Multi-stage process for the production of ethylene-based polymers with (ultra) high molecular weight polyethylene components

Abstract

An embodiment of a process for producing an ethylene-based polymer comprising a first polymer fraction and a second polymer fraction includes reacting ethylene monomer and optionally a C3-C olefin copolymer in a solvent in the presence of a first catalyst in at least one initial reactor. 12 reacting an α-olefin comonomer to produce a first polymer fraction that reaches an outlet temperature of the reaction zone of less than 160°C, wherein the first polymer fraction has a weight average molecular weight (Mw) of greater than 500,000 g / mol; and reacting the first polymer fraction with ethylene monomer and, optionally, C3-C 12 introducing an α-olefin comonomer, a solvent, and at least one second catalyst into at least one stirred solution polymerization reactor; and 12 reacting the α-olefin comonomer in a solvent in the presence of at least one second catalyst in at least one stirred solution polymerization reactor to produce a 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 / 409,941, filed September 26, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] FIELD OF THE INVENTION This specification relates generally to processes for making ethylene-based polymers, and more particularly to methods for making ethylene-based polymers that include an ultra-high molecular weight component. [Background technology]

[0003] To improve the toughness and processability of ethylene-based polymers (e.g., LLDPE), ultra-high molecular weight polyethylene (UHMWPE) materials are sometimes added to ethylene-based polymers. Currently, UHMWPE is produced using heterogeneous catalysts in the slurry or gas phase. Traditionally, adding UHMWPE via blending results in relatively large UHMWPE particles composed of highly entangled macromolecules. Incorporating these entangled clusters of UHMWPE into the molecular structure of ethylene-based polymers is challenging due to the extreme viscosity difference. Specifically, UHMWPE can have a melt index (I2) of less than 0.01, whereas the bulk resin (e.g., LLDPE) can have a melt index at least 100 times greater. Therefore, there is a continuing need for processes to better incorporate UHMWPE into ethylene-based polymers, such as LLDPE. Summary of the Invention

[0004] Embodiments of the present disclosure fulfill this need by improving UHMWPE incorporation by producing UHMWPE in solution at low to moderate reaction temperatures, where the catalyst used is aimed not at particle formation (as in slurry or gas-phase technologies) but at producing UHMWPE chains that are uniformly dispersed in the solvent either dissolved or as a fine mist (very fine phase separation). Under subsequent solution process conditions, the dissolved or dispersed UHMWPE is solution blended with an ethylene-based polymer. This results in a highly disentangled UHMWPE fraction in solution, which is easily incorporated into downstream solution reactors used to produce the ethylene-based polymer.

[0005] According to one embodiment, a method for producing an ethylene-based polymer comprising a first polymer fraction and a second polymer fraction is provided. The method includes reacting ethylene monomer and optionally C3-C olefins in a solvent in the presence of a first catalyst in at least one initial reactor. 12 reacting an α-olefin comonomer to produce a first polymer fraction that reaches an outlet temperature of the reaction zone of less than 160°C, wherein the first polymer fraction has a weight average molecular weight (Mw) of greater than 500,000 g / mol; and reacting the first polymer fraction with ethylene monomer and, optionally, C3-C 12 introducing an α-olefin comonomer, a solvent, and at least one second catalyst into at least one stirred solution polymerization reactor; and reacting ethylene monomer and optionally a C3-C olefin comonomer in the solvent in the presence of the at least one second catalyst in the at least one stirred solution polymerization reactor. 12 reacting an α-olefin comonomer to produce a second polymer fraction; and outputting an effluent from the stirred solution polymerization reactor, the effluent comprising an ethylene-based polymer having the first polymer fraction and the second polymer fraction, unreacted ethylene monomer, and optionally unreacted C3-C6 12and outputting an ethylene-based polymer comprising an α-olefin comonomer. The ethylene-based polymer comprises 0.1 to 15 weight percent of a first polymer fraction and greater than 70 weight percent of a second polymer fraction. Further, the ethylene-based polymer has a melt index (I2) of 0.1 to 50 g / 10 min, a density of 0.870 to 0.970 g / cc, and an Mz / Mw greater than Mw / Mn.

[0006] 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]

[0007] [Figure 1] FIG. 1 is a schematic diagram of the process, according to one or more embodiments of the present disclosure. [Figure 2] FIG. 2 is another schematic diagram of the process, according to one or more embodiments of the present disclosure. [Figure 3] FIG. 2 is yet another schematic diagram of the process, according to one or more embodiments of the present disclosure. [Figure 4] 1 is a graphical plot of I10 / I2 versus I2 for experimental samples, in accordance with one or more embodiments of the present disclosure. [Figure 5] 1 is a graphical plot of melt strength versus dynamic melt viscosity for experimental samples, in accordance with one or more embodiments of the present disclosure. [Figure 6A] 1 is a graphical plot of uniaxial stress growth coefficient over time for experimental samples, in accordance with one or more embodiments of the present disclosure. [Figure 6B] 1 is a graphical plot of uniaxial stress growth coefficient over time for experimental samples, in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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.

[0009] 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 monomers. As used herein, the term "interpolymer" refers to a polymer prepared by polymerization of at least two different monomers. Thus, the generic term interpolymer includes copolymers and polymers prepared from three or more different monomers, such as terpolymers.

[0010] "Polyethylene" or "ethylene-based polymer" means a polymer containing greater than 50% by weight of units derived from ethylene monomers. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). The comonomers may include olefin 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).

[0011] The term "LDPE," sometimes referred to as "high pressure ethylene polymer" or "highly branched polyethylene," is defined to mean that the polymer is partially or wholly homopolymerized or copolymerized in an autoclave or tubular reactor at pressures above 14,500 psi (100 MPa) using a free radical initiator such as peroxide (see, for example, U.S. Pat. No. 4,599,392, incorporated herein by reference). LDPE resins typically have densities ranging from 0.916 grams per cubic centimeter (g / cc) to 0.935 g / cc.

[0012] 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. Patent 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. Patent No. 3,645,992; heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent No. 4,076,698; and / or blends thereof (such as those disclosed in U.S. Patent Nos. 3,914,342 or 5,854,045). LLDPE resins may be made via gas phase, solution phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0013] The term "MDPE" refers to polyethylene having a density of 0.926 to 0.940 g / cc. "MDPE" is typically made using chromium or Ziegler-Natta catalysts, or using single-site catalysts, including but not limited to bismetallocene catalysts and constrained geometry catalysts.

[0014] The term "HDPE" refers to polyethylenes having a density greater than about 0.940 g / cc, which are generally prepared with Ziegler-Natta, chromium, or single-site catalysts, including, but not limited to, bismetallocene and constrained geometry catalysts.

[0015] The term "UHMWPE" refers to polyethylene having a weight average molecular weight (Mw) of greater than 500,000 g / mol as measured by conventional gel permeation chromatography.

[0016] The term "disentangled network" refers to a polymer in which the chains are less interconnected, thereby allowing for increased flow, processability, and extensibility. In contrast, the term "entangled network" refers to a polymer in which the chains are highly interconnected, thereby reducing flow, processability, and extensibility.

[0017] As used in this disclosure, the terms "blend" or "polymer blend," when used, refer to a mixture of two or more polymers. A blend may or may not be miscible (phase separated at the molecular level). A blend may or may not be phase separated. A blend may or may not contain one or more domain configurations as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and other methods well known in the art. Blends can be prepared by physically mixing two or more polymers at a macro level (e.g., melt blending or compounding of resins) or a micro level (e.g., co-forming in the same reactor). Blends can be prepared in the melt phase or using solution blending in common solvents.

[0018] 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 not, unless stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any subsequent 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.

[0019] Embodiments of the present disclosure are directed to systems and methods for producing an ethylene-based polymer comprising a first polymer fraction and a second polymer fraction. The first polymer fraction may also be referred to herein as the high molecular weight fraction or "HMW fraction," while the second polymer fraction may also be referred to herein as the "bulk fraction." Referring to Figures 1 and 3, the process comprises reacting ethylene monomer and optionally C3-C6 olefins in a solvent 10 in the presence of a first catalyst 20 in at least one initial reactor 100. 12 and reacting an α-olefin comonomer to produce a first polymer fraction 130 that reaches an outlet temperature of the reaction zone of less than 160° C., and the first polymer fraction has a weight average molecular weight (Mw) of greater than 500,000 g / mol. The first polymer fraction may also be considered a UHMWPE fraction. Various means for feeding the monomers, solvent, and catalyst are contemplated as suitable. In another embodiment shown in FIG. 2, ethylene 2, C3-C 12The α-olefin comonomer 4 and solvent 6 may be mixed in a mixing vessel 50 upstream of the initial reactor 100. While Figure 2 depicts mixing vessel 50 as a Continuous Stirred Tank Reactor (CSTR), a variety of additional mixing vessels are contemplated as suitable. Additionally, as shown in Figure 2, the pre-catalyst 22 and co-catalyst 24 may be fed separately as shown, or, as shown in Figure 1, the catalysts may be fed in a single stream 20.

[0020] In one or more embodiments, the initial reactor 100 may comprise a tubular reactor, such as a tubular plug flow reactor. Additionally, as noted above, the outlet temperature may be less than 160°C, or less than 157°C. Furthermore, the outlet temperature may be 60-160°C, or 60-90°C, or 80-110°C, or 120-160°C, or 120-145°C, or 130-155°C, or 140-160°C. The pressure may range from about 400 to about 1000 psi, or from about 650 to about 800 psi. The residence time may be from about 0.5 minutes to about 15 minutes, or from about 0.5 minutes to about 2 minutes. In other embodiments, the initial reactor (e.g., a tubular reactor) may be operated under adiabatic conditions. In other embodiments, the initial reactor (e.g., a tubular reactor) may be operated under cooling, heating, or a combination thereof.

[0021] A variety of solvents are contemplated as suitable. Exemplary solvents include, but are not limited to, isoparaffin. For example, such solvents are commercially available under the name ISOPAR E (ExxonMobil Chemical Co., Houston, Tex.).

[0022] Within the first fraction, ethylene monomer may be present in an amount of at least 50% by weight, or at least 60% by weight, or at least 70% by weight, or at least 80% by weight. 12 The α-olefin comonomer may be present in the first fraction in an amount less than 50 wt%, or less than 40 wt%, or less than 30 wt%, or less than 20 wt%.

[0023] The first catalyst may comprise at least one molecular catalyst, at least one heterogeneous Ziegler-Natta catalyst, or a combination thereof. Constrained geometry catalysts and metallocene catalysts are also believed to be suitable. In one embodiment, the first catalyst comprises a molecular catalyst. The molecular catalyst may comprise one or more bis-biphenyl-phenoxy catalysts. Without being bound by theory, the use of a molecular homogeneous catalyst in a temperature regime below 160°C helps produce a first fraction of UHMWPE in a phase-separated mode that can be better incorporated into the second polymer fraction produced in the downstream stirred solution polymerization reaction, as further defined below. Without being bound by theory, the constrained crystallization of these UHMWPE chains may alter the overall performance characteristics of the polymer.

[0024] The first polymer fraction may comprise a weight average molecular weight (Mw) of greater than 500,000 g / mol, greater than 750,000 g / mol, or greater than 1,000,000 g / mol, as measured according to gel permeation chromatography. Furthermore, the first polymer fraction may have a Mw of 500,000 to 1,500,000 g / mol, 500,000 to 1,250,000 g / mol, 500,000 to 1,100,000 g / mol, 750,000 to 1,500,000 g / mol, 750,000 to 1,250,000 g / mol, 750,000 to 1,100,000 g / mol, 900,000 to 1,500,000 g / mol, 900,000 to 1,200,000 g / mol, or 900,000 to 1,100,000 g / mol. The first polymer fraction may further comprise a number average molecular weight (Mn) of greater than 250,000 g / mol, or greater than 400,000 g / mol, or greater than 500,000 g / mol, as measured by gel permeation chromatography. The first polymer fraction may further comprise a Mn of 250,000 to 750,000 g / mol, 250,000 to 600,000 g / mol, 400,000 to 750,000 g / mol, or 400,000 to 600,000 g / mol. The first polymer fraction may further comprise an MWD (=Mw / Mn) of 1 to 20, 1 to 15, 1 to 10, 1 to 5, or 1 to 3.

[0025] Furthermore, the density of the first polymer fraction may be in the range of 0.870 to 0.920 g / cc, 0.870 to 0.900 g / cc, or 0.870 to 0.890 g / cc. The melt index (I2) may be in the range of 0.0001 to 0.5 dg / min, 0.0001 to 0.1 dg / min, or 0.0001 to 0.05 dg / min.

[0026] Referring to FIGS. 1-3, a first polymer fraction 130, ethylene monomer 110, optionally C3-C 12 The α-olefin comonomer 120, solvent, and optionally at least one second catalyst 140 may be fed to at least one stirred solution polymerization reactor 200. In the stirred solution polymerization reactor 200, ethylene monomer and optionally C3-C olefin comonomer 120 are mixed together to form a C3-C olefin copolymer.12 The α-olefin comonomer is reacted in the presence of a second catalyst in a solvent to produce a second polymer fraction.

[0027] In one or more embodiments, the stirred solution polymerization reactor 200 may comprise at least one continuous stirred tank reactor (CSTR), at least one loop reactor, or a combination thereof. Further, as noted above, the outlet temperature may be from about 150 to about 575°C, or from about 175 to about 205°C. The pressure may range from about 30 to about 1000 psi, or from about 30 to about 750 psi. The residence time may be from about 2 minutes to about 20 minutes, or from about 10 minutes to about 20 minutes. In further embodiments, the outlet of the CSTR or loop reactor is connected to a tubular post-reactor capable of reaching an outlet temperature greater than 205°C.

[0028] As with the upstream initial reactor, a variety of solvents are believed to be suitable. Exemplary solvents include, but are not limited to, isoparaffins such as ISOPAR E. In one or more embodiments, the fraction of the first polymer in stirred solution polymerization reactor 200 may be less than 5 wt%, less than 2 wt%, or less than 1 wt%.

[0029] Within the second polymer fraction, ethylene monomer may be present in an amount of at least 50% by weight, or at least 60% by weight, or at least 70% by weight, or at least 80% by weight. 12 The α-olefin comonomer may be present in the second fraction in an amount less than 50 wt%, or less than 40 wt%, or less than 30 wt%, or less than 20 wt%. In one or more embodiments, the second polymer fraction comprises LLDPE.

[0030] A variety of compositions are contemplated as suitable for the second catalyst. In one embodiment, the first catalyst and the second catalyst comprise different compositions. In a further embodiment, the second catalyst may comprise at least one molecular catalyst, at least one heterogeneous Ziegler-Natta catalyst, or a combination thereof. Constrained geometry catalysts and metallocene catalysts are also contemplated as suitable. In another embodiment, the second catalyst may comprise a heterogeneous Ziegler-Natta catalyst.

[0031] The second polymer fraction may have a weight average molecular weight (Mw) of greater than 50,000 g / mol, greater than 75,000 g / mol, or greater than 90,000 g / mol, as measured by gel permeation chromatography. The second polymer fraction may also have a Mw of 50,000 to 120,000 g / mol, 50,000 to 100,000 g / mol, 75,000 to 120,000 g / mol, 75,000 to 100,000 g / mol, or 90,000 to 120,000 g / mol, or 90,000 to 100,000 g / mol. Furthermore, the second polymer fraction may have a number average molecular weight (Mn) of greater than 10,000 g / mol or greater than 15,000 g / mol, as measured by gel permeation chromatography. The second polymer fraction may have an Mn of 10,000 to 50,000 g / mol, 10,000 to 25,000 g / mol, 15,000 to 50,000 g / mol, or 15,000 to 25,000 g / mol. Furthermore, the second polymer fraction may have an MWD (=Mw / Mn) of 1 to 20, 1 to 15, 1 to 10, 2 to 5, or 3 to 5.

[0032] Furthermore, the density of the second polymer fraction may be in the range of 0.870 to 0.970 g / cc, 0.870 to 0.940 g / cc, 0.890 to 0.920 g / cc, or 0.905 to 0.920 g / cc. The melt index (I2) may be in the range of 0.1 to 50 dg / min, 0.1 to 5 dg / min, 1 to 5 dg / min, or 1 to 3 dg / min.

[0033] Referring again to FIGS. 1-3, the effluent 210 output from the stirred solution polymerization reactor 200 comprises a first polymer fraction and a second polymer fraction, unreacted ethylene monomer, and optionally unreacted C3-C6 monomers. 12 The ethylene-based polymer may include an α-olefin comonomer. The ethylene-based polymer comprises 0.1 to 15 weight percent of the first polymer fraction and greater than 70 weight percent of the second polymer fraction. Further, the ethylene-based polymer has a melt index (I2) of 0.1 to 50 g / 10 min, a density of 0.870 to 0.970 g / cc, and an Mz / Mw ratio greater than Mw / Mn.

[0034] In an embodiment, the effluent of the stirred solution polymerization reactor 200 comprises unreacted ethylene monomer and optionally unreacted C3-C6 12 To isolate the ethylene-based polymer from the α-olefin comonomer, it may be subjected to one or more separation steps.

[0035] The ethylene-based polymer may have a weight average molecular weight (Mw) of greater than 50,000 g / mol, greater than 50,000 g / mol, or greater than 100,000 g / mol, as measured by gel permeation chromatography. The ethylene-based polymer may also have a Mw of 50,000 to 150,000 g / mol, 50,000 to 120,000 g / mol, 75,000 to 150,000 g / mol, 75,000 to 120,000 g / mol, 90,000 to 150,000 g / mol, or 90,000 to 120,000 g / mol. Furthermore, the ethylene-based polymer may have a number average molecular weight (Mn) of greater than 10,000 g / mol or greater than 15,000 g / mol, as measured by gel permeation chromatography. The ethylene-based polymer may have an Mn of 10,000 to 50,000 g / mol, 10,000 to 25,000 g / mol, 15,000 to 50,000 g / mol, or 15,000 to 25,000 g / mol. The ethylene-based polymer may have a z-average molecular weight (Mz) of at least 500,000 g / mol or 750,000 g / mol. The ethylene-based polymer may have an Mz of 750,000 to 1,000,000 g / mol or 800,000 to 900,000 g / mol. Furthermore, the ethylene-based polymer may have an Mz / Mw of 1 to 20, 1 to 15, 1 to 10, 5 to 10, or 5 to 7.

[0036] Furthermore, the density of the ethylene-based polymer may be in the range of 0.870 to 0.970 g / cc, 0.870 to 0.940 g / cc, 0.890 to 0.920 g / cc, or 0.905 to 0.920 g / cc. The melt index (I2) may be in the range of 0.1 to 50 dg / min, 0.1 to 25 dg / min, 0.1 to 10 dg / min, 0.1 to 5 dg / min, 0.5 to 50 dg / min, 0.5 to 25 dg / min, 0.5 to 5 dg / min, 0.5 to 2 dg / min, or 0.5 to 1 dg / min. The ethylene-based polymer may have an I2 of 1 to 30, 5 to 20, 5 to 15, 9 to 15, or 9 to 12. 10 / I2.

[0037] 2 and 3, the effluent 210 of the stirred solution polymerization reactor 200 may be passed through a mixer 300 downstream of the stirred solution polymerization reactor 200, which includes the addition of a third catalyst 220. The third catalyst is used to remove unreacted ethylene monomer and, optionally, any unreacted C3-C6 monomer. 12 Further reaction of the α-olefin comonomer is promoted to produce a third polymer fraction having a different density and melt index (I2) than the second polymer fraction.

[0038] The third catalyst comprises at least one molecular catalyst, at least one heterogeneous Ziegler-Natta catalyst, or a combination thereof. Constrained geometry catalysts and metallocene catalysts are also believed to be suitable.

[0039] 3 , the process includes introducing mixer effluent 310 from mixer 300 into tubular polymerization reactor 400, where mixer effluent 310 comprises an ethylene-based polymer having a first polymer fraction, a second polymer fraction, and a third polymer fraction. While third catalyst 220 may already be provided to upstream mixer 300, it is contemplated that a third catalyst or another catalyst may be added to tubular reactor 300 as shown in stream 320.

[0040] Ethylene-based polymers are believed to be suitable for multiple applications, including films (monolayer and multilayer), fibers, nonwoven materials, artificial turf, and various articles incorporating these films. For example, ethylene-based polymers may be used in a variety of films, including, but not limited to, extrusion coatings, food packaging, consumer, industrial, and agricultural (coatings or films) lamination films, produce films, meat films, cheese films, candy films, clear shrink films, collated shrink films, stretch films, oriented films (MDO, BOPE), silage films, greenhouse films, fumigation films, liner films, stretch hoods, heavy-duty shipping bags, pet food, sandwich bags, sealants, and diaper backsheets.

[0041] Test Method density Samples for density measurements 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.

[0042] 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.

[0043] Melt Strength Melt strength was measured at 190 °C using a Goettfert Rheotens 71.97 (Goettfert Inc., Rock Hill, SC) and the melt was fed into a Goettfert Rheotester 2000 capillary rheometer equipped with a flat entrance angle (180 degrees) of 30 mm length and 2 mm diameter. Pellets were fed into a barrel (length = 300 mm, diameter = 12 mm), compressed, and melted for 10 min before being compressed at a wall shear rate of 38.2 s for the given die diameter. -1 The extrusion was carried out at a constant piston speed of 0.265 mm / s, corresponding to a piston speed of 0.265 mm / s. The extrudate was passed through a Rheotens wheel located 100 mm below the die exit, with an acceleration of 2.4 mm / s. 2 The strand was pulled downward by a wheel at 1000 kJ / min. The force (cN) applied to the wheel was recorded as a function of the wheel speed (mm / s). Melt strength was reported as the plateau force (cN) before the strand broke or had a significant draw resonance.

[0044] Dynamic-Mechanical Spectroscopy (DMS) Melt rheology and constant temperature frequency scans were performed under a nitrogen purge using a TA Instruments Advanced Rheometric Expansion System (ARES) rheometer equipped with 25 mm parallel plates. Frequency sweeps were performed at 190 °C for all samples spaced 2.0 mm apart at a constant tension of 10%. The frequency range was 0.1 to 100 rad / sec. The stress response was analyzed for amplitude and phase, from which the storage modulus (G'), loss modulus (G"), and dynamic melt viscosity (n * ) was calculated.

[0045] Triple Detector Gel Permeation Chromatography (TDGPC) The chromatography system consisted of a PolymerChar (Valencia, Spain) GPC-IR high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) and a 4-capillary viscometer (DV) coupled to a Precision Detectors (now Agilent Technologies) 2-angle laser light scattering (LS) detector model 2040. A 15° angle was used for all light scattering measurements. The autosampler oven compartment was set to 160°C, and the column compartment was set to 150°C. The columns used were four Agilent "Mixed A" 30 cm, 20-micron linear mixed-bed columns and a 20-um precolumn. The chromatography 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.

[0046] Calibration and calculations were performed for conventional molecular weight moments and distributions according to methods described in conventional GPC procedures (using a 20 um "Mixed A" column).

[0047] A systematic approach to determining multidetector offsets was performed in a manner consistent with that published by Balke, Mourey, et al. (Mourey and Balke, Chromatography Polym. Chpt 12, (1992)) (Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym. Chpt 13, (1992)) using PolymerChar's GPCOne™ software to optimize triple detector log (MW and IV) results from broad homopolymer polyethylene standards (Mw / Mn > 3) to narrow standard column calibration results from a narrow standard calibration curve. As used herein, "MW" refers to molecular weight.

[0048] Absolute molecular weight data were obtained using PolymerChart's GPCOne™ software in a manner consistent with that published by Zimm (Zimm, BH, J. Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scattering from Polymer Solutions, Elsevier, Oxford, NY (1987)). The total injected concentration used in determining the molecular weight was obtained from the mass detector area and mass detector constant derived from a suitable linear polyethylene homopolymer or one of the polyethylene standards of known weight-average molecular weight. Calculated molecular weights (using GPCOne™) were obtained using the light scattering constant derived from one or more of the polyethylene standards described below, and a refractive index concentration coefficient, dn / dc, of 0.104. Generally, the mass detector response (IR5) and light scattering constant (determined using GPCOne™) should be determined from a linear standard with a molecular weight greater than approximately 50,000 g / mol. Viscometer calibration (determined using GPCOne™) can be achieved using the method described by the manufacturer, or alternatively, by using published values ​​of a suitable linear standard, such as Standard Reference Material (SRM) 1475a (available from the National Institute of Standards and Technology (NIST)). The viscometer constant (obtained using GPCOne™) is calculated by relating the specific viscosity area (DV) and injected mass for the calibration standard to its intrinsic viscosity (IV). The chromatographic concentration is assumed to be low enough to preclude addressing the second viral index effect (concentration effect on molecular weight).

[0049] The absolute weight average molecular weight (Mw(Abs)) is obtained (using GPCOne™) by dividing the area integrated light scattering (LS) chromatogram (factored by the light scattering constant) by the mass recovered from the mass constant and mass detector (IR5) area. The molecular weight and intrinsic viscosity response are extrapolated (using GPCOne™) at the chromatographic end where the signal to noise is low. The other respective moments, Mn (Abs) and Mz (Abs) is calculated according to the following formulas 1 and 2.

[0050]

number

[0051] For conventional GPC, the chromatography system consisted of a PolymerChar (Valencia, Spain) GPC-IR high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) coupled to a Precision Detectors (now Agilent Technologies) two-angle laser light scattering (LS) detector model 2040. A 15-degree angle was used for all light scattering measurements. The autosampler oven compartment was set to 160 °C, and the column compartment was set to 150 °C. The columns used were four Agilent "Mixed A" 30 cm, 20 micron linear mixed-bed columns. The chromatography 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.

[0052] The GPC column set was calibrated 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. The polystyrene standards were prepared at 0.025 grams in 50 milliliters of solvent for molecular weights equal to or greater than 1,000,000 g / mol and 0.05 grams in 50 milliliters for molecular weights less than 1,000,000 g / mol. The polystyrene standards were dissolved at 80°C for 30 minutes with gentle agitation. 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)). MW ポリエチレン =A×(Mw ポリスチレン ) B (Formula 3) where MW is the molecular weight, A has a value of 0.4315, and B is equal to 1.0.

[0053] A fifth-order polynomial was used to fit each polyethylene-equivalent calibration point. A small adjustment (approximately 0.395 to 0.440) was made to A to correct for column resolution and band-broadening effects, such as a linear homopolymer polyethylene standard obtained at 120,000 g / mol (Mw).

[0054] Total plate counts for the GPC column set were performed using decane (prepared at 0.04 g in 50 milliliters of TCB). Plate counts (Equation 4) and symmetry (Equation 5) were measured with a 200 microliter injection according to the following equations:

[0055]

number

[0056]

number

[0057] Samples were prepared semi-automatically 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 septa-capped vial that had been pre-sparged with nitrogen. Samples were dissolved at 160°C with "low speed" shaking for 2 hours.

[0058] Calculations of Mn(conv), Mw(conv), and Mz(conv) were performed using the internal IR5 detector (measurement channel) of a PolymerChar GPC-IR chromatograph, according to equations 6-8, using PolymerChar's GPCOne™ software, based on GPC results using baseline-subtracted IR chromatograms at equally spaced data collection points (i) and polyethylene equivalent molecular weights obtained from a narrow standard calibration curve at point (i) from equation 1.

[0059]

number

[0060] 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 (Flow Rate (Nominal)) for each sample by RV-matching the respective decane peak in the sample (RV (FM Sample)) with that of the decane peak in the narrow standard calibration (RV (FM Calibrated)). Any change in the time of the decane marker peak was then assumed to be related to a linear shift in flow rate (Flow Rate (Effective)) throughout the run. To facilitate the highest accuracy in the RV measurement of the flow rate marker peaks, a least-squares fitting routine was used to fit the peaks in the flow rate marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation was then used to solve for the true peak position. After calibrating the system based on the flow rate marker peaks, the effective flow rate (relative to the narrow standard calibration) was calculated as shown in Equation 9. Processing of the flow rate marker peaks was performed via PolymerChar's GPCOne™ software. The allowable flow correction is to ensure that the effective flow is within ±2% of the nominal flow. Flow rate (effective) = Flow rate (nominal) * (RV(FM calibrated) / RV(FM sample)) (Equation 9)

[0061] GPC deconvolution Conventional GPC data were deconvoluted to obtain a most likely fit for two molecular weight components. There are many deconvolution algorithms available, both commercially and in the literature. These can lead to different answers depending on the assumptions used. The algorithm summarized here is optimized for the deconvolution problem of two most likely molecular weight distributions (with adjustable error terms). To allow for changes in the underlying distribution due to macromer incorporation and small variations in reactor conditions (i.e., temperature, concentration), the basis functions were modified to incorporate a normal distribution term. This term allows the basis functions for each component to be "smeared" to various degrees along the molecular weight axis. The advantage is that in the limit (low LCB, perfect control of concentration and temperature), the basis functions become a simple, most likely Flory distribution.

[0062] Three components (j = 1, 2, 3) are derived, and the third component (j = 3) is an adjustable error term. GPC data are normalized and Log 10 The weight fraction must be correctly converted to a molecular weight vector. In other words, each potential curve in the deconvolution has a height Log 10 height vector, h, reported at known intervals of molecular weight i It should consist of h i is the Log 10 The molecular weight domain is correctly converted, and the i Furthermore, these data need to be made available in a Microsoft EXCEL™ application.

[0063] Several assumptions are made for the deconvolution: each component, j, has a parameter σ j The resulting three basis functions are then used to calculate the most likely Flory distribution, which is convolved with a normal or Gaussian spread function. The resulting chi-squared, Χ 2 Used in the GPC data vector, h iIdentify the parameters that best fit the n points of

[0064]

number

[0065] Variable, CumND j、k is calculated using the EXCEL™ function “NORMDIST(x, mean, standard_dev, cumulative)” with the parameters set as follows: x=μ j +(k-10) * σ j / 3 mean=μj standard dev=σj cumulative=TRUE

[0066] Table 1 below summarizes these variables and their definitions. The EXCEL™ software application, Solver, is suitable for this task. Constraints are added to Solver to ensure a correct minimization.

[0067] [Table 1]

[0068] The eight parameters derived from the chi-square minimization are μ1, μ2, μ3, σ1, σ2, σ3, w1, and w2. The term w3 is then derived from w1 and w2 because the sum of the three components must equal 1. Table 2 is a summary of the Solver constraints used in the EXCEL program.

[0069] [Table 2]

[0070] If the Solver is correctly initialized, the Solver routine will jNone of them need to be moved to a value less than about 0.005, so no constraints need to be entered, but additional constraints that should be understood are that μ greater than 0 is allowed. j includes only the allowed limits. Also, w j is understood to be all positive. This constraint can be processed outside the Solver. w j If it is understood that w is generated from the selection of two points along the time interval of 0.0 < P1 < P2 < 1.0, then w1 = P1, w2 = P2 - P1 and w3 = 1.0 - P2, and the constraints on P1 and P2 are equivalent to the constraints required for the above w j .

[0071] Table 3 is a summary of the Solver settings under the Options tab.

[0072]

Table 3

[0073] The initial guesses for the values of μ1, μ2, w1, and w2 can be obtained by assuming two ideal Flory components that give the observed weight average, number average, and z average molecular weights for the observed GPC distribution.

[0074]

Number

[0075] Next, the values of μ1, μ2, w1, and w2 are calculated. These should be carefully adjusted to allow for a small error term, w3, and to satisfy the constraints of Table II before inputting to the Solver for the minimization process. The starting value of σ j is set to 0.05 for all.

[0076] Turbidity Haze is measured using a Byk Haze-Gard I. After the thickness measurement, the film sample is held against the lens at the integrating sphere end of the Haze-Gard I and the Illuminant A value is measured according to ASTM D1003. This test is performed first because it is non-destructive.

[0077] Instrumented Dart Impact (IDI) IDI is measured according to ASTM D7192. This standard requires a probe assembly with a diameter of 12.70 ± 0.13 mm with a hemispherical end of the same diameter. The probe used has a range of 4500 N with a sensitivity of 1.1 mV / N and is designed for dynamic measurements. The dart probe assembly is mounted on a LinMot linear motor, a tubular electromagnetic direct drive motor. The maximum speed is 5.4 m / s and the maximum force is 1650 N.

[0078] MD and CD tearing MD and CD tears were tested according to ASTM D1922-15 and measured the average force required to propagate a tear through a specified length of plastic film after the tear was initiated using an Elmendorf type tearing tester. [Example]

[0079] The embodiments will be further clarified by the following examples.

[0080] [Table 4]

[0081] The above inventive polymers were produced in a multiple reactor system, with reference to the process conditions in Table 4 above. The precharger reactor that produced the HMW component contained a catalyst system including Precatalyst 1 provided below. The precharger reactor is a tubular reactor with an elongated laminar flow profile. The residence time in the precharger is approximately 2 minutes.

[0082] Pre-catalyst 1

[0083] [ka]

[0084] In addition to precatalyst 1, the catalyst system in the precharger includes MMAO-7 (CAS 206451-54-9) cocatalyst and deactivator. The catalyst is provided at a feed rate of about 50 g / h and contains a concentration of 0.08 mmol / kg.

[0085] Reactor 2, downstream of the precharger reactor, was a CSTR reactor containing a heterogeneous Ziegler-Natta catalyst. The heterogeneous Ziegler-Natta catalyst premix was prepared substantially according to U.S. Patent No. 4,612,300 by sequentially adding volumes of ISOPAR E, a slurry of anhydrous magnesium chloride in ISOPAR E, a solution of EtAlCl2 in heptane, and a solution of Ti(O-iPr)4 in heptane to obtain a composition containing a magnesium concentration of 0.20 M and a Mg / Al / Ti ratio of 40 / 12.5 / 3. An aliquot of this composition was further diluted with ISOPAR E to obtain a final Ti concentration of 500 ppm in the slurry. While being fed to the polymerization reactor and prior to entering the polymerization reactor, the catalyst premix was contacted with a dilute solution of triethylaluminum (Et3Al) with an Al to Ti molar ratio of 4.6 to obtain the active catalyst. The Ziegler-Natta catalyst was added at a concentration of 0.63 mmol / kg.

[0086] [Table 5]

[0087] [Table 6]

[0088] [Table 7]

[0089] Referring to Figure 4 and Table 7, the HMW component increased shear thinning compared to similar samples with intermediate molecular weights. As described herein, intermediate molecular weight in this context corresponds to a Mw value of approximately 500,000 g / mol. High molecular weight corresponds to a Mw value of 1,000,000 g / mol. As shown in Figure 4, Ref ZN(A1), which does not contain an HMW component, exhibited the lowest I 10 / I2. As further shown in Figure 4, the slope of the 5% high M (C2) is higher than the 5% medium M (B2). Without being limited by theory, the increased slope is generated in part by turning off the H2 feed to reduce termination reactions during the polymerization process, thereby producing larger molecules.

[0090] Furthermore, as shown in Figure 5 and Table 7, the HMW component provides a better balance of melt strength and shear viscosity, specifically, a low η 100 It provides higher MS (high free surface flow stability) at lower temperatures (easy die flow). As shown in Figure 5, Ref ZN(A1), which does not contain HMW components, exhibits the lowest melt strength. Furthermore, Figure 5 shows a clear shift to the upper left corner of the correlation diagram for the high molecular weight samples compared to similar samples with intermediate molecular weights.

[0091] Furthermore, Figures 6A and 6B show how the HMW component increases the strain hardening of samples with an HMW component. Figure 6A is a stress / time graph for Comparative Sample A1, and Figure 6B is a stress / time graph for a 5% high molecular weight sample (C1). This shows that the molecular stress resistance changes substantially during the orientation process. For the Comparative Sample without an HMW component, the slope is essentially constant over time. An important difference between Figures 6A and 6B is the "hump" or arc in the curve of Figure 6B after an extended period of stretching. This indicates that the presence of very large linear molecules, e.g., UHMW molecules, strengthens intramolecular bonds compared to the reference sample of Figure 6A.

[0092] Monolayer film manufacturing In addition to Resin 1 and Resin 2 of the present invention described above, films were also made from the following commercially available resins manufactured by Dow Inc. (Midland, MI). INNATE™ ST50 is an LLDPE resin with a density of 0.918 g / cc and a melt index (I2) of 0.85 dg / min; AGILITY™ 1500 is an LDPE resin with a density of 0.920 g / cc and a melt index (I2) of 0.15 dg / min; DOWLEX™ 2045 is an LLDPE resin with a density of 0.920 g / cc and a melt index (I2) of 1.0 dg / min.

[0093] Films were made on a Collin Blown Film line using the process conditions in Table 4.

[0094] [Table 8]

[0095] [Table 9]

[0096] As shown in the data above, polymers E2 and C2 of the present invention have a significant 2-fold increase in CD and MD tear, thereby demonstrating a step-change improvement in CD and MD. Without being limited by theory, this increased strength correlates with the inclusion of HMW resin in the bulk resin.

[0097] 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: In at least one initial reactor, ethylene monomer and optionally C are reacted in a solvent in the presence of a first catalyst. ３ -C １２ reacting an α-olefin comonomer to produce a first polymer fraction that reaches an outlet temperature of the reaction zone of less than 160°C, wherein the first polymer fraction has a weight average molecular weight (Mw) of greater than 500,000 g / mol; the first polymer fraction, ethylene monomer, and optionally C ３ -C １２ introducing an α-olefin comonomer, a solvent, and at least one second catalyst into at least one stirred solution polymerization reactor; In said at least one stirred solution polymerization reactor, said ethylene monomer and optionally said C are polymerized in a solvent in the presence of said at least one second catalyst. ３ -C １２ reacting an α-olefin comonomer to produce a second polymer fraction; outputting an effluent from the stirred solution polymerization reactor, wherein the effluent comprises the ethylene-based polymer having the first polymer fraction and the second polymer fraction, unreacted ethylene monomer, and optionally unreacted C ３ -C １２ and outputting the α-olefin comonomer. the ethylene-based polymer comprises 0.1 to 15 weight percent of the first polymer fraction and greater than 70 weight percent of the second polymer fraction; The ethylene-based polymer has a melt index (I ２ ), a density of 0.870 to 0.970 g / cc and an Mz / Mw greater than said Mw / Mn.

2. The method of claim 1 , wherein the at least one initial reactor comprises at least one tubular reactor.

3. 3. The method of claim 2, wherein the at least one tubular reactor is a plug flow reactor.

4. and reacting the effluent of the stirred solution polymerization reactor in a mixer downstream of the stirred solution polymerization reactor in the presence of a third catalyst, wherein the third catalyst is capable of reacting the unreacted ethylene monomer and, optionally, any unreacted C. ３ -C １２ Further reaction of the α-olefin comonomer is promoted to produce a polymer having a density and melt index (I) different from that of the second polymer fraction. ２ The method of any one of claims 1 to 3, wherein a third polymer fraction is produced having a

5. 5. The method of claim 4, wherein the third catalyst comprises at least one molecular catalyst, at least one heterogeneous Ziegler-Natta catalyst, or a combination thereof.

6. 6. The method of any one of claims 1 to 5, further comprising introducing a mixer effluent from the mixer into a tubular polymerization reactor, wherein the mixer effluent comprises the ethylene-based polymer having the first polymer fraction, the second polymer fraction, and the third polymer fraction.

7. 7. The method of any one of claims 1 to 6, wherein the stirred solution polymerization reactor comprises at least one continuously stirred tank reactor (CSTR), at least one loop reactor, or a combination thereof.

8. The method of any one of claims 1 to 7, wherein the first catalyst and the second catalyst comprise different compositions.

9. A process according to any one of claims 1 to 8, wherein the stirred solution polymerization reactor comprises an outlet temperature of at least 180°C, preferably at least 190°C, or most preferably at least 200°C.

10. The method of any one of claims 1 to 9, wherein the first catalyst comprises a molecular catalyst.

11. The method of any one of claims 1 to 10, wherein the second catalyst comprises at least one molecular catalyst, at least one heterogeneous Ziegler-Natta catalyst, or a combination thereof.

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