Classifications

• • 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
  • 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
  • B01D53/14—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 absorption
• • 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
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/12—Metallic powder containing non-metallic particles

Definitions

• This disclosure relates to an iron-based mixed powder and an oxygen reactant.
• Oxygen reactants that utilize the reaction between iron-based powder and oxygen are used, for example, as oxygen scavengers and heat generating agents.
• Oxygen scavengers can create a low-oxygen state inside a container by sealing it together with the preserved object such as food or medicine, and are therefore used to prevent quality deterioration due to oxidation of the preserved object or the proliferation of aerobic mold.
• Heat generating agents are widely used, for example, as disposable hand warmers.
• As the oxygen reactant water, activated carbon, sodium chloride, etc. are added to the iron-based powder to further promote the reaction with oxygen.
• additives may be added to the oxygen reactant to adjust the reaction rate and the amount of heat generated, as well as to process by-product gases such as hydrogen.
• Oxygen absorbers and heat generating agents are often stored sealed in non-breathable packaging immediately after production. However, if oxygen remains in the packaging, oxidation of the iron progresses. As a result of this oxidation, the moisture added to the oxygen absorber or heat generating agent breaks down and hydrogen gas is generated. If a large amount of hydrogen gas is generated, the packaging material will expand and there is a risk of it bursting. For this reason, it is necessary to suppress the generation of hydrogen gas.
• Patent Document 1 discloses a hand warmer.
• the hand warmer uses iron powder treated with sulfur as the oxidizable agent.
• the oxidizable agent is produced by heating sulfur powder and iron powder, by heating iron powder coated with a sulfur solution or by immersing the iron powder in a sulfur solution and then drying the coated iron powder, or by heating iron powder in a solution of sulfur dissolved in a solvent.
• Patent Document 1 discloses the effect of using iron powder treated with sulfur to reduce the amount of gas generated.
• Patent Document 2 relates to raw iron powder for a slow heat-generating composition and its manufacturing method.
• the raw iron powder is mixed with a reaction aid, water, and a water retention agent for a composition that slowly heats up in the atmosphere.
• the raw iron powder is prepared by adding 1 g of the iron powder to 100 ml of water, mixing and stirring the resulting supernatant, and measuring the pH of the resulting solution to be 8 to 10.
• Thiosulfate powder is then mixed with the iron powder to give a sulfur content of 0.001% to 0.2% by weight.
• Patent Document 2 discloses that the use of the raw iron powder makes it possible to effectively suppress hydrogen gas generation during storage without adding large amounts of substances that adversely affect the heat-generating properties of the slow heat-generating composition.
• Patent Document 1 requires heating for treatment using sulfur, making the manufacturing process complicated.
• Patent Document 2 there is a demand to effectively utilize other sulfur-containing powders, not just the thiosulfate powder disclosed in Patent Document 2.
• the present disclosure has been made in consideration of the above-mentioned circumstances, and its purpose is to provide an iron-based mixed powder and an oxygen reactant that can be easily manufactured, have high reactivity with oxygen, and suppress the generation of hydrogen gas.
• iron-based mixed powder and oxygen reactant are as follows:
• the sulfur-containing powder is an iron-based mixed powder as described in [1] above, which contains manganese sulfide powder.
• the oxygen reactant has a content of the sulfur-containing powder of 0.020 mass % or more and 5.000 mass % or less with respect to the total content of the iron-based powder and the content of the sulfur-containing powder.
• the sulfur-containing powder is an oxygen reactant described in [4] above, which contains manganese sulfide powder.
• the present disclosure provides an iron-based mixed powder and an oxygen reactant that can be easily manufactured, have high reactivity with oxygen, and suppress the generation of hydrogen gas.
• iron-based powder refers to a powder containing 50.000 mass% or more of Fe.
• Iron-based alloy powder refers to an alloy powder containing 50.000 mass% or more of Fe.
• Iron powder refers to a powder consisting of Fe and unavoidable impurities, and is generally referred to as “pure iron powder” in this technical field.
• the iron-based mixed powder according to this embodiment is a mixed powder consisting of an iron-based powder having an oxygen to iron atomic ratio O/Fe of 0.800 or less, and a sulfur-containing powder having a sulfur content of 10.000 mass% or more and 100.000 mass% or less.
• the content of the sulfur-containing powder in the iron-based mixed powder according to this embodiment is 0.020 mass% or more and 5.000 mass% or less with respect to the total content of the iron-based powder and the sulfur-containing powder.
• the oxygen reactant in this embodiment includes the above-mentioned iron-based mixed powder.
• the iron-based mixed powder according to this embodiment is highly reactive with oxygen and can suppress the generation of hydrogen gas, making it suitable for use as an oxygen reactant.
• the iron-based mixed powder and oxygen reactant according to this embodiment are described in detail below.
• the iron-based mixed powder according to this embodiment is a powder in which an iron-based powder and a sulfur-containing powder are mixed.
• the iron-based mixed powder is composed of an iron-based powder and a sulfur-containing powder.
• the iron-based powder may be, for example, iron powder or iron-based alloy powder.
• the iron-based powder may further contain elements such as C, S, O, N, Si, Na, Mg, and Ca in addition to Fe.
• the iron-based powder may contain elements such as C, S, O, N, Si, Na, Mg, and Ca as inevitable impurities.
• the atomic ratio of oxygen to iron in the iron-based powder (hereinafter sometimes referred to as O/Fe) is 0.800 or less, preferably 0.700 or less, more preferably 0.600 or less, and even more preferably 0.250 or less.
• O/Fe may be 0 or 0.000.
• O/Fe is preferably 0.030 or more, and more preferably 0.150 or more.
• the O/Fe ratio of the iron-based powder is measured by X-ray diffraction. Specifically, it is measured by the method described in the Examples.
• the method for producing the iron-based powder is not particularly limited, and it can be produced by a conventional method.
• the iron-based powder can be produced by a method such as an atomization method or a reduction method.
• the atomization method is a method in which water or gas is sprayed onto a molten metal, which is then pulverized and cooled to solidify. Either a water atomization method or a gas atomization method can be used.
• the reduction method is, for example, a method in which iron oxide (mill scale) or iron ore powder generated on the surface of a steel sheet during hot rolling of the steel material is reduced. That is, the iron-based powder can be an atomized iron-based powder or a reduced iron-based powder.
• the iron-based powder can be a water atomized iron-based powder or a gas atomized iron-based powder.
• the above-mentioned powder may be subjected to one or both of pulverization and classification to adjust the particle size.
• the method of pulverization and classification is not particularly limited, and may be performed by a conventional method.
• a heat treatment may be performed using a reducing agent at a maximum temperature of 750°C or higher.
• the reducing agent may be, for example, carbon such as coke, coal, or graphite, or hydrogen gas.
• the reducing agent may, for example, be added to or mixed with the above-mentioned powder.
• the sulfur-containing powder in this embodiment is preferably a powder containing one or both of elemental sulfur and a sulfur compound.
• the sulfur-containing powder may be composed of elemental sulfur or may be composed of a sulfur compound.
• the sulfur-containing powder preferably contains one or both of a powder of elemental sulfur and a powder of a sulfur compound, and the sulfur-containing powder may be a powder of elemental sulfur or may be a powder of a sulfur compound.
• the sulfur contained in the sulfur-containing powder may be derived from only one or both of elemental sulfur and a sulfur compound.
• the term "sulfur powder" refers to powder of elemental sulfur.
• the sulfur compound examples include sulfides.
• the sulfides include manganese sulfide, calcium sulfide, sodium sulfide, and nickel sulfide. That is, the sulfur-containing powder may contain any of manganese sulfide powder, calcium sulfide powder, sodium sulfide powder, and nickel sulfide powder, and may be any of manganese sulfide powder, calcium sulfide powder, sodium sulfide powder, and nickel sulfide powder.
• the sulfur-containing powder contains one or both of sulfide and elemental sulfur, and it is more preferable that it is one or both of sulfide powder and sulfur powder.
• sulfides manganese sulfide powder has a larger specific gravity than sulfur powder and is closer to iron-based powder, so it is well mixed with iron-based powder.
• the sulfur-containing powder preferably contains manganese sulfide, and more preferably is manganese sulfide powder.
• the sulfur-containing powder may also contain, for example, an additive.
• the additive may or may not contain sulfur.
• the additive include silica and carbon. That is, the sulfur-containing powder may contain silica powder, or may contain carbonaceous powder.
• Silica powder is an inert powder that does not contribute to the reaction between iron and oxygen, and can be added to mix elemental sulfur and sulfur compounds more uniformly with the iron-based powder.
• Carbonaceous powder can be added to further promote the reaction between iron and oxygen. Examples of the carbonaceous powder include activated carbon powder, coke powder, carbon black powder, acetylene black powder, and graphite powder.
• the sulfur-containing powder has a sulfur content of 10.000% by mass or more and 100.000% by mass or less.
• the sulfur content of the sulfur-containing powder is set to 10.000% by mass or more, preferably 43.000% by mass or more, and more preferably 80.000% by mass or more.
• the upper limit of the sulfur content of the sulfur-containing powder is not particularly limited and can be 100.000% by mass. However, from the viewpoint of adding additives, it may be, for example, 99.900% by mass or less.
• the content of the sulfur-containing powder is 0.020% by mass or more and 5.000% by mass or less with respect to the sum of the content of the iron-based powder and the content of the sulfur-containing powder.
• the content of the sulfur-containing powder with respect to the sum of the content of the iron-based powder and the content of the sulfur-containing powder may be simply referred to as the content of the sulfur-containing powder.
• the content of the sulfur-containing powder is 0.050% by mass or more, the reactivity with oxygen is improved and the effect of suppressing hydrogen gas can be obtained. Therefore, the content of the sulfur-containing powder is 0.050% by mass or more, preferably 0.200% by mass or more, more preferably 0.600% by mass or more, and even more preferably 1.100% by mass or more.
• the content of the sulfur-containing powder is 5.000% by mass or less, the water on the surface of the iron-based powder is prevented from becoming too acidic, thereby suppressing the generation of hydrogen gas.
• the hydrogen gas is converted to hydrogen sulfide gas by reaction with sulfur, the excessive generation of hydrogen sulfide gas due to this reaction is suppressed, thereby suppressing the generation of the rotten egg odor caused by hydrogen sulfide gas. Therefore, the content of the sulfur-containing powder is 5.000% by mass or less, and preferably 3.000% by mass or less.
• the iron-based powder and the sulfur-containing powder are uniformly mixed.
• the iron-based powder and the sulfur-containing powder may be mixed using a powder mixing device such as a V-type mixer, a double cone mixer, or a conical blender.
• the volumetric median diameter of the iron-based mixed powder (the median value of the particle diameter calculated from the volumetric particle size distribution, so-called D50 ) is not particularly limited as long as there is no problem in handling.
• the volumetric median diameter of the iron-based mixed powder is preferably 1000 ⁇ m or less, more preferably 400 ⁇ m or less, even more preferably 200 ⁇ m or less, and particularly preferably 100 ⁇ m or less.
• the volumetric median diameter of the iron-based mixed powder is preferably 5 ⁇ m or more, and more preferably 70 ⁇ m or more.
• the median diameter of the iron-based mixed powder on a volume basis is measured using a laser diffraction particle size distribution analyzer.
• the volumetric median diameter of the iron-based mixed powder is specifically measured as follows. First, the powder to be measured is placed in ethanol and dispersed by ultrasonic vibration for 30 seconds or more. Then, the volumetric particle size distribution is measured using a laser diffraction particle size distribution measuring instrument (LA-950V2, manufactured by Horiba, Ltd.) that uses the laser diffraction and scattering method. The median diameter is obtained by calculating the cumulative particle size distribution from the volumetric particle size distribution obtained by this measurement.
• LA-950V2 laser diffraction particle size distribution measuring instrument
• the oxygen reactant according to this embodiment includes the iron-based mixed powder according to this embodiment.
• the oxygen reactant according to this embodiment may use the iron-based mixed powder, and does not exclude the inclusion of other components in addition to the iron-based mixed powder.
• the sulfur in the fine sulfur powder formed on the surface of the iron particles reacts with the hydrogen generated during the hydrolysis described above and is converted into hydrogen sulfide. This is thought to suppress the generation of hydrogen gas throughout the system.
• the oxygen reactant according to this embodiment may be enclosed in a bag.
• a bag is a bag made of a breathable packaging material in which a nonwoven fabric and perforated polyethylene are layered together, or a bag made of a breathable packaging material in which paper and perforated polyethylene are layered together.
• the iron-based mixed powder according to this embodiment will be explained below based on examples.
• the iron-based mixed powder in this example was produced using the following procedure.
• Iron ore powder was reduced with coke at 800-1000°C to adjust the O/Fe ratio, and iron powder was obtained.
• the O/Fe ratio was calculated by measuring the content of elemental Fe, Fe and O compounds, and other compounds using an X-ray diffraction device (Rigaku Corporation, SmartLab).
• the sulfur-containing powder used was a powder in which sulfur powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., SSE02PB) was mixed with silica powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., SIO09PB) to adjust the sulfur content.
• sulfur powder manufactured by Kojundo Chemical Laboratory Co., Ltd., SSE02PB
• silica powder manufactured by Kojundo Chemical Laboratory Co., Ltd., SIO09PB
• manganese sulfide powder manufactured by Kojundo Chemical Laboratory Co., Ltd., MNI09PB
• calcium sulfide powder manufactured by Kojundo Chemical Laboratory Co., Ltd., CA105PB
• the iron powder and the sulfur-containing powder were mixed to obtain iron-based mixed powders according to the examples and comparative examples.
• Comparative Example 1 no sulfur-containing powder was mixed.
• Table 1 shows the O/Fe ratio of the iron powder, the type of sulfur-containing powder, the sulfur content (mass%) of the sulfur-containing powder, the content (mass%) of the sulfur-containing powder, and the median diameter ( D50 ) of the iron-based mixed powder measured by the above-mentioned method.
• the underlined values indicate that the values are outside the range of this embodiment.
• the reactivity with oxygen, the amount of hydrogen gas generated, and the amount of hydrogen sulfide gas generated of the iron-based mixed powders in the examples and comparative examples were evaluated as follows.
• the reactivity with oxygen was evaluated as follows. First, 0.006 g of sodium chloride powder (NAH07PB, manufactured by Kojundo Chemical Laboratory Co., Ltd.) was mixed with 1.50 g of iron-based mixed powder. A mixture of 0.95 g of Isolite CG (No. 1, manufactured by Isolite Kogyo Co., Ltd.), made of baked diatomaceous earth, and 0.85 g of water was added to the resulting powder, and the mixture was filled into a breathable packaging bag (45 mm long x 40 mm wide) to prepare a sample for evaluation in the examples or comparative examples. A laminated material consisting of nonwoven fabric and perforated polyethylene was used for the breathable packaging bag.
• a gas barrier bag made of a laminated material consisting of five layers of nylon/polyethylene/aluminum foil/polyethylene/polyethylene.
• the bags containing the sealed samples were left to stand at 25°C for 72 hours.
• the oxygen concentration of the gas in the bag was then measured using a gas chromatograph (GC3210D, manufactured by GL Sciences Inc.).
• the amount of oxygen lost in the bag was calculated by subtracting the oxygen concentration in the bag from the oxygen concentration in the air.
• the amount of oxygen reacted per gram of iron-based mixed powder (ml/g) was then calculated based on this amount of oxygen lost.
• the oxygen reaction amount in this embodiment refers to the volume (ml) of oxygen that 1 g of the iron-based mixed powder can remove from 3000 mL of air at atmospheric pressure at 25°C over a period of 72 hours.
• the greater the oxygen reaction amount the higher the reactivity with oxygen.
• the iron-based mixed powder when used as an oxygen reactant, it is superior in terms of total heat generation, heat generation temperature, and heat generation time (excellent heat generation characteristics).
• the amount of hydrogen gas and hydrogen sulfide gas generated was evaluated as follows. First, 0.06 g of sodium chloride powder (NAH07PB, manufactured by Kojundo Chemical Laboratory Co., Ltd.) was mixed with 15.00 g of iron-based mixed powder. A mixture of 7.89 g of Isolite CG (No. 1, manufactured by Isolite Kogyo Co., Ltd.), made of baked diatomaceous earth, and 7.11 g of water was added to the resulting powder, and the mixture was filled into a breathable packaging bag (length 80 mm x width 80 mm) to prepare a sample for evaluation in the examples or comparative examples. A laminated material consisting of nonwoven fabric and perforated polyethylene was used for the breathable packaging bag.
• a gas barrier bag made of a laminated material consisting of five layers of nylon/polyethylene/aluminum foil/polyethylene/polyethylene.
• the bags containing the sealed samples were left to stand at 55°C for 72 hours.
• the hydrogen gas concentration (volume %) in the bags was then measured using a gas chromatograph (GC3210D, manufactured by GL Sciences Inc.).
• the hydrogen sulfide concentration (ppm) in the bags was measured using a gas monitor (GX-3R Pro, manufactured by Riken Keiki Co., Ltd.).
• the study also assessed that hydrogen sulfide generation is prevented if the concentration is less than 0.3 ppm, which is known to be the concentration at which humans do not detect a rotten egg smell.
• Table 1 also shows the evaluation results for the oxygen reaction amount, hydrogen gas concentration, and hydrogen sulfide concentration mentioned above.
• the iron-based mixed powder of the embodiment had higher reactivity with oxygen, generated less hydrogen gas, and generated less hydrogen sulfide than the powder of the comparative example.
• the iron-based mixed powders of Examples 3 to 10 had a median diameter of 400 ⁇ m or less, which further increased their reactivity with oxygen and further reduced the amount of hydrogen gas generated. In addition, the generation of hydrogen sulfide was also prevented.
• the median diameter was set to 200 ⁇ m or less, which increased the reactivity with oxygen and reduced the amount of hydrogen gas generated compared to Examples 1 to 4. In addition, the generation of hydrogen sulfide was also prevented.
• the iron-based mixed powder according to this embodiment is highly reactive with oxygen and hydrogen gas generation is suppressed.
• the iron-based mixed powder according to this embodiment generates a small amount of hydrogen sulfide, preventing the rotten egg odor.
• This disclosure is applicable to iron-based mixed powders and oxygen reactants.

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