Oxygen scavenger composition

Abstract

Provided is an oxygen scavenger composition for which the initial oxygen absorption by the composition is suppressed, thereby making it possible for the composition to exhibit sufficient oxygen absorption performance even after being handled in the atmosphere for a certain amount of time. This oxygen scavenger composition contains: a metal halide-coated iron powder (A) obtained by coating a reduced iron powder having an iron oxide on the iron surface with a metal halide; and a moisture-donating agent (B). The proportion of the element iron in the iron powder that results from excluding the metal halide and moisture from the metal halide-coated iron powder (A) is 97.0-99.3 mass%, and the metal halide content is 0.01-1.0 parts by mass per 100 parts by mass of the iron powder that results from excluding the metal halide and moisture from the metal halide-coated iron powder (A).

Description

Oxygen absorber composition

[0001] This invention relates to an oxygen absorber composition.

[0002] A known preservation technique for food, pharmaceuticals, and other items involves using oxygen absorbers. In this method, the items to be preserved and the oxygen absorber are sealed within a gas-barrier container. The oxygen absorber absorbs the oxygen inside the container, maintaining a substantially oxygen-free environment. The oxygen absorber needs to be small and capable of absorbing a large amount of oxygen. In other words, an oxygen absorber composition with a high oxygen absorption rate per unit volume is required.

[0003] Typical oxygen absorbers include iron-based oxygen absorbers, which primarily use iron (iron powder), and non-ferrous oxygen absorbers, which primarily use ascorbic acid or glycerin. While oxygen absorbers are selected appropriately depending on the application, iron-based oxygen absorbers are widely used from the standpoint of oxygen absorption performance. Iron-based oxygen absorbers can be either water vapor from an oxygen-deoxidizing environment (such as evaporation from food) (moisture-dependent type) or have a water-containing carrier pre-encapsulated within the oxygen absorber (self-reacting type). Self-reacting oxygen absorbers have the advantage of being able to absorb oxygen even when the external humidity is relatively low because they contain a water donor.

[0004] Halide metals and the like are used as oxidation accelerators to efficiently supply moisture to the iron surface from a moisture donor. For example, Patent Document 1 discloses an oxygen absorber characterized by comprising iron powder, an oxidation accelerator, a filler, and a moisture donor made of diatomaceous earth containing moisture, which has adsorption properties that show a relative humidity of 55% or more when it contains 2% moisture, with the aim of obtaining an oxygen absorber that is compact and inexpensive yet has high oxygen absorption capacity.

[0005] Japanese Patent Application Publication No. 5-237374

[0006] As mentioned above, moisture-dependent oxygen absorbers can only exhibit oxygen absorption performance in environments where moisture can be supplied from the outside, thus limiting their applications. Self-reacting oxygen absorbers have the advantage of being able to absorb oxygen even when the external humidity is relatively low, but they react immediately upon contact with oxygen, and the reaction progresses during the process of sealing them in a product, resulting in a decrease in oxygen absorption performance. On the other hand, for example, if a self-reacting oxygen absorber is manufactured without adding an oxidation accelerator, the initial oxidation reaction can be suppressed, but the oxygen absorption performance after sealing in a product will also be inferior, and it will not have sufficient performance as an oxygen absorber. The present invention has been made in view of these circumstances, and the object of the present invention is to provide a self-reacting oxygen absorber composition in which initial oxygen absorption is suppressed and sufficient oxygen absorption performance can be exhibited even after being handled in the atmosphere for a certain period of time.

[0007] The inventors have discovered that an oxygen scavenger composition comprising metal halide coated iron powder having an iron oxide on a specific iron surface and a moisture donor can solve the above problems, and have completed the invention.

[0008] In other words, the present invention relates to the following [1] to

[22] . [1] A deoxidizing agent composition comprising metal-halide coated iron powder (A), in which reduced iron powder having iron oxide on the iron surface is coated with a metal halide, and a moisture donor (B), wherein the proportion of iron elements in the iron powder after removing the metal halide and moisture from the metal-halide coated iron powder (A) is 97.0 to 99.3% by mass, and the content of the metal halide is 0.01 to 1.0 parts by mass per 100 parts by mass of the iron powder after removing the metal halide and moisture from the metal-halide coated iron powder (A). [2] The deoxidizing agent composition according to [1], wherein the average particle size of the metal-halide coated iron powder (A) is 30 to 500 μm. [3] The deoxidizing agent composition according to [1] or [2], wherein the metal halide is at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, and sodium bromide. [4] The specific surface area of ​​the reduced iron powder is 0.06 to 0.12 m². ２[1] to [3] above, wherein the oxygen absorber composition is / g. [5] The oxygen absorber composition according to any one of [1] to [4] above, wherein the moisture donor (B) is a carrier impregnated with water. [6] The oxygen absorber composition according to any one of [1] to [5] above, wherein the moisture donor (B) contains sodium chloride. [7] The oxygen absorber composition according to [5] or [6] above, wherein the amount of water contained in the moisture donor (B) is 15 to 60 parts by mass per 100 parts by mass of iron powder obtained by removing the metal halide from metal halide coated iron powder (A). [8] The oxygen absorber composition according to any one of [5] to [7] above, wherein the carrier is at least one selected from the group consisting of zeolite, diatomaceous earth, silica gel, perlite, vermiculite, activated alumina, activated clay, granular activated carbon, and bentonite. [9] A method for producing an oxygen scavenger composition, comprising the steps of: step 1, mixing iron powder (a) and an aqueous solution of a metal halide in an oxygen-containing gas atmosphere and drying to obtain metal halide-coated iron powder (A) having iron oxide on the iron surface; and step 2, mixing the metal halide-coated iron powder (A) and a water donor (B), wherein the amount of metal halide contained in the aqueous solution of the metal halide is 0.01 to 1.00 parts by mass per 100 parts by mass of iron powder (a), and the proportion of iron element in the iron powder after removing the metal halide and water from the metal halide-coated iron powder (A) is 97.0 to 99.3% by mass.

[10] The method for producing an oxygen scavenger composition according to [9], wherein the amount of water contained in the aqueous solution of the metal halide is 7 to 25 parts by mass per 100 parts by mass of iron powder (a).

[11] The method for producing an oxygen scavenger composition according to [9] or

[10] , wherein the concentration of the aqueous solution of the metal halide is 0.08 to 10% by mass.

[12] A method for producing an oxygen absorber composition according to any one of [9] to

[11] , wherein in step 1, drying is performed by self-heating during mixing.

[13] A method for producing an oxygen absorber composition according to any one of [9] to

[12] , wherein the average particle size of the iron powder (a) is 30 to 500 μm.

[14] A method for producing an oxygen absorber composition according to any one of [9] to

[13] , wherein the metal halide is at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, and sodium bromide.

[15] A method for producing an oxygen scavenger composition according to any one of [9] to

[14] , wherein the water donor (B) is a carrier impregnated with water.

[16] A method for producing an oxygen scavenger composition according to any one of [9] to

[15] , wherein the water donor (B) contains sodium chloride.

[17] A method for producing an oxygen scavenger composition according to

[15] or

[16] , wherein the amount of water contained in the water donor (B) is 15 to 60 parts by mass per 100 parts by mass of iron powder obtained by removing the metal halide from metal halide coated iron powder (A).

[18] A method for producing an oxygen scavenger composition according to any one of

[15] to

[17] , wherein the carrier is at least one selected from the group consisting of zeolite, diatomaceous earth, silica gel, perlite, vermiculite, activated alumina, activated clay, granular activated carbon, and bentonite.

[19] An oxygen absorber package comprising an oxygen absorber composition according to any one of [1] to [8] above and a breathable packaging container containing the oxygen absorber composition.

[20] A method for manufacturing an oxygen absorber package, comprising containing the oxygen absorber composition according to any one of [1] to [8] above in a breathable packaging container.

[21] A method for deoxygenating, comprising containing the oxygen absorber composition according to any one of [1] to [8] above or the oxygen absorber package according to

[19] above and the object to be preserved in a gas barrier container.

[22] The method for deoxygenating according to

[21] above, wherein the object to be preserved is food, an industrial product, or a pharmaceutical product.

[0009] According to the present invention, it is possible to provide an oxygen absorber composition in which initial oxygen absorption is suppressed and sufficient oxygen absorption performance can be exhibited even after being handled in the atmosphere for a certain period of time.

[0010] [Oxygen Absorber Composition] The oxygen absorber composition of the present invention contains metal halide-coated iron powder (A), which is obtained by coating reduced iron powder having iron oxide on the iron surface with a metal halide, and a moisture donor (B), wherein the proportion of iron element in the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A) is 97.0 to 99.3% by mass, and the content of the metal halide is 0.01 to 1.0 parts by mass per 100 parts by mass of the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A).

[0011] The reason why the oxygen absorber composition of the present invention suppresses initial oxygen absorption and exhibits sufficient oxygen absorption performance even after being handled in the atmosphere for a certain period of time is not entirely clear, but it is thought to be as follows: When metal halide-coated iron powder and a moisture donor coexist in an oxygen-free environment, the humidity in the atmosphere increases due to the moisture donor. This causes the metal halide coating the iron powder to deliquesce, and moisture adheres to the surface of the iron powder. At this time, the presence of iron oxide on the surface of the iron powder increases the specific surface area, resulting in high dispersion of the metal halide, and it is thought that the moisture adhering to the surface of the iron powder is also in a highly dispersed state. Reduced iron powder has many lattice defects on its surface and many areas that are easily oxidized, so it is thought that it is possible to easily form an oxide film over the entire surface, and moisture and other substances are thought to be in a more highly dispersed state. When exposed to air in this state, the moisture adhering to the surface of the iron powder immediately disappears due to oxidation and evaporation of the iron powder. For the iron powder to be oxidized again from here, the metal halide needs to deliquesce again, but the time required for this second deliquescing suppresses initial oxygen absorption, and it is thought that deactivation due to oxygen absorption is reduced even when handled in the atmosphere. Therefore, it is believed that the oxygen absorption performance is preserved, and sufficient oxygen absorption performance can be exhibited even after handling in the atmosphere. In addition, it is thought that the presence of iron oxide on the surface of the iron powder forms an oxide film, which further suppresses initial oxygen absorption.

[0012] <Halogenated Metal-Coated Iron Powder (A)> The halogenated metal-coated iron powder (A) contained in the oxygen absorber composition of the present invention is obtained by coating reduced iron powder having iron oxide on the iron surface with a halogenated metal. The proportion of iron elements in the iron powder after removing the halogenated metal and water is 97.0 to 99.3% by mass, and the content of the halogenated metal is 0.01 to 1.0 parts by mass per 100 parts by mass of the halogenated metal-coated iron powder (A) after removing the halogenated metal and water. Note that halogenated metal-coated iron powder (A) usually has moisture absorbed on the iron surface. The moisture present on the surface is taken in by evaporation residue during the manufacture of the halogenated metal, moisture absorption from the atmosphere after manufacture, and moisture absorption from the moisture donor. When calculating the proportion of iron elements in the iron powder, if moisture is present on the iron surface, the amount of moisture is subtracted from the calculation. The amount of moisture is measured with a moisture meter. Specifically, the moisture content can be measured using a heated vaporization Karl Fischer moisture meter (Kyoto Electronics Manufacturing Co., Ltd.: MKC-610), etc.

[0013] The average particle size (D50) of the metal halide-coated iron powder (A) is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 400 μm or less, even more preferably 300 μm or less, even more preferably 200 μm or less, even more preferably 100 μm or less, even more preferably 90 μm or less, and even more preferably 10 μm or more, even more preferably 30 μm or more, even more preferably 40 μm or more, even more preferably 45 μm or more, even more preferably 50 μm or more, even more preferably 55 μm or more, and even more preferably 60 μm or more. More specifically, the average particle size (D50) of the metal halide-coated iron powder (A) is preferably 1 to 3000 μm, more preferably 10 to 1000 μm, even more preferably 30 to 500 μm, even more preferably 40 to 400 μm, even more preferably 45 to 300 μm, even more preferably 50 to 200 μm, even more preferably 55 to 100 μm, and even more preferably 60 to 90 μm. The average particle size can be measured as the average particle size (D50) at a cumulative frequency of 50% in the volume-based particle size distribution obtained by the laser diffraction / scattering particle size distribution measurement method. The average particle size can be measured using a commercially available laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by Horiba, Ltd.), etc.

[0014] (Iron Powder) In this section, "iron powder obtained by removing the halide metal and moisture from halide metal coated iron powder (A)" will be simply referred to as "iron powder" below. In other words, "iron powder" in this section is "iron powder obtained by removing the halide metal from halide metal coated iron powder (A) and further removing the moisture present on the surface." Furthermore, "iron powder obtained by removing the halide metal from halide metal coated iron powder (A) and further removing the moisture present on the surface" is distinguished from the "raw iron powder" described later. The iron powder is reduced iron powder having iron oxide on the iron surface, and the proportion of iron element in the iron powder is 97.0 to 99.3% by mass. Components other than the iron element include oxygen and hydrogen, with oxygen being the main component. In other words, it is preferable that the iron powder used in the oxygen scavenging agent composition of the present invention has iron oxide on its surface and a low proportion of iron element, while the interior of the iron powder has a high proportion of iron element. The proportion of iron elements in the iron powder is 97.0 to 99.3 mass%, preferably 97.5 to 99.1 mass%, more preferably 98.1 to 99.0 mass%, and from the viewpoint of improving oxygen absorption performance, even more preferably 98.3 to 98.9 mass%, and even more preferably 98.4 to 98.6 mass%. From the viewpoint of suppressing initial oxygen absorption, even more preferably 98.1 to 98.7 mass%, and even more preferably 98.3 to 98.6 mass%. When the proportion of iron elements in the iron powder is within the above range, initial oxygen absorption is suppressed, handling in the atmosphere becomes easier, and oxygen absorption performance is also excellent. The proportion of iron elements in the iron powder can be calculated from the amount of raw iron powder added during the production of metal halide coated iron powder. Furthermore, if the mass proportion in the sample is unknown, such as when total analysis of the produced metal halide coated iron powder is not possible, it can be determined by a calibration curve method using an inductively coupled plasma (ICP) emission spectrometer. The proportion of iron elements in the iron powder can be determined more specifically by the method described in the examples.

[0015] Furthermore, from the viewpoint of oxygen absorption performance, the specific surface area of ​​the reduced iron powder is preferably 0.03 m². ２ / g or more, more preferably 0.06m ２ It is 0.07 m or more per gram. ２ It is 1 / g or more, and from the viewpoint of suppressing dust generation, preferably 0.20 m ２ / g or less, more preferably 0.12 m ２ / g or less, still more preferably 0.10 m ２ / g or less. More specifically, the specific surface area of the raw iron powder is preferably 0.03 to 0.20 m ２ / g, more preferably 0.06 to 0.12 m ２ / g, still more preferably 0.07 to 0.10 m ２ / g. The specific surface area of the reduced iron powder can be measured by the BET multi-point method.

[0016] The iron powder (the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A)) can be produced by oxidizing the raw iron powder. The raw iron powder used as the raw material is reduced iron powder. It is considered that the reduced iron powder has fine irregularities on its surface, and thus has a high oxygen absorption suppression effect at the initial stage of oxygen absorption by the iron oxide on the surface. The "raw iron powder" refers to the iron powder that is the raw material of the metal halide-coated iron powder (A), before adjusting the amount of iron oxide on the surface and before being coated with the metal halide. The "iron powder (a)" in the manufacturing method of the deoxidizer composition described later is also included in the "raw iron powder". The raw iron powder can be used alone as one kind of reduced iron powder, or two or more kinds of reduced iron powders can be used in combination as needed. Commercially available products may also be used.

[0017] The average particle size (D50) of the raw iron powder is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 400 μm or less, even more preferably 300 μm or less, even more preferably 200 μm or less, even more preferably 100 μm or less, and even more preferably 90 μm or less, and from the viewpoint of suppressing dust generation, it is preferably 10 μm or more, more preferably 30 μm or more, even more preferably 40 μm or more, even more preferably 45 μm or more, even more preferably 50 μm or more, even more preferably 55 μm or more, and even more preferably 60 μm or more. More specifically, the average particle size (D50) of the raw iron powder is preferably 1 to 3000 μm, more preferably 10 to 1000 μm, even more preferably 30 to 500 μm, even more preferably 40 to 400 μm, even more preferably 45 to 300 μm, even more preferably 50 to 200 μm, even more preferably 55 to 100 μm, and even more preferably 60 to 90 μm. The average particle size can be measured as the average particle size (D50) at a cumulative frequency of 50% in the volume-based particle size distribution obtained by the laser diffraction / scattering particle size distribution measurement method. The average particle size can be measured using a commercially available laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by Horiba, Ltd.), etc.

[0018] Furthermore, from the viewpoint of oxygen absorption performance, the specific surface area of ​​the raw iron powder is preferably 0.03 m². ２ / g or more, more preferably 0.06m ２ It is 1 / g or more, and more preferably 0.07m ２ It is 1 / g or more, and from the viewpoint of suppressing dust generation, preferably 0.20 m ２ / g or less, more preferably 0.12m ２ / g or less, more preferably 0.10m ２ It is less than or equal to / g. More specifically, the specific surface area of ​​the raw iron powder is preferably 0.03 to 0.20 m². ２ / g, more preferably 0.06 to 0.12 m ２The value is / g, and more preferably 0.07 to 0.10 m ２ The value is / g. The specific surface area of ​​the raw iron powder can be measured using the BET multipoint method.

[0019] The proportion of iron element in the raw iron powder is preferably 97.1% by mass or more, and since it is necessary to control the iron element concentration of the iron powder by oxidation, high purity is preferable. The proportion of iron element in the raw iron powder is more preferably 97.5% by mass or more, even more preferably 98.0% by mass or more, even more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, and even more preferably 99.9% by mass or more.

[0020] The aforementioned iron powder (iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A)) is preferably obtained by oxidizing the surface of the raw iron powder. Methods for oxidizing the surface include oxidation with air, oxidation with chemicals, and oxidation with water, and these may be used in appropriate combinations. Among these, the method of oxidation in the presence of an aqueous solution of metal halide, as described later, is more preferable because it can simultaneously achieve metal halide coating and surface oxidation of the iron powder, and the amount of metal halide coating and surface oxidation, i.e., the iron concentration in the iron powder, can be easily controlled.

[0021] (Metal Halides) Metal halide-coated iron powder (A) has metal halides on its surface. Metal halides are substances that catalytically act on the oxidation reaction of iron and improve the activity of iron. In addition, metal halides play a role in preventing water contained in the oxygen absorber composition from evaporating and being lost from the oxygen absorber composition. Furthermore, the presence of metal halides on the surface of the iron powder allows moisture to be attracted to the surface of the iron powder by utilizing the deliquescence phenomenon of metal halides.

[0022] As for the metal halide, any generally known metal can be used without particular limitations. The metal in the metal halide is not particularly limited, but examples include one or more selected from the group consisting of alkali metals, alkaline earth metals, copper, zinc, aluminum, tin, iron, cobalt, and nickel. Among these, one or more selected from the group consisting of alkali metals, alkaline earth metals, and iron is preferred, one or more selected from the group consisting of lithium, potassium, sodium, magnesium, calcium, barium, and iron is more preferred, one or more selected from the group consisting of sodium and calcium is even more preferred, and calcium is even more preferred. Furthermore, the halide in the metal halide is not particularly limited, but examples include chlorides, bromides, and iodides, preferably one or more selected from the group consisting of chlorides and bromides, and more preferably chlorides.

[0023] From the standpoint of handling and safety, the metal halide is preferably at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, sodium bromide, calcium iodide, and sodium iodide; more preferably at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, and sodium bromide; even more preferably at least one selected from the group consisting of calcium chloride, calcium bromide, and sodium bromide; and most preferably calcium chloride. One type of metal halide can be used alone, or two or more types can be used in combination as needed. Furthermore, these metal halides may be in anhydrous or hydrated form, and readily available commercial products may be used.

[0024] The content of metal halides is 0.01 to 1.0 parts by mass per 100 parts by mass of iron powder obtained by removing metal halides and moisture from metal halide-coated iron powder (A). The content of metal halides is preferably 0.02 to 0.90 parts by mass, more preferably 0.03 to 0.80 parts by mass, even more preferably 0.05 to 0.60 parts by mass, even more preferably 0.06 to 0.50 parts by mass, even more preferably 0.07 to 0.40 parts by mass, even more preferably 0.08 to 0.20 parts by mass, and even more preferably 0.09 to 0.15 parts by mass per 100 parts by mass of iron powder obtained by removing metal halides and moisture from metal halide-coated iron powder (A), from the viewpoint of high oxygen absorption performance and suppression of initial oxygen absorption. Note that the content of metal halides in this invention refers to the content of metal halides only. In other words, if the metal halide in the metal halide-coated iron powder (A) is in the hydrated state, the amount of the metal halide is the amount obtained by subtracting the water of hydration from the hydrated metal halide.

[0025] The content of metal halides can be calculated from the amount of metal halides added during the production of metal halide-coated iron powder. Furthermore, if the total amount of metal halide-coated iron powder produced cannot be analyzed, or if the mass percentage in the sample is unknown, it can be quantified using, for example, the following method: Accurately weigh 1 g of metal halide-coated iron powder. Add 50 mL of pure water to the metal halide-coated iron powder, stir well, and then filter. Repeat this operation three times, collect all the filtrate, mix, add 5 mL of 400 μg / mL Co standard solution (manufactured by Kanto Chemical Co., Ltd., for chemical analysis) and pure water to bring the total volume to 200 mL to obtain the measurement solution. The above-mentioned measurement solution is measured using a multi-ICP emission spectrometer (SPECTRO ARCOS, manufactured by SPECTRO Analytical Instruments). From the target metal halide / Co intensity ratio and a separately prepared calibration curve, the amount of metal halide in the measurement solution, i.e., the amount of metal halide added per 1 g of metal halide-coated iron powder, can be determined.

[0026] <Oxygen supply agent (B)> The oxygen scavenger composition of the present invention contains an oxygen supply agent (B).The oxygen supply agent (B) is preferably one in which water is impregnated in a carrier (water-containing carrier). The oxygen supply agent (B) supplies water to iron.

[0027] The carrier may be any that can supply the supported moisture to the metal halide-coated iron powder (A). Generally, granular materials are preferably used. The carrier is preferably at least one selected from the group consisting of zeolite, diatomaceous earth, silica gel, perlite, vermiculite, activated alumina, activated clay, granular activated carbon, and bentonite, and more preferably at least one selected from the group consisting of zeolite, diatomaceous earth, and granular activated carbon. In this specification, granular activated carbon refers to activated carbon having an average particle diameter (D50 diameter measured by a laser diffraction / scattering particle size distribution measuring device) of 150 to 1000 μm. The average particle diameter of the granular activated carbon is 150 to 1000 μm, preferably 200 to 1000 μm. The granular activated carbon is an activated carbon with excellent water retention ability.

[0028] The amount of water contained in the oxygen supply agent (B) is preferably 15 to 60 parts by mass, more preferably 20 to 60 parts by mass, still more preferably 30 to 60 parts by mass, even more preferably 40 to 60 parts by mass, and even more preferably 40 to 55 parts by mass with respect to 100 parts by mass of the iron powder obtained by removing the metal halide from the metal halide-coated iron powder (A). When the amount of water contained in the oxygen supply agent (B) is within the above range, appropriate moisture can be supplied to the metal halide-coated iron powder (A), and a balance between the initial oxygen absorption rate and the oxygen absorption performance can be achieved.

[0029] The oxygen supply agent (B) preferably contains sodium chloride. By containing sodium chloride in the oxygen supply agent (B), the water activity can be adjusted, and a balance between the initial oxygen absorption rate and the oxygen absorption performance can be achieved.

[0030] The amount of sodium chloride contained in the water donor (B) is preferably 3 to 45 parts by mass, more preferably 4 to 40 parts by mass, even more preferably 15 to 37 parts by mass, even more preferably 25 to 37 parts by mass, and even more preferably 30 to 37 parts by mass, based on 100 parts by mass of water contained in the water donor (B). When the amount of sodium chloride contained in the water donor (B) is within the above range, the water activity can be adjusted, and a balance can be achieved between the initial oxygen absorption rate and the oxygen absorption performance.

[0031] <Additives> In addition to the above-mentioned metal halide-coated iron powder (A) and moisture donor (B), the oxygen absorber composition of the present invention may contain additives as needed. Examples of such additives include silica, alumina, and powdered activated carbon, for the purposes of promoting oxidation, preventing odor, suppressing dust, and providing microwave resistance. In particular, powdered activated carbon is preferred as an additive from the viewpoint of promoting oxidation and preventing odor. Powdered activated carbon refers to activated carbon with an average particle size (D50 diameter measured by a laser diffraction / scattering particle size distribution analyzer) of 1 to 80 μm. Powdered activated carbon exhibits excellent odor prevention effects due to its deodorizing ability. Furthermore, because it has a large surface area and is conductive, an oxidation-promoting effect through battery reaction can also be expected. The powdered activated carbon may be mixed with metal halide-coated iron powder (A) and then mixed with the moisture donor (B), or mixed with the moisture donor (B) and then mixed with the metal halide-coated iron powder (A), or mixed with a mixture of metal halide-coated iron powder (A) and the moisture donor (B). Among these, it is more preferable to mix with the moisture donor (B) and then mix with the metal halide-coated iron powder (A) in order to mix uniformly and stably. The content of the powdered activated carbon in the oxygen scavenger composition is preferably 0.1 to 1.0 parts by mass, and more preferably 0.3 to 0.8 parts by mass, per 100 parts by mass of iron powder obtained by removing the metal halide from metal halide-coated iron powder (A).

[0032] [Method for Producing Deoxidizer Composition] The deoxidizer composition of the present invention may be obtained by any production method, but it is preferably obtained by the production method of the present invention described below. The production method of the present invention comprises a step 1 of mixing iron powder (a) which is reduced iron powder and an aqueous solution of a metal halide in an oxygen-containing gas atmosphere and drying to obtain metal halide-coated iron powder (A) having iron oxide on the iron surface, and a step 2 of mixing the metal halide-coated iron powder (A) and a moisture-providing agent (B), wherein the amount of the metal halide contained in the aqueous solution of the metal halide is 0.01 to 1.0 parts by mass with respect to 100 parts by mass of the iron powder (a). This is a method for producing a deoxidizer composition.

[0033] <Step 1: Step of Obtaining Metal Halide-Coated Iron Powder (A)>The production method of the present invention has a step 1 of mixing iron powder (a) which is reduced iron powder and an aqueous solution of a metal halide in an oxygen-containing gas atmosphere and drying to obtain metal halide-coated iron powder (A) having iron oxide on the iron surface, wherein the amount of the metal halide contained in the aqueous solution of the metal halide is 0.01 to 1.0 parts by mass with respect to 100 parts by mass of the iron powder (a). By performing step 1, it is possible to obtain metal halide-coated iron powder (A) in which the proportion of iron element in the iron powder from which the metal halide and moisture have been removed from the metal halide-coated iron powder (A) is 97.0 to 99.3% by mass.

[0034] In this step, first, iron powder (a) which is reduced iron powder and an aqueous solution of a metal halide are mixed in an oxygen-containing gas atmosphere.

[0035] (Iron Powder (a)) Iron powder (a) is the iron powder that serves as the raw material for the metal halide-coated iron powder (A), and it is preferably the iron powder described in the description of the raw material iron powder. Specifically, it is the iron powder shown below. Iron powder (a) is preferably reduced iron powder. It is considered that reduced iron powder has fine irregularities on its surface, and thus has a high oxygen absorption suppression effect at the initial stage of oxygen absorption by the iron oxide on the surface. One kind of reduced iron powder can be used alone for iron powder (a), and two or more kinds of reduced iron powders can be used in combination as needed. Commercially available products may also be used.

[0036] The average particle size (D50) of the iron powder (a) is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 400 μm or less, even more preferably 300 μm or less, even more preferably 200 μm or less, even more preferably 100 μm or less, even more preferably 90 μm or less, and even more preferably 10 μm or more, even more preferably 30 μm or more, even more preferably 40 μm or more, even more preferably 45 μm or more, even more preferably 50 μm or more, even more preferably 55 μm or more, and even more preferably 60 μm or more. More specifically, the average particle size (D50) of the iron powder (a) is preferably 1 to 3000 μm, more preferably 10 to 1000 μm, even more preferably 30 to 500 μm, even more preferably 40 to 400 μm, even more preferably 45 to 300 μm, even more preferably 50 to 200 μm, even more preferably 55 to 100 μm, and even more preferably 60 to 90 μm. The average particle size can be measured as the average particle size (D50) at a cumulative frequency of 50% in the volume-based particle size distribution obtained by the laser diffraction / scattering particle size distribution measurement method. The average particle size can be measured using a commercially available laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by Horiba, Ltd.), etc.

[0037] Furthermore, the specific surface area of ​​the iron powder (a) is preferably 0.03 m² from the viewpoint of oxygen absorption performance. ２ / g or more, more preferably 0.06m ２ It is 1 / g or more, and more preferably 0.07m ２ It is 1 / g or more, and from the viewpoint of suppressing dust generation, preferably 0.20 m ２ / g or less, more preferably 0.12m ２ / g or less, more preferably 0.10m ２ It is less than or equal to / g. More specifically, the specific surface area of ​​the iron powder (a) is preferably 0.03 to 0.20 m². ２ / g, more preferably 0.06 to 0.12 m ２The value is / g, and more preferably 0.07 to 0.10 m ２ The value is / g. The specific surface area of ​​iron powder (a) can be measured using the BET multipoint method.

[0038] The proportion of iron element in iron powder (a) is preferably 97.1% by mass or more, and since it is necessary to control the iron element concentration of the iron powder by oxidation, high purity is preferable. The proportion of iron element in iron powder (a) is more preferably 97.5% by mass or more, even more preferably 98.0% by mass or more, even more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, and even more preferably 99.9% by mass or more.

[0039] (Aqueous solution of metal halide) The metal halide contained in the aqueous solution of metal halide can be any generally known metal without particular limitations. The metal in the metal halide is not particularly limited, but can be one or more selected from the group consisting of alkali metals, alkaline earth metals, copper, zinc, aluminum, tin, iron, cobalt, and nickel. Among these, one or more selected from the group consisting of alkali metals, alkaline earth metals, and iron is preferred, one or more selected from the group consisting of lithium, potassium, sodium, magnesium, calcium, barium, and iron is more preferred, one or more selected from the group consisting of sodium and calcium is even more preferred, and calcium is even more preferred. The halide in the metal halide is not particularly limited, but can be chloride, bromide, and iodide, preferably one or more selected from the group consisting of chloride and bromide, and more preferably chloride.

[0040] From the standpoint of handling and safety, the metal halide is preferably at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, sodium bromide, calcium iodide, and sodium iodide; more preferably at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, and sodium bromide; even more preferably at least one selected from the group consisting of calcium chloride, calcium bromide, and sodium bromide; and most preferably calcium chloride. One type of metal halide can be used alone, or two or more types can be used in combination as needed. Furthermore, these metal halides may be in anhydrous or hydrated form, and readily available commercial products may be used.

[0041] The amount of metal halide used is preferably 0.01 to 1.0 parts by mass per 100 parts by mass of iron powder (a). From the viewpoint of high oxygen absorption performance and suppression of initial oxygen absorption, the amount of metal halide used is preferably 0.02 to 0.90 parts by mass, more preferably 0.03 to 0.80 parts by mass, even more preferably 0.05 to 0.60 parts by mass, even more preferably 0.06 to 0.50 parts by mass, even more preferably 0.07 to 0.40 parts by mass, even more preferably 0.08 to 0.20 parts by mass, and even more preferably 0.09 to 0.15 parts by mass per 100 parts by mass of iron powder (a). Note that the amount of metal halide used in this invention is the amount of metal halide used only. In other words, when a hydrate is used as the metal halide in an aqueous solution of metal halide, the amount of metal halide used is the amount obtained by subtracting the water of hydration from the hydrate of the metal halide.

[0042] The amount of water contained in the aqueous solution of the metal halide is preferably 7 to 25 parts by mass, more preferably 8 to 20 parts by mass, even more preferably 9 to 16 parts by mass, and even more preferably 10 to 15 parts by mass, per 100 parts by mass of iron powder (a). When the amount of water contained in the aqueous solution of the metal halide is within the above range, the proportion of iron elements in the iron powder can be adjusted to the range of 97.0 to 99.3% by mass, and a balance can be achieved between the initial oxygen absorption rate and the oxygen absorption performance.

[0043] The concentration of the aqueous solution of the metal halide is preferably 0.08 to 10% by mass, more preferably 0.1 to 8% by mass, even more preferably 0.2 to 6% by mass, and even more preferably 0.4 to 2% by mass. The concentration of the aqueous solution of the metal halide is the mass ratio of the metal halide to the total amount (mass) of the aqueous solution. When the concentration of the aqueous solution of the metal halide is within the above range, the proportion of iron elements in the iron powder can be adjusted to the range of 97.0 to 99.3% by mass, and a balance can be achieved between the initial oxygen absorption rate and the oxygen absorption performance.

[0044] (Mixing) In this process, mixing is carried out under an oxygen-containing gas atmosphere. The oxygen-containing gas is preferably oxygen or a mixture of nitrogen and oxygen, and more preferably a mixture of nitrogen and oxygen. As the mixture of nitrogen and oxygen, air is even more preferable. Using air is simple. Furthermore, by using air, the proportion of iron elements in the iron powder can be adjusted to a range of 97.0 to 99.3 mass%, and a balance can be struck between the initial oxygen absorption rate and the oxygen absorption performance.

[0045] (Drying) Next, the mixture is dried to obtain metal halide coated iron powder (A) having iron oxide on the iron surface. Drying may be performed by heating after the above mixing is completed, but it is preferable to perform it simultaneously with the mixing. In other words, it is preferable to dry the mixture by gradually evaporating the water in the aqueous solution by mixing the aqueous solution and iron powder (a) at a temperature higher than room temperature. Since an oxidation reaction occurs on the iron surface during mixing, drying may be performed by the self-heating that occurs at that time, or to dry it quickly, heat may be applied from the outside and heated. Among these, drying by self-heating is preferable because it is possible to adjust the proportion of iron elements in the iron powder to a range of 97.0 to 99.3 mass%, and it is possible to balance the initial oxygen absorption rate and oxygen absorption performance. That is, in step 1, it is preferable to dry the mixture by the self-heating that occurs when the iron powder (a) is mixed with the aqueous solution of the metal halide.

[0046] <Step 2: Step of mixing metal halide-coated iron powder (A) and moisture donor (B)> The manufacturing method of the present invention includes, following Step 1, Step 2 of mixing the metal halide-coated iron powder (A) obtained in Step 1 with the moisture donor (B). The moisture donor (B) is the moisture donor (B) described above. A detailed description follows below.

[0047] (Moisture Donor (B)) The moisture donor (B) used in this process is preferably a carrier impregnated with water (hydrated carrier). The moisture donor (B) supplies water to the iron powder.

[0048] The carrier can be any material capable of supplying the supported moisture to the metal halide-coated iron powder (A), and granular materials are generally preferred. Preferably, the carrier is at least one selected from the group consisting of zeolite, diatomaceous earth, silica gel, perlite, vermiculite, activated alumina, activated clay, granular activated carbon, and bentonite, and more preferably at least one selected from the group consisting of zeolite, diatomaceous earth, and granular activated carbon. As stated above, in this specification, granular activated carbon refers to activated carbon with an average particle diameter (D50 diameter measured by a laser diffraction / scattering particle size distribution analyzer) of 150 to 1000 μm.

[0049] The amount of water contained in the moisture donor (B) is preferably 15 to 60 parts by mass, more preferably 20 to 60 parts by mass, even more preferably 30 to 60 parts by mass, even more preferably 40 to 60 parts by mass, and even more preferably 40 to 55 parts by mass, per 100 parts by mass of iron powder obtained by removing the metal halide from the metal halide coated iron powder (A). When the amount of water contained in the moisture donor (B) is within the above range, an appropriate amount of moisture can be supplied to the metal halide coated iron powder (A), and a balance can be achieved between the initial oxygen absorption rate and the oxygen absorption performance.

[0050] The water donor (B) preferably contains sodium chloride. By including sodium chloride in the water donor (B), the water activity can be adjusted, and a balance can be struck between the initial oxygen absorption rate and the oxygen absorption performance.

[0051] The amount of sodium chloride contained in the water donor (B) is preferably 3 to 45 parts by mass, more preferably 4 to 40 parts by mass, even more preferably 15 to 37 parts by mass, even more preferably 25 to 37 parts by mass, and even more preferably 30 to 37 parts by mass, based on 100 parts by mass of water contained in the water donor (B). When the amount of sodium chloride contained in the water donor (B) is within the above range, the water activity can be adjusted, and a balance can be achieved between the initial oxygen absorption rate and the oxygen absorption performance.

[0052] (Mixing) In this step, the metal halide-coated iron powder (A) obtained in step 1 and the moisture donor (B) are mixed. There are no particular restrictions on the mixing method. When manufacturing the oxygen absorber packaging described later, the metal halide-coated iron powder (A) and the moisture donor (B) may be mixed by placing them in a breathable packaging container, or they may be mixed in a mixing container and then placed in a breathable packaging container, or the metal halide-coated iron powder (A) and the moisture donor (B) may be mixed in a mixing container and then directly placed in the product. Among these methods, it is preferable to mix the metal halide-coated iron powder (A) and the moisture donor (B) by placing them in a breathable packaging container, or to mix them in a mixing container and then place them in a breathable packaging container.

[0053] [Oxygen Absorber Packaging] The oxygen absorber packaging of the present invention is an oxygen absorber packaging comprising the oxygen absorber composition and a breathable packaging container containing the oxygen absorber composition. Specifically, the oxygen absorber packaging of the present invention comprises an oxygen absorber composition containing metal halide-coated iron powder (A), which is obtained by coating reduced iron powder having iron oxide on the iron surface with a metal halide, and a moisture donor (B), wherein the proportion of iron elements in the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A) is 97.0 to 99.3% by mass, and the content of the metal halide is 0.01 to 1.0 parts by mass per 100 parts by mass of the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A), and a breathable packaging container containing the oxygen absorber composition.

[0054] (Permeable Packaging Containers) Permeable packaging containers are not particularly limited as long as they are made of packaging materials used for oxygen absorbers. However, from the viewpoint of ensuring that the oxygen absorber packaging exhibits sufficient oxygen absorption performance, they must include at least a permeable packaging material. Examples include containers made by bonding two permeable packaging materials together to form a bag, containers made by bonding one permeable packaging material and one non-permeable packaging material together to form a bag, and containers made by folding one permeable packaging material and sealing the edges together except for the folded part. Other examples include containers in which permeable packaging material is attached to the opening surface of a non-permeable rigid container.

[0055] Here, if the breathable and non-breathable packaging materials are rectangular in shape, the breathable packaging container may be made by overlapping two breathable packaging materials and heat-sealing all four sides to form a bag, or by overlapping one breathable packaging material and one non-breathable packaging material and heat-sealing all four sides to form a bag, or by folding one breathable packaging material and heat-sealing the three sides excluding the folded part to form a bag. The packaging material may also be made by forming the breathable packaging material into a tube and heat-sealing both ends and the body of the tube to form a bag.

[0056] (Permeable Packaging Materials) As permeable packaging materials, packaging materials that allow oxygen and water vapor to pass through are selected. Among these, those with an air permeability resistance of 600 seconds or less, more preferably 90 seconds or less, as measured by the Gahl-type testing machine, are preferably used. Here, air permeability resistance refers to the value measured by the method of JIS P8117 (1998). More specifically, it refers to the time required for 100 mL of air to pass through the permeable packaging material using a Gahl-type densometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.).

[0057] As for the breathable packaging materials mentioned above, in addition to paper and nonwoven fabrics, breathable plastic films can be used. As for the plastic films, for example, laminated films can be used, which are made by laminating and bonding films such as polyethylene terephthalate, polyamide, polypropylene, and polycarbonate with films such as polyethylene, ionomer, polybutadiene, ethylene acrylic acid copolymer, ethylene methacrylic acid copolymer, or ethylene vinyl acetate copolymer as a sealing layer. These laminates can also be used as breathable packaging materials.

[0058] Various methods can be used to impart breathability, including perforation with cold or hot needles. When imparting breathability through perforation, the degree of breathability can be freely adjusted by the diameter, number, and material of the holes to be perforated.

[0059] Furthermore, the thickness of the laminated film is preferably 50 to 300 μm, and particularly preferably 60 to 250 μm. In this case, compared to cases where the thickness falls outside the above range, a packaging material can be made that maintains strength and has excellent heat sealability and packaging suitability.

[0060] (Non-permeable packaging materials) As non-permeable packaging materials, packaging materials used for oxygen absorber applications can be used, and packaging materials that can block moisture, alcohol, oil, and solid components from the stored items and also have sealing properties are preferred. Specifically, polyethylene terephthalate or nylon co-extruded multilayer sheets or films with an oxygen permeability of 0.05 to 20 mL / m² are preferred. ２ Examples include laminates with a curing rate of 24hr·atm (25℃, 50% RH).

[0061] [Method for Manufacturing an Oxygen Absorber Package] There are no limitations on the method for manufacturing the oxygen absorber package, but it is preferable to obtain it by the manufacturing method of the present invention described below. The manufacturing method of the present invention is a method for manufacturing an oxygen absorber package, in which the oxygen absorber composition is contained in a breathable packaging container.

[0062] As for the method of housing the oxygen absorber composition in a breathable packaging container, as described above, one method is to mix the metal halide-coated iron powder (A) and the moisture donor (B) constituting the oxygen absorber composition by placing them in a breathable packaging container to form the oxygen absorber composition in the breathable packaging container and then housing the oxygen absorber composition in the breathable packaging container. Alternatively, one method is to pre-mix the metal halide-coated iron powder (A) and the moisture donor (B), and then housing the resulting oxygen absorber composition in a breathable packaging container. From the viewpoint of producing an oxygen absorber package simply and quickly and suppressing excessive oxidation reactions, the method of mixing the metal halide-coated iron powder (A) and the moisture donor (B) constituting the oxygen absorber composition by placing them in a breathable packaging container to form the oxygen absorber composition in the breathable packaging container and then housing the oxygen absorber composition in the breathable packaging container is preferred.

[0063] [Deoxygenation Method] The deoxygenation method of the present invention is a method of deoxygenation in which the oxygen absorber composition or the oxygen absorber packaging and the object to be preserved are placed in a gas barrier container. Preferably, the deoxygenation method of the present invention is a method of deoxygenation in which the oxygen absorber packaging and the object to be preserved are placed in a gas barrier container.

[0064] The oxygen scavenger composition used in the oxygen scavenger method of the present invention specifically contains, as described above, a metal halide-coated iron powder (A) obtained by coating a reduced iron powder having iron oxide on its iron surface with a metal halide, and a moisture donor (B), wherein the proportion of iron elements in the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A) is 97.0 to 99.3% by mass, and the content of the metal halide is 0.01 to 1.0 parts by mass per 100 parts by mass of the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A). The oxygen absorber packaging used in the oxygen removal method of the present invention is specifically, as described above, an oxygen absorber packaging comprising an oxygen absorber composition containing a metal halide-coated iron powder (A) obtained by coating reduced iron powder having iron oxide on the iron surface with a metal halide, and a moisture donor (B), wherein the proportion of iron elements in the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A) is 97.0 to 99.3% by mass, and the content of the metal halide is 0.01 to 1.0 parts by mass per 100 parts by mass of the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A), and a breathable packaging container containing the oxygen absorber composition.

[0065] (Gas Barrier Containers) Gas barrier containers are not particularly limited as long as they are airtight and substantially gas barrier properties, and can be appropriately selected based on the properties of the stored items, their use, and their price. If the stored items are to be consumed in a short period of time, a container with relatively poor gas barrier properties may suffice, but if the stored items require long-term storage or are sensitive to oxygen, a container with high gas barrier properties is required. From the viewpoint of blocking external ventilation, gas barrier containers are preferably made of the above-mentioned non-permeable material. Specifically, this includes multilayer sheets and films having a laminated structure such as polyethylene terephthalate or nylon co-extruded multilayer sheets or films, polyethylene terephthalate / aluminum vapor deposition / polyethylene, stretched polypropylene / polyvinyl alcohol / polyethylene, polyvinylidene chloride coated stretched nylon / polyethylene, etc., with an oxygen permeability of 0.05 to 20 mL / m². ２Bags and packaging containers made of a 24hr·atm (25℃, 50% RH) laminate can be easily used. In addition to the above, metal cans, glass bottles, plastic containers, etc. can also be used as gas barrier containers.

[0066] The preserved items are preferably those whose quality can be prevented from deteriorating by avoiding contact with oxygen, and the preserved items are preferably food products, industrial products, or pharmaceuticals.

[0067] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and includes all aspects included in the concept and claims of the present invention, and can be modified in various ways within the scope of the present invention.

[0068] The embodiment will be described in detail below using examples and comparative examples, but this embodiment can be modified as appropriate insofar as it achieves the effects and advantages of the present invention. In the examples and comparative examples, "parts" means parts by mass unless otherwise specified. Furthermore, various measurements and evaluations in the examples and comparative examples were carried out as follows.

[0069] <Percentage of iron element in iron powder> The percentage of iron element in iron powder obtained by removing the halide metal and water from the halide metal coated iron powder (A) was determined by the following formula, using the amount of raw iron powder used in the production of the halide metal coated iron powder, the amount of halide metal, the mass of the product after the coating process, and the mass of water in the halide metal coated iron powder (A): [Percentage of iron element (mass %)] = 100 × [Amount of raw iron powder] × [Purity of raw iron powder] / ([Mass of product after coating process (halide metal coated iron powder (A))] - [Amount of halide metal] - [Mass of water in halide metal coated iron powder (A)]) The mass of water in halide metal coated iron powder (A) was measured using 0.3 g of halide metal coated iron powder (A) with a heated vaporization Karl Fischer moisture meter (Kyoto Electronics Manufacturing Co., Ltd., MKC-610). Furthermore, the purity of the raw material, reduced iron powder (percentage of iron elements, quantified using a calibration curve method with an inductively coupled plasma (ICP) emission spectrometer) was 99.9%. Similarly, the purity of the raw material, atomized iron powder (percentage of iron elements, quantified using a calibration curve method with an inductively coupled plasma (ICP) emission spectrometer) was also 99.9%.

[0070] <Oxygen Absorption of Oxygen Absorber Composition> A sampling rubber sheet (25 mm x 25 mm, 2 mm thick) was attached to one side of an aluminum bag (aluminum foil laminated plastic film bag, 350 mm x 400 mm) to obtain a measuring aluminum bag. Next, the oxygen absorber packaging obtained in the examples and comparative examples (containing an oxygen absorber composition containing 1.00 g of metal halide coated iron powder) and 3000 mL of air were placed in the measuring aluminum bag, and the opening was heat-sealed. Then, the aluminum bag was quickly placed in a constant temperature bath at 25°C. The oxygen concentration inside the aluminum bag was measured 2 hours and 48 hours after sealing, and the amount of oxygen absorbed was calculated. Table 1 shows the amount of oxygen absorbed per 1 g of metal halide coated iron powder (indicated as the amount of oxygen absorbed per 1 g of iron powder) (mL). The oxygen concentration was measured using an oxygen analyzer (ISM-3, manufactured by MOCON), with the measuring needle inserted from the rubber sheet into the aluminum bag for 48 hours of automatic measurement. A lower oxygen absorption rate after 2 hours is preferable because it suppresses initial oxygen absorption and makes handling in the atmosphere easier. Specifically, an absorption rate of 35 mL or less per gram of metal halide-coated iron powder is more preferable because it suppresses initial oxygen absorption and makes handling in the atmosphere easier. Furthermore, a higher oxygen absorption rate after 48 hours is preferable because it allows for sufficient oxygen absorption performance. Specifically, an absorption rate of 250 mL or more is more preferable because it allows for sufficient oxygen absorption performance.

[0071] [Production of oxygen absorber composition and oxygen absorber packaging] Example 1 (1) Dissolve 0.135 g of calcium chloride dihydrate (0.102 g of calcium chloride) in 10.49 g of water, and this aqueous solution is mixed with reduced iron powder (manufactured by Höganäs, average particle size 80 μm (D50 diameter measured by laser diffraction / scattering particle size distribution analyzer), specific surface area 0.090 m²) ２(1) 100 g of (1 / g) was mixed with an air atmosphere (oxygen concentration 21 vol%) and stirred with a spatula in an air atmosphere, and the iron powder was gradually heated to about 120°C and dried. This yielded metal halide coated iron powder. The proportion of iron element in the iron powder after removing calcium chloride and water from the metal halide coated iron powder was 98.5 mass%. (2) Next, 17.5 g of sodium chloride was dissolved in 51.5 g of water and impregnated into 75 g of granular diatomaceous earth (manufactured by Showa Chemical Industry Co., Ltd., average particle size 1000 μm (D50 diameter measured by laser diffraction / scattering particle size distribution analyzer)) to prepare a water donor. The water activity of the obtained water donor was 75% RH. 0.5 g of powdered activated carbon (manufactured by Osaka Gas Chemical Co., Ltd.: Shirasagi A, average particle size 10 μm (D50 diameter measured by laser diffraction / scattering particle size distribution analyzer)) was mixed with the moisture donor to obtain a mixture containing the moisture donor and powdered activated carbon. (3) 1.00 g of the metal halide coated iron powder obtained in (1) and 1.35 g of the mixture containing the moisture donor and powdered activated carbon obtained in (2) were filled into a 40 mm x 40 mm bag (breathable packaging container) made of breathable laminated film (composition: polyethylene nonwoven fabric (manufactured by Unitika Ltd., "Elves") / oil-resistant synthetic paper (manufactured by Awa Paper Co., Ltd., "Alto")) and mixed to obtain an oxygen absorber composition. Furthermore, it was sealed to obtain an oxygen absorber package. The evaluation results are shown in Table 1.

[0072] Examples 3-4 and Comparative Examples 1-2: Except for changing the amount of calcium chloride dihydrate (calcium chloride) and the amount of water used to dissolve the calcium chloride to the amounts shown in Table 1, oxygen absorber compositions and oxygen absorber packaging were obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0073] In Example 2, the amount of calcium chloride dihydrate (calcium chloride) and the amount of water used to dissolve the calcium chloride were changed to the amounts shown in Table 1. The calcium chloride aqueous solution was mixed with reduced iron powder and dried while being heated on a hot plate. Except for these changes, the oxygen absorber composition and oxygen absorber packaging were obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0074] Comparative Example 3: The amount of calcium chloride dihydrate (calcium chloride) and the amount of water used to dissolve the calcium chloride were changed to the amounts shown in Table 1, and the raw material iron powder was changed to atomized iron powder (manufactured by Kobe Steel, Ltd., average particle size 100 μm (D50 diameter measured by laser diffraction / scattering particle size distribution analyzer), specific surface area 0.052 m²). ２ Except for changing the amount per g, an oxygen absorber composition and an oxygen absorber packaging were obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0075]

[0076] As shown in Table 1, the oxygen absorber composition of the example showed low oxygen absorption up to 2 hours after sealing the product, indicating that initial oxygen absorption was suppressed. Furthermore, the oxygen absorption after 48 hours was high, demonstrating sufficient oxygen absorption performance. Therefore, the oxygen absorber composition of the present invention is useful as an oxygen absorber that can be used in a wide range of products such as food, industrial products, and pharmaceuticals, as it is easy to handle in the atmosphere while exhibiting sufficient oxygen absorption performance.

Claims

1. An oxygen scavenger composition comprising metal halide-coated iron powder (A), which is obtained by coating reduced iron powder having iron oxide on its iron surface with a metal halide, and a moisture donor (B), wherein the proportion of iron element in the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A) is 97.0 to 99.3% by mass, and the content of the metal halide is 0.01 to 1.0 parts by mass per 100 parts by mass of the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A).

2. The oxygen scavenger composition according to claim 1, wherein the average particle size of the metal halide-coated iron powder (A) is 30 to 500 μm.

3. The oxygen scavenger composition according to claim 1 or 2, wherein the metal halide is at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, and sodium bromide.

4. The specific surface area of ​​the reduced iron powder is 0.06 to 0.12 m². ２ The oxygen absorber composition according to any one of claims 1 to 3, wherein the concentration is / g.

5. The oxygen scavenger composition according to any one of claims 1 to 4, wherein the water donor (B) is a carrier impregnated with water.

6. The oxygen scavenger composition according to any one of claims 1 to 5, wherein the moisture donor (B) contains sodium chloride.

7. The oxygen scavenger composition according to claim 5 or 6, wherein the amount of water contained in the water donor (B) is 15 to 60 parts by mass per 100 parts by mass of iron powder obtained by removing the metal halide and water from the metal halide coated iron powder (A).

8. The oxygen absorber composition according to any one of claims 5 to 7, wherein the carrier is at least one selected from the group consisting of zeolite, diatomaceous earth, silica gel, perlite, vermiculite, activated alumina, activated clay, granular activated carbon, and bentonite.

9. A method for producing an oxygen scavenger composition, comprising: step 1 of mixing iron powder (a), which is reduced iron powder, and an aqueous solution of a metal halide in an oxygen-containing gas atmosphere and drying to obtain metal halide-coated iron powder (A) having iron oxide on the iron surface; and step 2 of mixing the metal halide-coated iron powder (A) and a water donor (B), wherein the amount of metal halide contained in the aqueous solution of the metal halide is 0.01 to 1.0 parts by mass per 100 parts by mass of iron powder (a), and the proportion of iron element in the iron powder after removing the metal halide and water from the metal halide-coated iron powder (A) is 97.0 to 99.3% by mass.

10. The method for producing the oxygen scavenger composition according to claim 9, wherein the amount of water contained in the aqueous solution of the metal halide is 7 to 25 parts by mass per 100 parts by mass of iron powder (a).

11. A method for producing the oxygen scavenger composition according to claim 9 or 10, wherein the concentration of the aqueous solution of the metal halide is 0.08 to 10% by mass.

12. A method for producing an oxygen absorber composition according to any one of claims 9 to 11, wherein in step 1, drying is performed by self-heating during mixing.

13. A method for producing an oxygen absorber composition according to any one of claims 9 to 12, wherein the average particle size of the iron powder (a) is 30 to 500 μm.

14. A method for producing an oxygen scavenger composition according to any one of claims 9 to 13, wherein the metal halide is at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, and sodium bromide.

15. A method for producing an oxygen scavenger composition according to any one of claims 9 to 14, wherein the water donor (B) is a carrier impregnated with water.

16. A method for producing an oxygen scavenger composition according to any one of claims 9 to 15, wherein the moisture donor (B) contains sodium chloride.

17. A method for producing an oxygen scavenger composition according to claim 15 or 16, wherein the amount of water contained in the water donor (B) is 15 to 60 parts by mass per 100 parts by mass of iron powder obtained by removing the metal halide and water from the metal halide coated iron powder (A).

18. A method for producing an oxygen absorber composition according to any one of claims 15 to 17, wherein the carrier is at least one selected from the group consisting of zeolite, diatomaceous earth, silica gel, perlite, vermiculite, activated alumina, activated clay, granular activated carbon, and bentonite.

19. An oxygen absorber package comprising an oxygen absorber composition according to any one of claims 1 to 8 and a breathable packaging container containing the oxygen absorber composition.

20. A method for producing an oxygen absorber package, comprising containing the oxygen absorber composition according to any one of claims 1 to 8 in a breathable packaging container.

21. A method for deoxygenating an object, comprising placing the deoxygenating agent composition according to any one of claims 1 to 8 or the deoxygenating agent packaging according to claim 19, and the object to be preserved into a gas barrier container.

22. The deoxygenation method according to claim 21, wherein the object to be preserved is food, industrial product, or pharmaceutical.

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