Laminate, packaging material, and package

Abstract

To provide a laminate excellent in recyclability and tearability.SOLUTION: A laminate having a structure in which a base material layer and a sealant layer are laminated in this order, or a structure in which a base material layer, an intermediate layer, and a sealant layer are laminated in this order, wherein the base material layer, the intermediate layer, and the sealant layer contain polyethylene, at least any of the base material layer and the sealant layer, the base material layer and the intermediate layer, and the intermediate layer and the sealant layer are laminated via a highly elastic adhesive layer, and a tensile modulus of the highly elastic adhesive layer is 1000MPa or more at 23 °C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laminate, a packaging material, and a package using the same. More specifically, the present disclosure relates to a laminate having excellent material recyclability and a small environmental impact, and a packaging material and a package using the same. [Background technology]

[0002] Packaging bags are made from a combination of various materials, taking into consideration the properties of the contents to be packaged, the amount of contents, post-processing to prevent deterioration of the contents, the form in which the packaging bag will be transported, how the packaging bag will be opened, and how it will be disposed of.

[0003] For example, in packaging bags for flexible packages using laminated films, a biaxially oriented film such as polypropylene or polyester is used in combination to provide the mechanical strength of the packaging bag, and a sealant film such as polyethylene, polypropylene, or ethylene-vinyl acetate copolymer is used to seal the contents of the packaging bag. Furthermore, to prevent deterioration of the contents, aluminum foil or an ethylene-vinyl alcohol copolymer is also laminated onto these films.

[0004] Laminates made from the various materials described above are designed with an emphasis on suitability for each process, from packaging the contents to transportation, storage, and opening. However, with the increasing awareness of environmental issues in recent years, emphasis has been placed on resource conservation, recyclability, and other features of various products, and similar functions are being sought for laminates used in packaging bags. Generally, packaging materials are considered to be highly recyclable when the proportion of the main resin in the material is 90% by mass or more. However, many conventional packaging materials are composed of multiple resin materials and, in some cases, paper and metal materials, and do not meet this standard, so they are not currently recycled.

[0005] Therefore, Patent Document 1 describes that in a laminate having a base material, an adhesive layer, and a heat-sealing layer, the base material and the heat-sealing layer are made of polyethylene. By making the base material and the heat-sealing layer out of the same material, it becomes easier to meet the recyclability standards. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-55157 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when a notch is provided in a packaging bag made from the laminate described in Patent Document 1 and an attempt is made to tear the packaging bag at the notch, a large force may be required to tear the bag, or the bag may not be able to be torn in the desired direction. Thus, conventional polyethylene-based laminates, which are considered to have excellent recyclability, have room for improvement in terms of tearability.

[0008] Therefore, an object of the present disclosure is to provide a laminate that has excellent recyclability and tearability, and a packaging material and a package that use the same. [Means for solving the problem]

[0009] The present disclosure is, for example, as follows. [1] A structure in which a base layer and a sealant layer are laminated in this order, the substrate layer and the sealant layer comprise polyethylene; the base material layer and the sealant layer are laminated via a highly elastic adhesive layer, A laminate in which the highly elastic adhesive layer has a tensile modulus of elasticity of 1000 MPa or more at 23°C. [2] A structure in which a base layer, an intermediate layer, and a sealant layer are laminated in this order, the substrate layer, the intermediate layer, and the sealant layer comprise polyethylene; At least one of the base material layer and the intermediate layer, and the intermediate layer and the sealant layer are laminated via a highly elastic adhesive layer, A laminate in which the highly elastic adhesive layer has a tensile modulus of elasticity of 1000 MPa or more at 23°C. [3] The laminate according to [1] or [2], wherein the tensile modulus of elasticity in the machine direction (MD) of the substrate layer is 300 MPa or more at 23°C. [4] The laminate according to any one of [1] to [3], wherein the sealant layer has a tensile modulus in the machine direction (MD) of 600 MPa or less at 23°C. [5] The laminate according to [2], wherein the intermediate layer has a tensile modulus in the machine direction (MD) of 300 MPa or more at 23°C. [6] The laminate according to any one of [1] to [5], wherein the base layer has a printed layer on at least one surface. [7] The laminate according to any one of [1] to [6], wherein the highly elastic adhesive layer has a thickness of 0.5 to 6 μm. [8] The laminate according to any one of [1] to [7], wherein the proportion of polyethylene in the laminate is 90% by mass or more. [9] A packaging material comprising the laminate according to any one of [1] to [8].

[10] A package comprising the packaging material described in [9] and contents contained in the packaging material. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a laminate that has excellent recyclability and tearability, and a packaging material and a package that use the same. That is, a packaging bag made from the laminate according to the present disclosure does not require a large force to tear, and can be torn in a desired direction. [Brief explanation of the drawings]

[0011] [Figure 1]1 is a cross-sectional schematic diagram showing one embodiment of a laminate according to the present disclosure. [Figure 2] 1 is a cross-sectional schematic diagram showing one embodiment of a laminate according to the present disclosure. [Figure 3] 1 is a cross-sectional schematic diagram showing one embodiment of a laminate according to the present disclosure. [Figure 4] FIG. 2 is a schematic diagram showing a test piece before and after a tear test. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described in detail, with reference to the drawings as needed. However, the present disclosure is not limited to the following embodiments.

[0013] <Laminate> FIG. 1 is a cross-sectional schematic diagram showing one embodiment of a laminate according to the present disclosure. The laminate 1 shown in FIG. 1 has a structure in which a base layer 10 and a sealant layer 30 are laminated in this order, and the base layer 10 and the sealant layer 30 are laminated via a highly elastic adhesive layer, which is a first adhesive layer 40.

[0014] FIG. 2 is a cross-sectional view showing another embodiment of the laminate of the present disclosure. The laminate 2 shown in Figure 2 has a structure in which a base material layer 10, an intermediate layer 20, and a sealant layer 30 are laminated in this order, with the base material layer 10 and the intermediate layer 20 being laminated via another adhesive layer, which is a first adhesive layer 40, and the intermediate layer 20 and the sealant layer 30 being laminated via a highly elastic adhesive layer, which is a second adhesive layer 50. The base material layer 10 has a protective layer 11 on its outer surface 10a side. The base material layer 10 has a printed layer 12 on its inner surface 10b side. The intermediate layer 20 has a vapor-deposited layer 14 on the sealant layer 30 side, and a gas barrier coating layer 15 on the vapor-deposited layer 14 .

[0015] FIG. 3 is a cross-sectional schematic view showing another embodiment of the laminate of the present disclosure. 3 is the laminate 2 without the gas barrier coating layer 15. When the second adhesive layer 50 is an adhesive (gas barrier adhesive) that can exhibit gas barrier properties after curing, it is possible to suppress deterioration of the gas barrier properties due to cracking of the vapor deposition layer 14 without providing the gas barrier coating layer 15.

[0016] 1 to 3, the base layer 10, the optional intermediate layer 20, and the sealant layer 30 are all made of polyethylene, so the proportion of polyethylene in the laminate is 90% by mass or more. This gives the laminate excellent recyclability. When the base layer 10, the optional intermediate layer 20, and the sealant layer 30 are all made of polyethylene, the proportion (% by mass) of polyethylene in the laminate can be calculated using the following formula (1): {(mass of the base layer 10 + optionally the mass of the intermediate layer 20 + the mass of the sealant layer 30) / mass of the entire laminate} × 100 ... (1)

[0017] 1 to 3 all have a highly elastic adhesive layer as an adhesive layer, and therefore have excellent tear resistance. Generally, laminates with a high proportion of polyethylene tend to be easy to stretch and difficult to tear. In such laminates, by interposing a highly elastic adhesive layer having a tensile modulus of elasticity of 1000 MPa or more at 23°C between the layers, the elongation of the laminate can be suppressed, making the laminate easier to tear. Each layer of the laminate will now be described.

[0018] (base material layer) The base layer is a layer containing polyethylene and may be a layer composed of a polyethylene film. The polyethylene film may be a film containing 70% by mass or more, or 85% by mass or more, of polyethylene, or may be a film containing 100% by mass of polyethylene.

[0019] The base layer is the portion that becomes the outer surface when a packaging material is formed using the laminate. However, as shown in Figure 2, the outer surface of the base layer may be protected by a protective layer. The surface of the base layer can be subjected to an easy-adhesion treatment by dry surface treatment such as corona treatment or atmospheric pressure plasma treatment.

[0020] From the viewpoint of good tearability and heat resistance, the tensile modulus of the base layer in the machine direction (MD) can be 300 MPa or more, 900 MPa or more, or 1200 MPa or more at 23° C. The upper limit of the tensile modulus is not particularly limited, but can be, for example, 3000 MPa or less.

[0021] The tensile modulus of a film is measured as follows. In accordance with JIS K7161, a tensile test is performed on a film having a size of 15 mm width x 5 cm length (length direction is MD) using, for example, an Orientec Tensilon universal testing machine RTC-1250, with a chuck distance of 5 cm and a tensile speed of 200 mm / min at 23°C. The slope of the stress / strain curve corresponding to the two strain points where the tensile elongation is from 0.05% to 0.25% is the tensile modulus of the film.

[0022] The tensile modulus of the base layer can be adjusted by, for example, adjusting the film forming method or stretching method of the polyethylene film, adjusting the type of polyethylene contained in the polyethylene film (molecular weight or density), or using a polyethylene film with a multilayer structure, but the method for adjusting the tensile modulus is not limited to these.

[0023] The base layer is made of high-density polyethylene (HDPE: density 0.94 g / cm 3A film made of any of the above materials can be used. Using a high-density polyethylene film makes it easier to meet the above tensile modulus. The high-density polyethylene film may be petroleum-derived, plant-derived, or a mixture of these. The density of the substrate layer is measured using a density measuring device, BELPYCNO, manufactured by Microtrack Bell Corporation.

[0024] It is also possible to use, as the substrate layer, a multilayer polyethylene film obtained by coextrusion of polyethylenes of different densities (e.g., a polyethylene other than high-density polyethylene / high-density polyethylene / polyethylene other than high-density polyethylene structure), or a multilayer polyethylene film obtained by coextrusion of polyethylene and a polyolefin other than polyethylene (e.g., a polypropylene / polyethylene / polypropylene structure). The use of such a multilayer polyethylene film having a core layer with a skin layer having different (flexible) properties on the surface thereof makes it easier to satisfy the above-mentioned tensile modulus. For example, from the viewpoint of easily satisfying the above-mentioned tensile modulus, the ratio of the core layer in the multilayer polyethylene film may be 70% by mass or more and 95% by mass or less. Alternatively, the ratio of the thickness of the core layer to the thickness of the multilayer polyethylene film may be 70% by mass or more and 95% or less.

[0025] The thickness of the substrate layer is preferably 10 to 50 μm, more preferably 12 to 35 μm, and even more preferably 20 to 30 μm. By making the thickness of the substrate layer 10 μm or more, the strength of the laminate can be improved. By making the thickness of the substrate layer 50 μm or less, the processability of the laminate can be improved.

[0026] The substrate layer can be produced by forming a polyethylene film by a T-die method, an inflation method, or the like.

[0027] The polyethylene film constituting the base layer may be a stretched film or a biaxially stretched film, from the viewpoint of easily satisfying the above-mentioned tensile modulus. Examples of the stretching method for the biaxially stretched film include sequential biaxial stretching, tubular biaxial stretching, and simultaneous biaxial stretching. From the viewpoint of easily satisfying the above-mentioned tensile modulus, the biaxially stretched film is preferably one stretched by simultaneous biaxial stretching.

[0028] The melting point of the polyethylene (e.g., high-density polyethylene) used as the base layer is approximately 120°C to 140°C. On the other hand, the melting point of the polyethylene (e.g., low-density polyethylene) used as the sealant layer (described later) is approximately 90°C to 120°C. To heat-seal this laminate of base layer and sealant layer, the heat seal bar, which is a tool of the heat sealing machine, is heated to approximately 130°C to 140°C, and the heat is transferred to the sealant layer through the base layer and the intermediate layer (described later), resulting in heat welding.

[0029] (protective layer) The protective layer is provided to prevent defects during heat sealing during bag making and filling / sealing, and to ensure heat sealing suitability. Specifically, it can suppress appearance defects such as wrinkles that occur when the base layer comes into contact with the heat seal bar, and adhesion (removal) of the base layer to the heat seal bar due to thermal welding. For this purpose, the protective layer may be provided as the outermost layer of the laminate.

[0030] The thickness of the protective layer is adjusted according to the total thickness of the laminate, but from the viewpoint of improving heat resistance and reducing the amount of heat required for heat sealing, it may be, for example, 0.1 to 5.0 μm, 0.2 to 4.0 μm, or 0.3 to 2.0 μm.

[0031] The protective layer provided on the outer surface of the base material layer must be heat resistant so that it does not soften, melt, decompose, or the like even when heated to, for example, 140°C during heat sealing. Therefore, the protective layer preferably contains a thermosetting resin or a resin with a melting point of 160°C or higher. The resin is preferably at least one resin selected from the group consisting of polyurethane, polyester, polyamide, polyamideimide, and epoxy.

[0032] Examples of means for forming the protective layer include a method of applying a dispersion in which the above-mentioned resin or its raw materials are dispersed in water, or a coating liquid in which the above-mentioned resin or its raw materials are dissolved in an organic solvent, to the base layer and drying (curing) it to form the protective layer, and a method of forming the base layer by co-extrusion with an adhesive resin such as maleic anhydride-modified polyethylene when forming the base layer into a film.

[0033] When a protective layer is formed by applying and drying (curing) a coating agent, an adhesion-imparting layer may be formed on the substrate layer to improve adhesion between the substrate layer and the protective layer, as long as recyclability is not impaired.

[0034] (Printing layer) The substrate layer may have a printed layer on at least one surface. That is, the printed layer can be formed on the outer surface of the substrate layer, which is the side on which the protective layer is formed, or on the inner surface, which is the side on which the intermediate layer or sealant layer is laminated. The method for forming the printed layer (image) is not particularly limited, and it can be formed by ordinary gravure printing, flexographic printing, or the like, using an appropriate ink. As ink, there are solvent-based inks and water-based inks, but it is preferable to use water-based inks from an environmental perspective. In addition, the outer surface or inner surface of the substrate layer may be subjected to a surface treatment such as corona treatment or plasma treatment to improve the adhesion of the printed layer.

[0035] (middle class) The intermediate layer is a layer containing polyethylene and may be a layer composed of a polyethylene film. The polyethylene film may be a non-oriented film or an oriented film (biaxially oriented film). The surface of the intermediate layer may be subjected to an easy-adhesion treatment by dry surface treatment such as corona treatment or atmospheric pressure plasma treatment.

[0036] Here, unstretched polyethylene film refers to a polyethylene film that is not stretched during film formation and has a structure in which spherical crystals (spherulites) of approximately 10 to 100 μm in size, composed of randomly folded polyethylene molecular chains, are connected by amorphous molecules. Unstretched polyethylene film has the property that, when subjected to a strong impact, the spherulites are broken, and the molecular chains are oriented and stretched, preventing the film itself from tearing. Therefore, packaging (made by fabricating a packaging bag, filling it with contents, and sealing it) made from a laminate in which unstretched polyethylene film is laminated as an intermediate layer and a sealant layer is characterized by excellent bag drop strength.

[0037] From the viewpoint of good tear resistance and heat resistance, the tensile modulus of the intermediate layer in the machine direction (MD) can be 300 MPa or more, 900 MPa or more, or 1200 MPa or more at 23° C. There is no particular upper limit to the tensile modulus, but it can be, for example, 3000 MPa or less.

[0038] The tensile modulus of the intermediate layer can be adjusted by various methods in the same manner as for the base layer.

[0039] The middle layer is made of high-density polyethylene (HDPE: density 0.94 g / cm 3A film made of any of the above materials can be used. By using a high-density polyethylene film, the above tensile modulus can be easily satisfied (for example, the range of the tensile modulus can be adjusted by the stretching method, etc.). The high-density polyethylene film may be derived from petroleum, plant, or a mixture of these. As with the base layer, the intermediate layer can also be a multilayered unstretched polyethylene film obtained by co-extruding polyethylenes of different densities.

[0040] The thickness of the intermediate layer is preferably 9 to 50 μm, more preferably 12 to 40 μm, and even more preferably 12 to 35 μm. By making the thickness of the intermediate layer 9 μm or more, the strength and heat resistance of the laminate can be improved. By making the thickness of the intermediate layer 50 μm or less, the processability of the laminate can be improved.

[0041] The intermediate layer 20 can be produced by forming a polyethylene film by a T-die method, an inflation method, or the like.

[0042] (vapor deposited layer) The intermediate layer may have a vapor-deposited layer on at least one surface. That is, a vapor-deposited layer may be formed on at least one surface of the intermediate layer. In FIG. 2, the vapor-deposited layer is formed on the surface of the intermediate layer facing the second adhesive layer, but it may also be formed on the opposite surface. The vapor-deposited layer imparts oxygen barrier properties and water vapor barrier properties to the laminate.

[0043] Examples of the vapor-deposited layer include a vapor-deposited layer made of a metal oxide such as aluminum oxide, silicon oxide, magnesium oxide, or tin oxide. From the viewpoints of transparency and barrier properties, the metal oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. Furthermore, from the viewpoint of cost, it is selected from aluminum oxide and silicon oxide. Furthermore, from the viewpoint of excellent tensile elongation during processing, it is more preferable to use a layer made of silicon oxide. By using a barrier film made of a metal oxide as the vapor-deposited layer, high barrier properties can be obtained with an extremely thin layer that does not affect the recyclability of the laminate.

[0044] A vapor-deposited layer made of a metal oxide has transparency, and therefore has the advantage that, compared to a vapor-deposited layer made of a metal, it is less likely to cause a user who holds a packaging material made of the laminate to mistakenly believe that a metal foil is used.

[0045] The thickness of the vapor-deposited layer made of aluminum oxide is preferably 5 to 30 nm. A thickness of 5 nm or more can provide sufficient gas barrier properties. Furthermore, a thickness of 30 nm or less can prevent cracks from occurring due to deformation caused by internal stress in the thin film, thereby preventing a decrease in gas barrier properties. Note that a thickness exceeding 30 nm is undesirable from an economic standpoint, as it increases the amount of material used and the time required for film formation, which tends to increase costs. From the same viewpoint as above, the thickness of the vapor-deposited layer made of aluminum oxide is more preferably 7 to 15 nm.

[0046] The thickness of the vapor-deposited layer made of silicon oxide is preferably 10 to 50 nm. A thickness of 10 nm or more can provide sufficient gas barrier properties. Furthermore, a thickness of 50 nm or less can prevent cracks from occurring due to deformation caused by internal stress in the thin film, thereby preventing a decrease in gas barrier properties. Note that a thickness exceeding 50 nm is undesirable from an economic standpoint, as it increases the amount of material used and the film formation time, which tends to increase costs. From the same viewpoint as above, the thickness of the vapor-deposited layer made of silicon oxide is more preferably 20 to 40 nm.

[0047] The deposition layer can be formed by, for example, vacuum film formation. In vacuum film formation, physical vapor deposition or chemical vapor deposition can be used. Examples of physical vapor deposition include, but are not limited to, vacuum deposition, sputtering, and ion plating. Examples of chemical vapor deposition include, but are not limited to, thermal CVD, plasma CVD, and photo CVD.

[0048] In the vacuum film formation, resistance heating vacuum evaporation, EB (Electron Beam) heating vacuum evaporation, induction heating vacuum evaporation, sputtering, reactive sputtering, dual magnetron sputtering, plasma enhanced chemical vapor deposition (PECVD), and the like are particularly preferably used. However, in terms of productivity, vacuum evaporation is currently the most superior. As a heating means for vacuum evaporation, it is preferable to use any of the electron beam heating method, resistance heating method, and induction heating method.

[0049] An anchor coating layer may be formed on the surface of the intermediate layer on which the vapor deposition layer is formed, using a known anchor coating agent. This can improve the adhesion of the vapor deposition layer. Examples of anchor coating agents include polyester-based polyurethane resins, polyether-based polyurethane resins, and acrylic urethane resins. From the viewpoints of heat resistance and interlayer adhesive strength, polyester-based polyurethane resins are preferred.

[0050] A polyvinyl alcohol resin may be used as the anchor coating agent. The polyvinyl alcohol resin may be any resin having a vinyl alcohol unit formed by saponifying a vinyl ester unit, such as polyvinyl alcohol (PVA) or ethylene-vinyl alcohol copolymer (EVOH).

[0051] When a polyvinyl alcohol resin is used as the anchor coating agent, methods for forming the anchor coating layer include coating with a polyvinyl alcohol resin solution, multilayer extrusion, etc. In the case of multilayer extrusion, lamination may be performed via an adhesive resin such as maleic anhydride-grafted modified polyethylene.

[0052] Furthermore, in order to improve adhesion to the first adhesive layer, the second adhesive layer, the vapor deposition layer, and the above-mentioned anchor coat layer, etc., the corresponding surfaces of the intermediate layer may be subjected to surface treatment such as corona treatment or plasma treatment.

[0053] (Gas barrier coating layer) A gas barrier coating layer may be provided on the vapor deposition layer for the purpose of improving the gas barrier property and protecting the vapor deposition layer. Although not particularly limited, the gas barrier coating layer may contain a hydroxyl group-containing polymer compound, and specifically may be a heat-dried product of a composition containing at least one of a hydroxyl group-containing polymer compound and a hydrolyzate thereof, and at least one selected from the group consisting of a metal alkoxide, a silane coupling agent, and a hydrolyzate thereof.

[0054] The gas barrier coating layer can be formed using a composition (hereinafter referred to as an overcoat agent) obtained by adding a hydroxyl group-containing polymer compound and a metal alkoxide and / or a silane coupling agent to water or a water / alcohol mixture. The overcoat agent can be prepared, for example, by mixing a solution of a hydroxyl group-containing polymer compound, which is a water-soluble polymer, in an aqueous (water or water / alcohol) solvent with a metal alkoxide and / or a silane coupling agent directly, or with a solution that has been previously treated, for example, by hydrolysis.

[0055] Examples of hydroxyl group-containing polymer compounds include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. Among these, polyvinyl alcohol (PVA) is preferred when used as an overcoat agent for the gas barrier coating layer, as it provides particularly excellent gas barrier properties.

[0056] Examples of metal alkoxides include compounds represented by the following general formula (I). M(OR 1 ) m (R 2 ) n-m …(I) In the above general formula (I), R 1 and R 2 are each independently a monovalent organic group having 1 to 8 carbon atoms, and are preferably an alkyl group such as a methyl group or an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, or Zr. m is an integer from 1 to n. 1 or R 2 If there are multiple, R 1 Comrades or R 2 They may be the same or different.

[0057] Specific examples of metal alkoxides include tetraethoxysilane [Si(OC2H5)4], triisopropoxyaluminum [Al(O-2'-C3H7)3], etc. Tetraethoxysilane and triisopropoxyaluminum are preferred because they are relatively stable in aqueous solvents after hydrolysis.

[0058] The silane coupling agent includes a compound represented by the following general formula (II). Si(OR 11 ) p (R 12 ) 3-p R 13 …(II) In the above general formula (II), R 11 represents an alkyl group such as a methyl group or an ethyl group, and R 12represents a monovalent organic group such as an alkyl group, an aralkyl group, an aryl group, an alkenyl group, an alkyl group substituted with an acryloxy group, or an alkyl group substituted with a methacryloxy group, and R 13 represents a monovalent organic functional group, and p represents an integer of 1 to 3. 11 or R 12 If there are multiple, R 11 Comrades or R 12 R may be the same or different. 13 Examples of the monovalent organic functional group represented by the formula (I) include a monovalent organic functional group containing a glycidyloxy group, an epoxy group, a mercapto group, a hydroxyl group, an amino group, an alkyl group substituted with a halogen atom, or an isocyanate group.

[0059] Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane.

[0060] The silane coupling agent may also be a polymer formed by polymerization of a compound represented by the general formula (II). A trimer is preferred as the polymer, and 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate is more preferred. This is a condensation polymer of 3-isocyanatoalkylalkoxysilane. It is known that 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate has no chemical reactivity in the isocyanate moiety, but the reactivity is ensured by the polarity of the nurate moiety. It is generally added to adhesives, similar to 3-isocyanatoalkylalkoxysilane, and is known as an adhesion improver. Therefore, adding 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate to a hydroxyl group-containing polymer compound can improve the water resistance of a gas barrier coating layer through hydrogen bonding. While 3-isocyanate alkyl alkoxysilanes are highly reactive and have low liquid stability, 1,3,5-tris(3-trialkoxysilylalkyl) isocyanurates are not water-soluble due to the polarity of the nurate moiety, but they are easily dispersed in aqueous solutions and can maintain stable liquid viscosity. Furthermore, the water resistance of 3-isocyanate alkyl alkoxysilanes and 1,3,5-tris(3-trialkoxysilylalkyl) isocyanurates is equivalent.

[0061] Some 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurates are produced by thermal condensation of 3-isocyanatepropylalkoxysilane, and may contain the raw material 3-isocyanatepropylalkoxysilane, but this does not pose any particular problems. 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate is more preferred, and 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate is even more preferred. Because the methoxy group hydrolyzes quickly and those containing the propyl group are relatively inexpensive, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate is practically advantageous.

[0062] The amount of metal alkoxide in the overcoating agent can be 1 to 4 parts by mass, or may be 2 to 3 parts by mass, per part by mass of the hydroxyl-containing polymeric compound, from the viewpoints of maintaining adhesion to the vapor-deposited layer and gas barrier properties. Similarly, the amount of silane coupling agent can be 0.01 to 1 part by mass, or may be 0.1 to 0.5 parts by mass, per part by mass of the hydroxyl-containing polymeric compound. When a silane compound (alkoxysilane) is used as the metal alkoxide, the amount of the silane compound (metal alkoxide and silane coupling agent) in the overcoating agent can be 1 to 4 parts by mass, or may be 2 to 3 parts by mass, per part by mass of the hydroxyl-containing polymeric compound.

[0063] If necessary, known additives such as an isocyanate compound, a dispersant, a stabilizer, a viscosity modifier, a colorant, etc. may be added to the overcoating agent within a range that does not impair the gas barrier properties.

[0064] The overcoating agent can be applied by, for example, dipping, roll coating, gravure coating, reverse gravure coating, air knife coating, comma coating, die coating, screen printing, spray coating, gravure offset, etc. The coating film obtained by applying the overcoating agent can be dried by, for example, hot air drying, heat roll drying, high frequency irradiation, infrared irradiation, UV irradiation, or a combination thereof.

[0065] The temperature at which the coating film is dried can be, for example, 50 to 150° C., and preferably 70 to 100° C. By keeping the drying temperature within the above range, the occurrence of cracks in the vapor deposition layer or gas barrier coating layer can be further suppressed, and excellent barrier properties can be achieved.

[0066] The gas barrier coating layer may be formed using an overcoating agent containing a hydroxyl group-containing polymer compound (e.g., polyvinyl alcohol resin) and a silane compound. The overcoating agent may contain an acid catalyst, an alkali catalyst, a photopolymerization initiator, etc., as needed.

[0067] Examples of the silane compound include a silane coupling agent, polysilazane, and siloxane, and specific examples include tetramethoxysilane, tetraethoxysilane, glycidoxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, and hexamethyldisilazane.

[0068] The thickness of the gas barrier coating layer is preferably 50 to 1000 nm, more preferably 100 to 500 nm. When the thickness of the gas barrier coating layer is 50 nm or more, more sufficient gas barrier properties tend to be obtained, and when it is 1000 nm or less, sufficient flexibility tends to be maintained.

[0069] (sealant layer) The sealant layer is a layer containing polyethylene and may be a layer composed of a polyethylene film. The sealant layer is bonded by heat sealing when a packaging material such as a packaging bag is formed using the laminate. From the viewpoint of heat sealing properties, the polyethylene constituting the sealant layer is preferably low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or very low-density polyethylene (VLDPE). Furthermore, from the viewpoint of environmental impact, it is preferable that biomass-derived polyethylene or recycled polyethylene is used for the sealant layer. The sealant layer may be composed of a non-oriented polyethylene film. The surface of the intermediate layer can be subjected to an easy-adhesion treatment by dry surface treatment such as corona treatment or atmospheric pressure plasma treatment.

[0070] Low density polyethylene has a density of 0.900 g / cm 3 More than 0.925g / cm 3 As the linear low density polyethylene, polyethylene having a density of 0.900 g / cm3 or less can be used. 3 More than 0.925g / cm 3 Ultra-low density polyethylene can be used with a density of 0.900 g / cm. 3For the sealant layer, a copolymer of ethylene and other monomers can be used as long as the properties of the laminate are not impaired.

[0071] The thickness of the sealant layer can be changed appropriately depending on the weight of the contents to be filled into the packaging material to be produced. For example, when producing a packaging bag to be filled with 1 to 200 g of contents, the thickness of the sealant layer is preferably 20 to 60 μm. By making the thickness 20 μm or more, it is possible to prevent the filled contents from leaking due to damage to the sealant layer. By making the thickness 60 μm or less, it is possible to improve the processability of the laminate.

[0072] As another example, when producing a standing pouch to be filled with 50 to 2000 g of contents, the thickness of the sealant layer is preferably 50 to 200 μm. By making the thickness 50 μm or more, it is possible to prevent the filled contents from leaking due to damage to the sealant layer. Furthermore, by making the thickness 200 μm or less, preferably 150 μm or less, it is possible to improve the processability of the laminate.

[0073] From the viewpoint of good tearability and bag-forming suitability, the tensile modulus of the sealant layer in the machine direction (MD) can be 600 MPa or less, or alternatively 500 MPa or less, or 400 MPa or less at 23° C. There is no particular lower limit to the tensile modulus, but it can be, for example, 200 MPa or more.

[0074] The tensile modulus of the sealant layer can be adjusted by various methods in the same manner as for the base layer.

[0075] The polyethylene used in the substrate layer, intermediate layer, and sealant layer may contain additives such as antioxidants, antistatic agents, nucleating agents, and ultraviolet absorbers.

[0076] The sealant layer may be transparent or opaque. In the latter case, the sealant layer is preferably white. A laminate having a transparent sealant layer allows easy visual confirmation of the contents when used as a packaging material. A laminate having an opaque sealant layer tends to improve the visibility of the image displayed by the printing layer when used as a packaging material.

[0077] (Adhesive layer: High elasticity adhesive layer) The highly elastic adhesive layer is a layer formed from at least one type of adhesive, and is provided between the substrate layer and the sealant layer, between the substrate layer and the intermediate layer, or between the intermediate layer and the sealant layer to bond them together. Examples of adhesives for forming the highly elastic adhesive layer include polyether adhesives, polyester adhesives, silicone adhesives, polyamine adhesives, epoxy adhesives, urethane adhesives, rubber adhesives, vinyl adhesives, phenol adhesives, olefin adhesives, etc. Adhesives containing biomass components can also be preferably used.

[0078] The adhesive used to form the highly elastic adhesive layer may be an adhesive (gas barrier adhesive) that can exhibit gas barrier properties after curing. In other words, the highly elastic adhesive layer may contain a gas barrier adhesive, and may be said to be a cured product of the gas barrier adhesive. In particular, when the highly elastic adhesive layer that comes into contact with the vapor deposition layer is formed using an adhesive that exhibits gas barrier properties, it is possible to further suppress deterioration of the gas barrier properties due to cracking of the vapor deposition layer. This can further improve the gas barrier performance of the laminate. Examples of gas barrier adhesives include epoxy adhesives and polyester / polyurethane adhesives, with epoxy adhesives that use amines as a curing agent being preferred.

[0079] From the viewpoint of good tearability, the tensile modulus of the highly elastic adhesive layer at 23°C can be 1000 MPa or more, or alternatively 1200 MPa or more, 1300 MPa or more, or 1400 MPa or more. From the viewpoint of adhesiveness as an adhesive layer, the tensile modulus at 23°C can be 2500 MPa or less, or alternatively 2200 MPa or less, 2000 MPa or less, or 1800 MPa or less.

[0080] The tensile modulus of the highly elastic adhesive layer is measured as follows. In accordance with JIS K7161, a tensile test is performed on an adhesive coating film having dimensions of 15 mm width x 5 cm length x 40 μm thickness using, for example, an Orientec Tensilon universal testing machine RTC-1250, with a chuck distance of 5 cm and a tensile speed of 200 mm / min at 23°C. The slope of the stress / strain curve corresponding to the two strain points where the tensile elongation is from 0.05% to 0.25% is taken as the tensile modulus of elasticity of the adhesive coating (of the high-elasticity adhesive layer).

[0081] The tensile modulus of the highly elastic adhesive layer can be adjusted, for example, in the case of an epoxy-based adhesive, by changing the compounding ratio of epoxy to amines, which are common curing agents. By increasing the compounding ratio of epoxy, the tensile modulus of the highly elastic adhesive layer can be increased, while by decreasing the compounding ratio of epoxy (increasing the compounding ratio of amines), the tensile modulus of the highly elastic adhesive layer can be decreased. However, the method for adjusting the tensile modulus is not limited to these.

[0082] The thickness of the highly elastic adhesive layer is preferably 0.5 to 6 μm, more preferably 0.8 to 5 μm, and even more preferably 1.0 to 4.5 μm. By making the thickness of the highly elastic adhesive layer 0.5 μm or more, the adhesiveness of the highly elastic adhesive layer can be improved. By making the thickness of the highly elastic adhesive layer 6 μm or less, the processability of the laminate can be improved.

[0083] (adhesive layer: other adhesive layer) The other adhesive layer is a layer containing at least one type of adhesive and is provided between the base layer and the intermediate layer, or between the intermediate layer and the sealant layer, to bond them together. For example, either a one-component curing or two-component curing urethane adhesive can be used to form the other adhesive layer. In addition, both solvent-based and solventless adhesives can be used to form the other adhesive layer.

[0084] When another adhesive layer is provided between the substrate layer and the intermediate layer, the other adhesive layer may be formed using a solvent-free adhesive in order to suppress dimensional changes in the printed image of the printing layer during lamination. Examples of solvent-free adhesives include urethane-based adhesives, epoxy-based adhesives, and silicone-based adhesives. From the viewpoint of impact resistance, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are particularly preferred.

[0085] The two-component curing urethane-based solventless adhesive contains a polyol component as a base component and a polyisocyanate component as a curing agent.

[0086] The polyol component may be one or a mixture of two or more selected from the group consisting of polyester polyols, polyether polyols, polyether ester polyols, and polyurethane polyols.

[0087] The polyester polyol may be, for example, an ester reaction product of a polycarboxylic acid, a dialkyl ester of a polycarboxylic acid, or a mixture thereof with a glycol-based solvent. The polycarboxylic acid may be, for example, succinic acid, glutaric acid, isophthalic acid, terephthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, or dimer acid. The glycol-based solvent may be, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butylene glycol, neopentyl glycol, or 1,6-hexanediol.

[0088] The polyether polyol may be, for example, a polymer of an oxirane compound and a low-molecular-weight polyol. The oxirane compound may be, for example, ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran. The low-molecular-weight polyol may be, for example, water, ethylene glycol, propylene glycol, trimethylolpropane, or glycerin.

[0089] The polyetherester polyol may be obtained by reacting, for example, a polycarboxylic acid, a dialkyl ester of a polycarboxylic acid, or a mixture thereof with a polyether polyol.

[0090] The polyurethane polyol may be, for example, the reaction product of a polyester polyol, a polyether polyol, a polyetherester polyol, and a polyisocyanate monomer.

[0091] The polyisocyanate component may be an aliphatic polyisocyanate, an aromatic polyisocyanate, or a mixture thereof.

[0092] The aliphatic polyisocyanate may be, for example, a polyisocyanate monomer, a polyisocyanate derivative, or a polyisocyanate-terminated prepolymer. The polyisocyanate monomer may be, for example, tetramethylene diisocyanate, isopropylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, or trimethylhexamethylene diisocyanate. The polyisocyanate derivative may be, for example, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, lysine diisocyanate, or isophorone diisocyanate.

[0093] The aromatic polyisocyanate may be, for example, a polyisocyanate monomer, a polyisocyanate derivative, or a polyisocyanate-terminated prepolymer. The polyisocyanate monomer may be, for example, tolylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, or tetramethylxylylene diisocyanate. The polyisocyanate derivative may be, for example, an isocyanurate derived from the polyisocyanate monomer. The polyisocyanate-terminated prepolymer may be a bifunctional polyisocyanate containing terminal isocyanate groups obtained by reacting a polyisocyanate monomer with a bifunctional polyol compound such as polypropylene glycol. The polyisocyanate-terminated prepolymer may also be a multifunctional polyisocyanate containing terminal isocyanate groups obtained by reacting a polyisocyanate monomer with a trifunctional or higher polyol compound such as trimethylolpropane.

[0094] The other adhesive layer may be formed using a solvent-based adhesive from the viewpoint of resistance to the contents. Examples of solvent-based adhesives include urethane-based adhesives, epoxy-based adhesives, and silicone-based adhesives. From the viewpoint of impact resistance, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are particularly preferred. The solvent used in the solvent-based adhesive is not particularly limited, and examples thereof include ethyl acetate, methanol, isopropyl alcohol, methyl ethyl ketone, and ethanol.

[0095] The adhesive used to form the other adhesive layer may be an adhesive (gas barrier adhesive) that can exhibit gas barrier properties after curing. In other words, the other adhesive layer may contain a gas barrier adhesive, and may be said to be a cured product of the gas barrier adhesive. In particular, if the other adhesive layer that comes into contact with the vapor deposition layer is formed using an adhesive that exhibits gas barrier properties, it is possible to further suppress deterioration of the gas barrier properties due to cracking of the vapor deposition layer. This can further improve the gas barrier performance of the laminate. Gas barrier adhesives include epoxy adhesives, polyester / polyurethane adhesives, and polyamine adhesives.

[0096] The thickness of the other adhesive layer is preferably 0.5 to 6 μm, more preferably 0.8 to 5 μm, and even more preferably 1.0 to 4.5 μm. By making the thickness of the other adhesive layer 0.5 μm or more, the adhesiveness of the other adhesive layer can be improved. By making the thickness of the other adhesive layer 6 μm or less, the processability of the laminate can be improved.

[0097] When the laminate has a two-layer structure (a substrate layer and a sealant layer), a highly elastic adhesive layer is used as the first adhesive layer (between the substrate layer and the sealant layer). When the laminate has a three-layer structure (substrate layer, intermediate layer, and sealant layer), another adhesive layer may be used as the first adhesive layer (between the substrate layer and the intermediate layer) and a highly elastic adhesive layer may be used as the second adhesive layer (between the intermediate layer and the sealant layer), a highly elastic adhesive layer may be used as the first adhesive layer and another adhesive layer may be used as the second adhesive layer, or a highly elastic adhesive layer may be used as both the first adhesive layer and the second adhesive layer.

[0098] The coating weight (weight per unit area) of each adhesive layer is 0.5 to 3.0 g / m 2 is preferred, and 1.0 to 2.0 g / m 2 The coating weight of the adhesive layer is more preferably 0.5 g / m 2 If the coating weight of the adhesive layer is 3.0 g / m or more, the effect of suppressing delamination between layers can be improved. 2 If the thickness is equal to or less than this, it is possible to prevent the occurrence of winding misalignment during processing of the laminate, and it is possible to improve the appearance quality of the laminate, and in addition, appropriate lamination strength is obtained.

[0099] Each adhesive layer can be formed by various known methods such as direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine method, and transfer roll coating.

[0100] <Packaging materials> A packaging material (packaging bag) made of the laminate can be formed by folding one laminate with the sealant layers facing each other, or by stacking two laminates with the sealant layers facing each other, and then heat-sealing the sealant layers at the periphery, leaving the filled portion for the contents. By sandwiching the folded bottom film and performing the above-described joining, a standing pouch can be formed as a packaging material. It can also be used for various other packaging bags, such as pillow packaging bags, four-side sealed packaging bags, three-side sealed packaging bags, and gusset bags. In this way, the laminate can be used for various packaging materials.

[0101] <Package> The package includes the above-mentioned packaging material and contents accommodated in the packaging material. A packaging bag made from the above-mentioned laminate, filled with contents, and sealed is resistant to external impact and the contents are less likely to leak. Examples of the contents include food-related liquid seasonings, beverages, jellies, etc., and non-food-related liquids such as detergents, shampoos, conditioners, lotions, emulsions, disinfectants, etc.

[0102] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, the laminate may not include one or more of the printed layer, intermediate layer, vapor deposition layer, and gas barrier coating layer. If the laminate does not include the intermediate layer, the second adhesive layer is not necessary, and the vapor deposition layer may be provided on the substrate layer. [Example]

[0103] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0104] (Preparation of base layer) A biaxially oriented high-density polyethylene film having a thickness of 30 μm and having been corona-treated on one side was prepared as a substrate layer. The tensile modulus of the film in the machine direction (MD) was 1430 MPa at 23°C. A printing layer (thickness 1 μm) was formed on the corona treated surface on the inner side of the base material layer by gravure printing using a urethane ink.

[0105] (Preparing the middle layer) A 32 μm-thick unstretched high-density polyethylene film, corona-treated on both sides, was used as the intermediate layer. The tensile modulus of the film in the machine direction (MD) was 600 MPa at 23°C.

[0106] (Preparation of sealant layer) A 120 μm-thick, unstretched linear low-density polyethylene film, one side of which had been corona-treated, was used as the sealant layer. The tensile modulus of the film in the machine direction (MD) was 330 MPa at 23°C.

[0107] (Preparing the epoxy adhesive) A solvent-based epoxy adhesive was used as the highly elastic adhesive. An amine resin was used as the curing agent, and the epoxy / amine ratio was 1 / 3 (weight ratio of the base resin to the curing agent).

[0108] (Preparing urethane adhesive) 100 parts by mass of Takelac A525 manufactured by Mitsui Chemicals, Inc. were mixed with 11 parts by mass of Takenate A52 manufactured by Mitsui Chemicals, Inc. and 84 parts by mass of ethyl acetate to prepare a solvent-based urethane adhesive as another adhesive.

[0109] Example 1 The surface of the base layer on which the printed layer was formed was adhered to the sealant layer by dry lamination using an epoxy adhesive. The thickness of the formed first adhesive layer (highly elastic adhesive layer) was 2.1 μm, and the tensile modulus of elasticity was 1432.3 MPa at 23°C. The flow directions of the base layer and the sealant layer were aligned. A laminate was obtained as described above.

[0110] Example 2 The printed surface of the substrate layer was bonded to the intermediate layer by dry lamination using a urethane adhesive. The thickness of the first adhesive layer (another adhesive layer) formed was 3.1 μm, and the tensile modulus of elasticity was 1.5 MPa at 23°C.

[0111] Next, the intermediate layer and the corona-treated surface of the sealant layer were bonded by dry lamination using an epoxy adhesive. The thickness of the formed second adhesive layer (high-elasticity adhesive layer) was 2.1 μm, and the tensile modulus of elasticity was 1432.3 MPa at 23°C. The flow directions of the substrate layer, intermediate layer, and sealant layer were aligned. A laminate was obtained in this manner.

[0112] Example 3 A laminate was obtained in the same manner as in Example 2, except that the urethane adhesive and the epoxy adhesive were used interchangeably.

[0113] Example 4 A laminate was obtained in the same manner as in Example 2, except that an epoxy adhesive was used instead of the urethane adhesive.

[0114] (Comparative Example 1) A laminate was obtained in the same manner as in Example 1, except that a urethane adhesive was used instead of the epoxy adhesive.

[0115] (Comparative Example 2) A laminate was obtained in the same manner as in Example 2, except that a urethane adhesive was used instead of the epoxy adhesive.

[0116] <Evaluation> (Recyclability) The proportion (mass %) of polyethylene in the laminate of each example was calculated based on the following formula (1). In all examples, the polyethylene content was 90 mass % or more. {(mass of base layer + mass of intermediate layer (if applicable) + mass of sealant layer) / mass of entire laminate} × 100 ... (1)

[0117] (Tearability) The laminate obtained in each example was processed to a size of 150 mm long (machine direction) x 50 mm short. A 75 mm long slit was made in the center of the short side of the processed laminate, parallel to the long side. In this way, a test piece was obtained. According to JIS K7128-1 "Plastics - Testing methods for tear strength of films and sheets - Part 1: Trouser tearing method," the amount of displacement and tear strength were measured when the test piece was torn along the machine direction. The evaluation results are shown in Table 1. [Gap evaluation criteria] ○: Within 10mm △: Over 10mm to less than 20mm ×: More than 20mm [Tear strength evaluation criteria] ○: 40N or less △: Over 40N to less than 100N ×: 100N or more

[0118] Figure 4 is a schematic diagram showing the test piece before and after the tear test. Figure 4(a) shows the state of the test piece before the tear test, and Figure 4(b) shows the state of the test piece after the tear test. As shown in Figure 4(b), the test piece is torn from start point S to end point E. The displacement is the length from point P on the extension line of the slit to end point E.

[0119] [Table 1]

[0120] As shown in Table 1, the examples using adhesive layers having predetermined tensile moduli were not only excellent in recyclability but also in tearability. [Explanation of symbols]

[0121] 1, 2, 3... laminate, 10... base material layer, 10a... outer surface of base material layer, 10b... inner surface of base material layer, 11... protective layer, 12... printed layer, 14... vapor deposition layer, 15... gas barrier coating layer, 20... intermediate layer, 30... sealant layer, 40... first adhesive layer, 50... second adhesive layer.

Claims

1. A structure in which a base layer and a sealant layer are laminated in this order, the substrate layer and the sealant layer comprise polyethylene; the base material layer and the sealant layer are laminated via a highly elastic adhesive layer, A laminate in which the highly elastic adhesive layer has a tensile modulus of elasticity of 1000 MPa or more at 23°C.

2. A structure in which a base layer, an intermediate layer, and a sealant layer are laminated in this order, the substrate layer, the intermediate layer, and the sealant layer comprise polyethylene; At least one of the base material layer and the intermediate layer, and the intermediate layer and the sealant layer are laminated via a highly elastic adhesive layer, A laminate in which the highly elastic adhesive layer has a tensile modulus of elasticity of 1000 MPa or more at 23°C.

3. The laminate according to claim 1 or 2, wherein the base layer has a tensile modulus in the machine direction (MD) of 300 MPa or more at 23°C.

4. 3. The laminate according to claim 1, wherein the sealant layer has a tensile modulus in the machine direction (MD) of 600 MPa or less at 23°C.

5. The laminate according to claim 2, wherein the intermediate layer has a tensile modulus in the machine direction (MD) of 300 MPa or more at 23°C.

6. The laminate according to claim 1 or 2, wherein the substrate layer has a printed layer on at least one surface thereof.

7. 3. The laminate according to claim 1, wherein the highly elastic adhesive layer has a thickness of 0.5 to 6 μm.

8. 3. The laminate according to claim 1, wherein the proportion of polyethylene in the laminate is 90% by mass or more.

9. A packaging material comprising the laminate according to claim 1 or 2.

10. A package comprising the packaging material according to claim 9 and contents contained in the packaging material.

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