BR112020003952B1 - THERMOFORMED MULTI-LAYER FILM STRUCTURE, THERMOFORMED SINGLE-LAYER FILM AND ARTICLE - Google Patents

Abstract

Embodiments of thermoformed monolayer or multilayer films are provided, wherein the thermoformed monolayer or multilayer films comprise a first composition comprising at least one ethylene-based polymer, wherein the first composition comprises a Comonomer Distribution Index value Molecular Weighted (MWCDI) greater than 0.9 and a melt index ratio (I10/I2) that meets the following equation: I10/I2 = 7.0 - 1.2 x log (I2).

Description

TECHNICAL FIELD

[0001] Embodiments described herein generally refer to thermoformed film compositions and, more particularly, refer to thermoformed film compositions that are imparted with enhanced toughness due to the thermoforming process.

BACKGROUND

[0002] Thermoforming is one of the most frequently used film forming techniques in many packaging applications. In the process, the film is heated and formed, still in a solid state, into a specific shape in a mold; then the product is added and finally the lid film is sealed on top. Thermoforming film structure needs to meet different requirements in order to fulfill the process and end-use stages. Since sharp products can be packaged, very good puncture resistance is required.

[0003] Furthermore, in order to retain heavy products, a certain amount of rigidity is necessary, but it must be balanced with high toughness to protect the food products that are packaged inside. Also of importance is improving low temperature resistance, as many products are frozen to protect shelf life.

[0004] That said, many of the toughness properties of conventional polymer compositions are weakened due to the thermoforming process.

[0005] Therefore, there is a need for improved thermoformable compositions that not only maintain, but improve, toughness properties after thermoforming.

SUMMARY

[0006] The present compositions meet these needs, providing improved toughness after thermoforming. After thermoforming, the present compositions demonstrated improved puncture resistance, improved dart performance and improved rigidity.

[0007] According to at least one embodiment of the present disclosure, a thermoformed multilayer film structure is provided. The thermoformed multilayer film comprises a core layer and at least two outer layers disposed externally relative to the core layer. At least one layer of the thermoformed multilayer film structure comprises a first composition comprising at least one ethylene-based polymer, wherein the first composition comprises a Molecular Weighted Comonomer Distribution Index (MWCDI) value greater than 0.9 and a melt index ratio (I10/I2) that meets the following equation: I10/I2 > 7.0 - 1.2 x log (I2).

[0008] According to another embodiment, a thermoformed monolayer film structure is provided. The thermoformed monolayer film structure comprises the first composition. Thermoformed monolayer film demonstrates an increase in puncture resistance of at least 10% due to thermoforming applications.

[0009] These and other modalities are described in more detail in the following Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The following detailed description of specific embodiments of the present disclosure may be better understood when read in combination with the following drawings, in which similar structure is indicated with similar reference numerals and in which:

[0011] Figure 1 represents the plot of “SCBf versus IR5 Area Ratio” for ten SCB standards.

[0012] Figure 2 represents the various GPC profiles for determining the IR5 Height Ratio for a sample of the first composition.

[0013] Figure 3 represents the graph of “SCBf versus Log Mwi Molecular Equivalent of Polyethylene (GPC)” for a sample of the first composition.

[0014] Figure 4 represents a plot of “Comonomer in Percentage in Mole versus Log Mwi Polyethylene Equivalent (GPC)” for a sample of the first composition.

[0015] Figure 5 is a bar graph representing puncture resistance for various monolayer films before and after thermoforming in accordance with one or more embodiments of the present disclosure.

[0016] Figure 6 is a bar graph depicting instrumented dart impact for various multilayer films before and after thermoforming in accordance with one or more embodiments of the present disclosure.

[0017] Figure 7 is a bar graph representing puncture resistance for various multilayer films before and after thermoforming in accordance with one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

[0018] Specific modalities of the present application will now be described. The disclosure may, however, be embodied in different forms and should not be construed as limited to the modalities 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 subject matter to those skilled in the art.

[0019] DEFINITIONS

[0020] The term “polymer” refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus covers the term "homopolymer", usually used to refer to polymers prepared from only one type of monomer, as well as "copolymer" which refers to polymers prepared from two or more different monomers. The term "interpolymer", as used herein, refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term interpolymer thus includes copolymers and polymers prepared from more than two different types of monomers, such as terpolymers.

[0021] “Polyethylene” or “ethylene-based polymer” means polymers that contain more than 50% by weight of units derived from the ethylene monomer. This includes polyethylene homopolymers or copolymers (i.e. units derived from two or more comonomers). Common forms of polyethylene known in the art include low-density polyethylene (LDPE); Linear Low Density Polyethylene (LDPE); Ultra Low Density Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single-site catalyzed linear low-density polyethylene, including linear and substantially linear low-density resins (m-LLDPE); Medium Density Polyethylene (MDPE); and high-density polyethylene (HDPE).

[0022] The term “LDPE” may also be cited as “high pressure ethylene polymer” or “highly branched polyethylene” and is intended to mean that the polymer is partially or completely homopolymerized or copolymerized in autoclave or tubular reactors at pressures above of 14,500 psi (100 MPa) through the use of free radical initiators such as peroxides (see, for example, US 4,599,392, which is incorporated herein by reference). LDPE resins typically have a density in the range of 0.916 to 0.935 g/cm.

[0023] The term “LLDPE” includes resin made using Ziegler-Natta catalyst systems, as well as resin made using single-site catalysts including, but not limited to, bis-metallocene catalysts (sometimes called “m-LLDPE ”) and restricted geometry catalysts and resin made using molecular post-metallocene catalysts. LLDPE includes linear, substantially linear or heterogeneous polyethylene copolymers or homopolymers. LLDPEs contain fewer long-chain branches than LDPE and include the substantially linear ethylene polymers that are further defined in US Patent 5,272,236, US Patent 5,278,272, US Patent 5,582,923 and US Patent 5,733,155 ; homogeneously branched linear ethylene polymeric compositions, such as those of US Patent 3,645,992; heterogeneously branched ethylene polymers, such as those prepared according to the process disclosed in US Patent 4,076,698; and/or mixtures thereof (such as those disclosed in US 3,914,342 or US 5,854,045). LLDPE resins can be made through gas phase, solution or paste phase polymerization or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0024] The term “MDPE” refers to polyethylenes having densities of 0.926 to 0.935 g/cc. “MDPE” is typically made using chromium or Ziegler-Natta catalysts or using single-site catalysts including, but not limited to, bis-metallocene catalysts and restricted geometry catalysts.

[0025] The term “HDPE” refers to polyethylenes having densities greater than about 0.935 g/cm3 that are generally prepared with Ziegler-Natta catalysts, chromium catalysts or single-site catalysts which include, but are not limited to , bis-metallocene catalysts and restricted geometry catalysts.

[0026] The term “ULDPE” refers to polyethylenes having densities of 0.880 to 0.912 g/cm3, which are generally prepared with Ziegler-Natta catalysts, single-site catalysts including, but not limited to, bis-metallocene catalysts and restricted geometry and molecular post-metallocene catalysts. The term "propylene-based polymer" as used herein refers to a polymer comprising, in polymerized form, refers to polymers comprising more than 50% by weight of units that have been derived from the propylene monomer. This includes propylene homopolymer, random copolymer polypropylene, impact copolymer polypropylene, propylene/α-olefin interpolymer, and propylene/α-olefin copolymer. These polypropylene materials are generally known in the art.

[0027] “Multi-layer structure” means any structure with more than one layer. For example, the multilayer structure may have two, three, four, five or more layers. A multilayer structure can be described as having the layers designated with letters. For example, a three-layer structure with a core layer B and two outer layers A and C may be designated as A/B/C. Similarly, a structure with two main layers B and C and two outer layers A and D would be designated A/B/C/D. In some embodiments, a multilayer film of the present invention comprises up to 11 layers.

[0028] Reference will now be made in detail to embodiments of monolayer and multilayer film structures of the present invention, wherein the monolayer film structure or the multilayer film structure comprises a first composition comprising at least one polymer at least ethylene base, wherein the first composition comprises a Molecular Weighted Comonomer Distribution Index (MWCDI) value greater than 0.9 and a melt index ratio (I10/I2) that meets the following equation: I10/I2^ 7.0 - 1.2 x log (I2).

[0029] Embodiments of the multilayer film structure comprise a core layer and at least two outer layers disposed externally relative to the core layer. At least one layer of the multilayer film structure comprises the first composition. The first composition may be in multiple layers of the multilayer film. For example, the first composition may be present in the core layer, in layers external to the core layer, or in combinations thereof.

First Composition

[0030] Several properties contribute to the improved toughness of the first composition. For example, the first composition has a superior distribution of comonomers, which is significantly higher in the concentration of comonomers in the high molecular weight polymer molecules and is significantly lower in the concentration of comonomers in the low molecular weight polymer molecules, compared to the conventional polymers of the art in the same general density. It was also discovered that the first composition has low LCB (Long Chain Branches), as indicated by low ZSVR, compared to conventional polymers. As a result of this comonomer distribution, as well as the low LCB nature, the first composition has more linker chains and therefore improved film toughness.

[0031] As discussed above, the first composition comprises an MWCDI value greater than 0.9. In one embodiment, the first composition has an MWCDI value less than or equal to 10.0, less than or equal to 8.0, less than or equal to 6.0. In another embodiment, the first composition has an MWCDI value less than or equal to 5.0, still less than or equal to 4.0, still less than or equal to 3.0. In yet another embodiment, the first composition has an MWCDI value greater than or equal to 1.0, further greater than or equal to 1.1, further greater than or equal to 1.2. In a further embodiment, the first composition has an MWCDI value greater than or equal to 1.3, further greater than or equal to 1.4, further greater than or equal to 1.5.

[0032] The first composition has a melt index ratio (I10/I2) that meets the following equation: I10/I2 ^ 7.0 - 1.2 x log (I2). In yet another embodiment, the first composition has a melt index ratio I10/I2 greater than or equal to 7.0, even greater than or equal to 7.1, even greater than or equal to 7.2, even greater than or equal to 7.3. In one embodiment, the first composition has a melt index ratio I10/I2 less than or equal to 9.2, less than or equal to 9.0, less than or equal to 8.8, less than or equal to 8, 5.

[0033] In one embodiment, the first composition has a ZSVR value of 1.2 to 3.0, or 1.2 to 2.5, or 1.2 to 2.0.

[0034] In yet another embodiment, the first composition has a vinyl unsaturation level greater than 10 vinyls per 1,000,000 total carbons. For example, greater than 20 vinyls per 1,000,000 total carbons, or greater than 50 vinyls per 1,000,000 total carbons, or greater than 70 vinyls per 1,000,000 total carbons, or greater than 100 vinyls per 1,000,000 total carbons. Vinyl unsaturation is calculated using nuclear magnetic resonance (NMR) spectroscopy defined below.

[0035] In one embodiment, the first composition has a density in the range of 0.900 g/cm3 to 0.960 g/cm3, or from 0.910 to 0.940 g/cm3, or from 0.910 to 0.930, or from 0.910 to 0.925 g/cm3. For example, density can range from a lower limit of 0.910, 0.912, or 0.914 g/cm3 to an upper limit of 0.925, 0.927, or 0.930 g/cm3 (1 cm3 = 1 cc).

[0036] In a further embodiment, the first composition has a melt index (I2; at 190°C/2.16 kg) of 0.1 to 50 g/10 minutes, for example, from 0.1 to 30 g /10 minutes, or from 0.1 to 20 g/10 minutes or from 0.1 to 10 g/10 minutes. For example, the melt index (I2; at 190°C/2.16 kg) can vary from a lower limit of 0.1, 0.2, or 0.5 g/10 minutes to an upper limit of 1.0 , 2.0, 3.0, 4.0, 5.0, 10, 15, 20, 25, 30, 40 or 50 g/10 minutes.

[0037] In another embodiment, the first composition has a molecular weight distribution, expressed as the ratio of the weight average molecular weight to the number average molecular weight (Mw/Mn), as determined by conventional Gel Permeation Chromatography (GPC) (GPC conv.) in the range of 2.2 to 5.0. For example, the molecular weight distribution (Mw/Mn) can vary from a lower limit of 2.2, 2.3, 2.4, 2.5, 3.0, 3.2, or 3.4 to a lower limit of higher than 3.9, 4.0, 4.1, 4.2, 4.5 or 5.0.

[0038] In one embodiment, the first composition has a number average molecular weight (Mn) as determined by GPC conv. in the range of 10,000 to 50,000 g/mol. For example, the number average molecular weight can be from a lower limit of 10,000, 20,000, or 25,000 g/mol to an upper limit of 35,000, 40,000, 45,000, or 50,000 g/mol. In another embodiment, the ethylene-based polymer has a weight average molecular weight (Mw) as determined by GPC conv. in the range of 70,000 to 200,000 g/mol. For example, the number average molecular weight can be from a lower limit of 70,000, 75,000, or 78,000 g/mol to an upper limit of 120,000, 140,000, 160,000, 180,000, or 200,000 g/mol.

[0039] In one embodiment, the first composition has a melt viscosity ratio, Eta * 0.1/Eta * 100, in the range of 2.2 to 7.0, where Eta * 0.1 is the dynamic viscosity calculated at a shear rate of 0.1 rad/s and Eta * 100 is the dynamic viscosity calculated at a shear rate of 100 rad/s. More details on the melt viscosity ratio and dynamic viscosity calculations are provided below.

[0040] In one embodiment, the ethylene-based polymer of the first composition is an ethylene/α-olefin interpolymer and an ethylene/α-olefin copolymer. The α-olefin can have less than or equal to 20 carbon atoms. For example, α-olefin comonomers can have 3 to 10 carbon atoms or 3 to 8 carbon atoms. Exemplary α-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and 4-methyl-1-pentene. The one or more α-olefin comonomers may, for example, be selected from the group consisting of propylene, 1-butene, 1-hexene and 1-octene; or alternatively, from the group consisting of 1-butene, 1-hexene and 1-octene and further 1-hexene and 1-octene.

[0041] Ethylene-based polymers may comprise less than 20 percent by weight of units derived from one or more α-olefin comonomers. All individual values and subranges of less than 18 weight percent are included and disclosed here; for example, ethylene-based polymers may comprise less than 15 weight percent units derived from one or more α-olefin comonomers; or alternatively, less than 10 weight percent units derived from one or more α-olefin comonomers; or, alternatively, from 1 to 20 weight percent units derived from one or more α-olefin comonomers; or alternatively, from 1 to 10 percent by weight of units derived from one or more α-olefin comonomers.

[0042] Conversely, ethylene-based polymers can comprise at least 80 weight percent ethylene-derived units. All individual values and subranges of at least 80 weight percent are included and disclosed here; for example, ethylene-based polymers may comprise at least 82 weight percent ethylene-derived units; or alternatively, at least 85 weight percent ethylene-derived units; or alternatively, at least 90 weight percent ethylene-derived units; or alternatively, from 80 to 100 percent by weight of ethylene-derived units; or, alternatively, 90 to 100 weight percent ethylene-derived units.

[0043] Optionally, the first composition may further comprise a second ethylene-based polymer. In a further embodiment, the second ethylene-based polymer is an ethylene/α-olefin interpolymer and an ethylene/α-olefin copolymer or an LDPE. Suitable α-olefin comonomers are listed above.

[0044] In one embodiment, the second ethylene-based polymer is a heterogeneously branched ethylene/α-olefin interpolymer and a heterogeneously branched ethylene/α-olefin copolymer. Heterogeneously branched ethylene/α-olefin interpolymers and copolymers are typically produced using the Ziegler/Natta type catalyst system and have more comonomers distributed in the lower molecular weight molecules of the polymer.

[0045] In one embodiment, the second ethylene-based polymer has a molecular weight distribution (Mw/Mn) in the range of 3.0 to 5.0, for example, 3.2 to 4.6. For example, the molecular weight distribution (Mw/Mn) can be from a lower limit of 3.2, 3.3, 3.5, 3.7, or 3.9 to an upper limit of 4.6, 4, 7, 4.8, 4.9 or 5.0.

[0046] In one embodiment, the composition further comprises another polymer. In a further embodiment, the polymer is selected from the following: an LLDPE, an MDPE, an LDPE, an HDPE, a propylene-based polymer, or a combination thereof.

[0047] In one embodiment, the first composition additionally comprises an LDPE. In a further embodiment, the LDPE is present in an amount of 5 to 50% by weight, further from 10 to 40% by weight, further from 15 to 30% by weight, based on the weight of the composition. In a further embodiment, the LDPE has a density of 0.915 to 0.925 g/cm3 and a melt index (I2) of 0.5 to 5 g/10 min, in addition to 1.0 to 3.0 g/10 min. .

[0048] In other embodiments, the first composition may comprise one or more additives. Additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers (e.g. TiO2 or CaCO3), opacifiers, nucleators, processing aids, pigments, primary antioxidants, secondary antioxidants, UV stabilizers, anti-blocking agents , anti-slip agents, tackifiers, fire retardants, antimicrobial agents, odor reducing agents, antifungal agents and combinations thereof. Additional Thermoformed Film Components

[0049] Additionally, in one or more embodiments, the multilayer film may comprise propylene-based polymers. Various propylene-based polymer products are considered suitable, for example, propylene-ethylene copolymer resins, such as VERSIFY™ 3000 or 3200, which are both supplied by The Dow Chemical Company, Midland, MI. In some embodiments, the thermoformed multilayer film structure is substantially free of propylene-based polymers. As used herein, "substantially free from propylene-based polymers" means less than 0.5% by weight of the thermoformed multilayer film, or less than 0.1% by weight or less than 0.01% by weight.

[0050] Furthermore, in additional embodiments, the thermoformed monolayer and multilayer film structures consist essentially of ethylene-based polymers. As used herein, "essentially consists" means that the thermoformed monolayer or multilayer film structure may include other additives, but is limited to ethylene-based polymer.

[0051] Thermoformed monolayer and multilayer film structures may include additional ethylene-based polymers in addition to the ethylene-based polymer of the first composition. In one embodiment, the thermoformed multilayer film structure may comprise ethylene-based polymer having a density of 0.895-0.965 g/cm3 and a melt index (I2) of 0.5 to 6.0 g/10 min. , when measured in accordance with ASTM D 1238 at a load of 2.16 kg and a temperature of 190°C. In other embodiments, the density may be 0.900 to 0.940 g/cm3, or 0.9000.925 g/cm3 and the melt index (I2) is 0.85-3.5 g/10 min., or 2 .0 to 6.0 g/10 min. Examples may include, but are not limited to, DOW™ low density polyethylenes (LDPE) and linear low density polyethylenes (LLDPE), DOWLEX™ linear low density polyethylenes (LLDPE), ATTANE ultra low density polyethylenes (ULDPE) ™, ELITE™ intensified polyethylenes, each being commercially available from The Dow Chemical Company, Midland, MI.

[0052] In other embodiments, the thermoformed multilayer film may comprise additional compositions in one or more of the layers. In some embodiments, a multilayer film of the present disclosure may comprise one or more barrier layers. In such embodiments, the barrier layer may comprise one or more polyamides (nylons), ethylene vinyl alcohol (EVOH) copolymers and/or maleated polyolefins. EVOH may include a vinyl alcohol copolymer having 27 to 44 mol% ethylene and is prepared, for example, by hydrolysis of vinyl acetate copolymers. Examples of commercially available EVOH that can be used in embodiments of the present invention include EVAL™ from Kuraray and Noltex™ from Nippon Goshei. In embodiments where the barrier layer comprises polyamide, the polyamide may include polyamide 6, polyamide 9, polyamide 10, polyamide 11, polyamide 12, polyamide 6,6, polyamide 6/66 and aromatic polyamide, such as polyamide 61, polyamide 6T, MXD6, or combinations thereof.

[0053] Maleated polyolefins are contemplated for several layers of the thermoformed multilayer film. In some embodiments, the maleated polyolefins may be in a tie layer of the thermoformed multilayer film. Maleated polyolefins may comprise polyethylene grafted with maleic anhydride or polypropylene grafted with maleic anhydride. Suitable commercial examples of maleic anhydride-grafted polyethylene are AMPLIFY™ TY 1057H from The Dow Chemical Company (Midland, MI).

[0054] In other embodiments, multilayer or monolayer films may be free of polyamide. In some of these embodiments, the absence of polyamide can result in a cheaper multilayer film with thermoforming properties comparable to multilayer films comprising polyamide. In some embodiments, a multilayer film may comprise less than 5 wt% polyamide, or less than 3 wt% polyamide, or less than 1 wt% polyamide, or less than 0.5 wt% polyamide. , each based on the total weight of the film. However, as indicated above, there are some embodiments (e.g., when polyamide will be used as a barrier layer) in which a multilayer film includes greater amounts of polyamide.

[0055] In some embodiments, the multilayer films may include a tie layer. A tie layer can be used to adhere two layers together during coextrusion, particularly when there is an incompatibility between the compositions of the two layers. For example, if a multilayer film comprises an ethylene vinyl alcohol barrier layer, a tie layer can be used to adhere the ethylene vinyl alcohol layer to a layer predominantly comprising polyolefins. Persons skilled in the art can determine whether a tie layer is necessary and, if so, select an appropriate tie layer depending on the composition of the layers to be included in the multilayer film, based on the teachings presented herein.

[0056] It should be understood that any of the layers within a multilayer film of the present invention may further comprise one or more additives as known to those skilled in the art, such as, for example, antioxidants, ultraviolet light stabilizers, thermal stabilizers, slip agents, anti-blocking agents, pigments or dyes, processing aids, cross-linking catalysts, flame retardants, fillers and foaming agents.

[0057] The multilayer or monolayer films of the present disclosure may have a total thickness (before thermoforming) in the range of 10 μm to 250 μm, preferably 50 μm to 200 μm or 100 μm to 180 μm. Individual layer thickness may vary depending on the number of layers available, the type of layer (e.g. skin layer, barrier layer, inner layer, etc.) and the total thickness of the film. The multilayer films of the present disclosure may be coextruded (e.g., using a blown film process or a cast film process) in some embodiments using techniques known to those skilled in the art. Multilayer, collapsed, or monolayer films of the present disclosure are well suited for use in thermoforming applications in some embodiments. In one or more embodiments, the multilayer film may comprise at least 50% based on the overall multilayer film thickness percentage of the first composition. In another embodiment, the multilayer film may comprise at least 60% based on the overall multilayer film thickness percentage of the first composition.

[0058] The present multilayer and monolayer films can be formed into a variety of articles using techniques known to those skilled in the art. For example, monolayer and multilayer films can be thermoformed into an article in some embodiments. Examples of such articles include rigid containers, flexible trays and semi-flexible packaging. Such articles can be used, for example, in the packaging of foods, such as fruits, cheese, meat, processed meat, processed foods and frozen foods. Properties of Single-Layer and Multi-Layer Films

[0059] The thermoformed monolayer film can demonstrate an increase in puncture resistance of at least 10% due to thermoforming. In other embodiments, the thermoformed monolayer film may demonstrate an increase in puncture resistance of at least 15%, or at least 20%, due to the thermoforming step.

[0060] Additionally, the thermoformed polyolefin multilayer film structure can also demonstrate improved properties. For example, thermoformed polyolefin multilayer film may have an Instrumented Dart Impact of at least 0.6 J, or at least 0.8 J, or at least 1.0 J when measured in accordance with ASTM D3763. Polymerization Process to Make the First Composition

[0061] To produce the ethylene-based polymer of the first composition, suitable polymerization processes may include, but are not limited to, solution polymerization processes using one or more conventional reactors, e.g., closed loop reactors, isothermal reactors. , adiabatic reactors, stirred tank reactors, autoclave reactors in parallel, series and/or any combination thereof. Ethylene-based polymer compositions can, for example, be produced by solution phase polymerization processes using one or more closed loop reactors, adiabatic reactors and combinations thereof.

[0062] In general, the solution phase polymerization process occurs in one or more well-mixed reactors, such as one or more closed loop reactors and/or one or more adiabatic reactors at a temperature in the range of 115 to 250°C ; for example, from 135 to 200°C and at pressures in the range of 300 to 1,000 psig, for example, from 450 to 750 psig.

[0063] In one embodiment, the ethylene-based polymer can be produced in two closed-loop reactors in series configuration, the first reactor temperature is in the range of 115 to 200°C, for example, from 135 to 165° C and the second reactor temperature is in the range of 150 to 210°C, for example, 185 to 200°C. In another embodiment, the ethylene-based polymer composition can be produced in a single reactor, the reactor temperature is in the range of 115 to 200 ° C, for example, from 130 to 190 ° C. The residence time in a solution phase polymerization process is typically in the range of 2 to 40 minutes, e.g. 5 to 20 minutes. Ethylene, solvent, one or more catalyst systems, optionally one or more cocatalysts, and optionally one or more comonomers, are fed continuously to one or more reactors. Exemplary solvents include, but are not limited to, isoparaffins. For example, these solvents are commercially available under the name ISOPAR E from ExxonMobil Chemical. The resulting mixture of the ethylene-based polymer composition and solvent is then removed from the reactor or reactors, and the ethylene-based polymer composition is isolated. The solvent is normally recovered through a solvent recovery unit, i.e. heat exchangers and separator vessel, and the solvent is then recycled back to the polymerization system.

[0064] In one embodiment, the ethylene-based polymer of the first composition can be produced, through a solution polymerization process, in a dual reactor system, for example, a double circuit reactor system, in which ethylene and, optionally, one or more α-olefins, are polymerized in the presence of one or more catalyst systems, in a reactor, to produce a first ethylene-based polymer, and ethylene and, optionally, one or more α-olefins, are polymerized in the presence of one or more catalyst systems, in a second reactor, to produce a second ethylene-based polymer. Additionally, one or more cocatalysts may be present.

[0065] In another embodiment, the ethylene-based polymer can be produced through a solution polymerization process, in a single reactor system, e.g., a single-loop reactor system, in which ethylene and, optionally, one or more α-olefins, are polymerized in the presence of one or more catalyst systems. Additionally, one or more cocatalysts may be present.

[0066] As discussed above, the invention provides a process for forming a composition comprising at least two ethylene-based polymers, said process comprising the following: polymerizing ethylene and, optionally, at least one comonomer, in solution, in the presence of a catalyst system comprising a ligand-metal complex of Structure I, to form a first ethylene-based polymer; and polymerizing ethylene, and optionally at least one comonomer, in the presence of a catalyst system comprising a Ziegler/Natta catalyst, to form a second ethylene-based polymer; and where structure I is as follows: where: M is titanium, zirconium or hafnium, each independently being in a formal oxidation state of +2, +3 or +4; en is an integer from 0 to 3, and where, when n is 0, X is absent; and each X, independently, is a monodentate ligand that is neutral, monoanionic or dianionic; or two Xs are taken together to form a bidentate ligand that is neutral, monoanionic or dianionic; and X and n are chosen such that the metal-ligand complex of formula (I) is, in general, neutral; and each Z, independently, is O, S, N(C1-C40)hydrocarbyl or P(C1-C40)hydrocarbyl; and in which the ZLZ fragment is composed of formula (1): R1 to R16 are each independently selected from the group consisting of: a substituted or unsubstituted (C1-C40)hydrocarbyl, a substituted or unsubstituted (C1-C40)heterohydrocarbyl, Si(RC)3, Ge (RC)3, P(RP)2, N(RN)2, ORC, SRC, NO2, CN, CF3, RCS(O)-, RCS(O)2-, (RC)2C=N-, RCC( O)O-, RCOC(O)-, RCC(O)N(R)-, (RC)2NC(O)-, halogen atom, hydrogen atom; and wherein each RC is independently a (C1-C30)hydrocarbyl; RP is a (C1-C30)hydrocarbyl; and RN is a (C1-C30)hydrocarbyl; and wherein, optionally, two or more R groups (from R1 to R16) may combine together in one or more ring structures, with such ring structures each independently having from 3 to 50 ring atoms, excluding any atom of hydrogen.

[0067] The process may comprise a combination of two or more modalities, as described here. In one embodiment, the process comprises polymerizing ethylene and, optionally, at least one α-olefin, in solution, in the presence of a catalyst system comprising a metal ligand complex of Structure I, to form a first ethylene-based polymer; and polymerizing ethylene, and optionally at least one α-olefin, in the presence of a catalyst system comprising a Ziegler/Natta catalyst, to form a second ethylene-based polymer. In another embodiment, each α-olefin is independently a C1-C8 α-olefin.

[0068] In one embodiment, optionally, two or more R groups from R9 to R13 or R4 to R8 may combine together into one or more ring structures, wherein these ring structures each independently have 3 to 50 atoms in the ring, excluding any hydrogen atoms.

[0069] In one embodiment, M is hafnium.

[0070] In one embodiment, R3 and R14 are each independently an alkyl, and also a C1-C3 alkyl, and also methyl.

[0071] In one embodiment, R1 and R16 are each as follows: .

[0072] In one embodiment, each of the groups aryl, heteroaryl, hydrocarbyl, heterohydrocarbyl, Si(RC)3, Ge(RC)3, P(RP)2, N(RN)2, ORC, SRC, RCS (O)-, RCS(O)2-, (RC)2C=N-, RCC(O)O-, RCOC(O)-, RCC(O)N(R)-, (RC)2NC(O) -, hydrocarbylene and heterohydrocarbylene, independently, is not substituted or substituted by one or more RS substituents; and each RS is independently a halogen atom, polyfluoro substitution, perfluoro substitution, (C1-C18)unsubstituted alkyl, F3C-, FCH2O-, F2HCO-, F3CO-, R3Si-, R3Ge-, RO-, RS-, RS(O)-, RS(O)2-, R2P-, R2N-, R2C=N-, NC-, RC(O)O-, ROC(O)-, RC(O)N(R )- or R2NC(O)-, or two of the RS are taken together to form an unsubstituted (C1-C18)alkylene, wherein each R is independently an unsubstituted (C1-C18)alkyl.

[0073] In one embodiment, two or more of R1 to R16 do not combine to form one or more ring structures.

[0074] In one embodiment, the catalyst system suitable for producing the first ethylene/α-olefin interpolymer is a catalyst system comprising bis((2-oxoyl-3-(dibenzo-1H-pyrrol-1-yl)-5 -(methyl)phenyl)-2-phenoxymethyl)-methylene-1,2-cyclohexanediyl-hafnium (IV) dimethyl, represented by the following Structure: IA:

[0075] Ziegler/Natta catalysts suitable for use in the invention are typical supported Ziegler-type catalysts, which are particularly useful at the high polymerization temperatures of the solution process. Examples of such compositions are those derived from organomagnesium compounds, alkyl halides or aluminum halides or hydrogen chloride and a transition metal compound. Examples of such catalysts are described in US Patents 4,612,300, 4,314,912, and 4,547,475; the teachings of which are incorporated herein by reference.

[0076] Particularly suitable organomagnesium compounds include, for example, hydrocarbon-soluble dihydrocarbylmagnesium, such as magnesium dialkyls and magnesium diaryls. Examples of suitable magnesium dialkyls include, particularly, n-butyl-sec-butylmagnesium, diisopropylmagnesium, di-n-hexylmagnesium, isopropyl-n-butylmagnesium, ethyl-n-hexylmagnesium, ethyl-n-butylmagnesium, di-n-octylmagnesium and others, where the alkyl has from 1 to 20 carbon atoms. Suitable everyday examples of magnesium include diphenylmagnesium, dibenzylmagnesium and Ditolylmagnesium. Suitable organomagnesium compounds include alkyl and aryl magnesium alkoxides and aryl oxides and aryl and alkyl magnesium halides, with halogen-free organomagnesium compounds being more desirable.

[0077] Halide sources include active non-metal halides, metal halides and hydrogen chloride. Suitable non-metal halides are represented by the formula R'X, where R' is hydrogen or an active monovalent organic radical and X is a halogen. Particularly suitable non-metal halides include, for example, hydrogen halides and active organic halides, such as t-alkyl halides, allyl halides, benzyl halides and other active hydrocarbyl halides. By active organic halide is meant a hydrocarbyl halide that contains a labile halogen at least as active, that is, as easily lost to another compound, as the sec-butyl chloride halogen, preferably as active as t-chloride. butyl. In addition to organic monohalides, it is understood that organic dihalides, trihalides and other polyhalides that are active, as previously defined, are also suitably employed. Examples of preferred active non-metal halides include hydrogen chloride, hydrogen bromide, t-butyl chloride, t-amyl bromide, allyl chloride, benzyl chloride, crotyl chloride, methylvinylcarbinyl chloride, α-phenylethyl bromide, diphenylmethyl chloride, and the like. Most preferred are hydrogen chloride, t-butyl chloride, allyl chloride and benzyl chloride.

[0078] Suitable metal halides include those represented by the formula MRy-a Xa, where: M is a metal from Groups IIB, IIIA or IVA of Mendeleev's periodic Table of Elements; R is a monovalent organic radical; X is a halogen; y has a value corresponding to the valence of M; and "a" has a value from 1 to y. Preferred metal halides are aluminum halides of the formula AlR3-a Xa, wherein each R is independently hydrocarbyl, such as alkyl; X is a halogen; and a is a number from 1 to 3. Most preferred are alkylaluminum halides, such as ethylaluminum sesquichloride, diethylaluminum chloride, ethylaluminum dichloride and diethylaluminum bromide, with ethylaluminum dichloride being especially preferred. Alternatively, a metal halide, such as aluminum trichloride, or a combination of aluminum trichloride with an alkyl aluminum halide, or a trialkyl aluminum compound may suitably be employed.

[0079] Any of the conventional Ziegler-Natta transition metal compounds may be useful as a transition metal component in the preparation of the supported catalyst component. Typically, the transition metal component is a compound of a Group IVB, VB, or VIB metal. The transition metal component is generally represented by the formulas: TrX'4-q (OR1)q, TrX'4-q (R2)q, VOX'3 and VO(OR)3.

[0080] Tr is a Group IVB, VB or VIB metal, preferably a Group IVB or VB metal, preferably titanium, vanadium or zirconium; q is 0 or a number equal to or less than 4; X' is a halogen and R1 is an alkyl group, aryl group or cycloalkyl group that has 1 to 20 carbon atoms; and R2 is an alkyl group, aryl group, aralkyl group, substituted aralkyls and the like.

[0081] Aryl, aralkyls and substituted aralkyls contain 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. When the transition metal compound contains a hydrocarbyl group, R2, being an alkyl, cycloalkyl, aryl or aralkyl group, the hydrocarbyl group will preferably not contain an H atom in the beta position to the carbon bond of the metal. Illustrative, but not limiting, examples of aralkyl groups are methyl, neopentyl, 2,2-dimethylbutyl, 2,2-dimethylhexyl; aryl groups such as benzyl; cycloalkyl groups such as 1-norbornyl. Mixtures of these transition metal compounds may be employed if desired.

[0082] Illustrative examples of transition metal compounds include TiCl4, TiBr4, Ti(OC2H5)3Cl, Ti(OC2H5)Cl3, Ti(OC4H9)3Cl, Ti(OC3H7)2Cl.2, Ti(OC6H13)2Cl2, Ti( OC8H17)2Br2 and Ti(OC12H25)Cl3, Ti(O-iC3H7)4 and Ti(O-nC4H9)4. Illustrative examples of vanadium compounds include VCl4, VOCl3, VO(OC2H5)3 and VO(OC4H9)3. Illustrative examples of zirconium compounds include ZrCl4, ZrCl3(OC2H5), ZrCl2(OC2H5)2, ZrCl(OC2H5)3, Zr(OC2H5)4, ZrCl3(OC4H9), ZrCl2(OC4H9)2 and ZrCl(OC4H9)3.

[0083] An inorganic oxide support can be used in preparing the catalyst, and the support can be any particulate oxide or mixed oxide that has been thermally or chemically dehydrated so that it is substantially free of adsorbed moisture. See US Patents 4,612,300, 4,314,912 and 4,547,475, the teachings of which are incorporated herein by reference.

[0084] The catalyst systems described above can be made catalytically active by contacting or combining it with the activation cocatalyst or by using an activation technique, such as those known in the art, for use in olefin-based polymerization reactions. of metal. Suitable activation cocatalysts for use herein include aluminum alkyl; polymeric or oligomeric alumoxanes (also known as aluminoxanes); neutral Lewis acids; and non-polymeric, non-coordinating, ion-forming compounds (including the use of such compounds under oxidizing conditions). A suitable activation technique is bulk electrolysis. Combinations of one or more of the above cocatalysts and activation techniques are also contemplated. The term "alkyl aluminum" means a monoalkyl aluminum dihydride or monoalkylaluminum dihalide, a dialkyl aluminum hydride or dialkyl aluminum halide or a trialkylaluminum. Aluminoxanes and preparations thereof are known, for example, in US Patent 6,103,657. Examples of preferred polymeric or oligomeric alumoxanes are methylalumoxane, triisobutylaluminum modified methylalumoxane and isobutylalumoxane.

[0085] Exemplary Lewis acid activation cocatalysts are Group 13 metal compounds that contain 1 to 3 hydrocarbyl substituents, as described herein. In some embodiments, examples of Group 13 metal compounds are substituted aluminum tri(hydrocarbyl) or tri(hydrocarbyl)-boron compounds. In some other embodiments, exemplary Group 13 metal compounds are substituted tri(hydrocarbyl) aluminum or tri(hydrocarbyl)-boron compounds, tri((C1-C10)alkyl)aluminum compounds, or tri((C6-C18) )aryl)boron and its halogenated (including perhalogenated) derivatives. In some other embodiments, examples of Group 13 metal compounds are tris(fluoro-substituted phenyl)boranes, in other embodiments, tris(pentafluorophenyl)borane. In some embodiments, the activation cocatalyst is a tris((C1-C20)hydrocarbyl)borate (e.g., trityl tetrafluoroborate) or a tri((C1-C20)hydrocarbyl)ammonium tetra((C1-C20)hydrocarbyl)borane ( for example, bis(octadecyl)methylammonium tetracis(pentafluorophenyl)borane). As used herein, the term "ammonium" means a nitrogen cation that is a ((C1-C20)hydrocarbyl)4N+, a ((C1-C20)hydrocarbyl)3N(H)+, a ((C1-C20)hydrocarbyl )2N(H)2+, (C1-C20)hydrocarbylN(H)3+ or N(H)4+, where each (C1-C20)hydrocarbyl can be the same or different.

[0086] Exemplary combinations of neutral Lewis acid activation cocatalysts include mixtures comprising a combination of tri((C1-C4)alkyl)aluminum and a halogenated tri((C6-C18)aryl)boron compound, especially a tris(pentafluorophenyl )borane. Other exemplary embodiments are combinations of such neutral mixtures of Lewis acid with a polymeric or oligomeric alumoxane and combinations of a single neutral Lewis acid, especially tris(pentafluorophenyl)borane with a polymeric or oligomeric alumoxane. Exemplary embodiments of number of moles of (metal-ligand complex):(tris(pentafluoro-phenylborane):(alumoxane) [for example, (Group 4 metal-ligand complex):(tris(pentafluoro-phenylborane): (alumoxane)] are from 1:1:1 to 1:10:30, other exemplary modalities are from 1:1:1.5 to 1:5:10.

[0087] Many activation cocatalysts and activation techniques have previously been taught, in relation to different metal-ligand complexes, in the following USPNs: US 5,064,802; US 5,153,157; US 5,296,433; US 5,321,106; US 5,350,723; US 5,425,872; US 5,625,087; US 5,721,185; US 5,783,512; US 5,883,204; US 5,919,983; US 6,696,379; and US 7,163,907. Examples of suitable hydrocarbyloxides are disclosed in US 5,296,433. Examples of Bronsted acid salts suitable for addition polymerization catalysts are disclosed in US 5,064,802; US 5,919,983; US 5,783,512. Examples of suitable salts of a cationic oxidizing agent and a non-coordinating compatible anion, as activating cocatalysts for addition polymerization catalysts, are disclosed in US 5,321,106. Examples of carbenium salts suitable as activation cocatalysts for addition polymerization catalysts are disclosed in US 5,350,723. Examples of suitable silicon salts as activation cocatalysts for addition polymerization catalysts are disclosed in US 5,625,087. Examples of suitable complexes of alcohols, mercaptans, silanols and oximes with tris(pentafluorophenyl)borane are disclosed in US 5,296,433. Some of these catalysts are also described in a portion of US 6,515,155 B1, starting at column 50, line 39 and passing through column 56, line 55, only that portion of which is incorporated herein by reference.

[0088] In some embodiments, the catalyst systems described above can be activated to form an active catalyst composition by combination with one or more cocatalysts, such as a cation-forming cocatalyst, a strong Lewis acid, or a combination thereof. Cocatalysts suitable for use include polymeric or oligomeric aluminoxanes, especially methyl aluminoxane, as well as inert, compatible, non-coordinating, ion-forming compounds. Examples of suitable cocatalysts include, but are not limited to, modified methyl aluminoxane (MMAO), bis(hydrogenated alkyl tallow)methyl, tetracis(pentafluorophenyl)borate(1-) amine, triethyl aluminum (TEA) and any combinations thereof.

[0089] In some embodiments, one or more of the above activation cocatalysts are used in combination with each other. In one embodiment, a combination of a mixture of tri((C1-C4)hydrocarbyl)aluminum, tri((C1-C4)hydrocarbyl)borane or an ammonium borate with an oligomeric or polymeric alumoxane compound may be used.

TEST METHODS

[0090] Test methods include the following:

Fusion Index (I2)

[0091] The melt index (I2) was measured according to ASTM D-1238 at 190°C at 2.16 kg. Values are reported in g/10 min., which corresponds to grams eluted per 10 minutes.

Density

[0092] Samples for density measurement were prepared in accordance with ASTM D4703 and reported in grams/cubic centimeter (g/cc or g/cm3). Measurements were taken within one hour of sample pressing using ASTM D792, Method B.

Dynamic Shear Rheology

[0093] Each sample was molded by compression in a circular plate “3 mm thick x 25 mm in diameter”, at 177°C, for five minutes, under pressure of 10 MPa, in air. The sample was then removed from the press and placed on a bench to cool.

[0094] Frequency sweep and constant temperature measurements were performed on an ARES strain-controlled rheometer (TA Instruments), equipped with 25 mm parallel plates, under nitrogen purge. For each measurement, the rheometer was thermally equilibrated for at least 30 minutes before resetting the gap. The sample disk was placed on the plate and allowed to melt for five minutes at 190 °C. The plates were then closed to 2 mm, the sample was trimmed, and the test began. The method had an additional five-minute delay built in to allow the temperature to equilibrate. The experiments were carried out at 190°C, in a frequency range of 0.1 to 100 rad/s, at five points per decade interval. The strain amplitude was constant at 10%. The stress response was analyzed in terms of amplitude and phase, from which the storage modulus (G'), loss modulus (G”), complex modulus (G*), dynamic viscosity (n* or Eta*) and tan δ (or tan delta) were calculated.

Fusion Strength

[0095] Melt strength measurements were performed on a Gottfert Rheotens 71.97 (Goettfert Inc.; Rock Hill, SC) coupled to a Gottfert Rheotester 2000 capillary rheometer. A polymer melt was extruded through a capillary die with an entry angle flat (180 degrees), with a capillary diameter of 2.0 mm and an aspect ratio (capillary length/capillary diameter) of 15.

[0096] After equilibrating the samples at 190°C for 10 minutes, the piston was operated at a constant speed of 0.265 mm/second. The standard test temperature was 190°C. The sample (about 20 grams) was uniaxially attracted to a set of accelerated necks, located 100 mm below the matrix, with an acceleration of 2.4 mm/second2. The traction force was recorded as a function of the advance speed of the clamping rollers. Melt strength was reported as the plateau force (cN) before yarn rupture. The following conditions were used to measure the fusion force: piston speed = 0.265 mm/second; wheel acceleration = 2.4 mm/s2; capillary diameter = 2.0 mm; capillary length = 30 mm; and cylinder diameter = 12 mm. Conventional Gel Permeation Chromatography (GPC conv.)

[0097] A GPC-IR high temperature chromatography system from PolymerChar (Valencia, Spain) was equipped with a Precision Detectors (Amherst, MA), a Model 2040 two-angle laser light scattering detector, an IR5 infrared detector and a 4-capillary viscometer, both from PolymerChar. Data collection was performed using PolymerChar's Instrument Control software and data collection interface. The system was equipped with a solvent degassing device and pumping system from Agilent Technologies (Santa Clara, CA).

[0098] The injection temperature was controlled at 150 degrees Celsius. The columns used were three 10 micron “Mixed-B” columns available from Polymer Laboratories (Shropshire, UK). The solvent used was 1,2,4-trichlorobenzene. Samples were prepared at a concentration of "0.1 grams of polymer in 50 milliliters of solvent." The chromatographic solvent and sample preparation solvent contained "200 ppm butylated hydroxytoluene (BHT)". Both solvent sources were sparged in nitrogen. The ethylene-based polymer samples were gently stirred at 160 degrees Celsius for three hours. The injection volume was "200 microliters" and the flow rate was "1 milliliter/minute." The GPC column set was calibrated by running 21 "narrow molecular weight distribution" polystyrene standards. The molecular weight (MW) of the standards ranged from 580 to 8,400,000 g/mol, and the standards were contained in six “cocktail” mixtures. Each standard mixture had at least a decade of separation between individual molecular weights. were purchased from Polymer Laboratories. Polystyrene standards were prepared at “0.025 g in 50 ml of solvent” for molecular weights equal to or greater than 1,000,000 g/mol and at “0.050 g in 50 ml of solvent” for molecular weights lower than 1,000,000 g/mol.

[0099] The polystyrene standards were dissolved at 80 °C, with gentle agitation, for 30 minutes. Narrow pattern mixtures were run first and in descending order of “highest molecular weight component” to minimize degradation. Standard polystyrene peak molecular weights were converted to polyethylene molecular weight using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Letters, 6, 621 (1968)): Mpolyethylene = A x (Mpolystyrene)B (Eq. 1), where M is the molecular weight, A is equal to 0.4316 and B is equal to 1.0.

[00100] The numerical average molecular weight (Mn(gpc conv)), the weight average molecular weight (Mw-gpc conv) and the z average molecular weight (Mz(gpc conv)) were calculated according to Equations 2 to 4 below.

[00101] In Equations 2 to 4, the RV is the column retention volume (linearly spaced), collected at “1 point per second”, the IR is the IR detector signal subtracted from the baseline, in Volts, from the IR5 measurement channel of the GPC instrument, and MPE is the MW equivalent to polyethylene determined from Equation 1. The data calculation was performed in the “GPC One software (version 2.013H)” from PolymerChar.

Creep Zero Shear Viscosity Measurement Method

[00102] Zero shear viscosities were obtained through creep tests, which were performed on a stress-controlled AR-G2 rheometer (TA Instruments; New Castle, Del), using “25 mm diameter” parallel plates, at 190°C. The rheometer oven was set to test temperature for at least 30 minutes before resetting the accessories. At the test temperature, a compression-molded sample disc was inserted between the plates and allowed to equilibrate for five minutes. The top plate was then lowered to 50 μ m (instrument adjustment) above the desired test range (1.5 mm). Any superfluous material was trimmed and the top plate was lowered to the desired slot. Measurements were carried out under nitrogen purge, at a flow rate of 5 l/min. The default creep time was set to two hours. Each sample was molded by compression in a circular plate measuring “2 mm thick x 25 mm in diameter”, at 177°C, for five minutes, under pressure of 10 MPa, in air. The sample was then removed from the press and placed on a bench to cool.

[00103] A constant low shear stress of 20 Pa was applied to all samples, to ensure that the steady-state shear rate was low enough to be in the Newtonian region. The resulting steady-state shear rates were in the range of 10-3 to 10-4 s-1 for the samples in this study. The steady state was determined using a linear regression for all data, in the last 10% of the time window of the “log (J(t)) vs. log(t)”, where J(t) was fluently compliant and it was time to kick ass. If the slope of the linear regression was greater than 0.97, steady state was considered reached, so the creep test was stopped. In all cases in this study, the slope meets the criterion within one hour. The steady-state shear rate was determined from the slope of the linear regression of all data points in the last 10% time window of the “ε vs. t”, where ε was strain. Zero shear viscosity was determined from the ratio of applied stress to steady-state shear rate.

[00104] To determine whether the sample was degraded during the creep test, a small amplitude oscillatory shear test was performed before and after the creep test, on the same sample from 0.1 to 100 rad/s. The complex viscosity values of the two tests were compared. If the difference in viscosity values, at 0.1 rad/s, was greater than 5%, the sample was considered degraded during the creep test and the result was discarded.

[00105] Zero Shear Viscosity Ratio (ZSVR) is defined as the ratio between the zero shear viscosity (ZSV) of the branched polyethylene material and the ZSV of a linear polyethylene material (see ANTEC procedure below) at the average molecular weight equivalent weight (Mw(gpc conv.)) according to the following Equation 5:

[00106] The ZSV value was obtained from the creep test, at 190°C, by the method described above. The Mw value (conv gpc) was determined by the conventional GPC method (Equation 3), as discussed above. The correlation between the ZSV of linear polyethylene and its Mw (gpc conv) was established based on a series of linear polyethylene reference materials. A description for the ZSV-Mw relationship can be found in the ANTEC process: Karjala et al., Detection of Low Levels of Long-chain Branching in Polyolefins, Annual Technical Conference - Society of Plastics Engineers (2008), 66th edition, 887 to 891 .

1H NMR method

[00107] A stock solution (3.26 g) was added to "0.133 g of polymer sample" in a 10 mm NMR tube. The stock solution was a mixture of tetrachloroethane-d2 (TCE) and perchloroethylene (50:50, w:w) with 0.001 M Cr3+. The solution in the tube was purged with N2 for 5 minutes to reduce the amount of oxygen. The capped sample tube was left at room temperature overnight to swell the polymer sample. The sample was dissolved at 110°C with periodic vortex mixing. The samples were free of additives that can contribute to unsaturation, for example, slip agents such as erucamide. Each 1H NMR analysis was performed with a 10 mm cryoprobe, at 120°C, on the Bruker AVANCE 400 MHz spectrometer.

[00108] Two experiments were carried out to obtain unsaturation: the control and double pre-saturation experiments. For the control experiment, data were processed with an exponential window function with LB = 1 Hz, and the baseline was corrected from 7 to -2 ppm. The TCE residual 1H signal was set to 100 and the integral Itotal from -0.5 to 3 ppm was used as the whole polymer signal in the control experiment. The "CH2 group number, NCH2," in the polymer was calculated as follows in Equation 1A:

[00109] For the double pre-saturation experiment, the data was processed with an exponential window function with LB = 1 Hz, and the baseline was corrected from about 6.6 to 4.5 ppm. The signal of the TCE residual 1H was set to 100, and the corresponding integrals for unsaturations (ivynylene, itrisubstituted, ivinyl and ivinylidene) were integrated. It is well known to use NMR spectroscopic methods to determine the unsaturation of polyethylene, for example, see Busico, V., et al., Macromolecules, 2005, 38, 6988. The number of unsaturation units for vinylene, trisubstituted, vinyl and vinylidene was calculated as follows:

[00110] The unsaturation units per 1,000 carbons, all polymers, including spinal and branched bones, were calculated as follows:

[00111] The chemical shift reference was set at 6.0 ppm for the 1H signal from the TCE-d2 residual proton. Control was performed with ZG pulse, NS = 4, DS = 12, SWH = 10,000 Hz, AQ = 1.64s, D1 = 14s. The double presaturation experiment was performed with a modified pulse sequence, with O1P = 1.354 ppm, O2P = 0.960 ppm, PL9 = 57db, PL21 = 70 db, NS = 100, DS = 4, SWH = 10,000 Hz, AQ = 1.64s, D1 = 1 s (where D1 is the pre-saturation time), D13 = 13s. Only vinyl levels were reported in Table 2 below.

13C NMR Method

[00112] Samples are prepared by adding approximately 3 g of a 50/50 mixture of tetra-chloroethane-d2/orthodichlorobenzene, containing 0.025 M Cr(AcAc)3, to a "0.25 g polymer sample" in a 10 mm NMR tube. Oxygen is removed from the sample by purging the headspace of the tube with nitrogen. The samples are then dissolved and homogenized by heating the tube and its contents to 150°C using a heating block and heat gun. Each dissolved sample is visually inspected to ensure homogeneity.

[00113] All data is collected using a Bruker 400 MHz spectrometer. Data is obtained using a 6 second pulse repetition delay, 90 degree rotation angles and inverse decoupling with a sample temperature of 120°C. All measurements are made on unwired samples in locked mode. Samples are allowed to thermally equilibrate for 7 minutes before data acquisition. 13C NMR chemical shifts were internally referenced to the EEE triad at 30.0 ppm.

[00114] C13 Comonomer Content NMR: It is well known to use NMR spectroscopic methods to determine the composition of the polymer. ASTM D 5017-96; J. C. Randall et al., In "NMR and Macromolecules" ACS Symposium series 247; J. Randall, Ed. Am. Chem. Soc., Washington, D.C., 1984, Ch. 9; and J. C. Randall in "Polymer Sequence Determination", Academic Press, New York (1977) provide general methods of analyzing polymers by NMR spectroscopy.

Molecular Weighted Comonomer Distribution Index (MWCDI)

[00115] A GPC-IR high temperature chromatographic system from PolymerChar (Valencia, Spain) was equipped with a two-angle laser light scattering detector from Precmer Detectors (Amherst, MA), model 2040, and an infrared detector IR5 (GPC-IR) and a capillary viscometer 4, both from PolymerChar. The “15 degree angle” of the light scattering detector was used for calculation purposes. Data collection was performed using PolymerChar's Instrument Control software and data collection interface. The system was equipped with a solvent degassing device and pumping system from Agilent Technologies (Santa Clara, CA).

[00116] The injection temperature was controlled at 150 degrees Celsius. The columns used were four 20 micron “Mixed-A” light scattering columns from Polymer Laboratories (Shropshire, UK). The solvent was 1,2,4-trichlorobenzene. Samples were prepared at a concentration of "0.1 grams of polymer in 50 milliliters of solvent." The chromatographic solvent and sample preparation solvent contained "200 ppm butylated hydroxytoluene (BHT)". Both solvent sources were sparged with nitrogen. The ethylene-based polymer samples were gently stirred at 160 degrees Celsius for three hours. The injection volume was “200 microliters” and the flow rate was “1 milliliter/minute”.

[00117] Calibration of the GPC column set was performed with 21 "narrow molecular weight distribution" polystyrene standards, with molecular weights ranging from 580 to 8,400,000 g/mol. These standards were organized into six "cocktail" mixtures, with at least a decade of separation between individual molecular weights. Standards were purchased from Polymer Laboratories (Shropshire UK). 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 at "0.050 grams in 50 milliliters of solvent" for molecular weights less than 1,000,000 g/mol mole. The polystyrene standards were dissolved at 80 degrees Celsius, with gentle stirring, for 30 minutes. Narrow pattern mixtures were run first and in descending order of “highest molecular weight component” to minimize degradation. Standard peak molecular weights of polystyrene were converted to molecular weights of polyethylene using Equation 1B (as described in Williams and Ward, J. Polym. Sci. Polym. Let., 6, 621 (1968)): Mpolyethylene = A x (Mpolystyrene)B (Eq. 1B), where M is the molecular weight, A has a value of approximately 0.40 and B is equal to 1.0. The A value was adjusted between 0.385 and 0.425 (depending on the efficiency of the specific column set) so that the linear weight average molecular weight of NBS 1475A (NIST) polyethylene corresponded to 52,000 g/mol, as calculated by Equation 3B, below: In Equations 2B and 3B, RV is the column retention volume (linearly spaced), collected at "1 point per second". The IR is the baseline-subtracted IR detector signal, in Volts, from the GPC instrument measurement channel and the MPE is the polyethylene equivalent MW determined from Equation 1B. Data calculation was performed using PolymerChar's “GPC One software (version 2.013H)”.

[00118] A calibration for IR5 detector ratios was performed using at least ten ethylene-based polymer standards (polyethylene homopolymer and ethylene/octene copolymers; narrow molecular weight distribution and homogeneous comonomer distribution) of known frequency of short chain branching (SCB) (measured by the 13C NMR Method, as discussed above), ranging from homopolymer (0 SCB/1,000 total C) to approximately 50 SCB/1,000 total C, with total C = carbons above. Each standard had a molecular weight distribution (Mw/Mn) of 2.0 to 2.5, as determined by the GPC-LALS processing method described above. Polymer properties for SCB standards are shown in Table 1. Table 1: "SCB" standards

[00119] The "IR5 Area Ratio (or “IR5 Methyl Channel Area/IR5 Measurement Channel Area”)" from "the response of the area subtracted by the IR5 methyl channel sensor baseline" to "the response of the area subtracted by the IR5" measurement channel sensor baseline (standard filters and filter wheel supplied by PolymerChar: part number IR5_FWM01 included as part of the GPC-IR instrument) was calculated for each of the "SCB" standards . A linear fit of the SCB frequency versus the “IR5 Area Ratio" was constructed in the form of the following Equation 4B:

[00120] SCB/1,000 total C = A0 + [A1 x (IR5 methyl channel area/IR5 measurement channel area)] (Eq. 4B), where A0 is the “SCB/1,000 total C” intercept with an “IR5 Area Ratio” of zero and A1 is the slope of “SCB/1,000 total C” versus “IR% Area Ratio” and represents the increase in “SCB/1,000 total C” as a function of “IR5 Area Ratio”.

[00121] A series of "baseline-subtracted linear chromatographic heights" for the chromatogram generated by the "IR5 methyl channel sensor" was established as a function of the column elution volume, to generate a baseline-corrected chromatogram ( methyl channel). A series of "baseline-subtracted linear chromatographic heights" for the chromatogram generated by the "IR5 measurement channel" was established as a function of the column elution volume, to generate a baseline-corrected chromatogram (measurement channel).

[00122] The "IR5 Height Ratio" of the "baseline-corrected chromatogram (methyl channel)" to "the baseline-corrected chromatogram (measurement channel)" was calculated at each column elution volume index (each index equally spaced, representing 1 data point per second at 1 ml/min elution) across the sample integration limits. The “IR5 height ratio” was multiplied by the A1 coefficient and the A0 coefficient was added to this result, to produce the predicted SCB frequency of the sample. The result was converted into comonomer in molar percentage, as follows in Equation 5B:

[00123] Mol percentage of comonomer = {SCBf/[SCBf + ((1,000 - SCBf * comonomer length)/2)]} * 100 (Eq. 5B), where "SCBf" is the "SCB per 1,000 C total" and the "Comonomer Length" = 8 for octene, 6 for hexene, and so on.

[00124] Each elution volume index was converted into a molecular weight value (Mwi) using the Williams and Ward method (described above; Eq. 1B). The "Molar Percent Comonomer (y-axis)" was plotted as a function of Log (Mwi), and the slope was calculated between Mwi of 15,000 and Mwi of 150,000 g/mol (end group corrections at chain ends were omitted for this calculation). An EXCEL linear regression was used to calculate the slope between and including Mwi from 15,000 to 150,000 g/mol. This slope is defined as the molecular weighted comonomer distribution index (MWCDI = Molecular Weighted Comonomer Distribution Index). Representative Determination of MWCDI

[00125] A plot of the measured “SCB per 1,000 total C (=SCBf)” versus the observed “IR% Area Ratio” of the SCB standards was generated (see Figure 1), and the intercept (A0) and slope (A1 ) were determined. Here, A0 = -90.246 SCB/1,000 C total; and A1 = 499.32 SCB/1,000 total C.

[00126] The “Height Ratio IR5” was determined for the sample composition (see integration shown in Figure 2). This height ratio (Height Ratio IR5) was multiplied by the coefficient A1 and the coefficient A0 was added to this result , to produce the predicted SCB frequency from this example, at each elution volume index, as described above (A0 = - 90.246 SCB/1,000 C total and A1 = 499.32 SCB/1,000 C total). The SCBf was plotted in function of the polyethylene equivalent molecular weight, as determined using Equation 1B, as discussed above, see FIG. 4 (Log Mwi used as x-axis).

[00127] SCBf was converted into "Mole Percent Comonomer" through Equation 5B. The "Mole Percent Comonomer" was plotted against the polyethylene equivalent molecular weight, as determined using Equation 1B, as discussed above. See FIG. 5 (Log Mwi used for x-axis). A linear fit was from Mwi of 15,000 g/mol to Mwi of 150,000 g/mol, yielding a slope of "2.27 mol percent comonomer x mole/g." Thus, the MWCDI = 2.27. An EXCEL linear regression was used to calculate the slope between and including Mwi from 15,000 to 150,000 g/mol. Puncture Resistance

[00128] Puncture resistance is measured on a dynamometer in accordance with ASTM D5748 in standard laboratory atmosphere, such as a temperature of 23 ± 2°C. Instrumented Dart Impact

[00129] Instrumented Dart Impact, which is measured in accordance with ASTM D3763, is the total energy required to pierce a material by impact with a falling dart under specified test conditions. Here, a 12.7 mm (0.5 in) diameter semi-spherical head dart was thrown from a height of 66 cm.

EXAMPLES

[00130] The following examples illustrate features of the present disclosure, but are not intended to limit the scope of the disclosure.

Commercial Polymers Used

[00131] The following compositions listed in Table 3 were included in the thermoformed monolayer and multilayer examples discussed below. * Binding Resin 1 corresponds to Inventive Binding Layer 1, which has a composition and manufacturing method described in Table 5 of PCT Publication WO2017/053221, which is incorporated by reference herein in its entirety. First Inventive Compositions 1 to 3

[00132] The First Inventive Compositions 1-3 each contain two ethylene-octene copolymers. Each composition was prepared, via solution polymerization, in a dual series loop reactor system in accordance with US patent 5,977,251 (see Figure 2 of this patent), in the presence of a first catalyst system, as described below , in the first reactor, and a second catalyst system, as described below, in the second reactor.

[00133] The first catalyst system comprised a bis((2-oxoyl-3-(dibenzo-1H-pyrrol-1-yl)-5-(methyl)phenyl)-2-phenoxymethyl)-methylene-1,2-cyclo - hexanediyl-inium (IV) dimethyl, represented by the following formula (CAT 1):

[00134] The molar ratios of the metal of CAT 1, added to the in situ polymerization reactor, to that of Cocat1 (modified methyl aluminoxane) or Cocat2 (bis(hydrogenated tallow alkyl))methyl, tetracis(pentafluorophenyl)(1-)amine )borate, are shown in Table 4 below.

[00135] The second catalyst system comprised a Ziegler-Natta type catalyst (CAT 2). The heterogeneous catalyst premix of the Ziegler-Natta type was prepared substantially in accordance with US Patent 4,612,300, by sequentially adding to a volume 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 produce 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 produce a final concentration of 500 ppm Ti in the paste. When fed and before entering the polymerization reactor, the catalyst premix was contacted with a diluted Et3Al solution, at the Al/Ti molar ratio specified in Table 4, to provide the active catalyst.

[00136] The polymerization conditions for First Inventive Compositions 1 to 3 are reported in Table 4. As seen in Table 4, Cocat. 1 (modified methyl aluminoxane (MMAO)); and Cocat. 2(bis(hydrogenated tallow alkyl)methyl, tetracis(pentafluorophenyl)borate(1-)amine) were used as cocatalysts for CAT 1. Additional properties of First Inventive Compositions 1 to 3 were measured and are reported in Table 5. Each composition of polymer was stabilized with smaller amounts (ppm) of stabilizers. Table 4: Polymerization Conditions (Rx1 = reactor 1; Rx2 = reactor 2) *solvent = ISOPAR E Table 5: Properties of the First Inventive Compositions 1-3 Example 1: Monolayer Films

[00137] Referring to Table 6 below, various monolayer films were produced on a Collin 5-Layer Coextrusion Blown Film Line according to the following parameters given in Table 7. Table 7: Monolayer Film

[00138] The monolayer films were thermoformed using an R145 Multivac thermoforming machine using the following thermoforming parameters provided in Table 8.

[00139] Puncture resistance for pre-thermoforming and post-thermoforming of monolayer films is provided in Figure 5. As shown, monolayer films comprising First Inventive Compositions 1 and 2 showed marked improvement (e.g., at least 10%) in puncture resistance after undergoing thermoforming, whereas comparative conventional monolayer films generally showed a decrease in puncture resistance or a very marginal increase. Example 2: Thermoformed Multi-Layer Films (Cast Film Extrusion)

[00140] The following multilayer films from Table 9 had a 5-layer ABCDE structure produced by cast film extrusion. The thickness percentages of each layer are also provided in Table 9. Table 9 - Film Samples 1 and 2 and Comparative Film Samples C1-C3 *C1-C3 represents Comparative Film Samples 1-3

[00141] The multi-layer films were produced on a Dow Freeport 5-Layer Cast Extrusion Film Line, with the following characteristics provided in Table 10.

[00142] The multilayer films of Table 9 were thermoformed into pouches using an R145 Multivac thermoforming machine with the following thermoforming parameters provided in Table 8.

[00143] Dart performance, specifically, Instrumented Dart Performance, for pouches after thermoforming are provided in Figure 6. As shown, Inventive Sample 1, which includes First Inventive Composition 3, has an Instrumented Dart Impact twice the value of the Comparative Samples, C2 and C3, and is approximately 10 times the value of the Comparative Sample C3. Example 3: Thermoformed Multi-Layer Films (Blown Film Extrusion)

[00144] The following multilayer films of Table 11 had a 5-layer ABCDE structure produced by blown film extrusion. All films had a thickness of 100 μm. Table 11 - Film Samples 1 and 2 and Comparative Film Samples C1-C3 *C4-C6 represents Comparative Examples 4-6

[00145] The multi-layer films of Table 11 were produced on a Collin 5-Layer Coextrusion Blown Film Line, with the following characteristics provided in Table 12.

[00146] The multi-layer films of Table 11 were thermoformed using an R145 Multivac thermoforming machine into pouches using the thermoforming parameters given in Table 8 above, with the exception that the depth is 80 mm for the multi-layer films from Table 11.

[00147] Puncture resistance for the pre-thermoforming and post-thermoforming multilayer films is provided in Figure 7. As shown, the inventive multilayer films (Samples 3, 4 and 6), which comprise the Inventive First Compositions 1 or 2, showed improvement in puncture resistance after undergoing thermoforming. Sample 5 also showed marginal improvement in puncture resistance; however, Sample 5 already had a high level of puncture resistance prior to thermoforming.

[00148] Comparative Sample 4 (multilayer film containing nylon), Comparative Sample 5 (multilayer film containing Nylon and EVOH) and Comparative Sample 6 (multilayer film containing EVOH) include polyamide and/or EVOH, which are commonly used in thermoformed packaging. The inventive samples (Samples 3-6) achieved comparable puncture resistance and adequate dart performance and stiffness, albeit utilizing a monomaterial packaging (i.e., ethylene-based polymer only). In Inventive Sample 7, which combines First Inventive Composition 2 and EVOH, there is a significant increase in puncture resistance after thermoforming, thus indicating synergistic benefits when including EVOH and the first inventive composition.

[00149] Additionally, Samples 5 and 6, which both include the First Inventive Composition 2 having a density of 0.926, demonstrated additional surprising results. As shown, Sample 5, which included 40% of the total thickness of the First Inventive Composition 2, maintained its puncture resistance after thermoforming. However, for Sample 6, which included 60% of the total thickness of the First Inventive Composition 2, the puncture resistance greatly increased after thermoforming.

[00150] It will be clear that modifications and variations are possible without departing from the scope of disclosure defined in the attached claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to those aspects.

Claims (14)

1. Thermoformed multilayer film structure, characterized by the fact that it comprises: a core layer and at least two outer layers disposed externally relative to the core layer, wherein at least one layer of the thermoformed multilayer film structure comprises a first composition comprising at least one ethylene-based polymer, the first composition comprising a Molecular Weighted Comonomer Distribution Index (MWCDI) value greater than 1.2, and a melt index ratio (I10/I2) which meets the following equation: I wherein the thermoformed multilayer film is a thermoformed blown film; and wherein the melt index I2 is measured in accordance with ASTM D-1238 at 190°C at 2.16 kg; and MWCDI is measured according to the method described in the report. 2. Thermoformed multilayer film structure according to claim 1, characterized in that the thermoformed multilayer film structure comprises at least one of polyamide, ethylene vinyl alcohol (EVOH) and maleated polyolefins. 3. Thermoformed multilayer film structure according to any one of claims 1 or 2, characterized in that the thermoformed multilayer film structure is substantially free of propylene-based polymers. 4. Thermoformed multilayer film structure according to any one of claims 1 to 3, characterized in that the thermoformed multilayer film structure consists essentially of ethylene-based polymers. 5. Thermoformed multilayer film structure according to any one of claims 1 to 4, characterized in that the core layer comprises the first composition. 6. Thermoformed multilayer film structure according to any one of claims 1 to 5, characterized in that at least one of the outer layers comprises the first composition. 7. Thermoformed multilayer film structure according to claim 6, characterized in that the ethylene-based polymer is an ethylene-α-olefin interpolymer, wherein the α-olefin comprises one or more C3-C12 olefins. 8. Thermoformed multilayer film structure according to any one of claims 1 or 2, characterized in that at least one of the outer layers comprises propylene-based polymers. 9. Thermoformed multilayer film structure according to any one of claims 1 to 8, characterized in that the thermoformed multilayer film structure has a total thickness of 50 to 250 μm. 10. Thermoformed monolayer film, characterized by the fact that it comprises: a first composition comprising at least one ethylene-based polymer, the first composition comprising a Molecular Weighted Comonomer Distribution Index (MWCDI) value greater than 1.2 and a melt index ratio (I10/I2) that meets the following equation: wherein the thermoformed monolayer film demonstrates an increase in puncture resistance of at least 10% due to thermoforming applications; wherein the thermoformed monolayer film is a thermoformed blow film, and wherein the melt index (2 is measured in accordance with ASTM D-1238 at 190°C at 2.16 kg; and MWCDI is measured in accordance with the method described in the report. 11. Thermoformed monolayer film according to claim 10, characterized in that the thermoformed monolayer film structure consists essentially of ethylene-based polymer. 12. Thermoformed monolayer film according to any one of claims 10 or 11, characterized in that the thermoformed monolayer film structure has a total thickness of 50 to 250 μm. 13. Article, characterized by the fact that it comprises the thermoformed multilayer film structure defined in any one of claims 1 to 9, or the thermoformed monolayer film structure defined in any one of claims 10 to 12. 14. Article according to claim 13, characterized in that the article is a flexible packaging material.