JP7763197B2 - Substrates, laminates, packaging materials, packaging bags and stand-up pouches - Google Patents

Description

The present invention relates to a substrate, a laminate comprising the substrate, and packaging materials, packaging bags, and stand-up pouches constructed from the laminate.

Conventionally, resin films made from resin materials have been used as packaging materials. For example, resin films made from polyolefins are widely used as packaging materials because they have moderate flexibility and transparency, as well as excellent heat-sealing properties.

Resin films made from polyolefins typically have poor strength and heat resistance and cannot be used as base materials for packaging materials, etc., and are instead laminated with resin films made from polyester, polyamide, etc. For this reason, typical packaging materials are made from laminates in which the base material and heat seal layer are made from different resin materials (see, for example, Patent Document 1).

In recent years, with growing calls for the creation of a recycling-oriented society, there has been a demand for packaging materials to be highly recyclable. However, as mentioned above, conventional packaging materials are composed of different resin materials, and because it is difficult to separate the individual resin components, they are not currently recycled.

Japanese Patent Application Laid-Open No. 2009-202519

The present inventors have discovered that by subjecting a polyolefin film, specifically a polyethylene film, which has conventionally been used as a heat seal layer, to a stretching treatment and an electron beam irradiation treatment, the strength and heat resistance of the film can be significantly improved, and the film can be used as a base material for packaging materials, etc.
Furthermore, the inventors discovered 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, etc.

The present invention was made in light of the above findings, and the problem it aims to solve is to provide a substrate that has sufficient strength and barrier properties to be used as a substrate for packaging materials, etc., and that also enables the production of packaging materials that are highly recyclable.

Another problem that the present invention aims to solve is to provide a laminate comprising this substrate.

Furthermore, the problem to be solved by the present invention is to provide packaging materials, packaging bags, and stand-up pouches made from this laminate.

The substrate of the present invention is a film made of polyethylene,
The film has been subjected to a stretching treatment,
At least one surface of the film has been subjected to electron beam irradiation treatment;
The film is characterized by having a vapor-deposited film on at least one surface thereof.

In one embodiment, the thickness of the substrate of the present invention is 10 μm or more and 50 μm or less.

In one embodiment, the stretching ratio of the substrate of the present invention in the longitudinal and/or transverse directions is 2 times or more and 10 times or less.

In one embodiment, the density of the polyethylene before electron beam irradiation is 0.935 g/cm ³ or more and 0.957 g/cm ³ or less.

In one embodiment, the thickness of the deposited film is 1 nm or more and 150 nm or less.

The laminate of the present invention is
The substrate;
a heat seal layer;
a substrate is provided so that the electron beam irradiated surface of the substrate is the outermost surface and the surface of the substrate on which the vapor-deposited film is formed is the heat seal layer side;
The heat seal layer is made of polyethylene.

In one embodiment, the laminate of the present invention is used in packaging applications.

The packaging material of the present invention is characterized by being composed of the above-mentioned laminate.

The packaging bag of the present invention is composed of the above-mentioned laminate,
The thickness of the heat seal layer is 20 μm or more and 60 μm or less.

The stand-up pouch of the present invention is constituted by the above-mentioned laminate,
The thickness of the heat seal layer is 50 μm or more and 200 μm or less.

The present invention provides a substrate that has sufficient strength and barrier properties to be used as a base material for packaging materials, and also enables the production of packaging materials that are highly recyclable.

1 is a cross-sectional schematic view showing one embodiment of a substrate of the present invention. 1 is a cross-sectional schematic view showing one embodiment of a substrate of the present invention. 1 is a cross-sectional schematic view showing one embodiment of a laminate of the present invention. 1 is a cross-sectional schematic view showing one embodiment of a laminate of the present invention. 1 is a perspective view showing one embodiment of a packaging material produced using a laminate of the present invention. 1 is a perspective view showing one embodiment of a packaging material produced using a laminate of the present invention.

(Base material)
As shown in FIG. 1, the substrate 10 of the present invention is a film 11 made of polyethylene, which is characterized by having been stretched and having at least one surface thereof subjected to electron beam irradiation.
In this way, by stretching a film made of polyethylene and irradiating at least one surface of the film with an electron beam to increase the crosslink density of the polyethylene, the heat resistance and strength of the film can be significantly improved, and the film can satisfy the physical properties required for the outer layer of packaging materials, etc.
The substrate 10 of the present invention also has a vapor-deposited film 12 on at least one surface.

As the polyethylene, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene and very low density polyethylene can be used.
Among these, high density polyethylene and medium density polyethylene are preferred from the viewpoint of the strength and heat resistance of the substrate, and medium density polyethylene is more preferred from the viewpoint of the stretchability.

In the present invention, the high-density polyethylene may be polyethylene having a density of 0.945 g/cm3 or ^more , the medium-density polyethylene may be polyethylene having a density of 0.925 g/cm3 ^or more and less than 0.945 g/ ^cm3 , the low-density polyethylene may be polyethylene having a density of 0.900 g/cm3 ^or more and less than 0.925 g/ ^cm3 , the linear low-density polyethylene may be polyethylene having a density of 0.900 g/cm3 ^or more and less than 0.925 g/ ^cm3 , and the ultra-low-density polyethylene may be polyethylene having a density less than 0.900 g/ ^cm3 .
In the present invention, it is preferable to use polyethylene having a density of 0.935 g/cm ^or more and 0.950 g/cm ^or less. By using polyethylene having such a density, the crosslinking reaction proceeds more smoothly, and the strength and heat resistance of the substrate can be further improved.

Polyethylenes with different densities and branching such as those described above can be obtained by appropriately selecting the 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 the polymerization catalyst, and to carry out the polymerization in one stage or two or more stages using one of the following methods: gas phase polymerization, slurry polymerization, solution polymerization, or high-pressure ionic polymerization.

The single-site catalyst is a catalyst capable of forming a uniform active species, and is typically 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, compared to multi-site catalysts, they have a uniform active site structure and can polymerize polymers with high molecular weights and highly uniform structures. Metallocene catalysts are particularly preferred as single-site catalysts. Metallocene catalysts are catalysts that contain the following catalytic components: a transition metal compound of Group IV of the periodic table containing a ligand with a cyclopentadienyl skeleton, a cocatalyst, and, optionally, an organometallic compound and a carrier.

In the above-mentioned transition metal compounds of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, the cyclopentadienyl skeleton may be a cyclopentadienyl group, a substituted cyclopentadienyl group, or the like. 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, and halosilyl groups. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may bond to each other to form a ring, such as an indenyl ring, a fluorenyl ring, an azulenyl ring, or a hydrogenated version thereof. The rings formed by bonding the substituents to each other may further have substituents.

In the transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, the transition metal can be zirconium, titanium, hafnium, or the like, with zirconium and hafnium being particularly preferred. The transition metal compound typically contains two ligands having a cyclopentadienyl skeleton, and the cyclopentadienyl ligands 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. Substituted silylene groups are preferred. The above-mentioned transition metal compounds of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton can be used as a catalyst component, either singly or in combination.

The co-catalyst refers to a catalyst that can effectively use the above-mentioned transition metal compounds of Group IV of the periodic table as a polymerization catalyst, or that can balance the ionic charge in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes of organoaluminum oxy compounds and 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.

The transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton may be used by being supported on an inorganic or organic carrier. The carrier is preferably an inorganic or organic porous oxide, and specific examples include ion-exchange layered silicates such as montmorillonite, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO ₂ , and mixtures thereof. Furthermore, examples of organometallic compounds that may be used if necessary include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these, organoaluminum compounds are preferred.

Copolymers of ethylene and other monomers can also be used as long as they do not impair the properties of the present invention. Examples of ethylene copolymers include copolymers of ethylene and an α-olefin 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. Copolymers with vinyl acetate or acrylic esters, etc., can also be used as long as they do not impair the objectives of the present invention.

In addition, in the present invention, biomass-derived ethylene may be used as the raw material for obtaining the polyethylene, instead of ethylene obtained from fossil fuels. Because such biomass-derived polyethylene is a carbon-neutral material, it is possible to reduce the environmental impact of packaging materials and other products made from laminates containing the multilayer substrate. Such biomass-derived polyethylene can be produced, for example, by a method such as that described in JP 2013-177531 A. Alternatively, commercially available biomass-derived polyethylene (such as Green PE, available from Braskem) may be used.

Polyethylene recycled through mechanical recycling can also be used. Mechanical recycling generally refers to a method in which recovered polyethylene film is crushed and washed with alkali to remove dirt and foreign matter from the film surface, and then dried at high temperature and reduced pressure for a certain period of time to diffuse any contaminants remaining inside the film, thereby decontaminating it and removing the dirt from the polyethylene film and returning it to polyethylene.

The base material may contain additives as long as they do not impair the properties of the present invention. Examples of such additives include crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

In one embodiment, the substrate of the present invention has a multi-layer structure.
In one embodiment, the substrate of the present invention includes a layer composed of high-density polyethylene (hereinafter referred to as high-density polyethylene layer), a layer composed of medium-density polyethylene (hereinafter referred to as medium-density polyethylene layer), and a layer composed of high-density polyethylene (hereinafter referred to as high-density polyethylene layer).
By adopting such a configuration, the strength and heat resistance of the substrate can be further improved while maintaining the stretchability of the substrate.
In this case, the thickness of the high density polyethylene layer is preferably 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. Also, 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.

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 the sake of simplicity), a medium-density polyethylene layer, and a high-density polyethylene layer.
By adopting such a configuration, it is possible to improve the stretchability of the substrate, improve the strength and heat resistance of the substrate, prevent the occurrence of curling in the substrate, and improve the production efficiency of the substrate.
In this case, the thickness of the high density polyethylene layer is preferably 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, and 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.
The thickness of the high-density polyethylene layer is preferably 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 be 1/0.25 or more, the heat resistance of the substrate can be improved. Also, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer to be 1/1 or less, the adhesion between the medium-density polyethylene layers can be improved.
In one embodiment, a substrate having such a configuration can be produced by, for example, an inflation method.
Specifically, the film can be produced 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 from the outside into a tubular shape, 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 using such a method, the number of defective products in the manufacturing process can be significantly reduced, and ultimately production efficiency can be improved.
Furthermore, stretching can also be carried out in the inflation film-forming machine, which can further improve production efficiency.

The substrate may be a uniaxially stretched film or a biaxially stretched film.
The stretching ratio in the machine direction (MD) of the substrate is preferably 2 times or more and 10 times or less, and more preferably 3 times or more and 7 times or less.
By setting 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. Furthermore, the transparency of the substrate can be improved. On the other hand, the upper limit of the stretching ratio in the longitudinal direction (MD) of the substrate is not particularly limited, but it is preferably 10 times or less from the viewpoint of the breaking limit of the substrate.
The stretching ratio in the transverse direction (TD) of the substrate is preferably 2 times or more and 10 times or less, and more preferably 3 times or more and 7 times or less.
By setting 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. Furthermore, the transparency of the substrate can be improved. On the other hand, the upper limit of the stretching ratio in the transverse direction (TD) of the substrate is not particularly limited, but it is preferably 10 times or less from the viewpoint of the breaking limit of the substrate.

The substrate 10 may be one in which the crosslink density of polyethylene on one surface has been improved by electron beam irradiation, as shown in FIG. 1, or one in which the crosslink density of polyethylene has been improved throughout the entire substrate, as shown in FIG. 2.
When the substrate has a multi-layer structure, it is sufficient that the crosslink 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 crosslink density of the polyethylene as a whole is improved by electron beam irradiation.

The device that can be used to irradiate the substrate with electron beams can be a conventionally known device, such as a curtain-type electron beam irradiation device (LB1023, manufactured by i-Electron Beam Co., Ltd.), a line-type low-energy electron beam irradiation device (EB-ENGINE, manufactured by Hamamatsu Photonics K.K.), or a drum roll-type electron beam irradiation device (EZ-CURE, manufactured by i-Electron Beam Co., Ltd.).

The dose of the electron beam irradiated onto the substrate is preferably in the range of 10 kGy to 2000 kGy, more preferably in the range of 20 kGy to 1000 kGy.
The acceleration voltage of the electron beam is preferably in the range of 30 kV to 300 kV, more preferably in the range of 50 kV to 300 kV, and even more preferably in the range of 50 kV to 250 kV.
The irradiation energy of the electron beam 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.

The oxygen concentration inside the electron beam irradiation device is preferably 500 ppm or less, and more preferably 100 ppm or less. By performing electron beam irradiation under these conditions, it is possible to suppress the generation of ozone and prevent the radicals generated by electron beam irradiation from being deactivated by oxygen in the atmosphere. These conditions can be achieved, for example, by creating an inert gas (nitrogen, argon, etc.) atmosphere inside the device.

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

The substrate may also be subjected to a surface treatment, which can improve adhesion between adjacent layers when the substrate is formed into a laminate as described below.
The method of surface treatment is not particularly limited, and examples thereof include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and/or nitrogen gas, and glow discharge treatment, as well as chemical treatments such as oxidation treatment using chemicals.
Alternatively, an anchor coating layer may be formed on the surface of the substrate using a conventionally known anchor coating agent.

The substrate of the present invention may have an image formed on its surface. The image to be formed is not particularly limited, and may be a letter, a pattern, a symbol, or a combination thereof.
The image formation on the substrate is preferably carried out using ink derived from biomass, and by using the substrate of the present invention, packaging materials and the like that impose less of a burden on the environment can be produced.
The method for forming the image is not particularly limited, and examples thereof include conventionally known printing methods such as gravure printing, offset printing, flexographic printing, etc. Among these, flexographic printing is preferred from the viewpoint of environmental load.

1 and 2, the substrate 10 of the present invention has a vapor-deposited film 12 on at least one surface thereof, which can improve the gas barrier properties, specifically the oxygen barrier properties and water vapor barrier properties.
In addition, when the crosslink density of only the polyethylene on one side of the polyethylene film 11 is improved by electron beam irradiation, as in the substrate shown in Figure 1, it is preferable that the vapor-deposited film be provided on the other side of the substrate.

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

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, the oxygen barrier property and water vapor barrier property 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. Furthermore, when the substrate of the present invention is applied to the laminate described below, its recyclability can be maintained.

In one embodiment, the substrate of the present invention includes a barrier coat layer, which can improve the oxygen barrier property and water vapor barrier property of the substrate.
The barrier coat layer may be provided on or under the vapor-deposited film.

In one embodiment, the barrier coat layer contains a gas barrier resin such as ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyacrylonitrile, polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide (MXD6), polyester, polyurethane, and (meth)acrylic resin. Among these, polyvinyl alcohol is preferred from the viewpoint of oxygen barrier property and water vapor barrier property.
Furthermore, when the vapor-deposited film is made of an inorganic oxide, the occurrence of cracks in the vapor-deposited film can be effectively prevented by including polyvinyl alcohol in the barrier coat layer.

The content of the gas barrier resin 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 making the content of the gas barrier resin in the barrier coat layer 50% by mass or more, the oxygen barrier property and water vapor barrier property of the substrate of the present invention can be further improved.

The barrier coat layer may contain the above additives as long as they do not impair the properties of the present invention.

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 making the thickness of the barrier coat layer 0.01 μm or more, the oxygen barrier property and water vapor barrier property of the substrate of the present invention can be further improved. By making the thickness of the barrier coat layer 10 μm or less, the recyclability of the substrate of the present invention can be maintained when it is applied to the laminate described below.

The barrier coat layer can be formed by dissolving or dispersing the above materials in water or a suitable solvent, applying the solution, and drying. Alternatively, the barrier coat layer can be formed by applying and drying a commercially available barrier coating agent.

In another embodiment, the barrier coat layer is a gas barrier coating film containing at least one resin composition such as a hydrolyzate of a metal alkoxide or a hydrolysis condensate of a metal alkoxide obtained by polycondensing 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, an organic solvent, etc.
When the substrate of the present invention has a vapor-deposited film made of an inorganic oxide, by providing a barrier coat layer of this type adjacent to the vapor-deposited film, it is possible to effectively prevent cracks from occurring in the vapor-deposited film.

In one embodiment, the metal alkoxide is represented by the following general formula:
R ¹ _n M(OR ² ) _m
(In the formula, R ¹ and R ² each represent 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.)

As the metal atom M, for example, silicon, zirconium, titanium, aluminum, etc. can be used.
Examples of the organic groups represented by R ¹ and R ² include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and an i-butyl group.

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 ).

It is also preferable to use a silane coupling agent together with the metal alkoxide.
As the silane coupling agent, known organoalkoxysilanes containing organic reactive groups can be used, but organoalkoxysilanes containing epoxy groups are particularly preferred. Examples of organoalkoxysilanes containing epoxy groups include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

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

Preferred water-soluble polymers are polyvinyl alcohol and ethylene-vinyl alcohol copolymers, and from the standpoints of oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance, it is preferable to use these in combination.

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 the metal alkoxide.
By adjusting 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 the metal alkoxide, the oxygen barrier property and water vapor barrier property of the substrate of the present invention can be further improved. Also, by adjusting 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 the metal alkoxide, the film formability of the gas barrier coating film can be improved.

The thickness of the gas barrier coating film is preferably 0.01 μm or more and 100 μm or less, and more preferably 0.1 μm or more and 50 μm or less, which can further improve the oxygen barrier property and water vapor barrier property while maintaining recyclability.
By making the thickness of the gas barrier coating film 0.01 μm or more, the oxygen barrier property and water vapor barrier property of the substrate of the present invention can be improved. Furthermore, when the gas barrier coating film is provided adjacent to a vapor-deposited film made of an inorganic oxide, the occurrence of cracks in the vapor-deposited film can be prevented.

The gas barrier coating film can be formed by applying a composition containing the above-mentioned materials by a conventionally known means such as roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, or applicator coating, and then polycondensing the composition by a sol-gel method.
The sol-gel catalyst is preferably an acid or an amine compound. As the amine compound, a tertiary amine that is substantially insoluble in water and soluble in an organic solvent is preferred, such as N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. Among these, N,N-dimethylbenzylamine is preferred.
The sol-gel catalyst is preferably used in the range of 0.01 to 1.0 part by mass, more preferably 0.03 to 0.3 part by mass, per 100 parts by mass of the metal alkoxide.
By using a sol-gel catalyst in an amount of 0.01 part by mass or more per 100 parts by mass of the metal alkoxide, the catalytic effect can be improved, and by using a sol-gel catalyst in an amount of 1.0 part by mass or less per 100 parts by mass of the metal alkoxide, the thickness of the gas barrier coating film formed can be made uniform.

The composition may further contain an acid, which is used as a catalyst in the sol-gel process, mainly for the hydrolysis of alkoxides, silane coupling agents, etc.
The acid may be a mineral acid such as sulfuric acid, hydrochloric acid, or nitric acid, or an organic acid such as acetic acid, tartaric acid, etc. The amount of the acid used is preferably 0.001 mol or more and 0.05 mol or less based on the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.
The catalytic effect can be improved by using an acid in an amount of 0.001 mole or more relative to the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent, and the thickness of the gas barrier coating film formed can be made uniform by using an acid in an amount of 0.05 mole or less relative to the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.

The composition preferably contains water in an amount of 0.1 to 100 moles, more preferably 0.8 to 2 moles, per mole of the total molar amount of the alkoxides.
By adjusting the water content to 0.1 mol or more per mol of the total molar amount of alkoxide, the oxygen barrier property and water vapor barrier property of the laminate of the present invention can be improved. Furthermore, by adjusting the water content to 100 mol or more per mol of the total molar amount of alkoxide, the hydrolysis reaction can be carried out quickly.

The composition may also contain an organic solvent. Examples of organic solvents that can be used include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butanol.

An embodiment of the method for forming a gas barrier coating film will be described below.
First, a composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and optionally a silane coupling agent, etc. A polycondensation reaction gradually proceeds in the composition.
Next, the composition is applied onto the polyolefin resin layer by the above-mentioned conventionally known method and dried, which further promotes the polycondensation reaction of the alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains one) to form a composite polymer layer.
Finally, the composition is heated at a temperature of 20 to 250° C., preferably 50 to 220° C., for 1 second to 10 minutes to form a gas barrier coating film.

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

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 thickness of the substrate 10 μm or more, the strength required for the substrate of packaging materials etc. can be fully satisfied. Furthermore, by making the thickness of the substrate 50 μm or less, the processability of the substrate can be improved.

The substrate can be produced by forming a resin composition containing at least polyethylene into a film using a T-die method, an inflation method, or the like, to form a resin film, and then stretching and irradiating it with an electron beam.
By forming the film by the inflation method, the resin film can be stretched at the same time.
The resin film may be stretched or irradiated with electron beams in either order, but it is preferable to perform the stretching first in terms of suitability for stretching processing.

When the substrate is produced by the T-die method, the resin composition preferably has an MFR of 3 g/10 min or more and 20 g/10 min or less.
By setting the MFR of the resin composition to 3 g/10 min or more, the processability of the substrate of the present invention can be improved, and by setting the MFR of the resin composition to 20 g/10 min or less, the substrate can be prevented from breaking.

When the substrate is produced by an 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 adjusting the MFR of the resin composition to 0.5 g/10 min or more, the processability of the substrate of the present invention can be improved, and by adjusting the MFR of the resin composition to 5 g/10 min or less, the film-forming property can be improved.

The deposition film can be formed using conventional methods, such as physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition (CVD) methods such as plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

Furthermore, for example, a composite film consisting of two or more layers of vapor-deposited films of different inorganic oxides can be formed and used by combining physical vapor deposition and chemical vapor deposition. The degree of vacuum in the vapor deposition chamber is preferably about 10 ^-2 to 10 ^-8 mbar before oxygen is introduced, and about 10 ^-1 to 10 ^-6 mbar after oxygen is introduced. The amount of oxygen introduced varies depending on the size of the vapor deposition machine, etc. For the oxygen to be introduced, an inert gas such as argon gas, helium gas, or nitrogen gas may be used as a carrier gas, provided that this does not cause any problems. The film transport speed can be about 10 to 800 m/min.

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

(Laminate)
As shown in FIG. 3, the laminate 13 of the present invention comprises the above-mentioned substrate 10 and a heat seal layer 14 .
Furthermore, the heat seal layer of the laminate of the present invention is made of polyethylene, and by adopting such a configuration, the recyclability of the laminate can be improved.

In one embodiment, the laminate 13 of the present invention includes an intermediate layer 15 between the substrate 10 and the heat seal layer 14, as shown in Figure 4.

In one embodiment, the laminate of the present invention may include an adhesive layer 16 between any of the layers, as shown in Figures 3 and 4.

The content of polyethylene in the entire laminate of the present invention is preferably 90% by mass or more, more preferably 90% by mass or more.
By making the polyethylene content in the entire laminate of the present invention 90% by mass or more, the recyclability of the laminate of the present invention can be improved.

The following describes each layer that makes up the laminate of the present invention.

(Base material)
In the laminate, the substrate is provided so that the electron beam irradiated surface is the outermost surface and the surface on which the vapor-deposited film is formed is the heat seal layer side. Details of the configuration of the substrate have been described above and will not be described here.

(Heat seal layer)
The heat seal layer is characterized by being composed of polyethylene. Since the laminate of the present invention is composed of a substrate and a heat seal layer both composed of polyethylene, the recyclability of packaging materials and the like produced using the laminate can be improved.
However, the heat seal layer is formed from an unstretched polyolefin resin film or by melt extrusion of polyolefin.

From the viewpoint of heat sealing properties, it is preferable to use low density polyethylene, linear low density polyethylene, and very low density polyethylene as the polyethylene.
Furthermore, the above-mentioned biomass-derived polyethylene and mechanically recycled polyethylene can also be used.

The thickness of the heat seal layer is preferably changed appropriately depending on the weight of the contents to be filled in the packaging material made from the laminate of the present invention.
For example, when producing a packaging bag as shown in FIG. 5 which is filled with a content of 1 g or more and 200 g or less, the thickness of the heat seal layer is preferably 20 μm or more and 60 μm or less.
By making the thickness of the heat seal layer 20 μm or more, it is possible to prevent leakage of the filled contents due to damage to the heat seal layer, and by making the thickness of the heat seal layer 60 μm or less, it is possible to improve the processability of the laminate of the present invention.

Furthermore, for example, when producing a stand pouch as shown in FIG. 6 which is filled with a content of 50 g or more and 2000 g or less, the thickness of the heat seal layer is preferably 50 μm or more and 200 μm or less.
By making the thickness of the heat seal layer 50 μm or more, it is possible to prevent the contents from leaking due to damage to the heat seal layer, and by making the thickness of the heat seal layer 200 μm or less, it is possible to improve the processability of the laminate of the present invention.
The hatched areas in Figures 5 and 6 are heat-sealed areas.

The heat seal layer may have a vapor-deposited film on its substrate-side surface. By providing a vapor-deposited film, oxygen barrier properties and water vapor barrier properties can be improved.

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

Furthermore, 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.

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

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

(middle class)
In one embodiment, the intermediate layer comprises an oriented polyethylene film, which can further enhance the strength of the laminate of the present invention.
The stretched polyethylene film is made of polyethylene, and high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene can be used.
Biomass-derived polyethylene and mechanically recycled polyethylene can also be used.

The stretched polyethylene film may also have the above-mentioned multilayer structure.

The stretched polyethylene film may be a uniaxially stretched film or a biaxially stretched film, and the preferred stretching ratio is as described above.

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, and by making the thickness of the stretched polyethylene film 50 μm or less, the processability of the laminate can be improved.

In one embodiment, the intermediate layer includes a gas barrier layer made of a gas barrier resin. When the laminate of the present invention includes such an intermediate layer, the oxygen barrier property and water vapor barrier property 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 polymetaxylylene adipamide (MXD6), polyesters, polyurethanes, and (meth)acrylic resins.

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 property and water vapor barrier property of the laminate of the present invention can be further improved, and 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.

In one embodiment, the intermediate layer comprises a vapor-deposited film. The types of vapor-deposited films that can be used, their preferred thicknesses, and formation methods are as described above.

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

(adhesive layer)
The laminate of the present invention may have an adhesive layer between any of the layers, thereby improving the adhesion between the layers.

The adhesive layer may be formed from a conventionally known adhesive, which may be a one-component curing adhesive, a two-component curing adhesive, or a non-curing adhesive.
The adhesive may be either a solvent-free adhesive or a solvent-based adhesive, but from the viewpoint of environmental load, a solvent-free adhesive is preferably used.
Examples of solvent-free adhesives include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, and urethane adhesives, and among these, two-component curing urethane adhesives can be 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.

Furthermore, when 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 phosphoric acid-modified compound.
Furthermore, when a laminate with a vapor-deposited film is molded into a packaging material, a bending load is applied to the laminate by a molding machine or the like, which may cause cracks in the aluminum vapor-deposited film. By configuring the adhesive layer as described above, it is possible to suppress a decrease in the oxygen barrier property and water vapor barrier property (flexural load resistance) even if cracks occur in the aluminum vapor-deposited film.

Polyester polyols have two or more hydroxyl groups as functional groups in each molecule. Also, isocyanate compounds have two or more isocyanate groups as functional groups in each molecule. Polyester polyols have, for example, a polyester structure or a polyester polyurethane structure as their main skeleton.

Specific examples of resin compositions (adhesives) containing polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound include the PASLIM series sold by DIC Corporation.

The resin composition may further contain a plate-like inorganic compound, a coupling agent, cyclodextrin and/or its derivatives, etc.

As the polyester polyol having two or more hydroxyl groups in one molecule as functional groups, for example, the following [Example 1] to [Example 3] can be used.
[Example 1] Polyester polyol obtained by polycondensation of ortho-oriented polycarboxylic acid or its anhydride with polyhydric alcohol [Example 2] Polyester polyol having a glycerol skeleton [Example 3] Polyester polyol having an isocyanuric ring Each polyester polyol will be explained below.

The polyester polyol according to the first example is a polycondensate obtained by polycondensing a polycarboxylic acid component containing at least one or more orthophthalic acid and anhydrides thereof and 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 the content of orthophthalic acid and its anhydride relative to the total amount of polycarboxylic acid components is 70 to 100% by mass are preferred.

The polyester polyol according to the first example essentially contains orthophthalic acid and its anhydride as polycarboxylic acid components, but other polycarboxylic acid components may be copolymerized within a range that does not impair the effects of this embodiment.
Specific 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, aromatic polycarboxylic acids such as 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.
Two or more of the above other polycarboxylic acids may be used.

As a polyester polyol according to the second example, a polyester polyol having a glycerol skeleton represented by general formula (1) can be mentioned.
In general formula (1), R ₁ , R ₂ and R ₃ are each independently H (hydrogen atom) or a group represented by the following general formula (2).

In formula (2), n represents an integer of 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 a substituent, and Y represents an alkylene group having 2 to 6 carbon atoms.
However, at least one of R ₁ , R ₂ and R ₃ represents a group represented by general formula (2).

In general formula (1), at least one of R ₁ , R ₂ and R ₃ must be a group represented by general formula (2). In particular, it is preferable that all of R ₁ , R ₂ and R ₃ are groups represented by general formula (2).

In addition, the compound may be a mixture of two or more of a compound in which any one of R ₁ , R ₂ , and R ₃ is a group represented by general formula (2), a compound in which any two of R 1 , _{R 2} , and R _{3 are groups represented by general formula (2), and a compound in which all of R 1 , R 2 , and R 3 are groups represented} by general formula (2).

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 a substituent.
When X is substituted with a substituent, it may be substituted with one or more substituents, and the substituent is bonded to any carbon atom on X that is different from the free radical. Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.

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

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

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

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

The polyester polyol according to the third example is a polyester polyol having an isocyanuric ring represented by the following general formula (3).
In general formula (3), R ₁ , R ₂ and R ₃ each independently represent "-(CH ₂ )n1-OH (wherein n1 represents an integer of 2 to 4)" or a structure of general formula (4).

In general formula (4), n2 represents an integer of 2 to 4, n3 represents an integer of 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 a substituent, and Y represents an alkylene group having 2 to 6 carbon atoms, provided that at least one of R ₁ , R ₂ , and R ₃ is a group represented by general formula (4).

In the general formula (3), the alkylene group represented by —(CH ₂ )n1— may be linear or branched. Among these, n1 is preferably 2 or 3, and most preferably 2.

In the general formula (4), n2 represents an integer of 2 to 4, and n3 represents an integer of 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 a substituent.

When X is substituted with a substituent, it may be substituted with one or more substituents, and the substituent is bonded to any carbon atom on X that is different from the free radical. Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.
The substituent for X is preferably a hydroxyl group, a cyano group, a nitro group, an amino group, a phthalimido group, a carbamoyl group, an N-ethylcarbamoyl group, or a phenyl group, and most preferably a hydroxyl group, a phenoxy group, a cyano group, a nitro group, a phthalimido group, or a phenyl group.

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

In general formula (3), at least one of R ₁ , R ₂ and R ₃ is a group represented by general formula (4). In particular, it is preferable that all of R ₁ , R ₂ and R ₃ are groups represented by general formula (4).

In addition, the compound may be a _{mixture of two or more of a compound in which any one of R 1 , R 2 , and} R ₃ is a group represented by general formula (4), a compound in which any two of R ₁ , R ₂ , and R ₃ are groups represented by general formula (4), and a compound in which all of R ₁ , R ₂ , and R 3 are groups represented by general formula (4).

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

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

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

Such substituents include chloro, bromo, methyl, ethyl, i-propyl, hydroxyl, methoxy, ethoxy, phenoxy, methylthio, phenylthio, cyano, nitro, amino, phthalimido, carboxyl, carbamoyl, N-ethylcarbamoyl, phenyl, and naphthyl groups.

The polyhydric alcohol component may be an alkylene diol having 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, or dimethylbutanediol.
Among these, polyester polyol compounds having an isocyanuric ring, which use 1,3,5-tris(2-hydroxyethyl)isocyanuric acid or 1,3,5-tris(2-hydroxypropyl)isocyanuric acid as the triol compound having an isocyanuric ring, orthophthalic anhydride as the aromatic polycarboxylic acid or its anhydride in which the carboxylic acid is substituted at the ortho position, and ethylene glycol as the polyhydric alcohol, are particularly excellent in oxygen barrier properties and adhesiveness and are therefore preferred.

Isocyanuric rings are highly polar and trifunctional, which can increase the polarity of the entire system and increase the crosslink density. From this perspective, it is preferable for the adhesive resin to contain 5% or more by mass of isocyanuric rings relative to the total solids content.

The isocyanate compound has two or more isocyanate groups in the molecule.
The isocyanate compound may be either aromatic or aliphatic, and may be either a low molecular weight compound or a high molecular weight compound.
Furthermore, the isocyanate compound may be a blocked isocyanate compound obtained by addition reaction using a known isocyanate blocking agent by a known, conventional appropriate method.
Among these, from the viewpoints of adhesiveness and retort resistance, polyisocyanate compounds having three or more isocyanate groups are preferred, and from the viewpoints of oxygen barrier property and water vapor barrier property, aromatic compounds are preferred.

Specific examples of the isocyanate compound include 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, biurets, and allophanates obtained by reacting these isocyanate compounds with low-molecular-weight active hydrogen compounds or alkylene oxide adducts thereof, 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 high molecular weight active hydrogen compounds include polymeric active hydrogen compounds of various polyester resins, polyether polyols, and polyamides.

The phosphoric acid-modified compound is, for example, a compound represented by the following general formula (5) or (6).
In general formula (5), R ₁ , R ₂ , and R ₃ are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, a phenyl group which may have a substituent, and an alkyl group having 1 to 4 carbon atoms which has a (meth)acryloyloxy group, at least one of which is a hydrogen atom, and n is an integer of 1 to 4.
In the formula, R ₄ and R ₅ are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, a phenyl group which may have a substituent, and an alkyl group having 1 to 4 carbon atoms and having a (meth)acryloyloxy group, n is an integer of 1 to 4, x is an integer of 0 to 30, and y is an integer of 0 to 30, except when both x and y are 0.

More specifically, examples include phosphoric acid, pyrophosphoric acid, triphosphoric acid, 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.

The content of the phosphoric acid-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 adjusting the content of the phosphate-modified compound to 0.005% by mass or more, the oxygen barrier property and water vapor barrier property of the laminate of the present invention can be improved, and by adjusting the content of the phosphate-modified compound to 10% by mass or less, the adhesiveness of the adhesive layer can be improved.

The resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound may contain a plate-like inorganic compound, which can improve the adhesiveness of the adhesive layer and the flex load resistance of the laminate of the present invention.
Examples of the plate-like inorganic compounds include kaolinite-serpentine group clay minerals (halloysite, kaolinite, endelite, dickite, nacrite, antigorite, chrysotile, etc.) and pyrophyllite-talc group (pyrophyllite, talc, keroli, etc.).

Examples of the coupling agent include a silane-based coupling agent, a titanium-based coupling agent, and an aluminum-based coupling agent, which are represented by the following general formula (7). These coupling agents may be used alone or in combination of two or more.

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 N-β(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-isocyanatopropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethylbutylidene).

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 dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, diisostearoyl ethylene titanate, isopropyl tri(dioctyl phosphate)titanate, isopropyl tricumyl phenyl titanate, and dicumyl phenyl oxyacetate titanate.

Specific examples of aluminum-based coupling agents include acetoalkoxyaluminum diisopropylate, diisopropoxyaluminum ethyl acetoacetate, diisopropoxyaluminum monomethacrylate, isopropoxyaluminum alkyl acetoacetate mono(dioctyl phosphate), aluminum 2-ethylhexanoate oxide trimer, aluminum stearate oxide trimer, and alkyl acetoacetate aluminum oxide trimer.

The resin composition may contain cyclodextrin and/or a derivative thereof, which can improve the adhesiveness of the adhesive layer and the flex load resistance of the laminate of the present invention.
Specifically, for example, cyclodextrin, alkylated cyclodextrin, acetylated cyclodextrin, hydroxyalkylated cyclodextrin, and the like, in which the hydrogen atoms of the hydroxyl groups of the glucose units of cyclodextrin are substituted with other functional groups, can be used. Branched cyclic dextrins can also be used.
The cyclodextrin skeleton in the cyclodextrin and cyclodextrin derivatives may be any of α-cyclodextrin consisting of six glucose units, β-cyclodextrin consisting of seven glucose units, and γ-cyclodextrin consisting of eight glucose units.
These compounds may be used alone or in combination of two or more. These cyclodextrins and/or their derivatives may hereinafter be collectively referred to as dextrin compounds.

From the standpoint of compatibility and dispersibility in the resin composition, it is preferable to use a cyclodextrin derivative as the cyclodextrin compound.

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

Acetylated cyclodextrins include, for example, monoacetyl-α-cyclodextrin, monoacetyl-β-cyclodextrin, and monoacetyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

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

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 thickness of the adhesive layer 0.5 μm or more, the adhesiveness of the adhesive layer can be improved. Furthermore, when the adhesive layer is configured from a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound, the flex load resistance of the laminate can be improved.
By setting the thickness of the adhesive layer to 6 μm or less, the processability of the laminate can be improved.

The adhesive layer can be formed by applying and drying onto a substrate or the like using conventional methods such as direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine coating, and transfer roll coating.

The laminate of the present invention is particularly suitable for use as a packaging material in the following applications:

(packaging material)
The packaging material of the present invention is characterized by being composed of the above laminate.
The shape of the packaging material is not particularly limited, and may be a bag shape as shown in FIG.
In the figure, the shaded areas represent the heat-sealed areas.

In one embodiment, a bag-shaped packaging material can be produced by folding the laminate of the present invention in half, overlapping the laminate with the heat seal layer on the inside, and heat sealing the edges.
In another embodiment, the bag-shaped packaging material can also be produced by overlapping two laminates with their heat-sealable layers facing each other, and then heat-sealing the ends thereof.

The heat sealing method is not particularly limited, and can be performed using known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

In one embodiment, the packaging material has a stand-up pouch shape with a body and a bottom, as shown in Figure 6.

Stand-up pouch-shaped packaging materials can be produced by heat-sealing the above laminate into a cylindrical shape with the heat-seal layer facing inward to form the body, then folding another laminate into a V-shape with the heat-seal layer facing inward, sandwiching it in from one end of the body, and heat-sealing to form the bottom.

The contents filled into the packaging material are not particularly limited, and may be liquid, powder, or gel. The contents may also be food or non-food.
After filling the contents, the opening can be heat-sealed to form a package.

The present invention will now be described in more detail using examples, but the present invention is not limited to these examples.

Example 1
Medium-density polyethylene (density: 0.941 g/cm, melting point: 129°C, MFR: 1.3 g/10 min, manufactured by Dow Chemical, trade name: Elite 5538G) was formed into a film by inflation molding to obtain a polyethylene film having a thickness of 100 µm.
This polyethylene film was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a film having a thickness of 20 μm.

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

A 20 nm thick aluminum vapor deposition film was formed on the other side of the film using the PVD method, yielding the substrate of the present invention.

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

Example 2
Medium-density polyethylene (density: 0.941 g/cm, melting point: 129°C, MFR: 1.3 g/10 min, manufactured by Dow Chemical, trade name: Elite 5538G) was formed into a film by inflation molding to obtain a polyethylene film having a thickness of 100 µm.
This polyethylene film was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a film having a thickness of 20 μm.

A 20 nm thick aluminum vapor deposition film was formed on one side of the polyethylene film obtained in this way using the PVD method to create an intermediate layer.

The above adhesive was applied to the vapor-deposited film surface of the intermediate layer, and the image-forming surface of the substrate prepared in Example 1 was laminated thereon.

The above adhesive was applied to the surface of the intermediate layer without the vapor-deposited film, and the above LLDPE film with a thickness of 40 μm was laminated onto it to obtain the laminate of the present invention.

Example 3
High-density polyethylene (density: 0.961 g/cm ³ , melting point: 135°C, MFR: 0.7 g/10 min, ExxonMobil, product name: HTA108) and the above medium-density polyethylene were formed into a polyethylene film consisting of a high-density polyethylene layer/a medium-density polyethylene layer/a high-density polyethylene layer by inflation molding. The high-density polyethylene layer had a thickness of 20 μm, and the medium-density polyethylene layer had a thickness of 60 μm.
This polyethylene film was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a film with a total thickness of 20 μm, with the high-density polyethylene layer being 4 μm thick and the medium-density polyethylene layer being 12 μm thick.
The obtained film was irradiated with an electron beam under the same conditions as in Example 1, and a 20 nm thick aluminum vapor deposition film was formed on the other surface of the film by a PVD method, thereby preparing a substrate.
A laminate of the present invention was obtained in the same manner as in Example 1, except that the substrate prepared by the above method was used.

Comparative Example 1
The medium density polyethylene was formed into a film by inflation molding to obtain a polyethylene film having a thickness of 20 μm.

A 20 nm thick aluminum vapor deposition film was formed on the other side of the film using the PVD method, yielding a vapor deposition film.

A laminate was prepared in the same manner as in Example 1, except that the vapor-deposited film prepared as described above was used instead of the substrate.

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 and then a vapor-deposited film was formed.

Comparative Example 3
The medium density polyethylene was formed into a film by inflation molding to obtain a polyethylene film having a thickness of 100 μm.
This polyethylene film was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a polyethylene film having a thickness of 20 μm.

A 20 nm thick aluminum vapor deposition film was formed on one side of the film using the PVD method, yielding a vapor deposition film.

A laminate was prepared in the same manner as in Example 1, except that the vapor-deposited film prepared as described above was used instead of the substrate.

Comparative Example 4
A laminate was obtained in the same manner as in Example 1, except that the substrate was a biaxially stretched polyester film (manufactured by Toyobo Co., Ltd., product name: E5100) having a 12 μm thick aluminum vapor-deposited film on one side and a thickness of 20 nm.

<<Recyclability evaluation>>
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)
Good: The polyethylene content in the laminate was 90% by mass or more.
x: The polyethylene content in the laminate was less than 90% by mass.

<<Strength evaluation>>
The laminates produced in the above Examples and Comparative Examples were measured for strength when pierced with a needle having a diameter of 0.5 mm using a tensile tester (manufactured by Orientec Co., Ltd., product name: RTC-1310A). The piercing speed was set to 50 mm/min. The measurement results are summarized in Table 1.

<<Heat resistance evaluation>>
Two test pieces each measuring 80 mm long x 80 mm wide were prepared from the laminates obtained in the above Examples and Comparative Examples.
Two test pieces were placed together with the heat seal layers facing each other, and three sides were heat sealed at 150° C. to prepare a small pouch-shaped packaging material.
The produced packaging materials were visually observed, and the heat resistance of the laminates was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
(Evaluation criteria)
Good: No wrinkles or the like were observed on the surface of the packaging material, and no adhesion to the heat seal bar was observed.
x: Wrinkles or the like were observed on the surface of the packaging material, and adhesion to the heat seal bar was observed, making it impossible to form a bag.

<<Oxygen Barrier Property Evaluation>>
The laminates obtained in the above Examples and Comparative Examples were cut to A4 size, and their oxygen permeability (cc/ ^m2 /day/atm) was measured at 23°C and 90% relative humidity using an OXTRAN2/20 manufactured by MOCON Corporation, USA. The measurement results are summarized in Table 1.

<<Water vapor barrier property evaluation>>
The laminates obtained in the above Examples and Comparative Examples were cut to A4 size, and the water vapor permeability (g/ ^m2 /day/atm) was measured using a PERMATRAN 3/31 manufactured by MOCON Corporation in the United States under an environment of 40°C and a relative humidity of 90%. The measurement results are summarized in Table 1.

<<Heat sealability test>>
The laminates obtained in the above Examples and Comparative Examples were cut into 10 cm x 10 cm samples, which were then folded in half with the heat seal layer facing inward, and the 1 cm x 10 cm area was heat sealed at 140°C ^under a pressure of 1 kgf/cm for 1 second.
The heat-sealed sample piece was cut into 15 mm wide strips, and both ends that were not heat-sealed were held in a tensile tester to measure the peel strength (N/15 mm) at a speed of 300 mm/min and a load range of 50 N. The measurement results are summarized in Table 1.
The laminate obtained in Comparative Example 1 adhered to the heat seal bar, making it impossible to measure the peel strength, and was therefore marked "-".

10: Substrate, 11: Polyethylene film, 12: Vapor-deposited film, 13: Laminate, 14: Heat-seal layer, 15: Intermediate layer, 16: Adhesive layer

Claims (9)

A substrate;
A laminate comprising at least a heat seal layer,
the substrate is a film made of polyethylene having a density of 0.935 g/cm ³ or more and 0.950 g/cm ³ or less,
The substrate is subjected to a stretching treatment,
One surface of the substrate has been subjected to electron beam irradiation treatment,
a vapor-deposited film is provided on the other surface of the substrate;
The substrate does not have a multilayer structure,
the substrate is provided so that the electron beam irradiated surface of the substrate is the outermost surface and the surface of the substrate on which the vapor-deposited film is formed is the heat seal layer side;
The heat seal layer is made of polyethylene,
A recyclable laminate, characterized in that the polyethylene content in the entire laminate is 90 mass % or more. The recyclable laminate according to claim 1, wherein the thickness of the substrate is 10 μm or more and 50 μm or less. The recyclable laminate according to claim 1 or 2, wherein the stretching ratio in the longitudinal and/or transverse directions of the substrate is 2 to 10 times. The recyclable laminate according to any one of claims 1 to 3, wherein the density of the polyethylene in the film before electron beam irradiation is 0.935 g/cm ³ or more and 0.950 g/cm ³ or less. The recyclable laminate according to any one of claims 1 to 4, wherein the thickness of the vapor-deposited film is 1 nm or more and 150 nm or less. The recyclable laminate according to any one of claims 1 to 5, used as a packaging material. A packaging material comprising the recyclable laminate described in any one of claims 1 to 6. A packaging bag,
A recyclable laminate according to any one of claims 1 to 6,
A packaging bag characterized in that the thickness of the heat seal layer is 20 μm or more and 60 μm or less. A stand-up pouch,
A recyclable laminate according to any one of claims 1 to 6,
A stand-up pouch characterized in that the heat seal layer has a thickness of 50 μm or more and 200 μm or less.