Microwave-heated composition and method for preparing same

Abstract

The present application relates to the technical field of microwave heating, and specifically discloses microwave heating compositions and methods for preparing the same. [Solution] A microwave heating composition is prepared from a metal composite powder, an organic silicone rubber composite, a heat-resistant agent, and a vulcanizing agent, and the metal composite powder is prepared by growing nickel-copper-zinc ferrite particles into hollow porous carbon spheres. The microwave heating composition prepared in this application has the advantages of good microwave absorption and heating performance, fast heating speed, high temperature, strong aging resistance, and the ability to meet the requirements of 2.45 GHz high-frequency heating in microwave ovens.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION This application relates to the technical field of microwave heating, and more particularly to microwave heating compositions and methods for preparing same. [Background technology]

[0002] A well-known representative product of microwave ovens is the microwave tray, the operating principle of which is to convert microwave energy into thermal energy using a microwave-absorbing material attached to the back of the tray. By heating the metal tray, the food in the tray can not only be heated directly by the microwaves, but can also be heated by the tray. This two-way heating mode not only shortens food processing time, but also enables various traditional cooking methods such as stir-frying, deep-frying, simmering and boiling to be achieved in the microwave oven, greatly expanding the usability of microwave ovens and making them popular with many users.

[0003] With the spread of microwave ovens and changes in users, users have increasingly placed demands on microwave-absorbing heat-generating components, mainly in terms of functionality, such as being able to lightly brown the surface of ingredients without burning them when frying, grilling steaks and lamb chops without browning them, making deep-fried chicken thighs, pizza, omelets, boiled vegetables, etc., and also cooking white rice and traditional clay pot rice.

[0004] Conventional microwave cookware uses manganese-zinc ferrite as a microwave absorbing and heat generating powder, which results in slow heating speed, poor temperature stability, and a low temperature in the high-temperature zone, which cannot meet the demands of European and American customers. The main reason for this is that manganese-zinc ferrite is suitable for use in the low frequency range of 1 kHz to 5 MHz, while industrial or home microwave ovens typically operate in the frequency range of 915±25 MHz to 2450±50 MHz. Summary of the Invention

[0005] To further improve the heating rate and temperature stability of microwave absorbing materials, the present application provides a microwave heating composition and a method for preparing the same.

[0006] In a first aspect, the present application provides a microwave heating composition, which adopts the following technical solutions:

[0007] The microwave heat generating composition has a weight ratio of raw materials of 20-50 metal composite powder: 10-12 organic silicone rubber composite: 0.2-1 heat resistant agent: 0.5-1.8 vulcanizing agent.

[0008] According to the above technical solution, a metal composite powder is used as the main microwave absorbing heat generating material, and the microwave heating composition prepared together with an organic silicone rubber composite, a heat-resistant agent, and a vulcanizing agent has good microwave absorbing and heating performance and can meet the demands of 2.45 GHz high frequency heating in a microwave oven.

[0009] Preferably, the method for preparing the metal composite powder includes step S1 of mixing tetraphenoxysilane, ethyl silicate, ethanol, deionized water, and aqueous ammonia in a certain ratio, stirring and reacting for 30 to 50 minutes at room temperature, adding 2,6-dimethyl-1,4-benzenediol and formaldehyde solution, stirring and reacting for 24 to 36 hours, centrifuging to collect a precipitate, washing the precipitate alternately with water and ethanol to make the supernatant colorless, and finally transferring the precipitate to a watch glass and drying it at 60 to 70°C; and primary firing the dried precipitate in an argon atmosphere. Finally, in step S2, the hollow porous carbon spheres are treated with an NaOH solution for 40 minutes to obtain hollow porous carbon spheres; in step S3, the hollow porous carbon spheres and metal acetate are dispersed in a certain ratio in a mixed solution of deionized water, oleic acid, and ethanol, and then ultrasonically stirred for 40 to 60 minutes, followed by reaction at 200 to 220°C for 10 to 12 hours. After natural cooling to room temperature, the precipitate is centrifuged to remove it, washed alternately with water and ethanol, and the supernatant is colorless. After that, it is dried at 60 to 70°C; and in step S4, the dried precipitate is secondarily calcined in an argon atmosphere to obtain a metal composite powder.

[0010] By adopting the above technical solution, a precursor with a shell and core structure is prepared using tetraphenoxysilane, ethyl silicate, ammonia water, 2,6-dimethyl-1,4-benzenediol, and formaldehyde as raw materials, and then the precursor is etched with sodium hydroxide and calcined to prepare hollow porous carbon spheres with a porous hollow structure. After that, a metal acetate and oleic acid are used to form a coating of oleic acid metal complex on the carbon sphere shell, and after calcination, nickel-copper-zinc ferrite particles are formed on the inner and outer walls of the hollow porous carbon spheres. This porous hollow carbon magnetic structure can reduce eddy current loss, minimize heating effects other than magnetic loss, and improve wave absorption performance.

[0011] Preferably, the mass-volume ratio of tetraphenoxysilane, ethyl silicate, ethanol, deionized water, ammonia water, 2,6-dimethyl-1,4-benzenediol, and formaldehyde solution in S1 is (1 to 1.2) g: (2.5 to 3) mL: (60 to 80) mL: (10 to 12) mL: (4.5 to 5.5) mL: (0.5 to 0.8) g: (2.5 to 3) mL.

[0012] By adopting the above technical solution, tetraphenoxysilane, ethyl silicate, ammonia water, 2,6-dimethyl-1,4-benzenediol and formaldehyde are polymerized as raw materials to form a precursor in which the silane core structure is covered with a resin shell.

[0013] Preferably, the weight percentage of the aqueous ammonia is 25% and the weight percentage of the formaldehyde solution is 38%.

[0014] By adopting the above technical solution, the volume of the shell core formed at that ratio becomes an appropriate size.

[0015] Preferably, the primary firing in S2 is performed by slowly increasing the temperature to 700 to 750°C at a rate of 2 to 4°C / min, and firing at a constant temperature for 4 to 5 hours, and the concentration of the NaOH solution is 1 mol / L.

[0016] By adopting the above technical solution, silica can be etched with NaOH and then calcined to form carbon spheres with porous hollow structure.

[0017] Preferably, the mass / volume ratio of the hollow porous carbon spheres, the metal acetate, and the mixed solution in S3 is (0.5 to 0.8) g:(0.2 to 0.4) g:(60 to 80) mL.

[0018] By adopting the above technical solution, the metal acetate and oleic acid form a coating of oleic acid metal complex on the carbon sphere shell.

[0019] Preferably, the volume ratio of deionized water, oleic acid and ethanol in the mixed solution is (1-1.2):(15-20):(80-100), and the metal acetate is selected from iron acetate, zinc acetate, copper acetate and nickel acetate. 0.4 Cu 0.2 Zn 0.4 Fe 2.0 Weigh accordingly at O4.

[0020] By adopting the above technical solutions, the crystal formation of nickel-copper-zinc ferrite particles is facilitated.

[0021] Preferably, the secondary firing is performed by slowly increasing the temperature to 780 to 900°C at a rate of 3°C / min, and firing at a constant temperature for 1 to 1.5 hours.

[0022] By adopting the above technical solutions, the crystal formation of nickel-copper-zinc ferrite particles becomes smaller.

[0023] In a second aspect, the present application provides a method for preparing a microwave-heatable composition, comprising the steps of: (1) uniformly mixing a metal composite powder, an organic silicone rubber composite, a rubber heat resistance agent, and a vulcanizing agent in a mixer at a specific ratio at 60-80°C to prepare a rubber material; (2) pressing the mixed rubber material into a raw material sheet 1-3 mm thick using a rolling mill or an open-type rubber kneading machine and cooling to room temperature; and (3) heating the raw material sheet to 150-180°C under pressure to vulcanize and mold it, and then cooling to room temperature to obtain a microwave-heatable composition. The raw material sheet has a thickness of 1-3 mm.

[0024] In summary, the present application has the following beneficial effects:

[0025] 1. In this application, metal composite powder is used as the main microwave-absorbing heat-generating material. The microwave-heat-generating composition prepared together with organic silicone rubber composite, heat-resistant agent, and vulcanizing agent has good microwave-absorbing and heat-generating performance and can meet the demands of 2.45GHz high-frequency heating in microwave ovens.

[0026] 2. In this application, preferably, tetraphenoxysilane, ethyl silicate, ammonia water, 2,6-dimethyl-1,4-benzenediol, and formaldehyde are used as raw materials to prepare a precursor with a shell and core structure, which is then etched with sodium hydroxide and calcined to prepare hollow porous carbon spheres with a porous hollow structure. After that, a metal acetate and oleic acid are used to form a coating of oleic acid metal complex on the carbon sphere shell, and after calcination, nickel-copper-zinc ferrite particles are formed on the inner and outer walls of the hollow porous carbon spheres. This porous hollow carbon magnetic structure can reduce eddy current loss, minimize heating effects other than magnetic loss, and improve wave absorption performance.

[0027] 3. The microwave heating composition prepared by the preparation method of the present application has the advantages of good microwave absorption and heating performance, fast heating speed, high temperature, strong aging resistance, and can meet the requirements of 2.45GHz high frequency heating in microwave ovens. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 shows SEM and TEM images of hollow porous carbon spheres and metal composite powder prepared in Example 2 of the present application (a is an SEM image of hollow porous carbon spheres, b is a TEM image of hollow porous carbon spheres, c is an SEM image of metal composite powder, and d is a TEM image of metal composite powder). [Figure 2] 1 is an XRD spectrum of the metal composite powder prepared in Example 2 of the present application. [Figure 3] FIG. 2 is a curve diagram showing the temperature change over time at the center point of the tray in the present application. [Figure 4] 1 is a comparative diagram of an aging experiment (left: Example 2 before aging, center: Example 2 after aging, right: Comparative Example 2 after aging). DETAILED DESCRIPTION OF THE INVENTION

[0029] The present application will be explained in more detail in conjunction with examples.

[0030] The raw materials in the examples and comparative examples of this application are generally commercially available unless otherwise specified.

[0031] Example Example 1 This microwave heat generating composition contains the following ingredients as raw materials, in a weight ratio of 20 parts metal composite powder, 10 parts organic silicone rubber composite, 0.2 parts heat resistance agent, and 0.5 parts vulcanizing agent.

[0032] The heat resistant agent is heat resistant agent Bluestar AD703, and the vulcanizing agent is 2,4-dichlorobenzoyl peroxide vulcanizing agent.

[0033] The method for preparing the metal composite powder includes the following steps S1 to S4.

[0034] In S1, 1 g of tetraphenoxysilane, 2.5 mL of ethyl silicate, 60 mL of ethanol, 10 mL of deionized water, and 4.5 mL of 25 wt% aqueous ammonia are mixed and stirred at room temperature for 30 minutes to react, after which 0.5 g of 2,6-dimethyl-1,4-benzenediol and 2.5 mL of 38 wt% formaldehyde solution are added and stirred for 24 hours to react, after which the precipitate is centrifuged to remove it, washed alternately with water and ethanol, and the supernatant is made colorless. Finally, the precipitate is transferred to a watch glass and dried at 60°C.

[0035] In S2, the dried precipitate was first calcined under an argon atmosphere (slowly increasing the temperature to 700 °C at a rate of 2 °C / min and calcining at a constant temperature for 4 h), and finally treated with 1 mol / L NaOH solution for 40 min to obtain hollow porous carbon spheres.

[0036] In S3, 0.5 g of hollow porous carbon spheres and 0.2 g of metal acetate were dispersed in 60 mL of a mixed solution of deionized water, oleic acid, and ethanol, and the mixture was ultrasonicated at a frequency of 20 KHz while stirring at a speed of 600 r / min for 40 minutes. Then, the mixture was reacted at 200°C for 10 hours. The mixture was naturally cooled to room temperature, centrifuged to separate the precipitate, and washed alternately with water and ethanol. The supernatant was then colorless and dried at 60°C. The volume ratio of deionized water, oleic acid, and ethanol in the mixed solution was 1:15:80. The metal acetate was selected from iron acetate, zinc acetate, copper acetate, and nickel acetate. 0.4 Cu 0.2 Zn 0.4 Fe 2.0 Weigh according to O4.

[0037] In S4, the dried precipitate is slowly heated to 780°C at a rate of 3°C / min under an argon atmosphere and then subjected to secondary firing at a constant temperature for 1 hour to obtain a metal composite powder.

[0038] A method for preparing a microwave-heatable composition includes the following steps: (1) uniformly mixing a metal composite powder, an organic silicone rubber composite, a rubber heat resistance agent, and a vulcanizing agent in a certain ratio in a mixer at 60°C to prepare a rubber material; (2) pressing the mixed rubber material into a raw material sheet with a thickness of 3 mm in a rolling mill or an open rubber kneading machine and cooling it to room temperature; and (3) heating the raw material sheet to 150°C under pressure to perform a vulcanization treatment and molding, and then cooling it to room temperature to obtain a microwave-heatable composition.

[0039] Example 2 This microwave heating composition contains as raw materials 35 parts metal composite powder, 11 parts organic silicone rubber composite, 0.6 parts heat resistance agent, and 1.2 parts vulcanizing agent (the weight ratio is 35 parts metal composite powder, 11 parts organic silicone rubber composite, 0.6 parts heat resistance agent, and 1.2 parts vulcanizing agent).

[0040] The heat resistant agent is heat resistant agent SH-826, and the vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane vulcanizing agent.

[0041] The method for preparing the metal composite powder includes the following steps S1 to S4.

[0042] In S1, 1.1 g of tetraphenoxysilane, 2.8 mL of ethyl silicate, 70 mL of ethanol, 11 mL of deionized water, and 5 mL of 25 wt% aqueous ammonia were mixed and stirred at room temperature for 40 minutes to react, after which 0.65 g of 2,6-dimethyl-1,4-benzenediol and 2.8 mL of 38 wt% formaldehyde solution were added and stirred for 30 hours to react, after which the precipitate was centrifuged to remove it, washed alternately with water and ethanol, and the supernatant was made colorless. Finally, the precipitate was transferred to a watch glass and dried at 65°C.

[0043] In S2, the dried precipitate was first calcined under an argon atmosphere (slowly increasing the temperature to 750 °C at a rate of 3 °C / min and calcining at a constant temperature for 4 h), and finally treated with 1 mol / L NaOH solution for 40 min to obtain hollow porous carbon spheres.

[0044] In S3, 0.65 g of hollow porous carbon spheres and 0.3 g of metal acetate were dispersed in 70 mL of a mixed solution of deionized water, oleic acid, and ethanol, and the mixture was ultrasonicated at a frequency of 20 KHz while stirring at a speed of 700 r / min for 50 minutes. After that, the mixture was reacted at 210°C for 11 hours, naturally cooled to room temperature, centrifuged to remove the precipitate, washed alternately with water and ethanol, and the supernatant was colorless and then dried at 65°C. The volume ratio of deionized water, oleic acid, and ethanol in the mixed solution was 1.1:18:90, and the metal acetate was Ni, consisting of iron acetate, zinc acetate, copper acetate, and nickel acetate. 0.4 Cu 0.2 Zn 0.4 Fe 2.0 Weigh according to O4.

[0045] In S4, the dried precipitate is slowly heated to 820°C at a rate of 3°C / min in an argon atmosphere and then subjected to secondary firing at a constant temperature for 1.5 hours to obtain a metal composite powder.

[0046] A method for preparing a microwave-heatable composition includes the following steps: (1) uniformly mixing a metal composite powder, an organic silicone rubber composite, a rubber heat resistance agent, and a vulcanizing agent in a certain ratio in a mixer at 70°C to prepare a rubber material; (2) pressing the mixed rubber material into a raw material sheet with a thickness of 2 mm in a rolling mill or an open rubber kneading machine and cooling it to room temperature; and (3) heating the raw material sheet to 165°C under pressure to perform a vulcanization treatment and molding, and then cooling it to room temperature to obtain a microwave-heatable composition.

[0047] The heat resistant agent is heat resistant agent SH-826, and the vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane vulcanizing agent.

[0048] The organic silicone rubber composite is Dow Corning Silicone Rubber, model number SH-52U.

[0049] Example 3 This microwave heating composition contains as raw materials 50 parts metal composite powder, 12 parts organic silicone rubber composite, 1 part heat resistance agent, and 1.8 parts vulcanizing agent (the weight ratio is 50 parts metal composite powder, 12 parts organic silicone rubber composite, 1 part heat resistance agent, and 1.8 parts vulcanizing agent).

[0050] The heat resistant agent is heat resistant agent Bluestar AD703, and the vulcanizing agent is a platinum vulcanizing agent.

[0051] The method for preparing the metal composite powder includes the following steps S1 to S4.

[0052] In S1, 1.2 g of tetraphenoxysilane, 3 mL of ethyl silicate, 80 mL of ethanol, 12 mL of deionized water, and 5.5 mL of 25 wt% aqueous ammonia were mixed and stirred at room temperature for 50 minutes to react, after which 0.8 g of 2,6-dimethyl-1,4-benzenediol and 3 mL of 38 wt% formaldehyde solution were added and stirred for 36 hours to react, after which the precipitate was centrifuged to remove it, washed alternately with water and ethanol, and the supernatant was made colorless. Finally, the precipitate was transferred to a watch glass and dried at 70°C.

[0053] In S2, the dried precipitate was first calcined under an argon atmosphere (slowly increasing the temperature to 750 °C at a rate of 4 °C / min and calcined at a constant temperature for 5 h), and finally treated with 1 mol / L NaOH solution for 40 min to obtain hollow porous carbon spheres.

[0054] In S3, 0.8 g of hollow porous carbon spheres and 0.4 g of metal acetate were dispersed in 80 mL of a mixed solution of deionized water, oleic acid, and ethanol, and the mixture was ultrasonicated at a frequency of 20 KHz while stirring at a speed of 800 r / min for 60 minutes. After that, the mixture was reacted at 220°C for 12 hours, naturally cooled to room temperature, centrifuged to remove the precipitate, washed alternately with water and ethanol, and the supernatant was colorless and then dried at 70°C. The volume ratio of deionized water, oleic acid, and ethanol in the mixed solution was 1.2:20:100, and the metal acetate was Ni, consisting of iron acetate, zinc acetate, copper acetate, and nickel acetate. 0.4 Cu 0.2 Zn 0.4 Fe2.0 Weigh according to O4.

[0055] In S4, the dried precipitate is slowly heated to 900°C at a rate of 3°C / min under an argon atmosphere and then secondary fired at a constant temperature for 1.5 hours to obtain a metal composite powder.

[0056] A method for preparing a microwave-heatable composition includes the following steps: (1) uniformly mixing a metal composite powder, an organic silicone rubber composite, a rubber heat resistance agent, and a vulcanizing agent in a certain ratio in a mixer at 80°C to prepare a rubber material; (2) pressing the mixed rubber material into a raw material sheet with a thickness of 1 mm in a rolling mill or an open rubber kneading machine and cooling it to room temperature; and (3) heating the raw material sheet to 180°C under pressure to perform a vulcanization treatment and molding, and then cooling it to room temperature to obtain a microwave-heatable composition.

[0057] Comparative Example Comparative Example 1 The procedure was the same as in Example 2, except that oleic acid was not added during the preparation of the metal composite powder.

[0058] Comparative Example 2 The procedure was the same as in Example 2, except that the firing temperature in the metal composite powder preparation step S4 was set to 700°C.

[0059] Comparative Example 3 It is the same as Example 2, except that Ni 0.4 Cu 0.2 Zn 0.4 Fe 2.0 Metal powders containing O4 were prepared according to conventional methods, specifically Fe2O3, CuO, NiO, and ZnO. 0.4 Cu 0.2 Zn 0.4 Fe 2.0 After weighing the powder according to O4, it is mixed intensively in a strong mixer for 12 hours, and the mixed powder is heated to 1500°C in a sintering furnace at 15°C, fired for 24 hours, and then cooled to room temperature. The sintered powder is sand-milled for 36 hours, dried for 72 hours, and passed through a 500-mesh sieve to obtain the metal powder.

[0060] Next, instead of the metal composite powder, metal powder and hollow porous carbon spheres are mixed in a mass ratio of all metal atoms to hollow porous carbon spheres according to Comparative Example 2 to prepare a microwave heat generating composition.

[0061] Comparative Example 4 This example is similar to Example 2, except that during the preparation of the microwave heating composition, nitrile rubber (purchased from Anqing Hualan Technology Co., Ltd.) is used instead of the organic silicone rubber composite, and manganese-zinc ferrite nanocrystals (purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.) are used instead of the metal composite powder.

[0062] Performance Detection Test (1) The microscopic morphology and structure of the hollow porous carbon spheres and metal composite powder prepared in Example 2 were observed using a scanning electron microscope and a transmission electron microscope, and the results are shown in FIG.

[0063] As can be seen from Figures 1(a) and (b), the structure of the hollow porous carbon spheres is porous hollow spherical with uniform size, smooth surface, and particle size of about 170 nm. As can be seen from Figures 1(c) and (d), the structure of the metal composite powder is still porous hollow spherical, but compared to the hollow porous carbon spheres, it has a larger diameter, higher dispersion, a rougher surface, and small particles attached to the inner and outer walls of the hollow porous carbon spheres.

[0064] (2) The particles adhering to the surface of the metal composite powder prepared in Example 2 were subjected to physical phase analysis using an X-ray diffractometer, and the results are shown in FIG.

[0065] As can be seen from FIG. 2, in the metal composite powder prepared in Example 2, the particles adhering to the surfaces of the hollow porous carbon spheres are ferrite powder with a spinel structure phase.

[0066] (3) The microwave-heating compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were attached to the bottom of a microwave oven tray (tray specifications: Φ290), placed in a microwave oven, and heated at a high frequency of 2.45 GHz with 800 W of power. The temperature curve at the center of the tray over time was recorded. The results are shown in Figure 3.

[0067] As can be seen from FIG. 3, the microwave heat generating compositions prepared in Examples 1 to 3 of the present application have a fast temperature rise and a high heat generation temperature.

[0068] (4) The microwave heat generating compositions prepared in Example 2 and Comparative Example 4 were attached to the bottom of a microwave oven tray (tray specifications: Φ290) and heated at 350°C for 2 hours to conduct an aging experiment. The results are shown in Figure 4.

[0069] As can be seen from FIG. 4, the microwave-heated composition prepared in Example 2 of the present application became slightly embrittled after being heated at 350°C for 2 hours and aged, whereas the microwave-heated composition prepared in Comparative Example 4 was already carbonized. Thus, the microwave-heated composition prepared in the present application has superior heat resistance and aging resistance.

[0070] This specific example is merely for the purpose of illustrating the present application and does not limit the present application. Any non-inventive changes to the present example that a person skilled in the art makes as necessary after reading this specification shall be protected by patent law as long as they fall within the scope of protection claimed in this application.

Claims

1. A microwave heat generating composition, characterized in that the weight ratio of raw materials is 20-50 metal composite powder: 10-12 organic silicone rubber composite: 0.2-1 heat resistant agent: 0.5-1.8 vulcanizing agent.

2. The method for preparing the metal composite powder comprises: Step S1: mixing tetraphenoxysilane, ethyl silicate, ethanol, deionized water, and aqueous ammonia in a certain ratio, stirring and reacting for 30 to 50 minutes at room temperature, adding 2,6-dimethyl-1,4-benzenediol and formaldehyde solution, stirring and reacting for 24 to 36 hours, centrifuging to remove the precipitate, washing alternately with water and ethanol to make the supernatant colorless, and finally transferring the precipitate to a watch glass and drying at 60 to 70°C; Step S2: primary firing the dried precipitate under an argon atmosphere, and finally treating it with a NaOH solution for 40 minutes to obtain hollow porous carbon spheres; Step S3: Dispersing hollow porous carbon spheres and metal acetate in a certain ratio in a mixed solution of deionized water, oleic acid, and ethanol, followed by ultrasonic agitation for 40 to 60 minutes, reacting at 200 to 220°C for 10 to 12 hours, naturally cooling to room temperature, centrifuging to remove the precipitate, washing alternately with water and ethanol, making the supernatant colorless, and then drying at 60 to 70°C. and Step S4 of secondary firing the dried precipitate in an argon atmosphere to obtain a metal composite powder.

3. 3. The microwave heating composition according to claim 2, wherein the mass / volume ratio of tetraphenoxysilane, ethyl silicate, ethanol, deionized water, aqueous ammonia, 2,6-dimethyl-1,4-benzenediol, and formaldehyde solution in S1 is (1 to 1.2) g:(2.5 to 3) mL:(60 to 80) mL:(10 to 12) mL:(4.5 to 5.5) mL:(0.5 to 0.8) g:(2.5 to 3) mL.

4. 4. The microwave heating composition according to claim 3, wherein the weight percentage of the ammonia water is 25% and the weight percentage of the formaldehyde solution is 38%.

5. The microwave-heatable composition according to claim 4, wherein the primary firing in step S2 involves slowly raising the temperature to 700-750°C at a rate of 2-4°C / min and firing at a constant temperature for 4-5 hours, and the concentration of the NaOH solution is 1 mol / L.

6. 6. The microwave heat generating composition according to claim 5, wherein the mass-volume ratio of the hollow porous carbon spheres, the metal acetate, and the mixed solution in S3 is (0.5-0.8) g:(0.2-0.4) g:(60-80) mL.

7. The volume ratio of deionized water, oleic acid and ethanol in the mixed solution is (1-1.2):(15-20):(80-100), and the metal acetate is selected from iron acetate, zinc acetate, copper acetate and nickel acetate. ０．４ Cu ０．２ Zn ０．４ Fe ２．０ O ４ The microwave heating composition according to claim 6, characterized in that it is weighed out according to the following formula:

8. The microwave heat generating composition according to claim 7, wherein the secondary baking is performed by slowly raising the temperature to 780 to 900°C at a rate of 3°C / min and baking at a constant temperature for 1 to 1.5 hours.

9. A method for preparing a microwave heat generating composition, based on the microwave heat generating composition according to any one of claims 1 to 8, comprising the following steps: (1) a step of uniformly mixing a metal composite powder, an organic silicone rubber composite, a rubber heat resistance agent, and a vulcanizing agent in a certain ratio in a mixer at 60 to 80°C to prepare a rubber material; (2) a step of pressing the mixed rubber material into a raw material sheet having a thickness of 1 to 3 mm in a rolling mill or an open rubber kneading machine, and cooling to room temperature; and (3) a step of heating the raw material sheet under pressure to 150 to 180°C to perform vulcanization and molding, and cooling to room temperature to obtain a microwave heat generating composition.

10. 10. The method for preparing a microwave heat generating composition according to claim 9, wherein the thickness of the raw material sheet is 1 to 3 mm.

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