WO2020190507A1

WO2020190507A1 - Multilayer oriented films

Info

Publication number: WO2020190507A1
Application number: PCT/US2020/020949
Authority: WO
Inventors: Xirui WANG; Etienne R.H. LERNOUX
Original assignee: Exxonmobil Chemical Patents Inc.
Priority date: 2019-03-19
Filing date: 2020-03-04
Publication date: 2020-09-24

Abstract

The present disclosure provides multilayer films including: a first layer including a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, where the first layer is substantially free of polymers having a density of 0.908 or less; a second layer including a polyolefin, the second layer disposed on the first layer; and a third layer including a polyethylene composition including a propylene- based elastomer, the third layer disposed on the second layer, and the multilayer film has a haze of about 10% or less.

Description

MULTILAYER ORIENTED FILMS

CROSS REFERNCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 62/820,706, filed March 19, 2019 and entitled“Multilayer Oriented Films,” the disclosure of which is hereby incorporated by reference in its entirety.

FIELD

[0002] This present disclosure relates to films, and in particular, to novel multilayer films with balanced physical and optical properties, and methods for making such films.

BACKGROUND

[0003] Polymer films have found utility in a wide variety of packaging and other applications. The polymer films used in packaging are generally transparent multilayer films comprised of two or more polymers which generally include polyethylene (PE), polypropylene (PP), ethylene vinyl alcohol (EVA), polyethylene terephthalate (PET), polyamides (Nylons) and other similar polymers. Currently many of the packaging films on the market are made by combining PE layers and layers made from materials like PET or Nylons to provide desirable physical properties.

[0004] Multilayer film properties can be dependent on the combined effect of the coextrusion process conditions, polymer compositions, and post-extrusion processing or stretching. In order to address requirements of particular end-uses, film producers balance mechanical properties such as stiffness and impact strength to make stronger films for a given thickness and optical properties such as clarity, haze, and gloss which impact the attractiveness of the packaging and visual inspection of the goods at the point of sale.

[0005] Also, because the margins of many packaging products can be narrow, the cost of the packaging material is ideally kept to a minimum. Therefore, thinner films are often desirable because fewer source materials are used and the cost per item decreases. However, the downgauging (making thinner) of polymer films is typically associated with a loss of stiffness or toughness and therefore a loss of utility in packaging.

[0006] One way to downgauge a film is by a stretching (also referred to as directional orientation, drawing, directionally orienting, or orienting) process. Directional orientation is a post-extrusion process in which an extruded film is heated and stretched in one or more directions. Generally, single direction stretching takes place in the machine direction (MD) or perpendicular to the machine direction: the transverse direction (TD) and biaxial stretching takes place in both the machine and transverse directions. The stretching process has been shown to improve film properties including modulus, barrier, tensile strength, and optics. For films stretched in a single direction (uniaxially oriented) certain properties are directional in nature and are measured in the direction of stretching (DS), which could be in the MD or TD. Another advantage to stretching a film is downgauging the thickness of the film which lowers the amount of source material and the number of processing steps to produce polymer films.

[0007] One method to produce an oriented multilayer film for packaging includes producing a bubble through the blown process, flattening the bubble, heating the flattened bubble to a temperature lower than the melting point of the skins, stretching the flattened bubble in the machine direction, annealing the stretched flattened bubble, separating the two parts of the annealed bubble after orientation and winding the two separated parts resulting in a stretched multilayer film. However, it has been viewed as a difficulty by film manufacturers of various applications to develop an oriented multilayer film comprised substantially of polyethylene for this and similar processes. In particular, reaching good optical and physical properties while avoiding blocking or, in other words, keeping the ability to separate the two parts of the flattened bubble, has been a challenge. In order to compensate for blocking, blown extrusion processes for the multilayer film typically have a high density polymer or anti-blocking additives on the interior of the bubble or for the bubble to undergo cooling before it is collapsed.

[0008] Another method of compensating for blocking issues in blown films is to make the layer on the interior of the bubble of a material that will adhere completely to itself when the bubble is collapsed, to achieve perfect blocking. The blocked structure becomes a single film which is then oriented to produce a thinner film. The blocking may be aided by the addition of lower density polymers or elastomers to the interior layers. Moreover, lower density polyethylene in the outer layer may improve optical properties.

[0009] Directional orientation may be limited by polymer or polymer mixture type because mixtures of certain polymers may cause cavitation during the orientation process. Cavitation can cause a loss of clarity or gloss and an increase in haze. Cavitation can occur when a mixture of immiscible polymers is stretched and is caused when one polymer forms a region that does not stretch at the same rate as the rest of the film which creates a discontinuity in the film that increases in size during stretching. These microscopic spaces increase the opacity of a film which is desirable in some applications, but generally undesirable in the packaging industry. For example, directional orientation of mixtures of polypropylenes with polyethylene are frequently plagued with cavitation issues and are, therefore, not commonly used to prepare multilayer films for use in packaging. [0010] In balancing the processability and the optical properties, blown film manufacturers may desire to achieve complete blocking (complete sealing of two- sides of a collapsed bubble) while also producing a film with desirable optical properties (reduced or eliminated cavitation) and maintaining a well-balanced overall film performance. There is a need to further improve multilayer films by providing alternative film formulations which can provide a desired combination of processability (including compensating for blocking), and physical and optical properties (e.g. clarity, gloss, stiffness, and toughness).

SUMMARY

[0011] The present disclosure provides stretched multilayer films including a first layer, a second layer disposed on the first layer, and a third layer disposed on the second layer. The first layer includes a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater, (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater, or (iii) a mixture thereof, where the first layer is substantially free of polymers having a density of about 0.908 g/cc or less. The second layer includes a polyolefin. The third layer includes a polyethylene composition including a propylene -based elastomer. The multilayer film has a haze of about 10% or less.

[0012] The present disclosure also provides stretched multilayer films including: (a) a first layer including a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, wherein the first layer is free of polymers having a density of about 0.908 g/cc or less; (b) a second layer including a polyolefin, the second layer disposed on the first layer; (c) a third layer including a polyethylene composition including a propylene-based elastomer, the third layer disposed on the second layer; (d) a fourth layer including a polyethylene composition of substantially the same chemical composition as the polyethylene composition of the third layer, the fourth layer disposed on the third layer; (e) a fifth layer including a polyolefin of substantially the same chemical composition as the polyolefin of the second layer, the fifth layer disposed on the fourth layer; and (f) a sixth layer including a polyethylene of substantially the same chemical composition as the polyethylene of the first layer, the sixth layer disposed on the fifth layer, where the stretched multilayer film has a haze of about 10% or less.

[0013] The present disclosure also provides a method for preparing a stretched multilayer film including: extruding a first layer, a second layer disposed on the first layer, and a third layer disposed on the second layer, where the first layer includes a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater, (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater, or (iii) a mixture thereof, where the first layer is free of polymers having a density of about 0.908 g/cc or less, the second layer includes a polyolefin, and the third layer includes a polyethylene composition including a propylene-based elastomer. The method includes stretching the multilayer film in a uniaxial direction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The Figure is a graph comparing the percent haze, gloss and clarity various multilayer films, according to one embodiment.

DETAILED DESCRIPTION

[0015] The present disclosure fulfils the need for additional polymer film formulations with a balance of optical properties and physical properties while also fulfilling the need to avoid incomplete blocking known to blown film formation processes. Applicant has found that a stretched multilayer film with desired physical properties can be achieved by the combination of addition of a propylene-based elastomer to a given layer or layers in a polyethylene multilayer film, and directional orientation of the unstretched multilayer film. The addition of propylene elastomer(s) to multilayer polyethylene films in conjunction with stretching can provide balanced optical properties and mechanical properties, and can furthermore reduce or eliminate incomplete blocking. The mixture of polypropylene and polyethylene in blown films may cause cavitation during directional orientations and decrease the gloss and clarity of a film. However, it has been discovered that the addition of certain propylene-based elastomers to polyethylene multilayer films does not promote cavitation, despite immiscibility of the different polyolefins. The lack of cavitation caused by addition of a propylene -based elastomer to a polyethylene layer allows for production of a multilayer film made substantially from polyethylene with great optical properties, including low haze and high clarity. Another possible added benefit is that resulting multi-layer films composed substantially from polyethylene are recyclable in a single collection stream.

[0016] Blocking occurs when a bubble in a blown film process is collapsed and opposing sides bond to one another. In order to compensate for blocking issues, it is common in blown extrusion processes for the multilayer film to have a high density polymer and/or anti- blocking additive on the interior of the bubble, or for the bubble to undergo cooling before it is collapsed. Another method of compensating for blocking issues in blown films is to make the layer on the interior of the bubble of a material with that will adhere completely to itself when the bubble is collapsed, e.g. U.S. Patent No. 6,413,346. [0017] The present disclosure demonstrates that use of propylene-based elastomers in the interior of the bubble of a blown film can reduce or eliminate incomplete blocking by allowing opposing layers in a collapsed bubble to adhere to each other without reducing the balance between processability and optical properties in a multilayer film. Therefore, a multilayer film containing propylene-based elastomers offers promising alternatives for future development in the coextruded multilayer film industry, allowing the film manufacturer to adjust overall film performance achievable by adjusting copolymer or polyethylene blend distribution between different layers. Although the use of propylene- based elastomers in layers containing polyethylene could cause cavitation, it has been discovered that addition of propylene-based elastomers, having one or more advantageous properties, to polyethylene layers does not cause cavitation or a loss of clarity in blown films. Definitions

[0018] As used herein, a“polymer” may be used to refer to homopolymers, copolymers, interpolymers, terpolymers, etc. A“polymer” has two or more of the same or different monomer units. A“homopolymer” is a polymer having monomer units that are the same. A “copolymer” is a polymer having two or more monomer units that are different from each other. A“terpolymer” is a polymer having three monomer units that are different from each other. The term“different” as used to refer to monomer units indicates that the monomer units differ from each other by at least one atom or are different isomerically. Accordingly, the definition of copolymer, as used herein, includes terpolymers and the like. Likewise, the definition of polymer, as used herein, includes copolymers and the like.

[0019] Thus, as used herein, the terms “polyolefin,” “olefinic copolymer,” and “polyolefin component” mean a polymer or copolymer including olefin units of about 50 mol% or greater, about 70 mol% or greater, about 80 mol% or greater, about 90 mol% or greater, about 95 mol% or greater, or 100 mol% (in the case of a homopolymer). Polyolefins include homopolymers or copolymers of C to C olefins, e.g. a copolymer of an a-olefin and another olefin or a-olefin (ethylene is defined to be an a-olefin). Some examples of polyolefins include homopolyethylene, homopolypropylene, propylene copolymerized with ethylene and/or butene, ethylene copolymerized with one or more of propylene, butene or hexene, and optional dienes. Other examples include thermoplastic polymers such as ultra- low density polyethylene, very low density polyethylene, linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, isotactic polypropylene, highly isotactic polypropylene, syndiotactic polypropylene, random copolymer of propylene and ethylene and/or butene and/or hexene, elastomers such as ethylene propylene rubber, ethylene propylene diene monomer rubber, neoprene, and compositions of thermoplastic polymers and elastomers, such as, for example, thermoplastic elastomers and rubber toughened plastics. The method of producing the polyolefin is not critical, it can be produced by slurry, solution, gas phase, high pressure or other suitable processes, and by using catalyst systems appropriate for the polymerization of polyolefins, such as Ziegler-Natta-type catalysts, chromium catalysts, metallocene-type catalysts, other appropriate catalyst systems or combinations thereof, or by free-radical polymerization.

[0020] As used herein, the terms “polyethylene,” “ethylene polymer,” “ethylene copolymer,”“polyethylene component” and“ethylene based polymer” mean a polymer or copolymer including ethylene units of about 50 mol% or greater, about 70 mol% or greater, about 80 mol% or greater, about 90 mol% or greater, about 95 mol% or greater, or 100 mol% (in the case of a homopolymer). Furthermore, the term“polyethylene composition” means a composition containing one or more polyethylene components where the sum of ethylene monomers is greater than 50 wt%. The polyethylene compositions described herein may be physical blends or in situ blends of more than one type of polyethylene or compositions of polyethylenes with polymers other than polyethylenes.

[0021] As used herein, when a polymer is referred to as including a monomer, the monomer is present in the polymer in the polymerized form of the monomer or in the derivative form of the monomer.

[0022] As used herein, when a polymer is said to include a certain percentage, e.g. wt%, of a monomer, that percentage of monomer is based on the total weight amount of monomer units in the polymer.

[0023] Unless otherwise specified, the term“elastomer” as used herein, refers to a polymer or composition of polymers consistent with the ASTM D1566 definition.

[0024] For purposes of the present disclosure, an ethylene polymer having a density of 0.910 g/cm³ to 0.940 g/cm³ is referred to as a“low density polyethylene” (LDPE); an ethylene polymer having a density of 0.890 g/cm³ to 0.940 g/cm³, that is linear and does not contain a substantial amount of long-chain branching is referred to as“linear low density polyethylene” (LLDPE) and can be produced with suitable Ziegler-Natta catalysts, vanadium catalysts, or with metallocene catalysts in gas phase reactors, high pressure tubular reactors, and/or in slurry reactors and/or with any of the disclosed catalysts in solution reactors (“linear” means that the polyethylene has no or only a few long-chain branches, typically referred to as a g'_ViS of 0.97 or above, 0.98 or above); and an ethylene polymer having a density of more than 0.940 g/cm is referred to as a“high density polyethylene” (HDPE).

[0025] As used herein,“first” layer,“second” layer, and“third” layer (etc.) are merely identifiers used for convenience, and shall not be construed as limitation on individual layers, their relative positions, or the multi-layer structure, unless otherwise specified herein.

[0026] “Disposed on” may mean disposed directly on or disposed indirectly on, unless otherwise specified.

[0027] As used herein, stretch ratio in a uniaxial direction is the ratio of a film dimension before stretching to that film dimension after stretching in said uniaxial direction. This is stated, for example, as a stretch ratio of 4, where 4 represents the film length after stretching relative to a film of unit length before stretching, e.g., the film has been stretched to 4 times the original length. Orientation refers to the alignment of polymer chains in the film.

[0028] As used herein, a“multilayer film” may include a stretched or unstretched multilayer film, unless otherwise specified

Propylene-based Elastomer

[0029] In an embodiment, the propylene-based elastomer is a random copolymer having crystalline regions interrupted by non-crystalline regions and from about 5 wt% to about 25 wt%, by weight of the propylene-based elastomer, of ethylene or C to Cio a-olefin derived units, and optionally diene-derived units, the remainder of the polymer being propylene- derived units. Not intended to be limited by any theory, it is believed that the non-crystalline regions may result from regions of non-crystallizable polypropylene segments and/or the inclusion of comonomer units. The crystallinity and the melting point of the propylene-based elastomer are reduced compared to highly isotactic polypropylene by the introduction of errors (stereo and regio defects) in the insertion of propylene and/or by the presence of comonomer. In an embodiment, the propylene-based elastomer is a propylene -based elastomer having limited crystallinity due to adjacent isotactic propylene units and a melting point as described herein. In other embodiments, the propylene-based elastomer is generally devoid of substantial intermolecular heterogeneity in tacticity and comonomer composition, and also generally devoid of substantial heterogeneity in intramolecular composition distribution.

[0030] The propylene-based elastomer can contain about 50 wt% or greater, about 60 wt% or greater, about 65 wt% or greater, about 75 wt% or greater, or about 99 wt% or less propylene-derived units, based on the total weight of the propylene-based elastomer. In some embodiments, the propylene-based elastomer includes propylene monomer incorporation in an amount based on the weight of propylene-based elastomer of from about 75 wt% to about 95 wt%, about 75 wt% to about 92.5 wt%, and about 82.5 wt% to about 92.5 wt%, and about 82.5 wt% to about 90 wt%. Correspondingly, the units, or comonomers, derived from at least one of ethylene or a C₄ to C o a-olefin may be present in an amount of about 5 wt%, about 10 wt%, or about 14 wt% to about 22 wt%, or about 25 wt% by weight of the elastomer.

[0031] The comonomer content of the propylene-based elastomer may be adjusted to vary the physical properties including: heat of fusion, melting point (T_m), crystallinity, and melt flow rate (MFR).

[0032] The propylene-based elastomer may include more than one comonomer. In at least one embodiment, a propylene-based elastomer may have more than one comonomer including propylene-ethylene-octene, propylene-ethylene-hexene, and propylene-ethylene- butene terpolymers.

[0033] In embodiments where more than one comonomers derived from at least one of ethylene or a C₄ to C o a-olefins are present, the amount of each comonomer may be about 5 wt% or less of the propylene -based elastomer, but the combined amount of comonomers by weight of the propylene-based elastomer is about 5 wt% or greater.

[0034] In another embodiment, the comonomer is ethylene, 1-hexene, or 1-octene, in an amount of about 5 wt%, about 10 wt%, or about 14 wt% to about 22 wt%, or about 25 wt% by weight based on the weight of the propylene-based elastomer.

[0035] In one or more embodiments, the propylene-based elastomer can include ethylene- derived units. The propylene-based elastomer may include of about 5 wt%, about 10 wt%, or about 14 wt% to about 22 wt%, or about 25 wt% of ethylene-derived units by weight of the propylene -based elastomer. In another embodiment, the propylene -based elastomer consists essentially of units derived from propylene and ethylene, meaning that the propylene -based elastomer does not contain any other comonomer in an amount greater than typically present as impurities in the ethylene and/or propylene feedstreams used during polymerization or an amount that would materially affect the heat of fusion, melting point, crystallinity, or melt flow rate of the propylene-based elastomer, or any other comonomer intentionally added to the polymerization process.

[0036] In one or more embodiments, diene comonomer units are included in the propylene -based elastomer. Examples of the diene include, but not limited to, 5-ethylidene- 2-norbornene, 5-vinyl-2-norbomene, divinylbenzene, 1,4-hexadiene, 5-methylene-2- norbornene, 1 ,6-octadiene, 5-methyl-l, 4-hexadiene, 3, 7-dimethyl- 1,6-octadiene, 1,3- cyclopentadiene, 1 ,4-cyclohexadiene, dicyclopentadiene, or a combination thereof. The amount of diene comonomer can be from about 0 wt%, about 0.5 wt%, about 1 wt%, or about 1.5 wt% to about 5 wt%, about 4 wt%, about 3 wt % or about 2 wt% based on the weight of propylene -based elastomer.

[0037] Propylene-based elastomers may be synthesized according to U.S. Patent No. 7,390,866.

Propylene-based Elastomer Properties

[0038] In an embodiment, the propylene-based elastomer has a heat of fusion

as determined by the Differential Scanning Calorimetry (“DSC”), of about 100 J/g or less, about 75 J/g or less, about 70 J/g or less, about 50 J/g or less, or about 35 J/g or less. In another embodiment, the propylene-based elastomer may have an H_f of about 0.5 J/g or greater, about 1 J/g or greater, or about 5 J/g of greater. For example, the H_f value may be anywhere from about 1 J/g, about 1.5 J/g, about 3 J/g, about 4 J/g, about 6 J/g, or about 7 J/g, to about 30 J/g, about 35 J/g, about 40 J/g, about 50 J/g, about 60 J/g, about 70 J/g, or about 75 J/g.

[0039] The propylene-based elastomer may have a percent crystallinity, as determined according to the DSC procedure described herein, of from about 0.25%, about 0.5 %, about 1%, about 2% or about 5% to about 65%, about 40%, about 35%, or about 30%, of isotactic polypropylene.

[0040] In an embodiment, the propylene-derived units of the propylene-based elastomer have an isotactic triad fraction of about 50% to about 99%, about 65% to about 97%, and about 75% to about 97%. In at least one embodiment, the first polymer has a triad tacticity as measured by ¹³C NMR, of about 75% or greater, about 80% or greater, about 82% or greater, about 85% or greater, or about 90% or greater. The triad tacticity of a polymer is the relative tacticity of a sequence of three adjacent propylene units, a chain consisting of head to tail bonds, expressed as a binary combination of m and r sequences. It is usually expressed as the ratio of the number of units of the specified tacticity to all of the propylene triads in the first polymer. The triad tacticity (mm fraction) of a propylene copolymer can be determined from a ¹³C NMR spectrum of the propylene copolymer. The calculation of the triad tacticity is described in U.S. Patent No. 5,504,172.

[0041] The propylene-based elastomer may have a single peak melting transition as determined by DSC. In any embodiment, the copolymer has a primary peak transition of 90°C or less, with a broad end-of-melt transition of 110°C or greater. The peak“melting point” (“T_m”) is defined as the temperature of the greatest heat absorption within the range of melting of the sample. However, the copolymer may show secondary melting peaks adjacent to the principal peak, and/or at the end-of-melt transition. For the purposes of this disclosure, such secondary melting peaks are considered together as a single melting point, with the highest of these peaks being considered the T„, of the propylene-based elastomer. The propylene -based elastomer may have a T„, of about 100°C or less, about 90°C or less, about 80°C or less, or about 70°C or less. In an embodiment, the propylene-based elastomer has a T_m of about 25°C to about 100°C, about 25°C to about 85°C, about 25°C to about 75°C, or about 25°C to about 65°C. In one or more embodiments, the propylene -based elastomer has a T„, of about 30°C to about 80°C, about 30°C to about 70°C.

[0042] For the thermal properties of the propylene -based elastomers, Differential Scanning Calorimetry (“DSC”) can be used. Such DSC data can be obtained using a Perkin - Elmer DSC, where 7.5 mg to 10 mg of a sheet of the polymer to be tested can be pressed at approximately 200°C to 230°C, then removed with a punch die and annealed at room temperature for 48 hours. The samples can then be sealed in aluminum sample pans. The DSC data can be recorded by first cooling the sample to -50°C and then gradually heating it to 200°C at a rate of 10°C/min. The sample can be kept at 200°C for 5 minutes before a second cooling-heating cycle is applied. Both the first and second cycle thermal events are recorded. Areas under the melting curves are measured and used to determine the heat of fusion and the degree of crystallinity. The percent crystallinity (X%) is calculated using the formula, X% = [area under the curve (Joules/gram)/B(Joules/gram)]*100, where B is the heat of fusion for the homopolymer of the major monomer component. These values for B are found from the Polymer Handbook, Fourth Edition, published by John Wiley and Sons, New York 1999. A value of 189 J/g (B) is used as the heat of fusion for 100% crystalline polypropylene. The melting temperature is measured and reported during the second heating cycle (or second melt).

[0043] In an embodiment, the propylene-based elastomer may have a Mooney viscosity [ML (1+4) @ 125°C], as determined according to ASTM D-1646, of about 100 or less, about 75 or less, about 60 or less, or about 30 or less.

[0044] The propylene-based elastomer may have a density of about 0.850 g/cm³ to about 0.920 g/cm³, about 0.860 g/cm³ to about 0.900 g/cm³, about 0.860 g/cm³ to about 0.890 g/cm³, at room temperature as measured per ASTM D-1505.

[0045] The propylene-based elastomer has a melt flow rate (“MFR”) of about 0.5 g/10 min or greater, and about 1,000 g/10 min or less, about 800 g/10 min or less, about 500 g/10 min or less, about 200 g/10 min or less, about 100 g/10 min or less, about 50 g/10 min or less. Some embodiments include a propylene-based elastomer with an MFR of about 25 g/10 min or less, such as from about 1 g/10 min to about 25 g/10 min, about 1 g/10 min to about 20 g/10 min. The MFR is determined according to ASTM D-1238, condition L (2.16 kg, 230°C).

[0046] The propylene-based elastomer may have a weight average molecular weight (“Mw”) of about 5,000 g/mole to about 5,000,000 g/mole, about 10,000 g/mole to about 1,000,000 g/mole, or about 50,000 g/mole to about 400,000 g/mole; a number average molecular weight (“Mn”) of about 2,500 g/mole to about 2,500,00 g/mole, about 10,000 g/mole to about 250,000 g/mole, or about 25,000 g/mole to about 200,000 g/mole; and/or a z- average molecular weight (“Mz”) of about 10,000 g/mole to about 7,000,000 g/mole, about 80,000 g/mole to about 700,000 g/mole, or about 100,000 g/mole to about 500,000 g/mole. The propylene-based elastomer may have a molecular weight distribution (Mw/Mn, or “MWD”) of about 1.5 to about 20, about 1.5 to about 15, about 1.5 to about 5, about 1.8 to about 5, or about 1.8 to about 4.

[0047] The propylene-based elastomer may have an Elongation at Break of about 2000% or less, about 1000% or less, or about 800% or less, as measured per ASTM D412.

Commercial examples of such propylene-based elastomers includes Vistamaxx™ propylene- based elastomers from ExxonMobil Chemical Company, Tafmer™ elastomers from Mitsui Chemicals, and Versify™ elastomers from Dow Chemical Company. For Example:

Vistamaxx™ 6102 resin has an MI of 1.4 g/10 min. and density of 0.862 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

Vistamaxx™ 3000 resin has an MI of 3.7 g/10 min. and density of 0.873 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

Versify™ 3300 resin has an MI of 8 g/10 min. and a density of 0.891 g/cm³, and is commercially available from DOW Chemical Company, Midland, Michigan.

Tamfer™ DF740 resin has an MFR of 3.6 g/10 min. and a density of 0.87 g/cm³, and is commercially available from Mitsui Chemicals, Tokyo, Japan.

Propylene-based Elastomer Production

[0048] The method of making the propylene-based elastomer can be by slurry, solution, gas phase, high pressure or other suitable processes, and by using catalyst systems appropriate for the polymerization of polyethylenes, such as Ziegler-Natta-type catalysts, chromium catalysts, metallocene-type catalysts, other appropriate catalyst systems or combinations thereof, or by free-radical polymerization. Propylene-based elastomers may be produced using mono- or bis-cyclopentadienyl transition metal catalysts in combination with an activator of alumoxane and/or a non-coordinating anion in solution, slurry, high pressure or gas phase. The catalyst and activator may be supported or unsupported and the cyclopentadienyl rings may be substituted or unsubstituted. In an embodiment, the propylene -based elastomers are made as described in U.S. Patent No. 7,390,866.

Polyethylenes

[0049] In one aspect of the present disclosure, a polyethylene that can be used for the multilayer film made according to a method of the present disclosure is selected from an ethylene homopolymer, and ethylene copolymer, or a composition thereof. Useful copolymers include one or more comonomers in addition to ethylene and can be a random copolymer, a statistical copolymer, a block copolymer, and/or compositions thereof.

[0050] Polyethylenes may include those sold by ExxonMobil Chemical Company in Houston Tex., including HDPE, LLDPE, and LDPE; and those sold under the trade names ENABLE”, EXACT”, EXCEED”, ESCORENE”, EXXCO”, ESCOR”, PAXON”, and OPTEMA” (ExxonMobil Chemical Company, Houston, Texas, USA); DOW”, DOWLEX”, ELITE”, AFFINITY”, ENGAGE”, and FLEXOMER” (The Dow Chemical Company, Midland, Michigan, USA); BORSTAR” and QUEO” (Borealis AG, Vienna, Austria); and TAFMER” (Mitsui Chemicals Inc., Tokyo, Japan).

[0051] Example LLDPEs include linear low density polyethylenes having comonomer content from about 0.5 wt% to about 20 wt%, the comonomer derived from C to C a- olefins, e.g. 1 -butene or 1 -hexene. In various embodiments, the density of LLDPEs are from 0.890 g/cm³ to 0.940 g/cm³, from about 0.910 g/cm³ to about 0.930 g/cm³, or from about 0.912 g/cm³ to about 0.925 g/cm³. The MI of such LLDPEs can be about 0.1 g/10 min, about 0.2 g/10 min, or about 0.4 g/10 min to about 4 g/10 min, about 6 g/10 min, or about 10 g/10 min. LLDPEs are distinct from LDPEs which are polymerized by free radical initiation and which contain a high amount of long chain branching resulting from backbiting reaction mechanisms that do not occur in catalytic polymerization as used for LLDPE which favors chain end incorporation of monomers. In at least one embodiment, the LLDPEs are made using a single site (often metallocene) catalyst, in a gas phase or solution process. The use of a single site catalyst, even if supported on a catalyst support, such as silica, can lead to improved homogeneity of the polymer, such as an MWD from about 2 to about 4. In another embodiment, the LLDPEs are made using multi-site titanium based Ziegler Natta catalysts, in a gas phase or solution process. Generally LLDPE made from Zeigler Natta catalysts can be considered as having a broad compositional distribution with a CDBI of about 50% or less. LLDPEs may have an MWD determined according to the procedure disclosed herein of about 5 or less. In another embodiment, a layer may contain more than one type of LLDPE.

[0052] Example LDPEs include ethylene based polymers produced by free radical initiation at high pressure in a tubular or autoclave reactor. The LDPEs have a medium to broad MWD determined according to the procedure disclosed herein of about 4 or greater, or from about 5 to about 40, and a high level of long chain branching as well as some short chain branching. The density is generally about 0.910 g/cm³ or greater, such as from about 0.920 g/cm³ to about 0.940 g/cm³. The MI may be about 0.55 g/10 min or less or about 0.45 g/10 min or less. In the present disclosure, a layer may contain more than one type of LDPE.

[0053] Example HDPEs include high density polyethylenes having comonomer content from about 0.01 wt% to about 5 wt%, the comonomer derived from C to C a-olefins, e.g. 1- butene or 1 -hexene, and in certain embodiments is a homopolymer of ethylene. In various embodiments, the density of HDPEs are from about 0.940 g/cm³ to about 0.970 g/cm³, from about 0.945 g/cm³ to about 0.965 g/cm³, or from about 0.950 g/cm³ to about 0.965 g/cm³. The MI of such HDPEs is from about 0.1 g/10 min, about 0.2 g/10 min, or about 0.4 g/10 min to about 4 g/10 min, about 6 g/10 min, or about 10 g/10 min. The HDPEs are typically prepared with either Ziegler-Natta or chromium-based catalysts in slurry reactors, gas phase reactors, or solution reactors. In the present disclosure, a layer may contain more than one type of HDPE.

[0054] Suitable commercial polymers for an HDPE may include those sold by

ExxonMobil Chemical Company in Houston Tex., including HDPE HD and HDPE HTA and those sold under the trade names PAXON” (ExxonMobil Chemical Company, Houston, Texas, USA); CONTINUUM™, DOW”, DOWLEX”, and UNIVAL™ (The Dow Chemical Company, Midland, Michigan, USA). Commercial HDPE is available with a density range such as 0.94 g/cm³ to 0.963 g/cm³ and melt index (U s) range such as 0.06 g/10 min. to 33 g/10 min. Example HDPE polymers include:

ExxonMobil” HDPE HTA 108 resin has an MI of 0.70 g/10 min and density of 0.961 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

- PAXON” AA60-003 resin has an MI of 0.25 g/10 min and density of 0.963 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas. CONTINUUM” DMDA-1260 resin has an MI of 2.7 g/10 min and density of 0.963 g/cm³, and is commercially available from Dow Chemical Company, Midland, Michigan.

UNIVAL” DMDA-6147 resin has an MI of 10 g/10 min and density of 0.948 g/cm³, and is commercially available from Dow Chemical Company, Midland,

Michigan.

[0055] In at least one embodiment, the polyethylene is an ethylene copolymer, either random or block, of ethylene and one or more comonomers selected from C to C linear, branched or cyclic monomers, often C to C a-olefins. Such polymers may have about 20 wt% or less, about 10 wt% or less, about 5 wt% or less, about 1 wt% or less, or from about 1 wt% to about 20 wt%, about 1 wt% to about 15 wt%, about 1 wt% to about 12.5 wt%, about 1 wt% to about 10 wt%, about 1 wt% to about 7.5 wt%, about 1 wt% to about 5 wt%, about 1 wt% to about 3 wt%, about 0.1 wt% to about 2 wt%, about 0.1 wt% to about 1 wt%, about 0.5 wt% to about 1 wt% of polymer units derived from one or more comonomers.

[0056] In at least one embodiment, the polyethylene includes propylene units of about 20 mol% or less, about 15 mol% or less, about 10 mol% or less, about 5 mol% or less, or about 0 mol% propylene units.

[0057] In some embodiments the comonomer is a C to C linear or branched alpha- olefin, e.g. 1 -butene, 1-pentene, 1 -hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1- dodecene, 4-methyl- 1-pentene, 3-methyl- 1-pentene, 3, 5, 5 -trimethyl- 1 -hexene, and 5-ethyl-l- nonene.

[0058] In certain embodiments, aromatic-group-containing monomers contain up to 30 carbon atoms. Suitable aromatic-group-containing monomers include at least one aromatic structure, from one to three aromatic structures, or a phenyl, indenyl, fluorenyl, or naphthyl moiety. The aromatic-group-containing monomer further includes at least one polymerizable double bond such that after polymerization, the aromatic structure will be pendant from the polymer backbone. The aromatic-group containing monomer may further be substituted with one or more hydrocarbyl groups including but not limited to C to C alkyl groups. Additionally, two adjacent substitutions may be joined to form a ring structure. In some embodiments, aromatic-group-containing monomers contain at least one aromatic structure appended to a polymerizable olefinic moiety. Examples of aromatic monomers include styrene, alpha-methylstyrene, para-alkylstyrenes, vinyl toluenes, vinylnaphthalene, allyl benzene, and indene; more specific examples include styrene, paramethyl styrene, 4-phenyl- 1 -butene and allyl benzene. [0059] Diolefin monomers may include any hydrocarbon structure, e.g. a

having at least two unsaturated bonds, where at least two of the unsaturated bonds are readily incorporated into a polymer by either a stereospecific or a non- stereospecific catalyst(s). The diolefin monomers may be selected from alpha, omega-diene monomers (e.g., di-vinyl monomers). The diolefin monomers may be linear di-vinyl monomers, containing from 4 to 30 carbon atoms. Examples of dienes include butadiene, pentadiene, hexadiene, heptadiene, octadiene, nonadiene, decadiene, undecadiene, dodecadiene, tridecadiene, tetradecadiene, pentadecadiene, hexadecadiene, heptadecadiene, octadecadiene, nonadecadiene, icosadiene, heneicosadiene, docosadiene, tricosadiene, tetracosadiene, pentacosadiene, hexacosadiene, heptacosadiene, octacosadiene, nonacosadiene, triacontadiene, other example dienes include 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11- dodecadiene, 1,12-tridecadiene, 1,13-tetradecadiene, and low molecular weight polybutadienes (Mw less than 1000 g/mol). Example cyclic dienes include cyclopentadiene, vinylnorbornene, norbomadiene, ethylidene norbomene, divinylbenzene, dicyclopentadiene, or higher ring containing diolefins with or without substituents at various ring positions.

[0060] In some embodiments, one or more dienes are present in the polyethylene at about 10 wt% or less, such as about 0.00001 wt% to about 2 wt%, about 0.002 wt% to about 1 wt%, about 0.003 wt% to about 0.5 wt%, based upon the total weight of the polyethylene. In some embodiments, diene is added to the polymerization in an amount of from about 500 ppm, about 400 ppm, or about 300 ppm to about 50 ppm, about 100 ppm, or about 150 ppm.

[0061] Polyethylene copolymers can include about 50 wt% or more ethylene and have a C to C comonomer, C to Gs comonomer, 1 -hexene or 1-octene comonomer wt% of about 50 wt% or less, such as about 10 wt% or less, about 1 wt% or less, from about 1 wt% to about 30 wt%, or about 1 wt% to about 5 wt%, based upon the weight of the copolymer.

[0062] The polyethylene may include from about 70 mol% to 100 mol% of units derived from ethylene. The lower value on the range of ethylene content may be from about 70 mol%, about 75 mol%, about 80 mol%, about 85 mol%, about 90 mol%, about 92 mol%, about 94 mol%, about 95 mol%, about 96 mol%, about 97 mol%, about 98 mol%, or about 99 mol% based on the mol% of polymer units derived from ethylene. The polyethylene may have an upper ethylene value of about 80 mol%, about 85 mol%, about 90 mol%, about 92 mol%, about 94 mol%, about 95 mol%, about 96 mol%, about 97 mol%, about 98 mol%, about 99 mol%, about 99.5 mol%, about 99.9 mol% or 100 mol%, based on polymer units derived from ethylene. For polyethylene copolymers, the polyethylene copolymer may have about 50 mol% or less of polymer units derived from a comonomer, e.g. C -C olefins or alpha-olefins. The lower value on the range of comonomer content may be about 25 mol%, about 20 mol%, about 15 mol%, about 10 mol%, about 8 mol%, about 6 mol%, about 5 mol%, about 4 mol%, about 3 mol%, about 2 mol%, about 1 mol%, about 0.5 mol% or about 0.1 mol%, based on polymer units derived from the comonomer. The upper value on the range of comonomer content may be about 30 mol%, about 25 mol%, about 20 mol%, about 15 mol%, about 10 mol%, about 8 mol%, about 6 mol%, about 5 mol%, about 4 mol%, about 3 mol%, about 2 mol%, or about 1 mol%, based on polymer units derived from the comonomer olefin. Any of the lower values may be combined with any of the upper values to form a range. Comonomer content is based on the total content of all monomers in the polymer.

Polyethylene Properties

[0063] Polyethylene homopolymers and copolymers can have one or more of the following properties:

(a) a weight average molecular weight (Mw) of about 15,000 g/mol or more, from about 15,000 to about 2,000,000 g/mol, from about 20,000 to about 1,000,000 g/mol, from about 25,000 to about 800,000 g/mol, from about 30,000 to about 750,000 g/mol, from about 150,000 to about 400,000 g/mol, from about 200,000 to about 350,000 g/mol as measured by size exclusion chromatography;

(b) a z-average molecular weight (Mz) to weight average molecular weight (Mw) (Mz/Mw) ratio about 1.5 or greater, about 1.7 or greater, or about 2 or greater. In some embodiments, this ratio is from about 1.7 to about 3.5, from about 2 to about 3, or from about 2.2 to about 3 where the Mz is measured by sedimentation in an analytical ultra-centrifuge;

(c) a T_m of about 30°C to about 150°C, about 30°C to about 140°C, about 50°C to about 140°C, or about 60°C to about 135°C, as determined based on ASTM D3418-03;

(d) a crystallinity of about 5% to about 80%, about 10% to about 70%, about 20% to about 60%, about 30% or greater, about 40% or greater, or about 50% or greater, as determined based on ASTM D3418-03;

(e) a percent amorphous content of from about 40%, about 50%, about 60%, or about 70% to about 95%, about 70%, about 60%, or about 50% as determined by subtracting the percent crystallinity from 100;

(f) a heat of fusion of about 300 J/g or less, about 1 to about 260 J/g, about 5 to about 240 J/g, or about 10 to about 200 J/g, as determined based on ASTM D3418-03; (g) a crystallization temperature (T_c) of about 15°C to about 130°C, about 20°C to about 120°C, about 25°C to about 110°C, or about 60°C to about 125°C, as determined based on ASTM D3418-03;

(h) a heat deflection temperature of about 30°C to about 120°C, about 40°C to about 100°C, or about 50°C to about 80°C as measured based on ASTM D648 on injection molded flexure bars, at 66 psi load (455 kPa);

(i) a shore hardness (D scale) of about 10 or more, about 20 or more, about 30 or more, about 40 or more, about 10 or less, or from about 25 to about 75 as measured based on ASTM D 2240;

(j) a density from about 0.9 g/cm³, about 0.905 g/cm³, about 0.910 g/cm³, about

0.912 g/cm³, about 0.915 g/cm³, about 0.918 g/cm³, about 0.92 g/cm³, about 0.925 g/cm³ about 0.93 g/cm³, or about 0.94 g/cm³ to about 0.95 g/cm³, about 0.94 g/cm³, 0.935 g/cm³, about 0.93 g/cm³, about 0.925 g/cm³, about 0.923 g/cm³, about 0.921 g/cm³, about 0.92 g/cm³, or about 0.918 g/cm³, or a density of about 0.94 g/cm³ or greater as measured in accordance with ASTM D-4703 and ASTM D- 1505/ISO 1183;

(k) a melt index (MI or E s) from about 0.05 g/10 min, about 0.1 g/10 min, about 0.15 g/10 min, about 0.18 g/10 min, about 0.2 g/10 min, about 0.22 g/10 min, about 0.25 g/10 min, about 0.28 g/10 min, about 0.3 g/10 min, about 0.5 g/10 min, about 0.7 g/10 min, about 1 g/10 min, or about 2 gr/10 min, to about 800 g/10 min, about 100 g/10 min, about 50 g/10 min, about 30g/10 min, about 15 g/10 min about 10 g/10 min, about 5 g/10 min, about 3 g/10 min, about 2 g/10 min, about 1.5 g/10 min, about 1.2 g/10 min, about 1.1 g/10 min, about 1 g/10 min, about 0.7 g/10 min, about 0.5 g/10 min, about 0.4 gr/10 min, about 0.3 g/10 min, or about 0.2 gr/10 min, or about 0.1 g/10 min, as measured by ASTM D-1238-E (190°C/2.16 kg);

(1) a melt index ratio (MIR) of from about 10 to about 100, from about 15 to about

80, from about 10 to about 50, from about 16 to about 50, from about 15 to about 45, from about 20 to about 40, from about 20 to about 35, from about 22 to about 38, from about 20 to about 32, from about 25 to about 31, or from about 28 to about 30 as measured by ASTM D- 1238-E (190°C/2.16 kg) and (190°C, 21.6 kg) the ratio of I₂. (190°C, 21.6 kg)/L· . (190°C, 2.16 kg);

(m) a composition distribution breadth index (“CDBI”) of about 100% or less, about 90% or less, about 85% or less, about 75% or less, about 5% to about 85%, or about 10% to 75%. The CDBI may be determined using techniques for isolating individual fractions of a sample of the resin, most commonly Temperature Rising Elution Fraction (“TREF”), as described in Wild et al., J. Poly. Sci., Poly. Phys. Ed., Vol. 20, p. 441 (1982);

(n) a molecular weight distribution (MWD) or (Mw/Mn) of about 40 or less, such as from about 1.5 to about 20, from about 1.8 to about 10, from about 1.9 to about 5, from about 1.5 to about 5.5, from about 1.5 to about 5, from about 2 to about 5, from about 2 to about 4, from about 3 to about 4.5, or from about 2.5 to about 4. MWD is measured using a gel permeation chromatograph (“GPC”) on a Waters 150 gel permeation chromatograph equipped with a differential refractive index (“DRI”) detector and a Chromatix KMX-6 on line light scattering photometer. The system is used at 135°C with 1,2,4-trichlorobenzene as the mobile phase using Shodex (Showa Denko America, Inc.) polystyrene gel columns 802, 803, 804, and 805. This technique is discussed in“Liquid Chromatography of Polymers and Related Materials III,” J. Cazes editor, Marcel Dekker, 1981, p. 207. Polystyrene is used for calibration. No corrections for column spreading are employed; however, data on generally accepted standards, e.g., National Bureau of Standards Polyethylene 1484 and anionically produced hydrogenated polyisoprenes (alternating ethylene-propylene copolymers demonstrate that such corrections on MWD are less than 0.05 units). Mw/Mn is calculated from elution times. The numerical analyses are performed using the commercially available Beckman/CIS customized LALLS software in conjunction with the standard Gel Permeation package. Reference to Mw/Mn implies that the Mw is the value reported using the LALLS detector and Mn is the value reported using the DRI detector described above;

(o) a branching index of about 0.85 or greater, about 0.9 or greater, about 0.95 or greater, about 0.97 or greater, about 0.98 or greater, about 0.985 or greater, about 0.99 or greater, about 0.995 or greater, or about 1. Branching Index is an indication of the amount of branching of the polymer and is defined as

g'=[Rg]²br[Rg]²im.

where “Rg” stands for Radius of Gyration and is measured using a Waters 150 gel permeation chromatograph equipped with a Multi- Angle Laser Light Scattering (“MALLS”) detector, a viscosity detector and a differential refractive index detector. “[RgV’ is the Radius of Gyration for the branched polymer sample and“| Rg|i_m" is the Radius of Gyration for a linear polymer sample; and/or

(p) an amount of long chain branching of about 2 long-chain branch/1000 carbon atoms or less, about 1 long-chain branch/1000 carbon atoms or less, about 0.5 long-chain branch/1000 carbon atoms or less, from about 0.05 to about 0.50 long-chain branch/1000 carbon atoms. Such values are characteristic of a linear structure that is consistent with a branching index (as defined above) of g'_ViS about 0.85 or greater, about 0.9 or greater, about 0.95 or greater, about 0.97 or greater, about 0.98 or greater, about 0.985 or greater, about 0.99 or greater, about 0.995 or greater, or about 1. Various methods are suitable for determining the presence of long-chain branches. For example, long-chain branching can be determined using ¹³C nuclear magnetic resonance (NMR) spectroscopy and to a limited extent; e.g., for ethylene homopolymers and for certain copolymers, and it can be quantified using the method of Randall ( Journal of Macromole cular Science, Rev. Macromol. Chem. Phys. , C29 (2&3), p. 285-297). Although conventional ¹³C NMR spectroscopy cannot determine the length of a long-chain branch in excess of about six carbon atoms, there are other suitable techniques useful for quantifying or determining the presence of long-chain branches in ethylene-based polymers, such as ethylene/l-octene interpolymers. For those ethylene -based polymers where the ¹³C resonances of the comonomer overlap completely with the ¹³C resonances of the long-chain branches, either the comonomer or the other monomers (such as ethylene) can be isotopically labelled so that the long-chain branches can be distinguished from the comonomer. For example, a copolymer of ethylene and 1-octene can be prepared using ¹³C-labeled ethylene. In this case, the resonances associated with macromer incorporation will be significantly enhanced in intensity and will show coupling to neighboring ¹³C carbons, whereas the octene resonances will be unenhanced.

Additional Polyethylene Embodiments

[0064] In at least one embodiment, the polyethylene is a first type of LLDPE (PEI -type) having about 99 wt% to about 80 wt%, about 99 wt% to about 85 wt%, about 99 wt% to about 87.5 wt%, about 99 wt% to about 90 wt%, about 99 wt% to about 92.5 wt%, about 99 wt% to about 95 wt%, or about 99 wt% to about 97 wt%, of polymer units derived from ethylene and about 1 wt% to about 20 wt%, about 1 wt% to about 15 wt%, about 1 wt% to about 12.5 wt%, about 1 wt% to about 10 wt%, about 1 wt% to about 7.5 wt%, about 1 wt% to about 5 wt%, or about 1 wt% to about 3 wt% of polymer units derived from one or more C to C a-olefin comonomers, such as C to C o a-olefins, C to Gs a-olefins, or hexene and octene. The a-olefin comonomer may be linear or branched, and two or more comonomers may be used, if desired. Examples of suitable comonomers include propylene, butene, 1- pentene; 1-pentene with one or more methyl, ethyl, or propyl substituents; 1-hexene; 1- hexene with one or more methyl, ethyl, or propyl substituents; 1-heptene; 1-heptene with one or more methyl, ethyl, or propyl substituents; 1-octene; 1-octene with one or more methyl, ethyl, or propyl substituents; 1-nonene; 1-nonene with one or more methyl, ethyl, or propyl substituents; ethyl, methyl, or dimethyl-substituted 1-decene; 1-dodecene; and styrene. [0065] The PEI -type polyethylene may have a composition distribution breadth index (CDBI) of about 70% or greater, such as about 75% or greater, about 80% or greater, about 82% or greater, about 85% or greater, about 87% or greater, about 90% or greater, about 95% or greater, or about 98% or greater. Additionally or alternatively, the CDBI may be about 100% or less, such as about 98% or less, about 95% or less, about 90% or less, about 87% or less, about 85% or less, about 82% or less, about 80% or less, or about 75% or less. Ranges expressly disclosed include, but are not limited to, ranges formed by combinations any of the above-enumerated values, e.g., about 70% to about 98%, about 80 to about 95%, about 85 to about 90% etc.

[0066] A PEl-type polyethylene may have a density about 0.918 g/cm³ or greater, about 0.920 g/cm³ or greater, about 0.922 g/cm³ or greater, about 0.928 g/cm³ or greater, about 0.930 g/cm³ or greater, about 0.932 g/cm³ or greater. Additionally, a PEl-type polyethylene may have a density of about 0.945 g/cm³ or less, about 0.940 g/cm³ or less, about 0.937 g/cm³ or less, about 0.935 g/cm³ or less, about 0.933 g/cm³ or less, or about 0.930 g/cm³ or less Ranges expressly disclosed include, but are not limited to, ranges formed by combinations any of the above-enumerated values, e.g., about 0.920 g/cm³ to about 0.945 g/cm³, about 0.920 g/cm³ to about 0.930 g/cm³, about 0.925 g/cm³ to about 0.935 g/cm³, about 0.920 g/cm³ to about 0.940 g/cm³, etc.

[0067] A PEl-type polyethylene can be a metallocene polyethylene (mPE). The PE1- type polyethylene may have a g'_vis of from about 0.85 to about 0.98, such as from about 0.87 to about 0.97, about 0.89 to about 0.97, about 0.91 to about 0.97, about 0.93 to about 0.95, about 0.97 to about 0.99, about 0.97 to about 0.98, or about 0.95 to about 0.98.

[0068] Suitable commercial polymers for the PEl-type polyethylene are available from ExxonMobil Chemical Company in Baytown, Texas under the trade name Enable”. Polyethylene polymers known as Enable” mPE available from ExxonMobil Chemical Company, Houston, Texas, offer a combination of polymer film processing advantages and higher alpha olefin (HAO) performance. A balance of operational stability, extended output, versatility with HAO performance, and resin sourcing simplicity are among some of the advantageous properties of this family of polyethylene polymers. Commercial Enable” mPE is available with a density range such as 0.920 g/cm³ to 0.935 g/cm³ and melt index (T s) range such as 0.3 g/10 min. to 1.0 g/10 min. Other Enable” polymers include:

Enable” 2703HH metallocene polyethylene (mPE) resin has an MI of 0.30 g/10 min. and density of 0.927 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas. Enable” 2705MC metallocene polyethylene (mPE) resin has an MI of 0.50 g/10 min and density of 0.927 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

Enable” 3505MC metallocene polyethylene (mPE) resin has an MI of 0.50 g/10 min and density of 0.935 g/cm³, and is commercially available from ExxonMobil

Chemical Company, Houston, Texas.

Enable” 4002MC metallocene polyethylene (mPE) resin has an MI of 0.25 g/10 min and a density of 0.94 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

- Enable” 4009MC metallocene polethylene (mPE) resin has an MI of 0.9 g/10 min and a density of 0.94 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

[0069] In at least one embodiment, the polyethylene a second type of LLDPE (PE2- type)polyethylene including about 50 wt % or greater of polymer units derived from a C₃ to C₂₀ alpha-olefin comonomer (e.g. hexene or octene) of about 50 wt % or less, such as about 1 wt% to about 35 wt%, or about 1 wt% to about 6 wt%. PE2-type polyethylenes can have a CDBI of about 60% or greater, such as about 60% to about 80%, or about 65% to about 80%. The PE2-type polyethylene may have a density of about 0.910 g/cm³ to about 0.950 g/cm³, about 0.915 g.cm³ to about 0.940 g/cm³, or about 0.918 g/cm³ to about 0.925 g/cm³. PE2-type polyethylenes may have a melt index (L s) according to ASTM D1238 (190°C/2.16 kg) of about 0.5 g/10 min to about 5 g/10 min, or about 0.8 g/10 min to about 1.5 g/10 min. A PE2- type polyethylene can be an mPE. Such PE2-type polyethylenes can have a gT of about 0.97 or greater, about 0.98 or greater and can be a prepared by gas-phase polymerization supported catalyst with an bridged bis(alkyl-substituted dicyclopentadienyl) zirconium dichloride transition metal component and methyl alumoxane cocatalyst. PE2-type polyethylenes are available from ExxonMobil Chemical Company under the trade name Exceed™ and Exceed” XP.

[0070] Polyethylene polymers known as Exceed” and Exceed” XP mPE available from ExxonMobil Chemical Company, Houston, Texas, offer a combination of high toughness and outstanding tensile strength. A balance of impact strength, tear strength, flex-crack resistance, and melt-strength are among some of the advantageous properties of this family of polyethylene polymers. Commercial Exceed” mPE is available with a density range such as 0.91 g/cm³ to 0.925 g/cm³ and melt index (T s) range such as 0.2 g/10 min. to 19 g/10 min. Other Exceed™ polymers include: Exceed™ XP 8656 metallocene polyethylene (mPE) resin has an MI of 0.5 g/10 min and a density of 0.916 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

Exceed” 1018 metallocene polyethylene (mPE) resin has an MI of 1 g/10 min and a density of 0.918 g/cm³, and is commercially available from ExxonMobil Chemical

Company, Houston, Texas.

Exceed” XP 8784 metallocene polyethylene (mPE) resin has an MI of 0.8 g/10 min and a density of 0.914 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

- Exceed” 1012HA metallocene polyethylene (mPE) resin has an MI of 1 g/10 min and a density of 0.912 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

Exceed” 2012HA metallocene polyethylene (mPE) resin has an MI of 2.0 g/10 min and a density of 0.912 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston.

Polyethylene Production

[0071] The method of making the polyethylene is not critical, as it can be made by slurry, solution, gas phase, high pressure or other suitable processes, and by using catalyst systems appropriate for the polymerization of polyethylenes, such as Ziegler-Natta-type catalysts, chromium catalysts, metallocene-type catalysts, other appropriate catalyst systems or combinations thereof, or by free-radical polymerization. Polyethylene homopolymers or copolymers that can be used may be produced using mono- or bis-cyclopentadienyl transition metal catalysts in combination with an activator of alumoxane and/or a non-coordinating anion in solution, slurry, high pressure or gas phase. The catalyst and activator may be supported or unsupported and the cyclopentadienyl rings may be substituted or unsubstituted. In an embodiment, the polyethylenes are made by the catalysts, activators and processes described in U.S. Patent Nos. 5,466,649; 5,741,563; 6,255,426; 6,342,566; 6,384,142; 6,476,171; and 7,951,873; and WO Publication Nos. 2004/022646 and 2004/022634, 2003/040201 and 1997/19991. Such catalysts are described in, for example, ZIEGLER CATALYSTS (Gerhard Fink, Rolf Miilhaupt and Hans H. Brintzinger, eds., Springer-Verlag 1995 5); Resconi et al.; and I, II METALLOCENE-BASED POLYOLEFINS (Wiley & Sons 2000).

[0072] In at least one embodiment of the present disclosure, the polyethylene is produced by polymerization of ethylene and, optionally, an alpha-olefin with a catalyst having, as a transition metal component, a bis (n-C₃ alkyl cyclopentadienyl) hafnium compound, where the transition metal component includes from about 95 mol% to about 99 mol% of the hafnium compound as further described in U.S. Pat. No. 6,956,088.

[0073] In another embodiment, the polyethylene is produced by gas-phase polymerization of ethylene with a catalyst having as a transition metal component a bis(n-C₃ alkyl cyclopentadienyl) hafnium compound, where said transition metal component includes from about 95 mol% to about 99 mol% of said hafnium compound.

[0074] In a class of embodiments, the polyethylene may contain less than 5 ppm hafnium, less than 2 ppm hafnium, less than 1.5 ppm hafnium, or less than 1 ppm hafnium. In other embodiments, the polyethylene polymers may contain from about 0.01 ppm to about 2 ppm hafnium, from about 0.01 ppm to about 1.5 ppm hafnium, or from about 0.01 ppm to about 1 ppm hafnium.

[0075] Typically, the amount of hafnium is greater than the amount of zirconium in the polyethylene polymer. In a class of embodiments, the ratio of hafnium to zirconium (ppm/ppm) is about 2 or more, about 10 or more, about 15 or more, about 17 or more, about

20 or more, about 25 or more, about 50 or more, about 100 or more, about 200 or more, or about 500 or more. While zirconium generally is present as an impurity in hafnium, it will be realized in some embodiments where particularly pure hafnium-containing catalysts are used, the amount of zirconium may be extremely low, resulting in a virtually undetectable or undetectable amount of zirconium in the polyethylene polymer. Thus, the upper value on the ratio of hafnium to zirconium in the polymer may be quite large.

Multilayer Films

[0076] The multilayer film includes a first layer, a second layer disposed on the first layer, and a third layer disposed on the second layer; each of the first layer, the second layer, and the third layer including a polyolefin polymer, optionally mixed with a polyethylene polymer or other polymers or additives. A stretched multilayer film is directionally oriented, and when uniaxially oriented it is stretched at a ratio of about 1:3 or greater.

[0077] The multilayer film may have a 1/2/3 structure where 1 is a first layer and 3 is a third layer and 2 is a second layer that is disposed between the first layer and the third layer. Suitably one or both of the first layer and the third layer are an outermost layer forming one or both film surfaces. Either of the polyolefin of the first layer and the polyolefin of the third layer layers may have a higher or lower density than the polyolefin of the second layer. In at least one embodiment, at least one of the polyolefins of the first layer and the polyolefin of the third layer has a density lower than the polyolefin of the second layer. [0078] The multilayer film may have a 1/2/3/3/2/1 structure where 1 is an outer layer and 3 has adhered to itself (complete blocking) when the bubble of the blown film is collapsed. In an embodiment, the addition of propylene-based elastomer to the third layer produces complete blocking of two identical films forming one multilayer film. In an embodiment, a laminate can be formed from a single blown film. In such embodiments, the inner surface of the blown film can collapse and block to itself to form a multilayer film having a thickness approximately twice the thickness of the blown film prior to forming the collapsed bubble multilayer film. In another embodiment, the 1/2/3/3/2/1 structure is produced by lamination of a 1/2/3 film to a 3/2/1 film.

[0079] The multilayer film may have a 1/3/3/1 structure where the second layer is not present and where 1 is an outer layer and a 3 layer has sealed to the other 3 layer when the bubble of the blown film is collapsed and blocked. In an embodiment, the addition of propylene -based elastomer to the third layer produces complete blocking of two identical films forming one multilayer film. In an embodiment, a laminate can be formed from a single blown film. In such embodiments, the inner surface of the blown film can collapse and adhere to itself to form a multilayer film having a thickness approximately twice the thickness of the blown film prior to forming the collapsed and blocked bubble multilayer film. In another embodiment, the 1/3/3/1 structure is produced by lamination of a 1/3 multilayer film to a 3/1 multilayer film.

[0080] The multilayer film may have a 1/4/2/5/3 structure where 1 and 3 are outer layers and 2 represents a central or core layer and 4 and 5 are inner layers disposed between the central layer and an outer layer. The composition of the fourth layer and the fifth layer may be the same or different. The first layer may have the same composition or a different composition from the fourth layer and the fifth layer. In at least one embodiment, at least one of the fourth layer and fifth layer has a different composition than that of the first layer. In another embodiment, the fourth layer and the fifth layer have substantially the same chemical composition and are different from the first layer. In another embodiment, the first layer, the fourth layer and the fifth layer have substantially the same chemical composition.

[0081] The multilayer film may have a 1/4/2/5/3/3/5/2/4/1 structure where 1 is an outer layer and a 3 layer has sealed to the other 3 layer when the bubble of the blown film is collapsed. In an embodiment, the addition of propylene-based elastomer to the third layer produces complete blocking of two identical films forming one multilayer film. In an embodiment, a laminate can be formed from a single blown film. In such embodiments, the inner surface of the blown film can collapse and seal on itself to form a multilayer film having a thickness approximately twice the thickness of the blown film prior to forming the collapsed and blocked multilayer film. In another embodiment, the 1/4/2/5/3/3/5/2/4/1 structure is produced by lamination of a 1/4/2/5/3 multilayer film to a 3/5/2/4/1 multilayer film.

[0082] In at least one embodiment, the LLDPE, LDPE, and HDPE present in a given layer may be optionally in a blend with one or more other polymers, such as polyethylenes defined herein, which blend is referred to as polyethylene composition as defined above. In some embodiments, the polyethylene composition is a blend of two polyethylenes with different densities.

[0083] In at least one embodiment, the polyethylene composition is an EH copolymer blended with a second polyethylene. The polyethylene may be the same as or different from the EH copolymer. In an embodiment where the polyethylene is different from the EH copolymer in a polyethylene composition, the polyethylene homopolymer in the homopolymer: copolymer blend may be present in an amount of about 50 wt% or less, about 45 wt% or less, about 40 wt% or less, about 35 wt% or less, about 30 wt% or less, about 25 wt% or less, about 20 wt% or less, about 15 wt% or less, about 10 wt% or less, or about 5 wt% or less, based on the total weight of polymer in the polyethylene composition.

[0084] In at least one embodiment, the polyethylene composition is a propylene-based elastomer blended with a polyethylene. In an embodiment, the polyethylene composition includes a propylene-based elastomer in an amount of about 50 wt% or less, about 45 wt% or less, about 40 wt% or less, about 35 wt% or less, about 30 wt% or less, about 25 wt% or less, about 20 wt% or less, about 15 wt% or less, or about 10 wt% or less, and about 1 wt% or greater, or about 5 wt% or greater, such as about 1 wt% to about 50 wt%, about 5 wt% to about 45 wt%, about 10 wt% to about 40 wt%, about 15 wt% to about 35 wt%, or about 25 wt% to about 35 wt% based on the total weight of polymer in the polyethylene composition.

[0085] In at least one embodiment, the first layer of the multilayer film includes about 90 wt% of an EH copolymer and about 10 wt% of LLDPE or LDPE, based on the total weight of polymers in the first layer. In another embodiment, the multilayer film includes in each of the fourth layer and the fifth layer 100 wt% of a HDPE, based on total weight of polymer in the fourth layer and the fifth layer.

[0086] In at least one embodiment, the polyolefin of the second layer of a multilayer film includes 100 wt% HDPE, LDPE, or LLDPE, based on the total weight of polymer in the second layer. In another embodiment, the polyolefin of the second layer of a multilayer film includes a polyethylene composition including 100 wt% EH copolymer, based on the total weight of polymer in the second layer. In at least one embodiment, the polyolefin of the second layer of a multilayer film includes a polyethylene composition including an EH copolymer and HDPE. In at least one embodiment, the polyolefin of the second layer of a multilayer film includes a polyethylene composition including about 40% or greater, such as about 40 wt% to about 90 wt%, about 45 wt% to about 80 wt%, about 50 wt% to about 75 wt%, about 55 wt% to about 70 wt%, or about 55 wt% to about 65 wt% of an EH copolymer and about 60 wt% or less, such as about 10 wt% to about 60 wt%, about 15 wt% to about 50 wt%, about 20 wt% to about 50 wt%, about 30 wt% to about 50 wt%, or about 35 wt% to about 45 wt% of an HDPE, based on the total weight of polymer in the second layer. In another embodiment, the polyolefin of the second layer of a multilayer film includes a polyethylene composition including about 60 wt% of an EH copolymer and about 40 wt% of an HDPE, based on the total weight of polymer in the second layer. In another embodiment, the second layer of a multilayer film includes a polyethylene, having a density of about 0.910 g/cm³ to about 0.945 g/cm³, an MI, I_{2 ie}, of about 0.1 g/10 min to about 15 g/10 min, an MWD of about 1.5 to about 5.5, and an MIR, E s/E s, of about 10 to about 100.

[0087] In at least one embodiment, the third layer of the multilayer film includes a polyethylene composition including a propylene-based elastomer and any of (i) a polyethylene, (ii) a polyethylene copolymer, and (iii) an EH copolymer. In another embodiment, the third layer of the multilayer film includes about 40% or greater, such as about 40 wt% to about 90 wt%, about 45 wt% to about 85 wt%, about 50 wt% to about 80 wt%, about 60 wt% to about 80 wt%, or about 65 wt% to about 75 wt% of a polyethylene copolymer and about 60 wt% or less, such as about 10 wt% to about 60 wt%, about 15 wt% to about 50 wt%, about 20 wt% to about 45 wt%, or about 25 wt% to about 40 wt%, or about 25 wt% to about 35 wt% of a propylene-based elastomer, based on total weight of polymer in the third layer. In an embodiment, the polyethylene copolymer is an EH copolymer.

[0088] In at least one embodiment, each of the first layer, the second layer, and the third layer of a multilayer film include a polyethylene or polyethylene composition. In at least one embodiment, at least one of LLDPE, LDPE, and HDPE is present in the second layer and the polyethylene present in the first layer and/or the third layer is an EH copolymer.

[0089] In at least one embodiment, a multilayer film has a three-layer 1/2/3 structure, including: (a) a first layer including about 50% or greater, such as about 50 wt% to about 99 wt%, about 60 wt% to about 98 wt%, about 70 wt% to about 95 wt%, about 80 wt% to about 95 wt%, or about 85 wt% to about 95 wt% of an EH copolymer and about 50 wt% or less, such as about 1 wt% to about 50 wt%, about 2 wt% to about 40 wt%, about 5 wt% to about 30 wt%, or about 5 wt% to about 20 wt%, or about 5 wt% to about 15 wt% of an LDPE, based on total weight of polymer in the first layer, where the EH copolymer has a density of about 0.910 to about 0.945 g/cm³, an MI ( b d, of about 0.1 to about 15 g/10 min, and MWD of about 1.5 to about 5.5; (b) a second layer disposed between the first layer and the third layer, including at least one of LLDPE, LDPE and HDPE in an amount of at least about 30 wt%, based on total weight of polymer in the second layer, and (c) a third layer disposed on the second layer including a polyethylene composition including an EH copolymer and at least 5 wt% of a propylene-based elastomer.

[0090] In at least one embodiment, the multilayer film has a five layer 1/4/2/5/3 structure, including: (a) a first layer including an EH copolymer, where the EH copolymer has a density of about 0.910 to about 0.945 g/cm³; (b) a second layer disposed on the first layer including an EH copolymer, where the EH copolymer has a density of about 0.910 to about 0.945 g/cm³; (c) a third layer, disposed on the second layer, including a polyethylene composition including an EH copolymer and, such as about 5 wt% to about 60 wt%, about 10 wt% to about 50 wt%, about 15 wt% to about 45 wt%, or about 20 wt% to about 40 wt%, or about 25 wt% to about 35 wt% of a propylene-based elastomer; (d) a fourth layer, disposed between the first layer and the second layer, including at least one of LLDPE, LDPE and HDPE in an amount of about 60 wt% or less, such as about 10 wt% to about 60 wt%, about 15 wt% to about 50 wt%, about 20 wt% to about 45 wt%, or about 25 wt% to about 40 wt%, or about 25 wt% to about 35 wt%, based on total weight of polymer in the second layer; and (e) a fifth layer, disposed between the second layer and the third layer, including at least one of LLDPE, LDPE and HDPE in an amount of about 10 wt% or greater, such as about 10 wt% to about 60 wt%, about 15 wt% to about 50 wt%, about 20 wt% to about 45 wt%, or about 25 wt% to about 40 wt%, or about 25 wt% to about 35 wt%, based on total weight of polymer in the fifth layer.

[0091] In another embodiment, the multilayer film includes in the fourth layer and the fifth layer at least one of LLDPE, LDPE and HDPE, the LLDPE, LDPE, HDPE or any combination thereof may be present in an amount of about 30 wt% or greater, for example, anywhere from about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt%, about 50 wt%, about 55 wt%, or about 60 wt%, to about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt%, about 90 wt%, about 95 wt%, or about 100 wt%, based on the total weight of polymer in the layer. Any of the polymers of the first layer, the fourth layer, or the fifth layer may have a higher or lower density than the polyolefin of the second layer. In at least one embodiment, at least one of the polymers of the first layer, the fourth layer or the fifth layer has a density lower than the polyolefin of the second layer.

[0092] The unstretched multilayer films can have an original thickness of about 40 pm to about 360 pm, such as about 50 pm to about 300 pm, or about 60 pm to about 200 pm. After stretching, the final thickness of the stretched multilayer film (uniaxially or biaxially oriented films) may be from about 5 pm to about 120 pm, such as about 10 pm to about 60 pm, or about 15 pm to about 45 pm. For the three-layer structure the first layer, the second layer and the third layer may be of equal thickness or alternatively the second layer may be thicker than each of the first layer and the third layer. In at least one embodiment, a multilayer film includes a first layer and a third layer which each independently forms about 10% to about 35%, or about 15% to about 30% of the total final thickness of the 3-layered film, the second layer forming the remaining thickness, e.g. about 30% to about 80%, or about 40% to about 70% of the total final thickness of the 3-layered film. The total thickness of the film is 100%, thus the sum of the individual layers has to be 100%.

[0093] For the multilayer film of 1/4/2/5/3 structure the individual layers can contribute to the total film thickness of the multilayer film in a variety of ways, for example:

about 10% to about 30%, or about 15% to about 25% independently for each of the first layer and the third layer, about 5% to about 30%, or about 8% to about 20% independently for each of the fourth layer and the fifth layer, and/or about 10% to about 40%, or about 15% to about 35% for the second layer.

[0094] In some embodiments, the first layer, the third layer, the fourth layer, and the fifth layer are of equal thickness. In some embodiments, the first layer, the second layer and the third layer are of equal thickness. In at least one embodiment, the second layer, the fourth layer, and the fifth layer are of equal thickness. In another embodiment, the second layer has a thickness greater than any of the other layers.

[0095] The multilayer film may further include additional layer(s), which may be any layer typically included in multilayer films. These additional layers may include barrier coatings that are added before or after stretching. Layers that provide barrier enhancement is a feature of interest in packaging application. Additional layers may be added through any suitable method including, co-extrusion, extrusion coating, solid sublimation, or solvent or water based coatings. For example, the additional layer(s) may be made from:

1. Polyolefins. As described above for the second layer.

2. Polar polymers. Polar polymers include homopolymers and copolymers of esters, amides, acetates, anhydrides, copolymers of a C to C olefin, such as ethylene and/or propylene and/or butene with one or more polar monomers, such as acetates, anhydrides, esters, alcohol, and/or acrylics. Examples include polyesters, polyamides, ethylene vinyl acetate copolymers, and polyvinyl chloride.

3. Cationic polymers. Cationic polymers include polymers or copolymers of geminally disubstituted olefins, a-heteroatom olefins and/or styrenic monomers. Geminally disubstituted olefins include isobutylene, isopentene, isoheptene, isohexane, isooctene, isodecene, and isododecene. a-Heteroatom olefins include vinyl ether and vinyl carbazole. Styrenic monomers include styrene, alkyl styrene, para-alkyl styrene, a-methyl styrene, chloro-styrene, and bromo-para-methyl styrene. Examples of cationic polymers include butyl rubber, isobutylene copolymerized with para methyl styrene, polystyrene, and poly-a-methyl styrene.

4. Miscellaneous. Other layers can be paper, wood, cardboard, metal, metal foils (such as aluminum foil and tin foil), metallized surfaces, glass (including silicon oxide (SiOx) or aluminum oxide (AlOx) coatings applied by evaporating SiOx or AlOx onto a film surface), fabric, spunbond fibers, and non-wovens (including polypropylene spunbond fibers or non- wovens), and substrates coated with inks, dyes, pigments, and the like.

[0096] As an example, a multilayer film can also include layers including materials such as ethylene vinyl alcohol (EVOH), polyamide (PA), polyvinylidene chloride (PVDC), or aluminium, so as to alter barrier performance for the film where appropriate.

[0097] A stretched multilayer film is directionally oriented in form (the form after the film has undergone stretching in a uniaxial or biaxial direction) and may be useful for laminating to materials having less elasticity than polyethylene films, such as, biaxially oriented polyester (e.g., polyethylene terephthalate (PET)) films, biaxially oriented polypropylene (BOPP) films, biaxially oriented polyamide (nylon) films, foil, paper, board, or fabric substrates, or may further include another of the above multilayer films to form a laminate.

[0098] It has been discovered that the use of propylene-based elastomers in a layer of a polyethylene multilayer film, and stretching or directional orientation of the unstretched multilayer film had little or no negative effect on optical and mechanical properties of the multilayer film. Also, addition of propylene -based elastomers may not cause cavitation and the resultant loss of desired optical properties and may also reduce or eliminate issues with blocking by allowing a complete seal to be formed in either a collapsed bubble or a laminate. As a result, the multilayer film can provide a convenient and cost-effective alternative to current options for film packaging where a balance of optical properties and overall film performance is expected.

Multilayer Film Properties

[0099] For uniaxially oriented multilayer films, the properties and descriptions below are intended to encompass measurements in both the direction of stretching (DS) and the direction perpendicular to the DS. Such measurements are reported separately, with the designation“DS” indicating a measurement in the direction of stretching, and“PS” indicating a measurement in the direction perpendicular to stretching.

[00100] Tensile properties of the films can be measured as specified by ASTM D882 with static weighing and a constant rate of grip separation. Since rectangular shaped test samples can be used, no additional extensometer is used to measure extension. The nominal width of the tested film sample is 15 mm and the initial distance between the grips is 50 mm. A pre load of 0.1N was used to compensate for the so called TOE region at the origin of the stress- strain curve. The constant rate of separation of the grips is 5 mm/min upon reaching the pre- load, and 5 mm/min to measure 1% Secant modulus (up to 1% strain). The film samples may be tested in direction of stretching or in a direction perpendicular to stretching.

[0100] Stretched Multilayer films of the present disclosure may have one or more of the following properties:

(a) A total thickness of from about 5 pm to about 200 pm, from about 10 pm to about 150 pm, or from about 20 pm to about 120 pm. The thickness of each of the first layer and the third layer may be at least 5% of the total thickness, or from about 10% to about 40%. The thickness ratio between one of the first layer or the third layer and the second layer may be about 1: 1 to about 1:6, for example, about 1:1, about 1:2, about 1:3, or about 1:4;

(b) A dart drop impact strength of about 0.5 g/pm or greater, about 1 g/pm or greater, about 2 g/pm or greater, about 3 g/pm or greater, about 5 g/pm or greater, or about 8 g/pm or greater. For example, the dart drop can be from about 0.5 g/pm to about 10 g/pm, from about 1 g/pm to about 8 g/pm, from about 1 g/pm to about 6 g/pm, from about 2 g/pm to about 6 g/pm, or from about 2 g/pm to about 4 g/pm, as determined by ASTM D1709;

(c) A Puncture Resistance break energy of about 120 mJ/pm or greater, about 130 mJ/pm or greater, about 150 mJ/pm or greater, or about 170 mJ/pm or greater. For example, the film may have a puncture resistance break energy of about 30 in-lb/mil or greater (or about 133 mJ/pm or greater), about 35 in-lb/mil or greater (or about 155 mJ/mhi or greater), and about 40 in-lb/mi or greater (or about 177 mJ/mhi or greater), Puncture resistance was measured based on ASTM D5748, which is designed to provide load versus deformation response under biaxial deformation conditions at a constant relatively low test speed (change from 250 mm/min to 5 mm/min after reach pre-load (0. IN)). Film samples were tested below the cross-head area with the 2.5 kN load cell. The sample was about 550 mm*900 mm in size. Maximum Puncture force is the maximum load achieved by the film sample before the break point;

(d) A Haze value of about 45% or less, about 40% or less, about 35% or less, about 30% or less, about 25% or less, about 20% or less, about 15% or less, or about

10% or less, as determined by ASTM D-1003;

(e) A Clarity (defined as regular transmitted light that is deflected less than 0.1 from the axis of incident light through the bulk of the film sample) of about 80% or greater, about 85% or greater, about 90% or greater, about 95% or greater, as determined by ASTM D1746; and/or

(f) A Gloss of about 30% or greater, about 35% or greater, about 40% or greater, about 45% or greater, about 50% or greater, about 55% or greater, about 60% or greater, as determined by ASTM D-2457, where a light source is beamed onto the plastic surface at an angle of 45° and the amount of light reflected is measured.

[0101] Uniaxially oriented multilayer films of the present disclosure may also have one or more of the following properties:

(g) A 1% secant modulus in the direction of stretching of about 500 MPa or greater, from about 500 MPa to about 1500 MPa, from about 600 MPa to about 1200 MPa, from about 600 MPa to about 1000 MPa, from about 600 MPa to about

900 MPa, or from about 600 MPa to about 800 MPa, as determined by ASTM D882. 1% Secant modulus is calculated by drawing a tangent through two well defined points on the stress-strain curve. The reported value corresponds to the stress at 1% strain (with x correction) and generally the 1% secant modulus is used for thin film and sheets as no clear proportionality of stress to strain exists in the initial part of the curve.;

(h) An absolute modulus of about 10 N/mm or greater, about 15 N/mm o greater, about 20 N/mm or greater, about 25 N/mm or greater, or about 30 N/mm or greater, where the absolute modulus is calculated by multiplying (i) the 1% secant modulus in the direction of stretching, as determined by ASTM D882 by (ii) the thickness of the multilayer film in millimeters.

(i) A 1% secant modulus in the PS of about 400 MPa or less, about 300 MPa or less, or about 250 MPa or less. For example, the 1% Secant Modulus perpendicular to the direction of stretching can be from about 70 MPa to about

400 MPa, from about 100 MPa to about 300 MPa, from about 100 MPa to about

275 MPa, from about 100 MPa to about 250 MPa, from about 150 MPa to about

250 MPa, from about 175 MPa to about 250 MPa, from about 150 MPa to about

200 MPa, or from about 200 MPa to about 250 MPa, as determined by ASTM D882;

(j) A Tensile Strength at break in the direction of stretching of about 80 MPa or greater, about 100 MPa or greater, about 120 MPa or greater, about 140 MPa or greater, or about 160 MPa or greater, as determined by ASTM D638;

(k) An Elmendorf Tear Strength in the direction of stretching of at about 0.3 g/pm or greater, about 0.5 g/pm or greater, about 0.6 g/pm or greater, or about 0.8 g/pm or greater. For example, the Elmendorf Tear strength in the direction of stretching can be from about 0.3 g/pm to about 2.5 g/pm, from about 0.5 g/pm to about 2 g/pm, from about 0.5 g/pm to about 1.5 g/pm, from about 0.6 g/pm to about 1 g/pm, or from about 0.7 g/pm to about 0.9 g/pm, as determined by ASTM D1922-06a, which measures the energy required to continue a pre-cut tear in the test sample, expressed in (g/pm). Samples are cut across the web using the constant radius tear die and were free of any visible defects (e.g., die lines, gels, etc.);

Multilayer Film Production

[0102] Also provided are methods for making stretched multilayer films. A method for making a multilayer film may include: extruding a first layer, a second layer disposed on the First layer, and a third layer disposed on the second layer, where the first layer includes a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, where the first layer is free of polymers with a density of about 0.908 or less; the second layer includes a polyolefin; the third layer includes a polyethylene composition including a propylene -based elastomer; and stretching the multilayer film in a uniaxial direction. In at least one embodiment the propylene-based elastomer has a density of about 0.9 or less, about 0.88 or less, about 0.87 or less, about 0.865 or less, about 0.864 or less, about 0.863 or less, or about 0.862 or less.

[0103] In another embodiment, a method of making a multilayer film further includes: extruding a fourth layer disposed between the first layer and the second layer.

[0104] In another embodiment, a method of making a multilayer film further includes: extruding a fifth layer disposed between the second layer and the third layer.

[0105] Multilayer films of the present disclosure may be formed by any suitable techniques including blown extrusion, cast extrusion, coextrusion, blow molding, casting, and extrusion blow molding. The materials forming each layer may be coextruded through a coextrusion feedblock and die assembly to yield a film with two or more layers adhered together but differing in composition. Coextrusion may be adapted to cast film or blown film processes. Certain combinations of resins can provide films having desired physical and optical properties. Multilayer films may also be formed by combining two or more single layer films prepared as described above. Unstretched multilayer films of the present disclosure may be uniaxially oriented by stretching in a single direction (machine or transverse) or may be biaxially oriented by stretching in more than one direction.

[0106] For example, the composition may be extruded in a molten state through an annular die and then blown and cooled to form a tubular, blown film. An example of a blown film process and apparatus suitable for forming films is described in U.S. Pat. No. 5,569,693. Other blown film forming methods can also be used. When a blown film process is used, the blown film can be formed, axially slit and opened prior to winding, or the blown film can be allowed to collapse so that the interior layer (the third layer as described herein) can adhere to itself forming an unstretched multilayer film that is twice as thick. In other words, a blown film process can be configured to form a 1/2/3 multilayer film, with 1 corresponding to the first layer, 2 corresponding to the second layer, and 3 corresponding to the third layer. In a typical process, the multilayer film would have a 1/2/3 structure. However, if the film were allowed to collapse and block to itself, the multilayer film would have a symmetrical 1/2/3/3/2/1 structure. Whether axially slit or collapsed and blocked, the unstretched multilayer film may be heated to a temperature under its melting point and stretched in the machine or the transverse direction.

[0107] As a specific example, blown films can be prepared as follows: The polymer composition is introduced into the feed hopper of an extruder, such as a 50 mm extruder that is water-cooled, resistance heated, and has an L/D ratio of 30:1. The film can be produced using a 28 cm W&H die with a 1.4 mm die gap, along with a W&H dual air ring and internal bubble cooling. The film is extruded through the die into a film cooled by blowing air onto the surface of the film. The film is drawn from the die typically forming a cylindrical film that is cooled, collapsed and, optionally, subjected to a desired auxiliary process, such as slitting, treating, sealing, or printing. Typical melt temperatures are from about 180° C. to about 230° C. The rate of extrusion for a blown film is generally from about 0.5 to about 2 kilograms per hour per millimeter of die diameter. The finished multilayer film can be wound into rolls for later processing.

[0108] The collapsing and blocking method for blown films may be desirable in certain situations such as when thicker films are desired. Collapsing and blocking films can be advantageous as it facilitates the manufacture of symmetric films which can be directionally oriented without curling and may also allow for faster cooling as some cooling of the thinner film occurs prior to collapsing into the thicker film. Another advantage may be enhanced barrier properties, because a barrier layer (e.g., an oxygen barrier layer or water vapor barrier layer) can be included in a blown film, and then duplicated when the blown film collapses and is blocked because a single barrier layer in the blown film becomes two barrier layers upon collapse.

[0109] By collapsing the film and allowing an interior layer to couple to itself (blocking), thick films can be made (e.g., a 250 micron film becomes 500 microns). Thus, some embodiments relate to blown films that are collapsed and blocked to form a thick film. In embodiments where collapsing and blocking is desired, the composition of the third layer, can be selected so as to facilitate its coupling (or adherence) to itself during the blown film process. In at least one embodiment, increased addition of a propylene-based elastomer is used to aid in the blocking process. In at least one embodiment, the propylene-based elastomer is included in the third layer to aid in sealing or blocking a collapsed film.

[0110] Thus, the collapsing and blocking method allows one to make relatively thinner and symmetrically blown films, which may have better cooling efficiency, better optics, and lower film crystallinity compared to a non-blocked film having a thickness comparable to the film after collapsing and blocking. The collapsing and blocking method also advantageously provides, in some embodiments, substantially flat films after collapsing and blocking. The ability to make thick films of 250 or 300 microns or greater can provide an advantage when the film is then directionally oriented. For example, a thick film of 500 microns can be directionally oriented at a stretch ratio of 5:1 to provide a 100 micron film that may be useful in heavy duty bag applications. [0111] In at least on embodiment, multilayer films are formed by later laminating two or more existing films to one another. For example, two or more films having the same structure can be prepared using a cast film process and then laminated to simulate the symmetric collapsed and blocked structures described above. The two films can each have a contact layer with a relatively low melting point such that the multilayer films can pass over a hot roll that heats the films and thermally laminates them together. The two multilayer films also could be laminated together with an adhesive. When the two multilayer films having the same structure are laminated together, the laminated film can simulate what occurs when a blown film is collapsed and blocked.

[0112] The number of layers in stretched multilayer films can depend on a number of factors including, for example, the desired properties of the film, the end use application for the film, the desired polymers to be used in each layer, the desired thickness of the film, whether the film is formed by collapsing and blocking a blown film, and others.

[0113] Unstretched multilayer films, whether collapsed and blocked or not, may then be oriented in a direction of stretching (DS) to provide uniaxially oriented stretched multilayer films. The uniaxially oriented film can be oriented in the machine (or processing) direction (MD) or transverse direction (TD) using any suitable techniques. Unstretched multilayer films, may also be oriented in both the MD and TD forming a biaxially oriented stretched multilayer film. During the orientation, the unstretched multilayer film from the blown-film line or other film process is heated to an orientation temperature. Generally, the temperature range for orientation can be 25 °C below the Vicat softening temperature (as measured by ASTM D1525) up to the melting point (as measured ASTM D3418-03) of the polyethylene from which the outermost layers are comprised. The heating may be performed utilizing single or multiple heating rollers, or a heated space surrounding the material.

[0114] In one embodiment, the unstretched multilayer film may be stretched in the MD by feeding the heated film into a slow drawing roll with a nip roller, which has the same rolling speed as the heating rollers. The film then enters a fast drawing roll with a nip roller. The fast drawing roll has a speed that is 1.5 to 10 times faster than the slow drawing roll, which effectively orients the multilayer film on a continuous basis. The stretched multilayer film enters annealing thermal rollers, which allow stress relaxation by holding the film at an elevated temperature for a period of time. In another embodiment, the unstretched multilayer film is biaxially oriented using a suitable MD/TD stretching process, such as tenter frame, double-bubble, or LISIM®. Alternative stretching methods are possible, including employing apparatus capable of simultaneous stretching, or stretching in the MD and then in the TD, or the inverse.

[0115] The annealing temperature may be within the same temperature range as used for stretching or slightly below (e.g. 10°C to 20°C below), with room temperature (about 23°C) being the lower limit. Annealing may take place at a temperature of about 23 °C or greater, about 25°C or greater, about 30°C or greater, about 40°C or greater, about 50°C or greater, about 60°C or greater, about 70°C or greater, about 80°C or greater, about 90°C or greater, about 100°C or greater, about 110°C or greater, or about 120°C or greater. The film may be cooled through cooling rollers to an ambient temperature

[0116] The film is said to be at maximum extension when DS tensile strength has a less than 100% elongation at break under ASTM D-882. The preparation process of a stretched multilayer film includes at least the steps of forming a layered film structure and stretching the obtained multilayer film in a draw ratio of 1:3 up to 1:12, 1:4 to 1:10, or 1:5 to 1:8. The film is stretched at least 3 times its original length in a specific direction; this is stated herein as a draw ratio of at least 1:3, where "1" represents the original length of the film and "3" denotes that it has been stretched to 3 times that original length.

[0117] An effect of stretching is that the thickness of the film is similarly reduced. Thus a draw ratio of at least 1:3 also means that the thickness of the film is one-third of the original thickness or less.

[0118] Addition of polypropylene to polyethylene films can cause cavitation when the multilayer films are stretched because the polypropylene may form an immiscible region or act as a filler particle. Cavitation occurs when the polyethylene is stretched and regions or particles within the film create a discontinuity in the film that increases in size during stretching. In essence, a portion of the stretched film pulls away from film regions or filler particles, resulting in tiny cavities. Cavitation, in turn, can result in decreased gloss, clarity, tear strength, and modulus. However, it has been discovered that the addition of certain propylene -based elastomers to a polyethylene does not demonstrate cavitation and does not cause cavitation when the polyethylene/propylene-based elastomer is part of a multilayer film that undergoes stretching. The same propylene-based elastomers may also reduce or eliminate issues with blocking by allowing coupling (or blocking) of two sides of a collapsed bubble, which delivers a stretched multilayer film with excellent overall performance. As a result, the addition of propylene-based elastomers to a multilayer film can provide a convenient and cost-effective alternative to current options for improving multilayer films for packaging including a balance of optical properties and overall film performance. [0119] The stretched multilayer film, may be further downgauged in comparison to known blown films of similar materials (oriented or non-oriented) while simultaneously improving or at least maintaining tensile modulus and furthermore maintaining the balance between optical properties and mechanical properties.

Other embodiments of the present disclosure can include:

[0120] Paragraph 1. A stretched multilayer film including: a first layer including a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, where the first layer is substantially free of polymers having a density of 0.908 or less; a second layer including a polyolefin, the second layer disposed on the first layer; and a third layer including a polyethylene composition including a propylene- based elastomer, the third layer disposed on the second layer, and where the stretched multilayer film has a haze of about 10% or less.

[0121] Paragraph 2. The stretched multilayer film of paragraph 1, further including a fourth layer including a polyethylene, the fourth layer disposed between the first layer and the second layer.

[0122] Paragraph 3. The stretched multilayer film of any of paragraphs 1 or 2, further including a fifth layer including a polyethylene, the fifth layer disposed between the second layer and the third layer.

[0123] Paragraph 4. The stretched multilayer film of paragraph 3, where the polyethylene of the fourth layer and polyethylene of the fifth layer have substantially the same chemical composition.

[0124] Paragraph 5. A stretched multilayer film including: a first layer including a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, where the first layer is free of polymers having a density of about 0.908 g/cc or less; a second layer including a polyolefin, the second layer disposed on the first layer; a third layer including a polyethylene composition including a propylene -based elastomer, the third layer disposed on the second layer; a fourth layer including a polyethylene composition of substantially the same chemical composition as the polyethylene composition of the third layer, the fourth layer disposed on the third layer; a fifth layer including a polyolefin of substantially the same chemical composition as the polyolefin of the second layer, the fifth layer disposed on the fourth layer; and a sixth layer including a polyethylene of substantially the same chemical composition as the polyethylene of the first layer, the sixth layer disposed on the fifth layer; and where the stretched multilayer film has a haze of about 10% or less.

[0125] Paragraph 6. The stretched multilayer film of paragraph 5, further including a seventh layer including a polyethylene and an eighth layer including a polyethylene, where the polyethylene of the seventh layer and the polyethylene of the eighth layer have substantially the same chemical composition, the seventh layer is disposed between the first layer and the second layer, and the eighth layer is disposed between the fifth layer and the sixth layer.

[0126] Paragraph 7. The stretched multilayer film of paragraphs 5 or 6, further including a ninth layer comprised of a polyethylene and a tenth layer comprised of a polyethylene, where the polyethylene of the ninth layer and the polyethylene of the tenth layer have substantially the same chemical composition, the ninth layer is disposed between the second layer and the third layer, and the tenth layer is disposed between the fourth layer and the fifth layer.

[0127] Paragraph 8. The stretched multilayer film of paragraph 7, where the polyethylene of the seventh layer, the polyethylene of the eighth layer, the polyethylene of the ninth layer, and the polyethylene of the tenth layer have substantially the same chemical composition.

[0128] Paragraph 9. The stretched multilayer film of any of paragraphs 5 to 8, where the stretched multilayer film has a clarity of about 60% or greater.

[0129] Paragraph 10. The stretched multilayer film of any of paragraphs 5 to 9, where the stretched multilayer film has a gloss of about 70% or greater.

[0130] Paragraph 11. The stretched multilayer film of any of paragraphs 5 to 10, where the stretched multilayer film has an average tensile strength at break in the direction of stretching of about 100 MPa or greater.

[0131] Paragraph 12. The stretched multilayer film of any of paragraphs 5 to 11, where the stretched multilayer film has an Elmendorf tear strength in the direction of stretching of about 2 g/pm or greater.

[0132] Paragraph 13. The stretched multilayer film of any of paragraphs 5 to 12, where the stretched multilayer film has a thickness of about 5 pm to about 200 pm.

[0133] Paragraph 14. The stretched multilayer film of any of paragraphs 5 to 13, where the stretched multilayer film has a dart impact strength of about 2 g/pm or greater. [0134] Paragraph 15. The stretched multilayer film of any of paragraphs 5 to 14, where the stretched multilayer film has a 1 % secant modulus in the direction of stretching of about 500 MPa or greater.

[0135] Paragraph 16. A method for preparing a stretched multilayer film including: extruding a first layer, a second layer disposed on the first layer, and a third layer disposed on the second layer to form a multilayer film, where the first layer includes a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, where the first layer is free of polymers having a density of about 0.908 g/cc or less, the second layer includes a polyolefin, and the third layer includes a polyethylene composition including a propylene-based elastomer; and stretching the multilayer film in a uniaxial direction to form a stretched multilayer film, where the stretched multilayer film has a haze of about 10% or less.

[0136] Paragraph 17. The method of paragraph 16, further including blowing the multilayer film into a bubble and pressing the bubble into a collapsed and blocked form before stretching.

[0137] Paragraph 18. The method of paragraphs 16 or 17, further including extruding a fourth layer disposed between the first layer and the second layer to form a multilayer film having the fourth layer disposed between the first layer and the second layer.

[0138] Paragraph 19. The method of paragraph 18, further including extruding a fifth layer disposed between the second layer and the third layer to form a multilayer film having the fifth layer disposed between the second layer and the third layer.

[0139] Paragraph 20. The method of paragraph 19, where the polyethylene of the fourth layer and the polyethylene of the fifth layer have substantially the same chemical composition.

[0140] Paragraph 21. The method of any of paragraphs 16 to 20, further including heating the multilayer film before stretching to an orientation temperature below the melting point of the polyethylene of the first layer.

[0141] Paragraph 22. The method of any of paragraphs 16 to 21, further including annealing the stretched multilayer film at a temperature above 25°C.

[0142] Paragraph 24. The method of any of paragraphs 16 to 23, where stretching includes stretching the multilayer film to form a stretched multilayer film with a final thickness of about 5 pm to about 200 pm. [0143] Paragraph 25. The method of any of paragraphs 16 to 24, where stretching includes stretching the multilayer film in the machine direction with a draw ratio of about 1:3 to about 1:12.

[0144] Paragraph 26. The method of any of paragraphs 16 to 25, where the stretched multilayer film has an Elmendorf tear strength in the stretching direction of about 2 g/pm or higher.

[0145] Paragraph 27. A multilayer film including: a first layer including a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, where the first layer is substantially free of polymers having a density of 0.908 or less; a second layer including a polyolefin, the second layer disposed on the first layer; a third layer including a polyethylene composition including a propylene-based elastomer, the third layer disposed on the second layer; a fourth layer including a polyethylene composition of the same chemical composition as the polyethylene composition of the third layer, the fourth layer disposed on the third layer; a fifth layer including a polyolefin of the same chemical composition as the polyolefin of the second layer, the fifth layer disposed on the fourth layer; and a sixth layer including a polyethylene of the same chemical composition as the polyethylene of the first layer, the sixth layer disposed on the fifth layer; and the multilayer film has a haze of about 10% or less.

[0146] Paragraph 28. A multilayer film including: a first layer including a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, where the first layer is substantially free of polymers having a density of 0.908 or less; a second layer, the second layer disposed on the first layer; a third layer including a polyolefin, the third layer disposed on the second layer; a fourth layer, the fourth layer disposed on the third layer; a fifth layer including a polyethylene composition including a propylene-based elastomer, the fifth layer disposed on the fourth layer; a sixth layer including a polyethylene composition of the same chemical composition as the polyethylene composition of the fifth layer, the sixth layer disposed on the fifth layer; a seventh layer of the same chemical composition as the fourth layer, the seventh layer disposed on the sixth layer; a eighth layer including a polyolefin of the same chemical composition as the polyolefin of the third layer, the eighth layer disposed on the seventh layer; a ninth layer of the same chemical composition as the second layer, the ninth layer disposed on the eighth layer; a tenth layer including a polyethylene of the same chemical composition as the polyethylene of the first layer, the tenth layer disposed on the ninth layer; and the multilayer film has a haze of about 10% or less.

EXAMPLES

[0147] The properties cited below were determined in accordance with the following test procedures. Where any of these properties is referenced in the appended claims, it is to be measured in accordance with the specified test procedure.

[0148] The density was measured according to ISO 1183 and ISO 1872-2 for sample preparation.

[0149] Haze, reported as a percentage (%), was measured as specified by ASTM D-1003 and is defined as the percentage of transmitted light passing through the bulk of the film sample that is deflected by more than 2.5°. Total transmittance is a measurement of how much light passes through a film (ratio of total transmitted light to incident light). The haze is the ratio in % of the diffused light relative to the total light transmitted by the sample film.

[0150] Gloss was measured as specified by ASTM D-2457, where a light source is beamed onto the plastic surface at an angle of 45° and the amount of light reflected is measured.

[0151] Clarity, reported as a percentage (%) was measured as specified by ASTM D1746 and is defined as the percentage of the incident light that is transmitted though the bulk of the film sample and is deflected less than 0.1 from the axis of incident light.

[0152] Example 1. A six layer film was produced on an Alpine blown line equipped with a 400 mm die diameter, a 2 mm die gap, and IBC. The production was made at an output of 280 kg/h, with cooling air at 15°C and a blow-up ratio (BUR) of 1:2.42. The first layer and the sixth layer were formed from a 89.5:10:0.5 blend of Exceed™ 1018HA (which is an EH copolymer with a density of 0.918 g/cm³, and a MI (190°C/2.16 kg) of 1 g/10 min), LD150BW (which is an LDPE with a density of 0.923 g/cm³, and a MI (190°C/2.16 kg) of 0.75 g/10 min), and Polybatch CE-505-E (slip masterbatch); and where the second layer and the fifth layer were formed from a 60:40 blend of Exceed™ XP 8656ML (which is an EH copolymer with a density of 0.916 g/cm³, and a MI (190°C/2.16 kg) of 0.50 g/10 min) and HTA 108 (which is an HDPE with a density of 0.961 g/cm³, and a MI (190°C/2.16 kg) of 0.70 g/10 min); and where the third layer and the fourth layer were formed from a 70:30 blend of Exceed” 1018HA (which is an EH copolymer with a density of 0.918 g/cm³, and a MI (190°C/2.16 kg) of 1 g/10 min) and Vistamaxx” 6102FL (which is a propylene-based elastomer with a density of 0.862 g/cm³, and a MI (190°C/2.16 kg) of 1.4 g/10 min). The multilayer film had a layer distribution of 1/5/0.5/0.5/5/1, the first layer and the sixth layer being twice as thick as the third layer and the fourth layer, and the second layer and the fifth layer being five times as thick as the first layer and the sixth layer. The multilayer film underwent machine direction stretching on an Alpine MDO unit as follows: The blown bubble was collapsed and blocked and the multilayer film was rolled across four pre -heating rollers at temperatures of 85°C, 95°C, 100°C, and 100°C, in that order, then across two stretching rollers both at 100°C, but turning at different rates so that the film was stretched in a 1:4.6 ratio to a final film thickness of 25pm. The oriented multilayer film was annealed and cooled by passing over two annealing rollers at temperatures of 100°C and 95 °C, and then across two cooling rollers at temperatures of 70°C and 40°C. The stretched multilayer film had a haze of 2.8%, a gloss of 87%, and a clarity of 78%.

[0153] Example 2. A five layer film was produced on an Alpine blown line equipped with a 400 mm die diameter, a 2 mm die gap, and IBC. The production was made at an output of 340 kg/h, with cooling air at 15°C and a blow-up ratio (BUR) of 1:2.42. The first layer was formed from Enable” 4002HH, and EH copolymer with a density of 0.940 g/cm³, and a MI (190°C/2.16 kg) of 0.25 g/10 min. The second layer was formed from Exceed” XP 8656ML, an EH copolymer with a density of 0.916 g/cm³, and a MI (190°C/2.16 kg) of 0.50 g/10 min. The third layer was formed from a 97: 1:2 blend of Enable” 4002HH, and EH copolymer with a density of 0.940 g/cm³, and a MI (190°C/2.16 kg) of 0.25 g/10 min, Polybatch CE-505-E, and Polybatch F15 (anti-block masterbatch). The fourth layer was formed from an HTA 108, a HDPE with a density of 0.961 g/cm³, and a MI (190°C/2.16 kg) of 0.70 g/10 min. The fifth layer was formed from a 99.5:0.5 blend of HTA 108, a HDPE with a density of 0.961 g/cm³, and a MI (190°C/2.16 kg) of 0.70 g/10 min and Polybatch CE- 505 -E. The multilayer film underwent machine direction stretching on an Alpine MDO unit as follows: The blown bubble was collapsed without blocking. The edges were trimmed from the collapsed bubble forming two separated multilayer film which were stretched together. The two multilayer films were rolled across four pre -heating rollers at temperatures of 105°C, 110°C, 112°C, and 112°C, in that order, then across two stretching rollers both at 112°C, but turning at different rates so that the films were stretched in a 1:4.6 ratio to a final film thickness of 25 pm. The stretched multilayer films were annealed and cooled by passing over two annealing rollers at temperatures of 110°C and 105°C, and then across two cooling rollers at temperatures of 70°C and 40°C. The two stretched multilayer films were separated and an individual stretched multilayer film had a haze of 6.2%, a gloss of 78%, and a clarity of 61%. [0154] Example 3. A five layer film was produced on an Alpine blown line equipped with a 400 mm die diameter, a 2 mm die gap, and IBC. The production was made at an output of 280 kg/h, with cooling air at 15°C and a blow-up ratio (BUR) of 1:2.42. The first layer was formed from a 85:15 blend of HTA 108, a HDPE with a density of 0.961 g/cm³, and a MI (190°C/2.16 kg) of 0.70 g/10 min, and LD150BW, an LDPE with a density of 0.923 g/cm³, and a MI (190°C/2.16 kg) of 0.75 g/10 min. The second layer was formed from Exceed” XP 8656ML, an EH copolymer with a density of 0.916 g/cm³, and a MI (190°C/2.16 kg) of 0.50 g/10 min. The third layer was formed from a 82: 15:1:2 blend of HTA 108, a HDPE with a density of 0.961 g/cm³, and a MI (190°C/2.16 kg) of 0.70 g/10 min, LD150BW, an LDPE with a density of 0.923 g/cm³, and a MI (190°C/2.16 kg) of 0.75 g/10 min, Polybatch CE-505-E, and Polybatch F15. The fourth layer was formed from Enable” 4002HH. The fifth layer was formed from a 99.5:0.5 blend of Enable” 4002HH and Polybatch CE-505-E. The multilayer film underwent machine direction stretching on an Alpine MDO unit as follows: The blown bubble was collapsed without blocking. The edges were trimmed from the collapsed bubble forming two separated multilayer film which were stretched together. The two multilayer films were rolled across four pre-heating rollers at temperatures of 100°C, 110°C, 114°C, and 114°C, in that order, then across two stretching rollers both at 114°C, but turning at different rates so that the films were stretched in a 1:4.6 ratio to a final film thickness of 25pm. The oriented multilayer films were annealed and cooled by passing over two annealing rollers at temperatures of 110°C and 105°C, and then across two cooling rollers at temperatures of 70°C and 40°C. The two stretched multilayer films were separated and an individual stretched multilayer film had a haze of 11.2%, a gloss of 58%, and a clarity of 40%.

[0155] The figure is a graph comparing the percent haze, gloss and clarity various stretched multilayer films including: (i) a three-layer collapsed and blocked bubble machine direction oriented polyethylene multilayer film according to example 1 having a haze of 2.8%, a gloss of 87%, and a clarity of 78%; (ii) a five-layer machine direction oriented polyethylene multilayer film with Enable” 4002HH in the outer layers according to example 2 having a haze of 6.2%, a gloss of 78%, and a clarity of 61%; (iii) a five-layer machine direction oriented polyethylene multilayer film with a blend of HDPE and LDPE in the outer layers according to example 3 having a haze of 11.2%, a gloss of 58%, and a clarity of 40%; (iv) an oriented polyethylene terephthalate film having a haze of 3.0%, a gloss of 124%, and a clarity of 70%; (v) a biaxially oriented polypropylene film having a haze of 5.0%, a gloss of 79%, and a clarity of 66%; and (vi) a biaxially oriented polyamide film having a haze of 3.6%, a gloss of 100%, and a clarity of 80%.

[0156] Overall, stretched multilayer films of the present disclosure can provide desired physical and optical properties with complete blocking and without cavitation. For example, the example three-layer multilayer film containing a propylene-based elastomer in the third layer had a haze value lower than that of oriented PET, PP, or Nylons. The addition of a propylene -based elastomer in a single layer in conjunction with the addition EH copolymers and directional orientation of the multilayer film can provide films with low haze, high gloss and clarity, without sacrificing tensile strength, puncture resistance, and toughness

[0157] For the sake of brevity, only certain ranges are explicitly disclosed. However, ranges from any lower value may be combined with any upper value to recite a range not explicitly recited, as well as, ranges from any lower value may be combined with any other lower value to recite a range not explicitly recited, in the same way, ranges from any upper value may be combined with any other upper value to recite a range not explicitly recited Additionally, within a range includes every point or individual value from its end point to end point even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0158] It is to be understood that while aspects of the present disclosure have been described in conjunction with specific embodiments thereof, the foregoing description is intended to illustrate and not limit the scope of the claims. Other aspects, advantages and modifications will be apparent to those skilled in the art to which the present disclosure pertains.

Claims

CLAIMS What is claimed is:

1. A stretched multilayer film comprising:

a first layer comprising a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, wherein the first layer is free of polymers having a density of about 0.908 g/cc or less;

a second layer comprising a polyolefin, the second layer disposed on the first layer; a third layer comprising a polyethylene composition comprising a propylene -based elastomer, the third layer disposed on the second layer;

wherein the multilayer film has a haze of about 10% or less.

2. The stretched multilayer film of claim 1, further comprising a fourth layer comprising a polyethylene, the fourth layer disposed between the first layer and the second layer.

3. The stretched multilayer film of claim 2, further comprising a fifth layer comprising a polyethylene, the fifth layer disposed between the second layer and the third layer.

4. The stretched multilayer film of claim 3, wherein the polyethylene of the fourth layer and the polyethylene of the fifth layer have substantially the same chemical composition.

5. A stretched multilayer film comprising:

a fourth layer comprising a polyethylene composition of substantially the same chemical composition as the polyethylene composition of the third layer, the fourth layer disposed on the third layer; a fifth layer comprising a polyolefin of substantially the same chemical composition as the polyolefin of the second layer, the fifth layer disposed on the fourth layer; and

a sixth layer comprising a polyethylene of substantially the same chemical composition as the polyethylene of the first layer, the sixth layer disposed on the fifth layer; wherein the stretched multilayer film has a haze of about 10% or less.

6. The stretched multilayer film of claim 5, further comprising a seventh layer comprising a polyethylene and an eighth layer comprising a polyethylene, wherein:

the polyethylene of the seventh layer and the polyethylene of the eighth layer have substantially the same chemical composition,

the seventh layer is disposed between the first layer and the second layer, and the eighth layer is disposed between the fifth layer and the sixth layer.

7. The stretched multilayer film of claim 6, further comprising a ninth layer comprised of a polyethylene and a tenth layer comprised of a polyethylene, wherein:

the polyethylene of the ninth layer and the polyethylene of the tenth layer have substantially the same chemical composition,

the ninth layer is disposed between the second layer and the third layer, and the tenth layer is disposed between the fourth layer and the fifth layer.

8. The stretched multilayer film of claim 7, wherein the polyethylene of the seventh layer, the polyethylene of the eighth layer, the polyethylene of the ninth layer, and the polyethylene of the tenth layer have substantially the same chemical composition.

9. The stretched multilayer film of claim 5 or any one of claims 6-8, wherein the stretched multilayer film has one or more of the following properties:

a clarity of about 60% or greater;

a gloss of about 70% or greater;

an average tensile strength at break in the direction of stretching of about 100 MPa or greater;

an Elmendorf tear strength in the direction of stretching of about 2 g/pm or greater; a thickness of about 5 pm to about 200 pm;

a dart impact strength of about 2 g/pm or greater; and

a 1% secant modulus in the direction of stretching of about 500 MPa or greater.

10. A method for preparing a stretched multilayer film comprising:

extruding a first layer, a second layer disposed on the first layer, and a third layer disposed on the second layer to form a multilayer film,

wherein:

the first layer comprises a polyethylene selected from (i) a polyethylene homopolymer having a density of about 0.913 g/cc or greater; (ii) a polyethylene copolymer having a density of about 0.913 g/cc or greater; or (iii) a mixture thereof, wherein the first layer is free of polymers having a density of about 0.908 g/cc or less,

the second layer comprises a polyolefin, and

the third layer comprises a polyethylene composition comprising a propylene- based elastomer; and

stretching the multilayer film in a uniaxial direction to form a stretched multilayer film,

wherein the stretched multilayer film has a haze of about 10% or less.

11. The method of claim 10, further comprising blowing the multilayer film into a bubble and pressing the bubble into a collapsed and blocked form before stretching.

12. The method of claim 10 or claim 11, further comprising extruding a fourth layer disposed between the first layer and the second layer to form a multilayer film having the fourth layer disposed between the first layer and the second layer.

13. The method of claim 12, further comprising extruding a fifth layer disposed between the second layer and the third layer to form a multilayer film having the fifth layer disposed between the second layer and the third layer.

14. The method of claim 13, wherein the polyethylene of the fourth layer and the polyethylene of the fifth layer have substantially the same chemical composition.

15. The method of claim 10, further comprising heating the multilayer film before stretching to an orientation temperature below the melting point of the polyethylene of the first layer.

16. The method of claim 10 or any one of claims 11-15, further comprising annealing the stretched multilayer film at a temperature above 25 °C.

17. The method of claim 10 or any one of claims 11-16, wherein stretching comprises stretching the multilayer film to form a stretched multilayer film with a final thickness of about 5 pm to about 200 pm.

18. The method of claim 10 or any one of claims 11-17, wherein stretching comprises stretching the multilayer film in the machine direction with a draw ratio of about 1:3 to about 1:12.

19. The method of claim 10 or any one of claims 11-18, wherein the stretched multilayer film has an Elmendorf tear strength in the stretching direction of about 2 g/pm or higher.