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
• • 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
  • B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
  • B01J20/0225—Compounds of Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt
  • B01J20/0229—Compounds of Fe
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F7/00—Heating or cooling appliances for medical or therapeutic treatment of the human body
  • A61F7/02—Compresses or poultices for effecting heating or cooling
  • A61F7/03—Compresses or poultices for effecting heating or cooling thermophore, i.e. self-heating, e.g. using a chemical reaction
• • 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
  • B01J20/20—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
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/16—Materials undergoing chemical reactions when used
  • C09K5/18—Non-reversible chemical reactions
• • 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 disclosure relates to iron-based powders and oxygen reactants for oxygen reactants.
• Oxygen reactants that utilize the reaction between iron-based powder and oxygen are known to be used, for example, as oxygen scavengers and exothermic agents.
• Oxygen scavengers are used to create a low-oxygen condition by sealing the container together with stored items such as foods and medicines, thereby suppressing quality deterioration due to oxidation of stored items and growth of mold, etc.
• As a heat generating agent it is widely used as a disposable body warmer to warm the human body.
• activated carbon, sodium chloride, silica powder, wood flour, water, sulfur powder, and the like are added to iron-based powder in order to further promote the oxygen reaction in these oxygen reactants.
• reaction rate between iron and oxygen is important, and as a means to control the reaction rate, mixing powders of conductive substances other than iron with iron powder has been considered. ing.
• Patent Document 1 Japanese Unexamined Patent Publication No. 2003-117385
• the surface of the iron powder is partially coated with conductive carbonaceous substances such as conductive graphite, carbon black, graphite, and activated carbon.
• Oxygen scavengers using active iron powder coated with weight percent are disclosed.
• Patent Document 1 discloses that the so-called free carbon state liberated from iron powder has no effect on the oxygen absorption properties of the oxygen scavenger and requires an operation to partially coat the surface of the iron powder.
• Patent Document 1 does not specify the components of the iron powder itself.
• the surface of iron powder is oxidized, it becomes difficult to form iron ions and emit electrons. Therefore, when the surface of iron powder is oxidized as is commonly seen, the phenomenon described in Patent Document 1 where the iron powder becomes an anode and the carbon material becomes a cathode, promoting the oxidation reaction, does not occur. , there is a problem that it becomes less likely to occur.
• the present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide an iron-based powder for an oxygen reactant and an oxygen reactant that have excellent oxygen reactivity.
• carbonaceous powder such as graphite is said to have no effect on the oxygen absorbing properties of an oxygen scavenger in its free carbon state, and is considered not to function as an oxygen reactant.
• iron powder and carbonaceous powder which is a conductive powder with a higher potential than the iron powder
• a corrosion current flows from the high potential carbonaceous powder to the low potential iron powder.
• a local battery mechanism occurs in which the corrosion current returns to the carbonaceous powder, which has a higher potential than the iron powder, via the electrolyte and then flows back to the iron powder. It is also believed that when such a mechanism occurs, the reaction between low-potential iron powder and oxygen is promoted.
• the present disclosure is based on the above findings, and the gist of the disclosure is as follows. 1. iron powder having an atomic ratio O/Fe of oxygen and iron of 0.30 or less; Carbonaceous powder having a C content of 50% by mass or more, An iron-based powder for an oxygen reactant, wherein the content of the carbonaceous powder is 0.20% by mass or more and 30.00% by mass or less.
• an iron-based powder for an oxygen reactant and an oxygen reactant having excellent oxygen reactivity can be obtained.
• the reason why the iron-based powder for oxygen reactants of the present disclosure exhibits excellent oxygen reactivity is presumed to be as follows. That is, since the carbonaceous powder has a higher potential than the iron powder, when the carbonaceous powder and the iron powder come into contact with each other in the electrolytic solution, a corrosion current is generated and the oxidation reaction of the iron powder is promoted. Further, the iron-based powder for an oxygen reactant of the present disclosure has excellent reactivity with oxygen, and therefore is suitably used as the oxygen reactant of the present disclosure. Therefore, the oxygen reactant of the present disclosure can exhibit the same characteristics and effects as the iron-based powder for oxygen reactants of the present disclosure.
• the potential of iron increases when it is oxidized, it is easier to increase the potential difference with the carbonaceous powder if the iron powder is not oxidized as much as possible before being used as an oxygen reactant. As a result, the corrosion current increases. Therefore, in the present disclosure, the atomic ratio of oxygen to iron (hereinafter also referred to as "O/Fe") in the iron powder of the iron-based powder for oxygen reactant needs to be 0.30 or less. If O/Fe is within this range, the potential difference between the carbonaceous powder and the iron powder in the electrolytic solution will be sufficiently large, and an effective (enough to promote the oxidation reaction of the iron powder) corrosion current amount will be obtained.
• O/Fe oxygen to iron
• O/Fe in the iron powder of the iron-based powder for an oxygen reactant is set to 0.30 or less.
• the lower limit of O/Fe is not particularly determined, and may be 0, but from an industrial perspective, about 0.15 is preferable.
• the value of O/Fe can be measured according to the method described later.
• the iron powder used in the present disclosure can be produced by water atomization, gas atomization, a pulverization method, and an oxide reduction method. Further, in the present disclosure, carbonaceous powder is added to the iron powder, but the carbonaceous powder may be commercially available graphite powder, coke powder, carbon black powder, or the like.
• the "iron-based powder” in the present disclosure refers to a metal powder containing 50.0% by mass or more of Fe. Moreover, the iron-based powder can further contain arbitrary elements such as C, S, O, N, Si, Na, Mg, and Ca in addition to the metal iron (Fe). Note that the metallic iron content of the iron-based powder can be measured in accordance with JIS A 5011-2 "Metallic iron quantitative determination method.”
• the iron-based powder for oxygen reactants is a mixed powder of iron powder and carbonaceous powder, and the content of carbonaceous powder in the mixed powder is in the range of 0.20% by mass or more and 30.00% by mass or less. do. If the content of carbonaceous powder in the iron-based powder for oxygen reactant is less than 0.20% by mass, the amount of corrosion current will be small and there will be no effect on promoting the oxygen reaction of iron powder. On the other hand, since carbonaceous powder itself is difficult to oxidize, it reacts with less oxygen than iron powder.
• the content of carbonaceous powder in iron-based powder for oxygen reactant is more than 30.00% by mass, iron powder
• the oxygen reaction amount of the mixture of iron powder and carbonaceous powder becomes too low than the oxygen reaction amount of the iron powder alone.
• the content of carbonaceous powder in the iron-based powder for oxygen reactant is preferably 0.50% by mass or more, and the content of carbonaceous powder is 15.00% by mass. It is preferable that it is below.
• the present disclosure can achieve excellent oxygen reactivity by providing an iron-based powder for an oxygen reactant that satisfies the above requirements.
• the particle size of the iron powder is not particularly limited as long as there is no problem in handling, but the median diameter (median value of particle size from cumulative volume frequency) D50 is 1 mm or less, preferably 400 ⁇ m or less, more preferably 200 ⁇ m or less. A particle size of . On the other hand, the lower limit is preferably about 5 ⁇ m from the viewpoint of handling. Additionally, D50 can be measured according to the method described below.
• the carbonaceous powder of the present disclosure is carbonaceous powder in which the content of C component (carbon component) in the carbonaceous powder is 50% by mass or more. If the C content in the carbonaceous powder is less than 50% by mass, the amount of corrosion current will be small and there will be no effect on promoting the oxygen reaction of the iron powder.
• the C content in the carbonaceous powder is preferably 60% by mass or more, more preferably 70% by mass or more.
• the upper limit is not particularly limited, and the C content in the carbonaceous powder may be 100% by mass, but from an economic point of view, it is preferably about 95% by mass.
• the particle size of the carbonaceous powder is not particularly limited as long as there is no problem in handling, but it is preferable to have a median diameter D50 of 100 ⁇ m or less, preferably 50 ⁇ m or less, more preferably 30 ⁇ m or less.
• the lower limit of the particle size of the carbonaceous powder is preferably about 5 ⁇ m from the viewpoint of handling.
• the method for measuring the median diameter D50 of iron powder and carbonaceous powder is as follows. Iron powder and carbonaceous powder to be measured are placed in ethanol as a solvent, dispersed by ultrasonic vibration for 30 seconds or more, and then measured using a laser diffraction particle size distribution analyzer using laser diffraction/scattering method. Measurement of particle size, ie volumetric particle size distribution of particles of iron powder and carbonaceous powder, respectively. A cumulative particle size distribution is calculated from the obtained particle size distribution, and the particle size of particles corresponding to 50% of the total volume of all particles is determined as the median diameter D50 . In the present disclosure, this median diameter D50 is used as a representative value of the particle size of the iron powder and carbonaceous powder, respectively.
• the method for measuring O/Fe in powder in the present disclosure is preferably as follows. By performing X-ray diffraction measurement on the target powder and performing Rietveld analysis on the obtained diffraction data, the content of Fe alone, a compound of Fe and O, and other compounds in the powder can be determined. Since the number of atoms of Fe and O can be determined from the numerical value of the content, the value of O/Fe can be calculated.
• iron powder used in manufacturing the iron powder used in the present disclosure, water or gas atomization methods are used, in which molten metal is sprayed with water or gas, pulverized, cooled, and solidified, and iron oxide (milled iron oxide) generated from the surface of steel sheets during hot rolling of steel materials is used. It is preferable to produce it by reducing iron ore powder (scale) or iron ore powder. Further, the produced powder may be classified or mixed using various methods to prepare iron powder according to the present disclosure. Note that in order to remove oxygen to achieve the O/Fe range described above, deoxidation may be performed using carbon such as coke or graphite or hydrogen gas at a temperature of 750° C. or higher.
• the carbonaceous powder of the present disclosure may be a commercially available product such as graphite powder, coke powder, carbon black powder, etc.
• coke powder it can be manufactured as follows. That is, in producing such coke powder, coal is carbonized at 1000° C. or higher for 10 hours or more to remove volatile matter and tar contained in the coal, and then pulverized or classified. Furthermore, recovered powder generated during pulverization and classification can also be suitably used.
• the above-described iron-based powder for an oxygen reactant can be used as an oxygen reactant.
• the oxygen reactant of the present disclosure can be obtained.
• the constituents of the oxygen reactant other than the iron-based powder for oxygen reactants can be used without any particular restriction as long as they are used in conventionally known oxygen reactants. Examples of this structure include bags made of breathable packaging material made by laminating nonwoven fabric and perforated polyethylene, and bags made of breathable packaging material made by laminating paper and perforated polyethylene.
• the iron-based powder for an oxygen reactant used in this example was produced using the following procedure. Iron ore powder was reduced with hydrogen to produce 39 types of iron powder with different O/Fe ratios. Such iron powder, two types of lignite (A, B), sub-bituminous coal, graphite powder (CPB, manufactured by Nippon Graphite Industries Co., Ltd.), and coke produced by carbonizing coal at 1200 ° C. for 15 hours are crushed. The produced coke powder and carbon black powder (REGAL 330R, manufactured by Cabot Corporation) were each put into a V-type mixer and mixed to produce each iron-based powder for an oxygen reactant. Here, the C content of the lignite A was 58.7% by mass.
• the C content of the lignite B was 68.2% by mass.
• the C content of the sub-bituminous coal was 75.7% by mass.
• the C content of the graphite powder was 97.3% by mass.
• the C content of the coke powder was 81.7% by mass.
• the C content of the carbon black powder was 98.1% by mass. Note that O/Fe of the iron powder was calculated by measuring the content of Fe alone, a compound of Fe and O, and other compounds using an X-ray diffraction device (SmartLab manufactured by Rigaku Corporation).
• the oxygen reaction rate of the iron-based powder for oxygen reactant was evaluated as follows. 0.6 g of an aqueous solution with a concentration of 12% by mass of sodium chloride was mixed with 1.5 g of zeolite (Shin Tohoku Chemical Industries, Zeofil 1424# with a particle size of 1.0 to 2.0 mm) and 0.1 g of activated carbon powder (Fujifilm Wa After adding it to the mixed powder made by Hikari Pure Chemical Industries (particle size 3.0 to 300 ⁇ m), 1.5 g of the mixture with the above iron-based powder for oxygen reactant was filled into a bag (50 mm long x 60 mm wide) of ventilation packaging material. Each oxygen reactant was obtained.
• a laminated material composed of nonwoven fabric and open-pore polyethylene was used as the ventilation packaging material.
• One of each oxygen reactant was sealed together with 3 L of air in a gas barrier bag made of a laminated material made of nylon/aluminum foil/polyethylene. After the bag was allowed to stand at 25° C. for 8 hours, the oxygen concentration inside the bag was measured using a gas chromatograph (GD3210D, manufactured by GL Sciences, Inc.). The oxygen reaction amount was calculated from the difference between the oxygen concentration thus measured and the oxygen concentration in the air, and the oxygen reaction amount per 1 g of the iron-based powder for oxygen reactant was calculated.
• GD3210D gas chromatograph
• Table 1 shows the results of the oxygen reaction amount of each iron-based powder for an oxygen reactant in Comparative Examples and Examples according to the present disclosure.
• the iron-based powders of Examples 1 to 10 with a content of 0.20% by mass or more and 30.0% by mass or less have a higher oxygen reaction amount than the iron-based powders of Comparative Examples 1 to 29. It can be seen that the oxygen reaction amount per 1 g of base powder was 60 mL/g or more, indicating that the oxygen reaction amount was excellent.
• Examples 7 to 10 in which the carbonaceous powder content is 0.50% by mass or more and 15.0% by mass or less have an oxygen reaction amount of 70mL/g or more per 1g of iron-based powder, and the oxygen It can be seen that the reaction amount is superior and the oxygen reactivity is excellent.

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