Iron-based powder for oxygen reactant and oxygen reactant

Abstract

Provided is an iron-based powder for oxygen reactants having excellent oxygen reactivity. The iron-based powder for an oxygen reactant contains an iron powder in which the atomic ratio (O / Fe) of oxygen to iron is 0.30 or less, and a carbonaceous powder in which the content of component C is 50 mass% or more, wherein the content of the carbonaceous powder is 0.20-30.00 mass%.

Description

Technical Field

[0001] The present disclosure relates to an iron-based powder for an oxygen reactant and an oxygen reactant. Background Art

[0002] As oxygen reactants that utilize the reaction between iron-based powder and oxygen, the uses of deoxidizers and exothermic agents are known. As deoxidizers, they are sealed in a container together with stored items such as food and medicines to form a low oxygen state, and are used to inhibit the quality deterioration caused by oxidation of stored items and the growth of molds, etc. As exothermic agents, they are widely used as disposable heating pads for heating the human body, etc. In general, in order to further promote the oxygen reaction, these oxygen reactants add activated carbon, sodium chloride, silica powder, wood powder, water, sulfur powder, etc. to the iron-based powder.

[0003] In any application, the reaction rate between iron and oxygen is of great importance, and as a means for controlling the reaction rate, mixing a conductive material powder other than iron with iron powder has been studied.

[0004] For example, Japanese Patent Application Laid-Open No. 2003-117385 (Patent Document 1) discloses a deoxidizer using activated iron powder whose surface is partially coated with 0.3 to 3.0 wt % of a conductive carbonaceous material such as conductive graphite, carbon black, graphite, and activated carbon.

[0005] It should be noted that Patent Document 1 discloses that the so-called free carbon state released from the iron powder has no effect on the oxygen absorption property of the deoxidizer, and that it is necessary to partially cover the surface of the iron powder.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2003-117385 Summary of the invention

[0009] However, the composition of the iron powder itself is not specified in the disclosure of Patent Document 1. In particular, if the surface of the iron powder is oxidized, it is difficult to form iron ions and release electrons. Therefore, there is a problem that if the surface of the iron powder is oxidized as is usually seen, it is difficult to cause the phenomenon described in Patent Document 1 that the iron powder is the anode and the carbon material is the cathode to promote the oxidation reaction.

[0010] In view of such actual circumstances, an object of the present disclosure is to provide an iron-based powder for an oxygen reactant and an oxygen reactant having excellent oxygen reactivity.

[0011] As described above, it is believed that the carbonaceous powders such as the graphite powder, coal powder, and activated carbon powder mentioned above have no effect on the oxygen absorption characteristics of the deoxidizer in the free carbon state and do not function as an oxygen reactant.

[0012] As can be seen from the potential-pH diagram of iron (Pourbait diagram), the standard electrode potential of the carbonaceous powder as described above is higher than that of iron, and when iron is oxidized, the potential increases.

[0013] Furthermore, if iron powder comes into contact with carbonaceous powder, which is a conductive powder with a higher potential than iron powder, in a corrosive environment such as an electrolyte, the following local battery mechanism occurs: the corrosion current flows from the high-potential carbonaceous powder to the low-potential iron powder, and then the corrosion current returns to the carbonaceous powder with a higher potential than iron powder via the electrolyte, and then flows through the iron powder again. It is believed that if such a mechanism occurs, the reaction between the low-potential iron powder and oxygen is promoted.

[0014] Therefore, in order to promote the reaction between iron-based powder and oxygen, the inventors thought of adding carbonaceous powder in a free carbon state that is difficult to react with oxygen to iron powder and conducted intensive research. As a result, they found that there is an appropriate mixing ratio of iron-based powder that exhibits excellent oxygen reactivity.

[0015] The present disclosure is based on the above findings, and its gist is as follows.

[0016] 1. An iron-based powder for an oxygen reactant, comprising:

[0017] Iron powder having an atomic ratio of oxygen to iron (O / Fe) of 0.30 or less, and

[0018] The carbonaceous powder contains 50% by mass or more of the component C.

[0019] The content of the carbonaceous powder is 0.20 mass % to 30.00 mass %.

[0020] 2. The iron-based powder for an oxygen reactant according to item 1 above, wherein the carbonaceous powder comprises at least one of coal powder and coke powder.

[0021] 3. The iron-based powder for an oxygen reactant according to item 1 above, wherein the carbonaceous powder includes coal powder and coke powder.

[0022] 4. The iron-based powder for an oxygen reactant according to any one of 1 to 3 above, wherein the carbonaceous powder contains at least one of activated carbon powder and carbon black powder.

[0023] 5. The iron-based powder for an oxygen reactant according to any one of 1 to 4 above, wherein the carbonaceous powder contains 0.12% by mass or more of coke powder.

[0024] 6. The iron-based powder for an oxygen reactant according to any one of 1 to 5 above, wherein the carbonaceous powder includes coke powder and carbon black powder.

[0025] 7. The iron-based powder for an oxygen reactant according to 6 above, comprising 3.50% by mass or more of the coke powder and 6.20% by mass or more of the carbon black powder.

[0026] 8. An oxygen reactant using the iron-based powder for an oxygen reactant according to any one of 1 to 7 above.

[0027] According to the present disclosure, an iron-based powder for an oxygen reactant and an oxygen reactant having excellent oxygen reactivity can be obtained. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present disclosure will be described. It should be noted that the following embodiments are examples for describing the present disclosure, and the present disclosure is not limited to these embodiments.

[0029] The reason why the iron-based powder for oxygen reactant of the present invention 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 contacts the iron powder in the electrolyte, a corrosion current is generated to promote the oxidation reaction of the iron powder. In addition, the iron-based powder for oxygen reactant of the present invention has excellent reactivity with oxygen and is therefore suitable for use in the oxygen reactant of the present invention. Therefore, the oxygen reactant of the present invention can have the same characteristics and effects as the iron-based powder for oxygen reactant of the present invention.

[0030] Here, if the iron is oxidized, the potential increases, so the iron powder before use as an oxygen reactant is not oxidized as much as possible and it is easier to increase the potential difference with the carbonaceous powder. As a result, the corrosion current becomes larger. Therefore, in the present disclosure, it is necessary to set the atomic ratio of oxygen to iron in the iron powder of the iron-based powder for oxygen reactant (hereinafter also referred to as O / Fe) to 0.30 or less. If it is such a range of O / Fe, the potential difference between the carbonaceous powder and the iron powder in the electrolyte becomes large enough to generate an effective (sufficient to promote the oxidation reaction of the iron powder) corrosion current. Therefore, in the present disclosure, the O / Fe in the iron powder of the iron-based powder for oxygen reactant is set to 0.30 or less. It should be noted that the lower limit of O / Fe is not particularly limited, and it can also be 0, and it is preferably about 0.15 in industry. In addition, the value of O / Fe can be measured according to the method described later.

[0031] The iron powder used in the present disclosure can be produced by water atomization, gas atomization, pulverization and oxide reduction. In addition, in the present disclosure, carbonaceous powder is added to such iron powder. Such carbonaceous powder can be commercially available activated carbon powder, coke powder and carbon black powder.

[0032] Here, the "iron-based powder" in the present disclosure refers to a metal powder containing 50.0 mass % or more of Fe. In addition, the iron-based powder may further contain any element such as C, S, O, N, Si, Na, Mg, Ca, etc. in addition to the above-mentioned metallic iron (Fe). It should be noted that the metallic iron content of the iron-based powder can be measured in accordance with JIS A5011-2 "Metallic Iron Quantitative Method".

[0033] The iron-based powder for oxygen reactant is a mixed powder of iron powder and carbonaceous powder, and the content of carbonaceous powder in the mixed powder is set to the range of 0.20 mass % to 30.00 mass %. If the content of carbonaceous powder in the iron-based powder for oxygen reactant is less than 0.20 mass %, the corrosion current is small and there is no effect of promoting the oxygen reaction of iron powder. On the other hand, since carbonaceous powder itself is not easily oxidized, the amount of reaction with oxygen is less than that of iron powder. If the content of carbonaceous powder in the iron-based powder for oxygen reactant is more than 30.00 mass %, the oxygen reaction amount of the mixture of iron powder and carbonaceous powder becomes too low compared to the oxygen reaction amount of iron powder alone (for example, 60 mL / g). It should be noted that from the viewpoint of oxygen reactivity, the content of carbonaceous powder in the iron-based powder for oxygen reactant is preferably 0.50 mass % or more, and the content of carbonaceous powder is preferably 15.00 mass % or less.

[0034] The present disclosure can achieve excellent oxygen reactivity by forming an iron-based powder for an oxygen reactant that satisfies the above requirements.

[0035] The particle size of the iron powder is not particularly limited as long as there is no problem in operation. The median particle size (the median value of the particle size based on the cumulative volume frequency) is D 50 The particle size is preferably 1 mm or less, preferably 400 μm or less, and more preferably 200 μm or less. On the other hand, from the perspective of operation, the lower limit is preferably about 5 μm. 50 The measurement can be carried out according to the method described later.

[0036] The carbonaceous powder disclosed in the present invention is a carbonaceous powder in which the content of the C component (carbon component) in the carbonaceous powder is 50% by mass or more. If the content of the C component in the carbonaceous powder is less than 50% by mass, the corrosion current decreases without promoting the oxygen reaction of the iron powder. The C component in the carbonaceous powder is preferably 60% by mass or more, more preferably 70% by mass or more. On the other hand, the upper limit is not particularly limited, and the C component in the carbonaceous powder is 100% by mass, and from the viewpoint of economic efficiency, it is preferably about 95% by mass.

[0037] The particle size of the carbonaceous powder is not particularly limited as long as there is no problem in operation. The median particle size D 50 The particle size is preferably 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less. On the other hand, the lower limit of the particle size of the carbonaceous powder is preferably about 5 μm from the viewpoint of handling.

[0038] Median particle size D of iron powder and carbonaceous powder 50 The measurement method is as follows. Iron powder and carbonaceous powder to be measured are put into ethanol as a solvent, dispersed by ultrasonic vibration for more than 30 seconds, and the particle size is measured using a laser diffraction particle size distribution measuring machine using a laser diffraction / scattering method, that is, the volume-based particle size distribution of the particles of iron powder and carbonaceous powder is measured respectively. The cumulative particle size distribution is calculated based on the obtained particle size distribution, and the particle size of the particles corresponding to 50% of the total volume of all particles is calculated as the median particle size D. 50 In the present disclosure, the median particle size D 50 As representative values ​​of the particle sizes of the above-mentioned iron powder and carbonaceous powder.

[0039] [Calculation method of O / Fe in powder]

[0040] The method for measuring O / Fe in the powder disclosed in the present invention is preferably as follows. The powder as the object is subjected to X-ray diffraction measurement, and the obtained diffraction data is subjected to Rietveld analysis, thereby knowing the content of Fe element, Fe and O compounds, and other compounds in the powder. The number of Fe and O atoms is obtained from the numerical value of the content, so the value of O / Fe can be calculated.

[0041] [Manufacturing of iron powder]

[0042] When manufacturing the iron powder used in the present disclosure, it is preferred to use a water atomization method or a gas atomization method in which water or gas is sprayed onto the molten metal to pulverize it and cool it to solidify, and to reduce the iron oxide (scale) or iron ore powder generated on the surface of the steel plate during hot rolling of the steel. Furthermore, the prepared powder can be classified or mixed by various methods to adjust it to the iron powder of the present disclosure. It should be noted that in order to remove oxygen to achieve the above-mentioned O / Fe range, deoxidation can be performed using carbon such as coke and graphite or hydrogen at a temperature above 750°C.

[0043] [Carbon powder]

[0044] The carbonaceous powder disclosed in the present invention may be a commercially available product such as coal powder, activated carbon powder, coke powder, carbon black powder, etc. For example, in the case of coke powder, it can be produced as follows. That is, when producing the coke powder, coal is dry-distilled at 1000° C. or more for 10 hours or more to remove volatile components and tar contained in the coal, and then pulverized and classified. In addition, powders obtained by recovering powders generated during pulverization and classification can also be appropriately used.

[0045] [Manufacturing of iron-based powder]

[0046] When the iron-based powder for oxygen reactant is produced, the iron powder and the carbonaceous powder need to be mixed. In the iron-based powder for oxygen reactant, the iron powder and the carbonaceous powder are preferably mixed uniformly. Therefore, it is preferred to use a device for mixing using a V-type mixer, a double cone mixer, a cone mixer, etc. It should be noted that the above-mentioned device and its mixing conditions can be used in the known manner.

[0047] [Oxygen reactant]

[0048] In the present disclosure, the oxygen reactant can be prepared using the above-mentioned iron-based powder for oxygen reactant. For example, if the above-mentioned iron-based powder for oxygen reactant is sealed in the bag described below, the oxygen reactant disclosed herein can be prepared. It should be noted that the constituents other than the iron-based powder for oxygen reactant in the oxygen reactant can be used without particular restrictions as long as they are substances used in the conventionally known oxygen reactants. As such constituents, for example, bags of breathable packaging materials formed by overlapping non-woven fabrics and open-pore polyethylene, bags of breathable packaging materials formed by overlapping paper and open-pore polyethylene, etc. can be cited.

[0049] Example

[0050] The iron-based powder for oxygen reactant used in this embodiment is prepared according to the following steps. Iron ore powder is hydrogen-reduced to prepare 39 kinds of iron powders with different O / Fe. The iron powder, two kinds of powdered lignite (A, B) as coal powder, sub-bituminous coal, activated carbon powder (Shirasagi PHC-14, manufactured by Osaka Gas Chemical Co., Ltd.), coke powder manufactured by crushing coke made by dry distilling coal at 1200°C for 15 hours, and carbon black powder (REGAL330R, manufactured by Cabot Corporation) are respectively put into a V-type mixer and mixed to prepare each iron-based powder for oxygen reactant. Here, the content of C component in the above-mentioned lignite A is 58.7% by mass. The content of C component in the above-mentioned lignite B is 68.2% by mass. The content of C component in the above-mentioned sub-bituminous coal is 75.7% by mass. The content of C component in the above-mentioned activated carbon powder is 89.8% by mass. The content of C component in the above-mentioned coke powder is 81.7% by mass. The carbon black powder contained 98.1% by mass of the component C. The O / Fe ratio of the iron powder was measured using an X-ray diffractometer (SmartLab manufactured by Rigaku Corporation) to calculate the content of simple Fe, compounds of Fe and O, and other compounds.

[0051] In this embodiment, the oxygen reactivity of the iron-based powder for oxygen reactants is evaluated as follows. After adding 0.6 g of an aqueous solution with a concentration of 12% by mass of sodium chloride to 1.5 g of zeolite (Zeolite 1424# with a particle size of 1.0 to 2.0 mm manufactured by Shintohoku Chemical Industry), the substance obtained by mixing with 1.5 g of the above iron-based powder for oxygen reactants is filled into a bag of a breathable packaging material (50 mm long × 60 mm wide) to obtain each oxygen reactant. The breathable packaging material uses a laminated material composed of non-woven fabric and open-pore polyethylene. Each oxygen reactant is sealed together with 3 L of air in a laminated material composed of nylon / aluminum foil / polyethylene, i.e., a gas barrier bag. After the bag is left to stand at 25°C for 8 hours, a gas chromatograph (GC3210D manufactured by GL Sciences Co., Ltd.) is used to measure the oxygen concentration in the bag. The oxygen reaction amount is calculated based on the difference between the oxygen concentration measured in this way and the oxygen concentration in the air, and the oxygen reaction amount per 1 g of iron-based powder for oxygen reactants is calculated.

[0052] Table 1 shows the results of the oxygen reaction amount of each iron-based powder for oxygen reactant in the comparative example and the example of the present disclosure. In addition, Table 2 shows the median particle size (D 50 Table 3 shows the median particle size (D 50 ) In the following description, the iron-based powder for oxygen reactant may be simply referred to as iron-based powder.

[0053] [Table 1]

[0054] Table 1

[0055]

[0056] ※ Underlined characters indicate outside the scope of the present invention.

[0057] [Table 2] Table 2

[0058]

[0059] [Table 3]

[0060] Table 3

[0061] <![CDATA[D of carbonaceous powder 50 (μm)]]> Lignite A 65 Lignite B 48 Subbituminous coal 52 Coke powder 32 Activated carbon powder 18 carbon black powder 10

[0062] As shown in Table 1, the iron-based powders of Examples 1 to 20, in which the atomic ratio O / Fe of oxygen to iron in the iron powder is 0.30 or more, the content of the C component in the mixed powder with the iron powder is 50% by mass or more, the content of the carbonaceous powder is 0.20% by mass to 30.0% by mass, and which contain at least one of coal powder and coke powder, have a high oxygen reaction amount compared to the iron-based powders of Comparative Examples 1 to 17, and the oxygen reaction amount per 1g of the iron-based powder is 60mL / g or more, and is excellent in oxygen reaction amount.

[0063] It can be seen that the oxygen reactivity per 1g of the iron-based powder of Examples 10 to 20 including coke powder as the carbonaceous powder was 65 mL / g or more, and all of them had more excellent oxygen reactivity in terms of oxygen reactivity.

[0064] The iron-based powders of Examples 10 to 20 all contain 0.12 mass % or more of coke powder. It is understood that when the iron-based powder contains 0.12 mass % or more of coke powder, it has more excellent oxygen reactivity in terms of oxygen reaction amount.

[0065] It can be seen that the iron-based powders of Examples 16 to 20 containing coke powder and carbon black powder all have an oxygen reaction amount of 77 mL / g or more per 1 g of the iron-based powder, and have very excellent oxygen reactivity in terms of oxygen reaction amount.

[0066] The iron-based powder of Example 19 further comprising activated carbon powder among the iron-based powders of Examples 16 to 20 comprising coke powder and carbon black powder has very excellent oxygen reactivity of 81 mL / g per 1 g of the iron-based powder, even though the content of carbonaceous powder is only 1.20% by mass.

[0067] It can be seen that the iron-based powders of Examples 16 to 18 and 20 containing only coke powder and carbon black powder as carbonaceous powder have very excellent oxygen reactivity if they contain 3.50 mass % or more of coke powder and 6.20 mass % or more of carbon black powder.

[0068] From the results of Comparative Examples 5, 9, 13, and 17, it can be seen that when the total amount of carbonaceous powder exceeds 30.00 mass%, the iron-based powder does not have excellent oxygen reactivity. In particular, when the iron-based powder contains coke powder and carbon black powder as carbonaceous powder, as in Comparative Examples 13 and 17, when the total amount of carbonaceous powder exceeds 30.00 mass%, the iron-based powder does not have excellent oxygen reactivity. Therefore, it is necessary to set the total amount of carbonaceous powder to 30.00 mass% or less.

[0069] In comparison of the iron-based powder of Example 19 containing coke powder, activated carbon powder and carbon black powder as carbonaceous powder, the iron-based powders of Examples 16 to 18 and 20 containing only coke powder and carbon black powder as carbonaceous powder, the iron-based powders of Examples 13 to 15 containing only coke powder and activated carbon powder as carbonaceous powder, the iron-based powders of Examples 10 to 12 containing only coke powder as carbonaceous powder, and the iron-based powders of Comparative Examples 4 and 5, the following can be further understood regarding the case where the iron-based powder contains coke powder.

[0070] When the iron-based powder contains only coke powder, the content of coke powder as carbonaceous powder is 0.20 mass% or more, and when the content of coke powder is 30.00 mass% or less (Examples 10 to 12), the iron-based powder has excellent reactivity. However, when the content of coke powder as carbonaceous powder is less than 0.20 mass% (Comparative Example 4) and when the content of coke powder is more than 30.00 mass% (Comparative Example 5), the iron-based powder does not have excellent reactivity.

[0071] As described above, even when the iron-based powder contains only a predetermined amount of coke powder, the iron-based powder has excellent reactivity. However, when other carbonaceous powders such as activated carbon powder and carbon black powder are coexisted in addition to coke powder (Examples 13 to 20), the iron-based powder has more excellent oxygen reactivity than when only coke powder in the iron-based powder is increased or decreased. In particular, when the iron-based powder contains at least coke powder and carbon black powder (Examples 16 to 20), the iron-based powder has very excellent oxygen reactivity.

[0072] It should be noted that the iron-based powders of Examples 1 to 9, in which the content of coal powder as carbonaceous powder is 0.20 mass% to 30.00 mass%, have an oxygen reaction amount per 1g of iron-based powder that is stable at 60 mL / g to 63 mL / g without deviation. If the content of coal powder as carbonaceous powder is 0.20 mass% to 30.00 mass%, it has excellent oxygen reactivity in terms of oxygen reaction amount and has stable oxygen reactivity without deviation.

[0073] As described above, it is possible to provide an iron-based powder for an oxygen reactant and an oxygen reactant having excellent oxygen reactivity.

[0074] Industrial Applicability

[0075] The present disclosure may be applicable to an iron-based powder for an oxygen reactant and an oxygen reactant.

Claims

1. An iron-based powder for an oxygen reactant, comprising: Iron powder having an atomic ratio of oxygen to iron (O / Fe) of 0.30 or less, and The carbonaceous powder contains 50% by mass or more of the component C. The content of the carbonaceous powder is 0.20 mass % to 30.00 mass %.

2. The iron-based powder for oxygen reactant according to claim 1, wherein: The carbonaceous powder includes at least one of coal powder and coke powder.

3. The iron-based powder for oxygen reactant according to claim 1, wherein: The carbonaceous powder includes coal powder and coke powder.

4. The iron-based powder for oxygen reactants according to any one of claims 1 to 3, wherein The carbonaceous powder includes at least one of activated carbon powder and carbon black powder.

5. The iron-based powder for oxygen reactants according to any one of claims 1 to 4, wherein The carbonaceous powder contains 0.12 mass % or more of coke powder.

6. The iron-based powder for oxygen reactants according to any one of claims 1 to 5, wherein The carbonaceous powder includes coke powder and carbon black powder.

7. The iron-based powder for oxygen reactant according to claim 6, wherein: The coke powder is contained in an amount of 3.50% by mass or more and the carbon black powder is contained in an amount of 6.20% by mass or more.

8. An oxygen reactant using the iron-based powder for an oxygen reactant according to any one of claims 1 to 7.

Images