Sealant films, laminates, and packaging containers

Abstract

To provide a sealant film which can be suitably used as a sealant layer in a packaging material, can reduce environmental load and is excellent in both low-temperature sealability and cuttability.SOLUTION: There is provided a sealant film having a first surface and a second surface opposite to the first surface, wherein the sealant film has a first layer constituting the first surface and a second layer, the first layer is a surface layer on one side in the sealant film, the first layer contains a linear low density polyethylene having a density of 0.910 g / cm3 or less, the second layer contains at least a copolymer of ethylene and an α-olefin having 4 carbon atoms as a linear low density polyethylene and at least one selected from the linear low density polyethylene contained in the first layer and the copolymer of ethylene and an α-olefin having 4 carbon atoms contained in the second layer is a biomass-derived polyethylene.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a sealant film, a laminate, and a packaging container.

Background Art

[0002] Film products are manufactured by laminating films of different materials (for example, a polyester film as a base material and a polyethylene film as a sealant layer) in order to exhibit various functions (for example, see Patent Document 1). Packaging containers are produced from such film products.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, efforts to address environmental problems such as plastic marine pollution and global warming have been emphasized. Therefore, high recyclability is required for packaging materials and the like. However, film products manufactured by laminating films of different materials are generally difficult to separate into their respective films, and there is a problem that they are difficult to recycle. In order to solve this problem, a technique called mono-materialization has been studied, in which the recyclability is improved by manufacturing film products by laminating polyethylene films of the same kind of material.

[0005] Monomaterialization using polyethylene can be achieved by laminating polyethylene films with different properties together. For example, by laminating a stretched polyethylene film (hereinafter also referred to as "stretched polyethylene film") which serves as a heat-resistant base material with a polyethylene film that serves as a heat-sealable sealant layer.

[0006] When using stretched polyethylene film as a base material instead of heat-resistant films such as polyester film, it is desirable to perform heat sealing at a low temperature to suppress thermal degradation of the base material during heat sealing. However, with conventional sealant layers, sufficient heat seal strength could not be obtained when heat sealing was performed at low temperatures.

[0007] The disclosers considered using a polyethylene film containing low-density polyethylene as a sealant layer to enable heat sealing at low temperatures, but found that this reduced the cutability (tearability) of the sealant layer. In other words, there is a trade-off relationship between low-temperature sealing ability and cutability in the sealant layer. Furthermore, from the perspective of addressing environmental issues, there is a demand for packaging materials with a low environmental impact.

[0008] One of the problems addressed by this disclosure is to provide a sealant film that can be suitably used as a sealant layer in packaging materials, reduces environmental impact, and exhibits excellent low-temperature sealing properties and cutability. [Means for solving the problem]

[0009] The sealant film of this disclosure has a first surface and a second surface opposite to the first surface. The sealant film comprises a first layer constituting the first surface and a second layer. The first layer is the surface layer on one side of the sealant film. The first layer has a density of 0.910 g / cm³ 3The following linear low-density polyethylene is included. The second layer contains at least a copolymer of ethylene and a carbon-4 α-olefin as the linear low-density polyethylene. At least one selected from the linear low-density polyethylene contained in the first layer and the copolymer of ethylene and a carbon-4 α-olefin contained in the second layer is biomass-derived polyethylene. [Effects of the Invention]

[0010] This disclosure provides a sealant film that is excellent in both low-temperature sealing properties and cutability. Such a sealant film can be suitably used, for example, as a sealant layer in packaging materials, and can also reduce the environmental impact of packaging materials. [Brief explanation of the drawing]

[0011]

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[0012] The embodiments of this disclosure will be described in detail below. This disclosure can be implemented in many different forms and is not construed as being limited to the embodiments described below. The drawings may schematically represent the width, thickness, and shape of each layer, etc., compared to the embodiments, in order to clarify the explanation, but these are merely examples and do not limit the interpretation of this disclosure. In this specification and in each figure, elements similar to those already described in the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0013] In this disclosure, polyethylene refers to a polymer in which the content of ethylene-derived structural units is 50 mol% or more of the total repeating structural units. In this polymer, the content of ethylene-derived structural units is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. The above content can be measured by NMR spectroscopy.

[0014] In this disclosure, polyethylene may be a homopolymer of ethylene, or a copolymer of ethylene and an ethylenically unsaturated monomer other than ethylene. Examples of ethylenically unsaturated monomers other than ethylene include α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene; vinyl monomers such as vinyl acetate and vinyl propionate; and (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate.

[0015] Examples of polyethylene in this disclosure include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene.

[0016] In this disclosure, the density of the polyethylene is as follows: The density of high-density polyethylene is preferably 0.945 g / cm 3 or higher. The upper limit of the density of high-density polyethylene is, for example, 0.965 g / cm 3 . The density of medium-density polyethylene is preferably 0.927 g / cm 3 or higher and less than 0.945 g / cm 3 . The density of low-density polyethylene is preferably 0.900 g / cm 3 or higher and less than 0.927 g / cm 3 . The density of linear low-density polyethylene is preferably 0.900 g / cm 3 or higher and less than 0.927 g / cm 3 . The density of ultra-low-density polyethylene is preferably less than 0.900 g / cm 3 . The lower limit of the density of ultra-low-density polyethylene is, for example, 0.860 g / cm 3 . The density of polyethylene is measured in accordance with JIS K7112, particularly Method D (density gradient tube method, 23°C).

[0017] Low-density polyethylene is usually polyethylene obtained by polymerizing ethylene by the high-pressure polymerization method, that is, high-pressure method low-density polyethylene. Linear low-density polyethylene is usually polyethylene obtained by polymerizing ethylene and a small amount of α-olefin using a multi-site catalyst typified by a Ziegler-Natta catalyst or a single-site catalyst typified by a metallocene catalyst.

[0018] Polyethylenes with different densities or degrees of branching can be obtained by appropriately selecting the polymerization method. For example, as the polymerization catalyst, using a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst, it is preferable to carry out polymerization in one stage or in multiple stages of two or more stages by any of the methods of gas-phase polymerization, slurry polymerization, solution polymerization, and high-pressure ionic polymerization.

[0019] A single-site catalyst is a catalyst capable of forming a uniform active species, and is usually prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activation co-catalyst. Compared to multi-site catalysts, single-site catalysts are preferred because they have a more uniform active site structure, allowing for the production of polymers with high molecular weight and high uniformity.

[0020] As a single-site catalyst, a metallocene catalyst is preferred. The metallocene catalyst is a catalyst comprising a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a co-catalyst, an organometallic compound if necessary, and a support if necessary.

[0021] Examples of transition metals in transition metal compounds include zirconium, titanium, and hafnium, with zirconium and hafnium being preferred.

[0022] In transition metal compounds, the cyclopentadienyl skeleton is a cyclopentadienyl group or a substituted cyclopentadienyl group. A substituted cyclopentadienyl group has at least one substituent selected from, for example, a hydrocarbon group having 1 to 30 carbon atoms, a silyl group, a silyl-substituted alkyl group, a silyl-substituted aryl group, a cyano group, a cyanoalkyl group, a cyanoaryl group, a halogen group, a haloalkyl group, and a halosilyl group. A substituted cyclopentadienyl group has one or more substituents, and the substituents may bond to each other to form a ring, which may form an indenyl ring, a fluorenyl ring, an azlenyl ring, or a hydrogenated version thereof. The ring formed by the bonding of substituents may further have substituents.

[0023] Transition metal compounds typically have two ligands having a cyclopentadienyl skeleton. Preferably, each ligand having a cyclopentadienyl skeleton is bonded to one another by a bridging group. Examples of bridging groups include alkylene groups having 1 to 4 carbon atoms, silylene groups, substituted silylene groups such as dialkylsilylene groups and diarylsilylene groups, and substituted germylene groups such as dialkylgermylene groups and diarylgermylene groups. Among these, substituted silylene groups are preferred.

[0024] A co-catalyst is a component that can effectively enable transition metal compounds of Group IV of the periodic table to function as polymerization catalysts, or a component that can balance the ionic charge in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes or benzene-insoluble organoaluminum oxy compounds, ion-exchangeable layered silicates, boron compounds, ionic compounds consisting of cations containing or not containing active hydrogen groups and non-coordinating anions, lanthanide salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing fluoro groups.

[0025] Examples of organometallic compounds that may be used as needed include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Among these, organoaluminum compounds are preferred.

[0026] Transition metal compounds may be used supported on an inorganic or organic compound. Preferred supports are porous oxides of inorganic or organic compounds, specifically ion-exchangeable layered silicates such as montmorillonite, SiO2, Al2O3, MgO, ZrO2, TiO2, B2O3, CaO, ZnO, BaO, ThO2, or mixtures thereof.

[0027] In this disclosure, polyethylene may be biomass-derived polyethylene (hereinafter also referred to as "biomass polyethylene"). That is, instead of ethylene obtained from fossil fuels as a raw material for obtaining polyethylene, biomass-derived ethylene may be used. Since biomass polyethylene is a carbon-neutral material, it can reduce the environmental burden of sealant films, laminates, or packaging materials. Biomass polyethylene can be produced, for example, by the method described in Japanese Patent Application Publication No. 2013-177531. Commercially available biomass polyethylene may also be used.

[0028] Biomass-derived ethylene, which is a raw material for biomass polyethylene, can be obtained by conventionally known methods. An example of a method for producing biomass-derived ethylene is described below.

[0029] Biomass-derived ethylene can be produced, for example, using biomass-derived ethanol as a raw material. In particular, it is preferable to use biomass-derived fermented ethanol obtained from plant materials. Conventional known plants can be used as plant materials, such as corn, sugarcane, beet, and manioc.

[0030] Biomass-derived fermented ethanol refers to ethanol produced by contacting a culture medium containing a carbon source obtained from plant raw materials with microorganisms that produce ethanol or products derived from their crushed material, and then purifying the ethanol. Conventional methods known as distillation, membrane separation, and extraction can be applied to purify the ethanol from the culture medium. For example, methods include adding benzene, cyclohexane, etc., and azeotropic distillation, or removing water by membrane separation, etc. To obtain the above-mentioned ethylene, further advanced purification may be performed at this stage, such as reducing the total amount of impurities in the ethanol to 1 ppm or less.

[0031] A catalyst is usually used when obtaining ethylene by the dehydration reaction of ethanol. Conventionally known catalysts can be used. A reaction mode that is advantageous from a process perspective is a fixed-bed flow reaction, which allows for easy separation of the catalyst and the product. For example, γ-alumina is preferred.

[0032] Since this dehydration reaction is an endothermic reaction, it is usually carried out under heating conditions. The heating temperature is not limited as long as the reaction proceeds at a commercially useful rate, but a temperature of 100°C or higher is preferable, more preferably 250°C or higher, and even more preferably 300°C or higher. There is no particular upper limit, but from the viewpoint of energy balance and equipment, it is preferable to have a temperature of 500°C or lower, more preferably 400°C or lower.

[0033] In the dehydration reaction of ethanol, the yield of the reaction depends on the amount of water contained in the ethanol supplied as a raw material. Generally, when performing a dehydration reaction, it is preferable to have no water present in order to improve the efficiency of water removal. However, in the case of the dehydration reaction of ethanol using a solid catalyst, the amount of other olefins, especially butene, tends to increase when water is absent. This is presumably because the dimerization of ethylene after dehydration cannot be suppressed without a small amount of water. The water content is, for example, 0.1% by mass or more, preferably 0.5% by mass or more. From the viewpoint of mass balance and heat balance, the water content is, for example, 50% by mass or less, preferably 30% by mass or less, and more preferably 20% by mass or less.

[0034] By carrying out the dehydration reaction of ethanol in this manner, a mixture of ethylene, water, and a small amount of unreacted ethanol is obtained. Since ethylene is a gas at room temperature and below approximately 5 MPa, water and ethanol can be removed from this mixture by gas-liquid separation to obtain ethylene. This can be done by known methods.

[0035] The ethylene obtained by gas-liquid separation is further distilled, and there are no particular restrictions on the distillation method, operating temperature, residence time, etc., except that the operating pressure at this time is above atmospheric pressure.

[0036] When the raw material is biomass-derived ethanol, the resulting ethylene contains trace amounts of impurities introduced during the ethanol fermentation process, such as carbonyl compounds like ketones, aldehydes, and esters, as well as their decomposition products like carbon dioxide, and nitrogen-containing compounds like amines and amino acids, as well as their decomposition products like ammonia. Depending on the intended use of the ethylene, these trace amounts of impurities may be problematic and may be removed by purification. Purification can be carried out by conventionally known methods. A suitable purification method is, for example, adsorption purification. Conventionally known adsorbents can be used as the adsorbent. For example, materials with a high surface area are preferred, and the type of adsorbent is selected according to the type and amount of impurities in the ethylene obtained by the dehydration reaction of biomass-derived ethanol.

[0037] Caustic water treatment may be used in combination as a method for purifying impurities in ethylene. If caustic water treatment is used, it is desirable to perform it before adsorption purification. In that case, it is necessary to perform a water removal treatment after the caustic treatment and before adsorption purification.

[0038] Biomass polyethylene is polyethylene obtained by polymerizing monomers containing ethylene derived from biomass. Preferably, the ethylene obtained by the above manufacturing method is used as the biomass-derived ethylene. Since biomass-derived ethylene is used as the raw material monomer, the polymerized polyethylene is biomass-derived.

[0039] The raw material monomers for biomass polyethylene do not necessarily have to contain 100% by mass of biomass-derived ethylene. The raw material monomers for biomass polyethylene may also contain ethylene derived from fossil fuels in addition to biomass-derived ethylene.

[0040] Atmospheric carbon dioxide contains a certain proportion (105.5 pMC) of C14, and it is known that the C14 content of plants that grow by taking in atmospheric carbon dioxide, such as corn, is also around 105.5 pMC. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the proportion of C14 contained in the total number of carbon atoms, the proportion of carbon derived from biomass can be calculated. In this disclosure, "biomass degree" refers to the weight ratio of biomass-derived components. For example, let's take polyethylene terephthalate as an example. Polyethylene terephthalate is a polymer obtained by polymerizing ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms in a molar ratio of 1:1. When only biomass-derived ethylene glycol is used, the weight ratio of biomass-derived components in the polyester is 31.25%. Therefore, the theoretical value of the biomass degree is 31.25%. Specifically, the mass of polyethylene terephthalate is 192, of which 60 is derived from biomass-derived ethylene glycol. Therefore, 60 ÷ 192 × 100 = 31.25. The weight ratio of biomass-derived components in fossil fuel-derived polyester produced using fossil fuel-derived ethylene glycol and fossil fuel-derived dicarboxylic acid is 0%, and the biomass content of fossil fuel-derived polyester is 0%. Hereafter, unless otherwise specified, "biomass content" refers to the weight ratio of biomass-derived components.

[0041] Theoretically, if all ethylene is derived from biomass as the raw material for polyethylene, the biomass-derived ethylene concentration will be 100%, and the biomass content of biomass polyethylene will be 100%. In fossil fuel polyethylene, which is produced using only fossil fuel-derived raw materials, the biomass-derived ethylene concentration is 0%, and the biomass content of fossil fuel polyethylene is 0%.

[0042] Examples of biomass polyethylene include, for example, biomass high-density polyethylene, biomass medium-density polyethylene, biomass low-density polyethylene, biomass linear low-density polyethylene, and biomass ultra-low-density polyethylene. In one embodiment, the biomass content of the biomass polyethylene is 80% or more, 85% or more, 90% or more, or 95% or more. As for biomass polyethylene, plant-derived polyethylene is preferred.

[0043] In this disclosure, the biomass polyethylene and biomass-derived resin layers do not need to be 100% biomass. This is because if even a portion of the laminate is made from biomass-derived raw materials, it is in line with the purpose of reducing the amount of fossil fuels used compared to conventional methods.

[0044] As polyethylene, polyethylene recycled by mechanical recycling or chemical recycling may be used. This reduces the environmental impact of sealant films, laminates, or packaging materials. Mechanical recycling generally involves crushing collected polyethylene film, washing it with alkali to remove dirt and foreign matter from the film surface, drying it at high temperature and reduced pressure for a certain period of time to disperse contaminants remaining inside the film and decontaminate it, removing the dirt from the film and returning it to polyethylene. Chemical recycling generally involves decomposing collected polyethylene film down to the monomer level and then repolymerizing the monomers to obtain polyethylene. The above description of polyethylene applies to the polyethylene described below.

[0045] [Sealing film] The sealant film of this disclosure has a first surface and a second surface facing the first surface. The sealant film of this disclosure comprises a first layer constituting a first surface and a second layer. The first layer is the surface layer on one side of the sealant film. The first layer has a density of 0.910 g / cm³. 3The following linear low-density polyethylene is contained. The second layer contains at least a copolymer of ethylene and a carbon-4 α-olefin as the linear low-density polyethylene.

[0046] In the sealant film of this disclosure, at least one selected from linear low-density polyethylene contained in the first layer and a copolymer of ethylene and a C4 α-olefin contained in the second layer is biomass-derived polyethylene. If the sealant film comprises a plurality of second layers, and the copolymer of ethylene and a C4 α-olefin contained in the second layer is biomass-derived polyethylene, then it is sufficient that at least one of the second layers contains the biomass-derived polyethylene, and not all of the second layers contain the biomass-derived polyethylene.

[0047] The sealant film having the above configuration exhibits excellent low-temperature sealing properties and cutability. Therefore, by using the sealant film of this disclosure as the sealant layer in a laminate comprising a stretched polyethylene substrate and a sealant layer, it is possible to provide a laminate with excellent low-temperature sealing properties and cutability, and a packaging material made from said laminate.

[0048] Furthermore, stretching the polyethylene film conventionally used as a sealant layer improves the heat resistance of the film, allowing the stretched polyethylene film to be used as a base material. However, when polyethylene film is uniaxially stretched in the flow direction (longitudinal direction, MD), the orientation of the resin aligns with the flow direction, which can reduce the cutability (tearability) of the laminate in the width direction (direction perpendicular to MD, TD).

[0049] Because the sealant film of this disclosure has excellent cutability in the width direction, even when a polyethylene substrate that has been uniaxially stretched in the flow direction (MD) is used as the stretched polyethylene substrate, the cutability in the width direction (TD) of the laminate can be improved. Therefore, it is possible to produce a packaging container that has excellent cutability in the width direction when opened, i.e., easy-to-open properties. Furthermore, for example, when continuously manufacturing packaging bags using a filling machine, a long laminate is cut in the width direction to produce individual packaging bags, so cutability in the width direction is important not only from the standpoint of ease of opening but also from the standpoint of manufacturability.

[0050] In one embodiment, the sealant film of the present disclosure may further comprise a third layer, the third layer having a different composition from both the first and second layers.

[0051] In the sealant film of this disclosure, for convenience, the first layer is also referred to as the "seal layer." The seal layer constitutes the first surface of the sealant film. The seal layer is a layer that constitutes the surface layer on one side of the laminate, or the surface layer on both sides of the laminate, when the sealant film is used as the sealant layer of the laminate, and is a layer that is fused by heat. In one embodiment, when a packaging container is made using a packaging material consisting of the laminate of this disclosure, the first layer is the layer facing the side containing the contents in the packaging container.

[0052] In the sealant film of this disclosure, for convenience, the surface layer opposite to the first layer is also referred to as the "laminate layer." The laminate layer constitutes the second surface of the sealant film. The layer located between the sealant layer and the laminate layer is also referred to as the "intermediate layer." The intermediate layer may be a single layer or a multilayer layer. If the intermediate layer is a multilayer layer, the composition of each intermediate layer may be the same or different. The intermediate layer may be omitted.

[0053] Figures 1 to 4 show one embodiment of the sealant film of this disclosure. The sealant film 10 in Figure 1 comprises a first layer 12 and a second layer 14 in this order in the thickness direction. The first layer 12 constitutes the first surface X of the sealant film 10, and the second layer 14 constitutes the second surface Y of the sealant film 10.

[0054] The sealant film 10 in Figure 2 comprises a first layer 12, a second layer 14A, and a second layer 14B in this order in the thickness direction. The first layer 12 constitutes the first surface X of the sealant film 10, and the second layer 14B constitutes the second surface Y of the sealant film 10.

[0055] The sealant film 10 in Figure 3 comprises a first layer 12, a second layer 14, and a third layer 16 in this order in the thickness direction. The first layer 12 constitutes the first surface X of the sealant film 10, and the third layer 16 constitutes the second surface Y of the sealant film 10. The second layer 14 is located between the first layer 12 and the third layer 16.

[0056] The sealant film 10 in Figure 4 comprises a first layer 12, a third layer 16, and a second layer 14 in this order in the thickness direction. The first layer 12 constitutes the first surface X of the sealant film 10, and the second layer 14 constitutes the second surface Y of the sealant film 10. The third layer 16 is located between the first layer 12 and the second layer 14.

[0057] In one embodiment, the number of layers in the sealant film is between 2 and 7, for example, between 3 and 7, or between 3 and 5. The number of layers in the sealant film is preferably odd, for example, 3, 5, or 7. Such a configuration increases the symmetry of the sealant film's lamination structure, thereby suppressing curling in the sealant film.

[0058] In one embodiment, the sealant film of this disclosure is an unstretched film. An unstretched film is a film that has not undergone stretching treatment, for example, an extruded film that has not undergone stretching treatment. Details of the stretching treatment will be described later in the description of the stretched polyethylene substrate.

[0059] The melt flow rate (MFR) of the polyethylene constituting the sealant film is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, and even more preferably 0.3 g / 10 min to 20 g / 10 min, from the viewpoint of film-forming properties and processability. The MFR of polyethylene is measured by Method A in accordance with JIS K7210, under conditions of a temperature of 190°C and a load of 2.16 kg.

[0060] For example, when manufacturing a sealant film by the T-die method, the MFR of the polyethylene constituting the film is preferably 3.0 g / 10 min or more and 20 g / 10 min or less, from the viewpoint of film-forming properties and processability.

[0061] For example, when manufacturing a sealant film by the inflation method, the MFR of the polyethylene constituting the film is preferably 0.5 g / 10 min or more and 5.0 g / 10 min or less, from the viewpoint of film-forming properties and processability.

[0062] The melting point (Tm) of the polyethylene constituting the sealant film is preferably 90°C to 140°C, more preferably 90°C to 130°C, and even more preferably 90°C to 120°C, from the viewpoint of balancing heat resistance and heat sealability. Tm is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0063] The polyethylene content in the sealant film is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. With such a configuration, for example, the recyclability of a packaging material consisting of a laminate comprising the sealant film of this disclosure can be improved.

[0064] The sealant film contains biomass polyethylene. The biomass content of the sealant film may be, for example, 10% or more, 10% to 80%, 20% to 75%, or 30% to 70%.

[0065] For example, in the case of a sealant film comprising a first layer and a second layer, at least one layer selected from the first layer and the second layer contains biomass polyethylene. For example, in the case of a sealant film comprising a first layer, a second layer and a third layer, at least one layer selected from the first layer, the second layer and the third layer contains biomass polyethylene.

[0066] In one embodiment, when the intermediate layer and the laminate layer are second layers, at least one selected from linear low-density polyethylene contained in the first layer, a copolymer of ethylene and a carbon-4 α-olefin contained in the intermediate layer, and a copolymer of ethylene and a carbon-4 α-olefin contained in the laminate layer is biomass polyethylene.

[0067] The sealant film may contain one or more resin materials other than polyethylene. Examples of such resin materials include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. Each layer constituting the sealant film may independently contain one of the above resin materials.

[0068] In one embodiment, the sealant film is a co-extruded resin film, and each layer constituting the sealant film is a co-extruded resin layer. The co-extruded resin film can be manufactured by forming a film using, for example, the inflation method or the T-die method. An example of these will be described below.

[0069] In the inflation method, first, the materials constituting each layer are dried, and then supplied to a melt extruder heated to a temperature above its melting point (Tm) ~ Tm + 100°C to melt them and extrude them into a cylindrical shape using an annular die. At this time, air is blown into the cylindrical molten resin from below to expand the diameter of the cylinder to a predetermined size, and cooling air is blown out of the cylinder from below. This expanded cylindrical body is called a bubble. Next, the bubble is folded into a film shape using guide plates and pinch rolls and wound up in a winding section. The folded film can be wound up as a tube, or both ends of the tube may be removed with a slitter or the like to separate it into two films, and then each may be wound up. This allows a sealant film to be formed.

[0070] In the T-die method, first, the materials constituting each layer are dried, then they are supplied to a melt extruder heated to a temperature above the melting point (Tm) to Tm+100°C to melt them, extrude them into a sheet from the die of the T-die, and the extruded sheet is rapidly cooled and solidified in a rotating cooling drum or the like to form a sealant film.

[0071] Examples of molten extruders used in the inflation method and the T-die method include single-screw extruders, twin-screw extruders, vented extruders, and tandem extruders.

[0072] The second surface of the sealant film may be subjected to a surface treatment. This can improve, for example, the adhesion between the sealant film and the layer laminated on the sealant film. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using gases such as oxygen and nitrogen gas, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals.

[0073] The total thickness of the sealant film is preferably 10 μm to 300 μm, more preferably 10 μm to 250 μm, and in one embodiment, 10 μm to 60 μm, or 40 μm to 200 μm. The total thickness of the sealant film is preferably changed as appropriate depending on the mass of the contents contained in the packaging container described later, from the viewpoint of the strength and processability of the sealant film.

[0074] For example, if the packaging container is a small bag, the total thickness of the sealant film is preferably 10 μm to 60 μm. In this case, for example, contents weighing 1 g to 200 g can be well contained within the small bag.

[0075] For example, if the packaging container is a standing pouch, the total thickness of the sealant film is preferably 40 μm to 200 μm, more preferably 60 μm to 150 μm. In this case, for example, contents weighing 50 g to 2000 g can be well contained within the standing pouch.

[0076] <First layer> The first layer has a density of 0.910 g / cm³ 3 It contains the following linear low-density polyethylene. The density of the above linear low-density polyethylene is preferably 0.900 g / cm³. 3 More than 0.910g / cm 3 The following is the result. This makes it possible to improve, for example, the low-temperature sealing properties and sealing strength of sealant films.

[0077] The stretched polyethylene substrate in the laminate described later is made of polyethylene, which has a lower melting point than polyester or nylon. Therefore, the heat-sealing temperature when manufacturing packaging containers using this laminate cannot be raised too high. The sealant film of this disclosure can be heat-sealed at low temperatures and can be well combined with the stretched polyethylene substrate.

[0078] Examples of the linear low-density polyethylene mentioned above include ethylene-α-olefin copolymers. Examples of the α-olefin comonomer in the ethylene-α-olefin copolymer include the above α-olefins having 3 to 20 carbon atoms, with α-olefins having 4 to 8 carbon atoms being preferred, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene being more preferred, and 1-hexene and 1-octene being even more preferred. The α-olefin in the ethylene-α-olefin copolymer may be one type or two or more types.

[0079] Preferably, the ethylene-α-olefin copolymer is ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, and ethylene-1-octene copolymer. In this disclosure, ethylene-1-hexene copolymer means a copolymer of ethylene and 1-hexene, but is not limited to copolymers of ethylene and 1-hexene alone, and also includes copolymers of ethylene, 1-hexene and other α-olefins, etc., and may be a terpolymer such as ethylene-propylene-1-hexene copolymer. The same applies to other copolymers in this disclosure.

[0080] The content of α-olefin-derived constituent units in the ethylene-α-olefin copolymer is, for example, 15 mol% or less, but may also be 10 mol% or less, or 5 mol% or less.

[0081] The density in the first layer is 0.910 g / cm³ 3The following linear low-density polyethylene content is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 75% by mass or more, based on the first layer. This can, for example, further improve the low-temperature sealing properties and sealing strength of the sealant film. It can also, for example, improve the recyclability of the laminate described later.

[0082] The density in the first layer is 0.910 g / cm³ 3 The upper limit of the linear low-density polyethylene content below may be 100% by mass, 95% by mass, or 90% by mass, based on the first layer.

[0083] The first layer may further contain low-density polyethylene, i.e., high-pressure low-density polyethylene. This can further improve, for example, the cutability, slipperiness, blocking resistance, and processability of the sealant film.

[0084] The content of low-density polyethylene in the first layer is preferably 3% to 40% by mass, more preferably 5% to 30% by mass, and even more preferably 8% to 20% by mass, based on the first layer. This makes it possible to further improve, for example, the cutability, slipperiness, blocking resistance, and processability of the sealant film.

[0085] As the linear low-density polyethylene and low-density polyethylene mentioned above, biomass polyethylene or mechanically or chemically recycled polyethylene may be used.

[0086] The first layer may contain one or more additives. Examples of additives include antiblocking agents, antistatic agents, crosslinking agents, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, pigments, dyes, and modifying resins.

[0087] The first layer may contain one or more antiblocking agents. The first layer has a density of 0.910 g / cm³.3 Because it contains the following linear low-density polyethylene, when a sealant film is produced by, for example, the inflation method, opposing first layers may adhere to each other. Such adhesion can be suppressed by including an antiblocking agent in the first layer.

[0088] Examples of antiblocking agents include inorganic compound-based antiblocking agents and organic compound-based antiblocking agents. Examples of inorganic compound-based antiblocking agents include oxides such as silica, aluminum oxide, magnesium oxide, calcium oxide, titanium oxide, and zinc oxide; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; carbonates such as magnesium carbonate and calcium carbonate; sulfates such as calcium sulfate and barium sulfate; silicates such as magnesium silicate, aluminum silicate, calcium silicate, and aluminosilicate; and others such as synthetic zeolites, natural zeolites, kaolin, talc, and diatomaceous earth. Examples of organic compound-based antiblocking agents include cross-linked polymethyl methacrylate resin particles and cross-linked styrene resin particles.

[0089] From the viewpoint of improving the dispersibility of the antiblocking agent in the polyethylene composition, the antiblocking agent may be pre-mixed with a thermoplastic resin such as polyethylene at a high concentration to form a masterbatch for use.

[0090] The content ratio of the antiblocking agent in the first layer is, for example, 0.1% by mass or more and 10% by mass or less, preferably 0.5% by mass or more and 8% by mass or less, based on the first layer. This allows for, for example, further improvement of the antiblocking properties of the first layer.

[0091] The density of the first layer is preferably 0.930 g / cm³. 3 More preferably, 0.900 g / cm³ 3 More than 0.928g / cm 3 More preferably, 0.900 g / cm³ 3 More than 0.926g / cm 3The following applies:

[0092] In this disclosure, the density of each layer may be measured in accordance with the above JIS K7112, or it may be calculated from the density of the components constituting the layer. For example, if a single layer contains multiple types (n types; n is an integer of 2 or more) of components with different densities (e.g., polyethylene), the average density D is calculated according to the following formula (f1). av This may be used as the density of the layer.

[0093] D av = ΣW i ×D i …(f1) In equation (f1), Σ represents W from 1 to n for i. i ×D i This means taking the sum of n, where n is an integer greater than or equal to 2, and W i This indicates the mass fraction of the i-th component, and D i This is the density of the i-th component (g / cm³). 3 ) indicates.

[0094] In a sealant film, the absolute difference between the density of the first layer (seal layer), which is the surface layer on one side, and the density of the other surface layer (laminate layer) is preferably 0.020 g / cm³. 3 More preferably, 0.015 g / cm³ 3 More preferably, 0.010 g / cm³ 3 The following is the result. This configuration increases the symmetry of the laminated structure of the sealant film, and for example, it can suppress the occurrence of curling in the sealant film.

[0095] The ratio of the thickness of the first layer to the total thickness of the sealant film is preferably 5% to 45%, more preferably 10% to 40%, and even more preferably 15% to 35%.

[0096] <Second layer> The second layer contains at least a copolymer of ethylene and a carbon-4 α-olefin as linear low-density polyethylene. This improves the cutability of sealant films, for example. This is presumed to be because the copolymer has less entanglement of molecular chains and therefore less cohesive force compared to other linear low-density polyethylenes.

[0097] In this disclosure, copolymers of ethylene and C4 α-olefins are not limited to copolymers of ethylene and C4 α-olefins alone, but also include copolymers of ethylene and C4 α-olefins with other α-olefins, etc. An example of an α-olefin having four carbon atoms is 1-butene. As a copolymer of ethylene and an α-olefin having four carbon atoms, ethylene-1-butene copolymer is preferred.

[0098] In a copolymer of ethylene and a carbon-4 α-olefin, the content of constituent units derived from the carbon-4 α-olefin is, for example, 15 mol% or less, but may also be 10 mol% or less, or 5 mol% or less.

[0099] For example, when manufacturing a sealant film by the inflation method, the MFR of the copolymer of ethylene and a carbon-4 α-olefin constituting the second layer is particularly preferably 2.5 g / 10 min or more and 5.0 g / 10 min or less. This can, for example, further improve the cutability of the sealant film.

[0100] The content ratio of the copolymer of ethylene and a carbon-4 α-olefin in the second layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 75% by mass or more, based on the second layer. This can, for example, further improve the cutability of the sealant film. It can also, for example, improve the recyclability of the laminate described later.

[0101] The upper limit of the content ratio of the copolymer of ethylene and carbon-4 α-olefin in the second layer may be 100% by mass, 95% by mass, or 90% by mass, based on the second layer.

[0102] The second layer may further contain low-density polyethylene, i.e., high-pressure low-density polyethylene. This can further improve, for example, the cutability, slipperiness, blocking resistance, and processability of the sealant film.

[0103] The content of low-density polyethylene in the second layer is preferably 3% to 40% by mass, more preferably 5% to 30% by mass, and even more preferably 8% to 25% by mass, based on the second layer. This makes it possible to further improve, for example, the cutability, slipperiness, blocking resistance, and processability of the sealant film.

[0104] As the linear low-density polyethylene and low-density polyethylene mentioned above, biomass polyethylene or mechanically or chemically recycled polyethylene may be used.

[0105] The second layer may contain one or more of the above-mentioned additives.

[0106] The density of the second layer is preferably 0.930 g / cm³. 3 More preferably, 0.900 g / cm³ 3 More than 0.928g / cm 3 More preferably, 0.910 g / cm³ 3 More than 0.926g / cm 3 The following applies:

[0107] In one embodiment, the laminate layer and / or intermediate layer is a second layer. In one embodiment, if the sealant film is composed of two layers, the laminate layer is the second layer. In one embodiment, if the sealant film is composed of three or more layers, the laminate layer and / or intermediate layer is the second layer. If the sealant film is composed of three or more layers, the second layer is preferably at least the laminate layer. There may be multiple second layers in the sealant film; for example, both the laminate layer and the intermediate layer may be the second layer.

[0108] The ratio of the thickness of the second layer to the total thickness of the sealant film is preferably 55% to 95%, more preferably 60% to 90%, and even more preferably 65% ​​to 85%, when the sealant film is composed of a first layer and a second layer. If there are multiple second layers, the above ratio refers to the ratio of their total thickness.

[0109] The ratio of the thickness of the second layer to the total thickness of the sealant film is preferably 5% to 45%, more preferably 10% to 40%, and even more preferably 15% to 35%, when a third layer is present and the second layer constitutes the second surface of the sealant film.

[0110] The ratio of the thickness of the second layer to the total thickness of the sealant film is preferably 20% to 90%, more preferably 30% to 80%, and even more preferably 40% to 70%, when a third layer is present and the third layer constitutes the second surface of the sealant film.

[0111] <Third layer> The third layer contains polyethylene as its main component. Details about polyethylene are as described above.

[0112] In this disclosure, the phrase "AAA contains polyethylene as its main component," "AAA containing polyethylene as its main component," or similar statements mean that the polyethylene content in the AAA is more than 50% by mass, preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0113] From the viewpoint of heat-sealability, at least one polyethylene selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene is preferred for the polyethylene constituting the third layer, and at least one selected from low-density polyethylene and linear low-density polyethylene is more preferred. Biomass polyethylene, or mechanically or chemically recycled polyethylene may be used.

[0114] Examples of linear low-density polyethylene include ethylene-α-olefin copolymers other than copolymers of ethylene and α-olefins having 4 carbon atoms. Examples of α-olefins that are comonomers in ethylene-α-olefin copolymers include the above-mentioned α-olefins having 5 to 20 carbon atoms, with α-olefins having 5 to 8 carbon atoms being preferred, and 1-hexene, 4-methyl-1-pentene, and 1-octene being more preferred. The α-olefin in the ethylene-α-olefin copolymer may be one type or two or more types. Specifically, preferred ethylene-α-olefin copolymers are ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, and ethylene-1-octene copolymer.

[0115] The content of α-olefin-derived constituent units in the ethylene-α-olefin copolymer is, for example, 15 mol% or less, but may also be 10 mol% or less, or 5 mol% or less.

[0116] The third layer may contain one or more types of polyethylene.

[0117] The content of linear low-density polyethylene in the third layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 75% by mass or more, based on the third layer. This improves the recyclability of the laminate, as described later.

[0118] The upper limit of the linear low-density polyethylene content in the third layer may be 100% by mass, 95% by mass, or 90% by mass, based on the third layer.

[0119] The third layer may further contain low-density polyethylene, i.e., high-pressure low-density polyethylene. This can further improve, for example, the cutability, slipperiness, blocking resistance, and processability of the sealant film.

[0120] The content of low-density polyethylene in the third layer is preferably 3% to 40% by mass, more preferably 5% to 30% by mass, and even more preferably 8% to 25% by mass, based on the third layer. This makes it possible to further improve, for example, the cutability, slipperiness, blocking resistance, and processability of the sealant film.

[0121] As the linear low-density polyethylene and low-density polyethylene mentioned above, biomass polyethylene or mechanically or chemically recycled polyethylene may be used.

[0122] The third layer may contain one or more of the above-mentioned additives.

[0123] The density of the third layer is preferably 0.930 g / cm³. 3 More preferably, 0.900 g / cm³ 3 More than 0.928g / cm 3 More preferably, 0.910 g / cm³ 3 More than 0.926g / cm 3 The following applies:

[0124] In one embodiment, the laminate layer and / or intermediate layer is a third layer. Multiple third layers may exist within the sealant film.

[0125] The ratio of the thickness of the third layer to the total thickness of the sealant film is preferably 5% to 45%, more preferably 10% to 40%, and even more preferably 15% to 35%, when the third layer constitutes the second surface of the sealant film.

[0126] The ratio of the thickness of the third layer to the total thickness of the sealant film is preferably 20% to 90%, more preferably 30% to 80%, and even more preferably 40% to 70%, when the second layer constitutes the second surface of the sealant film.

[0127] <Vapor deposition film> The sealant film of this disclosure may include a vapor-deposited film formed on the second surface. This can improve, for example, the oxygen barrier and water vapor barrier properties of the laminate described later. Details of the vapor-deposited film will be described later.

[0128] The surface of the deposited film may be subjected to the surface treatment described above. This can improve, for example, the adhesion between the deposited film and the layer laminated on it. [Laminated body] The laminate of the present disclosure comprises a stretched polyethylene substrate and a sealant layer. The sealant film of the present disclosure described above is used as the sealant layer. The sealant film is arranged such that its second surface faces the stretched polyethylene substrate. In one embodiment, the laminate of the present disclosure includes an adhesive layer between the stretched polyethylene substrate and the sealant layer.

[0129] In one embodiment of the laminate of this disclosure, the stretched polyethylene substrate and the sealant layer each contain polyethylene, which is the same type of resin material, as a main component. By using a laminate having such a configuration, for example, a packaging container with excellent recyclability can be manufactured.

[0130] For example, polyethylene includes high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene, all of which are classified as the same type of resin material. On the other hand, polyethylene and polyester, for example, are not classified as the same type of resin material.

[0131] In one embodiment, the laminate of the present disclosure contains biomass polyethylene. The biomass content of the laminate of the present disclosure may be, for example, 5% to 70%, 8% to 50%, or 10% to 30%. This can reduce the environmental burden of the laminate or packaging material, for example.

[0132] The polyethylene content in the entire laminate of this disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Since such a laminate uses polyethylene, which is a resin material of the same type, it can be classified as a so-called monomaterial material and can be suitably used, for example, in the manufacture of monomaterial packaging containers.

[0133] Figures 5 and 6 show one embodiment of the laminate of the present disclosure. The laminate 1 in Figure 5 comprises a stretched polyethylene substrate 30, an adhesive layer 20, and a sealant film 10 in this order in the thickness direction. The laminate 1 in Figure 6 has an extruded resin layer as the adhesive layer 20, and further comprises an anchor coat layer 22 between the stretched polyethylene substrate 30 and the adhesive layer 20. The adhesive layer 20 is in contact with the anchor coat layer 22.

[0134] <Stretched polyethylene substrate> The stretched polyethylene substrate contains polyethylene as its main component. Stretched polyethylene substrate is a polyethylene substrate that has undergone stretching treatment.

[0135] From the viewpoint of strength and heat resistance of the substrate, high-density polyethylene and medium-density polyethylene are preferred as the polyethylene contained in the stretched polyethylene substrate, and from the viewpoint of stretchability, medium-density polyethylene is preferred.

[0136] The melt flow rate (MFR) of the polyethylene constituting the stretched polyethylene substrate is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, even more preferably 0.2 g / 10 min to 10 g / 10 min, and particularly preferably 0.2 g / 10 min to 5.0 g / 10 min, from the viewpoint of film-forming properties and processability.

[0137] For example, when producing a stretched polyethylene substrate by the T-die method, the MFR of the polyethylene constituting the substrate is preferably 3.0 g / 10 min or more and 20 g / 10 min or less, from the viewpoint of film-forming properties and processability.

[0138] For example, when producing a stretched polyethylene substrate by the inflation method, the MFR of the polyethylene constituting the substrate is preferably 0.2 g / 10 min or more and 5.0 g / 10 min or less, from the viewpoint of film-forming properties and processability.

[0139] From the viewpoint of heat resistance, the melting point (Tm) of the polyethylene constituting the stretched polyethylene base material is preferably 100°C to 140°C, more preferably 110°C to 140°C, and even more preferably 120°C to 140°C.

[0140] The stretched polyethylene substrate may contain one or more types of polyethylene. The polyethylene content in the stretched polyethylene substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. This configuration can improve, for example, the recyclability of the laminate.

[0141] When the stretched polyethylene substrate has a multilayer structure, the polyethylene content in each layer constituting the substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, independently of each other. Such a configuration can improve, for example, the recyclability of the laminate.

[0142] The stretched polyethylene substrate may contain one or more resin materials other than polyethylene. Examples of such resin materials include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. If the stretched polyethylene substrate has a multilayer structure, each layer constituting the substrate may independently contain one of the above resin materials.

[0143] The stretched polyethylene substrate may contain one or more additives. Examples of additives include crosslinking agents, antiblocking agents, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins. If the stretched polyethylene substrate has a multilayer structure, each layer constituting the substrate may independently contain the above-mentioned additives.

[0144] Stretched polyethylene substrates are polyethylene substrates that have undergone a stretching treatment. This stretching treatment can improve, for example, the heat resistance and strength of the polyethylene substrate. Such stretched polyethylene substrates can satisfy the physical properties required for, for example, the outer layer of packaging materials.

[0145] The stretching may be uniaxial or biaxial. In one embodiment, the stretching ratio in the longitudinal direction (MD) of the stretched polyethylene substrate is preferably 2 to 10 times, more preferably 3 to 7 times. In one embodiment, the stretching ratio in the transverse direction (TD) of the stretched polyethylene substrate is preferably 2 to 10 times, more preferably 3 to 7 times.

[0146] If the stretching ratio is 2 times or more, for example, the rigidity, strength, and heat resistance of the substrate can be improved, the printability of the substrate can be improved, and the transparency of the substrate can be improved. If the stretching ratio is 10 times or less, for example, good stretching can be performed without causing the film to break.

[0147] In one embodiment, the stretched polyethylene substrate is a uniaxially oriented film, and more specifically, a uniaxially oriented film stretched in the longitudinal direction (MD). As described above, even when using such a uniaxially oriented film, a laminate with excellent cutability in the width direction (TD) can be obtained by using the sealant film of this disclosure.

[0148] The stretched polyethylene substrate may have a single-layer structure or a multi-layer structure. Hereinafter, a stretched polyethylene substrate having a multi-layer structure will also be referred to as a "stretched multi-layer substrate." A stretched multi-layer substrate is preferable from the viewpoint of improving its strength, heat resistance, and stretchability.

[0149] The stretched multilayer substrate has a multilayer structure of two or more layers. In one embodiment, the number of layers of the stretched multilayer substrate is two to seven, for example, three to seven, or three to five. The number of layers of the stretched multilayer substrate is preferably an odd number, for example, three, five, or seven. The stretched multilayer substrate has a multilayer structure, which improves the balance of the substrate's rigidity, strength, heat resistance, printability, and stretchability. It is also preferable that each layer of the stretched multilayer substrate contains polyethylene as its main component.

[0150] Below, several examples of embodiments of the stretched multilayer substrate will be described. Hereinafter, a layer with a high-density polyethylene content of 80% by mass or more will be referred to as the "high-density polyethylene layer," a layer with a medium-density polyethylene content of 80% by mass or more will be referred to as the "medium-density polyethylene layer," a layer with a low-density polyethylene content of 80% by mass or more will be referred to as the "low-density polyethylene layer," a layer with a linear low-density polyethylene content of 80% by mass or more will be referred to as the "linear low-density polyethylene layer," and a layer with an ultra-low-density polyethylene content of 80% by mass or more will be referred to as the "ultra-low-density polyethylene layer."

[0151] The stretched multilayer substrate of the first embodiment comprises a high-density polyethylene layer and a medium-density polyethylene layer in this order in the thickness direction. Having a high-density polyethylene layer as the surface resin layer of the substrate improves, for example, the strength and heat resistance of the substrate. Having a medium-density polyethylene layer in the substrate improves, for example, the stretchability of the pre-stretched laminate.

[0152] The stretched multilayer substrate of the second embodiment comprises a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer in this order in the thickness direction. With this configuration, for example, the strength and heat resistance of the substrate can be improved, the occurrence of curl in the substrate can be suppressed, and the stretchability of the pre-stretched laminate can be improved.

[0153] In the stretched multilayer substrates of the first and second embodiments, the thickness of the high-density polyethylene layer is preferably less than or equal to the thickness of the medium-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer (high-density polyethylene layer / medium-density polyethylene layer) is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less.

[0154] The stretched multilayer substrate of the third embodiment comprises a high-density polyethylene layer, a medium-density polyethylene layer, a low-density polyethylene layer, a linear low-density polyethylene layer, or an ultra-low-density polyethylene layer (for the sake of simplicity, these three layers are collectively referred to as "low-density polyethylene layer, etc."), a medium-density polyethylene layer, and a high-density polyethylene layer, in this order in the thickness direction. By having such a configuration, for example, the stretchability of the pre-stretched laminate can be improved, the strength and heat resistance of the substrate can be improved, and the occurrence of curl in the substrate can be suppressed.

[0155] In the stretched multilayer substrate of the third embodiment, the thickness of the high-density polyethylene layer is preferably less than or equal to the thickness of the medium-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer (high-density polyethylene layer / medium-density polyethylene layer) is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less.

[0156] In the stretched multilayer substrate of the third embodiment, the thickness of the high-density polyethylene layer is preferably equal to or greater than the thickness of the low-density polyethylene layer, etc. The ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer, etc. (high-density polyethylene layer / low-density polyethylene layer, etc.) is preferably 1 or more and 4 or less, more preferably 1 or more and 2 or less.

[0157] Other embodiments of stretched multilayer substrates include a substrate comprising a high-density polyethylene layer, a high-density polyethylene layer, a blend layer of medium-density polyethylene and high-density polyethylene, a high-density polyethylene layer, and a high-density polyethylene layer in this order in the thickness direction; and a substrate comprising a medium-density polyethylene layer, a high-density polyethylene layer, a linear low-density polyethylene layer, a high-density polyethylene layer, and a medium-density polyethylene layer in this order in the thickness direction.

[0158] Another example is a substrate comprising a high-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, a low-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, and a high-density polyethylene layer, in this order in the thickness direction.

[0159] The stretched multilayer substrate of the fourth embodiment comprises a medium-density polyethylene layer, a high-density polyethylene layer, a blended layer of medium-density polyethylene and high-density polyethylene, a high-density polyethylene layer, and a medium-density polyethylene layer, in this order in the thickness direction. With this configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretched laminate can be improved.

[0160] In the above-mentioned blend layer of medium-density polyethylene and high-density polyethylene, the mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0161] The stretched multilayer substrate of the fifth embodiment comprises, in the thickness direction, a medium-density polyethylene layer, a medium-density polyethylene layer, a blend layer of medium-density polyethylene and linear low-density polyethylene, a medium-density polyethylene layer, and a medium-density polyethylene layer. With this configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretched laminate can be improved.

[0162] In the above-mentioned blend layer of medium-density polyethylene and linear low-density polyethylene, the mass ratio of medium-density polyethylene to linear low-density polyethylene (medium-density polyethylene / linear low-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0163] The stretched multilayer substrate of the sixth embodiment comprises, in the thickness direction, a blend layer of medium-density polyethylene and high-density polyethylene, a blend layer of medium-density polyethylene and linear low-density polyethylene, a linear low-density polyethylene layer, a blend layer of medium-density polyethylene and linear low-density polyethylene, and a blend layer of medium-density polyethylene and high-density polyethylene. With this configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretched laminate can be improved.

[0164] In the above-mentioned blend layer of medium-density polyethylene and high-density polyethylene, the mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) is preferably 0.25 or more and 4 or less, and more preferably 0.4 or more and 2.4 or less, for each individual.

[0165] In the above-mentioned blend layer of medium-density polyethylene and linear low-density polyethylene, the mass ratio of medium-density polyethylene to linear low-density polyethylene (medium-density polyethylene / linear low-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0166] The stretched multilayer substrate of the seventh embodiment comprises, in the thickness direction, a blend layer of high-density polyethylene and medium-density polyethylene, a medium-density polyethylene layer, a blend layer of linear low-density polyethylene and medium-density polyethylene, a medium-density polyethylene layer, and a blend layer of high-density polyethylene and medium-density polyethylene. With this configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretched laminate can be improved.

[0167] In the above-mentioned blend layer of high-density polyethylene and medium-density polyethylene, the mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) is preferably 0.25 or more and 4 or less, and more preferably 0.4 or more and 2.4 or less, for each.

[0168] In the blend layer of linear low-density polyethylene and medium-density polyethylene, the mass ratio of linear low-density polyethylene to medium-density polyethylene (linear low-density polyethylene / medium-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0169] The stretched multilayer substrate of the eighth embodiment comprises, in the thickness direction, a first layer containing medium-density polyethylene and high-density polyethylene, a second layer containing high-density polyethylene, a third layer containing linear low-density polyethylene, a fourth layer containing high-density polyethylene, and a fifth layer containing medium-density polyethylene and high-density polyethylene, in this order.

[0170] The mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) in the first and fifth layers is preferably 1.1 to 5, and more preferably 1.5 to 3, independently of each other. This further improves the balance between ink adhesion and heat resistance.

[0171] The total content of medium-density polyethylene and high-density polyethylene in the first and fifth layers is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, respectively. This further improves the ink adhesion and heat resistance of the substrate.

[0172] The second and fourth layers may each independently further contain low-density polyethylene. This can further improve the balance of heat resistance, rigidity, and processability of the substrate.

[0173] The mass ratio of high-density polyethylene to low-density polyethylene (high-density polyethylene / low-density polyethylene) in the second and fourth layers is preferably 1 to 4, and more preferably 1.5 to 3, independently of each other. This further improves the balance of heat resistance, rigidity, and processability of the base material.

[0174] The content of high-density polyethylene in the second and fourth layers is preferably more than 50% by mass, more preferably 55% by mass or more, and even more preferably 60% by mass or more, independently of each other. This further improves the heat resistance of the substrate.

[0175] The total content of high-density polyethylene and low-density polyethylene in the second and fourth layers is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, respectively. This further improves the balance of heat resistance, rigidity, and processability of the base material.

[0176] The thickness of the second and fourth layers is preferably 0.5 μm to 15 μm, more preferably 1 μm to 10 μm, and even more preferably 1 μm to 8 μm, respectively. This further improves the heat resistance of the substrate.

[0177] The third layer may further contain low-density polyethylene.

[0178] The content of linear low-density polyethylene in the third layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, 90% by mass or more, or 95% by mass or more. This allows for a further improvement in the balance of heat resistance, rigidity, and stretchability.

[0179] When the third layer contains low-density polyethylene, the content of low-density polyethylene is preferably less than 50% by mass, more preferably 5% to 40% by mass, and even more preferably 10% to 30% by mass.

[0180] The thickness of the third layer is preferably 1 μm to 50 μm, more preferably 2 μm to 40 μm, and even more preferably 5 μm to 30 μm. This allows for a further improvement in the balance of heat resistance, rigidity, and stretchability.

[0181] The ratio of the total thickness of the second and fourth layers to the thickness of the third layer (total thickness of the second and fourth layers / thickness of the third layer) is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.5 to 2. This further improves the rigidity, strength, and heat resistance of the substrate.

[0182] In the stretched multilayer substrates of the fourth to eighth embodiments, the thickness of each of the two surface resin layers is preferably 0.5 μm to 10 μm, more preferably 1 μm to 8 μm, and even more preferably 1 μm to 5 μm, independently of each other. This allows for further improvement of, for example, the heat resistance and printability of the substrate.

[0183] In the stretched multilayer substrates of the fourth to eighth embodiments, it is preferable that the thickness of each of the two surface resin layers is smaller than the total thickness of the three inner layers (multilayer intermediate layers). The ratio of the thickness of each of the two surface resin layers to the total thickness of the multilayer intermediate layers (surface resin layer / multilayer intermediate layer) is preferably 0.05 or more and 0.8 or less, more preferably 0.1 or more and 0.7 or less, and even more preferably 0.1 or more and 0.4 or less. This allows for further improvement of the rigidity, strength, and heat resistance of the substrate, for example.

[0184] In a stretched multilayer substrate, the density of the polyethylene constituting each layer may be the same or different. For example, the stretched multilayer substrate may have a density gradient in each layer. By providing a density gradient in the stretched multilayer substrate, its strength, heat resistance, and stretchability can be improved, for example.

[0185] In a stretched multilayer substrate having a density gradient, it is preferable that the absolute value of the density difference between any two adjacent layers is small. The absolute value of the above density difference is preferably 0.040 g / cm³. 3 More preferably, 0.030 g / cm³ 3 More preferably, 0.020 g / cm³ 3 The following is the result. With this configuration, for example, the occurrence of delamination at the interface of each layer can be effectively suppressed.

[0186] The haze value of the stretched polyethylene substrate is preferably 25% or less, more preferably 15% or less, and even more preferably 12% or less. A lower haze value is preferable, but in one embodiment, the lower limit may be 0.1% or 1%. The haze value of the substrate is measured in accordance with JIS K7136.

[0187] The thickness of the stretched polyethylene substrate is preferably 10 μm to 60 μm, more preferably 15 μm to 50 μm. A substrate thickness of 10 μm or more improves rigidity and strength. A substrate thickness of 60 μm or less improves processability.

[0188] The stretched polyethylene substrate may be subjected to the surface treatment described above. This can improve, for example, the adhesion between the stretched polyethylene substrate and the layer laminated on the substrate. An anchor coat layer may be formed on the surface of the stretched polyethylene substrate using a conventionally known anchor coat agent.

[0189] Stretched polyethylene substrates can be manufactured, for example, by forming a film of polyethylene or a polyethylene composition using the inflation method or the T-die method, and then stretching it. Stretched multilayer substrates can be manufactured, for example, by forming a laminate by forming multiple films of polyethylene or polyethylene compositions using the inflation method or the T-die method, and then stretching the resulting laminate. Stretching improves the transparency, rigidity, strength, and heat resistance of the substrate, making the stretched polyethylene substrate suitable for use as a base material for packaging materials, for example. Stretching can also be performed in conjunction with inflation film forming machines.

[0190] In one embodiment, the stretched polyethylene substrate having a multilayer structure is a co-extruded resin film, and each layer constituting the substrate is a co-extruded resin layer. The co-extruded resin film can be manufactured by forming a film using, for example, the inflation method or the T-die method.

[0191] In one embodiment, a stretched multilayer substrate is obtained by stretching a laminate (precursor) having a multilayer structure. Specifically, the resin material constituting each layer can be co-extruded into a tubular shape to form a film and then the laminate can be manufactured. Alternatively, the resin material constituting each layer can be co-extruded into a tubular shape, and then the opposing layers can be pressed together with rubber rolls or the like to manufacture the laminate. By manufacturing the laminate in this way, the number of defective products can be significantly reduced and production efficiency can be improved.

[0192] In one embodiment, the stretched polyethylene substrate contains biomass polyethylene. The biomass content of the stretched polyethylene substrate may be, for example, 10% or more, 10% to 65%, 20% to 55%, or 25% to 50%.

[0193] When the stretched polyethylene substrate has a multilayer structure, that is, when the stretched polyethylene substrate comprises two or more resin layers containing polyethylene as the main component, at least one of the resin layers may contain biomass polyethylene.

[0194] For example, a stretched polyethylene substrate comprising a first resin layer mainly containing high-density polyethylene, a second resin layer mainly containing medium-density polyethylene, and a third resin layer mainly containing high-density polyethylene, in this order in the thickness direction, will be described. In this case, at least one selected from the high-density polyethylene in the first resin layer, the medium-density polyethylene in the second resin layer, and the high-density polyethylene in the third resin layer may be biomass polyethylene.

[0195] <Vapor deposition film> In one embodiment, the laminate of this disclosure may include a vapor-deposited film formed on the sealant layer side surface of the stretched polyethylene substrate. This can improve, for example, the oxygen barrier properties and water vapor barrier properties of the laminate.

[0196] Examples of vapor-deposited films include metals such as aluminum, chromium, tin, nickel, copper, silver, gold, and platinum; or inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, and silicon carbide oxide (carbon-containing silicon oxide). Among these, aluminum vapor-deposited films, aluminum oxide (alumina) vapor-deposited films, silicon oxide (silica) vapor-deposited films, or carbon-containing silicon oxide vapor-deposited films are preferred.

[0197] The carbon-containing silicon oxide vapor-deposited film contains silicon, oxygen, and carbon. In one embodiment of a carbon-containing silicon oxide vapor-deposited film, the carbon content C is preferably 3% to 50%, more preferably 5% to 40%, and even more preferably 10% to 35%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. By setting the carbon content C within the above range, for example, a decrease in gas barrier properties can be suppressed even when the laminate is bent. In this specification, the proportions of each element are expressed on a molar basis.

[0198] In one embodiment of a carbon-containing silicon oxide vapor-deposited film, the silicon content (Si) is preferably 1% to 45%, more preferably 3% to 38%, and even more preferably 8% to 33%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. The oxygen content (O) is preferably 10% to 70%, more preferably 20% to 65%, and even more preferably 25% to 60%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. By setting the silicon content (Si) and oxygen content (O) within the above ranges, for example, the decrease in gas barrier properties can be further suppressed even when the laminate is bent.

[0199] In one embodiment of a carbon-containing silicon oxide vapor-deposited film, the proportion of oxygen (O) is preferably higher than the proportion of carbon (C), and the proportion of silicon (Si) is preferably lower than the proportion of carbon (C). The proportion of oxygen (O) is preferably higher than the proportion of silicon (Si), meaning that the proportions are preferably decreasing in the order of O, C, and Si. This allows for a more suppression of the decrease in gas barrier properties, for example, even when the laminate is bent.

[0200] The proportions of C, Si, and O in a carbon-containing silicon oxide vapor-deposited film can be measured by X-ray photoelectron spectroscopy (XPS) using narrow-scan analysis under the following measurement conditions.

[0201] (Measurement conditions) Equipment used: "ESCA-3400" (manufactured by Kratos) [1] Spectrum acquisition conditions Incident X-ray: MgKα (monochromatic X-ray, hν=1253.6eV) X-ray output: 150W (10kV 15mA) X-ray scanning area (measurement area): Approximately 6 mmφ Photoelectron capture angle: 90 degrees [2] Ion sputtering conditions Ionic species: Ar + Acceleration voltage: 0.2 (kV) Emission current: 20 (mA) Etching area: 10mmφ Ion sputtering was performed for 30 seconds, and the spectrum was collected.

[0202] The thickness of the deposited film is preferably 1 nm to 150 nm, more preferably 5 nm to 60 nm, and even more preferably 10 nm to 40 nm. By setting the thickness of the deposited film to 1 nm or more, for example, the oxygen barrier and water vapor barrier properties of the laminate can be further improved. By setting the thickness of the deposited film to 150 nm or less, for example, the occurrence of cracks in the deposited film can be suppressed, and the recyclability of the laminate can be improved.

[0203] Examples of methods for forming a vapor-deposited film include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating; and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition. The vapor-deposited film may be a composite film containing two or more vapor-deposited films of different inorganic oxides, formed by using both physical vapor deposition and chemical vapor deposition methods in combination.

[0204] The vacuum level of the deposition chamber before oxygen introduction was 10 -2 ~10 -8 A bar of approximately mbar is preferred, and after oxygen introduction, 10 -1 ~10 -6 A pressure of approximately mbar is preferred. The amount of oxygen introduced will vary depending on the size of the deposition machine. Inert gases such as argon, helium, and nitrogen may be used as carrier gases for the oxygen introduced, within reasonable limits. The transport speed of the film to which the deposited film is formed is, for example, 10 m / min to 800 m / min.

[0205] The surface of the deposited film may be subjected to the surface treatment described above. This can improve, for example, the adhesion between the deposited film and the layer adjacent to it.

[0206] <Barrier coat layer> For example, if the vapor-deposited film is composed of inorganic oxides such as aluminum oxide and silicon oxide, a barrier coating layer may be provided on the surface of the vapor-deposited film. By adopting such a configuration, for example, the gas barrier properties of the laminate can be improved, and the occurrence of cracks in the vapor-deposited film can be effectively suppressed.

[0207] In one embodiment, the barrier coating layer contains a gas barrier resin as its main component. Examples of gas barrier resins include polyesters such as ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamides such as nylon 6, nylon 6,6, and polymethoxyylene adipamide, polyurethanes, and (meth)acrylic resins.

[0208] The gas barrier resin content in the barrier coat layer is preferably more than 50% by mass, more preferably 60% by mass or more, and even more preferably 70% by mass or more. With this configuration, for example, the gas barrier properties of the barrier coat layer can be improved.

[0209] The thickness of the barrier coating layer is preferably 0.01 μm to 10.0 μm, and more preferably 0.1 μm to 5.0 μm. By making the barrier coating layer thickness 0.01 μm or more, for example, the gas barrier properties can be further improved.

[0210] A barrier coating layer can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or a suitable organic solvent, and then applying and drying the resulting coating solution. Alternatively, a barrier coating layer can be formed by applying and drying a commercially available barrier coating agent.

[0211] In another embodiment, the barrier coat layer is a gas barrier coating layer formed by mixing a metal alkoxide, a water-soluble polymer, and optionally a silane coupling agent, adding water, an organic solvent, and a sol-gel catalyst to obtain a gas barrier composition, applying it to a vapor-deposited film, and drying it. The gas barrier coating layer contains hydrolyzed polycondensates obtained by hydrolysis and polycondensation of the metal alkoxide, etc., by the sol-gel method. By providing such a barrier coat layer on the vapor-deposited film, the occurrence of cracks in the vapor-deposited film can be effectively suppressed. Each of the above components can be used individually or in combination of two or more.

[0212] Metal alkoxides are represented, for example, by formula (1). R 1 n M(OR 2 ) m (1) In formula (1), R 1 and R 2 Each of these independently represents an organic group with 1 to 8 carbon atoms, M represents a metal atom, n represents an integer greater than or equal to 0, m represents an integer greater than or equal to 1, and n+m represents the valence of M.

[0213] R 1 and R 2 Examples of organic groups in this context include alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-hexyl, and n-octyl groups. The metal atom M is, for example, silicon, zirconium, titanium, or aluminum.

[0214] Examples of metal alkoxides include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0215] Examples of water-soluble polymers include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Depending on the desired physical properties such as oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance, either polyvinyl alcohol or ethylene-vinyl alcohol copolymer may be used, or both may be used in combination. Alternatively, a gas barrier coating layer obtained using polyvinyl alcohol and a gas barrier coating layer obtained using ethylene-vinyl alcohol copolymer may be laminated. The amount of water-soluble polymer used is preferably 5 to 500 parts by mass per 100 parts by mass of metal alkoxide.

[0216] As the silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used, and organoalkoxysilanes having an epoxy group are preferred, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The amount of silane coupling agent used is preferably 1 to 20 parts by mass per 100 parts by mass of metal alkoxide.

[0217] The gas barrier composition may contain water in a ratio of preferably 0.1 moles to 100 moles, more preferably 0.5 moles to 60 moles, per mole of metal alkoxide. By setting the water content above the lower limit, for example, the oxygen barrier and water vapor barrier properties of the laminate can be improved. By setting the water content below the upper limit, for example, hydrolysis reactions can be carried out rapidly.

[0218] Examples of organic solvents used in the preparation of gas barrier compositions include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, and n-butyl alcohol.

[0219] Acids or amine compounds are preferred as catalysts for the sol-gel method. Examples of acids include mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid; and organic acids such as acetic acid and tartaric acid. The amount of acid used is preferably 0.001 moles or more and 0.05 moles or less per mole of the total molar amount of the alkoxide portion (e.g., silicate portion) of the metal alkoxide and the silane coupling agent.

[0220] Examples of amine compounds include N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. The amount of amine compound used is preferably 0.01 parts by mass or more and 1.0 part by mass or less, based on 100 parts by mass of the total amount of the metal alkoxide and silane coupling agent.

[0221] Methods for applying the gas barrier composition include, for example, roll coating such as gravure roll coaters, spray coating, spin coating, dipping, brushing, bar coating, and application methods such as applicators.

[0222] The following describes one embodiment of a method for forming a gas barrier coating layer. A gas barrier composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and optionally a silane coupling agent. A polycondensation reaction gradually proceeds within the composition. The composition is applied to a vapor-deposited film by a conventional method and dried. This drying further promotes the polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains one), forming a composite polymer layer. Multiple composite polymer layers may be laminated by repeating the above operation. For example, the applied composition is heated at a temperature preferably between 20°C and 150°C, more preferably between 50°C and 120°C, and even more preferably between 50°C and 100°C for 1 second to 10 minutes. This forms a gas barrier coating layer.

[0223] The thickness of the gas barrier coating layer is preferably 0.01 μm to 10.0 μm, more preferably 0.1 μm to 5.0 μm, and even more preferably 0.1 μm to 2.0 μm. This allows for improved gas barrier properties and suppression of crack formation in the vapor-deposited film.

[0224] <Printing layer> In one embodiment, the laminate of the present disclosure may further comprise a printed layer formed on the stretched polyethylene substrate described above. In one embodiment, it is preferable that the printed layer be provided on the sealant layer side of the stretched polyethylene substrate so as to suppress image degradation over time. If the laminate comprises a vapor-deposited film or a barrier coat layer on the stretched polyethylene substrate, for example, the printed layer may be provided on the sealant layer side of the vapor-deposited film or barrier coat layer.

[0225] The printed layer includes, for example, an image. Examples of images include characters, figures, symbols, and combinations thereof. Examples of methods for forming the printed layer include gravure printing, offset printing, and flexographic printing. In one embodiment, flexographic printing is preferred from the viewpoint of reducing environmental impact. Furthermore, from the viewpoint of reducing environmental impact, the printed layer may be formed on the surface of the substrate using biomass-derived ink.

[0226] The thickness of the printed layer is preferably 0.1 μm or more and 10.0 μm or less, more preferably 0.2 μm or more and 5.0 μm or less, and even more preferably 0.3 μm or more and 3.0 μm or less.

[0227] <Adhesive layer> In one embodiment, the laminate of the present disclosure includes an adhesive layer between a stretched polyethylene substrate and a sealant layer. Examples of the adhesive layer include an adhesive layer composed of an extruded resin layer mainly containing polyethylene and an adhesive.

[0228] In one embodiment, the laminate of the present disclosure comprises an extruded resin layer mainly containing polyethylene between a stretched polyethylene substrate and a sealant layer. The extruded resin layer functions as an adhesive layer between the stretched polyethylene substrate and the sealant layer, or as an adhesive layer between the laminate comprising the stretched polyethylene substrate and the sealant layer. The laminate comprising the stretched polyethylene substrate comprises, for example, the stretched polyethylene substrate and other layers such as a printed layer and an anchor coat layer.

[0229] When the laminate of this disclosure includes an extruded resin layer containing polyethylene as the main component as an adhesive layer between the stretched polyethylene substrate or the laminate and the sealant layer, the polyethylene content in the laminate can be increased compared to when conventional non-polyethylene adhesives (e.g., two-component curing polyurethane adhesives) are used. This improves the recyclability of the laminate.

[0230] The extruded resin layer contains polyethylene as its main component. Details of the polyethylene are as described above. The polyethylene in the extruded resin layer and the polyethylene in the stretched polyethylene substrate may be the same or different.

[0231] In the laminate of this disclosure, the polyethylene constituting the extruded resin layer is preferably at least one selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene, with low-density polyethylene or linear low-density polyethylene being more preferred, from the viewpoint of adhesion. Biomass polyethylene or mechanically or chemically recycled polyethylene may also be used.

[0232] The melt flow rate (MFR) of the polyethylene constituting the extruded resin layer is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, and even more preferably 3.0 g / 10 min to 20 g / 10 min, from the viewpoint of film-forming properties and the processability of the laminate.

[0233] The melting point (Tm) of the polyethylene constituting the extruded resin layer is preferably 100°C to 140°C, more preferably 100°C to 130°C, and even more preferably 100°C to 120°C, from the viewpoint of balancing heat resistance and adhesiveness.

[0234] The extruded resin layer may contain one or more types of polyethylene. The polyethylene content in the extruded resin layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. This configuration can improve, for example, the recyclability of the laminate.

[0235] In one embodiment, the extruded resin layer contains biomass polyethylene. The biomass content of the extruded resin layer may be, for example, 30% or more, 50% or more, or 70% or more. There is no particular upper limit to the biomass content, but it may be, for example, 99% or 98%.

[0236] In the laminate of this disclosure, the thickness of the extruded resin layer as the adhesive layer is preferably 5 μm to 40 μm, more preferably 10 μm to 30 μm. This improves, for example, adhesion and recyclability.

[0237] The extruded resin layer can be formed, for example, by melting polyethylene or a polyethylene composition and extruding it onto a stretched polyethylene substrate or a laminate comprising said substrate. The melting temperature at this time is, for example, 280°C to 340°C, preferably 290°C to 335°C.

[0238] In one embodiment, this disclosure uses a melt extrusion lamination method, particularly a sand lamination method, using a molten resin mainly containing polyethylene as a component, to bond a stretched polyethylene substrate or a laminate comprising the substrate with a sealant film. This allows for a higher polyethylene content in the laminate. Furthermore, compared to laminating the stretched polyethylene substrate or the laminate with the sealant layer by, for example, dry lamination, the drying time can be reduced, and therefore the production efficiency of the laminate can be improved.

[0239] In one embodiment, the laminate of the present disclosure includes an adhesive layer, which is made of an adhesive, between the stretched polyethylene substrate and the sealant layer. This improves, for example, the adhesion between the stretched polyethylene substrate and the sealant layer.

[0240] The adhesive may be any of a one-component curable adhesive, a two-component curable adhesive, and a non-curable adhesive. The adhesive may be a solvent-based adhesive or a solventless adhesive. Examples of the solvent-based adhesive include rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and urethane-based adhesives. Examples of the solventless adhesive include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, and urethane-based adhesives. Among these, urethane-based adhesives are preferred, and two-component curable urethane-based adhesives are more preferred.

[0241] Examples of the coating method of the adhesive include a direct gravure roll coating method, a gravure roll coating method, a kiss coating method, a reverse roll coating method, a fountain method, and a transfer roll coating method.

[0242] In the laminate of the present disclosure, the thickness of the adhesive layer composed of the above adhesive is, for example, 0.1 μm or more and 10 μm or less, preferably 0.2 μm or more and 8 μm or less, and more preferably 0.5 μm or more and 6 μm or less.

[0243] In one embodiment, the laminate of the present disclosure can be produced by bonding a stretched polyethylene substrate and a sealant film by a laminating method using the above adhesive. For example, it may be produced by bonding by a dry laminating method using a solvent-based adhesive, or may be produced by bonding by a non-solvent laminating method using a solventless adhesive.

[0244] <Anchor coat layer> In one embodiment, when the laminate of the present disclosure includes an extruded resin layer as an adhesive layer, an anchor coat layer may be further provided between the stretched polyethylene substrate and the extruded resin layer. Thereby, for example, the interlayer adhesion in the laminate can be improved. The anchor coat layer is formed by an anchor coating agent. In this embodiment, the extruded resin layer is in contact with the anchor coat layer.

[0245] Examples of the anchor coating agent include polyurethane-based, polyolefin-based, polyethyleneimine-based, or epoxy resin-based anchor coating agents. In one embodiment, the anchor coating agent is a two-component curable resin, for example, composed of a polyol as the main component and a polyisocyanate as the curing agent.

[0246] Examples of the polyol include polyether polyol, polyester polyol, and (meth)acrylic polyol. Examples of the polyisocyanate include aromatic polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenylene polyisocyanate, and aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate.

[0247] In one embodiment, the anchor coating layer is made of polyurethane obtained by the reaction of a polyol and a polyisocyanate. Specific examples of the polyurethane include polyether polyurethane, polyester polyurethane, and poly(meth)acrylic polyurethane.

[0248] The anchor coating layer can be formed, for example, by applying an anchor coating agent to a stretched polyethylene substrate. The anchor coating agent can be applied by coating methods such as roll coating, gravure roll coating, and kiss coating, or by printing methods.

[0249] [[ID= / / ]] The thickness of the anchor coating layer is, for example, 0.05 μm or more and 3.0 μm or less, preferably 0.1 μm or more and 2.0 μm or less, more preferably 0.2 μm or more and 1.0 μm or less.

[0250] [Application] The laminate of the present disclosure can be suitably used for packaging material applications. The packaging material is used to manufacture a packaging container. The packaging material comprises the laminate of the present disclosure. By using at least the packaging material comprising the laminate of the present disclosure, a packaging container with excellent low-temperature sealing properties and cutability (tearability) can be manufactured.

[0251] The packaging container comprises the laminate of the present disclosure. Examples of packaging containers include packaging bags, tube containers, and containers with lids. A container with a lid comprises a container body having a storage compartment and a lid material joined (heat-sealed) to the container body to seal the storage compartment.

[0252] Examples of heat sealing methods include bar seals, rotary roll seals, belt seals, impulse seals, high-frequency seals, and ultrasonic seals.

[0253] Examples of packaging bags include various types such as standing pouch type, side seal type, two-side seal type, three-side seal type, four-side seal type, envelope seal type, gusset seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, and gusset type.

[0254] The packaging bag may be equipped with an easy-open section. Examples of easy-open sections include a notch that serves as the starting point for tearing the packaging bag, and a half-cut line formed by laser processing or a cutter as a path when tearing the packaging bag.

[0255] In one embodiment, a packaging bag can be made by folding the laminate of the present disclosure in half so that the stretched polyethylene base material is on the outside and the sealant layer is on the inside, overlapping the two halves, and then heat-sealing the edges. In another embodiment, a packaging bag can be made by overlapping multiple laminates of the present disclosure so that the sealant layers face each other, and then heat-sealing the edges. The entire packaging bag may be made of the above laminate, or only a part of the packaging bag may be made of the above laminate.

[0256] In one embodiment, the laminate of the present disclosure is used as a lid material for a container with a lid.

[0257] Examples of contents that can be contained in the packaging container include liquids, solids, powders, and gels. The contents may be food or beverages, or non-food items such as chemicals, cosmetics, and pharmaceuticals. After the contents are placed in the packaging container, the container can be sealed by heat-sealing the opening.

[0258] As specific examples of packaging bags, small bags and standing pouches will be described below. A small pouch is a small packaging bag used to contain contents weighing, for example, 1g to 200g. Examples of contents that can be contained in a small pouch include powders such as powdered foods (e.g., furikake, fried chicken batter), powdered medicines, and powdered beverages (e.g., coffee, tea); sauces, soy sauce, dressings, ketchup, syrups, cooking alcoholic beverages, and other liquid or viscous seasonings; liquid soups, powdered soups, and fruit juices; spices; liquid beverages, jelly-like beverages, instant foods, and other food and beverages. A specific example of a small pouch is a stick-shaped packaging bag (stick pouch).

[0259] Standing pouches are used to contain contents ranging from 50g to 2000g. Examples of contents that can be contained in standing pouches include shampoo, rinse, conditioner, hand soap, body soap, fragrances, deodorizers, insect repellents, detergents; dressings, cooking oils, mayonnaise, and other liquid or viscous condiments; liquid beverages, jelly beverages, instant foods, and other food and beverages; and creams.

[0260] Figure 7 shows a packaging bag 50 obtained by bonding two laminates together. The shaded area indicates a heat-sealed portion. The packaging bag 50 may also be equipped with an easy-open section 51. Examples of the easy-open section 51 include a notch 52 that serves as the starting point for tearing, and a half-cut line 53 formed by laser processing or a cutter as a tearing path.

[0261] Figure 8 shows a simplified example of the configuration of a standing pouch. The shaded area indicates a heat-sealed portion. In one embodiment, the standing pouch 60 comprises a body portion 61 (side sheet 63) and a bottom portion 62 (bottom sheet 64). The side sheet 63 and the bottom sheet 64 may be made of the same material or of different materials. The bottom portion 62 maintains the shape of the body portion 61, thereby giving the pouch self-supporting ability and enabling it to be a standing pouch. A storage space for accommodating contents is formed within the area surrounded by the side sheet 63 and the bottom sheet 64. In the standing pouch 60, the laminate of this disclosure is used as the side sheet 63. Therefore, in the standing pouch 60, the pouch is manufactured so that the first layer of sealant film of the laminate constituting the side sheet 63 becomes the innermost layer.

[0262] In one embodiment, the side sheet can be formed by manufacturing a bag such that the sealant layer of the laminate of the present disclosure is the innermost layer. In another embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them so that the sealant layers face each other, and heat-sealing the side edges on both sides to form a bag.

[0263] In another embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them so that the sealant layers face each other, and inserting two V-shaped folded laminates with the sealant layers facing outwards into the gaps between the laminates at the side edges on both sides of the overlapped laminates, and then heat-sealing them. According to this manufacturing method, a standing pouch having a body with side gussets can be obtained.

[0264] In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the lower parts of the bag-formed side sheets and heat-sealing it. More specifically, the bottom sheet can be formed by inserting a laminate folded in a V-shape with the sealant layer facing outwards between the lower parts of the bag-formed side sheets and heat-sealing it.

[0265] In one embodiment, two of the above laminates are prepared, stacked with their sealant layers facing each other, and then another laminate is folded in a V-shape with the sealant layer on the outside, sandwiched between the lower parts of the facing laminates, and heat-sealed to form the bottom. Next, two sides adjacent to the bottom are heat-sealed to form the body. In this way, a standing pouch of one embodiment can be formed.

[0266] The present disclosure relates to, for example, the following [1] to

[16] . [1] A sealant film having a first surface and a second surface facing the first surface, the sealant film including a first layer constituting the first surface and a second layer, the first layer being the surface layer on one side of the sealant film, the first layer having a density of 0.910 g / cm 3 Containing the following linear low-density polyethylene, the second layer containing at least a copolymer of ethylene and an α-olefin having 4 carbon atoms as linear low-density polyethylene, and at least one selected from the linear low-density polyethylene contained in the first layer and the copolymer of ethylene and an α-olefin having 4 carbon atoms contained in the second layer being biomass-derived polyethylene, the sealant film. [2] The first layer has a density of 0.910 g / cm 3 Containing more than 50% by mass of the following linear low-density polyethylene, and the second layer containing more than 50% by mass of a copolymer of ethylene and an α-olefin having 4 carbon atoms, the sealant film according to [1] above. [3] The sealant film according to [1] or [2] above, wherein at least one layer selected from the first layer and the second layer further contains low-density polyethylene. [4] The sealant film according to any one of [1] to [3] above, wherein the second layer constitutes the second surface of the sealant film. [5] The sealant film according to any one of [1] to [4] above, comprising a first layer constituting a first surface, an intermediate layer, and a layer constituting a second surface, wherein the intermediate layer and / or the layer constituting the second surface is a second layer, and if the intermediate layer and the layer constituting the second surface are the second layer, at least one selected from linear low-density polyethylene contained in the first layer, a copolymer of ethylene and a carbon-4 α-olefin contained in the intermediate layer, and a copolymer of ethylene and a carbon-4 α-olefin contained in the layer constituting the second surface is biomass-derived polyethylene. [6] A sealant film according to any of [1] to [5] above, having a thickness of 10 μm or more and 60 μm or less. [7] A sealant film according to any of [1] to [6] above, wherein the polyethylene content is 90% by mass or more of 100% by mass of the sealant film. [8] A laminate comprising a stretched polyethylene substrate and a sealant layer, wherein the sealant layer is a sealant film according to any of [1] to [7] above, and the sealant film is arranged such that the second surface of the sealant film faces the stretched polyethylene substrate. [9] The laminate according to [8] above, wherein the stretched polyethylene substrate is a polyethylene substrate that has been uniaxially stretched.

[10] The laminate according to [8] or [9] above, comprising an extruded resin layer mainly containing polyethylene between a stretched polyethylene substrate and a sealant layer.

[11] The laminate according to

[10] , wherein the polyethylene in the extruded resin layer is at least one selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene.

[12] The laminate according to

[10] or

[11] , wherein the laminate further comprises an anchor coat layer between the stretched polyethylene substrate and the extruded resin layer, and the extruded resin layer is in contact with the anchor coat layer.

[13] The laminate according to [8] or [9] above, comprising an adhesive layer made of an adhesive between a stretched polyethylene substrate and a sealant layer.

[14] A laminate according to any of [8] to

[13] above, wherein the polyethylene content is 90% by mass or more of 100% by mass of the laminate.

[15] A laminate according to any of the above [8] to

[14] , used for packaging material applications.

[16] A packaging container comprising the laminate described in any of [8] to

[15] above. [Examples]

[0267] The sealant films and laminates of this disclosure will be described in more detail based on examples, but the sealant films and laminates of this disclosure are not limited in any way by the examples.

[0268] In the following descriptions, polyethylene film will also be referred to as "PE film," high-density polyethylene as "HDPE," medium-density polyethylene as "MDPE," low-density polyethylene as "LDPE," and linear low-density polyethylene as "LLDPE." LLDPE in which the comonomer is a C4 α-olefin will also be referred to as "C4LLDPE," LLDPE in which the comonomer is a C6 α-olefin will also be referred to as "C6LLDPE," and LLDPE in which the comonomer is a C8 α-olefin will also be referred to as "C8LLDPE." Antiblocking agents are also referred to as "AB agents." Anchor coating agents are also referred to as "AC agents." The polyethylene extruded resin layer is also referred to as "EC-PE". Polyurethane adhesive is also sometimes referred to as "PU adhesive."

[0269] [Production of stretched PE substrate (substrate film)] <Production of uniaxially stretched PE film (A)> HDPE (density: 0.961g / cm 3 (Melting point: 135℃, MFR: 0.7g / 10min, ExxonMobil, product name: HTA108) and MDPE (density: 0.941g / cm³) 3A PE film with a thickness of 125 μm was obtained by co-extrusion using Dowchemical's Elite 5538G (melting point: 129°C, MFR: 1.3 g / 10 min) by inflation molding, consisting of an HDPE layer, an MDPE layer, and another HDPE layer in that order. The thickness of each HDPE layer was 25 μm, and the thickness of the MDPE layer was 75 μm. This PE film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain a stretched PE film with a thickness of 25 μm. One side of this stretched PE film was subjected to corona treatment to adjust the wettability index to 52 dyn. The substrate obtained in this way will also be referred to as "uniaxially oriented PE film (A)". The haze value of uniaxially oriented PE film (A) was measured in accordance with JIS K7136 and was found to be 8.9%.

[0270] [Examples and Comparative Examples: Production of sealing film] <Production of PE film (A)> As the laminate layer, LDPE (density: 0.919 g / cm³) 3 MFR: 2.0g / 10min, Sumitomo Chemical Co., Ltd., Product name: Sumikasen G201-F) at a concentration of 20% by mass, C4LLDPE (Density: 0.918g / cm³) 3 A blend of 80% by mass of Ube Maruzen Polyethylene Co., Ltd. (product name: Yumerit 720FT), with an MFR of 4.0g / 10 mins, is used as the intermediate layer, and plant-derived C4LLDPE (density: 0.916 g / cm³) is used. 3 Using MFR: 1.0g / 10min, Braskem, product name: SLL118), C6LLDPE (density: 0.901g / cm³) was used as the sealing layer. 3 MFR: 2.0g / 10min, Nippon Polyethylene Co., Ltd., Product name: Kernel KF260T) at 80% by mass concentration, LDPE (density: 0.919g / cm³) 3 MFR: 2.0g / 10 min, Sumitomo Chemical Co., Ltd., Product name: Sumikasen G201-F) at a concentration of 10% by mass, containing zeolite and talc-containing antiblocking agent (density: 1.07g / cm³) 3A sealant film (PE film (A)) with a thickness of 50 μm and a laminate layer:intermediate layer:seal layer thickness ratio of 1:2:1 was obtained by blending (MFR: 10.4 g / 10 min, Tokyo Ink Co., Ltd., product name: PEX ABT-16) at a concentration of 10% by mass and co-extruding it using the inflation molding method. The biomass content of PE film (A) was 43%. When laminating PE film (A) with an adhesive described later, PE film (A) with one side (the laminate layer side) treated with corona was used.

[0271] A sealant film with a thickness of 50 μm (PE film (B) to (D)) was obtained in the same manner as described above, except that the compound composition of the laminate layer, intermediate layer, and seal layer was changed as shown in Table 1.

[0272] [Tensile test] The breaking strength and elongation at break of the sealant films prepared in the examples and comparative examples were measured in accordance with JIS Z1702:1994. A Tensilon universal material tester RTC-1530 (manufactured by Orientec Co., Ltd.) was used as the measuring instrument.

[0273] Specifically, first, a dumbbell-shaped piece of sealant film was prepared as the test specimen. The measurement width of the test specimen was 5 mm, the initial distance between the pair of chucks holding the test specimen was 50 mm, and the tensile speed was 200 mm / min. The environment during the measurement of breaking strength and breaking elongation was 25°C and 50% relative humidity. Breaking strength and breaking elongation were measured for both the MD and TD of the sealant film. The laminated material, described later, was tested in the same manner.

[0274] [Measurement of tear strength] The tear strength of the sealant film was measured using an Elmendorf tear tester (manufactured by Toyo Seiki Seisakusho) and the Elmendorf method (compliant with JIS K7128-2). A test specimen measuring 75 mm x 63 mm was used. Tear strength was measured for both the medium (MD) and tread (TD) of the sealant film. The tear strength of the laminate was measured using the Trouser method (compliant with JIS K7128-1) at a test speed of 200 mm / min. The test specimens used were 150 mm x 50 mm in size, with a 75 mm long slit running lengthwise through the center of the specimen. Tear strength was measured for both the medium-density (MD) and tangential (TD) layers of the laminate.

[0275] [Table 1]

[0276] [Example 1] Uniaxially oriented PE film (A) and PE film (A) were prepared. A 1 μm thick printed layer was formed on the corona-treated surface of a uniaxially oriented PE film (A) using a water-based flexographic ink (Toyo Ink Co., Ltd., product name: Aquariona). A laminate was obtained by bonding the printed layer surface of the uniaxially oriented PE film (A) and the corona-treated surface of the PE film (A) via a 3 μm thick adhesive layer made of a two-component curing polyurethane adhesive (Rock Paint Co., Ltd., RU-77T / H-7). The biomass content of the laminate in Example 1 was 27.2%.

[0277] [Comparative Examples 1, 3 and 5] A laminate was obtained in the same manner as in Example 1, except that PE films (B) to (D) listed in Table 3 were used instead of PE film (A).

[0278] [Example 2] Uniaxially oriented PE film (A) and PE film (A) were prepared. A 1 μm thick printed layer was formed on the corona-treated surface of a uniaxially oriented PE film (A) using a water-based flexographic ink (Toyo Ink Co., Ltd., product name: Aquariona). A two-component curing polyurethane adhesive (Mitsui Chemicals, Inc., A-3210 / A-3075) was applied to the printed layer as an anchor coat agent to form a 0.3 μm thick anchor coat layer. LDPE (density: 0.918 g / cm³) was applied to the anchor coat layer. 3A laminate was obtained by sand laminating a PE film (A) while melt-extruding (MFR: 7.0 g / 10 min, melting point: 106°C, Nippon Polyethylene Co., Ltd., product name: Novatec LC600A) to a thickness of 15 μm. The biomass content of the laminate in Example 2 was 23.5%.

[0279] [Comparative Examples 2, 4 and 6] A laminate was obtained in the same manner as in Example 2, except that PE films (B) to (D) listed in Table 3 were used instead of PE film (A).

[0280] [Measurement of seal strength] Using two of each laminate prepared in the examples and comparative examples, the sealant layers of the laminates were heated at temperatures of 90°C, 100°C, 110°C, or 120°C, and pressure of 1 kgf / cm². 2 The material was heat-sealed for 1 second to form a seal. Subsequently, a section including the seal was cut out to prepare a test piece with a width of 15 mm and a length of 100 mm for measuring the seal strength. The length of the seal section was 15 mm. The seal strength was measured in accordance with JIS K7127:1999 at a test speed of 300 mm / min. An Orientec SA-1150 tensile testing machine was used as the measuring instrument.

[0281] [Table 2]

[0282] [Table 3] [Explanation of Symbols]

[0283] 1: Laminate 10: Sealant film 12: First Layer 14, 14A, 14B: Second layer 16: The third layer 20: Adhesive layer or extruded resin layer 22: Anchor coat layer 30: Stretched polyethylene substrate 50: Packaging bag 51: Easy opening part 52: Notch section 53: Half-cut line 60: Standing Pouch 61: Torso 62: Bottom 63: Side seats 64: Bottom sheet

Claims

1. A laminate comprising at least an oriented polyethylene substrate and a sealant layer, The sealant layer is a sealant film, The sealant film has a first surface and a second surface facing the first surface. The sealant film comprises at least a first layer constituting the first surface, an intermediate layer, and a second layer constituting the second surface. The first layer is the surface layer on one side of the sealant film, and the first layer has a density of 0.910 g / cm³. ３ It contains the following linear low-density polyethylene: The intermediate layer and the second layer contain at least a copolymer of ethylene and a carbon-4 α-olefin as linear low-density polyethylene. The copolymer of ethylene and a carbon-4 α-olefin contained in the aforementioned intermediate layer is biomass-derived polyethylene. The sealant film is positioned such that its second surface faces the stretched polyethylene substrate. Laminated structure.

2. The first layer has a density of 0.910 g / cm³. ３ The laminate according to claim 1, wherein the following linear low-density polyethylene is contained in more than 50% by mass, and the second layer contains more than 50% by mass of the copolymer of ethylene and a carbon-4 α-olefin.

3. The laminate according to claim 1 or 2, wherein at least one layer selected from the first layer and the second layer further contains low-density polyethylene.

4. The laminate according to any one of claims 1 to 3, wherein the thickness of the sealant film is 10 μm or more and 60 μm or less.

5. The laminate according to any one of claims 1 to 4, wherein the polyethylene content is 90% by mass or more of 100% by mass of the sealant film.

6. The laminate according to any one of claims 1 to 5, wherein the stretched polyethylene substrate is a polyethylene substrate that has been uniaxially stretched.

7. The laminate according to any one of claims 1 to 6, further comprising an extruded resin layer containing polyethylene as the main component between the stretched polyethylene substrate and the sealant layer.

8. The laminate according to claim 7, wherein the polyethylene in the extruded resin layer is at least one selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene.

9. The laminate according to claim 7 or 8, wherein the laminate further comprises an anchor coat layer between the stretched polyethylene substrate and the extruded resin layer, and the extruded resin layer is in contact with the anchor coat layer.

10. The laminate according to claim 5 or 6, further comprising an adhesive layer made of an adhesive between the stretched polyethylene substrate and the sealant layer.

11. The laminate according to any one of claims 1 to 10, wherein the polyethylene content is 90% by mass or more of 100% by mass of the laminate.

12. A laminate according to any one of claims 1 to 11, used for packaging material applications.

13. A packaging container comprising a laminate according to any one of claims 1 to 12.

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