Gas adsorption film

Abstract

To provide a gas adsorption film capable of exhibiting sufficient gas adsorption ability in high-humidity conditions.SOLUTION: The present invention relates to a gas adsorption film including, sequentially, a substrate layer (A), a porous metal complex layer (B), and a protective layer (C), the protective layer (C) having a free volume radius of 0.265-0.400 nm. The gas adsorption film is preferably an ethylene adsorption film, making it suitable for packaging fruits and vegetables.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to gas adsorption films and their applications. [Background technology]

[0002] Conventionally, in the fields of food, pharmaceuticals, electronic components, precision machinery, recording materials, etc., gas adsorbents have been incorporated into packages or storage containers to prevent quality deterioration due to harmful gases. Known harmful gases include, for example, ammonia, sulfur dioxide, and organic gases derived from organic solvents such as acetone and benzene.

[0003] Ethylene, a harmful gas, is produced by fruits and vegetables and is known as a plant hormone that promotes ripening and aging of plant tissues. It is believed that the production of ethylene is a major cause of the loss of freshness of fruits and vegetables during storage and transportation after harvest. Therefore, to maintain the freshness of fruits and vegetables, it is important to remove or decompose ethylene and prevent it from coming into contact with harvested fruits.

[0004] Various methods for removing or decomposing ethylene have been investigated. For example, Patent Document 1 discloses a freshness-maintaining material composition that maintains the freshness of fresh produce such as fruits and vegetables by suppressing their deterioration, and that contains cyclodextrin. Furthermore, Patent Document 2 discloses a plastic functional film capable of adhering ethylene to its surface, which contains a substance with catalytic function that decomposes ethylene into carbon dioxide and water and enables them to be released from one side of the film to the other side.

[0005] Porous materials such as activated carbon, silica gel, zeolite, and porous metal complexes are sometimes used for deodorization and gas separation and purification, and the use of such materials for ethylene removal is also being considered. For example, Patent Document 3 discloses an ethylene adsorbent characterized by being made of a synthetic zeolite powder or molded body having palladium supported thereon by an ion exchange method and having an SiO2 / Al2O3 ratio of 10 or more. Patent Document 4 also discloses an adsorption sheet containing organic fibers and a porous metal complex having a porous structure formed by metal ions and organic ligands capable of binding to the metal ions. Furthermore, Patent Document 5 discloses an adsorption sheet containing organic fibers and a porous metal complex having a porous structure formed by metal ions and organic ligands capable of binding to the metal ions. 10 H8N4)] n Patent Document 6 discloses an ethylene gas adsorbent comprising a porous coordination polymer complex having a chemical structure with the basic structural unit of (I), and Patent Document 6 discloses an ethylene gas adsorbent comprising a porous metal complex or a metal-supported inorganic porous material. The adsorbent sheet disclosed in Patent Document 4 is a fiber sheet formed by a wet papermaking method, while the ethylene adsorbents disclosed in Patent Documents 3 and 5 are powders. In addition, in the ethylene gas adsorbent disclosed in Patent Document 6, the ethylene gas adsorbent is mixed and dispersed in a thermoplastic resin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-170368 [Patent Document 2] International Publication No. 2017 / 135433 [Patent Document 3] Japanese Patent Application Publication No. 10-043583 [Patent Document 4] International Publication No. 2013 / 115033 [Patent Document 5] Japanese Patent Application Laid-Open No. 2004-322005 [Patent Document 6] Japanese Patent Publication No. 2022-001357 Summary of the Invention [Problem to be solved by the invention]

[0007] As mentioned above, methods for removing harmful gases such as ethylene by adsorbing the gases onto zeolites, porous metal complexes, etc. have been investigated. However, conventional gas adsorption films sometimes fail to exhibit sufficient gas adsorption capacity, particularly in high-humidity environments, and improvements have been required.

[0008] Therefore, in order to solve the problems of the conventional technology, the present inventors have carried out investigations with the aim of providing a gas adsorption film that exhibits sufficient gas adsorption capacity in a high humidity environment. [Means for solving the problem]

[0009] Examples of specific embodiments of the present invention are given below.

[0010] [1] A substrate layer (A), a porous metal complex layer (B), and a protective layer (C) are provided in this order; A gas adsorption film in which the free volume radius of the protective layer (C) is 0.265 to 0.400 nm. [2] The gas adsorption film according to [1], wherein the surface roughness Ra of the protective layer (C) is 0.5 or less. [3] The gas adsorption film according to [1] or [2], wherein the porous metal complex layer (B) has a thickness of 0.1 to 10 μm. [4] The gas adsorption film according to any one of [1] to [3], further comprising an anchor layer (D) between the substrate layer (A) and the porous metal complex layer (B). [5] The gas adsorption film according to [4], wherein the anchor layer (D) contains a polar group-containing polymer or an organic onium compound. [6] The gas adsorption film according to [4] or [5], wherein the anchor layer (D) has an arithmetic mean height Sa of 0.1 to 20 μm. [7] The gas adsorption film according to any one of [1] to [6], wherein the protective layer (C) contains low-density polyethylene. [8] The gas adsorption film according to any one of [1] to [7], wherein the porous metal complex layer (B) contains at least one porous metal complex selected from the group consisting of HKUST-1 (Cu / 1,3,5-benzenetricarboxylic acid), Mg-MOF-74 (Mg / 2,5-dihydroxyterephthalic acid), MOF-505 / GO (Cu / 3,3,5,5-biphenyltetracarboxylic acid), MOF-5 / G (Zn / 1,4-benzenedicarboxylic acid), Zr-MOF (Zr / 1,4-naphthalenedicarboxylic acid), MIL-101 (Cr / 1,4-benzenedicarboxylic acid), Co-MOF74 (Co / 2,5-dihydroxyterephthalic acid), and Ni-MOF-74 (Ni / 2,5-dihydroxyterephthalic acid). [9] The gas adsorption film according to any one of [1] to [8], which is an ethylene adsorption film.

[10] The gas adsorption film according to any one of [1] to [9], which is used for packaging fruits and vegetables.

[11] A method for packaging fruits and vegetables, which comprises covering the fruits and vegetables with the gas adsorption film according to any one of [1] to

[10] , with the protective layer (C) facing inward. [Effects of the Invention]

[0011] According to the present invention, a gas adsorption film that exhibits sufficient gas adsorption ability in a high-humidity environment can be obtained. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view illustrating the structure of the gas adsorption film of this embodiment. [Figure 2] FIG. 2 is a cross-sectional view illustrating the structure of the gas adsorption film of this embodiment. [Figure 3] FIG. 3 shows data comparing the moisture resistance of the gas adsorption films of the examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. The following description of the constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, the expression "X to Y" (X and Y are arbitrary numbers) means "X or more and Y or less," unless otherwise specified, and also includes "preferably greater than X" or "preferably less than Y." Furthermore, the expression "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number) also includes the meaning "preferably greater than X" or "preferably less than Y." In the following description, the terms "film" and "sheet" are not clearly distinguished from each other, and the term "film" includes the term "sheet," and the term "sheet" includes the term "film."

[0014] (gas adsorption film) This embodiment relates to a gas adsorption film (hereinafter also referred to as the present gas adsorption film) comprising a substrate layer (A), a porous metal complex layer (B), and a protective layer (C) in this order, with the protective layer (C) having a free volume radius of 0.265 to 0.400 nm. As shown in Fig. 1, the present gas adsorption film 10 comprises a substrate layer 2, a porous metal complex layer 6, and a protective layer 8 in this order. Other layers may be provided between the substrate layer 2, the porous metal complex layer 6, and the protective layer 8, as needed.

[0015] The gas adsorption film of this embodiment, having the above-described structure, can exhibit excellent gas adsorption ability, particularly even when placed in a high-humidity environment.

[0016] For example, gas adsorption capacity can be evaluated by calculating the amount of ethylene adsorption using the following method. Specifically, first, the gas adsorption film is cut to a predetermined size (e.g., 5 cm x 9 cm), placed in a glass bottle, and sealed. Next, standard ethylene gas is injected into the glass bottle so that the ethylene gas concentration in the bottle becomes 100 ppm. Immediately, 1 mL of gas is sampled from the glass bottle and the ethylene concentration is measured by gas chromatography. After one hour, 1 mL of gas is sampled again from the glass bottle and the ethylene concentration is measured. The amount of ethylene adsorbed by the gas adsorption film is calculated from the difference. Furthermore, the same measurement is performed without the gas adsorption film to determine the amount of ethylene leaked from the glass bottle during the one hour period, and this amount is subtracted from the amount of ethylene adsorbed by the gas adsorption film. That is, the amount of ethylene adsorption can be calculated using the following formula. Amount of ethylene adsorption (ppm / g / h) = Initial ethylene concentration (ppm) - Ethylene concentration after 1 hour in the glass bottle containing the gas adsorption film (ppm) - Amount of ethylene leaked from the glass bottle (ppm)

[0017] The ethylene adsorption amount (ppm / g / h) calculated by the above method is preferably 0.8 ppm / g / h or more, more preferably 0.9 ppm / g / h or more, even more preferably 1.0 ppm / g / h or more, still more preferably 1.5 ppm / g / h or more, even more preferably 2.0 ppm / g / h or more, still more preferably 2.5 ppm / g / h or more, and particularly preferably 3.0 ppm / g / h or more. The upper limit of the ethylene adsorption amount (ppm / g / h) calculated by the above method is not particularly limited and may be, for example, 100 ppm / g / h.

[0018] Furthermore, when a gas adsorption film is placed in a high-humidity environment (an environment of 80% relative humidity and 25°C temperature) for 24 hours, the ethylene adsorption capacity can be evaluated by measuring the amount of ethylene adsorbed by the gas adsorption film before and after it absorbs moisture in the high-humidity environment. The amount of ethylene adsorption before moisture absorption is calculated in the same manner as above. The amount of ethylene adsorption after moisture absorption is evaluated using a gas adsorption film after being placed in a high-humidity environment (an environment of 80% relative humidity and 25°C temperature) for 24 hours. In this specification, moisture resistance can be calculated using the following formula, and a larger value for moisture resistance (%) indicates less deterioration in ethylene adsorption capacity in a high-humidity environment. Moisture resistance [%] = (ethylene adsorption amount after moisture absorption (ppm / g / h) / ethylene adsorption amount before moisture absorption (ppm / g / h)) × 100

[0019] Specifically, the ethylene adsorption amount (ppm / g / h) after moisture absorption of the gas adsorption film after leaving it in an environment of 80% relative humidity and 25°C temperature for 24 hours is preferably 0.8 ppm / g / h or more, more preferably 0.9 ppm / g / h or more, even more preferably 1.0 ppm / g / h or more, still more preferably 1.5 ppm / g / h or more, even more preferably 2.0 ppm / g / h or more, still more preferably 2.5 ppm / g / h or more, and particularly preferably 3.0 ppm / g / h or more. The upper limit of the ethylene adsorption amount (ppm / g / h) after moisture absorption is not particularly limited and may be, for example, 100 ppm / g / h.

[0020] Furthermore, the moisture resistance calculated by the above formula is preferably 26% or more, more preferably 30% or more, even more preferably 35% or more, even more preferably 40% or more, still more preferably 45% or more, and particularly preferably 50% or more. The upper limit of the moisture resistance is not particularly limited, and may be 100% or more.

[0021] This gas adsorption film includes a porous metal complex layer as a gas adsorption layer. Porous metal complexes have a larger specific surface area than activated carbon or zeolite, and therefore exhibit excellent gas adsorption capacity. Previously, the use of powders of porous metal complexes as adsorbents for gases such as ethylene has been investigated. However, when forming powdered gas adsorbents into sheets, the gas adsorbent and resin are typically mixed and then formed into a sheet. In such cases, the gas adsorption sites are blocked by the resin, making it difficult to obtain a sheet with excellent gas adsorption capacity. Furthermore, porous metal complexes have low moisture stability, making it difficult to maintain their gas adsorption capacity in high-humidity environments. For example, when gas adsorption films are used to package fresh produce, moisture dissipation from the fresh produce can reduce the gas adsorption capacity of the gas adsorption film. For this reason, the present inventors conducted research aimed at producing a gas adsorption film having a porous metal complex layer with excellent gas adsorption capacity even in high-humidity environments. The present inventors have found that by using the layer structure of this embodiment, a gas adsorption film having moisture resistance can be obtained without inhibiting the gas adsorption sites of the porous metal complex.

[0022] As described above, the gas adsorption film has excellent moisture resistance due to the inclusion of a specific protective layer. Such excellent moisture resistance can be expected regardless of the type of adsorbed gas. Adsorbed gases are not limited to ethylene gas; examples include carbon dioxide, alkanes, alkenes, hydrogen, acetone, ethanol, ammonia, cyanogen chloride, sulfur dioxide, and other gases. Equivalent moisture resistance is expected for these gases. Furthermore, by appropriately controlling the size of the voids (adsorption sites) formed in the three-dimensional structure of the porous metal complex that constitutes the porous metal complex layer, it is possible to achieve a size suitable for the target gas to be adsorbed. In particular, the gas adsorption film is preferably one that adsorbs ethylene gas, and the gas adsorption film is preferably an ethylene adsorption film.

[0023] The total light transmittance of the gas adsorption film is not particularly limited, but is preferably 70% or more, more preferably 75% or more, and even more preferably 80% or more. The upper limit of the total light transmittance of the gas adsorption film is not particularly limited, and may be 100%. If the total light transmittance of the gas adsorption film is within the above range, the smoothness and design properties of the gas adsorption film can be improved, and the visibility of the contents can also be improved. The total light transmittance of the gas adsorption film is a value measured in accordance with JIS K 7136:2000.

[0024] The haze of the gas adsorption film is not particularly limited, but is preferably 70% or less, more preferably 60% or less, even more preferably 50% or less, even more preferably 40% or less, and particularly preferably 30% or less. The lower limit of the haze of the gas adsorption film is not particularly limited, and may be 0%. If the haze of the gas adsorption film is within the above range, the design of the gas adsorption film can be improved, and the visibility of the contents can also be improved. The haze of the gas adsorption film is a value measured in accordance with JIS K 7136:2000.

[0025] The total thickness of the gas adsorption film is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. The total thickness of the gas adsorption film is preferably 3000 μm or less, more preferably 2000 μm or less, and even more preferably 1500 μm or less. By keeping the total thickness of the gas adsorption film within the above range, the gas adsorption capacity can be more effectively improved.

[0026] This embodiment may also relate to a rolled body obtained by rolling up a gas adsorption film. Because this gas adsorption film has appropriate strength and flexibility, it can be stored or distributed in the form of a roll.

[0027] (Base material layer (A)) The gas adsorption film has a substrate layer. The type of substrate layer is not particularly limited, and examples include layers formed from synthetic polymers, woven fabrics, nonwoven fabrics, metal foils, paper, cellophane, glass, and the like. The type of substrate layer is appropriately selected depending on the application of the gas adsorption film. For example, when the gas adsorption film is used as a packaging material for fruits and vegetables, the substrate layer preferably has a certain degree of flexibility, and a resin layer is preferably used. Furthermore, when the gas adsorption film is required to have light-blocking properties, it is possible to use a metal foil as the substrate layer.

[0028] When the substrate layer is a resin layer, examples of the resin constituting the resin layer include polyolefins (e.g., polyethylene, polypropylene), polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate, polylactic acid), polyamides (e.g., nylon 6, nylon 66, nylon 610), polyvinyl chloride, polyvinylidene chloride, fluororesins, epoxy resins, acrylic resins, polyurethanes, silicone resins, phenolic resins, polyetherimides, polyimides, polyvinyl alcohol, polystyrene, cellulose-based resins, polycarbonates, etc. From the viewpoint of environmental conservation, it is also preferable to form the substrate layer from a biodegradable resin or a biomass resin.

[0029] When the substrate layer is a resin layer, the resin layer may be a transparent resin layer, a semi-transparent resin layer, or an opaque resin layer. The resin layer may also be a foamable resin layer. Furthermore, the resin layer may be printed.

[0030] The substrate layer may be subjected to a surface treatment. Examples of the surface treatment include corona treatment, flame treatment, and plasma treatment. By subjecting the substrate layer to a surface treatment, the interlayer adhesion between the substrate layer and the anchor layer can be more effectively improved.

[0031] The thickness of the substrate layer is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more. Furthermore, the thickness of the substrate layer is preferably 1000 μm or less, more preferably 900 μm or less, and even more preferably 800 μm or less. By setting the thickness of the substrate layer within the above range, the strength of the gas adsorption film can be increased and film formability can be improved. The substrate layer may have a single-layer structure or a multilayer structure having multiple layers. In the case of a multilayer structure, it is preferable that the thickness of each layer be within the above range.

[0032] The substrate layer may contain various additives. Examples of additives include antibacterial agents, antioxidants, ultraviolet absorbers, near-infrared absorbers, lubricants, antistatic agents, foaming agents, plasticizers, colorants, pH adjusters, opacifying agents, oils, flame retardants, near-infrared absorbers, and color correctors. The substrate layer may also contain zeolite or activated carbon as an ethylene adsorbent.

[0033] (Porous metal complex layer (B)) The gas adsorption film has a porous metal complex layer. The porous metal complex layer is a layer containing a porous metal complex (Porous Coordination Polymer or Metal Organic Framework: MOF). The content of the porous metal complex in the porous metal complex layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The content of the porous metal complex in the porous metal complex layer may be 100% by mass, and the porous metal complex layer may be a layer made of the porous metal complex. In this embodiment, the porous metal complex has been successfully formed into a membrane, and therefore, as described above, a porous metal complex layer with a high content of the porous metal complex can be formed.

[0034] In porous metal complexes, metals and organic ligands form coordination bonds to form a coordination network, resulting in a three-dimensional structure with a higher specific surface area than activated carbon or zeolites. Self-organization of the metal and organic ligands in porous metal complexes forms a crystalline framework, resulting in a high density of coordinatively unsaturated metal cations (adsorption sites), which can selectively interact with and adsorb gas components such as ethylene.

[0035] The metal (metal ion) contained in the porous metal complex is preferably at least one metal (metal ion) selected from metals belonging to groups 1 to 13 of the periodic table. The metal contained in the porous metal complex is preferably at least one selected from the group consisting of titanium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, zirconium, magnesium, calcium, vanadium, cadmium, and chromium, more preferably at least one selected from the group consisting of iron, copper, zinc, aluminum, and magnesium, and even more preferably at least one selected from the group consisting of copper and magnesium. The metal contained in the porous metal complex may be one type or two or more types.

[0036] The organic ligand constituting the porous metal complex is preferably an organic compound having two or more sites capable of forming a coordinate bond with the metal in the molecule, and the organic ligand is preferably an organic compound that forms a coordination network with the metal to form a porous structure having a plurality of pores capable of accommodating gas components such as ethylene.

[0037] The organic ligand is preferably an anionic ligand. Here, the anionic ligand means a ligand whose coordinated site to the metal is anionic. Examples of the organic ligand include sulfonic acids such as trifluoromethanesulfonic acid and benzenesulfonic acid; formic acid, acetic acid, trifluoroacetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, cyclohexanecarboxylic acid, caprylic acid, octylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, α-linolenic acid, eicosanoid acid, and the like. Aliphatic monocarboxylic acids such as sapentaenoic acid, docosahexaenoic acid, linoleic acid, and oleic acid; aromatic monocarboxylic acids such as benzoic acid, 2,5-dihydroxybenzoic acid, 3,7-dihydroxy-2-naphthoic acid, 2,6-dihydroxy-1-naphthoic acid, and 4,4'-dihydroxy-3-biphenylcarboxylic acid; heteroaromatic monocarboxylic acids such as nicotinic acid and isonicotinic acid; aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and fumarate; and 1,3-benzenedicarboxylic acid. aromatic dicarboxylic acids such as 1,4-benzenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and 2,5-dihydroxyterephthalic acid; heteroaromatic dicarboxylic acids such as 2,5-thiophenedicarboxylic acid, 2,2'-dithiophenedicarboxylic acid, 2,3-pyrazinedicarboxylic acid, 2,5-pyridinedicarboxylic acid, and 3,5-pyridinedicarboxylic acid; 1,3,5-benzenetricarboxylic acid; Examples of the aromatic carboxylic acids include carboxylic acids, aromatic tricarboxylic acids such as 1,3,4-benzenetricarboxylic acid and biphenyl-3,4',5-tricarboxylic acid; aromatic tetracarboxylic acids such as 1,2,4,5-benzenetetracarboxylic acid, [1,1':4',1'']terphenyl-3,3'',5,5''-tetracarboxylic acid and 5,5'-(9,10-anthracenediyl)diisophthalate; and heterocyclic compounds such as imidazolate, 2-methylimidazolate and benzimidazolate.

[0038] Among these, the organic ligand preferably has at least one functional group selected from the group consisting of a carboxy group, a hydroxy group, an amino group, and a sulfonic acid group, and particularly preferably has a carboxy group. That is, the organic ligand is preferably at least one selected from the group consisting of an aliphatic monocarboxylic acid, an aromatic monocarboxylic acid, a heteroaromatic monocarboxylic acid, an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, a heteroaromatic dicarboxylic acid, an aromatic tricarboxylic acid, and an aromatic tetracarboxylic acid, more preferably at least one selected from the group consisting of an aromatic monocarboxylic acid, a heteroaromatic monocarboxylic acid, an aromatic dicarboxylic acid, a heteroaromatic dicarboxylic acid, an aromatic tricarboxylic acid, and an aromatic tetracarboxylic acid, and particularly preferably at least one selected from the group consisting of 1,3,5-benzenetricarboxylic acid, 1,4-benzenedicarboxylic acid, and 2,5-dihydroxyterephthalic acid. The organic ligand contained in the porous metal complex may be one type or two or more types.

[0039] The organic ligand preferably has a ring structure, and more preferably has a benzene ring. Organic ligands having a ring structure tend to have high molecular symmetry, and therefore are more likely to form the skeleton of a porous metal complex. Furthermore, when the organic ligand has a ring structure, the ring can be easily modified with a functional group, making it easier to impart various functionalities to the porous metal complex layer.

[0040] The organic ligands described above may further have a substituent. The substituent is not particularly limited, but examples thereof include alkyl groups (straight-chain or branched alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and pentyl), halogen atoms (fluorine, chlorine, bromine, and iodine), alkoxy groups (methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, and tert-butoxy), and amino groups. , monoalkylamino groups (such as a methylamino group), dialkylamino groups (such as a dimethylamino group), formyl groups, epoxy groups, acyloxy groups (such as an acetoxy group, an n-propanoyloxy group, an n-butanoyloxy group, a pivaloyloxy group, or a benzoyloxy group), alkoxycarbonyl groups (such as a methoxycarbonyl group, an ethoxycarbonyl group, or an n-butoxycarbonyl group), nitro groups, cyano groups, hydroxy groups, acetyl groups, and trifluoromethyl groups.

[0041] Specific examples of porous metal complexes include HKUST-1 (Cu / 1,3,5-benzenetricarboxylic acid), Mg-MOF-74 (Mg / 2,5-dihydroxyterephthalic acid), MOF-505 / GO (Cu / 3,3,5,5-biphenyltetracarboxylic acid), MOF-5 / G (Zn / 1,4-benzenedicarboxylic acid), Zr-MOF (Zr / 1,4-naphthalenedicarboxylic acid), MIL-101 (Cr / 1,4-benzenedicarboxylic acid), Co-MOF74 (Co / 2,5-dihydroxyterephthalic acid), and N Examples include i-MOF-74 (Ni / 2,5-dihydroxyterephthalic acid). For example, MOF-505 / GO and Mg-MOF-74 adsorb carbon dioxide, ammonia, octane gas, and sulfur dioxide, HKUST-1 and MIL-101 adsorb ethylene gas, Cu-BTC adsorb ethylene gas and ethanol gas, MOF-5 / GO adsorb ethanol gas, Zr-MOF adsorbs hydrogen gas, Co-MOF74 adsorbs ammonia and cyanogen chloride gas, and Ni-MOF-74 adsorbs cyanogen chloride gas.

[0042] Among these, the porous metal complex preferably contains at least one metal ion selected from the group consisting of iron, copper, zinc, aluminum, and magnesium, and at least one organic ligand selected from the group consisting of 1,3,5-benzenetricarboxylic acid, 1,4-benzenedicarboxylic acid, and 2,5-dihydroxyterephthalic acid. Examples of such porous metal complexes include HKUST-1 (Cu / 1,3,5-benzenetricarboxylic acid) and Mg-MOF-74 (Mg / 2,5-dihydroxyterephthalic acid).

[0043] The thickness of the porous metal complex layer is preferably 0.1 μm or more, more preferably 0.3 μm or more, even more preferably 0.5 μm or more, even more preferably 0.7 μm or more, and particularly preferably 1 μm or more. The thickness of the porous metal complex layer is preferably 10 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, and particularly preferably 3 μm or less.

[0044] Increasing the density of the porous metal complex layer improves its gas adsorption capacity for ethylene and other gases; however, in conventional technology, it has been difficult to form a high-density porous metal complex layer on a substrate layer. Furthermore, when attempting to increase the density of the porous metal complex layer, the interlayer adhesion with the substrate layer and the strength of the porous metal complex layer itself tend to be poor, resulting in a trade-off between improved gas adsorption capacity and improved interlayer adhesion. However, in this embodiment, by forming a predetermined anchor layer on the substrate layer, the density of the porous metal complex layer has been successfully increased. Furthermore, in this embodiment, excellent interlayer adhesion is exhibited even when the density of the porous metal complex layer is increased.

[0045] In this embodiment, the porous metal complex layer may have a needle-shaped crystal structure (metal hydroxide nanostructure). That is, the gas adsorption film of this embodiment may include a substrate layer, an anchor layer, and a porous metal complex layer containing a needle-shaped crystal structure (metal hydroxide nanostructure). In this embodiment, the needle-shaped crystal structure (metal hydroxide nanostructure) is a precursor formed in the process of forming a porous metal complex layer by a method described below. At least a portion of the needle-shaped crystal structure (metal hydroxide nanostructure) is converted into a porous metal complex, but in this embodiment, some of the needle-shaped crystal structure (metal hydroxide nanostructure) formed in the manufacturing process may remain in the porous metal complex layer. When the porous metal complex layer contains a needle-shaped crystal structure (metal hydroxide nanostructure), the radius (cross-sectional radius) of the needle-shaped crystal structure (metal hydroxide nanostructure) is preferably, for example, 10 to 1000 nm, and the length is preferably 1 to 500 μm.

[0046] (Protective layer (C)) The gas adsorption film has a protective layer. In this embodiment, the protective layer is both moisture-resistant and gas-permeable. That is, the protective layer is impermeable to water vapor, but allows gas components such as ethylene to pass through. In this embodiment, by providing a protective layer on the porous metal complex layer, it is possible to prevent the porous metal complex from falling off from the porous metal complex layer, thereby improving the safety of the gas adsorption film during use.

[0047] The free volume radius of the protective layer is preferably 0.265 nm or more, more preferably 0.280 nm or more, and even more preferably 0.290 nm or more. The free volume radius of the protective layer is preferably 0.400 nm or less, more preferably 0.380 nm or less, and even more preferably 0.360 nm or less. By setting the free volume radius of the protective layer within the above range, the protective layer can exhibit excellent moisture resistance and excellent gas permeability.

[0048] The free volume radius of the protective layer can be measured using, for example, a compact positron lifetime measurement device (PALS-200A, manufactured by Fuji Invac Co., Ltd.) Specifically, a gas adsorption film is attached to a silicon wafer, and after vacuum degassing at 25°C, the positron annihilation lifetime is measured under the following conditions. Positron source: 2 2 Na-based positron annihilation Gamma-ray detector: BaF2 scintillator and photomultiplier tube Beam intensity: 7 keV or 9 keV Measurement temperature: 25℃ Measurement atmosphere: vacuum Total count: Approximately 5,000,000 counts Then, a 3-4 component analysis is performed on the obtained positron annihilation lifetime curve using the nonlinear least squares program POSITRONFIT, and the annihilation lifetimes are designated τ1, τ2, τ3, and τ4 in descending order of their annihilation lifetimes.The free volume radii R3 and R4 are calculated using the following equation from the average annihilation lifetimes τ3 and τ4, which capture the free volume radii on the sub-nm order. τ3=(1 / 2)[1-{R3 / (R3+0.166)}+(1 / 2π)sin{2π R3 / (R3+0.166)}]-1 τ4=(1 / 2)[1-{R4 / (R4+0.166)}+(1 / 2π)sin{2π R4 / (R4+0.166)}]-1

[0049] The water vapor permeability of the protective layer is 50g / m 2 / day or less, and 40 g / m 2 / day or less is more preferable, and 30 g / m 2 / day or less is more preferable, and 20 g / m 2 The lower limit of the water vapor transmission rate of the protective layer is not particularly limited, but it is preferably 1 g / m 2 / day or more. The water vapor transmission rate is measured under the conditions of 40°C and 100cm 2It can be measured by the Mocon method using a water vapor transmission rate measuring device (MOCON, PERMATRAN-W 3 / 34G) under conditions of 90% relative humidity. The Mocon method is a method for evaluating the amount of trace water vapor transmitted using an infrared sensor.

[0050] The oxygen permeability of the protective layer is 300 ml / m 2 ·day·MPa or more is preferable, and 500ml / m 2 ·day·MPa or more is more preferable, and 800ml / m 2 ·day·MPa or more is more preferable, and 1000ml / m 2 The upper limit of the oxygen permeability of the protective layer is not particularly limited, but is, for example, 100,000 ml / m 2 The oxygen permeability is measured under the conditions of 20°C and 100cm 2 It can be measured under conditions of 90% relative humidity using an oxygen permeability measuring device (MOCON, OX-TRAN 2 / 22) that uses the isobaric method. The isobaric method maintains equal air pressure on both sides of the sample, and oxygen molecules that permeate due to the partial pressure difference are detected by a coulometric sensor.

[0051] The surface roughness Ra (JIS B0601:2013) of the protective layer is preferably 0.5 μm or less, more preferably 0.4 μm or less, and even more preferably 0.3 μm or less. The lower limit of the surface roughness Ra of the protective layer is not particularly limited, but is preferably 0.0 μm or more, for example. The surface roughness Ra of the protective layer is a value measured using a laser microscope. By setting the surface roughness Ra of the protective layer within the above range, the transparency of the gas adsorption film can be more effectively improved. This can improve the visibility of the contents when packaging the contents in the gas adsorption film, for example.

[0052] Examples of the protective layer include metal foil, metal vapor deposition layer, inorganic oxide vapor deposition layer, carbon-containing inorganic oxide vapor deposition layer, and resin layer, with a resin layer being preferred. Examples of the resin layer include polyolefin, polystyrene, ethylene-vinyl acetate copolymer, polyoxyethylene, polycarbonate, polyvinyl chloride, polyethylene terephthalate, and polyamide. Forming the protective layer from the above resins makes it easy to keep the free volume radius of the protective layer within a predetermined range. The type of protective layer can be appropriately selected depending on the type of gas to be adsorbed by the porous metal complex layer.

[0053] In particular, the protective layer preferably contains polyolefin as a main component resin. Examples of polyolefin include polyethylene, polypropylene, polybutene, their mutual copolymers, and ionomer resins. In particular, the protective layer is preferably at least one selected from the group consisting of polyethylene, polypropylene, and their mutual copolymers.

[0054] The polyolefin content in the protective layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The polyolefin content in the protective layer may be 100% by mass, or the protective layer may be a layer consisting of polyolefin only.

[0055] When the gas to be adsorbed is ethylene, the protective layer preferably contains polyethylene. Examples of polyethylene contained in the protective layer include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). These may be used alone or in combination of two or more. Among these, the protective layer preferably contains at least one selected from linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE), and particularly preferably contains low-density polyethylene (LDPE).

[0056] The density of low-density polyethylene (LDPE) is 0.94 g / cm 3 Preferably, it is 0.93 g / cm or less. 3 More preferably, it is 0.92 g / cm or less. 3 It is more preferable that the density of low density polyethylene (LDPE) is 0.89 g / cm or less. 3 It is preferable that the concentration is 0.90 g / cm or more. 3 More preferably, it is 0.91 g / cm or more. 3 By setting the density within the above range, the moisture resistance and gas permeability of the protective layer can be more effectively improved.

[0057] The MFR (JIS K6922-2:2018, measurement temperature 190°C, measurement load 21.17N) of the low-density polyethylene (LDPE) is preferably 0.1 g / 10 min or more, more preferably 0.2 g / 10 min or more. The MFR of the low-density polyethylene (LDPE) is preferably 20.0 g / 10 min or less, more preferably 15.0 g / 10 min or less. By setting the MFR within the above range, the moisture resistance and gas permeability of the protective layer can be more effectively improved.

[0058] The melting point (JIS K7121:1987) of the low-density polyethylene (LDPE) is preferably 85°C or higher, more preferably 90°C or higher, and even more preferably 95°C or higher. The melting point of the low-density polyethylene (LDPE) is preferably 125°C or lower, more preferably 120°C or lower, and even more preferably 115°C or lower. By setting the melting point within the above range, moldability can be improved, and adhesion to the porous metal complex layer (B) can be improved.

[0059] The sheet containing low-density polyethylene may be a commercially available product, such as Taiko Polyethylene Film LL-XHT #25 manufactured by Futamura Chemical Co., Ltd., but is not limited thereto.

[0060] The thickness of the protective layer is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. The thickness of the protective layer is preferably 35 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less. By setting the thickness of the protective layer within the above range, moisture resistance and gas permeability can be more effectively improved. The protective layer may have a single-layer structure or a multilayer structure having multiple layers. In the case of a multilayer structure, it is preferable that the thickness of each layer be within the above range.

[0061] In addition to low-density polyethylene (LDPE), the protective layer may further contain a resin that is incompatible with low-density polyethylene. Examples of incompatible resins include, but are not limited to, styrene-based resins, vinyl-based resins, and acrylic-based resins. The protective layer may also contain additives. Examples of additives include colorants, inorganic fillers, organic fillers, ultraviolet absorbers, light stabilizers, heat stabilizers, antioxidants, lubricants (slip agents), anti-blocking agents, hydrolysis inhibitors, plasticizers, and flame retardants.

[0062] (Anchor layer (D)) The gas adsorption film may further include an anchor layer (D) between the substrate layer (A) and the porous metal complex layer (B). As shown in Fig. 2, the gas adsorption film 10 may include a substrate layer 2, an anchor layer 4, a porous metal complex layer 6, and a protective layer 8, in this order. Other layers may be provided between the substrate layer 2, the anchor layer 4, the porous metal complex layer 6, and the protective layer 8, as needed. However, in this embodiment, the substrate layer 2 and the anchor layer 4 are preferably directly laminated together, and the anchor layer 4 and the porous metal complex layer 6 are also preferably directly laminated together.

[0063] The anchor layer preferably contains a polar group-containing polymer or an organic onium compound. The content of the polar group-containing polymer or the organic onium compound in the anchor layer is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, and even more preferably 35% by mass or more.

[0064] In this embodiment, the provision of an anchor layer can more effectively improve the interlayer adhesion between the base layer and the porous metal complex layer. The interlayer adhesion can be evaluated, for example, by attaching an adhesive tape (Nichiban Co., Ltd.'s "Cellotape (registered trademark)") to the surface of the gas adsorption film facing the porous metal complex layer and then peeling it off, and then checking whether the adhesive tape remains adhesive.

[0065] The polar group contained in the polar group-containing polymer is not particularly limited, and examples thereof include a carboxy group, a hydroxy group, an amino group, an isocyanate group, an imino group, a (meth)acrylate group, and a sulfonic acid group. Of these, the polar group-containing polymer is preferably a hydrophilic polymer. The polar group-containing polymer is preferably at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyethyleneimine, polyacrylic acid, sodium polyacrylate, poly(4-styrenesulfonic acid), sodium poly(4-styrenesulfonate), and polyallylamine hydrochloride, and more preferably polyvinyl alcohol. Of these, polyvinyl alcohol that becomes insoluble in aqueous solvents upon reaction with a crosslinking agent is preferred. Examples of polyvinyl alcohol that becomes insoluble in aqueous solvents upon reaction with a crosslinking agent include polyvinyl alcohols modified with silanol groups, epoxy groups, acetoacetyl groups, amino groups, ammonium groups, sulfonic groups, carboxy groups, and the like.

[0066] The organic onium compound is an onium compound having at least one hydrocarbon group, and examples thereof include organic ammonium compounds and organic phosphonium compounds. Examples of the organic ammonium compound include quaternary ammonium halides having a hydrocarbon group and their salts, and examples of the organic phosphonium compound include quaternary phosphonium halides having a hydrocarbon group and their salts. Specific examples of the organic onium compound include polydiallyldimethylammonium and polydiallyldimethylammonium chloride.

[0067] The water contact angle of the surface of the anchor layer in contact with the porous metal complex layer is preferably 50° or less, more preferably 45° or less, even more preferably 40° or less, even more preferably 35° or less, and particularly preferably 30° or less. The lower limit of the water contact angle of the surface of the anchor layer in contact with the porous metal complex layer is not particularly limited, as long as it is 0° or more. By setting the water contact angle of the anchor layer within the above range, the interlayer adhesion with the porous metal complex layer can be more effectively improved. Furthermore, the fact that the water contact angle of the surface of the anchor layer in contact with the porous metal complex layer is within the above range means that the anchor layer is hydrophilic. That is, the anchor layer preferably contains a hydrophilic polymer, and the polar group-containing polymer is preferably a hydrophilic polymer.

[0068] The arithmetic mean height Sa of the surface of the anchor layer in contact with the porous metal complex layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, even more preferably 2 μm or more, even more preferably 3 μm or more, and particularly preferably 4 μm or more. The arithmetic mean height Sa of the anchor layer is preferably 20 μm or less, more preferably 15 μm or less, even more preferably 12 μm or less, even more preferably 10 μm or less, and particularly preferably 8 μm or less. The arithmetic mean height Sa of the surface of the anchor layer in contact with the porous metal complex layer can be measured using a laser microscope ("OPTELICS HYBRID+" manufactured by Lasertec) in accordance with ISO 25178.

[0069] In this embodiment, the anchor layer preferably contains at least one type of particles selected from organic particles and inorganic particles, which makes it easier to control the arithmetic mean height Sa within a predetermined range.

[0070] In this embodiment, it is preferable to form a fine uneven structure in the anchor layer so as to achieve the above-mentioned arithmetic mean height Sa. The fine uneven structure is formed, for example, by incorporating at least one type of particle selected from organic particles and inorganic particles into the anchor layer. Forming such a fine uneven structure in the anchor layer can more effectively improve the interlayer adhesion between the porous metal complex layer and the anchor layer, and between the anchor layer and the base layer. Increasing the interlayer adhesion between the anchor layer and the porous metal complex layer facilitates thickening of the porous metal complex layer. Furthermore, forming such a fine uneven structure in the anchor layer can increase the specific surface area of ​​the porous metal complex layer. By thickening the porous metal complex layer and / or increasing the specific surface area of ​​the porous metal complex layer, the ethylene adsorption capacity of the porous metal complex layer can be more effectively improved.

[0071] The average particle diameter (average primary particle diameter) of the organic particles and inorganic particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, even more preferably 1.5 μm or more, and particularly preferably 2 μm or more. The average particle diameter of the organic particles and inorganic particles is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The average particle diameter (average primary particle diameter) of the organic particles and inorganic particles can be determined by measuring the diameters of 10 or more particles using a scanning electron microscope (SEM) and averaging the results. When the cross-sectional shape of the particles is not circular (e.g., elliptical), the average of the longest and shortest diameters is used as the diameter of each particle.

[0072] Examples of organic particles that the anchor layer may contain include fine particles made of resins, naturally occurring components, sugars, chemically synthesized components, etc. Examples of organic particles include fine particles of acrylic resins, polystyrene, polysiloxane, melamine resins, benzoguanamine resins, polytetrafluoroethylene, polycarbonate, polyamide, chitin, chitosan, dextrin, oligosaccharides, wheat starch, rice starch, corn starch, potato starch, dextrin, cyclodextrin, lactose, glucose, sugar, reduced maltose, sorbitol, erythritol, xylitol, lactitol, mannitol, lactic acid bacteria, and casein.

[0073] Examples of inorganic particles that can be contained in the anchor layer include fine particles made of metals, alloys, metal oxides, metal nitrides, glass, rock components, inorganic compounds, and components produced by chemical synthesis. Examples of inorganic particles include zeolite, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, carbon black, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, silica, aluminum hydroxide, alumina, alumina hydrate, aluminosilicate, boehmite, pseudo-boehmite, and iron oxide. Among these, the inorganic particles are preferably at least one selected from the group consisting of metals, alloys, metal oxides, and metal nitrides, more preferably metal oxides, and particularly preferably silica particles.

[0074] The above-mentioned particles may be used alone or in combination of two or more kinds. Also, organic particles and inorganic particles may be used in combination, or particles of the same kind but different particle diameters may be used in combination.

[0075] The thickness of the anchor layer is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 50 nm or more. The thickness of the anchor layer is preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 400 nm or less. As will be described later, when the anchor layer is a multilayer structure consisting of two or more layers, it is preferable that the thickness of each anchor layer is within the above range. The thickness of the anchor layer can be determined by observing the cross section with a scanning electron microscope (SEM), measuring the thickness at any five or more points, and averaging the measurements.

[0076] In this embodiment, the anchor layer may have a single-layer structure, but may also have a multi-layer structure consisting of two or more layers. For example, the gas adsorption film of this embodiment may include two anchor layers.

[0077] When the gas adsorption film has two anchor layers, the first anchor layer preferably functions as an adhesive layer, and the second anchor layer preferably contains a polar group-containing polymer or an organic onium compound as described above. In this case, the first anchor layer preferably contains an adhesive resin. Examples of adhesive resins include polyolefins such as polyethylene, polyethyleneimine, polypropylene, and ethylene-propylene copolymers, polyesters, polyamides, ionomers, ethylene-vinyl acetate copolymers, acrylic resins such as acrylates and methacrylates, polyvinyl acetal, phenolic resins, modified epoxy resins, and copolymers or mixtures thereof. Among these, the adhesive resin is preferably at least one selected from the group consisting of polyethyleneimine, polyvinyl acetal, and modified epoxy resins.

[0078] The adhesive resin may be a thermoplastic elastomer, such as a styrene-based elastomer, an olefin-based elastomer, a urethane-based elastomer, a polyester-based elastomer, a nitrile-based elastomer, an amide-based elastomer, a polybutadiene-based elastomer, an acrylic-based elastomer, or a vinyl chloride-based thermoplastic elastomer.

[0079] The anchor layer may further contain a silane coupling agent, such as those having an epoxy group such as 3-glycidoxypropyltrimethoxysilane, those having an amino group such as 3-aminopropyltrimethoxysilane, those having a mercapto group such as 3-mercaptopropyltrimethoxysilane, and those having an isocyanate group such as 3-isocyanatepropyltriethoxysilane.

[0080] Furthermore, the anchor layer may contain various additives, such as antibacterial agents, antioxidants, ultraviolet absorbers, near-infrared absorbers, lubricants, and antistatic agents.

[0081] (arbitrary layer) The gas adsorption film may include other optional layers in addition to the protective layer, porous metal complex layer, anchor layer, and substrate layer. An example of an optional layer is a printed layer. The printed layer can be provided as the outermost layer of the substrate layer or between the substrate layer and the anchor layer. The printed layer can display patterns such as letters and designs. The printed layer contains, for example, a urethane-based, acrylic-based, nitrocellulose-based, rubber-based, or vinyl chloride-based ink binder resin, as well as additives such as various pigments, plasticizers, desiccants, and stabilizers. Examples of methods for forming the printed layer include well-known printing methods such as offset printing, gravure printing, and silk screen printing, and well-known coating methods such as roll coating, knife-edge coating, and gravure coating.

[0082] (Method of manufacturing gas adsorption film) This embodiment relates to a method for producing a gas adsorption film, which includes the steps of applying a solution in which a metal hydroxide is dispersed onto a substrate layer and converting the metal hydroxide into a porous metal complex to form a porous metal complex layer, and forming a protective layer on the porous metal complex layer. In this embodiment, the porous metal complex layer is preferably a layer formed by converting a metal hydroxide into a porous metal complex.

[0083] Furthermore, this embodiment preferably relates to a method for producing a gas adsorption film, which includes the steps of: forming an anchor layer containing a polar group-containing polymer or an organic onium compound on a substrate layer; applying a solution of a metal hydroxide dispersed on the anchor layer and converting the metal hydroxide into a porous metal complex to form a porous metal complex layer; and forming a protective layer on the porous metal complex layer. By providing the anchor layer, the interlayer adhesion between the substrate layer and the porous metal complex layer can be more effectively improved.

[0084]

[0042] In the following, as one embodiment of the method for producing a gas adsorption film, a manufacturing process for forming an anchor layer on a substrate layer will be described. When an anchor layer on a substrate layer is not formed, the step of forming an anchor layer containing a polar group-containing polymer or an organic onium compound may be omitted, and a porous metal complex layer may be formed on the substrate layer.

[0085] The step of forming an anchor layer containing a polar group-containing polymer or an organic onium compound on a substrate layer preferably includes a step of applying an anchor layer-forming composition to the substrate layer. The anchor layer-forming composition preferably contains a polar group-containing polymer or an organic onium compound and a solvent to enhance coatability. The anchor layer-forming composition can be applied by any known coating method, including, for example, dip coating, dipping, roll coating, gravure coating, reverse coating, air knife coating, comma coating, die coating, screen printing, spray coating, and gravure offset.

[0086] A drying step is preferably carried out after the step of applying the anchor layer-forming composition onto the base layer. Drying methods that can be used include, for example, hot air drying, heat roll drying, high-frequency irradiation, infrared irradiation, and UV irradiation. When a heat drying method is employed in the drying step, the heating temperature is not particularly limited, but it is preferable to dry at, for example, 60 to 140°C.

[0087] Before the step of applying the anchor layer-forming composition onto the substrate layer, a step of surface-treating the substrate layer may be performed. Examples of surface treatment methods include corona treatment, flame treatment, and plasma treatment. By performing a surface treatment on the substrate layer, the interlayer adhesion between the substrate layer and the anchor layer can be more effectively improved.

[0088] After the anchor layer is formed on the substrate layer, a step of coating the anchor layer with a solution of dispersed metal hydroxide and converting the metal hydroxide into a porous metal complex to form a porous metal complex layer is preferably carried out. In this step, the anchor layer is first coated with a solution of dispersed metal hydroxide to form a coating film of metal hydroxide on the anchor layer. The metal constituting the metal hydroxide is preferably at least one selected from the group consisting of titanium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, zirconium, magnesium, calcium, vanadium, cadmium, and chromium.

[0089] The solution in which the metal hydroxide is dispersed preferably contains a solvent. The solvent may be an organic solvent, water, or a mixture thereof. Specifically, methanol, ethanol, propanol, diethyl ether, dimethoxyethane, tetrahydrofuran, hexane, cyclohexane, heptane, benzene, toluene, methylene chloride, chloroform, acetone, ethyl acetate, acetonitrile, N,N-dimethylformamide, water, or a mixture thereof.

[0090] The step of forming the porous metal complex layer preferably includes the steps of applying a solution in which a metal hydroxide is dispersed onto an anchor layer to form a coating film, and immersing the coating film in a solution containing an organic ligand to form the porous metal complex layer. The coating film containing metal hydroxide is a film containing metal hydroxide nanostructures (metal hydroxide nanobelts), and by immersing such a coating film in a solution containing an organic ligand, the metal hydroxide nanostructures (metal hydroxide nanobelts) are converted into a porous metal complex layer.

[0091] Examples of the organic ligand include the organic ligands described above. The solution containing the organic ligand preferably contains a solvent. The solvent may be any of the solvents described above. The solution containing the organic ligand may be water, alcohol, or a mixed solvent thereof. Such solvents have low toxicity, and therefore the burden on the environment can be reduced.

[0092] From the viewpoint of facilitating the formation of a porous metal complex, the concentration of the organic ligand in the solution containing the organic ligand is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass or more. On the other hand, from the viewpoint of the solubility of the organic ligand and the formation of a porous metal complex uniformly throughout the membrane, the concentration of the organic ligand in the solution containing the organic ligand is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0093] When a coating containing copper hydroxide nanostructures is immersed in a solution containing 1,3,5-benzenetricarboxylic acid (HBTC) as an organic ligand, the following reaction occurs, forming a porous metal complex (Cu(BTC)). 3Cu(OH)2+2H3BTC→Cu3(BTC)2+6H2O When the porous metal complex (Cu3(BTC)2) is formed, Cu ions are eluted from the copper hydroxide nanostructure and form coordinate bonds with the ligands to form the porous metal complex. In this embodiment, the porous metal complex layer is formed on the anchor layer, and it is believed that the high surface free energy of the anchor layer allows the formed porous metal complex to be well adsorbed to the anchor layer.

[0094] The time for immersing the coating film containing a metal hydroxide in the solution containing an organic ligand is, for example, preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. The immersion time is preferably 100 hours or less. The immersion temperature is not particularly limited, and is preferably, for example, 10 to 50°C. In this embodiment, the immersion treatment can be carried out at a general temperature, such as room temperature.

[0095] In the method for producing a gas adsorption film of this embodiment, the step of immersing the coating film containing a metal hydroxide in a solution containing an organic ligand may be performed multiple times. That is, the method for producing a gas adsorption film of this embodiment may include the steps of forming an anchor layer containing a polar group-containing polymer or an organic onium compound on a substrate layer, applying a solution in which a metal hydroxide is dispersed on the anchor layer and converting the metal hydroxide into a porous metal complex to form a porous metal complex layer, and applying a solution in which a metal hydroxide is further dispersed on the formed porous metal complex layer and converting the metal hydroxide into a porous metal complex to form a porous metal complex layer. By performing the step of immersing the coating film containing a metal hydroxide in a solution containing an organic ligand multiple times, it is possible to increase the thickness of the porous metal complex layer.

[0096] In the method for producing a gas adsorption film of this embodiment, instead of the step of immersing the coating film containing a metal hydroxide in a solution containing an organic ligand, a step of applying a solution containing an organic ligand to the coating film containing a metal hydroxide may be provided.

[0097] After the step of forming the porous metal complex layer, it is preferable to provide a step of forming a protective layer on the porous metal complex layer. When forming the protective layer, it is preferable to laminate a protective layer-forming sheet. The film-forming method of the protective layer-forming sheet is not particularly limited, and it can be appropriately produced by known methods such as extrusion molding such as the T-die method and inflation molding method, extrusion lamination, dry lamination, etc. In the step of forming a protective layer on the porous metal complex layer, a protective layer-forming coating liquid may be applied to the porous metal complex layer and cured to form the protective layer.

[0098] When laminating a protective layer-forming sheet in the step of forming a protective layer, the porous metal complex layer and the protective layer-forming sheet may be bonded by heat fusion, but it is preferable to bond the porous metal complex layer and the protective layer-forming sheet via an adhesive. Examples of adhesives include urethane resins, acrylic resins, vinyl alcohol resins, ethylene vinyl alcohol resins, vinyl-modified resins, oxazoline group-containing resins, carbodiimide group-containing resins, epoxy group-containing resins, isocyanate group-containing resins, alkoxyl group-containing resins, modified styrene resins, and modified silicone resins, and these can be used alone or in combination of two or more. Among these, it is preferable to use an isocyanate group-containing resin in order to improve the adhesion between the porous metal complex layer and the protective layer.

[0099] The adhesive may further contain a curing agent. The curing agent is not particularly limited as long as it can cure the resin described above. For example, when an isocyanate group-containing resin is used as the adhesive, it is preferable to use an isocyanate resin curing agent. An isocyanate compound (polyisocyanate) can be used as the isocyanate resin curing agent. Examples of the isocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, and 4,4'-diphenylpropane diisocyanate. aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4 diisocyanate, naphthylene-1,5-diisocyanate, and 3,3'-dimethoxydiphenyl-4,4'-diisocyanate; aromatic polyisocyanates such as polyphenylene, polymethylene polyisocyanate, and crude tolylene diisocyanate; and aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), decamethylene diisocyanate, and lysine diisocyanate.

[0100] (Application) The gas adsorption film of this embodiment may be applied, for example, as a deodorizing sheet, or may be stored as a pollutant gas adsorption sheet in a storage case or a display case in a museum, etc. The gas adsorption film of this embodiment may also be applied to a space where harmful gases are generated.

[0101] Furthermore, the gas adsorption film of this embodiment exhibits excellent ethylene adsorption capacity and can therefore be used, for example, for packaging fruits and vegetables. By using the gas adsorption film of this embodiment for packaging fruits and vegetables, the progress of ripening and aging of fruits and vegetables due to the action of ethylene produced by the fruits and vegetables can be suppressed. For this reason, the gas adsorption film of this embodiment can also be called a freshness-preserving film.

[0102] When the gas adsorption film of this embodiment is used for packaging fruits and vegetables, its shape is not particularly limited, and it may be, for example, in the form of a sheet, a bag, or a box.

[0103] Furthermore, the gas adsorption film of the present embodiment may be a film-like ethylene adsorbent instead of a packaging material. For example, by enclosing a film-like ethylene adsorbent together with fruits and vegetables inside a package, ethylene can be adsorbed and removed.

[0104] The present embodiment may also relate to a method for packaging fruits and vegetables by covering the fruits and vegetables with a gas adsorption film. In this case, since water vapor is released from the fruits and vegetables, it is preferable that the fruits and vegetables are packaged with the protective layer facing inward (the protective layer being in contact with or close to the fruits and vegetables).

[0105] The present embodiment may also relate to a method for adsorbing ethylene or a method for removing ethylene using the gas adsorption film of the present invention, or to the use of the gas adsorption film of the present invention for removing ethylene. [Example]

[0106] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0107] <Free volume radius of the protective layer> The free volume radius of the protective layer was evaluated by the positron annihilation method using a small positron lifetime measurement device (PALS-200A, manufactured by Fuji Inback Co., Ltd.). Considering the distribution of the penetration depth of positrons, the beam intensity was adjusted so that positrons did not reach the layer below the protective layer, and the measurement was carried out. A sample of the gas adsorption film (laminate) was attached to a 15 mm × 15 mm silicon wafer, and the sample was vacuum-degassed at 25 °C. Using the sample, the positron annihilation lifetime was measured under the following conditions. Measuring device: Small positron annihilation generator PALS-200A manufactured by Fuji Inback Positron beam source: 2 2 Na-based positron annihilation γ-ray detector: Scintillator made of BaF2 and photomultiplier tube Beam intensity: 7 keV (Examples 1, 2, 3, Comparative Example 4), 9 keV (Comparative Example 5) Measurement temperature: 25 °C Measurement atmosphere: Vacuum Total count number: Approximately 5,000,000 counts Then, for the obtained positron annihilation lifetime curve, 3 - 4 component analysis was performed using the non-linear least squares program POSITRONFIT, and τ1, τ2, τ3, and τ4 were defined as those with shorter annihilation lifetimes from the smallest. From the average annihilation lifetimes τ3 and τ4 that capture the free volume radius on the sub-nm order, the free volume radii R3 and R4 were calculated using the following formula. τ3 = (1 / 2)[1 - {R3 / (R3 + 0.166)} + (1 / 2π)sin{2πR3 / (R3 + 0.166)}] - 1 τ4 = (1 / 2)[1 - {R4 / (R4 + 0.166)} + (1 / 2π)sin{2πR4 / (R4 + 0.166)}] - 1 In addition, since the positron annihilation lifetime curve of the protective layer of Comparative Example 4 had two peaks, as described above, the free volume radii R3 and R4 corresponding to each peak were measured.

[0108] <Thickness of the MOF layer><F The cross-section of the porous metal complex layer was observed with a scanning electron microscope (SEM), and the thicknesses at five or more arbitrary points were measured, and the average value was obtained.

[0109] <Water contact angle> The water contact angle of the anchor layer surface was measured using a contact angle meter (Drop Master 500, manufactured by Kyowa Chemical Industry Co., Ltd.). The measurement was performed under an environment of 23°C and 50% relative humidity. The water droplet volume was 10 μL, and the measurement was started 1 second after the water droplet was dropped. The value measured 1 second after the start of the measurement was taken as the water contact angle.

[0110] <Surface roughness Ra> The surface roughness Ra (JIS B0601:2013) of the protective layer surface was measured using a laser microscope (Lasertec "OPTELICS HYBRID+") (n=3).

[0111] <Arithmetic mean height Sa> The arithmetic mean height Sa (ISO 25178) of the surface of the anchor layer in contact with the porous metal complex layer was measured using a laser microscope ("OPTELICS HYBRID+" manufactured by Lasertec). Note that, since no anchor layer was provided in Comparative Examples 1 and 2, the arithmetic mean height Sa of the surface of the base material layer was measured.

[0112] <Total light transmittance / haze> The total light transmittance and haze of the gas adsorption film were measured in accordance with JIS K 7136:2000 using a haze meter "HM-150" manufactured by Murakami Color Research Institute.

[0113] <Amount of ethylene adsorbed> The gas adsorption film was cut into a 5 cm x 9 cm rectangle and placed in a glass bottle and sealed. Standard ethylene gas was then injected into the glass bottle so that the ethylene gas concentration in the bottle was 100 ppm. Immediately, 1 mL of gas was sampled from the glass bottle and the ethylene concentration was measured using a gas chromatograph (Shimadzu Corporation, GC-2014). After one hour, 1 mL of gas was sampled again from the glass bottle and the ethylene concentration was measured. The difference in the ethylene concentration was used to calculate the amount of ethylene adsorbed by the gas adsorption film. The same measurement was also performed without the gas adsorption film to determine the amount of ethylene that had leaked from the glass bottle over the course of one hour, and this was subtracted from the amount of ethylene adsorbed by the gas adsorption film. The ethylene adsorption amount can be calculated by the following formula. Ethylene adsorption amount (ppm / g / h) = Initial ethylene concentration (ppm) - Ethylene concentration after 1 hour in the glass bottle containing the gas adsorption film (ppm) - Amount of ethylene leaked from the glass bottle (ppm)

[0114] <Moisture resistance test> The gas adsorption film was cut into a 5 cm x 9 cm rectangle and吸湿させた was吸湿させた for 24 hours at a relative humidity of 80% and a temperature of 25°C. Then, ethylene adsorption measurement was carried out in the same manner as above. The moisture resistance was calculated by the following formula. Moisture resistance [%] = (Ethylene adsorption amount after moisture absorption (ppm / g / h) / Ethylene adsorption amount before moisture absorption (ppm / g / h)) × 100

[0115] (Example 1) <Preparation of polar group-containing polymer solution (D-1)> ​​​​​​​​​​​​0.1 g of 1,3,5-benzenetricarboxylic acid (HBTC) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in a mixed solution (100 mL) of ethanol and water prepared in a volume ratio of 5:2.

[0118] <Preparation of gas adsorption film> A polycarbonate sheet (FE-2000, manufactured by Mitsubishi Gas Chemical Company, Inc.) was used as the substrate layer. The surface of this polycarbonate sheet was heated at an output of 100 W min / m. 2 The corona-treated surface was bar-coated with a coating liquid prepared by diluting polyethyleneimine with ethanol to 2.5% by mass and then dried by heating (first anchor layer). Next, a polar group-containing polymer solution was bar-coated onto the first anchor layer and then dried by heating (second anchor layer). Next, a copper hydroxide dispersion solution (copper hydroxide nanobelt solution) was bar-coated onto the second anchor layer and dried at room temperature to form a copper hydroxide nanobelt layer. The resulting laminate was then immersed in a HBTC solution for 2 hours to convert the copper hydroxide nanobelt layer into a porous metal complex layer (MOF layer). In this way, a porous metal complex layer (B) was formed on the substrate layer (A).

[0119] <Preparation of adhesive solution> An adhesive solution was prepared by mixing the components so that the isocyanate (TOMOFLEX AD900 manufactured by Toyo-Morton Co., Ltd.) was 10 mass %, the curing agent (TOMOFLEX CAT-RT85 manufactured by Toyo-Morton Co., Ltd.) was 1.5 mass %, and the ethyl acetate was 15 mass %.

[0120] <Lamination of protective layers> A low-density polyethylene (Taiko Polyethylene Film LL-XHT #25, manufactured by Futamura Chemical Co., Ltd.) was used as the protective layer (C). An adhesive solution was bar-coated onto the low-density polyethylene, and the adhesive solution was laminated to cover the porous metal complex layer (B). The laminate was then heat-treated at 40°C for 1 hour to obtain a gas adsorption film.

[0121] Example 2 <Preparation of Polar Group-Containing Polymer Solution (D-2)> 0.15 g of acetoacetyl group-modified PVA (Z-100, manufactured by Mitsubishi Chemical Corporation), 0.23 g of silica particles (Sylysia 730, manufactured by Fuji Silysia Chemical Ltd., average particle size 4.0 μm), and 0.01 g of a crosslinker (Safelink SPM-01, manufactured by Mitsubishi Chemical Corporation) were dissolved in water to a concentration of 4% by mass.

[0122] <Preparation of gas adsorption film> A gas adsorption film was obtained in the same manner as in Example 1, except that the polar group-containing polymer solution (D-2) was used for bar coating instead of the polar group-containing polymer solution (D-1) in Example 1.

[0123] Example 3 A gas adsorption film was obtained in the same manner as in Example 1, except that the step of forming a porous metal complex layer (MOF layer) was repeated three times.

[0124] (Comparative Example 1) A gas adsorption film was obtained in the same manner as in Example 1, except that no protective layer was provided.

[0125] (Comparative Example 2) A gas adsorption film was obtained in the same manner as in Example 2, except that no protective layer was provided.

[0126] (Comparative Example 3) A gas adsorption film was obtained in the same manner as in Example 3, except that no protective layer was provided.

[0127] Comparative Example 4 <Preparation of Silicone Solution (E-1)> 5 g of liquid silicone (Silopren LSR 2650, manufactured by Momentive) Part A and 5 g of Part B were mixed and stirred for 5 minutes. 40 g of toluene was added and dissolved. The mixture was degassed by applying ultrasound for 30 minutes.

[0128] <Formation of protective layer> The coated surface of the gas adsorption film prepared in Comparative Example 2 was bar-coated with silicone solution (E-1) so that the film thickness after drying would be 25 μm, and the film was heated at 120°C for 5 minutes, and then further heated at 175°C for 10 minutes to obtain a gas adsorption film with a protective layer.

[0129] (Comparative Example 5) A gas adsorption film was obtained in the same manner as in Example 2, except that polyethylene terephthalate (Lumirror #12-S10, manufactured by Toray Industries, Inc.) was used as the protective layer (C).

[0130] [Table 1]

[0131] As shown in FIG. 3, the gas adsorption films obtained in the Examples were superior in moisture resistance to those obtained in the Comparative Examples, and exhibited excellent ethylene adsorption capacity even in a high-humidity environment. [Explanation of symbols]

[0132] 2 Base material layer 4 Anchor Layer 6. Porous metal complex layer 8 Protective layer 10 Gas adsorption film

Claims

1. A substrate layer (A), a porous metal complex layer (B), and a protective layer (C) are provided in this order; A gas adsorption film, wherein the free volume radius of the protective layer (C) is 0.265 to 0.400 nm.

2. 2. The gas adsorption film according to claim 1, wherein the surface roughness Ra of the protective layer (C) is 0.5 or less.

3. 3. The gas adsorption film according to claim 1, wherein the porous metal complex layer (B) has a thickness of 0.1 to 10 μm.

4. 3. The gas adsorption film according to claim 1, further comprising an anchor layer (D) between the substrate layer (A) and the porous metal complex layer (B).

5. The gas adsorption film according to claim 4 , wherein the anchor layer (D) comprises a polar group-containing polymer or an organic onium compound.

6. 5. The gas adsorption film according to claim 4, wherein the arithmetic mean height Sa of said anchor layer (D) is 0.1 to 20 μm.

7. 3. The gas adsorption film according to claim 1, wherein the protective layer (C) comprises low-density polyethylene.

8. 3. The gas adsorption film according to claim 1, wherein the porous metal complex layer (B) comprises at least one porous metal complex selected from the group consisting of HKUST-1 (Cu / 1,3,5-benzenetricarboxylic acid), Mg-MOF-74 (Mg / 2,5-dihydroxyterephthalic acid), MOF-505 / GO (Cu / 3,3,5,5-biphenyltetracarboxylic acid), MOF-5 / G (Zn / 1,4-benzenedicarboxylic acid), Zr-MOF (Zr / 1,4-naphthalenedicarboxylic acid), MIL-101 (Cr / 1,4-benzenedicarboxylic acid), Co-MOF74 (Co / 2,5-dihydroxyterephthalic acid), and Ni-MOF-74 (Ni / 2,5-dihydroxyterephthalic acid).

9. 3. The gas adsorption film according to claim 1, which is an ethylene adsorption film.

10. 3. The gas adsorption film according to claim 1, which is used for packaging fruits and vegetables.

11. A method for packaging fruits and vegetables, comprising covering the fruits and vegetables with the gas adsorption film according to claim 1 or 2, with the protective layer (C) facing inward.

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