Oriented polyethylene film and articles containing same

Abstract

The present invention relates to an oriented multilayer polyethylene film. In one embodiment, the biaxially oriented multilayer polyethylene film comprises: (1) (a) at least 97 wt. % of a polyethylene composition, based on the total weight of the polyethylene composition; (i) 0.935 to 0.947 g / cm 3 and a melt index (I2) of less than 0.1 g / 10 minutes; and (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene composition, wherein the nucleating agent comprises a calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate, and the polyethylene composition comprises: 13 and a density of at least 0.965 g / cm. 3 The melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 min.

Description

[Technical field]

[0001] The present invention relates to oriented multilayer polyethylene films, laminates comprising such films, and articles comprising such films and laminates. [Background technology]

[0002] As global interest in reducing packaging waste and improving the sustainability of flexible packaging grows, more and more efforts are being made to develop materials and technologies that can enhance the sustainability of flexible packaging. Flexible packaging film structures are often formed from multiple types of polymeric materials, including, for example, polyethylene, polypropylene, ethylene vinyl alcohol, polyethylene terephthalate, polyamide, etc. Such materials are typically combined to achieve a balance of properties that cannot be reached with a single material type. However, because these materials are heterogeneous, the final packaging is typically not easy to recycle. Thus, there is also a move toward single-component structures (e.g., all-polyethylene structures) to improve recyclability profiles. For example, for all-polyethylene structures, certain performance metrics (e.g., mechanical properties) need to be enhanced to improve recyclability while still maintaining the performance levels expected of these structures when formed from different polymeric materials. Thus, new resins and processing techniques are needed to fill the performance deficiencies of polyethylene compared to other material types.

[0003] One such relatively new material technology on the processing side is biaxially oriented polyethylene (BOPE) film. Such BOPE films are formed by cast extrusion and then oriented in the machine direction (MD) followed by transverse direction (TD) orientation in a tenter frame. Alternatively, the processes can also be carried out simultaneously. It is often difficult to biaxially orient conventional polyethylene due to the molecular structure, microstructure, and crystallization kinetics of polyethylene.

[0004] It would be desirable to have new polyethylene-based compositions that have good processability into biaxially oriented polyethylene films, and new biaxially oriented polyethylene films that have desired and / or improved properties. It would also be desirable to have new polyethylene-based compositions that have good processability into uniaxially oriented (e.g., machine direction oriented) polyethylene films, and new uniaxially oriented polyethylene films that have desired and / or improved properties. Summary of the Invention

[0005] The present invention provides polyethylene-based compositions suitable for processing into biaxially oriented multilayer polyethylene films, as well as biaxially oriented multilayer polyethylene films having desired and / or improved properties. Such polyethylene-based compositions, in some embodiments, can advantageously widen the operating window for stretching the film to provide a biaxially oriented polyethylene film. For example, by widening the operating window for biaxial orientation, higher density polyethylene can be oriented, resulting in improved film stiffness. Other advantages may include, but are not limited to, better converting and printability of the film, improved optics (e.g., higher clarity and lower haze), improved barrier performance of metallized biaxially oriented polyethylene films, and improved processability in larger and wider tenter frames. The present invention also provides polyethylene-based compositions suitable for processing into uniaxially oriented (e.g., machine direction oriented) multilayer polyethylene films, as well as uniaxially oriented multilayer polyethylene films having desired and / or improved properties.

[0006] In one embodiment, the biaxially oriented multilayer polyethylene film comprises: (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 0.935-0.947 g / cm 3and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition comprising 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising a calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate; The polyethylene composition is 13 and a density of at least 0.965 g / cm3. 3 The melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 minutes.

[0007] In another aspect, the invention relates to an article, such as a food package, hi one aspect, the article comprises any of the biaxially oriented multilayer polyethylene films disclosed herein.

[0008] In another aspect, the present invention relates to laminates and articles formed from such laminates. In some embodiments, the laminate comprises a first film comprising a polyethylene-based sealant film, polyethylene terephthalate, polypropylene, or polyamide, and an oriented multilayer polyethylene film according to any of the embodiments disclosed herein, the first film being laminated to the multilayer polyethylene film. In one aspect, the article comprises any of the laminates disclosed herein.

[0009] These and other embodiments are described in greater detail in the detailed description. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Unless stated to the contrary, implied from the context, or customary in the art, all parts and percentages are by weight, all temperatures are in degrees Celsius, and all test methods are current as of the filing date of this disclosure.

[0011] The term "composition," as used herein, refers to a mixture of materials that comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0012] "Polymer" means a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the generic term polymer encompasses the term homopolymer, defined below, and the term interpolymer, defined below. Trace amounts of impurities (e.g., catalyst residues) may be incorporated in and / or within the polymer. The polymer may be a single polymer, a polymer blend, or a polymer mixture, including a mixture of polymers formed in situ during polymerization.

[0013] As used herein, the term "homopolymer" refers to a polymer prepared from only one type of monomer, with the understanding that trace amounts of impurities may be incorporated into the polymer structure.

[0014] As used herein, the term "interpolymer" refers to a polymer prepared by the polymerization of at least two different types of monomers. Thus, the generic term interpolymer includes copolymers (used to refer to polymers prepared from two different types of monomers) and polymers prepared from three or more different types of monomers.

[0015] As used herein, the terms "olefin-based polymer" or "polyolefin" refer to a polymer that contains, in polymerized form (based on the weight of the polymer), a majority amount of olefin monomer, such as ethylene or propylene, and may optionally contain one or more comonomers.

[0016] As used herein, the term "ethylene / α-olefin interpolymer" refers to an interpolymer that contains, in polymerized form, a majority (>50 mol%) of units derived from ethylene monomer and the remainder being derived from one or more α-olefins. Typical α-olefins used to form ethylene / α-olefin interpolymers are C3-C 10 It is an alkene.

[0017] As used herein, the term "ethylene / α-olefin copolymer" refers to a copolymer that contains, in polymerized form, a majority amount (>50 mole %) of ethylene monomer and an α-olefin as the only two monomers.

[0018] As used herein, the term "α-olefin" refers to an alkene with a double bond in the first or alpha (α) position.

[0019] "Polyethylene" or "ethylene-based polymer" shall mean a polymer containing units derived from a majority (>50 mol%) of ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning that the units are derived from two or more comonomers). Common forms of polyethylene known in the art include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (ULDPE), single-site catalyzed linear low density polyethylene (m-LLDPE), which includes both linear and substantially linear low density resins, ethylene-based plastomers (POP) and ethylene-based elastomers (POE), medium density polyethylene (MDPE), and high density polyethylene (HDPE). These polyethylene materials are generally known in the art, but the following explanation may be helpful in understanding the differences between some of these different polyethylene resins.

[0020] The term "LDPE" may also be referred to as "high pressure ethylene polymer", or "highly branched polyethylene", and is defined to mean that the polymer is partially or fully homopolymerized or copolymerized in an autoclave or tubular reactor at pressures in excess of 14,500 psi (100 MPa) using a free radical initiator, such as peroxide (see, for example, U.S. Pat. No. 4,599,392, incorporated by reference). LDPE resins typically have a viscosity of 0.916 to 0.935 g / cm. 3 The density is in the range of

[0021] The term "LLDPE" includes both resins made using single-site catalysts, including, but not limited to, traditional Ziegler-Natta catalyst systems and chromium-based catalysts, as well as mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes) and constrained geometry catalysts, phosphinimine and polyaryloxy ether catalysts (typically referred to as bisphenylphenoxy), and 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 No. 3,914,342 or U.S. Patent No. 5,854,045). LLDPE may be made by gas phase, liquid phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0022] The term "MDPE" means 0.926 to 0.935 g / cm 3"MDPE" refers to polyethylene having a density of greater than 2.5, typically produced using chromium or Ziegler-Natta catalysts, or using single-site catalysts, including but not limited to substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts, and polyaryloxy ether catalysts (typically referred to as bisphenylphenoxys), and typically has a molecular weight distribution ("MWD") greater than 2.5.

[0023] The term "HDPE" refers to any polymer having a viscosity of about 0.935 g / cm, typically prepared using a single-site catalyst, including, but not limited to, Ziegler-Natta, chromium, or substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphimine catalysts, and polyaryloxy ether catalysts (typically referred to as bisphenylphenoxy). 3 Super ~ maximum approx. 0.980g / cm 3 It refers to polyethylene having a density of

[0024] The term "ULDPE" refers to poly(ethylene glycol densitometer-type) polymers having a viscosity of 0.855 to 0.912 g / cm, typically prepared using single-site catalysts including, but not limited to, Ziegler-Natta, chromium, or substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts, and polyaryloxy ether catalysts (typically referred to as bisphenylphenoxy). 3 ULDPE refers to polyethylene having a density of 0.855 to 0.912 g / cm3. ULDPE includes, but is not limited to, polyethylene (ethylene-based) plastomers and polyethylene (ethylene-based) elastomers. Polyethylene (ethylene-based) elastomer plastomers generally have a density of 0.855 to 0.912 g / cm3. 3 has a density of

[0025] The terms "blend", "polymer blend" and the like refer to a composition of two or more polymers. Such blends may or may not be miscible. Such blends may or may not be phase separated. Such blends may or may not contain one or more domain configurations as determined from transmission electron spectroscopy, light scattering, X-ray scattering, and any other method known in the art. A blend is not a laminate, although one or more layers of a laminate may contain the blend. Such blends may be prepared as dry blends or may be formed in situ (e.g., in a reactor), as melt blends, or using other techniques known to those skilled in the art.

[0026] The terms "comprising," "including," "having," and their derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether they are specifically disclosed or not. For the avoidance of any doubt, all compositions claimed through the use of the term "comprising" may include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless otherwise stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any ensuing description any other components, steps, or procedures, except those that are not essential to operability. The term "consisting of" excludes any components, steps, or procedures not specifically defined or listed.

[0027] The present invention generally relates to oriented multilayer polyethylene films. In some embodiments, such films are biaxially oriented. In some embodiments, such films are biaxially oriented using a tenter frame. In some embodiments, such films are uniaxially oriented in the machine direction. The oriented multilayer polyethylene films utilize a polyethylene-based composition in at least one layer that can advantageously expand the operating window for stretching the film. For example, by expanding the operating window for biaxial orientation, higher density polyethylene can be oriented, resulting in improved film stiffness. The oriented multilayer polyethylene films can be used in packaging applications in some embodiments.

[0028] In one embodiment, the biaxially oriented multilayer polyethylene film comprises: (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 0.935-0.947 g / cm 3 and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition comprising 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising a calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate; The polyethylene composition is 13 and a density of at least 0.965 g / cm3. 3 The melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 minutes.

[0029] In another aspect, the biaxially oriented multilayer polyethylene film comprises: (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 0.935-0.947 g / cm 3 and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition comprising 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising sodium 4-[(4-chlorobenzoyl)amino]benzoate; The polyethylene composition is 13 and a density of at least 0.965 g / cm3. 3 The melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 minutes.

[0030] In another aspect, the biaxially oriented multilayer polyethylene film comprises: (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 0.935-0.947 g / cm 3 and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition comprising 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising a calcium salt of 1,2-cyclohexanedicarboxylic acid; The polyethylene composition is13 and a density of at least 0.965 g / cm3. 3 The melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 minutes.

[0031] In some embodiments, the polyethylene-based composition comprises 20 to 2000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition.

[0032] In some embodiments, the biaxially oriented film is oriented in the machine direction with a stretch ratio of 2:1 to 9:1 and in the transverse direction with a stretch ratio of 2:1 to 11:1. In some embodiments, the biaxially oriented film is oriented in the machine direction with a stretch ratio of 2:1 to 6:1 and in the transverse direction with a stretch ratio of 2:1 to 9:1. In some embodiments, the biaxially oriented film is oriented in the machine direction with a stretch ratio of 4:1 to 6:1 and in the transverse direction with a stretch ratio of 6:1 to 9:1.

[0033] In some embodiments, the biaxially oriented multilayer polyethylene film further comprises a second polyethylene composition, the second polyethylene composition exhibiting at least two local peaks in the comonomer distribution measured by crystallization elution fractionation, excluding the soluble fraction, one of the peaks being between 40°C and 95°C. In some embodiments, the second polyethylene composition exhibiting at least two local peaks in the comonomer distribution measured by crystallization elution fractionation, excluding the soluble fraction, one of the peaks being between 40°C and 90°C. In some embodiments, the second polyethylene composition exhibiting at least two local peaks in the comonomer distribution measured by crystallization elution fractionation, excluding the soluble fraction, one of the peaks being between 40°C and 87 ... has a viscosity of 0.928 to 0.940 g / cm 3 In some embodiments, the layer comprising the polyethylene-based composition further comprises a second polyethylene composition.

[0034] In some embodiments, the overall density of the biaxially oriented multilayer film is from 0.931 to 0.975 g / cm 3 It is.

[0035] In some embodiments, the biaxially oriented multilayer film has a thickness of from 5 to 50 microns.

[0036] The biaxially oriented multilayer film, some embodiments, further comprises a layer comprising polyamide or ethylene vinyl alcohol.

[0037] In some embodiments, the biaxially oriented multilayer film further comprises an outer layer that is a sealant layer.

[0038] In some embodiments, the biaxially oriented multilayer film further comprises a layer comprising a metal deposited on an outer layer of the film, the metal comprising Al, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, Si, Mg, or an oxide thereof.

[0039] In another aspect, the invention relates to an article, such as a food package, hi one aspect, the article comprises any of the inventive biaxially oriented multilayer polyethylene films disclosed herein.

[0040] In another aspect, the present invention relates to a laminate and an article formed from such a laminate. In some embodiments, the laminate comprises a first film comprising a polyethylene-based sealant film, polyethylene terephthalate, polypropylene, or polyamide, and a biaxially oriented multilayer polyethylene film according to any of the embodiments disclosed herein, the first film being laminated to the multilayer polyethylene film. In one aspect, the article comprises any of the laminates disclosed herein.

[0041] In another aspect, the present invention relates to a uniaxially oriented multilayer polyethylene film, (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 0.935-0.947 g / cm 3 and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition comprising 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising a calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate; The polyethylene composition is 13 and a density of at least 0.965 g / cm3. 3 and the melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 min. In some embodiments, the film is oriented in the machine direction.

[0042] In another aspect, the present invention relates to a uniaxially oriented multilayer polyethylene film, (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 0.935-0.947 g / cm 3 and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition including 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent including a calcium salt of 1,2-cyclohexanedicarboxylic acid; The polyethylene composition is 13 and a density of at least 0.965 g / cm3. 3 and the melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 min. In some embodiments, the film is oriented in the machine direction.

[0043] In another aspect, the present invention relates to a uniaxially oriented multilayer polyethylene film, (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 0.935-0.947 g / cm 3 and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition comprising 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising sodium 4-[(4-chlorobenzoyl)amino]benzoate; The polyethylene composition is 13 and a density of at least 0.965 g / cm3. 3 and the melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 min. In some embodiments, the film is oriented in the machine direction.

[0044] In some embodiments, the uniaxially oriented film is oriented in the machine direction with a stretch ratio of 4:1 to 20:1. In some embodiments, the uniaxially oriented film is oriented in the machine direction with a stretch ratio of 4:1 to 16:1. In some embodiments, the uniaxially oriented film is oriented in the machine direction with a stretch ratio of 4:1 to 12:1. In some embodiments, the uniaxially oriented film is oriented in the machine direction with a stretch ratio of 4:1 to 10:1. In some embodiments, the uniaxially oriented film is oriented in the machine direction with a stretch ratio of 4:1 to 9:1.

[0045] In some embodiments, the uniaxially oriented multilayer polyethylene film further comprises a second polyethylene composition, the second polyethylene composition exhibiting at least two local peaks, excluding the soluble fraction, in a comonomer distribution as measured by crystallization elution fractionation, one of the peaks being between 40°C and 95°C. In some embodiments, the fraction forming the peak at 40°C to 95°C is up to 50 weight percent of the composition as measured by crystallization elution fractionation. In some embodiments, the second polyethylene composition exhibiting at least two local peaks, excluding the soluble fraction, in a comonomer distribution as measured by crystallization elution fractionation, one of the peaks being between 40°C and 90°C. In some embodiments, the second polyethylene composition exhibiting at least two local peaks, excluding the soluble fraction, in a comonomer distribution as measured by crystallization elution fractionation, one of the peaks being between 40°C and 87°C. In some embodiments, the second polyethylene composition has a viscosity of 0.928 to 0.940 g / cm 3 In some embodiments, the layer comprising the polyethylene-based composition further comprises a second polyethylene composition.

[0046] In some embodiments, the overall density of the uniaxially oriented multilayer film is between 0.931 and 0.975 g / cm 3 It is.

[0047] In some embodiments, the uniaxially oriented multilayer film has a thickness of from 5 to 50 microns.

[0048] The uniaxially oriented multilayer film, some embodiments, further comprises a layer comprising polyamide or ethylene vinyl alcohol.

[0049] In some embodiments, the uniaxially oriented multilayer film further comprises an outer layer that is a sealant layer.

[0050] In some embodiments, the uniaxially oriented multilayer film further comprises a layer comprising a metal deposited on an outer layer of the film, the metal comprising Al, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, Si, Mg, or an oxide thereof.

[0051] In another aspect, the invention relates to an article, such as a food package, hi one aspect, the article comprises any of the inventive uniaxially oriented multilayer polyethylene films disclosed herein.

[0052] In another aspect, the present invention relates to a laminate and an article formed from such a laminate. In some embodiments, the laminate comprises a first film comprising a polyethylene-based sealant film, polyethylene terephthalate, polypropylene, or polyamide, and a uniaxially oriented multilayer polyethylene film according to any of the embodiments disclosed herein, the first film being laminated to the multilayer polyethylene film. In one aspect, the article comprises any of the laminates disclosed herein.

[0053] Polyethylene Composition As described above, the biaxially oriented (or uniaxially oriented) multilayer film of the present invention comprises at least one layer comprising a polyethylene-based composition having specific properties. The polyethylene-based composition used in the embodiment of the present invention has (i) a polyethylene content of 0.935 to 0.947 g / cm 3 and a melt index (I2) of less than 0.1 g / 10 minutes, (ii) from 25 to 37 weight percent of a first polyethylene fraction having a density in the range of 13and a density of at least 0.965 g / cm3. 3 The melt index (I2) of the polyethylene composition is 0.5 to 10 g / 10 minutes.

[0054] In some embodiments, the polyethylene-based composition has a melt index (I2) less than or equal to 2.5 g / 10 min.

[0055] In some embodiments, the polyethylene composition has a viscosity of 0.940 to 0.947 g / cm 3 and 25 to 37 weight percent of a first polyethylene fraction having a density in the range of 0.970 g / cm 3 and 63 to 75 weight percent of a second polyethylene fraction having a density equal to or greater than 63 to 75 weight percent.

[0056] The polyethylene composition may comprise a combination of two or more embodiments as described herein.

[0057] In one embodiment, the polyethylene composition has a viscosity of at least 0.965 g / cm 3 In some embodiments, the polyethylene composition has a density of at least 0.968 g / cm 3 The polyethylene composition, in some embodiments, has a density of up to 0.976 g / cm 3 In some embodiments, the polyethylene composition has a density of 0.965 to 0.976 g / cm 3 , for example, 0.965 to 0.970, or 0.967 to 0.969, or 0.965 to 0.970 g / cm 3 For example, the density may be 0.965 or 0.967 g / cm 3 Lower limit ~ 0.970, 0.972, 0.975, or 0.976 g / cm 3 may be an upper limit of

[0058] The polyethylene composition has a melt index (I2 or I2 at 190° C. / 2.16 kg) of 0.5 to 10 g / 10 min. For example, the melt index (I2 or I2 at 190° C. / 2.16 kg) can be from a lower limit of 0.5, 0.7, 0.9, 1.0, 1.1, 1.2, 1.5, 2, 3, 4, or 5 g / 10 min to an upper limit of 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, or 10 g / 10 min. In some embodiments, the polyethylene composition has a melt index (I2) of 0.5 to 5 g / 10 min, or 0.5 to 2.5 g / 10 min, or 0.7 to 3 g / 10 min, or 1.0 to 2.0 g / 10 min, or 1.0 to 1.5 g / 10 min.

[0059] In some embodiments, the polyethylene composition has a melt index ratio (I 10 The polyethylene composition, in some embodiments, has a melt index ratio (I / I2) of up to 17. 10 In some embodiments, the polyethylene composition has a melt index ratio (I / I2) of 10 to 17. 10 The polyethylene composition, in some embodiments, has a melt index ratio (I / I2) of 12 to 17. 10 / I2).

[0060] The polyethylene composition has a low level of branching. In some embodiments, the polyethylene composition comprises: 13 The polyethylene composition has less than 0.10 branches per 1,000 carbon atoms as measured using C NMR. In some embodiments, the polyethylene composition comprises: 13 The polyethylene composition has less than 0.07 branches per 1,000 carbon atoms as measured using C NMR. In some embodiments, the polyethylene composition comprises: 13 In some embodiments, the polyethylene composition has less than 0.05 branches per 1,000 carbon atoms as measured using C NMR. 13 It has less than 0.03 branches per 1,000 carbon atoms as measured using C NMR.

[0061] In some embodiments, the polyethylene composition has a low level of non-vinyl unsaturation. In some embodiments, the polyethylene composition has 1 The polyethylene composition has less than 25 non-vinyl unsaturations per million carbon atoms as measured using H NMR. In some embodiments, the polyethylene composition comprises: 1 It has less than 20 non-vinyl unsaturations per million carbon atoms as determined using H NMR.

[0062] Without wishing to be bound by theory, it is believed that the combination of low levels of branching and low levels of non-vinyl unsaturation in the polyethylene composition provides a higher amount of crystallinity in the polyethylene composition, thereby improving its barrier properties when formed into a film.

[0063] In one embodiment, the polyethylene composition has a ZSVR value of less than 2.0, or from 1.0 to 2.0, or from 1.2 to 1.8, or from 1.3 to 1.7.

[0064] In one embodiment, the polyethylene composition has a ratio of weight average molecular weight to number average molecular weight (M w / M n , measured by conventional GPC), is in the range of 8.0 to 14.0. w / M n ) can range from a lower limit of 8.0, 8.5, 9.0, or 9.5 to an upper limit of 10.0, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, or 14.0. w / M n is 10.0 to 12.0.

[0065] In one embodiment, the polyethylene composition has a number average molecular weight (M nFor example, the number average molecular weight can be from a lower limit of 8,000, 9,000, 10,000, or 11,000 g / mol to an upper limit of 12,000, 13,000, 15,000, or 20,000 g / mol.

[0066] In one embodiment, the polyethylene composition has a weight average molecular weight (M w For example, the weight average molecular weight can be from a lower limit of 100,000, 105,000, or 110,000 g / mol to an upper limit of 115,000, 120,000, or 124,000 g / mol.

[0067] In one embodiment, the polyethylene composition has a z-average molecular weight (M) of at least 350,000 g / mol, such as in the range of 350,000 to 600,000 g / mol. Z For example, the z-average molecular weight can be from a lower limit of 350,000, 375,000, 400,000, 405,000, or 410,000 g / mol to an upper limit of 420,000, 425,000, 450,000, 475,000, 500,000, 550,000, or 600,000 g / mol.

[0068] In one embodiment, the polyethylene composition has an M z / M w The polyethylene composition, in some embodiments, has a M ratio of greater than 3.5 (each determined by conventional GPC). z / M w ratio (each determined by conventional GPC). z / M w may be 3.0 to 4.0 in some embodiments, or 3.5 to 4.5 in some embodiments, or 3.5 to 4.0 in some embodiments.

[0069] In one embodiment, the polyethylene composition has a ZSVR of less than 2.0 and a M of greater than 3.0. z / Mw In another embodiment, the polyethylene composition has a ZSVR of less than 2.0 and a M z / M w ratio (each determined by conventional GPC).

[0070] The polyethylene composition preferably comprises an ethylene-based polymer formed in the absence of a comonomer. In some embodiments, the polyethylene composition comprises at least 99 wt% of an ethylene-based polymer formed in the absence of a comonomer. In some embodiments, the polyethylene composition comprises at least 99 wt% of a polymer comprising a majority (>99 mol%) of units derived from ethylene monomer.

[0071] The polyethylene composition used in the polyethylene-based composition of the present invention comprises two fractions of polyethylene.

[0072] The first polyethylene fraction has a viscosity of 0.935 to 0.947 g / cm 3 In some embodiments, the first polyethylene fraction has a density of 0.940 to 0.947 g / cm 3 The first polyethylene fraction has a melt index (I2) of less than 0.1 g / 10 min. In some embodiments, the first polyethylene fraction has a melt index (I2) of 0.01 g / 10 min or greater. In some embodiments, the first polyethylene fraction has a melt index of 0.05 to 0.1 g / 10 min. In some embodiments, the first polyethylene fraction has 13 It has less than 0.10 branches per 1,000 carbon atoms as measured using C NMR.

[0073] In some embodiments, the second polyethylene fraction has a viscosity of 0.970 g / cm 3 In some embodiments, the first polyethylene fraction has a density of 0.940 to 0.947 g / cm 3and the second polyethylene fraction has a density of 0.970 g / cm 3 In some embodiments, the second polyethylene fraction has a melt index (I2) of at least 100 g / 10 min. In some embodiments, the second polyethylene fraction has a melt index (I2) of at least 100 g / 10 min and up to 10,000 g / 10 min or more. The second polyethylene fraction has a melt index (I2) of at least 100 g / 10 min and up to 10,000 g / 10 min. The second polyethylene fraction has a melt index (I2) of at least 100 g / 10 min and up to 1,000 g / 10 min.

[0074] In some embodiments, the ratio of the melt index (I2) of the second polyethylene fraction to the melt index (I2) of the first polyethylene fraction is at least 1,000.

[0075] The polyethylene composition comprises 25 to 37 weight percent of the first polyethylene fraction and 63 to 75 weight percent of the second polyethylene fraction, based on the total weight of the polyethylene composition. In some embodiments, the polyethylene composition comprises 30 to 37 weight percent of the first polyethylene fraction and 63 to 70 weight percent of the second polyethylene fraction, based on the total weight of the polyethylene composition.

[0076] The polyethylene-based composition comprises at least 97 wt% of the polyethylene composition, based on the total weight of the polyethylene-based composition. In some embodiments, the polyethylene-based composition comprises up to 99 wt% of the polyethylene composition, based on the total weight of the polyethylene-based composition. In some embodiments, the polyethylene-based composition comprises 97 wt%-98 wt% of the polyethylene composition, based on the total weight of the polyethylene-based composition.

[0077] The following discussion focuses on the preparation of polyethylene compositions for use in embodiments of the present invention.

[0078] polymerization Any conventional polymerization process may be used to produce the polyethylene composition. Such conventional polymerization processes include, but are not limited to, slurry polymerization processes, solution polymerization processes using one or more conventional reactors, such as loop reactors, isothermal reactors, stirred tank reactors, simultaneous, continuous batch reactors, and / or any combination thereof. The polyethylene composition may be produced, for example, by a solution phase polymerization process using one or more loop reactors, isothermal reactors, and combinations thereof.

[0079] Generally, the solution phase polymerization process is carried out in one or more well-stirred reactors, such as one or more isothermal loop reactors or one or more adiabatic reactors, at a temperature ranging from 115 to 250°C, e.g., 115 to 200°C, and a pressure ranging from 300 to 1,000 psi, e.g., 400 to 750 psi. In some embodiments, the temperature of the first reactor is in the range of 115 to 190°C, e.g., 115 to 175°C, and the temperature of the second reactor is in the range of 150 to 250°C, e.g., 130 to 165°C. In other embodiments, in a single reactor, the reactor temperature is in the range of 115 to 250°C, e.g., 115 to 225°C.

[0080] The residence time in the solution phase polymerization process ranges from 2 to 30 minutes, e.g., 10 to 20 minutes. Ethylene, solvent, hydrogen, one or more catalyst systems, optionally one or more cocatalysts, and optionally one or more comonomers are continuously fed to one or more reactors. Exemplary solvents include, but are not limited to, isoparaffins. For example, such solvents are commercially available under the name ISOPAR E from ExxonMobil Chemical Co., Houston, Texas. The mixture of polyethylene composition and solvent is then removed from the reactor, and the polyethylene composition is isolated. The solvent is typically recovered via a solvent recovery unit, i.e., a heat exchanger and a gas-liquid separator drum, and then recycled to the polymerization system.

[0081] In one embodiment, the polyethylene composition can be produced by solution polymerization in a dual reactor system, e.g., a dual loop reactor system, where ethylene is polymerized in the presence of one or more catalyst systems. In some embodiments, only ethylene is polymerized. Additionally, one or more cocatalysts may be present. In another embodiment, the polyethylene composition can be produced by solution polymerization in a single reactor system, e.g., a single loop reactor system, where ethylene is polymerized in the presence of two catalyst systems. In some embodiments, only ethylene is polymerized.

[0082] Catalyst system Specific embodiments of the catalyst system that can be used to produce the polyethylene compositions described herein are now described. It is understood that the catalyst system of the present disclosure may be embodied in different forms and should not be construed as being limited to the specific embodiments described in this disclosure. Rather, the 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.

[0083] The term "independently selected" means 1 , R 2 , R 3 , R 4 , and R 5 The R groups, such as R 1 , R 2 , R 3 , R 4 , and R 5 are all substituted alkyl, or R 1 and R 2 is a substituted alkyl; R 3 The terms "aryl" and "aryl" are used herein to indicate that an R group is an alkyl group, and may be aryl, etc. The use of the singular includes the use of the plural and vice versa (e.g., a hexane solvent includes a plurality of hexanes). A named R group will generally have a structure recognized in the art as corresponding to the R group having that name. These definitions are intended to supplement and illustrate, not preclude, definitions known to those of skill in the art.

[0084] The term "procatalyst" refers to a compound that has catalytic activity when combined with an activator. The term "activator" refers to a compound that chemically reacts with a procatalyst to convert the procatalyst into a catalytically active catalyst. As used herein, the terms "cocatalyst" and "activator" are interchangeable terms.

[0085] When used to describe a chemical group that contains a specific carbon atom, "(C x ~C y A bracketed expression having the form "(C1-C)" means that the unsubstituted form of the chemical group has from x carbon atoms to y carbon atoms, inclusive of x and y. For example, (C1-C 40 ) Alkyl is an alkyl group having 1 to 40 carbon atoms in its unsubstituted form. In some embodiments and general structures, specific chemical groups include R S The parenthetical "(C x ~C y ) for the chemical group R S The substituted version can be represented by any group R S Depending on the identity of R, R may contain more than y carbon atoms. For example, S Exactly one group R is phenyl (-C6H5) S (C1~C 40 "(C)alkyl" can contain from 7 to 46 carbon atoms. Thus, the parenthetical "(C)alkyl" is generally used. x ~C y )" is a substituent R S When substituted by, the minimum and maximum total number of carbon atoms in the chemical group shall be the sum of all the substituents R containing carbon atoms in both x and y. S It is determined by adding the combined sum of the carbon atoms derived from

[0086] The term "substituted" refers to the replacement of at least one hydrogen atom (-H) bonded to a carbon or heteroatom of a corresponding unsubstituted compound or functional group with a substituent (e.g., R S The term "persubstituted" means that all hydrogen atoms (H) attached to carbon or heteroatoms of the corresponding unsubstituted compound or functional group are replaced by a substituent (e.g., R S The term "polysubstituted" means that at least two, but fewer than all, of the hydrogen atoms bonded to a carbon or heteroatom of the corresponding unsubstituted compound or functional group are replaced by substituents.

[0087] The term "-H" means a hydrogen or hydrogen radical that is covalently bonded to another atom. "Hydrogen" and "-H" are interchangeable and mean the same thing unless otherwise specified.

[0088] "(C1~C 40 The term "(C1-C)hydrocarbyl" means a hydrocarbon radical of 1 to 40 carbon atoms. 40 The term "hydrocarbylene" means a hydrocarbon diradical of 1 to 40 carbon atoms, each of which may be aromatic or non-aromatic, saturated or unsaturated, straight or branched chain, cyclic (monocyclic and polycyclic, fused and non-fused polycyclic, including bicyclic, containing 3 or more carbon atoms) or acyclic, unsubstituted or substituted with one or more R S has been replaced by

[0089] In the present disclosure, (C1 to C 40 ) Hydrocarbyl is unsubstituted or substituted (C1-C 40 ) Alkyl, (C3-C 40 )Cycloalkyl, (C3-C 20 )Cycloalkyl-(C1-C 20 ) Alkylene, (C6-C 40 ) aryl, or (C6-C 20 )Aryl-(C1-C 20In some embodiments, the above (C1-C 40 Each of the hydrocarbyl groups has up to 20 carbon atoms (i.e., (C1-C 20 ) hydrocarbyl), in other embodiments having up to 12 carbon atoms.

[0090] "(C1~C 40 ) alkyl" and "(C1-C 18 The term "alkyl" means a saturated linear or branched hydrocarbon radical of 1 to 40 carbon atoms or 1 to 18 carbon atoms, respectively, which radical is unsubstituted or substituted by one or more R-S. 40 Examples of alkyl are unsubstituted (C1-C 20 ) Alkyl, unsubstituted (C1-C 10 ) alkyl, unsubstituted (C1-C5) alkyl, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methylpropyl, 1,1-dimethylethyl, 1-pentyl, 1-hexyl, 1-heptyl, 1-nonyl, and 1-decyl. 40 Examples of substituted (C1-C 20 ) Alkyl, Substituted (C1-C 10 ) alkyl, trifluoromethyl, and [C 45 ] alkyl. 45 The term "alkyl" (with brackets) means that there are up to 45 carbon atoms in the radical, including the substituents, e.g., one R that is (C1-C5) alkyl, S Replaced by (C 27 ~C 40 )alkyl. Each (C1-C5)alkyl can be methyl, trifluoromethyl, ethyl, 1-propyl, 1-methylethyl, or 1,1-dimethylethyl.

[0091] "(C6~C 40 The term "aryl" refers to an unsubstituted or substituted (one or more R Smeans a monocyclic, bicyclic, or tricyclic aromatic hydrocarbon radical, of which at least 6 to 14 carbon atoms are aromatic ring carbon atoms, the monocyclic, bicyclic, or tricyclic radical containing, respectively, one, two, or three rings, one ring being aromatic, two or three rings being independently fused or non-fused, and at least one of the two or three rings being aromatic. 40 Examples of aryl are unsubstituted (C6-C 20 )Aryl, unsubstituted (C6-C 18 )aryl, 2-(C1-C5)alkyl-phenyl, 2,4-bis(C1-C5)alkyl-phenyl, phenyl, fluorenyl, tetrahydrofluorenyl, indacenyl, hexahydroindacenyl, indenyl, dihydroindenyl, naphthyl, tetrahydronaphthyl, and phenanthrene. 40 Examples of aryl are substituted (C1-C 20 )Aryl, Substituted (C6-C 18 )aryl, 2,4-bis[(C 20 ) alkyl]-phenyl, polyfluorophenyl, pentafluorophenyl, and fluoren-9-on-1-yl.

[0092] "(C3~C 40 The term "cycloalkyl" means unsubstituted or substituted with one or more R S means a saturated cyclic hydrocarbon radical of 3 to 40 carbon atoms, substituted with other cycloalkyl groups, such as (C x ~C y )Cycloalkyl) has x to y carbon atoms and is unsubstituted or has one or more R S Unsubstituted (C3-C 40 Examples of cycloalkyl are unsubstituted (C 20 )Cycloalkyl, unsubstituted (C3-C 10 ) cycloalkyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl.40 Examples of cycloalkyl are substituted (C3-C 20 )Cycloalkyl, substituted (C3-C 10 ) cycloalkyl, cyclopentanon-2-yl, and 1-fluorocyclohexyl.

[0093] (C1~C 40 Examples of hydrocarbylenes include unsubstituted or substituted (C6-C 40 )Arylene, (C3-C 40 ) cycloalkylene, and (C1-C 40 ) Alkylene (e.g. (C1-C 20 ) alkylene). In some embodiments, the diradicals are on the same carbon atom (e.g., -CH2-), or on adjacent carbon atoms (i.e., 1,2-diradicals), or separated by one, two, or more than two intervening carbon atoms (e.g., 1,3-diradicals, 1,4-diradicals, etc., respectively). Some diradicals include α,ω-diradicals. α,ω-diradicals are diradicals with the greatest carbon backbone spacing between the radical carbons. (C2-C 20 Some examples of alkylene α,ω-diradicals include ethane-1,2-diyl (i.e. -CH2CH2-), propane-1,3-diyl (i.e. -CH2CH2CH2-), 2-methylpropane-1,3-diyl (i.e. -CH2CH(CH3)CH2-). (C6-C 50 ) Some examples of arylene α,ω-diradicals include phenyl-1,4-diyl, naphthalene-2,6-diyl, or naphthalene-3,7-diyl.

[0094] "(C1~C 40 The term "alkylene" refers to a group that is unsubstituted or has one or more R S means a saturated straight or branched diradical (i.e., the radical is not on a ring atom) of 1 to 40 carbon atoms, substituted by 50 Examples of alkylene are unsubstituted (C1-C 20) alkylene, including unsubstituted -CH2CH2-, -(CH2)3-, -(CH2)4-, -(CH2)5-, -(CH2)6-, -(CH2)7-, -(CH2)8-, -CH2C*HCH3, and -(CH2)4C*(H)(CH3), where "C*" represents a carbon atom from which a hydrogen atom has been removed to form a secondary or tertiary alkyl radical. 50 Examples of alkylene are substituted (C1-C 20 ) alkylene, -CF2-, -C(O)-, and -(CH2) 14 C(CH3)2(CH2)5- (i.e., 6,6-dimethyl-substituted normal-1,20-eicosylene). As mentioned above, the two R S Let's do it together (C1~C 18 ) alkylene, so that the substitution (C1-C 50 Examples of alkylene include 1,2-bis(methylene)cyclopentane, 1,2-bis(methylene)cyclohexane, 2,3-bis(methylene)-7,7-dimethyl-bicyclo[2.2.1]heptane, and 2,3-bis(methylene)bicyclo[2.2.2]octane.

[0095] "(C3~C 40 The term "cycloalkylene" refers to a group that is unsubstituted or has one or more R S "R" means a cyclic diradical (i.e., the radicals are on ring atoms) of 3 to 40 carbon atoms substituted with

[0096] The term "heteroatom" refers to an atom other than hydrogen or carbon. Examples of heteroatoms include O, S, S(O), S(O), Si(R C )2, P(R P ), N(R N ), -N=C(R C )2, -Ge(R C )2-, or -Si(R C )-, and each R C , each R N , and each R P is unsubstituted (C1 to C 18) hydrocarbyl or -H. The term "heterohydrocarbon" refers to a molecule or molecular backbone in which one or more carbon atoms are replaced with a heteroatom. "(C1-C 40 The term "heterohydrocarbyl" means a heterohydrocarbon radical of 1 to 40 carbon atoms, and is used interchangeably with "(C1-C 40 The term "heterohydrocarbylene" means a heterohydrocarbon diradical of 1 to 40 carbon atoms, each heterohydrocarbon having one or more heteroatoms. The heterohydrocarbyl radical may be present on a carbon atom or a heteroatom, and the heterohydrocarbyl diradical may be present on (1) one or two carbon atoms, (2) one or two heteroatoms, or (3) one carbon atom and one heteroatom. Each (C1 to C 50 ) heterohydrocarbyl and (C1-C 50 ) Heterohydrocarbylene is unsubstituted or substituted (one or more R S The ring structure may be aromatic or non-aromatic, saturated or unsaturated, straight or branched chain, cyclic (including monocyclic and polycyclic, fused polycyclic and non-fused polycyclic) or acyclic.

[0097] (C1~C 40 ) Heterohydrocarbyl is unsubstituted or substituted (C1-C 40 )heteroalkyl, (C1-C 40 ) hydrocarbyl-O-, (C1-C 40 ) Hydrocarbyl-S-, (C1-C 40 ) hydrocarbyl-S(O)-, (C1-C 40 ) hydrocarbyl-S(O)2-, (C1-C 40 ) Hydrocarbyl-Si(R C )2-, (C1~C 40 )hydrocarbyl-N(R N )-, (C1~C 40 ) hydrocarbyl-P(R P )-, (C2~C 40 )heterocycloalkyl, (C2-C 19 )Heterocycloalkyl-(C1-C 20 ) alkylene, (C3-C 20)Cycloalkyl-(C1-C 19 ) Heteroalkylene, (C2-C 19 )Heterocycloalkyl-(C1-C 20 ) Heteroalkylene, (C1-C 40 ) Heteroaryl, (C1-C 19 )Heteroaryl-(C1-C 20 ) Alkylene, (C6-C 20 )Aryl-(C1-C 19 ) heteroalkylene, or (C1-C 19 )Heteroaryl-(C1-C 20 ) heteroalkylene.

[0098] "(C4~C 40 The term "heteroaryl" refers to an unsubstituted or substituted heteroaryl group consisting of a total of 4 to 40 carbon atoms and 1 to 10 heteroatoms (one or more R S means a monocyclic, bicyclic, or tricyclic heteroaromatic hydrocarbon radical, the monocyclic, bicyclic, or tricyclic radical containing, respectively, one, two, or three rings, the two or three rings being independently fused or non-fused, and at least one of the two or three rings being heteroaromatic. Other heteroaryl groups, such as (C4-C 12 ) heteroaryl, etc., (C x ~C y ) Heteroaryl (general) has x to y carbon atoms (e.g., 4 to 12 carbon atoms) and is unsubstituted or has one or more R SThe monocyclic heteroaromatic hydrocarbon radicals are defined in the same manner as those substituted by. The monocyclic heteroaromatic hydrocarbon radicals are 5- or 6-membered rings. The 5-membered ring has 5 minus h carbon atoms, where h is the number of heteroatoms, which can be 1, 2, or 3, and each heteroatom can be O, S, N, or P. Examples of 5-membered heteroaromatic hydrocarbon radicals include pyrrol-1-yl, pyrrol-2-yl, furan-3-yl, thiophen-2-yl, pyrazol-1-yl, isoxazol-2-yl, isothiazol-5-yl, imidazol-2-yl, oxazol-4-yl, thiazol-2-yl, 1,2,4-triazol-1-yl, 1,3,4-oxadiazol-2-yl, 1,3,4-thiadiazol-2-yl, tetrazol-1-yl, tetrazol-2-yl, and tetrazol-5-yl. The six-membered ring has 6 minus h carbon atoms, where h is the number of heteroatoms, which can be 1 or 2, and the heteroatoms can be N or P. Examples of six-membered heteroaromatic hydrocarbon radicals are pyridin-2-yl, pyrimidin-2-yl, and pyrazin-2-yl. The bicyclic heteroaromatic hydrocarbon radicals can be fused 5,6- or 6,6-ring systems. Examples of fused 5,6-ring bicyclic heteroaromatic hydrocarbon radicals include indol-1-yl and benzimidazol-1-yl. Examples of fused 6,6-ring bicyclic heteroaromatic hydrocarbon radicals include quinolin-2-yl and isoquinolin-1-yl. The tricyclic heteroaromatic hydrocarbon radicals can be fused 5,6,5-, 5,6,6-, 6,5,6-, or 6,6,6-ring systems. An example of a fused 5,6,5-ring system is 1,7-dihydropyrrolo[3,2-f]indol-1-yl. An example of a fused 5,6,6-ring system is 1H-benzo[f]indol-1-yl. An example of a fused 6,5,6-ring system is 9H-carbazol-9-yl. An example of a fused 6,5,6-ring system is 9H-carbazol-9-yl. An example of a fused 6,6,6-ring system is acridine-9-yl.

[0099] The heteroalkyl group is any of (C1-C 50) or fewer carbon atoms and one or more heteroatoms. Similarly, heteroalkylene may be a saturated straight or branched chain diradical containing 1 to 50 carbon atoms and one or more heteroatoms. Heteroatoms as defined above include, but are not limited to, Si(R C )3, Ge(R C )3, Si(R C )2, Ge(R C )2, P(R P )2, P(R P ), N(R N )2, N(R N ), N, O, OR C , S, S.R. C , S(O), and S(O), each of the heteroalkyl and heteroalkylene groups may be unsubstituted or may contain one or more R S is replaced by

[0100] Unsubstituted (C2~C 40 Examples of heterocycloalkyl include unsubstituted (C-C 20 )Heterocycloalkyl, unsubstituted (C2-C 10 ) heterocycloalkyl, aziridin-1-yl, oxetan-2-yl, tetrahydrofuran-3-yl, pyrrolidin-1-yl, tetrahydrothiophene-S,S-dioxid-2-yl, morpholin-4-yl, 1,4-dioxan-2-yl, hexahydroazepin-4-yl, 3-oxa-cyclooctyl, 5-thio-cyclononyl, and 2-aza-cyclodecyl.

[0101] The term "halogen atom" or "halogen" refers to a radical of a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), or an iodine atom (I). The term "halide" refers to a radical of a fluoride atom (F - ), chloride (Cl - ), bromide (Br - ), or iodide (I - ) refers to the anionic form of a halogen atom.

[0102] The term "saturated" means lacking carbon-carbon double bonds, carbon-carbon triple bonds, and (in heteroatom-containing groups) carbon-nitrogen, carbon-phosphorus, and carbon-silicon double bonds. A saturated chemical group is one or more substituents R S When substituted with, one or more double and / or triple bonds may optionally be replaced by a substituent R S The term "unsaturated" refers to the presence of one or more carbon-carbon double bonds, carbon-carbon triple bonds, and (in heteroatom-containing groups) carbon-nitrogen, carbon-phosphorus, and carbon-silicon double bonds, provided that the substituents R, if present, are not present in the alkyl group. S The term "aromatic ring" is intended to exclude any double bonds which may be present in the (hetero)aromatic ring or, if present, in the (hetero)aromatic ring.

[0103] According to some embodiments, the catalyst system for producing the polyethylene composition comprises a metal-ligand complex according to formula (I): [ka]

[0104] In formula (I), M is a metal selected from titanium, zirconium, or hafnium, the metal is in a formal oxidation state of +2, +3, or +4, n is 0, 1, or 2, when n is 1, X is a monodentate or bidentate ligand, and when n is 2, each X is a monodentate ligand and is the same or different, the metal-ligand complex as a whole is charge neutral, and each Z is independently selected from -O-, -S-, -N(R N )-, or -P(R P )-, and L is selected from (C1 to C 40 ) hydrocarbylene or (C1-C 40 ) heterohydrocarbylene, (C1-C 40 ) the hydrocarbylene has a moiety that includes a linker skeleton of 1 to 10 carbon atoms (to which L is attached) that connects the two Z groups of formula (I), or (C1 to C 40) heterohydrocarbylene has a moiety containing a linker skeleton of 1 to 10 atoms connecting the two Z groups of formula (I), (C1 to C 40 Each of the 1 to 10 atoms of the 1 to 10 atom linker backbone of the heterohydrocarbylene is independently a carbon atom or a heteroatom, and each heteroatom is independently O, S, S(O), S(O), Si(R C )2, Ge(R C )2, P(R C ), or N(R C ) and each R C However, independently (C1~C 30 ) hydrocarbyl or (C1-C 30 ) heterohydrocarbyl, R 1 and R 8 However, independently, -H, (C1~C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C )3, -Ge(R C )3, -P(R P )2, -N(R N )2, -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R N ) 2NC(O)-, halogen, and a radical having the following formula (II), formula (III), or formula (IV): [ka] In formulas (II), (III), and (IV), R 31~35 , R 41~48 , or R 51~59 Each of the following is independently (C1 to C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C)3, -Ge(R C )3, -P(R P )2, -N(R N )2, -N=CHR C , -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R N )2NC(O)-, halogen, or -H, provided that R 1 or R 8 is a radical having formula (II), formula (III), or formula (IV).

[0105] In formula (I), R 2~4 , R 5~7 , and R 9~16 Each of the following is independently (C1 to C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C )3, -Ge(R C )3, -P(R P )2, -N(R N )2, -N=CHR C , -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R C ) 2NC(O)-, halogen, and -H.

[0106] In some embodiments, the polyethylene composition is formed using a first catalyst according to formula (I) in a first reactor and a different catalyst according to formula (I) in a second reactor.

[0107] In one exemplary embodiment in which a dual loop reactor is used, the procatalyst used in the first loop is zirconium, [[2,2′′-[[bis[1-methylethyl)germylene]bis(methyleneoxy-κO)]bis[3′,5,5″-tris(1,1-dimethylethyl)-5′-octyl[1,1′:3′,1″-terphenyl]-2′-olato-κO]](2-)]dimethyl-, represented by the chemical formula C 86 H 128 F2GeO4Zr and has the following structure: [ka] In such an embodiment, the procatalyst used in the second loop is zirconium, [[2,2′′-[1,3-propanediylbis(oxy-κO)]bis[3-[2,7-bis(1,1-dimethylethyl)-9H-carbazol-9-yl]]-5′-(dimethyloctylsilyl)-3′-methyl-5-(1,1,3,3-tetramethylbutyl)[1,1]-biphenyl]-2-olato-κO]](2-)]dimethyl, having the chemical formula C 107 H 154 N2O4Si2Zr and has the following structure: [ka]

[0108] cocatalyst component The catalyst system comprising the metal-ligand complex of formula (I) can be catalytically activated by any technique known in the art for activating metal-based catalysts for olefin polymerization reactions. For example, the system comprising the metal-ligand complex of formula (I) can be catalytically activated by contacting the complex with an activating cocatalyst or combining the complex with an activating cocatalyst. Activating cocatalysts suitable for use in the present invention include alkylaluminum, 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 aforementioned activating cocatalysts and techniques are also contemplated. The term "alkylaluminum" refers to monoalkylaluminum dihydrides or dihalides, dialkylaluminum hydrides or halides, or trialkylaluminum. Examples of polymeric or oligomeric alumoxanes include methylalumoxane, triisobutylaluminum modified methylalumoxane, and isobutylalumoxane.

[0109] The Lewis acid activator (cocatalyst) may be any of the Lewis acid activators described herein, which may be any of the Lewis acid activators having one to three (C1-C 20 In one embodiment, the Group 13 metal compound includes a tri((C1-C) hydrocarbyl substituent. 20 )hydrocarbyl)substituted aluminum or tri((C1-C 20 In another embodiment, the Group 13 metal compound is a tri(hydrocarbyl)-substituted aluminum, tri((C1-C 20 )hydrocarbyl)-boron compounds, tri((C1-C 10 ) alkyl) aluminum, tri((C6-C 18)aryl)boron compounds, and their halogenated (including perhalogenated) derivatives. In further embodiments, the Group 13 metal compound is tris(fluoro-substituted phenyl)borane, tris(pentafluorophenyl)borane. In some embodiments, the activating cocatalyst is tris((C1-C 20 ) hydrocarbyl borates (e.g., trityl tetrafluoroborate) or tri((C 20 )hydrocarbyl)ammonium tetra((C1-C 20 )hydrocarbyl)boranes (e.g., bis(octadecyl)methylammonium tetrakis(pentafluorophenyl)borane). As used herein, the term "ammonium" refers to any of the ((C1-C 20 ) Hydrocarbyl) 4N + , ((C1~C 20 )hydrocarbyl)3N(H) + , ((C1~C 20 )hydrocarbyl)2N(H)2 + , (C1~C 20 ) HydrocarbylN(H)3 + , or N(H)4 + Each of the nitrogen cations (C1 to C 20 ) When two or more hydrocarbyls are present, they may be the same or different.

[0110] As a combination of neutral Lewis acid activators (cocatalysts), tri((C1-C4) alkyl)aluminum and tri((C6-C 18)aryl)boron compounds, especially tris(pentafluorophenyl)borane. Other embodiments are combinations of such neutral Lewis acid mixtures with polymeric or oligomeric alumoxanes, and combinations of a single neutral Lewis acid, especially tris(pentafluorophenyl)borane, with polymeric or oligomeric alumoxanes. The ratio of the number of moles of (metal-ligand complex):(tris(pentafluorophenylborane):(alumoxane) [e.g., (Group 4 metal-ligand complex):(tris(pentafluorophenylborane):(alumoxane)] is 1:1:1 to 1:10:30, and in other embodiments is 1:1:1.5 to 1:5:10.

[0111] A catalyst system comprising the metal-ligand complex of formula (I) can be activated to form an active catalyst composition by combining one or more cocatalysts, such as cation-forming cocatalysts, strong Lewis acids, or combinations thereof. Suitable activating cocatalysts include polymeric or oligomeric aluminoxanes, particularly methylaluminoxane, as well as inert, compatible, non-coordinating, ion-forming compounds. Exemplary suitable cocatalysts include modified methylaluminoxane (MMAO), bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate (1 - ) amines, and combinations thereof.

[0112] In some embodiments, one or more of the aforementioned activating cocatalysts are used in combination with each other. Particularly preferred combinations are mixtures of tri((C1-C4)hydrocarbyl)aluminum, tri((C1-C4)hydrocarbyl)borane, or ammonium borate with oligomeric or polymeric alumoxane compounds. The ratio of the total number of moles of the one or more metal-ligand complexes of formula (I) to the total number of moles of the one or more activating cocatalysts is 1:10,000 to 100:1. In some embodiments, this ratio is at least 1:5000, in some other embodiments at least 1:1000, and not more than 10:1, and in some other embodiments not more than 1:1. When alumoxane is used alone as the activating cocatalyst, preferably the number of moles of alumoxane used is at least 100 times the number of moles of the metal-ligand complexes of formula (I). When tris(pentafluorophenyl)borane is used alone as the activating cocatalyst, in some other embodiments, the number of moles of tris(pentafluorophenyl)borane used relative to the total number of moles of one or more metal-ligand complexes of formula (I) is 0.5:1 to 10:1, 1:1 to 6:1, or 1:1 to 5:1. The remaining activating cocatalysts are generally used in a molar amount approximately equal to the total molar amount of one or more metal-ligand complexes of formula (I).

[0113] Nucleating Agent The polyethylene-based compositions used in the oriented multilayer films of the present invention further comprise a nucleating agent that is the calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate. These nucleating agents, when used in appropriate amounts and in combination with the polyethylene compositions described herein, are believed to provide a more uniform distribution of crystals and crystal sizes in the polyethylene film, more uniform melt behavior of the resulting polyethylene-based compositions and films formed from the polyethylene-based compositions, and a larger operating window during orientation of films formed from the polyethylene-based compositions, while also providing one or more other improvements (e.g., stiffness, barrier, and / or optics) in the resulting film.

[0114] In some embodiments, the nucleating agent is a calcium salt of 1,2-cyclohexanedicarboxylic acid. In some embodiments, the nucleating agent is sodium 4-[(4-chlorobenzoyl)amino]benzoate. In some embodiments, the polyethylene-based composition includes both a calcium salt of 1,2-cyclohexanedicarboxylic acid and sodium 4-[(4-chlorobenzoyl)amino]benzoate.

[0115] Nucleating agents such as calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate are heterogeneous nucleating agents. The amount and type of heterogeneous nucleating agent is important in providing the desired performance. In some embodiments, the polyethylene-based composition comprises 20-5000 ppm of a heterogeneous nucleating agent in the form of calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate based on the total weight of the polyethylene-based composition. In some embodiments, the polyethylene-based composition comprises 20-2000 ppm of calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate based on the total weight of the polyethylene-based composition. In some embodiments, the polyethylene-based composition comprises 500-2000 ppm of calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate based on the total weight of the polyethylene-based composition.

[0116] In some embodiments, the heterogeneous nucleating agent may be provided with a fatty acid metal salt, such as zinc stearate, zinc palmitate, and mixtures thereof. Based on how the zinc stearate is commercially prepared, some zinc palmitate may also be present, as commercially available stearic acid often contains significant amounts of palmitic acid. In some such embodiments, the polyethylene-based composition comprises at least one of zinc stearate and zinc palmitate from 45 to 1000 ppm, based on the total weight of the polyethylene-based composition. In some embodiments, the polyethylene-based composition comprises at least one of zinc stearate and zinc palmitate from 50 to 700 ppm, based on the total weight of the polyethylene-based composition. In some embodiments, the polyethylene-based composition comprises at least one of zinc stearate and zinc palmitate from 85 to 600 ppm, based on the total weight of the polyethylene-based composition.

[0117] One non-limiting example of a calcium salt of 1,2-cyclohexanedicarboxylic acid that can be used in embodiments of the present invention is Hyperform HPN-20E from Milliken Chemical of Spartanburg, South Carolina. Hyperform HPN-20E comprises 60-70 weight percent of the calcium salt of 1,2-cyclohexanedicarboxylic acid and 30-40 weight percent of zinc stearate / palmitate. In some embodiments, the polyethylene-based composition comprises 20-5000 ppm of Hyperform HPN-20E, based on the total weight of the polyethylene-based composition. The polyethylene-based composition comprises, in some embodiments, 20-2000 ppm of Hyperform HPN-20E, based on the total weight of the polyethylene-based composition.

[0118] One non-limiting example of sodium 4-[(4-chlorobenzoyl)amino]benzoate that can be used in embodiments of the present invention is Hyperform HPN 210M from Milliken Chemical, Spartanburg, South Carolina.

[0119] In some embodiments, the calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate (and fatty acid metal salts (e.g., zinc stearate and / or zinc palmitate), if also included) can be provided as a masterbatch by blending it with a carrier resin prior to combining with the polyethylene composition described herein. In some such embodiments, the carrier resin is a polyethylene having a melt index (I2) of 1 to 12 g / 10 min. In some embodiments where the calcium salt of 1,2-cyclohexanedicarboxylic acid and zinc stearate / zinc palmitate are provided as a masterbatch, the masterbatch comprises 2 to 4 weight percent of the calcium salt of 1,2-cyclohexanedicarboxylic acid and zinc stearate / zinc palmitate, based on the total weight of the masterbatch. In one embodiment, the carrier resin is a narrow molecular weight distribution high density polyethylene homopolymer having a density of 0.965 and a melt index (I2) of 8 to 9 g / 10 min. In some embodiments, the masterbatch can also include other additives. Depending on the total amount of additives included, the masterbatch can contain 85 to 98 weight percent carrier resin, based on the total weight of the masterbatch.

[0120] Other nucleating agents that can be used in some embodiments of the invention include those disclosed in U.S. Patent Publication Nos. 2015 / 0087758, 2015 / 0087759, and 2015 / 0086736, which are incorporated herein by reference. In some embodiments, the polyethylene-based composition comprises 20 to 5000 ppm of such nucleating agents, based on the total weight of the polyethylene-based composition. In some embodiments, the polyethylene-based composition comprises 20 to 2000 ppm of such nucleating agents, based on the total weight of the polyethylene-based composition.

[0121] silica In some embodiments, the polyethylene composition further comprises silica, which, when used in appropriate amounts in combination with the polyethylene compositions described herein, has been found to reduce the level of dusting in films formed from the polyethylene compositions.

[0122] The amount of silica used in the polyethylene-based composition can be important in reducing the level of dusting when the polyethylene-based composition is incorporated into a surface layer of a film. In some embodiments, the polyethylene-based composition comprises 75 to 800 ppm of silica, based on the total weight of the polyethylene-based composition. In some embodiments, the polyethylene-based composition comprises 100 to 500 ppm of silica, based on the total weight of the polyethylene-based composition.

[0123] One non-limiting example of a silica that can be used in embodiments of the present invention is Sylobloc 45, available from Grace Davison Company.

[0124] In some embodiments, talc can be used in addition to or as a replacement for silica.

[0125] In some embodiments, the silica can be provided as a masterbatch by blending it with a carrier resin, a calcium salt of 1,2-cyclohexanedicarboxylic acid or similar nucleating agent, and zinc stearate / palmitate prior to combining with the polyethylene composition described herein. The masterbatch can be as described above in relation to the calcium salt of 1,2-cyclohexanedicarboxylic acid and zinc stearate / palmitate. The amount of silica in the masterbatch can be based on the target silica for the overall polyethylene-based composition.

[0126] Oriented Multilayer Film The oriented (uniaxial or biaxial) polyethylene films of the present invention are multilayer films. As previously mentioned, such films include at least one layer comprising the polyethylene-based composition described herein.

[0127] In some embodiments of the multilayer film of the present invention, the multilayer film may include a polyethylene-based composition as described in more than one layer, while in other embodiments, such polyethylene-based composition is provided in a single layer. The amount of polyethylene-based composition used in the film of the present invention may depend on several factors, including, for example, the other layers in the film, the desired properties of the film, the end use of the film, etc.

[0128] The number of layers in the film can depend on several factors including, for example, the desired properties of the film, the desired thickness of the film, the content of other layers in the film, the end use of the film, the equipment available to manufacture the film, etc. For example, multilayer films can further include other layers typically included in multilayer films depending on the application including, for example, sealant layers, barrier layers, tie layers, structural layers, etc. Multilayer blown films can include up to 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 layers in various embodiments.

[0129] Other layers within the multilayer films of the present invention, in various embodiments, can comprise a polymer selected from the polyethylene-based compositions described herein, LLDPE, MDPE, LDPE, HDPE, HMWHDPE (high molecular weight HDPE), propylene-based polymers, polyolefin plastomers (POP), polyolefin elastomers (POE), olefin block copolymers (OBC), ethylene vinyl acetate, ethylene acrylic acid, ethylene methacrylic acid, ethylene methyl acrylate, ethylene ethyl acrylate, ethylene butyl acrylate, isobutylene, maleic anhydride grafted polyolefins, ionomers of any of the foregoing, or combinations thereof.

[0130] In some embodiments, in addition to the polyethylene-based composition, the oriented multilayer polyethylene film further comprises a second polyethylene composition, the second polyethylene composition exhibiting at least two local peaks in the comonomer distribution measured by crystallization elution fractionation, excluding the soluble fraction, one of the peaks being between 40°C and 95°C. In some embodiments, the fraction forming the peak at 40°C to 95°C is up to 50 weight percent of the composition, as measured by crystallization elution fractionation. In some embodiments, the second polyethylene composition exhibiting at least two local peaks in the comonomer distribution measured by crystallization elution fractionation, excluding the soluble fraction, one of the peaks being between 40°C and 87°C. In some embodiments, the fraction forming the peak at 40°C to 87°C is up to 50 weight percent of the composition, as measured by crystallization elution fractionation. In some embodiments, the density of the second polyethylene composition is 0.928 to 0.940 g / cm 3 Examples of polyethylene compositions that can be used as the second polyethylene composition include the linear low density polyethylene resins described in U.S. Pat. No. 10,363,700 (herein incorporated by reference), as well as commercially available resins from The Dow Chemical Company: DOWLEX™ 2750ST, ELITE™ 5940G, and ELITE™ 5960G. In embodiments where the film comprises such a second composition, the amount and location (i.e., layer) of the second composition used can depend on several factors, including, for example, the other layers of the film, the desired properties of the film, the end use of the film, etc. In some embodiments, the second composition is provided in a layer of the film that comprises the polyethylene-based composition described herein.

[0131] It should be understood that in some embodiments, any of the layers within the film may further include one or more additives (in addition to those described above for the polyethylene-based compositions) known to those skilled in the art, such as, for example, antioxidants, UV stabilizers, heat stabilizers, slip agents, antiblocking agents, pigments or colorants, processing aids, crosslinking catalysts, flame retardants, fillers, and blowing agents.

[0132] Being polyethylene-based, the oriented multilayer polyethylene film of the present invention can be incorporated into multilayer films and articles that are substantially, if not entirely, composed of polyethylene, in order to provide more easily recyclable films and articles, according to some embodiments of the present invention. For example, a film that comprises primarily polyethylene has an improved recyclability profile, in addition to other advantages that the use of such polymers may provide. For example, in some embodiments, the multilayer film is composed entirely of ethylene-based polymers, except for additives. Based on the total weight of the multilayer film, the multilayer film may comprise, in some embodiments, 90% by weight of ethylene-based polymer, or in some embodiments, 95% by weight of ethylene-based polymer, or in some embodiments, 99% by weight of ethylene-based polymer, or in some embodiments, 99.9% by weight of ethylene-based polymer, or in some embodiments, 100% by weight of ethylene-based polymer.

[0133] Multilayer films may have a variety of thicknesses before orientation, depending, for example, on the number of layers, the intended use of the film, and other factors. In some embodiments, such polyethylene films have a thickness of 320 to 3200 microns (typically 640 to 1920 microns) before orientation.

[0134] Prior to orientation, the polyethylene film can be formed using techniques known to those skilled in the art based on the teachings herein. For example, the film can be prepared as a blown film (e.g., a water-quenched blown film) or a cast film. For example, in the case of a multi-layer polyethylene film, for layers that can be coextruded, such layers can be coextruded as a blown film or a cast film using techniques known to those skilled in the art based on the teachings herein.

[0135] In various embodiments, the polyethylene film may be uniaxially or biaxially oriented using techniques known to those skilled in the art.

[0136] In some embodiments where the film is biaxially oriented, the polyethylene film is biaxially oriented using a tenter frame sequential biaxial orientation process. Such techniques are generally known to those skilled in the art. In other embodiments, the polyethylene film may be biaxially oriented using other techniques known to those skilled in the art based on the teachings herein, such as a double bubble orientation process. Generally, in a tenter frame sequential biaxial orientation process, a tenter frame is incorporated as part of a multilayer coextrusion line. After being extruded from the flat die, the film is cooled on a chill roll and immersed in a water bath filled with room temperature water. The cast film is then passed through a series of rollers with different rotation speeds to achieve stretching in the machine direction. There are several pairs of rollers in the MD stretching segment of the production line, all of which are oil heated. The pairs of rollers operate sequentially as preheat rollers, stretch rollers, and relaxation and annealing rollers. The temperature of each roller pair is controlled separately. After stretching in the machine direction, the film web is passed through a tenter frame hot air oven with a heating zone to perform stretching in the transverse direction. The first few zones are for preheating, followed by a zone for stretching and then a final zone for annealing.

[0137] In some embodiments, the polyethylene film may be oriented in the machine direction with a stretch ratio of 2:1 to 9:1, or in the alternative with a stretch ratio of 2:1 to 6:1, or in the alternative with a stretch ratio of 4:1 to 6:1. The polyethylene film may be oriented in the transverse direction with a stretch ratio of 2:1 to 11:1, or in the alternative with a stretch ratio of 2:1 to 9:1, or in the alternative with a stretch ratio of 6:1 to 9:1. In some embodiments, the polyethylene film is oriented in the machine direction with a stretch ratio of 2:1 to 9:1 and in the transverse direction with a stretch ratio of 2:1 to 11:1. The polyethylene film is oriented in the machine direction with a stretch ratio of 2:1 to 6:1 and in the transverse direction with a stretch ratio of 2:1 to 9:1, in some embodiments. In some embodiments, the polyethylene film is oriented in the machine direction with a stretch ratio of 4:1 to 6:1 and in the transverse direction with a stretch ratio of 6:1 to 9:1.

[0138] In some embodiments, after orientation, the biaxially oriented film has a thickness of 5 to 50 microns, hi some embodiments, the biaxially oriented film has a thickness of 15 to 40 microns.

[0139] In some embodiments, when the multilayer film is uniaxially oriented, the film is oriented in the machine direction only.As known to those skilled in the art based on the teachings herein, various processing parameters are considered suitable for stretching in the machine direction.For example, the uniaxially oriented multilayer film can be oriented in the machine direction with a stretch ratio of more than 1:1 and less than 8:1, or with a stretch ratio of 4:1 to 8:1.

[0140] In some embodiments, after orientation, the machine direction oriented film has a thickness of 5 to 50 microns, hi some embodiments, the machine direction oriented film has a thickness of 15 to 40 microns.

[0141] In some embodiments, for example, depending on the end use application, the oriented polyethylene film can be corona treated, plasma treated, or printed using techniques known to those of skill in the art. In some embodiments, the oriented multilayer film can be surface coated with aluminum, silicon oxide, aluminum oxide, or other metals known to those of skill in the art based on the teachings herein.

[0142] Laminate Embodiments of the invention also include laminates incorporating oriented multilayer polyethylene films. In some embodiments, a biaxially oriented multilayer polyethylene film according to an embodiment of the invention can be laminated to another film. In some embodiments, a uniaxially oriented (e.g., machine direction oriented) multilayer polyethylene film according to an embodiment of the invention can be laminated to another film.

[0143] Other films in such embodiments include polyethylene sealant films, polyethylene terephthalate, polypropylene, or polyamide. The polyethylene sealant film can be a monolayer or multilayer film formed substantially from polyethylene (e.g., containing more than 90 weight percent ethylene-based polymer, or more than 95 weight percent ethylene-based polymer, or more than 99 weight percent ethylene-based properties) that can seal the laminate to another film, another laminate, or itself when heated as part of a laminate structure. Any polyethylene sealant film known to those skilled in the art based on the teachings herein may be used. When the other film includes polyethylene terephthalate, polypropylene, or polyamide, the entire film can be formed from polyethylene terephthalate, polypropylene, or polyamide, or the film includes at least one layer that includes polyethylene terephthalate, polypropylene, or polyamide. Those skilled in the art can select a film that includes polyethylene terephthalate, polypropylene, or polyamide for use in such embodiments based on the teachings herein.

[0144] Laminates according to embodiments of the invention can be formed using techniques known to those skilled in the art based on the teachings herein. For example, an oriented multilayer polyethylene film can be laminated to another film using an adhesive. A variety of adhesive compositions are believed to be suitable for the adhesive used in the laminate. These may include polyurethane, epoxy, acrylic, and the like. In one embodiment, the laminate can include an adhesive layer that includes a polyurethane adhesive. The polyurethane adhesive can be solventless, water-based, or solvent-based. Additionally, the polyurethane adhesive can be a two-part formulation. The weight or thickness of the adhesive layer can depend on many factors, including, for example, the desired thickness of the multilayer structure, the type of adhesive used, and other factors. In some embodiments, the adhesive layer can be up to 5.0 g / m 2 , or 1.0 to 4.0 g / m 2 , or 2.0 to 3.0 g / m 2 It is applied with.

[0145] Laminates according to some embodiments of the present invention may also be formed by extrusion lamination.

[0146] Goods Embodiments of the present invention also relate to articles, such as packaging, formed from or incorporating the oriented multilayer polyethylene films of the present invention (or laminates incorporating such films). Such packaging can be formed from any of the films and laminates described herein.

[0147] Examples of such articles include flexible packaging, pouches, stand-alone pouches, and pre-made packages or pouches. In some embodiments, the oriented multilayer polyethylene film or laminate of the present invention can be used in food packaging. Examples of food products that can be included in such packaging include meat, cheese, cereal, nuts, juice, sauce, and the like. Such packaging can be formed using techniques known to those skilled in the art based on the teachings herein and based on the particular application of the packaging (e.g., type of food, amount of food, etc.).

[0148] Test Method Unless otherwise indicated herein, the following analytical methods are used in describing embodiments of the present invention.

[0149] Melt Index Melt index I2 (or I2) and I 10 (or I10) were measured according to ASTM D-1238 (Method B) at 190° C. and loads of 2.16 kg and 10 kg, respectively, and are reported in g / 10 min.

[0150] density Samples for density measurements were prepared according to ASTM D4703. Measurements were performed according to ASTM D792, Method B, within 1 hour of sample pressing.

[0151] Conventional Gel Permeation Chromatography (Conventional GPC) The GPC-IR high temperature chromatography system from PolymerChar (Valencia, Spain) is equipped with a two-angle laser light scattering detector model 2040 from Precision Detectors (Amherst, MA), an IR5 infrared detector and a four-capillary viscometer, both from PolymerChar. Data collection was performed using PolymerChar Instrument Control software and data collection interface. The system is equipped with an online solvent degassing device and pumping system from Agilent Technologies (Santa Clara, CA).

[0152] The injection temperature is controlled at 150 degrees Celsius. The columns used are three 10 micron "Mixed-B" columns from Polymer Laboratories (Shropshire, UK). The solvent used is 1,2,4-trichlorobenzene. The samples are prepared at a concentration of "0.1 grams of polymer in 50 milliliters of solvent". The chromatography solvent and the sample preparation solvent each contained "200 ppm of butylated hydroxytoluene (BHT)". Both solvent sources are nitrogen sparged. The ethylene-based polymer samples are gently stirred at 160 degrees Celsius for 3 hours. The injection volume is "200 microliters" and the flow rate is "1 milliliter / minute". The GPC column set is calibrated by running 21 "narrow molecular weight distribution" polystyrene standards. The molecular weights ("MW") of the standards range from 580 to 8,400,000 g / mol, and the standards are contained in six "cocktail" mixtures. Each standard mixture has at least 10 between individual molecular weights. Standard mixtures are purchased from Polymer Laboratories. Polystyrene standards are prepared at 0.025 g in 50 mL of solvent for molecular weights of 1,000,000 g / mol and above, and 0.050 g in 50 mL of solvent for molecular weights less than 1,000,000 g / mol.

[0153] The polystyrene standards are dissolved at 80° C. with gentle stirring for 30 minutes. The narrow standards mixtures are run in order of decreasing highest molecular weight component first to minimize degradation. The polystyrene standard peak molecular weights were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Letters, 6, 621 (1968)). Mpolyethylene=A×(Mpolystyrene) B Convert to polyethylene molecular weight using (Equation 1): where M is the molecular weight, A is equal to 0.4316, and B is equal to 1.0.

[0154] Calculate the number average molecular weight (Mn-conventional GPC), weight average molecular weight (Mw-conventional GPC), and z-average molecular weight (Mz-conventional GPC) according to the following Equations 2-4.

number

number

number

[0155] In Equations 2-4, RV is the column retention volume (linearly spaced) collected at "1 point per second", IR is the baseline subtracted IR detector signal in volts from the IR5 measurement channel of the GPC instrument, and M PE is the polyethylene equivalent MW determined from Equation 1. Data calculations are performed using PolymerChar's "GPC One software (version 2.013H)."

[0156] Creep Zero Shear Viscosity Measurement Method Zero shear viscosity is obtained by creep testing on an AR G2 stress-controlled rheometer (TA Instruments, New Castle, Del.) using "25 mm diameter" parallel plates at 190°C. The rheometer oven is set to the test temperature for at least 30 minutes before zeroing the fixture. At the test temperature, a compression molded sample disk is inserted between the plates and allowed to equilibrate for 5 minutes. The upper plate is then lowered to 50 μm (instrument setting) above the desired test gap (1.5 mm). Excess material is trimmed away and the upper plate is lowered to the desired gap. Measurements are taken under a nitrogen purge with a flow rate of 5 L / min. The default creep time is set for 2 hours. Each sample is compression molded into a "2 mm thick x 25 mm diameter" circular plaque at 177°C for 5 minutes under a pressure of 10 MPa in air. The sample is then removed from the press and placed on a counter to cool.

[0157] All of the samples were subjected to a constant low shear stress of 20 Pa to ensure that the steady state shear rate was low enough to be in the Newtonian region. The resulting steady state shear rate was 10 for the samples in this study. -3 ~10 -4 s -1 The steady state was determined by taking a linear regression of all the data in the last 10% time window of a plot of log(J(t)) versus log(t), where J(t) is the creep compliance and t is the creep time. If the slope of the linear regression is greater than 0.97, the steady state is considered to have been reached and the creep test is then stopped. In all cases in this test, the slope meets the criterion within 1 hour. The steady state shear rate is determined from the slope of the linear regression of all the data points in the last 10% time window of a plot of "ε versus t", where ε is strain. The creep zero shear viscosity is determined from the ratio of the applied stress to the steady state shear rate.

[0158] To determine if a sample has degraded during the creep test, small amplitude oscillatory shear tests are performed on the same sample from 0.1 to 100 rad / sec before and after the creep test. The complex viscosity values ​​of the two tests are compared. If the difference in viscosity value at 0.1 rad / sec is greater than 5%, the sample is considered to have degraded during the creep test and the results are discarded.

[0159] Zero Shear Viscosity Ratio (ZSVR) Zero Shear Viscosity Ratio (ZSVR) is defined as the ratio of the zero shear viscosity (ZSV) of a branched polyethylene material to the ZSV of a linear polyethylene material at equivalent average molecular weight according to the following equation: ZSVR=η 0B / η 0L = η 0B / (2.29 -15 × Mwt 3.65 ) ZSV values ​​are obtained from creep tests at 190°C by the method described above. Mwt is determined using gel permeation chromatography as described above. A correlation between the ZSV of a linear polyethylene and its molecular weight was established based on a series of linear polyethylene reference samples. A lower ZSVR indicates a lower level of long chain branching.

[0160] 13 Branching measurements using C NMR Sample preparation Samples are prepared by adding approximately 2.7 g of a 50 / 50 mixture of tetrachloroethane-d2 / orthodichlorobenzene containing 0.025 M Cr(AcAc)3 to 0.20-0.30 g of sample in a Norell 1001-7 10 mm NMR tube. Oxygen is removed by purging the tube with N2 for 1 min. Samples are dissolved and homogenized by heating the tube and its contents to 120-140 °C using a heating block and vortex mixer. Each sample is visually inspected to ensure homogeneity. Thoroughly mixed samples are not allowed to cool prior to insertion into the heated NMR sample changer and / or NMR probe.

[0161] Data Acquisition Parameters Data are collected using a Bruker 600 MHz spectrometer equipped with a Bruker 10 mm multinuclear high temperature CryoProbe. Data are acquired at a sample temperature of 120°C using 1280 voltage transients per data file, a pulse repetition delay of 7.8 seconds, a flip angle of 90 degrees, and inverse gated decoupling. All measurements are performed with the sample non-spinning in locked mode. Samples are allowed to thermally equilibrate prior to data acquisition. 13 C NMR chemical shifts are internally referenced to the EEE triad at 30.0 ppm. Data are processed into spectra and appropriate peaks are integrated (to quantify branching) and then either using one or more peak integrals or averaging over total branches / 1000 C. If branching is not detected, the integrals and signal-to-noise ratios of peaks such as those due to chain ends are used to calculate the detection limit of the spectrum.

[0162] 1 Unsaturation measurement using H NMR Add the stock solution (3.26 g) to 0.10–0.13 g of polymer sample in a 10 mm NMR tube. The stock solution is 0.001 M Cr 3+ A mixture of tetrachloroethane-d2 (TCE) and perchloroethylene (50:50, w:w) with 0.001M Cr 3+ The solution in the tube is purged with N2 for 5 min to reduce the amount of oxygen. The sample is dissolved at 120-140 °C with periodic vortex mixing. 1 1 H NMR analysis is performed on a Bruker AVANCE 600 MHz spectrometer using a 10 mm cryoprobe at 120°C.

[0163] Two experiments are performed to measure the unsaturation, one control experiment and one double presaturation experiment. In the control experiment, the data are processed with an exponential window function with 0.7 Hz line broadening. 1 The signal from H is set to 100, and the integral value (I 合計 ) is used as the signal from the whole polymer in the control experiment. The total carbon number NC in the polymer is calculated by Equation 1A as follows: NC=I 合計 / 2 (Equation 1A).

[0164] For the double presaturation experiment, process the data with an exponential window function with 0.7 Hz line broadening and correct the baseline to approximately 7-4 ppm. 1 The signal from H is set to 100 and the corresponding integral for unsaturation (I ビニレン , I 三置換 , I ビニル , and I ビニリデン) was integrated. The use of NMR spectroscopy to determine polyethylenic unsaturation is known, see for example Busico, V., et al., Macromolecules, 2005, 38, 6988. The number of vinylene, trisubstituted, vinyl, and vinylidene unsaturated units is calculated as follows: N ビニレン =I ビニレン / 2 (Equation 2A), N 三置換 =I 三置換 (Equation 3A), N ビニル =I ビニル / 2 (Equation 4A), N ビニリデン =I ビニリデン / 2 (Equation 5A).

[0165] The unsaturated units per 1,000 total carbons, i.e., all polymer carbons including the backbone and branches, are calculated as follows: N ビニレン / 1,000C=(N ビニレン / NC)*1,000(Equation 6A), N 三置換 / 1,000C=(N 三置換 / NC)*1,000 (Equation 7A), N ビニル / 1,000C=(N ビニル / NCH2)*1,000 (Equation 8A), N ビニリデン / 1,000C=(N ビニリデン / NC)*1,000 (Equation 9A).

[0166] From the residual protons from TCE-d2 1 Set the chemical shift reference at 6.0 ppm for the H signal. A control is performed with a ZG pulse, NS=16, DS=2, AQ=1.82 s, D1=14 s (D1 is the relaxation delay). A double presaturation experiment is performed with a modified pulse sequence with O1P=1.354 ppm, O2P=0.960 ppm, NS=50, AQ=1.82 s, D1=1 s (D1 is the presaturation time), D13=13 s (D13 is the relaxation delay).

[0167] Crystallization elution fractionation Crystallization elution fractionation (CEF) is described in Monrabal et al, Macromol. Symp. 257, 71-79 (2007). The instrument is equipped with an IR-4 detector (such as that available from PolymerChar, Spain) and a two-angle light scattering detector model 2040 (such as that available from Precision Detectors). The IR-4 detector is operated in compositional mode with two filters, C006 and B057. A 50 x 4.6 mm 10 micron guard column (such as that available from PolymerLabs) is installed in front of the IR-4 detector in the detector furnace. Obtain orthodichlorobenzene (ODCB, 99% anhydrous grade) and 2,5-di-tert-butyl-4-methylphenol (BHT) (such as that available from Sigma-Aldrich). Silica gel 40 (particle size 0.2-0.5 mm) (such as that available from EMD Chemicals) is also obtained. Prior to use, the silica gel is dried in a vacuum oven at 160°C for approximately 2 hours. 800 milligrams of BHT and 5 grams of silica gel are added to 2 liters of ODCB. Here, the ODCB containing BHT and silica gel is referred to as "ODCB". The ODCB is sparged with dry nitrogen (N2) for 1 hour prior to use. Dry nitrogen is obtained by passing nitrogen at less than 90 psig through CaCO3 and 5 Å molecular sieves. Sample preparation is performed with an autosump at 4 mg / ml with shaking at 160°C for 2 hours. The injection volume is 300 μL. The temperature profile of the CEF is crystallization from 110°C to 30°C at 3°C / min, thermal equilibration at 30°C for 5 minutes (including soluble fraction elution time set at 2 minutes), and elution from 30°C to 140°C at 3°C / min. The flow rate during crystallization is 0.052 ml / min. The flow rate during elution is 0.50 ml / min. Data are collected at 1 data point / sec.

[0168] Pack the CEF column with glass beads (such as those commercially available from MO-SCI Specialty Products) at 125 μm ± 6% using 1 / 8 inch stainless steel tubing according to US2011 / 0015346(A1). The internal liquid volume of the CEF column is 2.1-2.3 mL. Temperature calibration is performed by using a mixture of NIST standard reference material, linear polyethylene 1475a (1.0 mg / ml) and eicosane (2 mg / ml) in ODCB. The calibration consists of four steps: (1) calculating the delay volume, defined as the temperature offset between the measured peak elution temperature of eicosane and 30.00°C; (2) subtracting a temperature offset of the elution temperature from the CEF raw temperature data (note that this temperature offset is a function of the experimental conditions such as elution temperature, elution flow rate, etc.); (3) preparing a calibration line converting elution temperatures over the range of 30.00°C to 140.00°C such that NIST linear polyethylene 1475a has a peak temperature of 101.00°C and eicosane has a peak temperature of 30.00°C; (4) The method consists of four steps: linear extrapolation of elution temperatures by using an elution heating rate of 3°C / min for the soluble fraction measured isothermally at 30°C. The reported elution peak temperatures are obtained such that the observed comonomer content calibration curve matches that previously reported in US 8,372,931.

[0169] A linear baseline is calculated by selecting two data points, one before the polymer elutes (usually at a temperature of 26° C.) and one after the polymer elutes (usually at 118° C.). For each data point, the detector signal is subtracted from the baseline before integration.

[0170] Some embodiments of the present invention will now be described in detail in the following examples. EXAMPLES

[0171] Polyethylene composition 1 The following are examples of polyethylene-based compositions that can be used in the biaxially oriented multilayer polyethylene film embodiments of the present invention, as well as in the uniaxially oriented multilayer polyethylene film embodiments of the present invention. The polyethylene-based composition embodiments described in the following examples utilize polyethylene composition 1 and polyethylene composition 2. Polyethylene composition 1 was prepared according to the following process and based on the reaction conditions reported in Table 1.

[0172] All raw materials (ethylene monomer) and process solvents (high purity narrow boiling range isoparaffinic solvent, Isopar-E) are purified with molecular sieves prior to introduction into the reaction environment. Hydrogen is supplied under pressure as a high purity grade and is not further purified. The reactor monomer feed stream is pressurized to above reaction pressure via a mechanical compressor. The solvent feed is pressurized to a pressure above reaction pressure by a pump. Individual catalyst components are manually batch diluted with purified solvent to the specified component concentrations and pressurized to a pressure above reaction pressure. All reaction feed streams are metered using mass flow meters and independently controlled by computer automated valve control systems.

[0173] A continuous solution polymerization reactor consists of two liquid-filled, non-adiabatic, isothermal circulating loop reactors similar to a continuous stirred tank reactor (CSTR) with heat removal. Independent control of all unused solvent, monomer, hydrogen, and catalyst component feeds to each reactor is possible. The entire unused feed stream (solvent, monomer, and hydrogen) to each reactor is temperature controlled by passing the feed streams through heat exchangers. The entire unused feed to each polymerization reactor is injected into the reactor at two locations per reactor, with approximately equal reactor volumes between each injection location. The fresh feed to the first reactor is typically controlled such that each injector receives half of the total unused feed mass flow rate. The unused feed to the second reactor in series is typically controlled to maintain half of the total ethylene mass flow rate near each injector, and this injector typically has less than half of the total unused feed mass flow rate to the second reactor, since unreacted ethylene from the first reactor enters the second reactor adjacent to the low pressure unused feed.

[0174] The catalyst / cocatalyst components for each injector are injected into the polymerization reactor through specially designed injection stingers. Each catalyst / cocatalyst component is injected separately into the same relative position within the reactor with no contact time prior to the reactor. The main catalyst components are computer controlled to maintain individual reaction monomer conversions at specific targets. The cocatalyst components are fed based on a specific calculated molar ratio to the main catalyst component.

[0175] The catalyst used in the first reactor is zirconium, [[2,2′′-[[bis[1-methylethyl)germylene]bis(methyleneoxy-κO)]bis[3′,5,5′-tris(1,1-dimethylethyl)-5′-octyl[1,1′:3′,1′-terphenyl]-2′-olato-κO]](2-)]dimethyl-, and has the chemical formula C 86 H 128 F2GeO4Zr and has the following structure ("Catalyst 1"): [ka] The catalyst used in the second reactor is zirconium, [[2,2''-[1,3-propanediylbis(oxy-κO)]bis[3-[2,7-bis(1,1-dimethylethyl)-9H-carbazol-9-yl]]-5'-(dimethyloctylsilyl)-3'-methyl-5-(1,1,3,3-tetramethylbutyl)[1,1]-biphenyl]-2-olato-κO]](2-)]dimethyl, and has the chemical formula C 107 H 154 N2O4Si2Zr and has the following structure ("Catalyst 2"): [ka]

[0176] Immediately after the injection point of each reactor feed, the feed stream is mixed with the contents of a circulation polymerization reactor with static mixing elements. The contents of each reactor are continuously circulated through a heat exchanger that serves to remove most of the heat of reaction and at the temperature of the coolant side that serves to maintain an isothermal reaction environment at the specified reaction temperature. Circulation around each reactor loop is provided by a pump.

[0177] The effluent from the first polymerization reactor (containing solvent, monomer, hydrogen, catalyst components, and molten polymer) exits the first reactor loop, passes through a control valve (responsible for maintaining the pressure of the first reactor at a specific target), and is injected into a second polymerization reactor of similar design. The final effluent from the second polymerization reactor enters a zone where the effluent is deactivated by addition and reaction with a suitable reagent (water). At this same reactor exit location, other additives are added for polymer stabilization. This final effluent stream passes through another set of static mixing elements to facilitate catalyst deactivation and additive dispersion.

[0178] Following catalyst deactivation and additive addition, the reactor effluent enters a devolatilization system where the polymer is removed from the non-polymer stream. The isolated polymer melt is pelletized and collected. The non-polymer stream passes through various equipment that separates most of the ethylene that is removed from the system. Most of the solvent is recycled to the reactor after passing through a purification system. A small amount of solvent is purged from the process. Polyethylene Composition 1 was stabilized with a small amount (ppm) of stabilizer.

[0179] The polymerization conditions for polyethylene composition 1 are reported in Table 1. As seen in Table 1, cocatalyst 1 (bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate(1-)amine, and cocatalyst 2 (modified methylaluminoxane (MMAO)) are used as cocatalysts for catalyst 1 and catalyst 2, respectively.

[0180] Polyethylene composition 2 is prepared using the same process as polyethylene composition 1, using the same catalyst system and under comparable reaction conditions.

[0181] Additional properties of polyethylene composition 1 and polyethylene composition 2 were measured using the test methods described above and are reported in Table 2. The first polyethylene fraction refers to the polyethylene component from the first reactor and the second polyethylene fraction refers to the polyethylene fraction from the second reactor. [Table 1] [Table 2-1] [Table 2-2]

[0182] The densities of the first polyethylene fraction of polyethylene composition 1, the overall polyethylene composition 1, and the overall polyethylene composition 2 are measured as described above in the Test Methods section. The density of the first polyethylene fraction of polyethylene composition 2 is the target value. The density of the second polyethylene fraction is calculated using the following blending rules:

number

[0183] Additional properties of polyethylene composition 1 and polyethylene composition 2 were evaluated and are reported in Table 3. [Table 3]

[0184] Polyethylene composition 1 can be dry blended with Hyperform HPN-20E nucleating agent (Milliken Chemical) provided in a masterbatch to target different final loadings of HPN-20E nucleating agent ("HPN-20E"). An example of a masterbatch of HPN-20E includes 3 weight percent HPN-20E, 1.5 weight percent silica, 0.5 weight percent hydrotalcite, 5 weight percent antioxidant, and 90 weight percent carrier resin. The carrier resin has a loading of 0.965 g / cm. 3 and a melt index (I2) of 8.0 g / 10 min. Hyperform HPN-20E contains about 66 weight percent calcium salt of 1,2-cyclohexanedicarboxylic acid and about 34 weight percent zinc stearate / palmitate. In the examples that follow, this masterbatch formed with Hyperform HPN-20E nucleating agent is referred to as "Nucleating Agent Masterbatch 1."

[0185] Similar masterbatches can be formed with Hyperform HPN 210M nucleating agent (Milliken Chemical) to target different final loadings of HPN 210M nucleating agent ("HPN 210M"). An example masterbatch of HPN 210 includes 3 weight percent HPN 210M, 1.5 weight percent silica, 0.5 weight percent hydrotalcite, 5 weight percent antioxidant, and 90 weight percent carrier resin. The carrier resin has a loading of 0.965 g / cm. 3 and a melt index (I2) of 8.0 g / 10 min. In the examples that follow, this masterbatch formed with Hyperform HPN 210M nucleating agent is referred to as "Nucleating Agent Masterbatch 2."

[0186] Example 1 The following are examples of inventive oriented multilayer polyethylene films that can be produced in accordance with embodiments of the present invention. In these examples, three-layer oriented polyethylene films can be produced using a three-layer, 2.1 meter wide Biax pilot line. The films can be produced using a three-layer die with a 3.1 mm die gap cast onto a chilled drum using an air knife pinner. The films are stretched through a series of heated variable speed rolls at a 6:1 stretch ratio in the machine direction and then at an 8:1 stretch ratio in the transverse direction. Additional information regarding the production of these films is provided below.

[0187] A multilayer film 250 mm wide may be coextruded through a three-layer die at a processing temperature of about 225°C to 260°C and cast onto a cooling drum with a controlled surface temperature of 25°C to 50°C to solidify the unoriented film at a casting speed of about 4 to 6 meters per minute. The unoriented film may be preheated in the machine direction when stretched at about 75°C to 125°C and stretched in the machine direction at about 100°C to 145°C with a stretch ratio of about 6 times the original length. The resulting stretched sheet may be annealed at about 20°C to 110°C to reduce thermal shrinkage and obtain a uniaxially oriented film. The uniaxially oriented film may be introduced into a tenter at a linear speed of about 25-30 meters per minute, preheated at about 115°C-145°C, stretched in the transverse direction at about 110°C-145°C to a stretch ratio of about 8 times its original width, and heat set or annealed at about 105°C-135°C to reduce internal stresses due to orientation, minimize heat shrinkage of the final film, and obtain a relatively thermally stable biaxially oriented film. The total thickness of the coextruded film after biaxial orientation is nominally 18 microns, with the outer layers each being 3.5 microns. The biaxially oriented multilayer film may be wound into a roll. The orientation relaxation rate in the machine direction is 3-5%, and the orientation relaxation rate in the transverse direction is 3-6%.

[0188] The film has the following structure A / B / C with respective thicknesses of 3.5 microns / 11 microns / 3.5 microns. Layer B is the core layer, and layers A and C include both the skin and subskin layers of the five-layer film stretch line. It has a final width of 1.1 m.

[0189] Films 1 to 9 of the present invention are shown in Table 3. [Table 4-1] [Table 4-2]

[0190] INNATE™ XUS59910.08 is commercially available from The Dow Chemical Company and has a viscosity of 0.926 g / cm 3 and a melt index (I2) of 1.7 g / 10 min. AFFINITY™ 1880 is a polyethylene having a density of 0.902 g / cm3 available from The Dow Chemical Company. 3 and a melt index (I2) of 1 g / 10 min. In general, one skilled in the art can identify various antiblock and slip agents that can be used in Layer C based on the teachings herein. One example of an antiblock agent that can be used is CON-X AB 601 PE, available from Kafrit Group. One example of a slip agent that can be used is CON-X SL 504 PE, available from Kafrit Group.

[0191] In some embodiments, after extrusion, rather than biaxially oriented, these films can be oriented in the machine direction only to provide uniaxially oriented films. For example, a Windmoeller & Hoelscher MDO film stretch unit can be used to orient the film in the machine direction at a temperature of 75°C to 115°C preheat (75°C for preheat 1 and 115°C for preheat 2), stretch at 125°C to 145°C, anneal at 105°C, and cool at 45°C to 75°C (e.g., 70°C). The machine direction stretch ratio can be a stretch ratio of 4:1 to 20:1 (e.g., 4:1 to 16:1, or 4:1 to 12:1, or 4:1 to 10:1, or 4:1 to 9:1). The invention as originally claimed in the present application is set forth below. [1] A biaxially oriented multilayer polyethylene film, (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 25 to 37 weight percent of a first polyethylene fraction having a density in the range of 0.935 to 0.947 g / cm3 and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition comprising 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising a calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate; 1. A biaxially oriented multilayer polyethylene film, wherein the polyethylene composition has less than 0.10 branches per 1,000 carbon atoms as measured using 13C NMR, the density of the polyethylene composition is at least 0.965 g / cm3, and the melt index (I2) of the polyethylene composition is from 0.5 to 10 g / 10 min. [2] The film of [1], wherein the film is oriented in the machine direction with a stretch ratio of 2:1 to 9:1 and in the transverse direction with a stretch ratio of 2:1 to 11:1. [3] The film according to [1] or [2], further comprising a second polyethylene composition, the second polyethylene composition exhibiting at least two local peaks, excluding the soluble fraction, in a comonomer distribution measured by crystallization elution fractionation, one of the peaks being at 40°C to 95°C. [4] The film described in [3], wherein the layer containing the polyethylene composition further contains the second polyethylene composition. [5] Overall density: 0.931–0.975 g / cm 3 The film according to any one of [1] to [4], [6] The film according to any one of [1] to [5], wherein the film has a thickness of 5 to 50 microns. [7] The film according to any one of [1] to [6], further comprising a layer containing polyamide or ethylene vinyl alcohol. [8] The film according to any one of [1] to [7], wherein the outer layer is a sealant layer. [9] The film described in any of [1] to [8], further comprising a layer containing a metal deposited on an outer layer of the film, the metal comprising Al, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, Si, Mg, or an oxide thereof.

[10] A uniaxially oriented multilayer polyethylene film, (1) (a) at least 97 wt.% of a polyethylene composition, based on a total weight of the polyethylene composition, (i) 25 to 37 weight percent of a first polyethylene fraction having a density in the range of 0.935 to 0.947 g / cm3 and a melt index (I2) of less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) at least one layer comprising a polyethylene-based composition, the polyethylene-based composition comprising 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising a calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate; 1. A uniaxially oriented multilayer polyethylene film, wherein the polyethylene composition has less than 0.10 branches per 1,000 carbon atoms as measured using 13C NMR, the density of the polyethylene composition is at least 0.965 g / cm3, and the melt index (I2) of the polyethylene composition is from 0.5 to 10 g / 10 min.

[11] The film of

[10] , wherein the film is oriented in the machine direction at a stretch ratio of 4:1 to 20:1.

[12] The film according to

[10] or

[11] , further comprising a second polyethylene composition, the second polyethylene composition exhibiting at least two local peaks, excluding the soluble fraction, in a comonomer distribution measured by crystallization elution fractionation, one of the peaks being at 40°C to 95°C.

[13] The film of

[12] , wherein the layer comprising the polyethylene composition further comprises the second polyethylene composition.

[14] The film according to any one of

[10] to

[13] , having an overall density of 0.931 to 0.975 g / cm3.

[15] The film according to any one of

[10] to

[14] , wherein the film has a thickness of 5 to 50 microns.

[16] The film according to any one of

[10] to

[15] , further comprising a layer containing polyamide or ethylene vinyl alcohol.

[17] The film according to any one of

[10] to

[16] , wherein the outer layer is a sealant layer.

[18] The film according to any one of

[10] to

[17] , further comprising a layer comprising a metal deposited on an outer layer of the film, the metal comprising Al, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, Si, Mg, or an oxide thereof.

[19] An article comprising the film according to any one of [1] to

[18] .

[20] A laminate comprising: a first film comprising a polyethylene sealant film, polyethylene terephthalate, polypropylene, or polyamide; [1] to

[18] , and A laminate, wherein the first film is laminated to the multilayer polyethylene film.

[21] An article comprising the laminate described in

[20] .

Claims

1. 1. A biaxially oriented multilayer polyethylene film, comprising: （１） (a) at least 97 wt.% of a polyethylene composition, based on the total weight of the polyethylene composition, (i) 25 to 37 weight percent of a first polyethylene fraction having a density in the range of 0.935 to 0.947 g / cm3 and a melt index (I2) less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising a calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate; 1. A biaxially oriented multilayer polyethylene film, wherein the polyethylene composition has less than 0.10 branches per 1,000 carbon atoms as measured using 13C NMR, the density of the polyethylene composition is at least 0.965 g / cm3, and the melt index (I2) of the polyethylene composition is from 0.5 to 10 g / 10 min.

2. The film of claim 1, wherein the film is oriented in the machine direction with a stretch ratio of from 2:1 to 9:1 and in the transverse direction with a stretch ratio of from 2:1 to 11:

1.

3. 3. The film of claim 1 or claim 2, further comprising a second polyethylene composition, said second polyethylene composition exhibiting at least two local peaks in comonomer distribution measured by crystallization elution fractionation, excluding the soluble fraction, one of the peaks being between 40°C and 95°C.

4. 4. The film of claim 3, wherein the layer comprising the polyethylene-based composition further comprises the second polyethylene composition.

5. The film of any one of claims 1 to 4, having an overall density of 0.931 to 0.975 g / cm3.

6. A uniaxially oriented multilayer polyethylene film, （１） (a) at least 97 wt.% of a polyethylene composition, based on the total weight of the polyethylene composition, (i) 25 to 37 weight percent of a first polyethylene fraction having a density in the range of 0.935 to 0.947 g / cm3 and a melt index (I2) less than 0.1 g / 10 minutes; (ii) 63 to 75 weight percent of a second polyethylene fraction; and (b) 20 to 5000 ppm of a nucleating agent, based on the total weight of the polyethylene-based composition, the nucleating agent comprising a calcium salt of 1,2-cyclohexanedicarboxylic acid or sodium 4-[(4-chlorobenzoyl)amino]benzoate; 1. A uniaxially oriented multilayer polyethylene film, wherein the polyethylene composition has less than 0.10 branches per 1,000 carbon atoms as measured using 13C NMR, the density of the polyethylene composition is at least 0.965 g / cm3, and the melt index (I2) of the polyethylene composition is from 0.5 to 10 g / 10 min.

7. The film of claim 6, wherein the film is oriented in the machine direction at a stretch ratio of from 4:1 to 20:

1.

8. 8. The film of claim 6 or claim 7, further comprising a second polyethylene composition, said second polyethylene composition exhibiting at least two local peaks in comonomer distribution measured by crystallization elution fractionation, excluding the soluble fraction, one of the peaks being between 40°C and 95°C.

9. 9. The film of claim 8, wherein the layer comprising the polyethylene-based composition further comprises the second polyethylene composition.

10. An article comprising the film of any one of claims 1 to 9.

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