Multilayer structure comprising an oriented film and a sealant layer

Abstract

According to one or more embodiments presently disclosed herein, a multilayer structure can include an oriented film and a sealant layer. The oriented film can include at least 90 wt% polyethylene. The sealant layer can include 15 wt% to 40 wt% low density polyethylene, based on the total weight of the sealant layer. The sealant layer can further include: (a) 60 wt% to 85 wt% ethylene-based elastomer, based on the total weight of the sealant layer; or (b) 60 wt% to 85 wt% propylene-based plastomer, based on the total weight of the sealant layer.

Description

[0001] Cross-references

[0002] This application claims priority to U.S. Provisional Application 63 / 124,300, filed December 11, 2020, the contents of which are hereby incorporated in their entirety. Technical Field

[0003] This disclosure generally relates to multilayer structures, and more specifically to polyolefin multilayer structures, such as those used in consumer packaging. Background Technology

[0004] Polyolefin multilayer structures have been used to manufacture many types of flexible and semi-rigid packaging for the protection of food, beverages, other liquids, personal care products, and other consumer goods. As is widely understood, such structures can be sealed under heat. Typically, a layer of sealant is used within the packaging to seal the multilayer structure together at elevated temperatures. It may be desirable to have alternative multilayer structures that can be used in packaging and offer one or more benefits. Summary of the Invention

[0005] Many multilayer structures used in packaging, such as films, are sealed by utilizing heated sealing rods that bond two films together. A sealant layer can be provided as part of this multilayer structure, which is thermally melted to form a sealing bond. Oriented polyethylene films, such as longitudinally oriented films and biaxially oriented films, have become more common and are desired for use in some packaging applications. Embodiments of this disclosure provide a sealant layer comprising a combination of low-density polyethylene and an ethylene-based elastomer, or a combination of low-density polyethylene and a propylene-based plasmon. Such sealant layers can provide a seal at a lower sealing temperature compared to conventional sealant layers. This is particularly advantageous when used with oriented films containing at least 90% by weight polyethylene, as such films have a lower melting point compared to polypropylene or polyethylene terephthalate films commonly used in packaging materials. By promoting a seal at a lower temperature, the sealant layer can provide good seal strength when used with oriented films containing at least 90% by weight polyethylene, while minimizing or avoiding degradation or other damage to the oriented film. Furthermore, in one or more embodiments, the sealant layer disclosed herein can allow for improved processing (e.g., increased processing speed under reduced motor load). According to one or more embodiments described herein, the multilayer structure disclosed in this invention can exhibit these and other advantages.

[0006] According to one or more embodiments of this disclosure, the multilayer structure may include an oriented film and a sealant layer. The oriented film may contain at least 90% by weight polyethylene. The sealant layer may be located on the oriented film. Based on the total weight of the sealant layer, the sealant layer may contain 15% to 40% by weight low-density polyethylene. Based on the total weight of the sealant layer, the sealant layer may also contain 60% to 85% by weight ethylene-based elastomer. The ethylene-based elastomer of the sealant layer may have a content of 0.870 g / cm³. 3 Up to 0.911 g / cm 3 Its density and melt index (I2) of at least 3 g / 10 min.

[0007] According to one or more further embodiments of this disclosure, the multilayer structure may include an oriented film and a sealant layer. The oriented film may contain at least 90% by weight polyethylene. The sealant layer may be located on the oriented film. Based on the total weight of the sealant layer, the sealant layer may contain 15% to 40% by weight low-density polyethylene. Based on the total weight of the sealant layer, the sealant layer may also contain 60% to 85% by weight a propylene-based plasticizer. The propylene-based plasticizer may have a density of 0.890 g / cm³. 3 Or a lower density and a melt flow rate of at least 8 g / 10 min (at 230 °C and 2.16 kg).

[0008] These and other embodiments are described in more detail in the detailed description. It should be understood that both the foregoing general description and the following detailed description present embodiments of the present technology and are intended to provide an overview or framework for understanding the nature and features of the claimed technology. Drawings are included to provide further understanding of the technology, and these drawings are incorporated in and form part of this specification. The drawings illustrate various embodiments and, together with the description, serve to explain the principles and operation of the technology. Furthermore, the drawings and description are intended to be illustrative only and are not intended to limit the scope of the claims in any way. Attached Figure Description

[0009] The following detailed description of specific embodiments of this disclosure is best understood in conjunction with the following drawings, in which similar reference numerals indicate similar structures and in the drawings:

[0010] Figure 1 The sealing strength of one or more exemplary embodiments according to this disclosure is depicted graphically; and

[0011] Figure 2 The thermal adhesion strength of one or more exemplary embodiments according to this disclosure is depicted graphically. Detailed Implementation

[0012] Reference will now be made in more detail to various embodiments that are examples of the claimed subject matter. It should be understood that the multi-layered structural features described in the detailed embodiments should not be construed as a limitation on the claimed embodiments unless expressly stated otherwise.

[0013] According to one or more embodiments, this document describes a multilayered structure comprising an oriented membrane and a sealant layer. In some embodiments, the sealant layer may comprise low-density polyethylene and a propylene-based plasmon. In other embodiments, the sealant layer may comprise low-density polyethylene and an ethylene-based elastomer. As used herein, “multilayer structure” means any structure having more than one layer. For example, a multilayer structure (e.g., a membrane) may have two, three, four, five, or more layers. A multilayer structure may be described as having layers represented by letters. For example, a three-layer structure having a core layer B and two outer layers A and C may be designated as A / B / C. Similarly, a structure having two core layers B and C and two outer layers A and D may be designated as A / B / C / D.

[0014] According to one or more embodiments, the multilayer structure may include an oriented membrane. As described herein, an "oriented" membrane is one formed by stretching a membrane in any direction. Embodiments of oriented membranes include longitudinally oriented membranes and biaxially oriented membranes.

[0015] According to one or more embodiments, a multilayer structure may include a longitudinally oriented membrane. As described herein, a "longitudinally oriented" membrane is one formed by uniaxially stretching the membrane in the longitudinal direction. For example, the membrane may be heated and uniaxially stretched in the longitudinal direction on a series of rollers. As used herein, the term "longitudinal" refers to the length of the membrane in its production direction. Compared to membranes that have not undergone a longitudinal orientation process, longitudinally oriented membranes may exhibit improved tensile properties.

[0016] According to another embodiment, the multilayer structure may include a biaxially oriented film. As described herein, a “biaxially oriented” film is formed by biaxially stretching the film in a longitudinal and cross or transverse direction to improve physical and / or barrier properties. For example, the film may be heated and biaxially stretched on a series of rollers in both the longitudinal and transverse directions. As used herein, the term “longitudinal” refers to the length of the film in its production direction. The terms “cross direction” or “transverse direction” or “cross-direction” refer to the width of the film, i.e., in a direction substantially perpendicular to the longitudinal direction. Compared to films that have not undergone a biaxially oriented process, biaxially oriented films can exhibit improved tensile properties.

[0017] As described herein, a “membrane” generally comprises any continuous layer containing a polyolefin material, which typically has a large aspect ratio. In one or more embodiments, the membrane may comprise one or more olefin-based polymers. As used herein, the terms “olefin-based polymer,” “olefin-like polymer,” and “polyolefin” refer to a polymer that comprises a majority amount of olefin monomers, such as ethylene or propylene (based on the polymer’s weight), in polymeric form and may optionally comprise one or more comonomers. The term “polymer” refers to a polymeric compound prepared by polymerizing monomers (whether of the same or different types). Thus, the general term polymer encompasses the term “homopolymer,” which is generally used to refer to polymers prepared from only one type of monomer, and the term “copolymer,” which refers to polymers prepared from two or more different monomers. The membranes described herein may be multilayer membranes comprising more than one layer.

[0018] In one or more embodiments, the oriented film may comprise at least 90% by weight polyethylene. In other embodiments, the oriented film may comprise at least 95% by weight, at least 98% by weight, at least 99% by weight, or even at least 99.5% by weight polyethylene. It should be understood that the oriented film may be, for example, a single layer of a blended polymer wherein at least 90% by weight is polyethylene, or it may be multilayered, wherein some layers are not polyethylene, but the combination of layers comprises at least 90% by weight polyethylene. In one or more embodiments, the material of the oriented film closest to the sealant layer may comprise polyethylene.

[0019] As described herein, “polyethylene” or “ethylene-based polymer” means a polymer comprising more than 50 mol% of units derived from ethylene monomers. This includes ethylene-based homopolymers or copolymers (meaning units derived from two or more comonomers). Forms of polyethylene include, but are not limited to, low-density polyethylene (LDPE); linear low-density polyethylene (LLDPE); ultra-low-density polyethylene (ULDPE); very low-density polyethylene (VLDPE); single-point catalytic linear low-density polyethylene, including linear and substantially linear low-density resins (m-LLDPE); medium-density polyethylene (MDPE); and high-density polyethylene (HDPE).

[0020] Additionally, as described herein, the term "LDPE" can also be referred to as "high-pressure ethylene polymer" or "highly branched polyethylene," and is defined to mean that the polymer can be partially or completely homopolymerized or copolymerized in an autoclave or tubular reactor at pressures above 14,500 psi (100 MPa) using a free radical initiator (such as a peroxide) (see, for example, US 4,599,392, which is hereby incorporated by reference). LDPE resins typically have densities ranging from 0.916 g / cm³ to 0.940 g / cm³.

[0021] As described herein, the term "LLDPE" can include resins made using Ziegler-Natta catalyst systems, as well as resins made using mono-site catalysts, including but not limited to bismetallocene catalysts (sometimes referred to as "m-LLDPE"), phosphine imides, and catalysts with defined geometries; and resins made using post-metallocene, molecular catalysts, including but not limited to bis(biphenylphenoxy) catalysts (also referred to as polyaryloxy ether catalysts). LLDPE includes linear, substantially linear, or heterogeneous ethylene-based copolymers or homopolymers. LLDPE contains fewer long-chain branchings than LDPE and includes: substantially linear ethylene polymers, further defined in U.S. Patent Nos. 5,272,236, 5,278,272, 5,582,923, and 5,733,155; homogeneous branched ethylene polymers, such as those in U.S. Patent No. 3,645,992; heterogeneous branched ethylene polymers, such as those prepared according to the method disclosed in U.S. Patent No. 4,076,698; and blends thereof (such as those disclosed in U.S. Patent Nos. 3,914,342 or 5,854,045). LLDPE resins can be prepared via gas-phase, solution-phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art. LLDPE resins can be prepared by gas-phase, solution-phase, or slurry polymerization or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0022] The term “ULDPE” is defined as a polyethylene-based copolymer having a density in the range of 0.895 g / cc to 0.915 g / cc.

[0023] The term "MDPE" refers to polyethylene with a density of 0.926 g / cc to 0.935 g / cc. MDPE is typically prepared using chromium or Ziegler-Natta catalysts or using single-point catalysts (including, but not limited to, bis-metallocene catalysts and catalysts with defined geometries).

[0024] The term "MDPE" refers to polyethylene with a density of 0.926 g / cc to 0.935 g / cc. MDPE is typically prepared using chromium or Ziegler-Natta catalysts or using single-point catalysts (including, but not limited to, bis-metallocene catalysts and catalysts with defined geometries).

[0025] Additionally, as described herein, the term "HDPE" refers to polyethylene with a density of approximately 0.940 g / cm or greater, which is typically prepared using Ziegler-Natta catalysts, chromium catalysts, or even metallocene catalysts.

[0026] According to one or more embodiments, the oriented film can have a melting point of less than or equal to 150°C, such as less than or equal to 145°C, or even less than or equal to 140°C, and for example, at least 120°C. This is in contrast to other films that can have higher melting points. For example, polypropylene films can have melting points greater than 150°C, and polyethylene terephthalate films can have melting points greater than 250°C.

[0027] It should be understood that the oriented films described herein are not particularly limited by their manufacturing method or source. Those skilled in the art are generally familiar with oriented films, many of which are commercially available. As will be understood by those skilled in the art, a particular oriented film can be selected based on the intended use of the multilayer structure.

[0028] It should be understood that any layer of the membrane may additionally contain one or more additives known to those skilled in the art, such as, for example, plasticizers, stabilizers (including viscosity stabilizers, hydrolytic stabilizers), primary and secondary antioxidants, UV absorbers, antistatic agents, dyes, pigments or other colorants, inorganic fillers, flame retardants, lubricants, reinforcing agents (glass fibers and glass sheets), synthetic (e.g., aramid) fibers or pulp, foaming or bubbling agents, processing aids, slip additives, anti-caking agents (such as silica or talc), release agents, tackifying resins, or combinations of two or more of these. Inorganic fillers, such as calcium carbonate, may also be incorporated into one or more of the first, second, third, and combinations thereof. In some embodiments, the surface layer, subsurface layer, connecting layer, barrier layer, and combination may each include up to 5% by weight of such additional additives based on the total weight of the respective layers. This document includes and discloses all individual values ​​and sub-ranges from 0 wt% to 5 wt%; for example, based on the total weight of the corresponding layer, the total amount of additive in any layer can be 0.5 wt% to 5 wt%, 0.5 wt% to 4 wt%, 0.5 wt% to 3 wt%, 0.5 wt% to 2 wt%, 0.5 wt% to 1 wt%, 1 wt% to 5 wt%, 1 wt% to 4 wt%, 1 wt% to 3 wt%, 1 wt% to 2 wt%, 2 wt% to 5 wt%, 2 wt% to 4 wt%, 2 wt% to 3 wt%, 3 wt% to 5 wt%, 3 wt% to 4 wt%, or 4 wt% to 5 wt%. The incorporation of additives can be carried out by any known method, such as by dry blending, by extruding mixtures of various components, by conventional masterbatch techniques, etc.

[0029] The multilayer structure disclosed herein can have various thicknesses. The thickness of the multilayer structure can depend on many factors, including, for example, the number of layers in the multilayer structure, the composition of the layers in the multilayer structure, the desired properties of the multilayer structure, the desired end-use application of the multilayer structure, and the manufacturing process of the multilayer structure. In embodiments, the multilayer structure can have a thickness of less than 205 micrometers (μm or micrometer). In the implementation, the thickness of the multilayer structure can be 15μm to 205μm, 20μm to 180μm, 15μm to 180μm, 15μm to 160μm, 15μm to 140μm, 15μm to 120μm, 15μm to 100μm, 15μm to 80μm, 15μm to 60μm, 15μm to 40μm, 20μm to 160μm, 20μm to 140μm, 20μm to 120μm, 20μm to 100μm, 20μm to 80μm, 20μm to 60μm, or 20μm to 40μm.

[0030] Multilayer structures may also include a sealant layer. The sealant layer is typically heated and pressurized to seal the two multilayer structures together. The sealant layer may be positioned on the alignment film. As described herein, "positioned on" the alignment film means either in direct contact with the alignment film or minimally separated from it, such as by a bonding layer. As described herein, a "bonding layer" means a polymer layer positioned between and in direct contact with the two polymer layers. Bonding layers typically facilitate adhesion between the two polymer layers they contact. When a bonding layer is absent, the sealant layer may adherently contact the alignment film. The term "adhesive contact" and similar terms mean that one surface of one layer touches and adheres to another surface of another layer, such that one layer cannot be removed from the other without damaging the interlayer surfaces (i.e., contact surfaces) of the two layers.

[0031] In one or more embodiments, the sealant layer can be extruded onto the oriented film. As described herein and as known to those skilled in the art, the sealant layer can be extruded onto the longitudinally oriented polyethylene film by extruding a molten component of the sealant layer through a die to achieve a desired layer thickness. Extrusion coating is generally known to those skilled in the art and typically involves coating a molten web of polymeric material onto a substrate material, usually at elevated temperatures. If a bonding layer is present, the bonding layer can be directly extruded onto the oriented film, and the sealant layer can be extruded onto the bonding layer.

[0032] In one or more embodiments, the sealant layer may comprise 15 wt% to 40 wt% of low-density polyethylene based on the total weight of the sealant layer. For example, the sealant layer may comprise 15 wt% to 20 wt%, 20 wt% to 25 wt%, 25 wt% to 30 wt%, 30 wt% to 35 wt%, 35 wt% to 40 wt%, or any combination of these ranges of low-density polyethylene based on the total weight of the sealant layer. In another embodiment, the sealant layer may comprise 15 wt% to 30 wt% of low-density polyethylene based on the total weight of the sealant layer.

[0033] In one or more embodiments, the low-density polyethylene of the sealant layer may have a molecular weight distribution (Mw / Mn) of 7 to 13. For example, the low-density polyethylene of the sealant layer may have a molecular weight distribution of 7 to 8, 8 to 9, 9 to 10, 10 to 11, 11 to 12, 12 to 13, or any combination of these ranges. As used herein, the molecular weight distribution (MWD) of a polymer is defined as the quotient Mw / Mn, where Mw is the weight-average molecular weight of the polymer and Mn is the number-average molecular weight of the polymer.

[0034] In one or more embodiments, the low-density polyethylene of the sealant layer may have a melt index (I2) of 1.5 to 9. For example, the low-density polyethylene of the sealant layer may have a melt index of 1.5 to 2, 2 to 2.5, 2.5 to 3, 3 to 3.5, 3.5 to 4, 4 to 4.5, 4.5 to 5, 5 to 5.5, 5.5 to 6, 6 to 6.5, 6.5 to 7, 7 to 7.5, 7.5 to 8, 8 to 8.5, 8.5 to 9, or any combination of these ranges. For example, the low-density polyethylene of the sealant layer may have a melt index of about 2.3. As used herein, the melt index (I2) is a measure of the melt flow rate of the polymer as measured by ASTM D1238 at a temperature of 190°C and a load of 2.16 kg.

[0035] In one or more embodiments, the low-density polyethylene of the sealant layer may be selected from polyethylene with a density of 0.918 g / cm³. 3 DOW LDPE 770G (commercially available from Dow Chemical Company) with a melt index of 2.3 g / 10 min and a melting point of 110 °C, or a density of 0.918 g / cm³. 3 The AGILITY EC 7220 Performance LDPE with a melt index of 1.5 g / 10 min is commercially available from Dow Chemical Company. However, other LDPEs are intended for use in sealant layers, and the embodiments described herein are not limited to those including these polymers.

[0036] In some embodiments, in addition to low-density polyethylene, the sealant layer may also comprise a propylene-based plastomer. In one or more embodiments described herein, "propylene-based plastomer" can refer to a semi-crystalline copolymer of propylene and ethylene comprising more than 70% by weight of polypropylene containing a semi-crystalline isotactic stereochemistry. The propylene-based plastomer may have a density range of 0.888 g / cc to 0.858 g / cc and / or a glass transition temperature of -15°C to -35°C. The propylene-based plastomers described herein include propylene-based copolymers of propylene and α-olefin comonomers such as ethylene, butene, pentene, 4-methyl-1-pentene, hexene, heptene, octene, or nonene (meaning units derived from two or more comonomers). A plastomer is generally understood as a polymeric material combining the qualities of an elastomer and a plastic.

[0037] In one or more embodiments, the sealant layer may contain 60% to 85% by weight of a propylene-based plasticizer, based on the total weight of the sealant layer. For example, the sealant layer may contain 60% to 65% by weight, 65% to 70% by weight, 70% to 75% by weight, 75% to 80% by weight, 80% to 85% by weight, or any combination of these ranges of a propylene-based plasticizer, based on the total weight of the sealant layer.

[0038] According to one or more embodiments, the propylene-based plastide can have a density of 0.890 g / cm³. 3 Or even lower densities. For example, propylene-based plastides can have a density of 0.860 g / cm³. 3 Up to 0.890 g / cm 3 Such as 0.860 g / cm 3 Up to 0.865 g / cm 3 0.865g / cm 3 Up to 0.870 g / cm 3 0.870 g / cm 3 Up to 0.875 g / cm 3 0.875g / cm 3 Up to 0.880 g / cm 3 0.880 g / cm 3 Up to 0.885 g / cm 3 0.885g / cm 3 Up to 0.890 g / cm 3 Or the density of any combination of these ranges.

[0039] In one or more embodiments, the propylene-based plastomer may have a melt flow rate of at least 5 g / 10 min (at 230 °C and 2.16 kg). For example, the propylene-based plastomer may have a melt flow rate of 5 g / 10 min to 35 g / 10 min, such as 5 g / 10 min to 10 g / 10 min, 10 g / 10 min to 15 g / 10 min, 15 g / 10 min to 20 g / 10 min, 20 g / 10 min to 25 g / 10 min, 25 g / 10 min to 30 g / 10 min, 30 g / 10 min to 35 g / 10 min, or any combination of these ranges (at 230 °C and 2.16 kg). As described herein, the melt flow rate is measured according to ASTM D 1238-10, condition 230 °C / 2.16 kg, and reported in grams eluted per 10 minutes.

[0040] In one or more embodiments, the propylene-based plastide may have a melt flow rate of 20 g / 10 min to 30 g / 10 min. For example, the propylene-based plastide may have a melt flow rate of 20 g / 10 min to 22 g / 10 min, 22 g / 10 min to 24 g / 10 min, 24 g / 10 min to 26 g / 10 min, 26 g / 10 min to 28 g / 10 min, 28 g / 10 min to 30 g / 10 min, or any combination of these ranges. In one or more embodiments, the crystallinity of the propylene-based plastide may be 12% to 30%, and / or the glass transition temperature may be -15°C to 35°C.

[0041] In one or more embodiments, the propylene-based plastic body may have a melting point of 60°C to 120°C. For example, the propylene-based plastic body may have a melting point of 60°C to 80°C, 80°C to 100°C, 100°C to 120°C, or any combination of these ranges.

[0042] In one or more embodiments, the propylene-based plastic body may be a copolymer comprising propylene and ethylene units. According to one or more embodiments, the propylene-based plastic body may have an ethylene content of 2% to 15% by weight. For example, the propylene-based plastic body may have an ethylene content of 2% to 4% by weight, 4% to 6% by weight, 6% to 8% by weight, 8% to 10% by weight, 10% to 12% by weight, 12% to 15% by weight, or any combination of these ranges.

[0043] In one or more embodiments, the propylene-based plastide may be VERSIFY 4200 plastide (commercially available from Dow Chemical Company) having a content of 0.876 g / cm³. 3The density, melt flow rate of 25 g / 10 min, and melting point of 100 °C are described. However, other propylene-based plastomers are intended for use in sealant layers, and the embodiments described herein are not limited to those including these polymers.

[0044] In some embodiments, in addition to low-density polyethylene, the sealant layer may also comprise an ethylene-based elastomer. As described herein, "ethylene-based elastomer" means an elastomer containing more than 50 mol% of units derived from ethylene monomers. This includes ethylene-based α-olefin copolymers (meaning units derived from two or more comonomers) having a density of 0.870 g / cc to 0.911 g / cc. Elastomers can generally be understood as polymeric materials exhibiting viscoelasticity (i.e., those that exhibit both viscous and elastic properties when subjected to deformation).

[0045] According to one or more embodiments, the sealant layer may contain 60% to 85% by weight of an ethylene-based elastomer, based on the total weight of the sealant layer. For example, the sealant layer may contain 60% to 65% by weight, 65% to 70% by weight, 70% to 75% by weight, 75% to 80% by weight, 80% to 85% by weight, or any combination of these ranges of an ethylene-based elastomer, based on the total weight of the sealant layer.

[0046] In one or more embodiments, the ethylene-based elastomer may have a content of 0.87 g / cm³. 3 Up to 0.911 g / cm 3 The density. For example, ethylene-based elastomers can have a density of 0.87 g / cm³. 3 Up to 0.875 g / cm 3 0.875g / cm 3 Up to 0.88 g / cm 3 0.88g / cm 3 Up to 0.885 g / cm 3 0.885g / cm 3 Up to 0.90 g / cm 3 0.90g / cm 3 Up to 0.905 g / cm 3 0.905g / cm 3 Up to 0.911 g / cm 3 Or the density of any combination of these ranges.

[0047] In one or more embodiments, the ethylene-based elastomer may have a melt index of at least 3 g / 10 min, such as 3 g / 10 min to 30 g / 10 min. For example, ethylene-based elastomers may have melt indices of 3 g / 10 min to 5 g / 10 min, 5 g / 10 min to 7.5 g / 10 min, 7.5 g / 10 min to 10 g / 10 min, 10 g / 10 min to 12.5 g / 10 min, 12.5 g / 10 min to 15 g / 10 min, 15 g / 10 min to 17.5 g / 10 min, 17.5 g / 10 min to 20 g / 10 min, 20 g / 10 min to 22.5 g / 10 min, 22.5 g / 10 min to 25 g / 10 min, 25 g / 10 min to 27.5 g / 10 min, 27.5 g / 10 min to 30 g / 10 min, or any combination of these ranges.

[0048] In one or more embodiments, the ethylene-based elastomer may have a melting point of 65°C to 100°C. For example, the ethylene-based elastomer may have a melting point of 65°C to 70°C, 70°C to 75°C, 75°C to 80°C, 80°C to 85°C, 85°C to 90°C, 90°C to 95°C, 95°C to 100°C, or any combination of these ranges.

[0049] In one or more embodiments, the ethylene-based elastomer of the sealant layer may be selected from those with a density of 0.885 g / cm³. 3 Furthermore, ENGAGE 8401 (commercially available from Dow Chemical Company) with a melt index of 30 g / 10 min, or a density of 0.88 g / cm³, is required. 3 Furthermore, ENGAGE 8411 (commercially available from Dow Chemical Company) with a melt index of 18 g / 10 min is used. However, other ethylene-based elastomers are intended for use in sealant layers, and the embodiments described herein are not limited to those including these polymers.

[0050] In one or more embodiments, the combination of low-density polyethylene and propylene-based plasticizer may constitute at least 90% by weight of the sealant layer. In other embodiments, the combination of low-density polyethylene and propylene-based plasticizer may constitute at least 92% by weight, at least 94% by weight, at least 96% by weight, at least 98% by weight, at least 99% by weight, at least 99.5% by weight, or 100% by weight of the sealant layer.

[0051] In one or more embodiments, the combination of low-density polyethylene and ethylene-based elastomer may comprise at least 90% by weight of the sealant layer. In other embodiments, the combination of low-density polyethylene and ethylene-based elastomer may comprise at least 92%, at least 94%, at least 96%, at least 98%, at least 99%, at least 99.5%, or 100% by weight of the sealant layer.

[0052] As described herein, the multilayer structure may include a bonding layer. The bonding layer can provide adhesion between the oriented polyethylene film and a propylene-based plastisol sealant, such that the bonding layer can be positioned in contact with the sealant layer and the oriented film and located between the sealant layer and the oriented film. In one or more embodiments, the bonding layer may comprise polyethylene having a content of 0.923 g / cm³. 3 And / or lower density and melt index (I2) of at least 4 g / 10 min. The connecting layer may contain at least 60 wt% polyethylene, such as at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% polyethylene, which has a melt index (I2) of 0.923 g / cm³. 3 Or a lower density and a melt index (I2) of at least 4 g / 10 min. In one or more embodiments, such polyethylene may have a density of 0.923 g / cm³. 3 Or smaller, such as 0.900 to 0.905, 0.905 to 0.910, 0.910 to 0.915, 0.915 to 0.920, 0.920 to 0.923, or any combination of these ranges. In one or more embodiments, the connecting layer may have a melt index (I2) of at least 4 g / 10 min, such as at least 6 g / 10 min, at least 8 g / 10 min, at least 10 g / 10 min, at least 12 g / 10 min, at least 14 g / 10 min, at least 16 g / 10 min, at least 18 g / 10 min, or even at least 20 g / 10 min.

[0053] According to the embodiments described herein, a bonding layer may be particularly desirable when the sealant layer comprises a propylene-based plasticizer, thereby achieving good adhesion between the sealant layer and the outer polyethylene film layer. A bonding layer may be desirable in systems where the propylene and ethylene layers will be in direct contact with each other without the use of a bonding layer.

[0054] According to another embodiment, the connecting layer may contain at least 15% by weight of low-density polyethylene, based on the total weight of the connecting layer. For example, the connecting layer may contain at least 20% by weight, at least 25% by weight, at least 30% by weight, at least 35% by weight, at least 40% by weight, at least 45% by weight, or even at least 50% by weight of low-density polyethylene. The low-density polyethylene in the connecting layer may have similar or identical properties and characteristics to those disclosed regarding the low-density polyethylene of the sealant layer. For example, 70% by weight of ELITE... TM 5860 or AFFINITY TM 1451 with 30% by weight of DOW TM Blends of LDPE 770G or 7220 can be used as bonding layers.

[0055] Embodiments of this disclosure also relate to articles of manufacture, such as packaging, formed from the multilayer structures of this disclosure. Such packaging can be formed from any multilayer structure described herein. Examples of such articles of manufacture may include flexible packaging, bags, stand-up pouches, and prefabricated packaging or bags. Various methods for producing articles of manufacture from the multilayer films disclosed herein are well known to those skilled in the art.

[0056] 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 otherwise, all compositions claimed using the term “comprising” may include any additional additives, adjuvants, or compounds, whether polymerized 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 ingredients, steps, or procedures not specifically described or listed.

[0057] The terms “blend,” “polymer blend,” and similar terms mean a composition of two or more polymers. Such blends may or may not be miscible. Such blends may or may not be phase-separated. As determined by transmission electron spectroscopy, light scattering, X-ray scattering, and any other method known in the art, such blends may or may not contain one or more domain configurations. Blends are not laminates, but one or more layers of a laminate may contain blends. Such blends can be prepared as dry blends, in-situ formed (e.g., in a reactor), melt blends, or using other techniques known to those skilled in the art.

[0058] It is obvious that modifications and variations are possible without departing from the scope of this disclosure as defined in the appended claims. More specifically, although some aspects of this disclosure are identified herein as preferred or particularly advantageous, this disclosure is not necessarily limited to these aspects.

[0059] Example

[0060] Several embodiments are provided for one or more currently disclosed implementations.

[0061] Extrude the sealant layer onto the kraft paper (60g / m²). 2 All sealant layers were extruded at 290°C with a 250mm air gap and a 0.6mm die gap. The nip-off set was -15mm. The extrusion unit consisted of a DavisStandard ER-WE-PA (Maschinenfabrik Erkrath Nr. 7237) extrusion coating line with an EBR (edge ​​bead removal) flat, 1050mm wide slit die, equipped with a feed block co-extrusion system and an extruder with a polymer output of up to 350kg / h. For these evaluations, a single-groove feed block and the largest extruder "A" with an ET Barr 3.5" twin-thread compression screw L / D 32 were used. The molten polymer was coated onto a paper or film substrate and cooled by cooling rollers (cooling roller temperature 15°C).

[0062] Table 1 provides the various sealant layer compositions tested. All polymers tested in the sealant layers and identified in Table 1 are commercially available from Dow Chemical Company. Table 1 also provides reference numerals corresponding to the accompanying drawings. Table 2 provides information on the polymers used in the sealant layers.

[0063] Table 1 - Sealant layers tested

[0064]

[0065] Table 2 - Selected properties of the sealant layer materials tested

[0066]

[0067] Figure 1 The sealing strength (N / 15mm) as a function of sealing temperature (°C) is shown. As depicted, generally speaking, samples 1-3 have a greater sealing strength relative to temperature compared to the comparative examples tested. Additionally, Figure 2Hot tack data are shown, where samples 1-3 provide better hot tack strength at lower sealing temperatures (e.g., less than 80°C). It should be noted that samples 1 and 3 represent sealant layers comprising low-density polyethylene and an ethylene-based elastomer, as described in the specific embodiments. Sample 2 represents a sealant layer comprising low-density polyethylene and a propylene-based plasticizer. The increased sealing strength and hot tack strength at lower temperatures are desirable and indicate lower heat-sealing and hot tack initiation temperatures. Samples 1-3 also exhibit greater overall sealing strength at all temperatures compared to the comparative examples.

[0068] The processability of the samples was also analyzed. Table 3 shows the necking and draw rates of the test samples. Necking is the shrinkage of the polymer film between the die exit and the coating substrate (i.e., during the air gap) and is considered a waste of material. Draw refers to how fast the coating line can run and how thin the polymer film can be stretched. Good polymers for extrusion coating should have low necking (to minimize polymer waste) and high / sufficient draw (to obtain thin coatings and high throughput). As shown, samples 1-3 have acceptable and, in many cases, excellent necking and draw rates compared to other sealant materials.

[0069] Table 3

[0070]

[0071] The motor load was also analyzed, as shown in Table 4. Additionally, the melt pressure was analyzed and is shown in Table 5. Compared to other sealant materials, Samples 1-3 exhibit acceptable and, in many cases, excellent required motor loads. This is the desired processing characteristic.

[0072] Table 4 - Motor Load

[0073]

[0074] Table 5 - Melt Pressure

[0075]

[0076] The data on the initiation temperature of the hot tack strength were collected and are shown in Table 6. For these tests, the extruder set temperature was 290°C and the temperature was 100 m / min. 2 The coating weight is used to coat the sample onto the paper.

[0077] Table 5 - Thermal Adhesion

[0078]

[0079] Test methods

[0080] Unless otherwise specified, the following test methods shall be used to measure the corresponding properties shown below:

[0081] density

[0082] Samples for density measurement were prepared according to ASTM D1928. The polymer sample was pressed for three minutes at 190°C and 30,000 psi, followed by one minute at 21°C and 207 MPa. Measurements were performed using ASTM D792 Method B within one hour of sample pressing.

[0083] Melting point

[0084] Melting point (Tm) was determined using differential scanning calorimetry (DSC). The DSC was performed on a TA Instruments Q1000 DSC equipped with an RCS cooling accessory and an autosampler. The melting point (Tm) of the sample was measured according to ASTM D3418.

[0085] Melt index

[0086] Measure the melt index or I2 (g / 10min or dg / min) according to ASTM D 1238, conditions 190℃ / 2.16kg (for polyethylene) and 230℃ / 2.16kg (for polypropylene).

[0087] Heat seal measurement

[0088] Samples were sealed using a Kopp Heat Sealer within a standard temperature range of 60°C to 160°C. The sealing time was set to 0.5 seconds. The set pressure of the heat-sealing rod was 0.5 N / mm². 2 .

[0089] The heat-sealed membrane was measured on a commercial tensile testing machine according to ASTM F-88 (Technical A). The sample was a 15 mm wide die-cut strip. The sample was cut longitudinally; therefore, the actual interface was formed by the fused sealant material in the intersecting directions. The test result is the force required to pull apart the fused interface, or the force that would cause the membrane to rupture if it broke before the heat-sealed interface separated.

[0090] Sealing strength is related to opening force and packaging integrity. Before cutting, the film is conditioned for at least 40 hours at 23°C (+2°C) and 50% (+5%) RH (relative humidity) according to ASTM D-618 (Program A). Sealing strength is measured by pulling apart the fused interface using a Zwick Tensile Tester at a crosshead speed of 100 mm / min.

[0091] The heat-sealing initiation temperature is the minimum sealing temperature required to form a seal of significant strength, which in this case is 4 N / 15 mm. In the Kopp Heat Sealer, it is 0.5 N / mm. 2 The sealing was performed under pressure with a dwell time of 0.5 seconds. Tension was measured using a Zwick Tensile Tester with a crosshead speed of 100 mm / min.

[0092] Hot bonding

[0093] "Hot tack strength" and similar terms refer to the strength of a heat seal formed between the thermoplastic surfaces of a flexible web immediately after it is formed and before it cools to ambient temperature. In molding-fill operations, the sealed area of ​​a package is often subjected to destructive forces while still hot. If the heat seal is not sufficiently resistant to these forces, it may break during packaging. Hot tack strength is measured using a Hot Tack Tester "J&B" 3000. Hot tack strength, also known as heat seal strength, is a measure of a material's ability to perform in quality-critical commercial applications. In the measurement, the sample is cut into 1-inch strips longitudinally and tested using a standard hot tack profile from 80°C to 160°C (in 5°C increments up to 120°C and above, in 10°C increments up to 160°C). Teflon-coated clamps are standard, but metal clamps can also be used. The dwell time is 0.5 seconds, and the cooling time is 0.2 seconds. The seal is then pulled open at a speed of 200 mm / sec, and the peel strength is recorded.

[0094] The thermal tack initiation temperature is the temperature at which the thermal tack strength reaches at least a given threshold strength. For example, in some cases, the thermal tack initiation temperature is determined to be 1.5 N / 15 mm.

[0095] Gel permeation chromatography (GPC)

[0096] The chromatographic system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) connected to a Precision Detector (now an Agilent Technologies 2040 2-angle laser scattering (LS) detector. A 15-degree angle was used for all light scattering measurements. The autosampler oven chamber was set to 160°C, and the column chamber to 150°C. Four Agilent "Mixed A" 30 cm 20 μm linear mixed-bed columns were used. The chromatographic solvent was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen injection. The injection volume was 200 μL, and the flow rate was 1.0 mL / min.

[0097] The GPC column assembly was calibrated using 21 polystyrene standards with narrow molecular weight distributions, ranging from 580 to 8,400,000, arranged in six “cocktail” mixtures, with individual molecular weights spaced at least tenfold apart. The standards were purchased from Agilent Technologies. For molecular weights equal to or greater than 1,000,000, 0.025 g of polystyrene standard was prepared in 50 mL of solvent; for molecular weights less than 1,000,000, 0.05 g of polystyrene standard was prepared in 50 mL of solvent. The polystyrene standards were dissolved at 80°C and gently stirred for 30 minutes. The peak molecular weights of the polystyrene standards were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, *Journal of Polymer Science and Polymer Letters*, 6, 621 (1968)).

[0098] M 聚乙烯 =A×(M) 聚苯乙烯 ) B (Equation 1)

[0099] Where M is the molecular weight, A has a value of 0.4315, and B equals 1.0.

[0100] A fifth-order polynomial was used to fit the calibration point for the corresponding polyethylene equivalent. Small adjustments were made to A (from approximately 0.415 to 0.44) to correct for column resolution and band broadening effects, resulting in NIST standard NBS 1475 at 52,000 Mw.

[0101] Plate counting was performed on the GPC column assembly using eicosane (prepared in 50 mL of TCB at 0.04 g and dissolved under slow stirring for 20 min). Plate counts (Equation 2) and symmetry (Equation 3) were measured at 200 μL injections according to the following equations:

[0102]

[0103] Where RV is the retention volume in milliliters, peak width is in milliliters, peak maximum is the maximum height of the peak, and 1 / 2 height is 1 / 2 the height of the peak maximum.

[0104]

[0105] Where RV is the retention volume in milliliters, and peak width is in milliliters, peak maximum is the position of the peak value, one-tenth height is 1 / 10 of the height of the peak maximum, and a subsequent peak refers to the tail of a peak whose retention volume is later than the peak maximum, while a preceding peak refers to the front of a peak whose retention volume is earlier than the peak maximum. The plate count of the chromatographic system should be greater than 24,000, and the symmetry should be between 0.98 and 1.22.

[0106] Samples were prepared semi-automatically using PolymerChar "Instrument Control" software, with a target sample weight of 2 mg / ml. Solvent (containing 200 ppm BHT) was added to a pre-bubbled, diaphragm-capped vial using a PolymerChar high-temperature autosampler. The sample was then dissolved at 160°C for 2 hours with "low-speed" shaking.

[0107] Based on the GPC results, using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph, according to Equations 4-6, the PolymerChar GPCOne was used. TM The software calculates the Mn content based on the baseline-subtracted IR chromatograms at each equidistant data collection point (i) and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve at point (i) according to Equation 1. (GPC) Mw (GPC) and Mz (GPC) The calculation.

[0108]

[0109]

[0110]

[0111] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate (nominal flow rate) for each sample by comparing the RV (RV(FM sample)) of the corresponding decane peak within the sample with the RV (RV(FM calibrated)) of the decane peak within the narrow standard calibration. It was then assumed that any variation in the decane marker peak time was linearly related to the flow rate (effective flow rate) throughout the run. To achieve the highest accuracy in the RV measurement of the flow marker peak, a least-squares fitting procedure was used to fit the peak values ​​of the flow marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation was then used to solve for the true peak position. After calibration based on the flow marker peak, the effective flow rate (relative to the narrow standard calibration) was calculated according to Equation 7. (via PolymerChar GPCOne) TM The software processes the flow marker peaks. Acceptable flow rate correction ensures that the effective flow rate is within + / - 2% of the nominal flow rate.

[0112] Flow rate (effective) = Flow rate (nominal) * (RV (FM calibration) / RV (FM sample)) (Equation 7)

[0113] The systematic method for determining multi-detector offset was performed in a manner consistent with that published by Balke, Mourey et al. (Mourey and Balke, Chromatography Polym., Chapter 12, (1992)) (Balke, Thitiratsakul, Lew, Cheung, and Mourey, Chromatography Polym., Chapter 13, (1992)), using PolymerChar GPCOne. TM The software optimizes the triple detector logarithmic (MW and IV) results from wide homopolymer polyethylene standards (Mw / Mn>3) with the narrow standard column calibration results from the narrow standard calibration curve.

[0114] Absolute molecular weight data were obtained using PolymerChar GPCOne. TMThe software was obtained in a manner consistent with the following publications: Zimm (Zimm, BH, *Chem. Phys.*, 16, 1099 (1948)) and Kratochvil (Kratochvil, P., *Classical Light Scattering from Polymer Solutions*, Elsevier, Oxford, NY (1987)). The total injection concentration used for determining the molecular weight was obtained from the mass detector area and the mass detector constant, which was derived from one of suitable linear polyethylene homopolymers or polyethylene standards with known weight-average molecular weights. The calculated molecular weight (using GPCOne) was... TM The light scattering constant and refractive index concentration coefficient dn / dc of 0.104 are obtained using one or more polyethylene standards mentioned below. Typically, the mass detector response (IR5) and light scattering constant (using GPCOne) are also used. TM The determination should be performed using linear standards with a molecular weight exceeding approximately 50,000 g / mol. Other corresponding torques Mn (Abs) and Mz (Abs) The calculations are based on equations 8 and 9 as follows:

[0115]

[0116]

[0117] Extrusion coating

[0118] Single-layer extrusion coating is performed under the set temperature profile represented by the following temperature setting 1: Extruder -200℃ / 250℃ / 280℃ / 290℃ / 290℃ / 290℃; Flange / Adapter / Pipe -290℃ (6 zones); Die -290℃ × 10 zones

[0119] The polyethylene and polypropylene resin blends are fed onto a 3.5-inch diameter screw at a rate of 25 g / m³. 2 The amount (coating weight) extruded to 70 g / m 2On kraft paper, the length-to-diameter (L / D) ratio of the screw is 32, and the melt pressure and melt temperature are recorded using thermocouples placed in the adapter. The melt is conveyed through a Davis Standard / Er-We-Pa flexible lip bead removal die 510A series, with a die clearance nominally set at 0.7 mm. The melt is drawn towards the pressure roller and vertically applied to the moving substrate with an air gap of 250 mm and a pressure zone offset of 15 mm. The melt is applied to the moving substrate in the laminator pressure zone, which serves as the contact point with the pressure roller, where the rubber surface layer contacts a "water-cooled" cooling roller with a matte surface finish and is maintained at a temperature of 15°C to 20°C. The air gap is defined as the vertical distance between the die lip and the laminator pressure zone. The pressure zone offset is defined as the horizontal offset of the die lip position relative to the laminator pressure zone. For "drawing," a value of 15 g / m² is used. 2 Starting with an initial coating weight and an initial linear speed of 100 m / min, varying (gradually increasing) linear speeds are used. "Drawing" is defined as the maximum linear speed achievable before web breakage occurs. "Necking" is the difference between the final width of the web and the die width at a fixed linear speed (e.g., 100 m / min and 300 m / min). Lower "necking" and higher "drawing" are both desirable. Lower "necking" indicates better web dimensional stability, which in turn provides better control over the coating on the substrate. Higher "drawing" indicates higher linear speeds, which in turn means better productivity.

[0120] A first aspect of this disclosure includes a multilayer structure comprising: an oriented film comprising at least 90 wt% polyethylene; and a sealant layer disposed on the oriented film, wherein the sealant layer comprises: 15 wt% to 40 wt% low-density polyethylene based on the total weight of the sealant layer; and 60 wt% to 85 wt% ethylene-based elastomer based on the total weight of the sealant layer, wherein the ethylene-based elastomer of the sealant layer has a content of 0.870 g / cm³. 3 Up to 0.911 g / cm 3 Its density and melt index (I2) of at least 3 g / 10 min.

[0121] A second aspect of this disclosure includes a multilayer structure comprising: an oriented film comprising at least 90 wt% polyethylene; and a sealant layer disposed on the oriented film, wherein the sealant layer comprises: 15 wt% to 40 wt% low-density polyethylene based on the total weight of the sealant layer; and 60 wt% to 85 wt% propylene-based plasmon based on the total weight of the sealant layer, wherein the propylene-based plasmon has a content of 0.890 g / cm³. 3Or a lower density and a melt flow rate of at least 8 g / 10 min (at 230 °C and 2.16 kg).

[0122] The third aspect of this disclosure includes any of the foregoing aspects, wherein the low-density polyethylene of the sealant layer has a molecular weight distribution (Mw / Mn) of 7 to 13.

[0123] The fourth aspect of this disclosure includes any of the foregoing aspects, wherein the low-density polyethylene of the sealant layer has a melt index (I2) of 1.5 to 9.

[0124] The fifth aspect of this disclosure includes any of the foregoing aspects, wherein the orientation film comprises two or more layers.

[0125] The sixth aspect of this disclosure includes any of the foregoing aspects, wherein the sealant layer adheres to and contacts the oriented film.

[0126] The seventh aspect of this disclosure includes any of the foregoing aspects, wherein the multilayer structure further includes a connecting layer, wherein the connecting layer is positioned to contact the sealant layer and the orientation film and is located between the sealant layer and the orientation film.

[0127] The eighth aspect of this disclosure includes any of the foregoing aspects, wherein the connecting layer comprises at least 60% by weight polyethylene having a content of 0.923 g / cm³. 3 Or a lower density and a melt index (I2) of at least 4 g / 10 min.

[0128] The ninth aspect of this disclosure includes any of the foregoing aspects, wherein the connecting layer further comprises at least 15% by weight of low-density polyethylene based on the total weight of the connecting layer.

[0129] The tenth aspect of this disclosure includes any of the foregoing aspects, wherein the ethylene-based elastomer of the sealant layer has a melt index (I2) of 3.0 g / 10 min to 30 g / 10 min.

[0130] The eleventh aspect of this disclosure includes any of the foregoing aspects, wherein the ethylene-based elastomer of the sealant layer has a melting point of 65°C to 100°C.

[0131] The twelfth aspect of this disclosure includes the propylene-based plastide having a melt flow rate of 5 g / 10 min to 35 g / 10 min (at 230 °C and 2.16 kg).

[0132] The thirteenth aspect of this disclosure includes any of the foregoing aspects, wherein the propylene-based plastic body is a copolymer comprising propylene and ethylene units.

[0133] The fourteenth aspect of this disclosure includes any of the foregoing aspects, wherein the propylene-based plastic body has an ethylene content of 2% to 15% by weight.

[0134] The fifteenth aspect of this disclosure includes any of the foregoing aspects, wherein the sealant layer is extruded onto the oriented film.

[0135] The subject matter of this disclosure has been described in detail and with reference to specific embodiments. It should be understood that any detailed description of a component or feature of an embodiment does not necessarily imply that such component or feature is necessary for a particular embodiment or any other embodiment. Furthermore, it will be apparent to those skilled in the art that various modifications and changes can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

[0136] For purposes of description and limitation of this disclosure, it should be noted that the terms “about” or “approximately” are used in this disclosure to indicate the degree of uncertainty attributable to any quantitative comparison, value, measurement or other representation. The terms “about” and / or “approximately” are also used in this disclosure to indicate the degree to which a quantitative representation may vary from a specified reference without causing a fundamental change in the subject matter of interest.

[0137] It should be noted that one or more of the appended claims use the term "wherein" as a transitional expression. For the purpose of defining this technology, it should be noted that this term is introduced in the claims as an open transitional phrase used to introduce a description of a series of features of the structure, and should be interpreted in a similar manner to the more commonly used open prepositional term "comprising".

[0138] It should be understood that when the first component is described as "comprising" the second component, in some embodiments, the first component is "composed of" or "substantially composed of" the second component. It should also be understood that when the first component is described as "comprising" the second component, in some embodiments, the first component may contain at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even at least 99% of the second component (wherein the percentage may be weight percentage or molar percentage).

Claims

1. A multi-layer structure, the multi-layer structure comprising: An oriented film comprising at least 90% by weight polyethylene; as well as A sealant layer located on the orientation film, wherein the sealant layer comprises: Based on the total weight of the sealant layer, 15% to 40% by weight of low-density polyethylene; and Based on the total weight of the sealant layer, 60% to 85% by weight of an ethylene-based elastomer, wherein the ethylene-based elastomer of the sealant layer has a content of 0.870 g / cm³. 3 Up to 0.911 g / cm 3 The density and melt index I2 of at least 3 g / 10 min; The low-density polyethylene in the sealant layer has a molecular weight distribution of 7 to 13 (Mw / Mn). The molecular weight distribution was determined by GPC measurements. Density is measured according to ASTM D792, Method B. The melt index was measured according to ASTM D 1238, under conditions of 190°C / 2.16 kg.

2. A multi-layer structure, the multi-layer structure comprising: An oriented film comprising at least 90% by weight polyethylene; as well as A sealant layer located on the orientation film, wherein the sealant layer comprises: Based on the total weight of the sealant layer, 15% to 40% by weight of low-density polyethylene; and Based on the total weight of the sealant layer, 60% to 85% by weight of a propylene-based plastic body, wherein the propylene-based plastic body has a strength of 0.890 g / cm³ measured at 230°C and 2.16 kg. 3 Or a lower density and a melt flow rate of at least 8 g / 10 min; The low-density polyethylene in the sealant layer has a molecular weight distribution of 7 to 13 (Mw / Mn). Density is measured according to ASTM D792, Method B. The molecular weight distribution was determined by GPC measurements.

3. The multilayer structure according to any of the preceding claims, wherein the low-density polyethylene of the sealant layer has a melt index I2 of 1.5 to 9.

4. The multilayer structure according to claim 1 or 2, wherein the orientation film comprises two or more layers.

5. The multilayer structure according to claim 1 or 2, wherein the sealant layer is in adhesive contact with the oriented film.

6. The multilayer structure according to claim 1 or 2, wherein the multilayer structure further comprises a connecting layer, wherein the connecting layer is positioned to contact the sealant layer and the orientation film and is located between the sealant layer and the orientation film.

7. The multilayer structure according to claim 6, wherein the connecting layer comprises at least 60% by weight polyethylene, the polyethylene having a content of 0.923 g / cm³. 3 Or a lower density and a melt index I2 of at least 4 g / 10 min.

8. The multilayer structure of claim 7, wherein, based on the total weight of the connecting layers, the connecting layers further comprise at least 15% by weight of low-density polyethylene.

9. The multilayer structure according to claim 1, wherein the ethylene-based elastomer of the sealant layer has a melt index I2 of 3.0 g / 10 min to 30 g / 10 min.

10. The multilayer structure according to claim 1, wherein the ethylene-based elastomer of the sealant layer has a melting point of 65°C to 100°C; The melting point is measured according to ASTM D3418.

11. The multilayer structure according to claim 2, wherein the propylene-based plastide has a melt flow rate of 5 g / 10 min to 35 g / 10 min measured at 230 °C and 2.16 kg.

12. The multilayer structure according to claim 2, wherein the propylene-based plastic body is a copolymer comprising propylene and ethylene units.

13. The multilayer structure according to claim 12, wherein the propylene-based plastic body has an ethylene content of 2% to 15% by weight.

14. The multilayer structure according to claim 1, wherein the sealant layer is extruded onto the oriented film.

15. The multilayer structure according to claim 1, wherein the ethylene-based elastomer of the sealant layer has a content of 0.870 g / cm³. 3 Up to 0.90 g / cm 3 The density.

Images