JPH11302706A - Iron powder for reactive material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide improved iron powder for a reactive material for keeping a non-oxidizing atmosphere by absorbing oxygen in a tightly closed vessel and the producing method. SOLUTION: The iron powder for reactive material is a powdery oxygen scavenger composed of iron powder, preferably reduced iron powder reformed by forming a coating layer containing 0.1-2 wt.% Cl on the surface by the contact reaction with chlorine or hydrogen chloride gas and a sheet like material formed by kneading the powder with a resin. And the objective product is produced by carrying out a reforming treatment to bring the iron powder under fluidization into contact with chlorine or hydrogen chloride gas carried in an inert gas preferably accompanied by hydrogen as carrier at <=300 deg.C and a reduction heat treatment or a surface oxidation heat treatment of the iron powder in advance to the reforming treatment, preferably by carrying out cooperatively the reduction heat treatment and the surface oxidation heat treatment to improve the deoxygen performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deoxidizer for absorbing oxygen in a sealed container to maintain a non-oxidizing atmosphere, iron powder for a reaction material used as another reaction material, and its production. About the method.

[0002]

2. Description of the Related Art For example, in order to prevent deterioration of stored foods and the like due to oxygen, a deoxidizer in which iron powder is treated together with stored foods and the like and treated with iron powder to absorb oxygen in the sealed containers is practically used. Has been A sheet or film obtained by kneading a thermoplastic resin and an oxygen scavenger is used as a packaging material having oxygen scavenging performance. It is also known that a treated iron powder having a halide formed on its surface is particularly effective. As a conventional production technique for obtaining a deoxidizing agent using such iron halide powder, a technique of mixing iron powder with a metal halide solution such as sodium chloride, uniformly coating the surface of the iron powder with a metal halide, and then drying. Is described in JP-A-54-35883.
There is a disclosure in Japanese Patent Publication No. Japanese Patent Application Laid-Open No. Sho 54-54 discloses a technique for performing surface modification by contacting iron powder with an acidic aqueous solution such as hydrochloric acid.
This is disclosed in Japanese Patent Publication No. 99092.

A technique for directly mixing iron powder and an electrolyte powder such as a metal halide in a fine powder state and uniformly depositing the electrolyte powder on the iron powder for surface modification is disclosed in JP-A-60-209.
No. 86 discloses this. Also, a technique of adding an electrolyte powder such as a metal halide to iron powder, mixing and pulverizing the powder while applying mechanical force such as frictional force and / or compression force, and attaching and bonding the electrolyte powder to the iron powder is disclosed in −129137
There is a disclosure in Japanese Patent Publication No.

[0004]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open Nos. 54-35883 and 54-99092.
The technology disclosed in the publication is a wet treatment method in which iron powder is treated using an aqueous electrolyte solution, which requires a drying and moisture control step and, in some cases, generates a waste liquid, so that measures must be taken for that. There is a problem,
The techniques disclosed in JP-A-20986 and JP-A-60-129137 are disadvantageous in that the electrolyte is powdery and adhered to iron powder, and the reaction promoting effect is not sufficiently obtained and the deoxygenation reaction is slow. there were. That is, there is a problem that the reaction of the non-adhered portion is slow.
No. 986 discloses a process in which only the mixing is performed, so that the amount of the electrolyte powder adhered to the iron powder having a small particle size is small. Was. To solve the above problems, the present invention provides:
Provided is a deoxidizing agent which is manufactured by a dry treatment method, does not require a moisture control step such as drying, is excellent in uniform covering properties of halides, particularly chlorides in iron powder, and is excellent in a deoxidizing reaction, and a method for producing the same. Aim.

[0005]

According to the present invention, reforming is performed by using a common chlorine or hydrogen chloride gas as a reaction gas, that is, a halogen gas or a halide gas, and contacting and reacting these gases with iron powder. The deoxygenation activity is improved, and the entire surface of the iron powder including the recesses and internal pores can be uniformly coated, so that the reaction area is substantially increased, and the deoxygenation activity is increased, and in the dry treatment, Therefore, the present invention has been made based on the finding that it is not necessary to control the water content and the like, and the processing steps are simple.

That is, according to the present invention, there is provided an iron powder in which a coating layer made of iron chloride is formed on the surface.
Iron powder for a reactant containing ~ 2 wt% Cl,
The coating layer is formed of the iron powder for a reaction material according to the first aspect, which is generated by a contact reaction with chlorine or hydrogen chloride gas, and the iron powder for a reaction material, wherein the iron powder is reduced iron. Still further, the present invention provides an iron powder for a reaction material obtained by kneading the powdered iron powder for a reaction material with a resin to form a sheet or a film.

Further, the present invention provides a method for producing an iron powder for a reaction material, wherein the iron powder is brought into contact with chlorine or hydrogen chloride gas to cause a reaction to form iron chloride on the surface of the iron powder. The reforming treatment is a method for producing an iron powder for a reaction material performed while flowing the iron powder, and the reforming treatment is a method for producing an iron powder for a reaction material performed at a temperature of room temperature to 300 ° C. The method for producing an iron powder for a reactant, in which a gas is entrained in a carrier gas by an inert gas, the method for producing an iron powder for a reactant, in which the chlorine or hydrogen chloride gas is entrained in a carrier gas and water vapor by an inert gas, Iron powder is a method for producing a reaction material iron powder that performs a reduction heat treatment before the reforming treatment, the iron powder is a method for producing a reaction material iron powder that performs a surface oxidation heat treatment before the modification treatment, Then, the iron powder is subjected to a reduction heat treatment before the reforming treatment. An object of the present invention is to provide a method for producing iron powder for a reaction material, in which the treatment and the surface oxidation heat treatment are performed in a cooperative manner.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In order to cause a reaction gas consisting of chlorine or hydrogen chloride gas to contact and react with iron powder, the iron powder is put into a reaction vessel whose atmosphere can be adjusted, and the inside of the reaction vessel is filled with an inert gas such as nitrogen. A means is taken to replace the atmosphere with an inert gas, and to introduce a reaction gas, preferably together with a carrier gas, into contact with the iron powder. As the reaction gas, hydrogen chloride gas is generally used from the viewpoint of reactivity and safety (hereinafter, the reaction gas will be described as hydrogen chloride gas).

In this case, the iron powder is brought into contact with hydrogen chloride gas in a fluidized state by utilizing a rotating mechanism or an internal stirring mechanism of the reaction vessel, so that the reaction can be uniformly performed over the entire iron powder. By using an inert gas such as nitrogen, argon or helium as a carrier gas, the reaction rate during the treatment can be adjusted. The reaction by contact with hydrogen chloride gas is remarkable,
Iron chloride is formed uniformly and relatively early over the entire surface up to the recesses and internal voids of the iron powder. Therefore, a long process is not required. The treatment temperature is lower than the melting point of FeCl ₃ , that is, 300 ° C., and preferably from room temperature to 200 ° C. A higher temperature can suppress the adhesion of unreacted hydrogen chloride gas, so that the reaction efficiency of hydrogen chloride gas becomes better.However, if the temperature is too high, the control of the reaction amount tends to be difficult, and the This causes problems such as corrosion. It is meaningless to set the temperature below room temperature from the viewpoint of economic efficiency. The iron powder is not limited to the quality and the shape, but reduced iron fine powder having a large specific surface area is also desirable from the viewpoint of the covering property of the iron chloride with the hydrogen chloride gas.

By the above-mentioned hydrogen chloride gas treatment, iron powder for a reaction material can be obtained from iron powder containing 0.1 to 2% by weight of Cl in the form of iron chloride in the surface layer. This iron powder for the reaction material
In use, Cl in the surface layer iron chloride promotes the ionization of Fe, absorbs oxygen in the presence of water, and produces iron hydroxide.
If the Cl content is less than 0.1% by weight, the oxygen absorbing power is not sufficient, and if the Cl content is more than 2% by weight, the improvement of the oxygen absorbing power corresponding to the productivity cannot be expected. In the above-mentioned reforming treatment, when introducing hydrogen chloride gas into the reaction vessel, when the carrier gas is accompanied by water vapor, the adsorbability of the hydrogen chloride gas to the iron powder is increased and the reaction efficiency is improved.

Further, by performing a reduction heat treatment of the iron powder before the reforming treatment, when used as an oxygen scavenger, the quality of metallic iron on the surface is improved, thereby suppressing generation of hydrogen gas and improving oxygen absorbing ability. This has the effect. This suppression of hydrogen gas generation is thought to be due to the fact that the heat treatment by reduction removes the distortion of the iron powder and reduces the surface energy, thereby suppressing the decomposability of water. This suppresses the generation of hydrogen gas due to the unnecessary reaction between the water and the iron powder even when the oxygen in the deoxygenation container becomes low and only water is used when the oxygen absorber is used. It has the effect of being done.

It is desirable to perform a surface oxidation heat treatment before the modification treatment. This surface oxidation heat treatment improves the reaction efficiency of hydrogen chloride gas. The reason is considered to be that the specific surface area increases. However, the performance as a deoxidizer is further improved, and it becomes possible to suppress the generation of hydrogen gas during use and promote the consumption of oxygen. By performing the reduction heat treatment and the surface oxidation heat treatment in combination, the oxygen absorbing ability as a deoxidizer is further improved.

The oxygen scavenger of the present invention can be effectively used as a sheet or film which can be easily handled by kneading it in a resin. The treated iron powder reacts not only on the surface of the sheet or film but also in the resin with oxygen that has passed through the resin, and the reacted oxygen is consumed for the production of iron oxide and iron hydroxide.

[0014]

[Example 1] A rotary evaporator equipped with a vacuum suction device and capable of adjusting the temperature was used as an apparatus, and reduced iron powder having an average particle size of 25 µm was used as iron powder. First,
500 g of iron powder was charged into the device container. The rotation of the device is 45
After replacing the inside of the apparatus container with nitrogen gas at 150 rpm, hydrogen chloride gas was introduced at a rate of 150 ml / min, and a reforming treatment was performed at a treatment temperature of 25 ° C for 60 minutes to obtain a deoxidizer powder sample. . 1 g of the obtained oxygen scavenger powder sample (sample 1)
It was sealed in a breathable polyethylene bag of 40 mm x 45 mm. The bag-containing oxygen absorber powder sample was put in a deoxygenator made of aluminum laminate bags together with filter paper impregnated with 1 ml of water and 1500 ml of air and sealed. This was stored at 20 ° C., and after 24 hours, the amount of oxygen absorption was measured from the change in the oxygen concentration in the deoxygenation container.

The oxygen scavenger powder sample (sample 1) and a polypropylene resin (FL25HA, trade name of Mitsubishi Chemical Corporation)
And a weight ratio of 3: 7, and kneaded for 10 minutes at a device rotation speed of 30 rpm and a processing temperature of 200 ° C. using a Labo Plastomill equipped with a mixer mechanism and an extrusion mechanism capable of adjusting the temperature. Dissolve the obtained kneaded material on a hot plate,
After molding into 1 mm, it was cut into 60 mm x 60 mm to obtain a resin kneaded sheet sample. The resin-kneaded sheet sample was put in a deoxygenating container made of an aluminum laminate bag together with filter paper impregnated with 1 ml of water and 1500 ml of air, and sealed. This deoxygenation container was stored at 50 ° C., and after 24 hours, the amount of oxygen absorption was measured from the change in the oxygen concentration in the deoxygenation container. Iron powder 1
Table 1 shows the calculation results of the amount of oxygen absorbed per g.

[Example 2] A batch type rotary furnace was used as an apparatus, and 3000 g of reduced iron powder having an average particle size of 25 µm was used as iron powder.
Was charged into the apparatus container. 10 rpm
After replacing the inside of the apparatus container with nitrogen, the temperature was raised to 200 ° C. and maintained. Hydrogen chloride gas was introduced at a rate of 150 ml / min for 6 hours, and a reforming treatment was performed to obtain an oxygen scavenger powder sample. With respect to the obtained oxygen scavenger powder sample (hereinafter referred to as sample 2), a sample in a powder state and a resin kneaded sheet state were prepared under the same conditions as in Example 1, and the amount of oxygen absorbed in the oxygen scavenging container was measured. It was measured. Table 1 shows the calculation results of the amount of oxygen absorbed per gram of iron powder.

Example 3 A batch type rotary furnace was used as an apparatus, and 3000 g of reduced iron powder having an average particle diameter of 25 μm was used as iron powder.
And filled into the apparatus container. 10 rp
After replacing the inside of the apparatus container with nitrogen, the temperature was raised to 600 ° C., hydrogen gas was introduced at a rate of 3 l / min, and reduction heat treatment of the iron powder surface was performed for 6 hours. The resulting reduced iron powder was subjected to a reforming treatment with hydrogen chloride gas under the same conditions as in Example 1. For the obtained oxygen-absorbing agent powder sample (hereinafter referred to as sample 3), a sample in a powder state and a resin-kneaded sheet state were prepared in the same manner as in Example 1, and the amount of oxygen absorbed in the oxygen-absorbing container was measured. It was measured. Table 1 shows the calculation results of the amount of oxygen absorbed per gram of iron powder.

Example 4 A batch type rotary furnace was used as an apparatus, and 3000 g of reduced iron powder having an average particle size of 25 μm was used as iron powder.
And filled into the apparatus container. Set the number of rotations of the device container to 1
After setting the pressure to 0 rpm and replacing the inside of the apparatus container with nitrogen, the temperature was raised to 200 ° C., air was introduced at a rate of 2 l / min, and the surface oxidation heat treatment of the iron powder was performed for 20 minutes. The resulting oxidized iron powder was subjected to a reforming treatment with hydrogen chloride gas under the same conditions as in Example 1. With respect to the obtained oxygen-absorbing agent powder sample (hereinafter referred to as sample 4), a sample in a powder state and a resin kneaded sheet state were prepared in the same manner as in Example 1, and the amount of oxygen absorbed in the oxygen-absorbing container was measured. It was measured. Table 1 shows the calculation results of the amount of oxygen absorbed per gram of iron powder.

[Embodiment 5] A surface reduction heat treatment of iron powder was carried out under the same conditions as in Embodiment 3 using a batch type rotary furnace and reduced iron powder. The obtained reduced iron powder was subjected to a surface oxidation heat treatment of the iron powder under the same conditions as in Example 4. The resulting reduced and oxidized iron powder was subjected to a reforming treatment with hydrogen chloride gas under the same conditions as in Example 1. With respect to the obtained oxygen scavenger powder sample (hereinafter referred to as sample 5), a sample in a powder state and a resin kneaded sheet state were prepared in the same manner as in Example 1, and the oxygen absorption amount in the oxygen scavenging container was measured. It was measured. Table 1 shows the calculation results of the amount of oxygen absorbed per gram of iron powder.

Comparative Example 1 Reduced iron powder having an average particle size of 25 μm
500 g and 10 g of sodium chloride having an average particle size of 16 μm as electrolyte powder are mixed for 30 minutes in a 1-liter V-type mixer (with a horizontal stirring blade inside a V-shaped cylinder) to deoxygenate. An agent powder sample was obtained. For the obtained oxygen-absorbing agent powder sample (sample 6), a sample in a powder state and a resin-kneaded sheet state were prepared in the same manner as in Example 1, and the amount of oxygen absorbed in the oxygen-absorbing container was measured. did. Table 1 shows the calculation results of the amount of oxygen absorbed per gram of iron powder.

Comparative Example 2 Reduced iron powder having an average particle size of 45 μm
1500 g and 30 g of sodium chloride with an average particle size of 16 μm as an electrolyte powder were mixed, and pulverized for 6 hours in a 3 l vibrating ball mill containing 10.5 kg of 1/2 inch steel balls. An oxygen scavenger powder sample with a diameter of 22 μm was obtained. For the obtained oxygen-absorbing agent powder sample (hereinafter referred to as sample 7), a sample in a powder state and a resin-kneaded sheet state were prepared in the same manner as in Example 1, and the amount of oxygen absorbed in the deoxidizing container was measured. did. Table 1 shows the calculation results of the amount of oxygen absorbed per gram of iron powder.

Comparative Example 3 A universal stirrer equipped with a stirrer capable of adjusting the rotation speed in a container was used, and the average particle size was 25 μm.
2,000 g of reduced iron powder of NaCl 100
While immersing and mixing in 400 ml of NaCl aqueous solution containing 2 g / l, in a nitrogen atmosphere flowing nitrogen gas at 2 l / min.
The temperature was raised to ° C and drying was performed to obtain a powder sample of an oxygen scavenger. For the obtained oxygen-absorbing agent powder sample (hereinafter referred to as sample 8), a sample in a powder state and a resin-kneaded sheet state were prepared in the same manner as in Example 1, and the amount of oxygen absorbed in the oxygen-absorbing container was measured. It was measured. Table 1 shows the calculation results of the amount of oxygen absorbed per gram of iron powder.

[0023]

[Table 1]

From these results, it was found that the iron powder modified using sodium chloride as the electrolyte substance by the conventional method was subjected to simple mixing (sample 6), immersion in an aqueous solution (sample 8), and mixing. Although the performance is improved in the order of the pulverizing treatment (sample 7), it can be seen that the method according to the present invention is significantly improved as compared with these conventional methods (sample 1, sample 2). In addition, as shown in the case where the hydrogen reduction heat treatment was performed prior to the reforming treatment (Sample 3) and the case where the air oxidation heat treatment was performed (Sample 4), particularly, the hydrogen reduction heat treatment and the air oxidation heat treatment were linked. The effect of the pre-treatment was remarkable, as shown in the sample (Sample 5) that was performed in a selective manner. Further, it can be seen that the reaction rate becomes slower by using the kneaded material with the resin, but a sufficient improvement effect of the deoxidation performance can be obtained in the same order as the processing conditions in the case of the powder.

[0025]

As is apparent from the above description, according to the present invention in which iron powder is reformed with chlorine or hydrogen chloride gas, uniform coating properties are excellent, and conventional powder-mixing processing and electrolyte aqueous solution are performed. The deoxygenation performance is remarkably improved as compared with the immersion treatment in water, and the dry treatment method has effects such as not requiring drying and moisture control treatment. Further, by entraining water vapor with chlorine or hydrogen chloride gas, it is further remarkable by performing reduction heat treatment or surface oxidation heat treatment of iron powder or linking treatment of reduction heat treatment and surface oxidation heat treatment prior to the reforming treatment. This has the effect that a high deoxidation performance can be obtained. Furthermore, there is an effect that sufficient deoxidation performance can be obtained even in a sheet or film state kneaded with a resin.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhiro Senoo 1-8-2, Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (72) Inventor Kazuto Ito 1-8-2, Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (72) Inventor Masahiro Maeda 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (72) Inventor Yukihiro Matsuda 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (72) Inventor Takeaki Nagasaki 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd.

Claims (12)

[Claims] 1. An iron powder having a coating layer made of iron chloride on its surface, wherein the coating layer contains 0.1 to 2% by weight of C.
1. An iron powder for a reaction material, comprising: 2. The method according to claim 1, wherein the coating layer is formed by a contact reaction with chlorine or hydrogen chloride gas.
The described iron powder for a reaction material. 3. The iron powder for a reaction material according to claim 1, wherein the iron powder is reduced iron powder. 4. The iron powder for a reaction material according to claim 1, wherein the iron powder is formed into a sheet or film by kneading with a resin. 5. A method for producing iron powder for a reaction material, comprising performing a reforming treatment for forming iron chloride on the surface of the iron powder by bringing chlorine or hydrogen chloride gas into contact with the iron powder to cause a reaction. 6. The method for producing iron powder for a reaction material according to claim 5, wherein the reforming treatment is performed while the iron powder is flowing. 7. The method for producing an iron powder for a reaction material according to claim 5, wherein the reforming treatment is performed at a temperature of room temperature to 300 ° C. 8. The method for producing iron powder for a reaction material according to claim 5, wherein the chlorine or hydrogen chloride gas is accompanied by a carrier gas of an inert gas. 9. The method for producing iron powder for a reaction material according to claim 5, wherein said chlorine or hydrogen chloride gas is accompanied by a carrier gas and water vapor by an inert gas. 10. The method for producing an iron powder for a reaction material according to claim 5, wherein a reduction heat treatment is performed on the iron powder before the modification treatment. 11. The method according to claim 5, wherein the iron powder is subjected to a surface oxidation heat treatment before the modification treatment. 12. The method according to claim 5, wherein the iron powder is subjected to a reduction heat treatment and a surface oxidation heat treatment before the modification treatment. Method.