Laminate, packaging material, packaging bag and stand pouch

Abstract

To provide a laminate that enables production of a packaging material which has sufficient strength and is excellent in recyclability.SOLUTION: A laminate includes a base material and a heat seal layer, in which the base material and the heat seal layer are composed of the same material, at least one surface of the base material is subjected to electron beam irradiation treatment, the same material is polyethylene, and the base material is provided so that an electron beam irradiation surface of the base material is the outermost surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to laminates, and to packaging materials, packaging bags, and stand-up pouches composed of said laminates. [Background technology]

[0002] Traditionally, resin films made from resin materials have been used as components of packaging materials. For example, resin films made from polyolefins are widely used in packaging materials because they possess moderate flexibility, transparency, and excellent heat-sealing properties.

[0003] Typically, resin films made from polyolefins are inferior in terms of strength and heat resistance, and therefore cannot be used as a base material for packaging materials. Instead, they are used in combination with resin films made from polyester, polyamide, etc. Therefore, typical packaging materials are composed of laminates in which the base material and the heat-seal layer are made of different resin materials (for example, Patent Document 1).

[0004] In recent years, with the growing demand for a circular economy, there is a growing need for high recyclability in packaging materials. However, as mentioned above, conventional packaging materials are composed of different types of resin materials, making it difficult to separate them, and as a result, they are not currently recycled. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2009-202519 [Overview of the project] [Problems that the invention aims to solve]

[0006] The inventors have found that by subjecting a polyolefin film, specifically a polyethylene film, which was conventionally used as a heat seal layer, to stretching and electron beam irradiation, its strength and heat resistance can be significantly improved, and it can be used as a base material for packaging materials and the like. Furthermore, we have found that by laminating the substrate with a heat-seal layer made of polyethylene to form a laminate, it is possible to obtain a laminate that has high strength and heat resistance and can be used to produce recyclable packaging materials.

[0007] This invention has been made in view of the above findings, and the problem it aims to solve is to provide a laminate that enables the production of packaging materials that have sufficient strength and excellent recyclability.

[0008] Furthermore, the problem that the present invention aims to solve is to provide a packaging material, a packaging bag, and a stand-up pouch composed of the laminate. [Means for solving the problem]

[0009] The laminate of the present invention comprises a base material and a heat-seal layer. The base material and the heat seal layer are made of the same material. At least one surface of the substrate is subjected to electron beam irradiation treatment. The same material is polyethylene. The substrate is provided such that the electron beam irradiation surface of the substrate becomes the outermost surface.

[0010] In one embodiment, the thickness of the substrate is 10 μm or more and 50 μm or less.

[0011] In one embodiment, the stretching ratio in the longitudinal and / or transverse direction of the substrate is 2 times or more and 10 times or less.

[0012] In one embodiment, the density of the polyethylene contained in the substrate before electron beam irradiation is 0.935 g / cm³. 3Above 0.957 g / cm 3 It is as follows.

[0013] In one embodiment, the laminate of the present invention further includes an adhesive layer between a base material and a heat-sealing layer. The adhesive layer contains a polyethylene polymer.

[0014] In one embodiment, the adhesive layer is formed using an aqueous dispersion in which the number average particle diameter of the polyethylene polymer is dispersed to be 1 μm or less.

[0015] In one embodiment, the laminate of the present invention is used for packaging materials.

[0016] The packaging material of the present invention is characterized by being composed of the above laminate.

[0017] The packaging bag of the present invention is composed of the above laminate, and is characterized in that the thickness of the heat-sealing layer is 20 μm or more and 60 μm or less.

[0018] The stand-up pouch of the present invention is composed of the above laminate, and is characterized in that the thickness of the heat-sealing layer is 50 μm or more and 200 μm or less.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a laminate that enables the production of a packaging material having sufficient strength and excellent recyclability.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 2] It is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 3] It is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 4]This is a perspective view showing one embodiment of a packaging material made using the laminate of the present invention. [Figure 5] This is a perspective view showing one embodiment of a packaging material made using the laminate of the present invention. [Modes for carrying out the invention]

[0021] (Laminated structure) As shown in Figure 1, the laminate 10 of the present invention comprises a base material 11 and a heat seal layer 12.

[0022] In one embodiment, the laminate 11 of the present invention includes an intermediate layer 13 between the base material 10 and the heat seal layer 12, as shown in Figure 2.

[0023] In one embodiment, the laminate of the present invention may include an adhesive layer 14 between any layers, as shown in Figures 1 and 2.

[0024] The polyethylene content in the entire laminate of the present invention is preferably 90% by mass or more, and more preferably 90% by mass or more. By setting the polyethylene content in the entire laminate of the present invention to 90% by mass or more, the recyclability of the laminate of the present invention can be improved.

[0025] The following describes each layer that constitutes the laminate of the present invention.

[0026] (base material) The base material is a film made of polyethylene, characterized in that it has been stretched and at least one of its surfaces has been subjected to electron beam irradiation. In this way, by stretching a film made of polyethylene and irradiating at least one of its surfaces with an electron beam to improve the crosslinking density of the polyethylene, the heat resistance and strength of the film can be significantly improved, and the physical properties required for an outer layer of packaging material can be satisfied.

[0027] As the polyethylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene can be used. Among these, from the viewpoints of the strength and heat resistance of the base material, high-density polyethylene and medium-density polyethylene are preferred, and from the viewpoint of drawability, medium-density polyethylene is more preferred.

[0028] In the present invention, as the high-density polyethylene, polyethylene having a density of 0.945 g / cm 3 or more can be used, and as the medium-density polyethylene, polyethylene having a density of 0.925 g / cm 3 or more and less than 0.945 g / cm 3 can be used, and as the low-density polyethylene, polyethylene having a density of 0.900 g / cm 3 or more and less than 0.925 g / cm 3 can be used, and as the linear low-density polyethylene, polyethylene having a density of 0.900 g / cm 3 or more and less than 0.925 g / cm 3 can be used, and as the ultra-low-density polyethylene, polyethylene having a density of 0.900 g / cm 3 or less can be used. In the present invention, it is preferable to use polyethylene having a density of 0.935 g / cm 3 or more and 0.950 g / cm 3 or less. By using polyethylene having such a density, the crosslinking reaction can proceed more favorably, and the strength and heat resistance of the base material can be further improved.

[0029] The polyethylene with different densities and branches as described above can be obtained by appropriately selecting a polymerization method. For example, as the polymerization catalyst, a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst is used, and it is preferably carried out in one stage or in multiple stages of two or more stages by any of the methods of gas-phase polymerization, slurry polymerization, solution polymerization, and high-pressure ionic polymerization.

[0030] The single-site catalyst described above is a catalyst capable of forming a uniform active species, and is usually prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activation co-catalyst. Single-site catalysts are preferred over multi-site catalysts because they have a more uniform active site structure, allowing for the polymerization of polymers with high molecular weight and high uniformity. As a single-site catalyst, metallocene catalysts are particularly preferred. A metallocene catalyst is a catalyst comprising a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a co-catalyst, an organometallic compound if necessary, and each catalytic component of a support.

[0031] In the transition metal compounds of Group IV of the periodic table containing the ligand having the cyclopentadienyl skeleton described above, the cyclopentadienyl skeleton is a cyclopentadienyl group, a substituted cyclopentadienyl group, etc. The substituted cyclopentadienyl group has at least one substituent selected from hydrocarbon groups having 1 to 30 carbon atoms, silyl groups, silyl-substituted alkyl groups, silyl-substituted aryl groups, cyano groups, cyanoalkyl groups, cyanoaryl groups, halogen groups, haloalkyl groups, halosilyl groups, etc. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may bond to each other to form a ring, forming an indenyl ring, a fluorenyl ring, an azlenyl ring, or a hydrogenated version thereof. The ring formed by the bonding of substituents may further have substituents on each other.

[0032] In a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, examples of the transition metal include zirconium, titanium, and hafnium, with zirconium and hafnium being particularly preferred. The transition metal compound usually has two ligands having a cyclopentadienyl skeleton, and it is preferable that each ligand having a cyclopentadienyl skeleton is bonded to each other by a bridging group. Examples of bridging groups include alkylene groups having 1 to 4 carbon atoms, silylene groups, substituted silylene groups such as dialkylsilylene groups and diarylsilylene groups, and substituted germylene groups such as dialkylgermylene groups and diarylgermylene groups. A substituted silylene group is preferred. The above transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton can be used as a catalyst component, either individually or as a mixture of two or more.

[0033] Co-catalysts are those that can effectively utilize the transition metal compounds of Group IV of the periodic table as polymerization catalysts, or that can balance the ionic charge of the catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes and benzene-insoluble organoaluminum oxy compounds, ion-exchangeable layered silicates, boron compounds, ionic compounds consisting of cations containing or not containing active hydrogen groups and non-coordinating anions, lanthanide salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing fluoro groups.

[0034] Transition metal compounds of Group IV of the periodic table containing ligands having a cyclopentadienyl skeleton may be used by being supported on an inorganic or organic compound. Preferred supports are porous oxides of inorganic or organic compounds, specifically including ion-exchange layered silicates such as montmorillonite, SiO2, Al2O3, MgO, ZrO2, TiO2, B2O3, CaO, ZnO, BaO, ThO2, or mixtures thereof. Further organometallic compounds that may be used as needed include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these, organoaluminum compounds are preferred.

[0035] Furthermore, copolymers of ethylene and other monomers can be used, as long as they do not impair the properties of the present invention. Examples of ethylene copolymers include copolymers consisting of ethylene and α-olefins having 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms include 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. Also, copolymers with vinyl acetate or acrylic acid esters, etc., are acceptable, as long as they do not impair the objectives of the present invention.

[0036] Furthermore, in this invention, instead of ethylene obtained from fossil fuels, biomass-derived ethylene may be used as a raw material for obtaining the above-mentioned polyethylene. Since such biomass-derived polyethylene is a carbon-neutral material, it can reduce the environmental impact of packaging materials and other products made from laminates comprising this multilayer substrate. Such biomass-derived polyethylene can be manufactured, for example, by a method described in Japanese Patent Application Publication No. 2013-177531. Alternatively, commercially available biomass-derived polyethylene (for example, Green PE, commercially available from Braschem) may be used.

[0037] In addition, recycled polyethylene can be used through mechanical recycling. Mechanical recycling generally involves crushing collected polyethylene film, washing it with alkali to remove dirt and foreign matter from the film surface, and then drying it under high temperature and reduced pressure for a certain period of time to disperse any contaminants remaining inside the film, thereby decontaminating it and removing the dirt from the polyethylene film, returning it to polyethylene once again.

[0038] The base material may contain additives to the extent that they do not impair the properties of the present invention, such as crosslinking agents, antioxidants, antiblocking agents, lubricants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0039] In one embodiment, the substrate has a multilayer structure. In one embodiment, the substrate comprises a layer made of high-density polyethylene (hereinafter referred to as the high-density polyethylene layer), a layer made of medium-density polyethylene (hereinafter referred to as the medium-density polyethylene layer), and a layer made of high-density polyethylene (hereinafter referred to as the high-density polyethylene layer). By adopting this configuration, it is possible to improve the strength and heat resistance of the base material while maintaining its stretchability. In this case, it is preferable that the thickness of the high-density polyethylene layer is thinner 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 is preferably 1 / 10 or more and 1 / 1 or less, and more preferably 1 / 5 or more and 1 / 2 or less. By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1 / 10 or more, the strength and heat resistance of the substrate can be further improved. Furthermore, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1 / 1 or less, the stretchability of the substrate can be further improved.

[0040] In one embodiment, the substrate comprises a high-density polyethylene layer, a medium-density polyethylene layer, a low-density polyethylene layer, a linear low-density polyethylene layer, or an ultra-low-density polyethylene layer (collectively referred to as a low-density polyethylene layer in this paragraph for simplification), a medium-density polyethylene layer, and a high-density polyethylene layer. This configuration improves the stretchability of the substrate, enhances its strength and heat resistance, prevents curling, and improves the production efficiency of the substrate. In this case, it is preferable that the thickness of the high-density polyethylene layer is thinner 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 is preferably 1 / 10 or more and 1 / 1 or less, and more preferably 1 / 5 or more and 1 / 2 or less. By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1 / 10 or more, the strength and heat resistance of the substrate can be improved. Furthermore, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1 / 1 or less, the stretchability of the substrate can be improved. Furthermore, it is preferable that the thickness of the high-density polyethylene layer is the same as or greater than the thickness of the low-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer is preferably 1 / 0.25 or more and 1 / 2 or less, and more preferably 1 / 0.5 or more and 1 / 1 or less. By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer to 1 / 0.25 or more, the heat resistance of the substrate can be improved. Furthermore, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer to 1 / 1 or less, the adhesion between the medium-density polyethylene layers can be improved. In one embodiment, a substrate with such a configuration can be produced, for example, by an inflation method. Specifically, it can be manufactured by co-extruding a high-density polyethylene layer, a medium-density polyethylene layer, and a low-density polyethylene layer, a linear low-density polyethylene layer, or an ultra-low-density polyethylene layer into a tube shape from the outside, and then pressing the opposing low-density polyethylene layers, linear low-density polyethylene layers, or ultra-low-density polyethylene layers together using a rubber roll or the like. By manufacturing in this manner, the number of defective products in production can be significantly reduced, ultimately improving production efficiency. Furthermore, the inflation film-forming machine can also perform stretching, which further improves production efficiency.

[0041] The substrate may be a uniaxially oriented film or a biaxially oriented film. The stretching ratio in the longitudinal direction (MD) of the substrate is preferably 2 times or more and 10 times or less, and preferably 3 times or more and 7 times or less. By increasing the stretching ratio in the longitudinal direction (MD) of the substrate to 2 times or more, the strength and heat resistance of the substrate of the present invention can be improved. Furthermore, the printability of the substrate can be improved. In addition, the transparency of the substrate can be improved. On the other hand, there is no particular upper limit to the stretching ratio in the longitudinal direction (MD) of the substrate, but from the viewpoint of the breaking limit of the substrate, it is preferable to set it to 10 times or less. Furthermore, the stretching ratio in the transverse direction (TD) of the substrate is preferably 2 times or more and 10 times or less, and preferably 3 times or more and 7 times or less. By increasing the stretching ratio in the transverse direction (TD) of the substrate to 2 times or more, the strength and heat resistance of the substrate of the present invention can be improved. Furthermore, the printability of the substrate can be improved. In addition, the transparency of the substrate can be improved. On the other hand, there is no particular upper limit to the stretching ratio in the transverse direction (TD) of the substrate, but from the viewpoint of the breaking limit of the substrate, it is preferable to set it to 10 times or less.

[0042] As shown in Figures 1 and 2, the base material 10 may have polyethylene on one side whose crosslinking density has been improved by electron beam irradiation, or, as shown in Figure 3, the crosslinking density of polyethylene throughout the entire base material may be improved. Furthermore, if the substrate has a multilayer structure, it is sufficient that the crosslinking density of the polyethylene in the outermost layer is improved by electron beam irradiation. From the viewpoint of strength and heat resistance, it is preferable that the overall crosslinking density of polyethylene is improved by electron beam irradiation.

[0043] Conventional and known devices can be used for electron beam irradiation of substrates. For example, curtain-type electron beam irradiation devices (LB1023, manufactured by I-Electron Beam Co., Ltd.), line-type low-energy electron beam irradiation devices (EB-ENGINE, manufactured by Hamamatsu Photonics K.K.), and drum-roll type electron beam irradiation devices (EZ-CURE, manufactured by I-Electron Beam Co., Ltd.) can be suitably used.

[0044] The dose of the electron beam irradiated onto the substrate is preferably in the range of 10 kGy to 2000 kGy, and more preferably in the range of 20 kGy to 1000 kGy. Furthermore, the acceleration voltage of the electron beam is preferably in the range of 30kV to 300kV, more preferably in the range of 50kV to 300kV, and even more preferably in the range of 50kV to 250kV. Furthermore, the electron beam irradiation energy is preferably in the range of 20 keV to 750 keV, more preferably in the range of 25 keV to 500 keV, even more preferably in the range of 30 keV to 400 keV, and particularly preferably in the range of 20 keV to 200 keV.

[0045] The oxygen concentration inside the electron beam irradiation apparatus is preferably 500 ppm or less, and more preferably 100 ppm or less. By performing electron beam irradiation under these conditions, the generation of ozone can be suppressed, and the deactivation of radicals generated by electron beam irradiation by oxygen in the atmosphere can be suppressed. Such conditions can be achieved, for example, by creating an inert gas atmosphere (nitrogen, argon, etc.) inside the apparatus.

[0046] In one embodiment, electron beam irradiation can be performed simultaneously with cooling using a cooling drum or the like.

[0047] Furthermore, the substrate may be surface-treated. This improves the adhesion between adjacent layers when forming the laminate described below. The surface treatment method is not particularly limited and includes physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals. Alternatively, an anchor coat layer may be formed on the substrate surface using a conventionally known anchor coat agent.

[0048] The substrate may have an image formed on its surface, and the image formed is not particularly limited and may represent letters, patterns, symbols, or combinations thereof. Image formation on the substrate is preferably carried out using biomass-derived ink, which makes it possible to produce packaging materials and the like with less environmental impact using the substrate. The method of image formation is not particularly limited and can include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of environmental impact.

[0049] In one embodiment, the substrate may have a vapor-deposited film on its surface, specifically on the side where the heat-seal layer is laminated. This improves the gas barrier properties of the substrate, specifically its oxygen barrier properties and water vapor barrier properties.

[0050] Examples of vapor-deposited films include those composed of metals such as aluminum, as well as inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide.

[0051] Furthermore, the thickness of the deposited film is preferably 1 nm to 150 nm, more preferably 5 nm to 60 nm, and even more preferably 10 nm to 40 nm. By making the thickness of the vapor-deposited film 1 nm or more, the oxygen barrier and water vapor barrier properties of the substrate can be further improved. Furthermore, by making the thickness of the vapor-deposited film 150 nm or less, the occurrence of cracks in the vapor-deposited film can be prevented. Additionally, when the substrate is applied to the laminate described below, its recyclability can be maintained.

[0052] In one embodiment, the substrate is provided with a barrier coating layer, which improves the oxygen barrier properties and water vapor barrier properties of the substrate. If the substrate includes a vapor-deposited film, the barrier coat layer may be provided on or beneath the vapor-deposited film.

[0053] In one embodiment, the barrier coat layer includes ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyacrylonitrile, polyamides such as nylon 6, nylon 6,6 and polymethaxylylene adipamide (MXD6), polyester, polyurethane, and gas barrier resins such as (meth)acrylic resin. Among these, polyvinyl alcohol is preferred from the viewpoint of oxygen barrier properties and water vapor barrier properties. Furthermore, when the vapor-deposited film is composed of an inorganic oxide, the occurrence of cracks in the vapor-deposited film can be effectively prevented by incorporating polyvinyl alcohol into the barrier coat layer.

[0054] The gas barrier resin content in the barrier coat layer is preferably 50% by mass or more and 95% by mass or less, and more preferably 75% by mass or more and 90% by mass or less. By setting the gas barrier resin content in the barrier coat layer to 50% by mass or more, the oxygen barrier and water vapor barrier properties of the substrate can be further improved.

[0055] The barrier coating layer may contain the above-mentioned additives to the extent that they do not impair the properties of the present invention.

[0056] The thickness of the barrier coat layer is preferably 0.01 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less. By setting the barrier coat layer thickness to 0.01 μm or more, the oxygen barrier and water vapor barrier properties of the substrate can be further improved. By setting the barrier coat layer thickness to 10 μm or less, the recyclability of the substrate can be maintained when applied to the laminate described below.

[0057] A barrier coating layer can be formed by dissolving or dispersing the above-mentioned material in water or a suitable solvent, applying it, and drying it. Alternatively, a barrier coating layer can also be formed by applying and drying a commercially available barrier coating agent.

[0058] In another embodiment, the barrier coating layer is a gas barrier coating film containing at least one resin composition, such as a hydrolyzed metal alkoxide or a hydrolyzed condensate of a metal alkoxide, obtained by polycondensation of a mixture of a metal alkoxide and a water-soluble polymer by a sol-gel method in the presence of a sol-gel catalyst, water, and an organic solvent. When the substrate comprises a vapor-deposited film made of an inorganic oxide, the occurrence of cracks in the vapor-deposited film can be effectively prevented by providing a barrier coating layer of this form adjacent to the vapor-deposited film.

[0059] In one embodiment, the metal alkoxide is represented by the following general formula. R 1 n M(OR 2 ) m (However, in the formula, R 1 , R 2 (Each represents an organic group with 1 to 8 carbon atoms, M represents a metal atom, n represents a non-negative integer, m represents a non-negative integer, and n+m represents the valence of M.)

[0060] Examples of metal atoms M that can be used include silicon, zirconium, titanium, and aluminum. Also, R 1 and R 2 Examples of organic groups represented by include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, and i-butyl groups.

[0061] Examples of metal alkoxides that satisfy the above general formula include tetramethoxysilane (Si(OCH3)4), tetraethoxysilane (mass%) Si(OC2H5)4), tetrapropoxysilane (Si(OC3H7)4), and tetrabutoxysilane (Si(OC4H9)4).

[0062] Furthermore, it is preferable to use a silane coupling agent together with the above-mentioned metal alkoxide. As silane coupling agents, known organic reactive group-containing organoalkoxysilanes can be used, but organoalkoxysilanes having an epoxy group are particularly preferred. Examples of organoalkoxysilanes having an epoxy group include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0063] Two or more silane coupling agents may be used as described above, and it is preferable to use the silane coupling agent in an amount of about 1 to 20 parts by mass per 100 parts by mass of the total amount of the alkoxides.

[0064] As water-soluble polymers, polyvinyl alcohol and ethylene-vinyl alcohol copolymers are preferred, and from the viewpoint of oxygen barrier properties, water vapor barrier properties, water resistance and weather resistance, it is preferable to use these in combination.

[0065] The content of the water-soluble polymer in the gas barrier coating film is preferably 5 parts by mass or more and 500 parts by mass or less per 100 parts by mass of metal alkoxide. By setting the content of the water-soluble polymer in the gas barrier coating film to 5 parts by mass or more per 100 parts by mass of metal alkoxide, the oxygen barrier and water vapor barrier properties of the substrate can be further improved. Furthermore, by setting the content of the water-soluble polymer in the gas barrier coating film to 500 parts by mass or less per 100 parts by mass of metal alkoxide, the film-forming properties of the gas barrier coating film can be improved.

[0066] The thickness of the gas barrier coating film is preferably 0.01 μm to 100 μm, and more preferably 0.1 μm to 50 μm. This allows for improved oxygen barrier and water vapor barrier properties while maintaining recyclability. By setting the thickness of the gas barrier coating film to 0.01 μm or more, the oxygen barrier and water vapor barrier properties of the substrate can be improved. Furthermore, when applied adjacent to a vapor-deposited film composed of inorganic oxides, it is possible to prevent the occurrence of cracks in the vapor-deposited film.

[0067] A gas barrier coating film can be formed by applying a composition containing the above-mentioned materials using conventionally known methods such as roll coating (including gravure roll coaters), spray coating, spin coating, dipping, brushing, barcode application, or applicator application, and then polycondensing the composition by a sol-gel method. Suitable catalysts for the sol-gel process include acids or amine compounds. Suitable amine compounds include tertiary amines that are substantially insoluble in water and soluble in organic solvents, such as N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. Among these, N,N-dimethylbenzylamine is preferred. The sol-gel catalyst is preferably used in an amount of 0.01 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of metal alkoxide, and more preferably in an amount of 0.03 parts by mass or more and 0.3 parts by mass or less. The catalytic effect of the sol-gel method catalyst can be improved by using 0.01 parts by mass or more per 100 parts by mass of metal alkoxide. Furthermore, by using 1.0 part by mass or less per 100 parts by mass of metal alkoxide, the thickness of the formed gas barrier coating film can be made uniform.

[0068] The above composition may further contain an acid. The acid is used as a catalyst for the sol-gel process, mainly as a catalyst for the hydrolysis of alkoxides and silane coupling agents. As acids, mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid, as well as organic acids such as acetic acid and tartaric acid, can be used. The amount of acid used is preferably 0.001 moles or more and 0.05 moles or less relative to the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent. By using an amount of acid equal to 0.001 moles or more relative to the total molar amount of the alkoxide component (e.g., silicate portion) of the alkoxide and silane coupling agent, the catalytic effect can be improved. Furthermore, by using an amount of acid equal to 0.05 moles or less relative to the total molar amount of the alkoxide component (e.g., silicate portion) of the alkoxide and silane coupling agent, the thickness of the formed gas barrier coating film can be made uniform.

[0069] Furthermore, the above composition preferably contains water in an amount of 0.1 moles to 100 moles, more preferably 0.8 moles to 2 moles, per mole of the total molar amount of alkoxide. By setting the water content to 0.1 moles or more per mole of total alkoxide, the oxygen barrier and water vapor barrier properties of the laminate of the present invention can be improved. Furthermore, by setting the water content to 100 moles or more per mole of total alkoxide, the hydrolysis reaction can be carried out rapidly.

[0070] Furthermore, the above composition may contain an organic solvent. Examples of organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butanol.

[0071] The following describes one embodiment of a method for forming a gas barrier coating film. First, a 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 proceeds within this composition. Next, the composition is applied to the polyolefin resin layer and dried using the conventionally known method described above. This drying further promotes the polycondensation reaction between the alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains one), forming a composite polymer layer. Finally, a gas barrier coating film can be formed by heating the composition at a temperature of 20 to 250°C, preferably 50 to 220°C, for 1 second to 10 minutes.

[0072] The barrier coat layer may have an image formed on its surface. The method for forming the image is as described above.

[0073] The thickness of the substrate is preferably 10 μm or more and 50 μm or less, and more preferably 12 μm or more and 30 μm or less. By making the substrate thickness 10 μm or more, the required strength for a substrate such as packaging material can be fully satisfied. Furthermore, by making the substrate thickness 50 μm or less, the processability of the substrate can be improved.

[0074] The substrate can be produced by forming a resin film from a resin composition containing at least polyethylene using a T-die method or inflation method, and then stretching and irradiating it with an electron beam. By forming the film using the inflation method, the stretching of the resin film can be performed simultaneously. While stretching and electron beam irradiation of the resin film can be performed in either order, stretching is preferable for reasons of suitability for stretching.

[0075] When preparing a substrate using the T-die method, the MFR of the resin composition is preferably 3 g / 10 min or more and 20 g / 10 min or less. By setting the MFR of the resin composition to 3g / 10min or more, the processability of the substrate can be improved. Furthermore, by setting the MFR of the resin composition to 20g / 10min or less, it is possible to prevent the substrate from fracturing.

[0076] When preparing a substrate by the inflation method, the MFR of the resin composition is preferably 0.5 g / 10 min or more and 5 g / 10 min or less. By setting the MFR of the resin composition to 0.5 g / 10 min or higher, the processability of the substrate can be improved. Furthermore, by setting the MFR of the resin composition to 5 g / 10 min or lower, the film-forming properties can be improved.

[0077] The formation of a deposited film on a substrate can be carried out using conventionally known methods, such as physical vapor deposition (PVD) methods including vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods including plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition.

[0078] Furthermore, for example, a composite film consisting of two or more layers of deposited inorganic oxides can be formed and used by combining both physical vapor deposition and chemical vapor deposition methods. The vacuum level of the deposition chamber before oxygen introduction is 10 -2 ~10 -8 A bar of approximately mbar is preferred, and after oxygen introduction, 10 -1 ~10 -6A pressure of approximately mbar is preferred. The amount of oxygen introduced will vary depending on the size of the deposition machine. Inert gases such as argon, helium, or nitrogen may be used as carrier gases for the oxygen introduced, within reasonable limits. The film transport speed can be approximately 10 to 800 m / min.

[0079] The surface of the vapor-deposited film is preferably subjected to the above-mentioned surface treatment. This improves adhesion with adjacent layers when applied to the laminate described below.

[0080] (Heat seal layer) The heat-seal layer is characterized by being made of polyethylene. Because the laminate of the present invention is composed of a base material and a heat-seal layer made of polyethylene, the recyclability of packaging materials and the like made using the laminate can be improved. However, the heat-seal layer is formed from an unstretched polyolefin resin film or from a polyolefin by melt extrusion.

[0081] From the standpoint of heat sealability, it is preferable to use low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene as the polyethylene material. Furthermore, the above-mentioned biomass-derived polyethylene and mechanically recycled polyethylene can also be used.

[0082] In one embodiment, the heat seal layer has a multilayer structure and includes an intermediate layer comprising at least one of medium-density polyethylene and high-density polyethylene. Specifically, the structure can consist of a layer containing at least one of low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene; a layer containing at least one of medium-density polyethylene and high-density polyethylene; and a layer containing at least one of low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene. By adopting the above configuration, it is possible to further improve the suitability for bag making and strength of the laminate of the present invention while maintaining heat sealability.

[0083] The thickness of the heat-seal layer is preferably adjusted as appropriate according to the weight of the contents to be filled into the packaging material made from the laminate of the present invention. For example, when preparing a packaging bag like the one shown in Figure 4, which is filled with contents of 1g or more and 200g or less, the thickness of the heat seal layer is preferably 20μm or more and 60μm or less. By making the heat seal layer 20 μm or thicker, it is possible to prevent the filled contents from leaking due to damage to the heat seal layer. Furthermore, by making the heat seal layer 60 μm or less, the processability of the laminate of the present invention can be improved.

[0084] Furthermore, when manufacturing a stand pouch as shown in Figure 5, for example, which is filled with contents of 50g or more and 2000g or less, the thickness of the heat seal layer is preferably 50μm or more and 200μm or less. By making the heat seal layer 50 μm or thicker, it is possible to prevent the filled contents from leaking due to damage to the heat seal layer. Furthermore, by making the heat seal layer 200 μm or less thick, the processability of the laminate of the present invention can be improved. Note that the shaded areas in Figures 4 and 5 represent the heat-sealed sections.

[0085] The heat seal layer may have a vapor-deposited film on its substrate-side surface. The presence of a vapor-deposited film can improve oxygen barrier properties and water vapor barrier properties.

[0086] Examples of vapor-deposited films include those composed of metals such as aluminum, as well as inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide.

[0087] Furthermore, the thickness of the deposited film is preferably 1 nm to 150 nm, more preferably 5 nm to 60 nm, and even more preferably 10 nm to 40 nm.

[0088] The method for forming the vapor-deposited film is as described above.

[0089] It is preferable that the surface of the deposited film is subjected to the above-mentioned surface treatment. This improves adhesion with adjacent layers.

[0090] (Middle class) In one embodiment, the intermediate layer comprises a stretched polyethylene film, which further improves the strength of the laminate of the present invention. The stretched polyethylene film is composed of polyethylene, and high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene can be used. Additionally, biomass-derived polyethylene and mechanically recycled polyethylene can be used.

[0091] Furthermore, the stretched polyethylene film may have the above-described multilayer structure.

[0092] The stretched polyethylene film may be either uniaxially oriented or biaxially oriented, and the preferred stretching ratio is as described above.

[0093] The thickness of the stretched polyethylene film is preferably 10 μm or more and 50 μm or less, and more preferably 12 μm or more and 30 μm or less. By making the thickness of the stretched polyethylene film 10 μm or more, the strength and heat resistance of the laminate of the present invention can be improved. Furthermore, by making the thickness of the stretched polyethylene film 50 μm or less, the processability of the laminate can be improved.

[0094] In one embodiment, the intermediate layer comprises a gas barrier layer made of a gas barrier resin. By including such an intermediate layer in the laminate of the present invention, the oxygen barrier properties and water vapor barrier properties can be improved. Examples of gas barrier resins include ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyacrylonitrile, polyamides such as nylon 6, nylon 6,6 and polymethaxylylene adipamide (MXD6), polyesters, polyurethanes, and (meth)acrylic resins.

[0095] The thickness of the gas barrier layer is preferably 0.01 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less. By setting the thickness of the gas barrier layer to 0.01 μm or more, the oxygen barrier and water vapor barrier properties of the laminate of the present invention can be further improved. By setting the thickness of the gas barrier layer to 10 μm or less, the recyclability of the laminate of the present invention can be maintained.

[0096] In one embodiment, the intermediate layer comprises a vapor-deposited film. The types of vapor-deposited films that can be used, preferred thickness, and formation method are as described above.

[0097] In one embodiment, the intermediate layer comprises a barrier coat layer. The configuration, preferred thickness, and formation method of the barrier coat layer are as described above.

[0098] (adhesive layer) The laminate of the present invention may include an adhesive layer between any of the layers. This improves the adhesion between the layers.

[0099] The adhesive layer may be formed using a conventionally known adhesive. This adhesive may be a one-component curing type, a two-component curing type, or a non-curing type. Furthermore, the adhesive may be either a solvent-free adhesive or a solvent-based adhesive, but from the standpoint of environmental impact, a solvent-free adhesive is preferable. Examples of solvent-free adhesives include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, and urethane-based adhesives. Among these, two-component curing type urethane-based adhesives are preferably used. Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and olefin-based adhesives.

[0100] Furthermore, if the adhesive layer is provided adjacent to the aluminum vapor-deposited film, it is preferable that the adhesive layer be composed of a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphate-modified compound. When forming a laminate with a vapor-deposited film into a packaging material, bending loads are applied to the laminate by the molding machine, etc., which may cause cracks in the aluminum vapor-deposited film. By using the above-described configuration for the adhesive layer, even if cracks occur in the aluminum vapor-deposited film, the decrease in oxygen barrier properties and water vapor barrier properties can be suppressed (bending load resistance).

[0101] Polyester polyols have two or more hydroxyl groups as functional groups in one molecule. Isocyanate compounds, on the other hand, have two or more isocyanate groups as functional groups in one molecule. Polyester polyols have, for example, a polyester structure or a polyester polyurethane structure as their main backbone.

[0102] A specific example of a resin composition (adhesive) containing polyester polyol, isocyanate compound, and phosphate-modified compound is the PASLIM series sold by DIC Corporation.

[0103] The resin composition may further contain plate-like inorganic compounds, coupling agents, cyclodextrins and / or their derivatives.

[0104] Examples of polyester polyols having two or more hydroxyl groups in one molecule as functional groups include the following [Example 1] to [Example 3]. [Example 1] Polyester polyol obtained by polycondensation of an ortho-oriented polycarboxylic acid or its anhydride with a polyhydric alcohol [Example 2] Polyester polyol having a glycerol skeleton [Example 3] Polyester polyol having an isocyanuric ring The following describes each type of polyester polyol.

[0105] The polyester polyol of the first example is a polycondensate obtained by polycondensing a polycarboxylic acid component containing at least one orthophthalic acid and its anhydride with a polyhydric alcohol component containing at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol. In particular, polyester polyols in which orthophthalic acid and its anhydride are present in a proportion of 70 to 100% by mass relative to the total polycarboxylic acid components are preferred.

[0106] The polyester polyol according to the first example requires orthophthalic acid and its anhydride as polycarboxylic acid components, but other polycarboxylic acid components may be copolymerized to the extent that the effects of this embodiment are not impaired. Specifically, examples include aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; unsaturated bond-containing polycarboxylic acids such as maleic anhydride, maleic acid, and fumaric acid; alicyclic polycarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, anhydrides of these dicarboxylic acids, and ester-forming derivatives of these dicarboxylic acids; and polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids. Among these, succinic acid, 1,3-cyclopentanedicarboxylic acid, and isophthalic acid are preferred. Furthermore, two or more of the above-mentioned polycarboxylic acids may be used.

[0107] As an example of a polyester polyol related to the second example, a polyester polyol having a glycerol skeleton represented by general formula (1) can be mentioned. [ka] In general formula (1), R1, R2, and R3 are each independently either H (hydrogen atom) or a group represented by the following general formula (2). [ka]

[0108] In formula (2), n represents an integer from 1 to 5, X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have substituents, and Y represents an alkylene group having 2 to 6 carbon atoms. However, at least one of R1, R2, and R3 represents a group represented by general formula (2).

[0109] In general formula (1), at least one of R1, R2, and R3 must be a group represented by general formula (2). In particular, it is preferable that all of R1, R2, and R3 are groups represented by general formula (2).

[0110] Furthermore, the compound may be a mixture of two or more compounds in which one of R1, R2, or R3 is a group represented by general formula (2), two of R1, R2, or R3 are groups represented by general formula (2), or all of R1, R2, and R3 are groups represented by general formula (2).

[0111] X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have substituents. If X is substituted by a substituent, it may be substituted by one or more substituents, the substituents being bonded to any carbon atom on X that is different from the free radical. Examples of substituents include chloro, bromo, methyl, ethyl, i-propyl, hydroxyl, methoxy, ethoxy, phenoxy, methylthio, phenylthio, cyano, nitro, amino, phthalimide, carboxyl, carbamoyl, N-ethylcarbamoyl, phenyl, and naphthyl groups.

[0112] In general formula (2), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, propylene group, butylene group, neopentylene group, 1,5-pentylene group, 3-methyl-1,5-pentylene group, 1,6-hexylene group, methylpentylene group, and dimethylbutylene group. Among these, propylene and ethylene groups are preferred, with ethylene being the most preferred.

[0113] Polyester resin compounds having a glycerol skeleton represented by general formula (1) can be synthesized by reacting glycerol with an aromatic polycarboxylic acid or its anhydride in which the carboxylic acid is substituted in the ortho position, and a polyhydric alcohol component as essential components.

[0114] Examples of aromatic polycarboxylic acids or their anhydrides in which the carboxylic acid is substituted at the ortho position include orthophthalic acid or its anhydride, naphthalene 2,3-dicarboxylic acid or its anhydride, naphthalene 1,2-dicarboxylic acid or its anhydride, anthraquinone 2,3-dicarboxylic acid or its anhydride, and 2,3-anthracenecarboxylic acid or its anhydride. These compounds may have substituents on any carbon atom of the aromatic ring. Examples of substituents include chloro, bromo, methyl, ethyl, i-propyl, hydroxyl, methoxy, ethoxy, phenoxy, methylthio, phenylthio, cyano, nitro, amino, phthalimide, carboxyl, carbamoyl, N-ethylcarbamoyl, phenyl, and naphthyl groups.

[0115] Furthermore, examples of polyhydric alcohol components include alkylenediols having 2 to 6 carbon atoms. Examples of diols include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol.

[0116] The polyester polyol in the third example is a polyester polyol having an isocyanuric ring represented by the following general formula (3). [ka] In general formula (3), R1, R2, and R3 each independently represent either "-(CH2)n1-OH (where n1 is an integer from 2 to 4)" or the structure of general formula (4). [ka]

[0117] In general formula (4), n2 represents an integer from 2 to 4, n3 represents an integer from 1 to 5, X represents an arylene group selected from the group consisting of 1,2-phenylene, 1,2-naphthylene, 2,3-naphthylene, 2,3-anthraquinonediyl, and 2,3-anthracenediyl groups, which may have substituents, and Y represents an alkylene group having 2 to 6 carbon atoms. However, at least one of R1, R2, and R3 is a group represented by general formula (4).

[0118] In general formula (3), the alkylene group represented by -(CH2)n1- may be linear or branched. n1 is preferably 2 or 3, with 2 being the most preferred.

[0119] In general formula (4), n² represents an integer between 2 and 4, and n³ represents an integer between 1 and 5. X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have substituents.

[0120] If X is substituted by a substituent, it may be substituted by one or more substituents, the substituents being bonded to any carbon atom on X that is different from the free radical. Examples of substituents include chloro, bromo, methyl, ethyl, i-propyl, hydroxyl, methoxy, ethoxy, phenoxy, methylthio, phenylthio, cyano, nitro, amino, phthalimide, carboxyl, carbamoyl, N-ethylcarbamoyl, phenyl, and naphthyl groups. The substituents of X are preferably hydroxyl, cyano, nitro, amino, phthalimide, carbamoyl, N-ethylcarbamoyl, and phenyl groups, with hydroxyl, phenoxy, cyano, nitro, phthalimide, and phenyl groups being the most preferred.

[0121] In general formula (4), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, propylene group, butylene group, neopentylene group, 1,5-pentylene group, 3-methyl-1,5-pentylene group, 1,6-hexylene group, methylpentylene group, and dimethylbutylene group. Among these, propylene and ethylene groups are preferred, with ethylene being the most preferred.

[0122] In general formula (3), at least one of R1, R2, and R3 is a group represented by general formula (4). In particular, it is preferable that all of R1, R2, and R3 are groups represented by general formula (4).

[0123] Furthermore, the compound may be a mixture of two or more compounds in which one of R1, R2, or R3 is a group represented by general formula (4), two of R1, R2, or R3 are groups represented by general formula (4), or all of R1, R2, and R3 are groups represented by general formula (4).

[0124] Polyester polyols having an isocyanuric ring, represented by general formula (3), can be synthesized by reacting a triol having an isocyanuric ring with an aromatic polycarboxylic acid or its anhydride in which the carboxylic acid is substituted in the ortho position, and a polyhydric alcohol component as essential components.

[0125] Examples of triols having an isocyanuric ring include alkylene oxide adducts of isocyanuric acids such as 1,3,5-tris(2-hydroxyethyl)isocyanuric acid and 1,3,5-tris(2-hydroxypropyl)isocyanuric acid.

[0126] Furthermore, examples of aromatic polycarboxylic acids or their anhydrides in which the carboxylic acid is substituted at the ortho position include orthophthalic acid or its anhydride, naphthalene 2,3-dicarboxylic acid or its anhydride, naphthalene 1,2-dicarboxylic acid or its anhydride, anthraquinone 2,3-dicarboxylic acid or its anhydride, and 2,3-anthracenecarboxylic acid or its anhydride. These compounds may have substituents on any carbon atom of the aromatic ring.

[0127] Examples of substituents include chloro group, bromo group, methyl group, ethyl group, i-propyl group, hydroxyl group, methoxy group, ethoxy group, phenoxy group, methylthio group, phenylthio group, cyano group, nitro group, amino group, phthalimide group, carboxyl group, carbamoyl group, N-ethylcarbamoyl group, phenyl group, and naphthyl group.

[0128] Furthermore, examples of polyhydric alcohol components include alkylenediols having 2 to 6 carbon atoms. Examples include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol. In particular, polyester polyol compounds having an isocyanuric ring are preferred when 1,3,5-tris(2-hydroxyethyl)isocyanuric acid or 1,3,5-tris(2-hydroxypropyl)isocyanuric acid is used as the triol compound having an isocyanuric ring, an aromatic polycarboxylic acid in which the carboxylic acid is substituted at the ortho position or orthophthalic anhydride is used as the anhydride, and ethylene glycol is used as the polyhydric alcohol, as these compounds exhibit particularly excellent oxygen barrier properties and adhesion.

[0129] The isocyanuric ring is highly polar and trifunctional, which can increase the overall polarity of the system and increase the crosslinking density. From this viewpoint, it is preferable to contain 5% by mass or more of the isocyanuric ring relative to the total solid content of the adhesive resin.

[0130] Isocyanate compounds have two or more isocyanate groups in their molecule. Furthermore, the isocyanate compound may be aromatic or aliphatic, and may be a low-molecular-weight compound or a high-molecular-weight compound. Furthermore, the isocyanate compound may be a blocked isocyanate compound obtained by an addition reaction using a known isocyanate blocking agent by a known and conventional method. In particular, polyisocyanate compounds having three or more isocyanate groups are preferred from the viewpoint of adhesion and retort resistance, and aromatic compounds are preferred from the viewpoint of oxygen barrier properties and water vapor barrier properties.

[0131] Specific examples of isocyanate compounds include, for example, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, metaxylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds, as well as adducts, burettes, and allophanates obtained by reacting these isocyanate compounds with low molecular weight active hydrogen compounds or their alkylene oxide adducts, or high molecular weight active hydrogen compounds. Examples of low molecular weight active hydrogen compounds include ethylene glycol, propylene glycol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, and metaxylylenediamine. Examples of molecular weight active hydrogen compounds include high molecular weight active hydrogen compounds of various polyester resins, polyether polyols, and polyamides.

[0132] Phosphate-modified compounds are, for example, compounds represented by the following general formulas (5) or (6). [ka] In general formula (5), R1, R2, and R3 are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, an optionally substituted phenyl group, and an alkyl group having 1 to 4 carbon atoms, but at least one of them is a hydrogen atom, and n represents an integer from 1 to 4. [ka] In the formula, R4 and R5 are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, an optionally substituted phenyl group, and an alkyl group having 1 to 4 carbon atoms with a (meth)acryloyloxy group, where n is an integer from 1 to 4, x is an integer from 0 to 30, and y is an integer from 0 to 30, except when both x and y are 0.

[0133] More specifically, examples include phosphoric acid, pyrophosphate, triphosphate, methyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, dibutyl phosphate, 2-ethylhexyl acid phosphate, bis(2-ethylhexyl) phosphate, isododecyl acid phosphate, butoxyethyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, and polyoxyethylene alkyl ether phosphate, and one or more of these can be used.

[0134] The content of the phosphate-modified compound in the resin composition is preferably 0.005% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 1% by mass or less. By setting the content of the phosphate-modified compound to 0.005% by mass or more, the oxygen barrier and water vapor barrier properties of the laminate of the present invention can be improved. Furthermore, by setting the content of the phosphate-modified compound to 10% by mass or less, the adhesion of the adhesive layer can be improved.

[0135] The resin composition containing polyester polyol, isocyanate compound, and phosphate-modified compound may also contain plate-like inorganic compound, which can improve the adhesion of the adhesive layer. Furthermore, it can improve the bending load resistance of the laminate of the present invention. Examples of plate-like inorganic compounds include kaolinite-serpentine clay minerals (haloysite, kaolinite, endelite, dickite, nacrite, antigorite, chrysotile, etc.) and pyrophyllite-talc group minerals (pyrophyllite, talc, kerolite, etc.).

[0136] Examples of coupling agents include silane-based coupling agents, titanium-based coupling agents, and aluminum-based coupling agents represented by the general formula (7) below. These coupling agents may be used individually or in combination of two or more types. [ka]

[0137] Examples of silane coupling agents include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxytrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β( Examples include aminoethyl)γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethylbutylidene).

[0138] Examples of titanium-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraoctyl bis(didodecyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyl trioctainol titanate, isopropyl dimethacrylate isostearoyl titanate, isopropyl isostearoyl diacrylic titanate, diisostearoylethylene titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumylphenyl titanate, and dicumylphenyl oxyacetate titanate.

[0139] Specific examples of aluminum-based coupling agents include, for example, acetalkoxyaluminum diisopropylate, diisopropoxyaluminum ethyl acetacetate, diisopropoxyaluminum monomethacrylate, isopropoxyaluminum alkyl acetacetate mono(dioctyl phosphate), aluminum-2-ethylhexanoate oxide trimer, aluminum stearate oxide trimer, and alkyl acetacetate aluminum oxide trimer.

[0140] The resin composition may contain cyclodextrin and / or its derivatives, thereby improving the adhesion of the adhesive layer. Furthermore, the bending load resistance of the laminate of the present invention can be further improved. Specifically, for example, cyclodextrins such as alkylated cyclodextrins, acetylated cyclodextrins, and hydroxyalkylated cyclodextrins, in which the hydrogen atom of the hydroxyl group of the glucose unit of a cyclodextrin is substituted with another functional group, can be used. Branched cyclic dextrins can also be used. Furthermore, the cyclodextrin skeleton in cyclodextrins and cyclodextrin derivatives may be any of the following: α-cyclodextrin consisting of 6 glucose units, β-cyclodextrin consisting of 7 glucose units, or γ-cyclodextrin consisting of 8 glucose units. These compounds may be used individually or in combination of two or more. Furthermore, these cyclodextrins and / or their derivatives may collectively be referred to as dextrin compounds from now on.

[0141] From the viewpoint of compatibility and dispersibility with resin compositions, it is preferable to use cyclodextrin derivatives as the cyclodextrin compound.

[0142] Examples of alkylated cyclodextrins include methyl-α-cyclodextrin, methyl-β-cyclodextrin, and methyl-γ-cyclodextrin. These compounds may be used individually or in combination of two or more.

[0143] Examples of acetylated cyclodextrins include monoacetyl-α-cyclodextrin, monoacetyl-β-cyclodextrin, and monoacetyl-γ-cyclodextrin. These compounds may be used individually or in combination of two or more.

[0144] Examples of hydroxyalkylated cyclodextrins include hydroxypropyl-α-cyclodextrin, hydroxypropyl-β-cyclodextrin, and hydroxypropyl-γ-cyclodextrin. These compounds may be used individually or in combination of two or more.

[0145] The thickness of the adhesive layer is preferably 0.5 μm or more and 6 μm or less, more preferably 0.8 μm or more and 5 μm or less, and even more preferably 1 μm or more and 4.5 μm or less. By making the adhesive layer thickness 0.5 μm or more, the adhesion of the adhesive layer can be improved. Furthermore, if the adhesive layer is composed of a cured product of a resin composition containing polyester polyol, isocyanate compound, and phosphate-modified compound, the bending load resistance of the laminate can be improved. By reducing the thickness of the adhesive layer to 6 μm or less, the processability of the laminate can be improved.

[0146] The adhesive layer can be formed by applying and drying it on a substrate or the like using conventionally known methods such as the direct gravure roll coating method, gravure roll coating method, kiss coating method, reverse roll coating method, fontein method, and transfer roll coating method.

[0147] The laminate of the present invention can be used particularly suitably for the following packaging material applications.

[0148] (packaging material) The packaging material of the present invention is characterized by being composed of the above-mentioned laminate. The shape of the packaging material is not particularly limited, and it may be in the shape of a bag, as shown in Figure 4. In the diagram, the shaded areas represent the heat-sealed portions.

[0149] In one embodiment, a bag-shaped packaging material can be manufactured by folding the laminate of the present invention in half and overlapping the two layers so that the heat-seal layer faces inward, and then heat-sealing the edges. In another embodiment, the bag-shaped packaging material can also be manufactured by overlapping two laminates so that their heat-seal layers face each other, and then heat-sealing the edges.

[0150] The heat sealing method is not particularly limited and can be carried out by known methods such as bar seals, rotary roll seals, belt seals, impulse seals, high-frequency seals, and ultrasonic seals.

[0151] In one embodiment, the packaging material has a stand-up pouch shape with a body and a bottom, as shown in Figure 5.

[0152] The stand-up pouch packaging material can be manufactured by first forming the body of the laminated material by heat-sealing it in a cylindrical shape with the heat-seal layer facing inward, and then folding another laminated material in a V-shape with the heat-seal layer facing inward, sandwiching it from one end of the body, and heat-sealing it to form the bottom.

[0153] The contents to be filled into the packaging material are not particularly limited and may be liquids, powders, or gels. They may also be food products or non-food products. After filling with contents, the opening can be heat-sealed to create a package. [Examples]

[0154] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0155] Example 1 Medium-density polyethylene (density: 0.941 g / cm³) 3 A polyethylene film with a thickness of 100 μm was obtained by using inflation molding with a material (melting point 129°C, MFR: 1.3 g / 10 min, manufactured by Dowchemical, trade name: Elite5538G). This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain a film with a thickness of 20 μm.

[0156] Next, the film was irradiated with an electron beam from one side using an electron beam irradiation device (line irradiation type irradiation device EZ-CURE, manufactured by Iwasaki Electric Co., Ltd.) under the following conditions to obtain the substrate for the present invention. Voltage: 100kV Irradiation dose: 280kGy Oxygen concentration inside the device: 100 ppm or less Line speed: 25m / min

[0157] An image was formed on the side of the substrate opposite to the side that was irradiated with an electron beam, using gravure printing with oil-based gravure ink (manufactured by DIC Graphics Co., Ltd., product name: Finart).

[0158] As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm (product name: TUX-TCS, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) was prepared and laminated onto the image-forming surface of the substrate via the above-mentioned two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-77T / H-7) to obtain the laminate of the present invention. The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.

[0159] Example 2 A laminate was fabricated in the same manner as in Example 1, except that a 20 nm thick aluminum vapor-deposited film was formed on the laminated surface of the LLDPE film substrate by PVD.

[0160] Example 3 Medium-density polyethylene (density: 0.941 g / cm³) 3 A polyethylene film with a thickness of 100 μm was obtained by using inflation molding with a material (melting point 129°C, MFR: 1.3 g / 10 min, manufactured by Dowchemical, trade name: Elite5538G). This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain a film with a thickness of 20 μm.

[0161] An intermediate layer was fabricated by forming a 20 nm thick aluminum vapor-deposited film on one side of the polyethylene film obtained in this manner using the PVD method.

[0162] The above adhesive was applied to the vapor-deposited film formation surface of the intermediate layer, and the image-forming surface of the substrate prepared in Example 1 was laminated onto it.

[0163] The above adhesive was applied to the non-deposited surface of the intermediate layer, and the above LLDPE film with a thickness of 40 μm was laminated to obtain the laminate of the present invention.

[0164] Example 4 High-density polyethylene (density: 0.961 g / cm³) 3 A polyethylene film consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer was prepared by inflation molding using a medium-density polyethylene (HTA108) material with a melting point of 135°C and an MFR of 0.7 g / 10 min (manufactured by ExxonMobil). The thickness of the high-density polyethylene layer was 20 μm, and the thickness of the medium-density polyethylene layer was 60 μm. This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times, resulting in a film with a total thickness of 20 μm, where the high-density polyethylene layer was 4 μm thick and the medium-density polyethylene layer was 12 μm thick. The obtained film was subjected to electron beam irradiation under the same conditions as in Example 1 to obtain the substrate of the present invention.

[0165] The laminate of the present invention was prepared in the same manner as in Example 1, except that the substrate was changed to the one prepared as described above.

[0166] Comparative Example 1 The above medium-density polyethylene was used to form a film by inflation molding to obtain a polyethylene film with a thickness of 20 μm. A laminate was prepared in the same manner as in Example 1, except that the base material was changed to the polyethylene film.

[0167] Comparative Example 2 A laminate was prepared in the same manner as in Comparative Example 1, except that one side of the polyethylene film prepared in Comparative Example 1 was irradiated with an electron beam in the same manner as in Example 1.

[0168] Comparative Example 3 The above-mentioned medium-density polyethylene was fabricated using an inflation molding method to obtain a polyethylene film with a thickness of 100 μm. This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain a polyethylene film with a thickness of 20 μm. A laminate was prepared in the same manner as in Example 1, except that the base material was changed to the polyethylene film.

[0169] Comparative Example 4 A laminate was obtained in the same manner as in Example 1, except that the base material was a 12 μm thick biaxially oriented polyester film (manufactured by Toyobo Co., Ltd., product name: E5100).

[0170] <<Recyclability Assessment>> The recyclability of the laminates obtained in the above examples and comparative examples was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1. (Evaluation Criteria) ○: The polyethylene content in the laminate was 90% by mass or more. ×: The polyethylene content in the laminate was less than 90% by mass.

[0171] <<Strength Evaluation>> The laminates prepared in the above examples and comparative examples were tested for their strength when pierced with a 0.5 mm diameter needle using a tensile testing machine (Orientec Co., Ltd., product name: RTC-1310A). The piercing speed was set to 50 mm / min. The measurement results are summarized in Table 1.

[0172] <<Heat Resistance Evaluation>> Two test specimens measuring 80 mm in length and 80 mm in width were prepared from the laminates obtained in the above examples and comparative examples. Two test pieces were placed on top of each other with their heat-sealed layers facing each other, and three sides were heat-sealed at 150°C to create a small pouch-shaped packaging material. The prepared packaging materials were visually inspected, and the heat resistance of the laminate was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1. (Evaluation Criteria) ◎: No wrinkles or other defects were observed on the surface of the packaging material, and no adhesion to the heat seal bar was observed. ○: There were some wrinkles on the surface of the packaging material, and some adhesion to the heat seal bar, but these were not significant enough to cause practical problems. ×: Wrinkles and other defects were present on the surface of the packaging material, and it was also found to be adhering to the heat seal bar, making it impossible to form bags.

[0173] <<Oxygen Barrier Assessment>> The laminates obtained in the above examples and comparative examples were cut to A4 size, and the oxygen permeability (cc / m³) was measured using OXTRAN2 / 20 manufactured by MOCON, Inc., USA, in an environment of 23°C and 90% relative humidity. 2 The / day / atm (atm) was measured. The measurement results are summarized in Table 1. Note that the measurement limit is 200 cc / m³. 2 For amounts exceeding / day / atm, "-" is indicated.

[0174] <<Evaluation of water vapor barrier properties>> The laminates obtained in the above examples and comparative examples were cut to A4 size, and the water vapor transmission rate (g / m³) was measured using PERMATRAN3 / 31 manufactured by MOCON, Inc., USA, in an environment of 40°C and 90% relative humidity. 2 The / day / atm (atm) was measured. The measurement results are summarized in Table 1.

[0175] <<Heat sealability test>> The laminates obtained in the above examples and comparative examples were cut into 10cm x 10cm pieces to create sample pieces. These sample pieces were folded in half with the heat-sealed layer facing inward, and the temperature was set to 140°C and the pressure to 1kgf / cm². 2 A 1cm x 10cm area was heat-sealed under a 1-second condition. The heat-sealed sample pieces were cut into 15mm wide strips, and the unheat-sealed ends were gripped in a tensile testing machine. The peel strength (N / 15mm) was measured under conditions of a speed of 300mm / min and a load range of 50N. The measurement results are summarized in Table 1. In Comparative Example 1, the laminate obtained adhered to the heat seal bar, making it impossible to measure the peel strength, therefore it was marked as "-".

[0176] [Table 1] [Explanation of symbols]

[0177] 10: Laminate, 11: Substrate, 12: Heat seal layer, 13: Intermediate layer, 14: Adhesive layer

Claims

1. A laminate comprising at least a substrate and a heat seal layer, the substrate and the heat seal layer are made of polyethylene, One surface of the substrate has been subjected to an electron beam irradiation treatment, and the substrate has been subjected to a stretching treatment; the substrate before electron beam irradiation comprises medium-density polyethylene; the substrate is provided so that the electron beam irradiated surface of the substrate is the outermost surface; a printing layer is provided on a surface of the substrate opposite to the electron beam irradiated surface, A laminate, characterized in that the content of polyethylene in the entire laminate is 90 mass % or more.

2. The laminate according to claim 1 , wherein the thickness of the substrate is 10 μm or more and 50 μm or less.

3. The laminate according to claim 1 or 2, wherein the stretching ratio of the substrate in the longitudinal direction and / or the transverse direction is 2 times or more and 10 times or less.

4. The density of the polyethylene contained in the base material before electron beam irradiation is 0.935 g / cm ３ 0.950g / cm or more ３ The laminate according to any one of claims 1 to 3, wherein:

5. An adhesive layer is further provided between the substrate and the heat seal layer, The laminate of any one of claims 1 to 4, wherein the adhesive layer comprises a polyethylene polymer.

6. The laminate according to any one of claims 1 to 5, wherein the adhesive layer is formed using an aqueous dispersion in which the polyethylene polymer is dispersed so that the number average particle diameter is 1 µm or less.

7. The laminate according to any one of claims 1 to 6, which is used for packaging material applications.

8. A packaging material comprising the laminate according to any one of claims 1 to 7.

9. A packaging bag, A laminate according to any one of claims 1 to 7. A packaging bag characterized in that the thickness of the heat seal layer is 20 μm or more and 60 μm or less.

10. It is a stand-up pouch, The laminate according to any one of claims 1 to 7 is constituted by: The thickness of the heat seal layer is 50 μm or more and 200 μm or less. Stand up pouch.

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