Compositions including recycled ethylene-based polymers and multilayer films incorporating same

Abstract

Embodiments are directed to multilayer films comprising a recycled polyethylene having a density from 0.870 to 0.950 g / cm3 and a melt index (I2) of 0.5 to 10.0 g / 10 min as determined according to ASTM D1238 (2.16 kg 190 °C); a polyethylene having a density from 0.870 to 0.950 g / cm3 and a melt index (I2) of 0.5 to 10.0 g / 10 min; and 1 to 10 wt.% of a functionalized polyethylene compatibilizer having a density from 0.860 g / cm3 to 0.970 g / cm3 and a melt index (I2) at least 1.0 g / 10 min, wherein the functionalized polyethylene compatibilizer comprises: a copolymerized reaction product of ethylene monomer and ethylenically unsubstituted dicarboxylic acid or derivatives thereof; a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivatives thereof; or combinations thereof. The multilayer film comprises from 5 to 30 wt.% polypropylene. The multilayer films provide environmental sustainability while maintaining mechanical strength in the multilayer films.

Description

COMPOSITIONS INCLUDING RECYCLED ETHYLENE-BASED POLYMERS AND MULTILAYER FILMS INCORPORATING SAMECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 615,365 filed December 28, 2023, the contents of which are incorporated in their entirety herein.TECHNICAL FIELD

[0002] Embodiments disclosed herein generally relate to compositions comprising a recycled ethylene-based polymer, multilayer films comprising the compositions, and multilayer films suitable for use as stretch films for pallet wrapping.BACKGROUND

[0003] There is a growing demand for using recycled polyethylene resins due to an increased emphasis on environmental sustainability. However, the use of recycled resins may be limited due to challenges in maintaining the mechanical integrity. Multilayer films, including stretch films, are extensively used in the packaging industry for securing goods to pallets during transportation and storage to ensure their safe transportation throughout the logistics chain. Films made for pallet wrapping typically include Linear Low-Density Polyethylene (LLDPE) resins or similar materials to meet the demanding mechanical performance requirements such as flexibility, durability, tear resistance, ultimate stretch, and tear strength.

[0004] It is desirable to use recycled polyethylene materials in stretch films; however, recycled polyethylene can degrade the performance of the films due to the presence of cellulosic residue that causes the formation of gels. Gels are imperfections, which can cause early breakage of the film and reduce ultimate stretch. Accordingly, there is a continual need for recycled polyethylene compositions without sacrificing or significantly sacrificing the mechanical performance.BRIEF SUMMARY

[0005] Embodiments of the present disclosure meet this need by providing a composition comprising recycled polyethylene and functionalized polyethylene compatibilizer. Generally, the presence of the functionalized polyethylene compatibilizer can enable the use of increased quantities of the recycled polyethylene without significant degradation of the mechanical properties in articles such as multilayer films.

[0006] According to one or more embodiments, the multilayer film comprises a first outer layer, second outer layer, and a core comprising one or more core layers, wherein a first core layer comprises: a recycled polyethylene having a density from 0.870 to 0.950 g / cm3and a melt index (I2) of 0.5 to 10.0 g / 10 min as determined according to ASTM D1238 (2.16 kg 190 °C); a polyethylene having a density from 0.870 to 0.950 g / cm3and a melt index (I2) of 0.5 to 10.0 g / 10 min; and 1 to 10 wt.% of a functionalized polyethylene compatibilizer having a density from 0.860 g / cm3to 0.970 g / cm3and a melt index (I2) of at least 1.0 g / 10 min, wherein the functionalized polyethylene compatibilizer comprises: a copolymerized reaction product of ethylene monomer and ethylenically unsubstituted dicarboxylic acid or derivative thereof; a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof; or combinations thereof; wherein the multilayer film comprises from 5 to 30 wt.% polypropylene, based on the total weight of the multilayer film.

[0007] Additional features and advantages will be set forth in the detailed description, which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows and the claims.

[0008] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

[0010] FIG. 1 schematically depicts a cross-sectional view of a multilayer film, according to one or more embodiments described in this disclosure; and

[0011] FIG. 2 schematically depicts a cross-sectional view of a multilayer film, according to one or more embodiments described in this disclosure.

[0012] Reference will now be made in detail to various embodiments, some embodiments of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. For example, where two embodiments include the same component, like numerals will be used to describe like components (e.g. first outer layer 102 in FIG. 2 will correspond to first outer layer 102 in FIG. 1).DETAILED DESCRIPTION

[0013] Specific embodiments of the present application will now be described. The disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth in this disclosure. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art.

[0014] Definitions

[0015] "Multilayer film" refers to any structure having more than one layer. For example, the multilayer film may have three or more layers, such as 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 33, 55 or more layers.

[0016] “Polyethylene” or "ethylene-based polymer" shall mean polymers comprising greater than 50% by weight of units, which have been derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of polyethylene known in the art include Low Density Polyethylene (LDPE); Linear Low Density Polyethylene (LLDPE); Ultra Low Density Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single-site catalyzed Linear Low Density Polyethylene, including both linear and substantially linear low density resins (m-LLDPE); Medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE).

[0017] “Polypropylene” or "propylene-based polymer" shall mean polymers comprising greater than 50% by weight of units derived from propylene monomer. This includes polypropylene homopolymers or copolymers (meaning units derived from comonomer, such as ethylene). Common forms of polypropylene known in the art include homopolymerpolypropylene (hPP), random copolymer polypropylene (rcPP), impact copolymer polypropylene (hPP + at least one elastomeric impact modifier) (ICPP) or high impact polypropylene (HIPP), high melt strength polypropylene (HMS-PP), isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), and combinations thereof.

[0018] The term “ULDPE” is defined as a polyethylene-based copolymer having a density in the range of 0.895 to 0.915 grams per cubic centimeter (g / cc).

[0019] The term “LDPE” may also be referred to as “high pressure ethylene polymer” or “highly branched polyethylene” and is defined to mean that the polymer is partly or entirely homopolymerized or copolymerized in autoclave or tubular reactors at pressures above 14,500 psi (100 MPa) with the use of free-radical initiators, such as peroxides (see for example U.S. Pat. No. 4,599,392, incorporated herein by reference).

[0020] The term “LLDPE”, includes resins made using the traditional Ziegler-Natta catalyst systems as well as single-site catalysts such as metallocene catalysts (sometimes referred to as “m-LLDPE”). LLDPEs contain less long chain branching than LDPEs and include the substantially linear ethylene polymers, which are further, defined in U.S. Pat. No. 5,272,236, U.S. Pat. No. 5,278,272, U.S. Pat. No. 5,582,923 and U.S. Pat. No. 5,733,155; the homogeneously branched linear ethylene polymer compositions such as those in U.S. Pat. No. 3,645,992; the heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Pat. No. 4,076,698; and / or blends thereof (such as those disclosed in U.S. Pat. No. 3,914,342 or U.S. Pat. No. 5,854,045). The LLDPE can 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, including, but not limited to, gas and solution phase reactors.

[0021] The term “HDPE” generally refers to polyethylenes having densities greater than about 0.935 g / cc and up to about 0.980 g / cc, which are generally prepared with Ziegler-Natta catalysts, chrome catalysts or single-site catalysts including, but not limited to, substituted mono- or bis-cyclopentadienyl catalysts (typically referred to as metallocene), constrained geometry catalysts, phosphinimine catalysts & polyvalent aryloxy ether catalysts (typically referred to as bisphenyl phenoxy).

[0022] "Polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The term polymer thus embraces the termhomopolymer (employed to refer to polymers prepared from only one type of monomer, with the understanding that trace amounts of impurities can be incorporated into the polymer structure), and the term copolymer or interpolymer. Trace amounts of impurities (for example, catalyst residues) may be incorporated into and / or within the polymer. A polymer may be a single polymer or a polymer blend.

[0023] As used herein, the term “copolymer” means a polymer formed by the polymerization reaction of at least two structurally different monomers. The term “copolymer” is inclusive of terpolymers. For example, ethylene copolymers, such as ethylene-propylene copolymers, include at least two structurally different monomers (e.g., ethylene-propylene copolymer includes copolymerized units of at least ethylene monomer and propylene monomer) and can optionally include additional monomers or functional materials or modifiers, such as acid, acrylate, or anhydride functional groups. Put another way, the copolymers described herein comprise at least two structurally different monomers, and although the copolymers may consist of only two structurally different monomers, they do not necessarily consist of only two structurally different monomers and may include additional monomers or functional materials or modifiers.

[0024] The term “defect” refers to a visible defect in the bulk polymer or film. Defects may arise from foreign contamination or degraded polymer. When defects are present, they reduce transparency in the film and ESTL ultimate stretch.

[0025] The term “pre-consumer recycled polyethylene” and refer to polymers, including blends of polyethylene polymers, recovered from pre-consumer material, as defined by ISO- 14021. The generic term pre-consumer recycled polyethylene thus includes blends of polyethylene and other polymers recovered from materials diverted from the waste stream during a manufacturing process. The generic term pre-consumer recycled polyethylene excludes the reutilization of polyethylene materials, such as rework, regrind, or scrap, generated in a process and capable of being reclaimed within the same process that generated it. In some instances, pre-consumer recycled polyethylene may include post-industrial recycled polyethylene.

[0026] The term “post-consumer recycled” (or “PCR”) polyethylene, as used herein, refers to a polyethylene material, such as the PCR HDPE, that includes materials previously used in a consumer or industry application i.e., pre-consumer recycled polyethylene and post-industrial recycled HDPE. PCR polyethylene is typically collected from recycling programs and recycling plants. The PCR polyethylene may include one or more contaminants. The contaminants may be the result of the polyethylene material’s use prior to being repurposed for reuse. For example, contaminants may include paper, ink, food residue, or other recycled materials in addition to the polymer, which may result from the recycling process. PCR polyethylene is distinct from virgin polyethylene. A virgin polyethylene does not include materials previously used in a consumer or industry application, whereas the PCR polyethylene does include them. Virgin polyethylene material has not undergone, or otherwise has not been subject to, a heat process or a molding process, after the initial polymer manufacturing process. The physical, chemical, and flow properties of PCR polyethylene polymers differ when compared to virgin polyethylene, which in turn can present challenges to incorporating PCR polyethylene into blends for commercial use.

[0027] It is contemplated that the PCR polyethylene includes various polyethylene compositions. PCR polyethylene may be sourced from HDPE packaging such as bottles (milk jugs, juice containers), LDPE / LLDPE packaging such as films. PCR polyethylene also includes residue from its original use, residue such as paper, adhesive, ink, nylon, ethylene vinyl alcohol (EVOH), polyethylene terephthalate (PET), and other odor-causing agents. Sources of PCR polyethylene can include, for example, bottle caps and closures, milk, water or orange juice containers, detergent bottles, office automation equipment (printers, computers, copiers, etc.), white goods (refrigerators, washing machines, etc.), consumer electronics (televisions, video cassette recorders, stereos, etc.), automotive shredder residue (the mixed materials remaining after most of the metals have been sorted from shredded automobiles and other metal-rich products “shredded” by metal recyclers), packaging waste, household waste, rotomolded parts (kayaks / coolers), building waste and industrial molding and extrusion scrap.

[0028] In embodiments, the polyethylene of the PCR polyethylene comprises low density polyethylene, linear low density polyethylene, or a combination thereof. In embodiments, the PCR polyethylene further comprises residue from its original use, such as paper, adhesive, ink, nylon, ethylene vinyl alcohol (EVOH), polyamide (PA), polyethylene terephthalate (PET), and other organic or inorganic material. Examples of PCR polymers include KWR101-150 and KWR-102 commercially available from KW Plastics, and AVANGARDTMNATURA PCR-LDPCR-100 (“AVANGARD™ 100”) and AVANGARD™ NATURA PCR-LDPCR-150 (“AVANGARD™ 150”) (PCR polymer commercially available from Avangard Innovative LP, Houston, Texas).

[0029] “Recycled polymer” or “recycled polyethylene” encompasses embraces both pre- consumer recycled polymer and post-consumer recycled polymer. Recycled polymers are defined in ISO 14021 7.8.1.1.

[0030] "wt.%" means weight percentage.

[0031] “g / 10 min” means grams per ten minutes.

[0032] As used herein, the term “core layer” refers to a non-skin or non-outer layer of a multilayer film. A core layer is an internal layer, i.e., a layer positioned between two outer layers, of a multilayer film. In one embodiment, a core layer is the non-outer layer of a three- layer film that comprises a first outer layer and a second outer layer. The totality of core layers in the multilayer film of this invention, i.e., one or a plurality, constitute the “core” of the film.

[0033] The terms “comprising,” “including,” “having,” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, “consisting essentially of” excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term “consisting of” excludes any component, step or procedure not specifically delineated or listed.

[0034] Embodiments of the present disclosure are directed to a composition comprising a recycled polyethylene having a density from 0.870 to 0.950 g / cm3and a melt index (I2) of 0.5 to 10.0 g / 10 min as determined according to ASTM D1238 (2.16 kg 190 °C); a polyethylene having a density from 0.870 to 0.950 g / cm3and a melt index (I2) of 0.5 to 10.0 g / 10 min; and 1 to 10 wt.% of a functionalized polyethylene compatibilizer having a density from 0.860 g / cm3to 0.970 g / cm3and a melt index (I2) of at least 1.0 g / 10 min, wherein the functionalized polyethylene compatibilizer comprises: a copolymerized reaction product of ethylene monomer and ethylenically unsubstituted dicarboxylic acid or derivative thereof apolyethylene grafted with ethylenically unsubstituted dicarboxylic acid; or derivative thereof combinations thereof.

[0035] Functionalized Polyethylene Compatibilizer

[0036] The ethylenically unsubstituted dicarboxylic acid or derivative thereof may be selected from the group consisting of maleic anhydride, itaconic anhydride, maleic acid diesters, fumaric diesters, maleic acid monoesters, fumaric acid monoesters, esters of C1to C4alcohols, maleic acid, itaconic acid, fumaric acid, or mixtures thereof. In one embodiment, the ethylenically unsubstituted dicarboxylic acid or derivative thereof comprises maleic anhydride.

[0037] In grafted polyethylene embodiments, the polyethylene may be a hompolymer or a copolymer wherein the ethylene may copolymerize with C3to C14a-olefin comonomer. In specific embodiments, the C3to C14a-olefin comonomer may be propylene, butene, hexene, or octene. In another embodiment, the polyethylene may comprise the polymerized reaction product of ethylene monomer, at least one C3-C14alpha-olefin comonomer, and at least one additional comonomer selected from alkyl acrylate, monocarboxylic acid, or combinations thereof. In yet another embodiment, the polyethylene may comprise the polymerized reaction product of ethylene monomer and at least one additional comonomer selected from alkyl acrylate, monocarboxylic acid, or combinations thereof. The additional comonomer may include one or more of vinyl acetate, acrylic acid, methacrylic acid, and alkyl acrylate (e.g., methyl acrylate, ethyl acrylate and butyl acrylate).

[0038] Various grafting amounts of the ethylenically unsubstituted dicarboxylic acid or derivative thereof are contemplated, for example, from 0.1 to 5.0 wt.% based on the total weight of the functionalized polyethylene compatibilizer. In further embodiments, the grafting level may be from 0.5 to 3.0 wt.%, or from 0.75 to 1.5 wt.%.

[0039] In other embodiments wherein the functionalized polyethylene compatibilizer comprises the copolymerized reaction product of ethylene monomer and ethylenically unsubstituted dicarboxylic acid or derivative thereof, the copolymer may optionally include at least one additional comonomer selected from alkyl acrylate, monocarboxylic acid, or combinations thereof. Like the grafted embodiment, the additional comonomer may include one or more of vinyl acetate, acrylic acid, methacrylic acid, and alkyl acrylate (e.g., methyl acrylate, ethyl acrylate and butyl acrylate).

[0040] In these ethylene / ethylenically unsubstituted dicarboxylic acid copolymer embodiments, the ethylenically unsubstituted dicarboxylic acid or derivative thereof may be incorporated into the polymer chain at an amount of 0.1 to 20.0 wt.% based on the total weight of the functionalized polyethylene compatibilizer. In further embodiments, the incorporation level may be from 0.5 to 10.0 wt.%, or from 0.75 to 5.0 wt.%.

[0041] As stated above, the functionalized polyethylene compatibilizer may have a density from 0.860 g / cm3 to 0.970 g / cm3 and a melt index (I2) of at least 1.0 g / 10 min. In some embodiments, the functionalized polyethylene compatibilizer may have a higher melt index. For example, the functionalized polyethylene compatibilizer may have a density from 0.860 to 0.900 g / cm3and a melt index (I2) from 500.0 to 1000.0 g / 10 min. In further embodiments, the density may be from 0.860 to 0.890 g / cm3, or from 0.865 to 0.875 g / cm3, whereas the melt index (I2) may be from 550.0 to 800.0 g / 10 min, or from 600.0 to 700.0 g / 10 min. Without being limited by theory, the higher melt index functionalized polyethylene compatibilizer can lower the viscosity of a polymer blend in addition to compatibilizing polar and nonpolar polymers. One commercial example of a higher melt index functionalized polyethylene compatibilizer is RETAIN™ 3000 from The Dow Chemical Company, Midland, MI. In other embodiments, the functionalized polyethylene compatibilizer may have a lower melt index. For example, the functionalized polyethylene compatibilizer may be from 0.900 to 0.925 g / cm3, and 0.910 to 0.920 g / cm3, whereas the melt index (I2) is from 1.0 to 10.0 g / 10 min, or from 2.0 to 5.0 g / 10 min. One commercial example is RETAIN™ 2000 from The Dow Chemical Company, Midland, MI.

[0042] Polyethylene

[0043] The polyethylene may have a density from 0.870 to 0.950 g / cm3, from 0.900 to 0.925 g / cm3, or from 0.910 to 0.920 g / cm3. The polyethylene may have a melt index (I2) from 0.5 to 10.0 g / 10 min, from 1.0 to 5.0 g / 10 min, or from 3.0 to 5.0 g / 10 min. Suitable polyethylene resins for use in the core layer 104 may include ELITE™ 5230 GC, an ethylene-octene copolymer, available from The Dow Chemical Company, Midland, MI.

[0044] Recycled polyethylene

[0045] The recycled polyethylene may have a density from 0.870 to 0.950 g / cm3, from 0.900 to 0.925 g / cm3, or from 0.910 to 0.920 g / cm3. The recycled polyethylene may have a melt index (I2) from 0.5 to 10.0 g / 10 min, from 1.0 to 5.0 g / 10 min, or from 1.0 to 3.0 g / 10 min.Various compositions are considered suitable for the recycled polyethylene, for example, LLDPE.

[0046] The recycled polyethylene may be added to the composition in various forms. For example, the recycled polyethylene may be delivered as a singular recycled component for blending with the polyethylene and functionalized polyethylene compatibilizer. Alternatively, the recycled polyethylene may be delivered in a blend of recycled polyethylene and polyethylene components which is then blended with the polyethylene and functionalized polyethylene compatibilizer

[0047] Various amounts are considered suitable for the components of the composition. For example, the composition may include 10 to 89 wt.%, from 20 to 80 wt.%, or from 30 to 70 wt.% of the recycled polyethylene. The composition may include 10 to 89 wt.%, from 20 to 80 wt.%, or from 30 to 70 wt.% of the polyethylene. In one embodiment, the composition may include more polyethylene than recycled polyethylene. In further embodiments, the composition may comprise 1 to 10 wt.%, from 1 to 5 wt.%, or from 2 to 4 wt.% of the functionalized polyethylene compatibilizer.

[0048] The composition may be incorporated in a multilayer film. Referring to the multilayer film 100 embodiment of FIG. 1, the multilayer film 100 comprises a first outer layer 102, a second outer layer 106, and a core comprising one or more core layers. A first core layer 108 comprises the compositions as described above. Additionally, the multilayer film 100 includes from 5 to 30 wt.% polypropylene, based on the total weight of the multilayer film 100.

[0049] In some embodiments, as depicted in FIGS. 1 and 2, the first outer layer 102 and the second outer layer 106 may be the outermost layers of the multilayer film 100; however, it is contemplated that there may be other layers exterior to the first outer layer 102 and the second outer layer 106.

[0050] Polypropylene

[0051] As stated above, the multilayer film 100 includes from 5 to 30 wt.% polypropylene, based on the total weight of the multilayer film 100. In further embodiments, the multilayer film 100 includes from 10 to 25 wt.% polypropylene.

[0052] Referring to FIG. 1, the first outer layer 102, the second outer layer 106, or both may comprise polypropylene. In embodiments, the first outer layer 102, the second outer layer 106, or both may comprise 10 to 100 wt.% polypropylene.

[0053] The polypropylene may have a melt flow rate (MFR) of 0.5 to 20 g / 10 mins, from 1 to 10 g / 10 mins, from 2 to 8 g / 10 mins, or from 6 to 8 g / 10 mins as measured according measured in accordance with ASTM D-1238 (230 °C / 2.16 kg).

[0054] Various commercial polypropylene compositions are considered suitable, for example, polypropylenes from Braskem, VERSIFY™ from The Dow Chemical Company, Midland, MI and Vistamaxx™ from Exxon-Mobil.

[0055] Referring to FIG. 2, the core layer includes the first core layer 108, a second core layer 110 and a third core layer 112 disposed on opposite sides of the first core layer 108. In one embodiment, the first core layer 108 may comprise the above described composition (i.e., recycled polyethylene, polyethylene, and functionalized polyethylene compatibilizer), whereas the second core layer 110, the third core layer 112, or both may comprise polypropylene. In other embodiments, the second core layer 110, the third core layer 112 or both, may comprise 10 to 100 wt.% polypropylene. Additionally, the first core layer 108 may include polypropylene. In one embodiment, all layers of the multilayer film 200 may include polypropylene. Without being limited by theory, the combination of the compositions described above and the polypropylene provide increased mechanical performance (e.g., ESTL Ultimate Stretch, ESTL Tear, and On Pallet Tear) for multilayer films, for example, stretch films.

[0056] In further embodiments, the second core layer 110 and the third core layer 112 may also comprise polyethylene, recycled polyethylene, and functionalized polyethylene compatibilizer. In one or more embodiments, all layers of the multilayer film 200 comprise functionalized polyethylene compatibilizer.

[0057] First Outer Layer

[0058] Referring again to FIG. 2, the first outer layer 102 may comprise a polyethylene, such as LLDPE. In embodiments, the first outer layer 102 may comprise at least 50 wt. %, such as at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, or even at least 99 wt. % of LLDPE.

[0059] The first outer layer 102 may serve as a release layer. A release layer, for example, may have non-cling characteristics or may exhibit lower cling characteristics than a cling layer. The first outer layer 102 may comprise any material suitable for use as a release layer.

[0060] The polyethylene of the first outer layer 102 may have a melt index (I2) of from 1.0 grams per ten minutes (g / 10 min.) to 10.0 g / 10 min. In embodiments, the first outer layer 102 may have a melt index (I2) of from 1.0 g / 10 min to 6.0 g / 10 min, from 1.5 g / 10 min to 4.0 g / 10 min, from 2.0 g / 10 min to 3.0 g / 10 min, from 2.0 g / 10 min to 7.0 g / 10 min, from 3.0 g / 10 min to 6.0 g / 10 min, or any subset thereof. In embodiments, the multilayer film 100 may be a cast stretch film and the first core layer 102 may have a melt index (I2) of from 2.0 g / 10 min to 6.0 g / 10 min. In embodiments, the multilayer film 100 may be a blown film and the first outer layer 102 may have a melt index (I2) of from 0.5 g / 10 min to 3.0 g / 10 min.

[0061] The polyethylene of the first outer layer 102 may have a density of from 0.900 g / cm3to 0.935 g / cm3. In embodiments, the first outer layer 102 may have a density of from 0.910 g / cm3to 0.930 g / cm3, from 0.916 g / cm3to 0.925 g / cm3, from 0.916 g / cm3to 0.920 g / cm3, from 0.925 g / cm3to 0.935 g / cm3, from 0.920 g / cm3to 0.930 g / cm3, or any subset thereof.

[0062] It is further contemplated that the first outer layer 102 may also comprise recycled polyethylene, functionalized polyethylene compatibilizer, or combinations thereof.

[0063] Second Outer Layer

[0064] Referring again to FIG. 1, the second outer layer 106 may comprise polyethylene, such as a LLDPE. In embodiments, the second outer layer 106 may comprise at least 50 wt. %, such as at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, or even at least 99 wt. % of polyethylene.

[0065] The second outer layer 106 may be a cling layer. Cling layers, for example, may enable the multilayer film 100 to cling to itself when the film is wrapped on a load. The second outer layer 106 may comprise any material suitable for use as a cling layer.

[0066] In embodiments, the second outer layer 106 may comprise a polyethylene base resin and a cling resin. In some embodiments, the second outer layer 106 may comprise at least 50 wt.%, at least 70 wt. %, or at least 80 wt. %, of the polyethylene base resin, based on the total polymer weight of the second outer layer 106.

[0067] In one or more embodiments, the cling resin may comprise polyethylene or polypropylene. The cling resin may have a density of from 0.870 g / cm3to 0.920 g / cm3, from 0.890 g / cm3to 0.910 g / cm3, or from 0.900 g / cm3to 0.910 g / cm3. The cling resin may a melt index (I2) from 1.0 to 10.0 g / 10 min, from 1 g / 10 min to 5 g / 10 min, or from 1 g / 10 min to 2 g / 10 min. Suitable cling resins may include ATTA NE™ and VERSIFY™ from The Dow Chemical Company, Midland, MI.

[0068] The polyethylene base resin may have a density from 0.870 to 0.950 g / cm3, from 0.900 to 0.925 g / cm3, or from 0.910 to 0.920 g / cm3. The polyethylene base resin may have a melt index (I2) from 0.5 to 10.0 g / 10 min, from 1.0 to 5.0 g / 10 min, or from 3.0 to 5.0 g / 10 min.

[0069] It is further contemplated in other embodiments that the second outer layer 106 may also comprise recycled polyethylene, functionalized polyethylene compatibilizer, or combinations thereof.

[0070] Articles

[0071] Various thicknesses are consider suitable for the multilayer films of the present disclosure. The multilayer film 100 may have a thickness of 8 to 70 μm.

[0072] The multilayer film may be constructed from two or more film layers by any film lamination and / or coextrusion technique and using any blown or cast film extrusion and lamination equipment known in the art. For example, multilayer film structures may be prepared using coextrusion techniques, such as, by cast coextrusion techniques.

[0073] These multilayer films may be included in a variety of articles. Examples of such articles can include stretch films, wraps, packages, flexible packages, pouches, and sachets. The multilayer film may also include stretch films having an ESTL ultimate stretch greater than 250%.TEST METHODS

[0074] Density

[0075] Density is measured in accordance with ASTM D792, and expressed in grams / cm3(g / cm3).

[0076] Melt Index ( I2)

[0077] The Melt Index for samples other than RETAIN 3000 are measured in accordance with ASTM D-1238, condition 190 °C / 2.16 kg. For polymers with a melt index greater than or equal to 200 g / 10 min, melt index is calculated from Brookfield viscosity as described in U.S. Patents 6,335,410; 6,054,544; 6,723,810 using the following equation: (Eqn.l)where I2is the calculated melt index in g / lOmin at 190 °C / 2.16 kg, η is the melt viscosity in centipoise measured in accordance with ASTM D 3236 (177°C., 350°F.), using a Brookfield Digital Viscometer (Model DV-III, version 3).

[0078] Melt Flow Rate (MFR)

[0079] The Melt Flow Rate for polypropylene samples was measured in accordance with ASTM D-1238 (230 °C / 2.16 kg).

[0080] Engineering Solutions for Transport and Logistics (ESTL) Ultimate stretch

[0081] ESTL Ultimate Stretch is determined on an ESTL FPT-750 Film Performance Tester, which incrementally stretches the film over rollers until it breaks. The testing is conducted at multiple different speeds and is intended to replicate the mechanisms of pallet wrappers. This test reports the force in the unwind section, forces on the wind drum, forces required to stretch the film, peel-off angle, peel-off force and unwind noise.

[0082] ESTL Tear propagation

[0083] This test was executed on ESTL FPT-750 Film Performance Tester which. The film is stretched to a pre-stretch level of 250%. Next, the film is clamped with a frame and counter frame, so a sharp blade can travel with a fixed pre-defined speed until it reaches the film. After the incision is made, the clamp is opened and the forces in the film are monitored. If the tear does not propagate, the wind drum will start to slowly pull until the film completely breaks.

[0084] On Pallet Puncture - Type B Load (OPP-B)

[0085] If unitized pallet is not uniform in shape with limited irregularities, it is defined as Type “B-Load”. This test uses a Bruceton staircase method to determine the maximum force to load at which the film can be passed over a test probe for three overlapping wraps with no failures. The test probe is inserted into the test stand at the desired protrusion distance. All films were tested by 2 inch x 2 inch blunt metal probe extending 6 inches out. The film ispositioned such that the test probe is aligned with the center of the film. The film is attached to the test stand and the wrapper started. Once the wrapper reaches 250% pre-stretch, the film is allowed to pass over the probe for a maximum of three wraps. The film is wrapped three times starting with post stretch film tension / force to load (F2) of 7 lbs. If the film is not punctured by the probe, the test is repeated at an increased F2 force at increments of 0.5 lbs. until failure. Any breakage of the film during any of the wrap is considered a failure at that force to load setting. Once the F2 force reaches a point where failures start to happen the test is repeated for 6 times at one force setting. If the film passes 4 of the 6 tests, the film F2 force is increased. If the film fails 4 of the 6 tests, then the test is stopped and this is considered the failure point of the film. Depending on the performance of the film at the load setting (z. e. , passed or failed), the force to load is increased / decreased and the test is repeated at the new load setting. This test continues until the maximum force at which failure is greater than 50% is found. The highest passing F2 force is reported as On Pallet Puncture (OPP) value. Standard variation for this test is observed to be + / - 1 lb. Under these testing conditions, the machine maxes out at 18 Ib-f. It should be understood that Type B Load Test is commonly used in pallet packing that a person of ordinary skill in the art would recognize its meaning as used herein. Table C below provides the equipment and settings used in this method.Table C

[0086] On Pallet Tear (OPT)

[0087] This test uses a Bruceton staircase method to determine the maximum force to load at which the film can be passed over a test probe fixed with a blade to initiate a puncture. The test probe is inserted into the test stand at the desired protrusion distance. The film is positioned such that the test probe is aligned with the center of the film. The film is attached to the test stand and the wrapper started. Once the wrapper reaches 250% pre-stretch, the film is allowed to pass over the probe, for this test a single layer of film is tested. The film tension(F2 force) is increased from an initial low value of ~7 lbs. in increments of 0.5 lbs. until the film tears completely across the cross direction (CD) or transverse direction (TD). An on- pallet tear value is recorded as the highest F2 force that results in the initial puncture not propagating through the entire width of the film causing its failure. Table D provides the equipment and settings used in this method.Table D

[0088] Machinability

[0089] Machinability was determined on a table stretch wrapper (Synergy 4 from Highlight Industries) by applying the film on a type-B load by wrapping with a pattern of 4 bottom wraps, 6 top wraps, moving down and finishing with 4 bottom wraps for a total of 27 revolutions. The test starts with a pre-stretch ratio of 250% (Fl) and no secondary stretch (F2 stretch) and incrementally increases the secondary force for each new wrap until the film breaks.EXAMPLES

[0090] The following examples are presented to further illustrate the present invention in detail but are not to be construed as limiting the scope of the claims. Unless otherwise indicated, all parts and percentages are by weight.

[0091] Materials

[0092] ELITE™ 5230G (also referred to herein as “5230G”) is a linear low-density polyethylene with an octene comonomer, having a density of 0.916 g / cm3and melt index (I2) of 4.0 g / 10 min. ELITE™ 5230G is commercially available from The Dow Chemical Company., (Midland, MI). ELITE™ 5230G is an ethylene-based polymer as that term is defined herein.

[0093] AVANGARD™ NATURA PCR-LDPCR- 100 (also referred to herein as “AV 100”), a PCR commercially available from Avangard Innovative LP, Houston, Texas (hereinafter “PCR”), is a post-consumer recycled ethylene-based polymer with a melt index (I2) of 2 dg / min and a density of 0.914 g / cc.

[0094] RETAIN™ 2000 (also referred to herein as “R2000”) is a maleic anhydride (g-MAH) functionalized ethylene / a-olefin copolymer having a density of 0.912 g / cm3, and melt index (I2) of 3.0 g / 10 min. RETAIN™ 2000 is commercially available functionalized polyethylene compatibilizer from The Dow Chemical Company., (Midland, MI).

[0095] ATTANE™ 4404G (also referred to herein as “4404G”) is an ultra low density polyethylene with a density of 0.904 g / cm3and a melt index (I2) of 4.0 g / 10 min. ATTANE™ 4404G is commercially available from The Dow Chemical Company., (Midland, MI).

[0096] Braskem DS6D82 is a polypropylene random copolymer having a melt flow rate (MFR) of 7.0 g / 10 min, which is commercially available from Braskem.

[0097] 5 -Layer Films

[0098] The multilayer films of Table 2 were prepared on a cast film line at the conditions given in Table 1.Table 1

[0099] Table 2 gives the compositions of some 5 -layer multilayer films of the present disclosure. Unless otherwise specified, all percentages are weight percentages.Table 2

[0100] Referring to Comparative Examples CA-CC in Table 2, it is clear that increasing the polypropylene increases the ultimate stretch and ESTL tear of the films. These properties correlate to improved film wrapping consistency, because the film fails less frequently during pallet wrapping when film tension (F2 stretch) is increased during application. The Machinability test further confirms the impact of ultimate stretch and ESTL tear on wrapping consistency, specifically, the higher the polypropylene content, the higher the film performance during wrapping.

[0101] Further as shown in Table 2, including functionalized polyethylene compatibilizer RETAIN 2000 in the core layer improves ESTL ultimate stretch and ESTL Tear as compared to all Comparative Examples including CC, which has the same amount of polypropylene as the Inventive Example.

[0102] While particular embodiments of the present disclosure 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 disclosure. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this disclosure.

Claims

AMENDED CLAIMS received by the International Bureau on 12 May 2025 (12.05.2025)1. A multilayer film comprising a first outer layer, second outer layer, and a core comprising one or more core layers, wherein a first core layer comprises: a recycled polyethylene having a density from 0.870 to 0.950 g / cm3and a melt index (I2) of 0.5 to 10.0 g / 10 min as determined according to ASTM D1238 (2.16 kg 190 °C); a polyethylene having a density from 0.870 to 0.950 g / cm3and a melt index (I2) of 0.5 to 10.0 g / 10 min; and1 to 10 wt.% of a functionalized polyethylene compatibilizer having a density from 0.860 g / cm3to 0.970 g / cm3and a melt index (I2) of at least 1.0 g / 10 min, wherein the functionalized polyethylene compatibilizer comprises: a copolymerized reaction product of ethylene monomer and ethylenically unsubstituted dicarboxylic acid or derivative thereof; a polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof; or combinations thereof; wherein the multilayer film comprises from 5 to 30 wt.% polypropylene, based on the total weight of the multilayer film.

2. The multilayer film of claim 1 , wherein the ethylenically unsubstituted dicarboxylic acid or derivative thereof is selected from the group consisting of maleic anhydride, itaconic anhydride, maleic acid diesters, fumaric diesters, maleic acid monoesters, fumaric acid monoesters, esters of Cl to C4 alcohols, maleic acid, itaconic acid, fumaric acid, or mixtures thereof.

3. The multilayer film of any preceding claim, wherein the density of the polyethylene is from 0.900 to 0.925 g / cm3and the melt index (I2) of the polyethylene is from 1.0 to 5.0 g / 10 min.

4. The multilayer film of any preceding claim, wherein the density of the recycled polyethylene is from 0.900 to 0.925 g / cm3and the melt index (I2) of the recycled polyethylene is from 1.0 to 5.0 g / 10 min.

5. The composition of any preceding claim, wherein the functionalized polyethylene compatibilizer comprises the copolymerized reaction product of ethylene monomer and ethylenically unsubstituted dicarboxylic acid or derivative thereof, and optionally at least one additional comonomer selected from alkyl acrylate, monocarboxylic acid, or combinations thereof.

6. The composition of any of claims 1 to 4, wherein the functionalized polyethylene compatibilizer comprises the polyethylene grafted with ethylenically unsubstituted dicarboxylic acid or derivative thereof, wherein the polyethylene comprises the polymerized reaction product of ethylene monomer and optionally at least one additional comonomer selected from alkyl acrylate, monocarboxylic acid, or combinations thereof.

7. The multilayer film of any preceding claim, wherein the density of the functionalized polyethylene compatibilizer is from 0.860 g / cm3to 0.900 g / cm3and the melt index (I2) of the functionalized polyethylene compatibilizer is from 500 g / 10 min to 1000 g / 10 min.

8. The multilayer film of any preceding claim, wherein the density of the functionalized polyethylene compatibilizer is from 0.900 g / cm3to 0.925 g / cm3and the melt index (I2) of the functionalized polyethylene compatibilizer is from 1.0 g / 10 min to 10.0 g / 10 min.

9. The multilayer film of any preceding claim, wherein the first core layer comprises 10 to 89 wt.% the recycled polyethylene, and 10 to 89 wt.% the polyethylene, wherein weight percent is based on the total weight of the core layer.

10. The multilayer film of any preceding claim, wherein the first outer layer comprises a polyethylene resin having a density of 0.900 to 0.935 g / cm3and a melt index (I2) of 1.0 to 10.0 g / 10 min.

11. The multilayer film of any preceding claim, wherein at least the second outer layer comprises a polyethylene resin having a density of 0.880 to 0.920 g / cm3and a melt index (I2) of 1.0 to 10.0 g / 10 min.

12. The multilayer film of any preceding claim, wherein the core comprises polypropylene.

13. The multilayer film of any preceding claim, wherein the core comprises a second core layer and a third core layer, the second core layer and the third core layer each comprise polypropylene.

14. The multilayer film of any preceding claim, wherein the first outer layer and the second outer layer each comprise polypropylene.

15. The multilayer film of any preceding claim, wherein the multilayer film has an ESTL ultimate stretch greater than 250%.

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