, and optionally at least one activator. Embodiments of the catalyst system may comprise a main catalyst and a metallocene trim catalyst. Embodiments of the catalyst system may also comprise one or more additives commonly used in the field of olefin polymerization. For example, embodiments of the catalyst system may comprise one or more continuous additives, flow aids, and antistatic agents. In embodiments, the reactor may be a gas-phase reactor, but a slurry-phase reactor may also be used.

[0041] An embodiment of the catalyst system may include at least one catalyst (sometimes referred to herein as the “HMW catalyst”) for producing a first polyethylene component (higher molecular weight component) by polymerization, and at least one catalyst compound (sometimes referred to herein as the “LMW catalyst”) for producing a second polyethylene component (lower molecular weight component) by polymerization.

[0042] An embodiment of the catalyst system may be referred to as a "bimodal catalyst system." Such catalyst systems produce polyethylene compositions with separate, identifiable high and low molecular weight distributions. The term "bimodal catalyst system" can include any formulation, mixture, or system comprising at least two different catalyst compounds, each having the same or different metal groups but typically different ligand or catalyst structures, including "dual catalysts." Alternatively, each different catalyst compound in the bimodal catalyst system is present on a single support particle; in this case, the dual catalyst is considered a supported catalyst. However, the term "bimodal catalyst system" also broadly includes systems or mixtures in which one catalyst is present on one set of support particles and the other on another set of support particles. In such embodiments, two supported catalysts are introduced simultaneously or sequentially into a single reactor, and polymerization takes place in the presence of both supported catalyst sets. Alternatively, a bimodal catalyst system may comprise a mixture of unsupported catalysts in slurry form.

[0043] The single-phase gas polymerization reactor can be a fluidized bed gas-phase polymerization (FB-GPP) reactor, and effective polymerization conditions can include conditions (a) to (e): (a) an FB-GPP reactor having a fluidized resin bed with a bed temperature of 80°C to 110°C, alternatively 85°C to 108°C, alternatively 90°C to 108°C, alternatively 94°C to 107°C, or alternatively 95°C to 106°C; (b) the FB-GPP reactor receiving feeds of the following, each in independently controlled amounts: ethylene, characterized in that 1-olefin and ethylene (C x A 1-olefin with a molar ratio of (C2) to ethylene, a bimodal catalyst system, optionally including a solution of a metallocene catalyst in an unsupported form made of a metal-ligand complex of formula (I) in an inert hydrocarbon liquid, and a trimming catalyst, optionally characterized by a hydrogen (H2) molar ratio of hydrogen to ethylene (H2 / C2) or a ratio of H2 to C2 molar percentage (H2ppm / C2 mol%) in parts per million by weight, and optionally containing (C5-C2) molar ratios of 1-olefins, a bimodal catalyst system, optionally including a solution of a metallocene catalyst in an unsupported form made of a metal-ligand complex of formula (I) in an inert hydrocarbon liquid, and optionally including (C5-C2) molar ratios of 1-olefins (H2 / ... 10An induced condenser (ICA) of an alkane such as isopentane; wherein the (C6 / C2) molar ratio is 0.0001 to 0.1, alternatively 0.0002 to 0.03, alternatively 0.003 to 0.02; wherein when H2 is fed, the H2 / C2 molar ratio is 0.0001 to 0.1, alternatively 0.0002 to 0.0020, alternatively 0.0003 to 0.001, or the H2 ppm / C2 mol% ratio is 1 to 1,000, alternatively 2.0 to 20.0, alternatively 3.0 to 10.0; and wherein when ICA is fed, the concentration of ICA in the reactor is 1 mol% to 25 mol%, alternatively 4 mol% to 20 mol%, based on the total moles of ethylene, 1-olefin, and ICA in the reactor. The average residence time of the copolymer in the reactor can be 1 hour to 6 hours, alternatively 2 hours to 4 hours. Continuous additives can be used in the FB-GPP reactor during polymerization.

[0044] The bimodal catalyst system is characterized by an inverse response to bed temperature, such that as the bed temperature increases, the viscoelastic value of the resulting composition decreases, and as the bed temperature decreases, the viscoelastic value of the resulting bimodal poly(ethylene-co-1-olefin) copolymer increases. The bimodal catalyst system is also characterized by an inverse response to the H2 / C2 ratio, such that as the H2 / C2 ratio increases, the viscoelastic value of the resulting bimodal poly(ethylene-co-1-olefin) copolymer decreases, and as the H2 / C2 ratio decreases, the viscoelastic value of the resulting composition increases.

[0045] The composition comprises a higher molecular weight component (HMW component) and a lower molecular weight component (LMW component). In an illustrative pilot-scale process for preparing bimodal polyethylene polymers, a fluidized bed, gas-phase polymerization reactor (“FB-GPP reactor”) is used, having a reaction zone with an inner diameter of 304.8 mm (12 inches) and a straight-side height of 2.4384 m (8 ft) and containing particles of the composition. A circulating gas line is configured for the FB-GPP reactor to facilitate the flow of circulating gas. A gas feed inlet and a polymer product outlet are fitted to the FB-GPP reactor. A gaseous feed stream of ethylene and hydrogen, along with a 1-olefin comonomer (e.g., 1-hexene), is introduced into the circulating gas line below the FB-GPP reactor bed. The concentrations of (C5-C6) in the gas / vapor effluent are measured by sampling the gas / vapor effluent from the circulating gas line. 20 Total alkane concentration. Gas / vapor effluent (except for a small portion removed for sampling) is returned to the FB-GPP reactor via a recirculation gas line.

[0046] Polymerization operating conditions are any variable or combination of variables that may affect the polymerization reaction in the GPP reactor or the composition or properties of the bimodal polyethylene copolymer produced therefrom. Variables may include reactor design and size; catalyst composition and amount; reactant composition and amount; molar ratio of two different reactants; presence or absence of feed gases (such as H2 and / or O2), molar ratio of feed gases to reactants, absence or concentration of interfering materials (e.g., H2O), average polymer residence time in the reactor, partial pressure of components, monomer feed rate, reactor bed temperature (e.g., fluidized bed temperature), nature or sequence of process steps, and transition time between steps. Variables other than the one / those variables described or changed by the method or application may remain constant.

[0047] When operating this method, control the ethylene (“C2”) and 1-olefin (“C…”) x For example, 1-hexene or "C6" or "C x "where x is 6") and the individual flow rate of any hydrogen gas ("H2") to maintain a fixed comonomer to ethylene monomer gas molar ratio (C) equal to the described value. x / C2, e.g., C6 / C2), a constant hydrogen to ethylene gas molar ratio equal to the described value (“H2 / C2”) and a constant ethylene (“C2”) partial pressure equal to the described value (e.g., 1,000 kPa). Alternatively, ethylene (“C2”), 1-olefins (“C…”) x For example, 1-hexene or "C6" or "C x "where x is 6") and the individual flow rate of any hydrogen gas ("H2") to maintain a fixed comonomer to ethylene monomer gas flow ratio (C) equal to the described value. xThe H2 / C2 flow ratio (e.g., kg C6 / kg C2FR), a constant hydrogen to ethylene gas flow ratio equal to the described value (“H2 / C2 flow ratio”, e.g., kg H2 / kg C2FR), and a constant ethylene (“C2”) partial pressure equal to the described value (e.g., 1,000 kPa) are used. Gas concentrations are measured by online gas chromatography to understand and maintain the composition in the recirculating gas stream. The reaction bed of growing polymer particles is maintained in a fluidized state by continuously flowing the supplementary feed and recirculating gas through the reaction zone. Apparent gas velocities are used from 0.43 m / sec to 0.76 m / sec (1.4 ft / sec to 2.5 ft / sec). The FB-GPP reactor is operated at a total pressure of approximately 2000 kPa to approximately 2413 kPa (approximately 290 psig to approximately 350 psig) and at the described reactor bed temperature RBT. The fluidized bed is maintained at a constant height by withdrawing a portion of the bed at a rate equal to the production rate of the bimodal polyethylene polymer in particulate form, which can be from 4,500 kg / hr to 90,000 kg / hr, or alternatively from 9,000 kg / hr to 80,000 kg / hr. The resulting bimodal poly(ethylene-co-1-olefin) copolymer is semi-continuously removed via a series of valves into one or more fixed-volume chambers, the resin is conveyed to a product purge chamber, and the removed composition is progressively contacted with a suitable purge medium to remove dissolved hydrocarbons, and then the resin is contacted with a humidified nitrogen (N2) gas stream to deactivate any trace amounts of residual catalyst.

[0048] The bimodal catalyst system can be fed into the polymerization reactor in either a "dry mode" or a "wet mode," replacing the traditional dry mode. The dry mode uses dry powder or granules. The wet mode uses an inert liquid (such as mineral oil or C5-C...). 20A suspension in alkanes. In some aspects, the composition is prepared by in-situ contacting the metal-ligand complex of formula (I) and the unit-site non-metallocene catalyst with at least one activator in a GPP reactor in the presence of olefin monomers and comonomers (e.g., ethylene and 1-olefins) and growing polymer chains. These embodiments may be referred to herein as in-situ contact embodiments. In other aspects, the metal-ligand complex of formula (I), the unit-site non-metallocene catalyst, and at least one activator are premixed together for a period of time to prepare an activated bimodal catalyst system, and the activated bimodal catalyst system is then injected into a GPP reactor, where it contacts the olefin monomers and growing polymer chains. These latter embodiments involve pre-contaminating the metal-ligand complex of formula (I), the unit-site non-metallocene catalyst, and at least one activator together in the absence of olefin monomers (e.g., the absence of ethylene and α-olefins) and growing polymer chains, i.e., in an inert environment, and are referred to herein as pre-contamination embodiments. The premixing time period of the pre-contamination embodiments may be from 1 second to 10 minutes, alternatively from 30 seconds to 45 minutes, or alternatively from 5 minutes to 30 minutes. ICA can be fed alone into the FB-GPP reactor or as part of a mixture that also contains a bimodal catalyst system. ICA can be (C 11 -C 20 Alkanes, alternatively (C5-C) 10 Alkanes, alternative to C5 alkanes, such as pentane or 2-methylbutane; hexane; heptane; octane; nonane; decane; or any combination of two or more thereof. An aspect of the polymerization method using ICA may be referred to as Induced Condensation Mode Operation (ICMO). ICMO is described in US 4,453,399; US 4,588,790; US 4,994,534; US 5,352,749; US 5,462,999; and US 6,489,408. The peak area percentage is calibrated to molar percentage (mol%) using gas chromatography by standardizing a gas mixture of suitable gas phase components of known concentration, to indirectly measure the ICA concentration in the reactor as the total concentration of ICA discharged.

[0049] This method uses a gas-phase polymerization (GPP) reactor, such as a stirred-bed gas-phase polymerization reactor (SB-GPP reactor) or a fluidized-bed gas-phase polymerization reactor (FB-GPP reactor), to prepare the compositions disclosed herein. Such gas-phase polymerization reactors and methods are generally well known in the art. For example, FB-GPP reactors / methods are described in the following documents: US3,709,853; US 4,003,712; US 4,011,382; US 4,302,566; US 4,543,399; US 4,882,400; US5,352,749; US 5,541,270; EP-A-0-802-202; and Belgian Patent 839,380. These SB-GPP and FB-GPP polymerization reactors and methods mechanically agitate or fluidize the polymerization medium inside the reactor by the continuous flow of gaseous monomers and diluents. Other anticipated useful reactors / methods include tandem or multi-stage polymerization methods, such as those described in the following literature: US 5,627,242; US 5,665,818; US 5,677,375; EP-A-0 794 200; EP-B1-0 649 992; EP-A-0-802-202; and EP-B-634421.

[0050] Polymerization conditions may also include one or more additives, such as chain transfer agents or accelerators. Chain transfer agents are well known and may be alkyl metals, such as diethylzinc. Accelerators are known as those in US 4,988,783 and may include chloroform, CFC13, trichloroethane, and difluorotetrachloroethane. A scavenger may be used to react with moisture before reactor start-up and during reactor transition, a scavenger may be used to react with excess activator. The scavenger may be trialkylaluminum. Gas-phase polymerization can be operated without (unintentionally added) scavengers. Polymerization conditions for gas-phase polymerization reactors / methods may also include an amount (e.g., 0.5 ppm to 200 ppm based on all feed into the reactor) of electrostatic control agents and / or continuous additives, such as aluminum stearate or polyethyleneimine. Electrostatic control agents may be added to the FB-GPP reactor to suppress the formation or accumulation of static charge therein. Electrostatic control agents may be pre-added to the FB-GPP reactor at a preset concentration before starting the catalyst feed.

[0051] This method utilizes a fluidized bed gas-phase polymerization reactor (FB-GPP), comprising a reactor vessel containing a fluidized bed of bimodal polyethylene polymer powder, a distribution plate positioned above a bottom head defining a bottom gas inlet, and an expansion section or cyclone system at the top of the reactor vessel to reduce the amount of resin powder that may escape from the fluidized bed. The expansion section defines a gas outlet. The FB-GPP also includes a compressor blower of sufficient power to continuously circulate or loop the gas from the gas outlet in the expansion section at the top of the reactor vessel downwards to and into the bottom gas inlet of the FB-GPP, flowing through the distribution plate and the fluidized bed. The FB-GPP also includes a cooling system to remove the heat of polymerization and maintain the fluidized bed at a target temperature. The gas composition of feedstocks such as ethylene, 1-olefins (e.g., 1-hexene), and hydrogen in the pilot reactor is monitored by online gas chromatography in the circulation loop to maintain specific concentrations that define polymer properties and allow for control of polymer characteristics. The bimodal catalyst system can be fed into the FB-GPP from the high-pressure unit in slurry or dry powder form, with the slurry fed via a pump and the dry powder fed via a metering pan. The bimodal catalyst system typically enters the fluidized bed at less than one-third of its height. The FB-GPP also includes a pathway for monitoring the fluidized bed weight and an isolation port (product discharge system) for discharging bimodal polyethylene polymer powder from the reactor vessel in response to the increasing fluidized bed weight as the polymerization reaction proceeds.

[0052] In some implementations, the FB-GPP reactor is a commercial-scale reactor, such as the UNIPOL, which is available from Univation Technologies, LLC, a subsidiary of The Dow Chemical Company, Midland, Michigan, USA. ™ Reactor. In some embodiments, the bimodal catalyst system used in this method is essentially composed of a metallocene catalyst and bis((alkyl-substituted phenylamido)ethyl)amine ZrR 1 2. The catalyst and optionally the host material are composed; wherein the host material (when present) is selected from at least one of inert hydrocarbon liquid and solid support; wherein the metallocene catalyst is an activation reaction product of contacting the activator with the aforementioned metal-ligand complex of formula (I); and wherein the bis((alkyl-substituted phenylamido)ethyl)amine catalyst is a catalyst of contacting the activator with the aforementioned bis((alkyl-substituted phenylamido)ethyl)amine ZrR 12. Activation reaction products of catalyst contact. The phrase "consisting primarily of..." means that the bimodal catalyst system and the method of using it are free from third-point catalysts (e.g., different metallocenes, different amine catalysts, or biphenol catalysts) and non-third-point catalysts (e.g., free from Ziegler-Natta or chromium catalysts). The bimodal catalyst system may also consist primarily of the host material and / or at least one activator species, which are byproducts of the reaction between the metallocene catalyst or the non-metallocene molecular catalyst and the activator.

[0053] Without being bound by theory, it is believed that bis((alkyl-substituted phenylamido)ethyl)amine catalysts (e.g., dibenzylbis(2-(pentamethylphenylamido)ethyl)amine zirconium) are essentially mono-site non-metallocene catalysts, effective for the preparation of the HMW component of bimodal poly(ethylene-co-1-olefin) copolymers, and that metallocene catalysts (made from metal-ligand complexes of formula (I)) are essentially mono-site catalysts, independently effective for the preparation of the LMW component of the composition. The molar ratio of the two catalysts in a bimodal catalyst system can be based on the molar ratio of their respective catalytic metal atom contents (M, e.g., Zr), which can be calculated by weight of their components or can be analytically measured. The molar ratio of the two catalysts can be varied in the polymerization process by using different bimodal catalyst system formulations with different molar ratios or by using the same bimodal catalyst system and a trimmed catalyst. Changing the molar ratio of the two catalysts during the polymerization process can be used to modify specific properties of the bimodal poly(ethylene-co-1-olefin) copolymer within the limitations of its stated characteristics.

[0054] The catalyst in a bimodal catalyst system can be unloaded when in contact with an activator, which can be the same or different for different catalysts. Alternatively, the catalyst can be set onto a solid support material by spray drying before contact with one or more activators. The solid support material can be uncalcined or calcined before contact with the catalyst. The solid support material can be hydrophobic pyrolytic silica (e.g., pyrolytic silica treated with dimethyldichlorosilane). The bimodal (unloaded or loaded) catalyst system can be in powder, free-flowing particulate solid form. Support material. The support material can be an inorganic oxide material. As used herein, the terms "support" and "support material" are the same and refer to porous inorganic or organic materials. In some embodiments, the desired support material can be an inorganic oxide comprising Group 2, Group 3, Group 4, Group 5, Group 13, or Group 14 oxides, alternatively Group 13 or Group 14 atoms. Examples of inorganic oxide-type support materials are silica, alumina, titanium dioxide, zirconium oxide, thorium oxide, and mixtures of any two or more of these inorganic oxides. Examples of such mixtures are silica-chromium, silica-alumina, and silica-titanium dioxide.

[0055] The inorganic oxide support material is porous and has variable surface area, pore volume, and average particle size. In some embodiments, the surface area is 50 square meters per gram (m²). 2 / g) to 1000m 2 / g, and the average particle size is 20 micrometers (μm) to 300 μm. Alternatively, the pore volume is 0.5 to 6.0 cubic centimeters per gram (cm³). 3 / g), and a surface area of ​​200m² 2 / g to 600m 2 / g. Alternatively, the pore volume is 1.1cm³. 3 / g to 1.8cm 3 / g, and the surface area is 245m² 2 / g to 375m 2 / g. Alternatively, the pore volume is 2.4 cm³. 3 / g to 3.7cm 3 / g, and the surface area is 410m² 2 / g to 620m 2 / g. Alternatively, the pore volume is 0.9cm³. 3 / g to 1.4cm 3 / g, and the surface area is 390m² 2 / g to 590m 2 / g. Each of the above properties is measured using conventional techniques known in the art.

[0056] The carrier material may include silica, alternatively amorphous silica (not quartz), or alternatively high surface area amorphous silica (e.g., 500 to 1000 m²). 2 / g). This type of silica is commercially available from several sources, including Davison Chemical Division of WRGrace and Company (e.g., Davison 952 and Davison 955 products) and PQ Corporation (e.g., ES70 product). Silica may be in the form of spherical particles obtained by a spray drying process. Alternatively, MS3050 product is unspray-dried silica from PQ Corporation. As obtained, this silica is not calcined (i.e., not dehydrated). Calcined silica purchased prior to purchase can also be used as a carrier material.

[0057] The support material can be pretreated by heating it in air before contacting the catalyst to obtain a calcined support material. The pretreatment involves heating the support material at a peak temperature of 350°C to 850°C, alternatively 400°C to 800°C, alternatively 400°C to 700°C, alternatively 500°C to 650°C, for a duration of 2 hours to 24 hours, alternatively 4 hours to 16 hours, alternatively 8 hours to 12 hours, or alternatively 1 hour to 4 hours, thereby producing a calcined support material. The support material can be a calcined support material.

[0058] The method may also employ a trimming catalyst. The trimming catalyst can be any of the aforementioned metallocene catalysts made from a metal-ligand complex of formula (I) and an activator. For convenience, the trimming catalyst is fed into the reactor as a solution in a hydrocarbon solvent (e.g., mineral oil or heptane). The hydrocarbon solvent may be ICA. The trimming catalyst can be made from the same metal-ligand complex of formula (I) used to prepare the bimodal catalyst system; alternatively, the trimming catalyst can be made from a different metal-ligand complex of formula (I) than the metallocene catalyst used to prepare the bimodal catalyst system. The trimming catalyst can be used to change the amount of metallocene catalyst used in the method, within limitations, relative to the amount of non-metallocene catalyst per unit point in the bimodal catalyst system. Each catalyst in the bimodal catalyst system is activated by contacting it with an activator. Any activator may be the same as or different from each other, and may independently be a Lewis acid, a noncoordinate ion activator, an ionizing activator, or a Lewis base, an alkylaluminoxane, or an alkylaluminoxane. Alkylaluminum may be trialkylaluminum, an alkylaluminum halide, or an alkylaluminum alkoxide (diethylethoxyaluminum). Trialkylaluminum may be trimethylaluminum, triethylaluminum (“TEAl”), tripropylaluminum, or tri(2-methylpropyl)aluminum. Alkylaluminum halide may be diethylaluminum chloride. Alkylaluminum alkoxide may be diethylethoxyaluminum. Alkylaluminoxane may be methylaluminoxane (MAO), ethylaluminoxane, 2-methylpropylaluminoxane, or modified methylaluminoxane (MMAO). Each alkyl group of the alkylaluminum or alkylaluminoxane may independently be (C1-C7) alkyl, alternatively (C1-C6) alkyl, or alternatively (C1-C4) alkyl. The molar ratio of the activator's metal (Al) to the metal (catalytic metal, such as Zr) of the specific catalyst compound can be from 1000:1 to 0.5:1, alternatively from 300:1 to 1:1, or alternatively from 150:1 to 1:1. Suitable activators are commercially available.

[0059] Once the activator and catalyst in a bimodal catalyst system come into contact with each other, the catalyst in the bimodal catalyst system is activated, and an activator species can be prepared in situ. The activator species may have a different structure or composition from the catalyst and activator from which it is derived, and may be a byproduct of catalyst activation or a derivative of the byproduct. The corresponding activator substances may be Lewis acids, noncoordinate ion activators, ionized activators, Lewis bases, or derivatives of alkylaluminum or alkylaluminoxanes. An example of a byproduct derivative is a methylaluminoxane species formed by devolatation during the spray drying of a bimodal catalyst system prepared with methylaluminoxane.

[0060] Each contact step between the activator and the catalyst can be carried out independently in a separate vessel outside the GPP reactor (e.g., outside the FB-GPP reactor) or in the feed line to the GPP reactor. In option (a), once the catalyst in the bimodal catalyst system is activated, the bimodal catalyst system can be fed into the GPP reactor in dry powder form, or alternatively in slurry form in a nonpolar, aprotic (hydrocarbon) solvent. One or more activators can be fed into the reactor in "wet mode" as a solution in an inert liquid such as mineral oil or toluene, in slurry mode as a suspension, or in dry mode as a powder. Each contact step can be carried out at the same or different times.

[0061] Test methods

[0062] density

[0063] Density was measured according to ASTM D792 and expressed in grams per cubic centimeter. 3 (g / cm) 3 (or g / cc) indicates.

[0064] Melt flow rates (I2, I5, and I21)

[0065] The melt flow rate was determined according to the procedure described in ASTM D1238. Method B of ASTM D1238 was used. Samples were run under loads of 21.6 kg, 5.0 kg, or 2.16 kg (i.e., I21, I5, or I2, respectively).

[0066] Absolute GPC (molecular weight distribution)

[0067] The chromatographic system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) connected to a Precision Detectors (now Agilent Technologies) 2-angle laser scattering (LS) detector model 2040 and four capillary viscometers (DV). For all absolute light scattering measurements, a 15-degree angle was used. The autosampler oven chamber was set to 160°C, and the column and detector chambers were set to 150°C. The columns used were four Agilent "MixedA" 30 cm 20 μm linear mixed-bed columns. The chromatographic solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen injection. The injection volume used was 200 μL, and the flow rate was 1.0 mL / min.

[0068] Total plate counts of the GPC column assembly were performed using decane, which was introduced into the blank sample via a micropump controlled by a PolymerChar GPC-IR system. For four Agilent "Mixed A" 30 cm 20 μm linear mixed-bed columns, the plate count of the chromatographic system should be greater than 18,000.

[0069] Samples were prepared semi-automatically using PolymerChar "Instrument Control" software, with a target sample weight of 2 mg / ml. Solvent (containing 200 ppm BHT) was added to a pre-bubbled, diaphragm-capped vial via a PolymerChar high-temperature autosampler. The sample was then dissolved at 160°C for 2 hours with "low-speed" shaking.

[0070] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate (nominal flow rate) for each sample by comparing the RV (RV(FM sample)) of the corresponding decane peak within the sample with the RV (RV(FM calibrated)) of the decane peak within the narrow standard calibration. It was then assumed that any variation in the decane marker peak time was linearly related to the flow rate (effective flow rate) throughout the run. After calibration based on the flow marker peak, the effective flow rate (relative to the narrow standard calibration) was calculated according to Equation 1. (via PolymerChar GPCOne) ™ The software processes the flow marker peaks. Acceptable flow rate correction ensures that the effective flow rate is within + / - 0.5% of the nominal flow rate.

[0071]

[0072] To determine the bias of the viscometer and light scattering detector relative to the IR5 detector, the systematic method for determining the multi-detector bias was performed in a manner consistent with that published by Balke, Mourey et al. (Mourey and Balke, Chromatography Polym., Chapter 12, (1992)) and (Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym., Chapter 13, (1992)), thereby using PolymerChar GPCOne. ™The software optimized triple detector logarithmic (MW and IV) results from linear homopolymer polyethylene standards (3.5 > Mw / Mn > 2.2) with narrow standard column calibration results from narrow standard calibration curves for a molecular weight range of 115,000 g / mol to 125,000 g / mol.

[0073] Absolute molecular weight data were obtained using PolymerChar GPCOne. ™ The software was obtained in accordance with the following published methods: Zimm (Zimm, BH, *Chem. Phys.*, 16, 1099 (1948)) and Kratochvil (Kratochvil, P., *Classical Light Scattering from Polymer Solutions*, Elsevier, Oxford, NY (1987)). The total injection concentration used for determining the molecular weight was obtained from the mass detector area and the mass detector constant, which was derived from either a suitable linear polyethylene homopolymer or a polyethylene standard with a known weight-average molecular weight. The calculated molecular weight (using GPCOne) was... ™ The light scattering constant and refractive index concentration coefficient dn / dc of -0.104 from one or more polyethylene standards mentioned below are typically obtained. The mass detector response (IR5) and light scattering constant (using GPCOne) are also used. ™ The determination should be performed using linear standards with a molecular weight exceeding approximately 50,000 g / mol. Viscometer calibration (using GPCOne) ™ The determination can be performed using the method described by the manufacturer, or alternatively, by using published values ​​of a suitable linear standard (such as Standard Reference Material (SRM) 1475, available from the National Institute of Standards and Technology (NIST)). The viscometer constant is calculated using GPCOne. ™ The specific viscosity area (DV) of the standard to be used for calibration and the injection mass are related to its intrinsic viscosity. It is assumed that the chromatographic concentration is low enough to eliminate the effect of resolving the second virial coefficient (the effect of concentration on molecular weight).

[0074] The absolute weight-average molecular weight (Mw(Abs)) is calculated by dividing the light scattering (LS) integral chromatogram (determined by the light scattering constant) by the mass recovered from the mass constant and the mass detector (IR5) region (using GPCOne). ™ The molecular weight and intrinsic viscosity responses were obtained at the chromatographic endpoints where the signal-to-noise ratio decreased (using GPCOne). ™Linear extrapolation. Calculate the other corresponding moments Mn(Abs) and Mz(Abs) according to the following equations:

[0075]

[0076] Deconvolution of absolute GPC chromatograms

[0077] Deconvolution of Absolute GPC Chromatograms - The absolute GPC chromatogram is fitted to a first and second fraction using a Flory distribution broadened with the following normal distribution function: For the log M axis, 601 equally spaced Log(M) points are established between 2 and 8, with an interval of 0.01, representing molecular weights between 100 and 100,000,000, where Log is a logarithmic function to base 10. At any given Log(M), the population of the Flory distribution takes the form of Equation 2:

[0078]

[0079] Where Mw is the absolute weight-average molecular weight of the Flory distribution, and M is the absolute molecular weight point on the x-axis (10 ^ [Log(M)]). The weighted fraction of the Flory distribution is widened at each Log(M) exponent at equal intervals of 0.01 according to the normal distribution function, with the width denoted as Log(M),s; and the current M exponent is denoted as Log(M),m.

[0080]

[0081] It should be noted that the area of ​​the distribution (dW) before and after applying the diffusion function is different. f / dLogM) is normalized to one as a function of Log(M). The two weight fraction distributions dW of components LMW and HMW, or components 1 and 2, are... f 1 and dW f 2 Let A1 and A2 be represented by two unique objective values ​​Mw1 and Mw2, and the total components. Both distributions are broadened by the same width s. The two distributions are summed as follows:

[0082]

[0083] Where: A1 + A2 = 1.

[0084] The weighted fractions of the measured absolute GPC molecular weight distribution were interpolated along 601 logM points using a second-order polynomial. (Microsoft Excel was used.) ™The 2010 Solver was used to minimize the sum of squared residuals of the isospatial ranges of the interpolated molecular weight distribution and the two broadened Flory distribution components (s1 and s2) at 601 LogM points, weighted by A1 and A2 based on their respective components. The initial iteration values ​​for each component are as follows:

[0085] Component 1: Mw1=60,000, s=0.200, and A1=0.7.

[0086] Component 2: Mw2 = 700,000, s = 0.200, and A2 = 1 - A 1。

[0087] (Note that s1 = s2 and A1 + A2 = 1).

[0088] The boundaries between components 1 and 2 are such that s > 0.001 yields approximately 2.00 Mw / Mn, and s < 0.550 yields approximately 5.71 Mw / Mn. Component A1 is limited to between 0.000 and 1.000. Mw1 is limited to between 2,500 and 2,000,000. Component A2 is limited to between 0.000 and 1.000. Mw2 is limited to between 2,500 and 2,000,000. (In ExcelSolver) ™ Select the "GRG Nonlinear" engine, set the precision to 0.00001, and the convergence to 0.0001. Obtain the converged solution (in all cases shown, the solution converges within 60 iterations). The high molecular weight percentage is equal to the output from A2 described above.

[0089] Pennsylvania Gap Test (PENT)

[0090] PENT was measured according to ASTM F1473 at 80°C and 2.4 MPa. Results are reported in hours.

[0091] strain hardening modulus

[0092] The strain hardening modulus was determined according to ISO 18488. The sample was compressed and molded at 180°C with a preheating time of 5 to 15 minutes, followed by a full pressure of 5 MPa for 5 minutes. A controlled cooling rate of 15°C / min was used in the final step. The compressed sheet was conditioned at 120°C for one hour, followed by controlled cooling to RT at a rate of 2°C / min. Tensile bars were punched from the compressed sheet. Tensile tests were performed at 80°C. Strain was recorded using a non-contact elongator. The slope between the tensile ratios of 8 and 12 was calculated using the Neo-Hookean strain scale (NHSM) and the true stress diagram, as specified in ISO 18488. If failure occurred before the tensile ratio reached 12, the tensile ratio corresponding to the failure strain was considered the upper limit of the slope. If failure occurred before the tensile ratio reached 8.5, the test was considered invalid.

[0093] melt strength

[0094] Melt strength was determined using a combination of a Göttfert Rheotens unit model 71.9 and a capillary rheometer (such as the Rheotester 2000 from Göttfert). The polymer melt (approximately 20 to 30 grams, granules) was extruded through a capillary die with a flat inlet angle (180 degrees), a capillary diameter of 2.0 mm, and an aspect ratio (capillary length / capillary diameter) of 15. After equilibrating the sample at 190°C for 10 minutes, the molten polymer was extruded at a theoretical average exit velocity corresponding to 9.5 mm / s and a s⁻¹ of 38.2 s⁻¹. -1 A constant volumetric flow rate extrusion die with an apparent wall shear rate. Rheotens' wheels are at standard laboratory temperature. The distance between the die exit and the wheels is 100 mm. The extruded line is stretched through a set of standard smooth wheels with a 0.4 mm gap. The wheels move at 2.4 mm / s. 2 The rate of tension is accelerated, and the tensile force is recorded as a function of the tensioning speed until the filament breaks. The breaking speed is a measure of the stretchability of the polymer melt. Melt strength is defined as the plateau value of the force-velocity curve just before online breakage and is reported in Newtons (N).

[0095] Complex viscosity

[0096] Complex viscosity (q*) was calculated using dynamic mechanical spectroscopy and reported in Pascal-seconds (Pa-s). Samples were compressed and molded into rectangular sheets measuring 9.75 inches x 10.25 inches x 1.85 mm thick in air at 190°C for 6.5 minutes under 25,000 psi pressure. The samples were then removed from the press and allowed to cool. The resulting sheets were subjected to a 25 mm diameter die cutter to extract disc-shaped samples for rheological testing. Isothermal frequency scanning was performed using a TA instrument with an Advanced Rheometric Expansion System (ARES) equipped with a 25 mm (diameter) parallel plate under nitrogen purging. The sample was placed on the plate and allowed to melt at 190°C for five minutes. The plate was then brought close to a 1.8 mm gap, the sample was trimmed (removing any excess sample extending beyond the perimeter of the 25 mm diameter plate), and testing commenced. This method includes an additional five-minute delay to allow for temperature equilibration. The test was conducted at 190°C within a frequency range of 0.1 radians per second (rad / s) to 100 rad / s under a constant strain amplitude of 10%.

[0097] Tension / Tear / Puncture / NCTL on Geomembrane

[0098] Tensile, tear, and puncture tests were performed on geomembranes formed from the multimodal compositions of this invention and comparative multimodal compositions according to GM-13 standard for MDPE membranes. Tear strength was measured according to ASTM D1004. Puncture resistance was measured according to ASTM D4833. Single-point NCTL was measured according to ASTM D5397. Tensile properties (i.e., tensile yield strength, elongation at break, yield stress, and tensile strength) were measured according to ASTM D6693.

[0099] Geomembrane manufacturing

[0100] The geomembrane was manufactured on the Collin casting line from certain of the multimodal compositions of this invention and comparative multimodal compositions. The melt temperature was set at 240°C, and the output rate was approximately 20 lb / hr. A membrane with a thickness of 60 mils and a width of 8 inches was produced. A low winding speed of approximately 0.7 m / min was used to minimize longitudinal orientation.

[0101] Example

[0102] Materials used

[0103] The following materials are included in the embodiments discussed below.

[0104] DOW ™DGDA-5310 NT (i.e., a unimodal ethylene copolymer medium-density polyethylene) was used as Comparative Example (CE) 1 and is commercially available from Dow Chemical Company, Midland, Michigan.

[0105] CONTINUUM ™ DGDA-2420 NT (i.e., a bimodal ethylene copolymer medium-density polyethylene) was used as Comparative Example (CE) 2 and is commercially available from Dow Chemical Company, Midland, Michigan.

[0106] Preparation of Comparative Examples 3 to 5

[0107] Bimodal polyethylene compositions, designated as Comparative Examples (CE) 3-5, were produced via gas-phase polymerization in a single reactor. The main catalyst was fed via a 0.125-inch injection tube to a reactor suitable for use as a UNIPOL. ™ In a polyethylene reactor commercially available from Univation Technologies, a 0.125-inch injection tube is positioned at the center of a 0.250-inch sleeve, through which isopentane and nitrogen streams are introduced to aid catalyst dispersion. The trimmed catalyst is also fed into the polyethylene reactor via the same 0.125-inch injection tube at a rate sufficient to provide the desired resin flow index. The reactor gas composition is controlled by metering the feed into the polyethylene reactor at a rate sufficient to maintain the desired ethylene partial pressure, the molar ratio of comonomer to ethylene (C2), the molar ratio of hydrogen (H2) to ethylene (C2), and the amount of isopentane. Based on the ethylene feed rate to the reactor, an additive, CA-300, commercially available from Univation Technologies, is fed separately into the polyethylene reactor at a rate sufficient to maintain an additive concentration of approximately 35 to 55 parts by weight per million parts by weight (ppmw). The polyethylene reactor temperature is maintained at the desired temperature, and the reactor residence time is approximately 1.8 to 2.5 hours. The reactor bed weight is maintained by discharging the granular resin into a discharge tank, which is then purged with nitrogen and again with a mixture of nitrogen and steam before being poured into the fiber bundles. Table 1A lists the polymerization conditions for CE 3 to CE 5.

[0108]

[0109] Embodiments 1 and 2 of the present invention and Comparative Embodiment 6

[0110] Dibenzylbis(2-(pentamethylphenylamino)ethyl)amine zirconium is a compound of formula (II), wherein M is Zr and each R is a benzyl group (“Bn”). It can be prepared by the procedures described in the art or obtained from UniVision Technologies LLC, a subsidiary of Dow Chemical Company, Midland, Michigan, USA, in Houston, Texas, USA. Representative compounds containing Group 15 elements (including dibenzylbis(2-(pentamethylphenylamido)ethyl)amine zirconium) and their preparation can be discussed and described in the following documents: U.S. Patent Nos. 5,318,935; 5,889,128; 6,333,389; 6,271,325; 6,689,847; and 9,981,371; and WO Publications WO 99 / 01460; WO 98 / 46651; WO2009 / 064404; WO 2009 / 064452; and WO 2009 / 064482.

[0111]

[0112] (II) CA-300: A continuous additive purchased from UniVision Technologies Ltd. Added to the gas-phase polymerization reactor to reduce electrostatic accumulation.

[0113] 1-Hexene comonomer: H2C=C(H)(CH2)3CH3. A comonomer copolymerized with ethylene in a gas-phase polymerization reactor. Ethylene (“C2”): CH2=CH2. A monomer polymerized in a gas-phase polymerization reactor. When copolymerized with 1-hexene, an ethylene / 1-hexene copolymer is prepared.

[0114] ICA: A mixture primarily composed of at least 95%, alternatively at least 98%, of 2-methylbutane (isopentane) and a minor component including at least pentane (CH3(CH2)3CH3). Molecular hydrogen: H2. Can be added to the gas-phase polymerization reactor to alter the molecular weight of the polyethylene produced therein. Mineral oil: Sonneborn HYDROBRITE 380 PO White. Can be used as a carrier liquid for feeding the catalyst into the gas-phase polymerization reactor.

[0115] Preparation 1: Synthetic Formula 3,6-Dimethyl-1H-indene. In a glove box, tetrahydrofuran (25 mL) and methylmagnesium bromide (2 equivalents, 18.24 mL, 54.72 mmol) were loaded into a 250-mL two-necked container equipped with a thermometer (side neck) and a solid feeding funnel. The contents of the container were cooled in a refrigerator set to -35°C for 40 minutes; when removed from the refrigerator, the contents of the container were measured to be -12°C. While stirring, solid indene [5-methyl-2,3-dihydro-1H-indene-1-one (catalog #HC-2282)] (1 equivalent, 4.000 g, 27.36 mmol) was added in small portions to the container, and the temperature rose due to the exothermic reaction; the addition was controlled to keep the temperature at or below room temperature. Once the addition was complete, the funnel was removed and the container was sealed (SUBA). The sealed container was moved to a fume hood (where the contents were already at room temperature) and placed under nitrogen purging, then stirred for 3 hours. The nitrogen purging was removed, and ether (25 mL) was added to the container in place of the evaporated solvent. The reaction was then cooled using an acetone / ice bath. Using a feeding funnel, a 15% v / v HCl solution (9 equivalents, 50.67 mL, 246.3 mmol) was added very slowly to the contents of the container, maintaining the temperature below 10 °C. The contents of the container were then slowly heated for approximately 12 hours (bath in place). The contents of the container were then transferred to a separatory funnel and the phases were separated. The aqueous phase was washed with ether (3 times, 25 mL). The combined organic phase was then washed with sodium bicarbonate (50 mL, saturated aqueous solution), water (50 mL), and brine (50 mL). The organic phase was dried over magnesium sulfate, filtered, and the solvent was removed by a rotary evaporator. The resulting dark oil, confirmed as a product by NMR, was dissolved in pentane (25 mL) and then filtered through a short silica gel stopper (pre-wetted with pentane) sealed with sodium sulfate. The stopper was rinsed with additional pentane (25 mL to 35 mL) and then combined with the first solution. The solution was dried by a rotary evaporator to give 2.87 g (74% yield) of 3,6-dimethyl-1H-indene, confirmed as a product by NMR. 1 H NMR (C6D6): δ7.18 (d, 1H), 7.09 (s, 1H), 7.08 (d, 1H), 5.93 (m, 1H), 3.07 (m, 2H), 2.27 (s, 3H), 2.01 (q, 3H).

[0116] Preparation 2: Synthesis of dimethyl(cyclopentadienyl)(1,5-dimethylindene)zirconium, which is a compound of formula (I), wherein R is H and each X is methyl. In a glove box under an anhydrous inert gas atmosphere (anhydrous nitrogen or argon), 10 mL of dimethoxyethane containing 1,000 g (6.94 mol) of 3,6-dimethyl-1H-indene was added to a 120 mL (4 oz) container, which was then capped and the contents were frozen to -35°C. Butyllithium (1.6 M hexane, 4.3 mL, 0.0069 mol) was added to the container, and the contents were stirred for approximately 3 hours while removing heat to maintain the contents near -35°C. Small aliquots were dissolved in d8-THF for... 1 ¹H NMR analysis was used to monitor the reaction progress; when the reaction was complete, solid cyclopentadienyl zirconium trichloride (CpZrCl₃) (1.821 g) was added in portions to the contents of the container while stirring. Small aliquots were dissolved in d8-THF for further analysis. 1 H NMR analysis was used to monitor the reaction progress; the reaction was completed after approximately 3 hours, and the contents of the container were stirred for approximately 12 hours. Then, methylmagnesium bromide (3.0 M in diethyl ether, 4.6 mL) was added to the contents of the container, and the contents were stirred for approximately 12 hours after the addition. The solvent was then removed under vacuum, and the product was extracted into hexane (40 mL) and filtered through diatomaceous earth, washed with another 30 mL of hexane, and then vacuum dried to provide dimethylcyclopentadienyl(1,5-dimethylindene)zirconium. Dimethyl(cyclopentadienyl)(1,5-dimethylindene)zirconium was analyzed by proton NMR spectroscopy (…). 1 Confirmed by H NMR analysis. 1 H NMR (C6D6): δ 7.26 (d, 1H), 6.92 (d, 1H), 6.83 (dd, 1H), 5.69 (d, 1H), 5.65 (m, 1H), 5.64(s, 5H), 2.18 (s, 3H), 2.16 (s, 3H), -0.34 (s, 3H), -0.62 (s, 3H).

[0117] According to IUPAC nomenclature rules, it is believed that the dimethyl group in the molecule 3,6-dimethyl-1H-indene is numbered as the conjugated anion 1,5-dimethylindene after deprotonation.

[0118] Preparation 3: Preparation of Bimodal Catalyst System 1 (AFS-BMCS1). A slurry containing 70.3 parts by weight of treated pyrolytic silica (CABOSIL TS-610) and 1000 parts by weight of toluene was prepared. Then, a 30% by weight solution of 171 parts by weight of methylaluminoxane (MAO) in toluene, 3.54 parts by weight of dibenzylbis(2-(pentamethylphenylamide)ethyl)amine zirconium, and 0.229 parts by weight of dimethylcyclopentadienyl(1,5-dimethylindene)zirconium from Preparation 2 were added to obtain a mixture. Using a spray dryer set to 160°C and with an outlet temperature of 70°C to 80°C, the mixture was introduced into the atomization device of the spray dryer to generate droplets of the mixture. The mixture was then contacted with a hot nitrogen stream to evaporate the liquid from the mixture, yielding a powder. The powder was separated from the gas mixture in a cyclone separator and discharged into a container to obtain the bimodal catalyst system 1 (“BMCS1”) catalyst as a fine powder. The resulting powdered BMCS1 was prepared into a slurry to obtain an activator formulation slurry of BMCS1 in the form of "AFS-BMCS1" with 22% by weight solids in 10% by weight isoparaffin fluid and 68% by weight mineral oil.

[0119] Preparation 4: Preparation of a trimming catalyst solution 1 (“TCS1”) comprising a trimming solution of dimethylcyclopentadienyl(1,5-dimethylindene)zirconium in hexane and isopentane. The dimethyl(cyclopentadienyl)(1,5-dimethylindene)zirconium from Preparation 2 and hexane were loaded into a first cylinder. The resulting solution of dimethyl(cyclopentadienyl)(1,5-dimethylindene)zirconium in hexane was transferred from the first cylinder into a 106-liter (L; 28-gallon) second cylinder. The second cylinder contained 310 g of 1.07 wt% dimethyl(cyclopentadienyl)(1,5-dimethylindene)zirconium. 7.98 kg (17.6 lb) of high-purity isopentane was added to a 106 L cylinder to produce a 0.04 wt% dimethyl(cyclopentadienyl)(1,5-dimethylindenyl)zirconium in hexane and isopentane as a modified catalyst solution 1.

[0120] Polymerization process. For Examples 1, 2, and CE 6 of the present invention described below, ethylene and 1-hexene are copolymerized in a fluidized bed-gas phase polymerization (FB-GPP) reactor with a distributed grid using a bimodal catalyst system 1 (AFS-BMCS1) in the form of an activator formulation slurry and a controlled relative amount of a trimming catalyst solution 1 (TCS1) to obtain an embodiment of a bimodal poly(ethylene-co-1-hexene) copolymer as a bimodal poly(ethylene-co-1-olefin) copolymer. The trimming catalyst solution 1 (TCS1), mixed with an isopentane support, is contacted with the bimodal catalyst system 1 (AFS-BCMC1) in the form of an activator formulation slurry en route to the reactor and mixed with a nitrogen support using a static mixer before being injected into the reactor. The catalyst is fed via a 0.125-inch injection tube. The 0.125-inch injection tube is located at the center of a 0.250-inch sleeve, in which isopentane and nitrogen streams are added to aid catalyst dispersion. The trimming catalyst was also fed into the polyethylene reactor via the same 0.125-inch injection tube at a rate sufficient to provide the desired resin flow index. The FB-GPP reactor has an inner diameter of 0.35 m and a bed height of 2.3 m, and the fluidized bed is composed of polymer particles. The fluidizing gas flows through a recirculating gas loop, which sequentially includes a recirculating gas compressor and a shell-and-tube heat exchanger with both water and gas sides. The fluidizing gas flows through the compressor, then the water side of the shell-and-tube heat exchanger, and then into the FB-GPP reactor below the distribution grid. The fluidizing gas velocity in the bed is approximately 0.58 m / s to 0.61 m / s (1.9 ft / s to 2.0 ft / s). The fluidizing gas then exits the FB-GPP reactor through nozzles in the top of the reactor and is continuously recirculated through the recirculating gas loop. A constant fluidized bed temperature of 95°C is maintained by continuously adjusting the temperature of the water on the shell side of the shell-and-tube heat exchanger. The feed streams of ethylene, nitrogen, hydrogen, and 1-hexene comonomer were introduced into the recirculating gas line. The FB-GPP reactor was operated at a total pressure of approximately 2413 kPa gauge pressure, and reactor gases were vented to a flare to control the total pressure. The individual flow rates of ethylene, nitrogen, hydrogen, and 1-hexene were adjusted to maintain their respective gas composition targets. The partial pressure of ethylene was set to 1.52 MPa (220 psi), and the C6 / C2 molar ratio and H2 / C2 molar ratio were set according to Table 1. The isopentane (ICA) concentration was maintained at approximately 10.5 mol%. The average copolymer residence time was approximately 2.3 to 2.5 hours. The concentrations of all gases were measured using online gas chromatography. The fluidized bed was maintained at a constant height by extracting a portion of the bed at a rate equal to the formation rate of the particulate product bimodal poly(ethylene-co-1-hexene) copolymer. The product was semi-continuously removed into a fixed-volume chamber via a series of valves.Nitrogen purging removed a significant portion of the entrained and dissolved hydrocarbons from the fixed-volume chamber. Following purging, the product was discharged from the fixed-volume chamber into a fiber pack for collection. The product was further treated with a small stream of moist nitrogen to deactivate any trace amounts of residual catalyst and co-catalyst. The ratio of the feed of the trimmed catalyst solution TCS1 to the feed of the bimodal catalyst system AFS-BMCS1 was set to control the HLMI (I) of the bimodal poly(ethylene-co-1-hexene) copolymer generated in the reactor. 21 Adjust to the target value. Set the catalyst feed to a rate sufficient to maintain the production rate of the bimodal poly(ethylene-co-1-hexene) copolymer at approximately 17 kg / h to approximately 21 kg / h (approximately 38 lbs / hr to approximately 46 lbs / hr).

[0121] Examples 1 and 2 (IE1, IE2) and Comparative Example 6 (CE6) of the present invention: embodiments of the copolymers of the present invention were synthesized using the above-described polymerization procedure and a bimodal catalyst system 1 (AFS-BMCS1) in the form of an activator formulation slurry and a trimmed catalyst solution 1 (TCS1), wherein the 1-olefin comonomer is 1-hexene. The polymerization conditions and process results are described in Table 1 below.

[0122]

[0123] The compositional properties of polyethylene were measured according to the above test method. A geomembrane was formed from certain polyethylene compositions according to the above geomembrane manufacturing method.

[0124]

[0125] Table 2B – Properties of IE 1 and 2 and CE 6

[0126]

[0127]

[0128] As can be seen from Tables 2A and 2B, the embodiments of the present invention exhibit an ideal balance of PENT, strain hardening, melt strength, and processability (as shown by viscosity, melt flow rate, and molecular weight distribution) superior to the comparative embodiments, and provide ideal tensile properties when the composition forms a geomembrane.

Claims

1. A multimodal polyethylene composition comprising from 20 wt% to 45 wt% of a first polyethylene component and a second polyethylene component, based on the total weight of the multimodal polyethylene composition, wherein the first polyethylene component has a greater molecular weight than the second polyethylene component, and wherein the multimodal polyethylene composition has the following: (a) a density of 0.933 g / cm 3 to 0.945 g / cm 3 to 0.945 g / cm (b) a high flow melt index (I 21 ) from 7.5 g / 10 min to 18.0 g / 10 min; (c) a molecular weight distribution (Mw / Mn) of less than 15.0 as measured by absolute GPC; and (d) a strain hardening modulus of at least 50 MPa.

2. The multimodal polyethylene composition of any preceding claim, wherein the multimodal composition has a PENT value of at least 5,000 hours as measured according to ASTM F1472.

3. The multi-modal polyethylene composition according to any preceding claim, wherein the composition has an I 21 / I5.

4. The multi-modal polyethylene composition of any preceding claim, wherein the composition has an I 21 / I2 of greater than 50.

5. The multimodal polyethylene composition of any preceding claim, wherein the composition has a Mz of greater than 1,600,000 g / mol.

6. The multimodal polyethylene composition of any preceding claim, wherein the composition has a melt strength of greater than 12.0 cN.

7. The multimodal polyethylene composition of any preceding claim, wherein the composition has a complex viscosity of less than 2,700 Pa.s at 100 rad / s.

8. The multimodal polyethylene composition of any preceding claim, wherein the composition is a bimodal polyethylene composition.

9. The multimodal polyethylene composition of any preceding claim, wherein the composition has a molecular weight distribution from absolute GPC, wherein the absolute GPC molecular weight distribution has a first peak and a shoulder peak in the Log (molecular weight) range of 3.5 to 7.0, wherein the first peak corresponds to the second polyethylene component and the shoulder peak corresponds to the first polyethylene component.

10. The multimodal polyethylene composition of any preceding claim, wherein when the composition forms a geomembrane, the geomembrane exhibits at least one of the following properties: a yield strength of at least 2,300 psi (or at least 2,400 psi); a break strength of at least 4,000 psi (or at least 4,500 psi or at least 49,00 psi); a yield elongation of at least 13% (or at least 14% or at least 14.5%); a break elongation of at least 700% (or at least 720%); a puncture strength of at least 2,000 pounds per inch (or at least 2,100 pounds per inch).

11. The multimodal polyethylene composition of any preceding claim, wherein when the composition forms a geomembrane, the geomembrane has a notched constant tensile load failure time of greater than 1,000 hours at 30% yield stress as measured according to ASTM D5397.

12. The multi-modal polyethylene composition of any preceding claim, wherein the composition is made in a single reactor in the presence of a bimodal catalyst system, wherein the bimodal catalyst system consists essentially of a metallocene catalyst, a single site non-metallocene catalyst that is a bis((alkyl-substituted phenylamido)ethyl)amine catalyst, an optional support material, and an optional activator; wherein the support material, when present, is selected from at least one of an inert hydrocarbon liquid and a solid support; wherein the metallocene catalyst is an activated reaction product of contacting an activator with a metal-ligand complex of the formula (R 1-2 Cp)((alkyl) 1-3 indenyl)MX2, wherein R is hydrogen, methyl, or ethyl; each alkyl is independently (Ci-C4)alkyl; M is titanium, zirconium, or hafnium; and each X is independently a halide, a (Ci to C 20 )alkyl, a (C7 to C 20 )aralkyl, a (Ci to C6)alkyl-substituted (C6 to C 12 )aryl, or a (Ci to C6)alkyl-substituted benzyl; and wherein the bis((alkyl-substituted phenylamido)ethyl)amine catalyst is an activated reaction product of contacting an activator with a bis((alkyl-substituted phenylamido)ethyl)amine ZrR 1 2, wherein each R 1 is independently selected from F, CI, Br, I, benzyl, -CH2Si(CH3)3, (Ci-C5)alkyl, and (C2-C5)alkenyl.

13. The multimodal polyethylene composition of any preceding claim, wherein the first polyethylene component and the second polyethylene component comprise 1-hexene.

14. A geomembrane comprising the multimodal polyethylene composition of any preceding claim.

15. The geomembrane of claim 14, wherein the geomembrane has a notched constant tensile load failure time greater than 1,500 hours at 30% yield stress as measured according to ASTM D5397.

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