Laminate and package

Abstract

To provide a laminate that makes it possible to prepare a packaging bag or the like having excellent recyclability while maintaining heat sealability.SOLUTION: A laminate has a base material and a heat seal layer, and the base material is composed of polyester.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a laminate used in the manufacture of packaging and the like. Furthermore, this invention relates to a packaging comprising the laminate.

[0002] Traditionally, resin films made from resin materials have been used as the material for packaging. For example, polyester film is widely used because it has excellent mechanical properties, chemical stability, heat resistance, and transparency, as well as being inexpensive.

[0003] Typically, polyester film is laminated with heat-sealable polyolefin film or gas-barrier polyamide film to form a laminate, and packaging is manufactured by heat-sealing the polyolefin films within the laminate.

[0004] In recent years, with the growing demand for a circular economy, there is a growing need for high recyclability in packaging materials. However, conventional packaging bags, as mentioned above, are composed of different types of resin materials, making it difficult to separate them, and as a result, they are not currently recycled. [Overview of the project] [Problems that the invention aims to solve]

[0005] This invention has been made in view of the above-mentioned problems, and the problem it aims to solve is to provide a laminate that enables the production of packaging bags and the like that have excellent recyclability while maintaining heat-sealability. Furthermore, the problem that the present invention aims to solve is to provide a packaging body comprising the laminate. [Means for solving the problem]

[0006] The laminate of the present invention comprises a base material and a heat-seal layer, characterized in that the base material is made of polyester.

[0007] In one embodiment, the ratio of the thickness of the substrate to the total thickness of the laminate is 60% or more.

[0008] In one embodiment, the heat seal layer includes a polyester-based heat sealant.

[0009] In one embodiment, the substrate comprises a vapor-deposited film.

[0010] In one embodiment, the laminate of the present invention comprises an intermediate layer between the substrate and the heat-seal layer, The intermediate layer is made of the same material as the base material. That same material is polyester.

[0011] In one embodiment, the polyester content in the entire laminate is 60% by mass or more.

[0012] In one embodiment, the laminate of the present invention is used for packaging applications.

[0013] The packaging of the present invention is characterized by comprising the above-mentioned laminate. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a laminate that enables the production of packaging bags and the like that have excellent recyclability while maintaining heat-sealability. Furthermore, according to the present invention, a packaging body comprising this laminate can be provided. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 2] This is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 3] This is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 4]It is a front view showing an embodiment of a package including the laminate of the present invention. [Figure 5] It is a perspective view showing an embodiment of a package including the laminate of the present invention.

Embodiments for Carrying out the Invention

[0016] (Laminate) [[ID=]13]As shown in FIG. 1, the laminate 10 of the present invention is characterized by including a base material 11 and a heat-sealing layer 12. In one embodiment, as shown in FIG. 2, the base material 11 includes a vapor deposition film 13. Also, in one embodiment, as shown in FIG. 3, the laminate 10 of the present invention includes an intermediate layer 14 between the base material 11 and the heat-sealing layer 12. Further, in one embodiment, as shown in FIG. 4, the laminate 10 of the present invention includes an adhesive layer between the base material 11 and the intermediate layer 14, as shown in FIG. 3. Note that the laminate 10 of the present invention may include two or more intermediate layers 14.

[0017] The ratio of the thickness of the base material to the thickness of the entire laminate of the present invention is preferably 60% or more, and more preferably 70% or more. By setting the ratio of the thickness of the base material to the thickness of the entire laminate of the present invention to 60% or more, the recyclability of the laminate of the present invention can be improved.

[0018] The content of polyester in the entire laminate of the present invention is preferably 60% by mass or more, and more preferably 70% by mass or more. By setting the content of polyester in the entire laminate of the present invention to 60% by mass or more, the recyclability of the laminate of the present invention can be improved.

[0019] Hereinafter, each layer included in the laminate of the present invention will be described.

[0020] (Base Material) The substrate constituting the laminate of the present invention is characterized by being made of polyester. In this invention, polyester means a copolymer of a dicarboxylic acid compound and a diol compound. Examples of dicarboxylic acid compounds include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedionic acid, eicosanedionic acid, pimelic acid, azelaic acid, methylmalonic acid and ethylmalonic acid, adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodium sulfisoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenantradiocarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorenic acid and their ester derivatives. Examples of diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanediethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecaneethanol, decalindiethanol, decalindiethanol, 5 Examples include methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, adamandiol, paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, and pentaerythritol. Furthermore, the polyester may contain monomers other than dicarboxylic acid compounds and diol compounds, to the extent that it does not impair the properties of the present invention. Among the above, polyethylene terephthalate (hereinafter simply referred to as PET), which is a copolymer of terephthalic acid and ethylene glycol, is preferred.

[0021] In one embodiment, biomass-derived polyester can be used as the polyester constituting the base material. This polyester has a diol compound copolymer that is derived from biomass, which can significantly reduce the amount of fossil fuels used and effectively reduce the environmental burden of laminate production. Biomass-derived diol compounds, such as biomass-derived ethylene glycol, are produced using ethanol (biomass ethanol) manufactured from biomass as a raw material. Biomass-derived ethylene glycol can be obtained by conventionally known methods, such as producing ethylene glycol via ethylene oxide from biomass ethanol. Alternatively, commercially available biomass ethylene glycol may be used; for example, biomass ethylene glycol sold by India Glycol can be suitably used.

[0022] In biomass-derived polyesters, it is preferable that the biomass-derived carbon content, as determined by radiocarbon (C14) measurement, is 10-25% of the total carbon in the biomass-derived polyester. Since atmospheric carbon dioxide contains a certain proportion (105.5 pMC) of C14, it is known that the C14 content of plants that grow by absorbing atmospheric carbon dioxide, such as corn, is also around 105.5 pMC. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the proportion of C14 in the total carbon atoms of biomass-derived polyester, the proportion of carbon derived from biomass can be calculated. In this invention, the C14 content in biomass-derived polyester is P C14 In that case, the carbon content P from biomass bio This is defined as shown in equation (1) below.

number

[0023] For example, since PET is a polymer of ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms in a molar ratio of 1:1, if only biomass-derived diol units are used as ethylene glycol, the biomass-derived carbon content in the biomass polyester is P bio That will be 20%. In this embodiment, the biomass-derived carbon content, as determined by radiocarbon (C14) measurement, is preferably 10-25% of the total carbon in the polyester. If the biomass-derived carbon content in the polyester is less than 10%, its effect as a carbon offset material will be poor. On the other hand, as mentioned above, a biomass-derived carbon content in the polyester that is closer to 25% is preferable, but due to issues in the film manufacturing process and physical properties, it is preferable to include additives in the resin composition, so the actual upper limit is 22%.

[0024] In other words, when only biomass-derived diol units are used as ethylene glycol, the content of biomass-derived carbon in the biomass-derived polyester is P bio Since the content of biomass-derived carbon is 20% and the content of biomass-derived carbon is 10-19% of the total carbon in the resin composition, it is preferable that the biomass polyester obtained using biomass-derived ethylene glycol as the diol unit and fossil fuel-derived dicarboxylic acid as the dicarboxylic acid unit is contained in the base material in a mass of 50 (=10% / 20%) to 100 (=20% / 20%).

[0025] In one embodiment, recycled polyester can be used as the polyester constituting the base material. The recycled polyester of the present invention includes chemically recycled polyester and mechanically recycled polyester. Chemically recycled polyester refers to polyester obtained by decomposing polyester containers down to the monomer level and then repolymerizing them. Mechanically recycled polyester refers to polyester obtained by sorting, crushing, and washing polyester containers to remove contaminants and foreign matter, obtaining flakes, and then further treating the flakes at high temperature and reduced pressure for a certain period of time to remove contaminants from inside the resin.

[0026] The base material may contain additives to the extent that they do not impair the properties of the present invention, such as crosslinking agents, antioxidants, antiblocking agents, lubricants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0027] The thickness of the substrate is preferably 9 μm or more and 50 μm or less, and more preferably 12 μm or more and 25 μm or less. By making the substrate thickness 9 μm or more, the recyclability, heat resistance, and mechanical strength of the laminate of the present invention can be improved. Furthermore, by making the thickness of the base material 50 μm or less, the processability of the laminate of the present invention can be improved.

[0028] The base material is preferably a stretched film from the viewpoint of heat resistance and strength, and may be either a uniaxially oriented film or a biaxially oriented film.

[0029] The substrate can be prepared by forming a film from a resin composition containing at least polyester using a T-die method or an inflation method. By forming the film using the inflation method, the stretching of the resin film can be performed simultaneously.

[0030] Furthermore, the substrate may be surface-treated. This can improve adhesion with adjacent layers. The surface treatment method is not particularly limited and includes physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals. Alternatively, an anchor coat layer may be formed on the substrate surface using a conventionally known anchor coat agent.

[0031] The substrate may have a printed layer on its surface, and the image formed on the printed layer is not particularly limited and may represent characters, patterns, symbols, or combinations thereof. From an environmental perspective, it is preferable to use biomass-derived inks for forming the printed layer on the substrate. The method for forming the printed layer is not particularly limited and can be described as conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of environmental impact.

[0032] The substrate may have a vapor-deposited film on its surface. By having a vapor-deposited film on the substrate, the gas barrier properties of the laminate of the present invention, specifically the oxygen barrier properties and water vapor barrier properties, can be improved. Furthermore, the mass reduction of the contents filled into a package made using the laminate of the present invention can be suppressed.

[0033] Examples of vapor-deposited films include those composed of metals such as aluminum, as well as inorganic oxides such as aluminum oxide, silicon oxide (silica), magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide.

[0034] Furthermore, the thickness of the deposited film is preferably 1 nm to 150 nm, more preferably 5 nm to 60 nm, and even more preferably 10 nm to 40 nm. By making the thickness of the vapor-deposited film 1 nm or more, the oxygen barrier and water vapor barrier properties of the laminate can be further improved. Furthermore, by making the thickness of the vapor-deposited film 150 nm or less, the occurrence of cracks in the vapor-deposited film can be prevented. Additionally, the recyclability of the laminate can be maintained.

[0035] The formation of a deposited film on a substrate can be carried out using conventionally known methods, such as physical vapor deposition (PVD) methods including vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods including plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition.

[0036] Furthermore, for example, a composite film consisting of two or more layers of deposited inorganic oxides can be formed and used by combining both physical vapor deposition and chemical vapor deposition methods. The vacuum level of the deposition chamber before oxygen introduction is 10 -2 ~10 -8 A bar of approximately mbar is preferred, and after oxygen introduction, 10 -1 ~10 -6 A pressure of approximately mbar is preferred. The amount of oxygen introduced will vary depending on the size of the deposition machine. Inert gases such as argon, helium, or nitrogen may be used as carrier gases for the oxygen introduced, within reasonable limits. The film transport speed can be approximately 10 to 800 m / min.

[0037] It is preferable that the surface of the deposited film is subjected to the above-mentioned surface treatment. This improves adhesion with adjacent layers.

[0038] (Heat seal layer) The heat seal layer can be formed with a heat sealant containing a resin that can fuse together with heat, such as low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), ethylene-α·olefin copolymer polymerized using a metallocene catalyst, random or block copolymer of ethylene-polypropylene, polypropylene, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylic acid copolymer (EMAA), ethylene Examples include methyl methacrylate copolymer (EMMA), ionomer resins, heat-sealable ethylene-vinyl alcohol resins, or copolymerized resins, methylpentene resins, ethylene-propylene copolymers, methylpentene polymers, polybutene polymers, polyethylene, polypropylene, or polyolefin copolymers, acid-modified polyolefins obtained by modifying polyolefins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid, polyesters such as PET, polyvinyl acetate resins, poly(meth)acrylic resins, and polyvinyl chloride resins. Among these, from the viewpoint of the recyclability of the laminate of the present invention, it is preferable to form the heat seal layer using a polyester-based heat sealant, particularly a PET-based heat sealant. The heat sealant used to form the heat seal layer may be a commercially available product. Examples of PET-based heat sealants include Unitika Ltd.'s Elitel KT-0507, KT-8904, KT8701, KT-9204, and KT-8803.

[0039] The number-average molecular weight (Mn) of the resin contained in the heat-sealing agent that forms the heat-seal layer is preferably 10,000 or more and 35,000 or less, and more preferably 12,000 or more and 25,000 or less. By setting the Mn content of the resin to 10,000 or more, the ease of forming the heat seal layer can be improved. Furthermore, by setting the Mn content of the resin to 35,000 or less, the heat-sealing properties of the heat-seal layer can be improved. In this invention, Mn refers to the value measured by gel permeation chromatography using polystyrene as a standard substance, and is measured in accordance with JIS K 7252-1.

[0040] The thickness of the heat seal layer is preferably 1 μm or more, and more preferably 3 μm or more. Furthermore, if the heat seal layer is made of a resin other than polyester, its thickness is preferably 10 μm or less, and more preferably 5 μm or less. By making the thickness of the heat seal layer 1 μm or more, the heat sealability of the laminate of the present invention can be improved. Furthermore, if the heat-seal layer is made of a resin other than polyester, the recyclability of the laminate of the present invention can be improved by making its thickness 10 μm or less.

[0041] The heat seal layer can be formed using methods such as dry lamination or melt extrusion lamination.

[0042] (Middle class) In one embodiment, the laminate of the present invention comprises an intermediate layer between the substrate and the heat-seal layer, wherein the intermediate layer is made of the same material as the substrate, i.e., polyester. By adopting this configuration, the recyclability, heat resistance, and strength of the present invention can be further improved.

[0043] The intermediate layer is made of the polyester described above, and is preferably made of PET. Furthermore, the intermediate layer may contain biomass-derived polyester and / or recycled polyester. Furthermore, the intermediate layer may contain the above-mentioned additives, to the extent that it does not impair the properties of the present invention.

[0044] The thickness of the intermediate layer is preferably 9 μm or more and 50 μm or less, and more preferably 12 μm or more and 25 μm or less. By making the thickness of the intermediate layer 9 μm or more, the recyclability, heat resistance, and mechanical strength of the laminate of the present invention can be improved. Furthermore, by setting the thickness of the intermediate layer to 50 μm or less, the processability of the laminate of the present invention can be improved.

[0045] The intermediate layer is preferably a stretched film from the viewpoint of heat resistance and strength, and may be either a uniaxially oriented film or a biaxially oriented film.

[0046] The intermediate layer can be formed by depositing a resin composition containing at least polyester using a T-die method or inflation method, and then laminating it with a substrate via an adhesive layer. Furthermore, an intermediate layer can also be formed by melt-extruding a resin composition onto a substrate.

[0047] Furthermore, the intermediate layer may be surface-treated to improve adhesion with adjacent layers. Furthermore, the intermediate layer may have a printed layer and / or a vapor-deposited film on its surface.

[0048] (adhesive layer) The laminate of the present invention may include an adhesive layer between the substrate and the intermediate layer. The adhesive layer may be formed using a conventionally known adhesive. This adhesive may be a one-component curing type, a two-component curing type, or a non-curing type. Furthermore, the adhesive may be either a solvent-free adhesive or a solvent-based adhesive, but from the standpoint of environmental impact, a solvent-free adhesive is preferable. Examples of solvent-free adhesives include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, and urethane-based adhesives. Among these, two-component curing urethane-based adhesives are preferably used. Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and olefin-based adhesives. Among the above, polyester adhesives are preferred from the viewpoint of the recyclability of the laminate of the present invention.

[0049] In one embodiment, the adhesive layer may contain an oxygen absorber. There are no particular restrictions on the oxygen absorber; it may be an inorganic compound or an organic compound, and can be appropriately selected depending on the purpose. Examples of inorganic compounds include metal powders such as iron powder, titanium dioxide, cerium oxide, ferrous salts, dithionites, sulfites, metal halides, and zeolites. Examples of organic compounds include benzenetriols, polyhydric phenol compounds, polyhydric alcohol compounds, ascorbic acid compounds, cyclohexene compounds, polyene polymers having unsaturated double bonds, ethylene-vinyl alcohol copolymers, and mixtures thereof.

[0050] Within the limits that do not impair the properties of the present invention, the adhesive layer may contain additives such as oxygen absorbers, pigments such as titanium dioxide, zinc oxide and carbon black, dyes such as disperse dyes, acid dyes and cationic dyes, antioxidants, lubricants, colorants, stabilizers, wetting agents, thickeners, coagulants, gelling agents, anti-settling agents, softeners, curing agents, plasticizers, leveling agents, ultraviolet absorbers and flame retardants.

[0051] The thickness of the adhesive layer is preferably 1 μm or more, and more preferably 3 μm or more. When the adhesive layer is composed of an adhesive other than a polyester-based adhesive, its thickness is preferably 6 μm or less, more preferably 4 μm or less. By setting the thickness of the adhesive layer to 1 μm or more, the adhesion between the base material and the intermediate layer can be improved. When the adhesive layer is composed of an adhesive other than a polyester-based adhesive, by setting its thickness to 6 μm or less, the recyclability of the laminate of the present invention can be improved.

[0052] (Barrier coating layer) When the laminate of the present invention includes a vapor deposition film composed of an inorganic oxide, a barrier coating layer can be provided adjacent to this vapor deposition film. As a specific example, the laminate of the present invention includes a base material, an inorganic oxide vapor deposition film, a barrier coating layer, and a heat seal layer in this order. With such a configuration, the oxygen barrier property and water vapor barrier property of the laminate of the present invention can be improved. In addition, the generation of cracks in the vapor deposition film can be effectively prevented.

[0053] In one embodiment, the barrier coating layer is a gas barrier coating film containing at least one resin composition such as a hydrolyzate of a metal alkoxide or a hydrolytic condensate of a metal alkoxide obtained by polycondensing a mixture of a metal alkoxide and a water-soluble polymer by the sol-gel method in the presence of a sol-gel method catalyst, water, an organic solvent, etc.

[0054] In one embodiment, the metal alkoxide is represented by the following general formula. R 1 n M(OR 2 ) m (However, in the formula, R 1 , R 2 each 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.)

[0055] Examples of metal atoms M that can be used include silicon, zirconium, titanium, and aluminum. Also, R 1 and R 2 Examples of organic groups represented by include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, and i-butyl groups.

[0056] 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).

[0057] Furthermore, it is preferable to use a silane coupling agent together with the above-mentioned metal alkoxide. As silane coupling agents, known organic reactive group-containing organoalkoxysilanes can be used, but organoalkoxysilanes having an epoxy group are particularly preferred. Examples of organoalkoxysilanes having an epoxy group include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0058] Two or more of the above-mentioned silane coupling agents may be used, and it is preferable to use the silane coupling agent in an amount of about 1 to 20 parts by mass per 100 parts by mass of the total amount of the above-mentioned alkoxides.

[0059] As water-soluble polymers, polyvinyl alcohol and ethylene-vinyl alcohol copolymers are preferred, and from the viewpoint of oxygen barrier properties, water vapor barrier properties, water resistance and weather resistance, it is preferable to use these in combination.

[0060] The content of the water-soluble polymer in the gas barrier coating film is preferably 5 parts by mass or more and 500 parts by mass or less per 100 parts by mass of metal alkoxide. By setting the content of the water-soluble polymer in the gas barrier coating film to 5 parts by mass or more per 100 parts by mass of metal alkoxide, the oxygen barrier and water vapor barrier properties of the laminate can be further improved. Furthermore, by setting the content of the water-soluble polymer in the gas barrier coating film to 500 parts by mass or less per 100 parts by mass of metal alkoxide, the film-forming properties of the gas barrier coating film can be improved.

[0061] The thickness of the gas barrier coating film is preferably 0.01 μm or more and 2 μm or less, and more preferably 0.1 μm or more and 1 μm or less. By setting the thickness of the gas barrier coating film to 0.01 μm or more, the oxygen barrier and water vapor barrier properties of the laminate of the present invention can be improved. Furthermore, by setting the thickness of the gas barrier coating film to 2 μm or less, the recyclability of the laminate of the present invention can be improved.

[0062] A gas barrier coating film can be formed by applying a composition containing the above-mentioned materials using conventionally known methods such as roll coating (including gravure roll coaters), spray coating, spin coating, dipping, brushing, barcode application, or applicator application, and then polycondensing the composition by a sol-gel method. Suitable catalysts for the sol-gel process include acids or amine compounds. Suitable amine compounds include tertiary amines that are substantially insoluble in water and soluble in organic solvents, such as N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. Among these, N,N-dimethylbenzylamine is preferred. The sol-gel catalyst is preferably used in an amount of 0.01 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of metal alkoxide, and more preferably in an amount of 0.03 parts by mass or more and 0.3 parts by mass or less. The catalytic effect of the sol-gel method catalyst can be improved by using 0.01 parts by mass or more per 100 parts by mass of metal alkoxide. Furthermore, by using 1.0 part by mass or less per 100 parts by mass of metal alkoxide, the thickness of the formed gas barrier coating film can be made uniform.

[0063] The above composition may further contain an acid. The acid is used as a catalyst for the sol-gel process, mainly as a catalyst for the hydrolysis of alkoxides and silane coupling agents. As acids, mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid, as well as organic acids such as acetic acid and tartaric acid, can be used. The amount of acid used is preferably 0.001 moles or more and 0.05 moles or less relative to the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent. By using an amount of acid equal to 0.001 moles or more relative to the total molar amount of the alkoxide component (e.g., silicate portion) of the alkoxide and silane coupling agent, the catalytic effect can be improved. Furthermore, by using an amount of acid equal to 0.05 moles or less relative to the total molar amount of the alkoxide component (e.g., silicate portion) of the alkoxide and silane coupling agent, the thickness of the formed gas barrier coating film can be made uniform.

[0064] Furthermore, the above composition preferably contains water in an amount of 0.1 moles to 100 moles, more preferably 0.8 moles to 2 moles, per mole of the total molar amount of alkoxide. By setting the water content to 0.1 moles or more per mole of total alkoxide, the oxygen barrier and water vapor barrier properties of the laminate of the present invention can be improved. Furthermore, by setting the water content to 100 moles or more per mole of total alkoxide, the hydrolysis reaction can be carried out rapidly.

[0065] Furthermore, the above composition may contain an organic solvent. Examples of organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butanol.

[0066] The following describes one embodiment of a method for forming a gas barrier coating film. First, a composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and, if necessary, a silane coupling agent. A polycondensation reaction gradually proceeds within this composition. Next, the composition is applied to the substrate using the conventionally known method described above and dried. This drying further promotes the polycondensation reaction between the alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains one), forming a layer of composite polymer. Finally, a gas barrier coating film can be formed by heating the composition at a temperature of 20 to 250°C, preferably 50 to 220°C, for 1 second to 10 minutes.

[0067] The barrier coat layer may have a printed layer formed on it. The method for forming the printed layer is as described above.

[0068] The barrier coating layer may contain the above-mentioned additives to the extent that they do not impair the properties of the present invention.

[0069] (packaging) The packaging body of the present invention is characterized by comprising the above-mentioned laminate. Examples of packaging bodies include packaged products (packaging bags), lid materials, and laminate tubes.

[0070] Examples of packaging bags include various types such as standing pouch type, side seal type, two-side seal type, three-side seal type, four-side seal type, envelope seal type, gusset seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, and gusset type.

[0071] A standing pouch, which is an example of a packaging body comprising the laminate of the present invention, will be described. Figure 3 is a simplified diagram showing an example of the configuration of a standing pouch. As shown in Figure 3, the standing pouch 20 consists of a body (side sheet) 21 and a bottom (bottom sheet) 22. The side sheet 21 and bottom sheet 22 of the standing pouch 20 may be made of the same material or of different materials.

[0072] In one embodiment, the body portion 21 of the standing pouch 20 can be formed by manufacturing the bag such that the heat-seal layer of the laminate of the present invention becomes the innermost layer. In another embodiment, the side sheet 21 can be formed by preparing two laminates of the present invention, overlapping them so that the heat-seal layers face each other, and inserting two V-shaped folded laminates from both ends of the overlapping laminate so that the heat-seal layers face outwards, and then heat-sealing them. According to this manufacturing method, a stand pouch having a body with a gusset 23 as shown in Figure 4 can be made.

[0073] In one embodiment, the bottom sheet 22 of the standing pouch 20 can be formed by inserting the laminate of the present invention between the side sheets of the bag and heat sealing them. More specifically, the laminate can be formed by folding it into a V-shape so that the heat-seal layer faces outwards, inserting it between the side sheets of the bag-shaped laminate, and then heat-sealing it.

[0074] Heat sealing can be carried out using known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high-frequency sealing, and ultrasonic sealing.

[0075] The contents to be filled into the packaging are not particularly limited and may be liquids, powders, or gels. They may also be food products or non-food products. [Examples]

[0076] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0077] Example 1 A 25 μm thick biaxially oriented PET film was prepared as the substrate, with one side treated with corona. A printed layer was formed on the corona-treated side of this PET film using gravure printing.

[0078] On the printed layer formed as described above, an ethylene-vinyl acetate copolymer emulsion (Seikadine 1900w, manufactured by Dainichi Seika Kogyo Co., Ltd.) was applied and dried to form a heat-seal layer with a thickness of 3 μm, thereby obtaining the laminate of the present invention.

[0079] Example 2 A 12 μm thick biaxially oriented PET film was prepared as the substrate, with one side treated with corona. A printed layer was formed on the corona-treated side of this PET film using gravure printing.

[0080] A two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-40 / hardener H-4) was applied to the printed layer formed as described above, dried to form a 3 μm thick adhesive layer, and a 12 μm thick biaxially oriented PET film, which had been corona-treated on both sides, was laminated as an intermediate layer.

[0081] An ethylene-vinyl acetate copolymer emulsion (Seikadine 1900w, manufactured by Dainichi Seika Kogyo Co., Ltd.) was applied to the other side of the PET film, which is the intermediate layer, as a heat sealant, and dried to form a heat seal layer with a thickness of 3 μm, thereby obtaining the laminate of the present invention.

[0082] Example 3 A 12 μm thick biaxially oriented PET film with a silica vapor-deposited film formed on one side was prepared as the substrate. A printed layer was formed on the vapor-deposited side of this PET film by gravure printing.

[0083] The two-component curing urethane adhesive described above was applied to the printed layer formed as described above and dried to form an adhesive layer with a thickness of 3 μm. A 12 μm thick biaxially oriented PET film, which had been corona-treated on both sides, was laminated as an intermediate layer.

[0084] An ethylene-vinyl acetate copolymer emulsion (Seikadine 1900w, manufactured by Dainichi Seika Kogyo Co., Ltd.) was applied to the other side of the PET film, which is the intermediate layer, as a heat sealant, and dried to form a heat seal layer with a thickness of 3 μm, thereby obtaining the laminate of the present invention.

[0085] Example 4 A laminate was obtained in the same manner as in Example 2, except that the PET film used as the base material was changed to a 12 μm thick biaxially oriented biomass PET film (manufactured by Dai Nippon Printing Co., Ltd., product name Biomatec PET, biomass content 20%) with corona treatment on one side, and the PET film used as the intermediate layer was changed to a 12 μm thick biaxially oriented biomass PET film (manufactured by Dai Nippon Printing Co., Ltd., product name Biomatec PET, biomass content 20%) with corona treatment on both sides.

[0086] Example 5 A laminate was obtained in the same manner as in Example 2, except that the PET film used as the base material was changed to a 12 μm thick biaxially oriented recycled PET film (manufactured by Toyobo Co., Ltd.) with corona treatment on one side, and the PET film used as the intermediate layer was changed to a 12 μm thick biaxially oriented recycled PET film (manufactured by Toyobo Co., Ltd.) with corona treatment on both sides.

[0087] Example 6 A laminate was obtained in the same manner as in Example 2, except that a polyethylene emulsion (Arrowbase SD-1205-J2, manufactured by Unitika Ltd.) was used as the heat sealant.

[0088] Example 7 A laminate was obtained in the same manner as in Example 2, except that a PET-based emulsion (Unitika Ltd., Elitel KT-0507, Mn17000, Tg-25℃) was used as the heat sealant.

[0089] Comparative Example 1 A 12 μm thick biaxially oriented PET film was prepared as the substrate, with one side treated with corona. A printed layer was formed on the corona-treated side of this PET film using gravure printing.

[0090] A two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-40 / curing agent H-4) was applied to the printed layer formed as described above, dried to form a 3 μm thick adhesive layer, and a 30 μm thick LLDPE film was laminated as a heat-seal layer to obtain a laminate.

[0091] <<Recyclability Assessment>> The PET content in the entire laminate prepared in the above examples and comparative examples was determined, and its recyclability was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1. (Evaluation Criteria) A: The PET content in the entire laminate was 70% by mass or more. NG: The PET content in the entire laminate was less than 70% by mass.

[0092] <<Heat seal strength test>> Two of the laminates prepared in the above examples and comparative examples were stacked so that the heat-sealed layers faced each other, and heat-sealed (140°C, 1 kgf, 1 second) was performed. Next, the seal strength was measured using a tensile testing machine and evaluated based on the evaluation criteria below. The evaluation results are summarized in Table 1. (Evaluation results) A: The heat seal strength was 4.0 N / 15 mm or higher. MG: The heat seal strength was less than 4.0 N / 15 mm.

[0093] [Table 1]

[0094] As is clear from the results in Table 1, the laminate of the present invention makes it possible to produce packaging bags that maintain heat sealability while exhibiting excellent recyclability. [Explanation of symbols]

[0095] 10: Laminate, 11: Substrate, 12: Heat seal layer, 13: Vapor-deposited film, 14: Intermediate layer, 15: Adhesive layer, 20: Standing pouch, 21: Body, 22: Bottom, 23: Gusset

Claims

1. A laminate comprising at least a substrate, an intermediate layer, and a heat seal layer, The substrate is made of polyester, the intermediate layer is made of polyester, the substrate and the intermediate layer are subjected to a stretching treatment, the heat seal layer is formed from a heat seal agent containing a resin having a number average molecular weight (Mn) of 10,000 or more and 35,000 or less, A laminate characterized in that the thickness of the heat seal layer is 1 μm or more and 5 μm or less.

2. The laminate according to claim 1 , wherein the ratio of the thickness of the substrate to the thickness of the entire laminate is 60% or more.

3. The laminate according to claim 1 or 2, wherein the heat seal layer comprises a polyester-based heat seal agent.

4. The laminate according to any one of claims 1 to 3, wherein the substrate comprises a vapor-deposited film.

5. The laminate according to any one of claims 1 to 4, wherein the content of polyester in the entire laminate is 60 mass% or more.

6. The laminate according to any one of claims 1 to 5, which is used for packaging purposes.

7. A packaging body comprising the laminate according to any one of claims 1 to 6.

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