Oxygen scavenger composition

Abstract

This oxygen scavenger composition contains (A) a metal halide-coated iron powder having iron oxide at the iron surface and (B) a moisture donor. The proportion of the element iron in the iron powder provided by removing the metal halide and moisture from the metal halide-coated iron powder (A) is 90.0-96.3 mass%. Also provided are a method for producing the oxygen scavenger composition, an oxygen scavenger package, and a deoxygenation method.

Description

Oxygen scavenger composition

[0001] The present invention relates to an oxygen scavenger composition.

[0002] A method using an oxygen absorber is known as a preservation technique for foods, pharmaceuticals, etc. In this method, the preserved item and the oxygen absorber are enclosed in a gas-barrier sealed container and then sealed, so that the oxygen in the sealed container is absorbed by the oxygen absorber, thereby maintaining the atmosphere in the sealed container substantially oxygen-free. The function of the oxygen absorber is required to be small and to absorb a large amount of oxygen. In other words, an oxygen absorber composition that has a high oxygen absorption amount per unit volume is required.

[0003] Typical oxygen absorbers include iron-based oxygen absorbers, which are primarily made of iron (iron powder), and non-iron-based oxygen absorbers, which are primarily made of ascorbic acid, glycerin, etc. Oxygen absorbers are selected appropriately depending on the application, but iron-based oxygen absorbers are widely used from the perspective of oxygen absorption performance. Iron-based oxygen absorbers are classified into two types: those that use water vapor in the oxygen-removing environment (such as evaporation from food) (moisture-dependent type), and those that contain 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 encapsulate a moisture-donating agent.

[0004] Metal halides and the like are used as oxidation promoters for efficiently donating moisture from a moisture donor to the iron surface. For example, Patent Document 1 discloses an oxygen absorber that is compact, inexpensive, and yet has high oxygen absorption capacity, and is characterized by comprising iron powder, an oxidation promoter, a filler, and a moisture donor obtained by incorporating moisture into diatomaceous earth that has adsorption properties that show a relative humidity of 55% or more when it contains 2% moisture.

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

[0006] As described above, moisture-dependent oxygen absorbers can only exhibit their oxygen scavenging performance in environments where moisture can be supplied from the outside, limiting their applications. Self-reacting oxygen absorbers have the advantage of being able to absorb oxygen even in relatively low external humidity conditions, but they react immediately upon contact with oxygen, and the reaction progresses during the process of packaging in a product, resulting in a decrease in oxygen scavenging performance. On the other hand, if a self-reacting oxygen absorber is manufactured without incorporating an oxidation promoter, the initial oxidation reaction can be suppressed, but the oxygen absorbing performance after packaging in a product will also be poor, resulting in an insufficient performance as an oxygen absorber. The present invention has been made in light of these circumstances, and an object of the present invention is to provide a self-reacting oxygen scavenger composition that suppresses initial oxygen absorption and can exhibit sufficient oxygen absorbing performance even after handling in the atmosphere for a certain period of time.

[0007] The present inventors have discovered that the above-mentioned problems can be solved by an oxygen scavenger composition containing a metal halide-coated iron powder having iron oxide on the specific iron surface and a moisture donor, and have completed the present invention.

[0008] That is, the present invention relates to the following [1] to

[22] . [1] An oxygen scavenger composition containing a metal halide-coated iron powder (A) having an iron oxide on the iron surface 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 90.0 to 96.3 mass%. [2] The oxygen scavenger composition according to [1] above, wherein the metal halide-coated iron powder (A) has an average particle size of 30 to 500 μm. [3] The oxygen scavenger composition according to [1] above, 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 oxygen absorbing composition according to any one of [1] to [3] above, wherein the content of the metal halide in the halide-coated iron powder (A) is 0.10 parts by mass or more and 1.00 parts by mass or less per 100 parts by mass of iron powder obtained by excluding the metal halide and water from the halide-coated iron powder (A). [5] The oxygen absorbing composition according to any one of [1] to [4] above, wherein the moisture donating agent (B) is a carrier impregnated with water. [6] The oxygen absorbing composition according to any one of [1] to [5] above, wherein the moisture donating agent (B) contains sodium chloride. [7] The oxygen absorbing composition according to [5] or [6] above, wherein the amount of water contained in the moisture donating agent (B) is 15 to 60 parts by mass per 100 parts by mass of iron powder obtained by excluding the metal halide and water from the halide-coated iron powder (A). [8] The oxygen scavenger composition according to any one of [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, activated carbon, and bentonite. [9] A method for producing an oxygen scavenger composition, comprising: Step 1 of mixing iron powder (a) and an aqueous solution of a metal halide under an oxygen-containing gas atmosphere and drying the mixture to obtain a 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) with a moisture donor (B), wherein the amount of the metal halide contained in the aqueous solution of the metal halide is 0.10 parts by mass or more and 1.00 parts by mass or less per 100 parts by mass of the iron powder (a).

[10] A method for producing an oxygen absorbing composition according to [9] above, wherein the amount of water contained in the aqueous solution of metal halide is 10 to 20 parts by mass per 100 parts by mass of iron powder (a).

[11] A method for producing an oxygen absorbing composition according to [9] or

[10] above, wherein the concentration of the aqueous solution of metal halide is 0.1 to 10 mass%.

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

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

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

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

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

[13] above, 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 absorbing composition according to any one of [9] to

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

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

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

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

[15] or

[16] 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 and water from the metal halide-coated iron powder (A).

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

[15] to

[17] 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, activated carbon, and bentonite.

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

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

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

[22] The method for absorbing oxygen 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 absorbing composition that suppresses initial oxygen absorption and that can exhibit sufficient oxygen absorbing performance 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 a metal halide-coated iron powder (A) having iron oxide on the iron surface and a moisture donor (B), and is an oxygen absorber composition in which 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 90.0 to 96.3 mass %.

[0011] The reason why the oxygen absorber composition of the present invention suppresses initial oxygen absorption and exhibits sufficient oxygen absorption performance even after handling in the atmosphere for a certain period of time is unclear, 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 moisture donor increases the humidity in the atmosphere. This causes the metal halide coating the iron powder to deliquesce, and moisture adheres to the iron powder surface. The presence of iron oxide on the iron powder surface increases the specific surface area, resulting in high dispersion of the metal halide and a high dispersion of the moisture adhered to the iron powder surface. When exposed to air in this state, the moisture adhered to the iron powder surface immediately disappears by evaporation. For the iron powder to be oxidized again, the metal halide must deliquesce again. However, the time required for this second deliquescence suppresses initial oxygen absorption, and the loss of effectiveness due to oxygen absorption is thought to be reduced even when handled in the atmosphere. Therefore, oxygen absorption performance is preserved, and sufficient oxygen absorption performance can be exhibited even after handling in the atmosphere. Furthermore, the presence of iron oxide on the iron powder surface forms an oxide film, further suppressing initial oxygen absorption.

[0012] <Halide Metal-Coated Iron Powder (A)> The halide metal-coated iron powder (A) contained in the oxygen absorber composition of the present invention has iron oxide on the iron surface. The iron powder (A) contains 90.0 to 96.3 mass% of iron element, excluding the metal halide and moisture. The halide metal-coated iron powder (A) typically also contains absorbed moisture on the iron surface. The moisture present on the surface may be the residue of moisture evaporated from the raw materials used in the production of the halide metal-coated iron powder, or may be absorbed by moisture absorption from the atmosphere or moisture-donating agents after production. When moisture is present on the iron surface, the amount of moisture present on the iron surface is subtracted from the calculated iron element content. The moisture content is measured using a moisture meter. Specifically, the moisture content can be measured using a thermal vaporization Karl Fischer moisture meter (MKC-610, manufactured by Kyoto Electronics Manufacturing Co., Ltd.) or the like.

[0013] The average particle size (D50) of the halide metal-coated iron powder (A) is preferably 3,000 μm or less, more preferably 1,000 μm or less, even more preferably 500 μm or less, and even more preferably 200 μm or less from the viewpoint of improving contact with oxygen, and is preferably 1 μm or more, more preferably 10 μm or more, even more preferably 30 μm or more, and even more preferably 40 μm or more from the viewpoint of suppressing dust generation. More specifically, the average particle size (D50) of the halide metal-coated iron powder (A) is preferably 1 to 3,000 μm, more preferably 10 to 1,000 μm, even more preferably 30 to 500 μm, and even more preferably 40 to 200 μm. The average particle size can be measured as the average particle size (D50) at a cumulative frequency of 50% in a volume-based particle size distribution using a commercially available laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by Horiba, Ltd.) or the like.

[0014] (Iron Powder) In this section, "iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A)" will be referred to simply as "iron powder" below. That is, "iron powder" in this section refers to "iron powder obtained by removing the metal halide from the metal halide-coated iron powder (A) and further removing the moisture present on the surface." Furthermore, "iron powder obtained by removing the metal halide from the metal halide-coated iron powder (A) and further removing the moisture present on the surface" is distinguished from the "raw iron powder" described below. The iron powder has iron oxide on the iron surface, and the iron content in the iron powder is 90.0 to 96.3 mass%. Examples of components other than iron include oxygen and hydrogen, with oxygen being the main component. That is, it is preferable that the iron powder used in the oxygen scavenger composition of the present invention has iron oxide on the surface, resulting in a low iron content, and that the iron content in the interior of the iron powder is high. The iron content of the iron powder is 90.0 to 96.3 mass%, preferably 92.0 to 96.3 mass%, more preferably 93.0 to 96.3 mass%, even more preferably 93.0 to 96.0 mass%, even more preferably 93.0 to 95.8 mass%, and even more preferably 93.0 to 95.0 mass%. When the iron content of the iron powder is within the above range, initial oxygen absorption is suppressed, making it easier to handle in the atmosphere. The iron content of the iron powder is determined by a calibration curve method using an inductively coupled plasma (ICP) optical emission analyzer. More specifically, the iron content of the iron powder can be determined by the method described in the Examples.

[0015] The iron powder (iron powder obtained by removing the metal halide and water from the metal halide-coated iron powder (A)) can be produced by oxidizing a raw iron powder. The raw iron powder may be reduced iron powder, electrolytic iron powder, atomized iron powder, or the like. Alternatively, pulverized or cut cast iron or the like may also be used. Among these, the raw iron powder is preferably at least one selected from the group consisting of reduced iron powder, electrolytic iron powder, and atomized iron powder, and more preferably atomized iron powder. The term "raw iron powder" refers to the iron powder used to produce the metal halide-coated iron powder (A), and refers to the iron powder before adjusting the amount of iron oxide on the surface and before coating with a metal halide. The term "raw iron powder" also includes "iron powder (a)" in the method for producing an oxygen scavenger composition described below. The raw iron powder may be used singly or in combination of two or more types as needed. Commercially available products may also be used.

[0016] The average particle size (D50) of the iron powder is preferably 3000 μm or less, more preferably 1000 μm or less, even more preferably 500 μm or less, and even more preferably 200 μm or less from the viewpoint of improving contact with oxygen, and is preferably 1 μm or more, more preferably 10 μm or more, even more preferably 30 μm or more, and even more preferably 40 μm or more from the viewpoint of suppressing dust generation. More specifically, the average particle size (D50) of the iron powder is preferably 1 to 3000 μm, more preferably 10 to 1000 μm, even more preferably 30 to 500 μm, and even more preferably 40 to 200 μm. The average particle size (D50) of the raw iron powder is preferably 3000 μm or less, more preferably 1000 μm or less, even more preferably 500 μm or less, and even more preferably 200 μm or less, from the viewpoint of improving contact with oxygen. Furthermore, from the viewpoint of suppressing dust generation, it is preferably 1 μm or more, more preferably 10 μm or more, even more preferably 30 μm or more, and even more preferably 40 μm or more. More specifically, the average particle size (D50) of the iron powder is preferably 1 to 3000 μm, more preferably 10 to 1000 μm, even more preferably 30 to 500 μm, and even more preferably 40 to 200 μm. The average particle size can be measured as the average particle size (D50) at 50% cumulative frequency in a volume-based particle size distribution obtained by a 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 measurement device (LA-960, manufactured by Horiba, Ltd.), or the like.

[0017] In addition, the specific surface area of ​​the raw material iron powder is preferably 0.03 m from the viewpoint of oxygen absorption performance. ２ / g or more, more preferably 0.05m ２ / g or more, and from the viewpoint of suppressing the generation of dust, it is preferably 0.20 m ２ / g or less, more preferably 0.10m ２ / g or less, more preferably 0.09m ２ More specifically, the specific surface area of ​​the raw material iron powder is preferably 0.03 m ２ / g or more 0.20m ２ / g or less, more preferably 0.03 m ２ / g or more 0.10m ２ / g or less, more preferably 0.05m ２ / g or more 0.09m ２ The specific surface area of ​​the raw material iron powder can be measured by the BET multipoint method.

[0018] The iron content of the raw material iron powder is preferably 90% by mass or more, and since it is necessary to control the iron content of the iron powder by oxidation, high purity is preferred. The iron content of the raw material pure iron powder is more preferably 95% by mass or more, even more preferably 97% by mass or more, even more preferably 99% by mass or more, and even more preferably 99.5% by mass or more.

[0019] The iron powder (iron powder obtained by removing the metal halide and water 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 combination as appropriate. Among these, the method of oxidation in the presence of an aqueous metal halide solution, which will be described later, is more preferred because it can simultaneously achieve metal halide coating and surface oxidation of the iron powder and also allows for easy control of the amount of metal halide coating and the amount of surface oxidation, i.e., the iron concentration in the iron powder.

[0020] (Metal Halide) In the metal halide-coated iron powder (A), a metal halide is present on the surface of the iron powder. The metal halide is a substance that acts catalytically on the oxidation reaction of iron and improves the activity of iron. The metal halide also plays a role in preventing water contained in the oxygen scavenger composition from evaporating and being lost from the oxygen scavenger composition. Furthermore, the presence of the metal halide on the surface of the iron powder makes it possible to attract moisture to the surface of the iron powder by utilizing the deliquescence phenomenon of the metal halide.

[0021] As the metal halide, any commonly known metal can be used without any particular limitation. The metal in the metal halide is not particularly limited, but includes at least one selected from the group consisting of alkali metals, alkaline earth metals, copper, zinc, aluminum, tin, iron, cobalt, and nickel. Among them, at least one selected from the group consisting of alkali metals, alkaline earth metals, and iron is preferred, at least one selected from the group consisting of lithium, potassium, sodium, magnesium, calcium, barium, and iron is more preferred, at least one 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 includes chloride, bromide, and iodide, preferably at least one selected from the group consisting of chloride and bromide, more preferably chloride.

[0022] From the viewpoints of ease 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 even more preferably calcium chloride. One type of metal halide can be used alone, or two or more types can be used in combination as necessary. Furthermore, these metal halides may be anhydrous or hydrated, and easily available commercially available products may be used.

[0023] The content of the metal halide in the halide-coated iron powder (A) is preferably 0.10 parts by mass or more and 1.00 parts by mass or less, based on 100 parts by mass of iron powder obtained by excluding the metal halide and moisture from the halide-coated iron powder (A). From the viewpoints of improving iron activity, suppressing evaporation of moisture in the oxygen scavenger composition, and ensuring moisture on the iron powder surface, the content of the metal halide is more preferably 0.10 parts by mass or more and 0.70 parts by mass or less, based on 100 parts by mass of iron powder obtained by excluding the metal halide and moisture from the halide-coated iron powder (A). Furthermore, from the viewpoint of suppressing initial oxygen absorption, the content of the metal halide is even more preferably 0.10 parts by mass or more and 0.50 parts by mass or less, even more preferably 0.10 parts by mass or more and 0.30 parts by mass or less, and even more preferably 0.10 parts by mass or more and 0.20 parts by mass or less. The content of the metal halide in the present invention refers to the content of only the metal halide. That is, when the metal halide in the metal halide-coated iron powder (A) is in a hydrate state, the content of the metal halide is the amount of the metal halide hydrate excluding the water of hydration.

[0024] The metal halide content can be calculated from the amount of metal halide added during production of the metal halide-coated iron powder. Furthermore, when the mass ratio in a sample is unknown, such as when total analysis of the produced metal halide-coated iron powder is not possible, the metal halide content can be quantified, for example, using the following method. Accurately weigh out 1 g of metal halide-coated iron powder. Add 50 mL of pure water to the resulting metal halide-coated iron powder, stir thoroughly, and then filter. This procedure is repeated three times, and the entire filtrate is recovered and mixed. Add 5 mL of a 400 μg / mL Co standard solution (Kanto Chemical, for chemical analysis) and pure water to a final volume of 200 mL to obtain a test solution. The above-mentioned measurement solution is measured using a multi-ICP optical emission spectrometer (SPECTRO ARCOS, manufactured by SPECTRO Analytical Instruments), and the amount of metal halide in the measurement solution, i.e., the amount of metal halide added per gram of metal halide-coated iron powder, can be determined from the metal halide / Co intensity ratio of the target and a separately prepared calibration curve.

[0025] <Moisture-donating agent (B)> The oxygen scavenger composition of the present invention contains a moisture-donating agent (B). The moisture-donating agent (B) is preferably a carrier impregnated with water (a water-containing carrier). The moisture-donating agent (B) supplies water to iron.

[0026] The carrier may be any carrier capable of supplying the supported moisture to the metal halide-coated iron powder (A), and a granular carrier is generally suitably 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, activated carbon, and bentonite, and more preferably at least one selected from the group consisting of zeolite, diatomaceous earth, and activated carbon.

[0027] 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, still 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 excluding the metal halide and water 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 provided 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.

[0028] The moisture donating agent (B) preferably contains sodium chloride. When the moisture donating agent (B) contains sodium chloride, the water activity can be adjusted, and the initial oxygen absorption rate and oxygen absorption performance can be balanced.

[0029] The amount of sodium chloride contained in the moisture 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, still more preferably 25 to 37 parts by mass, and even more preferably 30 to 37 parts by mass, relative to 100 parts by mass of water contained in the moisture donor (B). When the amount of sodium chloride contained in the moisture 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.

[0030] [Method for producing oxygen scavenger composition] The oxygen scavenger composition of the present invention may be obtained by any production method, but is preferably obtained by the production method of the present invention described below. The production method of the present invention is a method for producing an oxygen scavenger composition, comprising: Step 1 of mixing iron powder (a) and an aqueous solution of a metal halide in an oxygen-containing gas atmosphere and drying the mixture to obtain a 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) with a moisture donor (B), wherein the amount of the metal halide contained in the aqueous solution of the metal halide is 0.10 parts by mass or more and 1.00 parts by mass or less per 100 parts by mass of the iron powder (a).

[0031] <Step 1: Step of Obtaining Metal Halide-Coated Iron Powder (A)> The manufacturing method of the present invention includes Step 1 of 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, wherein the amount of metal halide contained in the aqueous solution of metal halide is 0.10 parts by mass or more and 1.00 parts by mass or less per 100 parts by mass of iron powder (a). By performing Step 1, it is possible to obtain metal halide-coated iron powder (A) having an iron content of 90.0 to 96.3 mass % in the iron powder after excluding the metal halide and water from metal halide-coated iron powder (A).

[0032] In this step, first, iron powder (a) and an aqueous solution of a metal halide are mixed in an oxygen-containing gas atmosphere.

[0033] (Iron Powder (a)) The iron powder (a) is an iron powder that is a raw material for the metal halide-coated iron powder (A), and is preferably the iron powder described in the description of the raw iron powder above. Specific examples include the following iron powders. The iron powder (a) can be reduced iron powder, electrolytic iron powder, atomized iron powder, etc., and is preferably at least one selected from the group consisting of reduced iron powder, electrolytic iron powder, and atomized iron powder, more preferably atomized iron powder. Pulverized or cut products of cast iron or the like can also be used. The iron powder (a) can be used singly or in combination of two or more types as needed. Commercially available products may also be used.

[0034] The average particle size (D50) of the iron powder (a) is preferably 3000 μm or less, more preferably 1000 μm or less, even more preferably 500 μm or less, and even more preferably 200 μm or less from the viewpoint of improving contact with oxygen, and is preferably 1 μm or more, more preferably 10 μm or more, even more preferably 30 μm or more, and even more preferably 40 μm or more from the viewpoint of suppressing dust generation. 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, and even more preferably 40 to 200 μm. The average particle size can be measured as the average particle size (D50) at a cumulative frequency of 50% in a volume-based particle size distribution using a commercially available laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by Horiba, Ltd.) or the like.

[0035] In addition, the specific surface area of ​​the iron powder (a) is preferably 0.03 m from the viewpoint of oxygen absorption performance. ２ / g or more, more preferably 0.05m ２ / g or more, and from the viewpoint of suppressing the generation of dust, it is preferably 0.20 m ２ / g or less, more preferably 0.10m ２ / g or less, more preferably 0.09m ２ More specifically, the specific surface area of ​​the iron powder (a) is preferably 0.03 m ２ / g or more 0.20m ２ / g or less, more preferably 0.03 m ２ / g or more 0.10m ２ / g or less, more preferably 0.05m ２ / g or more 0.09m ２ The specific surface area of ​​the iron powder (a) can be measured by the BET multipoint method.

[0036] (Metal Halide Aqueous Solution) The metal halide contained in the metal halide aqueous solution can be any commonly known metal halide without any particular limitation. The metal in the metal halide is not particularly limited, but may be at least one selected from the group consisting of alkali metals, alkaline earth metals, copper, zinc, aluminum, tin, iron, cobalt, and nickel. Among them, at least one selected from the group consisting of alkali metals, alkaline earth metals, and iron is preferred, at least one selected from the group consisting of lithium, potassium, sodium, magnesium, calcium, barium, and iron is more preferred, at least one 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 may be chloride, bromide, or iodide, preferably at least one selected from the group consisting of chloride and bromide, more preferably chloride.

[0037] From the viewpoints of ease 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 even more preferably calcium chloride. One type of metal halide can be used alone, or two or more types can be used in combination as necessary. Furthermore, these metal halides may be anhydrous or hydrated, and easily available commercially available products may be used.

[0038] The amount of the metal halide used is preferably 0.10 parts by mass or more and 1.00 parts by mass or less relative to 100 parts by mass of the iron powder (a). The amount of the metal halide used is preferably 0.10 parts by mass or more and 0.70 parts by mass or less, more preferably 0.10 parts by mass or more and 0.50 parts by mass or less, even more preferably 0.10 parts by mass or more and 0.30 parts by mass or less, and still more preferably 0.10 parts by mass or more and 0.20 parts by mass or less relative to 100 parts by mass of the iron powder (a). The amount of the metal halide used in the present invention is the amount of the metal halide used alone. In other words, when a hydrate is used as the metal halide used in the metal halide aqueous solution, the amount of the metal halide used is the amount of the metal halide hydrate excluding water of hydration.

[0039] The amount of water contained in the aqueous metal halide solution is preferably 10 to 20 parts by mass, more preferably 15 to 20 parts by mass, even more preferably 16 to 20 parts by mass, and still more preferably 16 to 19 parts by mass, relative to 100 parts by mass of the iron powder (a). When the amount of water contained in the aqueous metal halide solution is within the above range, the proportion of iron element in the iron powder can be adjusted to the range of 90.0 to 96.3% by mass, and a balance can be achieved between the initial oxygen absorption rate and the oxygen absorption performance.

[0040] The concentration of the metal halide aqueous solution is preferably 0.08 to 10 mass%, more preferably 0.1 to 10 mass%, even more preferably 0.1 to 4 mass%, still more preferably 0.2 to 3 mass%, and even more preferably 0.4 to 2 mass%. The concentration of the metal halide aqueous solution is the mass ratio of the metal halide to the total amount (mass) of the aqueous solution. When the concentration of the metal halide aqueous solution is within the above range, the proportion of iron element in the iron powder can be adjusted to the range of 90.0 to 96.3 mass%, and a balance can be achieved between the initial oxygen absorption rate and the oxygen absorption performance.

[0041] (Mixing) In this step, mixing is carried out in an oxygen-containing gas atmosphere. As the oxygen-containing gas, oxygen or a mixed gas of nitrogen and oxygen is preferred, and a mixed gas of nitrogen and oxygen is more preferred. As the mixed gas of nitrogen and oxygen, air is even more preferred. The use of air is simple. Furthermore, by using air, the proportion of iron element in the iron powder can be adjusted to a range of 90.0 to 96.3 mass%, and a balance can be achieved between the initial oxygen absorption rate and the oxygen absorption performance.

[0042] (Drying) Next, the mixture is dried to obtain a metal halide-coated iron powder (A) having iron oxide on the iron surface. Drying can be performed by heating after the mixing is completed, but is preferably performed simultaneously with the mixing. That is, it is preferable to mix the aqueous solution and iron powder (a) at a temperature higher than room temperature to gradually volatilize the water in the aqueous solution and dry the mixture. Since an oxidation reaction occurs on the iron surface during mixing, drying can be achieved by the self-heating that occurs during the reaction. To dry quickly, external heat can be applied to dry the mixture. Among these, drying by self-heating is preferred because it allows the proportion of iron element in the iron powder to be adjusted to a range of 90.0 to 96.3 mass%, thereby achieving a balance between the initial oxygen absorption rate and oxygen absorption performance. That is, in step 1, drying is preferably achieved by the self-heating that occurs during mixing of the iron powder (a) and the metal halide aqueous solution.

[0043] <Step 2: Step of Mixing the Halide-Coated Iron Powder (A) and the Moisture-Donating Agent (B)> The production method of the present invention includes, following Step 1, Step 2 of mixing the halide-coated iron powder (A) obtained in Step 1 with the moisture-donating agent (B). The moisture-donating agent (B) is the moisture-donating agent (B) described above. This is described in detail below.

[0044] (Moisture-donating agent (B)) The moisture-donating agent (B) used in this step is preferably a carrier impregnated with water (a water-containing carrier). The moisture-donating agent (B) supplies water to the iron powder.

[0045] The carrier may be any carrier capable of supplying the supported moisture to the metal halide-coated iron powder (A), and a granular carrier is generally suitably 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, activated carbon, and bentonite, and more preferably at least one selected from the group consisting of zeolite, diatomaceous earth, and activated carbon.

[0046] 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, still 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 excluding the metal halide and water from the metal halide-coated iron powder (A). 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, still more preferably 40 to 60 parts by mass, and even more preferably 40 to 55 parts by mass, per 100 parts by mass of 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 provided to the metal halide-coated iron powder (A), thereby achieving a balance between the initial oxygen absorption rate and the oxygen absorption performance.

[0047] The moisture donating agent (B) preferably contains sodium chloride. When the moisture donating agent (B) contains sodium chloride, the water activity can be adjusted, and the initial oxygen absorption rate and oxygen absorption performance can be balanced.

[0048] The amount of sodium chloride contained in the moisture 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, still more preferably 25 to 37 parts by mass, and even more preferably 30 to 37 parts by mass, relative to 100 parts by mass of water contained in the moisture donor (B). When the amount of sodium chloride contained in the moisture 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.

[0049] (Mixing) In this step, the halide-coated iron powder (A) obtained in step 1 is mixed with the moisture-donating agent (B). The mixing method is not particularly limited. When producing the oxygen absorber package described below, the halide-coated iron powder (A) and the moisture-donating agent (B) may be mixed by placing them in an air-permeable packaging container; the halide-coated iron powder (A) and the moisture-donating agent (B) may be mixed in a mixing container and then placed in the air-permeable packaging container; or the halide-coated iron powder (A) and the moisture-donating agent (B) may be mixed in a mixing container and then placed in the air-permeable packaging container. Among these, mixing by placing the halide-coated iron powder (A) and the moisture-donating agent (B) in an air-permeable packaging container or by mixing the halide-coated iron powder (A) and the moisture-donating agent (B) in a mixing container and then placed in the air-permeable packaging container is preferred.

[0050] [Oxygen Absorber Package] The oxygen absorber package of the present invention is an oxygen absorber package comprising the oxygen absorber composition described above and a breathable packaging container containing the oxygen absorber composition. Specifically, the oxygen absorber package of the present invention comprises an oxygen absorber composition containing a metal halide-coated iron powder (A) having iron oxide on the iron surface and a moisture donor (B), wherein the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A) has an iron element ratio of 90.0 to 96.3 mass %, and a breathable packaging container containing the oxygen absorber composition.

[0051] (Breathable Packaging Container) The breathable packaging container is not particularly limited as long as it is a container made of a packaging material used for oxygen absorbers, but from the viewpoint of ensuring that the oxygen absorber package exhibits sufficient oxygen absorption performance, it includes at least a breathable packaging material, and examples thereof include a bag-shaped container made by bonding two sheets of breathable packaging material together, a bag-shaped container made by bonding one sheet of breathable packaging material and one sheet of non-breathable packaging material together, and a bag-shaped container made by folding one sheet of breathable packaging material and sealing the edges excluding the folded part. Other examples include containers in which a breathable packaging material is bonded to the opening surface of a non-breathable rigid container.

[0052] Here, when the breathable packaging material and the non-breathable packaging material are rectangular, the breathable packaging container may be one formed by overlapping two sheets of breathable packaging material and heat-sealing the four sides to form a bag, one formed by overlapping one sheet of breathable packaging material and one sheet of non-breathable packaging material and heat-sealing the four sides to form a bag, or one formed by folding one sheet of breathable packaging material and heat-sealing three sides excluding the folded part to form a bag. The packaging material may also be one formed by shaping the breathable packaging material into a cylindrical shape and heat-sealing both ends and the body of the cylindrical body to form a bag.

[0053] (Breathable Packaging Material) As the breathable packaging material, a packaging material that is permeable to oxygen and water vapor is selected. Among them, a material having an air resistance of 600 seconds or less, more preferably 90 seconds or less, as measured by a Gurley tester is preferably used. Here, the air resistance refers to a value measured by the method of JIS P8117 (1998). More specifically, it refers to the time required for 100 mL of air to permeate the breathable packaging material using a Gurley densometer (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0054] The breathable packaging material may be paper, nonwoven fabric, or a plastic film that has been given breathability. Examples of the plastic film include laminated films formed by laminating and bonding a film of polyethylene terephthalate, polyamide, polypropylene, polycarbonate, or the like with a film of polyethylene, ionomer, polybutadiene, ethylene acrylic acid copolymer, ethylene methacrylic acid copolymer, ethylene vinyl acetate copolymer, or the like as a sealing layer. These laminates may also be used as breathable packaging materials.

[0055] As a method for imparting breathability, various methods can be adopted, including perforation processing using a cold needle or a hot needle. When perforation processing is used to impart breathability, the breathability can be freely adjusted by the diameter, number, material, etc. of the holes to be perforated.

[0056] The thickness of the laminated film is preferably 50 to 300 μm, and particularly preferably 60 to 250 μm, in which case the film can be made into a packaging material that maintains strength and has excellent heat-sealing properties and packaging suitability, compared to thicknesses outside the above range.

[0057] (Non-breathable packaging material) As the non-breathable packaging material, a packaging material used for oxygen absorbers can be used, and a packaging material that can block moisture, alcohol, oil, and solid components of the stored item and has a sealability is suitable. Specifically, a packaging material having an oxygen permeability of 0.05 to 20 mL / m, such as a polyethylene terephthalate or nylon-based co-extruded multilayer sheet or film, is suitable. ２ - 24 hr·atm (25°C, 50% RH) laminates and the like.

[0058] [Method for manufacturing oxygen absorber package] The method for manufacturing the oxygen absorber package is not limited, but it is preferably obtained 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 placed in a breathable packaging container.

[0059] The method for packaging the oxygen scavenger composition in a breathable packaging container may be, as described above, a method in which the halide-coated iron powder (A) and the moisture donor (B) constituting the oxygen scavenger composition are placed in a breathable packaging container and mixed, the oxygen scavenger composition is formed in the breathable packaging container, and the oxygen scavenger composition is packaged in the breathable packaging container, or a method in which the halide-coated iron powder (A) and the moisture donor (B) are mixed in advance, and the resulting oxygen scavenger composition is packaged in a breathable packaging container. From the viewpoints of producing an oxygen scavenger package simply and in a short time and suppressing excessive oxidation reactions, a method in which the halide-coated iron powder (A) and the moisture donor (B) constituting the oxygen scavenger composition are placed in a breathable packaging container and mixed, the oxygen scavenger composition is formed in the breathable packaging container, and the oxygen scavenger composition is packaged in the breathable packaging container is preferred.

[0060] [Oxygen absorbing method] The oxygen absorbing method of the present invention is a method of absorbing oxygen in which the oxygen absorber composition or the oxygen absorber package and a preserved item are placed in a gas barrier container. The oxygen absorbing method of the present invention is preferably a method of absorbing oxygen in which the oxygen absorber package and a preserved item are placed in a gas barrier container.

[0061] The oxygen scavenger composition used in the oxygen scavenging method of the present invention is specifically, as described above, an oxygen scavenger composition containing a metal halide-coated iron powder (A) having an iron oxide on its surface and a moisture donor (B), wherein the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A) has an iron element ratio of 90.0 to 96.3 mass%. The oxygen scavenger package used in the oxygen scavenger method of the present invention is specifically, as described above, an oxygen scavenger package comprising: a metal halide-coated iron powder (A) having an iron oxide on its surface and a moisture donor (B), wherein the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A) has an iron element ratio of 90.0 to 96.3 mass%, and a breathable packaging container containing the oxygen scavenger composition.

[0062] (Gas Barrier Container) The gas barrier container is not particularly limited as long as it is sealable and has substantial gas barrier properties, and can be appropriately selected depending on the properties, use, price, etc. of the preserved item. If the preserved item is to be consumed within a short period of time, a container with relatively poor gas barrier properties may be used. However, if the preserved item requires long-term storage or is oxygen-sensitive, a container with high gas barrier properties is required. From the viewpoint of blocking external ventilation, the gas barrier container is preferably made of the above-mentioned non-breathable packaging material. Specifically, a gas barrier container having an oxygen permeability of 0.05 to 20 mL / m, such as a polyethylene terephthalate or nylon-based co-extruded multilayer sheet or film, or a multilayer sheet or film having a laminated structure such as polyethylene terephthalate / aluminum vapor deposition / polyethylene, oriented polypropylene / polyvinyl alcohol / polyethylene, or polyvinylidene chloride-coated oriented nylon / polyethylene, is preferred. ２Bags and packaging containers made of the 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.

[0063] The preserved item is preferably one whose quality can be prevented from deteriorating by avoiding contact with oxygen, and the preserved item is preferably food, industrial products, or pharmaceuticals.

[0064] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention.

[0065] The present embodiment will be described in detail below using examples and comparative examples, but the present embodiment can be modified as appropriate as long as the effects of the present invention are achieved. In the examples and comparative examples, "parts" refers to parts by mass unless otherwise specified. Furthermore, various measurements and evaluations in the examples and comparative examples were performed as follows.

[0066] <Ratio of Iron Element in Iron Powder> The ratio of iron element in iron powder obtained by removing metal halide and water from metal halide-coated iron powder was measured by the calibration curve method using an inductively coupled plasma (ICP) optical emission spectrometer as follows. (Creation of Calibration Curve) A 1000 μg / mL Fe standard solution (Kanto Chemical Co., Ltd., for chemical analysis) was diluted with 5 mL of a 400 μg / mL Co standard solution (Kanto Chemical Co., Ltd., for chemical analysis), 1 mL of hydrochloric acid, and pure water to a final volume of 100 mL to prepare calibration curve standard solutions with Fe concentrations of 0, 10, 20, 40, and 60 μg / mL. The calibration curve standard solutions were measured using a multi-ICP optical emission spectrometer (SPECTRO ARCOS, SPECTRO Analytical Instruments), and a calibration curve of the Fe / Co amount ratio and the Fe / Co intensity ratio was created. (Preparation of measurement solution) 0.5 g of halide-coated iron powder was weighed into a 100 mL glass beaker, 5 mL of hydrochloric acid was added, and the beaker was covered with a glass watch glass. Next, the beaker was heated at an oven temperature of 150 °C for 1 hour. After cooling, the solution was transferred to a 100 mL polypropylene container and the entire volume was poured in with pure water to bring the Fe aqueous solution volume to 100 g. Next, 0.5 g of the Fe aqueous solution, 5 mL of a 400 μg / mL Co standard solution (Kanto Chemical Co., Inc., for chemical analysis), and 1 mL of hydrochloric acid were added to a 100 mL measuring flask, and the volume was adjusted to 100 mL with pure water to obtain a measurement solution. (Measurement of Iron Element Proportion) The above-mentioned measurement solution was measured using a multi-ICP optical emission spectrometer (SPECTRO ARCOS, manufactured by SPECTRO Analytical Instruments), and the amount of iron element in the measurement solution was determined from the Fe / Co intensity ratio and the above-mentioned calibration curve. The iron element proportion in the iron powder obtained by removing the metal halide and water from the metal halide-coated iron powder was calculated using the following formula: [Iron element proportion (mass %)] = ([Amount of iron element in measurement solution] × 100 / 0.5) / ([Mass of product (metal halide-coated iron powder) after coating process] - [Total mass of raw materials other than raw iron powder] - [Mass of water in metal halide-coated iron powder]) × 100. In Examples 1 to 6 and Comparative Examples 1 and 2, the "total mass of raw materials other than raw iron powder" in the above formula is the mass of the metal halide. The mass of water in the halide-coated iron powder was measured using 0.3 g of the halide-coated iron powder with a heat-vaporization Karl Fischer moisture meter (MKC-610, manufactured by Kyoto Electronics Manufacturing Co., Ltd.).<Ratio of Iron Element in Raw Iron Powder> The ratio of iron element in raw iron powder was also determined by the calibration curve method using an inductively coupled plasma (ICP) emission spectrometer, similar to the above <Ratio of Iron Element in Iron Powder>.

[0067] <Oxygen Absorption of Oxygen Absorber Composition> A rubber sheet for sampling (25 mm x 25 mm, 2 mm thick) was adhered to one side of an aluminum bag (aluminum foil-laminated plastic film bag, 350 mm x 400 mm) to obtain an aluminum bag for measurement. Next, the oxygen absorber packages (containing an oxygen absorber composition containing 1.00 g of halide metal-coated iron powder) obtained in the Examples and Comparative Examples and 3000 mL of air were placed in the aluminum bag for measurement, and the opening was heat-sealed. The aluminum bag was then immediately placed in a thermostatic chamber at 25°C. Two hours and 48 hours after sealing, the oxygen concentration in the aluminum bag was measured, and the oxygen absorption amount was calculated. Table 1 shows the oxygen absorption amount (mL) per 1 g of halide metal-coated iron powder. The oxygen concentration was measured using an oxygen analyzer (ISM-3, MOCON Corporation), with the measuring needle inserted through the rubber sheet into the aluminum bag, and automatic measurement was performed for 48 hours. The smaller the oxygen absorption amount after 2 hours, the more suppressed the initial oxygen absorption and the easier it is to handle in the atmosphere, which is preferable. Specifically, if the amount is 30 mL or less per 1 g of halide-coated iron powder, the more suppressed the initial oxygen absorption and the easier it is to handle in the atmosphere, which is more preferable. Furthermore, the larger the oxygen absorption amount after 48 hours, the more preferable it is, since sufficient oxygen absorption performance can be exhibited. Specifically, if the amount is 200 mL or more, the more preferable it is, since sufficient oxygen absorption performance can be exhibited.

[0068] [Production of oxygen absorber composition and oxygen absorber package] Example 1 (1) 0.194 g of calcium chloride dihydrate (0.146 g of calcium chloride) was dissolved in 17.50 g of water to obtain an aqueous calcium chloride solution. This aqueous solution was mixed with atomized iron powder (manufactured by Kobe Steel, Ltd., average particle size 100 μm (D50 diameter measured with a laser diffraction / scattering particle size distribution analyzer), specific surface area 0.052 m) and 17.50 g of water. ２100 g of 100 g of 100% NaCl (calcium chloride / g, iron element ratio: 99.86 mass%) was mixed in an air atmosphere (oxygen concentration 21 vol%) and stirred with a spatula. The iron powder gradually heated to approximately 120°C due to self-heating and dried. This resulted in a halide-coated iron powder. The iron element ratio in the iron powder obtained by removing calcium chloride and water from the halide-coated iron powder was 94.4 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 with a laser diffraction / scattering particle size distribution analyzer)) to prepare a moisture-donating agent. The water activity of the resulting moisture-donating agent was 75% RH. (3) 1.00 g of the metal halide-coated iron powder obtained in (1) above and 1.35 g of the moisture donor obtained in (2) above were filled into a 40 mm x 40 mm bag (breathable packaging container) made of breathable laminated film (composition: polyethylene nonwoven fabric ("Elves" manufactured by Unitika Ltd.) / oil-resistant synthetic paper ("Alto" manufactured by Awa Paper Co., Ltd.)) and mixed to obtain an oxygen absorber composition. The opening was then sealed to obtain an oxygen absorber package. The evaluation results are shown in Table 1.

[0069] Examples 2 to 4, 6 and Comparative Example 1 Oxygen absorber compositions and oxygen absorber packages were obtained in the same manner as in Example 1, except that the amount of calcium chloride dihydrate (calcium chloride) and the amount of water in which calcium chloride was dissolved were changed to the amounts shown in Table 1. The evaluation results are shown in Table 1.

[0070] Example 5 An oxygen absorber composition and an oxygen absorber package were obtained in the same manner as in Example 1, except that in (1) of Example 1, the amount of atomized iron powder was 3,000 g, the amount of calcium chloride dihydrate was 4.5 g (3.3 g of calcium chloride), and the amount of water was 527.4 g, and a 10 L ribbon mixer (manufactured by Ohno Chemical Machinery Co., Ltd.) was used as the stirring and mixing device. The evaluation results are shown in Table 1.

[0071] Comparative Example 2 In (1) of Example 1, the iron powder was replaced with reduced iron powder (manufactured by Höganäs, average particle diameter 100 μm (D50 diameter measured with a laser diffraction / scattering particle size distribution analyzer, iron element ratio: 99.9 mass%), specific surface area 0.085 m ２ / g), sodium chloride was used instead of calcium chloride dihydrate in the amount shown in Table 1, and the amount of water was changed to the amount shown in Table 1. The oxygen absorber compositions and oxygen absorber packages were obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0072]

[0073] As shown in Table 1, the oxygen absorber compositions of the Examples had a low oxygen absorption amount up to 2 hours after being sealed in a product, indicating that initial oxygen absorption was suppressed. Furthermore, the oxygen absorption amount after 48 hours was high, indicating that sufficient oxygen absorption performance was exhibited. From these results, the oxygen absorber composition of the present invention is easy to handle in the atmosphere and yet exhibits sufficient oxygen absorption performance, making it useful as an oxygen absorber that can be used in a wide range of products, such as food, industrial products, and pharmaceuticals.

Claims

1. A deoxidizer composition containing metal halide-coated iron powder (A) having iron oxide on the iron surface and a moisture provider (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 90.0 to 96.3% by mass.

2. The deoxidizer 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 deoxidizer 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 deoxidizer composition according to any one of claims 1 to 3, wherein the content of the metal halide in the metal halide-coated iron powder (A) is 0.10 part by mass or more and 1.00 part by mass or less with respect to 100 parts by mass of the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A).

5. The deoxidizer composition according to any one of claims 1 to 4, wherein the moisture provider (B) is obtained by impregnating a carrier with water.

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

7. The deoxidizer composition according to claim 5 or 6, wherein the amount of water contained in the moisture provider (B) is 15 to 60 parts by mass with respect to 100 parts by mass of the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A).

8. The deoxidizer 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, activated carbon, and bentonite.

9. A method for producing a deoxidizer composition, comprising step 1 of 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 of mixing the metal halide-coated iron powder (A) and a moisture provider (B), wherein the amount of the metal halide contained in the aqueous solution of the metal halide is 0.10 part by mass or more and 1.00 part by mass or less with respect to 100 parts by mass of the iron powder (a).

10. The method for producing a deoxidizer composition according to claim 9, wherein the amount of water contained in the aqueous solution of the metal halide is 10 to 20 parts by mass with respect to 100 parts by mass of the iron powder (a).

11. The method for producing a deoxidizer composition according to claim 9 or 10, wherein the concentration of the aqueous solution of the metal halide is 0.1 to 10% by mass.

12. The method for producing a deoxidizer composition according to any one of claims 9 to 11, wherein in step 1, it is dried by self-heating during mixing.

13. The method for producing a deoxidizer 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. The method for producing a deoxidizer 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. The method for producing a deoxidizer composition according to any one of claims 9 to 14, wherein the moisture donor (B) is water impregnated in a carrier.

16. The method for producing a deoxidizer composition according to any one of claims 9 to 15, wherein the moisture donor (B) contains sodium chloride.

17. The method for producing a deoxidizer composition according to claim 15 or 16, wherein the amount of water contained in the moisture donor (B) is 15 to 60 parts by mass with respect to 100 parts by mass of the iron powder obtained by removing the metal halide and moisture from the metal halide-coated iron powder (A).

18. The method for producing a deoxidizer 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, activated carbon, and bentonite.

19. A deoxidizer package comprising the deoxidizer composition according to any one of claims 1 to 8 and a breathable packaging container containing the deoxidizer composition.

20. The method for producing a deoxidizer package, wherein the deoxidizer composition according to any one of claims 1 to 8 is contained in a breathable packaging container.

21. A deoxidation method, wherein the deoxidizer composition according to any one of claims 1 to 8 or the deoxidizer package according to claim 19 and the object to be preserved are contained in a gas-barrier container.

22. The deoxidation method according to claim 21, wherein the object to be preserved is food, industrial products, or pharmaceuticals.

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