Preparation method of iron-carbon chemical spontaneous heating material

Abstract

The invention discloses a preparation method of an iron-carbon chemical self-heating material, the iron-carbon chemical self-heating material is formed by mixing a heating material and an auxiliary material, the heating material has a core-membrane structure with reduced iron powder as a core and polyacrylic acid water-absorbent resin as a shell, the auxiliary materials comprise disodium hydrogen phosphate dodecahydrate as a phase change material, titanium dioxide as a soaking material and activated carbon powder as an adsorption material. The method can effectively delay contact between the reduced iron powder and the external environment, the heating temperature and the effective heating duration of the iron-carbon chemical spontaneous heating material are controlled by adding the phase change material with the low phase change temperature, and the prepared iron-carbon chemical spontaneous heating material is short in heating time, stable in heating temperature, sustainable in heating effect and capable of achieving the purpose of improving the heating efficiency of the iron-carbon chemical spontaneous heating material. The problem of scalding or poor heating effect caused by improper temperature control can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of self-heating materials of chemical materials, and in particular to a preparation method of an iron-carbon chemical self-heating material. Background Art

[0002] With the improvement of living standards, modern people pay more and more attention to health issues. Self-heating materials play an important role in keeping the body warm. They do not require external heat sources and can quickly generate heat under aerobic conditions. In addition, they have low raw material costs and are easy to carry and use in daily life. They have become one of the most important hot compress materials. However, in actual use, improper temperature control may cause burns or poor heating effects.

[0003] At present, the mainstream preparation method on the market is to adopt a physical mixing method, that is, to mix raw materials such as iron powder, activated carbon, salt and water in a certain proportion, and stimulate the iron powder to undergo an oxidation reaction with oxygen in the air through physical action, thereby generating heat. However, this preparation method has obvious disadvantages: first, the reaction rate is difficult to control, resulting in uneven heating, which affects the use effect; second, the material mixing uniformity is not high, and local overheating or insufficient reaction is prone to occur, which reduces the heating efficiency and duration of the material; third, the dust and exhaust gas generated during the preparation process cause certain pollution to the environment, which is not conducive to environmental protection requirements. It is particularly important to prepare an iron-carbon chemical self-heating material with a stable heating temperature and sustainable heating effect. Therefore, it is necessary to develop a preparation method for an iron-carbon chemical self-heating material. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an iron-carbon chemical self-heating material to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention is implemented according to the following technical solutions: On the one hand, an iron-carbon chemical self-heating material includes 100 parts of a heating material and 25-60 parts of an auxiliary material in a mass ratio, wherein the heating material has a core-membrane structure with reduced iron powder as the core and a polyacrylic acid absorbent resin as the shell, and the auxiliary materials include disodium hydrogen phosphate dodecahydrate, titanium dioxide and activated carbon powder.

[0006] Furthermore, the material includes 100 parts of reduced iron powder, 10 parts of polyacrylic acid water-absorbing resin, 10-20 parts of activated carbon powder, 5-10 parts of titanium dioxide and 10-30 parts of disodium hydrogen phosphate dodecahydrate.

[0007] Furthermore, the polyacrylic acid water-absorbing resin is a reaction product of 10 parts of sodium acrylate, 1 part of potassium persulfate, 1 part of sodium sulfite, 0.5 part of N,N'-methylenebisacrylamide and 50 parts of water.

[0008] Furthermore, the phase change temperature of the disodium hydrogen phosphate dodecahydrate phase change material is controlled at 35.8°C.

[0009] Furthermore, the particle size of the reduced iron powder and the activated carbon powder is 100 mesh, and the particle size of the titanium dioxide is 200 mesh.

[0010] On the other hand, a method for preparing an iron-carbon chemical self-heating material comprises the following steps: (1) At room temperature, 100 parts of reduced iron powder, 10 parts of sodium acrylate, 1 part of potassium persulfate, 1 part of sodium sulfite, 0.5 parts of N,N'-methylenebisacrylamide and 50 parts of water were added according to the mass ratio and mixed evenly to obtain a mixture; (2) under anaerobic conditions, adding the mixture into nitrogen-purged deionized water, heating to 35° C., stirring and reacting for 6 hours to obtain a gel resin containing reduced iron powder, and then repeatedly washing, drying and crushing with anhydrous ethanol, and centrifuging in a centrifuge to retain a powder of a core-membrane structure component with a large specific gravity; (3) Add activated carbon powder, titanium dioxide and disodium hydrogen phosphate dodecahydrate to the powder of the core-membrane structure component in a mass ratio of 100: (10-20): (5-10): (10-30), mix well, and obtain an iron-carbon chemical self-heating material.

[0011] An iron-carbon chemical self-heating material is used for heat preservation. When a sodium chloride solution with a mass fraction of 5-15% is added dropwise to the iron-carbon chemical self-heating material, the material starts to generate heat.

[0012] The beneficial effects of the present invention are: The present invention is a method for preparing an iron-carbon chemical self-heating material. Compared with the prior art, the present invention has the following technical effects: The heating material part of the iron-carbon chemical self-heating material provided by the invention has a core-membrane structure, and a layer of polyacrylic acid water-absorbing resin film is synthesized on the basis of reduced iron powder as the core.

[0013] During use of the present invention, the electrolyte solution is absorbed and infiltrated by the polyacrylic acid water-absorbing resin film layer, contacts with the reduced iron powder, and the dissolved oxygen and gaseous oxygen are enriched near the activated carbon powder, providing conditions for electrochemical corrosion of iron.

[0014] The present invention controls the heating temperature and effective heating time of the iron-carbon chemical self-heating material by adding a phase change material with a low phase change temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the heating principle of an iron-carbon chemical self-heating material of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described below by means of specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0017] like Figure 1 As shown, a method for preparing an iron-carbon chemical self-heating material comprises the following steps: Example 1

[0018] (1) Preparation of core-membrane structural components: In a reaction vessel equipped with a stirring device, add 100 parts of reduced iron powder, 10 parts of sodium acrylate, 1 part of potassium persulfate, 1 part of sodium sulfite, 0.5 parts of N,N'-methylenebisacrylamide and 50 parts of water and mix them evenly. Under anaerobic conditions, add the obtained mixture into deionized water purged with nitrogen, heat it to 35°C, stir and react for 6 hours to obtain a gel-state resin containing reduced iron powder, and then repeatedly wash, dry and crush it with anhydrous ethanol, centrifuge it, and retain the core-membrane structural components with a higher specific gravity; (2) Preparation of iron-carbon chemical self-heating material: Take 100 parts of the powder of the core-membrane structure component obtained in step (1), add 10 parts of activated carbon powder, 5 parts of titanium dioxide, and 10 parts of disodium hydrogen phosphate dodecahydrate, and mix well; (3) Heating of the iron-carbon chemical self-heating material: 5 parts of sodium chloride and 95 parts of water are prepared into an electrolyte solution, and 20 parts are added dropwise to 125 parts of the iron-carbon chemical self-heating material prepared in step (2). The material begins to heat up. Example 2

[0019] (1) Preparation of core-membrane structural components: In a reaction vessel equipped with a stirring device, add 100 parts of reduced iron powder, 10 parts of sodium acrylate, 1 part of potassium persulfate, 1 part of sodium sulfite, 0.5 parts of N,N'-methylenebisacrylamide and 50 parts of water and mix them evenly. Under anaerobic conditions, add the obtained mixture into deionized water purged with nitrogen, heat it to 35°C, stir and react for 6 hours to obtain a gel-state resin containing reduced iron powder, and then repeatedly wash, dry and crush it with anhydrous ethanol, centrifuge it, and retain the core-membrane structural components with a higher specific gravity; (2) Preparation of iron-carbon chemical self-heating material: Take 100 parts of the powder of the core-membrane structure component obtained in step (1), add 15 parts of activated carbon powder, 7 parts of titanium dioxide, and 20 parts of disodium hydrogen phosphate dodecahydrate, and mix well; (3) Heating of the iron-carbon chemical self-heating material: 10 parts of sodium chloride and 90 parts of water are prepared into an electrolyte solution, and 20 parts are added dropwise to 142 parts of the iron-carbon chemical self-heating material prepared in step (2). The material begins to heat up. Example 3

[0020] (1) Preparation of core-membrane structural components: In a reaction vessel equipped with a stirring device, add 100 parts of reduced iron powder, 10 parts of sodium acrylate, 1 part of potassium persulfate, 1 part of sodium sulfite and 0.5 parts of N,N'-methylenebisacrylamide and mix them evenly. Under anaerobic conditions, add the obtained mixture into deionized water purged with nitrogen, heat it to 35°C, stir and react for 6 hours to obtain a gel-state resin containing reduced iron powder, and then repeatedly wash, dry and crush it with anhydrous ethanol, centrifuge it, and retain the core-membrane structural components with a higher specific gravity; (2) Preparation of iron-carbon chemical self-heating material: Take 100 parts of the powder of the core-membrane structure component obtained in step (1), add 20 parts of activated carbon powder, 10 parts of titanium dioxide, and 30 parts of disodium hydrogen phosphate dodecahydrate, and mix well; (3) Heating of the iron-carbon chemical self-heating material: 15 parts of sodium chloride and 85 parts of water are prepared into an electrolyte solution, and 20 parts are added dropwise to 160 parts of the iron-carbon chemical self-heating material prepared in step (2). The material begins to heat up.

[0021] Comparative Example 1 (1) Preparation of coreless-membrane structured iron-carbon chemical self-heating material: In a reaction vessel equipped with a stirring device, 100 parts of reduced iron powder, 20 parts of activated carbon powder, 10 parts of titanium dioxide, and 30 parts of disodium hydrogen phosphate dodecahydrate were added and mixed evenly; (2) Heating of the coreless-membrane structured iron-carbon chemical self-heating material: An electrolyte solution prepared by adding 15 parts of sodium chloride and 85 parts of water to 160 parts of the coreless-membrane structured iron-carbon chemical self-heating material powder prepared in step (1) was dropped, and the material began to heat up.

[0022] Comparative Example 2 (1) Preparation of core-membrane structural components: In a reaction vessel equipped with a stirring device, add 100 parts of reduced iron powder, 10 parts of sodium acrylate, 1 part of potassium persulfate, 1 part of sodium sulfite, 0.5 parts of N,N'-methylenebisacrylamide and 50 parts of water and mix them evenly. Under anaerobic conditions, add the obtained mixture into deionized water purged with nitrogen, heat it to 35°C, stir and react for 6 hours to obtain a gel-state resin containing reduced iron powder, and then repeatedly wash, dry and crush it with anhydrous ethanol, centrifuge it, and retain the core-membrane structural components with a higher specific gravity; (2) Preparation of iron-carbon chemical self-heating material (without phase change material): Take 100 parts of the powder of the core-membrane structure component obtained in step (1), add 20 parts of activated carbon powder and 10 parts of titanium dioxide, and mix well; (3) Heating of iron-carbon chemical self-heating material (without phase change material): 15 parts of sodium chloride and 85 parts of water are prepared into an electrolyte solution, and 20 parts are added dropwise to 130 parts of the iron-carbon chemical self-heating material (without phase change material) prepared in step (2). The material begins to heat up.

[0023] Evaluation of heating effect: The temperature-time data of the iron-carbon chemical self-heating materials prepared in the above control examples and embodiments are tested for the heating time (the time required to rise to 40°C), the heating time (the duration of maintaining 40°C and above) and the maximum heating temperature. The results are as follows: Table 1 Temperature-time test data

[0024] From the temperature-time test data in Table 1, it can be seen that as the amount of phase change material increases (Comparative Example 2, Example 1, Example 2 and Example 3), the maximum heating temperature decreases from 55°C to 42°C, and the heating time increases from 98min to 192min. The reason for this may be that the addition of disodium hydrogen phosphate dodecahydrate, a phase change material, effectively controls the maximum heating temperature of the iron-carbon chemical self-heating material to shift to the vicinity of the phase change temperature, while the total amount of heat remains unchanged, and the heating time is correspondingly extended. In addition, in combination with Example 1, Example 2, Example 3 and Comparative Example 1, it is found that the heating time of the embodiment with a core membrane structure is extended and the maximum heating temperature becomes lower. The reason for this may be that the membrane structure of the polyacrylic acid water-absorbing resin delays the contact between the reduced iron powder and the external environment.

[0025] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An iron-carbon chemical self-heating material, characterized in that: The invention comprises 100 parts of heating material and 25-60 parts of auxiliary materials according to the mass ratio. The heating material has a core-membrane structure with reduced iron powder as the core and polyacrylic acid water-absorbing resin as the shell. The auxiliary materials include disodium hydrogen phosphate dodecahydrate, titanium dioxide and activated carbon powder.

2. The iron-carbon chemical self-heating material according to claim 1, characterized in that: The material comprises 100 parts of reduced iron powder, 10 parts of polyacrylic acid water-absorbing resin, 10-20 parts of activated carbon powder, 5-10 parts of titanium dioxide and 10-30 parts of disodium hydrogen phosphate dodecahydrate.

3. The iron-carbon chemical self-heating material according to claim 1, characterized in that: The polyacrylic acid water-absorbing resin is a reaction product obtained by mixing 10 parts of sodium acrylate, 1 part of potassium persulfate, 1 part of sodium sulfite, 0.5 parts of N,N'-methylenebisacrylamide and 50 parts of water.

4. The iron-carbon chemical self-heating material according to claim 1, characterized in that: The phase change temperature of the disodium hydrogen phosphate dodecahydrate phase change material is controlled at 35.8°C.

5. The iron-carbon chemical self-heating material according to claim 1, characterized in that: The particle size of the reduced iron powder and the activated carbon powder is 100 mesh, and the particle size of the titanium dioxide is 200 mesh.

6. A method for preparing an iron-carbon chemical self-heating material, for preparing the iron-carbon chemical self-heating material as claimed in claims 1 to 5, comprising the following steps: (1) At room temperature, 100 parts of reduced iron powder, 10 parts of sodium acrylate, 1 part of potassium persulfate, 1 part of sodium sulfite, 0.5 parts of N,N'-methylenebisacrylamide and 50 parts of water were added according to the mass ratio and mixed evenly to obtain a mixture; (2) under anaerobic conditions, adding the mixture into nitrogen-purged deionized water, heating to 35° C., stirring and reacting for 6 hours to obtain a gel resin containing reduced iron powder, and then repeatedly washing, drying and crushing with anhydrous ethanol, and centrifuging in a centrifuge to retain a powder of a core-membrane structure component with a large specific gravity; (3) Add activated carbon powder, titanium dioxide and disodium hydrogen phosphate dodecahydrate to the powder of the core-membrane structure component in a mass ratio of 100: (10-20): (5-10): (10-30), mix well, and obtain an iron-carbon chemical self-heating material.

7. An application of an iron-carbon chemical self-heating material in heat preservation, characterized in that: Adding a sodium chloride solution with a mass fraction of 5-15% to the iron-carbon chemical self-heating material will start to generate heat.

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