Packaging material

Abstract

To provide a packaging material having sufficient strength while being excellent in recyclability.SOLUTION: A packaging material is constituted of a laminate comprising a base material and a heat seal layer. The base material and the heat seal later are constituted of the same material, with the base material having been subjected to stretching treatment and at least one surface of the base material having been subjected to electron beam irradiation treatment. The same material is polyethylene, and the base material is arranged so that the surface of the base material subjected to electron beam irradiation becomes the outermost surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to packaging materials. [Background technology]

[0002] Conventionally, resin films made of resin materials have been used as materials for forming packaging materials. For example, resin films made of polyolefins have suitable flexibility and transparency, as well as excellent heat-sealing properties, and are therefore widely used as packaging materials.

[0003] Normally, resin films made of polyolefins cannot be used as a base material for packaging materials because they are inferior in strength and heat resistance, and are therefore used by laminating them with resin films made of polyester, polyamide, etc. Therefore, ordinary packaging materials are made up of a laminate in which the base material and the heat seal layer are made of different types of resin materials (for example, Patent Document 1).

[0004] In recent years, with the growing demand for the creation of a recycling-oriented society, high recyclability is being demanded of packaging materials. However, as mentioned above, conventional packaging materials are composed of different resin materials, and because it is difficult to separate each resin material, they are not currently recycled. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-202519 Summary of the Invention [Problem to be solved by the invention]

[0006] 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. 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.

[0007] The present invention has been made in light of the above findings, and the problem to be solved by the present invention is to provide a packaging material that has sufficient strength and is also highly recyclable. [Means for solving the problem]

[0008] The packaging material of the present invention comprises: It is composed of a laminate including a substrate and a heat seal layer, The substrate and the heat seal layer are made of the same material, The substrate is subjected to a stretching treatment, At least one surface of the substrate has been subjected to electron beam irradiation treatment; The same material is polyethylene, The substrate is characterized in that the surface of the substrate that is irradiated with the electron beam is the outermost surface.

[0009] In one embodiment, the thickness of the substrate is 10 μm or more and 50 μm or less.

[0010] In one embodiment, the stretching ratio of the substrate in the longitudinal direction and / or transverse direction is 2 times or more and 10 times or less.

[0011] In one embodiment, the density of the polyethylene contained in the substrate before electron beam irradiation is 0.935 g / cm 3 More than 0.957g / cm 3 The following is the result.

[0012] In one embodiment, the thickness of the heat seal layer is 20 μm or more and 60 μm or less, and the packaging material has a shape of a packaging bag.

[0013] In one embodiment, the thickness of the heat seal layer is 50 μm or more and 200 μm or less, and the packaging material has a stand-up pouch shape. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a packaging material that has sufficient strength and is also highly recyclable. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view illustrating one embodiment of a packaging material of the present invention. [Figure 2] 1 is a perspective view illustrating one embodiment of a packaging material of the present invention. [Figure 3] 1 is a cross-sectional schematic view showing one embodiment of a laminate constituting a packaging material of the present invention. [Figure 4] 1 is a cross-sectional schematic view showing one embodiment of a laminate constituting a packaging material of the present invention. [Figure 5] 1 is a cross-sectional schematic view showing one embodiment of a laminate constituting a packaging material of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] (packaging material) The packaging material of the present invention is characterized by being composed of a laminate having a substrate and a heat seal layer, both of which are made of polyethylene. The packaging material of the present invention has such a structure, and therefore the recyclability of the packaging material can be significantly improved.

[0017] 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.

[0018] In one embodiment, the bag-shaped packaging material can be produced by folding the laminate in half, overlapping it, and heat-sealing the edges so that the heat-sealable layer is on the inside. 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 edges.

[0019] The heat sealing method is not particularly limited, and can be performed by any known method such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, or ultrasonic sealing.

[0020] In one embodiment, the packaging material has a shape like a stand-up pouch having a body and a bottom, as shown in FIG.

[0021] A stand-up pouch-shaped packaging material can be produced by heat-sealing the laminate into a cylindrical shape with the heat-seal layer facing inward to form a body, and then folding another laminate into a V-shape with the heat-seal layer facing inward, sandwiching it from one end of the body, and heat-sealing it to form a bottom.

[0022] The contents filled in 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.

[0023] (Laminate) The laminate 10 used to prepare the packaging material of the present invention comprises a substrate 11 and a heat seal layer 12, as shown in FIG.

[0024] In one embodiment, the laminate 11 includes an intermediate layer 13 between the substrate 10 and the heat seal layer 12, as shown in FIG.

[0025] In one embodiment, the laminate may include adhesive layers 14 between any of the layers, as shown in FIGS.

[0026] The content of polyethylene in the entire laminate is preferably 90% by mass or more, and more preferably 90% by mass or more. By making the polyethylene content in the entire laminate 90% by mass or more, the recyclability of the laminate can be improved.

[0027] Each layer constituting the laminate will now be described.

[0028] (base material) The substrate is a film made of polyethylene, which has been stretched and at least one surface of which has been irradiated with electron beams. 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.

[0029] 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.

[0030] In the present invention, the high density polyethylene has a density of 0.945 g / cm 3 The polyethylene having a density of 0.925 g / cm or more can be used. 3 More than 0.945g / cm 3 Low density polyethylene can be used, and low density polyethylene is polyethylene with a density of 0.900 g / cm3 More than 0.925g / cm 3 Polyethylenes with a density of less than 0.900 g / cm can be used, and linear low-density polyethylenes with a density of less than 0.900 g / cm can be used. 3 More than 0.925g / cm 3 Polyethylene with a density of less than 0.900 g / cm can be used, and ultra-low density polyethylene has a density of 0.900 g / cm 3 Less than 100% polyethylene can be used. In the present invention, the density is 0.935 g / cm 3 More than 0.950g / cm 3 It is preferable to use the following polyethylene: 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.

[0031] The polyethylenes with different densities and branching as described above can be obtained by appropriately selecting a polymerization method. For example, it is preferable to use a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as the polymerization catalyst, and to carry out the polymerization in one stage or in two or more stages by any of gas phase polymerization, slurry polymerization, solution polymerization, and high pressure ionic polymerization.

[0032] The single-site catalyst is a catalyst capable of forming a uniform active species, and is usually prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activating co-catalyst. Single-site catalysts are preferred because they have a more uniform active site structure than multi-site catalysts, making it possible to polymerize polymers with high molecular weights and highly uniform structures. Metallocene catalysts are particularly preferred as single-site catalysts. Metallocene catalysts are catalysts containing the following catalytic components: a transition metal compound of Group IV of the periodic table containing a ligand with a cyclopentadienyl skeleton, a co-catalyst, and optionally an organometallic compound and a carrier.

[0033] In the above-mentioned transition metal compound 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 be bonded to each other to form a ring, such as an indenyl ring, a fluorenyl ring, an azulenyl ring, or a hydrogenated product thereof. The rings formed by bonding the substituents to each other may further have substituents.

[0034] 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, etc., 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.

[0035] The co-catalyst refers to a catalyst that can effectively use the above-mentioned transition metal compound 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 the co-catalyst 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.

[0036] The transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton may be supported on an inorganic or organic support. The support is preferably a porous oxide of an inorganic or organic compound, and specific examples include ion-exchange layered silicates such as montmorillonite, SiO2, Al2O3, MgO, ZrO2, TiO2, BO3, CaO, ZnO, BaO, ThO2, 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.

[0037] Copolymers of ethylene and other monomers can also be used as long as the properties of the present invention are not impaired. 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 can also be used as long as the properties of the present invention are not impaired.

[0038] Furthermore, in the present invention, biomass-derived ethylene may be used as a 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 produced using laminates including 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 (e.g., Green PE available from Braskem) may be used.

[0039] It is also possible to use polyethylene recycled through mechanical recycling, which generally involves crushing collected polyethylene film and washing it with an alkali to remove dirt and foreign matter from the film surface, and then drying it at high temperature and reduced pressure for a certain period of time to diffuse any contaminants remaining inside the film, thereby decontaminating it and removing the dirt from the polyethylene film and returning it to polyethylene.

[0040] The substrate may contain additives within the range that does not impair the properties of the present invention, such as crosslinking agents, antioxidants, antiblocking agents, slip agents, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0041] In one embodiment, the substrate has a multi-layer structure. In one embodiment, the substrate comprises a layer made of high-density polyethylene (hereinafter referred to as high-density polyethylene layer), a layer made of medium-density polyethylene (hereinafter referred to as medium-density polyethylene layer), and a layer made 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.

[0042] 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 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 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.

[0043] 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 from the viewpoint of the breaking limit of the substrate, it is preferably 10 times or less. 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 from the viewpoint of the breaking limit of the substrate, it is preferably 10 times or less.

[0044] As shown in Figures 3 and 4, the substrate 10 may have polyethylene on one side whose crosslink density has been improved by electron beam irradiation, or as shown in Figure 5, the substrate 10 may have polyethylene whose crosslink density has been improved throughout its entirety. 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.

[0045] As an apparatus that can be used to irradiate a substrate with an electron beam, a conventionally known apparatus can be used, and for example, a curtain-type electron beam irradiation apparatus (LB1023, manufactured by i-Electron Beam Co., Ltd.), a line-type low-energy electron beam irradiation apparatus (EB-ENGINE, manufactured by Hamamatsu Photonics K.K.), and a drum-roll-type electron beam irradiation apparatus (EZ-CURE, manufactured by i-Electron Beam Co., Ltd.) can be suitably used.

[0046] 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. Furthermore, the irradiation energy of the electron beam is preferably in the range of 20 keV or more and 750 keV or less, more preferably in the range of 25 keV or more and 500 keV or less, even more preferably in the range of 30 keV or more and 400 keV or less, and particularly preferably in the range of 20 keV or more and 200 keV or less.

[0047] The oxygen concentration in the electron beam irradiation apparatus is preferably 500 ppm or less, more preferably 100 ppm or less. By performing electron beam irradiation under such conditions, it is possible to suppress the generation of ozone and also to prevent the radicals generated by electron beam irradiation from being deactivated by oxygen in the atmosphere. Such conditions can be achieved, for example, by creating an inert gas (nitrogen, argon, etc.) atmosphere inside the apparatus.

[0048] In one embodiment, the electron beam irradiation can be performed simultaneously with cooling using a cooling drum or the like.

[0049] 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 surface treatment method 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.

[0050] The substrate may have an image formed on its surface. The image to be formed is not particularly limited, and may represent letters, patterns, symbols, or combinations thereof. Preferably, the image is formed on the substrate using ink derived from biomass, which allows the substrate to be used to produce packaging materials with a lower environmental impact. 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.

[0051] In one embodiment, the substrate may have a vapor-deposited film on its surface, on the side on which the heat seal layer is laminated, thereby improving the gas barrier properties, specifically the oxygen barrier properties and water vapor barrier properties, of the substrate.

[0052] Examples of the vapor-deposited film include vapor-deposited films 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.

[0053] 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 is applied to the laminate described below, its recyclability can be maintained.

[0054] In one embodiment, the substrate comprises a barrier coat layer, which can improve the oxygen barrier property and water vapor barrier property of the substrate. When the substrate has a vapor-deposited film, the barrier coat layer may be provided on or under the vapor-deposited film.

[0055] 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.

[0056] 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 can be further improved.

[0057] The barrier coat layer may contain the above-mentioned additives to the extent that the properties of the present invention are not impaired.

[0058] 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 can be further improved, and by making the thickness of the barrier coat layer 10 μm or less, the recyclability of the substrate can be maintained when it is applied to the laminate described below.

[0059] The barrier coat layer can be formed by dissolving or dispersing the above-mentioned material in water or an appropriate solvent, applying the solution, and drying. Alternatively, the barrier coat layer can be formed by applying a commercially available barrier coating agent and drying it.

[0060] 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 hydrolyzed 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 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.

[0061] In one embodiment, the metal alkoxide is represented by the following general formula: R 1 nM(OR 2 )m (wherein, R 1 , R 2 each represents an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the valence of M.

[0062] As the metal atom M, for example, silicon, zirconium, titanium, aluminum, etc. can be used. Also, R 1 and R 2 Examples of the organic group represented by the formula (I) 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.

[0063] 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).

[0064] 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 having epoxy groups are particularly preferred. Examples of organoalkoxysilanes having epoxy groups include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0065] Two or more of the above silane coupling agents may be used, and the silane coupling agent is preferably used in an amount of about 1 to 20 parts by mass per 100 parts by mass of the total amount of the alkoxides.

[0066] As the water-soluble polymer, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are preferred, and from the viewpoints of oxygen barrier property, water vapor barrier property, water resistance and weather resistance, it is preferred to use these in combination.

[0067] 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 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.

[0068] The thickness of the gas barrier coating film is preferably from 0.01 μm to 100 μm, and more preferably from 0.1 μm to 50 μm, which allows for improved oxygen barrier properties and water vapor barrier properties 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 can be improved, and 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.

[0069] 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, tripentylamine, etc. 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 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 metal alkoxide, the thickness of the gas barrier coating film formed can be made uniform.

[0070] 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, and the like. The acid may be a mineral acid such as sulfuric acid, hydrochloric acid, or nitric acid, or an organic acid such as acetic acid or tartaric acid. 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. Also, 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.

[0071] 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 moles or more per mole of the total alkoxide amount, the oxygen barrier property and water vapor barrier property of the laminate can be improved, and by adjusting the water content to 100 moles or more per mole of the total alkoxide amount, the hydrolysis reaction can be carried out quickly.

[0072] The composition may also contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butanol.

[0073] 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.

[0074] The barrier coat layer may have an image formed on its surface, and the method for forming the image is as described above.

[0075] 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, and by making the thickness of the substrate 50 μm or less, the processability of the substrate can be improved.

[0076] 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.

[0077] When the substrate is produced by 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 3 g / 10 min or more, the processability of the substrate 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.

[0078] 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 setting the MFR of the resin composition to 0.5 g / 10 min or more, the processability of the substrate can be improved, and by setting the MFR of the resin composition to 5 g / 10 min or less, the film-forming properties can be improved.

[0079] The deposition film can be formed on the substrate using a conventionally known method, for example, physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0080] Also, 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 deposition chamber is 10 -2 ~10 -8 After oxygen is introduced, the pressure is preferably about 10 -1 ~10 -6 A pressure of about mbar is preferred. The amount of oxygen introduced varies depending on the size of the deposition machine. An inert gas such as argon gas, helium gas, or nitrogen gas may be used as a carrier gas for the oxygen introduced, provided that this does not cause any problems. The film transport speed can be about 10 to 800 m / min.

[0081] The surface of the vapor-deposited film is preferably subjected to the above-mentioned surface treatment, which can improve adhesion to adjacent layers when applied to the laminate described below.

[0082] (heat seal layer) The heat seal layer is characterized by being made of polyethylene. By having the laminate composed of a base material and a heat seal layer made of polyethylene, the recyclability of packaging materials 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.

[0083] 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.

[0084] In one embodiment, the heat seal layer has a multi-layer structure and includes, as an intermediate layer, a layer containing at least one of medium density polyethylene and high density polyethylene. Specifically, the laminate may be configured as follows: a layer containing at least one of low-density polyethylene, linear low-density polyethylene, and very 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 very low-density polyethylene. By adopting the above-mentioned configuration, the bag-making suitability and strength of the laminate of the present invention can be further improved while maintaining heat sealability.

[0085] 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. For example, when producing a packaging bag as shown in FIG. 1 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 heat seal layer 20 μm or thicker, it is possible to prevent leakage of the filled contents due to damage to the heat seal layer, and by making the heat seal layer 60 μm or thicker, it is possible to improve the processability of the laminate.

[0086] Furthermore, for example, when producing a stand pouch as shown in FIG. 2 to be filled with contents 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. The hatched areas in FIGS. 1 and 2 are heat-sealed portions.

[0087] The heat seal layer may have a vapor-deposited film on the surface facing the substrate, which can improve the oxygen barrier property and water vapor barrier property.

[0088] Examples of the vapor-deposited film include vapor-deposited films 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.

[0089] 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.

[0090] The method for forming the vapor-deposited film is as described above.

[0091] The surface of the deposited film is preferably subjected to the above-mentioned surface treatment, which can improve adhesion to adjacent layers.

[0092] (middle class) In one embodiment, the intermediate layer comprises an oriented polyethylene film, which can provide additional strength to the laminate. 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.

[0093] The stretched polyethylene film may also have the above-mentioned multilayer structure.

[0094] The stretched polyethylene film may be a uniaxially stretched film or a biaxially stretched film, and the preferred stretching ratio is as described above.

[0095] 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.

[0096] In one embodiment, the intermediate layer includes a gas barrier layer made of a gas barrier resin. By including such an intermediate layer in the laminate, it is possible to improve the oxygen barrier property and water vapor barrier property. 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.

[0097] 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 making the thickness of the gas barrier layer 0.01 μm or more, the oxygen barrier property and water vapor barrier property of the laminate can be further improved, and by making the thickness of the gas barrier layer 10 μm or less, the recyclability of the laminate can be maintained.

[0098] In one embodiment, the intermediate layer comprises a vapor-deposited film. The form, preferred thickness, and formation method of the vapor-deposited film that can be used are as described above.

[0099] In one embodiment, the intermediate layer comprises a barrier coating layer, the configuration, preferred thickness, forming method, etc. of which are as described above.

[0100] (adhesive layer) The laminate may have an adhesive layer between any of the layers, thereby improving the adhesion between the layers.

[0101] 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.

[0102] 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. 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.

[0103] The polyester polyol has two or more hydroxyl groups as functional groups in one molecule. The isocyanate compound has two or more isocyanate groups as functional groups in one molecule. The polyester polyol has, for example, a polyester structure or a polyester polyurethane structure as the main skeleton.

[0104] As a specific example of a resin composition (adhesive) containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound, the PASLIM series sold by DIC Corporation can be used.

[0105] The resin composition may further contain a plate-like inorganic compound, a coupling agent, cyclodextrin and / or a derivative thereof, and the like.

[0106] As polyester polyols 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 with a glycerol skeleton [Example 3] Polyester polyol with isocyanuric ring Each polyester polyol will be described below.

[0107] The polyester polyol according to the first example is a polycondensate obtained by polycondensing a polycarboxylic acid component containing at least one or more of orthophthalic acid and its anhydride, 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 mass % are preferred.

[0108] 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.

[0109] As a polyester polyol according to a 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 H (hydrogen atom) or a group represented by the following general formula (2). [ka]

[0110] In formula (2), n represents an integer of 1 to 5, X represents an arylene group selected from the group consisting of 1,2-phenylene groups, 1,2-naphthylene groups, 2,3-naphthylene groups, 2,3-anthraquinonediyl groups, and 2,3-anthracenediyl groups, which may have a substituent, 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).

[0111] 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).

[0112] In addition, the compound may be a mixture of two or more of the following compounds: a compound in which any one of R1, R2, and R3 is a group represented by general formula (2); a compound in which any two of R1, R2, and R3 are groups represented by general formula (2); and a compound in which all of R1, R2, and R3 are groups represented by general formula (2).

[0113] X represents an optionally substituted 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. 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. The substituent includes 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.

[0114] In general formula (2), 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. Of these, a propylene group or an ethylene group is preferred, and an ethylene group is most preferred.

[0115] 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.

[0116] 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.

[0117] Examples of polyhydric alcohol components include alkylene diols 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, and dimethylbutanediol.

[0118] The polyester polyol according to the third example is a polyester polyol having an isocyanuric ring represented by the following general formula (3). [ka] In the general formula (3), R1, R2, and R3 each independently represent "-(CH2) n1 -OH (where n1 represents an integer of 2 to 4)" or a structure of general formula (4). [ka]

[0119] 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. However, at least one of R1, R2, and R3 is a group represented by general formula (4).

[0120] In the general formula (3), -(CH2) n1 The alkylene group represented by - may be linear or branched. Among these, n1 is preferably 2 or 3, and most preferably 2.

[0121] 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.

[0122] 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. The substituent includes 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.

[0123] 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. Of these, a propylene group or an ethylene group is preferred, and an ethylene group is most preferred.

[0124] 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).

[0125] In addition, the compound may be a mixture of two or more of the following compounds: a compound in which any one of R1, R2, and R3 is a group represented by general formula (4); a compound in which any two of R1, R2, and R3 are groups represented by general formula (4); and a compound in which all of R1, R2, and R3 are groups represented by general formula (4).

[0126] 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 a carboxylic acid is substituted at the ortho position, and a polyhydric alcohol component as essential components.

[0127] 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.

[0128] 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-anthracene carboxylic acid or anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring.

[0129] 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.

[0130] 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 preferred because of their excellent oxygen barrier properties and adhesiveness.

[0131] The isocyanuric ring is highly polar and trifunctional, and can increase the polarity of the entire system and the crosslink density. From these perspectives, it is preferable that the adhesive resin contains 5% by mass or more of the isocyanuric ring based on the total solid content of the adhesive resin.

[0132] 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.

[0133] 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.

[0134] The phosphoric acid-modified compound is, for example, a compound represented by the following general formula (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, 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. [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, 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.

[0135] More specific 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.

[0136] 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 setting 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 can be improved, and by setting the content of the phosphate-modified compound to 10% by mass or less, the adhesiveness of the adhesive layer can be improved.

[0137] 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. 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.).

[0138] Examples of coupling agents include silane-based coupling agents, titanium-based coupling agents, and aluminum-based coupling agents represented by the following general formula (7). These coupling agents may be used alone or in combination of two or more. [ka]

[0139] 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( N-beta(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-beta(aminoethyl)γ-aminopropyltrimethoxysilane, N-beta(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).

[0140] 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.

[0141] 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.

[0142] The resin composition may contain cyclodextrin and / or a derivative thereof, which can improve the adhesiveness of the adhesive layer and the bending load resistance of the laminate. 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. Furthermore, the cyclodextrin skeleton in 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.

[0143] From the viewpoint of compatibility and dispersibility in the resin composition, it is preferable to use a cyclodextrin derivative as the cyclodextrin compound.

[0144] 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.

[0145] Examples of acetylated cyclodextrins include monoacetyl-α-cyclodextrin, monoacetyl-β-cyclodextrin, and monoacetyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

[0146] 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.

[0147] 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.

[0148] The adhesive layer can be formed by applying the adhesive to a substrate or the like and drying it using a conventionally known method such as direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine method, and transfer roll coating. [Example]

[0149] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0150] Example 1 Medium density polyethylene (density: 0.941 g / cm 3 A polyethylene film having a thickness of 100 μm was formed from a polyethylene glycol terephthalate (e.g., melting point 129° C., MFR: 1.3 g / 10 min, manufactured by Dow Chemical Co., trade name: Elite 5538G) by inflation molding. This polyethylene film was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a film with a thickness of 20 μm.

[0151] 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 to obtain a substrate. Voltage: 100kV Irradiation dose: 280kGy Oxygen concentration inside the device: 100 ppm or less Line speed: 25m / min

[0152] On the surface of the substrate opposite to the surface that had been irradiated with electron beams, an image was formed by gravure printing using oil-based gravure ink (manufactured by DIC Graphics Corporation, trade name: Finart).

[0153] A 40 μm thick unstretched linear low-density polyethylene film (manufactured by Mitsui Chemicals Tohcello Co., Ltd., product 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., product name: RU-77T / H-7) to obtain a laminate. The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.

[0154] Example 2 A laminate was produced in the same manner as in Example 1, except that an aluminum vapor deposition film having a thickness of 20 nm was formed by PVD on the substrate lamination surface of the LLDPE film.

[0155] Example 3 Medium density polyethylene (density: 0.941 g / cm 3 A polyethylene film having a thickness of 100 μm was formed from a polyethylene glycol terephthalate (e.g., melting point 129° C., MFR: 1.3 g / 10 min, manufactured by Dow Chemical Co., trade name: Elite 5538G) by inflation molding. This polyethylene film was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a film with a thickness of 20 μm.

[0156] An aluminum vapor deposition film having a thickness of 20 nm was formed by PVD on one surface of the polyethylene film thus obtained to prepare an intermediate layer.

[0157] The adhesive was applied to the surface of the intermediate layer on which the vapor-deposited film was formed, and the image-forming surface of the substrate prepared in Example 1 was laminated thereon.

[0158] The adhesive was applied to the surface of the intermediate layer on which the vapor-deposited film was not formed, and the LLDPE film having a thickness of 40 μm was laminated thereon to obtain a laminate.

[0159] Example 4 High density polyethylene (density: 0.961 g / cm 3 A polyethylene film consisting of a high-density polyethylene layer / medium-density polyethylene layer / high-density polyethylene layer was produced by inflation molding using a polyethylene polyethylene copolymer (HTA108, melting point 135°C, MFR 0.7g / 10min, manufactured by ExxonMobil) and the above medium-density polyethylene. The high-density polyethylene layers were each 20µm thick, and the medium-density polyethylene layer was 60µm thick. 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 to obtain a substrate.

[0160] A laminate was produced in the same manner as in Example 1, except that the substrate was changed to the one produced as described above.

[0161] 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 laminate was produced in the same manner as in Example 1, except that the substrate was changed to the polyethylene film.

[0162] Comparative Example 2 A laminate was produced in the same manner as in Comparative Example 1, except that one surface of the polyethylene film produced in Comparative Example 1 was irradiated with an electron beam in the same manner as in Example 1.

[0163] 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 with a thickness of 20 μm. A laminate was produced in the same manner as in Example 1, except that the substrate was changed to the polyethylene film.

[0164] 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 having a thickness of 12 μm (manufactured by Toyobo Co., Ltd., trade name: E5100).

[0165] <<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) ◯: The polyethylene content in the laminate was 90% by mass or more. ×: The polyethylene content in the laminate was less than 90% by mass.

[0166] <<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.

[0167] <<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-sealable 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) ⊚: No wrinkles or the like were observed on the surface of the packaging material, and no adhesion to the heat seal bar was observed. ◯: Some wrinkles were observed on the surface of the packaging material, and some adhesion to the heat seal bar was observed, but this was not a problem for practical use. ×: 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 make a bag.

[0168] <<Oxygen barrier evaluation>> The laminates obtained in the above Examples and Comparative Examples were cut into A4 size pieces, and the oxygen permeability (cc / m) was measured using OXTRAN 2 / 20 manufactured by MOCON, USA, at 23°C and a relative humidity of 90%. 2 The measurement results are summarized in Table 1. The upper limit of measurement is 200cc / m 2 For amounts exceeding / day / atm, a "-" is displayed.

[0169] <<Water vapor barrier property evaluation>> The laminates obtained in the above Examples and Comparative Examples were cut into A4 size pieces, and the water vapor permeability (g / m) was measured using a PERMATRAN 3 / 31 manufactured by MOCON, USA, under an environment of 40°C and a relative humidity of 90%. 2 The measurement results are summarized in Table 1.

[0170] <<Heat sealability test>> The laminates obtained in the above Examples and Comparative Examples were cut into 10 cm x 10 cm samples. These samples were folded in half with the heat seal layer facing inward, and then heated to 140°C and a pressure of 1 kgf / cm. 2 An area of ​​1 cm x 10 cm was heat-sealed under the conditions of 1 second, 1 minute, 1 minute. The heat-sealed sample pieces were cut into 15 mm wide strips, and both ends that were not heat-sealed were clamped 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 "-". [Table 1] [Explanation of symbols]

[0171] 10: laminate, 11: substrate, 12: heat seal layer, 13: intermediate layer, 14: adhesive layer

Claims

1. A packaging material comprising a laminate comprising a base material and a heat-seal layer, The base material and the heat seal layer are made of polyethylene. The substrate has a multilayer structure comprising at least a layer made of high-density polyethylene with a density of 0.945 g / cm³ or more, and a layer made of medium-density polyethylene with a density of 0.925 g / cm³ or more and less than 0.945 g / cm³. The aforementioned substrate has been subjected to a stretching treatment. At least one surface of the substrate is subjected to electron beam irradiation treatment. A packaging material characterized in that the substrate is provided such that the electron beam irradiation surface of the substrate is the outermost surface.

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

3. The packaging material according to claim 1, wherein the stretch ratio in the longitudinal and / or transverse direction of the base material is 2 times or more and 10 times or less.

4. The thickness of the heat seal layer is 20 μm or more and 60 μm or less. The packaging material according to claim 1, having the shape of a packaging bag.

5. The thickness of the heat seal layer is 50 μm or more and 200 μm or less. The packaging material according to claim 1, having a stand-up pouch shape.

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