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. The base material and the heat seal layer are composed of the same material. The same material is polyester.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminate used for producing a package, etc. The present invention also relates to a package comprising the laminate.

[0002] Conventionally, resin films made of resin materials have been used as materials for forming packaging bodies. For example, polyester films are widely used because they are inexpensive and have excellent mechanical properties, chemical stability, heat resistance, and transparency.

[0003] Typically, a polyester film is laminated with a polyolefin film having heat-sealing properties or a polyamide film having gas barrier properties, and the polyolefin films in the laminate are heat-sealed to produce a package.

[0004] In recent years, with the growing demand for the creation of a recycling-oriented society, there is a demand for high recyclability of packaging materials, etc. However, as described above, conventional packaging bags are made of different resin materials, and it is difficult to separate them into individual resin materials, so they are not currently recycled. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above problems, and the problem to be solved by the present invention is to provide a laminate that enables the production of packaging bags and the like that are excellent in recyclability while maintaining heat sealability. Another problem to be solved by the present invention is to provide a package including the laminate. [Means for solving the problem]

[0006] The laminate of the present invention comprises a substrate and a heat seal layer, The substrate and the heat seal layer are made of the same material, The uniform material is polyester.

[0007] In one embodiment, the heat seal layer is formed from an unoriented film composed of polyester or a melt extruded layer composed of polyester.

[0008] In one embodiment, the substrate comprises a vapor-deposited film.

[0009] In one embodiment, an adhesive layer is provided between the substrate and the heat seal layer, The adhesive layer is made of a polyester-based adhesive.

[0010] In one embodiment, an intermediate layer is provided between the substrate and the heat seal layer, The intermediate layer is made of the same material as the base material, The same material is polyester.

[0011] In one embodiment, the content of polyester in the entire laminate is 75% by mass or more.

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

[0013] The packaging body of the present invention is characterized by comprising the above-mentioned laminate. Effect 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 package including this laminate can be provided. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic cross-sectional view showing one embodiment of a laminate of the present invention. [Diagram 2]1 is a schematic cross-sectional view showing one embodiment of a laminate of the present invention. [Diagram 3] 1 is a schematic cross-sectional view showing one embodiment of a laminate of the present invention. [Figure 4] 1 is a front view showing one embodiment of a package including a laminate of the present invention. [Diagram 5] 1 is a perspective view illustrating one embodiment of a package including a laminate of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (Laminate) The laminate 10 of the present invention is characterized by comprising a substrate 11 and a heat seal layer 12, as shown in FIG. In one embodiment, as shown in FIG. 2, the laminate of the present invention includes an adhesive layer 13 between a substrate 11 and a heat seal layer 12 . In one embodiment, as shown in FIG. 3, the laminate 10 of the present invention includes an intermediate layer 14 between the substrate 11 and the heat seal layer 12 . The laminate 10 of the present invention may have two or more intermediate layers 14.

[0017] In the laminate of the present invention, the base material and the heat seal layer are made of the same material, that is, polyester. By producing a package using a laminate having such a configuration, the package can be made to have excellent recyclability.

[0018] The content of polyester in the entire laminate of the present invention is preferably 75% by mass or more, and more preferably 85% by mass or more. By making the content of polyester in the entire laminate of the present invention 75% by mass or more, the recyclability of the laminate of the present invention can be improved.

[0019] Each layer of the laminate of the present invention will be described below.

[0020] (base material) The substrate constituting the laminate of the present invention is characterized by being made of polyester. In the present invention, the 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, dodecanedioic acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, 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-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorene acid, and ester derivatives thereof. Examples of the diol compound include ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecane dimethanol, tricyclodecane ethanol, tetracyclododecane dimethanol, tetracyclododecane diethanol, decalin dimethanol, decalin diethanol, 5-cyclohexanediol ... -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, adamantanediol, paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, and pentaerythritol. Furthermore, the polyester may contain a monomer other than the dicarboxylic acid compound and the diol compound, so long as the characteristics of the present invention are not impaired. 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, a biomass-derived polyester can be used as the polyester constituting the substrate. This polyester contains a diol compound, which is a copolymerization component, derived from biomass, and can significantly reduce the amount of fossil fuel used, thereby effectively reducing the environmental impact of producing the laminate. Biomass-derived diol compounds, for example, biomass-derived ethylene glycol, are made from ethanol (biomass ethanol) produced from biomass as a raw material. Biomass-derived ethylene glycol can be obtained by a method of producing ethylene glycol from biomass ethanol via ethylene oxide using a conventionally known method. Commercially available biomass ethylene glycol may also be used, and for example, biomass ethylene glycol sold by India Glycoal Limited can be suitably used.

[0022] The biomass-derived polyester preferably contains 10 to 25% of biomass-derived carbon based on radiocarbon (C14) measurement relative to the total carbon in the biomass-derived polyester. Carbon dioxide in the atmosphere contains a certain percentage of C14 (105.5 pMC), so it is known that the C14 content in plants that grow by absorbing carbon dioxide from the atmosphere, such as corn, is also about 105.5 pMC. It is also known that fossil fuels contain very little C14. Therefore, by measuring the percentage of C14 in the total carbon atoms in biomass-derived polyester, the percentage of carbon derived from biomass can be calculated. In the present invention, the content of C14 in the biomass-derived polyester is P C14 The content of carbon derived from biomass, P bio is defined as the following equation (1).

number

[0023] For example, 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 content of biomass-derived carbon in the biomass polyester is P bio is 20%. In this embodiment, the content of biomass-derived carbon based on radiocarbon (C14) measurement is preferably 10 to 25% relative to the total carbon in the polyester. If the biomass-derived carbon content in the polyester is less than 10%, the effect as a carbon offset material is poor. On the other hand, as described above, the biomass-derived carbon content in the polyester is preferably as close to 25% as possible, but because it is preferable to include an additive in the resin composition due to problems in the film manufacturing process and physical properties, the actual upper limit is 22%.

[0024] That is, when only biomass-derived diol units are used as ethylene glycol, the content of biomass-derived carbon in the biomass-derived polyester, P bio is 20%, and the content of biomass-derived carbon is 10 to 19% of the total carbon in the resin composition, which means that the biomass polyester obtained by using biomass-derived ethylene glycol as the diol unit and fossil fuel-derived dicarboxylic acid as the dicarboxylic acid unit is preferably contained in the base material in an amount of 50 (=10% / 20%) mass% to 100 (=20% / 20%) mass%.

[0025] In one embodiment, recycled polyester can be used as the polyester constituting the substrate. 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 polymerizing them again. Mechanically recycled polyester refers to polyester obtained by sorting, crushing and washing polyester containers to remove contaminants and foreign matter to obtain flakes, and then treating the flakes for a certain period of time under high temperature and reduced pressure to remove contaminants inside the resin.

[0026] The substrate may contain additives within the range that does not impair the characteristics of the present invention. Examples of such additives include crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[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 thickness of the substrate 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 substrate 25 μm or less, the processability of the laminate of the present invention can be improved.

[0028] From the viewpoint of heat resistance and strength, the substrate is preferably a stretched film, and may be either a uniaxially stretched film or a biaxially stretched film.

[0029] The substrate can be prepared by forming a film from a resin composition containing at least a polyester by using a casting method, a T-die method, an inflation method or the like. By forming the film by the inflation method, the resin film can be stretched at the same time.

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

[0031] The substrate may have a printed layer on its surface. The image formed on the printed layer is not particularly limited, and may represent characters, patterns, symbols, combinations of these, and the like. From the viewpoint of environmental impact, the formation of a printed layer on a substrate is preferably carried out using an ink derived from biomass. The method for forming the printed layer is not particularly limited, and examples of the method 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.

[0032] The substrate may have a vapor-deposited film on its surface. By providing the substrate with a vapor-deposited film, the gas barrier properties, specifically, the oxygen barrier properties and water vapor barrier properties of the laminate of the present invention can be improved. In addition, the weight loss of the contents filled in the package produced using the laminate of the present invention can be suppressed.

[0033] 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 (silica), magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide.

[0034] The thickness of the evaporated 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 laminate can be further improved. Also, 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. Also, the recyclability of the laminate can be maintained.

[0035] The deposition film on the substrate can be formed by a conventional 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.

[0036] 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 both physical vapor deposition and chemical vapor deposition. The degree of vacuum in the vapor deposition chamber is 10 -2 ~10 -8 After oxygen is introduced, the pressure is preferably about 10 -1 ~10 -6 The pressure is preferably about mbar. The amount of oxygen introduced varies depending on the size of the deposition machine. For the oxygen to be introduced, an inert gas such as argon gas, helium gas, or nitrogen gas may be used as a carrier gas to the extent that no problems occur. The film transport speed can be about 10 to 800 m / min.

[0037] The surface of the deposited film is preferably subjected to the above-mentioned surface treatment, which can improve adhesion to adjacent layers.

[0038] (Heat seal layer) The heat seal layer is characterized by being made of the same material as the base material, that is, polyester. Among the above polyesters, PET is preferred. Furthermore, the polyester may contain biomass-derived polyester and / or recycled polyester. Furthermore, the heat seal layer may contain the above-mentioned additives as long as the characteristics of the present invention are not impaired.

[0039] From the viewpoint of heat sealability, the heat seal layer is preferably made of a low crystalline or amorphous polyester. The degree of crystallinity of the polyester constituting the heat seal layer is preferably 12% or less, and more preferably 10% or less. By making the degree of crystallinity of the polyester 12% or less, the heat sealability can be further improved. In the present invention, the crystallinity of the polyester is determined by dividing the heat of fusion of a low-crystalline or amorphous polyester when melted using a differential scanning calorimeter by the heat of fusion of a completely crystalline polyester (140 J / g for PET), and multiplying the result by 100.

[0040] The glass transition temperature (Tg) of the polyester constituting the heat seal layer is preferably 60°C or higher and 90°C or lower, and more preferably 63°C or higher and 80°C or lower. By adjusting the Tg of the polyester to 90° C. or less, the heat sealability of the heat seal layer can be improved. Furthermore, by setting the Tg of the polyester to 60° C. or higher, the occurrence of blocking and the like can be prevented. In the present invention, Tg is a value determined by differential scanning calorimetry in accordance with JIS K 7121.

[0041] In one embodiment, the heat seal layer is formed of a film made of polyester. This film may be a stretched film or an unstretched film, but is preferably an unstretched film from the viewpoint of the heat sealability of the heat seal layer. Such a film can be produced by utilizing a casting method, a T-die method, an inflation method, or the like. The film-like heat seal layer can be laminated to the substrate via an adhesive described below.

[0042] In one embodiment, the heat seal layer is formed by a melt extrusion layer made of polyester.

[0043] The thickness of the heat seal layer is preferably 20 μm or more, and more preferably 30 μm or more.

[0044] (adhesive layer) The laminate of the present invention may have an adhesive layer between the substrate and the heat seal layer. When the laminate of the present invention has an intermediate layer described below, the adhesive layer may be provided between the substrate and the intermediate layer and between the intermediate layer and the heat seal layer. In this case, the configuration of each adhesive layer may be the same or different.

[0045] The adhesive layer may be formed from a conventionally known adhesive, which may be a one-component curing type, a two-component curing type, or a non-curing type. 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 preferably used. Examples of solvent-free adhesives include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, and urethane adhesives, and among these, two-liquid curing urethane adhesives can be preferably used. Examples of the solvent-based adhesive include rubber-based adhesives, vinyl-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and olefin-based adhesives. Of the above, from the viewpoint of recyclability of the laminate of the present invention, polyester-based adhesives are preferred, and PET-based adhesives are more preferred. For example, PET-based adhesives include Elitel KT-0507, KT-8904, KT8701, KT-9204, and KT-8803 manufactured by Unitika Ltd.

[0046] As long as the properties of the present invention are not impaired, the adhesive layer may contain additives such as oxygen absorbers, pigments such as titanium oxide, 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, hardeners, plasticizers, leveling agents, ultraviolet absorbers, and flame retardants.

[0047] The thickness of the adhesive layer is preferably 1 μm or more, and more preferably 6 μm or less. Furthermore, when the adhesive layer is made of an adhesive material other than a polyester-based adhesive, the thickness is preferably 5 μm or less, and more preferably 3 μm or less. By making the thickness of the adhesive layer 1 μm or more, the adhesion between the layers can be improved. Furthermore, when the adhesive layer is made of an adhesive material other than a polyester-based adhesive, the recyclability of the laminate of the present invention can be improved by making the thickness 5 μm or less.

[0048] (Middle class) In one embodiment, the laminate of the present invention comprises an intermediate layer between the substrate and the heat seal layer, and the intermediate layer is made of the same material as the substrate, that is, polyester. By adopting such a configuration, the recyclability, heat resistance, and strength of the present invention can be further improved.

[0049] The intermediate layer is made of the above-mentioned polyester, and is preferably made of PET. The intermediate layer can also include biomass-derived polyester and / or recycled polyester. Furthermore, the intermediate layer may contain the above-mentioned additives as long as the characteristics of the present invention are not impaired.

[0050] 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 making the thickness of the intermediate layer 50 μm or less, the processability of the laminate of the present invention can be improved.

[0051] From the viewpoints of heat resistance and strength, the intermediate layer is preferably a stretched film, and may be a uniaxially stretched film or a biaxially stretched film.

[0052] The intermediate layer can be formed by forming a film from a resin composition containing at least a polyester by using a casting method, a T-die method, an inflation method or the like, and laminating this to a substrate via an adhesive layer. Alternatively, the intermediate layer can be formed by melt-extruding the resin composition onto the substrate.

[0053] The intermediate layer may be subjected to a surface treatment in order to improve adhesion to the adjacent layer. The intermediate layer may also have a printed layer and / or a vapor-deposited film on its surface.

[0054] (Barrier coat layer) When the laminate of the present invention comprises a vapor-deposited film made of an inorganic oxide, it can comprise a barrier coat layer adjacent to this vapor-deposited film. As a specific example, the laminate of the present invention includes a substrate, an inorganic oxide vapor deposition film, a barrier coat layer, an adhesive layer, and a heat seal layer in this order. By adopting such a configuration, the oxygen barrier property and water vapor barrier property of the laminate of the present invention can be improved. Furthermore, the occurrence of cracks in the vapor-deposited film can be effectively prevented.

[0055] In one embodiment, the barrier coat layer is a gas barrier coating film containing at least one resin composition such as a hydrolysate 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.

[0056] In one embodiment, the metal alkoxide is represented by the following general formula: R 1 n M(OR 2 ) m (In the formula, R 1 , 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 atomic valence of M.

[0057] 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.

[0058] 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).

[0059] It is also preferable to use a silane coupling agent together with the metal alkoxide. As the silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used, and in particular, organoalkoxysilanes having epoxy groups are preferred. As organoalkoxysilanes having epoxy groups, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane can be mentioned.

[0060] Two or more of the above silane coupling agents may be used, and the silane coupling agent is preferably used in an amount within the range of about 1 to 20 parts by mass per 100 parts by mass of the total amount of the alkoxide.

[0061] As the water-soluble polymer, polyvinyl alcohol and an ethylene-vinyl alcohol copolymer are preferred, and from the viewpoints of oxygen barrier properties, water vapor barrier properties, water resistance and weather resistance, it is preferred to use these in combination.

[0062] 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 making the content of the water-soluble polymer in the gas barrier coating film 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 laminate can be further improved. Also, by making the content of the water-soluble polymer in the gas barrier coating film 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.

[0063] The thickness of the gas barrier coating film is preferably from 0.01 μm to 2 μm, and more preferably from 0.1 μm to 1 μm. By adjusting the thickness of the gas barrier coating film to 0.01 μm or more, the oxygen barrier property and water vapor barrier property of the laminate of the present invention can be improved. Furthermore, by making the thickness of the gas barrier coating film 2 μm or less, the recyclability of the laminate of the present invention can be improved.

[0064] 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, brushing, bar coding, or an applicator, and then polycondensing the composition by a sol-gel method. As the sol-gel catalyst, an acid or an amine compound is preferable. As the amine compound, a tertiary amine that is substantially insoluble in water and soluble in an organic solvent is preferable, and examples thereof include N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. Among these, N,N-dimethylbenzylamine is preferable. The sol-gel catalyst is preferably used in the range of 0.01 to 1.0 part by mass, and more preferably 0.03 to 0.3 part by mass, per 100 parts by mass of the metal alkoxide. By using a sol-gel catalyst in an amount of 0.01 part by mass or more per 100 parts by mass of the metal alkoxide, the catalytic effect can be improved, and by using a sol-gel catalyst in an amount of 1.0 part by mass or less per 100 parts by mass of the metal alkoxide, the thickness of the gas barrier coating film formed can be made uniform.

[0065] 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, tartaric acid, etc. The amount of the acid used is preferably 0.001 mol or more and 0.05 mol or less based on the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent. The amount of acid used is 0.001 moles or more relative to the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent, thereby improving the catalytic effect. Also, the amount of acid used is 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, thereby making the thickness of the gas barrier coating film formed uniform.

[0066] 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 controlling the water content to 0.1 moles or more per mole of the total molar amount of the alkoxides, the oxygen barrier property and water vapor barrier property of the laminate of the present invention can be improved. Also, by controlling the water content to 100 moles or more per mole of the total molar amount of the alkoxides, the hydrolysis reaction can be carried out quickly.

[0067] The composition may also contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butanol.

[0068] Hereinafter, one embodiment of the method for forming a gas barrier coating film will be described. 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. In the composition, a polycondensation reaction gradually proceeds. Next, the composition is applied onto a substrate by the above-mentioned conventionally known method and dried. This drying process further advances the polycondensation reaction between the alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains a silane coupling agent) 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.

[0069] The barrier coat layer may have a printed layer formed thereon. The method for forming the printed layer is as described above.

[0070] The barrier coat layer may contain the above-mentioned additives to the extent that the characteristics of the present invention are not impaired.

[0071] (packaging) The packaging body of the present invention is characterized by comprising the above laminate. Examples of the packaging body include packaging products (packaging bags), lids, and laminate tubes.

[0072] Examples of packaging bags include packaging bags of various shapes, such as standing pouch type, side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, grommet seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, and gusset type.

[0073] A standing pouch, which is an example of a packaging body including the laminate of the present invention, will be described. Fig. 3 is a diagram showing a simplified example of the configuration of a standing pouch. As shown in Fig. 3, the standing pouch 20 is composed of a body portion (side sheet) 21 and a bottom portion (bottom sheet) 22. The side sheet 21 and the bottom sheet 22 of the standing pouch 20 may be composed of the same material or different materials.

[0074] In one embodiment, the body 21 of the standing pouch 20 can be formed by bag making so 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 sheets of the laminate of the present invention, overlapping them with their heat seal layers facing each other, inserting two sheets of laminate folded in a V shape into both ends of the overlapped laminate so that the heat seal layers are on the outside, and heat sealing them. According to this production method, a stand pouch having a body with a gusset 23 as shown in Fig. 4 can be obtained.

[0075] In one embodiment, the bottom sheet 22 of the standing pouch 20 can be formed by inserting the laminate of the present invention between pre-formed side sheets and heat sealing them. More specifically, the laminate can be formed by folding it into a V shape so that the heat seal layer is on the outside, inserting it between side sheets that have been made into a bag, and heat sealing it.

[0076] The heat sealing can be performed by a known method such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, ultrasonic sealing, etc.

[0077] The contents filled in the package are not particularly limited, and may be liquid, powder, or gel. The contents may be food or non-food. EXAMPLES

[0078] 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.

[0079] Example 1 As a substrate, a biaxially stretched PET film (E5100, manufactured by Toyobo Co., Ltd.) having a thickness of 12 μm and having one surface subjected to a corona treatment was prepared. A print layer was formed on the corona-treated surface of this PET film by gravure printing.

[0080] PET1 (Vylon SI-173, manufactured by Toyobo Co., Ltd., Tg: 78°C) was cast to produce a 20 μm thick unstretched film for heat seal layer. This unstretched film for heat seal layer was laminated onto the printed layer-forming surface of the substrate via a two-liquid curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-40 / curing agent H-4) to obtain a laminate of the present invention.

[0081] Example 2 A laminate of the present invention was produced in the same manner as in Example 1, except that the unstretched film for the heat seal layer was changed to a 20 μm thick stretched film for the heat seal layer (manufactured by Toyobo Co., Ltd., Olyester DE046, Tg: 65° C.).

[0082] Example 3 A biaxially stretched PET film having a thickness of 12 μm and having a silica vapor deposition film formed on one side was prepared as a substrate. A print layer was formed on the vapor deposition surface of this PET film by gravure printing.

[0083] The unstretched film for the heat seal layer made of PET1 (Vylon SI-173, manufactured by Toyobo Co., Ltd.) prepared in Example 1 was laminated on the deposition layer-forming surface of the substrate via a two-component curing urethane adhesive (product name: RU-40 / curing agent H-4, manufactured by Rock Paint Co., Ltd.) to obtain a laminate of the present invention.

[0084] Example 4 A laminate was obtained in the same manner as in Example 1, except that the biaxially oriented PET film used as the substrate 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 one side subjected to corona treatment.

[0085] Example 5 A laminate was obtained in the same manner as in Example 2, except that the PET film used as the substrate was changed to a 12 μm-thick biaxially stretched recycled PET film (manufactured by Toyobo Co., Ltd.) that had been corona-treated on one side.

[0086] Example 6 A laminate was obtained in the same manner as in Example 1, except that the substrate and the heat seal layer were laminated via a PET emulsion (Elitel KT-0507, manufactured by Unitika Ltd.).

[0087] Comparative Example 1 A biaxially stretched PET film having a thickness of 12 μm and having one surface subjected to a corona treatment was prepared as a substrate. A print layer was formed on the corona-treated surface of the PET film by gravure printing.

[0088] A two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-40 / curing agent H-4) was applied onto the printed layer formed as described above and 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.

[0089] <<Recyclability evaluation>> The PET content in the entire laminate produced in the above Examples and Comparative Examples was determined, and the 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 80 mass % or more. NG: The PET content in the entire laminate was less than 80% by mass.

[0090] <<Heat seal strength test-1>> The laminates produced in the above Examples and Comparative Examples were cut to a size of 220 mm length x 130 mm width. Two of the laminates cut as described above were stacked together with their heat seal layers facing each other, and a laminate prepared in the above Examples and Comparative Examples was folded into a V shape at one end of the body so that the heat seal layer was on the outside and sandwiched between the laminates. Next, the two vertical sides and the side sandwiching the V-shaped laminate were heat sealed (140° C., 1 kgf, 1 second).

[0091] This packaging bag was filled with 300 mL of liquid detergent, and the remaining side was heat sealed (140° C., 1 kgf, 1 second) to form a package.

[0092] The above package was dropped 10 times from a height of 100 cm onto a hard floor with the body of the package horizontal to the ground. This test was carried out for 10 bags at a time, and the presence or absence of damage was visually observed, and the heat sealability was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1. (Evaluation Criteria) A: No damage was found in any of the 10 bags. NG: Damage was confirmed in one or more of the 10 bags, making the product unusable.

[0093] <<Heat seal strength test-2>> Two sheets of each of the laminates produced in the above Examples and Comparative Examples were overlapped with their heat seal layers facing each other, and heat sealed (140° C., 1 kgf, 1 second). The seal strength was then measured using a tensile tester. The measurement results are summarized in Table 1.

[0094] [Table 1]

[0095] As is clear from the results in Table 1, it is understood that the laminate of the present invention makes it possible to produce a packaging bag that is excellent in recyclability while maintaining heat sealability. [Explanation of symbols]

[0096] 10: laminate, 11: substrate, 12: heat seal layer, 13: adhesive layer, 14: intermediate layer, 20: standing pouch, 21: body portion, 22: bottom portion, 23: gusset

Claims

1. It comprises a base material and a heat-seal layer, The substrate and the heat seal layer are made of polyester. The polyester constituting the heat seal layer is a crystalline polyester whose glass transition temperature (Tg) is 60°C or higher and 90°C or lower. A laminate characterized by the following features.

2. The laminate according to claim 1, wherein the heat-seal layer is formed of an unstretched film made of polyester or a melt-extruded layer made of polyester.

3. The laminate according to claim 1 or 2, wherein the substrate comprises a vapor-deposited film.

4. An adhesive layer is provided between the substrate and the heat seal layer. The laminate according to any one of claims 1 to 3, wherein the adhesive layer is composed of a polyester adhesive.

5. An intermediate layer is provided between the substrate and the heat seal layer. The laminate according to any one of claims 1 to 4, wherein the intermediate layer is made of polyester.

6. The laminate according to any one of claims 1 to 5, wherein the polyester content in the entire laminate is 75% by mass or more.

7. A laminate according to any one of claims 1 to 6, used for packaging purposes.

8. A packaging body characterized by comprising a laminate according to any one of claims 1 to 7.

Images