Multilayer structure including orientation film and sealant layer

Abstract

According to one or more embodiments disclosed herein, the multilayer structure may include an oriented film and a sealant layer. The oriented film may include at least 90 wt% polyethylene. The sealant layer may include 15 to 40 wt% low density polyethylene, based on the total weight of the sealant layer. The sealant layer may 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

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Patent Application No. 63 / 124,300, filed on 11 December 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] This disclosure relates, in general, to multilayer structures, and more specifically to polyolefin multilayer structures, such as those used in consumer packaging. [Background technology]

[0003] Many types of flexible and semi-rigid packaging designed to protect food, beverages, other liquids, personal care products, and other consumer products have been manufactured using polyolefin multilayer structures. Such structures can be sealed under heat, as is widely understood. Generally, a sealant layer is used in packaging to seal the multilayer structure together at high temperatures. It is desirable to have alternative multilayer structures that can be used in packaging and that can offer one or more benefits. [Overview of the Initiative]

[0004] Many multilayer structures, such as films used in packaging, are sealed by utilizing a heated sealing bar that bonds two films together. A sealant layer may be provided as part of a multilayer structure that melts to form a sealing bond. Oriented polyethylene films, such as longitudinally oriented films and biaxially oriented films, are becoming more common and desirable for use in several packaging applications. Embodiments of this disclosure provide sealant layers comprising a combination of low-density polyethylene and an ethylene-based elastomer, or a combination of low-density polyethylene and a propylene-based plastomer. Such sealant layers can provide a seal at a lower sealing temperature compared to conventional sealant layers. This may be particularly advantageous when used with an oriented film containing at least 90% by weight of polyethylene, because such films have a lower melting point compared to polypropylene or polyethylene terephthalate films, which are often used in packaging materials. By facilitating sealing at lower temperatures, the sealant layer, when used with an oriented film having at least 90% by weight of polyethylene, can provide good seal strength while minimizing or avoiding degradation or other damage to the oriented film. In addition, the sealant layers disclosed herein may enable improved machining (e.g., increased machining speed with reduced motor load) in one or more embodiments. These and other advantages may be demonstrated by the multilayer structures of this disclosure according to one or more embodiments described herein.

[0005] According to one or more embodiments of the present disclosure, a multilayer structure may comprise an oriented film and a sealant layer. The oriented film contains at least 90% by weight of polyethylene. The sealant layer may be on the oriented film. The sealant layer may contain 15 to 40% by weight of low-density polyethylene, based on the total weight of the sealant layer. The sealant layer may further contain 60% to 85% by weight of an ethylene-based elastomer, based on the total weight of the sealant layer. The ethylene-based elastomer in the sealant layer is 0.870 g / cm³ 3 ~0.911 g / cm³ 3may have a density and a melt index (I2) of at least 3 g / 10 min.

[0006] According to one or more further embodiments of the present disclosure, the multilayer structure may include an oriented film and a sealant layer. The oriented film may include at least 90% by weight of polyethylene. The sealant layer may be on the oriented film. The sealant layer may include 15% to 40% by weight of low density polyethylene based on the total weight of the sealant layer. The sealant layer may further include 60% to 85% by weight of a propylene-based plastomer based on the total weight of the sealant layer. The propylene-based plastomer has a density of 0.890 g / cm 3 may have the following density and a melt flow rate (at 230 °C and 2.16 kg) of at least 8 g / 10 min.

[0007] These and other embodiments are described in more detail in the "Detailed Description of the Invention". It should be understood that both the above general description and the following detailed description are intended to represent embodiments of the technology and to provide an overview or framework for understanding the nature and characteristics of the technology as it is claimed. The accompanying drawings are included to provide a further understanding of the technology and are incorporated herein and constitute a part of this specification. The drawings illustrate various embodiments and, together with the description, serve to explain the principles and operations of the technology. Further, the drawings and the description are intended to be illustrative only and are not intended to limit the claims in any way.

Brief Description of the Drawings

[0008] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, in which like structures are indicated by like reference numerals.

[0009] [Figure 1] Graph showing the seal strength of an exemplary embodiment according to one or more embodiments of the present disclosure. [Figure 2]The hot tack intensity of exemplary embodiments according to one or more embodiments of this disclosure is shown graphically. [Modes for carrying out the invention]

[0010] Next, we will refer in more detail to various embodiments that are examples of the claimed subject matter. It should be understood that the multilayer structure features described in the detailed description should not be understood as limiting the claimed embodiments unless explicitly stated otherwise.

[0011] According to one or more embodiments, multilayer structures comprising an oriented film and a sealant layer are described herein. In some embodiments, the sealant layer may comprise low-density polyethylene and a propylene-based plastomer. In further embodiments, the sealant layer may comprise low-density polyethylene and an ethylene-based elastomer. As described herein, “multilayer structure” means any structure having two or more layers. For example, a multilayer structure (e.g., a film) may have two, three, four, five or more layers. A multilayer structure may be described as having layers specified by letters. For example, a three-layer structure having a core layer B and two outer layers A and C may be represented as A / B / C. Similarly, a structure having two core layers B and C and two outer layers A and D would be represented as A / B / C / D.

[0012] According to one or more embodiments, the multilayer structure may include an orientation film. As described herein, the “orientation” film is formed by stretching the film in any direction. Embodiments of the orientation film include longitudinal orientation films and biaxial orientation films.

[0013] According to one or more embodiments, the multilayer structure may include a longitudinally oriented film. As described herein, a “longitudinally oriented” film is formed by uniaxially stretching the film longitudinally. For example, the film may be heated and uniaxially stretched longitudinally on a series of rollers. As used herein, the term “longitudinal” means the length of the film in the direction in which the film is manufactured. A longitudinally oriented film may exhibit improved tensile properties compared to one that has not undergone a longitudinal orientation procedure.

[0014] In further embodiments, the multilayer structure may include a biaxially oriented film. As used herein, a “biaxially oriented” film is formed by biaxially stretching the film in a longitudinal and transverse or transverse direction to improve its physical and / or barrier properties. For example, the film may be heated and biaxially stretched in a longitudinal and transverse direction on a series of rollers. As used herein, the term “longitudinal” means the length of the film in the direction in which the film is manufactured. The terms “transverse” or “transverse” or “transverse” mean the width of the film, i.e., the direction generally perpendicular to the longitudinal direction. A biaxially oriented film may exhibit improved tensile properties compared to one that has not been subjected to a biaxial orientation procedure.

[0015] As used herein, “film” generally includes any continuous layer of polyolefin-containing material having a large length-to-width ratio. In one or more embodiments, the film may include one or more olefin polymers. As used herein, the terms “olefin polymer,” “olefin polymer,” and “polyolefin” refer to a polymer that, in its polymerized form, contains a majority of olefin monomers (based on the weight of the polymer), such as ethylene or propylene, and may optionally contain one or more comonomers. The term “polymer” refers to a polymer compound prepared by polymerizing monomers, whether of the same or different types. Thus, the general term polymer includes the term “homopolymer,” which is usually used to refer to a polymer prepared from only one type of monomer, and “copolymer,” which refers to a polymer prepared from two or more different monomers. The film described herein may be a multilayer film comprising two or more layers.

[0016] In one or more embodiments, the orientation film may contain at least 90% by weight of polyethylene. In further embodiments, the orientation film may contain at least 95% by weight, at least 98% by weight, at least 99% by weight, or even more than 99.5% by weight of polyethylene. It should be understood that the orientation film may be, for example, a single layer of a blended polymer in which at least 90% by weight is polyethylene, or a multilayer in which some layers are not polyethylene but the combination of layers contains at least 90% by weight of polyethylene. In one or more embodiments, the material of the orientation film closest to the sealant layer may contain polyethylene.

[0017] As described herein, “polyethylene” or “ethylene polymer” means a polymer containing more than 50 mol% of ethylene monomer-derived units. This includes ethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Examples of polyethylene include, but are not limited to, low-density polyethylene (LDPE). Examples include linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (ULDPE), very low-density polyethylene (VLDPE), single-site catalyst linear low-density polyethylene (m-LLDPE) including both linear low-density resins and substantially linear low-density resins, medium-density polyethylene (MDPE), and high-density polyethylene (HDPE).

[0018] As described herein, the term “LDPE” may also be referred to as “high-pressure ethylene polymer” or “highly branched polyethylene,” and is defined to mean that the polymer is partially or completely homopolymerized or copolymerized in an autoclave or tubular reactor at a pressure exceeding 14,500 psi (100 MPa) using a free radical initiator such as a peroxide (see, for example, U.S. Patent No. 4,599,392 incorporated by reference). LDPE resins typically have a density in the range of 0.916 to 0.940 g / cm³.

[0019] As described herein, the term "LLDPE" may include resins prepared using the Ziegler-Natta catalyst system, as well as resins prepared using single-site catalysts, including but not limited to bis-metallocene catalysts (sometimes referred to as "m-LLDPE"), phosphine imines, and constrained geometric catalysts; and resins prepared using post-metallocene molecular catalysts, including but not limited to bis(biphenylphenoxy) catalysts (also referred to as polyvalent aryloxy ether catalysts). LLDPEs include linear, substantially linear, or heterogeneous ethylene copolymers or homopolymers. LLDPE contains fewer long-chain branches than LDPE and comprises substantially linear ethylene polymers, including substantially linear ethylene polymers as further defined in U.S. Patents 5,272,236, 5,278,272, 5,582,923 and 5,733,155, homogeneously branched ethylene polymer compositions such as those in U.S. Patent 3,645,992, heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent 4,076,698, and blends thereof (such as those disclosed in U.S. Patents 3,914,342 or 5,854,045). LLDPE resins can be produced by gas-phase, solution-phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0020] The term "ULDPE" is defined as a polyethylene copolymer having a density in the range of 0.895 to 0.915 g / cc.

[0021] The term "MDPE" refers to polyethylene having a density of 0.926–0.935 g / cc. "MDPE" is typically produced using chromium or Ziegler-Natta catalysts, or single-site catalysts including, but not limited to, bis-metallocene catalysts and constrained geometric catalysts.

[0022] The term "MDPE" refers to polyethylene having a density of 0.926–0.935 g / cc. "MDPE" is typically produced using chromium or Ziegler-Natta catalysts, or single-site catalysts including, but not limited to, bis-metallocene catalysts and constrained geometric catalysts.

[0023] Furthermore, as described herein, the term "HDPE" generally refers to polyethylene having a density of about 0.940 g / cm³ or more, prepared using a Ziegler-Natta catalyst, a chromium catalyst, or even a metallocene catalyst.

[0024] According to one or more embodiments, the orientation film may have a melting point of 150°C or less, for example, 145°C or less, or even 140°C or less, for example, at least 120°C. This is in contrast to other films that may have higher melting points. For example, polypropylene films may have a melting point above 150°C, and polyethylene terephthalate films may have a melting point above 250°C.

[0025] It should be understood that the orientation films described herein are not particularly limited by their manufacturing method or source. Those skilled in the art are generally familiar with orientation films, many of which are commercially available. As will be understood by those skilled in the art, specific orientation films may be selected based on the intended application of the multilayer structure.

[0026] Each layer of the film may further contain one or more additives known to those skilled in the art, such as plasticizers, stabilizers including viscosity stabilizers, hydrolysis stabilizers, primary and secondary antioxidants, ultraviolet absorbers, antistatic agents, dyes, pigments, or other colorants, inorganic fillers, flame retardants, lubricants, reinforcing agents such as glass fibers and flakes, synthetic (e.g., aramid) fibers or pulp, forming agents or foaming agents, processing aids, slip additives, anti-tack agents such as silica or talc, release agents, tackifying resins, or two or more combinations thereof. Inorganic fillers such as calcium carbonate and analogues may also be incorporated into one or more of the first layer, second layer, third layer, and combinations thereof. In some embodiments, the skin layer, subskin layer, binding layer, barrier layer, and combinations may each contain up to 5 weight percent of the above-mentioned additional additives based on the total weight of each layer. All individual values ​​and subranges from 0% to 5% by weight are included and disclosed herein, for example, the total amount of additives in any layer may be 0.5% to 5% by weight, 0.5% to 4% by weight, 0.5% to 3% by weight, 0.5% to 2% by weight, 0.5% to 1% by weight, 1% to 5% by weight, 1% to 4% by weight, 1% to 3% by weight, 1% to 2% by weight, 2% to 5% by weight, 2% to 4% by weight, 2% to 3% by weight, 3% to 5% by weight, 3% to 4% by weight, or 4% to 5% by weight, based on the total weight of each layer. The incorporation of additives can be carried out by any known process, such as dry blending, extrusion of a mixture of various components, or conventional masterbatch technology.

[0027] The multilayer structures of this disclosure may have a variety of thicknesses. The thickness of the multilayer structure may depend on a number of factors, including, for example, the number of layers of the multilayer structure, the composition of the layers of the multilayer structure, the desired properties of the multilayer structure, the desired end use of the multilayer structure, and the manufacturing process of the multilayer structure. In embodiments, the multilayer structure may have a thickness of less than 205 micrometers (μm or micron). In this embodiment, the multilayer structure may have a thickness of 15 μm to 205 μm, 20 μm to 180 μm, 15 μm to 180 μm, 15 μm to 160 μm, 15 μm to 140 μm, 15 μm to 120 μm, 15 μm to 100 μm, 15 μm to 80 μm, 15 μm to 60 μm, 15 μm to 40 μm, 20 μm to 160 μm, 20 μm to 140 μm, 20 μm to 120 μm, 20 μm to 100 μm, 20 μm to 80 μm, 20 μm to 60 μm, or 20 μm to 40 μm.

[0028] The multilayer structure may further include a sealant layer. The sealant layer may generally be heated and pressurized to seal two multilayer structures together. The sealant layer may be positioned on an orientation film. As described herein, "positioned on" an orientation film means either in direct contact with the orientation film or minimally separated from it by a binder layer or the like. As described herein, a "binder layer" refers to a polymer layer positioned between two polymer layers and in direct contact with both polymer layers. A binder layer can generally facilitate adhesion between the two polymer layers it contacts. In the absence of a binder layer, the sealant layer may be in adhesive contact with the orientation film. Terms such as "adhesive contact" mean that one opposing surface of one layer and one opposing surface of another layer are in contact with each other and are in bonded contact, such that one layer cannot be removed from the other without damaging the interlayer surfaces (i.e., the contacting facial surfaces) of both layers.

[0029] In one or more embodiments, the sealant layer may be extruded onto the oriented film. As described herein, the sealant layer may be extruded onto a longitudinally oriented polyethylene film by extruding the molten component of the sealant layer through a die onto the film to achieve a desired layer thickness, as is known to those skilled in the art. Extrusion coating may be generally known to those skilled in the art and generally involves coating a molten web of polymer material onto a substrate material, usually at high temperatures. If a binder layer is present, the binder layer may be extruded directly onto the oriented film, and the sealant layer may be extruded onto the binder layer.

[0030] In one or more embodiments, the sealant layer may contain up to 15 to 40 weight percent of low-density polyethylene based on the total weight of the sealant layer. For example, the sealant layer may contain 15 to 20 weight percent, 20 to 25 weight percent, 25 to 30 weight percent, 30 to 35 weight percent, 35 to 40 weight percent, or any combination of these ranges based on the total weight of the sealant layer. In embodiments, the sealant layer may further contain 15 to 30 weight percent of low-density polyethylene based on the total weight of the sealant layer.

[0031] 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.

[0032] 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. When used herein, the melt index (I2) is a measure of the melt flow rate of a polymer and is measured by ASTM D1238 at a temperature of 190°C and a load of 2.16 kg.

[0033] In one or more embodiments, the low-density polyethylene of the sealant layer is 0.918 g / cm³. 3 DOW LDPE 770G (commercially available from The Dow Chemical Company) has a density of 2.3 g / 10 min, a melt index of 2.3 g / 10 min, and a melting point of 110 °C, or 0.918 g / cm³. 3 It may be selected from AGILITY EC 7220 Performance LDPE (commercially available from The Dow Chemical Company) having a density and a melt index of 1.5 g / 10 min. However, other LDPEs are intended for use in sealant layers, and the embodiments described herein are not limited to those containing these polymers.

[0034] In some embodiments, in addition to low density polyethylene, the sealant layer may include a propylene-based plastomer. In one or more embodiments described herein, "propylene-based plastomer" may refer to a semi-crystalline copolymer of propylene and ethylene that contains more than 70% by weight of polypropylene with 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 plastomer described herein includes propylene-based copolymers (meaning units derived from two or more comonomers) of propylene and an alpha olefin comonomer such as ethylene, butene, pentene, 4-methyl-1-pentene, hexene, heptene, octene, or nonene. A plastomer can generally be understood as a polymeric material that combines the qualities of an elastomer and a plastic.

[0035] According to one or more embodiments, the sealant layer may include 60 to 85 weight percent of a propylene-based plastomer based on the total weight of the sealant layer. For example, the sealant layer may include 60 to 65 weight percent, 65 to 70 weight percent, 70 to 75 weight percent, 75 to 80 weight percent, 80 to 85 weight percent, or any combination of these ranges of propylene-based plastomer based on the total weight of the sealant layer.

[0036] 1 According to one or more embodiments, the propylene-based plastomer may have the 3 following densities. For example, the propylene-based plastomer may have a density of 0.860 g / cm 3 to 0.890 g / cm 3 , for example, 0.860 g / cm 3 to 0.865 g / cm 3 , 0.865 g / cm 3 to 0.870 g / cm 3 , 0.870 g / cm 3 to 0.875 g / cm 3 , 0.875 g / cm 3 to 0.880 g / cm 3 , 0.880 g / cm3 ~0.885g / cm 3 , 0.885 g / cm³ 3 ~0.890g / cm 3 , or the density may be any combination of these ranges.

[0037] In one or more embodiments, the propylene 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 plastomer may have a melt flow rate of 5 g / 10 min to 35 g / 10 min, e.g., 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). When described herein, the melt flow rate is measured according to ASTM-D1238-10, under conditions of 230°C / 2.16 kg, and reported in grams eluted per 10 minutes.

[0038] In one or more embodiments, the propylene plastomer may have a melt flow rate of 20 g / 10 min to 30 g / 10 min. For example, the propylene plastomer 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 plastomer may be 12% to 30%, and / or the glass transition temperature may be -15°C to 35°C.

[0039] In one or more embodiments, the propylene-based plastomer may have a melting point between 60°C and 120°C. For example, the propylene-based plastomer may have a melting point between 60°C and 80°C, 80°C and 100°C, 100°C and 120°C, or any combination of these ranges.

[0040] In one or more embodiments, the propylene plastomer may be a copolymer containing propylene and ethylene units. According to one or more embodiments, the propylene plastomer may have an ethylene content of 2% to 15% by weight. For example, the propylene plastomer 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.

[0041] In one or more embodiments, the propylene-based plastomer is 0.876 g / cm³ 3 The VERSIFY 4200 plastomer (commercially available from The Dow Chemical Company) may be used, having a density of 25 g / 10 min, a melt flow rate of 25 g / 10 min, and a melting point of 100 °C. However, other propylene-based plastomers are intended for use in sealant layers, and the embodiments described herein are not limited to those containing these polymers.

[0042] In some embodiments, in addition to low-density polyethylene, the sealant layer may also contain an ethylene-based elastomer. As used herein, “ethylene-based elastomer” refers to a polymer containing more than 50 mol% units derived from ethylene monomers. This includes ethylene-based α-alkene copolymers (meaning units derived from two or more comonomers) having densities of 0.870 g / cc to 0.911 g / cc. Elastomers can generally be understood as viscoelastic polymer materials (i.e., those that exhibit both viscous and elastic properties when deformed).

[0043] 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 based on the total weight of the sealant layer.

[0044] In one or more embodiments, the ethylene-based elastomer is 0.87 g / cm³ 3 ~0.911 g / cm³ 3 It can have a density of 0.87 g / cm³. For example, ethylene-based elastomers have a density of 0.87 g / cm³. 3 ~0.875g / cm 3 , 0.875 g / cm³ 3 ~0.88 g / cm³ 3 , 0.88 g / cm³ 3 ~0.885g / cm 3 , 0.885 g / cm³ 3 ~0.90g / cm 3 0.90 g / cm³ 3 ~0.905 g / cm³ 3 , 0.905 g / cm³ 3 ~0.911 g / cm³ 3 , or the density may be any combination of these ranges.

[0045] In one or more embodiments, the ethylene-based elastomer may have a melt index of at least 3 g / 10 min, for example, 3 g / 10 min to 30 g / 10 min. For example, ethylene-based elastomers may have melt indices of 3g / 10 min to 5g / 10 min, 5g / 10 min to 7.5g / 10 min, 7.5g / 10 min to 10g / 10 min, 10g / 10 min to 12.5g / 10 min, 12.5g / 10 min to 15g / 10 min, 15g / 10 min to 17.5g / 10 min, 17.5g / 10 min to 20g / 10 min, 20g / 10 min to 22.5g / 10 min, 22.5g / 10 min to 25g / 10 min, 25g / 10 min to 27.5g / 10 min, 27.5g / 10 min to 30g / 10 min, or any combination of these ranges.

[0046] In one or more embodiments, the ethylene-based elastomer may have a melting point between 65°C and 100°C. For example, the ethylene-based elastomer may have a melting point between 65°C and 70°C, 70°C and 75°C, 75°C and 80°C, 80°C and 85°C, 85°C and 90°C, 90°C and 95°C, 95°C and 100°C, or any combination of these ranges.

[0047] In one or more embodiments, the ethylene-based elastomer in the sealant layer is 0.885 g / cm³ 3 ENGAGE 8401 (commercially available from The Dow Chemical Company) has a density and a melt index of 30 g / 10 min, or 0.88 g / cm³. 3 A choice may be made from ENGAGE 8411 (commercially available from The Dow Chemical Company) having a density and a melt index of 18 g / 10 min. However, other ethylene-based elastomers are intended for use in sealant layers, and the embodiments described herein are not limited to those containing these polymers.

[0048] In one or more embodiments, the combination of low-density polyethylene and propylene-based plastomer may include at least 90% by weight of a sealant layer. In embodiments herein, the combination of low-density polyethylene and propylene-based plastomer may include 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 at least 100% by weight of a sealant layer.

[0049] In one or more embodiments, the combination of low-density polyethylene and ethylene-based elastomer may constitute a sealant layer of at least 90% by weight. In embodiments herein, the combination of low-density polyethylene and ethylene-based elastomer may include a sealant layer of 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.

[0050] When described herein, the multilayer structure may include a binding layer. The binding layer may provide a bond between the oriented polyethylene film and the propylene-based plastomer sealant so that it can be positioned in contact with the sealant layer and the oriented film. In one or more embodiments, the binding layer has a density of 0.923 g / cm³. 3 The binder layer may contain polyethylene having the following density and melt index (I2) of at least 4 g / 10 min: at least 60% by weight of polyethylene, for example at least 70% by weight, at least 80% by weight, at least 90% by weight, at least 95% by weight, or even more than 99% by weight, at 0.923 g / cm³ 3 The polyethylene may also have the following densities and a melt index (I2) of at least 4 g / 10 min. In one or more embodiments, such polyethylene may be 0.923 g / cm³. 3 The densities may be, for example, 0.900-0.905, 0.905-0.910, 0.910-0.915, 0.915-0.920, 0.920-0.923, or any combination of these ranges. In one or more embodiments, the binding layer may have a melt index (I2) of at least 4 g / 10 min, for example, 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.

[0051] According to embodiments described herein, a binding layer may be particularly desirable when the sealant layer contains a propylene-based plastomer, so as to achieve good adhesion between the sealant layer and the outer layer of the polyethylene film. A binding layer may also be desirable in systems where the propylene layer and the ethylene layer are in direct contact with each other without the use of a binding layer.

[0052] In further embodiments, the binder layer may contain at least 15% by weight of low-density polyethylene, based on the total weight of the binder layer. For example, the binder 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 more than 50% by weight of low-density polyethylene. The low-density polyethylene of the binder layer may have the same or identical characteristics and properties as those disclosed with respect to the low-density polyethylene of the sealant layer. For example, a blend of 70% by weight of ELITE® 5860 or AFFINITY® 1451 and 30% by weight of DOW® LDPE 770G or 7220 may be used as the binder layer.

[0053] Embodiments of this disclosure also relate to articles such as packages formed from the multilayer structures of this disclosure. Such packages may be formed from any of the multilayer structures of this disclosure described herein. Examples of such articles include flexible packaging, pouches, self-standing pouches, and ready-made packaging materials or ready-made pouches. Various methods for manufacturing embodiments of articles from the multilayer films disclosed herein will be well known to those skilled in the art.

[0054] The terms “comprising,” “including,” and “having,” and their derivatives, are not intended to exclude the presence of any additional components, processes, or procedures, whether or not they are specifically disclosed. To avoid any doubt, all compositions claimed through the use of the term “comprising” may include any additional additives, auxiliaries, or compounds, whether polymeric or otherwise, unless otherwise stated. In contrast, the term “consisting essentially of” excludes any other components, processes, or procedures from the scope of any subsequent description, except those not essential to operability. The term “consisting of” excludes any components, processes, or procedures not specifically described or listed.

[0055] The terms “blend” and “polymer blend” refer to a composition of two or more polymers. Such a blend may or may not be miscible. Such a blend may or may not be phase-separated. Such a blend may or may not contain one or more domain configurations, as determined by transmission electron spectroscopy, light scattering, X-ray scattering, and any other method well known in the art. A blend is not a laminate, but one or more layers of a laminate may contain a blend. Such a blend may be prepared as a dry blend, or formed in situ (e.g., in a reactor), as a molten blend, or by other techniques known to those skilled in the art.

[0056] It will be apparent that modifications and changes are possible without departing from the scope of this disclosure as defined in the attached claims. More specifically, certain aspects of this disclosure are identified herein as preferred or particularly advantageous, but this disclosure is intended not to be limited to these aspects. [Examples]

[0057] Several examples relating to one or more of the currently disclosed embodiments are provided.

[0058] The sealant layer is made of kraft paper (60g / m²). 2 The molten polymer was extruded onto the substrate. All sealant layers were extruded at 290°C using a 250 mm air gap and a 0.6 mm die gap. The nip offset was -15 mm. The extrusion equipment included a Davis Standard ER-WE-PA, Maschinenfabrik Erkrath Nr.7237 extrusion coating line with an EBR (edge ​​bead removal) flat, 1050 mm wide slit die, equipped with a feed block co-extrusion system and an extruder with a polymer production capacity of up to 350 kg / h. For these evaluations, the largest extruder "A" with a single slot feed block and an ET Barr 3.5” double flight compression screw L / D32 was used. The molten polymer was coated onto a paper or film substrate and cooled by a cooling roll (cooling roll temperature 15°C).

[0059] Table 1 provides various sealant layer compositions that were tested. All polymers tested in the sealant layers and identified in Table 1 are commercially available from The Dow Chemical Co. Reference numbers corresponding to the figures are also provided in Table 1. Table 2 provides information on the polymers in the sealant layers.

[0060] [Table 1] [Table 2]

[0061] Figure 1 shows the seal strength (N / 15mm) as a function of seal temperature (°C). As shown, in general, samples 1-3 had greater seal strength with respect to temperature than the comparative examples tested. In addition, Figure 2 shows the hot tack data, and samples 1-3 provide better hot tack strength at lower seal temperatures (e.g., below 80°C). Note that samples 1 and 3 are representative examples of sealant layers containing low-density polyethylene and ethylene-based elastomers, as described in the detailed description. Sample 2 is a representative example of a sealant layer containing low-density polyethylene and propylene-based plastomer. Increased seal strength and hot tack strength at lower temperatures are desirable, and lower heat seal and hot tack initiation temperatures are shown. Samples 1-3 also had greater overall seal strength than the comparative examples at most temperatures.

[0062] The processability of the samples was also analyzed. Table 3 shows the neck-in and draw-down rates of the tested samples. Neck-in is the shrinkage of the polymer film between the die exit and the coating substrate (i.e., during the air gap), and is considered material waste. Draw-down refers to how fast the coating line can be run and how thinly the polymer film can be stretched. Polymers suitable for extrusion coating must have low neck-in (to minimize polymer waste) and high / sufficient draw-down (to obtain thin coatings and high throughput). As shown, samples 1-3 are acceptable and often have excellent neck-in and draw-down compared to other sealant materials. [Table 3]

[0063] As shown in Table 4, the motor load was also analyzed. Furthermore, the melting pressure was analyzed and is shown in Table 5. Samples 1-3 are acceptable and, in many cases, have excellent required motor loads compared to other sealant materials. This is a desirable processing characteristic. [Table 4] [Table 5]

[0064] Hot tack strength onset temperature data were collected and are shown in Table 6. For these tests, the samples were inflated at 25 g / m² at a line speed of 100 m / min and an extruder setting temperature of 290°C. 2 The paper was coated with the specified coating weight. [Table 6]

[0065] Test method Unless otherwise specified, the following test methods will be used to measure each of the characteristics listed below.

[0066] density

[0067] Samples for density measurement were prepared according to ASTM D1928. The polymer samples were pressed at 190°C and 30,000 psi for 3 minutes, followed by 21°C and 207 MPa for 1 minute. Measurements were performed within 1 hour of sample pressing using ASTM D792, Method B.

[0068] melting point

[0069] The melting point (Tm) was measured using differential scanning calorimetry (DSC). The DSC was performed using a TA Instruments Q1000 DSC equipped with RCS cooling accessories and an autosampler. The melting point (Tm) of the sample was measured according to ASTM D3418.

[0070] Melt Index

[0071] The melt index, or I2 (g / 10 min or dg / min), was measured according to ASTM D 1238, under the conditions of 190°C / 2.16 kg for polyethylene and 230°C / 2.16 kg for polypropylene.

[0072] Heat seal measurement

[0073] Samples were sealed using a Kopp heat sealer within the standard temperature range of 60°C to 160°C. The sealing time was set to 0.5 seconds. The heat seal bar pressure was set to 0.5 N / mm². 2 That was the case.

[0074] Heat seal measurements on the film were performed using a commercially available tensile testing machine according to ASTM F-88 (Technique A). The test specimen was a 15 mm wide die-cut strip. The sample was cut along the longitudinal direction. Therefore, the actual intermediate phase was formed transversely by the molten sealant material. The test results were the force required to separate the fused intermediate phase, or the force required to break the film if the film broke before the heat-sealed intermediate phase separated.

[0075] Seal strength is related to the opening force and the integrity of the package. Before cutting, the film was conditioned for a minimum of 40 hours at 23°C (±2°C) and 50% (±5%) RH (relative humidity) according to ASTM D-618 (Procedure A). Seal strength was measured by separating the molten interlayer on a Zwick tensile tester using a crosshead speed of 100 mm / min.

[0076] The heat seal initiation temperature was the minimum sealing temperature required to form a seal of considerable strength, in this case 4N / 15mm. The seal was formed in a Kopp heat sealer with a residence time of 0.5 seconds and a yield of 0.5N / mm. 2 The measurements were performed at the seal bar pressure. Tensile measurements were performed on a Zwick tensile tester using a crosshead speed of 100 mm / min.

[0077] Hot Tack

[0078] Terms such as "hot tack strength" refer to the strength of the heat seal formed between the thermoplastic surfaces of a flexible web immediately after the seal is created and before it cools to ambient temperature. In form-fill operations, the sealed area of ​​the package is often subjected to destructive forces while it is still hot. If the hot seal is not sufficiently resistant to these forces, breakage may occur during the packaging process. Hot tack strength was measured using a J&B "3000" hot tack tester. Hot tack strength, also known as hot seal strength, is a means of characterizing and ranking materials in their ability to perform in commercial applications where this quality is critical. In the measurement, the sample was cut into 1-inch strips longitudinally and tested against a standard hot tack curve in the range of 80°C to 160°C, in 5°C increments up to 120°C and in 10°C increments up to 160°C. Teflon-coated jaws are standard, but metal jaws can also be used. The residence time was 0.5 seconds and the cooling time was 0.2 seconds. Next, the seal was pulled off at a speed of 200 mm / second, and the peel strength was recorded.

[0079] The hot tack initiation temperature refers to the temperature at which the hot tack intensity reaches at least a predetermined threshold intensity. For example, in some cases, the hot tack initiation temperature was determined to be 1.5 N / 15 mm.

[0080] Gel permeation chromatography (GPC)

[0081] The chromatography system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) coupled to a Precision Detectors (now Agilent Technologies) Model 2040 two-angle laser light scattering (LS) detector. A 15-degree angle was used for all light scattering measurements. The autosampler oven compartment was set to 160°C and the column compartment to 150°C. The columns used were four Agilent "Mixed A" 30 cm, 20 micrometer linear mixed-bed columns. The chromatography solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was spurged with nitrogen. The injection volume used was 200 microliters, and the flow rate was 1.0 ml / min.

[0082] The GPC column set was calibrated using 21 polystyrene standards with narrow molecular weight distributions ranging from 580 to 8,400,000, placed in six "cocktail" mixtures with at least a 10-fold gap between individual molecular weights. The standards were purchased from Agilent Technologies. Polystyrene standards were prepared using 0.025 grams in 50 ml of solvent for molecular weights greater than 1,000,000, and 0.05 grams in 50 ml of solvent for molecular weights less than 1,000,000. The polystyrene standards were dissolved at 80 degrees Celsius for 30 minutes with gentle stirring. The peak molecular weights of the polystyrene standards were converted to polyethylene molecular weights using Formula 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)).

number

[0083] A quintic polynomial was used to fit each polyethylene equivalent calibration point. A slight adjustment (approximately 0.415 to 0.44) was made to A to compensate for column resolution and band broadening effects so that the NIST standard NBS 1475 could be obtained at 52,000 Mw.

[0084] The total plate count of the GPC column set was performed using Eicosane (prepared at 0.04 g in 50 ml of TCB and dissolved for 20 minutes with gentle agitation). Plate count (Equation 2) and symmetry (Equation 3) were measured using 200 microliter injections according to the following formulas.

number

number

[0085] Samples were prepared semi-automatically using PolymerChar "Instrument Control" software, with a target weight of 2 mg / mL. The solvent (containing 200 ppm BHT) was added to a pre-nitrogen-spurged, septa-capped vial via a PolymerChar high-temperature autosampler. The samples were dissolved at 160°C for 2 hours under "low-speed" shaking.

[0086] Mn (GPC) , Mw (GPC) , and Mz (GPC) The calculations were based on GPC results using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph, according to equations 4-6, using the PolymerChar GPCOne® software, the IR chromatogram with the baseline subtracted at each equally spaced data retrieval point (i), and the polyethylene equivalent molecular weight obtained from the narrow standard material calibration curve for point (i) in equation 1.

number

number

number

[0087] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by the PolymerChar GPC-IR system. Using this flow rate marker (FM), the pump flow rate (apparent flow rate) for each sample was linearly corrected by RV matching between the decane peak in each sample (RV(FM sample)) and that of the decane peak in the narrow standard calibration (RV(FM calibrated)). It was then assumed that any temporal changes in the decane marker peak corresponded to a linear shift in the flow rate (effective flow rate) throughout the run. To facilitate the highest accuracy of RV measurement of the flow rate marker peak, a least-squares fitting routine was used, fitting the peaks of the flow rate marker concentration chromatogram to a quadratic equation. The true peak location was then solved using the first derivative of the quadratic equation. After calibrating the system based on the flow rate marker peaks, the effective flow rate (relative to the narrow standard calibration) was calculated as shown in Equation 7. Processing of the flow rate marker peaks was performed via PolymerChar GPCOne® software. An acceptable flow correction is one such correction that the effective flow rate should be within + / - 2% of the apparent flow rate.

number

[0088] A systematic approach to determining the multiple detector offset was carried out in a manner consistent with that published by Balke, Mourey, et al. (Mourey and Balke, Chromatography Polym. Chpt 12, (1992)) (Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym. Chpt 13, (1992)), using PolymerChar GPCOne® software to optimize the results of triple detector logs (MW and IV) from a broad homopolymer polyethylene standard material (Mw / Mn>3) against the results of narrow standard column calibration from a narrow standard calibration curve.

[0089] Absolute molecular weight data were obtained using PolymerChar GPCOne® software in a format consistent with that published by Zimm (Zimm, BH, J. Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scattering from Polymer Solutions, Elsevier, Oxford, NY (1987)). The total injection concentration used in determining the molecular weight was obtained from the mass detector area and mass detector constant derived from one of a suitable linear polyethylene homopolymer or a polyethylene standard material with a known weight-average molecular weight. The molecular weight calculated (using GPCOne®) was obtained using the light scattering constant and the refractive index concentration coefficient of 0.104, dn / dc, derived from one or more of the polyethylene standards described below. In general, the mass detector response (IR5) and light scattering constant (determined using GPCOne®) should be determined from linear standard materials with a molecular weight greater than approximately 50,000 g / mol. (Abs) and Mz (Abs) This is calculated according to the following equations 8-9.

number

number

[0090] Extrusion coating

[0091] Single-layer extrusion coating was performed using the following temperature setting 1: Extruder -200°C / 250°C / 280°C / 290°C / 290°C / 290°C; Flange / Adapter / Piping -290°C (6 zones); and Die -290°C × 10 zones, representing the set temperature profile.

[0092] Polyethylene and polypropylene resins and blends are 25 g / m². 2 The amount (coating weight) is 70g / m2 The molten material was extruded onto kraft paper with a length-to-diameter (L / D) ratio of 32 onto a "3.5-inch" diameter screw, and the melting pressure and melting temperature were recorded using a thermocouple placed in the adapter. The molten material was delivered through a Davis Standard / Er-We-Pa flex-lip edge bead reduction die, Series 510A, set to a nominal die gap of 0.7 mm. Melt stretching and application (perpendicular to the moving molten substrate) was performed with a 250 mm gap and a 15 mm nip offset toward the pressure roll. The molten material was applied to the moving substrate within the laminator nip, which is the contact point with the pressure roll having a rubber surface layer and in contact with a "water-cooled" cooling roll having a matte surface finish, and maintained at a temperature of 15°C to 20°C. The gap is defined as the vertical distance between the die lip and the laminator nip. The nip offset is defined as the horizontal offset of the die lip position relative to the laminator nip. "Drawdown" was determined to be 15 g / m 2 A starting coating weight and a starting line speed of 100 m / min were used, along with a variable (gradually increasing) line speed. "Drawdown" is defined as the maximum line speed achievable before web breakage occurs. "Neck-in" is the difference between the final width of the web and the die width at fixed line speeds, e.g., 100 m / min and 300 m / min. Both lower "neck-in" and higher "drawdown" are highly desirable. Lower "neck-in" indicates better dimensional stability of the web, thereby providing better control over the coating onto the substrate. Higher "drawdown" indicates a higher line speed, which means higher productivity.

[0093] A first aspect of the present disclosure is a multilayer structure comprising an orientation film containing at least 90% by weight of polyethylene and a sealant layer on the orientation film, wherein the sealant layer comprises 15% to 40% by weight of low-density polyethylene based on the total weight of the sealant layer and 60% to 85% by weight of an ethylene-based elastomer based on the total weight of the sealant layer, and the ethylene-based elastomer of the sealant layer is 0.870 g / cm³ 3 ~0.911 g / cm³3 It comprises a multilayer structure having a density and a melt index (I2) of at least 3 g / 10 min.

[0094] A second aspect of the present disclosure is a multilayer structure comprising an orientation film containing at least 90% by weight of polyethylene and a sealant layer on the orientation film, wherein the sealant layer comprises 15% to 40% by weight of low-density polyethylene based on the total weight of the sealant layer and 60% to 85% by weight of propylene-based plastomer based on the total weight of the sealant layer, the propylene-based plastomer having a density of 0.890 g / cm³ 3 The material comprises a multilayer structure having the following density and a melt flow rate of at least 8 g / 10 min (at 230°C and 2.16 kg).

[0095] A third aspect of this disclosure includes any of the aforementioned aspects, wherein the low-density polyethylene of the sealant layer has a molecular weight distribution (Mw / Mn) of 7 to 13.

[0096] A fourth aspect of the present disclosure includes any of the above embodiments, wherein the low-density polyethylene of the sealant layer has a melt index (I2) of 1.5 to 9.

[0097] A fifth aspect of the present disclosure includes any of the aforementioned aspects, wherein the orientation film comprises two or more layers.

[0098] A sixth aspect of the present disclosure includes any of the above-described aspects, wherein the sealant layer is in adhesive contact with the orientation film.

[0099] A seventh aspect of the present disclosure includes any of the aforementioned aspects, further comprising a bonding layer, the bonding layer being positioned in contact between the sealant layer and the orientation film.

[0100] The eighth aspect of this disclosure is a binding layer having 0.923 g / cm³ 3 The present invention includes any of the above embodiments, comprising at least 60% by weight of polyethylene having the following density and a melt index (I2) of at least 4 g / 10 min.

[0101] A ninth aspect of the present disclosure includes any of the preceding aspects, wherein the binding layer further comprises at least 15% by weight of low-density polyethylene based on the total weight of the binding layer.

[0102] A tenth aspect of the present disclosure includes any of the aforementioned 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.

[0103] An eleventh aspect of this disclosure includes any of the aforementioned aspects, wherein the ethylene-based elastomer of the sealant layer has a melting point of 65°C to 100°C.

[0104] A twelfth aspect of this disclosure includes a propylene-based plastomer having a melt flow rate of 5 g / 10 min to 35 g / 10 min (at 230 °C and 2.16 kg).

[0105] A thirteenth aspect of the present disclosure includes any of the aforementioned aspects, wherein the propylene-based plastomer is a copolymer comprising propylene and ethylene units.

[0106] A fourteenth aspect of the present disclosure includes any of the aforementioned aspects, wherein the propylene plastomer has an ethylene content of 2% to 15% by weight.

[0107] A fifteenth aspect of the present disclosure includes any of the above embodiments, wherein the sealant layer is extruded onto an orientation film.

[0108] The subject matter of this disclosure is described in detail with reference to specific embodiments. It should be understood that any detailed description of the components or features of an embodiment does not necessarily imply that such component or feature is essential to that 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 subject matter set forth in the claims.

[0109] For the purposes of describing and defining this disclosure, the terms “about” or “approximately” are used in this disclosure to express the degree of inherent uncertainty that may arise from any quantitative comparison, value, measurement, or other expression. The terms “about” and / or “approximately” are also used in this disclosure to indicate the degree to which a quantitative expression may vary from the stated standard without altering the fundamental function of the subject matter in question.

[0110] Note that one or more of the following claims utilize the term “here” as a transitional clause. Note that for the purpose of defining the Art, this term is introduced into the claims as an unrestricted transitional clause used to introduce an enumeration of a set of structural features and should be interpreted similarly to the more commonly used unrestricted preamble term “including.”

[0111] Where a first component is described as "containing" a second component, it should be understood that in some embodiments, the first component is intended to "consist of" or "essentially consist of" its second component. Where a first component is described as "containing" a second component, it should be further understood that in some embodiments, the first component is intended to 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 more than 99% of its second component (where % can be by weight or by moles). The invention described in the original claims of this application is listed below. [1] A multilayer structure, An orientation film containing at least 90% by weight of polyethylene, The sealant layer on the orientation film, wherein the sealant layer is Based on the total weight of the sealant layer, 15% to 40% by weight of low-density polyethylene, The sealant layer contains 60% to 85% by weight of an ethylene-based elastomer based on the total weight of the sealant layer, wherein the ethylene-based elastomer in the sealant layer is 0.870 g / cm³. 3 ~0.911 g / cm³ 3 The density and melt index (I) of at least 3g / 10min 2 A sealant layer having, A multilayer structure comprising the above. [2] A multilayer structure, An orientation film containing at least 90% by weight of polyethylene, The sealant layer on the orientation film, wherein the sealant layer is Based on the total weight of the sealant layer, 15% to 40% by weight of low-density polyethylene, The sealant layer comprises 60% to 85% by weight of a propylene-based plastomer based on the total weight of the sealant layer, wherein the propylene-based plastomer is present in an amount of 0.890 g / cm³. 3 A sealant layer having the following density and a melt flow rate of at least 8 g / 10 min (at 230°C and 2.16 kg), A multilayer structure comprising the above. [3] The multilayer structure according to [1] or [2], wherein the low-density polyethylene of the sealant layer has a molecular weight distribution (Mw / Mn) of 7 to 13. [4] The low-density polyethylene of the sealant layer has a melt index of 1.5 to 9 (I 2 A multilayer structure according to any one of [1] to [3], having ) ). [5] The multilayer structure according to any one of [1] to [4], wherein the orientation film comprises two or more layers. [6] The multilayer structure according to any one of [1] to [5], wherein the sealant layer is in adhesive contact with the orientation film. [7] A multilayer structure according to any one of [1] to [6], further comprising a bonding layer, wherein the bonding layer is positioned in contact with the sealant layer and the orientation film. [8] The binding layer is 0.923 g / cm³ 3 The following densities and melt index (I) of at least 4g / 10min 2 The multilayer structure according to [7], comprising at least 60% by weight of polyethylene having ). [9] The multilayer structure according to [8], wherein the binding layer further comprises at least 15% by weight of low-density polyethylene based on the total weight of the binding layer.

[10] The ethylene-based elastomer in the sealant layer has a melt index of 3.0 g / 10 min to 30 g / 10 min (I 2 A multilayer structure as described in [1], having )

[11] The multilayer structure according to [1], wherein the ethylene-based elastomer of the sealant layer has a melting point of 65°C to 100°C.

[12] The multilayer structure according to [2], wherein the propylene-based plastomer has a melt flow rate of 5 g / 10 min to 35 g / 10 min (at 230 °C and 2.16 kg).

[13] The multilayer structure according to [2], wherein the propylene plastomer is a copolymer containing propylene and ethylene units.

[14] The multilayer structure according to

[13] , wherein the propylene plastomer has an ethylene content of 2% to 15% by weight.

[15] The multilayer structure according to [1], wherein the sealant layer is extruded onto the orientation film.

Claims

1. A multilayer structure, An orientation film containing at least 90% by weight of polyethylene, The sealant layer on the orientation film, wherein the sealant layer is Based on the total weight of the sealant layer, 25% to 40% by weight of low-density polyethylene, The sealant layer comprises 60% to 75% by weight of an ethylene-based elastomer based on the total weight of the sealant layer, wherein the ethylene-based elastomer in the sealant layer is 0.870 g / cm³. ３ ~0.911g / cm ３ The density and melt index (I) of at least 3 g / 10 min ２ ) has, The ethylene-based elastomer comprises a sealant layer containing more than 50 mol% of units derived from ethylene monomer, A multilayer structure comprising the above.

2. A multilayer structure, An orientation film containing at least 90% by weight of polyethylene, The sealant layer on the orientation film, wherein the sealant layer is Based on the total weight of the sealant layer, 15% to 40% by weight of low-density polyethylene, The sealant layer comprises 60% to 85% by weight of a propylene-based plastomer based on the total weight of the sealant layer, wherein the propylene-based plastomer is present in an amount of 0.890 g / cm³. ３ Having the following densities and a melt flow rate of at least 8 g / 10 min (at 230°C and 2.16 kg), The propylene-based elastomer comprises a sealant layer containing more than 70% by weight of units derived from propylene monomer, A multilayer structure comprising the above.

3. The multilayer structure according to claim 1 or 2, wherein the low-density polyethylene of the sealant layer has a molecular weight distribution of 7 to 13 (Mw / Mn).

4. The low-density polyethylene in the sealant layer has a melt index of 1.5 to 9 (I ２ A multilayer structure according to any one of claims 1 to 3, having )

5. The multilayer structure according to any one of claims 1 to 4, wherein the orientation film comprises two or more layers.

6. The multilayer structure according to any one of claims 1 to 5, wherein the sealant layer is in adhesive contact with the orientation film.

7. The multilayer structure according to any one of claims 1 to 6, further comprising a bonding layer, wherein the bonding layer is positioned in contact with the sealant layer and the orientation film.

8. The aforementioned binding layer is 0.923 g / cm³ ３ The following densities and melt index (I) of at least 4 g / 10 min ２ The multilayer structure according to claim 7, comprising at least 60% by weight of polyethylene having ).

9. The multilayer structure according to claim 8, wherein the binding layer further comprises at least 15% by weight of low-density polyethylene based on the total weight of the binding layer.

10. The ethylene-based elastomer in the sealant layer has a melt index (I) of 3.0 g / 10 min to 30 g / 10 min. ２ A multilayer structure according to claim 1, having ).

11. The multilayer structure according to claim 1, wherein the ethylene-based elastomer in the sealant layer has a melting point of 65°C to 100°C.

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

13. The multilayer structure according to claim 2, wherein the propylene-based plastomer is a copolymer containing propylene and ethylene units.

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

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

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