JP2014030784A - Method for manufacturing oxygen absorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an oxygen absorbent capable of maintaining stable oxygen absorbing properties without excessive heat evolution in the atmosphere.SOLUTION: The method for manufacturing an oxygen absorbent includes: treating an alloy (X) which includes at least one transition metal (A) selected from the group consisting of the manganese group, the iron group, the platinum group, and the copper group, and at least one metal (B) selected from the group consisting of aluminum, zinc, tin, lead, magnesium, and silicon, with aqueous acid or alkaline solution so as to elute at least a portion of the component (B) for removal; and oxidizing the surface of an alloy (Y) having the portion of at least partially removed component (B) with oxygen gas so as to form a coating film of metal oxide on at least one part of the surface of the alloy (Y).

Description

  The present invention relates to a method for producing an oxygen absorbent, and more particularly to a method for producing an oxygen absorbent capable of suppressing excessive heat generation in an air atmosphere and stably maintaining oxygen absorption performance.

  One storage technique for foods and pharmaceuticals is a storage technique using an oxygen absorbent (deoxygenating agent). Specifically, an oxygen scavenger that removes oxygen in the atmosphere is placed inside the sealed package together with the object, and the inside of the sealed package is made oxygen-free, thereby causing oxidative degradation, mold, This technology suppresses discoloration and the like.

  So far, oxygen absorbers that remove oxygen in the atmosphere have been proposed from various inorganic materials and organic materials. For example, metal powder such as iron as an inorganic main ingredient, sulfite, bisulfite, nitrite, etc., organic main ingredient L-ascorbic acid, erythorbic acid and their salts, sugars such as glucose, Examples include those using reducing polyhydric alcohols such as catechol and pyrogallol.

  However, these conventional oxygen scavengers have a problem that a practical oxygen scavenging ability cannot be obtained unless water or moisture is supplied at the time of use. In other words, conventional oxygen scavengers use water or a substance that retains moisture, for example, a compound having water of crystallization, or water vapor generated from food to be stored. For the first time, practical deoxygenation ability could be obtained. For this reason, it has been difficult to apply conventional oxygen scavengers to rust prevention preservation of pharmaceuticals or dry foods that need to be used or stored under dry conditions, and metal products that dislike the presence of water or moisture. .

  For this reason, in these applications, an oxygen absorbent that does not require moisture during oxygen absorption has been demanded. As an oxygen absorbent that can meet such demands, for example, a deoxygenating agent mainly using cerium oxide utilizing oxygen defects (Japanese Patent Laid-Open No. 2007-185653), and a titanium oxide having oxygen defects as a main agent. An oxygen scavenger (Japanese Patent Laid-Open No. 2005-104064), a oxygen scavenger based on a metal subjected to hydrogen reduction (Japanese Patent Laid-Open No. 62-277148), a oxygen scavenger utilizing auto-oxidation of organic matter, and the like It has been reported.

  However, among the oxygen scavengers described above, the oxygen scavengers disclosed in Japanese Patent Application Laid-Open No. 2007-185653 and Japanese Patent Application Laid-Open No. 2005-104064 are rare and expensive because the raw metal is a rare metal. . In addition, imports from overseas must be relied on, and depending on the situation, purchases may fluctuate and stable production may not be expected. For this reason, it was not necessarily satisfactory from the viewpoint of cost and stable supply. In addition, the oxygen scavenger disclosed in JP-A-62-277148 needs to be accompanied by a large-scale hydrogen reduction facility in production, and thus it can be said that it is not a simple method and is easy to handle in the atmosphere. Absent. Furthermore, since the oxygen scavenger using the auto-oxidation of the organic substance described above uses an organic substance oxidation reaction as a main agent, there is a problem of by-products generated after oxygen absorption.

  Therefore, it is an oxygen absorbent that has the ability to absorb oxygen in the atmosphere even in an atmosphere with little or no moisture, the raw material is inexpensive and stable, there are almost no problems of by-products, hydrogen There was still a desire for a device that does not require the attachment of a large-scale device as in the case of performing reduction.

JP 2007-185653 A JP 2005-104064 A Japanese Patent Laid-Open No. 62-277148

  The present inventors have found that the metal in which only aluminum is removed using an aqueous solution of sodium hydroxide from an alloy of aluminum and iron or an alloy of aluminum and nickel is 30% RH (25 ° C.) or less. Even in an atmosphere with little or no oxygen, the oxygen in the atmosphere can be absorbed and removed at a level equivalent to that of a conventional oxygen scavenger. Finding that it can be easily and inexpensively manufactured without using such a large-scale apparatus, and that this metal can be used as an oxygen scavenger to absorb oxygen even in an atmosphere with little moisture Got.

  However, the above-mentioned metals have a very high oxygen absorption activity and may generate heat by reacting with oxygen even in the air atmosphere. When the oxygen absorbent is used without generating heat, the oxygen absorbent is used in a specific environment. It is necessary to use under (for example, under an oxygen-free atmosphere). In this case, since a facility or the like is required to obtain a specific environment, handling is complicated and handling costs are increased.

  And the present inventors have now noticed that the oxygen absorption activity can be controlled by gradually oxidizing the metal with a mixed gas stream having a low oxygen concentration to form a metal oxide on the metal surface. According to the present invention, it has been found that an oxygen absorbent capable of suppressing excessive heat generation in an air atmosphere and stably maintaining oxygen absorption performance can be produced. The present invention is based on this finding.

  Accordingly, an object of the present invention is to provide a method for obtaining an oxygen absorbent capable of suppressing excessive heat generation in an air atmosphere and stably maintaining oxygen absorption performance.

The method for producing an oxygen absorbent according to the present invention comprises:
(A) at least one transition metal selected from the group consisting of manganese, iron, platinum and copper; and (B) selected from the group consisting of aluminum, zinc, tin, lead, magnesium and silicon. And subjecting the alloy (X) containing at least one metal to an acid or alkali aqueous solution treatment to elute and remove at least a part of the component (B),
Oxidizing the surface of the alloy (Y) from which at least a part of the component (B) has been removed to form a film made of a metal oxide on at least a part of the surface of the alloy (Y);
It is meant to include.

  According to the aspect of the present invention, the component (A) may be selected from the group consisting of iron, cobalt, nickel, and copper.

  According to the aspect of the present invention, the component (B) may be aluminum.

  Moreover, according to the aspect of the present invention, elution removal of the component (B) may be performed until the content of the component (B) contained in the alloy (Y) becomes 0.01 to 50% by mass. .

  According to an aspect of the present invention, the acid or alkali aqueous solution may be a sodium hydroxide aqueous solution.

  According to the aspect of the present invention, the alloy (X) powder containing the component (A) and the component (B) is subjected to an acid or alkali aqueous solution treatment, so that at least one of the component (B) is obtained. The powdered alloy (Y) may be obtained by elution and removal of the part.

  Moreover, according to the aspect of the present invention, the alloy (Y) may be oxidized in a mixed gas having an oxygen concentration of 0.1 to 10% by volume or a stream of reduced pressure air of 0.5 to 50 kPa. Good.

  According to another aspect of the present invention, an oxygen absorbent obtained by the above-described method is also provided.

  In the oxygen absorbent according to the aspect of the present invention, the alloy (Y) obtained by eluting and removing at least a part of the component (B) may have a porous shape.

In the oxygen absorbent according to the present invention, the alloy (Y) obtained by eluting and removing at least part of the component (B) has a specific surface area measured by the BET method of at least 10 m ² / g. Also good.

  According to another aspect of the present invention, an oxygen-absorbing package formed by packaging the above-described oxygen absorbent with a packaging material using all or part of a breathable packaging material, and an oxygen absorbent as a thermoplastic resin. An oxygen-absorbing resin composition is also provided.

  Moreover, according to another aspect of this invention, the oxygen-absorbing resin sheet or film which consists of the said oxygen-absorbing resin composition is also provided.

  According to the method for producing an oxygen absorbent according to the present invention, at least a part of the component (B) is eluted and removed from the alloy (X) containing the specific transition metal (A) and the specific metal (B). After obtaining Y), the surface of the alloy (Y) is oxidized to form a film made of a metal oxide on at least a part of the surface of the alloy (Y), thereby generating excessive heat generation in an air atmosphere. An oxygen absorbent that can suppress and stably maintain the oxygen absorption performance can be obtained.

<Method for producing oxygen absorbent>
The method for producing an oxygen absorbent according to the present invention includes (1) eluting and removing at least part of the component (B) from an alloy (X) containing a specific transition metal (A) and a specific metal (B). (Y) and (2) oxidizing the surface of the alloy (Y) from which at least a part of the component (B) has been removed, so that at least a part of the surface of the alloy (Y) is made of a metal oxide. Forming a coating film. Hereinafter, each process of the method for producing an oxygen absorbent will be described. In the present specification, the “oxygen absorber” refers to an agent that can selectively absorb oxygen from the ambient atmosphere in which the agent is installed.

Ingredient (A)
Transition metals that can be used as component (A) constituting the oxygen absorber are manganese group (manganese, technetium, rhenium), iron group (iron, cobalt, nickel), platinum group (ruthenium, rhodium, palladium, osmium, iridium). , Platinum) and copper group (copper, silver, gold). The above transition metals may be used alone or in combination of two or more. For example, when iron and nickel are selected, an Fe—Ni alloy may be used as the component (A).

  The component (A) is preferably manganese, iron, cobalt, nickel, or copper, more preferably iron, cobalt, nickel, or copper, and still more preferably iron, nickel, Preferably, it is iron. Among these, iron is preferable because it is safe and inexpensive.

Ingredient (B)
As the component (B) constituting the oxygen absorbent, one selected from aluminum, zinc, tin, lead, magnesium and silicon is used. These may be used alone or in combination of two or more. Among those exemplified as the component (B), those selected from aluminum, zinc, magnesium or silicon are preferable, aluminum, zinc, magnesium or silicon is more preferable, and aluminum is more preferable. Of these, aluminum is preferable because it is inexpensive.

  The oxygen absorbent according to the present invention prepares an alloy (X) containing the component (A) and the component (B) described above. At this time, the alloy (X) further contains molybdenum, chromium as an additive metal. , Titanium, vanadium, tungsten, or the like may be added. It may further contain additional components such as cyanic acids.

  The alloy (X) containing the component (A) and the component (B) as described above can be prepared by a melting method. At this time, the composition ratio of the component (A) and the component (B) is preferably 20 to 80% by mass when the component (A) is 20 to 80% by mass, and more Preferably, when the component (A) is 30 to 70% by mass, the component (B) is 30 to 70% by mass. To give a more specific example, when the component (A) is iron or nickel and the component (B) is aluminum, the proportion of iron or nickel is 30 to 55 mass%, and the proportion of aluminum is 45 to 70 mass%. Preferably there is.

  The obtained alloy (X) may be subjected to an acid or alkali aqueous solution treatment as it is, but is usually subjected to an acid or alkali aqueous solution treatment after being finely pulverized. In this specification, “alloy” includes not only a single composition having a specific crystal structure but also a mixture thereof and a mixture of metals themselves.

  As a method for finely pulverizing the alloy (X), a conventional method for pulverizing and pulverizing metals can be used as appropriate, for example, pulverizing with a jaw crusher, a roll crusher, a hammer mill, etc. Depending on the condition, it can be finely pulverized with a ball mill. Alternatively, the molten alloy may be pulverized by a rapid solidification method such as an atomizing method. Here, when the atomizing method is used, it is preferably performed in an inert gas such as an argon gas. As the atomizing method, for example, the method described in JP-A-5-23597 can be used.

  The particle size of the obtained alloy powder is preferably in the range of 5 to 200 μm, and the particle size distribution is preferably as narrow as possible. From the viewpoint of eliminating particles having a large particle size or aligning the particle size distribution, sieving (classification) may be appropriately performed using a commercially available mesh sieve (for example, a 200 mesh sieve). In the case of the atomizing method, the powder tends to be nearly spherical and the particle size distribution tends to be narrow.

Next, the alloy (X) or the powder thereof obtained as described above is subjected to an acid or alkali aqueous solution treatment to elute and remove at least a part of the component (B) from the alloy (X). That is, in the present invention, the alloy (Y) obtained after eluting and removing at least a part of the component (B) from the alloy (X) is used as an oxygen absorbent. As the aqueous solution of acid or alkali, the component (A) does not dissolve or hardly dissolves, and the component (B) mainly dissolves, or both the components (A) and (B) dissolve. As long as the dissolution rate of the component (B) is higher than that of the component (A), it can be used without any particular limitation. Examples of the acid in the aqueous acid solution include hydrochloric acid, sulfuric acid, and nitric acid. Examples of the alkali in the aqueous alkali solution include sodium hydroxide, potassium hydroxide, calcium hydroxide, and tetramethylammonium hydroxide (TMAH). ), Na ₂ CO ₃ , K ₂ CO ₃ , ammonia, and the like. About these acid and alkali aqueous solution, you may use it in combination of 2 or more type as needed.

  According to a preferred embodiment of the present invention, an aqueous alkali solution is preferably used as the aqueous acid or alkali solution, more preferably an aqueous sodium hydroxide solution. For example, when aluminum is used as the component (B), when sodium hydroxide is used as the alkaline aqueous solution, excess sodium hydroxide can be easily removed by washing with water, and the eluted aluminum can be easily removed. The effect of reducing the number of washings can be expected.

  In the treatment with an acid or alkali aqueous solution, usually, if an alloy powder is used, the alloy powder is gradually added to the acid or alkali aqueous solution while stirring, but the alloy powder is put in water and concentrated acid solution is added. Alternatively, alkali may be dropped.

  In the acid or alkali aqueous solution treatment, the concentration of the acid or alkali aqueous solution used is, for example, 5 to 60% by mass, and more specifically, for example, 10 to 40% by mass in the case of sodium hydroxide.

  In the acid or alkali aqueous solution treatment, the temperature of the aqueous solution is preferably about 20 to 120 ° C., for example. A more preferable temperature is 25 to 100 ° C.

  The treatment time for which the alloy or alloy powder is subjected to the acid or alkali aqueous solution treatment may vary depending on the shape and state of the alloy used, the amount thereof, the concentration of the acid or alkali aqueous solution, the temperature during the treatment, etc. Usually, it may be about 30 to 300 minutes. By adjusting the treatment time, the elution amount of the component (B) from the alloy can be adjusted.

  In the present invention, at least part of the component (B) is eluted and removed from the alloy (X) by treatment with an aqueous solution of acid or alkali. Here, “leaving and removing at least a part of the component (B)” means that a part of the component (B) is eluted and removed from the alloy (X) containing the component (A) and the component (B). In addition, it also includes the case where all of the component (B) is eluted and removed from the alloy (X). Therefore, in the present invention, the “alloy (Y)” is a concept including a metal from which all of the component (B) is eluted (that is, a metal composed only of the component (A)). In addition, in the process of elution of component (B), the possibility that a part of component (A) is dissolved as a result cannot be denied. Therefore, “at least a part of component (B)” includes only component (B). It is not necessary to interpret the present invention only when it is eluted with an aqueous solution of acid or alkali.

  By the aqueous solution treatment with acid or alkali, at least a part of component (B) (for example, aluminum), preferably most of the component (B) is eluted from the alloy (X). The rate of elution of the component (B) from the alloy (X) can be represented by the content (mass basis) (residual rate) of the component (B) in the alloy (Y) obtained by elution removal.

  In the metal used as the oxygen absorbent (that is, the alloy (Y) after eluting the component (B)), the content of the component (B) is preferably 0.01 to 50% by mass, more preferably It is 0.1-40 mass%. More specifically, for example, when the alloy (X) is an Al—Fe alloy, the aluminum content in the alloy (Y) obtained by elution removal of aluminum by treatment with an aqueous solution of acid or alkali is preferably 0. It is 0.01-50 mass%, More preferably, it is 0.1-40 mass%, More preferably, it is 1-5 mass%. In addition, content of the component (B) (for example, aluminum) in the alloy (Y) used for an oxygen absorber can be measured by ICP method, for example.

  Next, the surface of the alloy (Y) from which at least a part of the component (B) has been dissolved out is oxidized to form a film made of a metal oxide on at least a part of the surface of the alloy (Y). The alloy (Y) from which at least a part of the component (B) metal is eluted has a very high oxygen absorption activity, and may react with oxygen even in an air atmosphere to generate heat. As described above, the surface of the alloy (Y) after elution of the metal of the component (B) is slightly oxidized to form an oxide film on at least a part of the surface of the alloy (Y). Can be controlled. The reason why heat generation due to reaction with oxygen is suppressed by forming an oxide film on the surface of the alloy (Y) is not clear, but is considered as follows.

  By oxidizing the alloy (Y), a metal oxide film is formed on the surface of the alloy (Y). It is considered that this coating inhibits the diffusion of oxygen into the pores of the alloy (Y) and does not cause a rapid oxidation reaction, and as a result, heat generation is suppressed.

  As described above, as a method for finely oxidizing the surface of the alloy, a low oxygen concentration mixed gas, for example, an alloy is treated by flowing an oxygen / nitrogen mixed gas stream having an oxygen concentration of 0.1 to 10% by volume. The surface can be finely oxidized. The rapid oxidation is not only dangerous due to heat generation of the alloy, but also deteriorates the oxygen absorption performance. Therefore, it is preferable to carry out the oxidation treatment under such conditions that fine oxidation is performed. Therefore, fine oxidation may be performed using not only the above mixed gas having a low oxygen concentration but also decompressed air. For example, the fine oxidation treatment can be performed under a stream of reduced pressure air of about 0.5 to 50 kPa.

  The degree of the oxidation treatment of the alloy depends on the oxygen activity of the alloy, the amount of alloy treatment, the flow rate of the mixed gas or reduced pressure air, etc., but the alloy is treated for about 0.5 to 5 hours under the above mixed gas or reduced pressure air flow. By this, the film which consists of metal oxides can be formed in a part of surface of an alloy (Y).

  The fine oxidation treatment of the alloy (Y) from which the metal of the component (B) is eluted and removed may be performed when the alloy (Y) after elution and removal is washed with water, or may be performed during drying after washing with water, Moreover, you may carry out after drying.

  The oxygen absorbent obtained as described above can suppress excessive heat generation in an air atmosphere and can stably maintain oxygen absorption performance. Although depending on the usage of the oxygen absorbent, the surface temperature when the oxygen absorbent is taken out into the atmosphere is preferably 250 ° C. or lower, more preferably 200 ° C. or lower, further preferably 150 ° C. or lower, 100 It is particularly preferable that the temperature is not higher than ° C. For example, when an oxygen absorbent is taken out from the oxygen-free environment into the atmosphere and kneaded with a thermoplastic resin or the like, the oxygen absorbent having a lower surface temperature is kneaded with a thermoplastic resin having lower heat resistance. Is possible.

<Oxygen absorber>
The alloy (Y) obtained as described above has a porous shape (or a porous body). Here, the porous shape means a state having a large number of pores on the surface and inside that can be confirmed with an electron microscope. In the present invention, the degree of the porous shape of the alloy (Y) can be expressed by its specific surface area. Specifically, the specific surface area by the BET method of the alloy used in the oxygen absorber of the present invention (Y) is at least ^{10 m} 2 / g, preferably at least ^{20 m} 2 / g, more preferably at least ^{40 m} 2 / g.

For example, in the present invention, when iron is used as the component (A) and aluminum is used as the component (B), the specific surface area (by the BET method) of the obtained porous alloy (Y) is 20 to 40 m. ^{In the} case of normal iron powder (reduced iron powder or atomized iron powder) that is about ² / g but not porous, its specific surface area is about 0.07 to 0.13 m ² / g, and is porous. It is clear whether or not.

Further, the degree of the porous shape of the alloy (Y) can also be expressed by bulk density. The bulk density of the alloy (Y) used for the oxygen absorbent of the present invention is 2 g / cm ³ or less, and preferably 1.5 g / cm ³ or less. Incidentally, in the case of normal iron powder (reduced iron powder or atomized iron powder) that is not porous, the bulk density is about 2 to ³ g / cm ³ .

  In the present invention, since the porous alloy (Y) used as an oxygen absorbent has high oxygen absorption activity, it is a condition under low humidity conditions (for example, 30% RH (relative humidity) (25 ° C.) or less. ) Can be suitably used as an oxygen absorbent. Needless to say, it can be suitably used as an oxygen absorbent even in an atmosphere of high humidity conditions (for example, conditions of 100% RH (relative humidity) (25 ° C.)).

  Therefore, the alloy (Y) obtained as described above has at least 5 mL / g oxygen, more preferably 10 mL / g oxygen in a low humidity atmosphere of 30% RH (relative humidity) (25 ° C.) or less. , Can be absorbed. Moreover, when the said alloy (Y) is used as an oxygen absorber, the oxygen absorption amount will be 5-150 mL / g in the low humidity atmosphere below 30% RH (relative humidity) (25 degreeC), for example.

<Use of oxygen absorbent>
Since the oxygen absorbent composition, particularly the porous alloy (Y) used, is easily oxidized and deteriorated in the atmosphere, the alloy (Y) is mixed with a thermoplastic resin (kneading) in use. And can be used in the form of an oxygen-absorbing resin obtained. This oxygen-absorbing resin can be formed into a film or a sheet by extruding and stretching after kneading to obtain an oxygen-absorbing film or sheet.

  The type of the thermoplastic resin used is not particularly limited, and for example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, elastomer, or a mixture thereof can be used.

  Alternatively, the oxygen absorbent may be an oxygen absorbent package that is packaged with a packaging material that uses all or part of a breathable packaging material. As a packaging material, a bag-like shape obtained by bonding two air-permeable packaging materials, a bag-like shape obtained by bonding one breathable packaging material and one non-breathable packaging material, One example is one in which a single air-permeable packaging material is bent and the edges excluding the bent portion are sealed to form a bag. Further, as the breathable packaging material, a packaging material that transmits oxygen and carbon dioxide can be used. Examples of such a breathable packaging material include those obtained by imparting breathability to a conventionally known plastic film in addition to paper and non-woven fabric.

The oxygen absorbent according to the present invention absorbs oxygen regardless of the water activity and can be applied from a region having a high water activity to a region having a low water activity. Further, it can be suitably applied to articles that have low water activity and need to be stored under dry conditions of low humidity. The water activity is a scale indicating the free water content in an article, and is represented by a number from 0 to 1, with 0 for an article without moisture and 1 for pure water. That is, the water activity Aw of a certain article is expressed as follows: the water vapor pressure in the space after the article is sealed and reached an equilibrium state is P, the water vapor pressure of pure water is P ₀ , and the relative humidity in the space is RH (%). , And
Aw = P / P ₀ = RH / 100
Is defined.

  In order to store low moisture content articles that require low humidity storage conditions, the relative humidity (RH) of the atmosphere in which the low moisture content articles are stored is preferably 20-70%, more preferably 20-50%. It is. The moisture content of the low moisture content article is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 10% by mass or less. As low moisture content articles (packaged products) that require low humidity storage conditions, for example, powders, granular foods (powder soups, powdered beverages, powdered confectionery, seasonings, cereal flour, nutritional foods, health foods, coloring Such as fragrances, flavorings, spices), powders, granule drugs (powdered powders, powdered soaps, toothpastes, industrial chemicals), and molded articles (tablet type), etc. A certain food, medicine, etc. can be illustrated. In particular, when these packages are filled in an oxygen-absorbing package as described later, oxygen in the atmosphere is at a level equivalent to that of a conventional oxygen scavenger, even in an atmosphere with little or no moisture. It can be absorbed and removed. Therefore, it can be suitably used for applications such as deoxidizing the atmosphere of dry foods, pharmaceuticals, and electronic material packages that are difficult to apply conventional oxygen scavengers. For example, it can be suitably used for dry foods such as powder seasonings, powdered coffee, coffee beans, rice, tea, beans, rice crackers, rice crackers, and health foods such as pharmaceuticals and vitamins.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not particularly limited to the following examples.

Example 1
Al (aluminum) powder and Fe (iron) powder were mixed at a ratio of 50% by weight and dissolved in nitrogen to obtain an Al-Fe alloy. The obtained Al—Fe alloy was pulverized using a jaw crusher, a roll crusher and a ball mill, and the pulverized product was classified using a mesh of 200 mesh (0.075 mm), and an Al—Fe alloy powder of 200 mesh or less was obtained. Obtained. After 150 g of the obtained Al—Fe alloy powder was stirred and mixed in a 30 wt% sodium hydroxide aqueous solution at 50 ° C. for 1 hour, the mixed solution was allowed to stand and the upper layer liquid was removed. The remaining precipitate was washed with distilled water until the pH became 10 or less to obtain an Al—Fe porous alloy powder. Therefore, the porous alloy powder was obtained by reaction in an aqueous solution to avoid contact with oxygen.

The obtained porous alloy powder was vacuum dried at 200 Pa or less and 80 ° C. for 2 hours to obtain a dried Al—Fe porous alloy powder. The bulk density of the obtained alloy powder was 1.3 g / cm ³ (measured according to JIS Z2504). This 0.3 g is packaged in a breathable sachet, put in a gas barrier bag (Al foil laminated plastic bag) together with a desiccant, filled with 300 mL of air (oxygen concentration 20.9%), sealed and sealed at 25 ° C. The oxygen concentration after 1-day storage was 16.0%. As a result of calculating the oxygen absorption amount from the reduced oxygen concentration in the gas barrier bag, the oxygen absorption amount was 58.3 mL / g.

Moreover, when the average particle diameter of the obtained Al-Fe porous alloy powder was measured using a particle size / shape distribution measuring instrument (“PITA-2” manufactured by Seishin Enterprise Co., Ltd.), the average particle diameter was 31 μm. there were. Furthermore, when the specific surface area of the obtained Al—Fe porous alloy powder was measured using an automatic specific surface area measurement device (“Gemini VII2390” manufactured by Shimadzu Corporation), the specific surface area was 37.0 m ² / g. there were.

  Next, 5 g of the Al—Fe porous alloy powder obtained as described above is placed in an aluminum cup of φ50 × 25 mm, and a gas of 1 vol% oxygen and 99 vol% nitrogen gas is circulated at 500 mL / min for 90 minutes. It was. On the way, the porous alloy powder was stirred with a spatula so that the whole was uniformly oxidized. Thereafter, the oxygen absorption amount of the oxidized Al—Fe porous alloy powder was calculated in the same manner as described above.

  Moreover, 1 g of the oxidized Al—Fe porous alloy powder was wrapped in a glass filter in a nitrogen atmosphere, put into a gas barrier bag (Al foil laminated plastic bag), and then taken out into the atmosphere. A thermocouple was placed on the glass filter containing the alloy powder, and the temperature change of the alloy powder was measured with a temperature data logger. The results were as shown in Table 1 below.

Comparative Example 1
In Example 1, the oxygen absorption amount and temperature change were measured in the same manner as in Example 1 except that the oxidation treatment was not performed. The results were as shown in Table 1 below.

Claims (13)

A method for producing an oxygen absorber, comprising:
(A) at least one transition metal selected from the group consisting of manganese, iron, platinum and copper; and (B) selected from the group consisting of aluminum, zinc, tin, lead, magnesium and silicon. And subjecting the alloy (X) containing at least one metal to an acid or alkali aqueous solution treatment to elute and remove at least a part of the component (B),
Oxidizing the surface of the alloy (Y) from which at least a part of the component (B) has been removed, to form a film made of a metal oxide on at least a part of the surface of the alloy (Y);
The manufacturing method of the oxygen absorber which comprises this.   The method of claim 1, wherein component (A) is selected from the group consisting of iron, cobalt, nickel, and copper.   The method of Claim 1 or 2 that the said component (B) is aluminum.   The elution removal of the said component (B) is performed until the content rate of the component (B) contained in the said alloy (Y) becomes 0.01-50 mass%. the method of.   The method according to any one of claims 1 to 4, wherein the aqueous acid or alkali solution is an aqueous sodium hydroxide solution.   The alloy (X) powder containing the component (A) and the component (B) is subjected to an acid or alkali aqueous solution treatment, and at least a part of the component (B) is eluted and removed. The method according to any one of claims 1 to 5, comprising obtaining an alloy (Y).   The oxidation of the alloy (Y) is performed in a mixed gas having an oxygen concentration of 0.1 to 10% by volume or a stream of reduced pressure air of 0.5 to 50 kPa. The method described in 1.   The oxygen absorber obtained by the method as described in any one of Claims 1-7.   The oxygen absorbent according to claim 8, wherein the alloy (Y) obtained by eluting and removing at least a part of the component (B) has a porous shape. The oxygen absorption according to claim 8 or 9, wherein a specific surface area of the alloy (Y) obtained by eluting and removing at least a part of the component (B) is measured by BET method is at least 10 m ² / g. Agent.   An oxygen-absorbing package formed by packaging the oxygen absorbent according to any one of claims 8 to 10 with a packaging material using all or part of a breathable packaging material.   The oxygen-absorbing resin composition formed by mixing the oxygen absorbent as described in any one of Claims 8-10 with a thermoplastic resin.   An oxygen-absorbing resin sheet or film comprising the oxygen-absorbing resin composition according to claim 12.