Multilayer films containing ethylene-based polymers

Abstract

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

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to multilayer films, and more specifically to multilayer films comprising ethylene-based polymers. [Background technology]

[0002] Introduction Multilayer films incorporating various materials, including polypropylene, polyamide, and polyethylene terephthalate, are widely used in industrial and consumer products. Such films used in industrial and consumer products often require sufficient tear resistance to avoid the film being damaged during the film packaging process, for example, on a pallet. Although the combination of layers and materials can enable good performance of the film, such multilayer films can be difficult, if not impossible, to recycle together due to different types of materials that are not recyclable with each other. As the demand for sustainable and recyclable materials continues to rise, there remains a need for multilayer films that can be more easily recycled and have similar or improved performance characteristics, such as tear resistance. Summary of the Invention

[0003] The present disclosure satisfies one or more of the above-mentioned needs by providing a multilayer film that exhibits comparable or improved tear resistance and includes a recyclable ethylene-based polymer. The multilayer film can be fully recyclable in the polyethylene recycle stream, and the tear resistance performance of the multilayer film of the present invention can be comparable to or better than other multilayer films that do not include the recyclable polymer.

[0004] Disclosed herein is a multilayer film. In one embodiment, the multilayer film includes a first outer layer, a second outer layer, and a core, the core includes one or more core layers, the core layer being disposed between the first outer layer and the second outer layer, the core includes 100 wt. % ethylene-based polymer, based on the total polymer weight of the core, the first core layer includes an ethylene-propylene copolymer including 60-95 wt. % ethylene monomer and 5-40 wt. % propylene comonomer, and the ethylene-propylene copolymer has the following properties: 0.890-0.920 g / cm 3 a heat of fusion in the range of 90-150 J / g, a melt index (I2) of at least 0.5 g / 10 min or more, a single peak in the improved comonomer composition distribution (ICCD) elution profile in the temperature range between 40-100° C., and a molecular weight distribution Mw / Mn of 1.5-5.0.

[0005] These and other embodiments are described in greater detail in the Detailed Description. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram of a single reactor data flow diagram. [Diagram 2] 1 is an ICCD elution profile of Poly.1, a generated resin described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Aspects of the disclosed multilayer film are described in more detail below. The multilayer film can have a wide variety of applications, including cast stretch films, blown films, oriented films, stretch food films, etc. However, the disclosure should not be construed as limiting the embodiments described below, as the disclosure is an exemplary implementation of the embodiments described herein.

[0008] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the generic term polymer encompasses the terms homopolymer (used to refer to a polymer prepared from only one type of monomer) and copolymer. Trace amounts of impurities (e.g., catalyst residues) may be incorporated and / or present in the polymer. The polymer may be a single polymer, a polymer blend, or a polymer mixture, including a mixture of polymers formed in situ during polymerization.

[0009] As used herein, the term "copolymer" refers to a polymer formed by the polymerization reaction of at least two structurally different monomers. The term "copolymer" includes terpolymers. For example, an ethylene copolymer, such as an ethylene-propylene copolymer, can include at least two structurally different monomers (e.g., an ethylene-propylene copolymer can include at least copolymerized units of an ethylene monomer and a propylene monomer), and can optionally include additional monomers or functional materials or modifiers, such as acid, acrylate, or anhydride functional groups. In other words, the copolymers described herein include at least two structurally different monomers, and while the copolymers can consist of only two structurally different monomers, they do not necessarily consist of only two structurally different monomers and can include additional monomers or functional materials or modifiers.

[0010] As used herein, the term "polyethylene" or "ethylene-based polymer" is intended to mean a polymer that contains a majority (greater than 50% by weight) of units derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Unless otherwise indicated, the ethylene copolymers disclosed herein (e.g., the ethylene-propylene copolymers described herein) are ethylene-based polymers.

[0011] Common forms of polyethylene known in the art include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (ULDPE), very low density polyethylene (VLDPE), single-site catalyzed linear low density polyethylene (m-LLDPE), including both linear and substantially linear low density resins, ethylene-based plastomers (POP) and ethylene-based elastomers (POE), medium density polyethylene (MDPE), and high density polyethylene (HDPE). These polyethylene materials are generally well known in the art. However, the following description may be helpful in understanding the differences between some of these different polyethylene resins.

[0012] The term "LDPE", which may also be referred to as "high pressure ethylene polymer", or "highly branched polyethylene", is defined to mean that the polymer is partially or fully homopolymerized or copolymerized in an autoclave or tubular reactor at pressures in excess of 14,500 psi (100 MPa) using a free radical initiator, such as peroxide (see, for example, U.S. Pat. No. 4,599,392, incorporated herein by reference). LDPE resins typically have a viscosity of 0.916 to 0.935 g / cm. 3 The density is in the range of

[0013] The term "LLDPE" includes both resins made using traditional Ziegler-Natta catalyst systems and chromium-based catalysts, as well as single-site catalysts, including, but not limited to, mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts and polyaryloxy ether catalysts (typically referred to as bisphenylphenoxy), and includes linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains less long chain branching than LDPE and includes substantially linear ethylene polymers as further defined in U.S. Patent Nos. 5,272,236, 5,278,272, 5,582,923, and 5,733,155, homogeneously branched linear ethylene polymer compositions such as those in U.S. Patent No. 3,645,992, heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent No. 4,076,698, and / or blends thereof (such as those disclosed in U.S. Patent Nos. 3,914,342 or 5,854,045). LLDPE may be made via gas phase, solution phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0014] The term "MDPE" means 0.926 to 0.935 g / cm 3 "MDPE" refers to polyethylene having a density of greater than 2.5, typically produced using chromium or Ziegler-Natta catalysts, or using single-site catalysts, including, but not limited to, substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts, and polyaryloxy ether catalysts (typically referred to as bisphenylphenoxy), and typically has a molecular weight distribution ("MWD") greater than 2.5.

[0015] The term "HDPE" refers to poly(ethylene glycol) having a viscosity of about 0.935 g / cm, typically prepared using single-site catalysts including, but not limited to, Ziegler-Natta, chromium, or substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts, and polyaryloxy ether catalysts (typically referred to as bisphenylphenoxy). 3 Super ~ maximum approx. 0.980g / cm 3 It refers to polyethylene having a density of

[0016] The term "ULDPE" refers to poly(ethylene glycol) copolymers (ULDPE) having a viscosity of 0.855 to 0.912 g / cm, typically prepared using single-site catalysts including, but not limited to, Ziegler-Natta, chromium, or substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocenes), constrained geometry catalysts, phosphinimine catalysts, and polyaryloxy ether catalysts (typically referred to as bisphenylphenoxy). 3 ULDPE refers to polyethylene having a density of 1000 to 2000 mm. ULDPE includes, but is not limited to, polyethylene (ethylene based) plastomers and polyethylene (ethylene based) elastomers.

[0017] As used herein, the term "core layer" refers to a non-skin or non-outer layer of a multilayer film. The core layer is an inner layer of a multilayer film, i.e., a layer located between two outer layers. In one embodiment, the core layer is a non-outer layer of a three-layer film including a first outer layer and a second outer layer. The entire core layer, i.e., one or more, of the multilayer film of the present invention constitutes the "core" of the film.

[0018] The terms "comprising," "including," "having," and their derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether or not they are specifically disclosed. For the avoidance of any doubt, all compositions claimed through the use of the term "comprising" may include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless otherwise stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any succeeding description any other component, step, or procedure, except those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically delineated or listed.

[0019] Disclosed herein are multilayer films. In some embodiments, the multilayer film can be an oriented film that is oriented in the machine direction and / or the transverse direction. In some embodiments, the multilayer film is a blown film. In some embodiments, the multilayer film is a cast stretch film. In further embodiments, the multilayer film is a stretch food film.

[0020] A multilayer film according to embodiments disclosed herein includes a first outer layer, a second outer layer, and a core, the core including one or more core layers. The core is disposed between the first outer layer and the second outer layer. The core includes a first core layer including an ethylene-propylene copolymer.

[0021] First and second outer layers of the multilayer film The first and second outer layers of the multilayer film are not particularly limited. The first and second outer layers can have the same polymer composition or different polymer compositions. In some embodiments, each of the first and second outer layers has a thickness that is 10 to 30% of the total thickness of the multilayer film.

[0022] In some embodiments, the first outer layer and / or the second outer layer comprises an ethylene-based polymer such as, for example, ULDPE, LLDPE, LDPE, MDPE, or HDPE. For example, in some embodiments, the first outer layer and / or the second outer layer comprises LLDPE, LDPE, or a blend thereof.

[0023] In embodiments in which the first outer layer and / or the second outer layer comprises LLDPE, the LLDPE has a viscosity of 0.940 g / cm 3 It may have a density of 0.940 g / cm 3 All individual values ​​and subranges below are included and disclosed herein, for example, the density of the LLDPE may range from 0.870, 0.880, 0.890, 0.910, or 0.920 g / cm as a lower limit. 3 from 0.940, 0.938, 0.936, or 0.935 g / cm 3 It can be up to 0.870 to 0.940 g / cm 3 All individual values ​​and subranges are included and disclosed herein.

[0024] In embodiments in which the first outer layer and / or the second outer layer comprises an LLDPE, the LLDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 50 g / 10 min. All individual values ​​and subranges from 0.1 g / 10 min to 50 g / 10 min are disclosed and included herein. For example, the LLDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 40 g / 10 min, 0.1 g / 10 min to 30 g / 10 min, 0.1 g / 10 min to 20 g / 10 min, 0.1 g / 10 min to 10 g / 10 min, or 0.1 g / 10 min to 5 g / 10 min.

[0025] Commercially available examples of LLDPE that may be used in the first and / or second outer layers include those available from The Dow Chemical Company under the ELITE™ AT name, including, for example, ELITE™ AT6410, and those available under the DOWLEX™ name, including, for example, DOWLEX™ SC2108G.

[0026] In some embodiments, the first and second outer layers comprise ULDPE. In embodiments where the first and / or second outer layers comprise ULDPE, the ULDPE has a viscosity of 0.912 g / cm 3 It may have a density of 0.912 g / cm 3 All individual values ​​and subranges below are included and disclosed herein, for example, the density of ULDPE may range from 0.855, 0.860, 0.870, 0.880, or 0.890 g / cm as a lower limit. 3 to 0.912, 0.910, 0.908, or 0.906 g / cm 3 It can be up to 0.855 to 0.912 g / cm 3 All individual values ​​and subranges are included and disclosed herein.

[0027] In embodiments in which the first outer layer and / or the second outer layer comprises ULDPE, the ULDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 50 g / 10 min. All individual values ​​and subranges from 0.1 g / 10 min to 50 g / 10 min are disclosed and included herein. For example, the ULDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 40 g / 10 min, 0.1 g / 10 min to 30 g / 10 min, 0.1 g / 10 min to 20 g / 10 min, 0.1 g / 10 min to 10 g / 10 min, or 0.1 g / 10 min to 5 g / 10 min.

[0028] Commercially available examples of ULDPE that may be used for the first and / or second outer layers include those available under the ATTANE™ name from The Dow Chemical Company, including, for example, ATTANE™ AT4607GC.

[0029] Multilayer film core The multilayer film includes a core. The core includes one or more core layers and includes 100% by weight of an ethylene-based polymer including an ethylene-propylene copolymer (described below). The core is disposed between a first outer layer and a second outer layer. The core includes a first core layer. In some embodiments, the multilayer film disclosed herein is a three-layer film including a first outer layer, a second outer layer, and a core, and the core includes a first core layer. In other embodiments, the multilayer film includes at least five layers. For example, in some embodiments, the core includes a first core layer, a second core layer, and a third core layer, where the first core layer is disposed between the first outer layer and the second core layer, the second core layer is disposed between the first core layer and the third core layer, and the third core layer is disposed between the second core layer and the second outer layer. In embodiments in which the core comprises a first core layer, a second core layer, and a third core layer, the multilayer film comprises at least five layers (e.g., a multilayer film having a structure of first outer layer / first core layer / second core layer / third core layer / second outer layer).

[0030] The core comprises a first core layer. In some embodiments, the first core layer comprises an ethylene-propylene copolymer comprising 60-90% by weight ethylene monomer and 10-40% by weight propylene comonomer. In some embodiments, the ethylene-propylene copolymer has the following properties: 0.890-0.920 g / cm 3a heat of fusion in the range of 90 to 150 J / g; a melt index (I2) of at least 0.5 g / 10 min or greater; a single peak in an improved comonomer composition distribution (ICCD) elution profile in the temperature range between 40 to 100° C.; and a molecular weight distribution (Mw / Mn) in the range of 1.5 to 5.0. In some embodiments, the ethylene-propylene copolymer is formed in the presence of a catalyst composition comprising a single-site metallocene catalyst.

[0031] In some embodiments, the ethylene-propylene copolymer of the first core layer comprises 60-95 wt% ethylene monomer and 5-40 wt% propylene comonomer, based on the total weight of the ethylene-propylene copolymer. All individual values ​​and subranges between 60 wt% and 95 wt% ethylene monomer and 5-40 wt% propylene comonomer are disclosed and included herein. For example, the ethylene-propylene copolymer can comprise 60-95 wt%, 60-90 wt%, 70-90 wt%, or 80-90 wt% ethylene monomer and 5-40 wt%, 10-40 wt%, 10-30 wt%, or 10-20 wt% propylene comonomer. The comonomer content can be measured using any suitable technique, such as techniques based on nuclear magnetic resonance (NMR) spectroscopy, for example, by 13C NMR analysis as described in U.S. Pat. No. 7,498,282, incorporated herein by reference.

[0032] In some embodiments, the ethylene-propylene copolymer has a viscosity of 0.890 to 0.920 g / cm 3 It has a density in the range of 0.890 to 0.920 g / cm 3 All individual values ​​and subranges are disclosed and included herein. For example, ethylene-propylene copolymers have a viscosity of 0.890 to 0.910 g / cm 3 , 0.890~0.905g / cm 3 , 0.895~0.905g / cm 3 , or 0.895 to 0.910 g / cm 3 The density may be in the range of 0.1 to 1.0 μm.

[0033] In some embodiments, the ethylene-propylene copolymer has a heat of fusion in the range of 90 to 150 J / g. All individual values ​​and subranges between 90 and 150 J / g are disclosed and included herein. For example, the ethylene-propylene copolymer can have a heat of fusion in the range of 90 to 150 J / g, 90 to 140 J / g, 90 to 130 J / g, 90 to 120 J / g, or 90 to 110 J / g, where the heat of fusion is measured according to the test methods described below.

[0034] In some embodiments, the ethylene-propylene copolymer has a melt index (I2) of at least 0.5 g / 10 min. All individual values ​​and subranges of at least 0.5 g / 10 min are disclosed and included herein. For example, the ethylene-propylene copolymer may have a melt index (I2) of at least 0.5 g / 10 min, at least 0.6 g / 10 min, at least 0.7 g / 10 min, at least 0.8 g / 10 min, at least 0.9 g / 10 min, or at least 1.0 g / 10 min, or may have a melt index (I2) in the range of 0.5 g / 10 min to 500 g / 10 min, 0.5 g / 10 min to 200 g / 10 min, 0.5 g / 10 min to 100 g / 10 min, 0.5 g / 10 min to 50 g / 10 min, 0.5 g / 10 min to 10 g / 10 min, or 0.5 g / 10 min to 8 g / 10 min.

[0035] In some embodiments, the ethylene-propylene copolymer has a single peak in the improved comonomer composition distribution (ICCD) elution profile in the temperature range between 40 and 100° C. The improved comonomer composition distribution (ICCD) profile of the ethylene-propylene copolymer can be obtained by the test method described below.

[0036] In some embodiments, the ethylene-propylene copolymer has a molecular weight distribution (Mw / Mn) in the range of 1.5 to 5.0. All individual values ​​and subranges between 1.5 and 5.0 are disclosed and included herein. For example, the ethylene-propylene copolymer can have a molecular weight distribution (Mw / Mn) in the range of 1.5 to 5.0, 1.6 to 5.0, 1.8 to 5.0, 2.0 to 5.0, 1.5 to 4.0, 1.6 to 4.0, 1.8 to 4.0, 2.0 to 4.0, 1.5 to 3.0, 1.8 to 3.0, 2.0 to 3.0, 1.5 to 2.5, 1.8 to 2.5, or 2.0 to 2.5. The molecular weight distribution (Mw / Mn) can be measured according to the GPC test method described below.

[0037] In some embodiments, the ethylene-propylene copolymer has a melt flow ratio (I 10 All individual values ​​and subranges from 5 to 14 are disclosed and included herein. For example, the ethylene / α-olefin copolymers may have a melt flow ratio (I 10 / I2).

[0038] In some embodiments, the first core layer comprises 80-100 wt% ethylene-propylene copolymer based on the total weight of the first core layer. All individual values ​​and subranges between 80-100 wt% are disclosed and included herein. For example, the first core layer can comprise 80-100 wt%, 80-95 wt%, 80-90 wt%, or 90-100 wt% ethylene-propylene copolymer based on the total weight of the first core layer.

[0039] In some embodiments, in addition to the ethylene-propylene copolymer, the first core layer can include 0-20 wt.%, or 5-20 wt.%, of an ethylene-based polymer, such as ULDPE, LLDPE, LDPE, MDPE, or HDPE, based on the total weight of the first core layer. For example, in some embodiments, the first core layer includes 5-20 wt.% LLDPE, based on the total weight of the first core layer.

[0040] In embodiments where the first core layer comprises LLDPE, the LLDPE has a viscosity of 0.930 g / cm 3 It may have a density of 0.930 g / cm 3 All individual values ​​and subranges below are included and disclosed herein, for example, the density of linear low density polyethylene is 0.870 g / cm3 as a lower limit. 3 ~ 0.928, 0.925, 0.920, or 0.915 g / cm 3 0.870 to 0.930 g / cm 3 All individual values ​​and subranges are included and disclosed herein.

[0041] In embodiments in which the first core layer comprises an LLDPE, the LLDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 50 g / 10 min. All individual values ​​and subranges from 0.1 g / 10 min to 50 g / 10 min are disclosed and included herein. For example, the LLDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 40 g / 10 min, 0.1 g / 10 min to 30 g / 10 min, 0.1 g / 10 min to 20 g / 10 min, 0.1 g / 10 min to 10 g / 10 min, or 0.1 g / 10 min to 5 g / 10 min.

[0042] In some embodiments, in addition to the first core layer, the core of the multilayer film further includes a second core layer and a third core layer, the second core layer being disposed between the first core layer and the third core layer, and the third core layer being disposed between the second core layer and the second outer layer (e.g., the multilayer film has a structure of first outer layer / first core layer / second core layer / third core layer / second outer layer).

[0043] In some embodiments, the second core layer and / or the third core layer have the same polymer composition as the first core layer. In other embodiments, the second core layer and / or the third core layer have a different polymer composition than the first core layer. For example, in some embodiments, the third core layer also comprises an ethylene-propylene copolymer. That is, in some embodiments, the third core layer comprises an ethylene-propylene copolymer comprising 60-90 wt% ethylene monomer and 10-40 wt% propylene comonomer, the ethylene-propylene copolymer having the following properties: density in the range of 0.890-0.920 g / cc; heat of fusion in the range of 90-150 J / g; melt index (I2) of at least 0.5 g / 10 min or more; a single peak in the improved comonomer composition distribution (ICCD) elution profile in the temperature range between 40-100° C.; and a molecular weight distribution Mw / Mn of 1.5-5.0. In such embodiments, the third core layer can have the same polymer composition as the first core layer, and the ethylene-propylene copolymer of the third core layer can have the same properties as the ethylene-propylene copolymer of the first core layer (discussed above).

[0044] In embodiments where the multilayer film includes a first core layer, a second core layer, and a third core layer, the second core layer can include an ethylene-based polymer, such as ULDPE, LLDPE, LDPE, MDPE, or HDPE. For example, in some embodiments, the second core layer includes ULDPE. In embodiments where the second core layer includes ULDPE, the ULDPE can have a viscosity of 0.912 g / cm 3 It may have a density of 0.912 g / cm 3 All individual values ​​and subranges below are included and disclosed herein, for example, the density of ULDPE may range from 0.865, 0.870, 0.880, or 0.890 g / cm as a lower limit. 3 from 0.912, 0.910, 0.908, or 0.906 g / cm 3 0.865 to 0.912 g / cm 3 All individual values ​​and subranges are included and disclosed herein.

[0045] In embodiments in which the second layer comprises ULDPE, the ULDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 50 g / 10 min. All individual values ​​and subranges from 0.1 g / 10 min to 50 g / 10 min are disclosed and included herein. For example, the ULDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 40 g / 10 min, 0.1 g / 10 min to 30 g / 10 min, 0.1 g / 10 min to 20 g / 10 min, 0.1 g / 10 min to 10 g / 10 min, or 0.1 g / 10 min to 5 g / 10 min.

[0046] Commercially available examples of ULDPE that may be used for the second core layer include those available under the ATTANE™ name from The Dow Chemical Company, including, for example, ATTANE™ AT4607GC.

[0047] In some embodiments, the second core layer comprises LLDPE. In embodiments where the second core layer comprises LLDPE, the LLDPE has a viscosity of 0.930 g / cm 3 It may have a density of 0.930 g / cm 3 All individual values ​​and subranges below are included and disclosed herein, for example, the density of linear low density polyethylene is 0.870 g / cm3 as a lower limit. 3 ~ 0.928, 0.925, 0.920, or 0.915 g / cm 3 0.870 to 0.930 g / cm 3 All individual values ​​and subranges are included and disclosed herein.

[0048] In embodiments in which the second core layer comprises an LLDPE, the LLDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 50 g / 10 min. All individual values ​​and subranges from 0.1 g / 10 min to 50 g / 10 min are disclosed and included herein. For example, the LLDPE can have a melt index (I2) in the range of 0.1 g / 10 min to 40 g / 10 min, 0.1 g / 10 min to 30 g / 10 min, 0.1 g / 10 min to 20 g / 10 min, 0.1 g / 10 min to 10 g / 10 min, or 0.1 g / 10 min to 5 g / 10 min.

[0049] Commercially available examples of LLDPE that may be used for the second core layer include those available under the ELITE™ name from The Dow Chemical Company, including, for example, ELITE™ 5230G.

[0050] In some embodiments, the first core layer and the third core layer each have a thickness that is 5-20% of the total thickness of the multilayer film. In some embodiments, the second core layer has a total thickness that is 20%-70% of the total thickness of the multilayer film. In some embodiments, the core of the multilayer film has a thickness that is 70-90% of the total thickness of the multilayer film.

[0051] Additives It should be understood that any of the foregoing layers can further include one or more additives known to those skilled in the art, such as, for example, antioxidants, UV stabilizers, heat stabilizers, slip agents, antiblock agents, antistatic agents, pigments or colorants, processing aids, crosslinking catalysts, flame retardants, fillers, and foaming agents, etc. For example, in some embodiments, the first outer layer and the second outer layer each include an antiblock agent.

[0052] Multilayer Film The multilayer films disclosed herein can be manufactured using techniques known to those skilled in the art based on the teachings herein. For example, the multilayer films can be produced by coextrusion. The formation of coextruded multilayer films is known in the art and is applicable to the present disclosure. Coextrusion systems for making multilayer films use at least two extruders that feed into a common die assembly. The number of extruders depends on the number of different materials or polymers that make up the coextruded film. For example, a five-layer coextrusion may require up to five extruders, but fewer extruders may be used if two or more layers are made of the same material or polymer.

[0053] The multilayer film of the present invention can have several desirable properties in various embodiments. Without being bound by any theory, the specific structure of the multilayer film, together with the inclusion of a specific ethylene-propylene copolymer in the core, can result in the multilayer film having high tear resistance properties. Similarly, in some embodiments, the multilayer film exhibits a transverse tear resistance of at least 500g (or at least 600g, or at least 700g, or at least 800g), or in the range of 500g to 1000g, 600g to 1000g, 700g to 1000g, or 800g to 1000g. The transverse tear resistance can also be expressed in grams per μm of thickness of the multilayer film. For example, in some embodiments, the multilayer film may exhibit a transverse tear resistance of at least 16.66 g / μm (or at least 20 g / μm, or at least 23.33 g / μm, or at least 26.66 g / μm), or in the range of 16.66 g / μm to 33.33 g / μm, 20 g / μm to 33.33 g / μm, 23.33 g / μm to 33.33 g / μm, or 26.66 g / μm to 33.33 g / μm. Transverse tear resistance may be measured according to ASTM D1922-09.

[0054] In some embodiments, the multilayer film has a thickness of from 6 to 150 microns, or alternatively from 6 to 100 microns, or alternatively from 6 to 50 microns.

[0055] In some embodiments, the multilayer films of the present invention comprise at least 90% by weight ethylene-based polymer, or at least 95% by weight ethylene-based polymer, or at least 99% by weight ethylene-based polymer, or at least 99.5% by weight ethylene-based polymer, or at least 99.9% by weight ethylene-based polymer, based on the total weight of the multilayer film. Because the multilayer films in some embodiments comprise at least 90% by weight ethylene-based polymer, they may be compatible with polyethylene recycle streams.

[0056] In some embodiments, the multilayer film is a machine direction oriented film. In some embodiments, the multilayer film is a cast stretch film. In further embodiments, the multilayer film is a stretch hood film.

[0057] Cast Stretch Film In one embodiment, the multilayer film of the present invention is a cast stretch film. Cast stretch films are high transparency films utilized to protect and consolidate manufactured articles or items for transportation and storage. It is highly desirable for cast stretch films to have high transverse tear strength to minimize catastrophic breakage during pallet wrapping. Cast stretch films can be differentiated from blown stretch films by the manufacturing method. The main differences between cast and blown films relate to the cooling method, film orientation, line speed, and gauge control. Cast films typically exhibit better optical properties and a very high degree of machine direction orientation compared to blown films. Cast stretch films can be manufactured using techniques known to those skilled in the art based on the teachings herein.

[0058] Goods The present invention also provides an article comprising any of the multilayer films of the present invention described herein. Examples of such articles may include wraps, packaging, flexible packaging, pouches, and sachets. The articles of the present invention can be formed from the multilayer films disclosed herein using techniques known to those skilled in the art in view of the teachings herein.

[0059] Test Method density Density is measured in grams / cm according to ASTM D792. 3 (g / cm 3 )

[0060] Melt index (I2 and I 10 ) The melt index (I2) is measured at 190°C and 2.16 kg according to ASTM D-1238. 10 ) is measured at 190°C and 10 kg according to ASTM D-1238. Melt index values ​​are reported in g / 10 min, which corresponds to grams dissolved per 10 minutes. The melt flow ratio is I 10 / I2.

[0061] DSC method - Heat of fusion Differential scanning calorimetry (DSC) is a common technique that can be used to study the melting and crystallization of semicrystalline polymers. DSC measurements in general and the application of DSC to the study of semicrystalline polymers are explained in standard textbooks (e.g., Thermal Characterization of Polymeric Materials, ed. by E A Turi, Academic Press, 1981).

[0062] The heat of fusion is determined using a DSC from TA Instruments, Inc. The test is performed with reference to ASTM standard D3428. Calibration is performed by preparing 2-3 mg of indium and placing it in a Tzero aluminum pan. The pan is then loaded into the DSC instrument and subjected to the following heating program cycle: 1) equilibrate the test chamber at 180°C, 2) hold the temperature at 180°C for 1 minute, 3) decrease the temperature to 130°C at 10°C / min, 4) hold the temperature at 130°C for 3 minutes, and 5) increase the temperature to 180°C at 10°C / min. Once complete, the last heating curve performed in step 5 is analyzed to determine the melting temperature of the indium sample. The DSC is considered to be functioning in accordance with the standard if the melting temperature is within 0.5°C tolerance of 156.6°C.

[0063] For sample testing, the polymer sample is first pressed into a thin film at a temperature of 190°C. Approximately 4-5 mg of sample is weighed and placed in the DSC pan. A lid is crimped onto the pan to ensure a sealed environment. The sample pan is placed into the DSC cell and equilibrated at 180°C. The sample is held at this temperature for 5 minutes. The sample is then cooled to -90°C at a rate of 10°C / min and held isothermal at that temperature for 5 minutes. The sample is subsequently heated to 150°C (to ensure complete melting) at a rate of 10°C / min, a step referred to as the second heating curve. The resulting enthalpy curve is analyzed for peak melting temperature, crystallization onset and peak crystallization temperatures, and heat of fusion (also known as heat of fusion) ΔHf. The heat of fusion (in joules / gram) is measured from the second heating curve by linear integration of the melting endotherm according to the baseline.

[0064] Improved Comonomer Composition Distribution (ICCD) An improved comonomer content analysis method (iCCD) was developed in 2015 (Cong and Parrott et al., WO 2017040127(A1)). iCCD tests were performed using a Crystallization Elution Fractionation (CEF) instrument (PolymerChar, Spain) equipped with an IR-5 detector (PolymerChar, Spain) and a two-angle light scattering detector model 2040 (Precision Detectors, now Agilent Technologies). A 5 cm or 10 cm (length) x 1 / 4 inch (inner diameter) guard column packed with 20-27 micron glass (MoSCi Corporation, USA) on stainless steel was placed immediately before the IR-5 detector in the detector oven. Ortho-dichlorobenzene (ODCB, 99% anhydrous grade or technical grade) was used. Silica gel 40 (particle size 0.2-0.5 mm, catalog number 10181-3) was obtained from EMD Chemicals (which could be used to dry the ODCB solvent earlier). The dried silica was packed into three empty HT-GPC columns to further purify the ODCB as the eluent. The CEF instrument was equipped with an autosampler with N2 purging capability. Before use, the ODCB was sparged with dry nitrogen (N2) and agitated for 1 h. Sample preparation was performed at 4 mg / mL (unless otherwise specified) using the autosampler at 160 °C for 1 h with shaking. The injection volume was 300 μL. The temperature profile of the iCCD was crystallization from 105 °C to 30 °C at 3 °C / min, thermal equilibration at 30 °C for 2 min (including setting the soluble fraction elution time to 2 min), and elution from 30 °C to 140 °C at 3 °C / min. The flow rate during crystallization was 0.0 mL / min. The flow rate during elution is 0.50 mL / min. Data are collected at 1 data point / sec.

[0065] The iCCD column was packed with gold-coated nickel particles (Bright 7GNM8-NiS, Nippon Chemical Industrial Co.) in a 15 cm (length) x ¼ inch (inner diameter) stainless steel tube. Column packing and conditioning was performed with a slurry method according to references (Cong, R.; Parrott, A.; Hollis, C.; Cheatham, M. International Publication WO 2017040127(A1)). The final pressure using TCB slurry packing was 150 bar.

[0066] Column temperature calibration was performed using the reference material linear homopolymer polyethylene in ODCB (comonomer content zero, melt index (I2) 1.0, polydispersity M w / M n Conventional gel permeation chromatography was performed using a mixture of 1.0 mg / mL elution of 100 mM NaCl (approximately 2.6 mg / mL) and eicosane (2 mg / mL). The iCCD temperature calibration consisted of four steps: (1) calculating the delay volume, defined as the temperature offset between the measured peak elution temperatures of eicosane minus 30.00°C; (2) subtracting the temperature offset of the elution temperature from the iCCD raw temperature data. Note that this temperature offset is a function of experimental conditions such as elution temperature, elution flow rate, etc.; (3) creating a linear calibration line converting elution temperatures over the range of 30.00°C to 140.00°C, such that a linear homopolymer polyethylene standard has a peak temperature at 101.0°C and eicosane has a peak temperature of 30.0°C; (4) linearly extrapolating elution temperatures below 30.0°C for soluble fractions measured isothermally at 30°C by using an elution heating rate of 3°C / min according to references (Cerk and Cong et al., U.S. Patent No. 9,688,795).

[0067] Comonomer content versus iCCD elution temperature was constructed using 12 reference materials (ethylene homopolymers and ethylene-octene random copolymers made with single-site metallocene catalysts, with ethylene equivalent weight average molecular weights ranging from 35,000 to 128,000). All of these reference materials were analyzed at 4 mg / mL with the same methodology as specified previously. The reported elution peak temperatures have an R of 0.978. 2 followed the plot of mole % of octene versus iCCD elution temperature.

[0068] JPEG2025503907000002.jpg61170

[0069] The molecular weights of the polymers and polymer fractions were determined directly from the LS detector (at a 90 degree angle) and the concentration detector (IR-5) according to the Rayleigh-Gans-Debys approximation (Striegel and Yau, "Modern Size Exclusion Liquid Chromatogram", Page 242 and Page 263) by assuming a form factor of 1 and all virial coefficients of zero. An integration window was set to integrate all chromatograms with elution temperatures ranging from 23.0 to 120 °C (temperature calibration specified above).

[0070] Calculating molecular weight (Mw) from the iCCD involves the following steps: (1) Measure the inter-detector offset. The offset is defined as the geometric volume offset between the LS detector relative to the concentration detector. It is calculated as the difference in elution volume (mL) of the polymer peak between the concentration detector and the LS chromatogram. This is converted to a temperature offset by using the elution heat rate and elution flow rate. A linear high density polyethylene (comonomer content zero, melt index (I2) of 1.0, polydispersity M w / M n(2) LS data points of the LS chromatogram are shifted to correct for inter-detector offset before integration. (3) The baseline-subtracted LS and concentration chromatograms are integrated over the entire elution temperature range of step (1). The same experimental conditions are used as for the regular iCCD method described above, except for the following parameters: crystallization from 140°C to 137°C at 10°C / min, thermal equilibration at 137°C for 1 min as soluble fraction elution time, soluble fraction (SF) time of 7 min, and elution from 137°C to 142°C at 3°C / min. The flow rate during crystallization is 0.0 mL / min. The flow rate during elution is 0.80 mL / min. The sample concentration is 1.0 mg / mL. (2) Each LS data point of the LS chromatogram is shifted to correct for inter-detector offset before integration. (3) The baseline-subtracted LS and concentration chromatograms are integrated for the entire elution temperature range of step (1). The MW detector constant is calculated using HDPE samples of known MW in the range of 100,000-140,000 MW and the area ratio of the LS to concentration integrated signals. (4) The Mw of the polymer was calculated by using the ratio of the integrated light scattering detector (at a 90 degree angle) to the concentration detector and using the MW detector constant.

[0071] Conventional GPC (Mw / Mn) The chromatography system consisted of a PolymerChar (Valencia, Spain) GPC-IR high temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) coupled to a Precision Detectors (now Agilent Technologies) 2-angle laser light scattering (LS) detector model 2040. For all light scattering measurements, a 15 degree angle is used for measurement purposes. The autosampler oven compartment was set at 160°C and the column compartment was set at 150°C. The columns used were four Agilent "Mixed A" 30 cm, 20 micron linear mixed bed columns. The chromatography solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume employed was 200 microliters and the flow rate was 1.0 milliliters / min.

[0072] Calibration of the GPC column set was performed with 21 narrow molecular weight distribution polystyrene standards with molecular weights ranging from 580 to 8,400,000, arranged in six "cocktail" mixtures with at least 10-fold spacing between individual molecular weights. Standards were purchased from Agilent Technologies. Polystyrene standards were prepared at 0.025 grams in 50 milliliters of solvent for molecular weights equal to or greater than 1,000,000, and at 0.05 grams in 50 milliliters of solvent for molecular weights less than 1,000,000. The polystyrene standards were dissolved at 80°C for 30 minutes with gentle agitation. The peak molecular weights of the polystyrene standards were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)): M ポリエチレン =A×(M ポリスチレン ) B (Formula 1) where M is the molecular weight, A has a value of 0.4315, and B is equal to 1.0.

[0073] A fifth order polynomial was used to fit each polyethylene equivalent calibration point. A small adjustment (approximately 0.415 to 0.44) was made to A to correct for column resolution and band broadening effects, such that the NIST standard NBS 1475 is obtained at 52,000 MW.

[0074] Total plate counts of the GPC column set were performed using Eicosane (prepared at 0.04 g in 50 milliliters of TCB and dissolved for 20 minutes with gentle agitation). Plate counts (Equation 2) and symmetry (Equation 3) were measured with a 200 microliter injection according to the following equations:

[0075]

number

[0076]

number

[0077] Samples were prepared in a semi-automated fashion using PolymerChar's "Instrument Control" software to target sample weights of 2 mg / ml and add solvent (containing 200 ppm BHT) via a PolymerChar high temperature autosampler to pre-nitrogen sparged capped vials with septa. Samples were dissolved at 160° C. for 2 hours under "slow" shaking.

[0078] Mn (GPC) , Mw (GPC) , and Mz (GPC) The calculations were based on GPC results using the internal IR5 detector (measurement channel) of a PolymerChar GPC-IR chromatograph according to Equations 4-6 using PolymerChar's GPCOne™ software, baseline-subtracted IR chromatograms at each equally spaced data collection point (i), and polyethylene equivalent molecular weights obtained from a narrow standard calibration curve for point (i) of Equation 1.

[0079]

number

[0080] To monitor deviations over time, a flow marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. This flow marker (FM) was used to linearly calibrate the pump flow rate (Flow (nominal)) of each sample by RV matching the respective decane peak in the sample (RV (FM sample)) with the decane peak in the narrow standard calibration (RV (FM calibrated)). Any change in time of the decane marker peak is then assumed to be related to a linear shift in flow rate (Flow (effective)) throughout the run. To facilitate the highest accuracy of the RV measurement of the flow marker peak, a least squares fitting routine is used to fit the peaks of the flow marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation is then used to solve for the true peak position. After calibrating the system based on the flow marker peak, the effective flow rate (relative to the narrow standard calibration) is calculated as per Equation 7. Processing of the flow marker peaks was performed via PolymerChar GPCOne™ software. The allowable flow correction is such that the effective flow is within ±2% of the nominal flow.

[0081] Flow (effective) = Flow (nominal) * (RV(FM calibrated) / RV(FM sample)) (Equation 7)

[0082] A systematic approach to determining multiple detector offsets was performed in a manner consistent with that published by Balke, Mourey, et. al. (Mourey and Balke, Chromatography Polym. Chpt 12, (1992)) (Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym. Chpt 13, (1992)) using PolymerChar GPCOne™ software to optimize triple detector log (MW and IV) results from broad homopolymer polyethylene standards (Mw / Mn>3) to narrow standard column calibration results from narrow standard calibration curves.

[0083] Absolute molecular weight data were obtained using PolymerChar's GPCOne™ software in a manner consistent with that published by Zimm (Zimm, BH, J. Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scattering from Polymer Solutions, Elsevier, Oxford, NY (1987)). The total injected concentration used in the molecular weight determination was obtained from the mass detector area and mass detector constant derived from a suitable linear polyethylene homopolymer or one of the polyethylene standards of known weight average molecular weight. The calculated molecular weight (using GPCOne™) was obtained using the light scattering constant and refractive index concentration coefficient, dn / dc, of 0.104, derived from one or more of the polyethylene standards described below. In general, the mass detector response (IR5) and light scattering constant (determined using GPCOne™) should be determined from a linear standard having a molecular weight greater than about 50,000 g / mol. (Abs) and Mz (Abs) is calculated according to the following Equations 8-9.

[0084]

number

[0085] IR5 GPC composition correction The IR5 detector ratio calibration was performed using a series of known short chain branching (SCB) frequencies (SCBs) ranging from homopolymer (0 SCB / 1000 total C) to approximately 50 SCB / 1000 total C (where total C = carbons in the backbone + carbons in the branches). 13The characterization was performed using at least ten ethylene-based polymer standards (polyethylene homopolymers and ethylene / octene copolymers) with molecular weights of 100,000 g / mol and 100,000 g / mol, as determined by C NMR techniques. Each standard had a weight average molecular weight determined by GPC-LALLS of 36,000 g / mol to 126,000 g / mol. Each standard had a molecular weight distribution (Mw / Mn) of 2.0 to 2.5, as determined by GPC. Examples of polymer properties of the copolymer standards are shown in Table A.

[0086] [Table 1]

[0087] The “IR5 area ratio” (or “IR5 area ratio”) of the “baseline-subtracted area response of the IR5 methyl channel sensor” to the “baseline-subtracted area response of the IR5 measurement channel sensor” メチルチャネル面積 / IR5 測定チャネル面積 ")" (Standard filter and filter wheel supplied by PolymerChar, Part Number IR5_FWM01 included as part of the GPC-IR instrument) was calculated for each of the "copolymer" standards. A linear fit of the weight percent comonomer frequency versus "IR5 area ratio" was constructed in the form of Equation 10 below. Weight percent comonomer = A0 + [A1 × (IR5 メチルチャネル面積 / IR5 測定チャネル面積 )](Equation 10)

[0088] If there is significant spectral overlap with the comonomer termination (methyl) due to the molecular weight determined in each chromatographic slice, an end-group correction of the comonomer wt% data can be made using knowledge of the termination mechanism.

[0089] Cross-direction (CD) tear resistance The tear resistance of the example multilayer films is measured in the cross direction (CD) according to ASTM D1922-09, which determines the average force to propagate a tear in the cross direction through a specified length of plastic film after the tear has been initiated.

[0090] Highlights Ultimate stretch, puncture, and film retention The ultimate elongation, puncture, and film retention tests are performed using a Highlight stretch film test stand available from Highlight Industries, Inc. (Wyoming, Michigan). The Highlight stretch film test stand offers specific tests such as ultimate elongation, puncture, and film retention tests. The tests are based on ASTM D4649-03. The machine operates under the principle of stretching due to speed difference between two rollers. There is a first roller with a hydraulic brake and a second roller that pulls at a constant speed. The speed can be set up to 110 m / min, but for the following tests, the line speed is 55 m / min. Between the two rollers that stretch the film, there is a load cell with a capacity of 200 kilograms. In addition, there are two 60 kilogram capacity load cells to measure the unwind and wind forces. It also utilizes a metal drum carrying a 2.5 kilogram capacity load cell with an attachable tip for performing abuse testing.

[0091] The ultimate elongation test is used to determine the elongation and force at break of a film.

[0092] The film retention test is used to determine the force decay in percentage over a 2 minute period after subjecting a film to 200% elongation and punching with a rounded tip. Failure is understood as film breakage or excessive force decay. The device is set to reach a desired stretch level and the film is threaded so that it surrounds a metal drum. Once a predetermined elongation level is reached, it stops and then the tip exits the slot in the drum and the retention force is measured over a certain amount of time, and the initial and final force data are reported as the final retention force.

[0093] The puncture test is used to determine the force of a stretch film when pierced by a cone-shaped end tip. Failure is taken as the film breaking. The device is set to reach the desired stretch level and the film is threaded as it encircles a metal drum. Once the pre-determined stretch level is reached, it stops and then the tip exits the slot in the drum, measuring the puncture force and delivering the puncture force data. EXAMPLES

[0094] The example multilayer films discussed below contained the following materials:

[0095] Synthesis of ethylene-propylene copolymer The resin being developed (referred to herein as "Poly.1") is prepared according to the following process and table.

[0096] All raw materials (monomers and comonomers) as well as process solvents (high purity narrow boiling range isoparaffinic solvent, Isopar-E) are purified with molecular sieves prior to introduction into the reaction environment. Hydrogen is supplied under pressure as a high purity grade and is not further purified. The monomer feed stream to the reactor is pressurized to a pressure above the reaction pressure by a mechanical compressor. Solvent and comonomer (if present) feeds are pressurized to above the reaction pressure via pumps. Individual catalyst components are manually batch diluted with purified solvent and pressurized to above the reaction pressure. All reaction feed streams are metered using mass flow meters and each is independently controlled by a computer automated valve control system. The reactor configuration is a single reactor operation as specified in Table B below.

[0097] The reactor is a continuous solution polymerization reactor consisting of a liquid-filled non-adiabatic isothermal circulating loop reactor or a heat-removing continuous stirred tank reactor (CSTR). Independent control of all fresh solvent, monomer, comonomer (if present), hydrogen, and catalyst component feeds is possible. The total additional feed streams to the reactor (solvent, monomer, comonomer, and hydrogen) are temperature controlled, typically at 15-50°C, to maintain a single liquid phase by passing the feed streams through heat exchangers. In the case of a CSTR, all fresh feed to the polymerization reactor is injected at the bottom of the reactor. In the case of a circulating loop reactor, all additional feed to the polymerization reactor is injected into the reactor at two locations, with approximately equal reactor volume between each injection location. The fresh feed is controlled with each injector receiving half the mass flow rate of the total fresh feed. Catalyst components are injected into the polymerization reactor through one or more injection nozzles to introduce the components into the center of the reactor flow. The catalyst component feed is computer controlled to maintain the monomer conversion of the reactor at a specific value. The cocatalyst components are fed to the main catalyst components based on a calculated specific molar ratio. Immediately after the injection point of each reactor feed, the feed stream is mixed with the contents of a circulating polymerization reactor with static mixing elements. In the case of a CSTR, the heat of reaction is partially removed by a cooling jacket. The temperature of the coolant side serves to maintain an isothermal reaction environment at a specific temperature. In the case of a circulating loop reactor, the contents are continuously circulated, at the temperature of the coolant side, which serves to maintain an isothermal reaction environment at a specific temperature, to a heat exchanger, which serves to remove most of the heat of reaction. Circulation around the reactor loop is provided by a pump.

[0098] The reactor effluent enters a zone where it is deactivated by addition and reaction with a suitable reagent (water). At the outlet of this same reactor, other additives are added for polymer stabilization (typical antioxidants suitable for stabilization during extrusion and fabrication, such as octadecyl 3,5-di-Tert-butyl-4-hydroxyhydrocinnamate, tetrakis(methylene(3,5-di-Tert-butyl-4-hydroxyhydrocinnamate))methane, and tris(2,4-di-Tert-butyl-phenyl)phosphite, and acid scavengers, such as calcium stearate, if necessary).

[0099] Following catalyst deactivation and additive addition, the reactor effluent enters a devolatilization system where polymer is removed from the non-polymer stream. The isolated polymer melt is pelletized and recovered. The non-polymer stream passes through various equipment that separates most of the ethylene removed from the system. Depending on the reactor setup, either none of the solvent and unreacted comonomer are recycled to the reactor after passing through a purification system, or most of the solvent and unreacted comonomer are recycled to the reactor after passing through a purification system. Small amounts of solvent and comonomer are purged from the process.

[0100] The reactor stream feed data flows used to produce the off-stream resin, corresponding to the values ​​in Table B, are illustrated diagrammatically in Figure 1. The data are displayed for a reactor setup without a solvent recycle system and to allow the reaction system to be treated as a once-through flow diagram. Table A below provides the catalyst components.

[0101] [Table 2]

[0102] [Table 3]

[0103] Other materials ELITE™ 5230G is a linear low density polyethylene (LLDPE) with a density of 0.916 g / cm 3 and a melt index (I2) of 4.0 g / 10 min and is commercially available from The Dow Chemical Company, Midland, Mich. ELITE™ 5230G is an ethylene-based polymer as that term is defined herein.

[0104] DOWLEX™ SC2108G has a viscosity of 0.935 g / cm 3and a melt index (I2) of 2.6 g / 10 min, and is commercially available from The Dow Chemical Company, Midland, Mich. DOWLEX™ SC2108G is an ethylene-based polymer, as that term is defined herein.

[0105] ATTANE™ 4607GC has a viscosity of 0.904 g / cm 3 and a melt index (I2) of 4.0 g / 10 min, and is an extremely low density polyethylene (ULDPE) commercially available from The Dow Chemical Company, Midland, Mich. ATTANE™ 4607GC is an ethylene-based polymer, as that term is defined herein.

[0106] VERSIFY™ 3401 has a viscosity of 0.865 g / cm 3 VERSIFY™ 3401 is a propylene elastomer having a density of 1000 ppm. VERSIFY™ 3401 is commercially available from The Dow Chemical Company, Midland, Mich. VERSIFY™ 3401 is not an ethylene-based polymer as that term is defined herein.

[0107] Poly.1 contains 14.1% by weight propylene comonomer and more than 85.9% by weight ethylene monomer and has a viscosity of 0.900 g / cm 3 It has a density of 1.0, a heat of fusion of 101.7 J / g, a melt index (I2) of 6.0 g / 10 min, a Mw / Mn of 2.16, and an I 10 / I2. As seen in Figure 2, Poly.1 has a single peak in the temperature range between 40-100°C in the improved comonomer composition distribution (ICCD) elution profile. Poly.1 is an ethylene-based polymer as that term is defined herein.

[0108] A 5 layer multilayer film is formed on a Dr Collin coextrusion cast film line using the following parameters: target film thickness: 30 μm, extruders: 5 extruders, layer configuration: A / B / C / B / D, layer ratio / thickness: 15 mm / 15 mm / 40 mm / 15 mm / 15 mm, flat die size: 300 mm, line speed: 14 m / min, throughput rate: 7 kg / h, melt temperatures (° C.) for extruders A, B, C, and D respectively: 220° C., 226° C., 214° C., and 229° C.

[0109] Five layer cast stretch films having a thickness of 30 microns were formed and are designated as inventive and comparative examples. Each example film has a structure of A / B / C / D / E, where A is the first outer layer, B is the first core layer, C is the second core layer, D is the third core layer, and E is the second outer layer. Table 2 reports the structure of the five layer multilayer film formed. For each example, the first outer layer and the second outer layer each have a thickness that is 15% of the total thickness of the multilayer film, the first core layer and the third core layer have a thickness that is 15% of the thickness of the film, and the second core layer has a thickness that is 40% of the thickness of the film.

[0110] [Table 4]

[0111] Cross direction (CD) tear resistance is measured for each of the comparative and inventive examples. The results are reported in Table 3 below. As can be seen from the results, the inventive examples show improved CD tear resistance over the comparative examples. The inventive examples are compatible with polyethylene recycle streams and contain 100 wt% ethylene-based polymer, whereas Comparative Example 2 is not.

[0112] [Table 5]

[0113] All documents cited herein, including any cross-referenced or related patents or applications, if any, and any patent applications or patents to which this application claims priority or the benefit thereof, are incorporated herein by reference in their entirety, unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein, or that it alone, or in any combination with any other reference, teaches, suggests, or discloses such invention. Furthermore, to the extent that a meaning or definition of any term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0114] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended in the appended claims to cover all such changes and modifications that are within the scope of this invention.

Claims

1. A multilayer film, 1. A refractory material comprising: a first outer layer; a second outer layer; and a core, the core comprising one or more core layers, the core being disposed between the first outer layer and the second outer layer, the core comprising 100 wt. % of an ethylene-based polymer, based on a total polymer weight of the core, the first core layer comprising an ethylene-propylene copolymer comprising 60 to 95 wt. % ethylene monomer and 5 to 40 wt. % propylene comonomer, the ethylene-propylene copolymer having the following properties: 0.890~0.920g / cm ３ and a density in the range of a heat of fusion in the range of 90 to 150 J / g; A melt index (I) of at least 0.5 g / 10 min ２ )and, a single peak in the improved comonomer composition distribution (ICCD) elution profile between the temperature range of 40-100°C; A film having a molecular weight distribution (Mw / Mn) of 1.5 to 5.

0.

2. The ethylene-propylene copolymer has a melt flow ratio (I １０ / I ２ 10. The film of claim 1 further characterized by having:

3. 10. The film of claim 1, wherein the ethylene-propylene copolymer is formed in the presence of a catalyst composition comprising a single-site metallocene catalyst.

4. 10. The film of claim 1, wherein the first outer layer and the second outer layer each independently comprise linear low density polyethylene (LLDPE).

5. 10. The film of claim 1, wherein the core further comprises a second core layer and a third core layer, the first core layer being disposed between the first outer layer and the second core layer, the second core layer being disposed between the first core layer and the third core layer, and the third core layer being disposed between the second core layer and the second outer layer.

6. the third core layer comprises an ethylene-propylene copolymer comprising 60 to 90 weight percent ethylene monomer and 10 to 40 weight percent propylene comonomer, the ethylene-propylene copolymer having the following properties: 0.890~0.920g / cm ３ and a density in the range of a heat of fusion in the range of 90 to 150 J / g; A melt index (I) of at least 0.5 g / 10 min. ２ )and, a single peak in the improved comonomer composition distribution (ICCD) elution profile in the temperature range between 40 and 100°C; The film of claim 5, having a molecular weight distribution (Mw / Mn) of 1.5 to 5.

0.

7. The film of claim 5, wherein the first core layer and the third core layer each have a thickness that is 5 to 20% of the total thickness of the multilayer film.

8. The film of claim 1 , wherein the film is a machine direction oriented film.

9. The film of claim 1 , wherein the film is a cast stretch film.

10. The multilayer film of any one of claims 1 to 9, wherein the film is a stretch food film.

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