Multilayer film comprising an ethylene-based polymer

Abstract

Provided are multilayer films comprising ethylene-based polymers. The multilayer films can be fully compatible with polyethylene recycle streams. The multilayer films include a first outer layer, a second outer layer, and a core comprising a first core layer comprising an ethylene-propylene copolymer. The multilayer films of the present invention can exhibit improved, maintained, or desired properties, such as high tear resistance, compared to existing multilayer film structures that are not fully compatible with polyethylene recycle streams.

Description

Technical Field

[0001] The embodiments disclosed herein relate generally to multilayer membranes, and more specifically to multilayer membranes comprising ethylene-based polymers. Background Technology

[0002] Multilayer films incorporating various materials, including polypropylene, polyamide, and polyethylene terephthalate, are widely used in industrial and consumer products. Such films used in industrial and consumer products typically require sufficient tear resistance, for example, to prevent breakage during the film wrapping process on a pallet. The combination of layers and materials allows for good film performance, but because different types of materials are not recyclable and compatible with each other, such multilayer films may be difficult (if not impossible) to recycle together. As the demand for sustainable and recyclable materials continues to rise, there remains a need for multilayer films that are easier to recycle and exhibit desired performance characteristics, such as tear resistance. Summary of the Invention

[0003] Embodiments of this disclosure satisfy one or more of the aforementioned requirements by providing a multilayer membrane exhibiting comparable or improved tear resistance and comprising a recyclable, compatible ethylene-based polymer. The multilayer membrane can be fully recyclable in a polyethylene recycling stream, and the tear resistance of the multilayer membrane of the present invention can be comparable to or better than other multilayer membranes that do not contain a recyclable, compatible polymer. Without being bound by theory, among other features, in some embodiments, the structure of the membrane having a thin first core layer and a specific ethylene-propylene copolymer results in surprisingly desirable tear resistance when compared to existing membrane structures.

[0004] This document discloses a multilayer membrane. In one aspect, the multilayer membrane includes a first outer layer, a second outer layer, and a core, the core comprising one or more core layers; wherein the core is positioned between the first and second outer layers; wherein, based on the total polymer weight of the core, the core comprises greater than 90 wt% ethylene-based polymer; and wherein the first core layer comprises an ethylene-propylene copolymer comprising 60 wt% to 95 wt% ethylene monomer and 5 wt% to 40 wt% propylene comonomer, the ethylene-propylene copolymer having a content of 0.865 g / cm³. 3 Up to 0.920 g / cm 3 The density and melt index (I2) of the core are at least 0.5 g / 10 min, and the core contains less than 40% by weight of ethylene-propylene copolymer based on the total weight of the core.

[0005] These and other implementation schemes are described in more detail in the specific embodiments. Attached Figure Description

[0006] Figure 1 is a schematic diagram of a single reactor data flow graph.

[0007] Figure 2 shows the ICCD elution curves of polymer 1 and polymer 2 (the development resins described herein). Detailed Implementation

[0008] The disclosed multilayer film is described in more detail below. Multilayer films can have a variety of applications, including, for example, cast and stretched films, blown films, oriented films, stretched cover films, etc. However, this disclosure should not be construed as limiting the embodiments set forth below, as this disclosure is an illustrative description of the embodiments described herein.

[0009] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers of the same or different types. Therefore, the general term polymer encompasses the term homopolymer (used to refer to a polymer prepared from only one type of monomer) and the term copolymer. Trace impurities (e.g., catalyst residues) may be incorporated into and / or within a polymer. A polymer can be a single polymer, a polymer blend, or a mixture of polymers comprising a mixture of polymers formed in situ during polymerization.

[0010] As used herein, the term "copolymer" refers to a polymer formed by the polymerization of at least two monomers with different structures. The term "copolymer" includes terpolymers. For example, ethylene copolymers (such as ethylene-propylene copolymers) comprise at least two structurally different monomers (e.g., an ethylene-propylene copolymer comprises copolymer units of at least ethylene monomers and propylene monomers) and may optionally include additional monomers or functional materials or modifiers, such as acid, acrylate, or anhydride functional groups. In other words, copolymers described herein contain at least two structurally different monomers, and although copolymers may consist of only two structurally different monomers, they do not necessarily consist of only two structurally different monomers and may contain additional monomers or functional materials or modifiers.

[0011] As used herein, the terms "polyethylene" or "ethylene-based polymer" should mean a polymer comprising a majority amount (>50% by weight) of units derived from ethylene monomers. This includes polyethylene homopolymers and copolymers (meaning units derived from two or more comonomers). Unless otherwise explicitly stated, the ethylene copolymers disclosed herein (e.g., the ethylene-propylene copolymers described herein) are ethylene-based polymers.

[0012] Common forms of polyethylene known in the art include low-density polyethylene (LDPE); linear low-density polyethylene (LLDPE); ultra-low-density polyethylene (ULDPE); very low-density polyethylene (VLDPE); single-point catalytic linear low-density polyethylene, including linear and substantially linear low-density resins (m-LLDPE); 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; however, the following description may help to understand the differences between some of these different polyethylene resins.

[0013] The term "LDPE" can also be referred to as "high-pressure ethylene polymer" or "highly branched polyethylene," and it is defined as meaning that the polymer is partially or wholly homopolymerized or copolymerized in an autoclave or tubular reactor at pressures above 14,500 psi (100 MPa) using a free radical initiator (such as peroxide) (see, for example, US 4,599,392, which is hereby incorporated herein by reference). LDPE resin typically has a viscosity of 0.916 g / cm³. 3 Up to 0.935 g / cm 3 The density within the range.

[0014] The term "LLDPE" encompasses two resins prepared using conventional Ziegler-Natta catalyst systems and chromium-based catalyst systems, as well as single-site catalysts (including, but not limited to, substituted mono- or dicyclopentadienyl catalysts (commonly referred to as metallocenes), confined geometry catalysts, phosphine imine catalysts, and polyvalent aryloxy ether catalysts (commonly referred to as diphenylphenoxys), and comprising linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains less long-chain branching than LDPE and includes substantially linear ethylene polymers further defined in U.S. Patents 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; non-homogeneously 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 in US 3,914,342 or US 4,076,698). (Those disclosed in 5,854,045). LLDPE can be prepared by gas-phase, solution-phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0015] The term "MDPE" refers to a material with a density of 0.926 g / cm³. 3Up to 0.935 g / cm 3 Polyethylene. “MDPE” is typically prepared using chromium or Ziegler-Natta catalysts or using single-point catalysts, including but not limited to substituted mono- or di-cyclopentadienyl catalysts (commonly known as metallocenes), confined geometry catalysts, phosphine imine catalysts, and polyvalent aryloxy ether catalysts (commonly known as bisphenylphenoxy), and typically has a molecular weight distribution (“MWD”) greater than 2.5.

[0016] The term "HDPE" refers to a material with a density greater than approximately 0.935 g / cm³. 3 And at most about 0.980 g / cm 3 Polyethylene is generally prepared using Ziegler-Natta catalysts, chromium catalysts, or single-point catalysts (including but not limited to substituted mono- or di-cyclopentadienyl catalysts (commonly known as metallocenes), confined geometry catalysts, phosphine imine catalysts, and polyvalent aryloxy ether catalysts (commonly known as bisphenylphenoxy).

[0017] The term "ULDPE" refers to a material with a density of 0.855 g / cm³. 3 Up to 0.912 g / cm 3 Polyethylene, which is generally prepared using Ziegler-Natta catalysts, chromium catalysts, or single-site catalysts (including but not limited to substituted mono- or di-cyclopentadienyl catalysts (commonly known as metallocenes), confined geometry catalysts, phosphine imine catalysts, and polyvalent catalysts (commonly known as bisphenylphenoxys)). ULDPE includes, but is not limited to, polyethylene (ethylene-based) plasmons and polyethylene (ethylene-based) elastomers.

[0018] As used herein, the term "core layer" refers to a non-surface or non-outer layer of a multilayer film. The core layer is an inner layer of a multilayer film, i.e., a layer positioned between two outer layers. In one embodiment, the core layer is a non-outer layer of a three-layer film comprising a first outer layer and a second outer layer. All core layers (i.e., one or more) in the multilayer film of the present invention constitute the "core" of the film.

[0019] The terms “comprising,” “including,” “having,” and their derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether or not such components, steps, or procedures are specifically disclosed. For the avoidance of any doubt, unless stated to the contrary, all compositions claimed using the term “comprising” may include any additional additives, adjuvants, or compounds, whether polymerized or otherwise. In contrast, the term “consistently composed of” excludes any other components, steps, or procedures from any subsequently listed scope, except those that are not essential for operability. The term “composed of” excludes any ingredients, steps, or procedures not specifically described or listed.

[0020] This document discloses multilayer films. In some embodiments, the multilayer film may be an oriented film oriented in the longitudinal and / or transverse directions. In some embodiments, the multilayer film is a blown film. In other embodiments, the multilayer film is a cast stretch film. In still other embodiments, the multilayer film is a stretch cap film.

[0021] The multilayer film according to the embodiments disclosed herein includes a first outer layer, a second outer layer, and a core, the core including one or more core layers. The core is positioned between the first and second outer layers. The core includes a first core layer comprising an ethylene-propylene copolymer.

[0022] The first outer layer and the second outer layer of the multilayer film

[0023] The first and second outer layers may have the same polymer composition or different polymer compositions. In some embodiments, each of the first and second outer layers has a thickness of 10% to 40% of the total thickness of the multilayer film.

[0024] In some embodiments, the first outer layer and / or the second outer layer comprises polyethylene with a density less than 0.930 g / cc and a melt index (I2) less than 7 g / 10 min. This document discloses and includes all individual values ​​and sub-ranges of densities less than 0.930 g / cc. For example, the polyethylene of the first outer layer and / or the second outer layer may have densities less than 0.925 g / cc, less than 0.920 g / cc, less than 0.915 g / cc, less than 0.910 g / cc, less than 0.905 g / cc, or less than 0.900 g / cc, or in the range of 0.865 g / cc to 0.925 g / cc, or 0.875 g / cc to 0.925 g / cc. This document discloses and includes all individual values ​​and sub-ranges of melt index (I2) less than 7 g / 10 min. For example, the polyethylene in the first outer layer and / or the second outer layer may have a melt index (I2) of less than 6 g / 10 min, less than 5 g / 10 min, less than 4 g / 10 min, less than 3 g / 10 min, or less than 2 g / 10 min, or in the range of 0.5 g / 10 min to 6 g / 10 min, 0.5 g / 10 min to 5 g / 10 min, or 0.5 g / 10 min to 4 g / 10 min.

[0025] In some embodiments, the first outer layer and / or the second outer layer comprises 70% to 100% polyethylene based on the total weight of the respective layers. All individual values ​​of 70% to 100% are disclosed and included herein. For example, the first outer layer and / or the second outer layer may comprise 70% to 95% polyethylene, 75% to 95% polyethylene, 75% to 90% polyethylene, or 80% to 90% polyethylene.

[0026] Commercially available examples of polyethylene that can be used for the first outer layer and / or the second outer layer include those available from The Dow Chemical Company under the name DOWLEX. TM Those obtained through commercial purchases, including, for example, DOWLEX TM AT8090.

[0027] In some embodiments, the first and second outer layers comprise LDPE. In embodiments where the first and / or second outer layers comprise LDPE, the LDPE may have a concentration of 0.916 g / cm³. 3 Up to 0.935 g / cm 3 Density within the specified range. This document includes and discloses 0.916 g / cm³. 3 Up to 0.935 g / cm 3 All individual values ​​and sub-ranges; for example, the density of LDPE can be 0.916 g / cm³. 3 0.918 g / cm 3 0.920g / cm 3 0.922g / cm 3 The lower limit is 0.935 g / cm³. 3 0.933g / cm 3 0.931 g / cm 3 Or 0.929 g / cm 3 The upper limit.

[0028] In embodiments in which the first outer layer and / or the second outer layer comprises LDPE, the LDPE may have a melt index (I2) in the range of 0.1 g / 10 min to 50 g / 10 min. All individual values ​​and sub-ranges of 0.1 g / 10 min to 50 g / 10 min are disclosed and included herein. For example, LDPE may have a melt index (I2) in the range of 0.1 g / 10 min to 40 g / 10 min, 0.1 g / 10 min to 30 g / 10 min, 0.1 g / 10 min to 20 g / 10 min, 0.1 g / 10 min to 10 g / 10 min, or 0.1 g / 10 min to 5 g / 10 min.

[0029] In some embodiments, the first outer layer and / or the second outer layer may contain 0% to 30% LDPE based on the total weight of the respective layers. All individual values ​​from 0% to 30% LDPE are disclosed and included herein. For example, the first outer layer and / or the second outer layer may contain 5% to 25% LDPE or 10% to 20% LDPE based on the total weight of the respective layers.

[0030] Commercially available examples of LDPE that can be used for the first outer layer and / or the second outer layer include those available from Dow Chemical Company under the name DOW TM Those LDPE 310E obtained through commercial purchase.

[0031] Multilayer film core

[0032] The multilayer membrane includes a core. The core includes one or more core layers and comprises 90% by weight of an ethylene-based polymer, including an ethylene-propylene copolymer (described below). The core is positioned between a first outer layer and a second outer layer. The core includes a first core layer. In some embodiments, the multilayer membrane disclosed herein is a three-layer membrane comprising a first outer layer, a second outer layer, and a core, wherein the core includes a first core layer. In other embodiments, the multilayer membrane comprises at least five layers. For example, in some embodiments, the core comprises a first core layer, a second core layer, and a third core layer, wherein the first core layer is positioned between the second and third core layers, the second core layer is positioned between the first outer layer and the first core layer, and the third core layer is positioned between the first core layer and the second outer layer. In embodiments where the core comprises a first core layer, a second core layer, and a third core layer, the multilayer membrane comprises at least five layers (e.g., a multilayer membrane having a structure of first outer layer / second core layer / first core layer / third core layer / second outer layer).

[0033] For example, in some embodiments, the multilayer film includes at least five layers, including a first outer layer, a second outer layer, a first core layer, a second core layer, and a third core layer, wherein the first core layer is positioned between the second core layer and the third core layer, and the second core layer and the third core layer each contain polyethylene with a density of less than 0.930 g / cc and a melt index (I2) of less than 7 g / 10 min.

[0034] The core includes a first core layer. In some embodiments, the first core layer comprises an ethylene-propylene copolymer comprising 60% to 90% by weight of ethylene monomer and 10% to 40% by weight of propylene comonomer. In some embodiments, the ethylene-propylene copolymer has a density of 0.865 g / cc to 0.920 g / cc and a melt index (I2) of at least 0.5 g / 10 min. In some embodiments, the ethylene-propylene copolymer is formed in the presence of a catalyst composition comprising a unit point metallocene catalyst.

[0035] In some embodiments, based on the total weight of the ethylene-propylene copolymer, the ethylene-propylene copolymer of the first core layer comprises 60 wt% to 95 wt% ethylene monomer and 5 wt% to 40 wt% propylene comonomer. This document discloses and includes all individual values ​​and sub-ranges of 60 wt% to 95 wt% ethylene monomer and 5 wt% to 40 wt% propylene comonomer. For example, the ethylene-propylene copolymer may comprise 60 wt% to 95 wt%, 60 wt% to 90 wt%, 70 wt% to 90 wt%, or 80 wt% to 90 wt% ethylene monomer, and may comprise 5 wt% to 40 wt%, 10 wt% to 40 wt%, 10 wt% to 30 wt%, or 10 wt% to 20 wt% propylene comonomer. The comonomer content can be measured using any suitable technique, such as techniques based on nuclear magnetic resonance (“NMR”) spectroscopy, and for example, by 13C NMR analysis as described in U.S. Patent 7,498,282 (which is incorporated herein by reference).

[0036] In some embodiments, the ethylene-propylene copolymer has a density in the range of 0.865 g / cc to 0.920 g / cc. All individual values ​​and sub-ranges of 0.865 g / cc to 0.920 g / cc are disclosed and included herein. For example, the ethylene-propylene copolymer may have a density in the range of 0.870 g / cc to 0.920 g / cc, 0.880 g / cc to 0.910 g / cc, 0.895 g / cc to 0.905 g / cc, or 0.895 g / cc to 0.910 g / cc.

[0037] In some embodiments, the ethylene-propylene copolymer has a melt index (I2) of at least 0.5 g / 10 min. This document discloses and includes all individual values ​​and sub-ranges of at least 0.5 g / 10 min. For example, the ethylene-propylene copolymer may have a melt index (I2) of at least 0.5 g / 10 min, at least 0.6 g / 10 min, at least 0.7 g / 10 min, at least 0.8 g / 10 min, at least 0.9 g / 10 min, or at least 1.0 g / 10 min, or may have a melt index (I2) in the range of 0.5 g / 10 min to 500 g / 10 min, 0.5 g / 10 min to 200 g / 10 min, 0.5 g / 10 min to 100 g / 10 min, 0.5 g / 10 min to 50 g / 10 min, 0.5 g / 10 min to 10 g / 10 min, or 0.5 g / 10 min to 8 g / 10 min.

[0038] In some embodiments, the ethylene-propylene copolymer exhibits a single peak in the modified comonomer composition distribution (ICCD) elution profile within a temperature range of 40°C to 100°C. The modified comonomer composition distribution (ICCD) profile of the ethylene-propylene copolymer can be obtained via the test methods described below.

[0039] In some embodiments, the ethylene-propylene copolymer has a molecular weight distribution (Mw / Mn) in the range of 1.5 to 5.0. All individual values ​​and sub-ranges of 1.5 to 5.0 are disclosed and included herein. For example, the ethylene-propylene copolymer may have a molecular weight distribution (Mw / Mn) in the ranges of 1.5 to 5.0, 1.6 to 5.0, 1.8 to 5.0, 2.0 to 5.0, 1.5 to 4.0, 1.6 to 4.0, 1.8 to 4.0, 2.0 to 4.0, 1.5 to 3.0, 1.8 to 3.0, 2.0 to 3.0, 1.5 to 2.5, 1.8 to 2.5, or 2.0 to 2.5. The molecular weight distribution (Mw / Mn) can be measured according to the GPC test method described below.

[0040] In some embodiments, the ethylene-propylene copolymer is further characterized by having a melt flow ratio of 5 to 14 (I 10 / I2). This document discloses and includes all individual values ​​and sub-ranges of 5 to 14. For example, ethylene-propylene copolymers may have melt flow ratios of 5 to 14, 6 to 12, 6 to 10, or 5 to 10 (I 10 / I2).

[0041] In some embodiments, the ethylene-propylene copolymer has a heat of fusion in the range of 40 J / g to 150 J / g. All individual values ​​and sub-ranges of 40 J / g to 150 J / g are disclosed and included herein. For example, the ethylene-propylene copolymer may have a heat of fusion in the ranges of 40 J / g to 110 J / g to 150 J / g, 45 J / g to 130 J / g, 50 J / g to 120 J / g, 60 J / g to 110 J / g, 70 J / g to 110 J / g, 80 J / g to 110 J / g, and 90 J / g to 110 J / g, wherein the heat of fusion is measured according to the DSC test method described below.

[0042] In some embodiments, the first core layer comprises 60 wt% to 100 wt% of an ethylene-propylene copolymer based on the total weight of the first core layer. All individual values ​​and sub-ranges of 60 wt% to 100 wt% are disclosed and included herein. For example, the first core layer may comprise 65 wt% to 100 wt%, 75 wt% to 95 wt%, 80 wt% to 90 wt%, or 90 wt% to 100 wt% of the ethylene-propylene copolymer, wherein the weight percentage (wt%) is based on the total weight of the first core layer.

[0043] In some embodiments, in addition to the ethylene-propylene copolymer, the first core layer may also contain 0% to 40% or 5% to 20% by weight of an ethylene-based polymer, such as ULDPE, LLDPE, LDPE, MDPE, or HDPE, based on the total weight of the first core layer. For example, in some embodiments, the first core layer contains 5% to 20% by weight of polyethylene resin, wherein the weight percentage is based on the total weight of the first core layer.

[0044] In embodiments where the first core layer comprises polyethylene resin, the polyethylene resin may have a content of less than or equal to 0.930 g / cm³. 3 The density of the sample is included and disclosed herein. This document includes and discloses samples with a density less than or equal to 0.930 g / cm³. 3 All individual values ​​and sub-ranges; for example, the density of linear low-density polyethylene can range from a lower limit of 0.870 g / cm³. 3 Up to the upper limit of 0.928 g / cm 3 0.925g / cm 3 0.920g / cm 3 Or 0.915g / cm 3 This article includes and discloses 0.870 g / cm³. 3 With 0.930 g / cm 3 All individual values ​​and subranges between.

[0045] In some embodiments, the second core layer and / or the third core layer has the same polymer composition as the first core layer. In other embodiments, the second core layer and / or the third core layer has a different polymer composition than the first core layer. For example, in some embodiments, the third core layer further comprises an ethylene-propylene copolymer. That is, in some embodiments, the third core layer comprises an ethylene-propylene copolymer containing 60% to 90% by weight of ethylene monomer and 10% to 40% by weight of propylene comonomer. In such embodiments, the third core layer may have the same polymer composition as the first core layer, and the ethylene-propylene copolymer of the third core layer may have the same characteristics as the ethylene-propylene copolymer of the first core layer (described above).

[0046] In some embodiments, the thickness of the first core layer is less than 30% of the total thickness of the multilayer film. This document discloses and includes all individual values ​​and sub-ranges of less than 30%. For example, the thickness of the first core layer may be less than 25%, less than 20%, less than 15%, less than 10%, or less than 5% of the total thickness of the multilayer film; or, for example, the first core layer may comprise 2% to 30% of the total thickness of the multilayer film, or 8% to 25% of the total thickness of the multilayer film.

[0047] In some embodiments, based on the total weight of the core, the core of the multilayer film contains 90% by weight of an ethylene-based polymer, or 95% by weight of an ethylene-based polymer, or 100% by weight of an ethylene-based polymer.

[0048] In some embodiments, the core of the multilayer film comprises less than 40 wt% ethylene-propylene copolymer based on the total weight of the core. All individual values ​​and sub-ranges of less than 40 wt% are disclosed and included herein. For example, based on the weight of the core, the core may comprise less than 35 wt%, less than 30 wt%, less than 25 wt%, less than 20 wt%, or less than 15 wt% ethylene-propylene copolymer.

[0049] additive

[0050] It should be understood that any of the aforementioned layers may further include one or more additives known to those skilled in the art, such as antioxidants, UV stabilizers, heat stabilizers, slip agents, antiblocking agents, antistatic agents, pigments or colorants, processing aids, crosslinking catalysts, flame retardants, fillers, and foaming agents. For example, in some embodiments, the first outer layer and the second outer layer each contain an antiblocking agent.

[0051] Multilayer film

[0052] The multilayer films disclosed herein can be produced using techniques known to those skilled in the art, based on the teachings herein. For example, multilayer films can be produced by co-extrusion. The formation of co-extruded multilayer films is known in the art and is applicable to this disclosure. A co-extrusion system for manufacturing multilayer films employs at least two extruders feeding a common die assembly. The number of extruders depends on the number of different materials or polymers constituting the co-extruded film. For example, a five-layer co-extrusion may require up to five extruders, but if two or more layers are made of the same material or polymer, fewer extruders can be used.

[0053] In various embodiments, the multilayer film of the present invention can possess several desired properties. Without being bound by any theory, a specific structure of the multilayer film (e.g., a core comprising less than 40% by weight of an ethylene-propylene copolymer), along with the inclusion of a specific ethylene-propylene copolymer in the core, can result in a multilayer film with desired tear resistance properties. In some embodiments, the multilayer film exhibits transverse tear resistance of at least 1500 g (or at least 1600 g, or at least 1700 g, or at least 1800 g), or in the range of 1500 g to 3500 g, 1600 g to 3500 g, 1700 g to 3500 g, or 1800 g to 3500 g, wherein the thickness of the multilayer film is 100 μm. Transverse tear resistance can be expressed in grams per micrometer of the multilayer film thickness. For example, in some embodiments, the multilayer film may exhibit transverse tear resistance of at least 16.66 g / μm (or at least 20 g / μm, or at least 23.33 g / μm, or at least 26.66 g / μm), or in the range of 16.66 g / μm to 33.33 g / μm, 20 g / μm to 33.33 g / μm, 23.33 g / μm to 33.33 g / μm, or 26.66 g / μm to 33.33 g / μm. Transverse tear resistance can be measured according to ASTM D1922-09.

[0054] In some embodiments, the multilayer film has a thickness between 6 micrometers (μm) and 150 micrometers, or alternatively between 6 micrometers and 100 micrometers, or alternatively between 6 micrometers and 50 micrometers.

[0055] In some embodiments, based on the total weight of the multilayer membrane, the multilayer membrane of the present invention comprises at least 90% by weight of an ethylene-based polymer, or at least 95% by weight of an ethylene-based polymer, or at least 99% by weight of an ethylene-based polymer, or at least 99.5% by weight of an ethylene-based polymer, or at least 99.9% by weight of an ethylene-based polymer. Because in some embodiments the multilayer membrane comprises at least 90% by weight of an ethylene-based polymer, they are compatible with polyethylene recycling streams.

[0056] In some embodiments, the multilayer film is a longitudinally oriented film. In other embodiments, the multilayer film is a cast-stretched film. In still other embodiments, the multilayer film is a blown film.

[0057] Products

[0058] Embodiments of the present invention also provide articles comprising any of the multilayer films of the present invention described herein. Examples of such articles may include wraps, packages, flexible packaging, bags, and pouches. In view of the teachings herein, articles of the present invention can be formed from the multilayer films disclosed herein using techniques known to those skilled in the art.

[0059] Test methods

[0060] density

[0061] Density was measured according to ASTM D792 and expressed in grams per cubic centimeter. 3 (g / cm 3 Or g / cc) indicates.

[0062] Melt index (I2 and I) 10 )

[0063] Melt index (I²) was measured according to ASTM D-1238 at 190°C and 2.16 kg. 10 Measured according to ASTM D-1238 at 190°C and 10 kg. The melt index value is reported in g / 10 min, corresponding to the number of grams eluted per 10 minutes. The melt flow rate is I. 10 / I2.

[0064] Improved comonomer composition distribution (ICCD)

[0065] An improved method for comonomer content analysis (iCCD) was developed in 2015 (Cong and Parrott et al., WO2017040127A1). iCCD tests were performed using a Crystallization Elution Fractionation (CEF) instrument (Perimocha, Spain) equipped with an IR-5 detector (PolymerChar, Spain) and a two-corner light scattering detector model 2040 (Precision Detectors, now Agilent Technologies). A guard column filled with 20-27 micron glass (MoSCi Corporation, USA) was installed just before the IR-5 detector in the detector oven. o-Dichlorobenzene (ODCB, 99% anhydrous or industrial grade) was used. The benzene was sourced from EMD Chemicals. Chemicals obtained silica gel 40 (particle size 0.2–0.5 mm, catalog number 10181-3) (which could previously be used as a solvent for drying ODCB). The dried silica was packed into three empty HT-GPC columns to further purify ODCB as the eluent. The CEF instrument was equipped with an autosampler with N2 sweep capability. ODCB was bubbled with dry nitrogen (N2) for one hour before use. Sample preparation was performed at 160°C with shaking at a concentration of 4 mg / mL (unless otherwise specified) using an autosampler for 1 hour. The injection volume was 300 μL. The iCCD temperature profile was as follows: crystallization from 105°C to 30°C at 3°C / min, thermal equilibration at 30°C for 2 minutes (including elution time for the soluble fraction set to 2 minutes), and elution from 30°C to 140°C at 3°C / min. The flow rate during crystallization was 0.0 mL / min. The flow rate during elution was 0.50 mL / min. Data were collected at a rate of one data point per second.

[0066] An iCCD column was filled with gold-plated nickel particles (Bright7GNM8-NiS, Nippon Chemical Industrial Co.) in a 15cm (length) x 1 / 4” (ID) stainless steel tube. The column was filled and conditioned using a slurry method, following references (Cong, R.; Parrott, A.; Hollis, C.; Cheatham, M. WO2017040127A1). The final pressure for TCB slurry filling was 150 bar.

[0067] Column temperature calibration was performed using a mixture of a reference material, linear homopolymer polyethylene (with zero comonomer content, melt index (I2) of 1.0, polydispersity Mw / Mn of approximately 2.6 by conventional gel permeation chromatography, 1.0 mg / ml) and ODCB containing eicosane (2 mg / ml). The iCCD temperature calibration consisted of four steps: (1) calculating the delay volume, which was defined as the measured peak elution temperature of eicosane minus the temperature bias between 30.00 °C and the measured peak elution temperature; and (2) subtracting the temperature bias of the elution temperature from the raw iCCD temperature data. It should be noted that the temperature bias is a function of experimental conditions, such as elution temperature, elution flow rate, etc.; (3) A linear calibration line for switching elution temperatures in the range of 30.00 °C and 140.00 °C is established such that the linear homopolymer polyethylene reference has a peak temperature at 101.0 °C and the eicosane has a peak temperature at 30.0 °C; (4) For soluble fractions measured isothermally at 30 °C, elution temperatures below 30.0 °C are linearly extrapolated by using an elution heating rate of 3 °C / min, according to the reference (Cerk and Cong et al., US9,688,795).

[0068] A relationship between comonomer content and elution temperature of iCCD was constructed using 12 reference materials (ethylene homopolymers and ethylene-octene random copolymers prepared with unit-point metallocene catalysts, with ethylene equivalent weight-average molecular weights ranging from 35,000 to 128,000). All these reference materials were analyzed in the same manner as previously specified at 4 mg / mL. The reported elution peak temperatures follow the relationship between octene mol% and R in the figure. 2 The elution temperature of the iCCD is 0.978.

[0069]

[0070] By assuming a shape factor of 1 and all virial coefficients equal to zero, the molecular weight of the polymer and polymer fractions were determined directly from the LS detector (90-degree angle) and the concentration detector (IR-5) according to the Rayleigh-Gans-Debys approximation (Striegel and Yau, Modern Size Exclusion Liquid Chromatogram, pp. 242 and 263). An integration window was set to integrate all chromatograms over an elution temperature range of 23.0 °C to 120 °C (temperature calibration specified above).

[0071] Calculating molecular weight (Mw) from iCCD involves the following steps: (1) Measuring the inter-detector bias. The bias is defined as the geometric volume shift between the LS detector and the concentration detector. It is calculated as the difference in elution volume (mL) of the polymer peak between the concentration detector and the LS chromatogram. This is converted to a temperature bias using the elution heat rate and elution flow rate. Using linear high-density polyethylene (comonomer content of zero, melt index (I2) of 1.0), the polydispersity Mw was obtained by conventional gel permeation chromatography. w / M n Approximately 2.6). The same experimental conditions as the normal iCCD method described above were used, except for the following parameters: crystallization from 140°C to 137°C at 10°C / min, thermal equilibration at 137°C for 1 minute as the elution time for the soluble fraction, and elution of the soluble fraction (SF) from 137°C to 142°C at 3°C / min. The flow rate during crystallization was 0.0 mL / min. The flow rate during elution was 0.80 mL / min. The sample concentration was 1.0 mg / mL. (2) Before integration, each LS data point in the LS chromatogram was shifted to correct for inter-detector bias. (3) The baseline of step (1) was subtracted from the LS and concentration chromatograms over the entire elution temperature range. The MW detector constant was calculated using known MW HDPE samples in the range of 100,000 to 140,000 Mw and the area ratio of the integrated LS and concentration signals. (4) The Mw of the polymer was calculated by using the ratio of the integrated light scattering detector (90-degree angle) to the concentration detector and the MW detector constant.

[0072] Conventional GPC (Mw / Mn)

[0073] The chromatographic system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) connected to a Precision Detector (now an Agilent Technologies 2040 2-angle laser scattering (LS) detector). A 15-degree angle was used for all light scattering measurements. The autosampler oven chamber was set to 160°C, and the column chamber to 150°C. Four Agilent "Mixed A" 30 cm 20 μm linear mixed-bed columns were used. The chromatographic solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen injection. The injection volume was 200 μL, and the flow rate was 1.0 mL / min.

[0074] The GPC column assembly was calibrated using 21 polystyrene standards with narrow molecular weight distributions, ranging from 580 to 8,400,000, arranged in a six-cocktail mixture, with individual molecular weights spaced at least tenfold apart. The standards were purchased from Agilent Technologies. For molecular weights equal to or greater than 1,000,000, 0.025 g of polystyrene standard was prepared in 50 mL of solvent; for molecular weights less than 1,000,000, 0.05 g of polystyrene standard was prepared in 50 mL of solvent. The polystyrene standards were dissolved at 80°C and gently stirred for 30 minutes. The peak molecular weights of the polystyrene standards were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)).

[0075] M 聚乙烯 =A×(M) 聚苯乙烯 ) B (Equation 1)

[0076] Where M is the molecular weight, A has a value of 0.4315, and B equals 1.0.

[0077] A fifth-order polynomial was used to fit the calibration point for the corresponding polyethylene equivalent. Small adjustments were made to A (from approximately 0.415 to 0.44) to correct for column resolution and band broadening effects, resulting in the NIST standard NBS1475 at 52,000 Mw.

[0078] Plate counting was performed on the GPC column assembly using eicosane (prepared in 50 mL of TCB at 0.04 g and dissolved under slow stirring for 20 min). Plate counts (Equation 2) and symmetry (Equation 3) were measured at 200 μL injections according to the following equations:

[0079]

[0080] Where RV is the retention volume in milliliters, peak width is in milliliters, peak maximum is the maximum height of the peak, and 1 / 2 height is 1 / 2 the height of the peak maximum.

[0081]

[0082] Where RV is the retention volume in milliliters, and peak width is in milliliters, peak maximum is the position of the peak value, one-tenth height is 1 / 10 of the height of the peak maximum, and a subsequent peak refers to the tail of a peak whose retention volume is later than the peak maximum, while a preceding peak refers to the front of a peak whose retention volume is earlier than the peak maximum. The plate count of the chromatographic system should be greater than 24,000, and the symmetry should be between 0.98 and 1.22.

[0083] Samples were prepared semi-automatically using PolymerChar "Instrument Control" software, with a target sample weight of 2 mg / ml. Solvent (containing 200 ppm BHT) was added to a pre-bubbled, diaphragm-capped vial using a PolymerChar high-temperature autosampler. The sample was then dissolved at 160°C for 2 hours with "low-speed" shaking.

[0084] Based on the GPC results, using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph, according to Equations 4-6, the PolymerChar GPCOne was used. TM The software calculates the Mn content based on the baseline-subtracted IR chromatograms at each equidistant data collection point (i) and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve at point (i) according to Equation 1. (GPC) Mw (GPC) and Mz (GPC) The calculation.

[0085]

[0086] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate (nominal flow rate) for each sample by comparing the RV of the corresponding decane peak in the sample (RV(FM sample)) with the retention volume of the decane peak within the narrow standard calibration (RV(FM calibration)). It was then assumed that any variation in the decane marker peak time was linearly related to the flow rate (effective flow rate) over the entire run. To facilitate the highest accuracy in RV measurement of the flow marker peak, a least-squares fitting procedure was used to fit the peak values ​​of the flow marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation was then used to solve for the true peak position. After calibration based on the flow marker peak, the effective flow rate (relative to the narrow standard calibration) was calculated according to Equation 7. (via PolymerCharGPCOne) TMThe software processes the flow marker peaks. Acceptable flow rate correction ensures that the effective flow rate is within + / - 2% of the nominal flow rate.

[0087] Flow rate (effective) = Flow rate (nominal) * (RV (FM calibration) / RV (FM sample)) (Equation 7)

[0088] A systematic approach for determining multi-detector offsets was developed in conjunction with Balke, Mourey et al. (Mourey and Balke, Chromatography Polym. Chapter 12, (1992)) (Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym. Chapter 13, (1992)), thereby utilizing PolymerChar GPCOne. TM The software optimizes the triple detector logarithmic (MW and IV) results from wide homopolymer polyethylene standards (Mw / Mn>3) with the narrow standard column calibration results from the narrow standard calibration curve.

[0089] Absolute molecular weight data were obtained using PolymerChar GPCOne. TM The software was obtained in a manner consistent with the following publications: Zimm (Zimm, BH, J. Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scattering from Polymer Solutions, Elsevier, Oxford, NY (1987)). The total injection concentration used for determining the molecular weight was obtained from the mass detector area and the mass detector constant, which was derived from one of suitable linear polyethylene homopolymers or polyethylene standards with known weight-average molecular weights. The calculated molecular weight (using GPCOne) TM The light scattering constant and refractive index concentration coefficient dn / dc of 0.104 are obtained using one or more polyethylene standards mentioned below. Typically, the mass detector response (IR5) and light scattering constant (using GPCOne) are also used. TM The determination should be performed using linear standards with a molecular weight exceeding approximately 50,000 g / mol. Other corresponding torques Mn (Abs) and Mz (Abs) The calculation is based on equation 8-9 as follows:

[0090]

[0091] IR5 GPC composition calibration

[0092] Using known short chain branch (SCB) frequencies (via 13 At least ten ethylene-based polymer standards (polyethylene homopolymers and ethylene / octene copolymers) measured by the C10 NMR method were calibrated using IR5 detector quantification, ranging from homopolymers (0 SCB / 1000 total C) to approximately 50 SCB / 1000 total C, where total C = carbon in the main chain + carbon in the branches. The weight-average molecular weight of each standard ranged from 36,000 g / mol to 126,000 g / mol, as determined by GPC-LALLS. The molecular weight distribution (Mw / Mn) of each standard ranged from 2.0 to 2.5, as determined by GPC. Exemplary polymer properties of the copolymer standards are shown in Table A.

[0093] Table A: "Copolymer" Standards

[0094]

[0095]

[0096] For each of the "polymer" standards, calculate the "IR5 area ratio (or "IR5" of the "area response of the IR5 methyl channel sensor minus the baseline" to the "area response of the IR5 measurement channel sensor minus the baseline"). 甲基通道面积 / IR5 测量通道面积 (Including standard filters and filter wheels supplied by PolymerChar: part number IR5_FWM01 as part of the GPC-IR instrument). The linear fit of the wt% comonomer frequency relative to the "IR5 area ratio" is constructed by the following Equation 10:

[0097] % comonomer by weight = A0 + [A1 × (IR5)] 甲基通道面积 / IR5 测量通道面积 (Equation 10)

[0098] If there is significant spectral overlap between the molecular weight determined at each chromatogram slice and the end-capped (methyl) comonomer, then the end-capped comonomer data by weight % can be corrected by decapping the end-capping mechanism.

[0099] DSC Method - Heat of Melting

[0100] Differential scanning calorimetry (DSC) is a common technique used to examine the melting and crystallization of semi-crystalline polymers. The general principles of DSC measurements and its applications in the study of semi-crystalline polymers are described in standard texts (e.g., EATuri, ed., Thermal Characterization of Polymeric Materials, Academic Press, 1981).

[0101] The heat of fusion was determined using a DSC from TA Instruments, Inc. The test was performed according to ASTM standard D3428. Calibration was performed by preparing 2-3 mg of indium and placing it in a T-zero aluminum pan. The pan was then loaded into the DSC instrument and the following heating program was cycled: 1) equilibrate the test chamber at 180°C, 2) hold the temperature at 180°C for 1 minute, 3) gradually decrease the temperature to 130°C at a rate of 10°C / min, 4) hold the temperature at 130°C for 3 minutes, and 5) gradually increase the temperature back to 180°C at a rate of 10°C / min. Once completed, the final heating profile from step 5 was analyzed to determine the melting temperature of the indium sample. If the melting temperature was within a 0.5°C tolerance of 156.6°C, the DSC was considered to be operating compliantly.

[0102] For sample testing, the polymer sample was first pressed into a film at 190°C. Approximately 4 to 5 mg of sample was weighed and placed in a DSC pan. The lid was screwed on tightly to ensure a sealed atmosphere. The sample pan was placed in the DSC cell and equilibrated at 180°C. The sample was held at this temperature for 5 minutes. The sample was then cooled to -90°C at a rate of 10°C / min and held isothermally at this temperature for 5 minutes. Subsequently, the sample was heated to 150°C at a rate of 10°C / min (to ensure complete melting); this step was designated as the second heating curve. The peak melt temperature, onset and peak crystallization temperatures, and heat of fusion (also known as melting heat) ΔHf of the resulting enthalpy curve were analyzed. The heat of fusion, in Joules per gram, was measured from the second heating curve by linear integration of the endothermic melting from the baseline.

[0103] Tear resistance in the transverse direction (CD)

[0104] According to ASTM D1922-09, the tear resistance of an exemplary multilayer film is measured in the transverse (CD) direction. The ASTM D1922-09 standard determines the average force that propagates the tear transversely through a specified length of plastic film after the tear has begun.

[0105] Example

[0106] The following materials are included in the exemplary multilayer films discussed below.

[0107] Synthesis of ethylene-propylene copolymer – polymer 1

[0108] The resin (referred to herein as "polymer 1") was prepared according to the following method and table.

[0109] All feedstocks (monomers and comonomers) and process solvents (narrow-boiling-range, high-purity isoparaffin solvent, Isopar-E) were purified using molecular sieves before being introduced into the reaction environment. Hydrogen was supplied pressurized at a high purity level without further purification. The monomer feed stream to the reactor was pressurized to above the reaction pressure via a mechanical compressor. The solvent and comonomer feeds (if present) were pressurized to above the reaction pressure via pumps. Individual catalyst components were manually diluted in batches with purified solvent and pressurized to above the reaction pressure. All reaction feed streams were measured by mass flow meters and independently controlled by a computer-automated valve control system. The reactor configuration was a single-reactor operation as specified in Table B.

[0110] The reactor is a continuous solution polymerization reactor consisting of a liquid-filled, non-adiabatic isothermal circulating loop reactor or a deheated continuous stirred tank reactor (CSTR). All fresh solvent, monomer, comonomer (if present), hydrogen, and catalyst components can be independently controlled. The temperature of the total fresh feed stream (solvent, monomer, comonomer [if present], and hydrogen) entering the reactor is typically controlled between 15°C and 50°C to maintain a single solution phase by passing the feed stream through a heat exchanger. In the case of a CSTR, the entire fresh feed to the polymerization reactor is injected into the bottom of the reactor. In the case of a circulating loop reactor, the total fresh feed to the polymerization reactor is injected into the reactor at two locations, where the reactor volume between each injection location is approximately equal. The fresh feed is controlled by receiving half the total fresh feed mass flow rate at each injector. Catalyst components are injected into the polymerization reactor through one or more injection nozzles to introduce these components into the center of the reactor flow. The catalyst component feed is computer-controlled to maintain the reactor monomer conversion at a specified value. The co-catalyst component is fed based on a calculated specified molar ratio to the main catalyst component. Immediately following the feed injection point at each reactor, the feed stream is mixed with the contents of the circulating polymerization reactor using a static mixing element. In the case of a CSTR, the heat of reaction is partially removed by a cooled jacket. The temperature on the coolant side is responsible for maintaining the isothermal reaction environment at the specified temperature. In the case of a circulating loop reactor, the contents are continuously circulated through a heat exchanger, which is responsible for removing most of the heat of reaction, and the temperature on the coolant side is responsible for maintaining the isothermal reaction environment at the specified temperature. Circulation around the reactor loop is provided by a pump.

[0111] The reactor effluent enters a zone where it is deactivated by adding a suitable reagent (water) and reacting with it. At the same reactor outlet location, other additives are added to stabilize the polymer (typical antioxidants suitable for extrusion and manufacturing processes, such as octadecyl 3,5-di-tert-butyl-4-hydroxycinnamate, tetra(methylene(3,5-di-tert-butyl-4-hydroxycinnamate))methane and tris(2,4-di-tert-butyl-phenyl)phosphite, and acid scavengers, such as calcium stearate, if needed).

[0112] After catalyst deactivation and the addition of additives, the reactor effluent enters a volatilization section where polymers are removed from the non-polymer stream. The separated polymer melt is granulated and collected. The non-polymer stream is separated by various devices through which most of the ethylene removed from the system is separated. Depending on the reactor setup, little or no solvent and unreacted comonomers (if present) are recycled back to the reactor after passing through a purification system. Small amounts of solvent and comonomers (if present) are removed from the process.

[0113] The reactor feed data stream, corresponding to the values ​​in Table B, used to produce the development resin (polymer 1), is illustrated in Figure 1. The data is given for a reactor setup without a solvent recycling system, and the reaction system can be viewed as a direct-flow diagram.

[0114] Table A - Catalyst Components

[0115]

[0116] Table B - Reactor Information

[0117]

[0118] Synthesis of ethylene-propylene copolymer – polymer 2

[0119] The resin (referred to herein as "polymer 2") was prepared according to the following method and table.

[0120] All feedstocks (monomers and comonomers) and process solvents (narrow-boiling-range, high-purity isoparaffin solvent, Isopar-E) were purified using molecular sieves before being introduced into the reaction environment. Hydrogen was supplied pressurized at a high purity level without further purification. The monomer feed stream to the reactor was pressurized to above the reaction pressure via a mechanical compressor. The solvent and comonomer feeds (if present) were pressurized to above the reaction pressure via pumps. Individual catalyst components were manually diluted in batches with purified solvent and pressurized to above the reaction pressure. All reaction feed streams were measured by mass flow meters and independently controlled by a computer-automated valve control system. The reactor configuration was a single-reactor operation as specified in Table D.

[0121] The reactor is a continuous solution polymerization reactor consisting of a liquid-filled, non-adiabatic isothermal circulating loop reactor or a deheated continuous stirred tank reactor (CSTR). All fresh solvent, monomer, comonomer (if present), hydrogen, and catalyst components can be independently controlled. The temperature of the total fresh feed stream (solvent, monomer, comonomer [if present], and hydrogen) entering the reactor is typically controlled between 15°C and 50°C to maintain a single solution phase by passing the feed stream through a heat exchanger. In the case of a CSTR, the entire fresh feed to the polymerization reactor is injected into the bottom of the reactor. In the case of a circulating loop reactor, the total fresh feed to the polymerization reactor is injected into the reactor at two locations, where the reactor volume between each injection location is approximately equal. The fresh feed is controlled by receiving half the total fresh feed mass flow rate at each injector. Catalyst components are injected into the polymerization reactor through one or more injection nozzles to introduce these components into the center of the reactor flow. The catalyst component feed is computer-controlled to maintain the reactor monomer conversion at a specified value. The co-catalyst component is fed based on a calculated specified molar ratio to the main catalyst component. Immediately following the feed injection point at each reactor, the feed stream is mixed with the contents of the circulating polymerization reactor using a static mixing element. In the case of a CSTR, the heat of reaction is partially removed by a cooled jacket. The temperature on the coolant side is responsible for maintaining the isothermal reaction environment at the specified temperature. In the case of a circulating loop reactor, the contents are continuously circulated through a heat exchanger, which is responsible for removing most of the heat of reaction, and the temperature on the coolant side is responsible for maintaining the isothermal reaction environment at the specified temperature. Circulation around the reactor loop is provided by a pump.

[0122] The reactor effluent enters a zone where it is deactivated by adding a suitable reagent (water) and reacting with it. At the same reactor outlet location, other additives are added to stabilize the polymer (typical antioxidants suitable for extrusion and manufacturing processes, such as octadecyl 3,5-di-tert-butyl-4-hydroxycinnamate, tetra(methylene(3,5-di-tert-butyl-4-hydroxycinnamate))methane and tris(2,4-di-tert-butyl-phenyl)phosphite, and acid scavengers, such as calcium stearate, if needed).

[0123] After catalyst deactivation and the addition of additives, the reactor effluent enters a volatilization section where polymers are removed from the non-polymer stream. The separated polymer melt is granulated and collected. The non-polymer stream is separated by various devices through which most of the ethylene removed from the system is separated. Depending on the reactor setup, little or no solvent and unreacted comonomers (if present) are recycled back to the reactor after passing through a purification system. Small amounts of solvent and comonomers (if present) are removed from the process.

[0124] The reactor feed data stream corresponding to the values ​​in Table D for the production of the development resin (polymer 2) is illustrated in Figure 1. The data is given for a reactor setup without a solvent recycling system, and the reaction system can be viewed as a direct-flow diagram.

[0125] Table C - Catalyst Components

[0126]

[0127] Table D - Reactor Information

[0128]

[0129]

[0130] Material

[0131] DOWLEX TM GM 8090 is a linear low-density polyethylene (LLDPE) with a density of 0.916 g / cc and a melt index (I2) of 1.0 g / 10 min, commercially available from The Dow Chemical Company, Midland, MI. (DOWLEX) TM GM 8090 is an ethylene-based polymer, as the term is defined herein.

[0132] DOW TM LDPE 310E is a low-density polyethylene resin, a type of low-density polyethylene (LDPE) with a density of 0.923 g / cc and a melt index (I2) of 0.75 g / 10 min, commercially available from Dow Chemical Company, Midland, Michigan. TM LDPE 310E is an ethylene-based polymer, as the term is defined herein.

[0133] XZ 89507.00 is an ethylene-based copolymer having a density of 0.902 g / cc and a melt index of 0.85 g / 10 min, and is commercially available from Dow Chemical Company, Midland, Michigan. XZ 89507.00 is an ethylene-based polymer, as the term is defined herein.

[0134] XUS 39003.00 is an ethylene-propylene copolymer commercially available from Dow Chemical Company, Midland, Michigan. XUS 39003.00 contains 27.1 wt% propylene comonomer and 72.9 wt% ethylene monomer, and has a density of 0.867 g / cm³. 3The melt index (I2) is 0.90 g / 10 min, I 10 The I2 ratio is 10.82, the heat of fusion is 50.24 J / g, and the Mw / Mn ratio is 3.98. XUS 39003.00 is an ethylene-based polymer, as defined herein.

[0135] VERSIFY TM 2300 elastomer, a propylene-ethylene elastomer with a density of 0.867 g / cc, commercially available from Dow Chemical Company, Midland, Michigan. VERSIFY TM 2300 elastomer is not an ethylene-based polymer, as the term is defined herein.

[0136] AFFINITY TM EG 8100G is an ethylene-octene polyethylene plastide with a density of 0.870 g / cc and a melt index (I2) of 1.0 g / 10 min. AFFINITY TM EG 8100G is commercially available from Dow Chemical Company in Midland, Michigan. AFFINITY TM EG 8100G is an ethylene-based polymer, as the term is defined herein.

[0137] AFFINITY TM PL1840 is an ethylene-α-olefin with a density of 0.909 g / cc and a melt index (I2) of 1.0 g / 10 min. AFFINITY TM PL1840 is commercially available from Dow Chemical Company in Midland, Michigan. AFFINITY TM PL1840 is an ethylene-based polymer, as the term is defined herein.

[0138] Polymer 1 is an ethylene-propylene copolymer having 70 wt% ethylene monomer, 30 wt% propylene comonomer, a density of 0.870 g / cc, a melt index (I2) of 1.0 g / 10 min, a heat of fusion of 47.09 J / g, a Mw / Mn ratio of 2.2, and an I2 ratio of 9.4. 10 / I2. As shown in Figure 2, polymer 1 exhibits a single peak in the modified comonomer composition distribution (ICCD) elution curve within the temperature range of 40°C to 100°C. Polymer 1 is an ethylene-based polymer, as the term is defined herein.

[0139] Polymer 2 is an ethylene-propylene copolymer with 92 wt% ethylene monomer, 8 wt% propylene comonomer, a density of 0.910 g / cc, a melt index (I2) of 1.0 g / 10 min, a heat of fusion of 118.85 J / g, a Mw / Mn ratio of 2.6, and an I2 ratio of 13. 10 / I2. As shown in Figure 2, polymer 2 exhibits a single peak in the modified comonomer composition distribution (ICCD) elution curve within the temperature range of 40°C to 100°C. Polymer 2 is an ethylene-based polymer, as the term is defined herein.

[0140] Three-layer and five-layer multilayer films were formed using the above materials. The multilayer films were produced on a Collin co-extrusion blown film production line with a blow-up ratio (BUR) of 2.5 and a total thickness of 100 μm. The Collin co-extrusion blown film production line was manufactured by Collin Lab&Pilot Solutions GmbH. The Collin co-extrusion blown film production line has a die diameter of 100 mm; a die gap of 2.2 mm; a film width of 398 mm; an output of 16 kg / hr-17 kg / hr; and a melt temperature of 200°C-230°C. The Collin co-extrusion blown film production line is configured as shown in Table 1 below to prepare the multilayer films described in Table 2. The film thickness is 100 μm.

[0141] Table 1 - Collin Co-extrusion Blow Molding Production Line Configuration

[0142]

[0143]

[0144] Table 2 - Structure of the Embodiment

[0145]

[0146]

[0147] *Comparison membrane 5 has an A / B / C / D / E structure because layers B and D (equivalent to the two B layers of the A / B / C / B / A structure) are different polymer compositions.

[0148] Membranes 1, 2, 3, and 3a of the present invention, and comparative membranes 2, 3, 4, and 5, are five-layer membranes. Membranes 4 and 5 of the present invention, and comparative membranes 1, 6, and 7, are three-layer membranes because the polymers extruded from structures B and C are identical. Tear resistance in the longitudinal (MD) and transverse (CD) directions was measured for each of the comparative membranes and the membranes of the present invention. The results are reported in Table 3 below. The results show that the membranes of the present invention exhibit comparable or improved CD and MD tear resistance to the comparative membranes. The membranes of the present invention comprise all ethylene-based polymers desirable for polyethylene recycling streams and include less than 40% by weight of an ethylene-propylene copolymer in the core.

[0149] Table 3 - Tear Resistance of MD and CD in Examples

[0150] Membrane 1 of the present invention 100 2934 2391 Membrane 2 of the present invention 100 3192 2813 Membrane 3 of the present invention 100 2271 1825 Membrane 3a of the present invention 100 3293 2997 Comparison Membrane 2 100 2622 1880 Comparison Membrane 3 100 1602 1524 Comparison membrane 4 100 1669 1299 Comparison membrane 5 100 1517 1155 Membrane 4 of the present invention 100 2037 1649 Membrane 5 of the present invention 100 1931 1536 Comparison Membrane 1 100 1477 1322 Comparison Membrane 6 100 1261 962 Comparison Membrane 7 100 1480 1016

[0151] Unless expressly excluded or otherwise limited, every document cited herein (if any), including any cross-referenced or related patent or application and any patent application or patent claiming priority or benefit thereof, is incorporated herein by reference in its entirety. No reference to any document acknowledges it as prior art to any invention disclosed or claimed herein, or as teaching, indicating, or disclosing any such invention, alone or in combination with any other referenced document. Furthermore, in the event of any conflict between the meaning or definition of any term in this document and the meaning or definition of the same term in any document incorporated by reference, the meaning or definition given to the term in this document shall prevail.

[0152] While specific embodiments of the invention have been described and illustrated, it will be apparent to those skilled in the art that many other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications falling within the scope of the invention be covered in the appended claims.

Claims

1. A multilayer film comprising: A first outer layer, a second outer layer, and a core, wherein the core comprises one or more core layers; The core is positioned between the first outer layer and the second outer layer; the core comprises more than 90% by weight of an ethylene-based polymer based on the total polymer weight of the core; and the first core layer comprises an ethylene-propylene copolymer comprising 60% to 95% by weight of ethylene monomer and 5% to 40% by weight of propylene comonomer, the ethylene-propylene copolymer having a density of 0.865 g / cc to 0.920 g / cc and a melt index (I2) of at least 0.5 g / 10 min, and the core comprises less than 40% by weight of the ethylene-propylene copolymer based on the total polymer weight of the core.

2. The multilayer film according to any of the preceding claims, wherein the molecular weight distribution Mw / Mn of the ethylene-propylene copolymer is from 1.5 to 5.

0.

3. The multilayer film according to any of the preceding claims, wherein the ethylene-propylene copolymer has a single peak in the modified comonomer composition distribution (ICCD) elution profile within a temperature range of 40°C to 100°C.

4. The multilayer film according to any one of the preceding claims, wherein the ethylene-propylene copolymer has a melt flow ratio of 5 to 14. 10 / I2.

5. The multilayer film according to any of the preceding claims, wherein the ethylene-propylene copolymer is formed in the presence of a catalyst composition comprising a unit point metallocene catalyst.

6. The multilayer film according to any of the preceding claims, wherein the first core layer comprises 60% to 100% by weight of the ethylene-propylene copolymer.

7. The multilayer film according to any of the preceding claims, wherein the first outer layer and the second outer layer comprise polyethylene with a density of less than 0.930 g / cc and a melt index (I2) of less than 7 g / 10 min.

8. The multilayer film according to any of the preceding claims, wherein the core comprises 100% by weight of an ethylene-based polymer.

9. The multilayer film according to any of the preceding claims, wherein the thickness of the first core layer is less than 30% of the total thickness of the multilayer film.

10. The multilayer film according to any of the preceding claims, wherein the multilayer film comprises at least five layers, including a first outer layer, a second outer layer, a first core layer, a second core layer and a third core layer, wherein the first core layer is positioned between the second core layer and the third core layer, and the second core layer and the third core layer each comprise polyethylene with a density of less than 0.930 g / cc and a melt index (I2) of less than 7 g / 10 min.

11. The multilayer film according to any of the preceding claims, wherein the core comprises less than 30% by weight of an ethylene-propylene copolymer based on the total weight of the core.

12. The multilayer film according to any of the preceding claims, wherein, based on the total weight of the multilayer film, the multilayer film comprises at least 95% by weight of an ethylene-based polymer.

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