Multimodal ethylene-based copolymer compositions and methods of production

Abstract

The present invention provides a process for preparing a multimodal ethylene-based copolymer. These processes include adding ethylene, at least one olefin monomer, at least a first catalyst system, and less than 0.3 mol% hydrogen to a solution polymerization reactor at a reactor temperature greater than or equal to 100 DEG C to produce an effluent feed. The effluent feed and a second catalyst system are fed to a second reactor in the absence of fresh feed and in the absence of hydrogen. At least one of the first catalyst system and the second catalyst system has a chain transfer constant of 0.005 to 1.0. The multimodal ethylene-based copolymer comprises from 8% to 50%, based on the total percentage of the multimodal ethylene-based copolymer, of high molecular weight fractions, i.e. Fractions having a molecular weight greater than 500,000 g / mol.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 510,779, filed on June 28, 2023, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The embodiments of this disclosure generally relate to polymer compositions, and more specifically to multimodal ethylene-based copolymer compositions and methods for their production. Background Technology

[0004] The use of polyolefin compositions in industries such as packaging applications is well-known. Such polyolefin compositions can be produced using a variety of conventional methods. Various polymerization techniques using different catalyst systems have been used to produce polyolefin compositions suitable for packaging applications. However, despite efforts to develop compositions suitable for packaging applications in some embodiments, there remains a need for improved polyethylene compositions suitable for packaging applications that offer a good balance of physical properties and melt strength at the desired polymer composition density. Summary of the Invention

[0005] Melt strength and processability are related properties of polyethylene resins. Generally, higher melt strength provides polyethylene resins with improved processability.

[0006] Furthermore, conventional polyethylene resins produced by conventional methods typically involve a trade-off between the resin's mechanical properties and melt strength. For example, low-density polyethylene (LDPE) produced by the known harmful conventional free radical method generally exhibits high melt strength but poor mechanical properties. Conversely, linear low-density polyethylene (LLDPE) prepared via solution or gas-phase methods typically has poor melt strength but excellent mechanical properties.

[0007] Therefore, to improve processability, a certain amount of LDPE is often blended with LLDPE to improve the processability and melt strength of the LLDPE resin. Unfortunately, compared with pure LLDPE resin, the addition of LDPE leads to a decrease in the mechanical properties of the resulting blend.

[0008] Therefore, there is a need for a solution polymerization method to produce polyethylene resin that can have melt strength comparable to polyethylene resin produced via a free radical method. Specifically, there is a need for a solution polymerization method to produce polyethylene resin that can have melt strength comparable to LDPE resin produced via a free radical method. Therefore, there is a need to produce high molecular weight (HMW) polyethylene copolymers and low molecular weight (LMW) polyethylene copolymers to produce multimodal ethylene-based copolymers. These multimodal ethylene-based copolymers having an HMW ethylene-based copolymer component have higher melt strength than polyethylene with a similar melt index that does not have this HMW polyethylene component.

[0009] Embodiments of this disclosure meet those needs by providing multimodal ethylene-based copolymers comprising a bulk low molecular weight (LMW) ethylene-based component prepared by one or more catalysts and a high molecular weight (HMW) ethylene-based component prepared by different catalysts. The multimodal ethylene-based copolymers described herein may have long-chain branching, which, together with the HMW ethylene-based component, allows for melt strength comparable to or higher than that of various LDPEs produced via conventional methods. Therefore, the multimodal ethylene-based copolymers described herein can be used as blending components with LLDPE in smaller amounts than those required by conventional LDPE resins, resulting in improved mechanical properties of the resulting LLDPE blends compared to those in conventional LLDPE / LDPE blends. In embodiments, the multimodal ethylene-based copolymers are produced via solution polymerization.

[0010] Embodiments of this disclosure include methods utilizing low H2 levels. Controlling the H2 level in the reactor allows for adjustment of the molecular weight of the ethylene-based copolymer. If the H2 level is too high, the molecular weight difference between the polymers prepared by the two catalysts may decrease to the point where there is no HMW ethylene-based copolymer component (and both catalysts will produce LMWPE), and no improvement in melt strength is obtained.

[0011] Embodiments of this disclosure include a method for preparing a multimodal ethylene-based copolymer. In one embodiment, the method includes adding ethylene, at least one olefin monomer, at least a first catalyst system, and less than 0.3 mol% hydrogen to a solution polymerization reactor at a reactor temperature greater than or equal to 150°C to produce an effluent feed; feeding the effluent feed and a second catalyst system into a second reactor where no fresh feed and no hydrogen are present; wherein: the first catalyst system comprises a first master catalyst and a first activator; and the second catalyst system comprises a second master catalyst and optionally a second activator; at least one of the first catalyst system and the second catalyst system has a chain transfer constant of 0.005 to 1.0. The multimodal ethylene-based copolymer comprises a high molecular weight fraction of 8% to 50% based on the total percentage of the multimodal ethylene-based copolymer, the high molecular weight fraction being calculated by measuring the area fraction of a molecular weight chromatogram obtained from the absolute molecular weight obtained by low-angle light scattering greater than 500,000 g / mol. Detailed Implementation

[0012] Embodiments of multimodal ethylene-based copolymer compositions and methods for their production will now be described. Ethylene-based polymers of ethylene and optionally one or more comonomers (such as α-olefins) may comprise at least 50 mol% of ethylene-derived monomer units. All individual values ​​and subranges covered by “at least 50 mol%” are disclosed herein as separate embodiments; for example, ethylene-based polymers may comprise at least 60 mol% of ethylene-derived monomer units; at least 70 mol% of ethylene-derived monomer units; at least 80 mol% of ethylene-derived monomer units; or 50 mol% to 100 mol% of ethylene-derived monomer units; or 80 mol% to 100 mol% of ethylene-derived monomer units.

[0013] method

[0014] Embodiments of this disclosure include a method for preparing a multimodal ethylene-based copolymer. In one embodiment, the method includes adding ethylene, at least one olefin monomer, at least a first catalyst system, and less than 0.3 mol% hydrogen to a solution polymerization reactor at a reactor temperature greater than or equal to 150°C to produce an effluent feed; feeding the effluent feed and a second catalyst system into a second reactor where no fresh feed and no hydrogen are present; wherein: the first catalyst system comprises a first master catalyst and a first activator; and the second catalyst system comprises a second master catalyst and optionally a second activator; at least one of the first catalyst system and the second catalyst system has a chain transfer constant of 0.005 to 1.0. The multimodal ethylene-based copolymer comprises a high molecular weight fraction of 8% to 50% based on the total percentage of the multimodal ethylene-based copolymer, the high molecular weight fraction being calculated by measuring the area fraction of a molecular weight chromatogram obtained from the absolute molecular weight obtained by low-angle light scattering greater than 500,000 g / mol.

[0015] In one embodiment, the multimodal ethylene-based copolymer composition can be produced via solution polymerization. In another embodiment, the method for preparing the multimodal ethylene-based copolymer may include contacting at least two olefin monomers in a solution polymerization reactor system in the presence of a catalyst system comprising at least one low-molecular-weight catalyst and at least one high-molecular-weight catalyst.

[0016] In embodiments, the solution polymerization reactor system may include one or more reactors. In embodiments, the solution polymerization reactor system may be a single-reactor system. In embodiments, the solution polymerization reactor system may be a dual-reactor system. In embodiments including a dual-reactor system, the solution polymerization reactor system may include a first reactor and a second reactor. Such solution polymerization methods include the use of one or more conventional reactors, such as loop reactors, isothermal reactors, adiabatic reactors, fluidized bed gas-phase reactors, stirred tank reactors (such as continuous stirred tank reactors), and batch reactors.

[0017] In one or more embodiments, the method includes adding less than 0.3 mol% of hydrogen to a solution polymerization reactor to produce an effluent feed. In one or more embodiments, the hydrogen feed is 0 mol% to 0.27 mol%, 0 mol% to 0.25 mol%, 0 mol% to 0.23 mol%, 0 mol% to 0.22 mol%, 0 mol% to 0.20 mol%, 0 mol% to 0.18 mol%, 0 mol% to 0.15 mol%, 0 mol% to 0.12 mol%, or 0 mol% to 0.10 mol%.

[0018] In an embodiment, ethylene and at least one olefin monomer may be polymerized in the presence of a catalyst to produce the multimodal ethylene-based copolymer composition described herein. The olefin monomer may be an α-olefin comonomer. Typically, the α-olefin monomer has no more than 20 carbon atoms. For example, the α-olefin comonomer 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. For example, one or more α-olefin comonomers may be selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene; or alternatively, from the group consisting of 1-hexene and 1-octene. In an embodiment, the α-olefin comonomer and process solvent may be purified with a molecular sieve before being introduced into the solution polymerization reactor system. The solvent, monomer, comonomer, and hydrogen may be combined and fed into the solution polymerization reactor system. Exemplary solvents include, but are not limited to, isoparaffins. For example, this type of solvent can be named ISOPAR. ™ E is purchased from ExxonMobil Chemical. In the implementation scheme, the combined feed can be temperature controlled to the following temperatures: 5°C to 50°C, 5°C to 25°C, 5°C to 10°C, 10°C to 50°C, 10°C to 25°C, or 25°C to 50°C.

[0019] In one embodiment, the reactor temperature is greater than or equal to 150°C. In some embodiments, the reactor temperature is between 150°C and 300°C. In one or more embodiments, the reactor temperature is between 150°C and 200°C.

[0020] The catalyst system described in more detail in subsequent sections is used for the polymerization of olefins to produce the multimodal ethylene-based copolymer compositions described herein. As previously mentioned, the catalyst system in the solution polymerization reactor system may comprise at least one first catalyst that produces a bulk low molecular weight (LMW) ethylene-based component and at least one second catalyst that produces a high molecular weight (HMW) ethylene-based component.

[0021] In one embodiment, the multimodal ethylene-based copolymer composition can be produced via solution polymerization, wherein ethylene and optionally one or more α-olefins are polymerized in the presence of a first catalyst to produce a bulk low molecular weight (LMW) ethylene-based component. As used herein, “bulk” can refer to a component constituting more than 50% of the composition based on the total weight of the composition. In one or more embodiments, the first catalyst may have a first catalyst efficiency of 1,000 kg polymer / g metal to 30,000 kg polymer / g metal. In another embodiment, the first catalyst may have a polymer / g metal ratio of 1,000 kg / g to 25,000 kg / g metal, 1,000 kg / g to 20,000 kg / g metal, 1,000 kg / g to 15,000 kg / g metal, 1,000 kg / g to 10,000 kg / g metal, 1,000 kg / g to 5,000 kg / g metal, 5,000 kg / g to 25,000 kg / g metal, 5,000 kg / g to 20,000 kg / g metal, or 5,000 kg / g to... Low molecular weight catalyst efficiencies of 15,000 kg polymer / g metal, 5,000 kg polymer / g metal to 10,000 kg polymer / g metal, 10,000 kg polymer / g metal to 25,000 kg polymer / g metal, 10,000 kg polymer / g metal to 20,000 kg polymer / g metal, 10,000 kg polymer / g metal to 15,000 kg polymer / g metal, 15,000 kg polymer / g metal to 25,000 kg polymer / g metal, 15,000 kg polymer / g metal to 20,000 kg polymer / g metal, or 1,000 kg polymer / g metal to 25,000 kg polymer / g metal.

[0022] In one embodiment, the multimodal ethylene-based copolymer composition can be produced via solution polymerization, wherein ethylene and optionally one or more α-olefins are polymerized in the presence of a second catalyst to produce a high molecular weight (HMW) ethylene-based component. In one or more embodiments, the second catalyst may have a second efficiency of 1,000 kg polymer / g metal to 100,000 kg polymer / g metal. In another embodiment, the second catalyst may have a second efficiency of 1,000 kg polymer / g metal to 75,000 kg polymer / g metal, 1,000 kg polymer / g metal to 50,000 kg polymer / g metal, or 1,000 kg polymer / g metal to 25,000 kg polymer / g metal. In another embodiment, the second catalyst may have a polymer / g metal content of 1,000 kg / g to 25,000 kg / g metal, 1,000 kg / g to 20,000 kg / g metal, 1,000 kg / g to 15,000 kg / g metal, 1,000 kg / g to 10,000 kg / g metal, 1,000 kg / g to 5,000 kg / g metal, 5,000 kg / g to 25,000 kg / g metal, 5,000 kg / g to 20,000 kg / g metal, or 5,000 kg / g polymer / g metal. The second catalyst exhibits a second polymerization efficiency of up to 15,000 kg polymer / g metal, 5,000 kg polymer / g metal to 10,000 kg polymer / g metal, 10,000 kg polymer / g metal to 25,000 kg polymer / g metal, 10,000 kg polymer / g metal to 20,000 kg polymer / g metal, 10,000 kg polymer / g metal to 15,000 kg polymer / g metal, 15,000 kg polymer / g metal to 25,000 kg polymer / g metal, 15,000 kg polymer / g metal to 20,000 kg polymer / g metal, or 1,000 kg polymer / g metal to 25,000 kg polymer / g metal. In one or more embodiments, the second catalyst may exhibit a second polymerization reactivity ratio of less than 20. In another embodiment, the second catalyst may exhibit a second polymerization reactivity ratio of less than 20, less than 15, or less than 10. In another embodiment, the second catalyst may exhibit a first reactivity ratio of 10 to 20, or 10 to 15, or 15 to 20.

[0023] In some embodiments, the multimodal ethylene-based copolymer composition can be produced via solution polymerization in a dual-reactor system, such as a dual-loop reactor system, wherein ethylene and optionally one or more α-olefins are polymerized in a first reactor in the presence of a low molecular weight catalyst system to produce a bulk low molecular weight (LMW) ethylene-based component, and ethylene and optionally one or more α-olefins are polymerized in a second reactor in the presence of a high molecular weight catalyst system to produce a high molecular weight (HMW) ethylene-based component. Additionally, one or more co-catalysts may be present.

[0024] In some embodiments, multimodal ethylene-based copolymer compositions can be produced via solution polymerization in a dual-reactor system, wherein the first reactor is a continuous stirred reactor and the second polymerization reactor is a non-stirred polymerization reactor, such as a non-stirred kettle reactor or a tubular reactor. In one or more embodiments, the non-stirred reactor is a plug flow reactor or a plug flow reactor. The term "non-stirred reactor" refers to a reactor that does not involve mechanical stirring, such as stirring by agitators, mixers, kneaders, etc. Examples of non-stirred reactors include plug flow reactors, kettle reactors, and loop reactors, all of which do not have agitators, mixers, etc.

[0025] In some embodiments, the solution polymerization reactor system may include one or more reactors operating at temperatures greater than 150°C. In other embodiments, the solution polymerization reactor system may include one or more reactors operating at temperatures of 160°C to 200°C, 160°C to 190°C, 160°C to 180°C, 160°C to 170°C, 170°C to 200°C, 170°C to 190°C, 170°C to 180°C, 180°C to 200°C, 180°C to 190°C, or 190°C to 200°C. Operating the solution polymerization reactor at elevated reactor temperatures (>150°C) can increase production rates and reduce energy consumption while still producing polyethylene products with acceptable catalyst efficiency and process control.

[0026] The reactor monomer feed (ethylene) stream is pressurized to a reaction pressure above 525 psig via a mechanical compressor. The solvent and comonomer (1-octene) feed streams are pressurized to a reaction pressure above 525 psig via a mechanical positive displacement pump.

[0027] Immediately following each fresh injection point, static mixing elements are used to mix the feed stream with the contents of the circulating polymerization reactor. The effluent from the polymerization reactor (containing solvent, monomer, comonomer, hydrogen, catalyst components, and molten polymer) exits the first reactor loop and passes through a control valve (responsible for maintaining the pressure of the first reactor at a specified target). As the feed stream leaves the reactor, it comes into contact with water to stop the reaction. Additionally, various additives, such as antioxidants, can be added at this point. The feed stream then passes through another set of static mixing elements to uniformly disperse the catalyst deactivator and additives.

[0028] After the addition of additives, the effluent (containing solvent, monomers, comonomers, hydrogen, catalyst components, and molten polymer) passes through a heat exchanger to raise the flow temperature, thus preparing the polymer for separation from other lower-boiling-point reactive components. The flow then enters a secondary separation and de-volatiles system, in which the polymer is removed from the solvent, hydrogen, and unreacted monomers and comonomers. The separated and de-volatiles-free polymer melt is pumped through a die specially designed for underwater granulation, cutting it into uniform solid granules, which are then dried and transferred to boxes for storage.

[0029] catalyst system

[0030] Specific embodiments of catalyst systems that can be used in one or more embodiments to produce the multimodal ethylene-based copolymer compositions described herein will now be described. It should be understood that the catalyst systems of this disclosure may be embodied in different forms and should not be construed as limited to the specific embodiments set forth in this disclosure. Rather, the provision of embodiments makes this disclosure thorough and complete, and the embodiments will fully convey the scope of the subject matter to those skilled in the art.

[0031] The term "independently chosen" is used in this document to indicate R groups (such as R...). 1 R 2 R 3 R 4 and R 5 ) can be the same or different (e.g., R) 1 R 2 R 3 R 4 and R 5 Both can be substituted alkyl groups, or R 1 and R 2 It can be a substituted alkyl group, and R 3(This can be aryl, etc.). Using the singular form includes using the plural form, and vice versa (e.g., hexane solvent contains hexane). The named R group will generally have a structure recognized in the art as corresponding to the R group having that name. These definitions are intended to supplement and illustrate, rather than exclude, definitions known to those skilled in the art.

[0032] The term "procatalyst" refers to a compound that exhibits catalytic activity when combined with an activator. The term "activator" refers to a compound that reacts chemically with the procatalyst in a manner that converts the procatalyst into a catalytically active catalyst. As used herein, the terms "co-catalyst" and "activator" are interchangeable.

[0033] When used to describe certain carbon-containing chemical groups, the form is "(C x –C y The insertion of ")" indicates that the unsubstituted form of the chemical group has x to y carbon atoms, inclusive. For example, (C1–C 40 Alkyl groups are alkyl groups having 1 to 40 carbon atoms in their unsubstituted form. In some embodiments and general structures, certain chemical groups may be such as R S One or more substituents are substituted. Use the parenthetical phrase "(C x –C y The chemical group defined by )” is R S The substituted version can contain more than y carbon atoms, depending on any group R. S The identity. For example, "by only one group R" S Replacement (C1–C 40 )alkyl (wherein R) S The phenyl group (-C6H5) can contain 7 to 46 carbon atoms. Therefore, it is common practice to use the parenthetical phrase "(C6H5)" when referring to phenyl groups. x –C y The chemical group defined as ")" is substituent for one or more carbon atoms by one or more substituents R. S During substitution, both x and y are added with substituents R from all carbon-containing groups. S The minimum and maximum total number of carbon atoms in a chemical group are determined by the sum of the combinations of carbon atoms.

[0034] The term "substitution" means that at least one hydrogen atom (-H) bonded to the carbon atom or heteroatom of the corresponding unsubstituted compound or functional group is substituted by a substituent (e.g., R). S Substitution. The term "total substitution" means that each hydrogen atom (H) bonded to the carbon atom or heteroatom of the corresponding unsubstituted compound or functional group is replaced by a substituent (e.g., R). SSubstitution. The term "multi-substitution" means that at least two, but fewer than all, of the hydrogen atoms bonded to the carbon or heteroatom of the corresponding unsubstituted compound or functional group are replaced by substituents.

[0035] The term “–H” refers to a hydrogen or hydrogen group covalently bonded to another atom. “Hydrogen” and “-H” are interchangeable and have the same meaning unless explicitly stated otherwise.

[0036] The terms "halogen atom", "halogen", "halogen", "saturated", "unsaturated", and "(C1–C)" are used to describe the properties of halogen atoms, halogens, halides, saturated, unsaturated, and (C1–C) compounds. 50 )hydrocarbon group", (C1–C 50 )alkyl", (C1–C 18 )alkyl", (C6–C 50 )Aryl", (C3–C 50 )cycloalkyl", (C1–C 50 )alkylene", "heteroatom" and "(C1–C 50 "Heteroalkyl" is defined as in patent application publication number WO2020185494A1.

[0037] According to some embodiments, the catalyst system for generating multimodal ethylene-based copolymer compositions includes a metal-ligand complex according to formula (I):

[0038] In formula (I), M is a metal selected from scandium, titanium, zirconium, hafnium, or a lanthanide element, in an oxidation state of +2, +3, or +4; n is 0, 1, or 2; when n is 1, X is a monodentate or bidentate ligand; when n is 2, each X is a monodentate ligand and may be the same or different; the metal-ligand complex is electrically neutral overall; each Z is independently selected from -O-, -S-, -N(R N - or -P(R) P )-; L is (C1-C 40 ) alkylene group or (C1-C 40 ) heteroalkyl groups, of which (C1-C 40 A portion of the alkylene group comprises a linker backbone of 1 to 10 carbon atoms of two Z groups (bonded with L) in formula (I), or (C1-C 40 A portion of the heteroalkyl group comprises a linker backbone of 1 to 10 atoms of the two Z groups in formula (I), wherein (C1-C 40 The linker backbone of the heteroalkyl group consists of 1 to 10 atoms, each of which is independently a carbon atom or a heteroatom, wherein each heteroatom is independently O, S, S(O), S(O)2, Si(R)2, or S(O)2. C )2、Ge(RC 2. P(R) C ) or N(R C ), where each R C Independently for (C1-C) 30 ) hydrocarbon group or (C1-C 30 ) heterohydrocarbon group; R 1 and R 8 Independently select from the following groups: -H, (C1-C 40 ) hydrocarbon group, (C1-C 40 heterohydrocarbon group, -Si(R) C )3、-Ge(R C )3、-P(R P )2、-N(R N )2、-OR C -SR C -NO2, -CN, -CF3, R C S(O)-、R C S(O)2-、(R C )2C=N-、R C C(O)O-、R C OC(O)-, R C C(O)N(R N )-、(R N )2NC(O)-, halogens and groups having formula (II), (III) or (IV):

[0039] In equations (II), (III), and (IV), R 31-35 R 41-48 Or R 51-59 Each of them is independently selected from (C1-C) 40 ) hydrocarbon group, (C1-C 40 heterohydrocarbon group, -Si(R) C )3、-Ge(R C )3、-P(R P )2、-N(R N 2. -N=CHR C -OR C -SR C -NO2, -CN, -CF3, R C S(O)-、R C S(O)2-、(R C )2C=N-、R C C(O)O-、R C OC(O)-, R C C(O)N(R N )-、(RN )2NC(O)-, halogen or -H, condition R 1 Or R 8 At least one of them is a group having formula (II), formula (III) or formula (IV).

[0040] In equation (I), R 2-4 R 5-7 and R 9-16 Each of them is independently selected from (C1-C) 40 ) hydrocarbon group, (C1-C 40 heterohydrocarbon group, -Si(R) C )3、-Ge(R C )3、-P(R P )2、-N(R N 2. -N=CHR C -OR C -SR C -NO2, -CN, -CF3, R C S(O)-、R C S(O)2-、(R C )2C=N-、R C C(O)O-、R C OC(O)-, R C C(O)N(R N )-、(R C )2NC(O)-, halogens and -H.

[0041] In some embodiments, the multi-peak ethylene-based copolymer composition is formed using a first catalyst according to formula (I) in a first reactor and a different catalyst according to formula (I) in a second reactor.

[0042] In one or more embodiments, the first or second catalyst system is capable of producing polymers with a native molecular weight greater than 100,000 g / mol. In some embodiments, the other of the first or second catalyst systems (which cannot produce polymers greater than 100,000 g / mol) is capable of producing polymers with a native molecular weight less than 80,000 g / mol. The native molecular weight of the polymer was measured in a single 1-gallon reactor containing ethylene at 320 psi, 60 g of 1-octene, and 0 H2 in the presence of 1250 g ISOPAR-E, at a reactor temperature of at least 160 °C. The term "native molecular weight" refers to the weight-average molecular weight of the polymer produced by the catalyst in the absence of hydrogen.

[0043] In various embodiments, a first catalyst system is capable of producing a first polymer having a native molecular weight, and a second catalyst system is capable of producing a second polymer having a native molecular weight that differs from the native molecular weight of the first polymer by at least 80,000 g / mol. In some embodiments, the molecular weight difference between the first and second polymers is from 80,000 g / mol to 2,000,000 g / mol. In some embodiments, the molecular weight difference between the first and second polymers is at least 90,000 g / mol, at least 100,000 g / mol, at least 120,000 g / mol, or at least 150,000 g / mol. The native molecular weight of the polymers was measured in the presence of 1250 g ISOPAR-E in a single 1-gallon reactor containing ethylene at a pressure of 320 psi, 60 g of 1-octene, and 0 H2, and at a reactor temperature of at least 160 °C.

[0044] co-catalyst components

[0045] Catalytic activity can be achieved by any technique known in the art for activating metal-based catalysts for olefin polymerization reactions, including metal-ligand complexes of formula (I). For example, a system containing a metal-ligand complex of formula (I) can be made catalytically active by contacting the complex with an activating cocatalyst or by combining the complex with an activating cocatalyst. Activating cocatalysts suitable for this document include alkylaluminum; polymeric or oligomeric aluminum oxanes (also known as aluminum oxanes); neutral Lewis acids; and non-polymeric, non-coordinated, ion-forming compounds (including those used under oxidizing conditions). A suitable activation technique is bulk electrolysis. Combinations of one or more of the aforementioned activating cocatalysts and techniques are also contemplated. The term "alkylaluminum" means dihydrogenated monoalkylaluminum or dihalogenated monoalkylaluminum, hydrogenated dialkylaluminum or halodialkylaluminum, or trialkylaluminum. Examples of polymeric or oligomeric aluminum oxanes include methylaluminoxane, methylaluminoxane modified with triisobutylaluminum, and isobutylaluminoxane.

[0046] Lewis acid activators (co-catalysts) include those containing 1 to 3 (C1-C1) groups as described herein. 20 A Group 13 metal compound with a hydrocarbon substituent. In one embodiment, the Group 13 metal compound is a tri((C1-C) group 13 metal compound. 20 ()hydrocarbon-substituted aluminum or tri((C1-C) 20 (Hydrocarbon)-boron compounds. In various embodiments, the Group 13 metal compound is a tri(hydrocarbon)-substituted aluminum, tri((C1-C2)-boron compound. 20 )hydro-boron compounds, tri((C1-C 10 Alkyl aluminum, tri((C6-C) 18(Aryl)boron compounds and their halogenated (including perhalogenated) derivatives. In other embodiments, the Group 13 metal compound is tri(fluorosubstituted phenyl)borane or tri(pentafluorophenyl)borane. In some embodiments, the activation cocatalyst is tri((C1-C)borane. 20 ) hydrocarbon borates (e.g., triphenylmethyltetrafluoroborate) or tri((C1-C 20 )hydro-based)ammonium tetra((C1-C 20 )alkyl)borane (e.g., bis(octadecyl)methylammonium tetra(pentafluorophenyl)borane). As used herein, the term "ammonium" refers to a nitrogen cation that is ((C1-C) 20 )hydrocarbon group)4N + 、((C1-C 20 )hydrocarbon group)3N(H) + 、((C1-C 20 )hydrocarbon group)2N(H)2 + (C1-C) 20 )hydrocarbon N(H)3 + or N(H)4 + Where there are two or more (C1-C) 20 When hydrocarbon groups are involved, they can be the same or different.

[0047] Combinations of neutral Lewis acid activators (co-catalysts) include tri((C1-C4)alkyl)aluminum and tri((C6-C4)halogenated tri((C6-C4)alkyl)aluminum. 18 Mixtures of arylborane compounds, particularly combinations of tris(pentafluorophenyl)borane. Embodiments include combinations of such neutral Lewis acid mixtures with polymeric or oligomeric aluminum oxanes, and combinations of single neutral Lewis acids (particularly tris(pentafluorophenyl)borane) with polymeric or oligomeric aluminum oxanes. The molar ratio of (metal-ligand complex):(tris(pentafluorophenyl)borane):(aluminoxane) [e.g., (Group 4 metal-ligand complex):(tris(pentafluorophenyl)borane):(aluminoxane)] is from 1:1:1 to 1:10:30, and in embodiments from 1:1:1.5 to 1:5:10.

[0048] Catalytic systems comprising metal-ligand complexes of formula (I) can be activated to form active catalyst compositions by combination with one or more cocatalysts (e.g., cation-forming cocatalysts, strong Lewis acids, or combinations thereof). Suitable activating cocatalysts include polymeric or oligomeric aluminum oxanes (especially methylaluminoxanes) and inert, compatible, noncoordinate, ion-forming compounds. Exemplary suitable cocatalysts include, but are not limited to: modified methylaluminoxane (MMAO), bis(hydrogenated tallow alkyl)methyltetra(pentafluorophenyl)boronic acid (1... - )amines, and combinations thereof.

[0049] In some embodiments, one or more of the aforementioned activation cocatalysts are used in combination with each other. Particularly preferred combinations are mixtures of tris((C1-C4)alkyl)aluminum, tris((C1-C4)alkyl)borane, or ammonium borate with oligomeric or polymeric aluminum oxane compounds. The ratio of the total molar number of one or more metal-ligand complexes of formula (I) to the total molar number of one or more activation cocatalysts in the activation cocatalyst is from 1:10,000 to 100:1. In some embodiments, the ratio is at least 1:5000, in some embodiments at least 1:1000; and 10:1 or less, and in some embodiments 1:1 or less. When an aluminum oxane is used alone as an activation cocatalyst, preferably, the molar number of the aluminum oxane used is at least 100 times the molar number of the metal-ligand complex of formula (I). In some embodiments, when tris(pentafluorophenyl)borane is used alone as an activation cocatalyst, the molar ratio of tris(pentafluorophenyl)borane to the total molar ratio of one or more metal-ligand complexes of formula (I) is from 0.5:1 to 10:1, 1:1 to 6:1, or 1:1 to 5:1. The remaining activation cocatalyst is typically used in a molar amount approximately equal to the total molar amount of one or more metal-ligand complexes of formula (I).

[0050] Composition

[0051] It has been found that by performing the process described above, multimodal ethylene-based copolymer compositions with improved melt strength can be produced. The properties of multimodal ethylene-based copolymer compositions according to embodiments disclosed and described herein will now be provided. It should be understood that embodiments of multimodal ethylene-based copolymer compositions with different and desirable properties can be produced by modifying the various process conditions described above. Although the properties listed below are described in separate paragraphs, it should be understood that any property from any of the following paragraphs can be combined with any other property from any of the following paragraphs by modifying the various process conditions discussed above. Therefore, multimodal ethylene-based copolymer compositions having the various properties listed below are contemplated, and these copolymer compositions can be prepared according to embodiments.

[0052] In one or more embodiments, the multimodal ethylene-based copolymer composition may have a content of 0.900 g / cm³. 3 Up to 0.940 g / cm 3 The density. For example, embodiments of the multi-peak ethylene-based copolymer compositions disclosed in this invention may have the following density: 0.900 g / cm³. 3 Up to 0.925 g / cm 3 0.900g / cm 3 Up to 0.920 g / cm 3 0.900g / cm3 Up to 0.918 g / cm 3 0.900g / cm 3 Up to 0.916 g / cm 3 0.900g / cm 3 Up to 0.914 g / cm 3 0.900g / cm 3 Up to 0.912 g / cm 3 0.900g / cm 3 Up to 0.910 g / cm 3 0.900g / cm 3 Up to 0.908 g / cm 3 0.900g / cm 3 Up to 0.906 g / cm 3 0.900g / cm 3 Up to 0.904 g / cm 3 0.900g / cm 3 Up to 0.902 g / cm 3 0.902 g / cm 3 Up to 0.920 g / cm 3 0.902 g / cm 3 Up to 0.918 g / cm 3 0.902 g / cm 3 Up to 0.916 g / cm 3 0.902 g / cm 3 Up to 0.914 g / cm 3 0.902 g / cm 3 Up to 0.912 g / cm 3 0.902 g / cm 3 Up to 0.910 g / cm 3 0.902 g / cm 3 Up to 0.908 g / cm 3 0.902 g / cm 3 Up to 0.906 g / cm 3 0.902 g / cm 3 Up to 0.904 g / cm 3 0.904 g / cm 3 Up to 0.920 g / cm 3 0.904 g / cm 3 Up to 0.918 g / cm 3 0.904 g / cm 3 Up to 0.916 g / cm 3 0.904 g / cm 3 Up to 0.914 g / cm 30.904 g / cm 3 Up to 0.912 g / cm 3 0.904 g / cm 3 Up to 0.910 g / cm 3 0.904 g / cm 3 Up to 0.908 g / cm 3 0.904 g / cm 3 Up to 0.906 g / cm 3 0.906 g / cm 3 Up to 0.920 g / cm 3 0.906 g / cm 3 Up to 0.918 g / cm 3 0.906 g / cm 3 Up to 0.916 g / cm 3 0.906 g / cm 3 Up to 0.914 g / cm 3 0.906 g / cm 3 Up to 0.912 g / cm 3 0.906 g / cm 3 Up to 0.910 g / cm 3 0.906 g / cm 3 Up to 0.908 g / cm 3 0.908g / cm 3 Up to 0.920 g / cm 3 0.908g / cm 3 Up to 0.918 g / cm 3 0.908g / cm 3 Up to 0.916 g / cm 3 0.908g / cm 3 Up to 0.914 g / cm 3 0.908g / cm 3 Up to 0.912 g / cm 3 0.908g / cm 3 Up to 0.910 g / cm 3 0.910 g / cm 3 Up to 0.920 g / cm 3 0.910 g / cm 3 Up to 0.918 g / cm 3 0.910 g / cm 3 Up to 0.916 g / cm 3 0.910 g / cm 3 Up to 0.914 g / cm 3 0.910 g / cm 3 Up to 0.912 g / cm3 0.912 g / cm 3 Up to 0.920 g / cm 3 0.912 g / cm 3 Up to 0.918 g / cm 3 0.912 g / cm 3 Up to 0.916 g / cm 3 0.912 g / cm 3 Up to 0.914 g / cm 3 0.914 g / cm 3 Up to 0.920 g / cm 3 0.914 g / cm 3 Up to 0.918 g / cm 3 0.914 g / cm 3 Up to 0.916 g / cm 3 0.916 g / cm 3 Up to 0.920 g / cm 3 0.916 g / cm 3 Up to 0.918 g / cm 3 0.918 g / cm 3 Up to 0.920 g / cm 3 Or any combination of these ranges.

[0053] In one or more embodiments, when measured according to ASTM D-1238 at 190°C and 2.16 kg, the melt index (I2) of the multipeak ethylene-based copolymer composition can be from 0.50 g / 10 min to 10.0 g / 10 min. In one or more embodiments, when measured according to ASTM D-1238 at 190°C and 2.16 kg, the melt index (I2) of the multipeak ethylene-based copolymer composition can be from 0.50 g / 10 min to 10.0 g / 10 min. When measured at 190°C and 2.16 kg, D-1238 showed that the multi-peaked ethylene-based copolymer compositions could exhibit values ​​of 0.5 g / 10 min to 10.0 g / 10 min, 0.5 g / 10 min to 9.0 g / 10 min, 0.5 g / 10 min to 8.0 g / 10 min, 0.5 g / 10 min to 7.0 g / 10 min, 0.5 g / 10 min to 6.0 g / 10 min, 0.5 g / 10 min to 5.0 g / 10 min, 0.5 g / 10 min to 4.0 g / 10 min, 0.5 g / 10 min to 3.0 g / 10 min, 0... 0.5g / 10min to 2.0g / 10min, 0.5g / 10min to 1.0g / 10min, 1.0g / 10min to 10.0g / 10min, 1.0g / 10min to 9.0g / 10min, 1.0g / 10min to 8.0g / 10min, 1.0g / 10min to 7.0g / 10min, 1.0g / 10min to 6.0g / 10min, 1.0g / 10min to 5.0g / 10min, 1.0g / 10min to 4.0g / 10min, 1.0g / 10min to 3.0g / 10min n, 1.0g / 10min to 2.0g / 10min, 2.0g / 10min to 10.0g / 10min, 2.0g / 10min to 9.0g / 10min, 2.0g / 10min to 8.0g / 10min, 2.0g / 10min to 7.0g / 10min, 2.0g / 10min to 6.0g / 10min, 2.0g / 10min to 5.0g / 10min, 2.0g / 10min to 4.0g / 10min, 2.0g / 10min to 3.0g / 10min, 3.0g / 10min to 10.0g / 10 min, 3.0 g / 10 min to 9.0 g / 10 min, 3.0 g / 10 min to 8.0 g / 10 min, 3.0 g / 10 min to 7.0 g / 10 min, 3.0 g / 10 min to 6.0 g / 10 min, 3.0 g / 10 min to 5.0 g / 10 min, 3.0 g / 10 min to 4.0 g / 10 min, 4.0 g / 10 min to 10.0 g / 10 min, 4.0 g / 10 min to 9.0 g / 10 min, 4.0 g / 10 min to 8.0 g / 10 min, 4.0 g / 10 min to 7.0g / 10min, 4.0g / 10min to 6.0g / 10min, 4.0g / 10min to 5.0g / 10min, 5.0g / 10min to 9.0g / 10min, 5.0g / 10min to 8.0g / 10min, 5.0g / 10min to 7.0g / 10min, 5.0g / 10min to 6.0g / 10min, 6.0g / 10min to 10.0g / 10min, 6.0g / 10min to 9.0g / 10min, 6.0g / 1 Melt index (I2) of 0 min to 8.0 g / 10 min, 6.0 g / 10 min to 7.0 g / 10 min, 7.0 g / 10 min to 10.0 g / 10 min, 7.0 g / 10 min to 9.0 g / 10 min, 7.0 g / 10 min to 8.0 g / 10 min, 8.0 g / 10 min to 10.0 g / 10 min, 8.0 g / 10 min to 9.0 g / 10 min, 9.0 g / 10 min to 10.0 g / 10 min, or any combination of these ranges.

[0054] According to the implementation scheme, the molecular weight distribution of the multimodal ethylene-based copolymer composition, expressed as the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn), can be in the range of 2.0 to 6.0. For example, the multimodal ethylene-based copolymer composition may have a molecular weight distribution in the following ranges: 2.0 to 5.5, 2.0 to 5.0, 2.0 to 4.5, 2.0 to 4.0, 2.0 to 3.5, 2.0 to 3.0, 2.0 to 2.5, 2.5 to 6.0, 3.0 to 5.5, 3.0 to 5.0, 3.0 to 4.5, 3.0 to 4.0, 3.0 to 3. 5, 3.5 to 6.0, 3.5 to 5.5, 3.5 to 5.0, 3.5 to 4.5, 3.5 to 4.0, 4.0 to 6.0, 4.0 to 5.5, 4.0 to 5.0, 4.0 to 4.5, 4.5 to 6.0, 4.5 to 5.5, 4.5 to 5.0, 5.0 to 6.0, 5.0 to 5.5, or 5.5 to 6.0, or any combination of these ranges. As described herein, the molecular weight distribution can be calculated using gel permeation chromatography (GPC) techniques as described herein.

[0055] According to the implementation scheme, multi-peak ethylene-based copolymer compositions can have an activation energy (Ea) greater than 30 kJ / mol, as determined by dynamic mechanical analysis. The activation energy is calculated from rheological time-temperature superimposed viscosity data obtained from melt rheological frequency scans. These measurements were performed using a TA Instruments Advanced Rheological Extension System (ARES) equipped with a 25 mm parallel plate, purged with nitrogen. The linear viscoelastic response was measured at three different temperatures (150 °C, 190 °C, and 230 °C) using frequencies of 0.1 rad / s–500 rad / s, 0.1 rad / s–100 rad / s, and 0.01 rad / s–100 rad / s, respectively. Strain was varied based on the transducer torque output, ensuring the torque remained within acceptable limits. The stress response was analyzed based on amplitude and phase, from which the storage modulus and loss modulus, as well as the dynamic melt viscosity, were calculated. The temperature dependence of the linear viscoelastic curve can be predicted by using multiple sets of offset factors to make the modulus curve relative to a reference offset frequency axis (X-axis). This concept is commonly referred to as time-temperature superposition. This technique involves shifting curves at different temperatures in a manner that causes them to overlap and form a single curve, also known as the master curve. The shift factor is generated using RepTate software. A reference temperature of 190°C is chosen. The Arrhenius equation correlates the horizontal shift factor with the activation energy and the reference temperature according to the following equation:

[0056]

[0057] In other embodiments, the multimodal ethylene-based copolymer composition may have an activation energy (Ea) of the composition as determined by dynamic mechanical analysis, which may be 30 kJ / mol to 60 kJ / mol, 30 kJ / mol to 50 kJ / mol, 30 kJ / mol to 40 kJ / mol, 40 kJ / mol to 60 kJ / mol, 40 kJ / mol to 50 kJ / mol, or 50 kJ / mol to 60 kJ / mol.

[0058] According to the implementation scheme, the multimodal ethylene-based copolymer composition may have a melt strength (MS) that satisfies Equation 1 below:

[0059]

[0060] In Equation 2, x equals 15, y is greater than or equal to 1, and I2 is the melt index of the copolymer as measured according to ASTM 1238 at 2.16 kg and 190 °C. According to one or more embodiments, the multimodal ethylene-based copolymer composition may have a melt strength of at least 5 centinenewtons (cN). In another embodiment, the multi-peak ethylene-based copolymer composition may have 5cN to 50cN, 5cN to 45cN, 5cN to 40cN, 5cN to 35cN, 5cN to 30cN, 5cN to 25cN, 5cN to 20cN, 5cN to 15cN, 5cN to 10cN, 10cN to 50cN, 10cN to 45cN, 10cN to 40cN, 10cN to 35cN, 10cN to 30cN, 10cN to 25cN, 10cN to 20cN, 10cN to 15cN, 15cN to 50cN, 15cN to 45cN, 15cN to 40cN, 15cN to 35cN, 15cN to 30cN. Melt strengths of 15cN to 25cN, 15cN to 20cN, 20cN to 50cN, 20cN to 45cN, 20cN to 40cN, 20cN to 35cN, 20cN to 30cN, 20cN to 25cN, 25cN to 50cN, 25cN to 45cN, 25cN to 40cN, 25cN to 35cN, 25cN to 30cN, 30cN to 50cN, 30cN to 45cN, 30cN to 40cN, 30cN to 35cN, 35cN to 50cN, 35cN to 45cN, 35cN to 40cN, 40cN to 50cN, 40cN to 45cN, or 45cN to 50cN.

[0061] In one embodiment, the multimodal ethylene-based copolymer composition may have a viscosity ratio (V0.1 / V100) greater than 5, measured at 0.1 radians / second and 190°C, to the viscosity measured at 100 radians / second and 190°C, as determined by dynamic mechanical analysis. In another embodiment, the multimodal ethylene-based copolymer composition may have the following (V0.1 / V100) determined by dynamic mechanical analysis: 5 to 30, 5 to 25, 5 to 20, 5 to 15, 5 to 10, 10 to 30, 10 to 25, 10 to 20, 10 to 15, 15 to 30, 15 to 25, 15 to 20, 20 to 30, 20 to 25, or 25 to 30.

[0062] In the implementation plan, light scattering analysis (CDF) is performed at molecular weights greater than 500,000 g / mol. LSThe cumulative distribution fraction (CDF) of the copolymer is greater than or equal to 8%. In one or more embodiments, the molecular weight of more than 500,000 g / mol is 8% to 50%, 10% to 50%, 20% to 50%, 30% to 50%, or 20% to 40%, based on the total percentage of the multimodal ethylene-based copolymer.

[0063] In embodiments, the multi-peak ethylene-based copolymer composition may have a high molecular weight fraction of 8% to 50%, which is calculated by measuring the area fraction of a chromatogram with a low-angle light scattering (LALLS) detector greater than 500,000 g / mol. In embodiments, the high molecular weight fraction calculated by measuring the area fraction of a chromatogram with a low-angle light scattering (LALLS) detector greater than 500,000 g / mol may be 8% to 40%, 8% to 30%, 10% to 50%, 10% to 40%, 10% to 30%, 20% to 50%, 20% to 40%, 20% to 30%, 30% to 50%, 30% to 40%, or 40% to 50%.

[0064] In embodiments, the multi-peak ethylene-based copolymer composition may have a low molecular weight fraction greater than 50%, which is calculated by measuring the area fraction of a low-angle light scattering (LALLS) detector chromatogram of less than 500,000 g / mol. In embodiments, the high molecular weight fraction calculated by measuring the area fraction of a low-angle light scattering (LALLS) detector chromatogram of less than 500,000 g / mol may be 50% to 92%, 50% to 90%, 50% to 80%, 50% to 70%, 50% to 60%, 60% to 92%, 60% to 90%, 60% to 80%, 60% to 70%, 70% to 92%, 70% to 90%, 70% to 80%, 80% to 92%, 80% to 90%, or 90% to 92%. Traditionally, having as much high molecular weight material as possible is considered ideal because high molecular weight leads to a high level of entanglement that improves the properties of LLDPE. Therefore, the amount of low molecular weight material is kept to a minimum. However, when the high molecular weight fraction, calculated by measuring the area fraction of the chromatogram of a low-angle light scattering (LALLS) detector with a concentration greater than 500,000 g / mol, is 8% to 50%, the multi-peak ethylene-based copolymer compositions according to the embodiments disclosed and described herein exhibit unique and unexpected properties compared to commercially available LDPE products.

[0065] The multimodal ethylene-based copolymer composition may also contain one or more additives. Such additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, and combinations thereof. The multimodal ethylene-based copolymer composition may contain any amount of additives. Based on the total weight of the multimodal ethylene-based copolymer composition, the multimodal ethylene-based copolymer composition may contain about 0% to about 10% of such additives by weight. The multimodal ethylene-based copolymer composition may further contain fillers, which may include, but are not limited to, organic or inorganic fillers. Based on the total weight of the multimodal ethylene-based copolymer composition, the multimodal ethylene-based copolymer composition may contain about 0% to about 20% by weight of fillers, such as calcium carbonate, talc, or Mg(OH)₂. The multimodal ethylene-based copolymer composition may be further blended with one or more polymers to form blends.

[0066] Test methods

[0067] Unless otherwise indicated herein, the following analytical methods are used to describe various aspects of this disclosure:

[0068] Melt index

[0069] The melt index I2 (or I2) and I of the polymer sample 10 (Or I10) Measured at 190°C and under loads of 2.16 kg and 10 kg respectively, according to ASTM D-1238 (Method B). The values ​​are reported in g / 10 min.

[0070] density

[0071] Samples for density measurement are prepared according to ASTM D4703. According to ASTM D792, Method B involves measuring the sample within one hour of pressing it.

[0072] Triple detector gel permeation chromatography (GPC)

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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 of the corresponding decane peak in the sample (RV(FM sample)) with the retention volume of the decane peak within the narrow standard calibration (RV(FM 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 using the flow marker-based peak system, the effective flow rate (relative to the narrow standard calibration) was calculated according to Equation 3. 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.

[0077]

[0078] 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 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.

[0079] Absolute molecular weight data 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...) The light scattering constant and refractive index concentration coefficient dn / dc of -0.104 from one or more polyethylene standards mentioned below are used to obtain the light scattering constant. Typically, the mass detector response (IR5) and light scattering constant (using...) are... The determination should be performed using linear standards with a molecular weight exceeding approximately 50,000 g / mol. Viscometer calibration (using...) 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... 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).

[0080] Absolute weight-average molecular weight (MW) (Abs) ) is (using The molecular weight and intrinsic viscosity responses are obtained by dividing the area of ​​the light scattering (LS) integral chromatogram (calculated from the light scattering constant) by the mass recovered from the mass constant and the area of ​​the mass detector (IR5). The molecular weight and intrinsic viscosity responses are at the chromatographic ends where the signal-to-noise ratio decreases (using...). Linear extrapolation. Other corresponding torques Mn (Abs) and Mz (Abs) The calculation is based on equation 4-6 as follows:

[0081]

[0082]

[0083]

[0084] CDF Calculation Method

[0085] The cumulative detector fraction (CDF) of a low-angle laser scattering (LALLS) detector is calculated by subtracting peak height (H) from the baseline of the absolute molecular weight chromatogram. LS The calculation of molecular weight (RV) is performed. At each data slice (j), these values ​​are summed across the entire chromatogram from high molecular weight to low molecular weight (from low retention volume to high retention volume, RV), essentially integrating the area of ​​the chromatogram. The fraction of the entire molecular weight chromatogram (or a percentage if multiplied by 100) is obtained by comparing a value greater than or equal to 500,000 g / mol with the lowest RV relative to the entire chromatogram, Equation 7:

[0086]

[0087] NMR terminal group analysis procedure including vinyl counting

[0088] To determine the vinyl count, approximately 7 mg of polymer sample was loaded into a 5 mm NMR tube containing 0.6 mL of tetrachloroethane-d2 and 0.008 M chromium acetylacetone (III). The tube was purged with N2 and capped with Teflon tape. The prepared sample tube was heated in a heating block set to 125 °C and vortexed repeatedly until a homogeneous solution was obtained, as demonstrated by consistent flow when the tube was tilted horizontally. The completed sample was then inserted into a Bruker AVANCE 600 MHz system equipped with a 10 mm cryogenic probe set to 120 °C. 1 The acquisition parameters for the H NMR spectrum were: 90-degree pulse, 1.8-second acquisition time, 10-second relaxation delay, spectral center set at 2 ppm, spectral width at 20 ppm, and 128 scans for signal averaging. The resulting raw FID was exponentially multiplied, Fourier transformed, phased, and baseline corrected, and then integrated using MNOVA software.

[0089] melt strength

[0090] Melt strength tests were performed on either a Rheotester 2000 or Rheograph 25 capillary rheometer paired with a Rheotens model 71.97, all of which were manufactured by Göttfert. The test die had a diameter of 2 mm, a length of 30 mm, and an entry angle of 180 degrees. Each test was typically performed isothermally at 190 degrees Celsius.

[0091] During testing, a granular sample was loaded into a capillary tube and equilibrated at the test temperature for 10 minutes. A piston inside the tube then applied a steady force to the molten sample to achieve an apparent wall shear rate of 38.16 s⁻¹, extruding the melt through a die at an exit velocity of approximately 9.7 mm / s. 100 mm below the die exit, the extrudate was guided through a pair of Rheotens wheels, both accelerating at a constant rate of 2.4 mm / s², and the extrudate's response to the applied tensile force was measured. Note that the Rheotens wheels are serrated and spaced 0.4 mm apart. The results of this test were recorded as a graph of force versus Rheotens wheel speed using the RtensEvaluations2007 Excel macro. For analysis, the force at which fracture occurs in the melt is referred to as the melt strength of the material, and the corresponding Rheotens wheel speed at fracture is considered the tensile limit.

[0092] DMS frequency scan

[0093] For preparation, the test sample was initially placed in a 1.5-inch diameter groove with a thickness of 3.10 mm and compressed at 190°C using a Carver hydraulic press (model #4095.4NE2003) at a pressure of 25,000 lb for 6.5 min. After cooling to room temperature, the sample was removed and awaited rheological testing.

[0094] DMS (Dynamic Mechanical Spectroscopy) frequency scans were performed using 25 mm parallel plates at frequencies of 0.01 rad / s to -100 rad / s, 0.1 rad / s to 100 rad / s, and 0.1 rad / s to 500 rad / s at 150 °C, 190 °C, and 230 °C, respectively. The test gap separating these plates was 1.8 mm, and strain satisfying linear viscoelastic conditions, typically 10% strain, was used. Each test was performed under a nitrogen atmosphere and isothermal conditions. To initiate the DMS test, the rheometer oven was first equilibrated at the desired test temperature for at least 30 min, and then the sample was loaded into the test geometry. The sample was then equilibrated in the oven with the door closed for 1 minute. The test gap was then set to 1.8 mm, and the sample was distributed for 5 minutes to release the generated normal forces. Afterward, the oven was quickly opened, and the sample was trimmed to eliminate any bulging. The DMS measurement was then initiated after the oven was closed again. During the test, the shear modulus (G'), viscous modulus (G"), and complex viscosity (v) were measured.

[0095] All DMS frequency tests were performed on either an ARES-G2 or DHR-3 rheometer, both manufactured by TA Instruments. Data analysis was performed using TA Instruments' TRIOS software.

[0096] Polymerization procedure in a continuous reactor: Setting 1

[0097] The raw materials (ethylene, 1-octene) and process solvents (narrow boiling range, high-purity isoparaffin solvents, commercially available from Shell and ExxonMobil Corporation under the trademarks SBP100-140 or Isopar-E) were purified using molecular sieves and then introduced into the reaction environment. Hydrogen was supplied at a high purity level in a pressurized cylinder without further purification. The reactor monomer feed (ethylene) stream was pressurized to above the reaction pressure via a mechanical compressor. The solvent and comonomer (1-octene) feed streams were pressurized to above the reaction pressure via a mechanical positive displacement pump. MMAO-3A or MMAO-7, commercially available from Nouryon, was used as an impurity remover and / or catalyst activator. The individual catalyst components (pre-catalysts or co-catalysts) were manually diluted in batches with the purified solvent (Isopar E or SBP 100-140) to the specified component concentrations and pressurized to above the reaction pressure. The co-catalyst is [HNMe(C)], which is commercially available from Boulder Scientific. 18 H 37 [B(C6F5)4], and unless otherwise specified, used at a ratio of 1.2 relative to the main catalyst. All reaction feed streams are measured by mass flow meters and independently controlled by a computer-automated valve control system.

[0098] Continuous solution polymerization is carried out in one or more of a CSTR, loop, and / or plug flow reactor. When specified, the CSTR and loop reactors independently control all fresh solvent, monomer, comonomer, hydrogen, and catalyst component feeds. Fresh feed for a second reactor may not be required (i.e., fresh solvent, monomer, comonomer, and hydrogen may not be added to the second reactor). The plug flow reactor has independent control over the catalyst component feed. The temperature of the combined solvent, monomer, comonomer, and hydrogen fed to the reactor is controlled at any temperature between 5°C and 50°C, and typically 25°C. The fresh comonomer feed to the polymerization reactor is fed together with the solvent feed. The fresh solvent feed is typically controlled at half the total fresh feed mass flow rate received at each injector. The cocatalyst is fed based on a calculated specified molar ratio to the main catalyst. Immediately after each fresh injection point, a static mixing element is used to mix the feed stream with the contents of the circulating polymerization reactor. The catalyst feed ratio is adjusted to obtain the desired polymer MI, density, and melt strength. The effluent from the polymerization reactor system (containing solvent, monomer, comonomer, hydrogen, catalyst components, and molten polymer) exits and passes through a control valve (responsible for maintaining the reactor system pressure at a specified target). As the feed stream leaves the reactor, it comes into contact with water to stop the reaction. Additionally, various additives, such as antioxidants, can be added at this point. The feed stream then passes through another set of static mixing elements to uniformly disperse the catalyst, activator, and additives.

[0099] After the addition of additives, the effluent (containing solvent, monomers, comonomers, hydrogen, catalyst components, and molten polymer) passes through a heat exchanger to raise the flow temperature, thus preparing the polymer for separation from other lower-boiling-point reactive components. The flow then enters a secondary separation and de-volatiles system, where the polymer is removed from the solvent, hydrogen, and unreacted monomers and comonomers. The separated and de-volatiles-free polymer melt is pumped through a specially designed die for underwater granulation, cut into uniform solid beads, dried, and transferred to boxes for storage.

[0100] Polymerization process in a continuous reactor: Setting 2

[0101] All feedstocks (monomers and comonomers) and process solvents (narrow-boiling-range, high-purity isoparaffin solvent, Isopar-E) were purified using molecular sieves before being introduced into the reaction environment. Hydrogen was supplied pressurized at a high purity level without further purification. The monomer feed stream to the reactor was pressurized to above the reaction pressure via a mechanical compressor. The solvent and comonomer feed streams were pressurized to above the reaction pressure via pumps. Individual catalyst components were manually diluted in batches with purified solvent and pressurized to above the reaction pressure. All reaction feed streams were measured by mass flow meters and independently controlled by a computer-automated valve control system.

[0102] The dual-reactor system is used in series. The first reactor is a continuous solution polymerization reactor consisting of a fully liquid, adiabatic, continuously stirred tank reactor (CSTR). All fresh solvent, monomer, comonomer, hydrogen, and catalyst components can be independently controlled. The total fresh feed stream (solvent, monomer, comonomer, and hydrogen) to the second reactor is temperature-controlled to maintain a single solution phase by passing the feed stream through a heat exchanger. All fresh feed to the second polymerization reactor is injected into the reactor from one location. The catalyst component is injected separately from the fresh feed into the second polymerization reactor. The main catalyst component feed is computer-controlled to maintain the reactor monomer conversion at a specified value. The cocatalyst component is fed based on its molar ratio with the main catalyst component. Mixing in the second reactor can be provided by a stirrer. The effluent from the first polymerization reactor (containing solvent, monomer, comonomer, hydrogen, catalyst component, and polymer) exits the first reactor loop and is added separately from the optional fresh feed and catalyst feed components to the second reactor.

[0103] The second reactor is a continuous solution polymerization reactor consisting of a liquid-filled, non-adiabatic isothermal circulating loop reactor simulating a deheated continuous stirred tank reactor (CSTR). All fresh solvent, monomer, comonomer, hydrogen, and catalyst components can be independently controlled. The total fresh feed stream (solvent, monomer, comonomer, and hydrogen) to the first reactor is temperature-controlled to maintain a single solution phase by passing the feed stream through a heat exchanger. The total fresh feed to the first polymerization reactor is injected into the reactor at two locations, with the reactor volume approximately equal between each injection point. The fresh feed is controlled by receiving half the total fresh feed mass flow rate at each injector. If additional fresh feed is present, the catalyst component is injected into the polymerization reactor separately from the fresh feed. The main catalyst component feed is computer-controlled to maintain the reactor monomer conversion at a specified value and produce a polymer with the desired MI, density, and melt strength. The cocatalyst component is fed based on its molar ratio to the main catalyst component. Immediately following the feed injection point of each first reactor, the feed stream is mixed with the contents of the circulating polymerization reactor using a static mixing element. The contents of the first reactor are continuously circulated through a heat exchanger, which is responsible for removing a significant portion of the heat of reaction, and the temperature on the coolant side is responsible for maintaining the isothermal reaction environment at the specified temperature. Circulation around the first reactor loop is provided by a pump.

[0104] The effluent from the second reactor enters a region where it is deactivated by adding a suitable reagent (water) and reacting with it. Antioxidant addition can also be carried out at the same point. After catalyst deactivation and the addition of additives, the reactor effluent enters a volatilization section where polymers are removed from the non-polymer stream. The separated polymer melt is granulated and collected. The non-polymer stream is separated by various devices through which most of the ethylene removed from the system is separated. Most of the solvent and unreacted comonomers are recycled back to the reactor after passing through a purification system. Small amounts of solvent and comonomers are removed from the process.

[0105] The reactor feed data stream corresponds to the values ​​used in Table 2. Presenting the data makes it easier to handle the complexities of the solvent recycling system and the reaction system as a once-through flow diagram.

[0106] Chain transfer constant calculation

[0107] The chain transfer constant was calculated using the Mayo equation shown in Equation 7, where Mn0 is Mn without any hydrogen added to the reactor, H2 and ethylene concentrations are liquid phase concentrations, and c CTHThis is the ratio of the hydrogenolysis rate constant to the growth rate constant. The reactor volume is 3.414 L, the liquid phase ethylene concentration is estimated to be 0.539 M, and the estimated hydrogen concentrations for 10 mmol, 20 mmol, 40 mmol, 80 mmol, and 160 mmol H2 are 1.17 mM, 2.31 mM, 4.53 mM, 8.74 mM, and 16.3 mM, respectively. For each hydrogen loading, the Mn value is calculated using Equation 8. The Solver feature in MS Excel is used to change c. CTH The value of Mn is determined so as to minimize the sum of the squared deviations of the calculated Mn value from the experimental Mn values ​​for all hydrogen loads.

[0108]

[0109] Example

[0110] One or more features of this disclosure are illustrated by the following embodiments:

[0111] The following catalysts are used in one or more embodiments described in more detail below:

[0112]

[0113]

[0114] Example 1: Preparation of compositions 1 to 8

[0115] The multi-peaked ethylene-based polymer compositions 1 to 8 described in one or more embodiments in detail are prepared by the methods described below and using the catalysts and reactors described below. The reactors and feed conditions for synthesizing composition 1 are provided in Table 1, the reactors and feed conditions for synthesizing composition 2 are provided in Table 2, and the reactors and feed conditions for synthesizing compositions 3-7 are provided in Table 3.

[0116] Table 1: Conditions for synthesizing composition 1 using reactor setup 1

[0117]

[0118]

[0119] Table 2: Conditions for synthesizing composition 2 using reactor setup 1

[0120]

[0121] Table 3: Conditions for synthesizing compositions 3 to 6 using reactor setting 2.

[0122]

[0123]

[0124] Example 2: Preparation of comparative compositions C1 to C3

[0125] Comparative compositions C1 to C3 were prepared by the methods described below and using the catalyst and reactor described below.

[0126] All raw materials (monomers and comonomers) and process solvents (narrow-boiling-range, high-purity isoparaffin solvent, Isopar-E) were purified using molecular sieves before being introduced into the reaction environment. Hydrogen was supplied pressurized at a high purity level without further purification. The monomer feed stream to the reactor was pressurized above the reaction pressure using a mechanical compressor. The solvent and comonomer feed streams were pressurized above the reaction pressure using pumps. Each catalyst component was manually diluted in batches with the purified solvent and pressurized above the reaction pressure. All reaction feed streams were measured using mass flow meters and independently controlled using a computer-automated valve control system. The reactor and feed conditions used for synthesizing comparative compositions C1 to C3 are provided in Table 5.

[0127] Table 4: Reactor and feed conditions for synthesizing comparative compositions C1 to C3 .

[0128]

[0129] Example 3: Comparative compositions C4 to C8

[0130] Comparative compositions C4 and C5 are ethylene-based polymers produced by high-pressure free radical polymerization. Comparative composition C6 is an ethylene-based polymer produced in a single reactor using a single catalyst. Comparative compositions C7 and C8 are bimodal ethylene-based polymers produced in a dual-reactor system, with a single catalyst in each reactor.

[0131] Example 4: Preparation of comparative compositions C9 to C19

[0132] Comparative compositions C9 to C19 were prepared by the methods described below and using the catalyst and reactor described below.

[0133] Table 5: Reactor and feed conditions for synthesizing comparative compositions C9 to C19 .

[0134]

[0135]

[0136] Table 6: Evaluation of catalysts A, C, D, E, H, and G in a semi-batch reactor

[0137]

[0138] Conditions: 160℃ operation: 320psi ethylene, 60g 1-octene, 0 H2, 1250mL Isopar E solvent. 190℃ operation: 410psi ethylene, 65g 1-octene, 0 H2, 1250mL Isopar E solvent. All operations: ethylene molar fraction in solution = 0.709.

[0139] The reactivity ratio r1 is the reactivity ratio of monomers inserted after ethylene, and it is calculated using the Mayo-Lewise equation:

[0140]

[0141] In Equation 9, r2 is the reactivity ratio of the monomer inserted after the comonomer (here, 1-octene), f1 is the molar fraction of ethylene in the feed, f2 is the molar fraction of the comonomer (1-octene) in the feed, and F1 is the molar fraction of ethylene in the polymer.

[0142]

[0143] In Equation 10, F2 is the mole fraction of 1-octene in the polymer. This value can be obtained experimentally through GPC analysis of the polymer.

[0144] The Mayo-Lewis equations can be solved using the GRG nonlinear solver available in Microsoft Excel to find the r1 and r2 values ​​that give the best fit.

[0145] Example 5: Analysis of compositions 1 to 6 and comparative compositions 1 to 19 .

[0146] In Example 5, the properties of multi-peak ethylene-based polymer compositions 1 to 6 and comparative compositions 1 to 19, as listed in Tables 8 to 10, were tested according to the test methods described herein.

[0147] Table 7: Analysis of compositions 1 to 6 and comparative compositions 1 to 19 .

[0148] *Values ​​from absolute GPC analysis

[0149] **Values ​​from routine GPC analysis

[0150] Table 8: Analysis of compositions 1 to 6 and comparative compositions 1 to 19 .

[0151]

[0152] Table 9: Analysis of compositions 1 to 6 and comparative compositions 1 to 19 .

[0153]

[0154]

[0155] Table 10: Constants for chain transfer to hydrogen (CH2) of the selected catalyst at 160 °C

[0156]

[0157] As shown in Tables 7 to 9, Comparative Examples C1 to C3 were produced using biphenylphenol (BPP) alone. Although the polymers produced had high vinyl content, the lack of the higher molecular weight component prepared by the second catalyst resulted in low melt strength.

[0158] Comparative Examples C16 to C19 were produced in a dual reactor configured in series using two BPP catalysts, A and C. The hydrogen levels used in the reactor with BPP catalyst C (0.43 mol%–1.33 mol%) were quite high. This H2 level limited the ability of the BPP catalyst to build molecular weights, as can be seen from the CDF LS 500,000 g / mol cutoff data, where these values ​​ranged from 2.12% to 5.18%.

[0159] Examples 1 to 6 of the present invention utilize two BPP catalysts in various reactor configurations, including single-reactor and dual-reactor series, wherein the reactors are selected from CSTR, loop reactor, and plug flow reactor types. The hydrogen levels used to produce the embodiments of the present invention are significantly lower than the hydrogen levels used to produce Comparative Examples 16 to 19.

[0160] For example, Example 2 of the present invention uses a hydrogen level of 0.03 mol% to 0.3 mol%. The lower hydrogen level allows the BPP catalyst C or D (depending on the examples of the present invention) to produce polymers with higher molecular weights. This is reflected in the CDF LS500,000 g / mol cutoff data, where these values ​​are in the range of 13% to 31%, significantly higher than in Examples 16 to 19 of the present invention, which use higher levels of hydrogen.

[0161] Furthermore, Examples 1 to 6 of the present invention have improved rheological properties, exhibiting a melt strength of up to 36 cN, while the melt strength of Comparative Examples 1 to 3 and 16 to 19 is no higher than 6.2 cN, and this value is achieved for a lower MI polymer (MI = 0.77 g / 10 min).

Claims

1. A method for preparing a multimodal ethylene-based copolymer, the method comprising: Ethylene, at least one olefin monomer, at least a first catalyst system and less than 0.3 mol% of hydrogen are added to a solution polymerization reactor at a reactor temperature of 150°C or higher to produce an effluent feed, wherein the mol% of hydrogen is based on the number of moles of ethylene in the feed. The effluent feed and the second catalyst system are fed into a second reactor where there is no fresh feed and no hydrogen. in: The first catalyst system comprises a first main catalyst and a first activator; and the second catalyst system comprises a second main catalyst and an optional second activator; At least one of the first catalyst system and the second catalyst system has a chain transfer constant of 0.005 to 1.0, and The multi-peaked ethylene-based copolymer comprises a high molecular weight fraction of 8% to 50% based on the total percentage of the multi-peaked ethylene-based copolymer, the high molecular weight fraction being calculated by measuring the area fraction of a molecular weight chromatogram obtained by measuring the absolute molecular weight obtained by low-angle light scattering greater than 500,000 g / mol.

2. The method of claim 1, wherein one of the first catalyst system and the second catalyst system is capable of producing a polymer with a native molecular weight greater than 100,000 g / mol, wherein the native molecular weight of the polymer is measured in the presence of 1250 g ISOPAR-E in a single 1-gallon reactor containing 320 psi ethylene pressure, 60 g 1-octene, and 0 H2, and at a reactor temperature of at least 150°C.

3. The method of claim 2, wherein the other of the first catalyst system and the second catalyst system is capable of producing a polymer with a native molecular weight of less than 150,000 g / mol, wherein the native molecular weight of the polymer is measured in the presence of 1250 g ISOPAR-E in a single 1-gallon reactor containing 320 psi of ethylene, 60 g of 1-octene, and 0 H2, and at a reactor temperature of at least 160 °C.

4. The method of claim 1, wherein the first catalyst system is capable of producing a first polymer having a native molecular weight, and the second catalyst system is capable of producing a second polymer having a native molecular weight that differs from the native molecular weight of the first polymer by at least 80,000 g / mol.

5. The method according to any one of the preceding claims, wherein the solution polymerization reactor is a continuous stirred tank reactor, a loop reactor, or a plug flow reactor.

6. The method according to any one of the preceding claims, wherein the second polymerization reactor is a non-stirred reactor.

7. The method according to claim 4, wherein the unstirred reactor is a plug flow reactor.

8. The method according to any one of the preceding claims, wherein at least one of the first catalyst and the second main catalyst has a polymerization reactivity ratio of less than 20, wherein the polymerization reactivity ratio of the catalyst is measured in the presence of 1250 g ISOPAR-E in a single 1-gallon reactor containing 60 g of 1-octene and only the catalyst system in the presence of a solution containing 0.709 molar fraction of ethylene, and at a reactor temperature of at least 150°C.

9. The method according to any one of the preceding claims, wherein the multimodal ethylene-based copolymer further comprises a low molecular weight fraction of greater than or equal to 50% based on the total percentage of the multimodal ethylene-based copolymer, the low molecular weight fraction being calculated by measuring the area fraction of a molecular weight chromatogram obtained by measuring the absolute molecular weight obtained by low-angle light scattering of less than 500,000 g / mol.

10. The method according to any one of the preceding claims, wherein the multimodal ethylene-based copolymer further comprises a high molecular weight fraction of 10% to 50% based on the total percentage of the multimodal ethylene-based copolymer, the high molecular weight fraction being calculated by measuring the area fraction of a molecular weight chromatogram obtained by measuring the absolute molecular weight obtained by low-angle light scattering of greater than 500,000 g / mol.

11. The method according to any one of the preceding claims, wherein the multimodal ethylene-based copolymer further comprises a high molecular weight fraction of 20% to 50% based on the total percentage of the multimodal ethylene-based copolymer, the high molecular weight fraction being calculated by measuring the area fraction of a molecular weight chromatogram obtained by measuring the absolute molecular weight scattered by low-angle light greater than 500,000.

12. The method according to any one of the preceding claims, wherein the multimodal ethylene-based copolymer has a density of 0.900 g / cc to 0.940 g / cc as measured according to ASTM D792.

13. The method according to any one of the preceding claims, wherein the multimodal ethylene-based copolymer has a melt strength of at least 5 cN and a melt index (I2) of at least 0.5 g / 10 min as measured according to ASTM 1238 at 2.16 kg and 190 °C.

14. The method according to any one of the preceding claims, wherein the multimodal ethylene-based copolymer has a melt strength (MS) satisfying the following equation: Where x equals 15, y equals 1, and I2 is the melt index of the copolymer as measured according to ASTM 1238 at 2.16 kg and 190 °C.

15. The method according to any one of the preceding claims, wherein V, as determined by dynamic mechanical analysis, 0.1 / V 100 The value is greater than 10.

16. The method according to any one of the preceding claims, wherein the temperature of the first reactor is 160°C to 200°C.

17. The method according to any one of the preceding claims, wherein the first main catalyst is selected from one of the following: 。 18. The method according to any one of the preceding claims, wherein the second main catalyst is selected from one of the following:

19. The method according to any one of the preceding claims, wherein the method further comprises a third catalyst system.

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