Multilayer film containing polyethylene and barrier layer and method for producing the same

Abstract

Disclosed are multilayer film embodiments including a first layer comprising polyethylene, a second layer comprising a first medium-density polyethylene, a barrier layer, a third layer comprising a second medium-density polyethylene, and a fourth layer comprising polyethylene. The second layer can be disposed between the first layer and the barrier layer. The barrier layer can be disposed between the second layer and the third layer.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the priority of European Patent Application No. 19382903.3 filed on October 15, 2019, which claims the priority of U.S. Provisional Patent Application No. 62 / 883,467 filed on August 6, 2019 and U.S. Provisional Patent Application No. 62 / 883,497 filed on August 6, 2019, and the entire disclosures of which are incorporated herein by reference, respectively.

[0002] The embodiments described herein generally relate to multilayer films, and more specifically to multilayer films including a polyethylene layer and a barrier layer.

Background Art

[0003] Multilayer films are used in packaging applications including flexible package applications. In flexible packages, the use of a barrier layer is often required, which reduces the diffusion of aroma, water, and gas into and out of the flexible package.

Summary of the Invention

[0004] In conventional multilayer films, desirable film properties can be presented by including a polyamide - containing barrier layer. However, the incorporation of a polyamide - containing barrier layer increases the complexity of the process, increases the complexity of the film structure, produces a non - recyclable multilayer film, and can increase the material cost compared to using other materials. Therefore, improving sustainability and mechanical properties are goals of manufacturers of multilayer films containing polyethylene. However, polyethylene - containing films with reduced or no polyamide typically have improved Elastic modulus , but insufficient dart strength, or improved dart strength, but insufficient Elastic modulus Thereby, while enabling improved recyclability, dart strength and Elastic modulusIt is often difficult to obtain a polymer film that is balanced with it.

[0005] Therefore, it is beneficial for single-layer and multilayer polymer films that may include inflation or cast films to exhibit toughness while enabling reduction of material costs and / or improvement of recyclability. In addition to barrier properties that meet customer and industry requirements, there is a need for multilayer films that exhibit good physical properties such as high dirt and high Elastic modulus and the like.

[0006] Embodiments of the present disclosure meet those needs by providing a multilayer film that provides a balance of improved stiffness and improved abuse properties (e.g., dirt, puncture energy, tear). Such a multilayer film may include a medium-density polyethylene (MDPE) composition that exhibits an improved balance of toughness and creep resistance in one or more layers. In one or more embodiments, the MDPE composition in one or more layers of the film of the present disclosure may include a first polyethylene fraction and a second polyethylene fraction, each fraction having different elution profile peaks as described herein. The use of such MDPE compositions can enable a suitable balance of dirt strength versus Elastic modulus without polyamide while having good barrier properties. Further, a multilayer film including a barrier layer and such an MDPE composition can be improved as compared to a conventional multilayer film that includes the barrier layer but does not include the MDPE composition.

[0007] According to one or more embodiments, a multilayer film is provided. Embodiments of the multilayer film can include a first layer containing polyethylene, a second layer containing a first medium density polyethylene, a barrier layer, a third layer containing a second medium density polyethylene, and a fourth layer containing polyethylene. The second layer can be disposed between the first layer and the barrier layer. The barrier layer can be disposed between the second layer and the third layer. The third layer can be disposed between the barrier layer and the fourth layer. The first medium density polyethylene and the second medium density polyethylene each can include (a) a first polyethylene fraction having a single peak in a temperature range of 45°C to 87°C in an elution profile by an improved compositional distribution of comonomer (iCCD) analysis method, wherein the first polyethylene fraction area is the area within the elution profile under the single peak of the first polyethylene fraction at 45°C to 87°C, and (b) a second polyethylene fraction having a single peak in a temperature range of 95°C to 120°C in an elution profile by the iCCD analysis method, wherein the second polyethylene fraction area is the area within the elution profile under the single peak of the second polyethylene fraction at 95°C to 120°C. The first medium density polyethylene and the second medium density polyethylene each can have a density of 0.924 g / cm 3 ~0.936 g / cm 3 and a melt index (I2) of 0.25 g / 10 min to 2.0 g / 10 min. The first polyethylene fraction area can constitute at least 40% of the total area of the elution profile. The ratio of the first polyethylene fraction area to the second polyethylene fraction area can be 0.75 to 2.5. The width of the single peak of the second polyethylene fraction at 50 percent of the peak height can be less than 5.0°C.

[0008] According to one or more embodiments, a multilayer film is provided. Embodiments of the multilayer film can include a first outer layer comprising polyethylene, a first subskin layer comprising a first medium density polyethylene, a second subskin layer comprising a second medium density polyethylene, a first tie layer, a barrier layer, a second tie layer, a third subskin layer comprising a third medium density polyethylene, and a fourth subskin layer comprising a fourth medium density polyethylene. The first subskin layer can be disposed between the first outer layer and the second subskin layer. The second subskin layer can be disposed between the first subskin layer and the first tie layer. The first tie layer can be disposed between the second subskin layer and the barrier layer. The barrier layer can be disposed between the first layer and the second layer. The second tie layer can be disposed between the barrier layer and the third subskin layer. The third subskin layer can be disposed between the second tie layer and the fourth subskin layer. The fourth subskin layer can be disposed between the third subskin layer and the second outer layer. The first medium density polyethylene, the second medium density polyethylene, the third medium density polyethylene, and the fourth medium density polyethylene each can include (a) a first polyethylene fraction having a single peak in a temperature range of 45°C to 87°C in an elution profile by an improved compositional distribution (iCCD) analysis method, wherein the first polyethylene fraction area is the area within the elution profile under the single peak of the first polyethylene fraction at 45°C to 87°C, and (b) a second polyethylene fraction having a single peak in a temperature range of 95°C to 120°C in an elution profile by the iCCD analysis method, wherein the second polyethylene fraction area is the area within the elution profile under the single peak of the second polyethylene fraction at 95°C to 120°C. The first medium density polyethylene, the second medium density polyethylene, the third medium density polyethylene, and the fourth medium density polyethylene each can have a density of 0.924 g / cm 3 to 0.936 g / cm 3It may have a density of and a melt index (I2) of 0.25 g / 10 min to 2.0 g / 10 min, the area of the first polyethylene fraction may constitute at least 40% of the total area of the elution profile, the ratio of the area of the first polyethylene fraction to the area of the second polyethylene fraction may be 0.75 to 2.5, and the width of the single peak of the second polyethylene fraction at 50 percent of the peak height may be less than 5.0 °C.

[0009] These and the embodiments are described in more detail in the following mode for carrying out the invention in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0010] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, in which like structures are denoted by like reference numerals.

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0012] Here, specific embodiments of the present application will be described. These embodiments are provided so that the present disclosure is detailed and complete and conveys the scope of the claimed subject matter to those skilled in the art.

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

[0014] "Polyethylene" or "ethylene polymer" shall mean a polymer containing units derived from more than 50 mol% ethylene monomer. This includes ethylene homopolymers or copolymers (meaning that the units are derived from two or more comonomers). Common forms of ethylene polymers known in the art include, but are not limited to, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), single site catalyst linear low density polyethylene (m-LLDPE) which includes both linear and substantially linear low density resins, medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0015] As used herein, the term "composition" refers to a mixture of materials including the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0016] As used herein, the terms "polypropylene" or "propylene-based polymer" refer to polymers that, in polymerized form, consist of units derived from more than 50 mole% propylene monomer. This includes propylene homopolymers, random copolymer polypropylenes, impact copolymer polypropylenes, propylene / α-olefin copolymers, and propylene / α-olefin copolymers.

[0017] 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 a pressure exceeding 14,500 psi (100 MPa) by using a free radical initiator such as peroxide (see, for example, U.S. Patent No. 4,599,392, which is hereby incorporated by reference in its entirety). LDPE resins typically have a density in the range of 0.916 g / cm 3 ~0.940 g / cm 3 within the range.

[0018] The term "LLDPE" includes resins made using Ziegler-Natta catalyst systems, as well as resins made using single-site catalysts including, but not limited to, bis-metallocene catalysts (sometimes referred to as "m-LLDPE"), phosphinimines, and constrained geometry catalysts, and resins made using post-metallocene molecular catalysts including, but not limited to, bis(biphenylphenoxy) catalysts (also referred to as polyvalent aryloxy ether catalysts). LLDPE includes linear, substantially linear, or non-uniform ethylene copolymers or homopolymers. LLDPE contains fewer long-chain branches than LDPE and includes substantially linear ethylene polymers further defined in U.S. Patent Nos. 5,272,236, 5,278,272, 5,582,923, and 5,733,155, each of which is incorporated herein by reference in its entirety; homogeneous branched linear ethylene polymer compositions such as those in U.S. Patent No. 3,645,992, incorporated herein by reference in its entirety; non-uniformly branched ethylene polymers prepared according to the processes disclosed in U.S. Patent No. 4,076,698, incorporated herein by reference in its entirety; and blends thereof (including those disclosed in U.S. Patent Nos. 3,914,342 and 5,854,045, each of which is incorporated herein by reference in its entirety). LLDPE resins can be made by gas phase, solution phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0019] The term "selected MDPE", as will be described in more detail hereinbelow, refers to polyethylene having a density of 0.924 g / cm 3 ~0.936 g / cm 3 of.

[0020] The term "HDPE" refers to polyethylene having a density of 0.935 g / cm 3 to a maximum of approximately 0.980 g / cm 3 prepared using single-site catalysts including, but not limited to, Ziegler-Natta catalysts, chromium catalysts, or substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts, and polyvalent aryloxy ether catalysts (typically referred to as bisphenol phenoxy).

[0021] The term "ULDPE" refers to polyethylene having a density of 0.855 g / cm 3 to 0.912 g / cm 3 prepared using single-site catalysts including, but not limited to, Ziegler-Natta catalysts, chromium catalysts, or substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts, and polyvalent aryloxy ether catalysts (typically referred to as bisphenol phenoxy). 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 g / cm 3 to 0.912 g / cm 3

[0022] Terms such as "blend", "polymer blend", etc. mean 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 structures as determined by transmission electron spectroscopy, light scattering, X-ray scattering, and any other method known in the art. A blend is not a laminate, but one or more layers of a laminate may contain a blend. Such blends can be formed as dry blends, in situ (e.g., in a reactor), as melt blends, or using other techniques known to those skilled in the art.​

[0023] The term "multilayer structure" or "multilayer film" means any structure having two or more layers. For example, a multilayer structure (e.g., a film) can have two, three, four, five, six, seven, or more layers. A multilayer structure can be described as having layers designated by letters. For example, a three-layer structure designated as A / B / C can have a core layer (B), as well as two outer layers (A) and (C).

[0024] 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 they are specifically disclosed. To avoid any doubt, all compositions claimed through the use of the term "comprising" may contain any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless there is a contradictory description. In contrast, the term "consisting essentially of" excludes any other components, steps, or procedures from the scope of any subsequent description, except for those that are essential for operation. The term "consisting of" excludes any components, steps, or procedures that are not specifically defined or listed.

[0025] Multilayer film Here, reference is made to embodiments of the multilayer film described herein.

[0026] The multilayer films of the present disclosure can include at least 5 layers, and further can include 7, 9, 11, 13 or more layers. The number of layers of the multilayer film can depend on a number of factors including, for example, the composition of each layer of the multilayer film, the desired properties of the multilayer film, the desired end use of the multilayer film, the manufacturing process of the multilayer film, and the like. As described in more detail herein, embodiments of the multilayer film can include a barrier layer described later in the present disclosure, one or more outer layers described later in the present disclosure, and one or more subskin layers described later in the present disclosure. The one or more subskin layers can include a selected medium density polyethylene (MDPE) detailed below herein. The selected MDPE in the one or more subskin layers can be the same or different in composition.

[0027] The multilayer film can be a 5-layer film designated as A / B / C / D / E, the first layer can be designated as (A), the second layer can be designated as (B), the third layer can be designated as (C), the fourth layer can be designated as (D), and the fifth layer can be designated as (E). In embodiments, layer (C) may be referred to as an "intermediate layer" or a "core layer". In embodiments, layer (C) can be a barrier layer as described later in the present disclosure. In embodiments, one or both of layer (A) and layer (E) can be outer layers as described later in the present disclosure. In embodiments, one or both of layer (B) and layer (D) can be subskin layers as described later in the present disclosure.

[0028] As described above, in an embodiment, the third layer (C) can be the core layer of a five-layer film that can be disposed between the second layer (B) and the fourth layer (D). In an embodiment, the second layer (B) can be disposed between the first layer (A) and the third layer (C). In an embodiment, the fourth layer (D) can be disposed between the third layer (C) and the fifth layer (E). In an embodiment, one or both of the first layer (A) and the fifth layer (E) can be the outermost layer of the multilayer film. As used herein, the outermost layer of the multilayer film can be understood to mean that there may be no other layer deposited on the outermost layer such that the outermost layer is in direct contact with the surrounding air. In an embodiment, one or both of the first layer (A) and the fifth layer (E) may not be the outermost layer of the multilayer film.

[0029] As used herein, "direct contact" means that there may be no other layer disposed between two layers that are in direct contact with each other. In an embodiment, the first layer (A), the third layer (C), or both may be in direct contact with the second layer (B). In an embodiment, the second layer (B), the fourth layer (D), or both may be in direct contact with the third layer (C). In an embodiment, the third layer (C), the fifth layer (E), or both may be in direct contact with the fourth layer (D). In embodiments of a multilayer film comprising six or more layers, there may be additional layers disposed between layer (C) and one or more of layer (A) and layer (E).

[0030] In another embodiment, the multilayer film can be a 7-layer film designated as A / B / C / D / E / F / G, where the first layer can be designated as (A), the second layer can be designated as (B), the third layer can be designated as (C), the fourth layer can be designated as (D), the fifth layer can be designated as (E), the sixth layer can be designated as (F), and the seventh layer can be designated as (G). In an embodiment of the 7-layer film, layer (D) may be referred to as an intermediate layer or a core layer. In an embodiment, layer (D) can be a barrier layer, as will be described later in the present disclosure. Layer (D) can contain a polar material, as will be described later in the present disclosure. Layers (C) and (E) can be tie layers, as will be described later in the present disclosure. In an embodiment of the 7-layer film, one or both of layer (A) and layer (G) can be outer layers, as will be described later in the present disclosure. One or both of layers (B) and (F) can be subskin layers, as will be described later in the present disclosure.

[0031] As described above, in an embodiment of the 7-layer film, the fourth layer (D) can be an intermediate layer or a core layer of the 7-layer film that can be disposed between the third layer (C) and the fifth layer (E). In an embodiment, the second layer (B) can be disposed between the first layer (A) and the third layer (C). In an embodiment, the sixth layer (F) can be disposed between the fifth layer (E) and the seventh layer. In an embodiment, the first layer (A) and the seventh layer (G) can be the outermost layers of the 7-layer film. In an embodiment, one or both of the first layer (A) and the seventh layer (G) may not be the outermost layer of the multilayer film. In an embodiment of a multilayer film including eight or more layers, there can be additional layers disposed between layer (D) and one or more of layer (A) and layer (E).

[0032] In an embodiment of the 7-layer multilayer film, the first layer (A), the third layer (C), or both may be in direct contact with the second layer (B). In an embodiment, the second layer (B), the fourth layer (D), or both may be in direct contact with the third layer (C). In an embodiment, the third layer (C), the fifth layer (E), or both may be in direct contact with the fourth layer (D). In an embodiment, the fourth layer (D), the sixth layer (F), or both may be in direct contact with the fifth layer (E). In an embodiment, the fifth layer (E), the seventh layer (G), or both may be in direct contact with the sixth layer (F). In an embodiment of a multilayer film comprising eight or more layers, there may be additional layers disposed between layer (D) and one or more of layer (A) and layer (E).

[0033] In another embodiment, the multilayer film can be a 9-layer film designated as A / B / C / D / E / F / G / H / I, the first layer can be designated as (A), the second layer can be designated as (B), the third layer can be designated as (C), the fourth layer can be designated as (D), the fifth layer can be designated as (E), the sixth layer can be designated as (F), the seventh layer can be designated as (G), the eighth layer can be designated as (H), and the ninth layer can be designated as (I). In an embodiment of the 9-layer film, layer (E) may be referred to as an intermediate layer or a core layer. In an embodiment, layer (E) can be a barrier layer as described later in the present disclosure. Layer (E) can contain a polar material as described later in the present disclosure. Layers (D) and (F) can be tie layers as described later in the present disclosure. In an embodiment of the 9-layer film, one or both of layer (A) and layer (I) can be outer layers as described later in the present disclosure. One or more of layers (B), (C), (G), and (H) can be subskin layers as described later in the present disclosure.

[0034] As described above, in an embodiment of a nine-layer film, the fifth layer (E) can be an intermediate or core layer of the nine-layer film that can be disposed between the fourth layer (D) and the sixth layer (F). In an embodiment, the second layer (B) can be disposed between the first layer (A) and the third layer (C). In an embodiment, the third layer (C) can be disposed between the second layer (B) and the fourth layer (D). In an embodiment, the sixth layer (F) can be disposed between the fifth layer (E) and the seventh layer (G). In an embodiment, the seventh layer (G) can be disposed between the sixth layer (F) and the eighth layer (H). In an embodiment, the eighth layer (H) can be disposed between the seventh layer (G) and the ninth layer (I). In an embodiment, the first layer (A) and the ninth layer (I) can be the outermost layers of the nine-layer film. In an embodiment, the first layer (A) and the ninth layer (I) may not be the outermost layers of the nine-layer film. In an embodiment of a multilayer film comprising ten or more layers, there can be additional layers disposed between layer (E) and one or more of layer (A) and layer (I).

[0035] In an embodiment of a nine-layer multilayer film, the first layer (A), the third layer (C), or both may be in direct contact with the second layer (B). In an embodiment, the second layer (B), the fourth layer (D), or both may be in direct contact with the third layer (C). In an embodiment, the third layer (C), the fifth layer (E), or both may be in direct contact with the fourth layer (D). In an embodiment, the fourth layer (D), the sixth layer (F), or both may be in direct contact with the fifth layer (E). In an embodiment, the fifth layer (E), the seventh layer (G), or both may be in direct contact with the sixth layer (F). In an embodiment, the sixth layer (F), the eighth layer (H), or both may be in direct contact with the seventh layer (G). In an embodiment, the seventh layer (G), the ninth layer (I), or both may be in direct contact with the eighth layer (H). In an embodiment of a multilayer film comprising ten or more layers, there can be additional layers disposed between the fourth layer (D) and one or more of the first layer (A) and the ninth layer (I).

[0036] Any of the foregoing layers may further include one or more additives known to those skilled in the art, such as plasticizers, stabilizers including viscosity stabilizers, hydrolysis stabilizers, primary and secondary antioxidants, ultraviolet absorbers, antistatic agents, dyes, pigments, or other colorants, inorganic fillers, flame retardants, lubricants, reinforcing agents such as glass fibers and flakes, synthetic (e.g., aramid) fibers or pulp, forming agents or foaming agents, processing aids, slip additives, anti-adhesive agents such as silica or talc, release agents, tackifying resins, or combinations of two or more thereof. Inorganic fillers such as calcium carbonate and the like can also be incorporated into one or more of the first layer, the second layer, the third layer, and combinations thereof. In some embodiments, the skin layer, the sub-skin layer, the tie layer, the barrier layer, and combinations may each contain up to 5 weight percent of such additional additives based on the total weight of each layer. All individual values and sub-ranges from 0 weight percent to 5 weight percent are included and disclosed herein. For example, the total amount of additives in the first layer, the second layer, or the third layer can be 0.5 weight percent to 5 weight percent, 0.5 weight percent to 4 weight percent, 0.5 weight percent to 3 weight percent, 0.5 weight percent to 2 weight percent, 0.5 weight percent to 1 weight percent, 1 weight percent to 5 weight percent, 1 weight percent to 4 weight percent, 1 weight percent to 3 weight percent, 1 weight percent to 2 weight percent, 2 weight percent to 5 weight percent, 2 weight percent to 4 weight percent, 2 weight percent to 3 weight percent, 3 weight percent to 5 weight percent, 3 weight percent to 4 weight percent, or 4 weight percent to 5 weight percent based on the total weight of each respective layer. Incorporation of the additives can be done by any known process, such as dry blending, extrusion of mixtures of various components, conventional masterbatch techniques, and the like.

[0037] The multilayer films of the present disclosure can have various thicknesses. The thickness of the multilayer film can depend on a number of factors including, for example, the number of layers of the multilayer film, the composition of the layers of the multilayer film, the desired properties of the multilayer film, the desired end use of the film, the manufacturing process of the multilayer film, and the like. In embodiments, the multilayer film can have a thickness of less than 205 micrometers (μm or microns). In embodiments, the multilayer film can have a thickness of 15 μm to 205 μm, 20 μm to 180 μm, 15 μm to 180 μm, 15 μm to 160 μm, 15 μm to 140 μm, 15 μm to 120 μm, 15 μm to 100 μm, 15 μm to 80 μm, 15 μm to 60 μm, 15 μm to 40 μm, 20 μm to 160 μm, 20 μm to 140 μm, 20 μm to 120 μm, 20 μm to 100 μm, 20 μm to 80 μm, 20 μm to 60 μm, or 20 μm to 40 μm.

[0038] The multilayer films of the present disclosure can have a bulk density that depends on a number of factors including, for example, the number of layers of the multilayer film, the composition of the layers of the multilayer film, the desired properties of the multilayer film, the desired end use of the film, the manufacturing process of the multilayer film, and the like. In embodiments, the multilayer film can have a bulk density of at least 0.925 grams per cubic centimeter (g / cm 3 ). In embodiments, the bulk density of the multilayer film is 0.925 g / cm 3 to 0.970 g / cm 3 , 0.925 g / cm 3 to 0.940 g / cm 3 , 0.925 g / cm 3 to 0.935 g / cm 3 , 0.925 g / cm 3 to 0.930 g / cm 3 , 0.930 g / cm 3 to 0.940 g / cm 3 , 0.930 g / cm 3 to 0.935 g / cm 3 , 0.935 g / cm 3 to 0.940 g / cm 3 , or 0.935 g / cm 3 to 0.950 g / cm 3 .

[0039] The multilayer film of the present disclosure may have an average 2% secant in the machine direction of at least 250 MPa when measured in accordance with ASTM D882. Elastic modulus In embodiments, the multilayer film may have an average 2% secant in the machine direction of at least 260 MPa, or 270 MPa when measured in accordance with ASTM D882. Elastic modulus The multilayer film of the present disclosure may have an average 2% secant in the cross direction of at least 215 MPa when measured in accordance with ASTM D882. Elastic modulus In embodiments, the multilayer film may have an average 2% secant in the cross direction of at least 245 MPa, 255 MPa, 260 MPa, or 265 MPa when measured in accordance with ASTM D882. Elastic modulus may have.

[0040] The multilayer film of the present disclosure may have a puncture force of at least 1 Newton per micrometer of film (N / μm) when measured in accordance with ASTM D 5748-95. In embodiments, the multilayer film of the present disclosure may have a puncture force of 1 N / μm to 1.5 N / μm, 1 N to 1.25 N / μm, or 1.25 N / μm to 1.5 N / μm when measured in accordance with ASTM D 5748-95.

[0041] The multilayer film of the present disclosure may have a puncture elongation of at least 55 millimeters (mm) when measured in accordance with ASTM D 5748-95. In embodiments, the multilayer film of the present disclosure may have a puncture elongation of 55 mm to 100 mm, 55 mm to 80 mm, 55 mm to 60 mm, 60 mm to 100 mm, 60 mm to 80 mm, or 80 mm to 100 mm when measured in accordance with ASTM D 5748-95.

[0042] The multilayer film of the present disclosure can have a dirt drop impact resistance of at least 3.5 grams per micrometer of film (g / μm) when measured according to ISO 7765-1. In embodiments, the multilayer film of the present disclosure can have a dirt drop impact resistance of 3.50 g / μm to 7.50 g / μm, 3.50 g / μm to 6.25 g / μm, 3.50 g / μm to 5.00 g / μm, 5.00 g / μm to 7.50 g / μm, 50 g / μm to 6.25 g / μm, or 6.25 g / μm to 7.50 g / μm when measured according to ISO 7765-1.

[0043] Barrier layer As discussed above, the multilayer film can include a barrier layer. As used herein, the term "barrier layer" refers to a layer that reduces the diffusion of vapor or gas into and out of the multilayer film. For example, the barrier layer can reduce the diffusion of aroma, water, or oxygen into and out of the multilayer film.

[0044] In embodiments, the barrier layer containing a polar material can be the core layer of the multilayer film. For example, in an embodiment of a 5-layer multilayer film, the barrier layer can be layer (C), in an embodiment of a 7-layer multilayer film, the barrier layer can be layer (D), and in an embodiment of a 9-layer multilayer film, the barrier layer can be layer (E).

[0045] As described above, the barrier layer can include a polar material. As used herein, the term "polar material" refers to a polymer formed from at least one monomer containing at least one heteroatom. Some examples of heteroatoms include O, N, P, and S. In various embodiments, the polar material has a melt index (I2) (2.16 kg, 190 °C) of 0.1 g / 10 min to 40 g / 10 min, 0.2 g / 10 min to 20 g / 10 min, or 0.5 g / 10 min to 10 g / 10 min. In various embodiments, the polar material has a density of 1.00 g / cm 3 ~1.30 g / cm 3 or 1.10 g / cm 3 ~1.20 g / cm 3 (1 cm3 has a density of =1 cc).

[0046] In various embodiments, the polar material can be selected from ethylene vinyl alcohol polymer (EVOH) (such as Eval H171B sold by Kuraray) or a combination of EVOH and polyamide (PA) (such as nylon 6, nylon 66, and nylon 6 / 66 sold by DuPont). In various embodiments, the barrier layer consists of ethylene vinyl alcohol (EVOH). In some embodiments, the barrier layer does not contain or is substantially free of polyamide. As used herein, "substantially free of" can mean that the barrier layer contains less than 1% by weight of polyamide, based on the total weight of the barrier layer. In embodiments, the barrier layer can contain less than 0.5% by weight or less than 0.1% by weight of polyamide.

[0047] It should be understood that in embodiments, the barrier layer containing the polar material can contain or consist of the polar material. In embodiments where the layer containing the polar material contains the polar material, the polar material can be blended with any polymer containing polyethylene such as LLDPE, LDPE, ULDPE, MDPE, selected MDPE, and HDPE.

[0048] In embodiments, the barrier layer of the multilayer film of the present disclosure can have various thicknesses. The thickness of the barrier layer can depend on many factors including, for example, the composition of the barrier layer, the desired overall recyclability and barrier properties of the multilayer film. In embodiments, the barrier layer can have a thickness of 0.1 μm to 20 μm, 0.1 μm to 15 μm, 0.1 μm to 10 μm, 0.1 μm to 5 μm, 0.1 μm to 1 μm, 0.1 μm to 0.5 μm, 0.5 μm to 20 μm, 0.5 μm to 15 μm, 0.5 μm to 10 μm, 0.5 μm to 5 μm, 0.5 μm to 1 μm, 1 μm to 20 μm, 1 μm to 15 μm, 1 μm to 10 μm, 1 μm to 5 μm, 5 μm to 20 μm, 5 μm to 15 μm, 5 μm to 10 μm, 10 μm to 20 μm, 10 μm to 15 μm, or 15 μm to 20 μm.

[0049] The thickness of the barrier layer of the multilayer film disclosed in this specification may constitute 1% to 10%, 1% to 8%, 1% to 6%, 1% to 4%, 1% to 2%, 2% to 10%, 2% to 8%, 2% to 6%, 2% to 4%, 4% to 10%, 4% to 8%, 4% to 6%, 6% to 10%, 6% to 8%, or 8% to 10% of the total thickness of the multilayer film.

[0050] Tie layer The multilayer film may include one or more tie layers. As used herein, the term "tie layer" refers to a layer that adheres two layers to each other. For example, a tie layer can bond a polar material to one or more layers that do not contain the polar material. For example, the tie layer can be disposed adjacent to a layer containing a polar material to adhere the layer containing the polar material to a layer containing polyethylene.

[0051] In an embodiment, the tie layer can be disposed adjacent to the barrier layer to adhere the barrier layer containing a polar material to one or more layers containing polyethylene, such as one or more sub-skin layers. For example, in an embodiment of a 7-layer multilayer film, layer (C) and layer (E) can be tie layers, and in an embodiment of a 9-layer multilayer film, layer (D) and layer (F) can be tie layers.

[0052] In an embodiment, based on the teachings herein, a variety of polymers known to those skilled in the art as useful for adhering a layer containing a polar material (such as EVOH or polyamide, etc.) to a layer containing polyethylene can be used for the tie layer.

[0053] In an embodiment, the tie layer may include an ethylene and acid copolymer. In one or more embodiments, the tie layer may include an anhydride grafted ethylene / alpha-olefin interpolymer. As used herein, the term "anhydride grafted ethylene / alpha-olefin interpolymer" refers to an ethylene / alpha-olefin interpolymer that includes at least one anhydride group linked by a covalent bond. The anhydride grafted ethylene / alpha-olefin interpolymer may be an ethylene-based polymer to which an anhydride grafting monomer is grafted. Suitable ethylene-based polymers for low melt viscosity maleic anhydride grafted polyolefins include, but are not limited to, polyethylene homopolymers and copolymers with alpha-olefins, copolymers of ethylene and vinyl acetate, and copolymers of ethylene and one or more alkyl (meth)acrylates. In certain embodiments, the anhydride grafted ethylene / alpha-olefin interpolymer may include maleic anhydride grafted linear low density polyethylene (LLDPE).

[0054] In one or more embodiments, the anhydride grafted ethylene / alpha-olefin interpolymer includes up to 10 wt%, up to 5 wt%, or 1-4 wt% maleic anhydride grafting monomer, based on the total weight of the anhydride grafted ethylene / alpha-olefin interpolymer. The weight percent of the ethylene-based polymer is complementary to the amount of maleic anhydride grafting monomer such that the sum of the weight percents of the ethylene-based polymer and the maleic anhydride grafting monomer is 100 wt%. Thus, the anhydride grafted ethylene / alpha-olefin interpolymer includes up to 90 wt%, up to 95 wt%, or 96-99 wt% ethylene-based polymer, based on the total weight of the maleic anhydride grafted polyolefin.

[0055] Examples of the anhydride grafting moiety include, but are not limited to, maleic anhydride, citraconic anhydride, 2-methylmaleic anhydride, 2-chloromaleic anhydride, 2,3-dimethylmaleic anhydride, bicyclo[2,2,1]-5-heptene-2,3-dicarboxylic anhydride and 4-methyl-4-cyclohexene-1,2-dicarboxylic anhydride, bicyclo(2.2.2)oct-5-ene-2,3-dicarboxylic anhydride, lo-octahydronaphthalene-2,3-dicarboxylic anhydride, 2-oxa-1,3-diketospiro(4.4)nona-7-ene, bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride, norborn-5-ene-2,3-dicarboxylic anhydride, nadic anhydride, methyl nadic anhydride, himic anhydride, methyl himic anhydride, and x-methyl-bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic anhydride. In one embodiment, the anhydride grafting moiety comprises maleic anhydride.

[0056] In a further embodiment, the maleic anhydride-grafted ethylene / alpha-olefin interpolymer has a density of less than 0.940 grams per cubic centimeter (g / cm 3 ) as measured according to ASTM method D792-91, or from 0.855 g / cm 3 to 0.940 g / cm 3 . As another density range, from 0.855 g / cm 3 to 0.900 g / cm 3 , from 0.855 g / cm 3 to 0.880 g / cm 3 , from 0.855 g / cm 3 to 0.860 g / cm 3 , from 0.860 g / cm 3 to 0.940 g / cm 3 , from 0.860 g / cm 3 to 0.910 g / cm 3 , from 0.860 g / cm 3 to 0.880 g / cm 3 , from 0.880 g / cm 3 to 0.910 g / cm 3, or 0.880 g / cm 3 ~0.900 g / cm 3 may be possible.

[0057] In one or more embodiments, the anhydride-grafted ethylene / alpha-olefin interpolymer may have a melt index (I2) of 300 grams per 10 minutes (g / 10 min) to 1500 g / 10 min, or 300 g / 10 min to 1000 g / 10 min, 500 g / 10 min to 800 g / 10 min, 500 g / 10 min to 600 g / 10 min, 600 g / 10 min to 1000 g / 10 min, 600 g / 10 min to 800 g / 10 min, or 800 g / 10 min to 1000 g / 10 min as determined according to ASTM method D1238 at 190 °C and 2.16 kg.

[0058] In one or more embodiments, the anhydride-grafted ethylene / alpha-olefin interpolymer may have a melt viscosity of less than 200,000 cP when measured at 177 °C according to the test methods described later in this disclosure. In an embodiment, the anhydride-grafted ethylene / alpha-olefin interpolymer may have a melt viscosity of 2,000 cP to 200,000 cP, 2,000 cP to 100,000 cP, 2,000 cP to 50,000 cP, 2,000 cP to 10,000 cP, 10,000 cP to 200,000 cP, 10,000 cP to 100,000 cP, 10,000 cP to 50,000 cP, 50,000 cP to 200,000 cP, 50,000 cP to 100,000 cP, or 100,000 cP to 200,000 cP when measured at 177 °C according to the test methods described later in this disclosure.

[0059] Various commercial embodiments are considered to be suitable. For example, a suitable anhydride-grafted ethylene / alpha-olefin interpolymer may be commercially available from The Dow Chemical Company under the trademark BYNEL® 41E710.

[0060] Varying amounts of ethylene and acid copolymers or anhydride-grafted ethylene / alpha-olefin interpolymers are believed to be suitable within the tie layers of the multilayer films described herein. In some embodiments, the tie layer may comprise 20 wt% or less of ethylene and acid copolymer or anhydride-grafted ethylene / alpha-olefin interpolymer, based on the total weight of the tie layer. In embodiments, the tie layer may comprise 5 wt% to 15 wt%, or 10 wt% to 15 wt% of ethylene and acid copolymer or anhydride-grafted ethylene / alpha-olefin interpolymer, based on the total weight of the tie layer. The remaining portion of the tie layer may be polyethylene such as LDPE, HDPE, MDPE, or a selected MDPE detailed below herein.

[0061] Without being bound by theory, it is believed that anhydride-grafted ethylene / alpha-olefin interpolymers can be placed adjacent to a layer containing a polar material to bond the layer containing the polar material to a nonpolar layer. In embodiments, the tie layer may be placed in direct contact with the layer containing the polar material. In embodiments, the tie layer may be placed between and in direct contact with the layer containing the polar material and a layer containing a selected MDPE detailed below herein.

[0062] In embodiments, each tie layer of the multilayer films of the present disclosure may have varying thicknesses. The thickness of each tie layer may depend on many factors including, for example, the adhesion characteristics of the tie layer. In embodiments, each tie layer may have a thickness of 0.1 μm to 20 μm. In embodiments, each tie layer may have a thickness of 0.1 μm to 15 μm, 0.1 μm to 10 μm, 0.1 μm to 5 μm, 0.1 μm to 1 μm, 0.1 μm to 0.5 μm, 0.5 μm to 20 μm, 0.5 μm to 15 μm, 0.5 μm to 10 μm, 0.5 μm to 5 μm, 0.5 μm to 1 μm, 1 μm to 20 μm, 1 μm to 15 μm, 1 μm to 10 μm, 1 μm to 5 μm, 5 μm to 20 μm, 5 μm to 15 μm, 5 μm to 10 μm, 10 μm to 20 μm, 10 μm to 15 μm, or 15 μm to 20 μm.

[0063] The thickness of each tie layer of the multilayer film disclosed in this specification can constitute 1% - 10%, 1% - 8%, 1% - 6%, 1% - 4%, 1% - 2%, 2% - 10%, 2% - 8%, 2% - 6%, 2% - 4%, 4% - 10%, 4% - 8%, 4% - 6%, 6% - 10%, 6% - 8%, or 8% - 10% of the total thickness of the multilayer film.

[0064] Outer layer As described above, the multilayer film of the present disclosure may include one or more outer layers. As used herein, the term "outer layer" refers to a layer outside the barrier layer and the sub-skin layer (for example, when the barrier layer is regarded as the innermost layer). The outer layer can impart properties to the multilayer film that assist with elongation, processability, etc. The outer layer may also be referred to as the skin layer.

[0065] The outer layer may include a sealant layer. The sealant layer is generally the outer layer of a film that can be used to adhere the film to another film, a rigid material (such as a tray), or itself. Those skilled in the art will recognize that, based on the teachings of this specification, various olefin-based polymers can be used as the sealant layer in various embodiments. In some embodiments, polyethylene can be the main component of each sealant layer in order to promote reusability. One non-limiting example of a resin that can be used as the sealant layer is, according to some embodiments, SEALUTION™ 220. Other resins that can be used to form the sealant layer include, but are not limited to, AFFINITY™, ELITE AT™, and ELITE™ commercially available from The Dow Chemical Company.

[0066] For example, in an embodiment of a 5-layer multilayer film, layer (A) and layer (E) can be the outer layers, in an embodiment of a 7-layer multilayer film, layer (A) and layer (G) can be the outer layers, and in an embodiment of a 9-layer multilayer film, layer (A) and layer (I) can be the outer layers.

[0067] In an embodiment, at least one outer layer may comprise a selected MDPE as detailed below in this specification. In an embodiment, an outer layer comprising the selected MDPE described herein may have a density of 0.870 g / cm 3 to 0.970 g / cm 3 and may be blended with polyethylene. In an embodiment, at least one outer layer may comprise more than 20% by weight of the selected MDPE described below in this specification, based on the total weight of each layer. In one or more embodiments, each outer layer may comprise more than 20% by weight of the selected MDPE described below in this specification, based on the total weight of each layer. In some embodiments, each outer layer may comprise from 0% to 100%, 30% to 100%, 50% to 80%, 50% to 60%, 60% to 100%, 60% to 80%, or 80% to 100% by weight of the selected MDPE described below in this specification, based on the total weight of each layer.

[0068] In some embodiments, an outer layer that does not comprise the selected MDPE described herein may comprise polyethylene having a density of 0.870 g / cm 3 to 0.970 g / cm 3 . In an embodiment, each outer layer may comprise LLDPE, HDPE, selected MDPE, MDPE, LDPE, and combinations thereof.

[0069] In one or more embodiments, each outer layer may comprise linear low density polyethylene (LLDPE) having a density of 0.905 g / cm 3 to 0.930 g / cm 3 when measured in accordance with ASTM D792. In another embodiment, the density of the linear low density polyethylene may be 0.905 g / cm 3 to 0.925 g / cm 3 , 0.905 g / cm 3 to 0.920 g / cm 3 , 0.905 g / cm 3 to 0.915 g / cm 3 , 0.905 g / cm 3 to 0.910 g / cm 3 , 0.910 g / cm 3~0.930 g / cm 3 、0.910 g / cm 3 ~0.925 g / cm 3 、0.910 g / cm 3 ~0.920 g / cm 3 、0.910 g / cm 3 ~0.915 g / cm 3 、0.915 g / cm 3 ~0.930 g / cm 3 、0.915 g / cm 3 ~0.925 g / cm 3 、0.915 g / cm 3 ~0.920 g / cm 3 、0.920 g / cm 3 ~0.930 g / cm 3 、0.920 g / cm 3 ~0.925 g / cm 3 、0.925 g / cm 3 ~0.930 g / cm 3 may be.

[0070] In one or more embodiments, each outer layer may include linear low density polyethylene (LLDPE) having a melt index (I2) of 0.2 grams per 10 minutes (g / 10 min) to 6.0 g / 10 min as measured according to ASTM D1238. It is also contemplated that the melt index (I2) of the linear low density polyethylene may be 0.2 g / 10 min to 5.5 g / 10 min, 0.2 g / 10 min to 5.0 g / 10 min, 0.2 g / 10 min to 4.5 g / 10 min, 0.5 g / 10 min to 4.0 g / 10 min, 0.5 g / 10 min to 3.5 g / 10 min, 0.5 g / 10 min to 3.0 g / 10 min, 1.0 g / 10 min to 2.0 g / 10 min, 1.0 g / 10 min to 1.5 g / 10 min, or 1.5 g / 10 min to 2.0 g / 10 min.

[0071] According to an embodiment, the linear low density polyethylene may have a molecular weight distribution in the range of 3.5 to 5.5, expressed as the ratio of weight average molecular weight to number average molecular weight (Mw / Mn). In additional embodiments, the linear low density polyethylene may have a molecular weight distribution in the range of 3.5 to 4.5 or 4.5 to 5.5.

[0072] According to one or more additional embodiments, the linear low density polyethylene may have a zero shear viscosity ratio of 1.2 to 3.0 when measured according to the test methods described herein. In embodiments, the linear low density polyethylene may have a zero shear viscosity ratio of 1.2 to 2.5, 1.2 to 2.0, 2.0 to 3.0, 2.0 to 2.5, or 2.5 to 3.0.

[0073] Regarding the production of linear low density polyethylene, various methodologies are contemplated. For example, the linear low density polyethylene resin can be made using resins made using single site catalysts including, but not limited to, Ziegler-Natta catalyst systems, bis-metallocene catalysts, and constrained geometry catalysts, resins made using post-metallocene molecular catalysts. The linear low density polyethylene resin can include linear, substantially linear, or non-uniform, polyethylene copolymers or homopolymers. The linear low density polyethylene resin contains fewer long chain branches than LDPE, substantially linear polyethylene as further defined in U.S. Patent No. 5,272,236, U.S. Patent No. 5,278,272, U.S. Patent No. 5,582,923, and U.S. Patent No. 5,733,155, homogeneous branched linear ethylene polymer compositions such as those in U.S. Patent No. 3,645,992, non-uniformly branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent No. 4,076,698, and blends thereof (such as those disclosed in U.S. Patent No. 3,914,342 or U.S. Patent No. 5,854,045). The linear low density polyethylene resin can be made by gas phase, solution phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0074] In one or more embodiments, each outer layer may comprise linear low density polyethylene in an amount greater than 50% by weight, based on the total weight of each layer. In some embodiments, the second layer, the third layer, or both may comprise 50% to 100%, 50% to 80%, 50% to 60%, 60% to 100%, 60% to 80%, or 80% to 100% LLDPE, based on the total weight of each layer.

[0075] In an embodiment, each outer layer may comprise high density polyethylene (HDPE) having a density of from 0.935 g / cm 3 to a maximum of 0.980 g / cm 3 as measured in accordance with ASTM D792. In another embodiment, the density of the high density polyethylene is from 0.935 g / cm 3 to 0.970 g / cm 3 , from 0.935 g / cm 3 to 0.960 g / cm 3 , from 0.935 g / cm 3 to 0.950 g / cm 3 , from 0.935 g / cm 3 to 0.940 g / cm 3 , from 0.940 g / cm 3 to 0.980 g / cm 3 , from 0.940 g / cm 3 to 0.970 g / cm 3 , from 0.940 g / cm 3 to 0.960 g / cm 3 , from 0.940 g / cm 3 to 0.950 g / cm 3 , from 0.950 g / cm 3 to 0.980 g / cm 3 , from 0.950 g / cm 3 to 0.970 g / cm 3 , from 0.950 g / cm 3 to 0.960 g / cm 3 , from 0.960 g / cm 3 to 0.980 g / cm 3 , from 0.960 g / cm 3 to 0.970 g / cm 3 , or from 0.970 g / cm 3 to 0.980 g / cm3 It may be.

[0076] In one or more embodiments, each outer layer may comprise high density polyethylene having a melt index (I2) of from 0.1 grams per 10 minutes (g / 10 min) to 10.0 g / 10 min as measured according to ASTM D1238 at a load of 2.16 kg and a temperature of 190°C. It is also contemplated that the melt index (I2) of the high density polyethylene may be from 0.1 g / 10 min to 5.0 g / 10 min, from 0.1 g / 10 min to 1.0 g / 10 min, from 1.0 g / 10 min to 10.0 g / 10 min, from 1.0 g / 10 min to 5.0 g / 10 min, or from 5.0 g / 10 min to 10.0 g / 10 min.

[0077] For the production of high density polyethylene, various methodologies are contemplated. For example, the high density polyethylene resin can be made using a Ziegler-Natta catalyst system, a chromium catalyst, or a single site catalyst including but not limited to bis-metallocene catalysts and constrained geometry catalysts.

[0078] In one or more embodiments, each outer layer may comprise up to 50 weight percent high density polyethylene, based on the total weight of each layer. In some embodiments, each outer layer may comprise from 0 weight percent to 90 weight percent, from 15 weight percent to 80 weight percent, from 15 weight percent to 50 weight percent, from 20 weight percent to 50 weight percent, from 30 weight percent to 40 weight percent, or from 35 weight percent to 50 weight percent high density polyethylene, based on the total weight of each layer.

[0079] The term "MDPE", when used alone (i.e., not selected MDPE), has a density of 0.917 to 0.936 g / cm 3Refers to polyethylene having a density. "MDPE" is typically made using a chromium or Ziegler-Natta catalyst or a single-site catalyst including, but not limited to, substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts, and polyvalent aryloxy ether catalysts (typically referred to as bisphenylphenoxy). Note that MDPE can be used in one or more outer layers.

[0080] In one or more embodiments, each outer layer can contain up to 50 wt% MDPE based on the total weight of each layer. In some embodiments, each outer layer can contain 0 wt% - 90 wt%, 15 wt% - 80 wt%, 15 wt% - 50 wt%, 20 wt% - 50 wt%, 30 wt% - 40 wt%, or 35 wt% - 50 wt% MDPE based on the total weight of each layer.

[0081] In an embodiment, each outer layer can contain low density polyethylene (LDPE). In one or more embodiments, the low density polyethylene can have a melt index of 0.1 g / 10 min to 10.0 g / 10 min as measured according to ASTM D1238 at a load of 2.16 kg and a temperature of 190°C. In an embodiment, the low density polyethylene can have a melt index of 0.1 g / 10 min to 5.0 g / 10 min, or 0.5 g / 10 min to 5.0 g / 10 min, or 0.5 g / 10 min to 2.0 g / 10 min. In an embodiment, the low density polyethylene can have a density of 0.916 g / cm 3 ~0.935 g / cm 3 as measured according to ASTM D792. In another embodiment, the low density polyethylene can have a density of 0.916 g / cm 3 ~0.925 g / cm 3 as measured according to ASTM D792.

[0082] In one or more embodiments, each outer layer may contain less than 50% by weight of low-density polyethylene, based on the total weight of each layer. In some embodiments, each outer layer may contain from 0% to 50%, from 0% to 40%, from 0% to 35%, from 5% to 35%, from 10% to 35%, or from 15% to 35% by weight of low-density polyethylene, based on the total weight of each layer.

[0083] In embodiments, the outer layers of the multilayer film of the present disclosure may have various thicknesses. The thickness of each outer layer may depend on many factors including, for example, the composition of each outer layer, the desired processability characteristics of the multilayer film, etc. In embodiments, each outer layer may have a thickness of from 1 micrometer (μm or micron) to 40 μm. In embodiments, each outer layer may have a thickness of from 1 μm to 40 μm, from 1 μm to 30 μm, from 1 μm to 20 μm, from 1 μm to 10 μm, from 10 μm to 40 μm, from 10 μm to 30 μm, from 10 μm to 20 μm, from 20 μm to 40 μm, from 20 μm to 30 μm, or from 30 μm to 40 μm.

[0084] The thickness of each outer layer of the multilayer film disclosed herein may constitute from 5% to 20% by weight of the total thickness of the multilayer film. In some embodiments, the thickness of each outer layer may constitute from 5% to 15%, from 5% to 10%, from 10% to 20%, from 10% to 15%, or from 15% to 20% of the total thickness of the multilayer film.

[0085] Subskin layer As described above, the multilayer film of the present disclosure may include one or more subskin layers. As used herein, a subskin layer may refer to a layer disposed between a barrier layer and an outer layer of the multilayer film. In various embodiments, each subskin layer may include one or more materials that impart improved dirt and puncture characteristics to the multilayer film as compared to conventional multilayer films.

[0086] In an embodiment, the multilayer film can be a five-layer film designated as A / B / C / D / E, and layers (B) and (D) can be subskin layers. In an embodiment, the multilayer film can be a seven-layer film designated as A / B / C / D / E / F / G, and layers (B), (C), (E), and (F) can be subskin layers. In an embodiment, the multilayer film can be a nine-layer film designated as A / B / C / D / E / F / G / H / I, and layers (B), (C), (G), and (H) can be subskin layers.

[0087] In embodiments including a plurality of subskin layers, each subskin layer can contain the same material or each subskin layer can contain different materials. For example, in a five-layer film designated as A / B / C / D / E, layers (B) and (D) can contain the same material or different materials. In a seven-layer film designated as A / B / C / D / E / F / G, one or more of layers (B), (C), (E), and (F) can contain the same material or different materials. In a nine-layer film designated as A / B / C / D / E / F / G / H / I, one or more of layers (B), (C), (G), and (H) can contain the same material or different materials.

[0088] In an embodiment, at least one subskin layer can contain a selected MDPE detailed below in this specification. In an embodiment, the subskin layer containing the selected MDPE described in this specification has a density of 0.870 g / cm 3 ~0.970 g / cm 3It can be blended with polyethylene having a density of. In embodiments, at least one subskin layer may include a selected MDPE in excess of 20% by weight as described hereinbelow based on the total weight of each layer. In one or more embodiments, each subskin layer may include a selected MDPE in excess of 20% by weight as described hereinbelow based on the total weight of each layer. In some embodiments, each subskin layer may include 30% to 100% by weight, 50% to 80% by weight, 50% to 60% by weight, 60% to 100% by weight, 60% to 80% by weight, or 80% to 100% by weight of the selected MDPE as described hereinbelow based on the total weight of each layer.

[0089] In some embodiments, a subskin layer that does not include the selected MDPE described herein may include polyethylene having a density of 0.870 g / cm 3 ~0.970 g / cm 3 In embodiments, each subskin layer may include LLDPE, HDPE, selected MDPE, MDPE, LDPE, and combinations thereof.

[0090] In one or more embodiments, each subskin layer may include linear low density polyethylene (LLDPE) having a density of 0.905 g / cm 3 ~0.930 g / cm 3 when measured in accordance with ASTM D792. In another embodiment, the density of the linear low density polyethylene is 0.905 g / cm 3 ~0.925 g / cm 3 、0.905 g / cm 3 ~0.920 g / cm 3 、0.905 g / cm 3 ~0.915 g / cm 3 、0.905 g / cm 3 ~0.910 g / cm 3 、0.910 g / cm 3 ~0.930 g / cm 3 、0.910 g / cm 3 ~0.925 g / cm 3 、0.910 g / cm 3 ~0.920 g / cm3 , 0.910 g / cm 3 ~0.915 g / cm 3 , 0.915 g / cm 3 ~0.930 g / cm 3 , 0.915 g / cm 3 ~0.925 g / cm 3 , 0.915 g / cm 3 ~0.920 g / cm 3 , 0.920 g / cm 3 ~0.930 g / cm 3 , 0.920 g / cm 3 ~0.925 g / cm 3 , 0.925 g / cm 3 ~0.930 g / cm 3 may be.

[0091] In one or more embodiments, each subskin layer may comprise linear low density polyethylene (LLDPE) having a melt index (I2) of 0.2 grams per 10 minutes (g / 10 min) to 6.0 g / 10 min as measured according to ASTM D1238. It is also contemplated that the melt index (I2) of the linear low density polyethylene may be 0.2 g / 10 min to 5.5 g / 10 min, 0.2 g / 10 min to 5.0 g / 10 min, 0.2 g / 10 min to 4.5 g / 10 min, 0.5 g / 10 min to 4.0 g / 10 min, 0.5 g / 10 min to 3.5 g / 10 min, 0.5 g / 10 min to 3.0 g / 10 min, 1.0 g / 10 min to 2.0 g / 10 min, 1.0 g / 10 min to 1.5 g / 10 min, or 1.5 g / 10 min to 2.0 g / 10 min.

[0092] According to an embodiment, the linear low density polyethylene may have a molecular weight distribution in the range of 3.5 to 5.5, expressed as the ratio of weight average molecular weight to number average molecular weight (Mw / Mn). In additional embodiments, the linear low density polyethylene may have a molecular weight distribution in the range of 3.5 to 4.5 or 4.5 to 5.5.

[0093] According to one or more additional embodiments, the linear low density polyethylene may have a zero shear viscosity ratio of 1.2 to 3.0 when measured according to the test methods described herein. In embodiments, the linear low density polyethylene may have a zero shear viscosity ratio of 1.2 to 2.5, 1.2 to 2.0, 2.0 to 3.0, 2.0 to 2.5, or 2.5 to 3.0.

[0094] For the production of linear low density polyethylene, various methodologies are contemplated. For example, linear low density polyethylene resins can be made using resins made using single site catalysts including, but not limited to, Ziegler-Natta catalyst systems, bis-metallocene catalysts and constrained geometry catalysts, resins made using post-metallocene molecular catalysts. Linear low density polyethylene resins can include linear, substantially linear, or non-uniform, polyethylene copolymers or homopolymers. Linear low density polyethylene resins contain fewer long chain branches than LDPE and substantially linear polyethylene as further defined in U.S. Patent No. 5,272,236, U.S. Patent No. 5,278,272, U.S. Patent No. 5,582,923, and U.S. Patent No. 5,733,155, homogeneous branched linear ethylene polymer compositions such as those in U.S. Patent No. 3,645,992, non-uniformly branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent No. 4,076,698, and blends thereof (such as those disclosed in U.S. Patent No. 3,914,342 or U.S. Patent No. 5,854,045). Linear low density polyethylene resins can be made by gas phase, solution phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0095] In one or more embodiments, each sub-skin layer may contain 0 wt% to 80 wt%, 0 wt% to 60 wt%, 0 wt% to 40 wt%, 0 wt% to 20 wt%, 20 wt% to 80 wt%, 20 wt% to 60 wt%, 20 wt% to 40 wt%, 40 wt% to 80 wt%, 40 wt% to 60 wt%, or 60 wt% to 80 wt% of LLDPE, based on the total weight of each layer.

[0096] In an embodiment, each sub-skin layer may comprise low-density polyethylene (LDPE). In one or more embodiments, the low-density polyethylene may have a melt index of 0.1 g / 10 min to 10.0 g / 10 min when measured according to ASTM D1238 at a load of 2.16 kg and a temperature of 190 °C. In an embodiment, the low-density polyethylene may have a melt index of 0.1 g / 10 min to 5.0 g / 10 min, or 0.5 g / 10 min to 5.0 g / 10 min, or 0.5 g / 10 min to 2.0 g / 10 min. In an embodiment, the low-density polyethylene has a density of 0.916 g / cm 3 ~0.935 g / cm 3 when measured according to ASTM D792. In another embodiment, the low-density polyethylene may have a density of 0.916 g / cm 3 ~0.925 g / cm 3 when measured according to ASTM D792.

[0097] In one or more embodiments, each sub-skin layer may comprise less than 50 wt% LDPE, based on the total weight of each layer. In some embodiments, each sub-skin layer may comprise from 0 wt% to 50 wt%, from 0 wt% to 40 wt%, from 0 wt% to 35 wt%, from 5 wt% to 35 wt%, from 10 wt% to 35 wt%, or from 15 wt% to 35 wt% LDPE, based on the total weight of each layer.

[0098] The term "MDPE", when used alone (i.e., not a selected MDPE), refers to polyethylene having a density of 0.917 to 0.936 g / cm 3 when measured according to ASTM D792. "MDPE" is typically made using a chromium or Ziegler-Natta catalyst, or a single-site catalyst including, but not limited to, a substituted mono- or bis-cyclopentadienyl catalyst (typically referred to as a metallocene), a constrained geometry catalyst, a phosphinimine catalyst, and a polyvalent aryloxy ether catalyst (typically referred to as bisphenol phenoxy). Note that MDPE can be used in one or more layers.

[0099] In one or more embodiments, each sub-skin layer may contain more than 20 wt% MDPE, based on the total weight of each layer. In some embodiments, each sub-skin layer may contain 30 wt% to 100 wt%, 50 wt% to 80 wt%, 50 wt% to 60 wt%, 60 wt% to 100 wt%, 60 wt% to 80 wt%, or 80 wt% to 100 wt% MDPE, based on the total weight of each layer.

[0100] In an embodiment, each sub-skin layer has a density of 0.935 g / cm 3 to a maximum of 0.980 g / cm 3 and may contain high-density polyethylene (HDPE). In another embodiment, the density of the HDPE is 0.935 g / cm 3 to 0.970 g / cm 3 , 0.935 g / cm 3 to 0.960 g / cm 3 , 0.935 g / cm 3 to 0.950 g / cm 3 , 0.935 g / cm 3 to 0.940 g / cm 3 , 0.940 g / cm 3 to 0.980 g / cm 3 , 0.940 g / cm 3 to 0.970 g / cm 3 , 0.940 g / cm 3 to 0.960 g / cm 3 , 0.940 g / cm 3 to 0.950 g / cm 3 , 0.950 g / cm 3 to 0.980 g / cm 3 , 0.950 g / cm 3 to 0.970 g / cm 3 , 0.950 g / cm 3 to 0.960 g / cm 3 , 0.960 g / cm 3 to 0.980 g / cm 3 , 0.960 g / cm 3 to 0.970 g / cm 3 , or 0.970 g / cm 3 to 0.980 g / cm3 It may be.

[0101] In one or more embodiments, each sub-skin layer may comprise HDPE having a melt index (I2) of from 0.1 grams per 10 minutes (g / 10 min) to 10.0 g / 10 min as measured according to ASTM D1238 at a load of 2.16 kg and a temperature of 190°C. It is also contemplated that the melt index (I2) of the high-density polyethylene can be from 0.1 g / 10 min to 5.0 g / 10 min, from 0.1 g / 10 min to 1.0 g / 10 min, from 1.0 g / 10 min to 10.0 g / 10 min, from 1.0 g / 10 min to 5.0 g / 10 min, or from 5.0 g / 10 min to 10.0 g / 10 min.

[0102] For the production of high-density polyethylene, various methodologies are contemplated. For example, the HDPE resin can be made using a Ziegler-Natta catalyst system, a chromium catalyst, or a single-site catalyst including but not limited to bis-metallocene catalysts and constrained geometry catalysts.

[0103] In one or more embodiments, each sub-skin layer may comprise up to 50 wt% HDPE based on the total weight of each layer. In some embodiments, each sub-skin layer can comprise from 0 wt% to 90 wt%, from 15 wt% to 80 wt%, from 15 wt% to 50 wt%, from 20 wt% to 50 wt%, from 30 wt% to 40 wt%, or from 35 wt% to 50 wt% HDPE based on the total weight of each layer.

[0104] In embodiments, each sub-skin layer of the multi-layer film of the present disclosure can have various thicknesses. The thickness of each sub-skin layer can depend on many factors including, for example, the composition of the sub-skin layer, the desired overall dirt and puncture characteristics of the multi-layer film, etc. In embodiments, each sub-skin layer can have a thickness of from 1 micrometer (μm) to 85 μm. In embodiments, each outer layer can have a thickness of from 1 μm to 80 μm, from 1 μm to 60 μm, from 1 μm to 40 μm, from 1 μm to 20 μm, from 20 μm to 80 μm, from 20 μm to 60 μm, from 20 μm to 40 μm, from 40 μm to 80 μm, from 40 μm to 60 μm, or from 60 μm to 80 μm.

[0105] The thickness of each sub-skin layer of the multilayer film disclosed in this specification may constitute 5 wt% to 40 wt% of the total thickness of the multilayer film. In some embodiments, each sub-skin layer may constitute 5% to 20 wt%, 5% to 15%, 5% to 10%, 10% to 40%, 10% to 20%, 10% to 15%, 15% to 40%, 15% to 20%, or 20% to 40% of the total thickness of the multilayer film.

[0106] Additional layer As described above, the multilayer film according to an embodiment may include layers in addition to the barrier layer, the outer layer, and the sub-skin layer. Such additional layers may include additional layers containing polyethylene, which may include the selected MDPE detailed below in this specification, and in some embodiments may not include the selected MDPE detailed below in this specification. In one or more embodiments, the additional polyethylene layer may include a blend of LLDPE, LDPE, MDPE, HDPE, the selected MDPE detailed below in this specification, and combinations thereof. The various polyethylene components (e.g., LLDPE, LDPE, HDPE, and the selected MDPE detailed below in this specification) may be included in the additional polyethylene layer in any desired amounts according to the properties of the multilayer film to be achieved. Such additional layers may alternatively or additionally include one or more additional tie layers.

[0107] Exemplary 7-layer embodiment In an exemplary embodiment (the "exemplary 7-layer embodiment"), the multilayer film may be a 7-layer film designated as A / B / C / D / E / F / G, the first layer may be designated as (A), the second layer may be designated as (B), the third layer may be designated as (C), the fourth layer may be designated as (D), the fifth layer may be designated as (E), the sixth layer may be designated as (F), and the seventh layer may be designated as (G).

[0108] In an exemplary seven-layer embodiment, the fourth layer (D) can be an intermediate or core layer of a seven-layer film that can be disposed between the third layer (D) and the fifth layer (E). In an exemplary seven-layer embodiment, the second layer (B) can be disposed between the first layer (A) and the third layer (C). In an exemplary seven-layer embodiment, the sixth layer (F) can be disposed between the fifth (E) layer and the seventh layer (G). In an exemplary seven-layer embodiment, the first layer (A) and the seventh layer (G) can be the outermost layers of the multilayer film.

[0109] In an exemplary seven-layer embodiment, the first layer, the third layer, or both may be in direct contact with the second layer. In an exemplary seven-layer embodiment, the second layer, the fourth layer, or both may be in direct contact with the third layer. In an exemplary seven-layer embodiment, the third layer, the fifth layer, or both may be in direct contact with the fourth layer. In an exemplary seven-layer embodiment, the fourth layer, the sixth layer, or both may be in direct contact with the fifth layer. In an exemplary seven-layer embodiment, the fifth layer, the seventh layer, or both may be in direct contact with the sixth layer.

[0110] An exemplary seven-layer embodiment can have two outer layers each containing polyethylene, a first sub-skin layer containing a first selected MDPE, a second sub-skin layer containing a second selected MDPE, a barrier layer containing a polar material, and two tie layers adjacent to both sides of the barrier layer. In an embodiment, the polar material is ethylene vinyl alcohol (EVOH). In an exemplary seven-layer embodiment, layer (A) and layer (G) can be the outer layers, layer (B) and layer (F) can be the sub-skin layers, layer (C) and layer (E) can be the tie layers, and layer (D) can be the barrier layer.

[0111] When used in a film, the selected MDPE detailed below herein has toughness and Elastic moduluscan exhibit a balance, thereby enabling the multilayer film of the exemplary seven-layer embodiment to exhibit improved abuse properties (i.e., dirt, puncture energy, tear). For example, by utilizing the selected MDPE detailed below in the present specification in combination with a barrier layer containing EVOH as a polar material, a multilayer film having sufficient properties can be produced with improved recyclability compared to conventional multilayer films.

[0112] The multilayer film of the exemplary seven-layer embodiment can have various thicknesses. In an embodiment, the multilayer film of the exemplary seven-layer embodiment can have a thickness of less than 205 micrometers (μm or micron). In an embodiment, the multilayer film of the exemplary seven-layer embodiment can have a thickness of 25 μm to 200 μm, 25 μm to 150 μm, 25 μm to 100 μm, 25 μm to 75 μm, 25 μm to 50 μm, 50 μm to 200 μm, 50 μm to 150 μm, 50 μm to 100 μm, 50 μm to 75 μm, 75 μm to 200 μm, 75 μm to 150 μm, 75 μm to 100 μm, 100 μm to 200 μm, 100 μm to 150 μm, or 150 μm to 200 μm.

[0113] The barrier layer of the multilayer film of the exemplary seven-layer embodiment contains EVOH as a polar material. In an embodiment, the barrier layer of the exemplary seven-layer embodiment consists of EVOH. The barrier layer of the exemplary seven-layer embodiment can constitute 1% to 10% of the total thickness of the multilayer film of the exemplary seven-layer embodiment. In some embodiments, the barrier layer can constitute 1% to 10%, 1% to 8%, 1% to 6%, 1% to 4%, 1% to 2%, 2% to 10%, 2% to 8%, 2% to 6%, 2% to 4%, 4% to 10%, 4% to 8%, 4% to 6%, 6% to 10%, 6% to 8%, or 8% to 10% of the total thickness of the multilayer film of the exemplary seven-layer embodiment.

[0114] In an exemplary seven-layer embodiment, the tie layer may comprise the anhydride-grafted ethylene / alpha-olefin interpolymer described above, or a blend of the anhydride-grafted ethylene / alpha-olefin interpolymer described in detail below herein and a selected MDPE. The tie layer of the exemplary seven-layer embodiment may help the barrier layer to adhere to a layer that does not contain a polar material such as a subskin layer. The tie layers of the exemplary seven-layer embodiment may together constitute a distribution of 1% to 20%, 1% to 15%, 1% to 10%, 1% to 5%, 5% to 20%, 5% to 15%, 5% to 10%, 10% to 20%, 10% to 15%, or 15% to 20% of the total thickness of the multilayer film of the exemplary seven-layer embodiment.

[0115] In an exemplary seven-layer embodiment, layers (B) and (F) may each be adjacent to tie layers (C) and (E), respectively. In an exemplary seven-layer embodiment, layers (B) and (F) may each be in direct contact with tie layers (C) and (E), respectively. Layers (B) and (F) each comprise a selected MDPE described in detail below herein. In an exemplary seven-layer embodiment, layers (B) and (D) may have the same composition or different compositions.

[0116] In an exemplary seven-layer embodiment, layers (B) and (F) may each comprise more than 10 wt% of the selected MDPE described below herein, based on the total weight of each layer. In some embodiments, each subskin layer may comprise 30 wt% to 100 wt%, 50 wt% to 80 wt%, 50 wt% to 60 wt%, 60 wt% to 100 wt%, 60 wt% to 80 wt%, or 80 wt% to 100 wt% of the selected MDPE described below herein, based on the total weight of each layer.

[0117] In an exemplary seven-layer embodiment, layers (B) and (F) may each contain less than 50 wt% LDPE, based on the total weight of each layer. In some embodiments, layers (B) and (F) may each contain 0 wt% to 50 wt%, 0 wt% to 40 wt%, 0 wt% to 35 wt%, 5 wt% to 35 wt%, 10 wt% to 35 wt%, or 15 wt% to 35 wt% LDPE, based on the total weight of each layer.

[0118] In an exemplary seven-layer embodiment, layers (B) and (F) together constitute 10% to 80%, 10% to 60%, 10% to 40%, 10% to 20%, 20% to 80%, 20% to 60%, 20% to 40%, 40% to 80%, 40% to 60%, or 60% to 80% of the thickness of the multilayer film of the exemplary seven-layer embodiment.

[0119] Layers (A) and (G) of an exemplary seven-layer embodiment contain polyethylene. In an exemplary seven-layer embodiment, layer (A) may be adjacent to layer (B), and layer (G) may be adjacent to layer (F). In an exemplary seven-layer embodiment, layer (A) may be in direct contact with layer (B), and layer (G) may be in direct contact with layer (F). In an embodiment, layers (A) and (G) may have the same composition or different compositions.

[0120] Each of layers (A) and (G) of an exemplary seven-layer embodiment independently contains more than 20 wt% LLDPE, based on the total weight of each layer. In some embodiments, each of layers (A) and (G) may contain 30 wt% to 100 wt%, 50 wt% to 80 wt%, 50 wt% to 60 wt%, 60 wt% to 100 wt%, 60 wt% to 80 wt%, or 80 wt% to 100 wt% LLDPE, based on the total weight of each layer.

[0121] In an exemplary seven-layer embodiment, layers (A) and (G) can each contain less than 50% by weight of LDPE, based on the total weight of each layer. In some embodiments, layers (A) and (G) can each contain from 0% to 50%, from 0% to 40%, from 0% to 35%, from 5% to 35%, from 10% to 35%, or from 15% to 35% by weight of LDPE, based on the total weight of each layer.

[0122] In an exemplary seven-layer embodiment, layers (A) and (G) together constitute from 10% to 40%, from 10% to 20%, or from 20% to 40% of the thickness of the multilayer film of the exemplary seven-layer embodiment.

[0123] As described above, by using the selected MDPE detailed herein as a component of a multilayer film, such as the multilayer film described in the exemplary seven-layer embodiment, a multilayer film having an improved balance of dart impact resistance and stiffness (measured at 2% secant Elastic modulus can be provided.

[0124] Exemplary nine-layer embodiment In another exemplary embodiment (the "exemplary nine-layer embodiment"), the multilayer film can be a nine-layer film designated as A / B / C / D / E / F / G / H / I, where the first layer can be designated as (A), the second layer can be designated as (B), the third layer can be designated as (C), the fourth layer can be designated as (D), the fifth layer can be designated as (E), the sixth layer can be designated as (F), the seventh layer can be designated as (G), the eighth layer can be designated as (H), and the ninth layer can be designated as (I). In the exemplary nine-layer embodiment, layer (E) may be referred to as an intermediate or core layer. The exemplary nine-layer embodiment can include two outer layers each including polyethylene, a first subskin layer, a second subskin layer, a third subskin layer, a fourth subskin layer, a barrier material layer, and two tie layers adjacent to both sides of the barrier layer. In the exemplary nine-layer embodiment, layer (E) can be a barrier layer, layer (D) and layer (F) can be tie layers, one or both of layer (A) and layer (I) can be an outer layer, and one or more of layer (B), layer (C), layer (G), and layer (H) can be a subskin layer. Layer (B) can be referred to as the "first subskin layer", layer (C) can be referred to as the "second subskin layer", layer (G) can be referred to as the "third subskin layer", and layer (H) can be referred to as the "fourth subskin layer". The exemplary nine-layer embodiment can include a barrier layer containing ethylene vinyl alcohol (EVOH). In the exemplary nine-layer embodiment, one or more of the first subskin layer, the second subskin layer, the third subskin layer, and the fourth subskin layer can include a selected MDPE detailed below herein.

[0125] As described above, in an exemplary nine-layer embodiment, the fifth layer (E) can be an intermediate or core layer of a nine-layer film that can be disposed between the fourth layer (D) and the sixth layer (F). In an exemplary nine-layer embodiment, the second layer (B) can be disposed between the first layer (A) and the third layer (C). In an exemplary nine-layer embodiment, the third layer (C) can be disposed between the second layer (B) and the fourth layer (D). In an exemplary nine-layer embodiment, the sixth layer (F) can be disposed between the fifth layer (E) and the seventh layer (G). In an exemplary nine-layer embodiment, the seventh layer (G) can be disposed between the sixth layer (F) and the eighth layer (H). In an exemplary nine-layer embodiment, the eighth layer (H) can be disposed between the seventh layer (G) and the ninth layer (I). In an exemplary nine-layer embodiment, the first layer (A) and the ninth layer (I) can be the outermost layers of the nine-layer film.

[0126] In an exemplary nine-layer embodiment, the first layer (A), the third layer (C), or both can be in direct contact with the second layer (B). In an exemplary nine-layer embodiment, the second layer (B), the fourth layer (D), or both can be in direct contact with the third layer (C). In an exemplary nine-layer embodiment, the third layer (C), the fifth layer (E), or both can be in direct contact with the fourth layer (D). In an exemplary nine-layer embodiment, the fourth layer (D), the sixth layer (F), or both can be in direct contact with the fifth layer (E). In an exemplary nine-layer embodiment, the fifth layer (E), the seventh layer (G), or both can be in direct contact with the sixth layer (F). In an exemplary nine-layer embodiment, the sixth layer (F), the eighth layer (H), or both can be in direct contact with the seventh layer (G). In an exemplary nine-layer embodiment, the seventh layer (G), the ninth layer (I), or both can be in direct contact with the eighth layer (H).

[0127] When utilized in an exemplary nine-layer embodiment, the selected MDPE detailed below herein has toughness and Elastic moduluscan exhibit a balance, thereby enabling the multilayer film of the exemplary nine-layer embodiment to exhibit improved abuse properties (i.e., dirt, puncture energy, tear). For example, by utilizing the selected MDPE detailed below herein in combination with a layer containing EVOH as a polar material, a multilayer film of an exemplary nine-layer embodiment with sufficient properties can be produced along with improved recyclability as compared to conventional multilayer films.

[0128] The multilayer film of the exemplary nine-layer embodiment can have various thicknesses. In an embodiment, the multilayer film of the exemplary nine-layer embodiment can have a thickness of less than 205 micrometers (μm or micron). In an embodiment, the multilayer film can have a thickness of 25 μm to 150 μm. In an embodiment, the multilayer film can have an overall thickness of 25 μm to 100 μm, 25 μm to 75 μm, 25 μm to 50 μm, 50 μm to 150 μm, 50 μm to 100 μm, 50 μm to 75 μm, 75 μm to 150 μm, 75 μm to 100 μm, or 100 μm to 150 μm.

[0129] The barrier layer of the multilayer film of the exemplary nine-layer embodiment can contain EVOH as a polar material. The barrier layer of the exemplary nine-layer embodiment can consist of EVOH. The barrier layer of the exemplary nine-layer embodiment can constitute 1% to 10% of the total thickness of the multilayer film of the exemplary nine-layer embodiment. In some embodiments, the barrier layer can constitute 1% to 10%, 1% to 8%, 1% to 6%, 1% to 4%, 1% to 2%, 2% to 10%, 2% to 8%, 2% to 6%, 2% to 4%, 4% to 10%, 4% to 8%, 4% to 6%, 6% to 10%, 6% to 8%, or 8% to 10% of the total thickness of the multilayer film of the exemplary nine-layer embodiment.

[0130] In an exemplary nine-layer embodiment, the tie layer may comprise the anhydride-grafted ethylene / alpha-olefin interpolymer described above, or a blend of this anhydride-grafted ethylene / alpha-olefin interpolymer and a selected MDPE detailed below herein. The tie layer of the exemplary nine-layer embodiment may help the barrier layer to adhere to a layer that does not contain a polar material such as a subskin layer. The tie layers of the exemplary nine-layer embodiment, in combination, may constitute a distribution of from 1% to 20%, 1% to 15%, 1% to 10%, 1% to 5%, 5% to 20%, 5% to 15%, 5% to 10%, 10% to 20%, 10% to 15%, or 15% to 20% of the total thickness of the multilayer film of the exemplary nine-layer embodiment.

[0131] In an exemplary nine-layer embodiment, layers (C) and (G) may each be adjacent to tie layers (D) and (F), respectively. In an exemplary nine-layer embodiment, layers (C) and (G) may each be in direct contact with tie layers (D) and (F), respectively. In an exemplary nine-layer embodiment, layer (B) may be adjacent to layer (A) and layer (C), and (H) may be adjacent to layer (G) and layer (I). In an exemplary nine-layer embodiment, layer (B) may be in direct contact with layer (A) and layer (C), and (H) may be in direct contact with layer (G) and layer (I).

[0132] In an exemplary nine-layer embodiment, one or more of layers (B), (C), (G), and (H) may have the same composition or different compositions. In an exemplary nine-layer embodiment, layers (C) and (G) may have the same composition. In an exemplary nine-layer embodiment, layers (B) and (H) may have the same composition.

[0133] In an exemplary nine-layer embodiment, layer (B) may comprise a first selected MDPE. Layer (C) may comprise a second selected MDPE. Layer (G) may comprise a third selected MDPE. Layer (H) may comprise a fourth selected MDPE. In an embodiment, the first selected MDPE, the second selected MDPE, the third selected MDPE, and the fourth selected MDPE may all be different compositions. In an embodiment, the first selected MDPE and the fourth selected MDPE may be the same composition. In an embodiment, the second selected MDPE and the third MDPE may be the same composition. In an embodiment, the first selected MDPE, the second selected MDPE, the third selected MDPE, and the fourth selected MDPE may all be the same composition.

[0134] In an exemplary nine-layer embodiment, the subskin layers that may comprise selected MDPE may each comprise, based on the total weight of each layer, 5 wt% or more than 20 wt% of the selected MDPE described below herein. In an exemplary nine-layer embodiment, one or more of layers (B), (C), (G), and (H) may each comprise, based on the total weight of each layer, 5 wt% to 100 wt%, 50 wt% to 80 wt%, 50 wt% to 60 wt%, 60 wt% to 100 wt%, 60 wt% to 80 wt%, or 80 wt% to 100 wt% of the selected MDPE described below herein.

[0135] In an exemplary nine-layer embodiment, one or more of layers (B), (C), (G), and (H) may each comprise, based on the total weight of each layer, 0 wt% to 80 wt%, 0 wt% to 60 wt%, 0 wt% to 40 wt%, 0 wt% to 20 wt%, 20 wt% to 80 wt%, 20 wt% to 60 wt%, 20 wt% to 40 wt%, 40 wt% to 80 wt%, 40 wt% to 60 wt%, or 60 wt% to 80 wt% of LLDPE.

[0136] In an exemplary nine-layer embodiment, one or more of layers (B), (C), (G), and (H) may each contain 0 wt% to 50 wt%, 0 wt% to 40 wt%, 0 wt% to 35 wt%, 5 wt% to 35 wt%, 10 wt% to 35 wt%, or 15 wt% to 35 wt% of LDPE, based on the total weight of each respective layer.

[0137] In an exemplary nine-layer embodiment, one or more of layers (B), (C), (G), and (H) may each contain 20 wt% to 100 wt%, 30 wt% to 100 wt%, 50 wt% to 80 wt%, 50 wt% to 60 wt%, 60 wt% to 100 wt%, 60 wt% to 80 wt%, or 80 wt% to 100 wt% of MDPE, based on the total weight of each respective layer.

[0138] In an exemplary nine-layer embodiment, one or more of layers (B), (C), (G), and (H) may each contain 0 wt% to 80 wt%, 0 wt% to 60 wt%, 0 wt% to 40 wt%, 0 wt% to 20 wt%, 20 wt% to 80 wt%, 20 wt% to 60 wt%, 20 wt% to 40 wt%, 40 wt% to 80 wt%, 40 wt% to 60 wt%, or 60 wt% to 80 wt% of HDPE, based on the total weight of each respective layer.

[0139] In an exemplary nine-layer embodiment, layers (B), (C), (G), and (H) together constitute 10% to 80%, 10% to 60%, 10% to 40%, 10% to 20%, 20% to 80%, 20% to 60%, 20% to 40%, 40% to 80%, 40% to 60%, or 60% to 80% of the thickness of the multilayer film of the exemplary nine-layer embodiment.

[0140] Layers (A) and (I) of the exemplary nine-layer embodiment contain polyethylene. In an exemplary nine-layer embodiment, layer (A) may be adjacent to layer (B), and layer (I) may be adjacent to layer (H). In an exemplary nine-layer embodiment, layer (A) may be in direct contact with layer (B), and layer (I) may be in direct contact with layer (H). In an exemplary nine-layer embodiment, layers (A) and (I) may have the same composition or different compositions.

[0141] In each of layers (A) and (I) of the exemplary nine-layer embodiment, based on the total weight of each layer, it independently contains LLDPE in excess of 20% by weight. In some embodiments, each of layers (A) and (I) may contain 30% to 100% by weight, 50% to 80% by weight, 50% to 60% by weight, 60% to 100% by weight, 60% to 80% by weight, or 80% to 100% by weight of LLDPE, based on the total weight of each layer.

[0142] In the exemplary nine-layer embodiment, layers (A) and (I) may contain less than 50% by weight of LDPE, based on the total weight of each layer. In some embodiments, layers (A) and (I) may each contain 0% to 50% by weight, 0% to 40% by weight, 0% to 35% by weight, 5% to 35% by weight, 10% to 35% by weight, or 15% to 35% by weight of LDPE, based on the total weight of each layer.

[0143] In the exemplary nine-layer embodiment, layers (A) and (I) together constitute 10% to 40%, 10% to 20%, or 20% to 40% of the thickness of the multilayer film of the exemplary nine-layer embodiment.

[0144] As described above, by using the selected MDPE detailed herein as a component of a multilayer film, such as the multilayer film described in the exemplary nine-layer embodiment, a multilayer film having an improved balance of dirt impact resistance and rigidity (measured at 2% secant Elastic modulus can be provided.

[0145] The method for producing the film described herein Regarding the production of multilayer films, various methodologies are contemplated. In one or more embodiments, the process for manufacturing the multilayer film may include the extrusion of a cast film or the extrusion of an inflation film.

[0146] In some embodiments, the process of manufacturing a multilayer film can include forming an inflation film bubble. In some embodiments, the inflation film bubble can be a multilayer inflation film bubble. According to this embodiment, further, the multilayer inflation film bubble can include at least 5, 7, 9, or more layers, and these layers may be adhered to each other.

[0147] During an embodiment of the inflation film process, an extruded film can be formed (inflated) from an extrusion die and pulled upward in a tower onto a nip. Next, the film can be wound around a core. Before winding the film around the core, a folding device can be used to cut and fold the end of the film. Thereby, it becomes difficult to separate the layers of the film, which can be important for general transportation applications or for rugged transport sack applications.

[0148] In a further embodiment, the inflation film bubble can be formed via an inflation film extrusion line having a length-to-diameter (“L / D”) ratio of 30 to 1. In some embodiments, the extrusion line can have a blow-up ratio of 1 to 5, 1 to 3, 2 to 5, or 2 to 3. In some embodiments, the extrusion line can utilize a die having internal bubble cooling. In some embodiments, the die gap can be 1 millimeter (mm) to 5 mm, 1 mm to 3 mm, 2 mm to 5 mm, or 2 mm to 3 mm.

[0149] In some embodiments, the extrusion line may utilize a film thickness gauge scanner. In some embodiments, during the extrusion process, the multilayer film thickness may be maintained between 15 μm and 115 μm. In embodiments, the multilayer film thickness may be maintained between 15 μm and 100 μm, 15 μm and 75 μm, 15 μm and 50 μm, 15 μm and 25 μm, 25 μm and 115 μm, 25 μm and 100 μm, 25 μm and 75 μm, 25 μm and 50 μm, 50 μm and 115 μm, 50 μm and 100 μm, 50 μm and 75 μm, 75 μm and 115 μm, 75 μm and 100 μm, or 100 μm and 115 μm.

[0150] In some embodiments, the step of forming the multilayer inflation film bubble may be performed at a temperature of 350 - 500°F, or 375 - 475°F. The output speed may be 5 lb / hr / in - 25 lb / hr / in, 5 lb / hr / in - 20 lb / hr / in, 5 lb / hr / in - 15 lb / hr / in, 5 lb / hr / in - 10 lb / hr / in, 10 lb / hr / in - 25 lb / hr / in, 10 lb / hr / in - 20 lb / hr / in, 10 lb / hr / in - 15 lb / hr / in, 15 lb / hr / in - 25 lb / hr / in, 15 lb / hr / in - 20 lb / hr / in, or 20 lb / hr / in - 25 lb / hr / in.

[0151] Article Embodiments of the present disclosure also relate to articles such as packages formed from the multilayer films of the present disclosure. Such packages may be formed from any of the multilayer films of the present disclosure described herein. The multilayer films of the present disclosure are particularly useful in articles where good tear strength and dirt strength are desired.

[0152] Examples of such articles include flexible packages, pouches, stand-up pouches, and preformed packages or pouches.

[0153] Various methods for generating article embodiments from the multilayer films disclosed herein will be well known to those skilled in the art.

[0154] Composition and Property Evaluation of Selected MDPE In one or more embodiments, the selected MDPE (also referred to herein as "polyethylene composition") has a density of 0.924 g / cm 3 to 0.936 g / cm 3 . For example, embodiments of the polyethylene composition of the present disclosure have a density of 0.924 g / cm 3 to 0.931 g / cm 3 , 0.924 g / cm 3 to 0.928 g / cm 3 , 0.927 g / cm 3 to 0.931 g / cm 3 , or 0.929 g / cm 3 to 0.933 g / cm 3 . According to additional embodiments, the polyethylene composition can have a density of 0.924 to 0.928, 0.928 g / cm 3 to 0.932 g / cm 3 , 0.932 g / cm 3 to 0.936 g / cm 3 , or any combination of these ranges.

[0155] In one or more embodiments, the polyethylene composition can have a melt index (I2) of 0.25 g / 10 min to 2.0 g / 10 min, for example, 0.5 g / 10 min to 1.2 g / 10 min. For example, in one or more embodiments, the polyethylene composition can have a melt index (I2) of 0.25 g / 10 min to 0.5 g / 10 min, 0.5 g / 10 min to 0.7 g / 10 min, 0.7 g / 10 min to 0.9 g / 10 min, 0.59 g / 10 min to 1.1 g / 10 min, 1.1 g / 10 min to 1.3 g / 10 min, 1.3 g / 10 min to 1.5 g / 10 min, 1.5 g / 10 min to 1.7 g / 10 min, 1.7 g / 10 min to 2.0 g / 10 min, or any combination of these ranges. According to additional embodiments, the polyethylene composition can have a melt index (I2) of 0.65 to 1.05.

[0156] According to an embodiment, the polyethylene composition can have a molecular weight distribution in the range of 2.5 to 8.0, represented as the ratio of weight average molecular weight to number average molecular weight (Mw / Mn). For example, the polyethylene composition can have a molecular weight distribution of 2.5 to 3.0, 3.0 to 3.5, 3.5 to 4.0, 4.0 to 4.5, 4.5 to 5.0, 5.0 to 5.5, 5.5 to 6.0, 6.0 to 6.5, 6.5 to 7.0, 7.0 to 7.5, 7.5 to 8.0, or any combination of these ranges. In an additional embodiment, the polyethylene composition can have a molecular weight distribution of 3.0 to 5.0. As described herein, the molecular weight distribution can be calculated according to the gel permeation chromatography (GPC) technique described herein.

[0157] According to one or more additional embodiments, the polyethylene composition can have a zero shear viscosity ratio of less than 3.0. For example, the polyethylene composition can have a zero shear viscosity ratio of less than 2.9, less than 2.8, less than 2.7, less than 2.6, less than 2.5, less than 2.4, less than 2.3, less than 2.2, less than 2.1, less than 2.0, less than 1.9, less than 1.8, less than 1.7, less than 1.6, less than 1.5, less than 1.4, less than 1.3, less than 1.2, or in some cases less than 1.1. In one or more embodiments, the polyethylene composition can have a zero shear viscosity ratio of at least 1.0.

[0158] As described herein, a polyethylene "fraction" refers to a portion of the overall composition of a polyethylene composition. Embodiments of the present disclosure include at least a "first polyethylene fraction" and a "second polyethylene fraction". The various fractions included in a polyethylene composition can be quantified via an improved comonomer composition distribution (iCCD) analysis based on their temperature ranges in an elution profile. Unless otherwise specified, any elution profile referred to herein is that observed via iCCD. Examples of such fractions will be better understood in view of the examples provided herein. Generally, the first fraction can include a single peak in the temperature range of the first fraction, and the second fraction can include a single peak in the temperature range of the second fraction. The polyethylene compositions described herein can be referred to as "multimodal", which means that those polyethylene compositions include at least two peaks in their elution profiles. Some embodiments can be "bimodal", which means that two major peaks are present.

[0159] Referring to the iCCD distribution described above, FIG. 1 schematically shows a sample iCCD distribution 100 along with a cumulative weight fraction curve 200. FIG. 1 generally shows some features of the iCCD profile of a polyethylene composition described herein, such as a first fraction, a second fraction, a half-peak width, etc., which are discussed in detail herein. Thus, FIG. 1 can be used as a reference with respect to the disclosure related to the iCCD profile provided herein. Specifically, a first fraction 102 and a second fraction 106 are shown. The first fraction 102 has a peak 104, and the second fraction 106 has a peak 108. Each fraction has a half-peak width 110 and 112. It should be understood that the profile of FIG. 1 is not obtained from an experiment or observation, but rather is provided for the purpose of providing information to explain certain features of an iCCD elution profile.

[0160] In one or more embodiments, the first polyethylene fraction may have a single peak in the elution profile via iCCD in the temperature range of 45°C to 87°C. As used herein, "single peak" refers to an iCCD in which a particular fraction contains only a single peak. That is, in some embodiments, the iCCDs of the first and second polyethylene fractions include only an upward slope region followed by a downward slope region to form a single peak. In one or more embodiments, the single peak of the first polyethylene fraction may be in the temperature range of 60°C to 85°C, for example, 70°C to 85°C. Without being bound by theory, in at least some embodiments of the polyethylene compositions of the present disclosure where a dual reactor design is used for polymerization, a combination of high density crystalline domains and low density amorphous domains may be present. Impact strength is mainly controlled by the tie concentration connecting the amorphous regions or adjacent lamellae. When the density is less than 0.910 g / cm 3 , the relative tie chain concentration is presumed to be relatively large. The peak of the first polymer fraction in the composition of the present disclosure may be in the temperature range of 60°C to 85°C, which may provide a higher tie chain concentration and result in functional benefits such as improved toughness.

[0161] It should be understood that the peak of the first or second polyethylene fraction cannot be formed by the minimum value of each polyethylene fraction at a certain defined temperature boundary. That is, the peak must be a peak in the context of the entire range, not a peak formed by the threshold temperature of the polyethylene fraction. For example, if a single peak followed by a single valley is present in the polyethylene fraction (an upward slope followed by a downward slope followed by an upward slope), such a polyethylene fraction would have only a single peak.

[0162] In one or more embodiments, the second polyethylene fraction may have a single peak in the elution profile via iCCD in the temperature range of 95°C to 120°C. The temperature range of 95 - 120°C for the second polyethylene fraction may be desirable because the low molecular weight, high density components at 95 - 120°C enable polyethylene to achieve a higher overall density while maintaining a lower density fraction when explained by the ratio of these two fractions.

[0163] In one or more embodiments, the width of the single peak of the second polyethylene fraction at 50 percent of the peak height may be less than 5.0°C, less than 4°C, or in some cases less than 3°C. Generally, the lower temperature range at 50 percent of the peak height corresponds to a "sharper" peak. Without being bound by a particular theory, a "sharper" or "narrower" peak is a characteristic caused by the molecular catalyst, indicating minimal comonomer incorporation in the high density fraction and allowing for a greater density split between the two fractions.

[0164] In one or more embodiments, the polyethylene composition may have a minimum in the temperature range of 80°C to 90°C in the elution profile via iCCD. This minimum may be present between the peaks of the first and second polyethylene fractions.

[0165] In the embodiments described herein, the first polyethylene fraction area is the area within the elution profile at 45°C to 87°C under the single peak of the first polyethylene fraction. Similarly, the second polyethylene fraction area is the area within the elution profile at 95°C to 120°C under the single peak of the second polyethylene fraction. The first polyethylene fraction area and the second polyethylene fraction may each generally correspond to the total relative mass of each polymer fraction in the polyethylene composition. Generally, the polyethylene fraction area within the iCCD profile can be determined by integrating the iCCD profile between the specified start and end temperatures.

[0166] According to one or more embodiments, the difference between the single peak of the second polyethylene fraction and the single peak of the first polyethylene fraction can be at least 10 °C. For example, the difference between the single peak of the second polyethylene fraction and the single peak of the first polyethylene fraction can be at least 12 °C, 14 °C, 16 °C, 18 °C, or in some cases at least 20 °C.

[0167] In one or more embodiments, the area of the first polyethylene fraction can constitute at least 40% of the total area of the elution profile (e.g., at least 42%, at least 44%, at least 46%, at least 48%, at least 50%, at least 52%, or in some cases at least 54% of the total area of the elution profile). For example, the area of the first polyethylene fraction can constitute 40% - 65% of the total area of the elution profile, such as 42% - 58%, 43% - 45%, 45% - 47%, 53% - 55%, or 55% - 57%.

[0168] According to one or more embodiments, the area of the second polyethylene fraction can constitute at least 25% of the total area of the elution profile (e.g., at least 30%, at least 35%, or in some cases at least 40% of the total area of the elution profile). For example, the area of the first polyethylene fraction can constitute 20% - 50%, 27% - 31%, or 41% - 48% of the total area of the elution profile.

[0169] According to some embodiments, the ratio of the area of the first polyethylene fraction to the area of the second polyethylene fraction can be 0.75 - 2.5 (e.g., 0.75 - 1.0, 1.0 - 1.25, 1.25 - 1.5, 1.5 - 1.75, 1.75 - 2.0, 2.0 - 2.25, 2.25 - 2.5, or any combination of these ranges).

[0170] In one or more embodiments, the polyethylene composition comprises ethylene and C3 - C 12It is formed from the polymerization with comonomers such as alkenes. The comonomers envisaged include C6-C9 alkenes such as 1-octene and 1-hexene. In one or more embodiments, the comonomer is 1-octene.

[0171] In one or more embodiments, the difference between the single peak of the second polyethylene fraction and the single peak of the first polyethylene fraction is at least 10 °C, at least 12.5 °C, at least 15 °C, at least 17.5 °C, or in some cases at least 20 °C.

[0172] In one or more embodiments, the first polyethylene fraction may have a melt index (I2) of 0.01 to 0.18 g / 10 min. For example, according to one or more embodiments, the first polyethylene fraction has a melt index (I2) of 0.01 g / 10 min to 0.03 g / 10 min, 0.03 g / 10 min to 0.05 g / 10 min, 0.05 g / 10 min to 0.07 g / 10 min, 0.07 g / 10 min to 0.09 g / 10 min, 0.09 g / 10 min to 0.11 g / 10 min, 0.11 g / 10 min to 0.13 g / 10 min, 0.13 g / 10 min to 0.15 g / 10 min, 0.15 g / 10 min to 0.18 g / 10 min, or any combination of these ranges.

[0173] In one or more embodiments, the second polyethylene fraction may have a melt index (I2) of 1 to 10,000 g / 10 min. For example, in one or more embodiments, the second polyethylene fraction has a melt index (I2) of 10 g / 10 min to 1,000 g / 10 min, 20 g / 10 min to 800 g / 10 min, 1 g / 10 min to 100 g / 10 min, 100 g / 10 min to 1,000 g / 10 min, 1,000 g / 10 min to 10,000 g / 10 min, or any combination of these ranges.

[0174] In one or more embodiments, the weight average molecular weight of the second polyethylene fraction can be 120,000 g / mol or less, such as from 20,000 g / mol to 120,000 g / mol, or from 40,000 g / mol to 65,000 g / mol. In additional embodiments, the weight average molecular weight of the second polyethylene fraction can be from 20,000 g / mol to 40,000 g / mol, from 40,000 g / mol to 60,000 g / mol, from 60,000 g / mol to 80,000 g / mol, from 80,000 g / mol to 100,000 g / mol, from 100,000 g / mol to 120,000 g / mol, or any combination of these ranges. The molecular weight of the polyethylene fraction can be calculated based on the results of GPC as described below.

[0175] The polyethylene compositions described herein can have relatively good dirt strength when formed into a monolayer inflation film. According to one or more embodiments, a monolayer inflation film formed from the polyethylene composition and having a thickness of 2 mils has a dirt drop impact of at least 1000 grams when measured according to ASTM D1709 Method A. In additional embodiments, a monolayer inflation film formed from the polyethylene composition and having a thickness of 2 mils has a dirt drop impact of at least 1100 grams, at least 1200 grams, at least 1300 grams, at least 1400 grams, at least 1500 grams, at least 1600 grams, at least 1700 grams, at least 1800 grams, at least 1900 grams, or in some cases at least 2000 grams when measured according to ASTM D1709 Method A.

[0176] According to additional embodiments, the polyethylene composition can have a Dow rheology index of 5 or less, such as 4 or less, 3 or less, 2 or less, or in some cases 1 or less.

[0177] In one or more embodiments, the polyethylene composition of the present disclosure may further include additional components such as one or more additives. Such additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers such as TiO2 or CaCO3, opacifiers, nucleating agents, processing aids, pigments, primary antioxidants, secondary antioxidants, UV stabilizers, antiblocking agents, slip agents, tackifiers, flame retardants, antibacterial agents, odor reducing agents, antifungal agents, and combinations thereof. The polyethylene composition may contain such additives in a combined amount of 0.1 to 10 weight percent based on the weight of the polyethylene composition containing such additives.

[0178] Polymerization To produce the polyethylene composition described herein, any conventional polymerization process may be used. 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.

[0179] Generally, the solution phase polymerization process can be 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 in the range of 115 to 250 °C (e.g., 115 to 210 °C) and a pressure in the range of 300 to 1,000 psi (e.g., 400 to 800 psi). In some embodiments, in a dual reactor, the temperature of the first reactor is in the range of 115 to 190 °C (e.g., 160 to 180 °C) and the temperature of the second reactor is in the range of 150 to 250 °C (e.g., 180 to 220 °C). In other embodiments, in a single reactor, the temperature of the reactor is in the range of 115 to 250 °C (e.g., 115 to 225 °C).

[0180] The residence time in the solution phase polymerization process can be in the range of 2 to 30 minutes (e.g., 5 to 25 minutes). Ethylene, a solvent, hydrogen, one or more catalyst systems, optionally one or more cocatalysts, and optionally one or more comonomers are continuously fed into one or more reactors. Exemplary solvents include, but are not limited to, isoparaffin. For example, such a solvent is commercially available under the name ISOPAR E from ExxonMobil Chemical Co., Houston, Texas. The resulting mixture of the polyethylene composition and the solvent is then removed from the reactor and the polyethylene composition is isolated. The solvent is typically recovered via a solvent recovery unit, such as a heat exchanger and a vapor-liquid separator drum, and then recycled to the polymerization system.

[0181] In some embodiments, the polyethylene composition can be produced by solution polymerization in which ethylene is polymerized in the presence of one or more catalyst systems in a dual reactor system, such as a dual loop reactor system. 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 which ethylene is polymerized in the presence of two catalyst systems in a single reactor system, such as a single loop reactor system. In some embodiments, only ethylene is polymerized.

[0182] Catalyst system Specific embodiments of catalyst systems that can be used in one or more embodiments to produce the polyethylene compositions described herein are now described. It is to be understood that the catalyst systems of the present disclosure may be implemented in different forms and should not be construed as limited to the specific embodiments described in the present disclosure. Rather, the embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art.

[0183] The term "independently selected" means R 1 , R 2 , R 3 , R 4 , and R 5R groups such as may be the same or different (e.g., R 1 , R 2 , R 3 , R 4 , and R 5 are all substituted alkyl, or R 1 and R 2 are substituted alkyl and R 3 may be aryl, etc.) are used herein to indicate. The use of the singular includes the use of the plural and vice versa (e.g., a hexane solvent includes a plurality of hexanes). The named R groups will generally have a structure recognized to correspond to the R groups having that name in the art. These definitions are intended to supplement and illustrate, not exclude, definitions known to those skilled in the art.

[0184] The term "precursor catalyst" 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 precursor catalyst to convert it into a catalytically activated catalyst. As used herein, the terms "cocatalyst" and "activator" are interchangeable terms.

[0185] When used to describe a chemical group containing a specific carbon atom, the bracketed expression in the form of "(C x ~C y )" means that the unsubstituted form of the chemical group has from x to y carbon atoms including 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, a particular chemical group may be substituted by one or more substituents such as R S . The R S substituted version of a chemical group defined using the bracketed "(C x ~C y )" may contain more than y carbon atoms depending on the identity of any group R S . For example, "R SExactly one group R that is phenyl (-C6H5) S substituted (C1-C 40 ) alkyl」 may contain 7 to 46 carbon atoms. Thus, generally, when a chemical group defined using the parentheses "(C x -C y )" is substituted by one or more substituents R S containing carbon atoms, the minimum and maximum total numbers of carbon atoms of the chemical group are determined by adding to both x and y the sum of the carbon atoms derived from all substituents R S containing carbon atoms.

[0186] The term "substituted" means that at least one hydrogen atom (-H) bonded to a carbon atom or heteroatom of the corresponding unsubstituted compound or functional group is replaced by a substituent (e.g., R S ). The term "over-substituted" means that all hydrogen atoms (H) bonded to a carbon atom or heteroatom of the corresponding unsubstituted compound or functional group are replaced by a substituent (e.g., R S ). The term "multi-substituted" means that at least two, but less than all, of the hydrogen atoms bonded to a carbon atom or heteroatom of the corresponding unsubstituted compound or functional group are replaced by a substituent.

[0187] The term "-H" means a hydrogen or hydrogen radical covalently bonded to another atom. "Hydrogen" and "-H" are interchangeable and mean the same thing unless otherwise specified.

[0188] The term "(C1-C 40 ) hydrocarbyl" means a hydrocarbon radical having 1 to 40 carbon atoms, and "(C1-C 40The term "hydrocarbylene" means a hydrocarbon diradical having from 1 to 40 carbon atoms, and each hydrocarbon radical and each hydrocarbon diradical is aromatic or non-aromatic, saturated or unsaturated, straight-chain or branched-chain, cyclic (monocyclic and polycyclic, including fused and non-fused polycyclic having 3 or more carbon atoms in the bicyclic) or acyclic, unsubstituted or substituted by one or more R S and is substituted by.

[0189] In the present disclosure, (C1-C 40 ) hydrocarbyl may be 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 20 ) alkylene. In some embodiments, each of the above (C1-C 40 ) hydrocarbyl groups has a maximum of 20 carbon atoms (i.e., (C1-C 20 ) hydrocarbyl), and in embodiments, has a maximum of 12 carbon atoms.

[0190] The terms "(C1-C 40 ) alkyl" and "(C1-C 18 ) alkyl" each mean a saturated straight-chain or branched hydrocarbon radical having from 1 to 40 carbon atoms or from 1 to 18 carbon atoms, unsubstituted or substituted by one or more R S . Examples of unsubstituted (C1-C 40 ) 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. Substituted (C1-C 40Examples 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.

[0191] "(C6~C 40 The term "aryl" refers to an unsubstituted or substituted (one or more R S means 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.

[0192] "(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 (C3-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.

[0193] (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 20Some 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.

[0194] "(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.

[0195] "(C3~C40 ) The term "cycloalkylene" means a cyclic diradical of 3 to 40 carbon atoms, which is unsubstituted or substituted with one or more Rs S (i.e., the radicals are on the ring atoms).

[0196] The term "heteroatom" refers to an atom other than hydrogen or carbon. Examples of heteroatoms include O, S, S(O), S(O)2, 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 an unsubstituted (C1 - C 18 ) hydrocarbyl or -H. The term "heterohydrocarbon" refers to a molecule or molecular backbone in which one or more carbon atoms are substituted with heteroatoms. The term "(C1 - C 40 ) heterohydrocarbyl" means a heterohydrocarbon radical of 1 to 40 carbon atoms, and the term "(C1 - C 40 ) heterohydrocarbylene" means a heterohydrocarbon diradical of 1 to 40 carbon atoms, and each heterohydrocarbon has one or more heteroatoms. The radicals of heterohydrocarbyl are present on carbon atoms or heteroatoms, and the diradicals of heterohydrocarbylene can be present on (1) one or two carbon atoms, (2) one or two heteroatoms, or (3) one carbon atom and one heteroatom. Each (C1 - C 50 ) heterohydrocarbyl and (C1 - C 50 ) heterohydrocarbylene may be unsubstituted or substituted (by one or more Rs S ), aromatic or non - aromatic, saturated or unsaturated, straight - chain or branched - chain, cyclic (including monocyclic and polycyclic, fused polycyclic and non - fused polycyclic) or acyclic.

[0197] (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 may be.

[0198] The term “(C4-C 40 )heteroaryl” means an unsubstituted or substituted (by one or more R S ) monocyclic, bicyclic, or tricyclic heteroaromatic hydrocarbon radical having a total of 4 to 40 carbon atoms and 1 to 10 heteroatoms, wherein the monocyclic, bicyclic, or tricyclic radical contains 1, 2, or 3 rings, respectively, and the 2 or 3 rings are independently fused or unfused, and at least 1 of the 2 or 3 rings is heteroaromatic. Other heteroaryl groups (e.g., (C4-C12 ) Heteroaryl, etc., (C x ~C y ) heteroaryl in general) has x to y carbon atoms (such as 4 to 12 carbon atoms), and is unsubstituted or has one or more R SIt is defined in a similar manner as being replaced by. The monocyclic heteroaromatic hydrocarbon radical is a 5-membered or 6-membered ring. The 5-membered ring has 5 minus h carbon atoms, where h is the number of heteroatoms and can be 1, 2, or 3, and each heteroatom can be O, S, N, or P. Examples of 5-membered ring 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 6-membered ring has 6 minus h carbon atoms, where h is the number of heteroatoms and can be 1 or 2, and the heteroatom can be N or P. Examples of 6-membered ring heteroaromatic hydrocarbon radicals are pyridin-2-yl, pyrimidin-2-yl, and pyrazin-2-yl. The bicyclic heteroaromatic hydrocarbon radical can be a fused 5,6- or 6,6-ring system. Examples of fused 5,6-ring system bicyclic heteroaromatic hydrocarbon radicals include indol-1-yl and benzimidazol-1-yl. Examples of fused 6,6-ring system bicyclic heteroaromatic hydrocarbon radicals include quinolin-2-yl and isoquinolin-1-yl. The tricyclic heteroaromatic hydrocarbon radical can be a fused 5,6,5-, 5,6,6-, 6,5,6-, or 6,6,6-ring system. 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 acridin-9-yl.

[0199] The aforementioned heteroalkyl is (C1 to C 50It may be a saturated straight-chain or branched-chain radical containing a carbon atom of or less carbon atoms and one or more heteroatoms. Similarly, heteroalkylene may be a saturated straight-chain or branched-chain diradical containing 1 to 50 carbon atoms and one or two or more heteroatoms. Heteroatoms as defined above include 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, SR C , S(O), and S(O)2 may be included, and each of the heteroalkyl group and the heteroalkylene group is unsubstituted or substituted by one or more R S .

[0200] Examples of unsubstituted (C2-C 40 ) heterocycloalkyl include unsubstituted (C2-C 20 ) heterocycloalkyl, unsubstituted (C2-C 10 ) heterocycloalkyl, aziridin-1-yl, oxetan-2-yl, tetrahydrofuran-3-yl, pyrrolidin-1-yl, tetrahydrothiophene-S,S-dioxide-2-yl, morpholin-4-yl, 1,4-dioxan-2-yl, hexahydroazepin-4-yl, 3-oxa-cyclooctyl, 5-thia-cyclononyl, and 2-aza-cyclodecyl.

[0201] The term "halogen atom" or "halogen" means a radical of a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), or an iodine atom (I). The term "halide" means an anionic form of a halogen atom such as fluoride (F - ), chloride (Cl - ), bromide (Br - ), or iodide (I - ).

[0202] The term "saturated" means lacking a carbon-carbon double bond, a carbon-carbon triple bond, and carbon-nitrogen, carbon-phosphorus, and carbon-silicon double bonds (in heteroatom-containing groups). A saturated chemical group has one or more substituents R S When substituted with, one or more double and / or triple bonds may or may not be present in the substituent R S The term "unsaturated" means containing one or more carbon-carbon double bonds, carbon-carbon triple bonds, and carbon-nitrogen, carbon-phosphorus, and carbon-silicon double bonds (in heteroatom-containing groups), provided that any double bonds that may be present in the substituent R S Or, if present, may be present in the (hetero)aromatic ring, do not include any double bonds.

[0203] According to some embodiments, a catalyst system for producing a polyethylene composition comprises a metal-ligand complex according to formula (I).

Chemical formula

[0204] 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 ligand or a bidentate ligand, when n is 2, each X is a monodentate ligand and is the same or different, the metal-ligand complex is electrically neutral as a whole, each Z is independently -O-, -S-, -N(R N )-, or -P(R P )-, L is a (C1-C 40 ) hydrocarbylene or a (C1-C 40 ) heterohydrocarbylene, the (C1-C 40 ) hydrocarbylene has a moiety containing a linker backbone of 1 to 10 carbon atoms that connects two Z groups of formula (I) to which L is attached, or a (C1-C 40) The hetero hydrocarbylene has a moiety containing a 1- to 10-atom linker backbone that connects two Z groups of formula (I), (C1-C 40 ) Each of the 1 to 10 atoms of the 1- to 10-atom linker backbone of the hetero hydrocarbylene is independently a carbon atom or a heteroatom, and each heteroatom is independently O, S, S(O), S(O)2, Si(R C )2, Ge(R C )2, P(R C ), or N(R C ), and each R C is independently a (C1-C 30 ) hydrocarbyl or a (C1-C 30 ) hetero hydrocarbyl, and R 1 and R 8 are independently -H, a (C1-C 40 ) hydrocarbyl, a (C1-C 40 ) hetero hydrocarbyl, -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)-, a halogen, and a radical having the following formula (II), formula (III), or formula (IV) selected from the group consisting of.

Chemical formula

[0205] In formula (II), (III), and (IV), each of R 31~35 , R 41~48 , or R 51~59 is independently a (C1-C 40 ) hydrocarbyl, a (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 at least one of R 1 or R 8 is a radical having formula (II), formula (III), or formula (IV).

[0206] In formula (I), each of R 2~4 , R 5~7 , and R 9~16 is independently (C1-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.

[0207] 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.

[0208] In an exemplary embodiment where 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-, and has the chemical formula C 86 H 128 F2GeO4Zr and has the following structure (V).

Chemical formula

[0209] 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, and has the chemical formula C 107 H 154 N2O4Si2Zr and has the following structure (VI).

Chemical formula

[0210] 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, a system comprising the metal-ligand complex of formula (I) can be catalytically activated by contacting the complex with an activating cocatalyst or by combining the complex with an activating cocatalyst. Suitable activating cocatalysts for use in the present invention include alkylaluminum, polymeric or oligomeric aluminoxane (also known as aluminoxane), 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 foregoing activating cocatalysts and techniques are also contemplated. The term "alkylaluminum" means monoalkylaluminum dihydride or monoalkylaluminum dihalide, dialkylaluminum hydride or dialkylaluminum halide, or trialkylaluminum. Examples of polymeric or oligomeric aluminoxanes include methylaluminoxane, triisobutylaluminum-modified methylaluminoxane, and isobutylaluminoxane.

[0211] Lewis acid activators (cocatalysts) include Group 13 metal compounds containing 1 to 3 (C1-C 20 ) hydrocarbyl substituents as described herein. In one embodiment, the Group 13 metal compound is a tri((C1-C 20 ) hydrocarbyl) substituted aluminum or a tri((C1-C 20 ) hydrocarbyl)-boron compound. In embodiments, the Group 13 metal compound is a tri(hydrocarbyl)-substituted aluminum, a tri((C1-C 20 ) hydrocarbyl)-boron compound, a tri((C1-C 10 ) alkyl) aluminum, a tri((C6-C 18) are aryl) boron compounds and their halogenated (including perhalogenated) derivatives. In a further embodiment, the Group 13 metal compound is tris(fluorosubstituted phenyl)borane, tris(pentafluorophenyl)borane. In some embodiments, the activating cocatalyst is tris((C1-C 20 ) hydrocarbylborate (e.g., trityltetrafluoroborate) or tri((C1-C 20 ) hydrocarbyl)ammonium tetra((C1-C 20 ) hydrocarbyl)borane (e.g., bis(octadecyl)methylammonium tetrakis(pentafluorophenyl)borane). As used herein, the term "ammonium" means a nitrogen cation that is ((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 + , and each (C1-C 20 ) hydrocarbyl may be the same or different if more than one is present.

[0212] Combinations of neutral Lewis acid activators (cocatalysts) include tri((C1-C4)alkyl)aluminum and tri((C6-C 18) A mixture comprising an aryl boron compound, especially a combination with tris(pentafluorophenyl)borane, is exemplified. Embodiments include combinations of such neutral Lewis acid mixtures with polymers or oligomeric alumoxanes, and combinations of a single neutral Lewis acid, especially tris(pentafluorophenyl)borane, with polymers or oligomeric alumoxanes. The molar ratio of (metal-ligand complex):(tris(pentafluoro-phenyl)borane):(alumoxane) [e.g., (Group 4 metal-ligand complex):(tris(pentafluoro-phenyl)borane):(alumoxane)] is from 1:1:1 to 1:10:30, and in embodiments, from 1:1:1.5 to 1:5:10.

[0213] An active catalyst composition can be formed by activating a catalyst system comprising a metal-ligand complex of formula (I) and combining one or more cocatalysts, such as cation-forming cocatalysts, strong Lewis acids, or combinations thereof. Suitable activating cocatalysts include polymeric or oligomeric aluminoxanes, especially methylaluminoxane, and inert, compatible, non-coordinating, ion-forming compounds. Exemplary suitable cocatalysts include modified methylaluminoxane (MMAO), bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate(1 - ) amine, and combinations thereof, but are not limited thereto.

[0214] In some embodiments, one or more of the foregoing activating cocatalysts are used in combination with each other. Particularly preferred combinations are tri((C1-C4)hydrocarbyl)aluminum, tri((C1-C4)hydrocarbyl)borane, or a mixture of ammonium borate and an oligomeric or polymeric aluminoxane compound. The ratio of the total molar amount of one or more metal-ligand complexes of formula (I) to the total molar amount of one or more activating cocatalysts is from 1:10,000 to 100:1. In some embodiments, this ratio is at least 1:5000, in some embodiments at least 1:1000, and 10:1 or less, and in still some embodiments, 1:1 or less. When using an aluminoxane alone as the activating cocatalyst, preferably, the molar amount of the aluminoxane used is at least 100 times the molar amount of the metal-ligand complex of formula (I). When using tris(pentafluorophenyl)borane alone as the activating cocatalyst, in some embodiments, the molar amount of tris(pentafluorophenyl)borane used relative to the total molar amount 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).

[0215] Test method The test method includes the following.

[0216] Melt index The melt indices I2 (or I2) and I 10 (or I10) of the polymer sample are measured according to ASTM D-1238 (Method B) at 190 °C and under loads of 2.16 kg and 10 kg, respectively. These values are reported in g / 10 min. The fractions of the polymer sample are measured by collecting the product polymer from the reactor that produces that particular fraction or portion of the polymer composition. For example, the first polyethylene fraction can be collected from the reactor that produces the lower density and higher molecular weight components of the polymer composition. Before melt index measurement, the polymer solution is dried under vacuum.

[0217] Density Samples for density measurement were prepared according to ASTM D4703. Measurements were taken according to ASTM D792, Method B within one hour of sample pressurization.

[0218] ASTM D1709 Dart Impact The film dart impact test determines the energy at which the impact of freely falling darts causes breakage of the plastic film under defined conditions. The test result is expressed as the energy of the projectile falling from a defined height that will cause breakage of 50% of the test specimens being tested, which is the weight of this projectile.

[0219] After the film was produced, the film was conditioned at 23 °C (+ / - 2 °C) and 50% R.H. (+ / - 5) for at least 40 hours according to ASTM standards. The standard test conditions are 23 °C (+ / - 2 °C) and 50% R.H. (+ / - 5) according to ASTM standards.

[0220] Test results are reported by Method A using a dirt head of 1.5 inches in diameter and a drop height of 26 inches. The thickness of the sample is measured at the center of the sample and then the sample is fixed in an annular test specimen holder with an inner diameter of 5 inches. The dirt is loaded above the center of the sample and released by either a pneumatic or electromagnetic mechanism.

[0221] The test is carried out according to the "staircase" method. If the sample fails, a new sample is tested by reducing the weight of the dirt by a known fixed amount. If the sample does not fail, a new sample is tested by increasing the weight of the dirt by a known amount. After 20 test pieces have been tested, the number of failures is determined. If this number is 10, the test is completed. If this number is less than 10, the test is continued until 10 failures are recorded. If this number is greater than 10, the test is continued until the total number of non-failures reaches 10. The dirt drop strength is determined from these data, expressed in grams as a type A dirt drop impact according to ASTM D1709. All samples analyzed were 2 mils thick.

[0222] Instrumented dirt impact The instrumented dirt impact method is measured on plastic film test pieces using an Instron CEAST 9350 impact tester according to ASTM D7192. The test is carried out using a 12.7 mm diameter tap with a hemispherical head and a 75 mm diameter clamp assembly with a rubber-faced grip. The instrument is equipped with an environmental chamber for testing at low or high temperatures. The typical test piece size is 125 mm × 125 mm. The standard test speed is 200 m / min. The film thickness is 2 mils.

[0223] Creep zero shear viscosity measurement method The zero shear viscosity is obtained by a creep test performed on an AR-G2 stress control rheometer (TA Instruments; New Castle, Del) using parallel plates with a diameter of 25 mm at 190 °C. Before zeroing the mounting fixture, the rheometer oven is set to the test temperature for at least 30 minutes. At that test temperature, a disk of the compression-molded sample is inserted between the plates and allowed to equilibrate for 5 minutes. Then, the upper plate is lowered 50 μm above the desired test gap (1.5 mm). Any excess material is trimmed off and the upper plate is lowered to the desired gap. The measurement is carried out under a nitrogen purge at a flow rate of 5 L / min. The default creep time is set to 2 hours.

[0224] To ensure that the shear rate in the steady state has a sufficiently low value such that it is only in the Newtonian region, a constant low shear stress of 20 Pa is applied to all of the samples. The obtained steady state shear rate is between 10 -3 ~10 -4 s -1 for the samples in this test. The steady state is determined by taking a linear regression for all data within the last 10% time window of the 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, it is considered that the steady state has been reached, and then the creep test is stopped. In all cases of this test, the slope meets the criterion within 2 hours. The steady state shear rate is determined from the slope of the linear regression of all data points in the last 10% time window of the plot of ε versus t (where ε is the strain). The zero shear viscosity is determined from the ratio of the applied stress to the steady state shear rate.

[0225] To determine whether the sample is deteriorating during the creep test, a small amplitude oscillatory shear test is performed on the same sample before and after the creep test at 0.1 to 100 rad / s. The complex viscosity values of the two tests are compared. If the difference in the viscosity values at 0.1 rad / s is greater than 5%, it is considered that the sample has deteriorated during the creep test, and the results are discarded.

[0226] Gel Permeation Chromatography (GPC) The chromatography system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5). The autosampler oven compartment was set at 160 °C and the column compartment was set at 150 °C. The columns used were four Agilent "Mixed A" 30 cm 20 micron linear mixed-bed columns and a 20 um pre-column. The chromatography solvent used was 1,2,4-trichlorobenzene, which contained 200 ppm of butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume used was 200 microliters and the flow rate was 1.0 milliliter / minute.

[0227] The GPC column set was calibrated using 21 narrow molecular weight distribution polystyrene standards with molecular weights in the range of 580 to 8,400,000 and arranged in six "cocktail" mixtures with at least a 10-fold interval between individual molecular weights. The standards were purchased from Agilent Technologies. The polystyrene standards were prepared at 0.025 grams in 50 milliliters of solvent for molecular weights above 1,000,000 and 0.05 grams in 50 milliliters of solvent for molecular weights below 1,000,000. The polystyrene standards were dissolved at 80 °C for 30 minutes with gentle stirring. 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)).

Equation

[0228] A fifth-degree polynomial was used to fit each polyethylene equivalent calibration point. Minor adjustments (about 0.375 - 0.445) were made to A to correct the column resolution and band spreading effects so that the linear homopolymer polyethylene standard would yield 120,000 Mw.

[0229] The total plate count of the GPC column set was performed with decane (prepared at 0.04 g in 50 milliliters of TCB and dissolved for 20 minutes with gentle stirring). The plate count (Equation 2) and symmetry (Equation 3) were measured with a 200 microliter injection according to the following equations.

Number

Number

[0230] Samples were prepared in a semi-automatic mode using PolymerChar "Instrument Control" software, with a target sample weight of 2 mg / ml. Solvent (containing 200 ppm of BHT) was added to septum-capped vials pre-nitrogen sparged via a PolymerChar high-temperature autosampler. Samples were dissolved at 160 degrees Celsius for 2 hours while shaking at "low speed".

[0231] Mn(GPC) , Mw (GPC) , and Mz (GPC) were calculated using PolymerChar GPCOne (trademark) software, an IR chromatogram obtained by subtracting the baseline at each equally spaced data collection point (i), and polyethylene equivalent molecular weights obtained from a narrow standard calibration curve at point (i) of Equation 1, using the internal IR5 detector (measurement channel) of a PolymerChar GPC-IR chromatograph according to Equations 4-6, based on the GPC results.

Number

Number

Number

[0232] To monitor the deviation over time, a flow marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. This flow marker (FM) was used to linearly calibrate the pump flow rate (apparent flow rate) of each sample by matching the RV of each decane peak (RV(FM sample)) in the sample with that of the decane peak within a narrow standard calibration (RV(FM calibrated)). Thus, any change in the time of the decane marker peak is presumed to be related to a linear shift in the flow rate (effective flow rate) over the course of the run. To facilitate the highest accuracy in RV measurement of the flow marker peak, a least-squares fitting routine was used to fit the peak of the flow marker concentration chromatogram to a quadratic equation. Next, the first derivative of the quadratic equation was used to determine the true peak position. After calibrating the system based on the peak of the flow marker, the effective flow rate (relative to the narrow standard calibration) is calculated as shown in Equation 7. The processing of the flow marker peak was performed by PolymerChar GPCOne (trademark) software. For the allowable flow correction, the effective flow rate should be within + / - 0.5% of the apparent flow rate. Effective flow rate = Apparent flow rate × (RV(FM calibrated) / RV(FM sample)) (EQ7)

[0233] Improved comonomer content analysis method (iCCD) The improved comonomer content analysis method (iCCD) was developed in 2015 (Cong and Parrott et al., WO2017 / 040127A1). The iCCD test was carried out using a crystallization elution fractionation instrument (CEF) (PolymerChar, Spain) equipped with an IR-5 detector (PolymerChar, Spain) and a dual-angle light scattering detector model 2040 (Precision Detectors, now Agilent Technologies). Immediately before the IR-5 detector in the detector oven, a guard column filled with 20 - 27 micron glass (MoSCi Corporation, USA) in 5 cm or 10 cm (length) × 1 / 4 inch (ID) stainless steel was installed. Orthodichlorobenzene (ODCB, 99% anhydrous grade or technical grade) was used. Silica gel 40 (particle size 0.2 - 0.5 mm, catalog number 10181-3) was obtained from EMD Chemicals (which can be used for drying the ODCB solvent previously). The CEF instrument was equipped with an autosampler with N2 purge capability. Before use, dry nitrogen (N2) was sprayed into the ODCB for 1 hour. Sample preparation was carried out using the autosampler at 4 mg / ml while shaking at 160 °C for 1 hour (unless otherwise specified). The injection volume was 300 μl. The temperature profile of iCCD was crystallization from 105 °C to 30 °C at 3 °C / min, thermal equilibrium at 30 °C for 2 minutes (including setting the soluble fraction elution time 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 was collected at 1 data point / second.

[0234] The iCCD column was packed with nickel particles coated with gold (Bright 7GNM8-NiS, Nippon Chemical Industrial Co.) in a 15 cm (length) × 1 / 4 inch (ID) stainless steel tube. Column packing and conditioning were performed using the slurry method according to the reference (Cong, R, Parrott, A., Hollis, C., Cheatham, M. WO2017 / 040127A1). The final pressure including packing the TCB slurry was 150 bar.

[0235] Calibrate the column temperature using a mixture of linear homopolymer polyethylene (comonomer content zero, melt index (I2) 1.0, polydispersity M w / M n about 2.6 by conventional gel permeation chromatography, 1.0 mg / ml) and eicosane (2 mg / ml). The iCCD temperature calibration consisted of the following four steps. (1) Calculate the delay volume defined as subtracting 30.00 °C from the temperature offset between the measured peak elution temperatures of eicosane, (2) Subtract the temperature offset of the elution temperature from the iCCD raw temperature data. It should be noted that this temperature offset is a function of experimental conditions such as elution temperature and elution flow rate, (3) Create a linear calibration straight line that converts the elution temperature over the range of 30.00 °C to 140.00 °C such that the linear homopolymer polyethylene reference has a peak temperature of 101.0 °C and eicosane has a peak temperature of 30.0 °C, (4) For the soluble fraction 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).

[0236] The comonomer content versus the elution temperature of the iCCD was constructed by using 12 reference materials (ethylene homopolymers and ethylene-octene random copolymers made with single-site metallocene catalysts, having a weight-average molecular weight of ethylene equivalent in the range of 35,000 to 128,000). All of these reference materials were analyzed at 4 mg / mL in the same manner as previously specified. The reported elution peak temperatures were linearly fitted to the linear equation y = -6.3515x + 101.00, where y represents the elution temperature of the iCCD and x represents the octene mol%, and R 2 was 0.978.

[0237] The molecular weight of the polymer and the molecular weights of the polymer fractions were determined directly from the LS detector (90-degree angle) and the concentration detector (IR-5) according to the Rayleigh-Gans-Debye approximation (Striegel and Yau, Modern Size Exclusion Liquid Chromatography, pages 242 and 263), by assuming a form factor of 1 and all virial coefficients to be zero. An integration window was set to integrate all chromatograms at elution temperatures in the range of 23.0 to 120 °C (temperature calibration was specified above).

[0238] The calculation of the molecular weight (Mw) from the iCCD involves the following four steps.

[0239] (1) Measuring the detector offset. The offset is defined as the geometric volume offset between the LS detector and the concentration detector. This is calculated as the difference in the elution volume (mL) of the polymer peak between the concentration detector and the LS chromatogram. This is converted to a temperature offset by using the elution heat rate and the elution flow rate. Linear high-density polyethylene (comonomer content zero, melt index (I2) 1.0, polydispersity M w / M n of approximately 2.6 by conventional gel permeation chromatography) is used. The same experimental conditions as the normal iCCD method described above are used, except for parameters such as crystallization from 140 °C to 137 °C at 10 °C / min, a 1-minute heat equilibrium as the soluble fraction elution time at 137 °C, a 7-minute soluble fraction (SF) time, and elution from 137 °C to 142 °C at 3 °C / min. The flow rate during crystallization is 0.0 ml / min. The flow rate during elution is 0.80 ml / min. The sample concentration is 1.0 mg / ml.

[0240] (2) Shifting each LS data point of the LS chromatogram to correct for the detector offset before integration.

[0241] (3) The LS and concentration chromatograms with the baseline subtracted are integrated over the entire elution temperature range of step (1). The MW detector constant is calculated using a known MW HDPE sample in the range of 100,000 - 140,000 Mw and the area ratio of the LS and concentration integration signals.

[0242] (4) The Mw of the polymer is calculated using the ratio of an integrated light scattering detector (at a 90-degree angle) to a concentration detector and the MW detector constant.

[0243] The calculation of the half-width is defined as the temperature difference between the front temperature and the rear temperature at half of the maximum peak height. The front temperature at half of the maximum peak is searched forward from 35.0 °C, and the rear temperature at half of the maximum peak is searched backward from 119.0 °C.

[0244] Zero shear viscosity ratio (ZSVR) 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 the equivalent weight average molecular weight (Mw-gpc), according to the following equations (EQ) 8 and 9.

Number

Number

[0245] The ZSV value is obtained from a creep test at 190 °C by the method described above. The Mw-gpc value is determined by the conventional GPC method (Equation 5 in the description of the conventional GPC method). The correlation between the ZSV of linear polyethylene and its Mw-gpc was established based on a series of linear polyethylene reference materials. An explanation of the ZSV-Mw relationship can be found in ANTEC's abstract: Karjala, Teresa P., Sammler, Robert L., Mangnus, Marc A., Hazlitt, Lonnie G., Johnson, Mark S., Hagen, Charles M. Jr., Huang, Joe W.L., Reichek, Kenneth N., “Detection of low levels of long-chain branching in polyolefins”, Annual Technical Conference-Society of Plastics Engineers (2008), 66th 887-891.

[0246] MD tear MD tear is measured in accordance with ASTM D-1922. The force in grams required to propagate a tear across a film specimen is measured using an Elmendorf tear tester. Acting by gravity, the pendulum oscillates in an arc and tears the specimen from a pre-cut slit. The tear is propagated in a cross direction. The sample is conditioned for a minimum of 40 hours at the temperature prior to testing.

[0247] Dynamic rheological analysis To characterize the rheological behavior of substantially linear ethylene polymers, S Lai and G.W. Knight (ANTEC’93 Proceedings, Insite(TM) Technology Polyolefins(ITP)-New Rules in the Structure / Rheology Relationship of Ethylene &-01efin Copolymers, New Orleans, La., May 1993) introduced a new rheological measurement, the Dow Rheology Index (DRI), which represents the “normalized relaxation time as a result of long chain branching” of the polymer. S. Lai et al. (ANTEC ’94, Dow Rheology Index(DRI) for Insite(TM) Technology Polyolefins(ITP): Unique structure-Processing Relationships, pp.1814-1815) defined the DRI as the degree to which the rheology of ethylene-octene copolymers known as ITP (Dow's Insite technology polyolefins), which incorporate long chain branches into the polymer backbone, deviates from the rheology of conventional linear homogeneous polyolefins that are reported to have no long chain branches (LCB) according to the following normalized equation. DRI = [3650000 X (τ0 / η0)-1] / 10 (EQ10) Where τ0 is the relaxation time characteristic of this material and is the zero shear rate complex viscosity of this material. The DRI is calculated by the least squares fit of the rheology curve (dynamic complex viscosity η*(ω) vs. applied frequency (ω), e.g., 0.01~100 rad / sec) according to the following generalized cross equation, as described in U.S. Patent No. 6,114,486. η*(ω) = η0 / [1+(ω·τ0) n (EQ11) Where n is the power law index of the material, and η*(ω) and ω are the measured complex viscosity and applied frequency data, respectively.

[0248] Dynamic rheological measurements are performed on a dynamic rheometer equipped with 25 mm diameter parallel plates (e.g., TA Instruments ARES rheometer) in dynamic mode under an inert atmosphere according to ASTM D4440. In all experiments, the rheometer is thermally stabilized at 190 °C for at least 30 minutes, then properly stabilized (by antioxidants), and a compression molded sample is inserted between the parallel plates. Next, the plates are closed with a positive normal force recorded on the meter to ensure good contact. After about 5 minutes at 190 °C, the plates are lightly compressed and excess polymer around the plates is trimmed. Leave for an additional 10 minutes until the thermal stability and normal force return to zero. That is, all measurements are performed after the sample has been equilibrated at 190 °C for about 15 minutes and are performed under a complete nitrogen blanket.

[0249] Two strain sweep (SS) experiments are first performed at 190 °C over the full frequency range (e.g., 0.01 - 100 rad / sec) to determine the linear viscoelastic strain that produces a torque signal greater than 10% of the lower scale of the transducer. The first SS experiment is performed at a low applied frequency of 0.1 rad / sec. This test is used to determine the sensitivity of the torque at low frequencies. The second SS experiment is performed at a high applied frequency of 100 rad / sec. This is to ensure that the selected applied strain fits well within the linear viscoelastic region of the polymer so that the oscillatory rheological measurements do not cause a structural change in the polymer during the test. Additionally, a time sweep (TS) experiment is performed at the selected strain (determined by the SS experiment) at a low applied frequency of 0.1 rad / sec to confirm the stability of the sample during the test.

[0250] Storage (or elastic) Elastic modulus , loss (or viscous) Elastic modulus (G”), complex Elastic modulus (G*), complex viscosity (η*) and tanδ (loss Elastic modulus and storage Elastic modulus and the ratio G’VG’) values were obtained as a function of frequency (ω) at a given temperature (e.g., 190 °C).

[0251] ASTM D1922 MD (Machine Direction) and CD (Cross Direction) Elmendorf Tear Type B The Elmendorf tear test uses an Elmendorf type tear tester to determine the average force to propagate a tear through a specified length of plastic film or non-rigid sheet after the tear has been initiated.

[0252] After generating a film from the sample to be tested, the film was conditioned at 23 °C (+ / - 2 °C) and 50% R.H. (+ / - 5) for at least 40 hours according to ASTM standards. The standard test conditions were 23 °C (+ / - 2 °C) and 50% R.H. (+ / - 5) according to ASTM standards.

[0253] The force in grams required to propagate a tear in the film or sheet specimen was measured using a precisely calibrated pendulum device. In the test, the pendulum acted under gravity and swung in an arc to tear the specimen from a pre-cut slit. One side of the specimen was held by the pendulum and the other side was held by a fixed member. The energy loss by the pendulum was indicated by a pointer or an electronic scale. The scale reading is a function of the force required to tear the specimen.

[0254] The shape of the sample specimen used in the Elmendorf tear test was a "constant radius shape" as defined in ASTM D1922. The test was typically performed on specimens cut from both the MD and CD directions of the film. Before the test, the thickness of the film specimen was measured at the center of the sample. A total of 15 specimens were tested for each film direction and the average tear strength and average thickness were reported. The average tear strength was normalized with respect to the average thickness.

[0255] ASTM D882 MD and CD, 1% and 2% Secant Elastic modulus Film MD (Machine Direction) and CD (Cross Direction) Secant Elastic modulus was determined according to ASTM D882. The reported secant Elastic modulusThe value was the average of five measurements.

[0256] Puncture strength The puncture test determines the film's resistance to probe penetration at standard low speed and a single test speed. The puncture test method is based on ASTM D5748. After film formation, the film was conditioned at 23 °C (+ / - 2 °C) and 50% R.H. (+ / - 5) for at least 40 hours according to ASTM standards. The standard test conditions are 23 °C (+ / - 2 °C) and 50% R.H. (+ / - 5) according to ASTM standards. Puncture was measured with a tensile testing machine. Square specimens were cut from the sheet to a size of "6 inches × 6 inches". The specimens were fixed in a circular specimen holder with a "4-inch diameter", and the puncture probe was pushed into the center of the fixed film at a crosshead speed of 10 inches / min. The internal test method complies with ASTM D5748 with one modification. This method differs from the method of ASTM D5748 in that the probe used was a "0.5-inch diameter" ground steel ball on a "0.25-inch" support instead of the 0.75-inch diameter pear-shaped probe defined in D5748.

[0257] To prevent damage to the test fixture, there was a maximum travel length of "7.7 inches". There was no gauge length, and before the test, the probe was brought as close as possible to the specimen without touching it. A single thickness measurement was taken at the center of the specimen. For each specimen, the maximum force, force at break, penetration distance, and energy to break were determined. A total of five specimens were tested to determine the average puncture value. The puncture probe was cleaned with "Kimwipe" after each specimen.

Example

[0258] The following examples illustrate the features of the present disclosure and are not intended to limit the scope of the present disclosure. In the following experiments, the performance of the multilayer film embodiments described herein was analyzed.

[0259] Example 1A: Preparation of Polyethylene Compositions 1 - 5 The polyethylene compositions 1 to 5 described in accordance with one or more of the modes for carrying out the invention were prepared by the method described below and using the catalyst and reactor described below.

[0260] Before introducing into the reaction environment, all raw materials (monomers and comonomers) and process solvents (high-purity isoparaffin solvents with a narrow boiling range, Isopar-E) are purified with molecular sieves. Hydrogen is supplied pressurized as a high-purity grade and is not further purified. The reactor monomer feed stream is pressurized to above the reaction pressure via a mechanical compressor. The supply of solvents and comonomers is pressurized to above the reaction pressure via pumps. The individual catalyst components are manually batch diluted with the purified solvent and pressurized to above the reaction pressure. All reaction feed streams are measured using mass flow meters and independently controlled by a valve control system automated by a computer.

[0261] As shown in Figure 3, two reactor systems are used in a series configuration. Each continuous solution polymerization reactor consists of a liquid-filled, non-insulated, isothermal circulation loop reactor that mimics a continuous stirred tank reactor (CSTR) for heat removal. Independent control of all fresh solvent, monomer, comonomer, hydrogen, and catalyst component feeds is possible. The fresh feed streams to each reactor (solvent, monomer, comonomer, and hydrogen) are temperature-controlled by passing the feed streams through a heat exchanger to maintain a single solution phase. The fresh feeds to each polymerization reactor are injected into the reactor at two locations with approximately equal reactor volumes between each injection location. The fresh feeds are controlled such that each injector receives half of the fresh feed mass flow rate. The catalyst components are injected into the polymerization reactor through injection needles. The main catalyst component feed is computer-controlled to maintain monomer conversion in each reactor at a specific target. The cocatalyst component is supplied based on a calculated specific molar ratio to the main catalyst component. Immediately after the injection location of each reactor feed, the feed stream is mixed with the contents of the circulation polymerization reactor having a static mixing element. The contents of each reactor are continuously circulated through a heat exchanger that serves to remove most of the heat of reaction, with the temperature on the coolant side serving to maintain an isothermal reaction environment at a specific temperature. The circulation around each reactor loop is provided by a pump.

[0262] In the double series reactor configuration, the effluent from the first polymerization reactor (containing solvent, monomer, comonomer, hydrogen, catalyst components, polymer) exits the first reactor loop and is added to the second reactor loop.

[0263] The second reactor effluent enters a zone where the effluent is deactivated by the addition and reaction with a suitable reagent (water). At this same reactor outlet site, other additives are added for polymer stabilization (typical antioxidants suitable for stabilization during extrusion and film manufacture such as octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, tetrakis(methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate))methane, and tris(2,4-di-tert-butyl-phenyl)phosphite).

[0264] Following the deactivation of the catalyst and the addition of the additive, 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 removed from the system. Most of the solvent and unreacted comonomer are recycled to the reactor after passing through the purification system. A small amount of solvent and comonomer is purged from the process.

[0265] The reactor stream feed data flow corresponding to the values in Table 1 used to generate the examples is illustrated schematically in Figure 3. The data is presented such that the complexity of the solvent recycle system is considered and the reaction system can be more easily handled as a flow-through flow diagram. Table 1B shows the catalysts referred to in Table 1A.

Table 1-1

Table 1-2

Table 2

[0266] Example 1B: Preparation of Polyethylene Composition 6 Polyethylene Composition 6, described in accordance with one or more of the modes for carrying out the invention, was prepared by the methods described below and using the catalysts and reactors described below.

[0267] Before introducing into the reaction environment, all raw materials (monomers and comonomers) as well as the process solvent (high-purity isoparaffin solvent with a narrow boiling point range, Isopar-E) are purified with molecular sieves. Hydrogen is supplied pressurized as a high-purity grade and is not further purified. The reactor monomer feed stream is pressurized via a mechanical compressor beyond the reaction pressure. The supply of the solvent and comonomer is pressurized via a pump beyond the reaction pressure. The individual catalyst components are manually batch-diluted with the purified solvent and pressurized beyond the reaction pressure. All reaction feed streams are measured using mass flow meters and independently controlled by a computer-automated valve control system.

[0268] Two reactor systems are used in a parallel configuration. Each continuous solution polymerization reactor consists of a liquid-filled, non-adiabatic, isothermal circulation loop reactor that mimics a continuous stirred tank reactor (CSTR) for heat removal. Independent control of all fresh solvent, monomer, comonomer, hydrogen, and catalyst component feeds is possible. The fresh feed streams to each reactor (solvent, monomer, comonomer, and hydrogen) are temperature-controlled to maintain a single solution phase by passing the feed streams through a heat exchanger. The fresh feed to each polymerization reactor is injected into the reactor at two locations with approximately equal reactor volumes between each injection location. The fresh feed is controlled such that each injector receives half of the fresh feed mass flow rate. The catalyst components are injected into the polymerization reactor through specially designed injection needles. The main catalyst component feed is computer-controlled to maintain a specific monomer conversion in each reactor for a specific target. The cocatalyst component is supplied based on a calculated specific molar ratio to the main catalyst component. Immediately after the injection location of each reactor feed, the feed stream is mixed with the contents of the circulating polymerization reactor having static mixing elements. The contents of each reactor are continuously circulated through a heat exchanger that serves to remove most of the reaction heat, with the temperature on the coolant side serving to maintain an isothermal reaction environment at a specific temperature. The circulation around each reactor loop is provided by a pump.

[0269] The effluent streams from the first and second polymerization reactors are combined prior to any additional processing. This final composite reactor effluent enters a zone where the effluent is deactivated by the addition of a suitable reagent (water) and reaction therewith. At this same reactor outlet location, other additives are added for polymer stabilization (typical antioxidants suitable for stabilization during extrusion and inflation film manufacture such as octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, tetrakis(methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate))methane, and tris(2,4-di-tert-butyl-phenyl)phosphite).

[0270] 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 removed from the system. Most of the solvent and unreacted comonomer are recycled to the reactor after passing through a purification system. A small amount of solvent and comonomer are purged from the process.

[0271] The reactor stream feed data flow corresponding to the values in Table 2A, used to generate the examples, is illustrated schematically in FIG. 4. The data is presented such that the complexity of the solvent recycle system is considered and the reaction system can be more easily handled as a through-flow diagram. Table 1B shows the catalyst referred to in Table 2A of Example 1A.

Table 3

[0272] Example 2: Comparative Compositions A - J Comparative compositions A - C were prepared by the methods described below in this specification. Comparative compositions D - F are generally bimodal polyethylene compositions prepared using the catalyst system and process provided for preparing Invention Composition 1 in PCT Publication No. 2015 / 200743. Comparative compositions G - J are commercially available polyethylene compositions. Table 3 shows the commercially available polyethylene compositions of Comparative compositions G - J.

Table 4

[0273] The preparation of Comparative compositions A - C is described as follows. Before introduction into the reaction environment, all raw materials (monomers and comonomers) as well as the process solvent (a high - purity isoparaffin solvent with a narrow boiling range, Isopar - E) are purified with molecular sieves. Hydrogen is supplied pressurized as a high - purity grade and is not further purified. The reactor monomer feed stream is pressurized via a mechanical compressor to above the reaction pressure. The solvent and comonomer feeds are pressurized via pumps to above the reaction pressure. The individual catalyst components are manually batch - diluted with the purified solvent and pressurized to above the reaction pressure. All reaction feed streams are measured using mass flow meters and independently controlled by a computer - automated valve control system.

[0274] Two reactor systems are used in a series configuration. Each continuous solution polymerization reactor consists of a liquid-filled, non-insulated, isothermal circulation loop reactor that mimics a continuous stirred tank reactor (CSTR) for heat removal. Independent control of all fresh solvent, monomer, comonomer, hydrogen, and catalyst component feeds is possible. The fresh feed stream to each reactor (solvent, monomer, comonomer, and hydrogen) is temperature-controlled to maintain a single solution phase by passing the feed stream through a heat exchanger. The fresh feed to each polymerization reactor is injected into the reactor at two locations with approximately equal reactor volumes between each injection location. The fresh feed is controlled such that each injector receives half of the fresh feed mass flow rate. The catalyst component is injected into the polymerization reactor through an injection needle. The main catalyst component feed is computer-controlled to maintain monomer conversion in each reactor at a specific target. The cocatalyst component is supplied based on a calculated specific molar ratio to the main catalyst component. Immediately after the injection location of each reactor feed, the feed stream is mixed with the contents of the circulation polymerization reactor having 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, with the coolant side temperature serving to maintain an isothermal reaction environment at a specific temperature. The circulation around each reactor loop is provided by a pump.

[0275] In a double series reactor configuration, the effluent from the first polymerization reactor (containing solvent, monomer, comonomer, hydrogen, catalyst component, polymer) exits the first reactor loop and is added to the second reactor loop.

[0276] The second reactor effluent enters a zone where the effluent is deactivated by the addition and reaction with a suitable reagent (water). At this same reactor outlet site, other additives are added for polymer stabilization (typical antioxidants suitable for stabilization during extrusion and film production such as octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, tetrakis(methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate))methane, and tris(2,4-di-tert-butyl-phenyl)phosphite).

[0277] Following the deactivation of the catalyst and the addition of the additive, 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 removed from the system. Most of the solvent and unreacted comonomer are recycled to the reactor after passing through the purification system. A small amount of solvent and comonomer is purged from the process.

[0278] The reactor stream feed data flow corresponding to the values in Table 4A, used to generate the examples, is illustrated schematically in Figure 3. The data is presented taking into account the complexity of the solvent recycle system and such that the reaction system can be more easily handled as a flow-through flow diagram. Table 1B shows the catalysts and cocatalysts shown in Table 4A. [Table 5]

[0279] Example 3: Analysis of Polyethylene Samples The polyethylene compositions 1 - 6 of Examples 1A and 1B, the comparative polyethylene compositions A - C of Example 2, and the commercially available comparative polyethylene samples D - J of Example 2 were analyzed by iCCD. The iCCD data for polyethylene composition 5 is shown in Figure 2. Additional data generated from the iCCD tests of all samples are shown in Tables 5A and 5B. Specifically, Tables 5A and 5B include the analysis of the iCCD data including the areas of the first and second polyethylene fractions (45 - 87 °C and 95 - 120 °C). Additional data for each example composition, such as bulk density, dirt intensity (Method A), melt index, weight average molecular weight of the second PE fraction, etc., are also provided. These properties are based on single-layer inflation films made entirely from each polyethylene sample.

[0280] To conduct dirt tests and other tests based on formed films, a 2-mil inflation film was formed using a polyethylene sample. Specifically, the single-layer inflation film was produced via an Egan Davis Standard extruder equipped with a 3.5-inch semi-grooved barrel, a 30 / 1 L / D ratio, a barrier screw, and an Alpine air ring. The extrusion line has an 8-inch die with internal bubble cooling. The extrusion line also has a film thickness gauge scanner. The manufacturing conditions of the film were such that the film thickness was maintained at 2 mils (0.001 in or 0.0254 mm), the blow-up ratio (BUR) was 2.5, the die gap was 70 mils, and the frost line height (FLH) was 37 inches. The output speed was constant at 260 lbs / hr.

Table 6

Table 7

[0281] The results show that none of the comparative example compositions exhibit equivalent dirt strength at an overall density of at least 0.924 g / cm 3 For example, some of the comparative examples have high dirt strength, but these samples have much lower densities. The high-density comparative samples (e.g., 0.924 g / cm 3 ~0.936 g / cm 3 ) exhibit much lower dirt strength (e.g., less than 1000 grams).

[0282] Furthermore, some of the compositions of Example 1 had Dow rheology indices less than 10, such as 3.5, 4.6, and 5.5.

[0283] Example 4: Instrumented Dirt Impact Strength at Low Temperatures The instrumented dart impact strength was measured on some of the polyethylene compositions of Example 1 and some of the comparative polyethylene compositions of Example 2 at relatively low temperatures. The dart tests were performed on single-layer films prepared by the same method as disclosed in Example 3. Table 6 shows the observed instrumented dart strengths indicating the instrumented dart impact strength at 1 °C, -10 °C, and -20 °C. The data indicate that at low temperatures such as -20 °C, the dart strength is significantly improved in the compositions of Example 1 compared to the comparative examples. Thus, the polyethylene compositions of the present disclosure may have improved toughness when used in single-layer or multilayer films for frozen food packages or other situations where low temperatures are common.

Table 8

[0284] Example 5: Preparation of Comparative Films 5-A, 5-B, 5-C, 5-D and Films 5-1, 5-2, 5-3, 5-4 In this example, three comparative films and six films according to embodiments of the present disclosure were prepared, each having an overall thickness of 80 μm. Tables 7-15 provide the materials for generating each film sample of Example 5.

[0285] As shown in Table 7, Comparative Film 5-A contained a polyamide distribution of about 6% based on the total thickness of Comparative Film 5-A. The polyamide was included in Layers D and F of Comparative Film 5-A.

Table 9

[0286] As shown in Table 8, Comparative Film 5-B contained a polyamide distribution of about 15% based on the total thickness of Comparative Film 5-B. The polyamide was included in Layers D and F of Comparative Film 5-B.

Table 10

[0287] As shown in Table 9, the comparative film 5-C did not contain polyamide and contained about 43.2% of the comparative polyethylene composition E based on the total thickness of the comparative film 5-C. In the comparative film 5-C, the comparative polyethylene composition E was contained in layers B, C, G, and H.

Table 11

[0288] As shown in Table 10, the comparative film 5-D did not contain polyamide and contained about 43.2% of the comparative polyethylene composition B based on the total thickness of the comparative film 5-D. In the comparative film 5-D, the comparative polyethylene composition B was contained in layers B, C, G, and H.

Table 12

[0289] As shown in Table 11, the film 5-1 did not contain polyamide and contained about 43.2% of the polyethylene composition 2 based on the total thickness of the film 5-1. In the film 5-1, the polyethylene composition 2 was contained in layers B, C, G, and H.

Table 13

[0290] As shown in Table 12, the film 5-2 did not contain polyamide. The film 5-2 contained about 22% of the comparative polyethylene composition B and 21% of the polyethylene composition 2 based on the total thickness of the film 5-2. In the film 5-2, the comparative polyethylene composition B was contained in layers B and H, and the polyethylene composition 2 was contained in layers C and G.

Table 14

[0291] As shown in Table 13, Film 5-3 did not contain polyamide. Film 5-3 contained approximately 22% of Comparative Polyethylene Composition B and 18% of Polyethylene Composition 2 based on the total thickness of Film 5-3. In Film 5-3, Comparative Polyethylene Composition B was contained in Layers B and H, and Polyethylene Composition 2 was contained in Layers C and G.

Table 15

[0292] As shown in Table 14, Film 5-4 did not contain polyamide. Film 5-4 contained approximately 22% of Comparative Polyethylene Composition B and 8% of Polyethylene Composition 2 based on the total thickness of Film 5-4. In Film 5-4, Comparative Polyethylene Composition B was contained in Layers B and H, and Polyethylene Composition 2 was contained in Layers C and G.

Table 16

[0293] The extrusion conditions used for the production of Comparative Films 5-A, 5-B, 5-C, 5-D and Films 5-1, 5-2, 5-3, 5-4 are summarized in Table 15.

Table 17

[0294] Example 6: Analysis of Comparative Films 5-A, 5-B, 5-C, 5-D and Films 5-1, 5-2, 5-3, 5-4 To compare the performance of Comparative Films 5-A, 5-B, 5-C, 5-D with Films 5-1, 5-2, 5-3, 5-4, dirt drop impact was measured according to ISO 7765-1, and puncture elongation and puncture force were measured according to ASTM D 5748-95.

[0295] The results of puncture and dirt drop impact for Comparative Films 5-A, 5-B, 5-C, 5-D and Films 5-1, 5-2, 5-3, 5-4 are provided in Table 16.

Table 18

[0296] As shown in Table 16, the comparative films 5-C, 5-D and films 5-1, 5-2, 5-3, 5-4 showed higher puncture force and resistance to dirt drop impact than the comparative film 5-A containing about 6% polyamide. Both comparative films 5-A and 5-B containing polyamide showed the lowest puncture elongation measurement values (51.15 mm and 46.542 mm, respectively). The comparative film 5-B having about 15% polyamide showed the highest impact resistance as a result of its high molecular weight and molecular design. However, the comparative film 5-B also had the poorest recyclability when compared with the other films of Example 5 because of its high polyamide content.

[0297] The comparison of films 5-2, 5-3, and 5-4 shows the effect of increasing the density of the subskin layers adjacent to the tie layers (layers C and G) while keeping the remaining layers constant. Without being bound by theory, it is believed that the outer subskins (layers B and H) can have a greater influence on the puncture properties of the multilayer film as a whole. As shown in Table 16, the puncture elongation properties of the samples generally decreased as the density increased, but none of the films 5-1, 5-2, 5-3, or 5-4 showed lower elongation than the comparative films containing polyamide (comparative films 5-A and 5-B). Without being bound by theory, it is believed that increasing the density of the subskin layer can sharpen the slope of the puncture curve without affecting the maximum puncture force of the film. Furthermore, increasing the density of layers C and G seemed to have an adverse effect on the impact resistance of the film.

[0298] It will be apparent that modifications and changes can be made without departing from the scope of the disclosure as defined in the appended claims. More specifically, although some aspects of the disclosure have been identified herein as preferred or particularly advantageous, it is contemplated that the disclosure is not necessarily limited to these aspects. The present invention may include the following aspects. [1] A multilayer film comprising a first layer containing polyethylene, a second layer containing a first medium density polyethylene, a barrier layer, wherein the second layer is disposed between the first layer and the barrier layer, a third layer containing a second medium density polyethylene, wherein the barrier layer is disposed between the second layer and the third layer, a fourth layer containing polyethylene, wherein the third layer is disposed between the barrier layer and the fourth layer, wherein the first medium density polyethylene and the second medium density polyethylene each (a) is a first polyethylene fraction having a single peak in the temperature range of 45°C to 87°C in the elution profile by an improved comonomer composition distribution (iCCD) analysis method, and the area of the first polyethylene fraction is the area within the elution profile under the single peak of the first polyethylene fraction at 45°C to 87°C, (b) is a second polyethylene fraction having a single peak in the temperature range of 95°C to 120°C in the elution profile by the iCCD analysis method, and the area of the second polyethylene fraction is the area within the elution profile under the single peak of the second polyethylene fraction at 95°C to 120°C, The first medium density polyethylene and the second medium density polyethylene each have a density of 0.924 g / cm 3 ~0.936 g / cm 3 and a melt index (I 2 ) of 0.25 g / 10 min to 2.0 g / 10 min. The area of the first polyethylene fraction constitutes at least 40% of the total area of the elution profile. The ratio of the area of the first polyethylene fraction to the area of the second polyethylene fraction is 0.75 to 2.5, and the width of the single peak of the second polyethylene fraction at 50% of the peak height is less than 5.0°C. Multilayer film. [2] The multilayer film according to [1], further comprising one or more tie layers disposed between the barrier layer and one or both of the second layer and the third layer. [3] The multilayer film according to [1], wherein the second layer, the third layer, or both further comprises high density polyethylene, low density polyethylene, linear low density polyethylene, or a combination thereof, respectively. [4] The multilayer film according to any one of the preceding claims, wherein the second layer, the third layer, or both each comprises 5 wt% to 100 wt% of the first medium density polyethylene, the second medium density polyethylene, or a combination thereof, based on the total weight of each layer. [5] The multilayer film according to any one of the preceding claims, wherein the second layer, the third layer, or both each comprises up to 20 wt% of low density polyethylene, based on the total weight of each of the respective layers. [6] The multilayer film according to any one of the preceding claims, further comprising a fifth layer disposed between the barrier layer and the first layer, wherein the fifth layer comprises one or more of the first medium density polyethylene, high density polyethylene, low density polyethylene, linear low density polyethylene, or a combination thereof. [7] The multilayer film according to any one of the preceding claims, further comprising a sixth layer disposed between the barrier layer and the fourth layer, wherein the fifth layer comprises one or more of the second medium density polyethylene, high density polyethylene, low density polyethylene, linear low density polyethylene, or a combination thereof. [8] The multilayer film according to any one of the preceding claims, wherein the multilayer film comprises a combined 5 wt% to 90 wt% of the first medium density polyethylene and the second medium density polyethylene, based on the total weight of the multilayer film. [9] The multilayer film according to any one of the preceding claims, wherein the first layer, the fourth layer, or both each comprises 0 wt% to 100 wt% of linear low density polyethylene, based on the total weight of each of the respective layers.

[10] The multilayer film according to any one of the preceding claims, wherein the first layer, the fourth layer, or both each comprises 0 wt% to 100 wt% of the first medium density polyethylene, the second medium density polyethylene, or both, based on the total weight of each of the respective layers.

[11] The multilayer film according to any one of the preceding claims, having a puncture force exceeding 1 N / micrometer when measured according to ASTM D 5748-95.

[12] The multilayer film according to any one of the preceding claims, having a puncture elongation exceeding 55 mm when measured according to ASTM D 5748-95.

[13] The multilayer film according to any one of the preceding claims, substantially free of polyamide.

[14] A multilayer film comprising: A first outer layer containing polyethylene; A first subskin layer containing first medium density polyethylene; A second subskin layer containing second medium density polyethylene, wherein the first subskin layer is disposed between the first outer layer and the second subskin layer; A first tie layer, wherein the second subskin layer is disposed between the first subskin layer and the first tie layer; A barrier layer, wherein the first tie layer is disposed between the second subskin layer and the barrier layer; A second tie layer, wherein the barrier layer is disposed between the first tie layer and the second tie layer; A third subskin layer containing third medium density polyethylene, wherein the second tie layer is disposed between the barrier layer and the third subskin layer; A fourth subskin layer containing fourth medium density polyethylene, wherein the third subskin layer is disposed between the second tie layer and the fourth subskin layer; A second outer layer containing polyethylene, wherein the fourth subskin layer is disposed between the third subskin layer and the second outer layer. The first medium density polyethylene, the second medium density polyethylene, the third medium density polyethylene, and the fourth medium density polyethylene are each (a) a first polyethylene fraction having a single peak in an elution profile by an improved comonomer composition distribution (iCCD) analysis method in a temperature range of 45°C to 87°C, wherein the area of the first polyethylene fraction is the area within the elution profile under the single peak of the first polyethylene fraction at 45°C to 87°C; (b) A second polyethylene fraction having a single peak in the temperature range of 95°C to 120°C in the elution profile by the iCCD analysis method, wherein the area of the second polyethylene fraction is the area within the elution profile under the single peak of the second polyethylene fraction at 95°C to 120°C, including the second polyethylene fraction, The first medium-density polyethylene, the second medium-density polyethylene, the third medium-density polyethylene, and the fourth medium-density polyethylene each have a density of 0.924 g / cm 3 to 0.936 g / cm 3 and a melt index (I 2 ) of 0.25 g / 10 min to 2.0 g / 10 min. The area of the first polyethylene fraction constitutes at least 40% of the total area of the elution profile. The ratio of the area of the first polyethylene fraction to the area of the second polyethylene fraction is 0.75 to 2.5, and the width of the single peak of the second polyethylene fraction at 50% of the peak height is less than 5.0°C. A multilayer film.

[15] The multilayer film according to

[14] , wherein the multilayer film substantially does not contain polyamide.

Claims

Claim 1 A multilayer film comprising: a first layer containing polyethylene; a second layer containing a first medium-density polyethylene; a barrier layer, wherein the second layer is disposed between the first layer and the barrier layer; a third layer containing a second medium-density polyethylene, wherein the barrier layer is disposed between the second layer and the third layer; a fourth layer containing polyethylene, wherein the third layer is disposed between the barrier layer and the fourth layer; wherein the first medium-density polyethylene and the second medium-density polyethylene each comprise: (a) a first polyethylene fraction having a single peak in the temperature range of 45°C to 87°C in an elution profile by an improved comonomer composition distribution (iCCD) analysis method, wherein the area of the first polyethylene fraction is the area within the elution profile under the single peak of the first polyethylene fraction at 45°C to 87°C; and (b) a second polyethylene fraction having a single peak in the temperature range of 95°C to 120°C in the elution profile by the iCCD analysis method, wherein the area of the second polyethylene fraction is the area within the elution profile under the single peak of the second polyethylene fraction at 95°C to 120°C; The first medium-density polyethylene and the second medium-density polyethylene each have a density of 0.924 g / cm ３ to 0.936 g / cm ３ and a melt index (I ２ ) of 0.25 g / 10 min to 2.0 g / 10 min, the area of the first polyethylene fraction constitutes at least 40% of the total area of the elution profile, the ratio of the area of the first polyethylene fraction to the area of the second polyethylene fraction is 0.75 to 2.25, and the width of the single peak of the second polyethylene fraction at 50 percent of the peak height is less than 5.0 °C, a multilayer film. Claim 2 The multilayer film according to claim 1, further comprising one or more tie layers disposed between the barrier layer and one or both of the second layer and the third layer. Claim 3 The multilayer film according to claim 1, wherein the second layer, the third layer, or both further comprise high-density polyethylene, low-density polyethylene, linear low-density polyethylene, or a combination thereof. Claim 4 The multilayer film according to any one of claims 1 to 3, wherein the second layer, the third layer, or both each comprise 5% to 100% by weight of the first medium-density polyethylene, the second medium-density polyethylene, or a combination thereof based on the total weight of each layer. Claim 5 The multilayer film according to any one of claims 1 to 4, wherein the second layer, the third layer, or both each comprise up to 20% by weight of low-density polyethylene based on the total weight of each layer. Claim 6 Further comprising a fifth layer disposed between the barrier layer and the first layer, wherein the fifth layer comprises one or more of the first medium density polyethylene, high density polyethylene, low density polyethylene, linear low density polyethylene or combinations thereof, the multilayer film according to any one of claims 1-5.

7. Further comprising a sixth layer disposed between the barrier layer and the fourth layer, wherein the fifth layer comprises one or more of the second medium density polyethylene, high density polyethylene, low density polyethylene, linear low density polyethylene or combinations thereof, the multilayer film according to claim 6.

8. The multilayer film according to any one of claims 1-7, wherein the multilayer film comprises 5 wt% to 90 wt% of the first medium density polyethylene and the second medium density polyethylene in combination based on the total weight of the multilayer film.

9. The multilayer film according to any one of claims 1-8, wherein the first layer, the fourth layer, or both comprise 0 wt% to 100 wt% of linear low density polyethylene based on the total weight of each respective layer.

10. The multilayer film according to any one of claims 1-9, wherein the first layer, the fourth layer, or both comprise 0 wt% to 100 wt% of the first medium density polyethylene, the second medium density polyethylene, or both based on the total weight of each respective layer.

11. The multilayer film according to any one of claims 1-10, wherein the multilayer film has a puncture force exceeding 1 N / micrometer when measured according to ASTM D 5748-95.

12. The multilayer film according to any one of claims 1-11, wherein the multilayer film has a puncture elongation exceeding 55 mm when measured according to ASTM D 5748-95.

13. The multilayer film according to any one of claims 1-12, wherein the multilayer film is substantially free of polyamide.

14. A multilayer film, A first outer layer comprising polyethylene, A first subskin layer comprising a first medium density polyethylene, A second subskin layer comprising a second medium density polyethylene, wherein the first subskin layer is disposed between the first outer layer and the second subskin layer, the second subskin layer A first tie layer, wherein the second sub-skin layer is disposed between the first sub-skin layer and the first tie layer. A barrier layer, wherein the first tie layer is disposed between the second sub-skin layer and the barrier layer. A second tie layer, wherein the barrier layer is disposed between the first tie layer and the second tie layer. A third sub-skin layer containing a third medium density polyethylene, wherein the second tie layer is disposed between the barrier layer and the third sub-skin layer. A fourth sub-skin layer containing a fourth medium density polyethylene, wherein the third sub-skin layer is disposed between the second tie layer and the fourth sub-skin layer. A second outer layer containing polyethylene, wherein the fourth sub-skin layer is disposed between the third sub-skin layer and the second outer layer. The first medium density polyethylene, the second medium density polyethylene, the third medium density polyethylene, and the fourth medium density polyethylene are respectively (a) A first polyethylene fraction having a single peak in a temperature range of 45°C to 87°C in an elution profile by an improved comonomer composition distribution (iCCD) analysis method, wherein the first polyethylene fraction area is the area within the elution profile under the single peak of the first polyethylene fraction at 45°C to 87°C. (b) A second polyethylene fraction having a single peak in a temperature range of 95°C to 120°C in the elution profile by the iCCD analysis method, wherein the second polyethylene fraction area is the area within the elution profile under the single peak of the second polyethylene fraction at 95°C to 120°C. The first medium density polyethylene, the second medium density polyethylene, the third medium density polyethylene, and the fourth medium density polyethylene each have a density of 0.924 g / cm ３ to 0.936 g / cm ３ and a melt index (I ２ ) of 0.25 g / 10 min to 2.0 g / 10 min, the first polyethylene fraction area constitutes at least 40% of the total area of the elution profile, the ratio of the first polyethylene fraction area to the second polyethylene fraction area is 0.75 to 2.25, and the width of the single peak of the second polyethylene fraction at 50 percent of the peak height is less than 5.0 °C, a multilayer film.

15. The multilayer film according to claim 14, wherein the multilayer film substantially does not contain polyamide.

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