Oxygen absorbent material and method for storing article

Abstract

The present invention provides: [1] an oxygen absorbent material which comprises a base material (I), an inorganic layer (II) and a cured product layer (III) of an epoxy resin composition that contains an epoxy resin and an epoxy resin curing agent containing an amine-based curing agent, wherein the inorganic layer (II) and the cured product layer (III) are adjacent to each other; and [2] a method for storing an article, the method comprising one or more modes that are selected from among (1) a mode in which the article is contained in a packaging material in which the oxygen absorbent material described in [1] is sealed and (2) a mode in which the article is contained in a packaging material that at least partially comprises the oxygen absorbent material described in [1], and the packaging material has an oxygen transmission rate of 1 cc / (m2∙day∙atm) or less.

Description

Oxygen absorber and method for preserving articles

[0001] The present invention relates to an oxygen absorber and a method for preserving an article.

[0002] A preservation technique using an oxygen absorber is known as one of the preservation techniques for foods, medicines, etc. Specifically, this technique involves placing an oxygen absorber inside a sealed package together with the object to be preserved, creating an oxygen-free environment inside the sealed package, thereby suppressing oxidative deterioration, discoloration, etc. of the object to be preserved.

[0003] As the oxygen absorber, those made of inorganic materials and those made of organic materials have been proposed. Examples of inorganic materials include those using metal powder such as iron, sulfite, bisulfite, and dithionite, while examples of organic materials include those using L-ascorbic acid, erythorbic acid and salts thereof, sugars such as glucose, and reducing polyhydric alcohols such as catechol and pyrogallol.

[0004] Oxygen-absorbing resin compositions containing improved oxygen absorbents are also known. For example, Patent Document 1 discloses an oxygen-absorbing resin composition that has oxygen absorbing ability even in an atmosphere with little or no moisture, the oxygen-absorbing resin composition comprising an oxygen absorber containing a metal obtained by treating an alloy containing at least one transition metal selected from the group consisting of iron, cobalt, nickel, and copper and aluminum with an alkaline aqueous solution, the oxygen absorber having a specific surface area measured by the BET method equal to or greater than a predetermined value, and a thermoplastic resin, and having a moisture content equal to or less than a predetermined value.

[0005] Furthermore, technology for improving packaging materials has also been studied for oxygen absorbers that are attached to the inner surface of the center-sealed side of packaging bags when packaging food in pillow bags. For example, Patent Document 2 discloses that an oxygen absorber is sealed in a packaging bag formed by thermocompression bonding the peripheral edges of sheets made of laminated predetermined packaging materials, and the oxygen absorber has a stiffness value within a predetermined range at the heat-sealed part formed on the peripheral edge of the packaging bag by thermal bonding. The oxygen absorber is less likely to fall off or damage food during the packaging process and exhibits excellent food preservation effects.

[0006] JP 2015-7148 A JP 2016-140810 A

[0007] The oxygen absorbers used in Patent Documents 1 and 2 all contain metal powder such as iron powder, or a reducing organic compound. Meanwhile, studies have been conducted on oxygen-absorbing materials that use novel materials as oxygen absorbers and can be easily formed into a film without the need for operations such as kneading the oxygen absorber into a film, and that are suitable for preserving moisture-containing articles or articles in high-humidity environments. The present invention addresses the need to provide an oxygen absorber suitable for preserving moisture-containing articles or articles in high-humidity environments, and a method for preserving articles using the oxygen absorber.

[0008] The present inventors have found that the above problems can be solved by providing an oxygen absorber of a specific structure having a substrate, an inorganic layer, and a cured layer of a predetermined epoxy resin composition. Specifically, the present invention relates to the following: [1] An oxygen absorber having a substrate (I), an inorganic layer (II), and a cured layer (III) of an epoxy resin composition containing an epoxy resin and an epoxy resin curing agent including an amine-based curing agent, wherein the inorganic layer (II) and the cured layer (III) are adjacent to each other. [2] A method for preserving an article using the oxygen absorber described in [1] above, the method comprising one or more of the following aspects (1) or (2): (1) The article is housed in a packaging material in which the oxygen absorber is enclosed. (2) The article is housed in a packaging material having at least a portion thereof containing the oxygen absorber, and the packaging material has an oxygen permeability of 1 cc / (m ２ [3] Use of a laminate, which has a substrate (I), an inorganic layer (II), and a cured material layer (III) of an epoxy resin composition containing an epoxy resin and an epoxy resin curing agent including an amine-based curing agent, wherein the inorganic layer (II) and the cured material layer (III) are adjacent to each other, as an oxygen absorber.

[0009] According to the present invention, it is possible to provide an oxygen absorber that is particularly suitable for preserving moisture-containing articles or articles in a high-humidity environment, and a method for preserving articles using the oxygen absorber.

[0010] (a) is a photograph of the appearance of cut rice cakes before storage used in Example 24, Comparative Example 2, and Comparative Example 3. (b) is a photograph of the appearance of cut rice cakes after they were placed in a bag-shaped packaging material and the packaging material was stored for two months in an environment of 40°C and a relative humidity of 90% in Example 24, (c) is a photograph of the appearance of cut rice cakes after they were placed in a bag-shaped packaging material and the packaging material was stored for two months in an environment of 40°C and a relative humidity of 90% in Comparative Example 3. (a) is a photograph of the appearance of cheese tara fish before storage used in Example 25, Comparative Example 4, and Comparative Example 5. (b) is a photograph of the appearance of cheese tara fish after they were placed in a bag-shaped packaging material and the packaging material was stored for two months in an environment of 40°C and a relative humidity of 90% in Example 25, (c) is a photograph of the appearance of cheese tara fish after they were placed in a bag-shaped packaging material and the packaging material was stored for two months in an environment of 40°C and a relative humidity of 90% in Comparative Example 5.

[0011] [Oxygen Absorber] The oxygen absorber of the present invention has a substrate (I), an inorganic layer (II), and a cured material layer (III) of an epoxy resin composition containing an epoxy resin and an epoxy resin curing agent including an amine-based curing agent, and the inorganic layer (II) and the cured material layer (III) are adjacent to each other. The oxygen absorber of the present invention has oxygen absorbing properties and is particularly suitable for preserving moisture-containing articles.

[0012] The reason why the oxygen absorber of the present invention exhibits the above-mentioned effects is unclear, but is thought to be as follows. It is believed that the cured material layer (III) of a specific epoxy resin composition contained in the oxygen absorber of the present invention is oxidized upon contact with the inorganic layer (II) to exhibit oxygen absorbing properties. It is also believed that oxidation of the inorganic layer (II) progresses due to the influence of the adjacent cured material layer (III). Furthermore, since the inorganic layer (II) and the cured material layer (III) have not only oxygen absorbing properties but also gas barrier properties, packaging materials using the oxygen absorber of the present invention are suitable for preserving items that are prone to oxidative deterioration. In particular, the present inventors have discovered that the oxygen absorbing properties of the cured material layer (III) upon contact with the inorganic layer (II) are exhibited by moisture as a trigger. Therefore, the oxygen absorber of the present invention is suitable for preserving water-containing items or items in high-humidity environments.

[0013] The layer structure of the oxygen absorber of the present invention is not particularly limited as long as it has at least one layer of a substrate (I), an inorganic layer (II), and a cured material layer (III). However, from the viewpoint of exhibiting oxygen absorbing performance, it is necessary that the inorganic layer (II) and the cured material layer (III) are adjacent to each other. From the viewpoint of exhibiting oxygen absorbing performance and protecting the inorganic layer (II), the layer structure of the oxygen absorber preferably has the substrate (I), the inorganic layer (II), and the cured material layer (III) in this order, and the inorganic layer (II) and the cured material layer (III) are adjacent to each other. Furthermore, from the viewpoint of improving the strength of the oxygen absorber, it is preferable that the oxygen absorber has two or more substrates (I), and more preferably has the substrate (IA), the inorganic layer (II), the cured material layer (III), and the substrate (IB) in this order.

[0014] <Substrate (I)> From the viewpoint of improving oxygen absorption and flex resistance, the substrate (I) used in the oxygen absorber of the present invention is preferably a plastic film. Examples of plastic films used as the substrate (I) include polyolefin films such as low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and polypropylene; polyester films such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polyamide films such as nylon 6, nylon 6,6, and polymetaxylylene adipamide (N-MXD6); polyimide films; biodegradable films such as polylactic acid films; polyacrylonitrile films; poly(meth)acrylic films; polystyrene films; polycarbonate films; saponified ethylene-vinyl acetate copolymer (EVOH) films; and polyvinyl alcohol films. Among the above, from the viewpoints of oxygen absorption, flex resistance, strength, and heat resistance, the substrate (I) is preferably a film selected from the group consisting of polyolefin films, polyester films, polyamide films, and polyimide films, more preferably a film selected from the group consisting of polyolefin films and polyester films, and even more preferably a polypropylene film or a polyethylene terephthalate (PET) film. The above film may be a non-stretched film or may be uniaxially or biaxially stretched.

[0015] When the oxygen absorber has a substrate (IA) and a substrate (IB), the substrate (IA) and the substrate (IB) may be substrates made of the same type of resin or substrates made of different types of resin. However, from the viewpoint of ease of recycling, the substrate (IA) and the substrate (IB) are preferably substrates made of the same type of resin, and it is more preferable that the substrate (IA) and the substrate (IB) are polypropylene films.

[0016] The thickness of the substrate (I) can be appropriately selected depending on the application and is not particularly limited, but from the viewpoint of gas barrier properties and strength, it is preferably 5 to 300 μm, more preferably 5 to 100 μm, and even more preferably 10 to 60 μm. The above thickness is the thickness per sheet of the substrate (I).

[0017] <Inorganic Layer (II)> The inorganic layer (II) used in the oxygen absorber of the present invention can be made of a metal foil or formed by a vapor deposition method. From the viewpoint of improving oxygen absorption, the inorganic layer (II) is preferably an inorganic vapor deposition layer formed by a vapor deposition method. The inorganic material constituting the inorganic layer (II) is preferably an inorganic material capable of forming an inorganic vapor deposition layer, such as silicon, aluminum, magnesium, calcium, zinc, tin, nickel, titanium, zirconium, carbon, or oxides, carbides, nitrides, oxynitrides thereof, etc., and one or more of these can be used. Among these, from the viewpoint of improving oxygen absorption and gas barrier properties and the ease of forming an inorganic vapor deposition layer, the inorganic layer (II) is preferably a silicon oxide (silica) vapor deposition layer, an aluminum vapor deposition layer, or an aluminum oxide (alumina) vapor deposition layer, and from the viewpoint of improving oxygen absorption, an aluminum vapor deposition layer is more preferable. The thickness of the inorganic layer (II) is preferably 5 nm or more from the viewpoint of improving oxygen absorption and gas barrier properties. From the viewpoint of improving flex resistance, the thickness is preferably 20 μm or less, more preferably 10 μm or less, and when the inorganic layer (II) is an inorganic vapor deposition layer, the thickness is preferably 100 nm or less, more preferably 50 nm or less. The above thickness is the thickness per layer of the inorganic layer (II).

[0018] The method for forming the inorganic layer (II) is not particularly limited, and examples of the vapor deposition method include known vapor deposition methods such as physical vapor deposition methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. The inorganic layer (II) can be formed, for example, on the substrate (I) or the cured material layer (III).

[0019] <Cured Material Layer (III)> The cured material layer (III) used in the oxygen absorber of the present invention is a layer made of a cured product of an epoxy resin composition containing an epoxy resin and an epoxy resin curing agent including an amine-based curing agent. Hereinafter, each component contained in the epoxy resin composition will be described.

[0020] (Epoxy Resin) The epoxy resin used in the epoxy resin composition may be any of a saturated or unsaturated aliphatic compound, an alicyclic compound, an aromatic compound, or a heterocyclic compound. In consideration of the development of high oxygen absorption properties and gas barrier properties, an epoxy resin containing an aromatic ring or an alicyclic structure in the molecule is preferred. Specific examples of the epoxy resin include at least one selected from the group consisting of epoxy resins having a glycidylamino group derived from meta-xylylenediamine, epoxy resins having a glycidylamino group derived from para-xylylenediamine, epoxy resins having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from 1,4-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from diaminodiphenylmethane, epoxy resins having a glycidylamino group and / or a glycidyloxy group derived from para-aminophenol, epoxy resins having a glycidyloxy group derived from bisphenol A, epoxy resins having a glycidyloxy group derived from bisphenol F, epoxy resins having a glycidyloxy group derived from phenol novolac, and epoxy resins having a glycidyloxy group derived from resorcinol. The above epoxy resins can be used alone or in combination of two or more. Among the above, from the viewpoint of improving oxygen absorption and gas barrier properties, preferred epoxy resins are those containing, as a main component, at least one selected from the group consisting of epoxy resins having a glycidylamino group derived from meta-xylylenediamine, epoxy resins having a glycidylamino group derived from para-xylylenediamine, and epoxy resins having a glycidyloxy group derived from bisphenol F, and more preferred are those containing, as a main component, an epoxy resin having a glycidylamino group derived from meta-xylylenediamine. Note that the term "main component" as used herein means that other components may be contained within the scope of the present invention, and preferably means 50 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 90 to 100% by mass of the total.

[0021] (Epoxy resin curing agent containing an amine-based curing agent) The epoxy resin curing agent used in the epoxy resin composition contains an amine-based curing agent from the viewpoint of improving oxygen absorption and gas barrier properties. As the amine-based curing agent, polyamines conventionally used as epoxy resin curing agents or modified products thereof can be used. From the viewpoint of improving oxygen absorption and gas barrier properties, the amine-based curing agent is preferably a modified product of polyamine, and more preferably contains a reaction product of the following components (A) and (B): (A) at least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine; (B) at least one selected from the group consisting of unsaturated carboxylic acids represented by the following general formula (1) and derivatives thereof: (In formula (1), R １ , R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms.

[0022] From the viewpoint of improving oxygen absorption and gas barrier properties, the component (A) is preferably metaxylylenediamine. The component (B) is at least one selected from the group consisting of unsaturated carboxylic acids represented by the general formula (1) and derivatives thereof. From the viewpoint of improving oxygen absorption and gas barrier properties, R in the general formula (1) is preferably metaxylylenediamine. １ is preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, even more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. ２ is preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, even more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom.

[0023] Examples of the derivative of the unsaturated carboxylic acid represented by the general formula (1) include esters, amides, acid anhydrides, and acid chlorides of the unsaturated carboxylic acid. As the ester of the unsaturated carboxylic acid, alkyl esters are preferred, and from the viewpoint of obtaining good reactivity, the number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1 to 2.

[0024] Examples of the unsaturated carboxylic acid represented by the general formula (1) and its derivatives include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, α-ethylacrylic acid, α-propylacrylic acid, α-isopropylacrylic acid, α-n-butylacrylic acid, α-t-butylacrylic acid, α-pentylacrylic acid, α-phenylacrylic acid, α-benzylacrylic acid, crotonic acid, 2-pentenoic acid, 2-hexenoic acid, 4-methyl-2-pentenoic acid, 2-heptenoic acid, 4-methyl-2-hexenoic acid, 5-methyl-2-hexenoic acid, 4,4-dimethyl-2-pentenoic acid, 4-phenyl-2-butenoic acid, cinnamic acid, o-methylcinnamic acid, m-methylcinnamic acid, p-methylcinnamic acid, and 2-octenoic acid, as well as esters, amides, acid anhydrides, and acid chlorides thereof. Among the above, from the viewpoint of improving oxygen absorption properties and gas barrier properties, the component (B) is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, and derivatives thereof, more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, and alkyl esters thereof, even more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, and alkyl esters thereof, even more preferably alkyl esters of acrylic acid, and even more preferably methyl acrylate.

[0025] When an unsaturated carboxylic acid, ester, or amide is used as component (B), the reaction between component (A) and component (B) is carried out by mixing component (A) and component (B) at a temperature of 0 to 100°C, more preferably 0 to 70°C, and then carrying out a Michael addition reaction and an amide group-forming reaction by dehydration, dealcoholization, and deamination at a temperature of 100 to 300°C, preferably 130 to 250°C. In this case, during the amide group-forming reaction, the reactor may be depressurized at the final stage of the reaction, if necessary, to complete the reaction. Furthermore, the reaction mixture may be diluted with a nonreactive solvent, if necessary. Furthermore, a catalyst such as a phosphite ester may be added as a dehydrating agent or a dealcoholizing agent.

[0026] On the other hand, when an acid anhydride or acid chloride of an unsaturated carboxylic acid is used as component (B), the components are mixed at a temperature of 0 to 150°C, preferably 0 to 100°C, followed by the Michael addition reaction and the amide group formation reaction. In this case, during the amide group formation reaction, the reactor may be decompressed as needed in the final stage of the reaction to complete the reaction. Furthermore, the reaction may be diluted with a non-reactive solvent as needed. Furthermore, a tertiary amine such as pyridine, picoline, lutidine, or trialkylamine may also be added.

[0027] The amide group moiety formed by the reaction of the component (A) with the component (B) has high cohesive strength, and therefore the cured material layer (III) formed using the epoxy resin curing agent, which is the reaction product of the component (A) and the component (B), has oxygen absorption properties, gas barrier properties, and good adhesiveness.

[0028] The reaction molar ratio of the (B) component to the (A) component [(B) / (A)] is preferably in the range of 0.3 to 1.0. When the reaction molar ratio is 0.3 or more, a sufficient amount of amide groups is generated in the epoxy resin curing agent, resulting in high levels of gas barrier properties and adhesiveness. On the other hand, when the reaction molar ratio is in the range of 1.0 or less, the amount of amino groups necessary for reaction with the epoxy groups in the epoxy resin is sufficient, resulting in excellent heat resistance and excellent solubility in organic solvents and water. From the viewpoint of the oxygen absorption and gas barrier properties of the resulting cured product layer (III), it is more preferable that the reaction molar ratio of the (B) component to the (A) component [(B) / (A)] is in the range of 0.6 to 1.0.

[0029] The amine-based curing agent may be a reaction product of the components (A) and (B) and at least one compound selected from the group consisting of the following components (C), (D), and (E): ３ At least one (R ３ represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms which may have a hydroxyl group, or an aryl group having 6 to 12 carbon atoms.) (D) a cyclic carbonate (E) a monoepoxy compound having 2 to 20 carbon atoms

[0030] The component (C), R ３ The monocarboxylic acid represented by —COOH and its derivatives are used as needed to reduce the reactivity between the epoxy resin curing agent and the epoxy resin, thereby improving workability. ３ represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms which may have a hydroxyl group, or an aryl group having 6 to 12 carbon atoms; R ３ is preferably an alkyl group having 1 to 3 carbon atoms or a phenyl group. ３Derivatives of monocarboxylic acids represented by -COOH include, for example, esters, amides, acid anhydrides, and acid chlorides of the carboxylic acids. The esters of the carboxylic acids are preferably alkyl esters, and the number of alkyl carbon atoms is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1 to 2. Examples of the component (C) include monocarboxylic acids and derivatives thereof, such as formic acid, acetic acid, propionic acid, butyric acid, lactic acid, glycolic acid, and benzoic acid. The component (C) may be used singly or in combination of two or more.

[0031] The cyclic carbonate of component (D) is used as needed from the viewpoint of reducing the reactivity between the epoxy resin curing agent and the epoxy resin and improving workability, and is preferably a cyclic carbonate having a six-membered ring or less from the viewpoint of reactivity with component (A). Examples include ethylene carbonate, propylene carbonate, glycerin carbonate, 1,2-butylene carbonate, vinylene carbonate, 4-vinyl-1,3-dioxolan-2-one, 4-methoxymethyl-1,3-dioxolan-2-one, and 1,3-dioxan-2-one. Among these, at least one selected from the group consisting of ethylene carbonate, propylene carbonate, and glycerin carbonate is preferred from the viewpoint of gas barrier properties.

[0032] The monoepoxy compound of component (E) is a monoepoxy compound having 2 to 20 carbon atoms, and is used as needed from the viewpoint of reducing the reactivity between the epoxy resin curing agent and the epoxy resin and improving workability. From the viewpoint of gas barrier properties, a monoepoxy compound having 2 to 10 carbon atoms is preferred, and a compound represented by the following formula (2) is more preferred.

[0033] (In formula (2), R ４ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group, or R ５ -O-CH ２ represents -, and R ５represents a phenyl group or a benzyl group.) Examples of the monoepoxy compound represented by formula (2) include ethylene oxide, propylene oxide, 1,2-butylene oxide, styrene oxide, phenyl glycidyl ether, and benzyl glycidyl ether. The component (E) may be used alone or in combination of two or more.

[0034] When the component (C), component (D), or component (E) is used as the amine-based curing agent, any one compound selected from the group consisting of the component (C), component (D), and component (E) may be used alone, or two or more types may be used in combination.

[0035] The amine-based curing agent may be a reaction product obtained by reacting other components in addition to the components (A) to (E) as long as the effects of the present invention are not impaired. Examples of other components include aromatic dicarboxylic acids and derivatives thereof. However, the amount of the "other components" used is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less of the total amount of the reaction components constituting the amine-based curing agent.

[0036] The reaction product of the components (A) and (B) and at least one compound selected from the group consisting of the components (C), (D), and (E) can be obtained by reacting the component (A), which is a polyamine compound, with at least one compound selected from the group consisting of the components (C), (D), and (E) in combination with the component (B). The reaction can be carried out by adding the components (B) to (E) in any order and reacting them with the component (A), or by mixing the components (B) to (E) and reacting them with the component (A). The reaction between the component (A) and the component (C) can be carried out under the same conditions as the reaction between the component (A) and the component (B). When the component (C) is used, the components (B) and (C) can be mixed and reacted with the component (A), or the components (A) and (B) can be reacted first and then the component (C) can be reacted. On the other hand, when using the component (D) and / or component (E), it is preferable to first react the component (A) with the component (B), and then react the component (D) and / or component (E). The reaction between the component (A) and the component (D) and / or component (E) is carried out by mixing the component (A) with the component (D) and / or component (E) at 25 to 200°C, and then carrying out an addition reaction at 30 to 180°C, preferably 40 to 170°C. If necessary, a catalyst such as sodium methoxide, sodium ethoxide, or potassium t-butoxide can be used. During the above reaction, the component (D) and / or component (E) can be melted or diluted with a non-reactive solvent as needed to promote the reaction.

[0037] Even when the amine curing agent is a reaction product of the components (A) and (B) with at least one compound selected from the group consisting of the components (C), (D), and (E), the reaction molar ratio of the component (B) to the component (A) [(B) / (A)] is preferably in the range of 0.3 to 1.0, and more preferably in the range of 0.6 to 1.0, for the same reasons as above. On the other hand, the reaction molar ratio of the components (C), (D), and (E) to the component (A) [{(C)+(D)+(E)} / (A)] is preferably in the range of 0.05 to 3.1, more preferably in the range of 0.07 to 2.5, and even more preferably in the range of 0.1 to 2.0. However, from the viewpoints of oxygen absorption property, gas barrier property, and coatability, the reaction molar ratio of the components (B) to (E) to the component (A), [{(B)+(C)+(D)+(E)} / (A)], is preferably in the range of 0.35 to 2.5, and more preferably in the range of 0.35 to 2.0.

[0038] From the viewpoint of improving oxygen absorption properties, gas barrier properties, and adhesive properties, the amine-based curing agent, which is a reaction product of the component (A) and the component (B), is preferably a reaction product obtained by reacting only the component (A) and the component (B), and more preferably a reaction product obtained by reacting only metaxylylenediamine and an alkyl acrylate.

[0039] From the viewpoint of improving oxygen absorption properties, gas barrier properties, and adhesion, the content of the reaction product of the component (A) and the component (B) in the amine curing agent is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and still more preferably 90% by mass or more, but 100% by mass or less.

[0040] The epoxy resin curing agent used in the present invention may contain curing agent components other than the amine-based curing agent, but from the viewpoint of improving oxygen absorption and gas barrier properties, it is preferable that the content of the amine-based curing agent is high. From the viewpoint of improving oxygen absorption and gas barrier properties, the content of the amine-based curing agent in the epoxy resin curing agent is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and still more preferably 90% by mass or more, and 100% by mass or less.

[0041] The blending ratio of the epoxy resin and the epoxy resin curing agent in the epoxy resin composition may generally be within the standard blending range used when preparing an epoxy resin reaction product by reacting an epoxy resin with an epoxy resin curing agent. Specifically, the ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin (number of active hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin) is preferably in the range of 0.2 to 12.0. From the viewpoints of improving oxygen absorption, gas barrier properties, and adhesion, the ratio (number of active hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin) is more preferably in the range of 0.2 to 10.0, even more preferably 0.2 to 8.0, even more preferably 0.5 to 6.0, even more preferably greater than 1.0 but not exceeding 5.0, even more preferably 1.1 to 5.0, even more preferably 2.0 to 5.0, even more preferably 3.0 to 5.0, and even more preferably 3.5 to 5.0.

[0042] The epoxy resin composition may further contain a coupling agent from the viewpoint of improving the adhesion of the resulting cured material layer (III) to the inorganic layer (II). Examples of such coupling agents include silane coupling agents, titanate-based coupling agents, and aluminate-based coupling agents, with silane coupling agents being preferred. Examples of silane coupling agents include silane coupling agents having a vinyl group, silane coupling agents having an amino group, silane coupling agents having an epoxy group, silane coupling agents having a (meth)acrylic group, and silane coupling agents having a mercapto group. Among these, from the viewpoint of improving the adhesion of the resulting cured material layer (III) to the inorganic layer (II), at least one selected from the group consisting of silane coupling agents having an amino group and silane coupling agents having an epoxy group is preferred. When a coupling agent is used, the content of the coupling agent in the epoxy resin composition is preferably 0.1 to 10 parts by mass, more preferably 1 to 8 parts by mass, per 100 parts by mass of the epoxy resin curing agent.

[0043] The epoxy resin composition may contain additives such as thermosetting resins, wetting agents, tackifiers, antifoaming agents, curing accelerators, rust-preventive additives, pigments, oxygen scavengers, etc., as needed, within the scope of not impairing the effects of the present invention. When additives are used, the total content of the additives in the epoxy resin composition is preferably 20.0 parts by mass or less, and more preferably 0.001 to 15.0 parts by mass, per 100 parts by mass of the total amount of the epoxy resin and epoxy resin curing agent.

[0044] However, from the viewpoint of obtaining the effects of the present invention, the total content of the epoxy resin and the epoxy resin curing agent in the solid content of the epoxy resin composition is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and still more preferably 85% by mass or more, and is 100% by mass or less. The "solid content of the epoxy resin composition" means the components in the epoxy resin composition excluding water and organic solvents.

[0045] The epoxy resin composition may contain an organic solvent, and the organic solvent is preferably a non-reactive solvent. Specific examples of such organic solvents include protic polar solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and 1-propoxy-2-propanol, as well as ethyl acetate, butyl acetate, methyl isobutyl ketone, and toluene. Among these, at least one solvent selected from the group consisting of methanol, ethanol, and ethyl acetate is preferred from the viewpoint of improving the drying rate.

[0046] From the viewpoint of exhibiting higher adhesiveness in the resulting cured product layer (III), the epoxy resin composition preferably contains a small amount of lubricant. Specifically, the content of lubricant in the epoxy resin composition is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, even more preferably less than 2 parts by mass, still more preferably less than 1 part by mass, even more preferably less than 0.1 parts by mass, still more preferably less than 0.01 parts by mass, and even more preferably 0 part by mass, per 100 parts by mass of the total amount of epoxy resin and epoxy resin curing agent in the epoxy resin composition. The lubricant includes not only components conventionally known as lubricants, but also unsaturated fatty acid amides having 14 to 24 carbon atoms, such as erucic acid amide and oleic acid amide.

[0047] From the viewpoint of exhibiting higher adhesiveness in the obtained cured product layer (III), the epoxy resin composition preferably has a small content of filler such as organic or inorganic powder, organic or inorganic fiber, etc. Specifically, the content of the filler in the epoxy resin composition is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, even more preferably less than 2 parts by mass, still more preferably less than 1 part by mass, still more preferably less than 0.1 parts by mass, still more preferably less than 0.01 parts by mass, and still more preferably 0 part by mass, relative to 100 parts by mass of the total amount of the epoxy resin and epoxy resin curing agent in the epoxy resin composition.

[0048] The epoxy resin composition can be prepared, for example, by blending predetermined amounts of an epoxy resin, an epoxy resin curing agent, and optionally used additives and a solvent, and then stirring and mixing the mixture using a known method and apparatus.

[0049] The method for curing the epoxy resin composition to form the cured material layer (III) will be described later in the method for producing an oxygen absorber. From the viewpoint of improving oxygen absorption and gas barrier properties, the thickness of the cured material layer (III) is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, and even more preferably 1.5 μm or more. From the viewpoint of improving adhesiveness, the thickness is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. The above thickness is the thickness per layer of the cured material layer (III).

[0050] The oxygen absorber of the present invention may have any layer, such as an adhesive layer, a primer layer, an ink layer, a surface protection layer, etc., in addition to the substrate (I), the inorganic layer (II), and the cured material layer (III). However, the inorganic layer (II) and the cured material layer (III) must be adjacent to each other, and no any layer is included between the inorganic layer (II) and the cured material layer (III).

[0051] Because the oxygen absorber of the present invention exhibits oxygen absorption properties through the inorganic layer (II) and the cured material layer (III), it is preferable that the oxygen absorber does not have any oxygen-absorbing layers other than the inorganic layer (II) and the cured material layer (III). Examples of oxygen-absorbing layers include a polyamide resin layer containing a polyamide resin and a transition metal. Transition metals refer to elements of Groups 3 to 11 of the periodic table, and are generally compounds that enhance oxygen absorption performance when incorporated into a polyamide resin layer in the form of an inorganic acid salt, an organic acid salt, or a complex salt. Examples of such transition metals include cobalt, copper, cerium, manganese, iron, chromium, and nickel. It is also preferable that none of the layers constituting the oxygen absorber of the present invention contain the above-mentioned transition metals. Specifically, the total content of transition metals in the oxygen absorber of the present invention is preferably less than 5 ppm, more preferably less than 3 ppm, even more preferably less than 1 ppm, and even more preferably less than 0.1 ppm.

[0052] The total thickness of the oxygen absorbing material varies depending on the layer structure, but from the viewpoint of improving oxygen absorption and gas barrier properties, it is preferably 6 to 600 μm, more preferably 10 to 500 μm, even more preferably 20 to 300 μm, and still more preferably 20 to 200 μm.

[0053] <Method for Producing Oxygen Absorber> The method for producing the oxygen absorber of the present invention is not particularly limited, and known methods can be used. For example, a method for producing an oxygen absorber in which a substrate (I), an inorganic layer (II), and a cured material layer (III) are laminated in this order includes forming an inorganic layer (II) on one side of the substrate (I), applying the epoxy resin composition to a desired thickness on the inorganic layer (II), and then curing the epoxy resin composition to form the cured material layer (III). Note that the cured material layer (III) may also be formed on the inorganic layer (II) using a film in which the inorganic layer (II) has already been formed on the substrate (I). A method for producing an oxygen absorber in which a substrate (IA), an inorganic layer (II), a cured material layer (III), and a substrate (IB) are laminated in this order includes forming an inorganic layer (II) on one side of the substrate (IA), applying the epoxy resin composition to a desired thickness on the inorganic layer (II), then bonding the coated surface to the substrate (IB), and then curing the epoxy resin composition to form the cured material layer (III).

[0054] Examples of coating methods for applying the epoxy resin composition include bar coating, Mayer bar coating, air knife coating, gravure coating, reverse gravure coating, microgravure coating, microreverse gravure coating, die coating, slot die coating, vacuum die coating, dip coating, spin coating, roll coating, spray coating, and brush coating. Among these, bar coating, roll coating, and spray coating are preferred, and industrially, gravure coating, reverse gravure coating, microgravure coating, and microreverse gravure coating are preferred. After applying the epoxy resin composition, a step of volatilizing the solvent (drying step) is optionally performed. The conditions for the drying step can be appropriately selected, but can be, for example, a drying temperature of 60 to 180°C and a drying time of 5 to 180 seconds. After the drying step, the epoxy resin composition is cured to form a cured layer (III). The curing temperature can be selected, for example, from 10 to 140°C, preferably from 10 to 80°C. The curing time can be selected, for example, within the range of 0.5 to 200 hours, and is preferably within the range of 2 to 100 hours.

[0055] <Characteristics of Oxygen Absorber> The oxygen absorber of the present invention has oxygen absorbing properties and excellent gas barrier properties. For example, the oxygen permeability of the oxygen absorber at 23°C and a relative humidity of 60% varies depending on the barrier properties of the substrate (I) and inorganic layer (II) used, but is preferably 1 cc (m ２ ·day·atm) or less, more preferably 0.8 cc / (m ２ ·day·atm) or less, more preferably 0.6 cc / (m ２ ·day·atm) or less, and even more preferably 0.3 cc / (m ２ The oxygen permeability of the oxygen absorber can be measured specifically by the method described in the examples.

[0056] <Shape and Usage of Oxygen Absorber> The shape of the oxygen absorber of the present invention can be appropriately selected depending on the usage, and can be, for example, a sheet shape or a bag shape. Examples of usage of the oxygen absorber include a method in which a film-shaped oxygen absorber is enclosed inside a packaging material such as a container or a packaging bag; a method in which the oxygen absorber is used as a packaging material; etc.

[0057] [Method for Preserving an Article] The method for preserving an article according to the present invention is a method for preserving an article using the oxygen absorber, and the method includes one or more of the following aspects (1) or (2). (1) The article is housed in a packaging material in which the oxygen absorber is enclosed. (2) The article is housed in a packaging material having the oxygen absorber in at least a part thereof, and the oxygen permeability of the packaging material is 1 cc / (m ２ Since the oxygen absorber has oxygen absorbing properties, the article preservation method of the present invention (hereinafter also simply referred to as the "method of the present invention") can effectively suppress oxidative deterioration of the article to be preserved.

[0058] In the above-mentioned embodiment (1), the article is housed in a packaging material in which the oxygen absorber is enclosed. The shape of the oxygen absorber used in the above-mentioned embodiment (1) may be any shape that can be enclosed in the packaging material, and is preferably a sheet shape. The oxygen absorber may be attached to the inside of the packaging material, or may be enclosed in a packaging bag in the state where it is enclosed in the packaging material.

[0059] The form of the packaging material used in the embodiment (1) can be appropriately selected depending on the item to be stored or preserved, and examples thereof include packaging films; packaging containers such as packaging bags and bottles; and lids and sealing materials for packaging containers. Specific examples of packaging films or bags include three-sided sealed flat bags, standing pouches, gusseted packaging bags, pillow packaging bags, multi-chamber pouches consisting of a main chamber and an auxiliary chamber with an easily peelable wall between them, and shrink film packaging. The thickness and volume of the packaging material are also not particularly limited and can be appropriately selected depending on the item to be preserved. The material of the packaging material used in the embodiment (1) is not particularly limited, but is preferably a packaging material with gas barrier properties. For example, when the packaging material is a packaging bag, examples include aluminum packaging bags and packaging bags made of a plastic substrate with a transparent vapor deposition layer.

[0060] In the embodiment (2), the article is housed in a packaging material having the oxygen absorber in at least a part thereof, and the oxygen permeability of the packaging material is 1 cc / (m ２ ·day·atm) or less. From the viewpoint of effectively suppressing oxidative deterioration of the article, the packaging material is preferably a packaging material made of the oxygen absorbing material. The oxygen permeability of the packaging material used in the embodiment (2) is a value measured at 23°C and a relative humidity of 60% by the method described in the Examples, and is preferably 0.8 cc / (m ２ ·day·atm) or less, more preferably 0.6 cc / (m ２ ·day·atm) or less, more preferably 0.3 cc / (m ２ ・day・atm) or less.

[0061] The form of the packaging material used in the above embodiment (2) is preferably a packaging film or a packaging bag, from the viewpoint of containing the oxygen absorber in at least a part thereof, and specific examples thereof are the same as those described in the above embodiment (1). The thickness and volume of the packaging material are not particularly limited and can be selected appropriately depending on the item to be stored. The method of the present invention may be a method including the above embodiments (1) and (2).

[0062] Examples of items to be preserved in the method of the present invention include food, beverages, seasonings, chemicals, pharmaceuticals, cosmetics, pet food, detergents, etc. The item preferably contains water, from the viewpoint of triggering moisture to enhance the oxygen absorption of the oxygen absorber. For example, when the item to be preserved is food, the water activity (Aw) of the food is preferably 0.75 or more, more preferably 0.80 or more, even more preferably 0.85 or more, even more preferably 0.90 or more, and even more preferably 0.95 or more, from the viewpoint of triggering moisture to enhance the oxygen absorption of the oxygen absorber. Here, the water activity Aw of a food is defined as the ratio of the water vapor pressure P in a sealed system containing the food to the vapor pressure PO of pure water at that temperature, where Aw = P / PO. Furthermore, the water activity Aw of a food is expressed as Aw = RH / 100, where RH (%) is the relative humidity in a sealed system containing the food.

[0063] In the method of the present invention, from the viewpoint of enhancing the oxygen absorbing ability of the oxygen absorber, the temperature inside the packaging material containing the article is preferably 5° C. or higher, more preferably 10° C. or higher, even more preferably 25° C. or higher, and usually 80° C. or lower. Alternatively, in the method of the present invention, the packaging material containing the article is stored in an environment of preferably 5° C. or higher, more preferably 10° C. or higher, even more preferably 25° C. or higher, and usually 80° C. or lower.

[0064] In the method of the present invention, the relative humidity inside the packaging material containing the article is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more and 100% or less, from the viewpoint of enhancing the oxygen absorbing ability of the oxygen absorber. Alternatively, in the method of the present invention, the packaging material containing the article is stored in an environment with a relative humidity of preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more and 100% or less.

[0065] [Use] The present invention further provides use of a laminate comprising a substrate (I), an inorganic layer (II), and a cured material layer (III) of an epoxy resin composition containing an epoxy resin and an epoxy resin curing agent including an amine-based curing agent, wherein the inorganic layer (II) and the cured material layer (III) are adjacent to each other, as an oxygen absorber. Details and preferred embodiments of the substrate (I), inorganic layer (II), cured material layer (III), and the laminate are the same as those described for the oxygen absorber.

[0066] The present invention will now be described in detail with reference to examples. However, the present invention is not limited to these examples. Measurements and evaluations in these examples were carried out by the following methods.

[0067] <Thickness of Cured Layer> The thickness was measured using a multilayer film thickness measuring device ("DC-8200" manufactured by Gunze Co., Ltd.).

[0068] <Oxygen absorption amount (cc / g)> The film-like oxygen absorber obtained in each example was cut to prepare four 5 cm x 15 cm strip-shaped test pieces. These were placed in an approximately 21 cm x 15 cm aluminum bag, and 200 cc of air was then sealed in the bag. The humidity inside the bag was adjusted to the humidity shown in the table, and then the bag was sealed. The aluminum bag was stored for a predetermined period at the temperature shown in the table, and the oxygen concentration inside the bag was measured using a zirconia-type oxygen concentration measuring device ("LC-750F" manufactured by Toray Engineering Co., Ltd.), and the oxygen absorption amount per oxygen absorber was calculated.

[0069] Production Example 1 (Preparation of Epoxy Resin Curing Agent Solution A) A reaction vessel was charged with 1 mol of metaxylylenediamine (MXDA). The temperature was raised to 60°C under a nitrogen stream, and 0.93 mol of methyl acrylate was added dropwise over 1 hour. The temperature was raised to 165°C while distilling off the resulting methanol, and the temperature was maintained at 165°C for 2.5 hours to obtain an amine-based curing agent. Methanol was added dropwise thereto over 1.5 hours, and then a silane coupling agent, 3-aminopropyltriethoxysilane ("KBE-903" manufactured by Shin-Etsu Chemical Co., Ltd.), was added to obtain an epoxy resin curing agent solution A containing 62.2% by mass of the amine-based curing agent, 2.8% by mass of 3-aminopropyltriethoxysilane, and 35% by mass of methanol.

[0070] Production Example 2 (Preparation of Epoxy Resin Composition A) 2.15 g of methanol as a dilution solvent and 3.25 g of ethyl acetate were added and stirred thoroughly. Next, 3.13 g of the epoxy resin curing agent solution A obtained in Production Example 1 was added and stirred. 1.46 g of an epoxy resin having a glycidylamino group derived from metaxylylenediamine ("TETRAD-X" manufactured by Mitsubishi Gas Chemical Company, Inc.) (number of active hydrogen atoms in the epoxy resin curing agent / number of epoxy groups in the epoxy resin=0.8) was added as an epoxy resin and stirred to prepare epoxy resin composition A.

[0071] Production Example 3 (Preparation of Epoxy Resin Composition B) Epoxy resin composition B was prepared in the same manner as in Production Example 2, except that the blended amount of methanol as a dilution solvent was changed to 1.98 g, the blended amount of epoxy resin curing agent solution A obtained in Production Example 1 was changed to 3.64 g, and the blended amount of epoxy resin having a glycidylamino group derived from metaxylylenediamine ("TETRAD-X" manufactured by Mitsubishi Gas Chemical Company, Inc.) was changed to 1.13 g (number of active hydrogens in epoxy resin curing agent / number of epoxy groups in epoxy resin=1.2).

[0072] Production Example 4 (Preparation of Epoxy Resin Composition C) Epoxy resin composition C was prepared in the same manner as in Production Example 2, except that the blended amount of methanol as a dilution solvent was changed to 1.56 g, the blended amount of epoxy resin curing agent solution A obtained in Production Example 1 was changed to 4.83 g, and the blended amount of epoxy resin having a glycidylamino group derived from metaxylylenediamine ("TETRAD-X" manufactured by Mitsubishi Gas Chemical Company, Inc.) was changed to 0.36 g (number of active hydrogens in epoxy resin curing agent / number of epoxy groups in epoxy resin=5.0).

[0073] Production Example 5 (Preparation of Epoxy Resin Composition D) Epoxy resin composition D was prepared in the same manner as in Production Example 2, except that the amounts of methanol as a dilution solvent were changed to 3.62 g, ethyl acetate to 4.30 g, epoxy resin curing agent solution A obtained in Production Example 1 to 1.93 g, and epoxy resin having a glycidylamino group derived from metaxylylenediamine ("TETRAD-X" manufactured by Mitsubishi Gas Chemical Company, Inc.) to 0.14 g (number of active hydrogen atoms in epoxy resin curing agent / number of epoxy groups in epoxy resin=5.0).

[0074] Production Example 6 (Preparation of Epoxy Resin Composition E) Epoxy resin composition E was prepared in the same manner as in Production Example 2, except that the amount of methanol as the dilution solvent was changed to 2.47 g, the amount of epoxy resin curing agent solution A obtained in Production Example 1 was changed to 2.20 g, and 0.31 g (number of active hydrogens in epoxy resin curing agent / number of epoxy groups in epoxy resin=5.0) of a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A (manufactured by Mitsubishi Chemical Corporation, "jER828"; epoxy equivalent: 186 g / equivalent) was used instead of the epoxy resin having a glycidylamino group derived from metaxylylenediamine (manufactured by Mitsubishi Gas Chemical Company, Inc., "TETRAD-X").

[0075] Production Example 7 (Preparation of Epoxy Resin Composition F) Epoxy resin composition F was prepared in the same manner as in Production Example 2, except that the blended amount of methanol as a dilution solvent was changed to 2.40 g, the blended amount of epoxy resin curing agent solution A obtained in Production Example 1 was changed to 2.40 g, and 0.18 g (number of active hydrogens in epoxy resin curing agent / number of epoxy groups in epoxy resin=5.0) of an epoxy resin having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., "TETRAD-C") was used instead of the epoxy resin having a glycidylamino group derived from metaxylylenediamine (manufactured by Mitsubishi Gas Chemical Company, Inc., "TETRAD-X").

[0076] Example 1 (Preparation and Evaluation of Oxygen Absorber) Epoxy resin composition A obtained in Production Example 2 was applied to the aluminum-vapor-deposited surface of aluminum-vapor-deposited CPP ("Chemilite S-F-1" manufactured by Nakai Industrial Co., Ltd., thickness 25 μm), using a bar coater No. 8. The epoxy resin composition was dried by heating at 80°C for 10 seconds (thickness after drying: 3 μm). A biaxially oriented polypropylene (OPP) film ("FOR" manufactured by Futamura Chemical Co., Ltd., thickness 20 μm) was laminated thereon using nip rolls and heated at 40°C for 2 days to obtain an oxygen absorber having the layer structure shown in Table 1. Using this oxygen absorber, the oxygen absorption capacity was measured using the method described above. In measuring the oxygen absorption capacity, the humidity inside the aluminum bag was controlled by sealing moistened absorbent cotton inside the bag. The results are shown in Table 1. In the following tables, "A / E" means the number of active hydrogen atoms in the epoxy resin curing agent / the number of epoxy groups in the epoxy resin.

[0077] Examples 2 to 4 Oxygen absorbers were prepared in the same manner as in Example 1, except that the epoxy resin compositions in Example 1 were changed to those shown in Table 1, and the oxygen absorption amounts were measured by the same method as in Example 1. The results are shown in Table 1.

[0078] Comparative Example 1: In Example 1, an oxygen absorber was prepared using a urethane adhesive instead of epoxy resin composition A, as follows. The urethane adhesive was prepared by adding 0.8 g of CAT-RT37-0.8K as a curing agent and 38.7 g of ethyl acetate as a solvent to 17 g of TM-569 as a base resin, and thoroughly stirring. The urethane adhesive was applied to the aluminum-deposited surface of the aluminum-deposited CPP using a bar coater No. 12 and dried at 80°C for 10 seconds to form an adhesive layer (thickness after drying: 3 μm). A 20 μm-thick OPP film was laminated onto the adhesive using a nip roll and heated at 40°C for 2 days to obtain an oxygen absorber having the layer structure shown in Table 1. Using this oxygen absorber, the oxygen absorption capacity was measured using the same method as described above. In measuring the oxygen absorption capacity, the humidity inside the aluminum bag was controlled by sealing moistened absorbent cotton inside the bag. The results are shown in Table 1.

[0079]

[0080] It can be seen from Table 1 that the oxygen absorber of the present invention has better oxygen absorbing properties than the oxygen absorbers of the comparative examples. Furthermore, a comparison of Examples 1 to 3 shows that in the epoxy resin composition used in the cured product layer, when the ratio of the number of active hydrogen atoms in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin was in the range of 1.2 to 5.0, the amount of oxygen absorbed was increased.

[0081] Example 5: The epoxy resin composition A obtained in Production Example 2 was applied to the aluminum-vapor-deposited surface of a polyethylene terephthalate (PET) film ("ML-PET" manufactured by Mitsui Chemicals Tohcello, Inc., thickness 12 μm), which had aluminum vapor-deposited on one side, using a bar coater No. 8. The epoxy resin composition was dried by heating at 80°C for 10 seconds (thickness after drying: 3 μm). A non-oriented polypropylene (CPP) film ("P1146" manufactured by Toyobo Co., Ltd., thickness 50 μm) was laminated thereon using nip rolls and heated at 40°C for 2 days to obtain an oxygen absorbent having the layer structure shown in Table 2. The oxygen absorption capacity of this oxygen absorbent was measured using the method described above. In measuring the oxygen absorption capacity, the humidity inside the aluminum bag was controlled by sealing moistened absorbent cotton inside the bag. The results are shown in Table 2.

[0082] An oxygen absorber was prepared in the same manner as in Example 5, except that the epoxy resin composition C obtained in Production Example 4 was used instead of the epoxy resin composition A in Example 5, and the oxygen absorption amount was measured by the same method as above. The results are shown in Table 2.

[0083] Example 7 An oxygen absorber was prepared in the same manner as in Example 5, except that aluminum-deposited OPP ("ML-OP102" manufactured by Mitsui Chemicals Tohcello, Inc., thickness 12 μm) in which aluminum was deposited on one side of a stretched polypropylene (OPP) film was used instead of the aluminum-deposited PET in Example 5, and the oxygen absorption amount was measured by the same method as in Example 5. The results are shown in Table 2.

[0084] An oxygen absorber was prepared in the same manner as in Example 6, except that the aluminum-deposited OPP was used instead of the aluminum-deposited PET, and the oxygen absorption amount was measured in the same manner as in Example 6. The results are shown in Table 2.

[0085]

[0086] Example 9: The epoxy resin composition A obtained in Production Example 2 was applied to the alumina-deposited surface of a polyethylene terephthalate (PET) film ("Barrierox 1011HG" manufactured by Toray Advanced Film Co., Ltd., thickness 12 μm), which had alumina vapor-deposited on one side, using a bar coater No. 8. The epoxy resin composition was dried by heating at 80°C for 10 seconds (thickness after drying: 3 μm). A non-oriented polypropylene (CPP) film ("P1146" manufactured by Toyobo Co., Ltd., thickness 50 μm) was laminated thereon using a nip roll and heated at 40°C for 2 days to obtain an oxygen absorbent having the layer structure shown in Table 3. The oxygen absorption capacity of this oxygen absorbent was measured using the method described above. In measuring the oxygen absorption capacity, the humidity inside the aluminum bag was controlled by sealing moistened absorbent cotton inside the bag. The results are shown in Table 3.

[0087] An oxygen absorber was prepared in the same manner as in Example 9, except that the epoxy resin composition C obtained in Production Example 4 was used instead of the epoxy resin composition A in Example 9, and the oxygen absorption amount was measured by the same method as above. The results are shown in Table 3.

[0088] Example 11 An oxygen absorber was prepared in the same manner as in Example 9, except that silica-deposited PET ("Techbarrier TCBL" manufactured by Mitsubishi Chemical Holdings Group, thickness 12 μm) in which silica was deposited on one side of a polyethylene terephthalate (PET) film was used instead of the alumina-deposited PET in Example 9, and the oxygen absorption amount was measured in the same manner as in Example 9. The results are shown in Table 3.

[0089] Example 12 An oxygen absorber was prepared in the same manner as in Example 10, except that the silica-deposited PET was used instead of the alumina-deposited PET, and the oxygen absorption amount was measured in the same manner as in Example 10. The results are shown in Table 3.

[0090]

[0091] Table 2 shows examples in which the types of substrates (IA) and (IB) constituting the oxygen absorber were changed, and Table 3 shows examples in which the type of inorganic layer (II) constituting the oxygen absorber was changed. From Table 2, it can be seen that, for the combinations of substrates (IA) and (IB), the configurations of Examples 1 and 3 showed the greatest increase in oxygen absorption. Furthermore, from Table 3, it can be seen that when the inorganic layer (II) was an aluminum vapor-deposited layer, the oxygen absorption amount was greater than when it was an alumina vapor-deposited layer or a silica vapor-deposited layer.

[0092] Example 13 The amount of oxygen absorbed was measured in the same manner as in Example 1, except that the storage temperature of the oxygen absorber was changed to 23° C. The results are shown in Table 4.

[0093] Example 14 The amount of oxygen absorbed was measured in the same manner as in Example 3, except that the storage temperature of the oxygen absorber was changed to 23° C. The results are shown in Table 4.

[0094]

[0095] From Table 4, it can be seen that the oxygen absorption amount is greater when the oxygen absorber is stored at 40°C than when it is stored at 23°C.

[0096] Examples 15 to 20 Using the oxygen absorbers prepared in Example 3, the oxygen absorption amounts were measured in the same manner as in Example 3, except that the humidity in the aluminum bag was adjusted to the humidity shown in Table 5 using water and glycerin. The results are shown in Table 5.

[0097]

[0098] From Table 5, it can be seen that the higher the humidity during storage of the oxygen absorber, the greater the amount of oxygen absorbed.

[0099] Example 21 Example 21 illustrates the use of aluminum foil as the inorganic layer (II). The urethane adhesive (prepared by adding 17 g of TM-569 as the base agent, 0.8 g of CAT-RT37-0.8K as the curing agent, and 38.7 g of ethyl acetate as the solvent, and stirring thoroughly) was applied to one side of a polyethylene terephthalate film (thickness 12 μm) using a bar coater No. 12 and dried at 80°C for 10 seconds to form an adhesive layer (thickness after drying: 3 μm). A 7 μm-thick aluminum foil was then bonded onto the adhesive layer using a nip roll. Next, the epoxy resin composition C obtained in Production Example 4 was applied to the aluminum foil surface using a bar coater No. 8 and dried by heating at 80°C for 10 seconds (thickness after drying: 3 μm). A non-oriented polypropylene (CPP) film ("P1146" manufactured by Toyobo Co., Ltd., thickness 50 μm) was laminated thereon using nip rolls and heated at 40° C. for 2 days to obtain an oxygen absorber having the layer structure shown in Table 6. The oxygen absorption amount was measured using this oxygen absorber by the above-mentioned method. The results are shown in Table 6.

[0100]

[0101] Examples 22 to 23 Oxygen absorbers were prepared in the same manner as in Example 3, except that the epoxy resin compositions shown in Table 7 were used, and the oxygen absorption amounts were measured by the same method as in Example 3. The results are shown in Table 7.

[0102]

[0103] Example 24 (Storage Method) A white ink (Sakata Inx Corporation's "Bellcolor R115" diluted two-fold with a diluent (Sakata Inx Corporation's "L Solvent")) was applied to one side of a biaxially oriented polypropylene (OPP) film (Futamura Chemical Co., Ltd., thickness 20 μm) using a bar coater No. 8, and dried by heating at 80° C. for 10 seconds (thickness after drying: approximately 0.5 μm) to form a colored layer. A reverse printing gravure ink (Sakata Inx Corporation's "Bellflora R Medium" diluted two-fold with a diluent (Sakata Inx Corporation's "K Solvent")) was applied to the colored layer using a bar coater No. 8, and dried by heating at 80° C. for 10 seconds (thickness after drying: approximately 0.5 μm) to form a medium layer. The epoxy resin composition C obtained in Production Example 4 was applied onto the medium layer using a No. 8 bar coater and dried by heating at 80°C for 10 seconds (thickness after drying: 3 μm). The surface coated with the epoxy resin composition was superimposed on the aluminum-deposited surface of an aluminum-deposited CPP film ("Chemilite S-F-1" manufactured by Nakai Industrial Co., Ltd., thickness 25 μm), in which aluminum was vapor-deposited on one side of the CPP film. These were then bonded together using nip rolls and heated at 40°C for 2 days to obtain an oxygen absorber having a structure in which the CPP film (substrate (IA)) / aluminum-deposited layer (II) / cured product layer (III) / medium layer / colored layer / OPP film (substrate (IB)) were laminated in this order. The oxygen absorber was then made into a bag with the substrate (IA) side facing inward, to produce a bag-shaped packaging material. The oxygen permeability of the oxygen absorber constituting the packaging material was 0.09 cc / (m ２ ·day·atm). The oxygen permeability was measured by the method described below. Pieces of rice cake (Fig. 1(a), water activity Aw: 0.99) were placed in a bag-shaped packaging material and sealed, and the packaging material was stored for two months in an environment of 40°C and a relative humidity of 90%. The initial amount of oxygen in the packaging material was 10 cc, and the initial oxygen concentration in the packaging material was 20.8%. After storage for two months, the appearance of the pieces of rice cake was visually observed, and no change in appearance was observed (Fig. 1(b)).

[0104] <Measurement of Oxygen Permeability> The oxygen permeability was measured under conditions of 23° C. and a relative humidity of 60% using an oxygen permeability measuring device ("OX-TRAN2 / 21" manufactured by Modern Controls).

[0105] Comparative Example 2: In Example 24, the epoxy resin composition C obtained in Production Example 4 was replaced with the urethane adhesive (prepared by adding 0.8 g of CAT-RT37-0.8K as a curing agent and 38.7 g of ethyl acetate as a solvent to 17 g of TM-569 as a base agent and stirring thoroughly), and the rice cakes were stored in the same manner as in Example 24. The oxygen permeability of the oxygen absorber constituting the packaging material was 2.7 cc / (m ２ After storage for two months, the appearance of the rice cake was visually observed, and the growth of mold was observed (FIG. 1(c)).

[0106] Comparative Example 3 The urethane adhesive was applied to one side of an aluminum foil (thickness 7 μm) using a bar coater No. 12 and dried at 80 ° C for 10 seconds to form an adhesive layer (thickness after drying: 3 μm). A PET film ("E5100" manufactured by Toyobo Co., Ltd., thickness 12 μm) was bonded thereon using a nip roll and heated at 40 ° C for 2 days to obtain a laminate film having an aluminum foil (II) / urethane adhesive layer / PET film laminated in that order. Thereafter, the urethane adhesive was applied to the aluminum foil surface of the laminate film using a bar coater No. 12 and dried at 80 ° C for 10 seconds to form an adhesive layer (thickness after drying: 3 μm). A non-oriented polypropylene (CPP) film ("P1146" manufactured by Toyobo Co., Ltd., thickness 50 μm) was laminated thereon using nip rolls and heated at 40° C. for 2 days to obtain a laminate having a structure in which CPP / urethane adhesive layer / aluminum foil (II) / urethane adhesive layer / PET film were laminated in this order. The laminate was made into a bag with the aluminum foil (II) side facing inward to produce a bag-shaped packaging material. The oxygen permeability of the laminate constituting the packaging material was 0.01 cc / (m ２·day·atm) or less. The rice cakes (Fig. 1(a)) were placed in a bag-shaped packaging material and sealed, and the packaging material was stored for two months in an environment of 40°C and a relative humidity of 90%, as in Example 24. The initial amount of oxygen in the packaging material was 10 cc, and the initial oxygen concentration in the packaging material was 20.8%. After two months of storage, the appearance of the rice cakes was visually observed, and mold growth was confirmed (Fig. 1(d)). In Comparative Example 3, mold grew on the rice cakes (contents) despite the use of a packaging material with high oxygen barrier properties. This is thought to be because the packaging material used did not exhibit oxygen absorption properties, causing deterioration of the contents due to residual oxygen in the packaging material.

[0107] Example 25 A storage stability evaluation was carried out in the same manner as in Example 24, except that the product contained in the packaging material was changed to cheese tara (FIG. 2(a), water activity Aw: 0.99). After storage for 2 months, the appearance of the cheese tara was visually observed, and no change in appearance was observed (FIG. 2(b)).

[0108] Comparative Example 4 A storage stability evaluation was carried out in the same manner as in Comparative Example 2, except that the product contained in the packaging material was changed to cheese cod. After storage for two months, the appearance of the cheese cod was visually observed, and the growth of mold was found (FIG. 2(c)).

[0109] Comparative Example 5 A storage stability evaluation was carried out in the same manner as in Comparative Example 3, except that the product contained in the packaging material was changed to cheese cod. After storage for two months, the appearance of the cheese cod was visually observed, and the growth of mold was found (FIG. 2(d)).

[0110] According to the present invention, it is possible to provide an oxygen absorber that is particularly suitable for preserving moisture-containing articles or articles in a high-humidity environment, and a method for preserving articles using the oxygen absorber.

Claims

1. Base material (I), An inorganic layer (II), and An oxygen absorbing material comprising a cured material layer (III) of an epoxy resin composition containing an epoxy resin and an epoxy resin curing agent including an amine-based curing agent, wherein the inorganic layer (II) and the cured material layer (III) are adjacent to each other.

2. 2. The oxygen absorber according to claim 1, wherein the amine-based curing agent comprises a reaction product of the following components (A) and (B): (A) at least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine (B) At least one member selected from the group consisting of unsaturated carboxylic acids and derivatives thereof represented by the following general formula (1): 【Chemistry 1】 (In formula (1), R １ , R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms.

3. 2. The oxygen absorber according to claim 1, wherein the inorganic layer (II) is an aluminum vapor deposition layer.

4. 2. The oxygen absorber according to claim 1, wherein the substrate (I) is a plastic film.

5. The oxygen absorbing material according to claim 1, which comprises, in order, a substrate (IA), the inorganic layer (II), the cured material layer (III), and a substrate (IB).

6. 6. The oxygen absorber according to claim 5, wherein the substrate (IA) and the substrate (IB) are substrates made of the same type of resin.

7. 7. The oxygen absorber according to claim 6, wherein the substrate (IA) and the substrate (IB) are polypropylene films.

8. 2. The oxygen absorber according to claim 1, wherein in the epoxy resin composition, a ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin (number of active hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin) is in the range of 0.2 to 8.

0.

9. A method for preserving an article by using the oxygen absorbing material according to any one of claims 1 to 8, the method comprising one or more of the following aspects (1) or (2). (1) The article is housed in a packaging material in which the oxygen absorbing material is enclosed. (2) The article is housed in a packaging material having at least a part of the oxygen absorbing material, and the oxygen permeability of the packaging material is 1 cc / (m ２ ・day・atm) or less.

10. 10. The method of claim 9, wherein the relative humidity within the packaging is 85% or greater.

11. The method according to claim 9, wherein the packaging material containing the article is stored in an environment with a relative humidity of 85% or more.

12. The method of claim 9 , wherein the article contains water.

13. Base material (I), An inorganic layer (II), and 1. Use of a laminate as an oxygen absorber, comprising a cured layer (III) of an epoxy resin composition containing an epoxy resin and an epoxy resin curing agent including an amine-based curing agent, the laminate being adjacent to an inorganic layer (II).

Images