Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B2/00—Preservation of foods or foodstuffs, in general
  • A23B2/70—Preservation of foods or foodstuffs, in general by treatment with chemicals
  • A23B2/704—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
  • A23B2/708—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
  • A23B2/712—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O in which an absorbent is placed or used
  • A23B2/717—Oxygen absorbent
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B2/00—Preservation of foods or foodstuffs, in general
  • A23B2/70—Preservation of foods or foodstuffs, in general by treatment with chemicals
  • A23B2/725—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of liquids or solids
  • A23B2/729—Organic compounds; Microorganisms; Enzymes
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B2/00—Preservation of foods or foodstuffs, in general
  • A23B2/70—Preservation of foods or foodstuffs, in general by treatment with chemicals
  • A23B2/725—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of liquids or solids
  • A23B2/788—Inorganic compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
  • B01J20/041—Oxides or hydroxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
  • B01J20/043—Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
  • B01J20/045—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium containing sulfur, e.g. sulfates, thiosulfates, gypsum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
  • B01J20/046—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium containing halogens, e.g. halides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
  • B01J20/048—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium containing phosphorus, e.g. phosphates, apatites, hydroxyapatites
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
  • B01J20/28004—Sorbent size or size distribution, e.g. particle size
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
  • B01J20/2805—Sorbents inside a permeable or porous casing, e.g. inside a container, bag or membrane
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/10—Inorganic adsorbents
  • B01D2253/102—Carbon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/10—Inorganic adsorbents
  • B01D2253/112—Metals or metal compounds not provided for in B01D2253/104 or B01D2253/106
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/10—Single element gases other than halogens
  • B01D2257/104—Oxygen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2259/00—Type of treatment
  • B01D2259/45—Gas separation or purification devices adapted for specific applications
  • B01D2259/4525—Gas separation or purification devices adapted for specific applications for storage and dispensing systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2220/00—Aspects relating to sorbent materials
  • B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
  • B01J2220/42—Materials comprising a mixture of inorganic materials

Definitions

• the present invention relates to oxygen absorber powder.
• a method using oxygen scavengers is known as a preservation technology for foods and pharmaceuticals.
• an article to be stored and an oxygen scavenger are sealed in a gas-barrier sealed container, so that the oxygen in the sealed container is absorbed by the oxygen scavenger, and the atmosphere in the sealed container is substantially reduced.
• As a function of the oxygen scavenger it is required to be small and to absorb a large amount of oxygen. In other words, there is a need for an oxygen scavenger composition with a high oxygen absorption capacity per unit volume.
• Typical oxygen absorbers include iron-based oxygen absorbers based on iron (iron powder) and non-ferrous oxygen absorbers based on ascorbic acid, glycerin, etc.
• the oxygen scavenger is appropriately selected depending on the application, but iron-based oxygen scavengers are widely used from the viewpoint of oxygen absorption performance.
• Patent Document 1 describes iron powder, metal bromide and/or metal iodide for the purpose of improving economy and oxygen absorption and suppressing rusting under high humidity. and thiosulfate are disclosed.
• the oxygen scavenger reacts with oxygen in the atmosphere and generates heat when a product consisting of a container enclosing an article to be stored and the oxygen scavenger is opened.
• most moisture-dependent oxygen scavengers are composed mostly of iron powder, and tend to generate heat at a high temperature.
• the oxygen absorber packaging material is composed of a non-breathable laminate film on one side and a polyethylene nonwoven fabric on one side, as described in the method for producing an oxygen absorber package in Patent Document 1.
• the heat generation temperature tends to be particularly high because the packaging material has high air permeability and low heat insulation. Therefore, an oxygen absorber capable of suppressing heat generation has been required.
• the problem to be solved by the present invention is to provide an oxygen absorber powder that has excellent oxygen absorption performance and that can suppress heat generation when the product is unsealed.
• the present invention relates to the following ⁇ 1> to ⁇ 11>.
• ⁇ 1> Contains iron powder, a metal halide, and an alkaline agent, the solubility of the alkaline agent in 100 g of water at 25°C is less than 0.1 g, and the aqueous dispersion of the alkaline agent has a pH of 8 at 25°C.
• ⁇ 12 oxygen absorber powder.
• ⁇ 2> The oxygen absorber powder according to ⁇ 1>, wherein the oxygen absorber powder further contains activated carbon.
• ⁇ 3> The oxygen absorber powder according to ⁇ 1> or ⁇ 2> above, wherein the content of the alkaline agent is 0.1 to 20 parts by mass with respect to 100 parts by mass of the iron powder.
• ⁇ 4> The oxygen absorber powder according to ⁇ 2> or ⁇ 3> above, wherein the content of the activated carbon is 0.01 to 5 parts by mass with respect to 100 parts by mass of the iron powder.
• ⁇ 5> The oxygen absorber powder according to any one of ⁇ 1> to ⁇ 4> above, wherein the aqueous dispersion of the alkaline agent has a pH of 9.5 to 11.5 at 25°C.
• the magnesium oxide is at least one selected from the group consisting of heavy burnt magnesium oxide and electrofused magnesium oxide.
• the metal halide is at least one selected from the group consisting of alkali metal chlorides, alkali metal bromides, alkaline earth metal chlorides, and alkaline earth metal bromides.
• the oxygen absorber powder according to any one of ⁇ 7> ⁇ 9> The content of the metal halide is 0.01 to 5 parts by mass with respect to 100 parts by mass of the iron powder.
• the oxygen absorber powder according to any one of ⁇ 1> to ⁇ 8> ⁇ 10> The above ⁇ 1> to ⁇ , wherein the alkaline agent is particles, and the particles have an average particle size of 3 to 50 ⁇ m.
• 9> The oxygen absorber powder according to any one of items 9>.
• An oxygen absorber package comprising: the oxygen absorber powder according to any one of ⁇ 1> to ⁇ 10>above; and a breathable packaging material containing the oxygen absorber powder.
• the present invention provides oxygen absorber powder and an oxygen absorber package which generate less heat when a container containing an article to be stored and an oxygen absorber is opened, and has excellent oxygen absorption performance. be.
• the oxygen absorber powder of the present invention contains iron powder, a metal halide, and an alkali agent, the solubility of the alkali agent in 100 g of water at 25° C. is less than 0.1 g, and the aqueous dispersion of the alkali agent has a pH of 8-12 at 25°C.
• the oxygen absorber powder of the present invention has the effect of suppressing heat generation when opening a container in which the oxygen absorber powder is enclosed and having excellent oxygen absorption performance.
• Such oxygen scavenger powder of the present invention can be applied to oxygen scavengers containing iron as a main component, and is particularly suitable for water-dependent oxygen scavengers.
• iron powder The iron powder contained in the oxygen absorber powder of the present invention is not particularly limited as long as the iron surface is exposed, and reduced iron powder, electrolytic iron powder, atomized iron powder, etc. are preferably used. can be done. Pulverized products and cut products such as cast iron can also be used. One type of iron powder can be used alone, and two or more types can be used in combination as necessary. Moreover, these iron powders can also be easily obtained as commercial products.
• the average particle size of the iron powder is preferably 1000 ⁇ m or less, more preferably 500 ⁇ m or less, even more preferably 200 ⁇ m or less, still more preferably 100 ⁇ m or less, from the viewpoint of improving contact with oxygen. From the viewpoint of suppressing the generation of .
• the average particle size of the iron powder is the D50 median size.
• a specific measuring method includes the method described in Examples.
• the specific surface area of the iron powder is preferably 0.01 m 2 /g or more, more preferably 0.03 m 2 /g or more, from the viewpoint of oxygen absorption capacity.
• the specific surface area of iron powder can be measured by the BET multipoint method.
• the oxygen absorber powder of the present invention contains iron powder as a main ingredient.
• the content of the iron powder in the oxygen absorber powder is preferably 40% by mass or more and 99% by mass or less, more preferably 80% by mass or more and 98% by mass or less, and still more preferably. is 90% by mass or more and 97% by mass or less.
• the metal halide contained in the oxygen scavenger powder of the present invention is a substance that acts catalytically on the oxidation reaction of iron and improves the activity of iron.
• the metal halide also plays a role of retaining moisture absorbed by or in contact with the oxygen absorber powder in the oxygen absorber powder.
• the metal in the metal halide is not particularly limited, but includes, for example, at least one selected from the group consisting of alkali metals, alkaline earth metals, copper, zinc, aluminum, tin, iron, cobalt and nickel. Among them, at least one selected from the group consisting of lithium, potassium, sodium, magnesium, calcium, barium and iron is more preferable.
• Halides in metal halides are not particularly limited, but include, for example, chlorides, bromides, and iodides. Among these, the metal halide is preferably at least one selected from the group consisting of alkali metal chlorides, alkali metal bromides, alkaline earth metal chlorides, and alkaline earth metal bromides. .
• the metal halide is preferably at least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, sodium bromide, calcium iodide, and sodium iodide. At least one selected from the group consisting of calcium chloride, sodium chloride, calcium bromide, and sodium bromide is more preferred from the viewpoint of handling, safety, etc., and at least one selected from the group consisting of calcium chloride and sodium chloride is further preferred. preferable.
• One of the metal halides can be used alone, or two or more thereof can be used in combination, if necessary. In addition, commercial products can be used for these metal halides.
• the content of the metal halide in the oxygen absorber powder is not particularly limited, it is preferably 0.005% by mass or more and 5% by mass or less, more preferably 0.025% by mass or more and 2% by mass in the oxygen absorber powder. %, more preferably 0.05% by mass or more and 1% by mass or less, and even more preferably 0.1% by mass or more and 1% by mass or less. Also, it is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 2 parts by mass, and still more preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the iron powder.
• the oxygen absorber powder of the present invention contains an alkaline agent.
• the alkaline agent contained in the oxygen scavenger powder of the present invention is considered to contribute to suppression of heat generation of the oxygen scavenger, particularly when opening a container containing the scavenger powder.
• the alkali agent exhibits alkalinity in the liquid properties of water when it is made into an aqueous dispersion, and the pH of the aqueous dispersion of the alkali agent at 25° C. is 8 to 12, preferably 9 to 12, More preferably 9.5 to 11.5, still more preferably 10.0 to 11.5.
• the pH of the aqueous dispersion of the alkaline agent is the pH of the supernatant when the concentration of the alkaline agent is equal to or higher than the saturation solubility at 25° C. Specifically, it is measured by the method described in the Examples.
• the solubility of the alkaline agent in 100 g of water at 25° C. is less than 0.1 g.
• the reason why the effects of the present invention are exhibited by using an alkali agent having a solubility in 100 g of water at 25° C. of less than 0.1 g (hereinafter sometimes referred to as a poorly water-soluble alkali agent) is as follows. It is inferred that It is generally known that the oxidation rate of iron powder is affected by pH, and the oxidation rate of iron decreases in a high pH range.
• the oxygen absorber powder of the present invention by containing iron powder and a poorly water-soluble alkaline agent, when the oxygen absorber is enclosed in a packaging container together with an object to be preserved, oxidation by the iron powder progresses at the start of use, It can quickly absorb oxygen in the packaging container and deoxygenate it. After that, over time, the slightly water-soluble alkaline agent reacts with the moisture in the packaging container and gradually dissolves in water, changing the surface of the iron powder to a high pH state and lowering the oxidation activity of iron. .
• Alkaline agents can be used alone, or can be used in combination of two or more if necessary. Commercially available products can be used as these alkaline agents.
• the solubility of the alkaline agent in 100 g of water at 25° C. is less than 0.1 g, preferably less than 0.01 g. Although there is no lower limit, it is preferably 0.1 mg or more.
• the solubility of the alkaline agent in 100 g of water at 25° C. is a substance-specific value, and the value described in the (M)SDS of each substance can be referred to. If there is no (M)SDS value, It can also be measured by the temperature change method (Part 2) or the evaporation method.
• the alkaline agent is not limited, but is preferably at least one selected from the group consisting of magnesium oxide, magnesium hydroxide, basic magnesium carbonate, barium sulfate, and trimagnesium phosphate, and more preferably oxidizing At least one selected from the group consisting of magnesium, magnesium hydroxide, and basic magnesium carbonate, more preferably at least one selected from the group consisting of magnesium oxide and magnesium hydroxide, and still more preferably oxidation Magnesium.
• Alkaline agents can be used alone, or can be used in combination of two or more if necessary. Commercially available products can be used as these alkaline agents.
• the magnesium oxide is preferably at least one selected from the group consisting of heavy-burnt magnesium oxide and electrofused magnesium oxide.
• Heavy calcined magnesium oxide is magnesium oxide that has been calcined at a high temperature.
• electrofused magnesium oxide is especially preferred. The reason for this is that it has less adverse effect on the deoxidizing time than other alkaline agents, and deoxidizes quickly.
• electro-fused magnesium oxide is heavier than general magnesium oxide and mixes well with iron powder. It is also excellent in terms of handleability because it is small.
• the alkali agent contained in the oxygen absorber powder of the present invention is preferably in the form of particles, and the average particle size of the alkali agent particles contained in the oxygen absorber powder of the present invention is preferably 0.1 to 100 ⁇ m. , more preferably 0.5 to 70 ⁇ m, still more preferably 3 to 50 ⁇ m.
• the average particle size of the alkaline agent particles is the D50 median size.
• a specific measuring method includes the method described in Examples.
• the content of the alkaline agent in the oxygen absorber powder is not particularly limited, it is preferably 0.05% by mass or more and 20% by mass or less, and more preferably 0.25% by mass or more and 10% by mass, in the oxygen absorber powder. % by mass or less, more preferably 0.5% by mass or more and 8% by mass or less, and even more preferably 2.5% by mass or more and 8% by mass or less. Also, the amount is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and still more preferably 1.0 to 10 parts by mass with respect to 100 parts by mass of the iron powder. When the content of the alkaline agent is within the above range, the heat generated when the product is unsealed can be efficiently suppressed while maintaining the oxygen absorption performance of the iron powder.
• the oxygen absorber powder of the present invention preferably further contains activated carbon depending on the required performance.
• Activated carbon has the function of retaining water, promoting the oxidation reaction of iron powder, and adsorbing odors.
• the type of activated carbon is not particularly limited, and may be wood, coconut shell, coal, or the like.
• the properties of the activated carbon are not particularly limited, but from the viewpoint of ease of handling during production of the oxygen absorber, a powdery one having high fluidity is preferably used.
• the average particle size of the activated carbon is preferably 1 ⁇ m or more and 1000 ⁇ m or less, more preferably 3 ⁇ m or more and 200 ⁇ m or less, and still more preferably 10 ⁇ m or more and 60 ⁇ m or less, from the viewpoint of handleability during production of the oxygen absorber powder. is.
• the particles of activated carbon can be used regardless of whether they are primary particles, agglomerated particles, or granules, as long as they have a particle size within the above range.
• Activated carbon having a particle size within the above range can be used singly, or a plurality of types having different particle sizes can be mixed in an arbitrary ratio and used.
• the average particle size of activated carbon is the D50 median size.
• a specific measuring method includes the method described in Examples.
• the content of activated carbon in the oxygen absorber powder is not particularly limited, it is preferably 0.005% by mass or more and 5% by mass or less, more preferably 0.025% by mass or more and 2% by mass or less in the oxygen absorber powder. , more preferably 0.05% by mass or more and 1% by mass or less, and even more preferably 0.25% by mass or more and 1% by mass or less. Also, it is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 2 parts by mass, and still more preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the iron powder. When the content of activated carbon is within this range, the oxygen absorber powder retains water, promotes the oxidation reaction, and increases the oxygen absorption amount.
• the oxygen absorber powder of the present invention may optionally contain known additives within a range that does not impair the effects of the present invention.
• additives include silica, alumina, gypsum and the like. One type can be used alone, or two or more types can be used in combination as necessary.
• the oxygen absorber powder of the present invention contains iron powder, a metal halide, and a sparingly water-soluble alkaline agent.
• the average particle size of the oxygen absorber powder of the present invention is preferably 10-200 ⁇ m, more preferably 50-150 ⁇ m. When the average particle size of the oxygen scavenger powder is within the above range, it is possible to suppress the heat generation of the oxygen scavenger when the container containing the scavenger is opened while maintaining high oxygen absorption performance. .
• the oxygen absorber powder of the present invention is preferably used as a moisture-dependent oxygen absorber, and preferably contains substantially no moisture.
• the moisture content of the oxygen absorber powder of the present invention is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 1% by mass or less, and even more preferably 0.5% by mass. % or less.
• the method for producing the oxygen scavenger powder of the present invention is not particularly limited as long as it is a method for obtaining the oxygen scavenger powder described above, but preferred methods include the following methods.
• Method 1 A method in which an aqueous solution of iron powder and a metal halide is mixed, dried, and then mixed with a powdery poorly water-soluble alkaline agent.
• Method 2 Iron powder, a powdery poorly water-soluble alkaline agent, and halogen. In this method, an aqueous solution of metal oxide is mixed and dried.
• Method 1 includes (Method 1-1) a method of mixing an aqueous solution of iron powder, activated carbon and a metal halide, drying the mixture, and then mixing a powdery poorly water-soluble alkaline agent, (Method 1- 2) A method of mixing an aqueous solution of iron powder and a metal halide, drying the mixture, and then mixing activated carbon and a powdery poorly water-soluble alkaline agent.
• Method 2 (Method 2-1) a method of mixing and drying an aqueous solution of iron powder, a powdery poorly water-soluble alkaline agent, activated carbon and a metal halide, (Method 2-2) iron powder and powdery A method of mixing an aqueous solution of a sparingly water-soluble alkaline agent and a metal halide, drying the mixture, and then mixing activated carbon can be used.
• Methods 1 and 2 are preferable because the load of drying during production is small, and Method 1 is more preferable because heat generation can be efficiently suppressed because the surface of the iron powder can be dotted with the alkaline agent.
• the device used for mixing is not particularly limited, for example, a ribbon blender can be used.
• the oxygen absorber package of the present invention comprises the oxygen absorber powder described above and an air-permeable packaging material containing the oxygen absorber powder.
• packaging material As the packaging material, two sheets of air-permeable packaging material are pasted together to form a bag, and one sheet of air-permeable packaging material and one sheet of non-breathable packaging material are pasted together to form a bag-like form, For example, a sheet of air-permeable packaging material is folded, and edges other than the folded portion are sealed to form a bag.
• the packaging material is a bag-shaped material obtained by stacking two air-permeable packaging materials and heat-sealing the four sides of the packaging material.
• a sheet of breathable packaging material and a sheet of non-breathable packaging material are superimposed and heat-sealed on four sides to form a bag.
• the packaging material may be a bag-like material obtained by forming an air-permeable packaging material into a tubular shape and heat-sealing both ends and the body of the tubular body.
• a packaging material that is permeable to oxygen is selected as the breathable packaging material.
• those having an air permeability resistance of 600 seconds or less, more preferably 100 seconds or less, according to the Gurley type tester method are preferably used, but are not limited to the above, and may vary depending on desired product performance.
• a packaging material having a higher air permeability resistance may be used.
• the air resistance means a value measured by the method of JIS P8117 (1998). More specifically, it refers to the time required for 100 mL of air to permeate the air-permeable packaging material using a Gurley densometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.).
• plastic film with air permeability As the air-permeable packaging material, in addition to paper and non-woven fabric, a plastic film with air permeability is used.
• plastic films include films such as polyethylene terephthalate, polyamide, polypropylene, and polycarbonate, and films such as polyethylene, ionomer, polybutadiene, ethylene acrylic acid copolymers, ethylene methacrylic acid copolymers, and ethylene vinyl acetate copolymers as sealing layers.
• a laminated film or the like can be used. These laminates can also be used as breathable packaging materials.
• various methods can be adopted in addition to perforating with cold needles and hot needles.
• the air permeability can be freely adjusted by the diameter, number, material, etc. of the holes to be perforated.
• the thickness of the laminated film is preferably 50 to 300 ⁇ m, particularly preferably 60 to 250 ⁇ m.
• the packaging material can be made to have strength, heat-sealing property, and packaging suitability.
• Example 1 Manufacture of oxygen absorber powder and oxygen absorber package
• iron powder atomized iron powder, average particle size 80 ⁇ m
• magnesium oxide manufactured by Tomita Pharmaceutical Co., Ltd., food additive heavy, average particle size 30.2 ⁇ m, solubility in 100 g of water at 25 ° C.
• Example 2 Poorly water-soluble alkaline agent, electrofused magnesium oxide (manufactured by Tateho Chemical Industry Co., Ltd., "DENMAG", 325 mesh pass, average particle size 20.1 ⁇ m, solubility in 100 g of water at 25 ° C. 8.6 ⁇ 10 -3 g) was carried out in the same manner as in Example 1 except that the oxygen absorber powder and the oxygen absorber package were obtained. The following evaluation was performed using the obtained oxygen absorber package. Table 1 shows the results.
• Example 3 Magnesium hydroxide (manufactured by Naikai Salt Industry Co., Ltd., "Mizu Mag SP", average particle size 5.3 ⁇ m, solubility in 100 g of water at 25 ° C. 3.5 ⁇ 10 -4 g) is used as a poorly water-soluble alkaline additive.
• An oxygen absorber powder and an oxygen absorber package were obtained in the same manner as in Example 1 except that The following evaluation was performed using the obtained oxygen absorber package. Table 1 shows the results.
• Comparative example 1 The main ingredient of the oxygen absorber powder of Example 1 was used as the oxygen absorber powder of Comparative Example 1 without using an alkaline agent. An oxygen absorber package was obtained in the same manner as in Example 1. The following evaluation was performed using the obtained oxygen absorber package. Table 1 shows the results.
• Comparative example 2 Example 1 except that calcium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., calcium hydroxide special grade reagent, average particle size 14.4 ⁇ m, solubility in 100 g of water at 25 ° C. 0.17 g) was used as an alkaline agent. to obtain oxygen absorber powder and oxygen absorber packages. The following evaluation was performed using the obtained oxygen absorber package. Table 1 shows the results.
• calcium hydroxide manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., calcium hydroxide special grade reagent, average particle size 14.4 ⁇ m, solubility in 100 g of water at 25 ° C. 0.17 g
• solubility of alkaline agent in 100 g of water at 25°C As the solubility of the alkaline agent in 100 g of water at 25° C., the value described in the SDS provided by the manufacturer (material supplier) was used. Regarding the magnesium oxide used in Example 1, the SDS provided by the manufacturer did not describe the solubility in water, so the value of electrofused magnesium oxide in Example 2, which is the same magnesium oxide, was used.
• pH of aqueous dispersion of alkaline agent Add 5 g of the alkaline agent shown in Table 1 and 10 g of ion-exchanged water to a 30 mL vial bottle, cover with a lid, mix for 10 minutes with an ultrasonic cleaner, and allow to stand for 10 minutes to remove the aqueous dispersion of the alkaline agent. Obtained.
• the pH of the supernatant liquid of the aqueous dispersion was measured with a pH meter (“LAQUA F-72”, electrode: “9615D-10D”, manufactured by Horiba, Ltd.). The measurement condition was 25°C.
• the average particle size was obtained by measuring the D50 median size using a digital image analysis type particle size distribution analyzer ("CAMSIZER XT", manufactured by Microtrack Lecce).
• the oxygen absorber powder of the present invention generates little heat when the article to be stored and the container containing the oxygen absorber is opened, and has excellent oxygen absorption performance. Therefore, it can be applied to oxygen scavengers containing iron as a main component, and is particularly suitable for water-dependent oxygen scavengers.

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