Cling film

Abstract

The present disclosure provides a film. In an embodiment, the film includes a core structure having a first side and an opposing second side. The core structure includes a release layer. The release layer is composed of an ethylene-based polymer on the first side. A cling layer is on the second side of the core structure. The cling layer includes an acrylic polymer. The film has a cling force from 300 g to 1100 g at 100% stretch.

Description

CLING FILMBACKGROUND

[0001] Polymeric films have wide application in packaging because the properties of polymeric films can be tailored for a desired end use. Overwrap films, for example, are used for packaging goods, foodstuffs, forage crops and bale. In such applications, it is important for the overwrap film to have good barrier properties, good mechanical, cling, and stretch properties, good toughness, and strong resistance to puncture, impact, and tear.

[0002] Silage films are used to store grass and other animal feed crop at farms during the nongrowing season. The typical silage bale wrap film contains a core layer that provides mechanical performance for the film, a cling layer that provides sufficient stickiness and adherence, and a release layer that prevents blockage, decreases the roll unwinding force, and controls unwinding noise. The cling layer typically includes polyisobutylene (PIB) to provide stickiness and cling. PIB is problematic because PIB (i) is a sticky liquid and is difficult to handle; (ii) produces plate-out and contaminates equipment; (iii) is migratory and therefore needs to be incorporated into the core layer in order to reduce bloom-out; and (iv) can impart telescoping effects onto the film.

[0003] Therefore, a need exists for a cling film with improved cling performance for silage applications that avoids PIB.SUMMARY

[0004] The present disclosure provides a film. In an embodiment, the film includes a core structure having a first side and an opposing second side. The core structure includes a release layer. The release layer is composed of an ethylene-based polymer on the first side. A cling layer is on the second side of the core structure. The cling layer includes an acrylic polymer. The film has a cling force from 300 g to 1100 g at 100% stretch.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a graph showing the cling force for examples in accordance with embodiments of the present disclosure.

[0006] Any reference to the Periodic Table of Elements is that as published by CRC Press, Inc., 1990- 1991. Reference to a group of elements in this table is by the new notation for numbering groups.

[0007] For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety (or its equivalent US version is so incorporated by reference) especially with respect to the disclosure of definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure) and general knowledge in the art.

[0008] The numerical ranges disclosed herein include all values from, and including, the lower and upper value. For ranges containing explicit values (e.g., 1 or 2, or 3 to 5, or 6, or 7), any subrange between any two explicit values is included (e.g., 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).

[0009] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight and all test methods are current as of the filing date of this disclosure.

[0001] An "acrylic-based monomer," as used herein, is a monomer having the Structure (I) below:Structure (I)wherein Ri is a H or a Ci-Cis alkyl group, or a C1-C4 alkyl group and R2 is H or CH3. Nonlimiting examples of acrylic comonomers include acrylic acid, methacrylic acid, acrylates, and methacrylates.

[0010] The term "composition" refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0011] The terms "blend" or "polymer blend," as used herein, is a blend of two or more polymers. Such a blend may or may not be miscible (not phase separated at molecular level). Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and other methods known in the art.

[0012] 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. The term "or," unless stated otherwise, refers to the listed members individually as well as in any combination. Use of the singular includes use of the plural and vice versa.

[0013] An "ethylene-based polymer" is a polymer that contains more than 50 weight percent (wt%) polymerized ethylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Ethylene-based polymer includes ethylene homopolymer, and ethylene copolymer (meaning units derived from ethylene and one or more comonomers). The terms "ethylene-based polymer" and "polyethylene" may be used interchangeably. Nonlimiting examples of ethylene-based polymer (polyethylene) include low density polyethylene (LDPE) and linear polyethylene. Nonlimiting examples of linear polyethylene include linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), multi-component ethylene-based copolymer (EPE), ethylene / a-olefin multi-block copolymers (also known as olefin block copolymer (OBC)), substantially linear, or linear, plastomers / elastomers, and high density polyethylene (HDPE). Generally, polyethylene may be produced in gas-phase, fluidized bed reactors, liquid phase slurry process reactors, or liquid phase solution process reactors, using a heterogeneous catalyst system, such as Ziegler-Natta catalyst, a homogeneous catalyst system, comprising Group 4transition metals and ligand structures such as metallocene, non-metallocene metal-centered, heteroaryl, heterovalent aryloxyether, phosphinimine, and others. Combinations of heterogeneous and / or homogeneous catalysts also may be used in either single reactor or dual reactor configurations.

[0014] High density polyethylene (or "HDPE") is an ethylene homopolymer or an ethylene / a-olefin copolymer with at least one C4-C10 a-olefin comonomer, or C4-C8 a-olefin comonomer and a density from 0.940 g / cc, or 0.945 g / cc, or 0.950 g / cc, 0.953 g / cc to 0.955 g / cc, or 0.960 g / cc, or 0.965 g / cc, or 0.970 g / cc, or 0.975 g / cc, or 0.980 g / cc. The HDPE can be a monomodal copolymer or a multimodal copolymer. A "monomodal ethylene copolymer" is an ethylene / C4-Cw a-olefin copolymer that has one distinct peak in a gel permeation chromatography (GPC) showing the molecular weight distribution. A "multimodal ethylene copolymer" is an ethylene / C4-Cio a-olefin copolymer that has at least two distinct peaks in a GPC showing the molecular weight distribution. Multimodal includes copolymer having two peaks (bimodal) as well as copolymer having more than two peaks. Nonlimiting examples of HDPE include DOW™ High Density Polyethylene (HDPE) Resins (available from The Dow Chemical Company), CONTINUUM™ Bimodal Polyethylene Resins (available from The Dow Chemical Company), LUPOLEN™ (available from LyondellBasell), as well as HDPE products from Borealis, Ineos, and ExxonMobil.

[0015] "Low density polyethylene" (or "LDPE") consists of ethylene homopolymer, or ethylene / a-olefin copolymer comprising at least one C3-C10 a-olefin that has a density from 0.915 g / cc to less than 0.940 g / cc and contains long chain branching with broad MWD. LDPE is typically produced by way of high pressure free radical polymerization (tubular reactor or autoclave with free radical initiator). Nonlimiting examples of LDPE include MarFlex™ (Chevron Phillips), LUPOLEN™ (LyondellBasell), as well as LDPE products from Borealis, Ineos, ExxonMobil, and others.

[0016] "Linear low density polyethylene" (or "LLDPE") is a linear ethylene / a-olefin copolymer containing heterogeneous short-chain branching distribution comprising units derived from ethylene and units derived from at least one C3-C10 a-olefin comonomer. LLDPE is characterized by little, if any, long chain branching, in contrast to conventional LDPE. LLDPE has a density from0.910 g / cc to less than 0.940 g / cc. Nonlimiting examples of LLDPE include TUFLIN™ linear low density polyethylene resins (available from The Dow Chemical Company), DOWLEX™ polyethylene resins (available from the Dow Chemical Company), FINGERPRINT™ polyethylene resins (available from the Dow Chemical Company), and MARLEX™ polyethylene (available from Chevron Phillips).

[0017] An "olefin-based polymer" or "polyolefin" is a polymer that contains more than 50 weight percent polymerized olefin monomer (based on total amount of polymerizable monomers), and optionally, may contain at least one comonomer. Nonlimiting examples of olefin-based polymer include ethylene-based polymer and propylene-based polymer.

[0018] A "polymer" is a compound prepared by polymerizing monomers, whether of the same or a different type, that in polymerized form provide the multiple and / or repeating "units" or "mer units" that make up a polymer. The generic term polymer thus embraces the term homopolymer, usually employed to refer to polymers prepared from only one type of monomer, and the term copolymer, usually employed to refer to polymers prepared from at least two types of monomers. It also embraces all forms of copolymer, e.g., random, block, etc. The terms "ethylene / a-olefin polymer" and "propylene / a-olefin polymer" are indicative of copolymer as described above prepared from polymerizing ethylene or propylene respectively and one or more additional, polymerizable a- olefin monomer. It is noted that although a polymer is often referred to as being "made of" one or more specified monomers, "based on" a specified monomer or monomer type, "containing" a specified monomer content, or the like, in this context the term "monomer" is understood to be referring to the polymerized remnant of the specified monomer and not to the unpolymerized species. In general, polymers herein are referred to has being based on "units" that are the polymerized form of a corresponding monomer.

[0019] A "propylene-based polymer" is a polymer that contains more than 50 weight percent polymerized propylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Propylene-based polymer includes propylene homopolymer, and propylene copolymer (meaning units derived from propylene and one or more comonomers). The terms "propylene-based polymer" and "polypropylene" may be used interchangeably. A nonlimiting example of a propylene-based polymer (polypropylene) is apropylene / a-olefin copolymer with at least one C2 or C4-C10 a-olefin comonomer, or a C2 a-olefin comonomer.

[0001] "Ultra low density polyethylene" (or "ULDPE") and "very low density polyethylene" (or "VLDPE") each is a linear ethylene / a-olefin copolymer containing heterogeneous short-chain branching distribution comprising units derived from ethylene and units derived from at least one C3-C10 a-olefin comonomer. ULDPE and VLDPE each has a density from 0.885 g / cc to 0.915 g / cc. Nonlimiting examples of ULDPE and VLDPE include ATTANE™ ultra low density polyethylene resins (available from The Dow Chemical Company) and FLEXOMER™ very low density polyethylene resins (available from The Dow Chemical Company).TEST METHODS

[0020] Cling force. The cling force is the degree of adherence of the cling layer to release layer; the cling force is measured in accordance with ASTM D-5458 - 95, which is a peel cling procedure where a sample of 25.4 mm X 140 mm is adhered to a flat film attached to an surface inclined with a pulling angle of 20°. Afterwards the stripe is clamped with a clip attached to the mobile frame and the load cell. When the clip is pulled, the adhesion is measured as the force required to remove the film strip from the flat film. The main sheet is attached to the inclined plane and a narrow stripe placed over it and pressed against it Cling force from the test are reported in grams.

[0021] Density is measured in accordance with ASTM D792, Method B. The result is recorded in g / cc.

[0022] Differential Scanning Calorimetry (DSC). Differential Scanning Calorimetry (DSC) can be used to measure the melting, crystallization, and glass transition behavior of a polymer over a wide range of temperature. For example, the TA Instruments Q1000 DSC, equipped with an RCS (refrigerated cooling system) and an autosampler is used to perform this analysis. During testing, a nitrogen purge gas flow of 50 ml / min is used. Each sample is melt pressed into a thin film at 190°C; the melted sample is then air-cooled to room temperature (25°C). A 3-10 mg, 6 mm diameter specimen is extracted from the cooled polymer, weighed, placed in a light aluminum pan (50 mg), and crimped shut. Analysis is then performed to determine its thermal properties.

[0023] The thermal behavior of the sample is determined by ramping the sample temperature upand down to create a heat flow versus temperature profile. First, the sample is rapidly heated to 180°C and held isothermal for 3 minutes in order to remove its thermal history. Next, the sample is cooled to -80°Cat a 10°C / minute cooling rate and held isothermal at -80°Cfor 3 minutes. The sample is then heated to 180°C (this is the "second heat" ramp) at a 10°C / minute heating rate. The cooling and second heating curves are recorded. The values determined are extrapolated onset of melting, Tm, and extrapolated onset of crystallization, Tc. Heat of fusion (Hf) (in Joules per gram), the calculated % crystallinity for polyethylene samples using the following equation: % Crystallinity = ((Hf) / 292 J / g) x 100; and the calculated % crystallinity for polypropylene samples using the following equation: % Crystallinity = ((Hf) / 165 J / g) x 100.

[0024] The heat of fusion (Hf) and the peak melting temperature are reported from the second heat curve. Peak crystallization temperature is determined from the cooling curve.

[0025] Melting point, Tm, is determined from the DSC heating curve by first drawing the baseline between the start and end of the melting transition. A tangent line is then drawn to the data on the low temperature side of the melting peak. Where this line intersects the baseline is the extrapolated onset of melting (Tm). This is as described in Bernhard Wunderlich, The Basis of Thermal Analysis, in Thermal Characterization of Polymeric Materials 92, 277-278 (Edith A. Turi ed., 2d ed. 1997).

[0026] Melt index (Ml) (12) in g / 10 min for ethylene-based polymers is measured using ASTM D- 1238-04 (190°C / 2.16kg).

[0027] Melt viscosity (Brookfield). Melt viscosity is determined by ASTM D3236 using a Brookfield Laboratories DVII+ Viscometer equipped with disposable aluminum sample chambers. In general, a SC-31 spindle is used, suitable for measuring viscosities in the range of from 30 to 100,000 centipoise (cP). Ifthe viscosity is outside this range, an alternate spindle should be used which is suitable for the viscosity of the polymer. A cutting blade is employed to cut samples into pieces small enough to fit into the 1 inch wide, 5 inches long samples chamber. The disposable tube is charged with 8-9 grams of polymer. The sample is placed in the chamber, which is in turn inserted into a Brookfield Thermosel and locked into place with bent needle-nose pliers. The sample chamber has a notch on the bottom that fits in the bottom of the Brookfield Thermosel to ensure that the chamber is not allowed to turn when the spindle is inserted and spinning. The sample is heated to the desired temperature (177°C / 350°F). The viscometer apparatus is lowered and the spindle submerged intothe sample chamber. Lowering is continued until brackets on the viscometer align on the Thermosel. The viscometer is turned on, and set to a shear rate which leads to a torque reading in the range of 40 to 70 percent. Readings are taken every minute for about 15 minutes, or until the values stabilize, and then the final reading is recorded.

[0028] Stretch (or film stretch) is measured in accordance with ASTM D4649-03, with results reported in percent ("%"). By way of example, a film at 100% stretch is a film that is stretched, or otherwise oriented, 100% of the film original length. In order to achieve 100% stretch (machine direction) when testing, the films were stretched via tensile machine to 200%, allowed to elastically recover and then the cling force was measured at approximately 100% stretch in the area of the film showing neck-in.DETAILED DESCRIPTION

[0029] The present disclose provides a film. In an embodiment, the film includes a core structure having a first side and a second side opposing the first side. The core structure includes a release layer composed of an ethylene-based polymer. The release layer is on the first side of the core structure. The film includes a cling layer on the second side of the core structure. The cling layer is composed of an acrylic polymer. The film has a cling value from 300 g to 1100 g at 100% stretch.1. Core structure

[0030] The film includes a core structure having opposing sides. A release layer is on one side of the core structure. The core structure may be a single layer film structure (wherein the release layer constitutes the entirety of the core structure). Alternatively, the core structure may be a multilayer film structure.

[0031] The release layer is composed of one or more ethylene-based polymers. Nonlimiting examples of suitable ethylene-based polymer include high density polyethylene, low density polyethylene, linear low density polyethylene, ultra low density polyethylene, and any combination thereof.

[0032] In an embodiment, the core structure is a monolayer structure and the release layer forms the core structure. In other words, when the core structure is the monolayer structure, the core structure is composed solely of the release layer. The release layer is composed of one or moreethylene-based polymers.

[0033] In an embodiment, the core layer is a multilayer structure. The core layer may include two, or three, or four, or five, or six, or seven, or eight, or nine, or more layers. The composition of each layer can be the same or different.

[0034] In an embodiment the core structure is a three layer structure of (i) the release layer, (ii) a core layer, and (iii) an intermediate layer disposed between the release layer and the core layer. The core layer is in direct contact with the cling layer. In a further embodiment, each of the release layer, the core layer, and the intermediate layer is composed of one or more ethylene-based polymers.

[0035] In an embodiment, the core structure has a thickness of from 6.0 pm, or 7.0 pm, or 8.0 pm, or 9.0 pm, or 10.0 pm, or 11.0 pm, or 12.0 pm, or 13.0 pm, or 14.0 pm, or 15.0 pm, or 16.0 pm, or 17.0 pm, or 18.0 pm, or 19.0 pm, or 19.8 pm to 22.2 pm, or 23.0 pm, or 25 pm, or 30 pm, or 35 pm, or 40 pm, or 45 pm, or 50 pm, or 65 pm, or 70 pm, or 75 pm, or 80 pm, or 85 pm, or 90 pm.2. Cling layer

[0036] The present film includes the cling layer. The cling layer is on the second side of the core structure and is an outermost layer. The cling layer is on the side opposite to the release layer on the core structure. The cling layer is in direct contact with the core structure. The term "direct contact with" or "directly contacts" refers to a layer configuration whereby a first layer is located immediately adjacent to a second layer and no intervening layers or no intervening structures are present between the first layer and the second layer.

[0037] The cling layer is composed of an acrylic polymer. The acrylic polymer is applied to the second side of the core structure by way of a water-based acrylic dispersion. The term "water-based acrylic dispersion" is a composition wherein water is the continuous phase, i.e., a composition having an aqueous medium. The water-based acrylic dispersion includes water, one or more acrylic-based monomers, an initiator, a surfactant, and an optional neutralizer, to the exclusion of an ethylene-based polymer (interchangeably referred to as "acrylic emulsion"). The surfactant acts as an emulsifier and enables droplets of the acrylic-based monomer, which is hydrophobic, to form throughout the aqueous medium. A neutralizer is then introduced into the emulsified mixture. The neutralizer reacts with the acrylic-based monomer(s) dispersed throughout the aqueous medium until all, or substantially all, of the acrylic-based monomer(s) is / arepolymerized. The end result is an acrylic dispersion composed of a dispersion of acrylic-based polymer particles in the aqueous medium, the acrylic-based polymer particles composed of one or more acrylic-based monomer subunits to the exclusion of ethylene-based polymer.

[0038] The acrylic polymer has a Tg less than -20°C, or from -80°C to -20°C, or from -70°C to - 30°C, or from -60°C to -40°C and a Mw from greater than 100,000 daltons to 10,000,000 daltons and is composed of one or more acrylic-based monomers. Nonlimiting examples of suitable acrylic-based monomers include acrylic acid (AA), butyl acrylate (BA), ethylhexyl acrylate (2-EHA), ethyl acrylate (EA), methyl acrylate (MA), butyl methyacrylate (BMA), octyl acrylate, isooctyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate (MMA), isobutyl methacrylate, octyl methacrylate, isooctyl methacrylate, decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, pentadecyl methacrylate, stearyl methacrylate, n-butyl methacrylate, C12 to Cis alkyl methacrylates, cyclohexyl methacrylate, methacrylic acid, and combinations thereof. In addition to acrylic-based monomer, the acrylicbased polymer may also include monomer such as 2-hydroxyethyl acrylate (2-HEA), styrene (STY), vinyl ester, vinyl acetate, and combinations thereof.

[0039] In an embodiment, the acrylic polymer is composed of, or otherwise consists of, the acrylic-based monomers butyl acrylate, methyl methacrylate, methacrylic acid, 2 ethyl-hexyl acrylate, ethyl acrylate, styrene, acrylic acid, and any combination thereof, and the acrylic polymer has a Tg from -50°C to -20°C. In an further embodiment, the acrylic polymer is butyl acrylate / methyl methacrylate / ethyl acrylate / ethyl hexyl acrylate polymer (>95%) and is void of, or otherwise excludes ethylene (or polymerized units of ethylene), and / or butene (or polymerized units of butene).

[0040] In an embodiment, the acrylic polymer excludes, or otherwise is void of, styrene.

[0041] The water-based acrylic dispersion includes a surfactant. Nonlimiting examples of suitable surfactant include cationic surfactants, anionic surfactants, zwitterionic surfactants, non-ionic surfactants, and combinations thereof.

[0042] The water-based acrylic dispersion includes a neutralizer that stabilizes the acrylic dispersion.

[0043] The cling layer is formed by applying the water-based acrylic dispersion onto the second side of the core structure, followed by drying or curing. For the application of the water-based acrylic dispersion, a coater, e.g., a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, curtain coater, slot die coater, comma coater, knife coater or the like, can be employed.

[0044] In an embodiment, the surface of the second side of the core structure is subjected to a surface treatment. Nonlimiting examples of suitable surface treatments include a primer coating, plasma treatment, and / or a corona discharge treatment prior to application of the water-based acrylic dispersion onto the second side of the core structure. The second surface is corona treated or plasma treated in order to increase the surface energy of the film. After such corona treatment or plasma treatment, the second surface exhibits a surface energy of at least 38 dynes / cm2, or at least 39 dynes / cm2, or at least 40 dynes / cm2, or at least 41 dynes / cm2, or at least 42 dynes / cm2or from 38 dynes / cm2to 42 dynes / cm2as measured in accordance with ASTM D 2578-04. In a further embodiment, the surface of the second side of the core structure exhibits a surface energy from 38 dynes / cm2to 42 dynes / cm2at 60 days following the corona treatment. The surface energy is measured using US ACC dyne pens following ASTM D2578-04.

[0045] Upon drying, the particles of the water-based acrylic dispersion coalesce on the second side of the core structure to form a uniform cling layer, or a substantially uniform cling layer, on the core structure. The cling layer is coextensive with, or substantially coextensive with, the second side, thereby forming the cling layer. The cling layer is in direct contact with the second side of the core structure. In an embodiment, the thickness of the cling layer is from 1 micron to 100 microns, or from 10 microns to 75 microns, or from 15 microns to 30 microns.

[0046] The core structure and / or the cling layer may include optional additives. When the additive is present, nonlimiting examples of suitable additives include anti-block additives, antioxidants, antistatic agents, stabilizing agents, nucleating agents, colorants, pigments (TiOz particles), ultra violet (UV) absorbers or stabilizers, flame retardants, compatibilizers, plasticizers, fillers, processing aids, slip agents, and combinations thereof.

[0047] The present film is a cling film and is also a stretchable film. A "cling film," as used herein,is a film that adheres to itself when the film is overlapped upon itself, or adheres to itself when the cling layer contacts the release layer. The present cling film can be stretched to 100%, or 400% of its original, unstretched length, or stretched between 100% and 200%. The film exhibits a cling force from 300 g to 1100 g at 100% stretch.

[0048] In an embodiment, the film comprises, or consists of:(i) a core structure having a monolayer structure such that the core structure is composed solely of the release layer, the release layer composed solely of one or more ethylenebased polymers (and optional additives); and

[0049] (ii) a cling layer in direct contact with the core structure the cling layer comprising, or consisting of, an acrylic polymer with monomers selected from buthyl acrylate, methyl methacrylate, methacrylic acid, 2-ethyl-hexyl acrylate, ethyl acrylate, styrene, acrylic acid, and any combination thereof; and the film has a thickness from 20 pm to 90 pm, or 25 pm to 80 and the film has a cling force from 300 g to 1100 g, or from 450 g to 1100 g at 100% stretch.

[0050] In an embodiment, the film comprises, or consists of:(i) a core structure having a multilayer structure such that the core structure has three layers: (i) the release layer, (ii) a core layer, and (iii) an intermediate layer disposed between the release layer and the core layer, each of the release layer, the core layer, and the intermediate layer is composed solely of one or more ethylene-based polymers (and optional additives); and(ii) a cling layer in direct contact with the core structure the cling layer comprising, or consisting of, an acrylic polymer with monomers butyl acrylate, methyl methacrylate, methacrylic acid, 2-ethyl-hexyl acrylate, ethyl acrylate, styrene, acrylic acid, and any combination thereof; and the film has a thickness from 20 pm to 90 pm, or 25 pm to 80 and the film has a cling force from 300 g to 1100 g, or from 450 g to 1100 g at 100% stretch.

[0051] The film may comprise two or more embodiments disclosed herein.3. Process

[0052] The present disclosure provides a process. In an embodiment, the process includes stretching a film to at least 100%. The film is the present film and includes a core structure havinga first side and an opposing second side. The core structure includes a release layer composed of an ethylene-based polymer on the first side. The film includes a cling layer on the second side of the core structure. The cling layer is composed of an acrylic polymer. The process includes wrapping the film around a bale of a forage crop, contacting the cling layer to the release layer, and adhering the cling layer to the release layer at a cling force from 300 g to 1100 g at 100% stretch.

[0053] The film used in the process is the present film having the core structure and the cling layer. The core structure can be a monolayer structure (release layer only) or a multilayer structure as previously disclosed herein.

[0054] The process includes stretching the film to at least 100% and wrapping the film around a bale of forage crop. The stretching step and the wrapping step can occur sequentially. Alternatively, the stretching step and the wrapping step occur simultaneously, or substantially simultaneously. A "forage crop" is any plant that is grown and fed to livestock. Nonlimiting examples of forage crops include beans, clover, corns, cornstalk, grasses, grains (barley, oats, rice, wheat, rye, millet), hay, legumes (alfalfa, red clover, white clover, alsike clover, birdsfoot trefoil, vetches, sweetclover), sorghums, soybeans, vegetables, and any combination of the foregoing.

[0055] In an embodiment, a portion of the film cling layer contacts a portion of the bale and / or a portion of the forage crop.

[0056] In an embodiment, the process includes forming, with the film, a barrier around the bale of forage crop. A bale wrapping device wraps the present film around the bale to form a barrier. A bale wrapping device typically includes a loading arm that lifts the bale and places it on a wrapping table. The wrapping table includes rollers and belts which rotate the bale while the table itself revolves. A dispensing device provides one or more rolls of the wrapping film ( / .e., the present film). As the bale turns, the wrapping film is typically stretched as it is pulled through the dispensing device and wrapped tightly around the bale to remove oxygen from the bale. When the table has revolved a predetermined number of times, a lift device tilts the wrapping table to tip the wrapped bale off of the wrapping table. The dispensing device cuts the wrapping film prior to the wrapped bale falling from the wrapping table. Operation of the bale wrapping device can be controlled automatically (by way of a computer or similar logic) or manually. Conventionalbale wrapping procedures typically wrap the bale with from four to six layers of the wrapping film (i.e., the present film).

[0057] The process includes stretching the film to at least 100%, wrapping the film around the bale of forage crop and forming, with the stretched and wrapped film, a barrier around the bale to form a bale silage. The cling layer adheres to the release layer at a cling force from 300 g to 1100 g, or from 450 g to 1100 g at 100% stretch to form and maintain the barrier. The barrier is held together by the cling force applied by the present stretched cling film. A "bale silage" is one or more forage crops formed into a bale and covered with a wrapping (i.e., covered with the present stretched film) to exclude oxygen. Once wrapped, the bale of forage crop undergoes an ensiling process whereby anaerobic microorganisms ferment carbohydrates present in the forage crop to lactic acid forming silage. This fermentation process inhibits the growth of other detrimental microorganisms. Bale silage typically has a moisture content from 40 wt % to 60 wt %.

[0058] Damage to the barrier covering, surrounding, or otherwise encasing the bale silage is disfavored. Holes or tears in the barrier, for example, allow oxygen to enter the bale silage. Oxygen in the bale silage leads to aerobic deterioration of the silage resulting in spoilage. The present film stretched to at least 100%, or to 100%, with core structure and cling layer and cling force from 300 g to 1100 g provides suitable cling to maintain an airtight, or substantially airtight, barrier for extended periods and advantageously prevents aerobic deterioration of the bale silage.

[0059] By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail in the following Examples.EXAMPLES

[0060] Materials used in the inventive examples ("IE") and comparative samples ("CS") are provided in Table 1 below.Table 11. Preparation of multilayer films

[0061] Multilayer films with a thickness of 50 microns are provided with core structures having the layer configuration A / B / C at 15 / 70 / 15 volume ratio wherein A and B are Dowlex 2045G and C is 85 wt% Dowlex 2045G and 15 wt% LDPE150E, based on the total weight of layer C. An aqueous dispersion of acrylic polymer is applied to layer A via direct coating of the emulsion with a stainless steel meyer bar set for a dry coating weight of 5.0 gsm over a levelled lamination table. The coated multilayer film samples are dried in an oven at 120°C for 3 minutes forming a uniform cling layer on the core structure, the cling layer A having a thickness of 5-12.5 microns and the cling layer having a coat weight of 5-8 GSM (grams per square meter). After that, the samples were protected with siliconized release liner and placed in a controlled-temperature room (CTR) at 23.0 ± 0.5 °C and 50 ± 5 % RH for conditioning for 30 minutes.2. Stretch and cling evaluation

[0062] Cling force was measured on film samples at 0% stretch and at 100% stretch. The results are provided in Table 2 below.

[0063] Table 2* wt% based on total weight of the cling layer composition

[0064] Applicant discovered that the cling level unexpectedly is maintained when the film isstretched 100%. The present film thereby provides cling on the outer film surface when stretched 100%.

[0065] It is specifically intended that the present disclosure not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.

Claims

CLAIMS1. A film comprising: a core structure having a first side and an opposing second side, the core structure comprising a release layer composed of an ethylene-based polymer on the first side; a cling layer on the second side of the core structure, the cling layer comprising an acrylic polymer; and the film has a cling force from 300 g to 1100 g at 100% stretch.

2. The film of claim 1 wherein the core structure comprises the release layer and one or more other layers.

3. The film of claim 2 wherein the core structure comprises one or more ethylene-based polymers.

4. The film of any of claims 1-3 wherein the cling layer comprises an acrylic polymer having a butyl acrylate monomer.

5. The film of claim 4 wherein the cling layer(i) has a thickness from 4 GSM to 10 GSM; and(ii) the film has a cling force from 450g to 1100g at 100% stretch.

6. The film of any of claims 1-5 wherein the second side of the core structure comprises a surface-treated layer having a surface energy of at least 38 dynes / cm2.

7. A process comprising: stretching a film to at least 100%, the film comprisinga core structure having a first side and an opposing second side, the core structure comprising a release layer composed of an ethylene-based polymer on the first side, a cling layer on the second side of the core structure, the cling layer comprising an acrylic polymer; wrapping the film around a bale of a forage crop; contacting the cling layer to the release layer; and adhering the cling layer to the release layer at a cling force from 300 g to 1000 g at 100% stretch.

8. The process of claim 7 comprising forming, with the film, a barrier around the bale.

9. The process of any of claims 7-8 comprising contacting a portion of the bale with a portion of the cling layer.

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