Direct ethylene injection for dual reactor solution processes.

Abstract

An embodiment of the present process for producing an ethylene-based polymer comprising a first polymer fraction and a second polymer fraction comprises a step of reacting ethylene monomer and optionally a C3-C 12 The method includes reacting an α-olefin comonomer in a first solvent in the presence of a first catalyst in a first solution polymerization reactor to produce a first polymer fraction. The method further comprises reacting the first polymer fraction, a second catalyst, and ethylene monomer, optionally C3 to C6. 12 The method may further include reacting a second feed comprising an α-olefin comonomer, and optionally hydrogen, in a second solution polymerization reactor to produce a second polymer fraction. The second feed may be substantially free of solvent. The method may further include producing an effluent from the second solution polymerization reactor, the effluent comprising an ethylene-based polymer having the first polymer fraction and the second polymer fraction.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 478,275, filed January 3, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] This specification relates generally to ethylene-based polymers, and more particularly to an improved polymerization process that produces low melt index polymers. [Background technology]

[0003] Solution polymerization processes for producing ethylene-based polymers (e.g., LLDPE) utilize hydrocarbon solvents in their reactors to carry out a single, liquid-phase polymerization reaction. The solvent serves to dissolve the polymer and ethylene gas and provide a single, liquid-phase environment for the polymerization reaction while removing a portion of the heat of reaction. Because plant throughput is limited by the total solvent devolatilization capacity of the back-end equipment, the polymer concentration exiting the reactor section, or, viewed another way, the amount of solvent used to make each product, determines the maximum total polymer production rate. Therefore, any process improvement that reduces solvent usage will help increase overall facility capacity.

[0004] Traditionally, to ensure consistent reactor feed, ethylene monomer is dissolved in a solvent and comonomer and fed as a single liquid-phase feed stream. However, a single liquid-phase feed requires a large amount of solvent to completely dissolve the fresh ethylene. This limits the polymer concentration in the reactor, thereby limiting plant capacity. In a multiple reactor configuration, this single liquid-phase stream is traditionally fed to each reactor.

[0005] Excellent dart properties can be obtained by producing very low melt index (MI) and / or high molecular weight (Mw) components in the first reactor of a multiple reactor configuration. However, it may not be feasible to process such polymers in a dual loop reactor because the low MI and / or high Mw components may result in excessively high viscosities in the loop reactor.

[0006] In a continuously stirred tank reactor (CSTR) / loop dual reactor, very low MI and / or very high Mw components can be produced because the CSTR operates at a much lower polymer percentage and a higher solvent percentage. However, because the CSTR operates at a higher solvent percentage, such a process will result in a lower overall polymer percentage unless the solvent is removed before feeding the polymer to the second reactor. This low overall polymer percentage results in a relatively low plant production rate.

[0007] Thus, there is a continuing need for improved polymerization processes capable of producing ethylene-based polymers at high rates, including ethylene-based polymers with very low MI and / or high molecular weight. Summary of the Invention

[0008] Embodiments of the present disclosure fulfill this need for improved production of low melt index ethylene-based polymers by applying a direct ethylene injection system to provide a substantially solvent-free ethylene feed to the second reactor. This absence of solvent in the second reactor feed is believed to enable the production of high Mw and low melt index polymers in the first reactor without being limited by viscosity. The absence of solvent in the second reactor feed increases overall polymer concentration and reduces overall solvent loading, which in turn helps increase the production rate of existing dual reactor polymerization systems.

[0009] According to one embodiment, there is provided a method for producing an ethylene-based polymer comprising a first polymer fraction and a second polymer fraction. The method comprises: 12 The method includes reacting an α-olefin comonomer in a first solvent in the presence of a first catalyst in a first solution polymerization reactor to produce a first polymer fraction. The method further comprises reacting the first polymer fraction, a second catalyst, and ethylene monomer, optionally C3 to C6. 12 The method further comprises reacting a second feed comprising an α-olefin comonomer, and optionally hydrogen, in a second solution polymerization reactor to produce a second polymer fraction, the second feed being substantially free of solvent. An effluent from the second solution polymerization reactor is then produced, the effluent comprising an ethylene-based polymer having the first and second polymer fractions.

[0010] Additional features and advantages are set forth in the following Detailed Description, and in part will be readily apparent to those skilled in the art from that description or will be recognized by practicing the embodiments described herein, including the drawings, the following Detailed Description, and the claims. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a series of inventive dual reactor polymerization processes, in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Specific embodiments of the present application will now be described. However, this disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth in this disclosure. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present subject matter to those skilled in the art.

[0013] definition The term "polymer" refers to a polymeric compound prepared by polymerizing monomers (whether of the same or different types). Thus, the generic term polymer encompasses the term "homopolymer," which is typically used to refer to a polymer prepared from only one type of monomer, as well as "copolymer," which refers to a polymer prepared from two or more different types of monomers. As used herein, the term "interpolymer" refers to a polymer prepared by polymerization of at least two different types of monomers. Thus, the generic term "interpolymer" includes copolymers and polymers prepared from three or more different types of monomers, such as terpolymers.

[0014] "Polyethylene" or "ethylene-based polymer" means a polymer containing greater than 50 mole percent units derived from ethylene monomers. This includes polyethylene homopolymers or copolymers (meaning units derived from ethylene and one or more comonomers). Comonomers may include olefinic comonomers as well as polar comonomers. Common forms of polyethylene known in the art include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), single-site catalyzed linear low density polyethylene (m-LLDPE), including both linear and substantially linear low density resins, medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0015] The term "LLDPE" includes resins made using Ziegler-Natta catalyst systems, as well as resins made using single-site catalysts, including, but not limited to, bismetallocene catalysts (sometimes referred to as "m-LLDPE") and constrained geometry catalysts, and resins made using post-metallocene molecular catalysts. LLDPE includes linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains less long chain branching than LDPE and includes substantially linear ethylene polymers, as further defined in U.S. Pat. Nos. 5,272,236, 5,278,272, 5,582,923, and 5,733,155; homogeneously branched linear ethylene polymer compositions such as those in U.S. Pat. No. 3,645,992; heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Pat. No. 4,076,698; and / or blends thereof (such as those disclosed in U.S. Pat. Nos. 3,914,342 or 5,854,045).

[0016] The terms "comprising," "including," "having," and their derivatives are not intended to exclude the presence of any additional component, step, or procedure, whether or not it is specifically disclosed. For the avoidance of doubt, all compositions claimed through the use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any succeeding description any other component, step, or procedure, except those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically delineated or listed.

[0017] Embodiment Embodiments of the present disclosure are directed to a method of producing an ethylene-based polymer comprising a first polymer fraction and a second polymer fraction, wherein the first polymer fraction and the second polymer fraction have a weight average molecular weight (Mw), a melt index (I2), a density, a melt index ratio (I 21 The resulting polymer may have optimal properties, such as olefin copolymerization (e.g., olefin copolymerization), olefin copolymerization (e.g., olefin copolymerization), and molecular weight distribution, which can be achieved at acceptable production rates by eliminating the solvent feed to the second reactor in a two-reactor system.

[0018] First Supply 1, the process can include introducing a first feed 110 into a first solution polymerization reactor 120. The first feed comprises a first ethylene monomer and optionally a C3-C6 olefin in a first solvent. 12 The first feed 110 may comprise a single-phase feed containing the monomer completely dissolved in a solvent, or a two-phase feed containing the monomer dissolved in a solvent and a gas phase.

[0019] The ratio of (solvent + comonomer) to ethylene in first feed 110 can be from 5 to 9, e.g., from 5 to 8, from 5 to 7, from 5 to 6, from 6 to 9, from 6 to 8, from 7 to 9, from 7 to 8, or any subset thereof. In embodiments where first solution polymerization reactor 120 is a loop reactor, the ratio of (solvent + comonomer) to ethylene in first feed 110 (S / E) can be from 5 to 9, from 5 to 8, e.g., from 5 to 7, from 5 to 6, from 6 to 8, from 6 to 7, or from 7 to 8. In embodiments where first solution polymerization reactor 120 is a CSTR, the ratio of (solvent + comonomer) to ethylene in first feed 110 can be from 5 to 9, e.g., from 5 to 8, from 7 to 9, from 7 to 8, or any subset thereof.

[0020] The method comprises: 12The method may include reacting an α-olefin comonomer in a first solvent in the presence of a first catalyst in a first solution polymerization reactor 120 to produce a first polymer fraction. At least 80 wt%, at least 90 wt%, at least 99 wt%, or even at least 99.9 wt% of the polymerizable compounds contacted with the first catalyst in the presence of ethylene monomer are ethylene monomer and C3-C6 12 It may be an alpha-olefin comonomer.

[0021] C3~C 12 α-olefin comonomers can include, by way of example and not limitation, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-decene, and 1-octene, as well as other monomer types such as styrene, alkyl-substituted styrenes, vinylbenzocyclobutane, dienes such as 1,4-hexadiene, 1,7-octadiene, 1,9-decadiene, and ethylidene norbornene, and cycloalkenes (e.g., cyclopentene, cyclohexene, and cyclooctene).

[0022] Ethylene monomer and C3-C6 monomers fed to the first reactor 12 The ratio of α-olefin comonomer is 0 to 49 mol% C3 to C 12 C3 to C6 α-olefin comonomers, for example, 0 to 40 mol%, 0 to 30 mol%, 0 to 20 mol%, 0 to 10 mol%, 0 to 5 mol%, 0 to 1 mol%, 0 to 0.001 mol%, 1 to 49 mol%, 1 to 40 mol%, 1 to 30 mol%, 1 to 20 mol%, 1 to 10 mol%, 10 to 49 mol%, 10 to 40 mol%, 10 to 30 mol%, 10 to 20 mol%, 20 to 49 mol%, 20 to 30 mol%, or any subset thereof 12 It may be an alpha-olefin comonomer.

[0023] A variety of hydrocarbon solvents are contemplated as suitable for use as the first solvent. For example, in one or more embodiments, the hydrocarbon solvent may include a paraffinic, isoparaffinic, naphthenic, aromatic hydrocarbon solvent, aliphatic hydrocarbon solvent, or mixtures thereof. Specific solvents may include cyclohexane, hexane, heptane, octane, nonane, isooctane, ethylbenzene, isopentane, toluene, or methyl isobutyl ketone (MBK).

[0024] First Reactor and Reaction a first ethylene monomer and optionally a C3-C 12 The reaction of the α-olefin comonomer may occur in first solution polymerization reactor 120. First solution polymerization reactor 120 may be any solution reactor, such as at least one continuous stirred tank reactor (CSTR), at least one loop reactor, at least one tubular reactor, or a combination thereof.

[0025] The ratio of (solvent + comonomer) to ethylene in the first solution polymerization reactor 120 can be from 5 to 9, e.g., from 5 to 8, from 5 to 7, from 5 to 6, from 6 to 9, from 6 to 8, from 7 to 9, from 7 to 8, or any subset thereof. In embodiments where the first solution polymerization reactor 120 is a loop reactor, the ratio of (solvent + comonomer) to ethylene in the first solution polymerization reactor 120 can be from 5 to 9, from 5 to 8, e.g., from 5 to 7, from 5 to 6, from 6 to 8, from 6 to 7, or from 7 to 8. In embodiments where the first solution polymerization reactor 120 is a CSTR, the ratio of (solvent + comonomer) to ethylene in the first solution polymerization reactor 120 can be from 5 to 9, e.g., from 5 to 8, from 7 to 9, from 7 to 8, or any subset thereof.

[0026] The first catalyst may include Ziegler-Natta catalyst systems, including, but not limited to, bis-metallocene catalysts, constrained geometry catalysts, post-metallocene catalysts, molecular catalysts, bis-phenyl-phenoxy catalysts, and heterogeneous Ziegler-Natta catalysts, single-site catalysts, and multi-site catalysts. For example, the first catalyst may include at least one molecular catalyst, at least one heterogeneous Ziegler-Natta catalyst, at least one metallocene catalyst, or a combination thereof. The at least one Ziegler-Natta catalyst may include titanium chloride, magnesium chloride, or both, and a support material such as amorphous silica. Exemplary catalysts are listed in Table 5.

[0027] The first solution polymerization reactor can operate at a pressure from 10 bar to 450 bar. For example, the first solution polymerization reactor can operate at a pressure from 10 bar to 45 bar, from 30 bar to 450 bar, from 13 bar to 30 bar, or any subset thereof.

[0028] The first solution polymerization reactor can have an outlet temperature of at least 110° C. For example, the first solution polymerization reactor can have an outlet temperature of at least 120° C., at least 130° C., at least 140° C., at least 150° C., at least 160° C., at least 170° C., at least 180° C., at least 190° C., at least 200° C., 110° C. to 250° C., 120° C. to 250° C., 130° C. to 250° C., 140° C. to 250° C., 150° C. to 250° C., 160° C. to 250° C., 180° C. to 250° C., 110° C. to 200° C., or any subset thereof.

[0029] Ethylene monomer alone or C3 to C 12 At least 70%, at least 75%, at least 80%, at least 85%, or even at least 88% by weight of the ethylene monomer may be polymerized in combination with an α-olefin comonomer to form the first polymer fraction.

[0030] First polymer fraction a first ethylene monomer and optionally a C3-C olefin in the presence of a first catalyst in a first solvent; 12 The first polymer fraction can be produced by reacting an α-olefin comonomer. The first polymer fraction can have a weight average molecular weight (Mw) of at least 30,000 g / mol. For example, the first polymer fraction can have a weight average molecular weight (Mw) of at least 40,000 g / mol, at least 50,000 g / mol, at least 60,000 g / mol, at least 75,000 g / mol, at least 100,000 g / mol, at least 200,000 g / mol, at least 300,000 g / mol, at least 400,000 g / mol, at least 500,000 g / mol, 30,000 to 800,000 g / mol, 50,000 to 800,000 g / mol, or 100,000 to 1000,000 g / mol. The polymeric compound may have a Mw of 800,000 g / mol, 75,000 to 800,000 g / mol, 100,000 to 800,000 g / mol, 250,000 to 800,000 g / mol, 500,000 to 800,000 g / mol, 30,000 to 650,000 g / mol, 30,000 to 500,000 g / mol, 50,000 to 650,000 g / mol, 100,000 to 500,000 g / mol, or any subset thereof. The Mw of the polymeric compound can be determined by gel permeation chromatography, as described below.

[0031] The first polymer fraction can have a molecular weight distribution (Mw / Mn = MWD) of from 2 to 5. For example, the first polymer fraction can have an MWD of from 2 to 4.5, from 2 to 4, from 2 to 3, from 2 to 2.5, from 2.5 to 5, from 2.5 to 4.5, from 2.5 to 4, from 2.5 to 3, from 3 to 5, from 3 to 4.5, or any subset thereof.

[0032] The first polymer fraction may have a melt index (I2) of at least 0.001 g / 10 min. For example, the melt index (I2) of the first polymer fraction may be at least 0.01 g / 10 min, at least 0.1 g / 10 min, at least 1 g / 10 min, at least 2.01 g / 10 min, 0.001 to 50 g / 10 min, 0.001 to 25 g / 10 min, 0.001 to 10 g / 10 min, 0.001 to 5 g / 10 min, 0.001 to 3 g / 10 min, 0.001 to 1 g / 10 min, or 0.001 to 0.5 g / 10 min. The melt index of the first polymer fraction can be determined in accordance with ASTM D1238, as described below.

[0033] The first polymer fraction is 0.880 to 0.955 g / cm 3 For example, the first polymer fraction may have a density of 0.880 to 0.950 g / cm 3 , 0.880~0.945g / cm 3 , 0.880~0.940g / cm 3 , 0.880~0.935g / cm 3 , 0.880~0.930g / cm 3 , 0.880~0.925g / cm 3 , 0.880~0.920g / cm 3 , 0.880~0.915g / cm 3 , 0.880~0.910g / cm 3 , 0.880~0.905g / cm 3 , 0.890~0.955g / cm 3 , 0.900~0.955g / cm 3 , 0.910~0.955g / cm 3 , 0.920~0.955g / cm 3 , 0.930~0.955g / cm 3, 0.940~0.955g / cm 3 , 0.890~0.940g / cm 3 , 0.900~0.930g / cm 3 , 0.910~0.920g / cm 3 , or any subset thereof.

[0034] The first polymer fraction can be contained within the first polymer solution effluent 130. The polymer solids content of the first polymer solution effluent 130 can be at least 10 wt %. For example, the polymer solids content of the first polymer solution effluent 130 can be 10-22 wt % solids, 10-20 wt %, 10-16 wt %, 10-14 wt %, 10-13 wt %, 10-12 wt %, 18-20 wt %, or any subset thereof. The amount of polymer solids in the first polymer solution effluent 130 can be determined, at least in part, by the choice of reactor. Thus, if the first solution polymerization reactor 120 is a CSTR, the polymer solids content of the first polymer solution effluent 130 can be 10-16 wt %, 10-14 wt %, 10-13 wt %, 11-13 wt %, 10-12.9 wt %, or any subset thereof. When first solution polymerization reactor 120 is a loop reactor, the polymer solids content of first polymer solution effluent 130 can be 18-20 wt %, or 18-19 wt % polymer, or any subset thereof.

[0035] Secondary Supply The method comprises reacting a first polymer fraction, a second catalyst, and ethylene monomer, optionally C3 to C6 12 The method may further include reacting a second feed 140 comprising an α-olefin comonomer, and optionally hydrogen, in a second solution polymerization reactor 150 to produce a second polymer fraction. The second polymer fraction may be contained in an effluent 160.

[0036] The second feed 140 may be single-phase. For example, the second feed 140 may comprise ethylene monomer and optionally C3-C6 12It may be in the gas phase or supercritical phase containing the α-olefin comonomer.

[0037] The second feed 140 is ethylene monomer, optionally C3 to C6 12 For example, the second feed 140 may comprise at least 50 wt.%, at least 75 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, or even at least 99.9 wt.% ethylene monomer, C3-C6 12 It may include the combined weight of the α-olefin comonomer and hydrogen.

[0038] Second feed 140 may be substantially free of solvent. For example, second feed 140 may contain less than 0.1 wt. %, less than 0.01 wt. %, less than 0.001 wt. %, less than 0.0001 wt. %, or even 0 wt. % solvent. It should be understood that second feed 140 may refer to all compounds fed to the inlet of second solution polymerization reactor 150. However, the second feed does not include solvent that may pass through the reactor pump, such as through the pump seal.

[0039] The second feed 140 is C3 to C 12 It may be substantially free of comonomers, such as α-olefin comonomers. For example, second feed 140 may contain less than 5 wt.%, less than 1 wt.%, less than 0.1 wt.%, less than 0.01 wt.%, less than 0.001 wt.%, less than 0.0001 wt.%, or even 0 wt.% comonomers.

[0040] Ethylene monomer and C3 to C6 monomers fed to the second solution polymerization reactor 150 12 The ratio of α-olefin comonomer is 0 to 49 mol% C3 to C 12C3 to C6 α-olefin comonomers, for example, 0 to 40 mol%, 0 to 30 mol%, 0 to 20 mol%, 0 to 10 mol%, 0 to 5 mol%, 0 to 1 mol%, 0 to 0.001 mol%, 1 to 49 mol%, 1 to 40 mol%, 1 to 30 mol%, 1 to 20 mol%, 1 to 10 mol%, 10 to 49 mol%, 10 to 40 mol%, 10 to 30 mol%, 10 to 20 mol%, 20 to 49 mol%, 20 to 30 mol%, or any subset thereof 12 It may be an alpha-olefin comonomer.

[0041] The second feed 140 can include less than 1.5 mole percent (mol%) hydrogen. For example, the second feed can include 0.5-1.5 mol%, 0.5-1.25 mol%, 0.5-1.0 mol%, 0.75-1.5 mol%, 0.75-1.25 mol%, 0.75-1.0 mol%, less than 1.25 mol%, less than 1.0 mol%, less than 0.75 mol%, less than 0.5 mol%, or even less than 0.1 mol% hydrogen.

[0042] Second Reactor and Reaction The method comprises reacting a first polymer fraction, a second catalyst, and ethylene monomer, optionally C3 to C6 12 This may include reacting a second feed 140 comprising an α-olefin comonomer, and optionally hydrogen, in a second solution polymerization reactor 150 .

[0043] The second catalyst may include Ziegler-Natta catalyst systems, including, but not limited to, bis-metallocene catalysts, constrained geometry catalysts, post-metallocene catalysts, molecular catalysts, bis-phenyl-phenoxy catalysts, and heterogeneous Ziegler-Natta catalysts, single-site catalysts, and multi-site catalysts. For example, the second catalyst may include at least one molecular catalyst, at least one heterogeneous Ziegler-Natta catalyst, at least one metallocene catalyst, or a combination thereof. The at least one Ziegler-Natta catalyst may include titanium chloride, magnesium chloride, or both, and a support material such as amorphous silica. The at least one metallocene catalyst may include an organic ligand such as cyclopentadienyl, chlorine, and a metal such as Ti, Zn, or Hf.

[0044] In some embodiments, the first catalyst and the second catalyst may have different compositions. For example, the first catalyst may include a homogeneous molecular catalyst and one or more co-catalysts. The second catalyst may include a heterogeneous Ziegler-Natta catalyst including titanium chloride.

[0045] The second solution polymerization reactor 150 can include at least one continuous stirred tank reactor (CSTR), at least one loop reactor, at least one tubular reactor, or a combination thereof. In some embodiments, the second solution polymerization reactor includes a loop reactor. The second solution polymerization reactor 150 can operate at a pressure from 10 bar to 450 bar. For example, the second solution polymerization reactor 150 can operate at a pressure from 10 bar to 45 bar, from 30 bar to 450 bar, from 13 bar to 30 bar, or any subset thereof. The feed temperature of the second solution polymerization reactor can be maintained below 45°C.

[0046] The second solution polymerization reactor 150 can reach an outlet temperature of at least 110° C. For example, the second solution polymerization reactor 150 can reach an outlet temperature of at least 110° C., at least 120° C., at least 130° C., at least 140° C., at least 150° C., at least 160° C., at least 170° C., at least 180° C., at least 190° C., or at least 195° C., 110° C. to 225° C., 150° C. to 225° C., 160° C. to 225° C., 180° C. to 225° C., 190° C. to 225° C., 195° C. to 225° C., 150° C. to 200° C., 160° C. to 200° C., 170° C. to 200° C., or 180° C. to 200° C.

[0047] According to some embodiments, the only solvent entering second solution polymerization reactor 150 may be that which is in solution with the first polymer fraction. Specifically, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, at least 99.9 wt.%, at least 99.99 wt.%, at least 99.999 wt.%, or even at least 100 wt.% of the solvent entering second solution polymerization reactor 150 may be that which was present in first solution polymerization reactor 120.

[0048] It should be appreciated that in some embodiments, a relatively small amount of solvent may be fed to second solution polymerization reactor 150. In such embodiments, the solvent may be provided to second solution polymerization reactor 150 separate from second feed 140, e.g., by / through a pump. This allows the solvent to be fed such that, overall, excluding that provided by the effluent from first solution polymerization reactor 120, the ratio of (solvent+comonomer) to ethylene is less than 0.3, less than 0.25, less than 0.2, less than 0.1, less than 0.01, less than 0.001, less than 0.00001, between 0.001 and 0.3, between 0.001 and 0.2, between 0.01 and 0.3, between 0.01 and 0.2, between 0.1 and 0.3, between 0.1 and 0.2, between 0.2 and 0.3, or any subset thereof.

[0049] Second polymer fraction A second polymer fraction can be produced by reacting the first polymer fraction, the second catalyst, and the second feed in the second solution polymerization reactor 150. It should be understood that the second polymer fraction can be in solution or otherwise mixed with the first polymer fraction.

[0050] The second polymer fraction may have a molecular weight of 5,000 g / mol to 200,000 g / mol, for example, 10,000 g / mol to 200,000 g / mol, 25,000 g / mol to 200,000 g / mol, 50,000 g / mol to 200,000 g / mol, 75,000 g / mol to 200,000 g / mol, 100,000 g / mol to 200,000 g / mol, 150,000 g / mol to 200,000 g / mol, The polymer may have a weight average molecular weight (Mw) of from 5,000 g / mol, 5,000 g / mol to 150,000 g / mol, from 5,000 g / mol to 100,000 g / mol, from 5,000 g / mol to 75,000 g / mol, from 5,000 g / mol to 50,000 g / mol, from 25,000 g / mol to 175,000 g / mol, from 50,000 g / mol to 150,000 g / mol, or any subset thereof.

[0051] The second polymer fraction can have a molecular weight distribution (MWD) of from 2.0 to 5.0, such as from 2.0 to 4.0, from 2.0 to 3.0, from 3.0 to 5.0, from 4.0 to 5.0, or any subset thereof.

[0052] The second polymer fraction can have a density of 0.900 g / cc to 0.980 g / cc. For example, the second polymer fraction can have a density of 0.925 g / cc to 0.980 g / cc, 0.950 g / cc to 0.980 g / cc, 0.900 g / cc to 0.950 g / cc, 0.900 g / cc to 0.925 g / cc, 0.925 g / cc to 0.965 g / cc, or any subset thereof.

[0053] Third Reactor The systems and methods of the present disclosure may include additional polymerization reactors downstream of the first solution polymerization reactor 120 and the second solution polymerization reactor 150. These reactors may be loop reactors, continuous stirred tank reactors, pipe flow reactors, tubular reactors, or combinations thereof. For example, the systems and methods of the present disclosure may include a third solution polymerization reactor downstream of the second solution polymerization reactor 150. The third reactor may include a tubular reactor, such as a plug flow reactor.

[0054] The primary feed to the third solution polymerization reactor may be the effluent 160 from the second solution polymerization reactor. In some embodiments, no feed may be provided to the third reactor other than the effluent 160 from the second solution polymerization reactor 150. In such embodiments, the third reactor provides space for the reaction initiated in the second solution polymerization reactor 150 to continue, effectively increasing its residence time. In such embodiments, a catalyst deactivator may not be introduced after the second solution polymerization reactor 150.

[0055] In an alternative embodiment, a catalyst, such as the second catalyst or a separate third catalyst, may be provided to the third reactor, but no additional monomer may be provided. In yet another embodiment, the process of the present disclosure comprises reacting the first polymer fraction and the second polymer fraction with a third catalyst and ethylene monomer, optionally C3 to C6, in a third solution polymerization reactor. 12 and contacting the polymer with a third feed comprising an α-olefin comonomer, and optionally hydrogen, to produce a third polymer fraction.

[0056] The outlet temperature of the third reactor can be at least 110°C, at least 120°C, at least 130°C, at least 140°C, at least 150°C, at least 160°C, at least 170, 180°C, at least 190°C, at least 200°C, 110°C to 220°C, 160°C to 220°C, 180 to 220°C, 190 to 210°C, 200 to 210°C, or any subset thereof. The outlet temperature of the third reactor can be higher than the outlet temperature of the second solution polymerization reactor 150 by at least 5°C, at least 10°C, 0 to 20°C, 5 to 15°C, or any subset thereof.

[0057] In some embodiments, substantially no additional solvent is provided to the third reactor. Specifically, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, at least 99.9 wt.%, at least 99.99 wt.%, at least 99.999 wt.%, or even 100 wt.% of the solvent entering the third polymerization reactor may be that which was present in the second polymerization reactor.

[0058] A mixer may be provided downstream of the second or third reactor. The mixer may be any mixer suitable for mixing polymers, such as an extruder. The mixer introduces a catalyst kill agent into the polymer.

[0059] Ethylene-based polymers The method may further include producing an effluent 160 from second solution polymerization reactor 150. Effluent 160 may include an ethylene-based polymer having a first polymer fraction and a second polymer fraction.

[0060] In embodiments having a third solution polymerization reactor, the method may further include producing an effluent from the third solution polymerization reactor. In such embodiments, the effluent may include an ethylene-based polymer having a first polymer fraction and a second polymer fraction.

[0061] The ethylene-based polymer may have a melt index (I2) of 0.1 to 100.0 g / 10 min. For example, the ethylene-based polymer may have a melt index (I2) of 0.1 to 90.0 g / 10 min, 0.1 to 75 g / 10 min, 0.1 to 50 g / 10 min, 0.1 to 25 g / 10 min, 0.1 to 10 g / 10 min, 0.1 to 2 g / 10 min, 0.1 to 1 g / 10 min, 0.1 to 0.9 g / 10 min, 0.1 to 0.8 g / 10 min, 0.25 to 100 g / 10 min, 0.25 to 50 g / 10 min, 0.25 to 25 g / 10 min, / 10 min, 0.25 to 10 g / 10 min, 0.25 to 2 g / 10 min, 0.25 to 1 g / 10 min, 0.25 to 0.8 g / 10 min, 0.7 to 100 g / 10 min, 0.7 to 25 g / 10 min, 0.7 to 10 g / 10 min, 0.7 to 1 g / 10 min, 0.7 to 0.8 g / 10 min, 0.7 to 0.76, or any subset thereof. As described below, melt index (I2) can be measured according to standard test method ASTM D 1238.

[0062] The ethylene-based polymer can have a density from 0.900 to 0.975 g / cc. For example, the ethylene-based polymer can have a density from 0.925 to 0.975 g / cc, 0.950 to 0.975 g / cc, 0.900 to 9.950 g / cc, 0.900 to 0.925 g / cc, or any subset thereof.

[0063] Ethylene-based polymers have a melt index ratio (I 21 For example, the ethylene-based polymer may have an I ratio of 20 to 400, 20 to 300, 20 to 250, 20 to 200, 20 to 150, 20 to 100, 20 to 75, 20 to 50, 30 to 500, 30 to 350, 30 to 250, 30 to 200, 30 to 150, 30 to 100, 30 to 75, 40 to 500, 40 to 250, 40 to 200, 40 to 100, 60 to 500, 60 to 200, 60 to 150, 60 to 100, 80 to 500, 80 to 250, 80 to 200, 80 to 150, or any subset thereof. 21 As described below, the melt index (I / and I 21) can be measured according to standard test method ASTM D 1238. Without being limited by theory, I 21 The ratio / I2 indicates the processability of the polymer, with an increasing number making it easier to process.

[0064] Ethylene-based polymers have a melt index ratio (I 10 For example, the ethylene-based polymer may have a melt index ratio (I / I2) of from 5.5 to 25, from 5.5 to 20, from 5.5 to 15, from 5.5 to 10, from 10 to 30, from 10 to 20, or any subset thereof. 10 As described below, the melt index (I2 and I 10 ) can be measured according to standard test method ASTM D 1238.

[0065] The ethylene-based polymer can have a molecular weight distribution MWD from 2.5 to 40. For example, the ethylene-based polymer can have an MWD from 2.5 to 30, 2.5 to 25, 2.5 to 20, 2.5 to 15, 2.5 to 10, 2.5 to 8, 5 to 30, 5 to 25, 5 to 20, 5 to 15, 6.8 to 10, 6.8 to 9, 6.8 to 8.7, 7 to 11, 7 to 9, or any subset thereof.

[0066] Test Method density Samples for density measurement are prepared according to ASTM D1928. The polymer sample is pressed at 190°C and 30,000 psi for 3 minutes, then at 21°C and 207 MPa for 1 minute. Measurements are made within 1 hour of pressing the sample using ASTM D792, Method B.

[0067] Melt Index (I2) Melt index, or I2, (grams / 10 minutes or dg / minute) is measured according to ASTM D1238, Condition 190°C / 2.16 kg, Procedure B.

[0068] Melt index (I 10 ) Melt index, or I 10, (grams / 10 minutes or dg / minute) is measured according to ASTM D1238, condition 190°C / 10 kg, procedure B.

[0069] Melt index (I 21 ) Melt index, or I 21 , (grams / 10 minutes or dg / minute) is measured according to ASTM D1238, Condition 190°C / 21.6 kg, Procedure B.

[0070] Number and weight average molecular weight (Mn) Mn and Mw are measured by gel permeation chromatography (GPC).

[0071] Gel Permeation Chromatography (GPC) GPC was performed on a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5). The autosampler oven compartment was set at 160°C, and the column compartment was set at 150°C. The columns used were four "Mixed A" 30 cm, 20 micron linear mixed-bed columns (purchased from Agilent Technologies, Inc.). The chromatographic solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume used was 200 microliters, and the flow rate was 1.0 milliliters / minute.

[0072] Calibration of the GPC column set was performed using 21 narrow molecular weight distribution polystyrene standards ranging from 580 g / mol to 8,400,000 g / mol. The standards were prepared in six "cocktail" mixtures with at least a 10-fold separation between individual molecular weights. The standards were purchased from Agilent Technologies, Inc. Polystyrene standards were prepared at 0.025 grams in 50 milliliters of solvent for molecular weights above 1,000,000 and 0.05 grams in 50 milliliters of solvent for molecular weights below 1,000,000. The polystyrene standards were predissolved at 80°C with gentle agitation for 30 minutes, then cooled, and the room temperature solutions were transferred to an autosampler dissolving oven at 160°C for 30 minutes to cool. The peak molecular weights of the polystyrene standards were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)):

[0073]

number

[0074] A fifth order polynomial was used to fit each polyethylene equivalent calibration point.

[0075] A total plate count of the GPC column set was performed using decane introduced into the blank sample via a micropump controlled using a PolymerChar GPC-IR system. The plate count of the chromatography system must be greater than 18,000 for four "Mixed A" 30 cm 20-micron linear mixed-bed columns (Agilent Technologies, Inc.).

[0076] Samples were prepared in a semi-automated fashion using PolymerChar's "Instrument Control" software to target a sample weight of 2 mg / mL, and the solvent (containing 200 ppm BHT) was added via a PolymerChar high-temperature autosampler to a pre-nitrogen-sparged, septum-capped vial. Samples were dissolved at 160°C with "slow" shaking for 2 hours.

[0077] Calculations of Mn(GPC), Mw(GPC), and Mz(GPC) were based on GPC results using PolymerChar GPCOne™ software, the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to Equations 2-4, using baseline-subtracted IR chromatograms at each equally spaced data collection point (i), and the polyethylene equivalent molecular weight obtained from a narrow standard calibration curve at point (i) from Equation 1.

[0078]

number

[0079] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by the PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate (Flow Rate (Apparent)) for each sample by matching the RV of the respective decane peak in the sample (RV(FM Sample)) with the RV of the decane peak during calibration in the narrow standard (RV(FM Calibrated)). Any change in the time of the decane marker peak is then assumed to be related to a linear shift in flow rate (Flow Rate (Effective)) throughout the run. After calibrating the system based on the flow rate marker peak, the effective flow rate (relative to the narrow standard calibration) is calculated as per Equation 5. Processing of the flow rate marker peak was performed via PolymerChar GPCOne™ software. An acceptable flow rate correction requires that the effective flow rate be within ±0.5% of the apparent flow rate.

[0080]

number

[0081] The embodiments will be further clarified by the following examples.

[0082] A series of simulations was prepared according to the conditions specified in Tables 1-3. The simulated system used three reactors in series. Reactor 1 was a CSTR. Reactor 2 was a loop reactor. Reactor 3 was a plug flow reactor.

[0083] Table 1 shows the conditions for the first reactor, Table 2 shows the conditions for the second reactor, and Table 3 shows the conditions for the third reactor. Comparative examples are designated CE, and inventive examples are designated IE. In each of IE1-4 and CE1-4, the first reactor comonomer was 1-octene. Table 4 shows the total product exiting the third reactor, or the second reactor if no third reactor was present.

[0084] [Table 1]

[0085] [Table 2]

[0086] [Table 3]

[0087] [Table 4]

[0088] [Table 5]

[0089] Table 4 above shows data for the overall polymer manufacturing process. As can be seen from Table 4, the inventive examples demonstrate a significant increase in production rate beyond their design capabilities while maintaining the same overall density and melt index properties as the comparative examples.

[0090] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Accordingly, this specification is intended to cover all such modifications and variations of the various embodiments described herein, provided they come within the scope of the appended claims and their equivalents.

Claims

1. 1. A method for producing an ethylene-based polymer comprising a first polymer fraction and a second polymer fraction, comprising: Ethylene monomer and optionally C ３ ~C １２ reacting an α-olefin comonomer in a first solvent in the presence of a first catalyst in a first solution polymerization reactor to produce said first polymer fraction; The first polymer fraction, the second catalyst, and ethylene monomer, optionally C ３ ~C １２ reacting a second feed comprising an α-olefin comonomer, and optionally hydrogen, in a second solution polymerization reactor to produce a second polymer fraction, wherein the second feed is substantially free of solvent; producing an effluent from the second solution polymerization reactor, the effluent comprising the ethylene-based polymer having the first polymer fraction and the second polymer fraction.

2. The ethylene-based polymer has a melt index (I ２ 10. The method of claim 1, wherein

3. 3. The method of claim 1 or 2, wherein the weight average molecular weight (Mw) of the first polymer fraction is greater than 30,000 g / mol.

4. The method of any of claims 1 to 3, wherein the ethylene-based polymer has a density from 0.900 to 0.975 g / cc.

5. The ethylene-based polymer has an I of 20 to 500 ２１ / I ２ The method according to any one of claims 1 to 4, wherein the ratio

6. The method of any of claims 1 to 5, wherein the ethylene-based polymer has a molecular weight distribution (MWD = Mw / Mn) of 2.5 to 40.

7. 7. The method of any of claims 1 to 6, wherein the first solution polymerization reactor, the second solution polymerization reactor, or both comprise at least one continuous stirred tank reactor (CSTR), at least one loop reactor, at least one tubular reactor, or a combination thereof.

8. The process according to any one of claims 1 to 7, wherein the second solution polymerization reactor is a loop reactor.

9. 9. The method of any of claims 1 to 8, wherein the first catalyst, the second catalyst, or both, comprise at least one molecular catalyst, at least one heterogeneous Ziegler-Natta catalyst, at least one metallocene catalyst, or a combination thereof.

10. The method of any one of claims 1 to 9, further comprising a third reactor downstream of the second solution polymerization reactor.

11. The method of claim 10 , wherein the third reactor comprises a tubular reactor.

12. 12. The method of claim 10 or 11, wherein substantially no additional solvent is provided to the third reactor.

13. The method of any one of claims 1 to 12, wherein the first catalyst and the second catalyst have different compositions.

14. The process of any one of claims 1 to 13, wherein the outlet temperature of the first solution polymerization reactor is at least 110°C.

15. The process of any one of claims 1 to 14, wherein the outlet temperature of the first solution polymerization reactor is at least 160°C.

16. The method of any one of claims 1 to 15, wherein the first catalyst comprises a molecular catalyst.

17. The process of any of claims 1 to 16, wherein the feed temperature of the second solution polymerization reactor is maintained below 45°C.

18. An ethylene-based polymer produced by the method of any of claims 1-17.

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