Deoxygenation agent composition, method for producing same, and deoxygenation agent package

Abstract

A deoxygenation agent composition which contains an iron powder, an activated carbon, water, a halide of an alkaline earth metal, and an alkaline substance, wherein: the content of the activated carbon is 20 parts by mass to 40 parts by mass relative to 100 parts by mass of the content of the iron powder; the content of the water is 230 parts by mass to 370 parts by mass relative to 100 parts by mass of the content of the activated carbon; and the content of the halide of an alkaline earth metal is 50 parts by mass to 65 parts by mass relative to 100 parts by mass of the content of the water.

Description

Oxygen absorber composition, its manufacturing method, and oxygen absorber package

[0001] The present invention relates to an oxygen absorber composition, a method for producing the same, and an oxygen absorber package.

[0002] Oxygen absorbers that utilize the oxidation reaction of iron powder (hereinafter referred to as iron-based oxygen absorbers) have been proposed. Commercially available oxygen absorbers (for example, trade name "AGELESS" manufactured by Mitsubishi Gas Chemical Co., Inc.) are already widely used to preserve the quality and freshness of foods, pharmaceuticals, and other items by sealing them in gas-barrier containers and removing oxygen from the containers.

[0003] Iron-based oxygen absorbers are classified into "moisture-dependent" oxygen absorbers that start absorbing oxygen by utilizing moisture evaporated from the preserved material, etc., and "self-reacting" oxygen absorbers that already contain the moisture necessary for the oxygen absorption reaction of iron in the oxygen absorber composition. In the "self-reacting" oxygen absorber, by adding a moisture-donating agent such as a moisture-impregnated inorganic filler to the oxygen absorber composition, the moisture necessary for the oxygen absorption reaction of iron can be supplied from the moisture-donating agent to the iron.

[0004] However, since self-reacting oxygen absorbers contain moisture in advance, when they are used to preserve objects such as dried foods and medicines that have a lower moisture content (in other words, a lower water activity) than self-reacting oxygen absorbers, moisture migrates from the oxygen absorber composition to the object, causing a change in the moisture content of the object. Furthermore, when moisture migrates to the object, moisture necessary for the oxygen absorption reaction of iron is lost from the oxygen absorber composition, resulting in a decrease in oxygen absorption performance.

[0005] Such moisture transfer from the oxygen absorber composition to the preserved object tends to occur more easily as the difference in water activity between the preserved object and the oxygen absorber composition increases. Therefore, efforts have been made to obtain an oxygen absorber composition with a water activity close to that of the preserved object.

[0006] For example, Patent Document 1 proposes an oxygen absorbing composition containing iron powder, calcium chloride, water, and a water-retaining carrier, in which the contents of water and calcium chloride are controlled within predetermined ranges.

[0007] The oxygen absorbing composition proposed in Patent Document 1 solves the problem of moisture migration to stored items with relatively low water activity, while exhibiting excellent oxygen absorbing performance even in a low humidity atmosphere.

[0008] Patent No. 6690201

[0009] On the other hand, oxygen absorbing compositions exhibiting a relatively low water activity (so-called medium water activity) tend to have inferior oxygen absorption performance compared to oxygen absorbing compositions with a high water activity, and therefore require the use of large amounts of iron powder and water to increase the amount of oxygen absorbed. However, if large amounts of iron powder and water are used, the amount of hydrogen generated by the reaction during oxygen absorption increases, causing deformation or rupture of the container. Therefore, there is a demand for medium water activity oxygen absorbing compositions that can absorb large amounts of oxygen while suppressing the amount of hydrogen generated.

[0010] Therefore, an object of the present invention is to provide an oxygen absorbing composition that exhibits a medium water activity, has excellent oxygen absorbing performance, and generates a small amount of hydrogen, a method for producing the same, and an oxygen absorbing package.

[0011] That is, the gist of the present invention is as follows: [1] An oxygen scavenger composition comprising iron powder, activated carbon, water, an alkaline earth metal halide, and an alkaline substance, wherein the content of the activated carbon is 20 to 40 parts by mass per 100 parts by mass of the iron powder, the content of the water is 230 to 370 parts by mass per 100 parts by mass of the activated carbon, and the content of the alkaline earth metal halide is 50 to 65 parts by mass per 100 parts by mass of the water. [2] The oxygen scavenger composition according to [1] above, wherein the alkaline earth metal halide is one or more selected from the group consisting of calcium chloride, magnesium chloride, magnesium bromide, and calcium bromide. [3] The oxygen scavenger composition according to [1] or [2] above, wherein the alkaline substance is one or more selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, and salts of weak acids and strong bases. [4] The oxygen absorbing composition according to any one of [1] to [3] above, wherein the alkaline substance is calcium hydroxide. [5] The oxygen absorbing composition according to any one of [1] to [4] above, further comprising a swelling agent. [6] The oxygen absorbing composition according to [5] above, wherein the swelling agent is one or more selected from the group consisting of calcium carboxymethylcellulose, sodium carboxymethylcellulose, calcium bentonite, and sodium bentonite. [7] The oxygen absorbing composition according to [5] or [6] above, wherein the content of the swelling agent is 3 to 20 parts by mass per 100 parts by mass of the water. [8] The oxygen absorbing composition according to any one of [1] to [7] above, wherein the oxygen absorbing composition is in the form of a granule. [9] The oxygen absorbing composition according to any one of [1] to [8] above, wherein the water activity of the oxygen absorbing composition is 0.40 to 0.60.

[10] A method for producing the oxygen absorbing composition according to any one of the above [1] to [9], comprising a step of mixing iron powder, activated carbon, water, an alkaline earth metal halide, and an alkaline substance.

[11] An oxygen absorber package comprising the oxygen absorber composition according to any one of the above [1] to [9] and a breathable packaging material containing the oxygen absorber composition.

[0012] According to the present invention, it is possible to provide an oxygen absorbing composition that exhibits a medium water activity, has excellent oxygen absorbing performance, and generates a small amount of hydrogen, a method for producing the same, and an oxygen absorbing package.

[0013] The oxygen absorber composition, its manufacturing method, and oxygen absorber package according to the present invention will be described in detail below. In this specification, the term "A to B" used to describe numerical values ​​means "A or more and B or less" (when A<B) or "A or less and B or more" (when A>B). In the present invention, a combination of preferred embodiments is a more preferred embodiment.

[0014] [Oxygen Absorber Composition] The oxygen absorber composition of the present invention comprises iron powder, activated carbon, water, an alkaline earth metal halide, and an alkaline substance, wherein the content of the activated carbon is from 20 parts by mass to 40 parts by mass per 100 parts by mass of the iron powder, the content of the water is from 230 parts by mass to 370 parts by mass per 100 parts by mass of the activated carbon, and the content of the alkaline earth metal halide is from 50 parts by mass to 65 parts by mass per 100 parts by mass of the water.

[0015] The oxygen absorbing composition of the present invention has the above-mentioned constitution, and therefore exhibits a medium water activity, can exhibit excellent oxygen absorption performance, and can also suppress hydrogen generation. In this specification, "medium water activity" means that the water activity is in the range of "0.4 or more and 0.6 or less." The reason why the oxygen absorbing composition of the present invention exhibits the above-mentioned effects is not clear, but the following reason is thought to be one of the reasons.

[0016] Conventionally, the moisture donor contained in a self-reacting oxygen absorber composition has been an inorganic filler such as silica or diatomaceous earth, which serves as a water-retaining carrier and supports water on the water-retaining carrier. In contrast, the present invention is characterized by the selective use of activated carbon as the water-retaining carrier. Because activated carbon also functions as a reaction accelerator for the iron oxygen absorption reaction, it is believed that the resulting oxygen absorber composition has improved oxygen absorption performance compared to conventionally used water-retaining carriers such as silica. Furthermore, activated carbon tends to have a higher water absorption capacity (water retention capacity) per unit mass than silica, etc., and is therefore believed to be able to provide sufficient moisture to iron even with a reduced amount of moisture donor compared to when silica, etc. is used, thereby improving oxygen absorption performance. For these reasons, it is believed that using activated carbon as the water-retaining carrier can increase the oxygen absorption capacity per unit mass of the oxygen absorber composition (bulk powder). The oxygen absorber composition of the present invention is also characterized by the inclusion of an alkaline substance. The inclusion of an alkaline substance can maintain the iron surface (particularly the moisture present on the surface) alkaline. As a result, it is believed that the hydrogen ion concentration in the reaction water can be reduced on the surface of the iron during the oxygen absorption reaction, and that the generation of hydrogen due to the reduction of hydrogen ions by iron can be effectively suppressed. Furthermore, it is believed that the oxygen scavenger composition of the present invention can achieve both the effect of improving oxygen absorption performance and the effect of suppressing hydrogen generation while exhibiting a medium water activity, particularly by controlling the blending amounts of activated carbon, water, and alkaline earth metal halide to a predetermined ratio.

[0017] Each component will be described below. (Iron Powder) The oxygen absorbing composition of the present invention contains iron powder. The iron powder in the oxygen absorbing composition of the present invention is a main agent for the oxygen scavenging reaction.

[0018] The iron powder is not particularly limited, but is preferably one with an exposed surface of iron (zero-valent metallic iron), and may have an extremely thin oxide film like a normal metal surface, as long as it does not impair the effects of the present invention. Specifically, reduced iron powder, electrolytic iron powder, atomized iron powder, etc. can be suitably used. Crushed or cut cast iron or the like can also be used. One type of iron powder can be used alone, or two or more types can be used in combination as needed. These iron powders are also readily available commercially and can be used.

[0019] The average particle size (D50) of the iron powder is, for example, 3000 μm or less, preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 300 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, and even more preferably 20 μm or more. Specifically, the average particle size (D50) of the iron powder is preferably 1 to 1000 μm, more preferably 10 to 500 μm, and even more preferably 20 to 300 μm. Iron powder having an average particle size within the above range can be obtained by appropriately selecting commercially available iron powder. It can also be obtained, for example, by classification using a sieve according to the desired average particle size. The average particle size of the iron powder can be measured by the method described in the Examples.

[0020] In addition, the specific surface area of ​​the 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 0.50 m ２ / g or less, more preferably 0.20m ２ Specifically, the specific surface area of ​​the iron powder is preferably 0.03 to 0.50 m ２ / g, more preferably 0.05 to 0.20 m ２ The specific surface area of ​​the iron powder can be measured by the method described in the Examples.

[0021] The content of iron powder is not particularly limited, but is preferably 15% by mass or more and 75% by mass or less, more preferably 20% by mass or more and 60% by mass or less, and even more preferably 25% by mass or more and 50% by mass or less, in the oxygen absorbing composition.

[0022] (Activated Carbon) The oxygen absorbing composition of the present invention contains activated carbon, which functions as a reaction accelerator and a water-retaining carrier.

[0023] The activated carbon is not particularly limited, and the raw material may be wood, coconut shell, coal, or the like. However, from the viewpoint of using the oxygen scavenger composition of the present invention for food, one or more types selected from wood and coconut shell are preferred. The properties of the activated carbon are also not particularly limited, but from the viewpoint of ease of handling during the production of the oxygen scavenger composition, activated carbon in a granular or powder form with high fluidity is preferably used, and activated carbon with a shape close to spherical is more preferred. One type of activated carbon can be used alone, or two or more types can be used in combination as needed. These activated carbons are readily available commercially and can also be used.

[0024] Furthermore, in terms of ease of handling during the production of the oxygen scavenger composition, the average particle size of the activated carbon in powder form is preferably 0.1 μm or more and 1000 μm or less, more preferably 1 μm or more and 100 μm or less, and even more preferably 1 μm or more and 50 μm or less. As long as the activated carbon particles have a particle size within the above range, they can be used regardless of whether they are primary particles, agglomerated particles, or granulated particles. Activated carbon having a particle size within the above range can be used alone, or multiple types having different particle sizes can be mixed in any ratio. Such activated carbon is readily available commercially and can also be used. The average particle size of activated carbon can be measured by the method described in the Examples.

[0025] The content of activated carbon is 20 parts by mass or more and 40 parts by mass or less, preferably 20 parts by mass or more and 30 parts by mass or less, more preferably 20 parts by mass or more and 25 parts by mass or less, and even more preferably 20 parts by mass or more and 23 parts by mass or less, relative to 100 parts by mass of the iron powder. By setting the content within the above range, an oxygen scavenger composition can be obtained that exhibits medium water activity, has excellent oxygen absorption performance, and generates a small amount of hydrogen. On the other hand, if the content of activated carbon is too low, the oxygen scavenger composition cannot sufficiently retain moisture, and becomes a slurry, or the function as a reaction accelerator is not fully exhibited, and the oxygen absorption performance tends to be reduced.

[0026] (Water) The oxygen scavenger composition of the present invention contains water. Water contained in the oxygen scavenger composition of the present invention is a component necessary for promoting the oxygen scavenging reaction.

[0027] The water content is 230 to 370 parts by mass, preferably 250 to 370 parts by mass, more preferably 270 to 370 parts by mass, even more preferably 300 to 370 parts by mass, and still more preferably 300 to 350 parts by mass, per 100 parts by mass of the activated carbon. By adjusting the water content to within the above range, an oxygen scavenger composition can be obtained that exhibits medium water activity, has excellent oxygen absorption performance, and generates a small amount of hydrogen. On the other hand, if the water content is too high, the oxygen absorption performance tends to decrease significantly and the amount of hydrogen generated tends to increase.

[0028] (Alkaline earth metal halide) The oxygen absorbing composition of the present invention contains an alkaline earth metal halide. The alkaline earth metal halide in the oxygen absorbing composition of the present invention is a substance that acts catalytically on the oxidation reaction of iron powder and improves the activity of the iron powder. In addition, the alkaline earth metal halide plays a role in preventing water contained in the oxygen absorbing composition from evaporating and being lost from the oxygen absorbing composition, and exhibits the effect of suppressing moisture transfer to the stored item.

[0029] In order for iron to absorb oxygen, it is necessary to attract moisture to the surface of the iron, and this is achieved by utilizing the deliquescence phenomenon of metal salts. Alkaline earth metal halides are metal salts that exhibit deliquescence, but compared to alkali metal halides, they have a higher solubility in water and can easily reduce their water activity, making them effective when preparing an oxygen scavenger composition (bulk powder) with a medium water activity. The alkaline earth metal halides are preferably contained in the oxygen scavenger composition as an aqueous solution dissolved in water.

[0030] The alkaline earth metal halide is not particularly limited, and examples thereof include alkaline earth metal chlorides, bromides, and iodides, and is preferably at least one selected from the group consisting of alkaline earth metal chlorides and bromides. Among them, from the viewpoints of handleability and safety, the alkaline earth metal halide is preferably at least one selected from the group consisting of calcium chloride, magnesium chloride, magnesium bromide, and calcium bromide, more preferably at least one selected from the group consisting of calcium chloride and magnesium chloride, and even more preferably calcium chloride. The alkaline earth metal halide can be used alone, or two or more types can be used in combination as needed. In addition, the alkaline earth metal halides described above are readily available commercially and can also be used.

[0031] The content of the alkaline earth metal halide is 50 parts by mass or more and 65 parts by mass or less, preferably 52 parts by mass or more and 62 parts by mass or less, and more preferably 52 parts by mass or more and 56 parts by mass or less, per 100 parts by mass of water. By setting the content within the above range, an oxygen scavenger composition can be obtained that exhibits medium water activity, has excellent oxygen absorption performance, and generates a small amount of hydrogen. On the other hand, if the content of the alkaline earth metal halide is too high, the oxygen absorption performance tends to decrease.

[0032] (Alkaline substance) The oxygen absorbing composition of the present invention contains an alkaline substance. The alkaline substance in the oxygen absorbing composition of the present invention plays a role in keeping the surface of iron (particularly the water present on the surface) alkaline. This is thought to reduce the hydrogen ion concentration in the reaction water on the surface of iron during the oxygen absorption reaction, and effectively suppress the generation of hydrogen due to the reduction of hydrogen ions by iron.

[0033] The alkaline substance is not particularly limited, but is preferably at least one selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, and salts of weak acids and strong bases, more preferably at least one selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides, and even more preferably an alkaline earth metal hydroxide.

[0034] Examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide, with sodium hydroxide being preferred. Examples of alkaline earth metal hydroxides include calcium hydroxide and magnesium hydroxide, with calcium hydroxide being preferred. Examples of salts formed from weak acids and strong bases include phosphates, citrates, carbonates, and bicarbonates, with phosphates and citrates being preferred. Specific examples of salts formed from weak acids and strong bases include trisodium phosphate, trisodium citrate, sodium bicarbonate, and sodium carbonate, with trisodium phosphate and trisodium citrate being preferred. One alkaline substance can be used alone, or two or more alkaline substances can be used in combination as needed. These alkaline substances are readily available commercially and can also be used.

[0035] It is generally known that the oxidation rate of iron is affected by pH, and tends to decrease in a high pH range. Therefore, from the viewpoint of maintaining high oxygen absorption performance, it is more preferable to use calcium hydroxide (slaked lime) as the alkaline substance, which has appropriate solubility and can also function as a pH adjuster.

[0036] The content of the alkaline substance is not particularly limited, but is preferably 0.2 parts by mass to 10 parts by mass, more preferably 0.3 parts by mass to 5 parts by mass, and even more preferably 0.5 parts by mass to 3 parts by mass, relative to 100 parts by mass of the iron powder. By setting the content within the above range, an oxygen absorbing agent composition can be obtained that exhibits a medium water activity, has excellent oxygen absorption performance, and generates a small amount of hydrogen.

[0037] (Swelling Agent) The oxygen absorbing composition of the present invention preferably further contains a swelling agent. The swelling agent in the oxygen absorbing composition of the present invention is a substance that swells with water and has a caking function for maintaining the oxygen absorbing composition in a granular form. The swelling agent is preferably used in a substantially dry state or in a semi-swollen or swollen state after absorbing a small amount to a necessary amount of water.

[0038] The swelling agent is not particularly limited as long as it is a commonly known swelling agent, and known swelling agents, binding agents, adhesives, and binders used in foods, etc. can be used. Inorganic swelling agents include bentonites such as calcium bentonite and sodium bentonite; and clay minerals such as sodium montmorillonite. Organic swelling agents include organic bentonite; natural products such as defatted frozen tofu, agar, starch, dextrin, gum arabic, gelatin, and casein; cellulose-based semi-synthetic products such as crystalline cellulose, carboxymethylcellulose, sodium carboxymethylcellulose, calcium carboxymethylcellulose, and hydroxyethylcellulose; semi-synthetic products such as lignosulfonic acid and hydroxyethylated starch; and synthetic products such as water-insolubilized polyvinyl alcohol and polyvinyl methyl ether. Among these, the swelling agent is preferably one or more selected from the group consisting of clay minerals and cellulose-based semi-synthetic products. Clay minerals are preferred because they are inexpensive and have excellent performance. Clay minerals are also known as inorganic soaps and function as lubricants. Clay minerals that swell with water are known to exhibit high thixotropy and are also preferred because they exhibit caking properties. Cellulose-based semi-synthetic products are also preferred because they exhibit excellent swelling properties.

[0039] In particular, from the viewpoints of low cost, strong caking power, and excellent handling properties, the swelling agent is preferably one or more selected from the group consisting of carboxymethylcellulose calcium, carboxymethylcellulose sodium, calcium bentonite, and sodium bentonite, and even more preferably one or more selected from the group consisting of calcium bentonite and sodium bentonite. The swelling agents described above can be used alone, or two or more can be used in combination as needed. Furthermore, commercially available products may be used as these swelling agents.

[0040] The average particle size of the swelling agent is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, from the viewpoint of suppressing dust generation and of the binding function. The average particle size of the swelling agent can be measured by the method described in the Examples.

[0041] The content of the swelling agent is preferably 3 parts by mass or more and 20 parts by mass or less, more preferably 5 parts by mass or more and 15 parts by mass or less, even more preferably 5 parts by mass or more and 12 parts by mass or less, and still more preferably 5 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the water content. By setting the content within the above range, an oxygen absorbing composition can be obtained which exhibits medium water activity, has excellent oxygen absorption performance, and generates a small amount of hydrogen.

[0042] (Other Components) In addition to the above components, the oxygen absorbing composition of the present invention may contain other components as needed, such as a water-retaining carrier other than activated carbon, a flowability improver, a catalyst, an odor adsorbent, a heat dispersant, etc.

[0043] The water-retaining carrier other than activated carbon is not particularly limited as long as it can retain water, and commonly available porous materials and superabsorbent resins can be used. Examples of porous materials include diatomaceous earth, zeolite, sepiolite, cristobalite, porous glass, silica, activated clay, acid clay, vermiculite, and wood flour. Examples of superabsorbent resins include polyacrylate resins, polysulfonate resins, polyacrylamide resins, polyvinyl alcohol resins, starch resins, cellulose resins, and polyalginic acid resins.

[0044] However, in the present invention, since activated carbon functions as a water retention carrier, it is not necessary to use a water retention carrier other than activated carbon, but it can be used within a range that does not impair the effects of the present invention. From the viewpoint of increasing the proportion of activated carbon in the water retention carrier, the content of the water retention carrier other than activated carbon is preferably 5 parts by mass or less, more preferably 1 part by mass or less, per 100 parts by mass of iron powder, and it is even more preferable that the water retention carrier other than activated carbon is substantially not contained, i.e., 0 part by mass.

[0045] <Shape of oxygen absorber composition> The shape of the oxygen absorber composition of the present invention is not particularly limited, but is preferably granular. Here, the granular material may be an aggregated particle or a granulated material. Furthermore, examples of the particle shape include a spherical shape, an approximately spherical shape, an elliptical shape, and a cylindrical shape. Since they tend to have better packing properties and a higher bulk density, spherical and approximately spherical shapes are preferred, and spherical shapes are more preferred.

[0046] The average particle size of the oxygen absorber composition of the present invention is not particularly limited, but is preferably 0.3 mm or more and 5.0 mm or less, more preferably 0.5 mm or more and 2.0 mm or less. When the average particle size is 0.3 mm or more, adhesion to the powder / granular material contact portion of the packaging machine during filling and packaging due to static electricity or the like is suppressed. When the average particle size is 5.0 mm or less, the gaps between particles can be suppressed from becoming too large, thereby suppressing a decrease in the oxygen absorption amount per unit volume. To obtain an oxygen absorber composition having an average particle size within the above range, for example, sieving can be performed using sieves with openings of 0.3 mm and 5.0 mm. The average particle size of the oxygen absorber composition can be measured by the method described in the Examples.

[0047] <Characteristics of Oxygen Absorber Composition> The oxygen absorber composition of the present invention preferably exhibits a medium water activity. The closer the water activity value is to 1, the closer the water vapor pressure of water evaporating from the oxygen absorber composition is to the water vapor pressure of pure water. The water activity of the oxygen absorber composition of the present invention is preferably 0.40 or more and 0.60 or less, more preferably 0.42 or more and 0.55 or less, and even more preferably 0.42 or more and 0.53 or less, which is considered to be a so-called medium water activity. The method for measuring the water activity is not particularly limited, and the measurement can be performed using a known device such as a dew-point water activity measuring instrument, but specifically, the measurement can be performed by the method described in the examples.

[0048] Generally, when an item is stored in a sealed state, the greater the difference in water activity between the stored item and the oxygen absorber composition, the more likely moisture migration occurs. Therefore, from the viewpoint of suppressing moisture migration, it is preferable that the water activity of the oxygen absorber composition is similar to that of the stored item. The oxygen absorber composition of the present invention has a medium water activity and is therefore suitable for use in preserving stored items with a medium water activity.

[0049] Examples of preserved items suitable for the oxygen scavenger composition of the present invention include foods such as rice, miscellaneous grains, spices, dried bonito flakes, small dried fish, and seaweed; industrial products such as electronic components with soldered joints, metal screws, and metal blades such as razors; pharmaceuticals such as tablets, herbal medicines, and active pharmaceutical ingredients that may be subject to hydrolysis; and various other items. In particular, the composition is suitable for preserving pharmaceuticals.

[0050] [Method for producing oxygen scavenger composition] The method for producing the oxygen scavenger composition of the present invention is not particularly limited, but preferably includes a step of mixing iron powder, activated carbon, water, an alkaline earth metal halide, and an alkaline substance. According to such a production method, the iron powder, activated carbon, water, an alkaline earth metal halide, and an alkaline substance are mixed until they are uniformly dispersed to prepare a granular material, and the oxygen scavenger composition can be efficiently prepared.

[0051] The mixing step may be (1) a step of mixing all components at once, (2) a step of preparing an aqueous solution of an alkaline earth metal halide in water, and adding the aqueous solution to a uniform mixture of iron powder, activated carbon, an alkaline substance, and optionally a swelling agent and other components, and mixing the solution, or (3) a step of preparing an aqueous solution of an alkaline earth metal halide and an alkaline substance in water, and adding the aqueous solution to a uniform mixture of iron powder, activated carbon, and optionally a swelling agent and other components, and mixing the solution. From the viewpoint of obtaining a more homogeneous oxygen scavenger composition, the above steps (2) or (3) are preferred. Furthermore, in the case of step (3), the alkaline earth metal halide and the alkaline substance may react in the aqueous solution, which may change the concentration of the alkaline earth metal halide. Therefore, the above step (2) is more preferred from the viewpoint of adding and mixing the alkaline earth metal halide in an aqueous solution prepared to a desired concentration with the iron powder, etc.

[0052] The mixing method is not particularly limited, and can be performed by shaking mixing, mixing with a mixer, etc. Specific examples of the mixer include a Nauta mixer (manufactured by Hosokawa Micron Corporation), a conical mixer (manufactured by Ohno Chemical Machinery Co., Ltd.), a vertical granulator (manufactured by Powrex Corporation), a high-speed mixer (manufactured by Earth Technica Corporation), and a granulator (manufactured by Akira Kiko Co., Ltd.).

[0053] Since iron, the main component of the oxygen scavenger, reacts with oxygen, the reaction with oxygen proceeds gradually even in the absence of water or alkaline earth metal halides. Therefore, mixing is performed in an inert atmosphere (in the case of a substantially closed system, the system is usually filled with an oxygen-free inert gas (e.g., N ２ ) atmosphere) and it is preferable to take appropriate measures to remove heat.

[0054] [Oxygen Absorber Package] The oxygen absorber package of the present invention comprises the oxygen absorber composition described above and a breathable packaging material containing the oxygen absorber composition.

[0055] (Packaging material) Examples of packaging materials include a bag-shaped material made by bonding two sheets of breathable packaging material together, a bag-shaped material made by bonding one sheet of breathable packaging material and one sheet of non-breathable packaging material together, and a bag-shaped material made by folding one sheet of breathable packaging material and sealing the edges together except for the folded part.

[0056] Here, when the breathable packaging material and the non-breathable packaging material are rectangular, the packaging material may be formed by overlapping two sheets of breathable packaging material and heat-sealing the four sides to form a bag, by overlapping one sheet of breathable packaging material with one sheet of non-breathable packaging material and heat-sealing the four sides to form a bag, or 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 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.

[0057] (Breathable Packaging Material) As the breathable packaging material, a packaging material that allows oxygen and carbon dioxide to pass through is selected. Among them, those having an air resistance measured by the Oken Tester Method of preferably 40,000 seconds or less, more preferably 30,000 seconds or less, even more preferably 20,000 seconds or less, even more preferably 10,000 seconds or less, and preferably 500 seconds or more, more preferably 1,000 seconds or more are preferably used. Here, the air resistance refers to a value measured by the method of JIS P8117 (1998). More specifically, it can be measured by the method described in the Examples.

[0058] 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.

[0059] 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.

[0060] The thickness of the laminated film is preferably 30 μm to 300 μm, more preferably 40 μm to 250 μm, in which case the film can be a packaging material that maintains strength and has excellent heat-sealing properties and packaging suitability, compared to thicknesses outside the above range.

[0061] (Uses of Oxygen Absorber Package) The oxygen absorber package of the present invention contains the oxygen absorber composition of the present invention, and therefore exhibits a medium water activity, has excellent oxygen absorption performance, and generates a small amount of hydrogen. Therefore, it is suitable for use in preserving preserved items exhibiting a medium water activity. Specifically, it is suitable for use in a method for deoxygenating the space inside a gas barrier container containing a preserved item exhibiting a medium water activity, using the oxygen absorber package of the present invention. Such a method can suppress moisture transfer from the oxygen absorber package to the preserved item, and can also efficiently deoxygenate the space inside the gas barrier container, thereby maintaining the quality of the preserved item in good condition.

[0062] Furthermore, when the oxygen absorber package of the present invention is used, it is preferable that the package comprises the oxygen absorber package, a preserved object, and a gas barrier container for accommodating them. In this case, the humidity in the space inside the gas barrier container is preferably 40% RH or more and 60% RH or less from the viewpoint of maintaining the quality of the preserved object. Furthermore, the preserved object is preferably one or more selected from food, industrial products, and pharmaceuticals, more preferably pharmaceuticals.

[0063] 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.

[0064] 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.

[0065] <Materials> The materials used in the examples and comparative examples are as follows: Calcium chloride (CaCl ２ ): Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent Iron powder: average particle diameter 100 μm, specific surface area 0.104 m ２ / g [Measurement of average particle size of iron powder] The average particle size of the iron powder was measured by using a standard sieve conforming to ISO 3310-1:2000 (equivalent to JIS Z8801-1:2006) and vibrating it for 5 minutes, and measuring the average particle size (D50) at a cumulative frequency of 50% from the weight fraction of the sieve opening size. [Specific surface area of ​​iron powder] The specific surface area (unit: m ２ / g) was measured based on the BET multipoint method in accordance with JIS Z8830:2013. Activated carbon: "Shirasagi A" manufactured by Osaka Gas Chemicals Co., Ltd., powder form, average particle diameter 10 μm [Average particle diameter of activated carbon] The average particle diameter of the activated carbon was measured as the average particle diameter (D50) at a cumulative frequency of 50% in the volume-based particle size distribution using a laser diffraction / scattering particle size distribution measuring device ("LA-960" manufactured by Horiba, Ltd.). Calcium hydroxide (Ca(OH) ２ :Manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., special grade reagent Bentonite: calcium bentonite, "Neokunibond" manufactured by Kunimine Industries, Ltd., average particle size 32.7 μm [Average particle size of swelling agent] The average particle size of the swelling agent (bentonite) was measured as the average particle size (D50) at 50% cumulative frequency in the volume-based particle size distribution using a laser diffraction / scattering particle size distribution measuring device ("LA-960" manufactured by Horiba, Ltd.). Silica: precipitated wet silica, "CARPLEX (registered trademark) #67" manufactured by EVONIC. Breathable packaging material A: bag-shaped with outer dimensions of 40 mm x 30 mm. Breathable packaging material A is a bag-shaped material composed of linear low-density polyethylene (perforated film, thickness 30 μm, hereinafter simply referred to as "LLDPE") / wooden paper (basis weight 50 g / m ２A multilayer sheet (thickness 52 μm, air resistance 5300 seconds) consisting of LLDPE (perforated film, thickness 12 μm, hereinafter referred to as "PET") / polyethylene terephthalate (perforated film, thickness 12 μm, hereinafter referred to as "PET") was folded so that the LLDPE was on the inside, and three sides were heat-sealed with a seal width of 5 mm so that one side was an opening. [Air resistance of multilayer sheet] The air resistance of the multilayer sheet was measured three times using a digital Oken air permeability tester ("EG02" manufactured by Asahi Seiko Co., Ltd.). The arithmetic mean value of the obtained results was used as the measurement result. - Breathable packaging material B: bag-shaped with outer dimensions of 100 mm x 70 mm Breathable packaging material B was a bag-shaped sheet consisting of LLDPE (same as above) / wooden paper (basis weight 50 g / m ２ A multilayer sheet (thickness: 39 μm, air resistance: 10 seconds (measurement method: same as above)) having the above structure was folded so that the LLDPE was on the inside, and three sides were heat-sealed with a seal width of 5 mm so that one side would be an opening.

[0066] <Preparation of oxygen absorber composition and oxygen absorber package using the same> (Example 1) [1] Preparation of oxygen absorber composition First, calcium chloride (CaCl ) as an alkaline earth metal halide was added. ２ 8.4 g of calcium chloride was dissolved in 14.8 g of water to prepare an aqueous calcium chloride solution. Next, 20.0 g of iron powder, 4.0 g of activated carbon, and calcium hydroxide (Ca(OH) ２ ) and 1.5 g of bentonite as a swelling agent were placed in a 300 ml plastic container and mixed by shaking to obtain a mixture. Subsequently, a calcium chloride aqueous solution prepared in advance was added to the mixture, and the mixture was further mixed by shaking to obtain an oxygen absorbing agent composition. The obtained oxygen absorbing agent composition was a granular material in which powdery particles were aggregated (average particle diameter 1.60 mm). [Average Particle Diameter of Oxygen Absorber Composition] The average particle diameter of the oxygen absorbing agent composition was measured as the average particle diameter (D50) at 50% cumulative frequency in the volume-based particle size distribution using a laser diffraction / scattering particle size distribution analyzer ("LA-960" manufactured by Horiba, Ltd.).

[0067] [2] Preparation of oxygen absorber package [2-1] Preparation of oxygen absorber package A (sample for measuring oxygen absorption amount) 0.8 g of the oxygen absorber composition prepared in [1] above was filled into breathable packaging material A, and the opening was heat-sealed with a seal width of 5 mm to produce a bag-shaped oxygen absorber package A. The produced oxygen absorber package A was placed in a gas barrier bag with low oxygen permeability (manufactured by Fukusuke Kogyo Co., Ltd., laminated with barrier nylon and LLDPE), the opening was heat-sealed, and stored so as not to react with oxygen in the atmosphere until it was used to measure the oxygen absorption amount.

[0068] [2-2] Preparation of oxygen absorber package B (sample for measuring hydrogen generation amount) 25 g of the oxygen absorber composition prepared in [1] above was filled into breathable packaging material B, and the opening was heat-sealed with a seal width of 5 mm to prepare a bag-shaped oxygen absorber package B. The prepared oxygen absorber package B was placed in a gas barrier bag with low oxygen permeability (manufactured by Fukusuke Kogyo Co., Ltd., laminated with barrier nylon and LLDPE), the opening was heat-sealed, and stored to prevent reaction with oxygen in the atmosphere until it was used to measure the amount of hydrogen generation.

[0069] (Examples 2 to 16 and Comparative Examples 4 and 5) In Examples 2 to 16 and Comparative Examples 4 and 5, oxygen absorber compositions and oxygen absorber packages A and B were prepared in the same manner as in Example 1, except that the amounts of each component were changed to the values ​​shown in Table 1.

[0070] (Comparative Examples 1 to 3) In Comparative Examples 1 to 3, oxygen absorber compositions were prepared in the same manner as in Example 1, except that the blending amounts of each component were changed to the values ​​shown in Table 1. However, the obtained oxygen absorber compositions contained a small amount of activated carbon and were unable to retain water, resulting in a slurry state, and therefore oxygen absorber packages A and B were not prepared.

[0071] (Comparative Example 6) In Comparative Example 6, oxygen absorber packages A and B were prepared in the same manner as in Example 1, except that the oxygen absorber composition was prepared by the following method [1'] instead of the method [1] above. [1'] Preparation of oxygen absorber composition Calcium chloride (CaCl ) was used as the alkaline earth metal halide. ２) was dissolved in 16.5 g of water to prepare a calcium chloride aqueous solution. Next, 10.0 g of silica as a water-retaining carrier was placed in a 300 ml plastic container, and the calcium chloride aqueous solution was added and mixed to obtain a moisture-donating agent. Next, 50.0 g of iron powder was mixed with the moisture-donating agent, and 1.0 g of activated carbon was added, and the mixture was shaken and mixed in the plastic container to obtain an oxygen scavenger composition. The obtained oxygen scavenger composition was a granular product consisting of agglomerated powder particles (average particle diameter 0.12 mm, measurement method same as above).

[0072] (Comparative Example 7) In Comparative Example 7, an oxygen absorber composition and oxygen absorber packages A and B were prepared in the same manner as in Comparative Example 6, except that the blending amounts of each component were changed to the values ​​shown in Table 1.

[0073] <Evaluation> The oxygen absorber compositions and oxygen absorber packages A and B prepared in Examples 1 to 16 and Comparative Examples 4 to 7 were evaluated as follows. The results are shown in Table 1.

[0074] (Water Activity) The water activity was measured using the oxygen scavenger composition prepared in [1] above by the following method. First, 1.0 g of the oxygen scavenger composition was placed in a special dish, and the measurement was performed at 25°C using a water activity measuring device ("AquaLab TDL 2" manufactured by METER) according to the procedure specified for the device. The measurement was performed three times, and the arithmetic mean value of the obtained results was evaluated as the water activity value of the oxygen scavenger composition of each Example or Comparative Example. In this Example, a water activity of 0.40 to 0.60 (medium water activity) was defined as good, and a value closer to the median value of 0.50 was evaluated as even better. The water activity values ​​in Table 1 were rounded to two decimal places for evaluation.

[0075] (Oxygen absorption amount) The oxygen absorption amount was measured using the oxygen absorber package A prepared in the above [2-1] by the following method. First, one oxygen absorber package A was placed in a gas barrier bag made of nylon / polyethylene laminate film (manufactured by Fukusuke Kogyo Co., Ltd., dimensions: 250 mm × 400 mm, oxygen permeability: 7.3 ml / m²) together with 1500 ml of air at 25°C. ２1000ml / day·atm) and the opening was heat-sealed to seal. Furthermore, the oxygen concentration in the gas barrier bag at this time (initial oxygen concentration) was measured. Then, the gas barrier bag was quickly placed in a thermostatic chamber at 25°C and held for 72 hours, after which the oxygen concentration in the gas barrier bag (oxygen concentration after storage) was measured and the oxygen absorption amount (initial oxygen concentration - oxygen concentration after storage) was calculated. Furthermore, the calculated oxygen absorption amount was divided by the mass (unit: g) of the oxygen scavenger composition to calculate the oxygen absorption amount per unit mass of the oxygen scavenger composition (bulk powder) (unit: ml / 1 g of bulk powder). The oxygen concentration was measured using a gas analyzer ("Check Mate 3" manufactured by MOCON Corporation). The measurement was performed by inserting a hollow needle at the tip of a sampling silicone tube attached to a gas analyzer into the bag through a sampling rubber sheet (25 mm x 25 mm, 2 mm thick) previously attached to the gas barrier bag, and measuring the oxygen concentration inside the gas barrier bag. The above measurement was performed three times, and the arithmetic mean value of the obtained results was evaluated as the oxygen absorption amount of the oxygen absorber composition of each Example or Comparative Example. The larger the oxygen absorption amount, the better the oxygen absorption performance. In this Example, an oxygen absorber composition (bulk powder) with an oxygen absorption amount per unit mass of 85.0 [ml / 1 g of bulk powder] or more was evaluated as good.

[0076] (Amount of hydrogen generated) The amount of hydrogen generated was measured using the oxygen absorber package B prepared in [2-2] above by the following method. First, one oxygen absorber package B was placed in a gas barrier bag made of nylon / aluminum foil / polyethylene laminate film (manufactured by Meiwa Packs Co., Ltd., dimensions 175 mm × 250 mm, oxygen permeability 0.1 ml / m²) together with 25 ml of air at 35°C. ２The gas barrier bag was placed in a constant pressure (3500 kJ / day, atm or less) and the opening was heat-sealed to seal it. The gas barrier bag was then promptly placed in a thermostatic chamber at 35°C and maintained for 72 hours. The hydrogen concentration in the gas barrier bag was measured by gas chromatography, and the amount of hydrogen generated (unit: ml) was calculated. The calculated amount of hydrogen generated was then divided by the mass of the oxygen absorber composition (unit: g) to calculate the amount of hydrogen generated per unit mass of the oxygen absorber composition (bulk powder) (unit: ml / 1 g of bulk powder). The hydrogen concentration was measured using a gas chromatograph ("GC-14A" manufactured by Shimadzu Corporation). The above measurement was performed three times, and the arithmetic mean value of the obtained results was evaluated as the amount of hydrogen generated for the oxygen absorber composition of each Example or Comparative Example. A lower amount of hydrogen generated indicates more effectively suppressed hydrogen generation. In this example, an oxygen absorber composition (bulk powder) with an amount of hydrogen generated per unit mass of 0.100 [ml / 1 g of bulk powder] or less was evaluated as good.

[0077] (Amount of hydrogen generated per 100 ml of oxygen absorption) Using the oxygen absorption amount per 1 g of oxygen absorber composition calculated by the above method and the amount of hydrogen generated per 1 g of oxygen absorber composition, the amount of hydrogen generated per 100 ml of oxygen absorption (unit: ml / 100 ml of oxygen absorption), which is the amount of hydrogen generated when 100 ml of oxygen is absorbed, was calculated. The smaller the amount of hydrogen generated per 100 ml of oxygen absorption, the less hydrogen is generated relative to the amount of oxygen absorption required for actual use, and the better. In this example, a hydrogen generation amount per 100 ml of oxygen absorption of 0.050 [ml / 100 ml of oxygen absorption] or less was evaluated as good.

[0078]

[0079] As shown in Table 1, it was confirmed that oxygen scavenger compositions containing iron powder, activated carbon, water, alkaline earth metal halide, and alkaline substance, and having predetermined contents of iron powder, activated carbon, water, and alkaline earth metal halide, exhibited medium water activity, had excellent oxygen absorption performance, and generated a small amount of hydrogen (Examples 1 to 16).

[0080] On the other hand, when the content of activated carbon relative to iron powder is less than the predetermined ratio, the activated carbon, which functions as a water-retaining carrier, cannot retain all the water, resulting in a slurry state due to the excess water, making it impossible to prepare an oxygen absorber package (Comparative Examples 1 to 3). Furthermore, even if the content of activated carbon relative to iron powder is appropriate, when the content of water relative to activated carbon is greater than the predetermined ratio, the amount of oxygen absorbed is reduced (Comparative Examples 4 and 5). Furthermore, when silica is used instead of activated carbon, the silica functions as a water-retaining carrier and can retain water, so that a granular oxygen absorber composition can be obtained, but the amount of oxygen absorbed is low and the amount of hydrogen generated is large (Comparative Examples 6 and 7).

Claims

1. A deoxidizer composition containing iron powder, activated carbon, water, a halide of an alkaline earth metal, and an alkaline substance, wherein the content of the activated carbon is 20 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the content of the iron powder, the content of the water is 230 parts by mass or more and 370 parts by mass or less with respect to 100 parts by mass of the content of the activated carbon, and the content of the halide of the alkaline earth metal is 50 parts by mass or more and 65 parts by mass or less with respect to 100 parts by mass of the content of the water.

2. The deoxidizer composition according to claim 1, wherein the halide of the alkaline earth metal is at least one selected from the group consisting of calcium chloride, magnesium chloride, magnesium bromide, and calcium bromide.

3. The deoxidizer composition according to claim 1 or 2, wherein the alkaline substance is at least one selected from the group consisting of hydroxides of alkali metals, hydroxides of alkaline earth metals, and salts composed of weak acids and strong bases.

4. The deoxidizer composition according to claim 1 or 2, wherein the alkaline substance is calcium hydroxide.

5. The deoxidizer composition according to claim 1 or 2, further comprising a swelling agent.

6. The deoxidizer composition according to claim 5, wherein the swelling agent is at least one selected from the group consisting of calcium carboxymethyl cellulose, sodium carboxymethyl cellulose, calcium bentonite, and sodium bentonite.

7. The deoxidizer composition according to claim 5, wherein the content of the swelling agent is 3 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the content of the water.

8. The deoxidizer composition according to claim 1 or 2, wherein the deoxidizer composition is in granular form.

9. The deoxidizer composition according to claim 1 or 2, wherein the water activity of the deoxidizer composition is 0.40 or more and 0.60 or less.

10. A method for producing the deoxidizer composition according to claim 1 or 2, comprising a step of mixing iron powder, activated carbon, water, a halide of an alkaline earth metal, and an alkaline substance.

11. A deoxidizer package comprising the deoxidizer composition according to claim 1 or 2 and a breathable packaging material containing the deoxidizer composition.