Agricultural storage bag comprising polyethylene

Abstract

Multilayer films are provided. Multilayer films according to embodiments disclosed herein are suitable for making farm storage bags and include one or more core layers having a small amount of a polyethylene elastomer having a Brookfield viscosity of less than 12.0 Pa.s. The multilayer films can have a desirable balance of properties, such as puncture and tear properties.

Description

Technical Field

[0001] The embodiments disclosed herein generally relate to multilayer films suitable for making agricultural storage bags and methods thereof. Background Technology

[0002] Agricultural storage bags are an essential component of modern agricultural practice, providing a convenient and effective method for storing and preserving grains, forage, and other agricultural products. These large, flexible storage solutions are designed to protect the contents from environmental factors such as moisture, pests, and UV exposure. By providing a controlled atmosphere, agricultural storage bags can significantly extend the shelf life of the stored materials, ensuring that farmers can maintain the quality and nutritional value of their products until they are ready for use or sale.

[0003] The performance of agricultural storage bags faces several challenges in industry. One of the main issues is the durability and strength of the materials used in their construction. Agricultural storage bags must withstand harsh weather conditions, mechanical stress during filling and unloading, and potential damage from wildlife. Additionally, there is a need to balance the cost-effectiveness of production with the ability to provide sufficient protection and lifespan. Innovations in materials science and manufacturing processes are crucial to addressing these issues and enhancing the overall performance of agricultural storage bags, ensuring they remain a reliable and sustainable solution for agricultural storage. For example, agricultural storage bag applications made from blown multilayer films typically require high MD tear propagation resistance for unloading, high puncture resistance against uneven ground, high dart resistance to heavy rain and hail, and high creep resistance to maintain shape. Beyond these challenges, industry faces the challenge of reducing thickness and using less material to perform similar tasks. Therefore, new multilayer film formulations are needed to meet the requirements of agricultural storage bag applications and reduce material usage. Summary of the Invention

[0004] The embodiments disclosed herein satisfy one or more of the aforementioned needs by providing a multilayer film that achieves a balance of agricultural storage bag properties.

[0005] In a first aspect, a multilayer membrane is disclosed. The multilayer membrane includes a first outer layer, a second outer layer, and one or more core layers. The one or more core layers are positioned between the first outer layer and the second outer layer. Based on the total weight of the one or more core layers, the one or more core layers comprise at least 95% by weight of an ethylene polymer, at least 65% by weight of linear low-density polyethylene, less than 30% by weight of low-density polyethylene, and less than 5% by weight of a polyethylene elastomer. The first core layer comprises a combination of low-density polyethylene, linear low-density polyethylene, and a polyethylene elastomer having a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s.

[0006] In a second aspect, a method for producing a multilayer film is disclosed. The method includes: extruding a first outer layer, a second outer layer, and one or more core layers to form a multilayer film, wherein the one or more core layers are positioned between the first outer layer and the second outer layer; based on the total weight of the one or more core layers, the one or more core layers comprise at least 95% by weight of an ethylene polymer, at least 65% by weight of linear low-density polyethylene, less than 30% by weight of low-density polyethylene, and less than 5% by weight of a polyethylene elastomer, wherein the first core layer comprises a combination of low-density polyethylene, linear low-density polyethylene, and a polyethylene elastomer having a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s.

[0007] These and other implementation schemes are described in more detail in the specific embodiments. Detailed Implementation

[0008] The disclosed multilayer film is described in more detail below. Multilayer films are suitable for making agricultural storage bags and have a wide range of applications, including, for example, as coverings or bags.

[0009] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers of the same or different types. Therefore, the general term polymer encompasses the term homopolymer (used to refer to a polymer prepared from only one type of monomer) and the term copolymer or interpolymer. Trace amounts of impurities (e.g., catalyst residues) may be incorporated into and / or within a polymer. A polymer can be a single polymer, a polymer blend, or a mixture of polymers comprising a mixture of polymers formed in situ during polymerization.

[0010] As used herein, the term "copolymer" refers to a polymer formed by the polymerization of at least two monomers with different structures. The term "copolymer" includes terpolymers.

[0011] As used herein, the terms "polyethylene" or "ethylene-based polymer" should mean a polymer comprising a majority (>50 mol%) unit derived from ethylene monomers. This includes polyethylene homopolymers and copolymers (meaning units derived from two or more comonomers). The terms "ethylene-based polymer" and "polyethylene" are used interchangeably. Generally, polyethylene can be produced in gas-phase fluidized bed reactors, liquid-phase slurry reactors, or liquid-phase solution reactors using heterogeneous catalyst systems (such as Ziegler-Natta catalysts) and homogeneous catalyst systems containing Group 4 transition metals and ligand structures (such as metallocenes, non-metallocene metal centers, heteroaryl groups, isovalent aryloxy ethers, phosphine imides, etc.). Combinations of heterogeneous and / or homogeneous catalysts can also be used in single-reactor or dual-reactor configurations.

[0012] As used herein, the term "low-density polyethylene" or "LDPE" refers to "high-pressure ethylene polymer" or "highly branched polyethylene," and is defined to mean that the polymer is partially or wholly homopolymerized or copolymerized in an autoclave or tubular reactor at pressures above 14,500 psi (100 MPa) using a free radical initiator (such as peroxide) (see, for example, US 4,599,392, which is hereby incorporated herein by reference). As used herein, LDPE has a density of 0.910 to 0.930 g / cm³. 3 The density within the range.

[0013] The term "linear low-density polyethylene" or "LLDPE" includes resins prepared using conventional Ziegler-Natta catalyst systems and chromium-based catalyst systems, as well as single-site catalysts (including, but not limited to, substituted mono- or dicyclopentadienyl catalysts (commonly referred to as metallocenes), confined geometry catalysts, phosphine imine catalysts, and polyvalent aryloxy ether catalysts (commonly referred to as diphenylphenoxys), and comprising linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains less long-chain branching than LDPE, and LLDPE comprises substantially linear ethylene polymers, further defined in U.S. Patents 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 3,645,992; non-homogeneously branched ethylene polymers, such as those prepared according to the method disclosed in U.S. Patent No. 4,076,698; and / or blends thereof (such as those in U.S. Patent No. 4,076,698). (Those disclosed in US 3,914,342 or US 5,854,045). LLDPE can be manufactured by gas-phase, solution-phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art. As used herein, LLDPE has a viscosity ranging from 0.910 to 0.940 g / cm³. 3 The density within the range.

[0014] The term "polyethylene elastomer" should mean an ethylene / α-olefin copolymer that (i) comprises units derived from ethylene and units derived from at least one C3-C10 α-olefin comonomer, or at least one C4-C8 α-olefin comonomer, or at least one C6-C8 α-olefin comonomer; and (ii) has a content of 0.865 g / cm³. 3 or 0.870 g / cm 3 or 0.880 g / cm 3 or 0.890 g / cm 3 Up to 0.900 g / cm3 or 0.902 g / cm 3 or 0.904 g / cm 3 or 0.909 g / cm 3 or 0.910 g / cm 3 The density. α-olefin comonomers include C3-C 20 α-olefins, particularly propylene, isobutene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, and 1-decene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. This includes substantially linear or linear ethylene / α-olefin copolymers and ethylene / α-olefin multiblock copolymers containing a uniform distribution of short-chain branching. Non-limiting examples of ethylene elastomers include commercially available elastomers such as ENGAGE. ™ Polyolefin elastomers, and INFUSE ™ Olefin block copolymers (available from The Dow Chemical Company), EXACT ™ Plastics (available from ExxonMobil Chemical), Tafmer (available from Mitsui), Nexlene ™ (Available from SK Chemicals Co.) and Lucene ™ (Available from LG Chem Ltd.)

[0015] As used herein, the term "composition" means the materials comprising the composition, as well as mixtures of reaction products and decomposition products formed from the materials of the composition.

[0016] 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 such components, steps, or procedures are specifically disclosed. For the avoidance of any doubt, unless stated to the contrary, all compositions claimed using the term “comprising” may contain any additional additives, adjuvants, or compounds, whether polymeric or otherwise. In contrast, the term “substantially constitutes” excludes any other components, steps, or procedures from any subsequently listed scope, except those that are not essential for operability. The term “consisting of” excludes any components, steps, or procedures not specifically described or listed.

[0017] This document discloses multilayer films. A multilayer film includes a first outer layer, a second outer layer, and one or more core layers positioned between the first and second outer layers. The number of layers in the multilayer film is not particularly limited, except that the film has at least three layers, including a first outer layer, a first core layer, and a second outer layer. The location of the first core layer (e.g., when multiple core layers are present) is not particularly limited, except that it must be positioned between the first and second outer layers. In some embodiments, the multilayer film is a three-layer film having a first outer layer, a second outer layer, and a first core layer. Multilayer films may include 4, 5, 6, 7, 8, 9, 10, 11, or more layers. In one embodiment, the multilayer film includes five layers, including a first outer layer, a first core layer, a second core layer, a third core layer, and a second outer layer (A / B / C / D / E, where A and E are outer layers). The film may have different thicknesses. In some embodiments, the membrane has a thickness of 10 micrometers to 500 micrometers, or 20 micrometers to 350 micrometers, or 50 micrometers to 300 micrometers, or 180 micrometers to 260 micrometers. When the membrane is a blown film suitable for use as an agricultural storage bag, the membrane can be thickened while maintaining a balance of properties as disclosed herein. In some embodiments, the membrane is a five-layer membrane with a layer ratio of 20 / 20 / 20 / 20 / 20 having equally distributed layers, or a five-layer membrane with a layer ratio of 15 / 20 / 30 / 20 / 15, or ratios between these embodiments. In some embodiments, each layer of the membrane is between 15% and 30% of the total thickness of the membrane. In some embodiments, the first outer layer is between 15% and 30% of the total thickness of the membrane. In some embodiments, the one or more core layers are between 40% and 70% of the total thickness of the membrane.

[0018] In some embodiments, the multilayer membrane comprises at least 95% by weight of a vinyl polymer, or at least 97% by weight of a vinyl polymer, or at least 99% by weight of a vinyl polymer, based on the total weight of the membrane. In some embodiments, the multilayer membrane contains no polymers other than vinyl polymers. Membranes made solely or almost entirely of vinyl polymers are easier to recycle.

[0019] In some embodiments, based on the total weight of the membrane, the multilayer membrane comprises at least 60 wt% LLDPE, or at least 65 wt% LLDPE, or at least 70 wt% LLDPE, or 60 wt% to 80 wt% LLDPE. In some embodiments, based on the total weight of the multilayer membrane, the multilayer membrane comprises less than 35 wt% LDPE, less than 30 wt% LDPE, less than 25 wt% or less than 20 wt% LDPE. In some embodiments, based on the total weight of the membrane, the multilayer membrane comprises at least 15 wt% LDPE, at least 20 wt% LDPE, or at least 25 wt% LDPE, or at least 30 wt% LDPE, or 15 wt% to 40 wt% LDPE. In some embodiments, based on the total weight of the membrane, the multilayer membrane comprises less than 3 wt% polyethylene elastomer, less than 2 wt% polyethylene elastomer, or less than 1 wt% polyethylene elastomer. In some embodiments, the multilayer membrane comprises at least 0.1 wt%, at least 0.5 wt%, or at least 1 wt% or at least 3 wt% of polyethylene elastomer, based on the total weight of the membrane. For example, in some embodiments, the multilayer membrane comprises 65 wt% to 80 wt% of linear low-density polyethylene, 20 wt% to 30 wt% of low-density polyethylene, and less than 3 wt% of polyethylene elastomer, based on the total weight of the membrane.

[0020] Core layer

[0021] The multilayer membrane includes one or more core layers. The one or more core layers are positioned between a first outer layer and a second outer layer. Based on the total weight of the one or more core layers, the one or more core layers comprise at least 95% by weight of an ethylene polymer, at least 65% by weight of linear low-density polyethylene, less than 30% by weight of low-density polyethylene, and less than 5% by weight of a polyethylene elastomer. In this document, at least one core layer is considered a “first core layer.” Other specific core layers may be considered a “second core layer” or a “third core layer.” A core layer in the membrane is considered “one or more core layers.” In the presence of more than one core layer, the more than one core layer can be arranged in any order between the second outer layer and the first outer layer. In a three-layer embodiment, the multilayer membrane has a first outer layer, a first core layer, and a second outer layer as three layers. In some embodiments, the one or more core layers account for at least 40% of the total thickness of the membrane. In some embodiments, the one or more core layers account for 40% to 70% of the total thickness of the membrane, or 45% to 65% of the total thickness of the membrane.

[0022] The one or more core layers comprise at least 95 wt% ethylene-based polymers. In some embodiments, the one or more core layers comprise at least 96 wt%, 97 wt%, 98 wt%, or 99 wt% ethylene-based polymers based on their total weight. The one or more core layers may not contain polymers other than ethylene-based polymers. The one or more core layers comprise at least 65 wt% linear low-density polyethylene. In some embodiments, the one or more core layers comprise at least 66 wt%, 67 wt%, 68 wt%, 69 wt%, or 70 wt% linear low-density polyethylene based on their total weight, or comprise 65 wt% to 80 wt% or 65 wt% to 75 wt% linear low-density polyethylene based on their total weight. The one or more core layers comprise less than 30 wt% low-density polyethylene. In some embodiments, based on the total weight of one or more core layers, the one or more core layers comprise less than 29 wt%, 28 wt%, 27 wt%, 26 wt%, or 25 wt% of low-density polyethylene, or 15 wt% to 30 wt%, or 20 wt% to 30 wt%, or 22 wt% to 27 wt% of low-density polyethylene, based on the total weight of the one or more core layers. The one or more core layers comprise less than 5 wt% of polyethylene elastomer. In some embodiments, based on the total weight of the one or more core layers, the one or more core layers comprise less than 4 wt%, 3 wt%, or 2 wt% of polyethylene elastomer, or 0.5 wt% to 5 wt%, or 1 wt% to 5 wt%, or 1 wt% to 4 wt% of polyethylene elastomer. In some embodiments, for example, based on the total weight of the one or more core layers, the one or more core layers comprise 65 wt% to 80 wt% of linear low-density polyethylene, 20 wt% to 30 wt% of low-density polyethylene, and less than 5 wt% of polyethylene elastomer.

[0023] The first core layer comprises a combination of low-density polyethylene, linear low-density polyethylene, and a polyethylene elastomer having a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s. These are specific vinyl polymers of the first core layer and are vinyl polymers that contribute a weight percentage to the one or more core layers or films. As is well known to those skilled in the art, the one or more core layers may include additional types of LLDPE, LDPE, or polyethylene elastomers (e.g., different densities or melt indices as defined above) to achieve the weight percentages of the one or more core layers described herein. In some embodiments, where the first core layer is the only core layer, the first core layer comprises at least 95 wt% vinyl polymer, at least 65 wt% linear low-density polyethylene, less than 30 wt% low-density polyethylene, and less than 5 wt% polyethylene elastomer.

[0024] In some embodiments, the low-density polyethylene of the first core layer has a density between 0.910 g / cc and 0.930 g / cc and a melt index (I2) between 0.1 g / 10 min and 7.0 g / 10 min. In some embodiments, the low-density polyethylene of the first core layer has a density with a lower limit of 0.910 g / cc, 0.912 g / cc, 0.914 g / cc, 0.916 g / cc, 0.918 g / cc or 0.920 g / cc and an upper limit of 0.928 g / cc, 0.926 g / cc, 0.924 g / cc or 0.922 g / cc. In some embodiments, the low-density polyethylene of the first core layer has a melt index (I2) of 0.1 g / 10 min to 6.0 g / 10 min, 0.1 g / 10 min to 6.0 g / 10 min, 0.1 g / 10 min to 5.0 g / 10 min, 0.1 g / 10 min to 4.0 g / 10 min, 0.1 g / 10 min to 3.0 g / 10 min, 0.1 g / 10 min to 2.0 g / 10 min, or 0.2 g / 10 min to 1.0 g / 10 min. Based on the total weight of the first core layer, the first core layer may contain less than 30% by weight or 10% by weight to 30% by weight of the low-density polyethylene of the first core layer.

[0025] In some embodiments, the linear low-density polyethylene of the first core layer has a density between 0.910 g / cc and 0.930 g / cc and a melt index (I2) between 0.2 g / 10 min and 5.0 g / 10 min. In some embodiments, the linear low-density polyethylene of the first core layer has a density with a lower limit of 0.910 g / cc, 0.912 g / cc, 0.914 g / cc, 0.916 g / cc, 0.918 g / cc or 0.920 g / cc and an upper limit of 0.928 g / cc, 0.926 g / cc, 0.924 g / cc or 0.922 g / cc. In some embodiments, the linear low-density polyethylene of the first core layer has a melt index (I2) of 0.2 g / 10 min to 5.0 g / 10 min, 0.3 g / 10 min to 4.0 g / 10 min, 0.4 g / 10 min to 3.0 g / 10 min, 0.4 g / 10 min to 2.0 g / 10 min, or 0.5 g / 10 min to 2.0 g / 10 min. Based on the total weight of the first core layer, it may contain at least 65 wt% linear low-density polyethylene, or 65 wt% to 80 wt% linear lower-density polyethylene. In some embodiments, the linear low-density first core layer contains 1-octene.

[0026] The polyethylene elastomer of the first core layer has a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s. In some embodiments, the polyethylene elastomer of the first core layer has a lower limit density of 0.855 g / cc, 0.860 g / cc, or 0.865 g / cc and an upper limit density of 0.910 g / cc, 0.905 g / cc, 0.900 g / cc, 0.895 g / cc, 0.890 g / cc, 0.885 g / cc, 0.880 g / cc, or 0.875 g / cc. In some embodiments, the polyethylene elastomer of the first core layer has a Brinell viscosity of less than 11.0 Pa·s, less than 10.0 Pa·s, less than 9.0 Pa·s, or less than 8.5 Pa·s, or 6.0 Pa·s to 11.0 Pa·s or 7.0 Pa·s to 10.0 Pa·s. In some embodiments, the polyethylene elastomer of the first core layer has a melt index (I2) greater than 500 g / 10 min. In some embodiments, the first core layer contains less than 5% by weight of polyethylene elastomer, or 1% to 4% by weight of polyethylene elastomer, based on the total weight of the first core layer.

[0027] In some embodiments, the multilayer film includes a second core layer comprising a second low-density polyethylene (LDPE), a second linear low-density polyethylene (LLDPE), and a second polyethylene elastomer having a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s. In such embodiments, the second LLDPE, the second LLDPE, and the second polyethylene elastomer may be of the same or different types (e.g., trade names, densities, melt index) of the LLDPE, LLDPE, and polyethylene elastomer of the first core layer, as described herein. Similarly, in some embodiments, the multilayer film includes a third core layer or even more core layers comprising linear low-density polyethylene (LDPE), LLDPE, and / or polyethylene elastomer.

[0028] outer layer

[0029] In some embodiments, the first outer layer and the second outer layer each comprise linear low-density polyethylene and low-density polyethylene. In some embodiments, the first and second outer layers do not include polyethylene elastomer. In some embodiments, based on the total weight of the first outer layer, the first outer layer comprises at least 60% by weight of LLDPE, or at least 65% by weight of LLDPE, or at least 70% by weight of LLDPE, or 60% to 80% by weight of LLDPE. In some embodiments, based on the total weight of the first outer layer, the first outer layer comprises less than 35% by weight of LDPE, less than 30% by weight of LDPE, less than 25% by weight of LDPE, or less than 20% by weight of LDPE. In some embodiments, based on the total weight of the first outer layer, the first outer layer comprises at least 15% by weight of LDPE, at least 20% by weight of LDPE, or at least 25% by weight of LDPE, or at least 30% by weight of LDPE, or 15% to 40% by weight of LDPE.

[0030] In some embodiments, the second outer layer comprises at least 60 wt% LLDPE, or at least 65 wt% LLDPE, or at least 70 wt% LLDPE, or 60 wt% to 80 wt% LLDPE, based on the total weight of the second outer layer. In some embodiments, the second outer layer comprises less than 35 wt% LDPE, less than 30 wt% LDPE, less than 25 wt% or less than 20 wt% LDPE, based on the total weight of the second outer layer. In some embodiments, the second outer layer comprises at least 15 wt% LDPE, at least 20 wt% LDPE, or at least 25 wt% LDPE, or at least 30 wt% LDPE, or 15 wt% to 40 wt% LDPE, based on the total weight of the second outer layer. The first and second outer layers may comprise at least 95 wt% or 97 wt% or 99 wt% ethylene polymers.

[0031] Commercially available low-density polyethylene suitable for use in multilayer films according to the embodiments disclosed herein includes those commercially available from Dow Chemical Company, such as AGILITY. ™ AT 1604 is a performance LDPE and LDPE 310E. Other commercially available low-density polyethylenes include Sabic 2100, Carmel Ipethene 4203, Braskem LD7000A, Celanese AT505, and Repsol PE-033.

[0032] Commercially available linear low-density polyethylene suitable for use in multilayer films according to embodiments disclosed herein includes those commercially available from Dow Chemical Company, such as DOWLEX. ™ 2645 and DOWLEX ™2045G. Other commercially available linear low-density polyethylenes include Exceed 1018, Sabic Supeer 7118, Marlex 7109, Ineos LL8109, and Novapol PF0118.

[0033] Commercially available elastomers suitable for use in accordance with the embodiments disclosed herein include, for example, AFFINITY. ™ Polyolefin elastomers ™ Polyolefin elastomers and INFUSE ™ Olefin block copolymers (available from Dow Chemical Company), EXACT ™ Elastomers (available from ExxonMobil Chemicals), Tafmer (available from Mitsui), Nexlene ™ (Available from Sunkyung Chemical Co., Ltd.) and Lucene ™ (Available from LG Chem Ltd.)

[0034] Other layers

[0035] In addition to the first outer layer, the second outer layer, and the first core layer, the multilayer film may also include an additional core layer as disclosed herein.

[0036] Methods for producing multilayer films

[0037] Multilayer films can be formed via film casting or blown film processes. In some embodiments, the multilayer film is a blown film. In some embodiments, the film is an agricultural storage bag. Agricultural storage bags can be produced by a blown film process and are used for storing and preserving grains and other agricultural products. The blown film process is used by extruding molten polymer through a circular die to form a continuous plastic tube, which is then inflated to form a film. The film can then be wound onto rollers and can be transformed into agricultural storage bags of various sizes. Agricultural storage bags can be 5 feet to 12 feet in diameter and can be 200 feet to 240 feet in length.

[0038] The membranes and storage bags disclosed herein can achieve a desired balance of MD tear propagation, high puncture resistance, dart resistance, and creep. The properties and composition of the membrane according to the embodiments disclosed herein can produce a membrane and storage bag that provide excellent durability, puncture resistance, and flexibility, making them ideal for protecting stored products from environmental factors such as moisture, pests, and UV radiation. According to the embodiments disclosed herein, the multilayer membrane can have at least one of the following properties: dart impact resistance of at least 1450 g (or at least 1470 g); MD Elmandorf tear resistance of at least 4700 gf (or at least 4800 gf or at least 4900 gf); puncture elongation at break of at least 80 mm; puncture energy at break of at least 14.0 J (or at least 15.0 J); puncture force of at least 300 N (or at least 310 N); and puncture resistance of at least 7.0 J / cc (or at least 7.5 J / cc). Unbound by theory, compositions of one or more core layers having specific low amounts and types of elastomers can deliver membranes with the desired properties described herein. The compositions and membranes are suitable for recirculating steam and are formed from ethylene-based polymers.

[0039] The application of storage bags may require a balance of high MD tear propagation resistance (crucial during unloading), as well as puncture resistance (as storage bags are laid out in the field where unevenness in the soil can penetrate the bags, thus compromising the preservation conditions required for the grain) and drop resistance.

[0040] A method for producing a multilayer film according to embodiments disclosed herein includes: extruding a first outer layer, a second outer layer, and one or more core layers to form a multilayer film, wherein the one or more core layers are positioned between the first outer layer and the second outer layer; based on the total weight of the one or more core layers, the one or more core layers comprise at least 95 wt% of an ethylene polymer, at least 65 wt% of linear low-density polyethylene, less than 30 wt% of low-density polyethylene, and less than 5 wt% of a polyethylene elastomer, wherein the first core layer comprises a combination of low-density polyethylene, linear low-density polyethylene, and a polyethylene elastomer having a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s. In embodiments where the multilayer film is a blown film, the method may include extruding through a circular die to form a tube and expanding the tube to form a film.

[0041] The method can be adjusted to form a film as described herein, for example, by extruding additional layers, adding more or less polymer composition, adjusting the layer ratio, and adjusting the film thickness.

[0042] Test methods

[0043] density

[0044] Density was measured according to ASTM D792 and expressed in grams per cubic centimeter. 3 (g / cm) 3 (or g / cc) indicates.

[0045] Melt index (I2)

[0046] The melt index of low-density polyethylene and linear low-density polyethylene shall be determined following the procedure described in ASTM D1238. Method B of ASTM D1238 shall be used. Units are g / 10 min or dg / min.

[0047] pierce

[0048] The test was conducted using an Instron-5982 (load sensor: 500 N) apparatus, which punctures the membrane with a stainless steel probe until the membrane is completely punctured. The test reports the puncture energy (J), puncture force (N), puncture resistance (J / cc), elongation at break (mm), and thickness of the tested membrane. The test conforms to ASTM D-5748.

[0049] Dart Impact

[0050] The test was conducted using a Die Punch-6054-CEAST apparatus, which releases a 1350-gram standardized dart (according to ASTM D 1709) from a height of 0.66 meters (for Method A) and a 2000-gram dart from a height of 1.5 meters (for Method B). The impact is reported in grams.

[0051] Elmandorf Tear

[0052] The test was conducted in an Elmendorf-83200000 ED30-CEAST-Pro tear-81369-Thwing Albert apparatus (in accordance with ASTM D1922), which tears the membrane under test with a weighted blade. The tear resistance is reported in grams. The test was performed in both the longitudinal and transverse directions of the membrane.

[0053] Example

[0054] Materials used

[0055] The following materials are included in the embodiments discussed below.

[0056]

[0057] Films were extruded on the Dr. Collin blown film production line located at Pack Studios (Jundiai, Sao Paulo). Production line setup and processing conditions are available in Table 2. The first and second outer layers of each film were composed of 75% DOWLEX. ™ Made from TG 2085B and 25% LDPE 203M.

[0058]

[0059]

[0060]

[0061]

[0062]

Claims

1. A multilayer film comprising a first outer layer, a second outer layer, and one or more core layers positioned between the first outer layer and the second outer layer; based on the total weight of the one or more core layers, the one or more core layers comprising at least 95% by weight of an ethylene polymer, at least 65% by weight of linear low-density polyethylene, less than 30% by weight of low-density polyethylene, and less than 5% by weight of a polyethylene elastomer, wherein the first core layer comprises a combination of low-density polyethylene, linear low-density polyethylene, and a polyethylene elastomer having a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s.

2. The multilayer film according to any one of the preceding claims, wherein the linear low density of the first core layer has a density between 0.910 g / cc and 0.930 g / cc and a melt index (I2) between 0.2 g / 10 min and 5.0 g / 10 min.

3. The multilayer film according to any one of the preceding claims, wherein the low-density polyethylene of the first core layer has a density between 0.910 g / cc and 0.930 g / cc and a melt index (I2) between 0.1 g / 10 min and 7.0 g / 10 min.

4. The multilayer film according to any one of the preceding claims, wherein the polyethylene elastomer of the first core layer has a melt index (I2) greater than 500 g / 10 min.

5. The multilayer film according to any one of the preceding claims, wherein the multilayer film comprises a second core layer, the second core layer comprising a second low-density polyethylene, a second linear low-density polyethylene, and a second polyethylene elastomer having a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s.

6. The multilayer film according to any one of the preceding claims, wherein the first outer layer and the second outer layer each comprise linear low-density polyethylene and low-density polyethylene.

7. The multilayer film according to any one of the preceding claims, wherein the multilayer film comprises less than 3% by weight of polyethylene elastomer based on the total weight of the film.

8. The multilayer film according to any one of the preceding claims, wherein the multilayer film comprises at least 95% by weight of an ethylene polymer.

9. The multilayer film according to any one of the preceding claims, wherein, based on the total weight of the one or more core layers, the one or more core layers comprise 65% to 80% by weight of linear low-density polyethylene, 20% to 30% by weight of low-density polyethylene, and less than 5% by weight of polyethylene elastomer.

10. The multilayer film according to any one of the preceding claims, wherein, based on the total weight of the film, the multilayer film comprises 65% to 80% by weight of linear low-density polyethylene, 20% to 30% by weight of low-density polyethylene, and less than 3% by weight of polyethylene elastomer.

11. The multilayer film according to any one of the preceding claims, wherein the linear low-density first core layer comprises 1-octene.

12. The multilayer film according to any one of the preceding claims, wherein the multilayer film has a thickness between 180 micrometers and 260 micrometers.

13. The multilayer film according to any one of the preceding claims, wherein the one or more core layers account for at least 40% of the total thickness of the film.

14. The multilayer film according to any one of the preceding claims, wherein the multilayer film has at least one of the following properties: at least 1450 g dart impact resistance; at least 4700 gf MD Elmandorf tear resistance; at least 80 mm puncture break elongation; at least 14.0 J puncture break energy; at least 300 N puncture force; at least 7.0 J / cc puncture resistance.

15. The multilayer film according to any one of the preceding claims, wherein the film is a blown film.

16. The multilayer film according to any one of the preceding claims, wherein the film is an agricultural storage bag.

17. A method for fabricating a multilayer film, the method comprising: A first outer layer, a second outer layer, and one or more core layers are extruded to form a multilayer film, wherein the one or more core layers are positioned between the first outer layer and the second outer layer; based on the total weight of the one or more core layers, the one or more core layers comprise at least 95 wt% of an ethylene polymer, at least 65 wt% of linear low-density polyethylene, less than 30 wt% of low-density polyethylene, and less than 5 wt% of a polyethylene elastomer, wherein the first core layer comprises a combination of low-density polyethylene, linear low-density polyethylene, and a polyethylene elastomer having a density of 0.855 g / cc to 0.910 g / cc and a Brinell viscosity of less than 12.0 Pa·s.

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