JP2007117786A - Oxygen-absorptive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen-absorptive composition, wherein the oxygen absorptivity per unit mass of aluminum is drastically improved and hydrogen is hardly generated as a by-product. <P>SOLUTION: The oxygen-absorptive composition contains a unit of metal aluminum, a unit of an aluminum compound, and a unit of at least one additive selected from the group consisting of phosphoric acid, citric acid, tartaric acid and salts thereof. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an oxygen-absorbing composition that is packaged when packaging food or the like and can prevent oxidative deterioration of contents. In particular, the present invention relates to an oxygen-absorbing composition containing aluminum as a main component of oxygen absorption.

  By using it in the form of a sachet packaged in food packaging, etc., the inside of the packaging is kept in an oxygen-free state, causing discoloration, fading, taste changes and other performance changes due to oxidative deterioration of the contents during storage. In recent years, oxygen absorbers that can be prevented have been frequently used. These oxygen absorbents are, for example, those based on inorganic oxygen-absorbing compositions such as iron powder and silicon fine powder, and those based on organic oxygen-absorbing compositions such as ascorbic acid and unsaturated fatty acids. There are many.

  By the way, since aluminum is not detected by a magnetic metal detector unlike iron, an oxygen absorbent mainly composed of aluminum has an advantage that it can be inspected for contamination of food after being sealed together with food. Moreover, since aluminum is relatively inexpensive and is the same material as an aluminum foil or aluminum vapor deposition film that is generally used as a packaging material, it also has an advantage that it is easy to separate and dispose of waste (easy disposal). Furthermore, the reaction activity with oxygen is also high. For these reasons, proposals have been made to use aluminum as a main component of an oxygen absorbent.

  However, it is well known that aluminum forms a dense oxide film on the surface by oxidation, and this oxide film has low permeability to oxygen and water. That is, oxygen absorption is limited to the surface only. Therefore, by adding a salt such as sodium chloride to aluminum (for example, see Patent Document 1) or by making a mixture of aluminum and an alkali metal oxide and / or alkaline earth metal (for example, see Patent Document 2). Attempts have been made to increase the oxygen absorption of aluminum even slightly. However, in any case, the amount of oxygen absorbed is very small compared to the equivalent iron, and the shape and properties of the aluminum particles are almost unchanged before and after oxygen absorption. Therefore, the situation is far from practical use of an oxygen absorbent mainly composed of aluminum.

In addition, since oxidation of aluminum occurs mainly in the presence of water, in an oxygen absorbent mainly composed of aluminum, aluminum is also consumed in side reactions that generate hydrogen in an aerobic state. There was a problem that efficiency decreased.
JP-A-3-137935 JP-A-9-117660

  An object of the present invention is to propose an oxygen-absorbing composition that can greatly improve the oxygen-absorbing capacity per unit mass of aluminum and that hardly generates hydrogen during use.

  The first of the invention contains a metal aluminum unit, an aluminum compound unit, and a unit of at least one additive selected from the group consisting of phosphoric acid, citric acid, tartaric acid, and salts thereof. The oxygen-absorbing composition is characterized.

  Here, the property of the unit of the additive is preferably an aqueous solution. Moreover, it is preferable that the addition amount of the said additive unit with respect to the said metal aluminum unit is 1 ppm or more and 1 mass% or less. The aluminum compound is preferably an aluminum oxide. The aluminum oxide is preferably γ-alumina. The aluminum oxide is preferably boehmite.

  A second aspect of the invention is an oxygen absorbent comprising any one of the above oxygen-absorbing compositions so as to allow oxygen permeation.

  The oxygen-absorbing composition of the present invention has a high oxygen absorption capacity. Depending on the conditions, it is possible to obtain a value approaching the upper limit of the theoretical absorption amount of aluminum. Therefore, the required oxygen absorption capacity can be obtained with a small amount of metal. On the other hand, the amount of hydrogen generated by side reactions during oxygen absorption is reduced, and the utilization rate of metal aluminum for oxygen absorption is high.

  Hereinafter, the present invention will be specifically described. The oxygen-absorbing composition contains a metallic aluminum unit, an aluminum compound unit, and at least one additive unit selected from the group consisting of phosphoric acid, citric acid, tartaric acid, and salts thereof. Is a mixture of Here, the unit means that each of these three kinds of substances has an independent form. Each unit may be in the form of particles such as powder, fiber, or porous body, or in the form of a solution as long as it can be dissolved in a solvent that can contribute to an oxygen absorption reaction such as water. In short, it is only necessary to have a large surface area in contact with each other. The oxygen-absorbing composition is constituted by mixing at least three kinds of these units.

  The metallic aluminum unit contained in the oxygen-absorbing composition is a main component of oxygen absorption, and is oxidized by contact with oxygen molecules, and consequently plays a role of absorbing oxygen gas. The metal aluminum may be one in which an oxide film is not formed on the surface, but one in which a thin oxide film naturally occurs on the surface by touching oxygen in the air during production may be used as it is. Moreover, since impurities such as other metals contained in the metal aluminum tend to hinder oxygen absorption, it is preferable that the aluminum purity is high. Desirably, it is 95 mass% or more, More desirably, it is 99 mass% or more.

  The form of the metal aluminum unit is not particularly limited, but a form having a wide surface area for the mass is desirable, and for example, a foil form, a fiber form, a particulate form, a fine particle form, a powder form, and the like are desirable. Moreover, the aggregated thing which particle | grains, powder, etc. gathered may be used. In order to increase the oxygen absorption rate, a form with a wide surface area per gram of metallic aluminum is desirable, but from the viewpoint of stably maintaining oxygen absorption over a certain period, a volume portion that does not appear directly on the surface should be secured. Is desirable. Taking into consideration the ease of production, it is desirable to form fine particles. Specifically, the average particle diameter of the aluminum particles is preferably 0.1 μm or more and 1000 μm or less, and more preferably 1 μm or more and 300 μm or less. Particularly preferably, it is 3 μm or more and 100 μm or less.

  When the metallic aluminum unit is in the form of particles, fine particles, powders, etc., the shape of each metallic aluminum particle may be spherical, teardrop-shaped, flake-shaped, needle-shaped, or indefinite. What is necessary is just to select suitably in consideration of speed, duration, the amount of aluminum used, ease of manufacture, etc.

  Such a metal aluminum unit can be obtained by various conventional methods such as a normal atomizing method and a crushing method. In addition, for the purpose of further improving the reaction activity, the metal aluminum unit may be pretreated with an acid, an alkali, a surface treatment agent, or the like, but may not be performed.

  The metal aluminum unit can be almost completely oxidized not only on the surface but also inside the metal aluminum by oxygen absorption in the presence of an aluminum compound (and moisture) described later. Therefore, even if the initial metallic aluminum unit is a spherical particle having a certain average particle diameter, after sufficient oxygen absorption, almost the whole changes to an aggregate of aluminum oxide powders similar to iron red rust. This aggregate is easy to collapse and it is difficult to keep the original shape. Therefore, it is possible to cause oxidation to a point close to the theoretical value (upper limit value) of oxygen absorption calculated from the aluminum equivalent, and the oxygen absorption ability is greatly improved.

  The cause of such an unexpected phenomenon is unknown, but the surface oxide film of the metal aluminum unit is destroyed by the action of the coexisting aluminum compound unit and the formation of a new film is not inhibited. I guess.

  Next, the aluminum compound unit of the oxygen-absorbing composition will be described. As described above, the aluminum compound unit is an oxidation accelerator for the metal aluminum unit, and has an action of oxidizing the metal aluminum unit not only to the surface but also to the inside in the presence of moisture. The term “aluminum compound” as used herein means that the mass ratio of the aluminum element to other elements bonded to the aluminum element or the like is in the range of 1: 9 to 8: 2. Within this range, the oxygen-absorbing ability when the oxygen-absorbing composition is obtained increases. More preferably, it is 2: 8-7: 3. More preferably, it is 3: 7-6: 4, Most preferably, it is 3: 7-5.5: 4.5. The oxidation number of aluminum in the aluminum compound may be 1, 2, or 3, but an oxidation number of 3 is preferable.

  Suitable aluminum compounds include aluminum oxides, hydroxides, aluminates, aluminosilicates, sulfates, nitrates, phosphates, halides, acetates, among others, oxides or hydroxides. Things are preferred.

Examples of aluminum oxides or hydroxides include anhydrous aluminum compounds such as α-alumina, γ-alumina, η-alumina, δ-alumina, k-alumina, ρ-alumina, Al (OH) ₃ or Al ₂ O. Trihydrates of aluminum compounds such as gibbsite, pyalite, norstrandite represented by ₃ · 3H ₂ O, boehmite, diasbore, etc. represented by AlO (OH) or Al ₂ O ₃ · H ₂ O Monohydrates of aluminum compounds, and simple substances such as todite (5Al ₂ O _a · H ₂ O), alumina gel (Al ₂ O ₃ · nH ₂ O), and mixtures containing one or more of these are fisted. .

  In order to increase the oxygen absorption rate, γ-alumina is preferable among anhydrous oxides, and monohydrate is preferable among hydrates. The aluminum oxide is more preferably a hydrate, and most preferably boehmite.

  Further, the aluminum compound may contain one or more metal elements having a high ionization tendency as elements other than aluminum in order to increase the oxygen absorption rate. Examples of the metal element having a high ionization tendency include potassium, calcium, sodium, magnesium, zinc, chromium, manganese, iron (II) and the like.

  The form of the aluminum compound unit is not particularly limited, but it is preferable that the aluminum compound unit has a large surface area and high dispersibility so that a contact point with the surface of the metal aluminum unit is likely to occur. For example, a fiber shape, a particle shape, a fine particle shape, a powder shape, and the like can be mentioned. Further, as a particle shape, a spherical shape, a needle shape, a flake shape, an indefinite shape, and the like are fisted. The average particle size in the case of the particle shape is preferably 0.01 μm or more and 1000 μm or less, and more preferably 0.05 μm or more and 100 μm or less. Especially preferably, they are 0.1 micrometer or more and 10 micrometers or less.

The aluminum compound unit has a specific surface area of 1 m ² / g or more, more preferably 10 m ² / g or more, in order to ensure contact with the metal aluminum unit. Most preferably, it is 50 m < ² > / g or more.

  The aluminum compound unit preferably has a pH of 3 to 11 when 1 g of the aluminum compound unit is dispersed in 100 cc of water. By selecting the aluminum compound unit whose composition is adjusted so as to exhibit such pH, the hydrogen generation reaction that is a side reaction of the reaction between aluminum and oxygen is suppressed to some extent. More preferably, it is 4-9.

  The aluminum compound unit may be produced according to a conventional method. For example, the aluminum compound unit may be produced by performing a dry or wet chemical reaction and, if necessary, a drying treatment, a firing treatment, a purification treatment, a pulverization treatment, and the like.

  The mass ratio of mixing the metal aluminum unit and the aluminum compound unit can be determined in the range of 1:99 to 99: 1. When the ratio of the metal aluminum unit is large, the amount of oxygen that can be absorbed is large, but on the other hand, the oxygen absorption rate is small, and particularly the absorption rate at the initial stage of absorption is small. The reverse is true when the proportion of aluminum compound units is large. The mass ratio to be mixed may be appropriately determined according to specifications required for the oxygen absorbent while taking into consideration the surface area of the metal aluminum unit and the like. Usually, the mass ratio of the metal aluminum unit to the aluminum compound unit is 30:70. It is preferable to be about ~ 70: 30.

  In addition, the oxidation action to the inside of the metal aluminum unit in the coexistence of the aluminum compound unit and water occurs even if the metal aluminum unit and the aluminum compound unit are lightly mixed with a spoon. Therefore, it is considered that the destruction of the surface oxide film of the metal aluminum unit is not due to the mechanical action during mixing.

  Next, description will be made on at least one additive unit selected from the group consisting of phosphoric acid, citric acid, tartaric acid, and salts thereof (hereinafter sometimes abbreviated as additive unit) of the oxygen-absorbing composition. To do. Although the mechanism of these additive units is unknown, it acts as a suitable inhibitor of hydrogen generation, and effectively suppresses hydrogen generation due to side reactions during the oxidation reaction of the metal aluminum unit. In particular, since the reactivity of the metal aluminum unit is enhanced by the aluminum compound unit, the hydrogen generation suppressing action of the additive unit becomes more important.

  Examples of phosphoric acid include orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid, and any of these may be used, or a mixture thereof may be used. Of these, orthophosphoric acid is preferred. Examples of the phosphate include inorganic salts such as sodium hydrogen salt, sodium salt, lithium hydrogen salt, lithium salt, potassium potassium salt, potassium salt, ammonium salt, ammonium hydrogen salt, calcium salt, and zinc salt. A part of the salt may remain as hydrogen, or plural kinds of inorganic atoms may be mixed. Further, it may be a low molecular weight organic salt. From the viewpoint of solubility in water when used as an additive unit and disposal treatment after use, an inorganic salt is preferable, and a sodium salt or a sodium hydrogen salt is more preferable. Most preferred is monosodium dihydrogen salt of orthophosphoric acid.

  Citric acid may be citric acid itself or a salt. Examples of the citrate include inorganic salts such as sodium salt, lithium salt, potassium salt, ammonium salt, ammonium salt, calcium salt, iron salt, magnesium salt, etc. It may be left as it is, or plural kinds of inorganic atoms may be mixed. Further, it may be a low molecular weight organic salt. From the viewpoint of solubility in water when used as an additive unit and disposal treatment after use, an inorganic salt is preferable, and a sodium salt is more preferable.

  Tartaric acid may be either D-form or L-form, a mixture thereof, or a tartrate salt. Tartrate salts include lithium, sodium, potassium, rubidium, cesium, thallium, copper, silver, magnesium, calcium, strontium, barium, ammonium, zinc, mercury, Boron salts, aluminum salts, tin salts, lead salts, antimony salts, bismuth salts, manganese salts, iron salts, cobalt salts, etc. can be mentioned. Species inorganic atoms may be mixed. Further, it may be a low molecular weight organic salt. From the viewpoints of solubility in water when used as an additive unit and disposal treatment after use, an inorganic salt is preferable, and a sodium salt is more preferable.

  The additive unit may be used by selecting at least one selected from the group consisting of phosphoric acid, citric acid, tartaric acid, and salts thereof, or, if necessary, two or more. Among these, phosphoric acid is preferable from the viewpoint of the effect of suppressing hydrogen generation.

  The additive unit may be added in the form of powder or indefinite shape, but in order to accurately generate the hydrogen generation suppressing effect, it is dissolved or dissolved in water or an organic solvent stoichiometrically required for the oxygen absorption reaction. It is preferable to use in a dispersed manner. When the additive unit is added in the form of an aqueous solution or aqueous dispersion, the amount of the additive unit added is preferably in the range of 1 ppm to 1% by mass with respect to the metal aluminum unit. Within this range, a desirable effect of suppressing hydrogen generation is obtained, and the efficiency of oxygen absorption is also improved. More preferably, they are 10 ppm or more and 5000 ppm or less, More preferably, they are 20 ppm or more and 1000 ppm or less.

  To the oxygen-absorbing composition, a stoichiometrically necessary amount of water for the oxygen-absorbing reaction of the metal aluminum unit may be added in advance according to the use of the oxygen-absorbing composition. As an addition method, water may be added directly as it is, or it may be added while being supported on a water retention agent or a carrier. Further, as described above, the additive unit may be added as an aqueous solution or aqueous dispersion in which the additive unit is dissolved or dispersed. In that case, an aqueous solution is preferable from the viewpoint of storage stability.

  When adding water directly, in order to avoid non-uniformity such as aggregation of specific components, first, after dispersing any component, for example, aluminum compound unit in water, the dispersion is thoroughly stirred. However, a method such as adding a metal aluminum unit may be taken.

  A water retention agent is a known thickening agent or gelling agent that is hydrophilic and can hold hydration more than its own weight to form a sol or gel. For example, a synthetic polymer such as polyacrylate or carrageenan A polysaccharide etc. can be mentioned and it does not restrict | limit in particular.

  Carriers include fiber products with water retention properties such as absorbent cotton and nonwoven fabric, and inorganic powders such as activated carbon, zeolite, diatomaceous earth, activated clay, silica, talc, gypsum, calcium silicate, calcium chloride, graphite, carbon black, and carbon nanotubes Or an inorganic granular material is mentioned, It does not restrict | limit in particular. One type of water retention agent or carrier may be used, or two or more types may be used in combination.

  It should be noted that moisture is not necessarily added to the oxygen-absorbing composition, moisture separated from a packaged product such as a food packaged together with the oxygen-absorbing composition, and air remaining in the bag when packaging the packaging bag The oxygen absorption reaction may be carried out by using the water vapor inside or water vapor that permeates the packaging bag after packaging and enters the bag. In this case, it is preferable to use a larger amount of the additive unit than when it is added as an aqueous solution or the like.

  As long as the effects of the present invention are not impaired, an oxygen-absorbing composition may be added with a microwave spark inhibitor and other additives.

  The oxygen-absorbing composition can be obtained by mixing the above-described components at a predetermined ratio, and stirring and homogenizing. For homogenization, the metal aluminum unit, the aluminum compound unit, and the like may be stirred while being simultaneously pulverized. The mixing and homogenizing treatment is desirably performed in an oxygen-free atmosphere using an inert gas such as nitrogen gas or argon gas, carbon dioxide gas, or the like. Carbon dioxide is particularly preferable from the viewpoint of oxygen absorption performance.

As is known, the oxygen-absorbing composition can be enclosed in an oxygen-permeable paper sachet as it is, and can be enclosed in a package as an oxygen absorbent. Since the oxygen-absorbing composition has a relatively high oxygen-absorbing capacity, it can perform a necessary oxygen-absorbing function in a small amount. Therefore, it is suitable for processing and using other forms of oxygen absorbents. For example, it may be mixed with a binder at the time of paper production, or may be kneaded at the time of production of resin pellets or resin sheets using an oxygen permeable resin. In addition, a layer of an oxygen-absorbing composition processed with a binder can be sandwiched between paper and a resin sheet to form a multilayered sheet or film, and further processed into a tray or lid of a package. Good. In this case, an oxygen-permeable sheet or film is used for at least the inner surface portion of the package. It is desirable to use a sheet or film on the outer surface of the package that is less permeable to oxygen. It is optional to make the sheet or film moisture permeable or moisture impermeable as required.
[Example]

EXAMPLES Hereinafter, although an Example etc. are given and this invention is demonstrated further in detail, this invention is not limited to the specific aspect of the following Example. Measurement methods and evaluation methods for various physical properties in Examples and the like are as follows.
(1) Oxygen absorption (V _OS ) and hydrogen generation (V _HG )

  Under a room temperature (23 ° C.) environment, a storage sealed container having an initial capacity of 1000 cc (the body and lid are made of PMMA (acrylic), the lid packing is made of silicon, and the volume of the container is variable so that the container internal pressure is constant) was prepared . A predetermined amount of the oxygen-absorbing composition was sealed in the container under atmospheric pressure, and then left in a 23 ° C. atmosphere for 3 hours. The oxygen gas concentration and the hydrogen gas concentration in the container were measured before the introduction of the oxygen-absorbing composition and after 3 hours from the introduction.

  The oxygen concentration was measured with an oxygen monitor (trade name: JKO-O2LJD II, manufactured by Jiko Co., Ltd.). The hydrogen concentration was measured with an air / dissolved hydrogen measuring device (Able Co., Ltd., trade name: DM-10B2). Subsequently, the oxygen absorption amount at the time point of 3 hours was calculated by the following formula (a).

V _OS = {(C _O2,0 / 100) × V ₀ − (C _{O2, t} / 100) × V _t } / x (a)
(In the formula (a), V _OS is the amount of oxygen absorbed per gram of metallic aluminum (cc / g) from the start of measurement until 3 hours have passed, and C _{O2, t} is the oxygen concentration in the container (vol. %), C _O2,0 is the oxygen concentration in the container (vol.%) Before _charging the oxygen-absorbing composition, V ₀ is the initial volume of the container (= 1000 cc), and V _t is the volume of the storage container after 3 hours. (Cc) and x mean the weight (g) of metallic aluminum contained per gram of the oxygen-absorbing composition.

The obtained oxygen absorption (V _OS ) was evaluated according to the following criteria.
・ Oxygen absorption amount is 110% or more as compared with the case where the unit of additive is not included (reference example) (indicated by symbol “」 ”).
-Compared with the case where the unit of additive is not included (reference example), the oxygen absorption amount is in the range of 70% or more and less than 110%, which is good (indicated by symbol “◯”).
-Oxygen absorption amount is less than 70% compared to the case where the unit of additive is not included (reference example) ... inferior (indicated by symbol "x").

Further, the hydrogen generation amount (V _HG ) after 3 hours from the start of measurement was calculated by the following formula (b).
V _HG = (C _{H2, t} / 100) × V _t (b)
(In formula (b), V _HG is the amount of hydrogen generated per gram of metallic aluminum (cc / g) from the start of measurement until 3 hours have passed (measurement time), and C _{H2, t} is the hydrogen in the container when 3 hours have passed. concentration (vol.%), V _t denotes the volume at 3 hours after the storage container (cc), respectively.)

The obtained hydrogen generation amount (V _HG ) was evaluated according to the following criteria.
-Compared to the case where the unit of additive is not included (reference example), the amount of hydrogen generation is less than 30%, which is excellent (indicated by symbol “◎”).
-Compared with the case where the unit of additive is not included (reference example), the hydrogen generation amount is 30% or more and less than 50%, which is good (indicated by the symbol “◯”).
-Compared to the case where the unit of additive is not included (reference example), the amount of hydrogen generation is reduced, but 50% or more is insufficient (indicated by symbol “Δ”).
(2) Dispersion pH

After 1 g of aluminum compound unit is immersed in 100 cc of water and dispersed by stirring well with a glass rod, the pH of this dispersion is measured with a pH meter (manufactured by Shindengen Industrial Co., Ltd., trade name: Shindengen ISFET pH meter KS723). Measured using.
[Standard example]

Aluminum powder 0.5g (made by Eka Granular Japan Co., Ltd., grade name 8F02A, particle size 8μm, purity 99.7%) as metal aluminum unit and boehmite powder 1.0g (made by Daimei Chemical Co., Ltd.) as aluminum compound unit , Grade name AE-001, particle size 0.2 μm, purity 99.9%, dispersion pH 8.7) and 1.5 g of pure water are mixed and stirred with a spoon to prepare a uniform reference sample. Created. Using this, the oxygen absorption amount (V _OS ) and the hydrogen generation amount (V _HG ) were measured and used as the criteria for the evaluation of the examples.

Instead of 1.5 g of pure water, NaH ₂ PO ₄ powder (manufactured by Wako Pure Chemical Industries, Ltd., having a purity of 99% or more) is added as an additive unit so that the concentration becomes 1 × 10 ⁻⁵ mol / l. A sample of the oxygen-absorbing composition was prepared in the same manner as in the reference example except that 1.5 g of an aqueous solution dissolved in water was used. The additive amount of the additive unit relative to the metallic aluminum unit was 3.6 ppm. Using this, the oxygen absorption amount (V _OS ) and the hydrogen generation amount (V _HG ) were measured and evaluated. The results are shown in Table 1. The oxygen absorption evaluation was good and the hydrogen suppression effect was excellent.

A sample of the oxygen-absorbing composition was obtained in the same manner as in Example 1 except that the concentration of the dissolved NaH ₂ PO ₄ powder was 1 × 10 ⁻⁴ mol / l. The additive amount of the additive unit relative to the metal aluminum unit was 36 ppm. Using this, the oxygen absorption amount and the hydrogen generation amount were evaluated in the same manner as in Example 1. The results are shown in Table 1. The oxygen absorption evaluation was good and the hydrogen generation suppression evaluation was excellent.

A sample was obtained in the same manner as in Example 1 except that the concentration in which NaH ₂ PO ₄ was dissolved was 5 × 10 ⁻⁴ mol / l. The additive amount of the additive unit relative to the metal aluminum unit was 180 ppm. Using this, the oxygen absorption amount and the hydrogen generation amount were evaluated in the same manner as in Example 1. The results are shown in Table 1. Both the oxygen absorption evaluation and the hydrogen generation suppression evaluation were excellent.

A sample was obtained in the same manner as in Example 1 except that the concentration in which NaH ₂ PO ₄ was dissolved was 1 × 10 ⁻³ mol / l. The additive amount of the additive unit relative to the metallic aluminum unit was 360 ppm. Using this, the oxygen absorption amount and the hydrogen generation amount were evaluated in the same manner as in Example 1. The results are shown in Table 1. The oxygen absorption evaluation was good and the hydrogen generation suppression evaluation was excellent.

Sodium citrate (made by Wako Pure Chemical Industries, Ltd., having a purity of 99% or more) was used as an additive, except that sodium citrate powder was dissolved in pure water so as to have a concentration of 1 × 10 ⁻³ mol / l. Were obtained in the same manner as in Example 1. The additive amount of the additive unit relative to the metal aluminum unit was 774 ppm. Using this, the oxygen absorption amount and the hydrogen generation amount were evaluated in the same manner as in Example 1. The results are shown in Table 1. The oxygen absorption evaluation was excellent, and the hydrogen generation suppression evaluation was good.

A sample was obtained in the same manner as in Example 5 except that the concentration in which the sodium citrate powder was dissolved was 1 × 10 ⁻⁴ mol / l. The additive amount of the additive unit relative to the metal aluminum unit was 77 ppm. Using this, the oxygen absorption amount and the hydrogen generation amount were evaluated in the same manner as in Example 1. The results are shown in Table 1. Both the oxygen absorption evaluation and the hydrogen generation suppression evaluation were good.

Except for using sodium tartrate (made by Wako Pure Chemical Industries, Ltd., having a purity of 99% or more) as an additive and dissolving sodium tartrate powder in pure water to a concentration of 1 × 10 ⁻³ mol / l, A sample was obtained in the same manner as in Example 1. The additive amount of the additive unit relative to the metallic aluminum unit was 582 ppm. Using this, the oxygen absorption amount and the hydrogen generation amount were evaluated in the same manner as in Example 1. The results are shown in Table 1. Both the oxygen absorption evaluation and the hydrogen generation suppression evaluation were good.

Claims (7)

  An oxygen absorptivity characterized by containing a metallic aluminum unit, an aluminum compound unit, and a unit of at least one additive selected from the group consisting of phosphoric acid, citric acid, tartaric acid, and salts thereof Composition.   The oxygen-absorbing composition according to claim 2, wherein the property of the unit of the additive is an aqueous solution.   The oxygen-absorbing composition according to claim 2, wherein the additive amount of the additive unit relative to the metal aluminum unit is 1 ppm or more and 1 mass% or less.   The oxygen-absorbing composition according to any one of claims 1 to 3, wherein the aluminum compound is an aluminum oxide.   The oxygen-absorbing composition according to claim 4, wherein the aluminum oxide is γ-alumina.   The oxygen-absorbing composition according to claim 4 or 5, wherein the aluminum oxide is boehmite. An oxygen absorbent comprising the oxygen-absorbing composition according to any one of claims 1 to 6 so as to be permeable to oxygen.