Multilayer structure including a machine direction stretched multilayer film

Abstract

In one embodiment, the multilayer structure may include a machine direction oriented (MDO) multilayer film, a first layer, and a sealant layer. The MDO multilayer film may include (i) a metal layer, and (ii) an inner layer. The inner layer may include a blend of EVOH; PVOH; or polyethylene with an interpolymer of ethylene and methyl acrylate, ethyl acrylate, or a carboxylic acid. The first layer may be extruded onto the metal layer. The first layer may include an interpolymer of ethylene and acrylic acid or methacrylic acid. The interpolymer may have a melt index (I) of 5 to 20 g / 10 min. 2 ), an acid content of 1 to 10 wt. %, and a melting temperature of 90° C. to 100° C. The sealant layer may have a melt index (I 2 ) and a polyethylene having a heat seal initiation temperature of 95° C. or less.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 235,883, filed August 23, 2021, the entire disclosure of which is incorporated herein by reference.

[0002] FIELD OF THEINVENTION The present disclosure relates to multilayer structures, and more particularly to multilayer structures comprising machine direction stretched films. [Background technology]

[0003] There has been interest in machine direction oriented (MDO) polyethylene films in the market, but one limitation in the use of MDO polyethylene films is the significant loss of sealing performance after orientation compared to other films. A 20°C to 25°C increase in sealing temperature is typical for MDO polyethylene films compared to other films. MDO polyethylene films are also understood to have lower temperature resistance compared to laminated films. This combination of factors results in a very narrow sealing window, which can make it difficult to manufacture articles from such MDO films when a heat sealing process is required.

[0004] Therefore, new structures are desired that can cost effectively extend the range between sealing and shrinking in multi-layer structures. Summary of the Invention

[0005] The sealant layer should generally be sealable at a temperature lower than the decomposition temperature of the other parts of the multi-layer structure being sealed. For example, in some production lines where two films are sealed together by a sealing bar, the sealant layers of both films are brought into contact with each other and the sealing bar is heated in contact with the outer layer of the film. Heat is transferred through the outer layer of the film to the inner sealant layer that seals them together. A reduction in the sealing temperature is desirable because it can reduce the decomposition (e.g., combustion) of the other layers of the multi-layer structure. Furthermore, a reduction in the sealing temperature allows for more consistent sealing because the sealing procedure can be performed over a wider range between the decomposition temperature of the film and the seal initiation temperature of the sealant layer. An embodiment of the present disclosure meets this need by providing an MDO multi-layer film having a metal layer, a first layer extruded onto the metal layer, and a sealant layer in adhesive contact with the first layer, as further described herein.

[0006] According to one embodiment of the present disclosure, the multilayer structure may include a machine direction oriented (MDO) multilayer film, a first layer, and a sealant layer. The MDO multilayer film may include (i) a metal layer, and (ii) an inner layer in adhesive contact with the metal layer. The inner layer may include a blend of ethylene vinyl alcohol; polyvinyl alcohol; or polyethylene with an interpolymer of ethylene and methyl acrylate, ethyl acrylate, or carboxylic acid. The first layer may be extruded onto the metal layer of the MDO multilayer film. The first layer may include an interpolymer of ethylene and acrylic acid or methacrylic acid. The interpolymer may have a melt index (I2) of 5 to 20 g / 10 min, an acid content of 1 to 10 wt. %, and a melt temperature of 90° C. to 100° C. The sealant layer may be in adhesive contact with the first layer. The sealant layer may include polyethylene having a melt index (I2) of 3 to 30 g / 10 min and a heat seal initiation temperature of 95° C. or less.

[0007] Although the concepts of the present disclosure are described herein primarily with reference to machine direction stretched films having metal layers, it is contemplated that the concepts enjoy applicability to any multilayer film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Reference will now be made in more detail to various embodiments that are examples of the claimed subject matter, it being understood that the features of the multi-layer structure described in the detailed description should not be construed as limitations of the claimed embodiments, unless expressly so stated.

[0009] According to some embodiments of the present disclosure, the multilayer structure may include a machine direction oriented (MDO) multilayer film, a first layer, and a sealant layer. The machine direction oriented (MDO) multilayer film may include (i) a metal layer, and (ii) an inner layer in adhesive contact with the metal layer. In some embodiments, the metal layer is a metallized layer. The inner layer may include a blend of ethylene vinyl alcohol; polyvinyl alcohol; or polyethylene with an interpolymer of ethylene and methyl acrylate, ethyl acrylate, or carboxylic acid. The first layer may be extruded onto the metal layer of the machine direction oriented multilayer film. The first layer may include an interpolymer of ethylene and acrylic acid or methacrylic acid. The interpolymer may have a melt index (I2) of 5 to 20 g / 10 min, an acid content of 1 to 10 wt.%, and a melt temperature of 90° C. to 100° C. The sealant layer may be in adhesive contact with the first layer. The sealant layer may comprise polyethylene having a melt index (I2) of 3 to 30 g / 10 min and a heat seal initiation temperature of 95° C. or less.

[0010] According to one or more embodiments, the multilayer structure may include a machine direction stretched film. As described herein, a "machine direction stretched" film is one that is formed by uniaxially stretching a film in the machine direction to improve physical and barrier properties. For example, the film may be heated and uniaxially stretched longitudinally on a series of rollers. As used herein, the term "machine direction" refers to the length of the film in the direction in which the film is produced. A film that is oriented in the machine direction may exhibit improved tensile properties compared to one that has not been subjected to a machine direction orientation procedure.

[0011] As described herein, a "film" includes any continuous layer of a polyolefin-containing material, generally having a large length-to-width and width-to-thickness ratio. In one or more embodiments, the film may include one or more olefin-based polymers. As used herein, the terms "olefin-based polymer," "olefin polymer," and "polyolefin" refer to a polymer that, in polymerized form, includes a majority amount of an olefin monomer, e.g., ethylene or propylene (based on the weight of the polymer), and may optionally include one or more comonomers. The term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the generic term polymer encompasses the term "homopolymer," which is typically used to refer to a polymer prepared from only one type of monomer, as well as "copolymer," which refers to a polymer prepared from two or more different monomers. The films described herein may be multilayer films that include more than one layer.

[0012] As used herein, "interpolymer" may refer to a polymer derived from more than one type of monomer. For example, an interpolymer may contain two, three, four, or more than four types of monomer. As used herein, "terpolymer" may refer to a polymer derived from three types of monomer. A terpolymer may be characterized as a random interpolymer, a periodic interpolymer, a statistical interpolymer, or a block interpolymer. As used herein, "random interpolymer" may refer to an interpolymer containing multiple types of monomer units distributed in a random order. As used herein, "periodic interpolymer" may refer to an interpolymer containing three or more types of monomer units arranged in a repeating pattern. As used herein, "statistical interpolymer" may refer to an interpolymer containing two or more monomer units having a distribution according to a statistical rule. As used herein, "block interpolymer" may refer to an interpolymer containing two or more monomer units, where the monomer units form clusters with similar monomer units. For example, a block interpolymer may have a structure of the form AAAABBBCCC.

[0013] As used herein, "polyethylene" or "ethylene-based polymer" is intended to mean a polymer that contains more than 50 mole percent units derived from ethylene monomers. This includes ethylene-based homopolymers, ethylene copolymers (meaning units derived from ethylene and additional monomers), and ethylene interpolymers (meaning units derived from ethylene and at least one additional comonomer). These comonomers are selected from the group consisting of C3-C 12It may include an α-olefin comonomer or it may include a polar comonomer, which may include, but is not limited to, those having carboxylic acid, acrylate, or acetate functionality, such as methacrylic acid, acrylic acid, vinyl acetate, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, glycidyl methacrylate, and the monoethyl ester of maleic acid. Forms of polyethylene include, but are not limited to, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (ULDPE), very low density polyethylene (VLDPE), single-site catalyzed 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).

[0014] Additionally, as described herein, the term "LDPE" may also be referred to as "high pressure ethylene polymer", or "highly branched polyethylene", and is defined to mean that the polymer is partially or fully homopolymerized or copolymerized in an autoclave or tubular reactor at pressures above 14,500 psi (100 MPa) using a free radical initiator such as peroxide (see, for example, U.S. Pat. No. 4,599,392, which is incorporated by reference). LDPE resins typically have a density in the range of 0.916 to 0.940 g / cm.

[0015] As used herein, the term "LLDPE" can include 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"), phosphinimine, and constrained geometry catalysts; and post-metallocene molecular catalysts, including, but not limited to, bis(biphenylphenoxy) catalysts (also referred to as polyaryloxy ether catalysts). LLDPE includes linear, substantially linear, or heterogeneous ethylene-based copolymers or homopolymers. LLDPE contains less long chain branching than LDPE and includes substantially linear ethylene polymers, further defined in U.S. Pat. Nos. 5,272,236, 5,278,272, 5,582,923 and 5,733,155, homogeneously branched ethylene polymers as in U.S. Pat. No. 3,645,992, heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Pat. No. 4,076,698, and blends thereof (such as those disclosed in U.S. Pat. No. 3,914,342 or U.S. Pat. No. 5,854,045). LLDPE resins may be made via gas phase, solution phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art. LLDPE resins may 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.

[0016] The term "ULDPE" is defined as a polyethylene-based copolymer having a density in the range of 0.895 to 0.915 g / cc.

[0017] The term "MDPE" refers to polyethylene having a density of 0.926 to 0.935 g / cc. "MDPE" is typically made using chromium or Ziegler-Natta catalysts, and single-site catalysts, such as, but not limited to, bis-metallocene catalysts and constrained geometry catalysts.

[0018] Further, as used herein, the term "HDPE" refers to polyethylene having a density of about 0.940 g / cm or greater, generally prepared using Ziegler-Natta, chromium, or even metallocene catalysts.

[0019] The multilayer structure may include an MDO multilayer film, a first layer, and a sealant layer. As described herein, "multilayer structure" refers to any structure having two or more layers. For example, a multilayer structure (e.g., a film) may have two, three, four, five, or more layers. A multilayer structure may be described as having layers designated by letters. For example, a three-layer structure having a core layer B and two outer layers A and C may be designated as A / B / C. Similarly, a structure having two core layers B and C and two outer layers A and D would be designated as A / B / C / D.

[0020] The MOD multilayer film may have a thickness of 10 μm to 100 μm. For example, the MOD multilayer film may have a thickness of 10 μm to 90 μm, 10 μm to 75 μm, 10 μm to 60 μm, 10 μm to 45 μm, 10 μm to 30 μm, 20 μm to 100 μm, 20 μm to 90 μm, 20 μm to 75 μm, 20 μm to 60 μm, 20 μm to 45 μm, 20 μm to 30 μm, or any subset thereof.

[0021] According to one or more embodiments, the machine direction stretched film may have a melting point of 150° C. or less, such as 145° C. or less, or even 140° C. or less. This is in contrast to other films that may have higher melting points. For example, polypropylene films may have a melting point above 150° C., and polyethylene terephthalate films may have a melting point above 250° C.

[0022] An MDO multilayer film may include (i) a metal layer, and (ii) an inner layer in adhesive contact with the metal layer. The term "adhesive contact" and similar terms mean that one opposing surface of one layer and one opposing surface of another layer are in contact with each other and in bonding contact such that one layer cannot be removed from the other layer without damaging the interlaminar surfaces (i.e., the contacting facial surfaces) of both layers.

[0023] The metal layer may be a metallized layer applied to the outer layer of the MOD multilayer film using vacuum metallization, a well-known technique for depositing metals in which a metal source is evaporated in a vacuum environment and the metal vapor condenses on the surface of the film to form a thin layer as the film passes through a vacuum chamber.

[0024] Metals that can be deposited to form the metallization layer include Al, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, or oxides thereof. In some embodiments, the metallization layer is formed from aluminum or aluminum oxide (A1203). The metallization layer may also include metalloid silicon or an oxide thereof. According to some embodiments, the metallization layer may include aluminum, silicon, or an oxide thereof.

[0025] Metallized layers can advantageously provide good barriers to oxygen and water vapor. The combination of a MOD multilayer film with a metallized layer deposited on certain exterior surfaces can provide a synergistic combination of both mechanical and barrier properties.

[0026] In some embodiments, the metallization layer may be a decorative layer that is included to add luster to the flexible package. Those skilled in the art will be familiar with a number of applicable metallization techniques. These may include, but are not limited to, physical vapor deposition or vacuum metallization. While various thicknesses are contemplated, the metallization layer may have a thickness of less than 100 nanometers, or between 10 and 80 nanometers, or between 20 and 60 nanometers, in one or more embodiments.

[0027] In some embodiments, the metal layer may be a foil layer that is adhered to the remainder of the MDO multilayer film with the tie layer. In embodiments where the metal layer is a foil layer, the foil layer may have a thickness of 6 to 15 μm, 6 to 12 μm, 10 to 15 μm, 8 to 12 μm, or any subset thereof.

[0028] In embodiments in which a tie layer is present, the tie layer may comprise maleated polyethylene, a copolymer of ethylene and a carboxylic acid, or a combination thereof. As used herein, "maleated" materials are those that include salts or esters of maleic acid.

[0029] Referring again to the MDO multilayer film, the MDO multilayer film may have five layers and a structure A / B / C / D / E, where layer A is an inner layer and the metallized layer is on the surface of layer A. Layer A may have a thickness of 10% to 20% of the total thickness of the MDO multilayer film. Layer B may have a thickness of 10% to 20% of the total thickness of the MOD multilayer film. Layer C may have a thickness of 20% to 40% of the total thickness of the MOD multilayer film. Layer D may have a thickness of 10% to 30% of the total thickness of the MOD multilayer film. Layer E may have a thickness of 10% to 30% of the total thickness of the MOD multilayer film. The layers may be extruded one on top of the other. The MOD multilayer film may have one or more polyethylene layers. For example, the MDO multilayer film may have 2, 3, 4, or 5 polyethylene layers.

[0030] As previously mentioned, the inner layer, Layer A, comprises at least one polymer having at least one polar monomer. For example, the inner layer (Layer A) may comprise one or more of ethylene vinyl-alcohol (EVOH), polyvinyl-alcohol (PVOH), a polyethylene resin, a mixture of a polyethylene resin and an interpolymer of ethylene and an acrylate, or a mixture of a polyethylene resin and an interpolymer of ethylene and a carboxylic acid.

[0031] In an embodiment of the inner layer comprising EVOH, the EVOH has a viscosity of 0.90 g / cm 3 ~1.40g / cm 3 , or 0.95 g / cm 3 ~1.20g / cm 3 , or any subset thereof. Layer A may have a melt index from 0.70 g / 10 min to 1.9 g / 10 min. The EVOH may have a melt index from 1.00 g / 10 min to 3.00 g / 10 min, or from 1.00 g / 10 min to 2.50 g / 10 min, or from 1.50 g / 10 min to 2.00 g / 10 min, or any subset thereof. The EVOH may have a melt temperature from 120° C. to 250° C., or from 150° C. to 200° C., or any subset thereof. Suitable commercially available examples of EVOH include Eval E171B, F171B, and J171B commercially available grades available from EVAL Europe NV.

[0032] In an embodiment of the inner layer comprising a polyethylene resin, the polyethylene has a viscosity of 0.940 g / cm 3 ~0.975g / cm 3 , or 0.945 g / cm 3 ~0.970g / cm 3 , or 0.950 g / cm 3 ~0.965g / cm 3, or any subset thereof. The ethylene-α-olefin copolymer may have a melt index of 0.5 g / 10 min to 3.00 g / 10 min, or 0.75 g / 10 min to 2.00 g / 10 min, or any subset thereof. The ethylene-α-olefin copolymer may be an LLDPE. Suitable commercially available LLDPE resins may include DOWLEX™ 2750ST from Dow Inc., (Midland, MI). In addition, a suitable commercially available example may include ELITE™ 5960G1 reinforced polyethylene from Dow Inc., (Midland, MI).

[0033] In embodiments of the inner layer comprising an interpolymer of ethylene and an acrylate, the acrylate may be any suitable C2-C 12 Acrylates such as methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, and glycidyl methacrylate may be included. In one embodiment, the acrylate includes n-butyl acrylate. In terms of monomer amounts, the ethylene-acrylate comonomer may include 10-40 wt.% acrylate, or 15-35 wt.%, or 20-30 wt.% acrylate, with the balance including ethylene monomer. Interpolymers of ethylene and acrylates have a viscosity of 0.910 g / cm. 3 ~0.955g / cm 3 , or 0.920 g / cm 3 ~0.950g / cm 3 , or 0.925 g / cm 3 ~0.945g / cm 3 , or any subset thereof. The ethylene and acrylate interpolymers may have a melt index of 0.5 g / 10 min to 5.00 g / 10 min, or 1.00 g / 10 min to 4.50 g / 10 min, or 1.50 g / 10 min to 4.00 g / 10 min, or any subset thereof. Suitable commercial examples include ELVALOY™ AC grades 1224, 3117, and 3427 from Dow Inc. (Midland, MI).

[0034] Layer B may also include one or more polyethylenes. The polyethylene may have a viscosity of 0.910 g / cm 3 ~0.950g / cm 3 or 0.915~0.945g / cm 3 In some embodiments, the lower density polyethylene (0.910 g / cm 3 ~0.920g / cm 3 ) and higher density polyethylene (0.930 g / cm 3 ~0.945g / cm 3 ) may be present. The polyethylene may have a melt index of 0.25 g / 10 min to 2.0 g / 10 min, or 0.50 g / 10 min to 1.5 g / 10 min, or 0.75 g / 10 min to 1.25 g / 10 min, or any subset thereof. The polyethylene in Layer B may have a melt temperature of 100° C. to 140° C., or 110° C. to 130° C., or 115° C. to 130° C., or any subset thereof. Suitable commercially available examples include ELITE™ 5400 GS and 5940 ST reinforced polyethylenes from Dow Inc. (Midland, MI), which may be used individually or in blends.

[0035] In other embodiments, layer B may include a tie layer comprising ethylene and an 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 comprising at least one anhydride group covalently linked. 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 in the low melt viscosity maleic anhydride grafted polyolefin include, but are not limited to, polyethylene homopolymers and copolymers with α-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).

[0036] In one or more embodiments, the anhydride-grafted ethylene / alpha-olefin interpolymer comprises up to 10 wt%, up to 5 wt%, or from 0.1 to 4 wt% maleic anhydride grafting monomer, based on the total weight of the anhydride-grafted ethylene / alpha-olefin interpolymer.

[0037] Examples of anhydride grafting moieties 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-heptane-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, and 4-methyl-4-cyclohexene-1,2-dicarboxylic anhydride. ,3-dicarboxylic anhydride, 2-oxa-1,3-diketospiro(4.4)non-7-ene, bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride, norborn-5-ene-2,3-dicarboxylic anhydride, nadic anhydride, methylnadic anhydride, himic anhydride, methylhimic anhydride, and x-methyl-bi-cyclo(2.2.1)hept-5-ene-2,3-dicarboxylic anhydride. In one embodiment, the anhydride grafted portion comprises maleic anhydride.

[0038] In a further embodiment, the anhydride-grafted ethylene / α-olefin interpolymer has a viscosity of 0.890 g / cm as measured according to ASTM method D792-91. 3 ~0.940g / cm 3 Other density ranges are 0.900 g / cm 3 ~0.930g / cm 3 or 0.905 g / cm 3 ~0.915g / cm 3 In one or more embodiments, the anhydride-grafted ethylene / α-olefin interpolymer may have a melt index (I2) of 0.5 g / 10 min to 3 g / 10 min, or 1 g / 10 min to 2 g / 10 min, or 1.5 g / 10 min to 2.0 g / 10 min, as determined according to ASTM method D1238 at 190° C. and 2.16 kg. A suitable commercially available example of an anhydride-grafted ethylene / α-olefin interpolymer may include BYNEL™ 41E687B manufactured by Dow Inc. (Midland, MI).

[0039] Layers C and D may also contain one or more polyethylenes. As with Layer B, the polyethylene may have a viscosity of 0.910 g / cm 3 ~0.950g / cm 3 or 0.915~0.945g / cm 3 In some embodiments, the lower density polyethylene (0.910 g / cm 3 ~0.920g / cm 3 ) and higher density polyethylene (0.930 g / cm 3 ~0.945g / cm 3 ) may be present. The polyethylene may have a melt index of 0.25 g / 10 min to 2.0 g / 10 min, or 0.50 g / 10 min to 1.5 g / 10 min, or 0.75 g / 10 min to 1.25 g / 10 min, or any subset thereof. The polyethylene in Layer B may have a melt temperature of 100° C. to 140° C., or 110° C. to 130° C., or 115° C. to 130° C., or any subset thereof. Suitable commercially available examples include ELITE™ 5400 GS and 5940 ST reinforced polyethylenes from Dow Inc. (Midland, MI), which may be used individually or in blends.

[0040] Layer E may also include one or more polyethylene resins. 3 ~0.975g / cm 3 , or 0.945 g / cm 3 ~0.970g / cm 3 , or 0.950 g / cm 3 ~0.965g / cm 3, or any subset thereof. The ethylene-α-olefin copolymer may have a melt index of 0.5 g / 10 min to 3.00 g / 10 min, or 0.75 g / 10 min to 2.00 g / 10 min, or any subset thereof. The ethylene-α-olefin copolymer may be an LLDPE. Suitable commercially available LLDPE resins may include DOWLEX™ 2750ST from Dow Inc., (Midland, MI). In addition, a suitable commercially available example may include ELITE™ 5960G1 reinforced polyethylene from Dow Inc., (Midland, MI).

[0041] Referring again to the first layer above, the first layer may be extrusion coated onto the metallized layer of the machine direction oriented multilayer film. As described herein, extruding the first layer may include forming the first layer through a die to form the desired layer thickness and other physical characteristics. The polymer blends of the present disclosure may be prepared by melt blending a set amount of components in a twin screw extruder before feeding into an extrusion coater (or other equipment) for film production. Such polymer blends may also be prepared by tumble blending a set amount of components before feeding into an extrusion coater (or other equipment) for film production. In some embodiments, the polymer blends may be in the form of pellets. For example, the individual components may be melt blended and then formed into pellets using a twin screw extruder or other techniques known to those skilled in the art based on the teachings herein. In some embodiments, the polymer blends may include a combination of compounded pellets and additional polymers that are tumble blended before feeding into an extrusion coater.

[0042] The first layer may be extruded onto the MDO multilayer film at a loading of 2 grams per square meter (gsm) to 16 gsm. For example, the first layer may have a loading of 2 gsm to 12 gsm, 2 gsm to 8 gsm, 2 gsm to 6 gsm, 4 gsm to 16 gsm, 4 gsm to 12 gsm, 4 gsm to 8 gsm, or any subset thereof.

[0043] The interpolymer of the first layer can include from 50% to 98% by weight ethylene monomer. For example, the interpolymer of the first layer can include from 60% to 98% by weight, from 70% to 98% by weight, from 80% to 98% by weight, from 90% to 98% by weight, from 50% to 90% by weight, from 50% to 80% by weight, from 50% to 70% by weight, from 50% to 60% by weight, from 60% to 90% by weight, from 70% to 80% by weight, or any subset thereof.

[0044] The first layer may include an interpolymer of ethylene and acrylic acid or methacrylic acid.

[0045] The interpolymer of the first layer may have a melt index (I2) of 5 to 20 g / 10 min. For example, the interpolymer of the first layer may have an I2 of 5 to 18 g / 10 min, 8 to 20 g / 10 min, 8 to 18 g / 10 min, 5 to 15 g / 10 min, 12 to 20 g / 10 min, 12 to 15 g / 10 min, or any subset thereof. As used herein, "melt index" (I2) is a measure of the melt flow rate of a polymer, as measured by ASTM D1238 at a temperature of 190° C. and a load of 2.16 kg. "Melt index" is sometimes referred to herein as "I2" and "melt flow rate."

[0046] The interpolymer of the first layer may have an acid content of 1 to 10 weight percent (wt%). As used herein, "acid content" refers to the amount of acrylic acid relative to the total weight of the interpolymer. For example, the interpolymer of the first layer may have an acid content of 1 wt% to 9 wt%, 1 wt% to 8 wt%, 1 wt% to 6 wt%, 2 wt% to 10 wt%, 3 wt% to 10 wt%, 4 wt% to 10 wt%, 2 wt% to 8 wt%, 3 wt% to 7 wt%, 4 wt% to 6 wt%, or any subset thereof.

[0047] The interpolymer of the first layer can have a melting temperature of from 90° C. to 100° C. For example, the interpolymer of the first layer can have a melting temperature of from 90° C. to 98° C., from 90° C. to 96° C., from 90° C. to 94° C., from 90° C. to 92° C., from 92° C. to 98° C., from 92° C. to 96° C., from 92° C. to 94° C., from 94° C. to 98° C., from 94° C. to 96° C., from 96° C. to 98° C., or any subset thereof.

[0048] The interpolymer of the first layer may be a terpolymer of ethylene, acrylic acid or methacrylic acid, and an alkyl acrylate. For example, the interpolymer of the first layer may be a terpolymer of ethylene, acrylic acid, and an alkyl acrylate, or the interpolymer of the first layer may be a terpolymer of ethylene, methacrylic acid, and an alkyl acrylate. In one or more embodiments of the present disclosure, the interpolymer may be a member of the NUCREL™ line available from Dow Inc (Midland, MI).

[0049] The multi-layer structure may include a sealant layer, which may generally be heated and pressurized to seal the two multi-layer structures together via the sealant layer, which may be in adhesive contact with the first layer.

[0050] In one or more embodiments, the sealant layer can be in adhesive contact with the first layer. In one or more embodiments, the sealant layer can be extruded onto the first layer. As described herein, extruding the sealant layer can include forming the sealant layer through a die to form a desired layer thickness and other physical characteristics.

[0051] The sealant layer may be extruded onto the first layer at a loading of 10 gsm to 30 gsm. For example, the sealant layer may have a loading of 10 gsm to 26 gsm, 10 gsm to 24 gsm, 10 gsm to 21 gsm, 14 gsm to 30 gsm, 14 gsm to 26 gsm, 14 gsm to 24 gsm, 14 gsm to 21 gsm, 18 gsm to 30 gsm, 18 gsm to 24 gsm, 18 gsm to 21 gsm, 18 gsm to 20 gsm, or any subset thereof.

[0052] The sealant layer may comprise 60% to 85% by weight of at least one polyethylene. For example, the sealant layer may comprise 60% to 80%, 60% to 75%, 60% to 70%, 65% to 85%, 70% to 85%, 75% to 85%, 65% to 80%, 70% to 75% by weight, or any subset thereof, of at least one polyethylene.

[0053] The sealant layer may include a polyethylene having a density of 0.870 grams per cubic centimeter (g / cc) to 0.911 g / cc. For example, the sealant layer may include a polyethylene having a density of 0.870 g / cc to 0.901 g / cc, 0.870 g / cc to 0.891 g / cc, 0.870 g / cc to 0.881 g / cc, 0.880 g / cc to 0.911 g / cc, 0.890 g / cc to 0.911 g / cc, 0.901 g / cc to 0.911 g / cc, 0.880 g / cc to 0.901 g / cc, or any subset thereof.

[0054] The sealant layer may comprise a polyethylene having a melt index (I2) of at least 3 g / 10 min. For example, the sealant layer may comprise a polyethylene having an I2 of at least 4 g / 10 min, at least 5 g / 10 min, at least 7.5 g / 10 min, at least 10 g / 10 min, at least 15 g / 10 min, at least 20 g / 10 min, at least 25 g / 10 min, or even at least 30 g / 10 min.

[0055] The sealant layer may comprise a polyethylene having a melt index (I2) of 3 to 30 g / 10 min. For example, the sealant layer may comprise a polyethylene having a melt index (I2) of 3 to 25 g / 10 min, 3 to 15 g / 10 min, 3 to 10 g / 10 min, 8 to 30 g / 10 min, 8 to 20 g / 10 min, 16 to 30 g / 10 min, 16 to 25 g / 10 min, or any subset thereof. As used herein, melt index (I2) is a measure of the melt flow rate of a polymer as measured by ASTM D1238 at a temperature of 190° C. and a load of 2.16 kg.

[0056] The sealant layer may comprise a polyethylene having a heat seal initiation temperature of 95° C. or less. For example, the sealant layer may comprise a polyethylene having a heat seal initiation temperature of 92.5° C. or less, 90° C. or less, 87.5° C. or less, 85° C. or less, 82.5° C. or less, 80° C. or less, 75° C. or less, or even 70° C. or less.

[0057] In one or more embodiments, the sealant layer may include low density polyethylene.

[0058] According to one or more embodiments, the sealant layer may include 15 to 40 weight percent (wt%) low density polyethylene, based on the total weight of the sealant layer. For example, the sealant layer may include 15 wt% to 20 wt%, 20 wt% to 25 wt%, 25 wt% to 30 wt%, 30 wt% to 35 wt%, 35 wt% to 40 wt%, or any combination of these ranges, based on the total weight of the sealant layer. In further embodiments, the sealant layer may include 15 wt% to 30 wt% low density polyethylene, based on the total weight of the sealant layer.

[0059] In one or more embodiments, the low density polyethylene of the sealant layer may have a melt index (I2) of 0.9 g / 10 min to 3.5 g / 10 min. For example, the low density polyethylene of the sealant layer may have a melt index of 0.9 g / 10 min to 3.0 g / 10 min, 0.9 g / 10 min to 2.8 g / 10 min, 0.9 g / 10 min to 2.5 g / 10 min, 1.1 g / 10 min to 3.5 g / 10 min, 1.4 g / 10 min to 3.5 g / 10 min, 1.1 g / 10 min to 3.0 g / 10 min, 1.3 g / 10 min to 2.5 g / 10 min, or any subset thereof.

[0060] In one or more embodiments, the low density polyethylene of the sealant layer has a viscosity of 0.918 g / cm 3 DOW™ LDPE 770G (commercially available from Dow Inc, Midland, Mich.) having a density of 0.918 g / cm, a melt index of 2.3 g / 10 min, and a melting point of 110° C. 3 and a melt index of 1.5 g / 10 min. (commercially available from Dow Inc, Midland, Mich.). However, other LDPEs are contemplated for use in the sealant layer, and the embodiments described herein are not limited to those including these polymers.

[0061] The sealant layer may include a propylene-based plastomer. As described herein, "propylene-based plastomer" refers to a plastomer that contains more than 50 mole percent units derived from propylene monomers. This includes propylene-based homopolymers or interpolymers (meaning units derived from two or more monomers). A plastomer may generally be understood as a polymeric material that combines the qualities of an elastomer and a thermoplastic.

[0062] According to one or more embodiments, the sealant layer can include 60% to 85% by weight of the propylene-based plastomer, based on the total weight of the sealant layer. For example, the sealant layer can include 60% to 65%, 65% to 70%, 70% to 75%, 75% to 80%, 80% to 85% by weight of the propylene-based plastomer, based on the total weight of the sealant layer, or any combination of these ranges.

[0063] According to one or more embodiments, the propylene-based plastomer has a viscosity of 0.890 g / cm 3 For example, a propylene-based plastomer may have a density of 0.860 g / cm 3 ~0.890g / cm 3 , e.g., 0.860 g / cm 3 ~0.865g / cm 3 , 0.865g / cm 3 ~0.870g / cm 3 , 0.870g / cm 3 ~0.875g / cm 3 , 0.875g / cm 3 ~0.880g / cm 3 , 0.880g / cm 3 ~0.885g / cm 3 , 0.885g / cm 3 ~0.890g / cm 3 , or any combination of these ranges.

[0064] In one or more embodiments, the propylene-based plastomer may have a melt index (I2) (at 230° C. and 2.16 kg) of at least 8 g / 10 min. For example, the propylene-based plastomer may have a melt flow rate (at 230° C. and 2.16 kg) of 8 g / 10 min to 35 g / 10 min, e.g., 8 g / 10 min to 15 g / 10 min, 15 g / 10 min to 20 g / 10 min, 20 g / 10 min to 25 g / 10 min, 25 g / 10 min to 30 g / 10 min, 30 g / 10 min to 35 g / 10 min, or any combination of ranges therein. Unless otherwise indicated, as described herein, melt index (I2) is measured according to ASTM D 1238-10, condition 230° C. / 2.16 kg, and is reported in grams dissolved per 10 minutes.

[0065] In one or more embodiments, the propylene-based plastomer can have a melting point from 70° C. to 100° C. For example, the propylene-based plastomer can have a melting point from 70° C. to 80° C., from 80° C. to 90° C., from 90° C. to 100° C., or any combination of these ranges.

[0066] In one or more embodiments, the propylene-based plastomer may be an interpolymer comprising propylene and ethylene units. According to one or more embodiments, the propylene-based plastomer may have an ethylene content of 2 mol% to 12 mol%. For example, the propylene-based plastomer may have an ethylene content of 2 mol% to 4 mol%, 4 mol% to 6 mol%, 6 mol% to 8 mol%, 8 mol% to 10 mol%, 10 mol% to 12 mol%, or any combination of these ranges.

[0067] In one or more embodiments, the propylene-based plastomer has a viscosity of 0.876 g / cm 3 The sealant layer may be VERSIFY™ 4200 plastomer (commercially available from Dow Inc, Midland, Mich.), which has a density of 1000 MPa, a melt index of 25 g / 10 min, and a melting point of 84° C. However, other propylene-based plastomers are contemplated for use in the sealant layer, and the embodiments described herein are not limited to those including these polymers.

[0068] According to one or more embodiments, the sealant layer may include a combination of low density polyethylene and a propylene-based plastomer. For example, the sealant layer may include 15% to 40% by weight of low density polyethylene and 60% to 85% by weight of the propylene-based plastomer, based on the total weight of the sealant layer.

[0069] The present disclosure also relates to articles such as packages formed from the multi-layer structures of the present disclosure. Such packages can be formed from any of the multi-layer structures of the present disclosure described herein. Examples of such articles can include flexible packages, pouches, stand-alone pouches, and pre-made packages or pouches. According to certain embodiments of the present disclosure, the article can be a pouch.

[0070] The pouch may have a length of at least 25 mm. For example, the pouch may have a length of at least 50 mm, at least 75 mm, at least 100 mm, at least 150 mm, or at least 200 mm. The pouch may have a width of at least 25 mm. For example, the pouch may have a width of at least 50 mm, at least 75 mm, at least 100 mm, at least 150 mm, or at least 200 mm.

[0071] The pouch may have a volume of at least 25 milliliters (mL). For example, the pouch may have a volume of at least 50 mL, at least 75 mL, at least 100 mL, at least 150 mL, at least 200 mL, at least 250 mL, at least 300 mL, at least 400 mL, at least 500 mL, at least 750 mL, at least 1000 mL, at least 1500 mL, at least 2000 mL, or at least 2500 mL.

[0072] The pouch may have a sealed layer. The sealed layer may be a spot where two layers of the pouch are fused together under heat and pressure. The sealed layer may have a peel strength of at least 3 Newtons per 15 mm width of the seal (N / 15 mm). For example, the sealed layer may have a peel strength of at least 4 N / 15 mm, at least 5 N / 15 mm, or at least 6 N / 15 mm. Seal strength may be measured according to ASTM D903. EXAMPLES

[0073] A sample pouch was prepared from an MDO multilayer film, a first layer extruded onto the MDO multilayer film, and a sealant layer in adhesive contact with the first layer.

[0074] The MDO multilayer films had a total thickness of 25 μm. The films were arranged in the order A / B / C / D / E, with each of the respective layers being 15% / 15% / 30% / 20% / 20% of the thickness of the MDO multilayer film.

[0075] [Table 1]

[0076] Layer A was 15% of the total thickness of the MDO multilayer film and included EVOH Eval J171. Layer B was 15% of the total thickness of the MDO multilayer film and included Bynel 41E687. Layer C was 30% of the total thickness of the multilayer film and included 80% Elite 5940 ST + 20% ELITE™ 5400 GS. Layer D was 20% of the total thickness of the MDO multilayer film and included ELITE™ 5940 ST. Layer E was 20% of the total thickness of the MDO multilayer film and included ELITE™ 5960G1.

[0077] The above MDO films used as metallized substrates were prepared on a Hosokawa-Alpine 5-layer blown film line with screw settings of 65 / 65 / 90 / 65 / 65 mm, respectively, and a die head with a diameter of 400 mm. The thickness of the primary film before MDO was 130 μm. The take-off speed was 16.1 meters per minute (m / min). The output was 370 kg / hr. The blow-up ratio (BUR) was 3.0.

[0078] The temperature profile for each extruder was as follows: A = 225°C in all zones; B = 200°C in all zones; C = 200°C in all zones; D = 220°C in all zones; E = 225°C in all zones; and die head = 228°C in all zones.

[0079] The formed film was then subjected to MDO stretching to form an MDO film. The stretching process was carried out in a Hosokawa-Alpine MDO unit equipped with four preheaters and four annealing and cooling rollers. The speeds and ratios in the relevant parts of the system are: intake speed of 16.1 m / min; exit speed of 87.2; and total stretch ratio of 5.43. The relevant temperatures are: preheat 1 = 105°C; preheat 2 = 115°C; stretch 1 = 115°C; stretch 2 = 115°C; annealing = 110°C; and cooling = 75°C.

[0080] The MDO substrate film was further metallized by vacuum deposition using a K5 Expert System by Bobst. A metallization layer having a thickness of 30 nm was deposited on the surface of layer A opposite to the surface of layer A facing layer B.

[0081] MDO substrate film 10 -4 The aluminum wire was placed in a vacuum chamber at a pressure of 1000 Torr. The aluminum wire was placed in the vacuum chamber and heated to 1400° C. The MDO substrate film was then passed through the vacuum chamber at a speed of 500 m / min. The final coating thickness of the aluminum layer was about 30 nm.

[0082] The first layer was then extruded onto the MDO multilayer film, which contained 6 grams per square meter (gsm) of NUCREL™ 3990. The polymer was coated using an ErWePa extrusion coating line, using a melt temperature of 285° C. and a line speed of 100 m / min and an air gap of 250 mm. All other conditions were typical of this well-known processing technique. The first layer was in direct contact with layer E of the MDO film.

[0083] A sealant layer was extruded onto the first layer and comprised a 19 gsm blend containing 80 wt% AFFINITY™ PL1280 (Dow Inc.) and 20 wt% AGILITY™ EC7220. The processing conditions and machine settings were the same as for the layers above. The total thickness of the first layer and the sealant layer was 25 μm.

[0084] Example 1: Pouch The multilayer structure including the MDO multilayer film, the first layer, and the sealant layer was formed into a pouch. The pouch was heat sealed with a cross seal temperature of 110° C., a long seal temperature of 120° C., and a dwell time of 300 milliseconds (ms). The total thickness of the multilayer film was 50 μm. The pouches were sealed at a rate of 60 pouches / min ppm, each measuring 240 millimeters (mm) in length. The pouches were shown to be hermetically sealed when tested on a Bosch VFF sealing line and were deemed to have good visual appearance.

[0085] Example 2: Hot Tack Furthermore, the multilayer film was tested for hot tack strength. The operating conditions were as follows: sealing pressure was 0.5 N / mm 2 The seal time was 0.5 seconds, the cooling time was 0.2 seconds, the peel speed was 200 mm / sec, and the sample width was 15 mm. The results are shown in Table 2 as follows. The hot tack present at a lower temperature such as 100° C. indicates that the present multilayer film begins to heat seal initiation at a lower temperature.

[0086] [Table 2]

[0087] Test Method Unless otherwise stated, the following test methods are utilized to measure each of the properties set forth below.

[0088] density Samples for density measurements should be prepared in accordance with ASTM D4703. Measurements should be made in accordance with ASTM D792, Method B within one hour of sample pressing.

[0089] Melting point Melting points (Tm) should be measured using Differential Scanning Calorimetry (DSC). Differential Scanning Calorimetry (DSC) can be measured on a DSC, such as a TA Instruments Q1000 DSC equipped with an RCS cooling attachment and an autosampler. Melting points (Tm) of samples should be measured according to ASTM D3418.

[0090] Heat Seal Measurement Heat seal measurements on films should be performed on a commercially available tensile tester according to ASTM F-88 (Technique A). The heat seal test is a gauge of the strength of the seal (seal strength) of flexible barrier materials. It is performed by measuring the force required to separate a test strip of material containing the seal and identifies the mode of failure of the specimen. Seal strength is related to the opening force and package integrity. Prior to cutting, the film was conditioned for a minimum of 40 hours at 23°C (±2°C) and 50% (±5%) RH (relative humidity) according to ASTM D-618 (Procedure A). Sheets are then cut machine-wise from the 3-layer coextruded laminate film to a length of approximately 11 inches and a width of approximately 8.5 inches. Sealing pressure or dwell force 0.138 N / mm 2 The sheets are heat sealed in the machine direction on a Brugger HSG-C sealer over a range of temperatures under conditions of (20 psi) and dwell times of 0.3 and 0.5 seconds.

[0091] Sealing may be performed in a Brugger HSG-C sealer with a 0.5 second dwell time and a seal bar pressure of 210 N. Sealed specimens may be tested in an Instron Tensiomer at 10 in / min (4.2 mm / sec or 250 mm / min).

[0092] Hot Tack Terms such as "hot tack strength" refer to the strength of a heat seal formed between thermoplastic surfaces of a flexible web immediately after the seal is made and before it is cooled to ambient temperature. In form-fill operations, the sealed area of ​​the package is often subjected to destructive forces while still hot. If the hot seal does not adequately resist these forces, failure may occur during the packaging process. Hot tack strength, also known as hot seal strength, is a measure for characterizing and ranking materials for their ability to perform in commercial applications where this quality is important. Hot tack strength may be measured as follows according to ASTM F1921:

[0093] Hot tack initiation temperature refers to the temperature at which the hot tack strength is at least a certain threshold strength. For example, the hot tack initiation temperature can be determined at 1.0 N / 15 mm.

[0094] Several embodiments are described in this disclosure. A first embodiment may be a multilayer structure including: (a) a machine direction oriented (MDO) multilayer film, comprising (i) a metal layer and (ii) an inner layer in adhesive contact with the metal layer, the inner layer comprising ethylene vinyl alcohol, polyvinyl alcohol, or both; or a blend of polyethylene and an interpolymer of ethylene and methyl acrylate, ethyl acrylate, or carboxylic acid; (b) a first layer extruded onto the metal layer of the machine direction oriented multilayer film, the first layer comprising an interpolymer of ethylene and acrylic acid or methacrylic acid, the interpolymer having a melt index (I2) of 5 to 20 g / 10 min, an acid content of 1 to 10 weight percent, and a melt temperature of 90°C to 100°C; and (c) a sealant layer in adhesive contact with the first layer, the sealant layer comprising polyethylene having a melt index (I2) of 3 to 30 g / 10 min and a heat seal initiation temperature of 95°C or less.

[0095] Alternative embodiments may include any other previously disclosed embodiment in which the metal layer is a metallization layer comprising an oxide of aluminum or silicon.

[0096] Another embodiment can include any other previously disclosed embodiment in which the interpolymer of the first layer is a terpolymer of ethylene, acrylic acid or methacrylic acid, and an alkyl acrylate.

[0097] Alternative embodiments can include any other previously disclosed embodiment where the interpolymer of the first layer comprises 50 to 98 weight percent ethylene.

[0098] Alternative embodiments may include any other previously disclosed embodiment in which the sealant layer comprises 15 to 40 weight percent low density polyethylene, based on the total weight of the sealant layer.

[0099] Alternative embodiments may include any other previously disclosed embodiment, where the sealant layer further comprises 60 to 85 weight percent of a propylene-based plastomer having a density of 0.890 g / cc or less and a melt flow rate of at least 8 g / 10 min (at 230° C. and 2.16 kg).

[0100] Alternative embodiments may include any other previously disclosed embodiment, wherein the sealant layer further comprises 60 to 85 weight percent of at least one polyethylene having a density of 0.870 g / cc to 0.911 g / cc and a melt index (I2) of at least 3 g / 10 min.

[0101] Alternative embodiments can include any other previously disclosed embodiment in which the MDO multilayer film has one or more polyethylene layers.

[0102] Another aspect may include an article comprising the multi-layer structure of any of the previously disclosed aspects, hi another embodiment, the article is a pouch.

[0103] It should also be noted that descriptions herein of "at least one" component, element, etc. should not be used to create an inference that the alternative use of the article "a" or "an" should be limited to a single component, element, etc.

[0104] Although the subject matter of the present disclosure has been described in detail and by reference to certain embodiments thereof, it should be noted that various details disclosed herein should not be interpreted as meaning that these details relate to elements that are essential components of the various embodiments described herein, even if a particular element is shown in each of the drawings accompanying this description. Moreover, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, including but not limited to the embodiments defined in the appended claims. More specifically, although certain aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

[0105] It should be noted that one or more of the claims that follow utilize the term "wherein" as a transitional phrase. It should be noted that for purposes of defining the invention, this term is introduced in the claims as an open-ended transitional phrase used to introduce a recitation of a series of features of a structure, and should be interpreted in a similar manner to the more commonly used open-ended preamble term "comprising."

Claims

1. A multilayer structure comprising: (a) a machine direction oriented (MDO) multilayer film comprising: (i) a metal layer; and (ii) an inner layer in adhesive contact with the metal layer, the inner layer comprising: ethylene vinyl alcohol, polyvinyl alcohol, or both; or an MDO multilayer film comprising a blend of polyethylene and an interpolymer of ethylene and methyl acrylate, ethyl acrylate, or a carboxylic acid; (b) a first layer extruded onto the metal layer of the machine direction oriented multilayer film, the first layer comprising an interpolymer of ethylene and acrylic acid or methacrylic acid, the interpolymer having a melt index (I) of 5 to 20 g / 10 min; ２ a first layer having an acid content of 1 to 10 weight percent and a melting temperature of 90°C to 100°C; (c) a sealant layer in adhesive contact with the first layer, the sealant layer having a melt index (I) of 3 to 30 g / 10 min. ２ a sealant layer comprising a polyethylene having a heat seal initiation temperature of 95°C or less; A multilayer structure comprising:

2. 10. The multilayer structure of claim 1, wherein the metal layer is a metallized layer comprising an oxide of aluminum or silicon.

3. 10. The multilayer structure of claim 1, wherein the interpolymer of the first layer is a terpolymer of ethylene, acrylic acid or methacrylic acid, and an alkyl acrylate.

4. 10. The multilayer structure of claim 1, wherein the interpolymer of the first layer comprises 50 to 98 weight percent ethylene.

5. 10. The multi-layer structure of claim 1, wherein the sealant layer comprises 15 to 40 weight percent low density polyethylene, based on the total weight of the sealant layer.

6. 10. The multilayer structure of claim 1, wherein the sealant layer further comprises 60 to 85 weight percent of a propylene-based plastomer having a density of 0.890 g / cc or less and a melt flow rate of at least 8 g / 10 min (at 230° C. and 2.16 kg).

7. The sealant layer comprises 60 to 85 weight percent of a cellulose ester having a density of 0.870 g / cc to 0.911 g / cc and a melt index (I) of at least 3 g / 10 min. ２ 10. The multilayer structure of claim 1, further comprising at least one polyethylene having a carboxylic acid group.

8. 10. The multilayer structure of claim 1, wherein the MOD multilayer film comprises one or more polyethylene layers.

9. An article comprising the multilayer structure of any one of claims 1 to 8.

10. The article of claim 9, wherein the article is a pouch.