Laminate, packaging material, and packaging container

Abstract

To enhance the content of polyethylene in a laminate having a stretched polyethylene base material and a polyethylene layer as a sealant layer.SOLUTION: A laminate comprising a stretched polyethylene substrate and a sealant layer, wherein the stretched polyethylene substrate contains polyethylene as a main component, the sealant layer comprises a polyethylene layer containing polyethylene as a main component and a functional resin layer, and the laminate comprises an extruded resin layer containing polyethylene as a main component between the stretched polyethylene substrate and the sealant layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laminate, a packaging material, and a packaging container. [Background technology]

[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) together to achieve various functions (see, for example, Patent Document 1). Packaging containers are made from such film products. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-095454 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, efforts to address environmental issues such as plastic marine pollution and global warming have become increasingly important. Therefore, packaging materials and other materials are required to be highly recyclable. However, film products manufactured by laminating films of different materials are generally difficult to separate, making them difficult to recycle. To solve this problem, a technology called mono-materialization has been investigated, which increases recyclability by laminating films of the same material, polyethylene, together.

[0005] Monomaterialization using polyethylene can be achieved by bonding polyethylene films with different properties, for example, by bonding a stretched polyethylene film as a substrate with a polyethylene film as a sealant layer. However, using a conventional non-polyethylene adhesive to bond polyethylene films together reduces the polyethylene content, which can lead to a deterioration in the physical properties of the recycled material. Furthermore, providing a functional resin layer in the sealant layer to impart functions such as gas barrier properties further reduces the polyethylene content.

[0006] One problem to be solved by the present disclosure is to increase the polyethylene content in a laminate comprising a stretched polyethylene substrate and a polyethylene layer as a sealant layer. [Means for solving the problem]

[0007] The first laminate of the present disclosure comprises a stretched polyethylene substrate and a sealant layer, the stretched polyethylene substrate containing polyethylene as a primary component, the sealant layer comprising a polyethylene layer containing polyethylene as a primary component and a functional resin layer, and the laminate comprising an extruded resin layer containing polyethylene as a primary component between the stretched polyethylene substrate and the sealant layer. A second laminate of the present disclosure comprises a stretched polyethylene substrate and a sealant layer, wherein the stretched polyethylene substrate contains polyethylene as a main component, the sealant layer contains polyethylene as a main component, the laminate comprises a vapor-deposited film formed on the surface of the sealant layer facing the stretched polyethylene substrate, and the laminate comprises an extruded resin layer between the stretched polyethylene substrate and the vapor-deposited film, the extruded resin layer containing polyethylene as a main component. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to increase the polyethylene content in a laminate comprising an oriented polyethylene substrate and a sealant layer having a polyethylene layer and a functional resin layer. According to the present disclosure, it is possible to increase the polyethylene content in a laminate comprising an oriented polyethylene substrate, a polyethylene layer as a sealant layer, and a vapor-deposited film formed on the surface of the sealant layer. Because the laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component between the oriented polyethylene substrate and the sealant layer, it is possible to increase the polyethylene content while using, for example, a sealant layer having a functional resin layer. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of one embodiment of a laminate according to the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. [Figure 3] FIG. 3 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. [Figure 5] FIG. 5 is a schematic cross-sectional view of one embodiment of a laminate of the present disclosure. [Figure 6] FIG. 6 is a schematic cross-sectional view of one embodiment of a laminate of the present disclosure. [Figure 7] FIG. 7 is a perspective view of one embodiment of a standing pouch. [Figure 8] FIG. 8 is a perspective view of one embodiment of a standing pouch. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail. The present disclosure can be implemented in many different forms, and should not be construed as being limited to the description of the embodiments exemplified below. For clarity of explanation, the drawings may show the width, thickness, shape, etc. of each layer more schematically than in the embodiments, but these are merely examples and do not limit the interpretation of the present disclosure. In this specification and each drawing, elements similar to those already described with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0011] [Laminate] The first laminate of the present disclosure includes a stretched polyethylene substrate, a sealant layer having a polyethylene layer and a functional resin layer, and an extruded resin layer containing polyethylene as a main component between the stretched polyethylene substrate and the sealant layer.

[0012] The second laminate of the present disclosure includes a stretched polyethylene substrate, a polyethylene layer as a sealant layer, and a vapor-deposited film formed on the surface of the sealant layer facing the stretched polyethylene substrate. The second laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component between the stretched polyethylene substrate and the vapor-deposited film. The first laminate and the second laminate of the present disclosure are also collectively referred to as "the laminate of the present disclosure."

[0013] In one embodiment of the laminate of the present disclosure, the stretched polyethylene substrate and the polyethylene layer of the sealant layer each contain the same type of resin material, polyethylene, as a main component. By using a laminate having such a configuration, for example, a packaging container with excellent recyclability can be produced.

[0014] In the present disclosure, the terms "AAA contains polyethylene as a main component," "AAA containing polyethylene as a main component," and similar expressions 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.

[0015] For example, polyethylene includes high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene, which are classified as the same type of resin material, whereas polyethylene and polyester are not classified as the same type of resin material.

[0016] In the present disclosure, polyethylene refers to a polymer in which the content of ethylene-derived structural units in all repeating structural units is 50 mol% or more. 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 90 mol% or more, and particularly preferably 95 mol% or more. The content can be measured by NMR.

[0017] In the present disclosure, the polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and an ethylenically unsaturated monomer other than ethylene. Examples of the ethylenically unsaturated monomer 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.

[0018] In the present disclosure, polyethylene includes, for example, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, and very low density polyethylene.

[0019] In the present disclosure, the density of the polyethylene is as follows: The density of the high density polyethylene is preferably 0.945 g / cm 3 The upper limit of the density of high-density polyethylene is, for example, 0.965 g / cm 3 The density of the medium density polyethylene is preferably 0.925 g / cm 3 More than 0.945g / cm 3 The density of the low density polyethylene is preferably less than 0.900 g / cm 3 More than 0.925g / cm 3 The density of the linear low density polyethylene is preferably less than 0.900 g / cm 3 More than 0.925g / cm 3 The density of the very low density polyethylene is preferably less than 0.900 g / cm 3 The lower limit of the density of the 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).

[0020] Low-density polyethylene is typically obtained by polymerizing ethylene using a high-pressure polymerization process. Linear low-density polyethylene is typically obtained by polymerizing ethylene and a small amount of α-olefins using a low-pressure polymerization process (e.g., polymerization using a Ziegler-Natta catalyst or a metallocene catalyst).

[0021] Polyethylenes with different densities or branches can be obtained by appropriately selecting a polymerization method. For example, it is preferable to use a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as a polymerization catalyst and carry out polymerization in one or more stages by any of gas phase polymerization, slurry polymerization, solution polymerization, and high-pressure ionic polymerization.

[0022] 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 activating cocatalyst. Single-site catalysts are preferred because they have a more uniform structure of the active site than multi-site catalysts, making it possible to obtain polymers with high molecular weights and highly uniform structures.

[0023] The single-site catalyst is preferably a metallocene catalyst, which comprises a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a cocatalyst, an organometallic compound as needed, and a support as needed.

[0024] Examples of the transition metal in the transition metal compound include zirconium, titanium, and hafnium, with zirconium and hafnium being preferred.

[0025] The cyclopentadienyl skeleton in the transition metal compound is a cyclopentadienyl group or a substituted cyclopentadienyl group. The substituted cyclopentadienyl group has at least one substituent selected from, for example, a hydrocarbon group having from 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. The substituted cyclopentadienyl group has one or more substituents, and the substituents may be bonded to each other to form a ring, such as an indenyl ring, a fluorenyl ring, an azulenyl ring, or a hydrogenated product thereof. The ring formed by bonding the substituents to each other may further have a substituent.

[0026] The transition metal compound usually has two ligands having a cyclopentadienyl skeleton. The ligands having each cyclopentadienyl skeleton are preferably bonded to each other via a bridging group. Examples of the bridging group 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.

[0027] The co-catalyst refers to a component that enables a transition metal compound of Group IV of the periodic table to function effectively as a polymerization catalyst or a component that balances the ionic charge in a catalytically activated state. Examples of the co-catalyst include benzene-soluble aluminoxanes or benzene-insoluble organoaluminum oxy-compounds, ion-exchangeable layered silicates, boron compounds, ionic compounds consisting of a cation with or without an active hydrogen group and a non-coordinating anion, lanthanoid salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing a fluoro group.

[0028] Examples of organometallic compounds that may be used as needed include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these, organoaluminum compounds are preferred.

[0029] The transition metal compound may be used by being supported on an inorganic or organic carrier, preferably a porous oxide of an inorganic or organic compound, such as montmorillonite or other ion-exchangeable layered silicates, SiO2, Al2O3, MgO, ZrO2, TiO2, BO3, CaO, ZnO, BaO, ThO2, or mixtures thereof.

[0030] In the present disclosure, polyethylene may be derived from biomass (hereinafter also referred to as "biomass polyethylene"). That is, as a raw material for obtaining polyethylene, ethylene derived from biomass may be used instead of ethylene obtained from fossil fuels. Biomass polyethylene is a carbon-neutral material, and therefore can reduce the environmental impact of laminates or packaging materials. Biomass polyethylene can be produced, for example, by the method described in JP 2013-177531 A. Commercially available biomass polyethylene may also be used.

[0031] Biomass-derived ethylene, which is the raw material for biomass polyethylene, can be obtained by a conventionally known method. An example of a method for producing biomass-derived ethylene will be described below.

[0032] 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 raw materials. As the plant raw material, conventionally known plants can be used, for example, corn, sugarcane, beet, and manioc.

[0033] Fermented ethanol derived from biomass refers to ethanol produced by contacting a culture solution containing a carbon source obtained from plant raw materials with an ethanol-producing microorganism or a product derived from the disrupted microorganism, followed by purification. Purification of ethanol from the culture solution can be achieved by conventional methods such as distillation, membrane separation, and extraction. Examples include methods of adding benzene, cyclohexane, etc., followed by azeotropy, or removing water by membrane separation. To obtain the ethylene, the ethanol may be further purified at this stage to reduce the total impurity content to 1 ppm or less.

[0034] A catalyst is usually used to obtain ethylene by dehydration of ethanol. A conventionally known catalyst can be used as the catalyst. A fixed-bed flow reaction is an advantageous reaction method from the viewpoint of process, since it allows easy separation of the catalyst and the product. For example, γ-alumina is preferred.

[0035] Since this dehydration reaction is an endothermic reaction, it is usually carried out under heated conditions. The heating temperature is not limited as long as the reaction proceeds at a commercially useful reaction rate, but is preferably 100°C or higher, 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 preferably 500°C or lower, more preferably 400°C or lower.

[0036] 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 avoid water in terms of the efficiency of water removal. However, in the case of ethanol dehydration using a solid catalyst, the absence of water tends to increase the amount of other olefins, particularly butene, produced. This is presumably because the presence of a small amount of water makes it difficult to suppress ethylene dimerization after dehydration. The water content is, for example, 0.1% by mass or more, preferably 0.5% by mass or more. From the viewpoints of material 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.

[0037] 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 in a gaseous state at room temperature and below about 5 MPa, water and ethanol can be removed from this mixture by gas-liquid separation to obtain ethylene. This can be done by a known method.

[0038] The ethylene obtained by the gas-liquid separation is further distilled. The distillation method, operation temperature, residence time, etc. are not particularly limited, except that the operation pressure at this time must be atmospheric pressure or higher.

[0039] 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 (e.g., ketones, aldehydes, and esters) and their decomposition products (carbon dioxide), as well as nitrogen-containing compounds (e.g., amines and amino acids) and their decomposition products (ammonia). Depending on the intended use of ethylene, these trace amounts of impurities may be problematic, so they may be removed by purification. Purification can be carried out by conventionally known methods. Suitable purification procedures include, for example, adsorption purification. Conventionally known adsorbents can be used as the adsorbent. For example, a material with a high surface area is preferred, and the type of adsorbent is selected depending on the type and amount of impurities in the ethylene obtained by the dehydration reaction of biomass-derived ethanol.

[0040] A caustic water treatment may be used in combination as a method for purifying impurities in ethylene. When caustic water treatment is used, it is preferable to perform it before adsorption purification. In this case, it is necessary to perform a water removal treatment after the caustic treatment and before adsorption purification.

[0041] Biomass polyethylene is polyethylene obtained by polymerizing a monomer containing biomass-derived ethylene. As the biomass-derived ethylene, it is preferable to use ethylene obtained by the above-mentioned production method. Since biomass-derived ethylene is used as the raw material monomer, the polymerized polyethylene is biomass-derived.

[0042] The raw material monomers for biomass polyethylene do not have to contain 100% by mass of biomass-derived ethylene. The raw material monomers for biomass polyethylene may further contain ethylene derived from fossil fuels in addition to biomass-derived ethylene.

[0043] Atmospheric carbon dioxide contains a certain proportion of C14 (105.5 pMC), and it is known that the C14 content in plants that grow by absorbing atmospheric carbon dioxide, such as corn, is also approximately 105.5 pMC. It is also known that fossil fuels contain very little C14. Therefore, the proportion of biomass-derived carbon can be calculated by measuring the proportion of C14 in total carbon atoms. In this disclosure, "biomass ratio" refers to the weight ratio of biomass-derived components. Take polyethylene terephthalate as an example. Polyethylene terephthalate is a polymer formed by polymerizing ethylene glycol containing two carbon atoms and terephthalic acid containing eight carbon atoms in a 1:1 molar ratio. When only biomass-derived ethylene glycol is used, the weight ratio of biomass-derived components in the polyester is 31.25%. Therefore, the theoretical biomass ratio 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 the fossil fuel-derived polyester produced using fossil fuel-derived ethylene glycol and fossil fuel-derived dicarboxylic acid is 0%, and the biomass content of the fossil fuel-derived polyester is 0%. Hereinafter, unless otherwise specified, "biomass content" refers to the weight ratio of biomass-derived components.

[0044] Theoretically, if all ethylene derived from biomass is used as a raw material for polyethylene, the concentration of biomass-derived ethylene will be 100%, and the biomass content of biomass polyethylene will be 100%. However, the concentration of biomass-derived ethylene in fossil fuel polyethylene produced only from fossil fuel-derived raw materials will be 0%, and the biomass content of fossil fuel polyethylene will be 0%.

[0045] Specific examples of biomass polyethylene include biomass high-density polyethylene, biomass medium-density polyethylene, biomass low-density polyethylene, biomass linear low-density polyethylene, and biomass very 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 the biomass polyethylene, plant-derived polyethylene is preferred.

[0046] In the present disclosure, the biomass polyethylene or biomass-derived resin layer does not need to have a biomass content of 100%. This is because if even a part of the laminate is made from biomass-derived raw materials, it is in line with the purpose of reducing the amount of fossil fuel used compared to conventional methods.

[0047] The biomass ratio of the laminate of the present disclosure may be, for example, 5% to 70%, 8% to 40%, or 10% to 30%, which can reduce the environmental impact of the laminate or packaging material, for example.

[0048] The polyethylene may be recycled mechanically or chemically. This reduces the environmental impact of laminates or packaging materials. Mechanical recycling generally involves crushing recovered polyethylene film, washing it with an alkali to remove dirt and foreign matter from the film surface, and then drying it at high temperature and reduced pressure for a certain period of time to disperse any contaminants remaining inside the film, decontaminating it, and returning it to polyethylene. Chemical recycling generally involves breaking down recovered polyethylene film to the monomer level and repolymerizing the monomer to obtain polyethylene. The above description of polyethylene is applicable to the polyethylene in the following description.

[0049] The polyethylene content of the entire laminate of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more or 95% by mass or more. In the present disclosure, as described below, an extruded resin layer containing polyethylene as a main component is used as an adhesive layer, so the polyethylene content can be high. Since such a laminate uses polyethylene, which is the same type of resin material, it can be classified as a so-called monomaterial material and can be suitably used, for example, for producing monomaterial packaging containers.

[0050] Figures 1 and 2 show one embodiment of a first laminate of the present disclosure. The laminate 1 of Figure 1 comprises, in this order in the thickness direction, an oriented polyethylene substrate 10, an extruded resin layer 20, and a sealant layer 30 having a functional resin layer 32, an adhesive resin layer 34, and a polyethylene layer 36. The laminate 1 of Figure 2 further comprises an anchor coat layer 22 between the oriented polyethylene substrate 10 and the extruded resin layer 20. The extruded resin layer 20 is in contact with the anchor coat layer 22.

[0051] 3 and 4 show an embodiment of the first laminate of the present disclosure. The laminate 1 of Fig. 3 further includes a vapor-deposited film 38 between the sealant layer 30 and the extruded resin layer 20 in Fig. 1. The laminate 1 of Fig. 4 further includes a vapor-deposited film 38 between the sealant layer 30 and the extruded resin layer 20 in Fig. 2. The vapor-deposited film 38 is formed on the surface of the functional resin layer 32 of the sealant layer 30.

[0052] 1 to 4 show an embodiment in which the sealant layer 30 includes the functional resin layer 32, the adhesive resin layer 34, and the polyethylene layer 36, but an embodiment in which the adhesive resin layer 34 is not provided is also possible.

[0053] Figures 5 and 6 show one embodiment of a second laminate of the present disclosure. The laminate 1 of Figure 5 includes an oriented polyethylene substrate 10, an extruded resin layer 20, a vapor-deposited film 38, and a sealant layer 30, in this order in the thickness direction. The laminate 1 of Figure 6 further includes an anchor coat layer 22 between the oriented polyethylene substrate 10 and the extruded resin layer 20. The extruded resin layer 20 is in contact with the anchor coat layer 22. The vapor-deposited film 38 is formed on one surface of the sealant layer 30.

[0054] In one embodiment, the laminate 1 further includes a printed layer (not shown) on the stretched polyethylene substrate 10. The printed layer is formed, for example, on the surface of the stretched polyethylene substrate 10 facing the sealant layer 30. The printed layer is located, for example, between the stretched polyethylene substrate 10 and the extruded resin layer 20 (or the anchor coat layer 22, if provided).

[0055] <Stretched polyethylene base material> The stretched polyethylene substrate contains polyethylene as a main component. Because the resin material constituting the stretched polyethylene substrate is polyethylene, which is the same type of resin material as the resin material constituting the polyethylene layer in the sealant layer, a laminate having such a configuration can be suitably used as a laminate for producing a mono-material packaging container.

[0056] From the viewpoint of the strength and heat resistance of the stretched polyethylene substrate, high density polyethylene and medium density polyethylene are preferred, and from the viewpoint of suitability for stretching, medium density polyethylene is preferred.

[0057] 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 viewpoints of film-forming properties and processability of the laminate. The MFR of polyethylene is measured by Method A in accordance with JIS K7210, at a temperature of 190°C and a load of 2.16 kg.

[0058] For example, when a stretched polyethylene substrate is produced by the T-die method, the MFR of the polyethylene constituting the stretched polyethylene 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.

[0059] For example, when a stretched polyethylene substrate is produced by an inflation method, the MFR of the polyethylene constituting the stretched polyethylene 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.

[0060] From the viewpoint of heat resistance, the melting point (Tm) of the polyethylene constituting the stretched polyethylene substrate is preferably 100° C. or higher and 140° C. or lower, more preferably 110° C. or higher and 140° C. or lower, and even more preferably 120° C. or higher and 140° C. or lower. Tm is determined by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0061] The stretched polyethylene substrate can contain one or more polyethylenes. The content of polyethylene 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 the recyclability of the laminate, for example.

[0062] When the stretched polyethylene substrate has a multilayer structure, the polyethylene content in each layer constituting the substrate is independently preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. Such a configuration can, for example, improve the recyclability of the laminate.

[0063] 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. When the stretched polyethylene substrate has a multilayer structure, each layer constituting the substrate can independently contain the above-mentioned resin materials.

[0064] The stretched polyethylene substrate may contain one or more additives. Examples of additives include crosslinking agents, antiblocking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins. When the stretched polyethylene substrate has a multilayer structure, each layer constituting the substrate can independently contain the above-mentioned additives.

[0065] The stretched polyethylene substrate is a polyethylene substrate that has been subjected to a stretching treatment. The stretching treatment can improve, for example, the heat resistance and strength of the polyethylene substrate. Such a stretched polyethylene substrate can satisfy the physical properties required for, for example, the outer layer of a packaging material.

[0066] 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.

[0067] A stretching ratio of 2 times or more can improve, for example, the rigidity, strength, and heat resistance of the substrate, improve the printability of the substrate, and improve the transparency of the substrate.A stretching ratio of 10 times or less can achieve good stretching without causing breakage of the film, for example.

[0068] In one embodiment, the stretched polyethylene substrate is a uniaxially stretched film, more specifically, a uniaxially stretched film that has been stretched in the machine direction (MD).

[0069] The stretched polyethylene substrate may have a single-layer structure or a multilayer structure. Hereinafter, a stretched polyethylene substrate having a multilayer structure will also be referred to as an "stretched multilayer substrate." A stretched multilayer substrate is preferred from the viewpoint of improving its strength, heat resistance, and stretchability.

[0070] The stretched multilayer substrate has a multilayer structure of two or more layers. In one embodiment, the number of layers in the stretched multilayer substrate is from 2 to 7, for example, from 3 to 7, or from 3 to 5. The number of layers in the stretched multilayer substrate is preferably an odd number, for example, 3, 5, or 7. The multilayer structure of the stretched multilayer substrate can improve the balance between rigidity, strength, heat resistance, printability, and stretchability of the substrate. Each layer of the stretched multilayer substrate also preferably contains polyethylene as a main component.

[0071] Hereinafter, several examples of embodiments of the stretched multilayer base material will be described. Hereinafter, a layer containing 80% or more by mass of high-density polyethylene will be referred to as a "high-density polyethylene layer," a layer containing 80% or more by mass of medium-density polyethylene will be referred to as a "medium-density polyethylene layer," a layer containing 80% or more by mass of low-density polyethylene will be referred to as a "low-density polyethylene layer," a layer containing 80% or more by mass of linear low-density polyethylene will be referred to as a "linear low-density polyethylene layer," and a layer containing 80% or more by mass of very-low-density polyethylene will be referred to as an "ultra-low-density polyethylene layer."

[0072] 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 the high-density polyethylene layer as the surface resin layer of the substrate can improve, for example, the strength and heat resistance of the substrate. Having the medium-density polyethylene layer in the substrate can improve, for example, the stretchability of the pre-stretched laminate.

[0073] The stretched multilayer substrate of the second embodiment includes a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer in this order in the thickness direction. This configuration can improve the strength and heat resistance of the substrate, suppress curling in the substrate, and improve the stretchability of the pre-stretched laminate, for example.

[0074] In the stretched multilayer base materials of the first and second embodiments, the thickness of the high-density polyethylene layer is preferably equal to or less than 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.

[0075] The stretched multilayer substrate of the third embodiment comprises, in this order in the thickness direction, 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 simplicity, these three layers are collectively referred to as the "low-density polyethylene layer, etc."), a medium-density polyethylene layer, and a high-density polyethylene layer. This configuration can, for example, improve the stretchability of the laminate before stretching, improve the strength and heat resistance of the substrate, and suppress curling in the substrate.

[0076] In the stretched multilayer substrate of the third embodiment, the thickness of the high-density polyethylene layer is preferably equal to or less than the thickness of the medium-density polyethylene layer, and 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.

[0077] 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.

[0078] Other embodiments of the stretched multilayer substrate include a substrate comprising, in this order in the thickness direction, 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; and a substrate comprising, in this order in the thickness direction, 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.

[0079] Further, a substrate may be provided with, in the thickness direction, a high-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, a low-density polyethylene layer or the like, a blend layer of high-density polyethylene and medium-density polyethylene, and a high-density polyethylene layer in this order.

[0080] The stretched multilayer substrate of the fourth embodiment includes, in the thickness direction, a medium-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 medium-density polyethylene layer, in this order. This configuration can improve, for example, the printability, strength, and heat resistance of the substrate, and the stretchability of the pre-stretched laminate.

[0081] In the 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.

[0082] The stretched multilayer substrate of the fifth embodiment includes, 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 another medium-density polyethylene layer, in this order. This configuration can improve, for example, the printability, strength, and heat resistance of the substrate, and the stretchability of the pre-stretched laminate.

[0083] In the 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.

[0084] The stretched multilayer substrate of the sixth embodiment includes, 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, in this order. This configuration can improve, for example, the printability, strength, and heat resistance of the substrate, and the stretchability of the pre-stretched laminate.

[0085] In the blend layers 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.

[0086] In the 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.

[0087] The stretched multilayer substrate of the seventh embodiment includes, 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. This configuration can improve, for example, the printability, strength, and heat resistance of the substrate, and the stretchability of the pre-stretched laminate.

[0088] In the blend layers 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, more preferably 0.4 or more and 2.4 or less.

[0089] 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.

[0090] 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.

[0091] The mass ratio of the medium-density polyethylene to the high-density polyethylene (medium-density polyethylene / high-density polyethylene) in the first layer and the fifth layer is preferably 1.1 or more and 5 or less, more preferably 1.5 or more and 3 or less, thereby further improving the balance between ink adhesion and heat resistance.

[0092] The total content of the medium-density polyethylene and the high-density polyethylene in the first layer and the fifth layer is independently preferably at least 80% by mass, more preferably at least 90% by mass, and even more preferably at least 95% by mass, thereby further improving the ink adhesion and heat resistance of the substrate.

[0093] The second layer and the fourth layer may each independently further contain low-density polyethylene, which can further improve the balance of heat resistance, rigidity, and processability of the substrate.

[0094] The mass ratio of high-density polyethylene to low-density polyethylene (high-density polyethylene / low-density polyethylene) in the second layer and the fourth layer is independently preferably from 1 to 4, more preferably from 1.5 to 3. This allows the substrate to have a better balance of heat resistance, rigidity, and processability.

[0095] The content of high-density polyethylene in each of the second layer and the fourth layer is preferably more than 50% by mass, more preferably 55% by mass or more, and even more preferably 60% by mass or more, which can further improve the heat resistance of the substrate.

[0096] The total content of high-density polyethylene and low-density polyethylene in the second layer and the fourth layer is independently preferably at least 80% by mass, more preferably at least 90% by mass, and even more preferably at least 95% by mass, thereby further improving the balance between heat resistance, rigidity, and processability of the substrate.

[0097] The thickness of each of the second layer and the fourth layer is independently preferably 0.5 μm to 15 μm, more preferably 1 μm to 10 μm, and even more preferably 1 μm to 8 μm, which can further improve the heat resistance of the substrate.

[0098] The third layer may further contain low density polyethylene.

[0099] The content of the linear low-density polyethylene in the third layer is preferably more than 50% by mass, more preferably at least 60% by mass, even more preferably at least 70% by mass, and even more preferably at least 80%, at least 90%, or at least 95% by mass, thereby further improving the balance between heat resistance, rigidity, and extensibility.

[0100] 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.

[0101] The thickness of the third layer is preferably from 1 μm to 50 μm, more preferably from 2 μm to 40 μm, and even more preferably from 5 μm to 30 μm, which can further improve the balance between heat resistance, rigidity, and stretchability.

[0102] The ratio of the total thickness of the second layer and the fourth layer to the thickness of the third layer (total thickness of the second layer and the fourth layer / 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 can further improve the rigidity, strength, and heat resistance of the substrate.

[0103] In the stretched multilayer substrates of the fourth to eighth embodiments, the thickness of each of the two surface resin layers is preferably from 0.5 μm to 10 μm, more preferably from 1 μm to 8 μm, and even more preferably from 1 μm to 5 μm, which can further improve, for example, the heat resistance and printability of the substrate.

[0104] In the stretched multilayer substrates of the fourth to eighth embodiments, the thickness of each of the two surface resin layers is preferably smaller than the total thickness of the three inner layers (the multilayer intermediate layer). The ratio of the thickness of each of the two surface resin layers to the total thickness of the multilayer intermediate layer (surface resin layer / multilayer intermediate layer) is preferably 0.05 to 0.8, more preferably 0.1 to 0.7, and even more preferably 0.1 to 0.4. This can further improve, for example, the rigidity, strength, and heat resistance of the substrate.

[0105] In the 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 between each layer. By providing a density gradient in the stretched multilayer substrate, for example, its strength, heat resistance, and stretchability can be improved.

[0106] In a stretched multilayer substrate having a density gradient, the absolute value of the density difference between any two adjacent layers is preferably small. The absolute value of the density difference is preferably 0.040 g / cm 3 or less, more preferably 0.030 g / cm 3 or less, more preferably 0.020 g / cm 3 This configuration makes it possible to effectively prevent, for example, delamination at the interfaces between the layers.

[0107] In the present disclosure, the density of each layer may be measured in accordance with the above-mentioned JIS K7112, or may be calculated from the density of the components constituting the layer. For example, when one layer contains multiple components (n types; n is an integer of 2 or more) with different densities (e.g., polyethylene), the average density D calculated according to the following formula (f1) av may be the density of the layer.

[0108] D av = ΣW i ×D i …(f1) In formula (f1), Σ is W for i from 1 to n. i ×D i where n is an integer greater than or equal to 2, and Wi denotes the mass fraction of the i-th component, and D i is the density of the i-th component (g / cm 3 ) is shown.

[0109] 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. The smaller the haze value, the better, 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.

[0110] The thickness of the stretched polyethylene substrate is preferably 10 μm or more and 60 μm or less, more preferably 15 μm or more and 50 μm or less. When the thickness of the substrate is 10 μm or more, the rigidity and strength of the laminate can be improved. When the thickness of the substrate is 60 μm or less, the processability of the laminate can be improved.

[0111] The stretched polyethylene substrate may be subjected to a surface treatment. This can improve the adhesion between the substrate and a layer laminated thereon, for example. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using gases such as oxygen gas and nitrogen gas, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals. An anchor coating layer may be formed on the surface of the stretched polyethylene substrate using a conventional anchor coating agent.

[0112] A stretched polyethylene substrate can be produced by, for example, forming a film of polyethylene or a polyethylene resin composition by the inflation method or the T-die method, and stretching the film. A stretched multilayer substrate can be produced by, for example, forming a laminate from a plurality of polyethylenes or polyethylene resin compositions by the inflation method or the T-die method, and stretching the resulting laminate. The stretching treatment can improve the transparency, rigidity, strength, and heat resistance of the polyethylene substrate, making the substrate suitable for use as, for example, a substrate for packaging materials. Stretching can also be performed in an inflation film-forming machine.

[0113] In one embodiment, the stretched polyethylene substrate having a multilayer structure is a coextruded resin film, and each layer constituting the substrate is a coextruded resin layer. The coextruded resin film can be produced by film formation using, for example, an inflation method or a T-die method.

[0114] In one embodiment, the stretched multilayer substrate is obtained by stretching a laminate (precursor) having a multilayer structure. Specifically, the resin materials constituting each layer are co-extruded into a tubular shape to form a film, thereby producing a laminate. Alternatively, the resin materials constituting each layer are co-extruded into a tubular shape, and then the opposing layers are pressure-bonded together using a rubber roll or the like to produce a laminate. By producing a laminate using such a method, the number of defective products can be significantly reduced, and production efficiency can be improved.

[0115] In one embodiment, the stretched polyethylene substrate contains biomass polyethylene. In this case, 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%.

[0116] When the stretched polyethylene substrate has a multilayer structure, that is, when the stretched polyethylene substrate has two or more resin layers containing polyethylene as a main component, at least one of the resin layers may contain biomass polyethylene.

[0117] For example, consider a stretched polyethylene substrate having, in the thickness direction, a first resin layer containing high-density polyethylene as a primary component, a second resin layer containing medium-density polyethylene as a primary component, and a third resin layer containing high-density polyethylene as a primary component, in that order. 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.

[0118] The laminate of the present disclosure may include a vapor-deposited film formed on the surface of the stretched polyethylene substrate on the side of the sealant layer, thereby improving, for example, the oxygen barrier property and water vapor barrier property of the laminate.

[0119] The details of the vapor-deposited film will be described later. The surface of the vapor-deposited film may be subjected to the above-mentioned surface treatment, which can improve the adhesion between the vapor-deposited film and a layer adjacent to the vapor-deposited film, for example.

[0120] <Print layer> In one embodiment, the laminate of the present disclosure may further include a printed layer formed on the above-described stretched polyethylene substrate. In one embodiment, the laminate of the present disclosure preferably includes a printed layer on the surface of the stretched polyethylene substrate facing the sealant layer, since this can suppress deterioration of the image over time.

[0121] The printed layer includes, for example, an image. Examples of images include letters, 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 the environmental load. Furthermore, from the viewpoint of reducing the environmental load, the printed layer may be formed on the surface of the substrate or the like using a biomass-derived ink.

[0122] 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.

[0123] <Anchor coat layer> In one embodiment, the laminate of the present disclosure may further include an anchor coat layer between the stretched polyethylene substrate and the extruded resin layer. This can improve interlayer adhesion in the laminate, for example. The anchor coat layer is formed from an anchor coating agent. In this embodiment, the extruded resin layer is in contact with the anchor coat layer.

[0124] Examples of the anchor coating agent include polyurethane-based, polyolefin-based, and epoxy resin-based anchor coating agents. In one embodiment, the anchor coating agent is a two-component curing resin, and is composed of, for example, a polyol as a base agent and a polyisocyanate as a curing agent.

[0125] Examples of polyols include polyether polyols, polyester polyols, and (meth)acrylic polyols. Examples of polyisocyanates 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.

[0126] In one embodiment, the anchor coat layer is made of polyurethane obtained by reacting a polyol with a polyisocyanate. Specific examples of polyurethane include polyether polyurethane, polyester polyurethane, and poly(meth)acrylic polyurethane.

[0127] The anchor coat layer can be formed, for example, by applying an anchor coat agent to the stretched polyethylene substrate or the surface of the stretched polyethylene substrate on which the printing layer is to be formed. The anchor coat agent can be applied by a coating method such as roll coating, gravure roll coating, or kiss coating, or by a printing method.

[0128] The thickness of the anchor coat 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, and more preferably 0.2 μm or more and 1.0 μm or less.

[0129] <Extruded resin layer> The laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component 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 a laminate including the stretched polyethylene substrate and the sealant layer. A laminate including the stretched polyethylene substrate includes, for example, the stretched polyethylene substrate and other layers such as a printing layer and an anchor coat layer. Here, a vapor-deposited film may be formed on the surface of the sealant layer facing the stretched polyethylene substrate; this embodiment is also referred to as a "vapor-deposited sealant layer."

[0130] The laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component as an adhesive layer between the stretched polyethylene substrate or the laminate and the sealant layer or vapor-deposited sealant layer, thereby enabling the polyethylene content in the laminate to be increased compared to when a conventional non-polyethylene adhesive (e.g., a two-component curing polyurethane adhesive) is used, thereby improving the recyclability of the laminate.

[0131] The extruded resin layer contains polyethylene as a main component. The 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.

[0132] From the viewpoint of adhesiveness, the polyethylene constituting the extruded resin layer is preferably at least one selected from low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene, and more preferably low-density polyethylene or linear low-density polyethylene. Biomass polyethylene, or mechanically or chemically recycled polyethylene may also be used.

[0133] The melt flow rate (MFR) of the polyethylene constituting the extruded resin layer is preferably 0.1 g / 10 min or more and 50 g / 10 min or less, more preferably 0.2 g / 10 min or more and 30 g / 10 min or less, and even more preferably 3.0 g / 10 min or more and 20 g / 10 min or less, from the viewpoints of film-forming properties and processability of the laminate.

[0134] From the viewpoint of a balance between heat resistance and adhesiveness, the melting point (Tm) of the polyethylene constituting the extruded resin layer is preferably 100°C or higher and 140°C or lower, more preferably 100°C or higher and 130°C or lower, and even more preferably 100°C or higher and 120°C or lower.

[0135] The extruded resin layer may contain one or more polyethylenes. The content of polyethylene 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. Such a configuration can improve the recyclability of the laminate, for example.

[0136] In one embodiment, the extruded resin layer contains biomass polyethylene. In this case, the biomass content of the extruded resin layer may be, for example, 30% or more, 50% or more, or 70% or more. The upper limit of the biomass content is not particularly limited, but may be, for example, 99% or 98%.

[0137] In the laminate of the present disclosure, the thickness of the extruded resin layer serving as the adhesive layer is preferably 5 μm or more and 40 μm or less, more preferably 10 μm or more and 30 μm or less, which can improve, for example, adhesiveness and recyclability.

[0138] The extruded resin layer can be formed, for example, by melting polyethylene or a polyethylene resin composition and extruding it onto a stretched polyethylene substrate or a laminate comprising the substrate at a melting temperature of, for example, 280°C or higher and 340°C or lower, preferably 290°C or higher and 335°C or lower.

[0139] In one embodiment, the present disclosure uses a melt extrusion lamination method, particularly a sand lamination method, using a molten resin containing polyethylene as a primary component to bond a stretched polyethylene substrate or a laminate including the substrate to a sealant film serving as a sealant layer or a vapor-deposited sealant film serving as a vapor-deposited sealant layer. This method allows for a high polyethylene content in the laminate. Furthermore, the present disclosure reduces the time required for the drying and aging processes compared to laminating a stretched polyethylene substrate or the laminate to a sealant layer or a vapor-deposited sealant layer by, for example, dry lamination, thereby improving the production efficiency of the laminate.

[0140] <Sealant layer> The sealant layer in the first laminate of the present disclosure comprises: a polyethylene layer containing polyethylene as a main component; an adhesive resin layer as needed; Functional resin layer are provided in this order in the thickness direction. The sealant layer in the second laminate of the present disclosure is a polyethylene layer containing polyethylene as a main component.

[0141] The total thickness of the sealant layer is preferably from 10 μm to 300 μm, more preferably from 15 μm to 250 μm, and in one embodiment from 20 μm to 60 μm, or from 40 μm to 200 μm. From the viewpoint of the strength and processability of the sealant layer, it is preferable that the total thickness of the sealant layer be changed appropriately depending on the mass of the contents to be contained in the packaging container described below.

[0142] For example, when the packaging container is a small pouch, the total thickness of the sealant layer is preferably 20 μm or more and 60 μm or less. In this case, for example, 1 g or more and 200 g or less of contents can be well accommodated in the small pouch. When the sealant layer is thin, bonding the stretched polyethylene substrate and the sealant film using a conventional non-polyethylene adhesive significantly reduces the polyethylene content in the entire laminate. In one embodiment of the present disclosure, the stretched polyethylene substrate and the sealant film are bonded together using an extruded resin layer containing polyethylene as a main component, thereby increasing the polyethylene content.

[0143] For example, when the packaging container is a stand-up pouch, the total thickness of the sealant layer is preferably 40 μm to 200 μm, more preferably 60 μm to 150 μm, so that the contents of, for example, 50 g to 2000 g can be easily accommodated in the stand-up pouch.

[0144] In one embodiment, the sealant layer is an unstretched coextruded resin film, and each layer constituting the sealant layer is a coextruded resin layer. The coextruded resin film can be produced by film formation using, for example, an inflation method or a T-die method. This allows, for example, the formation of a thin functional resin layer. In one embodiment, the sealant layer in the first laminate of the present disclosure is obtained by coextrusion film formation of a material constituting the polyethylene layer, and, if the sealant layer includes an adhesive resin layer, a material constituting the adhesive resin layer, and a material constituting the functional resin layer, using a conventionally known method such as the T-die method or the inflation method.

[0145] The surface of the sealant layer may be subjected to the above-mentioned surface treatment, which can improve the adhesion between the sealant layer and a layer adjacent to the sealant layer, for example.

[0146] In the first laminate of the present disclosure, the polyethylene content in the sealant layer is preferably 60% by mass or more and 95% by mass or less, more preferably 65% ​​by mass or more and 90% by mass or less. This configuration can improve the recyclability of the laminate, for example.

[0147] (Polyethylene layer) The polyethylene layer contains polyethylene as a main component. In one embodiment, the polyethylene layer in the sealant layer is an unstretched layer (unstretched polyethylene layer). The unstretched layer is a layer that has not been subjected to a stretching treatment, such as an extruded film that has not been subjected to a stretching treatment. Details of the stretching treatment are as described above in the description of the substrate.

[0148] The polyethylene in the sealant layer may be the same as or different from the polyethylene in the stretched polyethylene substrate or the polyethylene in the extruded resin layer.

[0149] From the viewpoint of heat sealing property, the polyethylene constituting the polyethylene layer is preferably at least one selected from low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene, and more preferably linear low-density polyethylene. Biomass polyethylene, or mechanically or chemically recycled polyethylene may also be used.

[0150] The melt flow rate (MFR) of the polyethylene constituting the polyethylene layer is preferably 0.1 g / 10 min or more and 50 g / 10 min or less, more preferably 0.2 g / 10 min or more and 30 g / 10 min or less, and even more preferably 0.3 g / 10 min or more and 20 g / 10 min or less, from the viewpoints of film-forming properties and processability of the laminate.

[0151] The melting point (Tm) of the polyethylene constituting the polyethylene layer is preferably 90°C or higher and 140°C or lower, more preferably 90°C or higher and 130°C or lower, and even more preferably 90°C or higher and 120°C or lower, from the viewpoint of a balance between heat resistance and heat sealability.

[0152] The polyethylene layer can contain one or more types of polyethylene. The polyethylene content in the polyethylene layer 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 packaging materials made of the laminate of the present disclosure can be improved.

[0153] When the polyethylene layer has a multilayer structure, the polyethylene content in each layer constituting the polyethylene layer is independently preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. Such a configuration can, for example, improve the recyclability of the laminate.

[0154] The polyethylene layer 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. When the polyethylene layer has a multilayer structure, each layer constituting the polyethylene layer may independently contain the above-mentioned resin materials.

[0155] The polyethylene layer may contain one or more additives. Examples of additives include crosslinking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins. When the polyethylene layer has a multilayer structure, each layer constituting the polyethylene layer may independently contain the above-mentioned additives.

[0156] The polyethylene layer may have a single-layer structure or a multi-layer structure. In one embodiment, the number of polyethylene layers having a multilayer structure is 2 to 7, for example, 3 to 7, or 3 to 5. The number of polyethylene layers is preferably an odd number, for example, 3, 5, or 7. With such a configuration, for example, the symmetry of the laminated structure of the polyethylene layers is increased, and curling in the polyethylene layers can be suppressed.

[0157] In one embodiment, the polyethylene layer contains biomass polyethylene. In this case, the biomass content of the polyethylene layer may be, for example, 10% or more, 10% to 80%, 20% to 75%, or 30% to 70%.

[0158] When the polyethylene layer has a multilayer structure, that is, when the polyethylene layer has two or more resin layers containing polyethylene as a main component, at least one of the resin layers may contain biomass polyethylene.

[0159] The ratio of the thickness of the polyethylene layer to the total thickness of the sealant layer in the first laminate of the present disclosure is preferably 40% or more and 95% or less, more preferably 50% or more and 93% or less, and even more preferably 60% or more and 90% or less.

[0160] In one embodiment, the polyethylene layer constitutes a surface layer of the first laminate of the present disclosure. In one embodiment, when a packaging container is produced using a packaging material made of the first laminate of the present disclosure, the polyethylene layer is the layer facing the contents to be contained in the packaging container, i.e., the innermost layer of the packaging container. This ensures sufficient heat seal strength even when heat-sealed at a low temperature (e.g., about 140°C).

[0161] (adhesive resin layer) The sealant layer in the first laminate of the present disclosure may include an adhesive resin layer between the polyethylene layer and the functional resin layer, which can improve adhesion between the polyethylene layer and the functional resin layer, for example.

[0162] The adhesive resin layer contains one or more resin materials. Examples of the resin materials include polyolefins, modified polyolefins, vinyl resins, polyethers, polyesters, polyamides, polyurethanes, silicone resins, epoxy resins, and phenolic resins. Among these, polyolefins and modified polyolefins are preferred from the viewpoints of recyclability and adhesion, and modified polyolefins such as acid-modified polyolefins are more preferred.

[0163] Examples of modified polyolefins include polyolefins modified with unsaturated carboxylic acids such as maleic acid and fumaric acid, or their acid anhydrides, esters, or metal salts, particularly graft-modified polyolefins. Among resin materials, modified polyolefins are preferred from the viewpoint of obtaining a structure suitable for mono-material packaging materials.

[0164] From the viewpoint of film-forming ability and processability, the melt flow rate (MFR) of the modified polyolefin is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.3 g / 10 min to 30 g / 10 min, even more preferably 0.5 g / 10 min to 10 g / 10 min, and particularly preferably 0.5 g / 10 min to 5.0 g / 10 min. The MFR of the modified polyolefin is measured in accordance with ASTM D1238 at a temperature of 190°C and a load of 2.16 kg, although the measurement temperature may be changed depending on the melting point of the modified polyolefin.

[0165] The adhesive resin layer may contain one or more of the above additives.

[0166] The thickness of the adhesive resin layer is preferably 0.5 μm to 15 μm, more preferably 1.0 μm to 10 μm. When the thickness is equal to or greater than the lower limit, the adhesion can be improved, for example. When the thickness is equal to or less than the upper limit, the recyclability of the laminate can be improved, for example.

[0167] (Functional resin layer) The sealant layer in the first laminate of the present disclosure includes a functional resin layer. In one embodiment, the functional resin layer is a gas barrier resin layer. This can improve, for example, the gas barrier properties (specifically, oxygen barrier properties and / or water vapor barrier properties) of the laminate. Furthermore, by forming a vapor-deposited film on the gas barrier resin layer, for example, the adhesion of the vapor-deposited film can be improved.

[0168] The gas barrier resin layer contains one or more gas barrier resins. Examples of gas barrier resins include polyamide, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyester, polyurethane, and (meth)acrylic resin. Among these, polyamide and ethylene-vinyl alcohol copolymer are preferred from the viewpoint of oxygen barrier property and / or water vapor barrier property.

[0169] Examples of polyamides include aliphatic polyamides and semi-aromatic polyamides. As the polyamide, aliphatic polyamides are preferred, and crystalline aliphatic polyamides are more preferred.

[0170] Examples of aliphatic polyamides include aliphatic homopolyamides and aliphatic copolyamides. In the following examples, polyamides are also referred to as "PA."

[0171] Specific examples of aliphatic homopolyamides include polycaprolactam (PA6), polyenantholactam (PA7), polyundecane lactam (PA11), polylauryllactam (PA12), polyhexamethylene adipamide (PA66), polytetramethylene dodecamide (PA412), polypentamethylene azelamide (PA59), polypentamethylene sebacamide (PA510), polypentamethylene dodecamide (PA512), polyhexamethylene azelamide (PA69), polyhexamethylene sebacamide (PA610), polyhexamethylene dodecamide (PA612), poly Examples include nonamethylene adipamide (PA96), polynonameethylene azelamide (PA99), polynonameethylene sebacamide (PA910), polynonameethylene dodecamide (PA912), polydecamethylene adipamide (PA106), polydecamethylene azelamide (PA109), polydecamethylene decamide (PA1010), polydecamethylene dodecamide (PA1012), polydodecamethylene adipamide (PA126), polydodecamethylene azelamide (PA129), polydodecamethylene sebacamide (PA1210), and polydodecamethylene dodecamide (PA1212).

[0172] Specific examples of aliphatic copolymer polyamides include caprolactam / hexamethylenediaminoadipic acid copolymer (PA6 / 66), caprolactam / hexamethylenediaminoazelaic acid copolymer (PA6 / 69), caprolactam / hexamethylenediaminosebacic acid copolymer (PA6 / 610), caprolactam / hexamethylenediaminoundecanoic acid copolymer (PA6 / 611), caprolactam / hexamethylenediaminododecanoic acid copolymer (PA6 / 612), caprolactam / amino Examples include undecanoic acid copolymer (PA6 / 11), caprolactam / lauryllactam copolymer (PA6 / 12), caprolactam / hexamethylenediaminoadipic acid / lauryllactam copolymer (PA6 / 66 / 12), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminosebacic acid copolymer (PA6 / 66 / 610), and caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminododecanedicarboxylic acid copolymer (PA6 / 66 / 612).

[0173] The relative viscosity of the aliphatic polyamide is preferably 1.5 to 5.0, more preferably 2.0 to 5.0, and even more preferably 2.5 to 4.5. The relative viscosity of the aliphatic polyamide is measured at 25°C in accordance with JIS K6920 by dissolving 1 g of polyamide in 100 mL of 96% concentrated sulfuric acid.

[0174] The semi-aromatic polyamide is a polyamide having structural units derived from an aromatic diamine and structural units derived from an aliphatic dicarboxylic acid, or a polyamide having structural units derived from an aliphatic diamine and structural units derived from an aromatic dicarboxylic acid. Examples include polyamides composed of an aromatic diamine and an aliphatic dicarboxylic acid, and polyamides composed of an aliphatic diamine and an aromatic dicarboxylic acid.

[0175] Specific examples of semi-aromatic polyamides include polyhexamethylene terephthalamide (PA6T), polyhexamethylene isophthalamide (PA6I), polynonamethylene terephthalamide (PA9T), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (PA66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (PA66 / 6I), polyhexamethylene terephthalamide / polycaproamide copolymer (PA6T / 6), polyhexamethylene isophthalamide / polycaproamide copolymer (PA6I / 6), polyhexamethylene terephthalamide / polycaproamide copolymer (PA6I / 6), and polyhexamethylene terephthalamide / polycaproamide copolymer (PA6I / 6). Examples include lidodecaamide copolymer (PA6T / 12), polyhexamethylene isophthalamide / polyhexamethylene terephthalamide copolymer (PA6I / 6T), polyhexamethylene terephthalamide / poly(2-methylpentamethylene terephthalamide) copolymer (PA6T / M5T), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (PA66 / 6T / 6I), polyhexamethylene adipamide / polycaproamide / polyhexamethylene isophthalamide copolymer (PA66 / 6 / 6I), and polymetaxylylene adipamide (PAMXD6).

[0176] The melt volume rate (MVR) of the semi-aromatic polyamide is preferably 5 cm 3 / 200cm for more than 10 minutes 3 / 10 minutes or less, preferably 10cm 3 / 100cm for more than 10 minutes 3 The MVR is measured in accordance with ISO 1133 at a temperature of 275°C and a load of 5 kg.

[0177] In one embodiment, the gas barrier resin layer contains a crystalline aliphatic polyamide, such as PA6, PA11, PA12, PA66, PA610, PA612, PA6 / 66, and PA6 / 66 / 12.

[0178] The melting point (Tm) of the crystalline aliphatic polyamide is preferably 180° C. or higher and 300° C. or lower, more preferably 180° C. or higher and 250° C. or lower, and even more preferably 180° C. or higher and 230° C. In the present disclosure, Tm is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0179] The content of structural units derived from ethylene in the ethylene-vinyl alcohol copolymer (EVOH) (ethylene content) is preferably 20 mol% or more and 60 mol% or less, more preferably 25 mol% or more and 50 mol% or less. When the ethylene content is equal to or more than the lower limit, for example, the processability of the laminate can be improved. When the ethylene content is equal to or less than the upper limit, for example, the oxygen barrier property and / or water vapor barrier property of the laminate can be improved. The ethylene content is measured by NMR.

[0180] The melting point (Tm) of EVOH is preferably 130°C or higher and 200°C or lower, more preferably 140°C or higher and 195°C or lower, and even more preferably 150°C or higher and 190°C or lower.

[0181] From the viewpoint of film-forming property and processability, the melt flow rate (MFR) of EVOH is preferably 0.1 g / 10 min to 30 g / 10 min, more preferably 0.3 g / 10 min to 20 g / 10 min, and even more preferably 0.5 g / 10 min to 10 g / 10 min. The MFR of EVOH is measured in accordance with ASTM D1238 at a temperature of 190°C and a load of 2.16 kg, but the measurement temperature may be 210°C depending on the melting point of EVOH.

[0182] The content of the gas barrier resin in the gas barrier resin layer is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, 85% by mass or more, or 90% by mass or more, which can improve, for example, the oxygen barrier property and / or water vapor barrier property of the laminate.

[0183] In one embodiment, the functional resin layer is a heat-resistant resin layer, which can improve the heat resistance of the laminate, for example.

[0184] In one embodiment, the heat-resistant resin layer contains one or more resins having a melting point of 180° C. or higher (hereinafter also referred to as "high-melting-point resins"). Examples of high-melting-point resins include polyamides, polyimides, polyesters, polyolefins, vinyl resins, (meth)acrylic resins, cellulose resins, and ionomer resins, which have a melting point of 180° C. or higher.

[0185] The melting point of the high-melting-point resin is 180°C or higher, preferably 185°C or higher. When the melting point is equal to or higher than the lower limit, for example, the heat resistance of the sealant layer can be further improved, and the adhesion of the vapor-deposited film can also be further improved. The melting point of the high-melting-point resin is preferably 250°C or lower, more preferably 230°C or lower. This can improve, for example, the film-forming properties of the functional resin layer.

[0186] As the high-melting-point resin, a resin having a polar group is preferred. The polar group refers to a group containing one or more heteroatoms, and examples thereof include ester groups, epoxy groups, hydroxyl groups, amino groups, amide groups, urethane groups, carboxy groups, carbonyl groups, carboxylic anhydride groups, sulfo groups, thiol groups, and halogen groups. Among these, from the viewpoint of the gas barrier properties and laminate strength of the packaging container, hydroxyl groups, ester groups, amino groups, amide groups, carboxy groups, and carbonyl groups are preferred, and amide groups are more preferred. By forming a vapor-deposited film on a heat-resistant resin layer made of such a resin, for example, the adhesion of the vapor-deposited film can be improved.

[0187] Examples of high melting point resins having polar groups include polyamides, polyesters, ethylene-vinyl alcohol copolymers, and polyvinyl alcohols, which have a melting point of 180° C. or higher.

[0188] The content of the high-melting-point resin in the heat-resistant resin layer is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, 85% by mass or more, or 90% by mass or more, which can improve the heat resistance of the laminate, for example.

[0189] The difference between the melting point of the resin contained in the functional resin layer and the melting point of the polyethylene contained in the polyethylene layer is preferably not more than 90° C., more preferably not more than 80° C., and even more preferably not more than 70° C. When the difference is not more than the upper limit, for example, the film formability of the sealant layer can be improved.

[0190] The functional resin layer may contain one or more additives, such as a crosslinking agent, an antioxidant, an antiblocking agent, a slip agent, an ultraviolet absorber, a light stabilizer, a filler, a reinforcing agent, an antistatic agent, a compatibilizer, and a pigment.

[0191] The thickness of the functional resin layer is preferably 0.5 μm to 15 μm, more preferably 1.0 μm to 10 μm. When the thickness is equal to or greater than the lower limit, for example, the effect of the functional resin layer can be improved. When the thickness is equal to or less than the upper limit, for example, the recyclability of the laminate can be improved.

[0192] In one embodiment, the thickness of the functional resin layer is preferably smaller than the thickness of the polyethylene layer. This can improve the recyclability of the laminate, for example. The thickness of the functional resin layer is preferably smaller than the thickness of the polyethylene layer by 5 μm or more, and more preferably by 10 μm or more.

[0193] <Vapor deposition film> In one embodiment, the first laminate of the present disclosure may include a vapor-deposited film formed on the surface of the sealant layer facing the stretched polyethylene substrate. The second laminate of the present disclosure includes a vapor-deposited film formed on the surface of the sealant layer facing the stretched polyethylene substrate. This can improve, for example, the oxygen barrier property and water vapor barrier property of the laminate. In one embodiment, the vapor-deposited film of the first laminate of the present disclosure is provided on the surface of the functional resin layer of the sealant layer.

[0194] Examples of vapor-deposited films include those made of 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, and carbon-containing silicon oxide vapor-deposited films are preferred.

[0195] The carbon-containing silicon oxide vapor-deposited film contains silicon, oxygen, and carbon. In one embodiment of the 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 the total of the three elements silicon, oxygen, and carbon (100%). By setting the carbon content C within the above range, for example, deterioration in gas barrier properties can be suppressed even when the laminate is bent. In this specification, the proportion of each element is on a molar basis.

[0196] In one embodiment of the 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 the oxygen content O within the above ranges, for example, deterioration of the gas barrier property can be further suppressed even when the laminate is bent.

[0197] In one embodiment of the carbon-containing silicon oxide vapor-deposited film, the oxygen ratio O is preferably higher than the carbon ratio C, and the silicon ratio Si is preferably lower than the carbon ratio C. The oxygen ratio O is preferably higher than the silicon ratio Si, that is, the ratios preferably decrease in the order of ratio O, ratio C, and ratio Si. This makes it possible to further suppress a decrease in gas barrier properties, for example, even when the laminate is bent.

[0198] The proportions C, Si, and O in the carbon-containing silicon oxide vapor-deposited film can be measured by narrow scan analysis using X-ray photoelectron spectroscopy (XPS) under the following measurement conditions.

[0199] (Measurement conditions) Equipment used: "ESCA-3400" (manufactured by Kratos) [1] Spectral collection conditions Incident X-ray: MgKα (monochromatic X-ray, hν=1253.6eV) X-ray output: 150W (10kV 15mA) X-ray scanning area (measurement area): approx. 6 mm diameter Photoelectron capture angle: 90 degrees [2] Ion sputtering conditions Ion species: Ar + Acceleration voltage: 0.2 (kV) Emission current: 20 (mA) Etching range: 10mmφ Ion sputtering time: 30 seconds, and the spectrum was collected.

[0200] The thickness of the vapor-deposited film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and even more preferably 10 nm or more and 40 nm or less. By making the thickness of the vapor-deposited film 1 nm or more, for example, the oxygen barrier property and water vapor barrier property of the laminate can be further improved. By making the thickness of the vapor-deposited film 150 nm or less, for example, the occurrence of cracks in the vapor-deposited film can be suppressed and the recyclability of the laminate can be improved.

[0201] 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-enhanced chemical vapor deposition, thermal chemical 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 combining both physical vapor deposition and chemical vapor deposition.

[0202] The vacuum level in the deposition chamber was 10 -2 ~10 -8 After oxygen is introduced, the pressure is preferably about 10 -1 ~10 -6 The pressure is preferably about 100 mbar. The amount of oxygen introduced varies depending on the size of the deposition machine. An inert gas such as argon, helium, or nitrogen may be used as a carrier gas for the oxygen introduced, provided that no problems occur. The transport speed of the target film on which the deposition film is formed is, for example, 10 m / min or more and 800 m / min or less.

[0203] The surface of the vapor-deposited film may be subjected to the above-mentioned surface treatment, which can improve the adhesion between the vapor-deposited film and a layer adjacent to the vapor-deposited film, for example.

[0204] <Barrier coat layer> For example, when the vapor-deposited film is composed of an inorganic oxide such as aluminum oxide, silicon oxide, or silicon carbide 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.

[0205] In one embodiment, the barrier coat layer contains a gas barrier resin as a main component, such as polyesters (e.g., ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate), polyamides (e.g., nylon 6, nylon 6,6, and polymetaxylylene adipamide), polyurethanes, and (meth)acrylic resins.

[0206] The content of the gas barrier resin 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. Such a configuration can improve, for example, the gas barrier properties of the barrier coat layer.

[0207] The thickness of the barrier coat layer is preferably 0.01 μm or more and 10.0 μm or less, more preferably 0.1 μm or more and 5.0 μm or less. By making the thickness of the barrier coat layer 0.01 μm or more, for example, the gas barrier property can be further improved.

[0208] The barrier coat layer can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent, applying the resulting coating liquid, and drying it. The barrier coat layer can also be formed by applying and drying a commercially available barrier coating agent.

[0209] 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, and then adding water, an organic solvent, and a sol-gel catalyst to obtain a gas barrier composition, which is then coated on a vapor-deposited film and dried. The gas barrier coating layer contains a hydrolysis polycondensate obtained by hydrolyzing and polycondensing a metal alkoxide or the like by a sol-gel method. By providing such a barrier coat layer on a vapor-deposited film, the occurrence of cracks in the vapor-deposited film can be effectively suppressed. Each of the above components can be used alone or in combination.

[0210] The metal alkoxide is represented by, for example, formula (1). R 1 n M(OR 2 ) m (1) In formula (1), R 1 and R 2 each independently represents an organic group having 1 to 8 carbon atoms; M represents a metal atom; n represents an integer of 0 or more; m represents an integer of 1 or more; and n+m represents the valence of M.

[0211] R 1 and R 2 Examples of the organic group include alkyl groups having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an n-hexyl group, and an n-octyl group. The metal atom M is, for example, silicon, zirconium, titanium or aluminum.

[0212] Examples of metal alkoxides include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0213] Examples of water-soluble polymers include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Depending on the desired physical properties, such as oxygen barrier property, water vapor barrier property, 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 the metal alkoxide.

[0214] As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used, and an organoalkoxysilane having an epoxy group is preferred, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the metal alkoxide.

[0215] The gas barrier composition may contain water in a proportion of preferably 0.1 to 100 moles, more preferably 0.5 to 60 moles, per mole of metal alkoxide. By setting the water content at or above the lower limit, for example, the oxygen barrier property and water vapor barrier property of the laminate can be improved. By setting the water content at or below the upper limit, for example, the hydrolysis reaction can be carried out quickly.

[0216] Examples of organic solvents that can be used in preparing the gas barrier composition include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, and n-butyl alcohol.

[0217] The sol-gel catalyst is preferably an acid or an amine compound. Examples of the acid 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 the acid used is preferably 0.001 mol or more and 0.05 mol or less per 1 mol of the total molar amount of the metal alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.

[0218] Examples of the amine compound include N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. The amount of the amine compound used is preferably 0.01 to 1.0 parts by mass per 100 parts by mass of the total amount of the metal alkoxide and the silane coupling agent.

[0219] Examples of methods for applying the gas barrier composition include roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, and applicator coating.

[0220] Hereinafter, one embodiment of the method for forming the gas barrier coating layer will be described. A gas barrier composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and, if necessary, a silane coupling agent. A polycondensation reaction gradually progresses within the composition. The composition is then coated onto the vapor-deposited film by a conventional method and dried. This drying process further promotes polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains one) to form a composite polymer layer. Multiple composite polymer layers may be laminated by repeating the above process. For example, the coated composition is heated at a temperature of preferably 20°C to 150°C, more preferably 50°C to 120°C, and even more preferably 50°C to 100°C, for 1 second to 10 minutes. This process forms a gas barrier coating layer.

[0221] 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, which can improve the gas barrier properties and prevent cracks from occurring in the vapor-deposited film, for example.

[0222] [Application] The laminate of the present disclosure can be suitably used for packaging material applications. The packaging material is used to produce a packaging container. The packaging material comprises the laminate of the present disclosure. The packaging container can be produced by using at least the packaging material comprising the laminate of the present disclosure.

[0223] A packaging container includes the laminate of the present disclosure. Examples of packaging containers include packaging bags, tube containers, and lidded containers. The lidded container includes a container body having a storage section and a lid material joined (heat sealed) to the container body so as to seal the storage section.

[0224] Examples of heat sealing methods include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

[0225] Examples of packaging bags include various types of packaging bags such as a standing pouch type, a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope seal type, a palm seal type (pillow seal type), a pleated seal type, a flat bottom seal type, a square bottom seal type, and a gusset type.

[0226] The packaging bag may have an easy-to-open portion. Examples of the easy-to-open portion include a notch portion that serves as a starting point for tearing the packaging bag, and a half-cut line formed by laser processing or a cutter as a path for tearing the packaging bag.

[0227] In one embodiment, a packaging bag can be produced by folding the laminate of the present disclosure in half and overlapping it so that the stretched polyethylene substrate is on the outside and the sealant layer is on the inside, and then heat-sealing the edges, etc. In another embodiment, a packaging bag can be produced by overlapping multiple laminates of the present disclosure so that the sealant layers face each other, and then heat-sealing the edges, etc. The entire packaging bag may be made of the above-mentioned laminate, or only a portion of the packaging bag may be made of the above-mentioned laminate.

[0228] In one embodiment, the laminate of the present disclosure is used as a lid material for a lidded container.

[0229] The contents to be contained in the packaging container include, for example, liquids, solids, powders, and gels. The contents may be food or beverages, or non-food or beverages such as chemicals, cosmetics, and pharmaceuticals. After the contents are contained in the packaging container, the opening of the packaging container can be heat-sealed to seal the packaging container.

[0230] As specific examples of packaging bags, small pouches and standing pouches will be described below. A sachet is a small packaging bag used to hold contents of, for example, 1 g to 200 g, such as sauces, soy sauce, dressings, ketchup, syrup, cooking alcohol, other liquid or viscous seasonings, liquid soups, powdered soups, fruit juices, spices, liquid beverages, jelly-like beverages, instant foods, and other foods and beverages.

[0231] Stand-up pouches are used to store contents of, for example, 50 g to 2000 g, including shampoo, rinse, conditioner, hand soap, body soap, air freshener, deodorant, insect repellent, detergent, dressing, cooking oil, mayonnaise, other liquid or viscous seasonings, liquid beverages, jelly-like beverages, instant foods, other foods and beverages, and creams.

[0232] FIG. 6 is a simplified diagram showing an example of the configuration of a stand-up pouch. In the figure, the hatched areas represent heat-sealed portions. As shown in FIG. 6, in one embodiment, a stand-up pouch 40 comprises a body portion (side sheets) 41 and a bottom portion (bottom sheet) 42. The side sheets 41 and the bottom sheet 42 may be made of the same material, or may be made of different materials. The bottom sheet maintains the shape of the side sheets, thereby imparting self-supporting properties to the pouch and enabling it to be a standing pouch. A storage space for storing contents is formed within the area surrounded by the side sheets and the bottom sheet.

[0233] In a stand-up pouch, only the body portion may be made of the laminate of the present disclosure, only the bottom portion may be made of the laminate of the present disclosure, or both the body portion and the bottom portion may be made of the laminate of the present disclosure.

[0234] In one embodiment, the side sheets can be formed by preparing two laminates of the present disclosure, overlapping them with the sealant layers facing each other, and heat-sealing both side edges to form a bag.

[0235] In another embodiment, the side sheets can be formed by preparing two laminates of the present disclosure, overlapping them with the sealant layers facing each other, inserting two V-shaped laminates with the sealant layers facing outward between the laminates at the side edges on both sides of the overlapped laminates, and heat-sealing them. This production method results in a standing pouch 40 having a body portion 41 with side gussets 43, as shown in FIG. 7.

[0236] In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the lower portions of the side sheets of a bag and heat sealing them. More specifically, the bottom sheet can be formed by inserting the laminate folded in a V shape with the sealant layer facing outward between the lower portions of the side sheets of a bag and heat sealing them.

[0237] In one embodiment, two of the above laminates are prepared and stacked together with the sealant layers facing each other. Then, another of the above laminates is folded in a V shape with the sealant layer facing outward, and this is sandwiched between the two laminates and heat-sealed to form a bottom. Next, two sides adjacent to the bottom are heat-sealed to form a body. In this manner, a standing pouch according to one embodiment can be formed.

[0238] The present disclosure relates to, for example, the following [1] to

[13] . [1] A laminate comprising a stretched polyethylene substrate and a sealant layer, wherein the stretched polyethylene substrate contains polyethylene as a main component, the sealant layer comprises a polyethylene layer containing polyethylene as a main component, and a functional resin layer, and the laminate comprises an extruded resin layer containing polyethylene as a main component between the stretched polyethylene substrate and the sealant layer. [2] The laminate according to the above [1], wherein the functional resin layer is a gas barrier resin layer or a heat-resistant resin layer. [3] The laminate according to [1] or [2] above, wherein the sealant layer further comprises an adhesive resin layer between the polyethylene layer and the functional resin layer. [4] The laminate according to any one of the above [1] to [3], further comprising a vapor-deposited film formed on the surface of the sealant layer on the side of the stretched polyethylene substrate. [5] A laminate comprising a stretched polyethylene substrate and a sealant layer, wherein the stretched polyethylene substrate contains polyethylene as a main component, the sealant layer contains polyethylene as a main component, the laminate comprises a vapor-deposited film formed on the surface of the sealant layer facing the stretched polyethylene substrate, and the laminate comprises an extruded resin layer between the stretched polyethylene substrate and the vapor-deposited film, the extruded resin layer containing polyethylene as a main component. [6] The laminate according to any one of the above [1] to [5], wherein the thickness of the sealant layer is 20 μm or more and 60 μm or less. [7] The laminate according to any one of the above [1] to [6], wherein the stretched polyethylene substrate is a polyethylene substrate that has been subjected to a uniaxial stretching treatment or a biaxial stretching treatment. [8] The laminate according to any one of the above [1] to [7], further comprising a printed layer on the surface of the stretched polyethylene substrate on the side of the sealant layer. [9] The laminate according to any one of the above [1] to [8], further comprising 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 any one of the above [1] to [9], wherein the content of polyethylene is 85% by mass or more in 100% by mass of the laminate.

[11] The laminate according to any one of the above [1] to

[10] , which is used for packaging material applications.

[12] A packaging material comprising the laminate according to any one of [1] to

[11] above.

[13] A packaging container comprising the laminate according to any one of [1] to

[11] above. [Example]

[0239] The laminate of the present disclosure will be described more specifically based on examples, but the laminate of the present disclosure is not limited to these examples.

[0240] In the following description, 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." Anchor coating agents are also referred to as "AC agents." The extruded polyethylene resin layer is also referred to as "EC-PE." Polyurethane adhesives are also referred to as "PU adhesives."

[0241] [Preparation of stretched PE substrate (substrate film)] <Preparation of uniaxially stretched PE film (A)> HDPE (density: 0.961g / cm 3 , melting point: 135°C, MFR: 0.7g / 10min, ExxonMobil, trade name: HTA108) and MDPE (density: 0.941g / cm 3A 125 μm-thick PE film was obtained by coextrusion using an inflation molding method. The HDPE layer, MDPE layer, and HDPE layer were each 25 μm thick, and the MDPE layer was 75 μm thick. This PE film was stretched in the machine direction (MD) at a stretch ratio of 5 times to obtain a 25 μm-thick stretched PE film. One side of this stretched PE film was subjected to a corona treatment to adjust the wetting index to 52 dyn. The substrate thus obtained is also referred to as "uniaxially stretched PE film (A)." The haze value of the uniaxially stretched PE film (A) was measured in accordance with JIS K7136 and was found to be 8.9%.

[0242] [Preparation of sealant film] <Preparation of sealant film (A)> LLDPE (density: 0.916g / cm 3 , melting point: 116°C, MFR: 2.3g / 10min, Prime Polymer Co., Ltd., product name: SP2020) and adhesive resin (density: 0.890g / cm 3 , melting point: 128°C, MFR: 2.6g / 10min, Mitsui Chemicals, Inc., product name: Admer AT1955E) and a gas barrier resin (density: 1.14g / cm 3 A 50 μm thick sealant film was obtained by co-extrusion using an inflation molding method with an LLDPE layer, an adhesive resin layer, and a gas barrier resin layer (melting point: 165°C, MFR: 1.7 g / 10 min, Kraray, trade name: EVALE171B). The LLDPE layer was 40 μm thick, the adhesive resin layer was 5 μm thick, and the gas barrier resin layer was 5 μm thick. The gas barrier resin layer surface of this sealant film was subjected to a corona treatment. The sealant film obtained in this manner is also referred to as "sealant film (A)."

[0243] <Preparation of sealant film (B)> LLDPE (density: 0.916g / cm 3, melting point: 116°C, MFR: 2.3g / 10min, Prime Polymer Co., Ltd., product name: SP2020) and adhesive resin (density: 0.890g / cm 3 , melting point: 128°C, MFR: 2.6g / 10min, Mitsui Chemicals, Inc., product name: Admer AT1955E) and a heat-resistant resin (density: 1.12g / cm 3 The LLDPE layer was 40 μm thick, the adhesive resin layer was 5 μm thick, and the heat-resistant resin layer was 5 μm thick. The heat-resistant resin layer surface of this sealant film was subjected to a corona treatment. The sealant film obtained in this manner is also referred to as "sealant film (B)."

[0244] [Example 1] A uniaxially stretched PE film (A) and a 30 μm-thick unstretched LLDPE film (Mitsui Chemicals Tohcello, Inc., TUX-TCS) were prepared. A 20 nm-thick aluminum vapor-deposited film was formed on the corona-treated surface of the unstretched LLDPE film by PVD to obtain a vapor-deposited sealant film. The corona-treated surface of the uniaxially stretched PE film (A) was flexographically printed using a water-based flexographic ink (Toyo Ink Co., Ltd., product name: Aquariona) to form a 1 μm-thick printed layer. A two-component curing polyurethane adhesive (Mitsui Chemicals, Inc., A-3210 / A-3075) was applied as an anchor coating agent to the printed layer-forming surface to form a 0.3 μm-thick anchor coat layer. In this way, a laminate consisting of the uniaxially stretched PE film (A), the printed layer, and the anchor coat layer was obtained. LDPE (density: 0.918 g / cm) was applied to the anchor coat layer of the laminate. 3 A laminate was obtained by melt-extruding a resin (Novatec LC600A, melting point: 106°C, MFR: 7.0g / 10min, manufactured by Japan Polyethylene Co., Ltd.) to a thickness of 20µm, while sandwich-laminating the laminate and the vapor-deposited sealant film so that the anchor coat layer and the vapor-deposited film faced each other.

[0245] [Example 2] A laminate was obtained in the same manner as in Example 1, except that the sealant film (A) was used instead of the unstretched LLDPE film. The sealant film (A) was arranged so that the LLDPE layer was the outermost layer of the laminate.

[0246] [Example 3] A laminate was obtained in the same manner as in Example 1, except that the sealant film (B) was used instead of the unstretched LLDPE film. The sealant film (B) was arranged so that the LLDPE layer was the outermost layer of the laminate.

[0247] [Comparative Example 1] A uniaxially stretched PE film (A) and a 30 μm-thick unstretched LLDPE film (Mitsui Chemicals Tohcello, Inc., TUX-TCS) were prepared. A 20 nm-thick aluminum vapor-deposited film was formed on the corona-treated surface of the unstretched LLDPE film by PVD to obtain a vapor-deposited sealant film. A 1 μm-thick printed layer was formed on the corona-treated surface of the uniaxially stretched PE film (A) by flexographic printing using a water-based flexographic ink (Toyo Ink Co., Ltd., product name: Aquariona). In this way, a laminate consisting of the uniaxially stretched PE film (A) and the printed layer was obtained. The printed layer-formed surface of the laminate and the vapor-deposited film of the vapor-deposited sealant film were bonded together via a 4 μm-thick adhesive layer made of a two-component curing polyurethane adhesive (Rock Paint Co., Ltd., RU-77T / H-7) to obtain a laminate.

[0248] Comparative Example 2 A laminate was obtained in the same manner as in Comparative Example 1, except that the sealant film (A) was used instead of the unstretched LLDPE film. The sealant film (A) was arranged so that the LLDPE layer was the outermost layer of the laminate.

[0249] Comparative Example 3 A laminate was obtained in the same manner as in Comparative Example 1, except that the sealant film (B) was used instead of the unstretched LLDPE film. The sealant film (B) was arranged so that the LLDPE layer was the outermost layer of the laminate.

[0250] [Seal strength measurement method] Two sheets of each laminate prepared in the examples and comparative examples were used, and the sealant layers of the laminates were bonded together at a temperature of 140°C and a pressure of 1 kgf / cm 2 The sample was heat-sealed for 1 second, forming a seal. The portion containing the seal was then cut out to prepare a test piece measuring 15 mm in width and 100 mm in length for measuring the seal strength. The length of the seal was 15 mm. The seal strength was measured in accordance with JIS K7127:1999 at a test speed of 300 mm / min. The measuring instrument used was an SA-1150 tensile tester manufactured by Orientec Co., Ltd.

[0251] [Method for measuring oxygen permeability and water vapor permeability] The laminate obtained above was cut out to obtain a test piece. The test piece was used to measure the oxygen permeability (cc / m 2 ·day·atm) and water vapor permeability (g / m 2 ·day) was measured by the following method.

[0252] Using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON), the test piece was set so that the stretched PE substrate side was the oxygen supply side, and the oxygen permeability was measured in an environment of 23°C and 65% RH in accordance with JIS K7126-2.

[0253] Using a water vapor permeability measuring device (MOCON, PERMATRAN-w 3 / 33), the test piece was set so that the stretched PE substrate side was the water vapor supply side, and the water vapor permeability was measured in an environment of 40°C and 90% RH in accordance with JIS K7129.

[0254] [Table 1] [Explanation of symbols]

[0255] 1: Laminate 10: Stretched polyethylene base material 20: Extruded resin layer 22: Anchor coat layer 30: Sealant layer 32: Functional resin layer 34: Adhesive resin layer 36: Polyethylene layer 38: Vapor deposition film 40: Standing pouch 41: Body (side sheet) 42: Bottom (bottom sheet) 43: Side gusset

Claims

1. A laminate comprising a stretched polyethylene substrate and a sealant layer, The stretched polyethylene substrate contains polyethylene as a main component, The sealant layer is a polyethylene layer containing polyethylene as a main component; Functional resin layer Equipped with the laminate includes an extruded resin layer containing polyethylene as a main component between the stretched polyethylene substrate and the sealant layer; Laminate.

2. The laminate according to claim 1 , wherein the functional resin layer is a gas barrier resin layer or a heat-resistant resin layer.

3. The laminate according to claim 1 or 2, wherein the sealant layer further comprises an adhesive resin layer between the polyethylene layer and the functional resin layer.

4. The laminate according to any one of claims 1 to 3, further comprising a vapor-deposited film formed on a surface of the sealant layer on the side facing the stretched polyethylene substrate.

5. A laminate comprising a stretched polyethylene substrate and a sealant layer, The stretched polyethylene substrate contains polyethylene as a main component, The sealant layer contains polyethylene as a main component, the laminate comprises a vapor-deposited film formed on a surface of the sealant layer facing the stretched polyethylene substrate, the laminate includes an extruded resin layer containing polyethylene as a main component between the stretched polyethylene substrate and the vapor-deposited film; Laminate.

6. The laminate according to any one of claims 1 to 5, wherein the sealant layer has a thickness of 20 µm or more and 60 µm or less.

7. The laminate according to any one of claims 1 to 6, wherein the stretched polyethylene substrate is a polyethylene substrate that has been subjected to uniaxial or biaxial stretching treatment.

8. The laminate according to any one of claims 1 to 7, further comprising a printed layer on the surface of the stretched polyethylene substrate on the side of the sealant layer.

9. The laminate according to any one of claims 1 to 8, further comprising 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 any one of claims 1 to 9, wherein the content of the polyethylene is 85% by mass or more in 100% by mass of the laminate.

11. The laminate according to any one of claims 1 to 10, which is used for packaging material applications.

12. A packaging material comprising the laminate according to any one of claims 1 to 11.

13. A packaging container comprising the laminate according to any one of claims 1 to 11.

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