EP4106994A1

EP4106994A1 - High tenacity handwrap stretch film for improved pallet stability

Info

Publication number: EP4106994A1
Application number: EP21705775.1A
Authority: EP
Inventors: Bart Lauwers; Dirk VAN DER SANDEN
Original assignee: ExxonMobil Chemical Patents Inc
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 2020-02-18
Filing date: 2021-01-21
Publication date: 2022-12-28
Also published as: WO2021167739A1

Abstract

The present disclosure relates to multilayer films. The first layer may include a first polymer including polyethylene. The second layer, disposed on the first layer, may include a blend of a second polymer comprising a copolymer of ethylene and hexene and a third polymer comprising a copolymer of ethylene and hexene. The third layer, disposed on the second layer may include a fourth polymer including polyethylene. The present disclosure also relates to methods for preparing a multilayer films. The methods may include 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. Additionally, the present disclosure relates to pallets wrapped in a multilayer film, wherein the multilayer film is configured to provide a holding force of about 1.15 N per gram of the multilayer film per cubic meter of the pallet and goods.

Description

HIGH TENACITY HANDWRAP STRETCH FILM FOR IMPROVED PALLET

STABILITY CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application 62/977795, filed February 18, 2020, entitled “High Tenacity Handwrap Stretch Film for Improved Pallet Stability”, the entirety of which is incorporated by reference herein.

FIELD [0002] The present disclosure relates to polyolefin stretch films and pallet wrapping for improved product stability.

BACKGROUND

[0003] Polyolefin stretch film is one of the major technologies used to bundle and unitize loads onto a pallet. The use of polyolefin stretch films for palletization provides many advantages, including: low cost, consistency in strength and wrapping, and protection from dust, moisture, and damage during transportation. Puncture and tear resistance, good cling, load stability and stretchability are key requirements for stretch films. However, stretchability must be balanced with puncture and tear resistance because the stretched film must also be able to provide a resistance to puncture/tearing from load protrusions and sharp corners during transportation. The film may provide both a holding force to bundle the goods and a lock-in force maintaining the goods where they were placed on the pallet. Lock-in is important to the transportation of goods because even if the goods are held together if they shift during transportation there may be a loss in pallet stability or rejection of the delivery. Therefore, stretch wrap should provide both the holding force to keep goods together, and the lock-in force to keep the good in place. Indeed, contemplated legislation requires that pallet wrapping provide sufficient force to lock the goods in place on the pallet because shifting of goods in transit may cause highway safety issues.

[0004] Pallets may be wrapped manually (hand-wrap) by an operator walking and stretching the film around the pallet or by automated wrapping (machine- wrap). The choice is often dependent on the number of pallets to be wrapped and the cost of labor versus initial cost of a pallet wrapping devices. The choice of hand-wrap or machine-wrap may affect the choice of films used to wrap a pallet. For example, hand-wrap films may be limited to stretch ratios of 100% or below, whereas machine-wrap films may allow for stretch ratios of 400% stretch or higher. The stretch ratio may affect the desired thickness of the film because a thicker film may be stretched further while maintaining the same end thickness. Typically, stretch films can go from 4 to 50 mhi. Polyolefin stretch films may be composed of multiple layers providing different benefits, for example, the films may be composes of 3, 5, 7, or more layers. Additionally, the development of nanofeedblocks allows designing films with more than 55 layers.

[0005] One method commonly used to get to a desired performance is formation of pre stretched hand-wrap film through a two-step process. In a first step the film (based on more sophisticated materials and compositions) is extruded to a given thickness. In a second step those films are (either in- or off-line with the first step) stretched to the desired end-use thickness and performance. Pre-stretched handwrap film often provides sufficient force to hold goods together. However, pre-stretched handwrap formulations may not provide sufficient lock-in force to stabilize the goods in place on a pallet.

[0006] There is an increased recognition that delivering the (palletized) goods safely and in good quality from the supplier to the customer is critical from an economical, safety and sustainability perspective. Many current formulations cannot provide the desired balance of holding force and lock-in. There is a need for improved polyolefin stretch films with a balance of holding force and lock-in force to be used in palletization of consumer and industrial goods. [0007] Some references of potential interest in the area include: U.S. Patent Publication Nos. 2016/0221312; 2018/0257286; 2019/0001639; 2019/0118454; 2019/0118518;

2019/0177023; 2019/0202584.

SUMMARY

[0008] The present disclosure provides for multilayer films. The first layer may include a polyethylene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³. The second layer, disposed on the first layer, may include a blend of a second polymer including a copolymer of ethylene and hexene having a density of from about 0.92 g/cm³ to about 0.93 g/cm³ and a melt index of from about 0.3 g/lOmin to about 1 g/lOmin and a third polymer including a copolymer of ethylene and hexene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³ and a melt index of from about 2 g/lOmin to about 4 g/lOmin. The third layer, disposed on the second layer may include a fourth polymer including polyethylene having a density of about 0.91 g/cm³to about 0.92 g/cm³. The multilayer films of the present disclosure may include additional layers, such as a fourth layer disposed between the first layer and the second layer, the fourth layer including a fourth polymer including a copolymer of ethylene and hexene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³. Additionally, the multilayer films may include a fifth layer disposed between the second layer and the third layer, the fifth layer including a fifth polymer including a copolymer of ethylene and hexene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³.

[0009] The present disclosure also provides methods for preparing a multilayer films. The methods may include 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.

[0010] Additionally, the present disclosure provides for pallets wrapped in a multilayer film, wherein the multilayer film is configured to provide a holding force of about 1.15 N per gram of the multilayer film per cubic meter of the pallet and goods.

BRIEF DESCRIPTION OF THE DRAWING

[0011] FIG. 1A is a graph of tensile strength in the machine direction of polyolefin films both according to an embodiment and comparative examples.

[0012] FIG. IB is the same graph of tensile strength in the machine direction focused on a narrower percent elongation of polyolefin films both according to an embodiment and comparative examples.

[0013] FIG. 2A is a graph of tensile strength in the transverse direction of polyolefin films both according to an embodiment and comparative examples.

[0014] FIG. 2B is the same graph of tensile strength in the transverse direction focused on a narrower percent elongation of polyolefin films both according to an embodiment and comparative examples.

[0015] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the Drawings. It is contemplated that elements and features of one implementation may be beneficially incorporated in other implementations without further recitation.

DETAILED DESCRIPTION

[0016] It has been discovered that polyolefin film formulations including ethylene:higher alpha-olefin copolymers may provide added desired holding force and desired lock-in force. The film formulation does not involve pre- stretching because extrusion may be accomplished close to the end-use thickness. Additionally, the polyolefin film formulation may be more cost- efficient to other polyolefin films because less total polymer weight is needed to provide the film strength used to both hold the goods together and lock the goods in place. The cost- efficiency is further improved because the manufacture of the film may include: lower investment and operating costs, fewer production steps to reach desired performance, higher on-spec rates, and more consistent in-use performance. [0017] With many film formulations, including pre-stretched films, the film is stretched when wrapping a pallet. The amount of stretching may vary from operator to operator based on strength and energy, for example, films often are stretched further in the morning than in the afternoon, possibly corresponding to operator energy levels. Although the on-reel thickness of polyolefin stretch films of the present disclosure may be somewhat higher than that of the pre-stretched alternatives, the number of wraps to attain a desired pallet stability is lower. The fewer wraps may result in less grams of polymer per pallet, and the fewer wrapping cycles result in more efficient wrapping and less operator fatigue.

[0018] It has also been discovered that a polyolefin stretch film may be produced with a double-yield point allowing consistent and correct usage between operators. The double-yield point means that the films “tell” the operator to which level he should stretch the film, which results in more consistent wrapping and an overall more consistent holding force; a key contributing factor to the in- transport stability of the pallets. Additionally, the operators’ understanding of how much to stretch the film provides an easier, safer, and less tiring wrapping operation. The double-yield point provides a film where the level and slope of the natural draw ratio can be tailored to obtain the right balance between the desired holding force and lock-in level. Previously the industry attempted to produce films with a double-yield point by blending LDPE into more commonly used LLDPEs, but the films produced suffered from a loss of some key toughness attributes such as puncture and tear propagation resistance. The puncture and tear propagation resistance contribute to reduced failures of the wraps during application and in transport as they give higher resistance to sharp objects sticking out into the film.

Definitions

[0019] “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 includes terpolymers and the like. Likewise, the definition of polymer includes copolymers and the like.

[0020] Thus, 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 about 100 mol% (in the case of a homopolymer). Polyolefins include homopolymers or copolymers of C2 to C20 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.

[0021] Therefore, the terms “polyethylene,” “ethylene polymer,” “ethylene copolymer,” and “ethylene based polymer” mean a polymer or copolymer including about 50 mol% or more ethylene units (such as about 70 mol% or more ethylene units, about 80 mol% or more ethylene units, about 90 mol% or more ethylene units, about 95 mol% or more ethylene units or about 100 mol% ethylene units (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%. Polyethylene compositions may be physical blends or in situ blends of more than one type of polyethylene or compositions of polyethylenes with polymers other than polyethylenes.

[0022] 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. [0023] When a polymer is said to include a certain percentage, wt%, of a monomer, that percentage of monomer is based on the total amount of monomer units in the polymer.

[0024] An ethylene polymer having a density of 0.91 g/cm³ to 0.94 g/cm³ is referred to as a “low density polyethylene” (LDPE); an ethylene polymer having a density of 0.89 g/cm³ to 0.93 g/cm³, typically from 0.91 g/cm³ to 0.93 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 conventional 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 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 about 0.97 or above, or about 0.98 or above); and an ethylene polymer having a density of 0.94 g/cm³ or greater is referred to as a “high density polyethylene” (HDPE).

[0025] “Elastomer” or “elastomer composition” refers to a polymer or composition of polymers (such as blends of polymers) consistent with the ASTM D1566 definition. Elastomer includes mixed blends of polymers such as melt mixing and/or reactor blends of polymers. [0026] The terms “first” layer, “second” layer, “third” layer, “fourth” layer, and “fifth” layer 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.

[0027] The terms “first” polyethylene, “second” polyethylene, “third” polyethylene, “first” propylene -based elastomer, and “second” propylene-based elastomer are merely identifiers used for convenience, and shall not be construed as limitation on individual polyethylene or propylene-based elastomer, their relative order, or the number of polyethylenes or propylene-based elastomers used, unless otherwise specified.

[0028] “Disposed on” may mean disposed directly on or disposed indirectly on, unless otherwise specified.

[0029] Film layers that are the same in composition and in thickness are referred to as “identical” layers.

Polyethylenes

[0030] A polyethylene that can be used for the multilayer film may be selected from ethylene homopolymers, ethylene copolymers, and compositions 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. Polyethylenes may 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. In some embodiments, the polyethylenes are made by the catalysts, activators and processes described in U.S. Pat. Nos. 6,342,566; 6,384,142; and 5,741,563; and WO 03/040201 and WO 97/19991. Such catalysts are described in, for example, ZIEGLER CATALYSTS (Gerhard Fink, Rolf Miilhaupt and Hans H. Brintzinger, eds., Springer-Verlag 1995); Resconi et ah; and I, II METALLOCENE- BASED POLYOLEFINS (Wiley & Sons 2000). [0031] Useful polyethylenes include those sold by ExxonMobil Chemical Company in Houston Tex., including HDPE, LLDPE, and LDPE; and those sold under the ENABLE™, EXACT™, EXCEED™, ESCORENE™, EXXCO™, ESCOR™, PAXON™, and OPTEMA™ tradenames

[0032] Example LLDPEs include linear low density polyethylenes having a comonomer content from about 0.5 wt% to about 20 wt%, the comonomer derived from C3 to C20 a-olefins, e.g. 1-butene or 1-hexene. In various embodiments, the density of LLDPEs are from 0.89 g/cm³ to 0.94 g/cm³, such as from about 0.91 g/cm³ to about 0.93 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/10min, about 0.2 g/lOmin, or about 0.4 g/10min to about 4 g/lOmin, about 6 g/10min, or about 10 g/10min. 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 less than 50%. LLDPEs may have an MWD determined according to the procedure disclosed of about 5 or less. In another embodiment, a layer may contain more than one type of LLDPE. Suitable commercial polymers for an LLDPE may include those sold by ExxonMobil Chemical Company in Houston Tex., including LL1004YB.

[0033] 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 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 0.91 g/cm³ or greater, such as from about 0.92 g/cm³ to about 0.94 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.

[0034] Example HDPEs include high density polyethylenes having a comonomer content from about 0.01 wt% to about 5 wt%, the comonomer derived from C3 to C20 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 0.94 g/cm³ to 0.97 g/cm³, such as from about 0.945 g/cm³ to about 0.965 g/cm³, or from about 0.95 g/cm³ to about 0.965 g/cm³. The MI of such HDPEs is from about 0.1 g/lOmin, 0.2 g/lOmin, or 0.4 g/lOmin to about 4 g/lOmin, 6 g/lOmin, or 10 g/lOmin. 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.

[0035] 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 (MH_.ib) range such as 0.06 g/10 min. to 33 g/10 min. Other 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. [0036] In at least one embodiment, the polyethylene is an ethylene copolymer, either random or block, of ethylene and one or more comonomers selected from C3 to C20 linear, branched or cyclic monomers, often C4 to C12 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, such as 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%, or about 0.5 wt% to about 1 wt% of polymer units derived from one or more comonomers. In some embodiments, the ethylene copolymer has a weight average molecular weight of about 8,000 g/mol or greater, such as about 10,000 g/mol or greater, about 12,000 g/mol or greater, about 20,000 g/mol or greater, to about 1,000,000 g/mol or less, such as about 800,000 g/mol or less. [0037] In at least one embodiment, the polyethylene includes about 20 mol% or fewer propylene units, about 15 mol% or fewer, about 10 mol% or fewer, about 5 mol% or fewer, or about 0 mol% propylene units.

[0038] In some embodiments the comonomer is a C4 to C12 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.

[0039] 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 Ci to C10 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, other examples include styrene, paramethyl styrene, 4-phenyl- 1 -butene and allyl benzene.

[0040] Diolefin monomers may include any suitable hydrocarbon structure, e.g. a C4 to C30, 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, more 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, norbornadiene, ethylidene norbornene, divinylbenzene, dicyclopentadiene, or higher ring containing diolefins with or without substituents at various ring positions.

[0041] In an embodiment, 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 50 ppm, 100 ppm, or 150 ppm to about 500 ppm, 400 ppm, or 300 ppm.

[0042] Polyethylene copolymers can include at least 50 wt% ethylene and have a C3 to C20 comonomer, C4 to C12 comonomer, 1-hexene or 1-octene comonomer wt% of about 50 wt% or less, about 10 wt% or less, or about 1 wt% or less, such as about 1 wt% to about 30 wt%, about 1 wt% to about 5 wt%, based upon the weight of the copolymer.

[0043] A polyethylene may include from about 70 mol% to about 100 mol% of units derived from ethylene. The ethylene content may be from a low of about any one of 70, 75, 80, 85, 90, 92, 94, 95, 96, 97, 98, or 99 mol%, to a high of about any one of 80, 85, 90, 92, 94, 95, 96, 97, 98, 99, 99.5, 99.9, or 100 mol%, provided the high end of the range is greater than the low end; and further noting that such mol%s are of polymer units derived from ethylene out of the total polymer units derived from any monomer in the polyethylene. For polyethylene copolymers, the polyethylene copolymer may have about 50 mol% or less of polymer units derived from a comonomer, e.g. C3-C20 olefins or alpha-olefins. The comonomer content may be from 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%, to a high end of 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%, such mol%s being of polymer units derived from the comonomer out of the total polymer units derived from any monomer in the ethylene copolymer.

Polyethylene Properties

[0044] 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, the Mz/Mw 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 was 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 J/g to about 260 J/g, about 5 J/g to about 240 J/g, or about 10 J/g 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 greater, about 20 or greater, about 30 or greater, about 40 or greater, or 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, or greater, 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 0.93 g/cm³, or about 0.94 g/cm³ to about 0.955 g/cm³, about 0.95 g/cm³, about 0.94 g/cm³, about 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 MI2_.16) 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);

(l) a melt index ratio (MIR) of from about 10 to about 100, from about 15 to about 80, from about 25 to about 60, from about 10 to about 50, from about 30 to about 55, from about 35 to about 50, from about 40 to about 46, 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 (MI21.6 (190 °C, 21.6 kg)/MI_2.i6 (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 ah, 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, about 1.8, about 1.9, about 2, about 2.5, about 3, about 4, about 4.4, to about 5.5, about 5, about 4.5, 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. The 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 0.75 or greater, about 0.8 or greater, 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]²lin. 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. “[Rgj_br” is the Radius of Gyration for the branched polymer sample and “[Rgji_m” is the Radius of Gyration for a linear polymer sample; and/or

(p) an amount of long chain branching of about 3 long-chain branch/1000 carbon atoms or less, 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 0.75 or greater, about 0.8 or greater, 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. There are various methods 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 long-chain branching can be quantified using the method of Randall (Journal of Macromolecular 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 techniques 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 and, therefore, 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

[0045] In some embodiments, a polyethylene is a first type of LLDPE (EHl-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 C3 to C20 a-olefin comonomers, such as C3 to C₁₂ a-olefins, C₄ to C₁₂ 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.

[0046] An EHl-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 of the above- enumerated values, e.g., about 70% to about 98%, about 80 to about 95%, about 85 to about 90% etc. [0047] A EHl-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 0.927 g/cm³ or greater, about 0.930 g/cm³ or greater, about 0.932 g/cm³ or greater. Additionally, an EHl-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 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 0.927 g/cm³ to about 0.95 g/cm³, about 0.927 g/cm³ to about 0.940 g/cm³, etc.

[0048] An EHl-type polyethylene can be a metallocene polyethylene (mPE). The EHl- type polyethylene may have a g'_vjs of from about 0.75 to about 0.98, such as from about 0.75 to about 0.97, about 0.8 to about 0.97, about 0.85 to about 0.97, or about 0.9 to about 0.95. [0049] Suitable commercial polymers for the EHl-type polyethylene are available from ExxonMobil Chemical Company 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 the EHl-type family of polyethylene polymers. Commercial ENABLE™ mPE is available with a density range such as 0.920 g/cm³ to 0.940 g/cm³ and melt index (MH_.ib) range such as 0.3 g/10 min. to 1.0 g/10 min. Examples of ENABLE™ polymers include:

Enable™ 2703HH 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™ 2005MC mPE resin has an MI of 0.50 g/10 min and density of 0.920 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas. Enable™ 4009MC mPE resin has an MI of 0.90 g/10 min and density of 0.94 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas. Enable™ 2010CB mPE resin has an MI of 1.0 g/10min and a density of 0.92 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas. Enable™ 2305 mPE resin has an MI of 0.5 g/10min and a density of 0.923 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas. [0050] In some embodiments, a polyethylene is a second type of LLDPE (EH2-type) polyethylene including about 50 wt% or greater of polymer units derived from ethylene and 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%. EH2-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 EH2-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. EH2-type polyethylenes may have a melt index (ME_.ie) according to ASTM D1238 (190 °C/2.16 kg) of about 0.5 g/lOmin to about 5 g/10 min, or about 0.8 g/lOmin to about 1.5 g/10min. An EH2-type polyethylene can be an mPE. Such EH2-type polyethylenes can have a g’_vis of about 0.95 or greater, about 0.97 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. EH2-type polyethylenes are available from ExxonMobil Chemical Company under the trade name Exceed™ and Exceed™ XP.

[0051] 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 the EH2-type 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 (MH_.ib) range such as 0.2 g/10 min. to 19 g/10 min. Examples of EXCEED™ polymers include:

Exceed™ XP 2718CB metallocene polyethylene (mPE) resin has an MI of 2.7 g/10 min and a density of 0.918 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

Exceed™ 3518CB metallocene polyethylene (mPE) resin has an MI of 3.5 g/10 min and a density of 0.918 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

Exceed™ 1518 metallocene polyethylene (mPE) resin has an MI of 1.5 g/10 min and a density of 0.918 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas.

Exceed™ XP 8318 metallocene polyethylene (mPE) resin has an MI of 1.0 g/10 min and a density of 0.918 g/cm³, and is commercially available from ExxonMobil Chemical Company, Houston, Texas. Exceed™ 2718HA metallocene polyethylene (mPE) resin has an MI of 2.7 g/10 min and a density of 0.918 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

[0052] Polyethylene may 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; 6,242,545; 6,248,845; 6,255,426; 6,324,566; 6,384,142; 6,476,171; and 7,951,873 and WO Publication Nos. 2004/000919, 2004/022646, 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).

[0053] In at least one embodiment, 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-C3-4 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.

[0054] In some 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.

[0055] 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, 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.

Propylene-based Elastomers

[0056] In some embodiments , a propylene-based elastomer may be used in the formulation of a multilayer film. In some embodiments, a polyethylene may be blended with a propylene- based elastomer. The propylene -based elastomer may be 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 C4 to C10 a-olefin derived units, and optionally diene-derived units, the remainder of the polymer being propylene- derived units. Not intended to be limited by theory, it is believed that 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. 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.

[0057] 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 C10 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. [0058] 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).

[0059] 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.

[0060] In embodiments where more than one comonomers derived from at least one of ethylene or a C4 to C10 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.

[0061] 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.

[0062] 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 other comonomers 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 other comonomers intentionally added to the polymerization process.

[0063] 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-norbornene, divinylbenzene, 1 ,4-hexadiene, 5-methylene-2- norbornene, 1 ,6-octadiene, 5 -methyl- 1, 4-hexadiene, 3,7-dimethyl-l,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.

[0064] Propylene-based elastomers may be synthesized according to U.S. Patent No. 7,390,866. Propylene-based Elastomer Properties

[0065] In an embodiment, the propylene-based elastomer has a heat of fusion (“H_f”), 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 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.

[0066] The propylene-based elastomer may have a percent crystallinity, as determined according to the DSC procedure described, 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.

[0067] 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.

[0068] The propylene -based elastomer may have a single peak melting transition as determined by DSC. In some embodiments, 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. Secondary melting peaks are considered together as a single melting point, with the highest of these peaks being considered the T_m 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„, 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.

[0069] 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 the sample to 200 °C at a rate of 10 °C/minute. 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). [0070] 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.

[0071] 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.

[0072] 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). [0073] 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’j 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.

[0074] 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

[0074] Propylene-based elastomer may be produced 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.

Multilayer Films

[0075] 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 includes a polyethylene polymer, optionally mixed with a second or third polyethylene polymer or other polymers or additives. [0076] The multilayer film may have a 1/2/3 structure where 1 and 3 are outer layers and 2 is a central layer disposed between the outer layers. Suitably one or both of the first layer and the third layer can be an outermost layer forming one or both film surfaces. The composition of the polyethylene of the first layer and the polyethylene of the third layer may be the same or different. Either of the polyethylene of the first layer and the polyethylene of the third layer may have a higher or lower density than that of the polyethylene of the second layer. In at least one embodiment, at least one of the polyethylenes of the first layer and the third layer has a density higher than that of the polyethylene of the second layer. In some embodiments, the polyethylene of the first layer and the polyethylene of the third layer have substantially the same chemical composition.

[0077] 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 polyethylene of the fourth layer and the polyethylene of the fifth layer may also be the same or different. The polyethylene of the first layer and the polyethylene of the third layer may have the same composition or different compositions from the polyethylene of the fourth layer and the polyethylene of the fifth layer. In at least one embodiment, at least one of the polyethylene of the fourth layer and the polyethylene of the fifth layer has a different composition than that of the polyethylene of the first layer and the polyethylene of the third layer. In another embodiment, the polyethylene of the first layer and the polyethylene of the third layer have substantially the same chemical composition, and the polyethylene of the fourth layer and the polyethylene of the fifth layer have substantially the same chemical composition different from the polyethylene of the first layer and the polyethylene of the third layer. In another embodiment, the polyethylene of the first layer, the polyethylene of the third layer, the polyethylene of the fourth layer and the polyethylene of the fifth layer have substantially the same chemical composition.

[0078] In at least one embodiment, a multilayer film includes in at least one layer at least one of LLDPE, LDPE and HDPE. In some embodiments, where the multilayer film includes in the first layer and/or the third layer at least one of LLDPE, LDPE, HDPE, or combination(s) thereof, the polyethylene homopolymer may be present in an amount of about 30 wt% or greater, for example, from about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt%, about 50 wt%, about 55 wt%, about or 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. Often LLDPE is used in the outer layers of a stretch wrap film to provide cling as pallets and good are wrapped. The addition of elastomers, such as propylene-based elastomers to one of the outer layers may improve the cling of stretch wrap films.

[0079] In some embodiments, a multilayer film includes in at least one layer 100 wt% of an EAO copolymer, based on total weight of polymer in the layer. In some embodiments, a multilayer film includes in at least one layer 100 wt% of an EH copolymer, based on total weight of polymer in the layer. In some embodiments, the first layer, the second layer, and the third layer each include an EAO copolymer, such as an EH copolymer. In some embodiments, the second layer, the fourth layer, and the fifth layer each include an EAO copolymer, such as an EH copolymer.

[0080] In some embodiments, the LLDPE, LDPE, and HDPE present in a given layer may be a blend with one or more other polymers, such as polyethylenes or propylene -based elastomers, which blend may be referred to as a polyethylene composition. In some embodiments, the polyethylene compositions described may be physical blends or in situ blends of more than one type of polyethylene or compositions of polyethylenes with polymers other than polyethylenes. In some embodiments, a polyethylene composition is a blend of two polyethylenes with different densities.

[0081] In another embodiment, the polyethylene composition is an EAO copolymer blended with a second polyethylene. In at least one embodiment, the EAO copolymer is an EH copolymer blended with a second polyethylene. The second polyethylene may be a homopolymer or a copolymer different from the EAO copolymer. In an embodiment where the polyethylene composition is a homopolymer:copolymer blend, the polyethylene homopolymer in the 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.

[0082] In some embodiments, the first layer and the third layer include LLDPE, LDPE, or HDPE in some percentage. In some embodiments, the first layer and the third layer include LLDPE, LDPE, HDPE in about 75 wt% or greater. In at least one embodiment, a multilayer film includes in each of the first layer and the third layer about 95 wt% or greater of a LLDPE, based on total weight of polymer in the first layer and the third layer. In some embodiments, the first layer include a polyethylene composition including LLDPE and a propylene -based elastomer, such as about 75 wt% or greater, about 80 wt% or greater, about 85 wt% or greater, about 90 wt% or greater, about 95 wt% or greater LLDPE, with the remaining wt% including the propylene-based elastomer, based on the total weight of polymer in the first layer. In some embodiments, a multilayer film includes in each of the first layer or the third layer 100 wt% of an HDPE, based on total weight of polymer in the first layer or the third layer. In other embodiments, the first layer and the third layer include a polyethylene copolymer and, in at least one embodiment, the polyethylene copolymer is an EAO copolymer. In some embodiments, the polyethylene copolymer of the first layer and the third layer is an EH copolymer, such as an EH 1 -type polyethylene or an EH2-type polyethylene. In some embodiments, a multilayer film include in each of the first layer and the third layer 100 wt% of an EH2-type polyethylene based on the total weight of polymer in each layer.

[0083] In some embodiments, the second layer includes a polyethylene copolymer. The polyethylene copolymer may be an EAO copolymer, such as an EH copolymer. In some embodiment, the second layer includes 100 wt% of an EH copolymer based on the total weight of polymer in the second layer, such as 100 wt% of an EHl-type polyethylene or an EH2-type polyethylene. In some embodiments, the second layer includes 100 wt% of a polyethylene composition based on the total weight of polymer in the second layer. In some embodiments, the polyethylene composition of the second layer is a combination of homopolyethylene and an EAO copolymer, such as an EH copolymer. In other embodiments, the polyethylene composition of the second layer is a combination of different EAO copolymers. In some embodiments, the second layer includes a first EH copolymer and a second EH copolymer. In some embodiments, the first EH copolymer and the second EH copolymers are individually selected from an EHl-type polyethylene or an EH2-type polyethylene. In some embodiments, the second layer includes 100 wt% of a polyethylene composition including about 55 wt% or greater of an EHl-type polyethylene based on the total weight of polymer in the second layer, such as about 60 wt% or greater, about 65 wt% or greater, about 70 wt% or greater, about 75 wt% or greater, about 80 wt% or greater, about 85 wt% or greater, about 90 wt% or greater, about 95 wt% or greater of an EHl-type polyethylene. Additionally, in some embodiments, the remaining wt% of the polyethylene composition includes an EH2-type polyethylene. In at least one embodiment, the second layer includes 100 wt% of an EHl-type polyethylene based on the total weight of polymer in the second layer.

[0084] In some embodiments, a multilayer film includes in each of the fourth layer and the fifth layer 100 wt% of an EAO copolymer, based on total weight of polymer in the fourth layer and the fifth layer. In some embodiments, a multilayer film includes in each of the fourth layer and the fifth layer 100 wt% of and EH copolymer, such as an EHl-type polyethylene or an EH2-type polyethylene, based on the total weight of polymer in each of the fourth and fifth layers. [0085] In some embodiments, at least one of LLDPE, LDPE, and HDPE is present in the first layer and/or the third layer, and the polyethylene present in the second layer is a polyethylene composition. In at least one embodiment, at least one of LLDPE, LDPE, and HDPE is present in the first layer and/or the third layer, and the polyethylene present in the second layer is an EH copolymer.

[0086] In some embodiments, the first layer, the second layer, and the third layer each include 100 wt% of an EH copolymer. In at least one embodiment, the first layer and the third layer include 100 wt% of an EH2-type polyethylene and the second layer includes 100 wt% of an EHl-type polyethylene, based on the total weight of polymer within each layer.

[0087] In some embodiments, a multilayer film includes in each of the first layer and the third layer about 95 wt% or greater of an LLDPE, based on total weight of polymer in the first layer and the third layer; in the second layer 100 wt% of an EAO copolymer or a polyethylene composition; and in each of the fourth layer and the fifth layer 100 wt% of an EAO copolymer, based on total weight of polymer in the fourth layer and the fifth layer. In at least one embodiment, a multilayer film includes in one of the first layer and the third layer 100 wt% of an LLDPE, LDPE, HDPE, based on total weight of polymer in the first layer or the third layer; in the second layer 100 wt% of an polyethylene composition; and in each of the fourth layer and the fifth layer 100 wt% of an EH copolymer, based on total weight of polymer in the fourth layer and the fifth layer.

[0088] In at least one embodiment, the multilayer film has a three-layer 1/2/3 structure, including: (a) the first layer and the third layer, each including 100 wt% of a first EAO copolymer, based on total weight of polymer in each of the first layer and the third layer, where the first EAO copolymer has a density of about 0.91 g/cm³ to about 0.92 g/cm³, and an MI2.16 of about 0.1 g/10 min to about 15 g/10 min; and (b) a second layer disposed between the first layer and the third layer including 100 wt% of a second EAO copolymer, based on the total weight of polymer in the second layer, where the second EAO copolymer has a density of about 0.92 g/cm³ to about 0.95 g/cm³, and an MI2.16 of about 0.1 g/10 min to about 15 g/10 min. In at least one embodiment, the first EAO copolymer is an EH copolymer, such as an EH2-type polyethylene. In at least one embodiment, the second EAO copolymer is an EH copolymer, such as an EHl-type polyethylene. In at least one embodiment, the first EAO copolymer is an EH2-type polyethylene and the second EAO copolymer is an EHl-type polyethylene.

[0089] In at least one embodiment, the multilayer film has a five layer 1/4/2/5/3 structure, including: (a) the first layer and the third layer, each including about 95 wt% or greater of an LLDPE, where the LLDPE has a density of about 0.91 g/cm³ to about 0.925 g/cm³; (b) the fourth and the fifth layer, each including about 100 wt% of a first EAO copolymer based on total weight of polymer in each of the fourth layer and the fifth layer, where the first EAO copolymer has a density of about 0.91 g/cm³ to about 0.92 g/cm³, and an MI2.16 of about 0.1 g/10 min to about 15 g/10 min; and (b) a second layer disposed between the fourth layer and the fifth layer including 100 wt% of a second EAO copolymer, based on the total weight of polymer in the second layer, where the second EAO copolymer has a density of about 0.92 g/cm³ to about 0.95 g/cm³, and an MI2.16 of about 0.1 g/10 min to about 15 g/10 min. In at least one embodiment, the first EAO copolymer is an EH copolymer, such as an EH2-type polyethylene. In at least one embodiment, the second EAO copolymer is an EH copolymer, such as an EH 1 -type polyethylene. In at least one embodiment, the first EAO copolymer is an EH2-type polyethylene and the second EAO copolymer is an EH 1 -type polyethylene.

[0090] Any of the polyethylenes of the first layer, the third layer, the fourth layer or the fifth layer may have a higher or lower density than the polyethylene of the second layer. In at least one embodiment, the polyethylenes of the first layer, the third layer, the fourth layer, and the fifth layer have a density lower than the density of the polyethylene of the second layer. In at least one embodiment, the polyethylenes of the first layer, the third layer, the fourth layer and the fifth layer have a similar density (± 0.001 g/cm³).

[0091] The multilayer films can have a thickness of about 5 pm to about 20 pm, such as about 5 pm to about 18 pm, or about 6 pm to about 15 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 form 10% to 35%, or 15% to 30% of the total final thickness of the 3-layered film, the second layer forming the remaining thickness, e.g. 30% to 80%, or 40% to 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%.

[0092] 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: 5% to 30%, or 5% to 20% for each of the first layer and the third layer, 5% to 30%, or 10% to 20% for each of the fourth layer and the fifth layer, and/or 20% to 70%, or 25% to 60% for the second layer. [0093] In some embodiments, the second layer is thicker than each of the first layer, the third layer, the fourth layer, and the fifth layers. In at least one embodiment, the second layer is thicker than the combination of the individual thicknesses of first layer, the third layer, the fourth layer, and the fifth layers. [0094] In some embodiments, the first layer and the third layer are of equal thickness. In some embodiments, the fourth layer and the fifth layer are of equal thickness. In at least one embodiment, the fourth layer and the fifth layer are thicker than the first layer and the third layer. In at least one embodiment, the first layer and the third layer contribute 10% each to the total thickness of the multilayer film, the fourth layer and the fifth layer contribute 12.5% each to the total thickness of the multilayer film, and the second layer contributes 55% to the total thickness of the multilayer film.

Multilayer Film Properties

[0095] Where applicable, the properties and descriptions below are intended to encompass measurements in both the machine direction (MD) and the transverse direction (TD). Such measurements are reported separately, with the designation “MD” indicating a measurement in the machine direction, and “TD” indicating a measurement in the transverse direction. [0096] 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 is 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 (DS) or in a direction perpendicular to stretching (PS).

[0097] Multilayer films of the present disclosure may have one or more of the following properties:

(a) A 1% secant modulus in the MD of about 100 MPa or greater, from about 100 MPa to about 400 MPa, from about 150 MPa to about 350 MPa, from about 150 MPa to about 300 MPa, from about 150 MPa to about 250 MPa, or from about 160 MPa to about 200 MPa, as determined by ASTM D882 where 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;

(b) 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 MD, as determined by ASTM D 882 by (ii) the thickness of the multilayer film in millimeters. (c) A 1% secant modulus in the TD of about 400 MPa or less about 300 MPa or less, or about 250 MPa or less. For example, the 1% Secant Modulus in the transverse direction 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;

(d) A total thickness of from about 4 pm to about 20 pm, from about 6 pm to about 18 pm, or from about 7 pm to about 15 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 5% to about 20%. The thickness ratio between one of the first layer or the third layer and the second layer may be about 1:1 to about 1:8, for example, about 1:1, about 1:2, about 1:3, about 1:4, about 1:5, about 1:5.5, or about 1:6;

(e) An Elmendorf Tear Strength (tear resistance) in the MD of at about 0.5 g/pm or greater, about 1 g/pm or greater, about 2 g/pm or greater, about 4 g/pm or greater, about 6 g/pm or greater, or about 8 g/pm or greater. For example, the Elmendorf Tear strength in the MD can be from about 0.5 g/pm to about 20 g/pm, from about 0.5 g/pm to about 15 g/pm, from about 1 g/pm to about 12 g/pm, from about 2 g/pm to about 11 g/pm, or from about 4 g/pm to about 10 g/pm, as determined by ASTM D1922-06a, which measures the energy used to continue a pre-cut tear in the test sample, expressed in (g/pm). Samples were cut across the web using the constant radius tear die and were free of visible defects (e.g., die lines, gels, etc.);

(f) 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 60% or greater, about 70% or greater, about 75% or greater, about 80% or greater, about 85% or greater, about 90% or greater, about 95% or greater, as determined by ASTM D1746;

(g) A Gloss of about 30% or greater, about 40% or greater, about 50% or greater, about 60% or greater, about 70% or greater, about 80% or greater, about 90% 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;

(h) A tensile strength at yield in the machine direction of about 3 MPa or greater, such as about 5 MPa or greater, about 7 MPa or greater, about 9.5 MPa or greater, or about 12 MPa or greater as determined by ASTM D-1708; (i) A tensile strength at from 10% to 30% elongation in the machine direction of about 1.3 N or greater, such as about 1.4 N or greater, about 1.5 N or greater, about 1.6 N or greater, or about 1.7 N or greater as determined by ASTM D412;

(j) A tensile strength at yield in the transverse direction of about 3 MPa or greater, such as about 5 MPa or greater, about 7 MPa or greater, about 10 MPa or greater, or about 12 MPa or greater as determined by ASTM D-1708;

(k) A Elmendorf tear strength in the machine direction of about 20 g or greater, such as about 30 g or greater, about 40 g or greater, about 50 g or greater, or about 60 g or greater as determined by ASTM D-1922;

(l) A Elmendorf tear strength in the transverse direction of about 500 g or greater, such as about 525 g or greater, about 550 g or greater, about 575 g or greater, or about 600 g or greater as determined by ASTM D-1922;

(m) A dart drop impact strength of about 100 g or greater, such as about 110 g or greater, about 120 g or greater, about 130 g or greater, or about 150 g or greater as determined by ASTM D-1709;

[0098] In certain embodiments, the film has at least two, at least three, at least four, or more of the foregoing properties.

Additives

[0099] The multilayer film may also contain in at least one layer various additives. Examples of such additives include a filler, an antioxidant, an ultraviolet light stabilizer, a thermal stabilizer, a pigment, a processing aid, a crosslinking catalyst, a flame retardant, and a foaming agent, etc. In some embodiments, the additives may each individually present in an amount of about 0.01 wt % to about 50 wt %, or about 0.1 wt % to about 10 wt %, or from 1 wt % to 5 wt %, based on total weight of the film layer.

[0100] Any additive useful for the multilayer film may be provided separately or together with other additive(s) of the same or a different type in a pre-blended masterbatch, where the target concentration of the additive is reached by combining each neat additive component in an appropriate amount to make the final composition.

Multilayer Film Production

[0101] Also provided are methods for making multilayer films of the present disclosure. A method for making an 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 and the third layer include an EAO copolymer or a polyethylene composition including an EAO copolymer independently selected from (i) a polyethylene having a density of about 0.94 g/cc or greater; (ii) a polyethylene copolymer including ethylene and a C4-C12 alpha-olefin having a density from about 0.927 g/cc to about 0.95 g/cc; or (iii) a mixture thereof, where at least one of the first layer or the third layer includes the polyethylene copolymer, where the second layer includes a polyethylene composition having a density of about 0.91 g/cc or greater.

[0102] 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, where the fourth layer includes a polyethylene.

[0103] 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, where the fifth layer includes a polyethylene.

[0104] A multilayer film may be formed by any suitable technique 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 coupled with each other (e.g., adhered together) but differing in composition. Coextrusion may be adapted to cast film or blown film processes. Multilayer films may also be formed by combining two or more single layer films prepared as described above.

[0105] For example, the composition may be extruded in a molten state through a flat die and then rolled across cooling rollers to form a cast film, which can be cut and wound for end use.

[0106] As a specific example, cast films can be prepared as follows. The polyethylenes may be introduced individually into the feed hoppers of extruders, such as a 50 mm extruder that is water-cooled, resistance heated, and has an L/D ratio of 30:1. The multilayer film can be produced using a flat die with a 0.5 mm die gap die gap between 0.4- 1.2mm. 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 flat film that is cooled and, optionally, subjected to a desired auxiliary process, such as slitting, treating, sealing, or printing. Typical melt temperatures are from about 240 °C to about 300 °C. The rate of extrusion for a cast film is generally from about 0.5 to about 2 kilograms per hour per millimeter of die length. The finished film can be wound into rolls for later processing. Any suitable cast film process and apparatus suitable for forming films according to embodiments of the present disclosure may be used. Other film forming methods may also be used.

Film Properties and Applications [0107] Films may be used for any suitable purpose, and are well suited to stretch film applications. The films described may display outstanding properties as demonstrated by tensile strength, resistance to puncture and tearing, elastic recovery, transparency, which is especially important for stretch film applications. The multilayer film described can be used to establish a sufficient holding force and also to improve the film behavior during extension and after contraction around a load with reduced risk of tearing or puncturing. The multilayer film described may also provide sufficient lock-in, such that goods on a pallet do not shift during transit.

[0108] Additionally, the multilayer films described have a double-yield point which provides for more consistent wrapping when used as a hand wrap. Additionally, the force involved in reaching the double-yield point is lower than other films meaning that the films may be applied with less operator fatigue, which may also lead to more consistent wrapping. [0109] A film yields when the standard force used to elongate the film has little to no change. The yield can be seen as a flat section on a graph of machine direction tensile strength comparing elongation in percent to standard force. Therefore, the yield point is the point at which the Aforce (change in force) that causes about 10% or more elongation of the film is about 0.4N or less. When the film reaches a yield point the additional force to cause further elongation is small, or said in another way, the change in the force used to stretch the film further is small. A film with a double yield point include two such yield points. Multilayer films described may have a first yield point at about 1 N/15mm to about 2 N/15mm, such as about 1.2 N/15mm to about 2 N/15mm, about 1.3 N/15mm to about 1.9 N/15mm, or about 1.5 N/15mm to about 1.8 N/15mm. Multilayer films may have a second yield point of about 3 N/15mm to about 4N/15mm, such as about 3 N/1 mm to about 3.8 N/15mm, about 3.2 N/15mm to about 3.8 N/15mm, or about 3.4 N/15mm to about 3.7 N/15mm.

[0110] Multilayer films may be used to wrap goods on a pallet. The films described provide ability to both bundle the goods (holding force) and keep them in place during transit (lock-in force). The holding force may be characterized as a force provided per gram of the multilayer film per cubic meter of the pallet. Multilayer films described provide a holding force with fewer grams of film than previously described films and, therefore, a pallet wrapped in a multilayer film would use less total polymer to provide sufficient holding to bundle the goods. For example, a pallet wrapped in a multilayer film may experience a holding force of about 1 N or greater per gram of the multilayer film per cubic meter of the pallet and goods, such as about 1.1 N or greater, about 1.15 N or greater, about 1.2 N or greater, about 1.3 N or greater, about 1.5 N or greater, or about 2 N or greater. Examples

General

[0111] The density was measured according to ISO 1183 using ISO 1872-2 for sample preparation.

[0112] Example 1. A multilayer film of five layers was produced on a cast film line equipped with a 0.6 mm die gap the dies were at a temperature of 280 °C. The chill roll temperature was about 15 °C to about 35 °C. The production was made at an output of 893 kg/h, at a line speed of 500m/min. The first layer was formed from a blend of 96% LL1004YB (which is an LLDPE with a density of 0.918 and a ME_.ib oί 2.8 g/lOmin). The second layer was formed from Exceed™ 3518CB (which is an EH copolymer with density of 0.918 g/cm³, and an MI of 3.5 g/10 min. The third layer was formed from Enable™ 2010CB (which is an EH copolymer with a density of 0.92 g/cm³, and a MI2.16 of 1.0 g/lOmin). The fourth layer was formed from Exceed™ 3518CB. The fifth layer was formed fromLL1004YB. The fourth layer was disposed between the first and second layers, and the fifth layer was disposed between the second and third layers. The multilayer film had a thickness distribution of 10/12.5/55/12.5/10, the first layer, and the third layer having the same thickness; the fourth layer, and the fifth layer having the same thickness 1.25 times the thickness of the first layer and the third layer; and the second layer being 5.5 times as think as the first layer and the third layer. The multilayer films were cooled down on to a chill roll at temperatures of 20 °C and 20 °C. The multilayer film had a total thickness of 12 microns. The multilayer film had a tensile strength in the MD of 84.2MPa, a tensile strength in the TD of 36.8MPa, and a second yield point at 25.3MPa. [0113] Comparative Example 2. A commercially purchased 7 micron pre-stretch film had a tensile strength in the MD of 183 MPa, a tensile strength in the TD of 27 Pa, and a second yield point at 38.4 MPa.

[0114] Comparative Example 3 A commercially purchased 18 micron handwrap film had a tensile strength in the MD of 67 MPa, a tensile strength in the TD of 25 MPa, and a second yield point at 14.3.

[0115] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the Drawings.

[0116] FIG. 1A is a graph of tensile strength in the machine direction of polyolefin films both according to an embodiment and comparative examples. Line 101 represents a pre stretched film with a film thickness of 7 microns according to comparative example 2. Line 103 represents the film of example 1 with a thickness of 12 microns. Line 105 represents a handwrap film with a thickness of 18 microns according to comparative example 3. The tensile strength in the machine direction is one measure of holding force keeping goods on a pallet bundled together.

[0117] FIG. IB is the same graph of tensile strength in the machine direction focused on a narrower % elongation of polyolefin films both according to an embodiment and comparative examples. The MD tensile strength shows the double yield point of the film according to example 1 (line 103). The force used to stretch the film increases until a certain elongation (as shown for line 103 about 5-6%) and then the force needed to continue elongation changes very minimally, the film yields to the stretching. After about 25-35% elongation the force to continue stretching the film increases more dramatically and at about 50% elongation the force used to continue stretching the film does not change, showing the second yield point, therefore, line 103 has a double-yield point.

[0118] FIG. 2A is a graph of tensile strength in the transverse direction of polyolefin films both according to an embodiment and comparative examples. The tensile strength in the transverse direction is one measure of lock-in force for goods on a pallet meaning that the goods are less likely to shift during transport.

[0119] FIG. 2B is the same graph of tensile strength in the transverse direction focused on a narrower % elongation of polyolefin films both according to an embodiment and comparative examples. The film shown as 103 excels in lock-in of goods on a pallet because there is sufficient TD strength and high puncture resistance. The film shown as line 101 has TD tensile strength, but insufficient puncture resistance and changes in momentum cause the goods to shift on the pallet. The pre- stretched film represented by line 105 has too little TD tensile strength to maintain tension after elongation and, therefore, does not provide sufficient lock-in to keep the good in place during changes in momentum during transit.

[0120] Overall, it has been discovered that combinations of polyethylenes in multilayer stretch wrap film may provide sufficient holding force and lock-in to keep goods both bundled together and stationary in regards to the pallet on which they are placed. Additionally, such multilayer films may provide holding force and lock-in while also using a lower quantity of film (by weight) than comparative handwrap or pre-stretched films. Furthermore, the multilayer films may have a double yield point indicating to an operator how much stretched should be accomplished when wrapping to provide improved shipping results over other films. [0121] The phrases, unless otherwise specified, "consists essentially of" and "consisting essentially of" do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of this disclosure, additionally, they do not exclude impurities and variances normally associated with the elements and materials used. [0122] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, a range includes every point or individual value between its end points 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.

[0123] All documents described herein are incorporated by reference herein, including any priority documents and/or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of this disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of this disclosure. Accordingly, it is not intended that this disclosure be limited thereby. Likewise whenever a composition, an element or a group of elements is preceded with the transitional phrase “including,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa. The films and processes disclosed may be practiced in the absence of any element which is not disclosed herein.

[0124] While the present disclosure has been described with respect to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the present disclosure.

Claims

CLAIMS What is claimed is:

1. A multilayer film comprising: a first layer comprising a first polymer comprising polyethylene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³; a second layer disposed on the first layer, the second layer comprising a blend of (i) a second polymer comprising a copolymer of ethylene and hexene having a density of from about 0.92 g/cm³ to about 0.93 g/cm³ and a melt index of from about 0.3 g/lOmin to about 1 g/lOmin and (ii) a third polymer comprising a copolymer of ethylene and hexene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³ and a melt index of from about 2 g/lOmin to about 4 g/lOmin; and a third layer disposed on the second layer, the third layer comprising a fourth polymer comprising polyethylene having a density of about 0.91 g/cm³to about 0.92 g/cm³.

2. The multilayer film of claim 1, wherein the second layer has a thickness that is at least twice a thickness of the first layer or the third layer.

3. The multilayer film of claim 1, wherein the second layer has a thickness that is at least twice a thickness of the first layer and the third layer combined.

4. The multilayer film of claim 1 or any one of claims 2 or 3, wherein the multilayer film has one or more of the following properties:

(i) an average tensile strength at yield in the transverse direction of about 10 MPa or greater;

(ii) an Elmendorf tear strength in the transverse direction of about 300 g or greater;

(iii) an average tensile strength at yield in the machine direction of about 9.5 MPa or greater;

(iv) an Elmendorf tear strength in the machine direction of about 40 g or greater;

(v) a dart impact strength of about 70 g or greater;

(vi) a first yield point from about 1.2 N/15mm to about 2 N/15mm in the machine direction;

(vii) a second yield point from about 3 N/15mm to about 3.8 N/15mm; and

(viii) a tensile strength from 10% to 30% elongation in the transverse direction of about 1.6 N/15mm or greater.

5. The multilayer film of claim 1 or any one of claims 2-4, wherein the multilayer film has a thickness of about 12 mhi or less.

6. A multilayer film comprising: a first layer comprising a first polymer comprising polyethylene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³; a second layer disposed on the first layer, the second layer comprising a second polymer comprising a copolymer of ethylene and hexene having a density of from about 0.92 g/cm³ to about 0.93 g/cm³; a third layer disposed on the second layer, the third layer comprising a third polymer comprising a polyethylene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³; a fourth layer disposed between the first layer and the second layer, the fourth layer comprising a fourth polymer comprising a copolymer of ethylene and hexene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³; and a fifth layer disposed between the second layer and the third layer, the fifth layer comprising a fifth polymer comprising a copolymer of ethylene and hexene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³.

7. The multilayer film of claim 13 , wherein the multilayer film has one or more of the following properties:

(ii) an Elmendorf tear strength in the transverse direction of about 550 g or greater;

(v) a thickness of about 12 pm or less;

(vi) a dart impact strength of about 130 g or greater;

(vii) a first yield point at about 1.6 N/15mm in the machine direction;

(viii) a second yield point at about 3.6 N/15mm in the machine direction; and

(ix) a tensile strength in the transverse direction of about 1.6 N/15mm or greater from 10% to 30% elongation.

8. A method for preparing a 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 first polymer comprising polyethylene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³; the second layer comprises an second polymer comprising a copolymer of ethylene and hexene having a density of about 0.92 g/cm³ to about 0.93 g/cm³ and a melt index of from about 0.3 g/lOmin to about 1 g/10min; and the third layer comprising a third polymer comprising polyethylene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³.

9. The method of claim 8, wherein the extruding further comprises extruding through a feedblock and a flattening die.

10. The method of claim 8 or claim 9, wherein the second layer further comprises a fourth polymer comprising a copolymer of ethylene and hexene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³ and a melt index of from about 2 g/lOmin to about 4 g/lOmin.

11. The method of claim 8 or any one of claims 9 and 10, further comprising extruding a fourth layer comprising fifth polymer comprising a polyethylene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³ and a melt index of from about 2 g/lOmin to about 4 g/lOmin, the fourth layer disposed between the first layer and the second layer wherein the multilayer film has the fourth layer disposed between the first layer and the second layer.

12. The method of claim 11, further comprising extruding a fifth layer comprising a sixth polymer comprising a polyethylene having a density of from about 0.91 g/cm³ to about 0.92 g/cm³ and a melt index of from about 2 g/lOmin to about 4 g/lOmin, the fifth layer disposed between the second layer and the third layer wherein the multilayer film has the fifth layer disposed between the second layer and the third layer.

13. The method of claim 12, wherein the fifth polymer and the sixth polymer have substantially the same chemical composition.

14. A pallet wrapped in the multilayer film of any of claims 1 to 7, wherein the multilayer film is configured to provide a holding force of about 1.15 N per gram of the multilayer film per cubic meter of the pallet and goods.

15. A pallet wrapped in a multilayer film, wherein the multilayer film is configured to provide a holding force of about 1.15 N per gram of the multilayer film per cubic meter of the pallet and goods.