Gas-barrier laminate and method for manufacturing the same

Abstract

This invention relates to gas barrier laminates and their manufacturing methods. The invention provides a gas barrier laminate that is a thinner film and exhibits excellent gas barrier and aroma retention properties even after vacuum packaging in high temperature and high humidity environments. The present invention relates to a gas barrier laminate, characterized in that it comprises a plastic substrate (I) and a gas barrier layer (II) laminated on the plastic substrate, wherein the total thickness of the gas barrier laminate is less than 100 μm, (1) the plastic substrate (I) comprises a metal-containing layer, wherein the metal-containing layer comprises at least one of a metal and a metal compound and a resin component, (2) the total content of the metal and the metal compound in the metal-containing layer is 0.1 to 20% by mass, (3) the gas barrier layer (II) contains a polycarboxylic acid, (4) the metal-containing layer and the gas barrier layer are laminated in direct contact, and (5) the composite elastic modulus of the gas barrier layer (II) when the surface of the laminate is subjected to a cooking treatment of 120°C for 30 minutes is measured by nanoindentation method is 9.0 to 12.5 GPa.

Description

[0001] This application is a divisional application of the application filed on September 26, 2024, with application number 202480002760.8 and entitled "Gas Barrier Laminate and Manufacturing Method Thereof". Technical Field

[0002] This invention relates to gas barrier laminates and their manufacturing methods. Background Technology

[0003] Polyamide films and other plastic films are widely used as packaging materials due to their excellent strength, transparency, and formability. However, because these plastic films are highly permeable to oxygen, the contents of general food, cooked food, cosmetics, medical supplies, pesticides, and other products may oxidize upon contact with the permeating oxygen, leading to discoloration or a deterioration in taste.

[0004] Therefore, the plastic films used in these packaging applications need to have oxygen barrier properties, and packaging for foods containing moisture also needs to have gas barrier properties under high humidity.

[0005] As a method for imparting oxygen barrier properties to plastic films, a method of laminating a gas barrier layer on the film has been proposed. Specifically, gas barrier layers composed of polycarboxylic acid polymers, polyol polymers, and metal compounds are known to be used as gas barrier layers. For example, Patent Document 1, etc., discloses a gas barrier laminate with excellent oxygen barrier properties in a high humidity environment close to room temperature.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-185652

[0009] Patent Document 2: Japanese Patent Application Publication No. 2007-276421

[0010] Patent Document 3: International Publication WO2014 / 042133

[0011] Patent Document 4: Japanese Patent Application Publication No. 2019-151025 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] However, although the gas barrier laminate disclosed in Patent Document 1 and others has excellent gas barrier properties near room temperature, there is still room for improvement in gas barrier performance under high temperature and high humidity environments.

[0014] In recent summers, with the trend of global warming, the surrounding environment for cargo transportation is extremely hot and humid. From the perspective of inhibiting the oxidation and deterioration of contents, there is an urgent need for materials that can exhibit excellent gas barrier properties even in high temperature and high humidity environments. In particular, the gas barrier performance at high temperatures and high humidity above 40°C is receiving increasing attention.

[0015] Especially when packaging materials are used for vacuum packaging, further improvements are needed. Specifically, improvements should be made to gas barrier properties in high-temperature and high-humidity environments where localized elongation, bending, or folding has occurred.

[0016] For example, such as Figure 3 As shown in 3A, in the case of manufacturing a vacuum-packaged product by sealing food 31 (including processed products) with packaging material 32, the packaging material 32 is positioned to abut a portion of the surface of the food 31 before vacuuming. In contrast, as... Figure 3 As shown in 3B, by performing a vacuum, the packaging material 32 is sealed in a manner that follows the unevenness of the surface of the food 31. In this case, for example in Figure 3 In region A of 3B, the packaging material follows the concave shape of the food surface, resulting in localized bending and folding of the packaging material. Additionally, for example in... Figure 3 In region B of 3B, the packaging material follows the convex shape of the food surface, thereby causing the packaging material to stretch locally.

[0017] Thus, when packaging materials locally bend, fold, or stretch along the shape of the contents, the likelihood of microcracks forming at these bends, folds, or stretches, or developing microcracks over time, increases. Based on this understanding, there is a need to develop packaging materials that are durable even with localized bending, folding, and stretching.

[0018] Furthermore, packaging materials must prevent the leakage of odor components (fragrance or odor) from the contents, even in high-temperature and high-humidity environments. In such environments, the vapor pressure of odor components increases, making them more susceptible to leakage. Once the odor components leak, not only does the fragrance of the contents disappear or diminish, but the odor can also transfer to other packaging materials or other products. Therefore, packaging materials must also possess the ability to block odor components (fragrance retention).

[0019] However, in order to improve gas barrier properties, the method of thickening the gas barrier membrane is usually considered. But especially from the perspective of membrane bag-making properties, lightweight membrane products, and the perspective of reducing the volume of raw materials in recent years' environmental problems, there is a demand to develop thinner membranes.

[0020] Therefore, there is an urgent need to develop a material that, although it is a thinner membrane (especially a membrane with a total thickness of less than 100 μm), can still exhibit high gas barrier properties in high temperature and high humidity environments, but currently such a material has not yet been developed.

[0021] Therefore, the main objective of this invention is to provide a gas barrier laminate that is a thinner film and can maintain excellent gas barrier properties and aroma retention even after vacuum packaging in high temperature and high humidity environments.

[0022] Methods for solving problems

[0023] In view of the problems of these prior art, the inventors have repeatedly conducted in-depth research and found that the membrane obtained by a specific manufacturing method can achieve the above-mentioned objectives, thus completing the present invention.

[0024] That is, the present invention relates to the following gas barrier laminate and its manufacturing method.

[0025] 1. A gas barrier laminate, characterized in that it comprises a plastic substrate (I) and a gas barrier layer (II) laminated on the plastic substrate, wherein the total thickness of the gas barrier laminate is 100 μm or less.

[0026] (1) The above-mentioned plastic substrate (I) includes a metal-containing layer, wherein the metal-containing layer comprises at least one of a metal and a metal compound, and a resin component.

[0027] (2) The total content of metals and metal compounds in the above-mentioned metal-containing layers is 0.1% to 20% by mass.

[0028] (3) The above-mentioned gas barrier layer (II) contains polycarboxylic acids.

[0029] (4) The metal-containing layer and the gas barrier layer are stacked in direct contact.

[0030] (5) The composite elastic modulus of the gas barrier layer (II) after the above-mentioned laminate was subjected to a cooking treatment at 120°C for 30 minutes was measured by nanoindentation method and was 9.0 to 12.5 GPa.

[0031] 2. According to the gas barrier laminate described in item 1 above, the hardness of the gas barrier layer (II) after the laminate has been subjected to a boiling treatment at 120°C for 30 minutes is 0.7 to 1.3 GPa when measured by nanoindentation method.

[0032] 3. According to item 1 or 2 above, the gas barrier laminate, after being subjected to a boiling treatment at 120°C for 30 minutes, and simultaneously elongated by 7% in both the MD and TD directions at a rate of 1.5% / s under conditions of 35°C and 50%RH, has an oxygen permeability of 100 ml / (m³) under conditions of 40°C and 90%RH. 2 (day MPa) or below.

[0033] 4. The gas barrier laminate described in any one of items 1 to 3 above, wherein the plastic substrate (I) is composed of a multilayer film containing a metal layer.

[0034] 5. The gas barrier laminate described in any one of items 1 to 4 above, wherein the gas barrier layer (II) further contains a polyol.

[0035] 6. The gas barrier laminate according to any one of items 1 to 5 above, wherein the thickness of the gas barrier layer (II) is 0.05 to 5.00 μm, and the thickness of the plastic substrate (I) is 5 to 99.95 μm.

[0036] 7. The gas barrier laminate according to any one of items 1 to 6 above, wherein the polycarboxylic acid comprises at least one of polyacrylic acid, acrylic acid-maleic acid copolymer and olefin-maleic acid copolymer.

[0037] 8. The gas barrier laminate according to any one of items 1 to 7 above, wherein the resin component contained in the metal-containing layer comprises one or more thermoplastic resins, and the content of the resin component in the metal-containing layer is 99.9 to 80% by mass.

[0038] 9. The gas barrier laminate described in any one of items 1 to 8 above, wherein the plastic substrate (I) is composed of one or more metal-containing layers and one or more other resin-containing layers, and the ratio of the total thickness (Mt) of the metal-containing layers (M) to the total thickness (Rt) of the other resin-containing layers (R) [(Rt) / (Mt)] is 1 / 10 to 10 / 1.

[0039] 10. The gas barrier laminate described in any one of items 1 to 9 above, wherein the metal compound is at least one of lithium carbonate, sodium bicarbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium oxide, calcium carbonate, calcium hydroxide, calcium chloride, calcium phosphate, calcium sulfate, calcium acetate, zinc acetate, zinc oxide, and zinc carbonate.

[0040] 11. The gas barrier laminate described in any one of items 1 to 10 above, wherein the gas barrier layer (II) comprises an olefin-maleic acid copolymer, wherein the content of maleic acid units in the olefin-maleic acid copolymer is 5 mol% or more.

[0041] 12. The gas barrier laminate described in any one of items 1 to 11 above, wherein the metal and metal compound are in the form of powder with an average particle size of 0.005 to 5.0 μm.

[0042] 13. A packaging bag comprising the gas barrier laminate described in any one of items 1 to 12 above.

[0043] 14. A vacuum-packed product, wherein the packaging bag described in item 13 above contains and seals at least a solid component.

[0044] 15. A method for manufacturing a gas barrier laminate, characterized in that the method comprises:

[0045] (1) A step of preparing a raw material solution, wherein the raw material solution comprises a polycarboxylic acid, mineral oil, and an acetylenic diol-based nonionic surfactant, and the mass ratio of mineral oil to the acetylenic diol-based nonionic surfactant is 80 / 20 to 40 / 60; and

[0046] (2) A process of applying the above-mentioned raw material liquid as a coating liquid for forming a gas barrier layer (II) to the surface of at least the metal-containing layer of a plastic substrate (I) containing at least one of a metal and a metal compound and a resin component.

[0047] 16. The manufacturing method described in item 15 above, wherein before applying the above raw material liquid to the plastic substrate (I), the process further includes passing the above raw material liquid through a filter with a filtration accuracy of 1.0 to 10.0 μm in advance, thereby preparing a coating liquid for forming a gas barrier layer (II).

[0048] 17. The manufacturing method described in item 16 above, wherein the median particle size of the coating liquid used to form the gas barrier layer (II) after passing through the filter is 0.1 to 0.6 μm.

[0049] 18. The method for manufacturing a gas barrier laminate according to any one of items 15 to 17 above, wherein after applying the above-mentioned raw material liquid to the plastic substrate (I), the method further includes a step of subjecting the laminate coated with the above-mentioned raw material liquid to simultaneous biaxial stretching or successive biaxial stretching.

[0050] Invention Effects

[0051] According to the present invention, a gas barrier laminate is provided, which is a thinner film and can exhibit excellent gas barrier and aroma retention properties even after vacuum packaging in high temperature and high humidity environments.

[0052] In particular, in this invention, by employing a manufacturing method using a coating liquid (especially a coating liquid containing a pre-dispersion of sufficiently dispersed mineral oil) formulated with mineral oil and an acetylenol-based nonionic surfactant in a specific ratio, a unique gas barrier layer with a relatively homogeneous surface and a specific composite elastic modulus (hereinafter also simply referred to as "elastic modulus") can be formed. This unique gas barrier layer more reliably provides a gas barrier laminate that, even after being subjected to elongation during vacuum packaging or bending / folding caused by wrinkles, can maintain excellent gas barrier properties and aroma retention under harsh conditions such as high temperature and high humidity.

[0053] Thus, the gas barrier laminate of the present invention is suitable for applications such as food processing where oxygen is averse to permeability. In particular, even after elongation during vacuum packaging or bending or folding caused by wrinkles, it maintains excellent gas barrier properties and aroma retention under high temperature and high humidity environments. This ensures a longer shelf life and expiration date, and also enables long-distance and extended product transportation. Attached Figure Description

[0054] Figure 1 This is a diagram illustrating an example of the layer structure of the gas barrier laminate of the present invention.

[0055] Figure 2 This is a diagram illustrating another example of the gas barrier laminate structure of the present invention.

[0056] Figure 3 This is a schematic diagram showing the state of the contents and the packaging material when vacuum-packed products are manufactured by sealing the contents with packaging material. Detailed Implementation

[0057] 1. Gas barrier laminate

[0058] The gas barrier laminate of the present invention (the laminate of the present invention) is characterized in that it comprises a plastic substrate (I) and a gas barrier layer (II) laminated on the plastic substrate, wherein the total thickness of the gas barrier laminate is 100 μm or less.

[0059] (1) The above-mentioned plastic substrate (I) includes a metal-containing layer, wherein the metal-containing layer comprises at least one of a metal and a metal compound, and a resin component.

[0060] (2) The total content of metals and metal compounds in the above-mentioned metal-containing layers is 0.1% to 20% by mass.

[0061] (3) The above-mentioned gas barrier layer (II) contains polycarboxylic acids.

[0062] (4) The metal-containing layer and the gas barrier layer are stacked in direct contact.

[0063] (5) The composite elastic modulus of the gas barrier layer (II) after the above-mentioned laminate was subjected to a cooking treatment at 120°C for 30 minutes was measured by nanoindentation method and was 9.0 to 12.5 GPa.

[0064] exist Figure 1 An example of the layer structure of the laminate of the present invention is shown. Figure 1 In the laminate 10 of 1A, the plastic substrate 11 is composed of a single layer of a metal-containing layer 11a containing a metal or metal compound (hereinafter, unless otherwise specified, both are collectively referred to as "metal components"). A gas barrier layer 12 is laminated on the surface of the metal-containing layer 11a. Thus, through direct contact between the metal-containing layer 11a and the gas barrier layer 12, the metal component contained in the metal-containing layer 11a reacts with the polycarboxylic acid contained in the gas barrier layer 12, thereby achieving superior gas barrier properties. The reason for believing that the gas barrier properties are enhanced through this reaction is that the metal component (metal ions) in the metal-containing layer (especially in the coating film of the coating liquid for forming the gas barrier layer, as described later) moves towards the gas barrier layer. In the gas barrier layer, the carboxyl groups of the polycarboxylic acid react with the metal component, thereby forming a certain amount of cross-linked structure between the molecules of the polycarboxylic acid.

[0065] exist Figure 1 In the laminate 10' of 1B, the plastic substrate 11 is composed of multiple layers of a metal-containing layer 11a containing resin and metal components, and resin-containing layers (hereinafter also referred to as "other resin-containing layers") 11b and 11c without metal components. A gas barrier layer 12 is laminated on the surface of the metal-containing layer 11a. In this case, the metal-containing layer 11a is in direct contact with the gas barrier layer 12, allowing the metal component in the metal-containing layer 11a to react with the polycarboxylic acid contained in the gas barrier layer 12, thereby achieving superior gas barrier properties. Other resin layers in... Figure 1 1B has 2 layers, but it is acceptable as long as it has 1 layer or more.

[0066] exist Figure 1In the laminate 10'' of 1C, the plastic substrate 11 is composed of a single layer of a metal-containing layer 11a containing a metal component, and gas barrier layers 12, 12 are respectively laminated on both surfaces of the metal-containing layer 11a. In this case, the metal-containing layer 11a is in direct contact with the gas barrier layers 12, 12, thereby the metal component contained in the metal-containing layer 11a reacts with the polycarboxylic acid contained in the gas barrier layers 12, 12, thereby achieving superior gas barrier properties.

[0067] exist Figure 1 1A, Figure 1 In 1B, the metal-containing layer is always only one layer, but it can also form two or more layers. For example... Figure 2 As shown, the plastic substrate 11 is composed of multiple layers of metal-containing layers 11a, 11a, containing metal components, stacked on both sides of other resin-containing layers 11b. Alternatively, gas barrier layers 12, 12 may be stacked on the surfaces of each metal-containing layer 11a, 11a. That is, a layer structure formed by sandwiching other resin-containing layers 11b between two metal-containing layers 11a, 11a is also included in this invention. Thus, for the plastic substrate (I), a gas barrier layer (II) can be stacked on at least one side, and on the opposite side, a gas barrier layer (II) or other barrier layer can also be provided. In this way, by providing a double-sided coating formed by two metal-containing layers 11a, 11a, the gas barrier properties under high temperature and high humidity environments can be further improved. It should be noted that laminates having three or more metal-containing layers are also included in this invention.

[0068] The following is a detailed description of each layer constituting the gas barrier laminate of the present invention.

[0069] (1) Regarding each layer

[0070] (1-1) Plastic substrate

[0071] The plastic substrate functions as a supporting component of the laminate of the present invention, and also serves as a supply source for supplying the metal components to the gas barrier layer.

[0072] The plastic substrate comprises a metal-containing layer (a layer containing a metal element) containing at least one of a metal and a metal compound, as well as a resin component. Therefore, the plastic substrate can be a single layer consisting of a single metal-containing layer, or it can be a multilayer comprising a metal-containing layer and other layers. Furthermore, there can be two or more metal-containing layers.

[0073] The metal or metal compound can be used as at least one of the following: metal or metal compound, as long as it is possible to supply metal ions to the gas barrier layer to form the cross-linked structure described above. More specifically, the following metals or metal compounds can be used.

[0074] The metal (metallic element) is not limited, but from the viewpoint of gas barrier properties, monovalent metals such as lithium, sodium, potassium, rubidium, and cesium, and divalent or higher metals such as magnesium, calcium, zirconium, zinc, copper, cobalt, iron, nickel, and aluminum are preferred. Among these, from the viewpoint of readily reacting with carboxylic acids, metals with high ionization tendency are preferred. Specifically, at least one of lithium, sodium, potassium, magnesium, calcium, and zinc is preferred, and more particularly, at least one of magnesium, calcium, and zinc is preferred.

[0075] The metal constituting the metal compound is not particularly limited, but from the viewpoint of gas barrier properties, monovalent metals such as lithium, sodium, potassium, rubidium, and cesium, and divalent or higher metals such as magnesium, calcium, zirconium, zinc, copper, cobalt, iron, nickel, and aluminum are preferred. The type of metal is not limited to one, but may include two or more. From the viewpoint of readily reacting with carboxylic acids, metals with high ionization tendency are preferred. Specifically, at least one of lithium, sodium, potassium, magnesium, calcium, and zinc is preferred, and more preferably at least one of magnesium, calcium, and zinc.

[0076] The metal compound can be any compound containing the aforementioned metals, such as inorganic salts like oxides, hydroxides, halides, carbonates, bicarbonates, phosphates, and sulfates, as well as carboxylate salts like acetates, formates, stearates, citrates, malates, and maleates, and organic acid salts like sulfonates. One or more of these metals can be used.

[0077] As specific examples of the aforementioned metal compounds, at least one of the following can be used: lithium carbonate, sodium bicarbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium oxide, calcium carbonate, calcium hydroxide, calcium chloride, calcium phosphate, calcium sulfate, calcium acetate, zinc acetate, zinc oxide, and zinc carbonate. In this invention, at least one of the following is preferred: oxide, hydroxide, carbonate, bicarbonate, and acetate.

[0078] In particular, from the viewpoint of gas barrier properties, magnesium salts such as magnesium oxide, magnesium carbonate, magnesium hydroxide, and magnesium acetate are preferred; calcium compounds such as calcium carbonate and calcium acetate; and divalent metal compounds such as zinc oxide and zinc acetate.

[0079] Furthermore, from the viewpoint of ensuring the transparency of the plastic substrate (I), monovalent metal compounds such as lithium carbonate and sodium bicarbonate, and divalent metal compounds such as magnesium oxide, magnesium carbonate, and magnesium hydroxide (especially magnesium compounds) are preferred. One or more of them can be used. Among them, at least one of oxides and carbonates is particularly preferred.

[0080] In a preferred embodiment of the invention, at least one magnesium compound may be used as the metallic component. More specifically, at least one of magnesium oxide, magnesium hydroxide, and magnesium carbonate may be used.

[0081] The form of the metal component is not limited, but it is generally preferred to be in powder form. The average particle size is not particularly limited, and is generally within the range of about 0.001 to 10.0 μm, particularly more preferably 0.005 to 5.0 μm, even more preferably 0.01 to 2.0 μm, and most preferably 0.05 to 1.0 μm. From the perspective of improving the transparency of the plastic substrate (I), a small average particle size of the metal component is preferred. On the other hand, metal components with an average particle size of less than 0.001 μm tend to agglomerate due to their large surface area, and the presence of coarse agglomerates dispersed in the film can sometimes reduce the mechanical properties of the substrate. Furthermore, plastic substrates (I) containing metal components with an average particle size exceeding 10.0 μm tend to experience a higher frequency of breakage during film formation, leading to decreased productivity. Moreover, if the average particle size exceeds 10.0 μm, it may sometimes be unsuitable when the thickness of the plastic substrate (I) is thin.

[0082] Metallic particles can have their dispersibility, weather resistance, wettability with thermoplastic resins, heat resistance, and transparency improved or enhanced through surface treatments such as inorganic and organic processes. Examples of inorganic treatments include alumina treatment, silica treatment, titanium dioxide treatment, zirconium oxide treatment, tin oxide treatment, antimony oxide treatment, and zinc oxide treatment. Examples of organic treatments include those using fatty acid compounds, polyols such as pentaerythritol and trimethylolpropane, amine compounds such as triethanolamine and trimethylolamine, organosilicon resins, and organosilicon compounds such as alkylchlorosilanes.

[0083] The content of the metal component (the total content of elemental metal and metal compound) in the metal-containing layer is typically set to 0.1–20% by mass, particularly preferably 0.2–10% by mass, more preferably 0.3–5% by mass, and even more preferably 0.3–3% by mass, and most preferably 0.3–1% by mass. If the content of the metal compound in the metal-containing layer is 0.1–20% by mass, the resulting gas barrier laminate exhibits excellent gas barrier properties and aroma retention. If the content of the metal compound is less than 0.1% by mass, the cross-linking structure formed by the reaction of the gas barrier layer (II) with the polycarboxylic acid may decrease, resulting in reduced gas barrier properties of the resulting gas barrier laminate, or the hardness of the gas barrier layer (II) may fall below the preferred range, leading to reduced barrier properties after bending. On the other hand, plastic substrates (I) with a content exceeding 20% ​​by mass tend to break more frequently during film formation under stretching, which can easily reduce productivity. In addition, there is a trend that mechanical properties and transparency also decrease, and there are cases where the hardness exceeds the preferred range of the gas barrier layer (II), and the barrier properties decrease after bending.

[0084] There are no particular limitations on the method for incorporating the metal-containing layer with a metal component, and it can be incorporated at any point in the manufacturing process. Examples include: a) adding the metal component during the polymerization of the thermoplastic resin constituting the metal-containing layer; b) mixing the thermoplastic resin with the metal component using an extruder; and c) manufacturing a masterbatch by mixing the metal component into a high concentration and then adding the resulting masterbatch to the thermoplastic resin for dilution (masterbatch method). In this invention, from the viewpoint of operational efficiency, the above-described masterbatch method is preferred.

[0085] In this invention, the resin component constituting the metal-containing layer is not particularly limited, and one or more thermoplastic resins can generally be used.

[0086] Examples of thermoplastic resins include at least one selected from polyolefin resins such as polyethylene, polypropylene, and ionomers; polyamide resins such as nylon 6, nylon 66, nylon 46, nylon MXD6 (poly(m-adipamide)), and nylon 9T; polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polymethylene glycol terephthalate, polymethylene glycol naphthalate, polybutylene terephthalate, polybutylene naphthalate, polylactic acid; vinyl chloride; polystyrene resin; polycarbonate resin; polyarylate resin; ethylene-vinyl acetate copolymer; and ethylene-vinyl alcohol copolymer. Among these thermoplastic resins, at least one of polyamide resins and polyester resins is preferred. Especially when constructing packaging bags, polyamide resins (particularly nylon 6) are preferred from the perspective of superior puncture strength and impact resistance. Furthermore, from the perspective of superior heat resistance and economy, polyester resin (polyethylene terephthalate) is preferred. Therefore, these resin components can be appropriately selected according to the intended use of the laminate according to the present invention.

[0087] It should be noted that the thermoplastic resin constituting the metal-containing layer may contain any or more of the following components: biomass-derived components, chemically recycled resin components obtained by polymerizing recycled monomers or recycled oligomers obtained by depolymerizing resin waste, etc., as starting materials; material recycled resin components obtained by crushing edge trimming debris, chips, etc. generated during membrane manufacturing, or by remelting and granulating the aforementioned waste or defective membranes.

[0088] The resin content in the metal-containing layer is usually set to the remainder excluding the metal component and any additives added as needed. Therefore, in addition to being set to 99.9–80% by mass, it can also be set to 99.8–100% by mass, 99.7–95% by mass, or 99.7–99% by mass.

[0089] Within the metal-containing layer, and to the extent that it does not impair the effects of the present invention, at least one of various additives such as heat stabilizers, antioxidants, reinforcing materials, pigments, deterioration inhibitors, weathering agents, flame retardants, plasticizers, preservatives, ultraviolet absorbers, antistatic agents, and anti-blocking agents may be included as needed and to the extent that it does not adversely affect the performance of the plastic substrate (I). Furthermore, for purposes such as improving the slip properties of the plastic substrate (I), inorganic or organic lubricants other than metal components may be added to the metal-containing layer; silica is particularly preferred.

[0090] The total content of these additives is generally set to less than 5% by mass in the metal-containing layer, but is not limited to this. It should be noted that if these additives also belong to "at least one of the metals and metal compounds" in the metal-containing layer, the content of the additive is included in the content of "at least one of the metals and metal compounds".

[0091] The thickness of the metal-containing layer (single layer) is not limited. From the perspective of thickness control and reactivity with the gas barrier layer, it is usually set to a range of about 5 to 100 μm, and is particularly preferred to be set to 10 to 30 μm.

[0092] As described above, the plastic substrate (I) can be composed of a single layer containing a metal layer or a multilayer consisting of one or two or more layers containing a metal layer and other resin layers, in addition to being composed of a single layer containing a metal layer.

[0093] As for the other resin-containing layers at this time, any layer containing a thermoplastic resin is acceptable. As a thermoplastic resin, at least one of the aforementioned thermoplastic resins that can be used in the metal-containing layer can be cited. In this case, the thermoplastic resin contained in the metal-containing layer can be the same as or different from the thermoplastic resin contained in the other resin-containing layers.

[0094] Furthermore, in other resin-containing layers, at least one of the additives described above, which can be used in metal-containing layers, may be included to a extent that does not impair the effects of the present invention. In this case, the total content of the additives is generally set to about 5% by mass or less in the other resin-containing layers (each layer if there is one or more other resin-containing layers), but is not limited thereto. The other resin-containing layers can be any type of layer containing metal components or layer not containing metal components, and in particular, layers not containing metal components are also suitable. In addition, the content of the resin component in the other resin-containing layers is generally set to the remainder other than the additives described above. Therefore, for example, it can be set to about 95 to 100% by mass, but is not limited thereto.

[0095] As described above, the plastic substrate (I) can be composed of multiple layers, including other resin-containing layers, in addition to being composed of only a metal-containing layer. That is, the plastic substrate in the laminate of the present invention can be any of the following: (a) composed of one or more metal-containing layers, and (b) composed of one or more metal-containing layers and one or more other resin-containing layers.

[0096] In the case described in (b) above, there is no particular limitation on the thickness ratio of the metal-containing layer (M) to the other resin-containing layer (R). The ratio of the total thickness (Mt) of the metal-containing layer (M) to the total thickness (Rt) of the other resin-containing layer (R) [(Rt) / (Mt)] is preferably 1 / 1000 to 1000 / 1. In terms of making it easier to control the thickness of each layer, it is more preferably 1 / 100 to 100 / 1, and most preferably 1 / 10 to 10 / 1.

[0097] The thickness of the plastic substrate (I) can be appropriately selected according to the mechanical strength required for the resulting gas barrier laminate. In particular, from the perspective of mechanical strength and ease of handling, the thickness of the plastic substrate (I) can usually be set in the range of about 5 to 99.95 μm, especially preferably 5 to 50 μm, further more preferably 5 to 40 μm, and most preferably 10 to 30 μm.

[0098] (1-2) Gas barrier layer (II)

[0099] The gas barrier layer (II) constituting the laminate of the present invention contains a polycarboxylic acid. The polycarboxylic acid in the gas barrier layer (II) can exhibit gas barrier properties by reacting with the metal components in the plastic substrate (I) (the metal-containing layer).

[0100] As a polycarboxylic acid, any compound (including polymers) with two or more carboxyl groups in its molecule is acceptable. Furthermore, these carboxyl groups can form anhydride structures.

[0101] Specific examples of polycarboxylic acids include 1,2,3,4-butanetetracarboxylic acid, polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymer, acrylic acid-maleic acid copolymer, polymaleic acid, ethylene-maleic acid copolymer and other olefin-maleic acid copolymers, polysaccharides with carboxyl groups on the side chains such as alginate, carboxyl-containing polyamides, carboxyl-containing polyesters, etc. One or more of the above polycarboxylic acids may be used.

[0102] When the polycarboxylic acid is a polymer, its weight-average molecular weight is not limited, but is usually set to about 1,000 to 1,000,000, particularly preferably 10,000 to 150,000, and more preferably 15,000 to 110,000.

[0103] Furthermore, as shown in the manufacturing method described later, the polycarboxylic acid is preferably a substance obtained by neutralizing 0.1 to 20 mol% (especially 5 to 15 mol%) of the carboxyl group of the polycarboxylic acid with an alkaline compound. This results in superior gas barrier properties.

[0104] In this invention, at least one of the above-mentioned polycarboxylic acids, namely polyacrylic acid, acrylic acid-maleic acid copolymer, and olefin-maleic acid copolymer, is preferably used. Among them, olefin-maleic acid copolymer is preferred. In particular, from the viewpoint of gas barrier properties, ethylene-maleic acid copolymer (hereinafter sometimes abbreviated as "EMA") can be used appropriately.

[0105] EMA can be obtained, for example, by polymerizing maleic anhydride with ethylene using known methods such as solution radical polymerization. In the olefin-maleic acid copolymer, the maleic acid unit readily forms a maleic anhydride structure by dehydration and cyclization of adjacent carboxyl groups in a dry state, and undergoes ring-opening in a moist state or aqueous solution to form a maleic acid structure. Therefore, in this invention, unless otherwise specified, both maleic acid units and maleic anhydride units are collectively referred to as "maleic acid units".

[0106] The content of maleic acid units in EMA is not limited, but is generally preferred to be 5 mol% or more, particularly more preferably 20 mol% or more, even more preferably 30 mol% or more, and most preferably 35 mol% or more. The upper limit of the above-mentioned maleic acid unit content is not particularly limited, but is generally 90 mol% or less, particularly preferably 80 mol% or less. Furthermore, the weight-average molecular weight of EMA is not limited, but is generally preferred to be around 1,000 to 1,000,000, particularly more preferably 3,000 to 500,000, especially more preferably 7,000 to 300,000, and most preferably 10,000 to 200,000.

[0107] In the gas barrier layer (II), the polycarboxylic acid can be 100% by mass or less (e.g., 50-80% by mass, or, for example, 60-75% by mass), and other components may also be included. In this invention, polyols are particularly preferred as other components. By including polyols, the polycarboxylic acid in the gas barrier layer (II) reacts not only with the metal components in the plastic substrate (I) but also with the polyols, thus further improving the gas barrier properties. Therefore, in the gas barrier layer, the polyols may, for example, be about 20-50% by mass, preferably 25-40% by mass.

[0108] As a polyol, there is no limitation; for example, compounds having two or more hydroxyl groups within one molecule can be cited. These compounds can be any type of low-molecular-weight or high-molecular-weight compound. Furthermore, one or more of these compounds can be used.

[0109] Examples of such low-molecular-weight compounds include sugar alcohols such as glycerol and pentaerythritol, monosaccharides such as glucose, disaccharides such as maltose, and oligosaccharides such as galactooligosaccharides.

[0110] Examples of the aforementioned polymeric compounds include polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymers, and polysaccharides such as starch. The degree of saponification of the aforementioned polyvinyl alcohol and ethylene-vinyl alcohol copolymers is not limited, but is preferably 95 mol% or more, and particularly more preferably 98 mol% or more. Furthermore, the average degree of polymerization of the aforementioned polyvinyl alcohol and ethylene-vinyl alcohol copolymers is not particularly limited, but is generally preferably around 50 to 2,000, and particularly more preferably 200 to 1,000.

[0111] In this invention, these polyols can be used individually or in combination of two or more. Polyvinyl alcohol is particularly suitable for use in this invention.

[0112] The ratio of polycarboxylic acid to polyol in the gas barrier layer (II) is not limited as long as the desired effect can be obtained. It is generally preferred to be 0.01 to 20 in terms of the molar ratio of OH group to COOH group (OH group / COOH group), more preferably 0.01 to 10, particularly preferably 0.02 to 5, and most preferably 0.04 to 2.

[0113] In addition, the gas barrier layer (II) may contain at least one of polyacrylamide, polymethacrylamide, and polyamines (also collectively referred to as "polyamines, etc."). By containing these compounds, the polycarboxylic acids in the gas barrier layer (II) react with these compounds in addition to reacting with the metal components in the plastic substrate (I), thus further improving gas barrier properties and aroma retention. Known or commercially available products may be used for the polyamines, etc.

[0114] In this invention, polyamines are particularly preferred. The polyamine can be a polyamine having at least one amino group selected from primary and secondary amino groups as its amino group in the molecule. Specific examples include polyallylamine, polyvinylamine, branched polyethyleneimine, linear polyethyleneimine, polylysine, chitosan (a polysaccharide with amino groups on its side chain), and polyamides (a polyamide with amino groups on its side chain, such as polyarginine). One or more of these can be used. Furthermore, the weight-average molecular weight of the polyamine is not limited, but is generally preferred to be 5,000 to 150,000.

[0115] The mass ratio (polyamines, etc.) to polycarboxylic acids in the gas barrier layer (II) is not particularly limited, but from the viewpoint of improving gas barrier properties, it is usually preferably set to about 12.5 / 87.5 to 27.5 / 72.5.

[0116] The gas barrier layer (II) may contain a crosslinking agent. Containing a crosslinking agent improves gas barrier properties. The content of the crosslinking agent in the gas barrier layer (II) is preferably 0.1 to 30 parts by mass relative to 100 parts by mass of the polycarboxylic acid, and more preferably 1 to 20 parts by mass. Examples of crosslinking agents include a) compounds with self-crosslinking properties, and b) compounds having multiple functional groups that react with carboxyl groups within the molecule. When the gas barrier layer (II) contains a polyol, it may be a compound having multiple functional groups that react with hydroxyl groups within the molecule. Preferred crosslinking agents include at least one of isocyanate compounds, melamine compounds, urea compounds, epoxy compounds, carbodiimide compounds, zirconium salt compounds such as ammonium zirconium carbonate, and metal alkoxides.

[0117] Metal alkoxides are compounds containing a metal bonded with an alkoxy group. Other metal alkoxides include a) metal alkoxides bonded with a halogen group replacing a portion of the alkoxy group, and b) metal alkoxides bonded with an alkyl group substituted with a functional group that is reactive with a carboxyl group.

[0118] Examples of metals that can be considered as metal alkoxides include atoms of Si, Al, Ti, and Zr. It should be noted that the metals in this invention also include half-metals such as Si.

[0119] Examples of halogens include chlorine, iodine, and bromine. Examples of functional groups that are reactive with carboxyl groups include epoxy, amino, isocyanate, and urea groups. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, and isobutyl.

[0120] Specific examples of such metal alkoxides include at least one of the following: tetramethoxysilane, tetraethoxysilane, chlorotriethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-ureopropyltriethoxysilane, 3-isocyanopropyltriethoxysilane, etc.; alkoxysilane compounds such as tetraisopropoxide titanium and tetraethanoloxide titanium; alkoxyaluminum compounds such as triisopropoxyaluminum; and alkoxyzirconium compounds such as tetraisopropoxyzirconium.

[0121] These metal alkoxides can also be (a) substances which are partially or wholly hydrolyzed, (b) substances which are partially hydrolyzed and condensed, (c) substances which are completely hydrolyzed and partially condensed, or (d) substances which are combined together.

[0122] If the aforementioned metal alkoxides are mixed with polycarboxylic acids, they may sometimes react and become difficult to coat. Therefore, it is preferable to form a hydrolysis condensate before mixing. Any method known in sol-gel processes can be used to form the hydrolysis condensate.

[0123] In the gas barrier layer (II), additives such as heat stabilizers, antioxidants, reinforcing materials, pigments, deterioration inhibitors, weathering agents, flame retardants, plasticizers, release agents, lubricants, preservatives, wetting agents, viscosity modifiers, and defoamers may be included, provided that the gas barrier properties and adhesion to the plastic substrate (I) are not significantly impaired. Examples of heat stabilizers, antioxidants, or deterioration inhibitors include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, and alkali metal halides. One or more of these may be used.

[0124] In particular, examples of the aforementioned reinforcing materials include, for instance, clay, talc, wollastonite, silicon dioxide, alumina, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloons, carbon black, zeolite, montmorillonite, hydrotalcite, fluoromica, metal fibers, metal whiskers, ceramic whiskers, potassium titanate whiskers, boron nitride, graphite, glass fibers, carbon fibers, fullerenes (C60, C70, etc.), carbon nanotubes, and other inorganic or carbon-based fillers.

[0125] The total content of these additives is usually set to about 5% by mass or less in the gas barrier layer, but is not limited to this. It should be noted that if any of these additives has the same function as any of the polycarboxylic acids, polyols, polyamines, etc. that constitute the gas barrier layer, the content of the additive is set to the content of the aforementioned polycarboxylic acids, etc., and is not included in the "content of additives".

[0126] In this invention, the thickness of the gas barrier layer (II) laminated on the plastic substrate (I) is not limited. However, from the viewpoint of sufficiently improving the gas barrier properties of the elongated gas barrier laminate, it is preferably 0.05 μm or more, more preferably 0.10 μm or more, and most preferably 0.15 μm or more. Furthermore, from the perspective of suppressing performance degradation of the gas barrier layer (II) or from the perspective of economy, it is preferably 5.00 μm or less, more preferably 1.00 μm or less, and most preferably 0.50 μm or less.

[0127] (2) Layer structure and characteristics of the laminate of the present invention

[0128] (2-1) Composition of laminated bodies

[0129] The basic structure of the laminate of the present invention includes a plastic substrate (I) containing a metal layer and a gas barrier layer (II). However, as long as the metal layer (M) is in contact with the gas barrier layer (II), it can also be composed of one or more layers as described above.

[0130] Especially when the plastic substrate (I) is a multilayer film, as the laminate of the present invention, as described below, as long as the metal-containing layer (M) is in direct contact with the gas barrier layer (II), other resin-containing layers (R) may be included, without particular limitation.

[0131] a. "(R) / (M) / (II)",

[0132] b. "(M) / (R) / (M) / (II)",

[0133] c. "(II) / (M) / (R) / (II)",

[0134] d. "(II) / (M) / (R) / (M) / (II)"

[0135] These configurations effectively achieve gas barrier properties because at least the gas barrier layer (II) is in contact with the metal-containing layer (M), and the polycarboxylic acid in the gas barrier layer (II) readily reacts with the metal component in the metal-containing layer (M). Among these, the above-described "(R) / (M) / (II)" configuration is preferred when considering the equipment used for manufacturing, operability, etc.

[0136] (2-2) Characteristics of laminates

[0137] The laminate of the present invention has the following gas barrier properties, etc. It should be noted that, for the determination of gas barrier properties, the substance after the gas barrier laminate has been boiled at 120°C for 30 minutes is used as the sample for the test.

[0138] More specifically, the aforementioned cooking treatment used to determine gas barrier properties can be performed by subjecting the entire laminate to a hot water spray at 120°C for 30 minutes within a sealed container. For example, a commercially available hot water spray type, such as the "Niksaka Seisakusho RCS-100 / 10SPXG", can be used for this cooking treatment.

[0139] (2-2-1) Elastic modulus (composite elastic modulus)

[0140] For the laminate of the present invention, the laminate was subjected to a cooking treatment at 120°C for 30 minutes. The elastic modulus of the gas barrier layer (II) of the gas barrier laminate, measured by nanoindentation, was 9.0–12.5 GPa, preferably 9.5–12.0 GPa, and more preferably 10.0–11.5 GPa. Therefore, for example, in the case of vacuum packaging, even when bending or other stresses are applied to the gas barrier layer (II), it can exhibit excellent gas barrier properties and aroma retention under high temperature and high humidity conditions. That is, due to its high resistance (flexibility) to bending or other stresses applied during vacuum packaging, it can exhibit excellent gas barrier properties and aroma retention under high temperature and high humidity conditions. When the elastic modulus is less than 9.0 GPa, the thickness or quality of the gas barrier layer (II) becomes uneven, or the coating may peel off, or the cross-linking reaction may not be promoted (due to poor composition of the coating liquid in the gas barrier layer (II)). If stress is applied to the gas barrier layer (II), it may not be able to maintain excellent gas barrier properties and aroma retention under high temperature and high humidity conditions. When the elastic modulus exceeds 12.5 GPa, for the same reasons as above, when stress is applied to the barrier layer (II) as in vacuum packaging, it may sometimes not be able to maintain excellent gas barrier properties and aroma retention under high temperature and high humidity conditions. The elastic modulus here is a value measured using a nanoindenter. In addition, the elastic modulus refers to the value when an indenter is pressed into the surface of the gas barrier layer (II) of the gas barrier laminate.

[0141] (2-2-2) Hardness

[0142] The laminate of the present invention was subjected to a boiling treatment at 120°C for 30 minutes. The hardness of the gas barrier layer (II) measured by nanoindentation method is preferably 0.7 to 1.3 GPa, more preferably 0.8 to 1.2 GPa, and even more preferably 0.9 to 1.1 GPa. Therefore, even when physical stress is applied to the gas barrier layer (II) during processes such as vacuum packaging, it can exhibit excellent gas barrier properties and aroma retention under high temperature and high humidity conditions. Hardness refers to the value when an indenter is pressed into the gas barrier layer (II) of the gas barrier laminate.

[0143] (2-2-3) Oxygen permeability after elongation (temperature 40℃ and humidity 90%RH)

[0144] For the laminate of the present invention, after being subjected to a cooking treatment at 120°C for 30 minutes, and then simultaneously elongated by 7% in both the MD and TD directions at a rate of 1.5% / s under conditions of 35°C and 50%RH, the oxygen permeability of the laminate under conditions of 40°C and 90%RH is 100 ml / (m²). 2 Below ·day·MPa), preferably 80ml / (m2 Below 50 ml / (m·day·MPa), the optimal value is 50 ml / (m·day·MPa). 2 The oxygen permeability is below 10 ml / (m²). Therefore, even under physical stress such as that caused by vacuum packaging, excellent gas barrier properties and aroma retention are maintained. The lower limit of the aforementioned oxygen permeability can be set, for example, to 10 ml / (m²). 2 It is around (approximately ·day·MPa), but not limited to this.

[0145] There are no particular limitations on the apparatus used for elongation after the cooking treatment. For example, the "Karo IV" biaxial stretching apparatus for research and development manufactured by BRUCKNER can be used, which elongates by 7% simultaneously at a rate of 1.5% / s MD / TD. There are no particular limitations on the size of the specimen used for elongation, as long as it is a size that allows for the measurement of oxygen permeability (e.g., 10cm × 10cm). For the temperature and humidity during elongation, a vacuum packaging environment can be assumed, with a temperature of 35°C and a humidity of 50% RH.

[0146] For example, in vacuum-packed cooked products containing solid ingredients such as corn (vacuum-packed foods, etc.), the corn is pre-cooked (cooked raw corn) before packaging, filled into a packaging bag, and then vacuum-packed. Then, it undergoes a cooking process for sterilization. During the cooking process, heat and pressure are also applied to the packaging bag, resulting in a decrease in the strength of the packaging bag's substrate or its gas barrier properties, and a decrease in its flexibility. For the laminate of the present invention, in order to evaluate the gas barrier properties under such harsh processing conditions, it is also stretched after being subjected to the stress generated by the heat and pressure produced by the cooking process.

[0147] In particular, besides cases where the thickness or quality of the gas barrier layer (II) is uneven, defects such as peeling or poor cross-linking reactions can occur, leading to localized cracks or thinning of the gas barrier layer (II) due to elongation and / or bending, resulting in extreme reduction of gas barrier properties. In contrast, the present invention exhibits excellent gas barrier properties and aroma retention even after elongation or bending of the laminate following retort treatment, under harsh conditions such as 40°C and 90%RH. Furthermore, the present invention is a gas barrier laminate that maintains excellent gas barrier properties and aroma retention under high temperature and high humidity conditions even after vacuum packaging in applications involving hot water sterilization (boiling treatment) other than retort treatment.

[0148] (2-2-4) Oxygen permeability before elongation (temperature 40℃ and humidity 90%RH)

[0149] For the laminate of the present invention, after the laminate has been subjected to a cooking treatment at 120°C for 30 minutes, and the oxygen permeability is typically 50 ml / (m²) under the above-mentioned pre-elongation temperature of 40°C and humidity of 90%RH environment. 2 Below 40 ml / (m·day·MPa), preferably 40 ml / (m·day·MPa) 2 Below (day / MPa). The lower limit of the above oxygen permeability can be set, for example, to 1 ml / (m³). 2 It is around (approximately ·day·MPa), but not limited to this.

[0150] (2-2-5) Oxygen permeability after elongation (temperature 20℃ and humidity 90%RH)

[0151] For the laminate of the present invention, after the laminate is subjected to a cooking treatment at 120°C for 30 minutes, and then simultaneously elongated by 7% in both the MD and TD directions at a rate of 1.5% / s under conditions of 35°C and 50%RH, the oxygen permeability of the laminate under conditions of 20°C and 90%RH is typically 70 ml / (m²). 2 Below 50 ml / (m·day·MPa), preferably 50 ml / (m·day·MPa) 2 Below (day / MPa). The lower limit of the above oxygen permeability can be set, for example, to 1 ml / (m³). 2 It is around (approximately ·day·MPa), but not limited to this.

[0152] (2-2-6) Oxygen permeability before elongation (temperature 20℃ and humidity 90%RH)

[0153] For the laminate of the present invention, after the laminate has been subjected to a cooking treatment at 120°C for 30 minutes, and the oxygen permeability under the above-mentioned pre-elongation temperature of 20°C and humidity of 90%RH is typically 40 ml / (m²), 2 Below 35 ml / (m·day·MPa), preferably 35 ml / (m·day·MPa) 2 Below (day / MPa). The lower limit of the above oxygen permeability can be set, for example, to 0 ml / (m³). 2 It is around (approximately ·day·MPa), but not limited to this.

[0154] (2-2-7) Oxygen permeability after bending (temperature 20℃ and humidity 90%RH, temperature 40℃ and humidity 90%RH)

[0155] The laminate of the present invention preferably maintains high gas barrier properties even after bending. More specifically, as shown in Test Example 1 described later, a laminate (test sample) formed by laminating a 50 μm thick unstretched polypropylene film onto the gas barrier layer of the laminate of the present invention using a 4 μm thick two-component curable polyurethane adhesive layer was subjected to repeated bending fatigue testing (10 cycles) using a Gelbo Flex tester at 23°C and 50% RH according to ASTM F392. The oxygen permeability of this test sample at 20°C and 90% RH is preferably 50 ml / (m³). 2 ·day·MPa) or less, and more preferably 40ml / (m 2 Below (day / MPa). The lower limit of the above oxygen permeability can be set, for example, to 0 ml / (m³). 2 The oxygen permeability is approximately 100 ml / (m²·day·MPa), but not limited to this. Furthermore, the oxygen permeability of the test samples after the above treatment is preferably 100 ml / (m²·day·MPa) at a temperature of 40°C and a humidity of 90% RH. 2 ·day·MPa) or less, and more preferably 80ml / (m 2 Below 50 ml / (m·day·MPa), the optimal value is 50 ml / (m·day·MPa). 2 Below (day / MPa). The lower limit of the above oxygen permeability can be set, for example, to 10 ml / (m³). 2 It is around (approximately ·day·MPa), but not limited to this.

[0156] (2-2-8) Oxygen permeability evaluated based on images

[0157] As shown in Test Example 1 described later, the gas barrier properties of the laminate of the present invention can also be evaluated by image processing of the test sample after the same treatment as described above. More specifically, a test sample that had undergone 10 treatments using the Gelbo Flex tester described above was filled with a prescribed conditioning liquid (blue) in a three-side seal bag with dimensions of 100 mm width × 150 mm height, made with the sealing layer as the inner surface, and then sealed by heat sealing. The sealed three-side seal bag was subjected to a boiling treatment at 120°C for 30 minutes. Then, when the three-side seal bag was photographed on white paper, the blue-colored portion was identified in the image. This portion is where oxygen permeates due to poor gas barrier layer (II). Then, the gas barrier properties were evaluated based on the area ratio of the blue portion in the overall area of ​​the photographed three-side seal bag. The smaller the area ratio, the higher the gas barrier properties. In the gas barrier laminate of the present invention, the area ratio of the blue portion in the above evaluation method is generally preferably 0.3% or less, and more preferably less than 0.1%.

[0158] (2-2-9) Fragrance retention

[0159] The aroma retention properties of the laminate of the present invention are also excellent. That is, when the contents are sealed using the laminate of the present invention, leakage of aromatic components contained in the contents to the outside can be effectively prevented or suppressed. As a result, when food or the like is used as the contents, the aroma of the food or the like can be maintained for a longer period of time. The aroma retention properties of the present invention can be evaluated by the method shown in Test Example 1 described later. In the aroma retention properties based on this method, the concentration of leaked ethanol is preferably 0.1% by mass or less, and more preferably less than 0.5% by mass.

[0160] (2-2-10) Tensile strength

[0161] The tensile strength of the laminate of the present invention, measured in a tensile test according to Japanese Industrial Standard "JIS K7127" at 23°C and 50%RH, is preferably 150 MPa or more, and more preferably 180 MPa or more. If the tensile strength is less than 150 MPa, there is a tendency for insufficient mechanical strength and reduced puncture strength. Therefore, for example, it can be set to around 150 to 300 MPa, but is not limited thereto.

[0162] (2-2-11) Elongation at break

[0163] From the same viewpoint as tensile strength, the tensile elongation of the laminate of the present invention, measured in a tensile test at 23°C and 50% RH according to Japanese Industrial Standard "JIS K7127", is preferably 60% or more, and more preferably 80% or more. Therefore, it can be set to about 60 to 95%, for example, but is not limited thereto.

[0164] (2-2-12) Transparency

[0165] Regarding the transparency of the laminate of the present invention, the haze, measured according to Japanese Industrial Standard "JIS K7136" at an environment of 23°C and 50% RH, is preferably 70% or less, more preferably 50% or less, further preferably 30% or less, particularly preferably 15% or less, and most preferably 10% or less. However, depending on the application, transparency is sometimes not required, and therefore it is not limited to this. The lower limit of haze can be set, for example, to 1%, but is not limited to this.

[0166] (2-2-13) Resistance to pinholes

[0167] Regarding the pinhole resistance of the laminate of the present invention, the number of pinholes generated in 500 repeated bending fatigue tests at 5°C is preferably 100 or less, and more preferably 20 or less. The above-mentioned pinhole resistance is obtained by measuring and evaluating the number of pinholes generated after 500 bending cycles at 5°C using a Gelbo Flex tester (e.g., manufactured by TESTERSANGYO) according to ASTM F392. The closer the lower limit of the number of pinholes is to 0, the better; for example, it can be set to 0, but is not limited to this. It should be noted that the specimen (test area) of the laminate used in the pinhole resistance evaluation is 27cm × 20cm.

[0168] (2-2-14) Thickness

[0169] The total thickness (total thickness) of the laminate of the present invention is 100 μm or less, and can be appropriately set within this range depending on the application, etc. From the viewpoints of reducing material usage and bag-making performance, a thinner total thickness is better, particularly preferably 50 μm or less, and most preferably 30 μm or less. Furthermore, from the viewpoint of barrier properties, a thicker total thickness is better, particularly preferably 5 μm or more, and more preferably 10 μm or more. Therefore, for example, it can be set within the range of 5 to 100 μm.

[0170] 2. Method for manufacturing gas barrier laminates

[0171] The laminate of the present invention can be manufactured by any method as long as it possesses the features described above. In particular, the laminate of the present invention can be suitably manufactured by the following manufacturing method, which is a method for manufacturing a gas barrier laminate, comprising:

[0172] (1) The process of preparing the raw material liquid (raw material liquid preparation process), wherein the raw material liquid comprises a polycarboxylic acid, mineral oil and an acetylenic diol-based nonionic surfactant, and the mass ratio of mineral oil to acetylenic diol-based nonionic surfactant is 80 / 20 to 40 / 60; and

[0173] (2) A process of applying the above-mentioned raw material liquid as a coating liquid for forming a gas barrier layer (II) to the surface of at least the metal-containing layer of a plastic substrate (I) containing at least one of the metal and metal compounds and a resin component (coating process).

[0174] Raw material liquid preparation process

[0175] In the feedstock preparation process, a feedstock containing polycarboxylic acids, mineral oil, and acetylenic diol-based nonionic surfactants is prepared, wherein the mass ratio of mineral oil to acetylenic diol-based nonionic surfactants is 80 / 20 to 40 / 60.

[0176] From an operational perspective, the feed liquid is preferably aqueous (a liquid in which the solvent is an aqueous solvent). Therefore, polycarboxylic acids, as well as optional components such as polyols and polyamines, are preferably water-soluble or water-dispersible, and more preferably water-soluble.

[0177] As polycarboxylic acids, various polycarboxylic acids listed in "1. Gas Barrier Laminates" above can be used. In addition, polyols, etc., can also be the polyols listed in "1. Gas Barrier Laminates" above.

[0178] As the feedstock, an aqueous solution or aqueous dispersion of a polycarboxylic acid obtained by mixing a polycarboxylic acid with water can be used. In this case, the concentration of the polycarboxylic acid is not limited; for example, it can be set to approximately 5–30% by mass in the feedstock.

[0179] Furthermore, when using a combination of polyols to prepare an aqueous feedstock solution, the type of polyol used, the ratio of polycarboxylic acid to polyol, and additives can be as described in "1. Gas Barrier Laminate" above. In this case, it is preferable to add 0.1 to 20 equivalent percent of an alkaline compound relative to the carboxyl group of the polycarboxylic acid. If the content of the carboxyl group of the polycarboxylic acid is high, the hydrophilicity increases, so an aqueous solution can be prepared even without adding an alkaline compound. In this case, by adding an appropriate amount of alkaline compound, the gas barrier properties of the obtained gas barrier laminate can be significantly improved.

[0180] As the aforementioned alkali compound, any compound capable of neutralizing the carboxyl group of a polycarboxylic acid is acceptable. Examples include at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, ammonia, and sodium bicarbonate. From the viewpoint of enhancing gas barrier properties, the amount of alkali compound added (degree of neutralization) is generally preferably 0.1 to 20 mol% relative to the carboxyl group of the polycarboxylic acid.

[0181] In this invention, when preparing an aqueous coating solution by mixing a polycarboxylic acid with a polyamine, it is preferable to add an alkali to the polycarboxylic acid beforehand in order to suppress gelation.

[0182] As the aforementioned base, any base that does not impede the gas barrier properties of the resulting gas barrier laminate is acceptable. Examples include inorganic compounds such as sodium hydroxide, calcium hydroxide, and ammonia, and organic compounds such as methylamine and diethanolamine. One or more of these compounds may be used. Among these, ammonia is preferred from the viewpoint of being easily volatile during drying and heat treatment. From the viewpoint of suppressing gelation of the coating solution, the amount of base added is generally preferably 0.6 equivalents or more relative to the carboxyl group of the polycarboxylic acid, particularly more preferably 0.7 equivalents or more, and most preferably 0.8 equivalents or more.

[0183] In the manufacturing method of the present invention, mineral oil has the function of homogenizing the coating liquid for forming the gas barrier layer (II) described later. By distributing it evenly, it can help improve gas barrier properties and aroma retention.

[0184] There are no particular limitations on mineral oils as long as they are mixtures of petroleum-derived hydrocarbons containing hydrocarbons. For example, at least one type of hydrocarbon mineral oil from aromatic hydrocarbons, alkane hydrocarbons, and cycloalkane hydrocarbons can be used. Preferably, the average number of carbon atoms is 20 or more and 35 or less, and the oil is liquid at room temperature and pressure. Commercially available products can also be used. Examples of commercially available products include "AGITAN282" (manufactured by MUNZING CHEMIE GmbH) and "SN DEFOAMER 154S" (manufactured by San Nopco).

[0185] When adding mineral oil, in addition to water, silica particles, polyoxyethylene compounds, (meth)acrylic acid·(meth)acrylic acid alkyl ester copolymer (salt), and emulsifiers, known additives (antifreeze, waterproofing agents, film-forming regulators, etc.) and solvents can also be used in combination as needed.

[0186] The amount of mineral oil added is not limited. It is preferred to add 0.005 to 0.15 parts by mass relative to 100 parts by mass of the total (solid components) of polycarboxylic acids and polyols in the raw material liquid, more preferably 0.007 to 0.050 parts by mass, and most preferably 0.010 to 0.020 parts by mass.

[0187] Alkyne diol-based nonionic surfactants also have the function of homogenizing the coating liquid used to form the gas barrier layer (II). By making it evenly distributed, they can help improve gas barrier properties and aroma retention.

[0188] As a nonionic surfactant based on alkynyldiol, at least one of alkynyldiol compounds and their polyoxyethylene adducts can be used. It is essentially a nonionic surfactant with an acetylene group disposed in the center of the molecule and a left-right symmetrical structure with the acetylene group as the center, such as a compound with an alkynyldiol as the basic structure shown in the following general formula (1).

[0189]

Chemical Formula 1

[0190]

[0191] (wherein, R) 1 and R 2 The same or different from each other indicates methyl, propyl, or isopropyl. R 3 and R 4 The same or different from each other indicates hydroxyl or polyoxyethylene.

[0192] More specifically, examples include at least one of 3,6-dimethyl-4-decyn-3,6-diol, 2,4,7,9-tetramethyl-5-decyn-diol, and 2,4,7,9-tetramethyl-5-decyn-diol-dipolyoxyethylene ether. Among these compounds, ethylene oxide (EO) adducts are preferred. The content of the ethylene oxide moiety in the EO adduct is not limited, but is typically about 20-85% by mass, preferably 40-65% by mass.

[0193] Commercially available products can also be used as acetylenic diol-based nonionic surfactants. Examples include "OLFINE E1004", "OLFINE E1004C", "OLFINE E1006", "OLFINE E1010", "OLFINE E1020", "SURFYNOL 420", and "SURFYNOL 440" (all manufactured by Nissin Chemical Industry Co., Ltd.).

[0194] Relative to 100 parts by mass of the total (solid components) of polycarboxylic acids and polyols in the raw material liquid, the content of the acetylenic diol-based nonionic surfactant is preferably added in the form of 0.005 to 0.100 parts by mass, more preferably in the form of 0.007 to 0.050 parts by mass, and most preferably in the form of 0.010 to 0.020 parts by mass.

[0195] It should be noted that the acetylacetonate-based nonionic surfactant in the coating liquid used to form the gas barrier layer (II) may sometimes volatilize due to heat treatment after being applied to the plastic substrate (I), and may not remain in the formed gas barrier layer (II), depending on the type.

[0196] When the feed liquid contains mineral oil and acetylsyl-diol-based nonionic surfactants, one of the most important conditions is the ratio of mineral oil to acetylsyl-diol-based nonionic surfactants.

[0197] From the viewpoint of improving elongation or bending resistance, the mixing ratio (mass ratio) of mineral oil to acetylenol-based nonionic surfactant is preferably in the range of 80 / 20 to 40 / 60. Particularly preferred is 75 / 25 to 45 / 55, further preferred is 70 / 30 to 50 / 50, and most preferred is 65 / 35 to 55 / 45.

[0198] The ratio of mineral oil to acetylenol-based nonionic surfactants also affects the elastic modulus of the gas barrier layer (II). When the ratio of mineral oil exceeds 80%, the elastic modulus of the gas barrier layer (II) tends to increase, sometimes exceeding the upper limit of 12.5 GPa specified in this invention. On the other hand, when the ratio of mineral oil is less than 40%, the elastic modulus of the gas barrier layer (II) tends to decrease, sometimes failing to meet the lower limit of 9.0 GPa specified in this invention.

[0199] In addition, other additives may be included in the raw material liquid to a extent that does not impair the effects of the present invention. Examples of such additives include those listed in "1. Gas Barrier Laminate" above.

[0200] The feedstock solution can be suitably prepared by mixing the components using at least an aqueous solvent. In this case, mixing can be carried out using a dissolving vessel equipped with a stirrer. As the aqueous solvent, 1) water or 2) a mixture of water and a water-soluble organic solvent can be used. As the water-soluble organic solvent, there are no limitations; for example, monohydric alcohols such as methanol and ethanol, polyhydric alcohols such as diethylene glycol and glycerol can be used.

[0201] The mixing steps are not limited, but in the case of adding polyols, it is preferable to prepare aqueous solutions of the polycarboxylic acid and the polyol separately and mix them before application. In this case, if the above-mentioned alkaline compound is added to the aqueous solution of the polycarboxylic acid in advance, the stability of the aqueous solution can be improved.

[0202] In this invention, particularly as a method for containing mineral oil in the raw material liquid (coating liquid for forming gas barrier layer (II)), a method for preparing a pre-dispersion liquid and using it to prepare the raw material liquid can be suitable. For example, a pre-dispersion liquid obtained by diluting the mineral oil with an aqueous solution or dispersion containing a polycarboxylic acid can be used. As a result, the mineral oil (and the acetylenic diol-based nonionic surfactant) can be more uniformly dispersed in the coating liquid for forming gas barrier layer (II), resulting in a gas barrier laminate that can exhibit superior gas barrier properties and aroma retention.

[0203] There is no limitation on the method for preparing the predispersant. Examples include: (a) preparing a mixture (mixture a') that does not contain mineral oil and acetylenol-based nonionic surfactants, in addition to a mixture (mixture a) containing polycarboxylic acids but not mineral oil and acetylenol-based nonionic surfactants; using mixture a' and adding mineral oil (or mineral oil and acetylenol-based nonionic surfactants) to prepare a predispersant; and then mixing the above-mentioned mixture a with the predispersant; (b) collecting a portion of mixture a, using the collected mixture a2 to prepare a predispersant, and then mixing the remaining mixture a1 of the above-mentioned mixture a with the predispersant, etc.

[0204] Regarding the proportion of the mixture used to prepare the predispersed liquid, from the viewpoint of more reliably dispersing the mineral oil, in either case (a) or (b) above, if the total amount of the mixture contained in the feed liquid is set to 100% by mass, it is generally preferable to set it to about 0.05 to 15% by mass, and more preferably to set it to 0.1 to 5% by mass. In case (a) above, the total amount is the total amount of mixture a and mixture a'. In case (b) above, the total amount is the total amount of mixture a1 and mixture a2.

[0205] In this invention, from the viewpoints of ease of control of the composition of the mixture and manufacturing efficiency, the method described in (b) above is preferred. More specifically, a method comprising the following steps is suitable: 1) collecting a portion (mixture a2) of a mixture (mixture a) containing a polycarboxylic acid but free of mineral oil and acetylenol-based nonionic surfactants, and adding mineral oil (or mineral oil and acetylenol-based nonionic surfactants) to the collected mixture a2, thereby preparing a pre-dispersion; 2) mixing the remaining portion (mixture a1) of the above mixture with the above pre-dispersion, thereby preparing a coating liquid for forming a gas barrier layer (II). In this case, the above mixture a1 may contain mineral oil and acetylenol-based nonionic surfactants, but preferably does not contain mineral oil and acetylenol-based nonionic surfactants. Alternatively, mixture a2 may be collected in two or more portions and pre-dispersions may be prepared separately. For example, it may be divided into mixture a2 (1), mixture a2 (2), mixture a2 (3)... mixture a2 (n).

[0206] The mineral oil content in the pre-dispersion liquid is not limited as long as it is 0.005 to 0.15 parts by mass relative to 100 parts by mass of the total (solid component) of polycarboxylic acids and polyols in the raw material liquid (or coating liquid for forming gas barrier layer (II)). From the viewpoint of avoiding content errors or improving dispersibility, it can be adjusted to be 0.1 to 15 parts by mass (preferably 0.5 to 13 parts by mass, more preferably 1 to 12 parts by mass) relative to 100 parts by mass of the total (solid component) of polycarboxylic acids and polyols in the pre-dispersion liquid.

[0207] The mixer used for pre-dispersion is not particularly limited, and examples include blade mixers, high-speed rotary homogenizers, high-pressure homogenizers, and dissolvers. High-speed rotary homogenizers, high-pressure homogenizers, and dissolvers are particularly preferred, with high-speed rotary homogenizers being more preferred. The apparatus and mixing conditions used for dispersion are not particularly limited as long as they fall within the range of the median particle size determined in the particle size distribution described later. For example, it is preferable to pre-disperse at a speed of 2000 to 8000 rpm for 5 to 30 minutes using a high-speed rotary homogenizer.

[0208] Furthermore, there is no particular limitation on the method for containing an acetylenol-based nonionic surfactant in the coating liquid for forming the gas barrier layer (II). By combining and dispersing the acetylenol-based nonionic surfactant with mineral oil, the dispersion of the mineral oil can be improved. Therefore, it is preferable to combine the acetylenol-based nonionic surfactant when dispersing the mineral oil. Therefore, when combining mineral oil by the above-described pre-dispersion, it is also preferable to combine the acetylenol-based nonionic surfactant with the mineral oil.

[0209] Regarding the content of the acetylacetonate-based nonionic surfactant in the pre-dispersion liquid, it is not limited to 0.005 to 0.100 parts by mass relative to 100 parts by mass of the total (solid component) of polycarboxylic acid and polyol in the raw material liquid (or coating liquid for forming gas barrier layer (II)). From the viewpoint of improving elongation or bending resistance, it can be adjusted to 0.01 to 20 parts by mass (preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass) relative to 100 parts by mass of the total (solid component) of polycarboxylic acid and polyol in the pre-dispersion liquid.

[0210] The pre-dispersion prepared above can be used to obtain a feed solution, for example, by completely mixing with a mixture containing a polycarboxylic acid but not mineral oil and an alkynyldiol-based nonionic surfactant. In case (a) above, this mixture is equivalent to mixture a. In case (b) above, this mixture is equivalent to mixture a1. The method of mixing the two is not particularly limited, and can be carried out, for example, according to the apparatus and conditions that can be used in the pre-dispersion described above.

[0211] The obtained raw material liquid can be directly used as a coating liquid for forming the gas barrier layer (II) on a plastic substrate, or it can be used in a filtration process before coating. Preferably, the coating liquid for forming the gas barrier layer (II) can be prepared by passing the raw material liquid through a filter with a filtration accuracy (absolute filtration accuracy) of 1.0 to 10.0 μm. Surprisingly, through the above-described coating liquid preparation process, a membrane that exhibits high gas barrier properties, especially in high-temperature and high-humidity environments such as 40°C and 90%RH, can be obtained. The reason for this is not yet clear, but based on the applicant's subsequent speculation, it is believed to be as follows: By passing it through a filter, the bubbles contained in the raw material liquid can be further subdivided, and coarse particles can be removed. In addition, the condensates of polycarboxylic acids and / or polyols in the raw material liquid are subdivided, making it easier for the polycarboxylic acids to react more densely with polyols and with metal components when forming the gas barrier layer. As a result, the gas barrier layer (II) is homogeneous overall, forming a gas barrier layer (II) without defects such as pores and cracks.

[0212] From the viewpoint of suppressing the rejection or shedding of the coating liquid and forming a homogeneous gas barrier layer (II), a filter with a filtration accuracy of 1.0 to 10.0 μm is used, and a filter with a filtration accuracy of 2.0 to 5.0 μm is more preferred.

[0213] Furthermore, in this invention, to improve filtration efficiency and performance, it is preferable to pressurize the feed liquid while passing it through the filter. The pressure is typically set in the range of 0.1 to 0.3 MPa, and particularly preferably 0.15 to 0.25 MPa. If the pressure is less than 0.1 MPa, the filtration efficiency is low. On the other hand, there is a concern that the filter may be damaged if the pressure is greater than 0.3 MPa. In this invention, conventional pressurization devices (pumps, etc.) can be used as the pressurization method.

[0214] There are no particular limitations on the filter device as long as the filtration accuracy is in the range of 1.0 to 10.0 μm. For example, a filter device comprising (a) a filter housing, (b) a filter disposed in the filter housing, and (c) a pump for pressurizing and injecting the raw material liquid into the filter can be used.

[0215] As a filter (tube filter), it is suitable to use filters made of any material such as metal mesh, filter cloth, non-woven fabric laminate, resin molded body, ceramic molded body, etc. Furthermore, its shape is not limited; for example, a cylindrical filter (fish cake shape) can be used. Regarding size, for example, if it is cylindrical, it can be set to an outer diameter of approximately 50-100 mm, an inner diameter of approximately 10-30 mm, and a length of approximately 200-1000 mm, but is not limited to these. These devices can also use known or commercially available devices.

[0216] The processing method using filters can be either continuous or cyclic. Furthermore, the number of times the filter is passed through can be once or more (multi-stage). Therefore, for example, a method could be used where, after passing through a first filter with a filtration accuracy in the range of 1.0 to 10.0 μm, a second filter with a filtration accuracy in the range of 1.0 to 10.0 μm and a smaller filtration accuracy than the first filter could be used.

[0217] In this invention, the viscosity of the coating solution before passing through the filter is not particularly limited, but the viscosity measured using a type B viscometer at a liquid temperature of 25°C is preferably in the range of 5.0 to 50.0 mPa·s. By setting the viscosity of the liquid before passing through the filter within the above range, it is possible to further promote the finer separation of bubbles. In addition, it is also expected to promote the finer separation of polycarboxylic acids and / or polyol condensates. Therefore, even if the viscosity of the coating solution before passing through the filter is outside the above range, the viscosity of the coating solution can be adjusted as needed.

[0218] In this invention, the coating liquid for forming the gas barrier layer (II) is typically in the form of an aqueous dispersion (emulsion or dispersion) with an aqueous solvent. The droplet size is not limited, but from the viewpoint of homogeneity of the gas barrier layer (II), a median particle size (D50) of 0.1–0.6 μm is preferred, more preferably 0.15–0.55 μm, and most preferably 0.2–0.5 μm. When the median particle size is less than 0.1 μm, there is a high probability that mineral oil or acetylenol-based nonionic surfactants will be removed or adsorbed onto the filter when the feed liquid is passed through it, potentially resulting in a non-homogeneous gas barrier layer (II). Consequently, high gas barrier properties cannot be obtained at a temperature of 40°C and a humidity of 90% RH after elongation, leading to localized elongation and / or bending / bending, which sometimes further reduces the gas barrier properties. Furthermore, when the median particle size exceeds 0.6 μm, even if the feed solution is passed through a filter, aggregates or dissolved residues of polycarboxylic acids and / or polyols, as well as aggregates of mineral oil, will pass through the filter, causing rejection of the coating solution or coating peeling. In this case, since a homogeneous gas barrier layer (II) cannot be obtained, high gas barrier properties cannot be achieved at an elongated temperature of 40°C and a humidity of 90% RH.

[0219] Coating process

[0220] In the coating process, the gas barrier layer forming coating liquid is applied to the surface of at least the metal-containing layer of a plastic substrate (I) containing at least one of a metal and a metal compound and a resin component.

[0221] The plastic substrate (I) comprises a metal-containing layer containing at least one of a metal and a metal compound, as well as a resin component, and can be configured as described in "1. Gas Barrier Laminate" above. In particular, a plastic substrate configured with the metal-containing layer exposed can be suitable. As such a substrate, for example, a film pre-formed from a resin-containing raw material can be used. Furthermore, the manufacturing method of the plastic substrate (I) is not particularly limited, and for example, a plastic substrate (I) manufactured by the following operations can also be used.

[0222] In the case of a plastic substrate (I) formed from a single-layer film, for example, a thermoplastic resin mixed with a metal component is heated and melted in an extruder, extruded into a film shape from a T-die, and then cooled and cured on a rotating cooling drum by a known casting method such as air knife casting or electrostatic casting, to obtain an unstretched film. This can be used as the plastic substrate (I).

[0223] In the case of a plastic substrate (I) formed from a multilayered film, for example, a thermoplastic resin mixed with a metal component is heated and melted in extruder A, and another thermoplastic resin is heated and melted in extruder B. The two separately melted resins are overlapped in a die, and a film consisting of two layers, such as a metal-containing layer (M) and a resin layer (R), is extruded from a T-die. It is then cooled and cured in the same manner as described above, thereby obtaining a film in an unstretched state. This film can be used as the plastic substrate (I). In these methods, by containing metal in the plastic substrate (I), the step of laminating the metal-containing layer onto the substrate can be omitted.

[0224] Surface treatments such as corona discharge treatment can be applied to the plastic substrate (I) before the coating liquid is applied to form the gas barrier layer (II), as needed. These treatment methods can be carried out in accordance with known methods.

[0225] There is no particular limitation on the method of applying the gas barrier layer (II) to the plastic substrate (I) with the coating liquid. For example, one or a combination of two or more of the following methods can be used: air knife coating machine, kiss roll coating machine, metering bar coating machine, gravure roller coating machine, reverse roller coating machine, dip coating machine, and die coating machine.

[0226] After the gas barrier layer (II) is coated onto the plastic substrate (I) with a coating liquid, a drying process can be performed as needed to dry the coating.

[0227] There are no particular limitations on the drying method. For example, a) a method in which heat treatment is performed immediately after coating, so as to simultaneously form a dry film and perform heat treatment; b) a method in which moisture is evaporated by means of hot air blowing from a dryer or infrared irradiation after coating to form a dry film, and then heat treatment is performed.

[0228] In this invention, heat treatment is preferably performed immediately after coating, provided that the condition, gas barrier properties, and other physical properties of the gas barrier layer (II) are not specifically damaged.

[0229] There are no particular limitations on the heat treatment method; examples include heat treatment performed in a dry atmosphere such as an oven. Considering factors such as shortening the process, it is preferable to stretch the plastic substrate (I) after applying the coating liquid for forming the gas barrier layer (II). In any of the above cases, it is preferable to perform heat treatment on the plastic substrate (I) with the gas barrier layer (II) formed thereon for no more than 5 minutes in a heating atmosphere of 100°C or higher.

[0230] Furthermore, when the gas barrier layer (II) contains polycarboxylic acids and polyols, the heat treatment temperature after coating the liquid cannot be generalized, as it is also affected by their ratio, the presence or absence of added components, and the content of additives. It is generally preferred to set it to 100-300°C, more preferably 120-250°C, even more preferably 140-240°C, and most preferably 160-220°C. If the heat treatment temperature is less than 100°C, the cross-linking reaction between the polycarboxylic acid and the polyol cannot proceed sufficiently, and it is sometimes difficult to obtain a laminate with sufficient gas barrier properties. On the other hand, if the heat treatment temperature exceeds 300°C, the gas barrier layer (II) may become brittle.

[0231] The heat treatment time is generally preferably set to 5 minutes or less, more preferably 1 second to 5 minutes, even more preferably 3 seconds to 2 minutes, and most preferably 5 seconds to 1 minute. If the heat treatment time is too short, the above-mentioned cross-linking reaction cannot be fully carried out, making it difficult to obtain a laminate with gas barrier properties. On the other hand, if the heat treatment time is too long, the productivity will decrease.

[0232] The coating liquid used to form the gas barrier layer (II) applied to the plastic substrate (I) can be subjected to high-energy irradiation treatment, such as ultraviolet light, X-rays, or electron beams, before and after the aforementioned drying process. In such cases, components that are cross-linked or polymerized by high-energy irradiation can also be incorporated.

[0233] Stretching process

[0234] In this invention, as a stretching process, it is preferable to further include a process of simultaneously biaxially stretching or sequentially biaxially stretching the laminate coated with a coating liquid for forming a gas barrier layer.

[0235] The stretching method can be any of simultaneous biaxial stretching or successive biaxial stretching, with simultaneous biaxial stretching being particularly preferred. Simultaneous biaxial stretching typically balances practical properties such as mechanical properties, optical properties, thermal dimensional stability, and pinhole resistance. Furthermore, in successive biaxial stretching methods where transverse stretching follows longitudinal stretching, the increased orientation and crystallization of the film during longitudinal stretching reduces the stretchability of the thermoplastic resin during transverse stretching. Consequently, with a higher metal content, there is a tendency for the film fracture frequency to increase. Therefore, in this invention, water absorption treatment is preferably performed using simultaneous biaxial stretching.

[0236] In the case of simultaneous biaxial stretching, for example, a coating liquid for forming a gas barrier layer (II) is applied to a plastic substrate (I). After forming the gas barrier layer (II), simultaneous biaxial stretching is performed in the longitudinal direction (MD) and the transverse direction (TD) using a tenter-type simultaneous biaxial stretching machine, thereby obtaining a gas barrier laminate that has been simultaneously biaxially stretched.

[0237] In the case of successive biaxial stretching, for example, after stretching the obtained unstretched film along the longitudinal direction (MD), a gas barrier layer (II) is formed by coating with a coating liquid using the above method, and then stretching is performed along the transverse direction (TD), thereby obtaining a gas barrier laminate that has been successively biaxially stretched.

[0238] It should be noted that if the unstretched film is oriented, its stretchability may decrease in subsequent processes. Therefore, the unstretched film is preferably in an amorphous and unoriented state.

[0239] When using polyamide resin as the plastic substrate (I), it is preferable to perform a process (water absorption treatment) to allow the unstretched film to absorb water before stretching. By performing such treatment, the tensile stress is increased, and defects such as film cutting can be more effectively avoided. The method of water absorption treatment is not limited as long as it allows the unstretched film to absorb a certain amount of water, and can be any of the following: a) immersing the unstretched film in water; b) spraying water onto the unstretched film. In particular, from the perspective of more effective water absorption, the method described above (a) is preferred, and the method of immersing the unstretched film in warm water at about 30 to 80°C is even more preferred. The amount of water absorbed can be set to, for example, about 0.5 to 15 parts by weight (i.e., water absorption rate of 0.5 to 15%) of water relative to 100 parts by weight of the unstretched film, but is not limited to this. The immersion time is not limited, as long as it is set for a time sufficient to perform the water absorption of the amount described above. As a more specific method of water absorption treatment, for example, it is preferable to transfer the unstretched membrane to a water bath with the temperature adjusted to below 80°C and immerse it in the water for no more than 5 minutes (e.g., about 30 seconds to 5 minutes), thereby achieving a water absorption rate of 0.5% to 15% relative to the weight of the unstretched membrane.

[0240] The stretch ratio of the membrane is preferably 1.5 times or more in the case of uniaxial stretching, and is also preferably 1.5 times or more in both the longitudinal and transverse directions in the case of biaxial stretching. It can be set to approximately 1.5 to 4 times in the MD direction and approximately 1.5 to 4 times in the TD direction. Furthermore, the area ratio during biaxial stretching is not limited, but is generally preferably 3 times or more, particularly more preferably 6 to 20 times, and most preferably 6.5 to 13 times. On the other hand, the stretch ratio ratio (MD stretch ratio / TD stretch ratio) during biaxial stretching is not limited, but is preferably 1 / 3 to 3 / 1, more preferably 1 / 2.5 to 2.5 / 1. If the stretch ratio is within this range, a gas barrier laminate with superior mechanical properties can be obtained.

[0241] There is no limitation on the stretching temperature; for example, it can be carried out in the range of 40 to 220°C. Especially in the case of successive stretching, it is preferable to set the stretching temperature in the MD direction to 40 to 80°C and the stretching temperature in the TD direction to 80 to 150°C. In addition, in the case of simultaneous biaxial stretching, it is preferable to set it to 160 to 220°C.

[0242] The membrane that has undergone the stretching process can also undergo heat curing, relaxation, and other processes as needed. In this case, the temperature in the heat curing process can typically be set appropriately within the range of approximately 150–300°C, for example, it can be set to 200–230°C. The heat curing time can typically be varied within the range of approximately 1–30 seconds depending on the temperature, for example, it can be set to 1–5 seconds, but is not limited to this.

[0243] Furthermore, the relaxation process typically only requires relaxation in the longitudinal and / or transverse directions within a relaxation rate range of approximately 0-10% (preferably 2-6%). The temperature in the relaxation process can be appropriately set within the range of approximately 150-300°C, similar to the heat-setting process; however, to more reliably reduce the heat shrinkage rate, it is preferable to perform the relaxation process at a temperature lower than the highest temperature of the heat-setting treatment. The heat-setting and relaxation processes are preferably performed consecutively, for example, in a tenter frame after the stretching treatment.

[0244] The laminate of the present invention can also be further humidified as needed, separately from the above-mentioned water absorption treatment, particularly for the purpose of improving gas barrier properties, after any of the stretching, heat-setting, or relaxation processes. Humidification further promotes the reaction between the metallic components of the plastic substrate (I) and the polycarboxylic acid of the gas barrier layer (II). Such humidification is not limited; examples include a) exposing the laminate to a high-temperature, high-humidity atmosphere; and b) directly contacting the laminate with high-temperature water. The humidification conditions vary depending on the laminate's composition and the treatment method. When placed in a high-temperature, high-humidity atmosphere, a temperature of 30–130°C and a humidity of 50–100%RH are preferred. When in contact with high-temperature water, a temperature of approximately 30–130°C is also preferred (above 100°C is under pressure). The humidification time varies depending on the treatment conditions, but in any case, it can generally be appropriately set within the range of several seconds to hundreds of hours.

[0245] Surface treatments such as corona discharge treatment can be applied to the laminates of the present invention as needed. These treatment methods can be implemented in accordance with known methods.

[0246] 3. Applications of gas barrier laminates

[0247] In this invention, other layers may be used as long as they do not impair the effects of the invention. Such laminates are also included as laminates of this invention. Other layers are not particularly limited, and examples include substrate layers such as polyester and polyamide, sealing layers, barrier layers, antistatic layers, release layers, and printing layers. One or more of these may be used.

[0248] Examples of resins used as sealing layers include at least one from the following: low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polyethylene / polypropylene copolymer, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid / methacrylic acid copolymer, ethylene-acrylic acid / methacrylic acid copolymer, and polyvinyl acetate-based resins. Among these, polyolefin-based resins such as polyethylene, polypropylene, and polyethylene / polypropylene copolymers, which have high heat-sealing strength or inherent material strength, are preferred.

[0249] These resins can be used alone, or copolymerized or melt-blended with other resins, and can also be acid-modified. The method for forming a sealing layer on a gas barrier laminate is not limited; examples include a) laminating a film or sheet made of sealing resin onto the gas barrier laminate using an adhesive; and b) extruding and laminating the sealing resin onto the gas barrier laminate. In the former method, the film or sheet made of sealing resin can be in an unstretched state or in a low-ratio stretched state, but practically, the unstretched state is preferred.

[0250] The thickness of the sealing layer is not particularly limited, but is preferably 20 to 100 μm, and more preferably 40 to 70 μm.

[0251] As the barrier layer (other than the gas barrier layer of the laminate of the present invention), known barrier layers used in membranes can be used. For example, a polyvinylidene chloride copolymer layer or the like can be used as the barrier layer.

[0252] Regarding the laminate of the present invention, it is suitable as a packaging material for vacuum packaging applications where localized elongation stress and / or bending are easily generated during packaging, and is also suitable for hot water sterilization treatments such as boiling or steaming. Furthermore, it exhibits excellent gas barrier properties and aroma retention even in high-temperature and high-humidity environments that reduce gas barrier properties, making it suitable for long-distance transport of contents such as food or oxygen absorbers that may suffer from discoloration or deactivation due to oxidation.

[0253] In addition to the contents described above, the laminate of this invention can also be used for various food products, liquid detergents, cosmetics, chemical products, etc., in cases where a heating process with hot water or steam is required after filling and packaging. This applies to beverages, fruits, juices, water drinks, wine, cooked foods, seafood kneaded products, frozen foods, meat products, simmered dishes, bamboo shoots, corn, pickles, mochi, liquid soups, and seasonings.

[0254] When using the laminated body of the present invention as a packaging bag, its shape is not limited. For example, it can also be applied to any type of double-sided sealed bag, three-sided sealed bag, three-sided sealed bag with zipper, back sealed bag, gusset bag, folded bottom bag, stand-up bag, zipper stand-up bag, double-sided sealed bag, square flat bottom gusset bag, side sealed bag, bottom sealed bag, etc., as well as lid material for cup containers (cup products), deep-drawn packaging, etc. These packaging bags (the packaging bags of the present invention) are also included in the present invention.

[0255] In particular, even when the packaging bag of the present invention is used to make a vacuum-packed product containing solid components such as corn with uneven surfaces (e.g., surface unevenness with a step difference of more than 1 mm), the packaging bag of the present invention (the laminate of the present invention) will seal along the aforementioned uneven surfaces by drawing a vacuum. In this case, it also has durability against elongation stress and / or bending stress subjected to the laminate of the present invention, thus achieving higher gas barrier properties and aroma retention. Therefore, the present invention also includes vacuum-packed products made by using the packaging bag of the present invention to at least contain and seal solid components (especially solid components with uneven surfaces).

[0256] Example

[0257] The features of the present invention are illustrated below with examples and comparative examples. However, the scope of the present invention is not limited to the examples.

[0258] 1. Regarding the use of raw materials

[0259] The raw materials used in each embodiment and comparative example are as follows.

[0260] (1) Thermoplastic resin used to construct plastic substrate (I)

[0261] PA6: Nylon 6 resin (Unitika "A1030BRF", relative viscosity 3.0)

[0262] (2) Metal compounds used to construct plastic substrate (I)

[0263] •MgO: Magnesium oxide (PUREMAG FNM-G manufactured by Tateho Chemical Industries, average particle size 0.54 μm)

[0264] (3) A master sheet containing a metal compound used to construct a plastic substrate (I)

[0265] • Master sheet 1: Made by mixing 95 parts by weight of the above PA6 and 5 parts by weight of MgO.

[0266] • Master sheet 2: Made by mixing 75 parts by weight of the above PA6 and 25 parts by weight of MgO.

[0267] (4) The polycarboxylic acid component of the coating liquid used to form the gas barrier layer (II)

[0268] • EMA aqueous solution:

[0269] An aqueous solution of EMA (weight average molecular weight 60,000) with 15% by mass solids was prepared by adding EMA (weight average molecular weight 60,000) and sodium hydroxide to water, heating to dissolve, and then cooling to room temperature.

[0270] • PVA aqueous solution:

[0271] Polyvinyl alcohol (Kuraray 5-98, saponification degree 98-99%, average degree of polymerization about 500) was added to water, heated to dissolve, and then cooled to room temperature to prepare a 15% by mass aqueous solution of polyvinyl alcohol (PVA) with solid content.

[0272] (5) Mineral oil

[0273] • MUNZING CHEMIE GmbH's "AGITAN282" (referred to as "Mineral Oil A" in the table)

[0274] • San Nopco's "SN DEFOAMER 154S" (referred to as "Mineral Oil B" in the table)

[0275] • EVONIK's "AIRASE4655" (labeled as "vegetable oil" in the table)

[0276] (6) Surfactants

[0277] • Alkyne diol-based nonionic surfactants: "OLFINE E1004" manufactured by Nikshin Chemical Industry Co., Ltd.

[0278] • Anionic surfactant: San Nopco's "Nopco 1338"

[0279] 2. Regarding the embodiments and comparative examples

[0280] [Example 1]

[0281] Nylon 6 resin and masterbatch 1 were mixed with a magnesium oxide content of 0.5% by mass. The mixture was fed into an extruder and melted in a barrel at 270°C. The melt was extruded from a T-die into a sheet, which was then quenched by pressing it against a rotating drum cooled to 10°C, thereby obtaining an unstretched plastic substrate (I) film with a thickness of 150 μm formed of a metal-containing layer (M). The resulting unstretched film was then subjected to a 2-minute water absorption treatment in a 50°C water bath (5% water absorption rate).

[0282] Next, a mixture a is prepared by mixing PVA aqueous solution and EMA aqueous solution in a mass ratio (solid component) of 30 / 70.

[0283] Here, the pre-dispersion is prepared first. 0.15% of the total weight of the prepared mixture a is extracted (extraction rate). In this case, of the total amount of mixture a, the extracted mixture is designated as mixture a2, and the remaining mixture is designated as mixture a1.

[0284] Mineral oil (A) was mixed into mixture a2, and the acetylenol-based nonionic surfactant was incorporated into mixture a2 at a mineral oil / acetylenol-based nonionic surfactant mass ratio of 60 / 40. The amount of mineral oil and acetylenol-based nonionic surfactant added to mixture a2 relative to 100 parts by mass of the total mass (solid components) of PVA and EMA was 0.113 parts by mass of mineral oil (A) and 0.073 parts by mass of acetylenol-based nonionic surfactant.

[0285] Next, a pre-dispersion was prepared by dispersing the mixture a2 containing mineral oil (A) and acetylenic diol-based nonionic surfactant at 5000 rpm for 30 minutes using a high-speed rotary homogenizer.

[0286] The pre-dispersed liquid was then incorporated into the mixture a1, thereby obtaining a raw material liquid as an aqueous dispersion. Next, this raw material liquid was passed through a commercially available filter ("CLEAL BM FILTER, BM-03", manufactured by JNC FILTER, with a filtration precision of 3 μm) to prepare a coating liquid for forming a gas barrier layer (II) with a solid content of 10% by mass. The median droplet size of the resulting coating liquid was 0.45 μm.

[0287] Relative to the total mass (solid component) of PVA and EMA, 100 parts by mass, the contents of mineral oil and acetylation diol-based nonionic surfactant in the above raw material liquid (the above coating liquid) are 0.017 parts by mass of mineral oil and 0.011 parts by mass of acetylation diol-based nonionic surfactant, respectively.

[0288] The above-mentioned coating liquid was applied to one side of an unstretched film that had undergone water absorption treatment and then dried. The end of the unstretched film coated with the coating liquid and dried was held in the clamp of a strut stretcher and stretched to 3.3 times its original length along the MD and TD directions at 180°C. Then, with the relaxation rate of TD set to 5%, a heat treatment was performed at 210°C for 4 seconds, followed by slow cooling to room temperature, resulting in a gas barrier laminate with a thickness of 0.3 μm on a 15 μm thick plastic substrate (I) formed by a single layer of metal-containing layer (M).

[0289] [Examples 2-3, 14]

[0290] Except for setting the amount and ratio of mineral oil (A) and acetylenic diol-based nonionic surfactant as described in Table 1, the same procedure as in Example 1 was followed to obtain a gas barrier laminate.

[0291] [Example 4]

[0292] Nylon 6 resin and mother sheet 2 were fed into extruder A with a magnesium oxide content of 10% by mass and melted in a barrel at 270°C. Meanwhile, nylon 6 resin was fed into extruder B and melted in a barrel at 270°C. The two resins melted in extruders A and B were overlapped in a die, and a sheet consisting of a metal layer (M) and a resin layer (R) was extruded from a T-die. This sheet was then rapidly cooled by sealing it against a rotating drum cooled to 10°C, thereby obtaining an unstretched plastic substrate (I) film with a thickness of 150 μm and (M) / (R) = 30 / 120 μm. The unstretched plastic substrate (I) film was set as described in Table 1, and otherwise operated in the same manner as in Example 1, resulting in a gas barrier laminate.

[0293] [Examples 5 and 6]

[0294] In addition to obtaining a film of the thickness of an unstretched plastic substrate (I) formed from a metal-containing layer (M) as described in Table 1, a gas barrier laminate was obtained by operating in the same manner as in Example 1.

[0295] [Examples 7, 8, and 9]

[0296] Except for setting the magnesium oxide content of the metal-containing layer (M) in the manner described in Table 1, the same procedure as in Example 1 was followed to obtain a gas-barrier laminate.

[0297] [Examples 10 and 11]

[0298] Except that the thickness of the gas barrier layer (II) as described in Table 1 was set, the same procedure as in Example 1 was followed to obtain a gas barrier laminate.

[0299] [Examples 12 and 13]

[0300] In the composition of the coating liquid for forming the gas barrier layer (II), the neutralization degree of the polycarboxylic acid as described in Table 1 was set. Otherwise, the same procedure as in Example 1 was followed to obtain a gas barrier laminate.

[0301] [Example 15]

[0302] As shown in Table 1, using San Nopco's "SN DEFOAMER 154S" as mineral oil (B), the gas barrier laminate was obtained by operating in the same manner as in Example 1.

[0303] [Comparative Example 1]

[0304] As shown in Table 2, pure water was used instead of mixture a2 when preparing the pre-dispersion liquid. Otherwise, the same procedure as in Example 1 was followed to obtain a gas barrier laminate.

[0305] [Comparative Example 2]

[0306] As shown in Table 2, the commercially available anionic surfactant "Nopco 1338" was used instead of the alkynyl diol-based nonionic surfactant "OLFINE E1004". Otherwise, the same procedure as in Example 1 was followed to obtain a gas barrier laminate.

[0307] [Compare Examples 3 and 4]

[0308] Except for the amount and ratio of mineral oil and acetylenic diol-based nonionic surfactants as described in Table 2, the same procedure as in Example 1 was followed to obtain a gas barrier laminate.

[0309] [Comparative Example 5]

[0310] As shown in Table 2, gas barrier laminates were obtained by operating in the same manner as in Comparative Example 1, except that no alkynyl diol surfactant was added.

[0311] [Comparative Example 6]

[0312] As shown in Table 2, without pre-dispersion, mineral oil was directly added to mixture a, and otherwise the same procedure as in Example 1 was followed to obtain a gas barrier laminate.

[0313] [Comparative Example 7]

[0314] The magnesium oxide content of the metal-containing layer (M) was set in the manner described in Table 2, and pure water was used instead of mixture a2 when preparing the pre-dispersion. Otherwise, the same procedure as in Example 4 was followed to obtain a gas barrier laminate.

[0315] [Comparative Example 8]

[0316] In addition to obtaining a film with the thickness of an unstretched plastic substrate (I) formed by the thickness of the metal-containing layer (M) as described in Table 2, a gas barrier laminate was obtained by operating in the same manner as in Comparative Example 5.

[0317] [Compare Examples 9 and 10]

[0318] Except that the thickness of the gas barrier layer (II) as described in Table 2 was set, the same procedure as in Comparative Example 5 was followed to obtain a gas barrier laminate.

[0319] [Comparative Examples 11 and 12]

[0320] Except for setting the magnesium oxide content of the metal-containing layer (M) in the manner described in Table 2, the same procedure as in Comparative Example 5 was followed to obtain a gas-barrier laminate.

[0321] [Comparative Example 13]

[0322] As shown in Table 2, gas barrier laminates were obtained by operating in the same manner as in Comparative Example 5, except that the neutralization of polycarboxylic acids was not performed.

[0323] [Comparative Example 14]

[0324] In the composition of the coating liquid for forming the gas barrier layer (II), the neutralization degree of the polycarboxylic acid as described in Table 2 was set. Otherwise, the same procedure as in Comparative Example 5 was followed to obtain a gas barrier laminate.

[0325] [Comparative Example 15]

[0326] As shown in Table 2, gas barrier laminates were obtained by operating in the same manner as in Example 1, except that EVONIK plant oil "AIRASE4655" was used instead of mineral oil.

[0327] [Comparative Example 16]

[0328] As shown in Table 2, no mineral oil was added to the coating solution for forming the gas barrier layer (II), and the gas barrier laminate was obtained by operating in the same manner as in Example 1.

[0329] [Comparative Examples 17 and 18]

[0330] The amount and ratio of mineral oil and acetylsadiol-based nonionic surfactants were set as described in Table 2. Otherwise, the same procedure as in Example 1 was followed to obtain a gas barrier laminate.

[0331] [Comparative Example 19]

[0332] In addition to obtaining a film with the magnesium oxide content of the metal-containing layer (M), the thickness of the gas barrier layer (II), and the thickness of the unstretched plastic substrate (I) formed by the thickness of the metal-containing layer (M) as described in Table 2, a gas barrier laminate was obtained by operating in the same manner as in Comparative Example 5.

[0333] [Experimental Example 1]

[0334] The gas barrier laminates obtained in each embodiment and comparative example were evaluated for the following properties. The results are shown in Tables 3-4.

[0335] (1) Thickness of each layer

[0336] After the obtained gas barrier laminate was placed in an environment of 23°C and 50%RH for more than 2 hours, the membrane cross-section was observed using a scanning electron microscope (SEM) (40,000x magnification) to measure the thickness of each layer. Regarding the thickness, the thickness at any three locations was measured using the above method, and the average value is shown.

[0337] (2) The median particle size of the mineral oil droplets in the coating liquid forming the gas barrier layer (II)

[0338] The coating liquid for forming the gas barrier layer (II) to be coated before the unstretched film was used as the test sample, and the particle size distribution was measured using a laser diffraction particle size distribution measuring device (SALD-2300) manufactured by Shimadzu Corporation. The median particle size (D50) was taken as the average particle size.

[0339] (3) Elastic modulus and hardness of gas barrier layer (II) (nanoindenter)

[0340] The elastic modulus and hardness of the gas barrier layer (II) were measured using a nanoindenter (Triboindenter, Hysitron Inc.). A Berkovich indenter (triangular pyramidal indenter) (a three-sided pyramidal structure with an interior angle of 142.35°, an angle of 65.35° between the centerline and the face, and a length-to-diameter ratio of 1:8) was used as the indenter. Specifically, the elastic modulus and hardness of the gas barrier layer (II) were measured as follows: the gas barrier laminate (with the gas barrier layer (II) as the upper surface) was fixed on a glass plate, and the nanoindenter was used to indent the gas barrier layer (II) by only 10 nm at 25°C. A single indentation measurement method was used. The elastic modulus and hardness were measured at 10 arbitrary points using the above method, and their average values ​​are shown.

[0341] (4) Oxygen permeability before elongation

[0342] After subjecting the gas barrier laminates obtained in each embodiment and comparative example to a boiling treatment at 120°C for 30 minutes, the oxygen permeability was measured using a MOCON OX-TRAN 2 / 22L oxygen permeability measuring device (sample size 10.8cm × 10.8cm) at (a) a temperature of 20°C and 90% RH and (b) a temperature of 40°C and 90% RH. The unit is ml / (m³). 2 (day MPa).

[0343] (5) Oxygen permeability after elongation

[0344] After subjecting the gas barrier laminates obtained in each embodiment and comparative example to a boiling treatment at 120°C for 30 minutes, the MD / TD sections were simultaneously elongated by 7% using a research and development biaxial stretching apparatus "Karo IV" manufactured by BRUCKNER at 35°C and 50% RH. For this gas barrier laminate, the oxygen permeability was measured using an oxygen permeability measuring device (OX-TRAN 2 / 22L) manufactured by MOCON (sample size 10.8cm × 10.8cm) at (a) 20°C and 90% RH and (b) 40°C and 90% RH. The unit is ml / (m²). 2 (day MPa).

[0345] (6) Evaluation of oxygen barrier properties after bending

[0346] On the gas barrier layer (II) of the gas barrier laminate obtained in each embodiment and comparative example, a two-component curable polyurethane adhesive (DIC Graphics Co., Ltd., LX-500 / KR-90) with a coating thickness of 4 μm (when dry) was coated by gravure roller coating. A 50 μm thick unstretched polypropylene film (Mitsui Chemicals Tohcello Co., Ltd., CPP RXC-22) as a sealing layer was then dry-laminated and left to stand at 20°C and 40°C for 72 hours, respectively. Thus, a gas barrier laminate film (test sample) was produced.

[0347] The resulting laminate was subjected to 10 cycles of testing using a Gelbo Flex tester (TESTERSANGYO) at a temperature of 23°C and a humidity of 50%RH.

[0348] (6-1) Oxygen permeability

[0349] After the laminated film treated 10 times with the aforementioned Gelbo Flex tester was subjected to a boiling treatment at 120℃ for 30 minutes, the oxygen permeability was measured using a MOCON oxygen permeability measuring device (OX-TRAN 2 / 22L) (sample size 10.8cm × 10.8cm) at (a) 20℃ and 90%RH and (b) 40℃ and 90%RH. The unit is ml / (m²). 2 (day MPa).

[0350] (6-2) Evaluation of gas barrier layers based on image processing

[0351] The laminated film, processed 10 times using the aforementioned Gelbo Flex tester, was used to create a three-side seal bag with dimensions of 100mm width × 150mm height, with the sealing layer as the inner surface. After filling the bag with the following conditioning solution, the remaining side was sealed by heat sealing. The sealed three-side seal bag was then subjected to a boiling treatment at 120°C for 30 minutes, and a photograph of the three-side seal bag was taken on white paper. The blue areas in the treated three-side seal bag indicate the portions where oxygen permeated due to poor gas barrier layer (II).

[0352] The captured photos were converted to black and white using the image processing software "GIMP 2.10" (with the chroma scale setting changed to 0.0), and the area ratio of the white and black areas was calculated. The threshold for evaluating the area ratio was set to 155 out of 0-255 grayscale. The following scoring criteria were used to evaluate the defects of the curved gas barrier layer. A case where the area ratio of the blue area (oxygen permeable area) based on image processing is less than 0.1% is marked as "〇", a case where it is more than 0.1% but less than 0.3% is marked as "△", and a case where it is more than 0.3% is marked as "×".

[0353] It should be noted that the conditioning solution is prepared by adding 0.5g of methylene blue, 1.0g of mercaptoacetic acid, and 1000ml of deionized water to a container and stirring.

[0354] (7) Evaluation of aroma retention

[0355] Using the laminate obtained in the same manner as described in "(6) Evaluation of Oxygen Barrier Properties After Bending", a three-side seal bag with dimensions of 100 mm in height and 100 mm in width was made. 20 mL of a 3 wt% aqueous ethanol solution was filled into the bag for aroma retention, and the remaining side was heat-sealed. The three-side seal bag filled with the 3 wt% aqueous ethanol solution was placed into an aluminum foil bag for vacuum packaging. 100 cc of air captured by a syringe was injected into the vacuum-packed aluminum bag, and the bag was resealed. After storage at 40°C and 90% RH for one month, the concentration of ethanol leaking into the aluminum foil bag was measured using a Kitagawa-type gas sampler (manufactured by Komei Rikan Chemical Co., Ltd.). Aroma retention was evaluated according to the following scoring criteria.

[0356] Ethanol concentration less than 0.05% is recorded as “〇”, above 0.05% but below 0.1% is recorded as “△”, and above 0.1% is recorded as “×”.

[0357] Table 1

[0358]

[0359] Table 2

[0360]

[0361] Table 3

[0362]

[0363] Table 4

[0364]

[0365] According to the results in Tables 3-4, Examples 1-15 are gas barrier laminates manufactured by using a coating liquid containing mineral oil and acetylenic diol-based nonionic surfactants in a certain ratio and a pre-dispersed liquid containing mineral oil. Therefore, the surface elastic modulus of the gas barrier layer (II) after cooking meets a specific range. Even after vacuum packaging, it can exhibit excellent gas barrier properties in high temperature and high humidity environments, as well as excellent bending resistance and aroma retention.

[0366] Regarding the gas barrier laminates of Comparative Examples 1 and 7, pure water was used instead of mixture a2 when preparing the pre-dispersion liquid. Therefore, the dispersibility of mineral oil and acetylenic diol-based nonionic surfactants could not be fully obtained. The elastic modulus of the surface of the gas barrier layer (II) after cooking could not meet the specific range. As a result, the gas barrier properties under high temperature and high humidity environment after vacuum packaging could not be obtained.

[0367] Because anionic surfactants, rather than alkynyl glycol-based nonionic surfactants, were added to the gas barrier laminate of Comparative Example 2, the surface elastic modulus of the gas barrier layer (II) after cooking could not meet the specific range, and the gas barrier properties under high temperature and high humidity conditions after vacuum packaging could not be obtained.

[0368] The gas barrier laminates of Comparative Examples 5-6, 8-14, and 19 did not contain an acetylenol-based nonionic surfactant, so the surface elastic modulus of the gas barrier layer (II) after cooking could not meet the specific range, and the gas barrier properties under high temperature and high humidity conditions after vacuum packaging could not be obtained.

[0369] Since no mineral oil was added, the surface elastic modulus of the gas barrier layer (II) after the cooking treatment of the gas barrier laminates in Comparative Examples 15-16 could not meet the specific range, and the gas barrier properties under high temperature and high humidity environment after vacuum packaging could not be obtained.

[0370] On the other hand, Comparative Examples 3-4 and 17-18 are gas barrier laminates manufactured using a coating liquid that does not contain mineral oil and acetylenol-based nonionic surfactants in a certain ratio. Therefore, the elastic modulus of the surface of the gas barrier layer (II) after cooking cannot meet the specific range, and gas barrier properties under high temperature and high humidity conditions after vacuum packaging cannot be obtained.

Claims

1. A gas barrier laminate, characterized in that, The assembly comprises a plastic substrate (I) and a gas barrier layer (II) laminated on the plastic substrate, wherein the total thickness of the gas barrier laminate is less than 100 μm. (1) The plastic substrate (I) comprises a metal-containing layer, the metal-containing layer comprising at least one of a metal and a metal compound, and a resin component. (2) The total content of metal and metal compound in the metal-containing layer is 0.1% to 20% by mass. (3) The gas barrier layer (II) contains polycarboxylic acids. (4) The metal-containing layer and the gas barrier layer are stacked in direct contact. (5) The composite elastic modulus of the gas barrier layer (II) after the laminate was subjected to a cooking treatment at 120°C for 30 minutes was measured by nanoindentation and was found to be 9.0 GPa to 12.5 GPa. (6) The hardness of the gas barrier layer (II) after the laminate was subjected to a cooking treatment at 120°C for 30 minutes was measured by nanoindentation method and was 0.7 GPa to 1.3 GPa.

2. The gas barrier laminate according to claim 1, wherein, The laminate was subjected to a cooking treatment at 120°C for 30 minutes, and then elongated by 7% simultaneously in both the MD and TD directions at a rate of 1.5% / s under conditions of 35°C and 50%RH. The oxygen permeability of the laminate at 40°C and 90%RH was 100 ml / (m³). 2 (day MPa) or below.

3. The gas barrier laminate according to claim 1, wherein, The plastic substrate (I) is composed of a multilayer film containing a metal layer.

4. The gas barrier laminate according to claim 1, wherein, The gas barrier layer (II) also contains polyols.

5. The gas barrier laminate according to claim 1, wherein, The thickness of the gas barrier layer (II) is 0.05 μm to 5.00 μm, and the thickness of the plastic substrate (I) is 5 μm to 99.95 μm.

6. The gas barrier laminate according to claim 1, wherein, The polycarboxylic acid comprises at least one of polyacrylic acid, acrylic acid-maleic acid copolymer, and olefin-maleic acid copolymer.

7. The gas barrier laminate according to claim 1, wherein, The resin component contained in the metal-containing layer comprises one or more thermoplastic resins, and the content of the resin component in the metal-containing layer is 99.9% to 80% by mass.

8. The gas barrier laminate according to claim 1, wherein, The plastic substrate (I) is composed of one or more metal-containing layers and one or more other resin-containing layers. The ratio of the total thickness (Mt) of the metal-containing layers (M) to the total thickness (Rt) of the other resin-containing layers (R) is (Rt) / (Mt) and is 1 / 10 to 10 / 1.

9. The gas barrier laminate according to claim 1, wherein, The metal compound is at least one of lithium carbonate, sodium bicarbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium oxide, calcium carbonate, calcium hydroxide, calcium chloride, calcium phosphate, calcium sulfate, calcium acetate, zinc acetate, zinc oxide, and zinc carbonate.

10. The gas barrier laminate according to claim 1, wherein, The gas barrier layer (II) comprises an olefin-maleic acid copolymer, wherein the content of maleic acid units in the olefin-maleic acid copolymer is more than 5 mol%.

11. The gas barrier laminate according to claim 1, wherein, The metals and metal compounds are in the form of powder, with an average particle size of 0.005 μm to 5.0 μm.

12. A packaging bag comprising a gas barrier laminate according to any one of claims 1 to 11.

13. A vacuum-packed product, wherein, The packaging bag according to claim 12 contains and seals at least a solid component.

14. A method for manufacturing a gas barrier laminate, characterized in that, A method for manufacturing a gas barrier laminate, the manufacturing method comprising: (1) A step of preparing a raw material solution, wherein the raw material solution comprises a polycarboxylic acid, mineral oil, and an acetylenic diol-based nonionic surfactant, and the mass ratio of mineral oil to the acetylenic diol-based nonionic surfactant is 80 / 20 to 40 / 60; and (2) A step of applying the raw material liquid as a coating liquid for forming a gas barrier layer (II) onto the surface of at least said metal-containing layer of a plastic substrate (I) containing at least one of a metal and a metal compound and a resin component.

15. The manufacturing method according to claim 14, wherein, Before applying the raw material liquid to the plastic substrate (I), the process further includes a step of pre-passing the raw material liquid through a filter with a filtration accuracy of 1.0 μm to 10.0 μm to prepare a coating liquid for forming a gas barrier layer (II).

16. The manufacturing method according to claim 15, wherein, The median particle size of the coating liquid used to form the gas barrier layer (II) after passing through the filter is 0.1 μm to 0.6 μm.

17. The method for manufacturing a gas barrier laminate according to claim 14, wherein, After applying the raw material liquid to the plastic substrate (I), the process further includes a step of subjecting the laminate coated with the raw material liquid to simultaneous biaxial stretching or successive biaxial stretching.

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