Composite heating membrane and preparation method thereof, heating element and heating electric appliance

Abstract

The invention discloses a composite heating membrane and a preparation method thereof, a heating element and a heating electric appliance. The composite heating membrane comprises a heating membrane layer and a shielding membrane layer, the shielding membrane layer is arranged on one side of the heating membrane layer, and the radiance of the shielding membrane layer is smaller than that of the heating membrane layer. The composite heating film comprises the heating film layer with relatively high radiance and the shielding film layer with relatively low radiance, so that the energy utilization rate is effectively improved, and the cooking time is shortened. And meanwhile, the temperature of the shell is reduced, so that the cost of the heating electric appliance is reduced. In addition, the corrosion of the shell material caused by overhigh temperature of the shell is avoided, so that the service life of the heating electric appliance is prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of household appliances, and particularly relates to a composite heating film, a preparation method thereof, a heating element and a heating appliance. BACKGROUND

[0002] The heating appliance such as an electric oven, a microwave oven, a steam oven and the like mainly heats air in a cavity through a heating element and then heats food, or directly heats the surface of food through heat radiation. The heating element used in the above-mentioned heating appliance mainly includes a metal heating tube, a quartz heating tube, a halogen heating tube, a carbon fiber heating tube and a graphene heating element. However, the radiation of these heating tubes has no directionality and is uniformly radiated upward and downward. The heating tube is generally located above and / or below the electric oven. The infrared radiation emitted upward by the heating tube located above the electric oven and the infrared radiation emitted downward by the heating tube located below the electric oven cannot be fully utilized, resulting in that the energy cannot be fully utilized. In addition, since the distance between the heating tube and the upper and lower surfaces of the electric oven is generally close, the temperature of the upper and lower surfaces of the electric oven is relatively high, so that the material of the upper and lower surfaces of the electric oven is also more easily corroded at high temperature. SUMMARY

[0003] The present application aims to at least solve one of the technical problems in the related art. To this end, the present application aims to provide a composite heating film, a preparation method thereof, a heating element and a heating appliance. The composite heating film of the present application includes a heating film layer with relatively large emissivity and a shielding film layer with relatively small emissivity, which not only effectively improves the energy utilization rate and shortens the cooking time, but also reduces the temperature of the outer shell, thereby reducing the cost of the heating appliance. In addition, it also avoids the corrosion of the shell material due to the excessively high temperature of the outer shell, thereby prolonging the service life of the heating appliance.

[0004] In one aspect of the present application, the present application provides a composite heating film. According to an embodiment of the present application, the composite heating film includes:

[0005] a heating film layer;

[0006] a shielding film layer disposed on one side of the heating film layer, the shielding film layer having an emissivity smaller than that of the heating film layer.

[0007] According to the composite heating film sheet, the emissivity of the heating film layer is relatively large, and the emissivity of the shielding film layer is relatively small. The heating film layer with large emissivity is arranged on the side close to the food, and the high emissivity heating film layer can directly act on the food, so that the energy utilization rate is effectively improved, and the cooking time is shortened. Meanwhile, the shielding film layer with small emissivity is arranged on the side close to the heating appliance shell, and the heat radiation is effectively inhibited, so that the energy dissipation is effectively reduced, the shell temperature is reduced, the requirements for the shell material, the shell coating and the heat preservation are reduced, and the cost of the heating appliance is reduced. Meanwhile, the corrosion of the shell material caused by the high temperature of the shell is avoided, and the service life of the heating appliance is prolonged.

[0008] In addition, the composite heating film sheet according to the above-mentioned embodiments of the present application can further have the following additional technical features:

[0009] In some embodiments of the present application, the difference between the emissivity of the heating film layer and the emissivity of the shielding film layer is not less than 0.2.

[0010] In some embodiments of the present application, the difference between the emissivity of the heating film layer and the emissivity of the shielding film layer is not less than 0.6.

[0011] In some embodiments of the present application, the emissivity of the heating film layer is greater than or equal to 0.7 and less than 1.0.

[0012] In some embodiments of the present application, the emissivity of the shielding film layer is not greater than 0.5.

[0013] In some embodiments of the present application, the material of the heating film layer is a carbon-based material.

[0014] In some embodiments of the present application, the material of the heating film layer includes at least one of graphene, artificial graphite, natural graphite and carbon felt.

[0015] In some embodiments of the present application, the shielding film layer includes at least one of a metal shielding film layer and a ceramic shielding film layer.

[0016] In some embodiments of the present application, the material of the metal shielding film layer includes at least one of copper, silver and gold.

[0017] In some embodiments of the present application, the material of the ceramic shielding film layer includes at least one of ZnO, SnO2, ZnS, ITO and ZAO.

[0018] In some embodiments of the present application, the thickness of the heating film layer is 100-300 μm; and / or, the thickness of the shielding film layer is 10-50 μm.

[0019] In a second aspect, the application provides a method for preparing the composite heating film sheet in the above embodiments. According to the embodiments of the application, the method comprises:

[0020] forming a heating film layer;

[0021] forming a shielding film layer on one side of the heating film layer.

[0022] According to the method for preparing the composite heating film sheet in the embodiments of the application, by setting the heating film layer with relatively large emissivity and the shielding film layer with relatively small emissivity, the heating film layer with relatively large emissivity can be set on the side close to the food in a directional installation manner, and the heating film layer with high emissivity can directly act on the food, thereby effectively improving the energy utilization rate and shortening the cooking time. Meanwhile, the shielding film layer with relatively small emissivity is set on the side close to the outer shell of the heating appliance, and the heat radiation can be effectively inhibited, thereby effectively reducing the energy dissipation and the temperature of the outer shell, i.e. reducing the requirements for the outer shell material, the outer shell coating, heat preservation, etc., thereby reducing the cost of the heating appliance. Meanwhile, the corrosion of the shell material caused by the high temperature of the outer shell is avoided, thereby prolonging the service life of the heating appliance.

[0023] In a third aspect, the application provides a heating element. According to the embodiments of the application, the heating element comprises the composite heating film sheet in the above embodiments or the composite heating film sheet prepared by the method in the above embodiments. Thus, the heating element can effectively improve the energy utilization rate, shorten the cooking time, and reduce the requirements for the outer shell material, the outer shell coating, heat preservation, etc. of the heating appliance, thereby reducing the cost of the heating appliance. Meanwhile, the corrosion of the shell material caused by the high temperature of the outer shell is avoided, thereby prolonging the service life of the heating appliance.

[0024] In addition, the heating element according to the above embodiments of the application can have the following additional technical features:

[0025] In some embodiments of the application, the heating element further comprises a sleeve in which the composite heating film sheet is arranged, and a terminal arranged at both ends of the composite heating film sheet.

[0026] In a fourth aspect, this application proposes a heating appliance. According to an embodiment of this application, the heating appliance has the heating element described in the above embodiments. This heating appliance possesses all the features and advantages of the heating element described above, which will not be repeated here. In general, this heating appliance has a high energy utilization rate, thereby shortening cooking time; at the same time, the requirements for its outer casing material, outer casing coating, and insulation are reduced, thereby lowering the cost of the heating appliance; furthermore, it avoids corrosion of the casing material due to excessively high outer casing temperature, thus extending the service life of the heating appliance.

[0027] In addition, the heating appliance according to the above embodiments of this application may also have the following additional technical features:

[0028] In some embodiments of this application, the heating appliance includes at least one of an electric oven, microwave oven, steam oven, electric kettle, electric blanket, electric fan heater, electric heater, bathroom heater, electric ceramic stove, and disinfection cabinet.

[0029] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0030] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0031] Figure 1 This is a cross-sectional schematic diagram of the composite heating film in some embodiments of this application;

[0032] Figure 2 This is a schematic diagram of the cross-section of the composite heating film according to some embodiments of this application;

[0033] Figure 3 This is a cross-sectional schematic diagram of the composite heating film of some other embodiments of this application;

[0034] Figure 4 This is a cross-sectional schematic diagram of the composite heating film of some other embodiments of this application;

[0035] Figure 5 This is a cross-sectional schematic diagram of the composite heating film of some other embodiments of this application;

[0036] Figure 6 This is an exploded view of the heating element in some embodiments of this application;

[0037] Figure 7 These are schematic diagrams of the heating element structure in some embodiments of this application;

[0038] Figure 8This is a cross-sectional schematic diagram of the heating element in some embodiments of this application;

[0039] Figure 9 This is a schematic diagram of the internal temperature rise curves of the oven in Example 1 and Comparative Example 1;

[0040] Figure 10 This is a schematic diagram of the temperature rise curve of the upper inner surface of the oven in Example 1 and Comparative Example 1.

[0041] Figure label:

[0042] 100-Composite heating film, 101-Heating film layer, 102-Shielding film layer, 01-Heating unit, 02-Connecting section, 03-Perforated hole, 200-Sleeve, 300-Terminal. Detailed Implementation

[0043] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0044] This application was filed by the inventor based on the following questions:

[0045] Electric ovens, microwave ovens, and steam ovens primarily use heating elements such as metal heating tubes, quartz heating tubes, halogen heating tubes, carbon fiber heating tubes, and graphene heating elements. However, the radiation from these heating tubes is non-directional, radiating uniformly in all directions. Since the heating tubes are typically located above and / or below the oven, the upward infrared radiation emitted by the upper heating tube and the downward infrared radiation emitted by the lower heating tube cannot be fully utilized, resulting in inefficient energy allocation. For example, graphene heating tubes use graphene films as the heating element, with upward and downward radiation accounting for over 80% of the total radiation. However, the upward (upper heating tube) or downward (lower heating tube) infrared radiation cannot be fully utilized. Furthermore, the radiated heat is dispersed and cannot be effectively concentrated and supplied to the food.

[0046] Furthermore, the temperature range of metal heating tubes is between 550-750 degrees Celsius, that of quartz heating tubes is between 660-800 degrees Celsius, while halogen and carbon fiber heating tubes reach temperatures as high as 1000 degrees Celsius, and graphene heating tubes approach 1300 degrees Celsius. As the heating temperature increases, the temperature of the upper and lower surfaces of the oven also rises, thus placing higher demands on the oven's materials, coating, and insulation, ultimately increasing the cost of the heating appliances.

[0047] Furthermore, since the heating element is generally close to the top and bottom surfaces of the electric oven, the temperature of the top and bottom surfaces of the electric oven is relatively high. As a result, the materials on the top and bottom surfaces of the electric oven are more prone to corrosion at high temperatures, which reduces the service life of the heating appliance.

[0048] In view of this, in one aspect of this application, a composite heating diaphragm is proposed. According to an embodiment of this application, refer to the accompanying drawings. Figure 1 The composite heating film 100 includes a heating film layer 101 and a shielding film layer 102. The shielding film layer 102 is disposed on one side of the heating film layer 101, and the emissivity of the shielding film layer 102 is less than that of the heating film layer 101.

[0049] The beneficial effects of the composite heating film proposed in this application are described in detail below:

[0050] The composite heating film of this application includes a heating film layer and a shielding film layer. The heating film layer has a relatively high emissivity, while the shielding film layer has a relatively low emissivity. By directional installation, the heating film layer with higher emissivity can be placed on the side closer to the food. The high-emissivity heating film layer can directly apply radiation to the food (effectively concentrating the radiation to the food), thereby effectively improving energy utilization and shortening cooking time. Simultaneously, placing the shielding film layer with lower emissivity on the side closer to the heating appliance's outer casing effectively suppresses heat radiation, thereby reducing energy dissipation and lowering the outer casing temperature. This reduces the requirements for outer casing materials, coatings, and insulation, thus lowering the cost of the heating appliance. It also avoids corrosion of the casing material due to excessively high temperatures, thereby extending the service life of the heating appliance.

[0051] In the embodiments of this application, the emissivity mentioned above refers to the ability of an object's surface to release energy in the form of radiation. The emissivity of an object is equal to the ratio of the energy radiated by the object at a certain temperature to the energy radiated by a blackbody at the same temperature. The emissivity of a blackbody is equal to 1, and the emissivity of other objects is between 0 and 1.

[0052] According to some specific embodiments of this application, the difference between the emissivity of the heating film layer and the emissivity of the shielding film layer is not less than 0.2 and less than 1. By limiting the difference between the emissivity of the heating film layer and the emissivity of the shielding film layer within the above range, it is further beneficial that the high-emissivity heating film layer can directly apply radiation to the food, thereby effectively improving energy utilization and shortening cooking time. At the same time, the thermal radiation of the shielding film layer on the low-emissivity side is further effectively suppressed, thereby effectively reducing energy dissipation and lowering the shell temperature.

[0053] According to some specific embodiments of this application, the difference between the emissivity of the heating film layer and the emissivity of the shielding film layer is not less than 0.6 and less than 1. By limiting the difference between the emissivity of the heating film layer and the emissivity of the shielding film layer within the above range, it is further beneficial that the high-emissivity heating film layer can directly apply radiation to the food, thereby effectively improving energy utilization and shortening cooking time. At the same time, the thermal radiation of the shielding film layer on the low-emissivity side is further effectively suppressed, thereby effectively reducing energy dissipation and lowering the shell temperature.

[0054] According to some specific embodiments of this application, the emissivity of the heating film layer is greater than or equal to 0.7 and less than 1.0. Therefore, the emissivity of the heating film layer is relatively high, which further facilitates the heating film layer to directly apply radiation to the food, thereby further improving the energy utilization rate and further shortening the cooking time.

[0055] According to some specific embodiments of this application, the emissivity of the shielding film layer is no greater than 0.5. Therefore, the emissivity of the shielding film layer is relatively low, which further helps to effectively suppress the thermal radiation of the shielding film layer, thereby effectively reducing energy dissipation, further reducing the shell temperature, further reducing the cost of the heating appliance, and further extending the service life of the heating appliance.

[0056] In the embodiments of this application, the material of the heating film layer is not particularly limited, and those skilled in the art can choose according to actual needs. As some preferred options, the material of the heating film layer is a carbon-based material. Carbon-based materials are conductive and have a high thermal emissivity, allowing them to rapidly heat food through radiation after being energized. As some specific embodiments, the material of the heating film layer includes at least one of graphene, artificial graphite, natural graphite, and carbon felt. The emissivity of the heating film layers formed by the above-mentioned materials is relatively high. Specifically, the emissivity of the graphene heating film layer is approximately 0.95, the emissivity of the artificial graphite and natural graphite heating film layers is approximately 0.9, and the emissivity of the carbon felt heating film layer is approximately 0.8. Therefore, the heating film layers formed by the above-mentioned materials all have high emissivity, which further facilitates the direct application of radiation to the food, thereby further improving energy utilization and shortening cooking time.

[0057] In the embodiments of this application, the material of the shielding film layer is not particularly limited, and those skilled in the art can choose according to actual needs. As some preferred solutions, the shielding film layer includes at least one of a metal shielding film layer and a ceramic shielding film layer. Specifically, the material of the metal shielding film layer includes at least one of copper, silver, and gold, and the material of the ceramic shielding film layer includes at least one of zinc oxide (ZnO), tin oxide (SnO2), zinc sulfide (ZnS), indium tin oxide (ITO), and aluminum-doped zinc oxide (ZAO). The emissivity of the shielding film layers of the above-mentioned materials is relatively high, among which the emissivity of the ceramic shielding film layer is approximately 0.2. Therefore, the emissivity of the shielding film layers formed by the above-mentioned materials is relatively low, which further helps to effectively suppress the thermal radiation of the shielding film layer, thereby effectively reducing energy dissipation, further reducing the shell temperature, further reducing the cost of the heating appliance, and further extending the service life of the heating appliance.

[0058] In a preferred embodiment, the heating film layer is a graphene heating film layer, and the shielding film layer is a ceramic shielding film layer. The graphene heating film layer itself is conductive and has a high emissivity. After being energized, it can rapidly heat food through radiation. The ceramic shielding film layer has a low emissivity, which prevents heat from being transferred through radiation, and also has high heat resistance.

[0059] In the embodiments of this application, the heating film layer, as the main body of the composite heating film, has a relatively large thickness. According to some specific embodiments of this application, the thickness of the heating film layer is 100μm-300μm, for example, 100μm, 120μm, 150μm, 170μm, 200μm, 220μm, 250μm, 270μm, 300μm, etc.; the thickness of the shielding film layer is 10μm-50μm, for example, 10μm, 20μm, 30μm, 40μm, 50μm, etc. By limiting the thickness of the heating film layer and the shielding film layer to the above ranges, while ensuring the good heating performance of the composite heating film, it is possible to further ensure that the heating film layer directly radiates onto the food, thereby effectively improving energy utilization and shortening cooking time; at the same time, it is possible to further ensure that the heat radiation of the shielding film layer is effectively suppressed, thereby effectively reducing energy dissipation and lowering the shell temperature. Preferably, the thickness of the heating film layer is 150μm-250μm, and the thickness of the shielding film layer is 30μm-50μm.

[0060] In the embodiments of this application, the specific cut of the composite heating film can be diversified, and those skilled in the art can flexibly design the cut of the composite heating film according to actual needs. The following describes some cuts of the composite heating film based on some specific embodiments of this application:

[0061] In some embodiments of this application, reference is made toFigure 2 The composite heating film includes multiple heating units 01 arranged sequentially along its length, with adjacent heating units 01 spaced apart and connected by connecting sections 02. Therefore, the composite heating film of this application can be cut into various different shapes to meet different usage requirements. In some embodiments of this application, reference is made to... Figure 2 The outer peripheral wall of the heating unit is formed into an oblong or polygonal shape.

[0062] In some embodiments of this application, reference is made to Figure 2 In (b), (c), and (i), each heating unit 01 is provided with a perforated hole 03. Therefore, the perforated hole design can accelerate the heat dissipation rate of the composite heating film and thus accelerate the heating rate of the object to be heated.

[0063] In some embodiments of this application, reference is made to Figure 3 The composite heating film includes a first heating segment S1 and a second heating segment S2 that are adjacent in the length direction. The first heating segment S1 includes multiple connected heating units O1, and the second heating segment S2 includes multiple adjacent heating units O1. The size of the heating unit O1 corresponding to the first heating segment S1 is smaller than the size of the heating unit O1 corresponding to the second heating segment S2, for example... Figure 3 In (a), the length of the heating unit 01 corresponding to the first heating segment S1 is the same as the length of the heating unit 01 corresponding to the second heating segment S2, but their widths d1 and d2 are different. For example... Figure 3 In (b) and (c), the width of the heating unit 01 corresponding to the first heating segment S1 is the same as the width of the heating unit 01 corresponding to the second heating segment S2, but their lengths d1 and d2 are different. This allows for the diversification of composite heating diaphragm structures.

[0064] In some embodiments of this application, reference is made to Figure 4 The first heating section S1 and the second heating section S2 are staggered in the width direction of the composite heating diaphragm. This allows for the diversification of the composite heating diaphragm structure.

[0065] In some embodiments of this application, reference is made to Figure 2 In (d), (e), (f), (h), (i), and (j), the composite heating diaphragm includes multiple notches spaced apart along its length. This allows for diversification of the composite heating diaphragm structure. Furthermore, in some embodiments of this application, referring to... Figure 2 In (i), each notch is defined by a portion of the composite heating film that has been separated from the rest and bent.

[0066] In some embodiments, such as Figure 5As shown, the same composite heating film can also include multiple different cut types, or the same cut type with uneven density distribution.

[0067] In a second aspect, this application provides a method for preparing the composite heating film of the above embodiments. According to an embodiment of this application, the method includes:

[0068] S100: Formation of a heating film layer

[0069] In this step, the specific method for forming the heating film is not particularly limited. As a specific embodiment, the preparation method of the graphene heating film is as follows:

[0070] First, a graphene oxide slurry (i.e., GO slurry) is formed, coated, and dried to form a GO film; then, the edges are trimmed and wound to form a roll GO film, which is then stacked to form a sheet to be fired; then, the sheet to be fired is sequentially carbonized and graphitized at high temperature to form a low-expansion graphene film; finally, after flat pressing, rolling, and coating, a graphene heating film layer is finally formed.

[0071] S200: Forms a shielding film layer

[0072] In this step, a shielding film is formed on one side of the heating film. Different cut heating films obtained after cutting can be referenced. Figure 2 to Figure 5 The specific cutting characteristics are the same as the previous requirements, so I will not go into too much detail here.

[0073] In the embodiments of this application, the specific method for forming a shielding film layer on one side of the heating film layer is not particularly limited. As some specific embodiments, a high-temperature resistant shielding film layer can be deposited on the surface of the heating film layer by methods such as vacuum evaporation coating or magnetron sputtering coating.

[0074] According to the method for preparing a composite heating film according to embodiments of this application, the method involves setting a heating film layer with relatively high emissivity and a shielding film layer with relatively low emissivity. By directional installation, the heating film layer with high emissivity can be positioned closer to the food, allowing it to directly apply radiation to the food, thereby effectively improving energy utilization and shortening cooking time. Simultaneously, positioning the shielding film layer with low emissivity closer to the heating appliance's outer casing effectively suppresses heat radiation, thus reducing energy dissipation and lowering the outer casing temperature. This reduces the requirements for outer casing materials, coatings, and insulation, thereby lowering the cost of the heating appliance. Furthermore, it avoids corrosion of the casing material due to excessively high temperatures, thus extending the service life of the heating appliance.

[0075] In a third aspect, this application proposes a heating element (e.g., a heating tube). According to embodiments of this application, the heating element comprises the composite heating film of the above embodiments or the composite heating film prepared by the methods of the above embodiments. Therefore, this heating element can effectively improve energy utilization, shorten cooking time, and reduce the requirements for the heating appliance's outer casing material, outer casing coating, insulation, etc., thereby reducing the cost of the heating appliance. It also avoids corrosion of the casing material due to excessively high outer casing temperature, thereby extending the service life of the heating appliance.

[0076] According to some specific embodiments of this application, refer to Figure 6 (Area S in the figure refers to a partial cross-sectional view of the casing.) Figure 7 and Figure 8 The heating element also includes a sleeve 200 and terminals 300. The composite heating film 100 is disposed in the sleeve 200, and the terminals 300 are disposed at both ends of the composite heating film 100. The sleeve can be a quartz glass tube, etc.

[0077] In a fourth aspect, this application proposes a heating appliance. According to an embodiment of this application, the heating appliance has the heating element described in the above embodiments. This heating appliance possesses all the features and advantages of the heating element described above, which will not be repeated here. In general, this heating appliance has a high energy utilization rate, thereby shortening cooking time; at the same time, the requirements for its outer casing material, outer casing coating, and insulation are reduced, thereby lowering the cost of the heating appliance; furthermore, it avoids corrosion of the casing material due to excessively high outer casing temperature, thus extending the service life of the heating appliance.

[0078] According to embodiments of this application, the aforementioned heating appliances are electric ovens, microwave ovens, steam ovens, electric kettles, electric blankets, electric fan heaters, electric heaters, bathroom heaters, electric ceramic stoves, or disinfection cabinets.

[0079] Those skilled in the art will understand that, in addition to the heating element mentioned above, heating appliances also include essential structures or components. For example, an electric oven, in addition to the heating element mentioned above, also includes essential structures or components such as a housing, heating space, base, and plug.

[0080] The embodiments of this application are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known methods. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0081] Example 1

[0082] This embodiment provides a composite heating film, the preparation method of which is as follows:

[0083] (1) First, a graphene film with a thickness of 200 μm is prepared as a heating film.

[0084] (2) Then, a ZnO ceramic coating with a thickness of 30 μm is deposited on one side of the graphene film (as a shielding film) by vacuum evaporation coating to obtain a composite heating film.

[0085] Example 2

[0086] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0087] The graphene film has a thickness of 100 μm, and the ceramic coating has a thickness of 10 μm.

[0088] Example 3

[0089] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0090] The graphene film has a thickness of 150 μm, and the ceramic coating has a thickness of 20 μm.

[0091] Example 4

[0092] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0093] The graphene film has a thickness of 250 μm, and the ceramic coating has a thickness of 40 μm.

[0094] Example 5

[0095] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0096] The graphene film has a thickness of 300 μm, and the ceramic coating has a thickness of 50 μm.

[0097] Example 6

[0098] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0099] The graphene film in Example 1 was replaced with an artificial graphite film.

[0100] Example 7

[0101] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0102] The graphene film in Example 1 was replaced with a natural graphite film.

[0103] Example 8

[0104] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0105] The graphene film layer in Example 1 was replaced with a carbon felt film layer.

[0106] Example 9

[0107] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0108] The ZnO ceramic coating in Example 1 was replaced with an indium tin oxide (ITO) ceramic coating.

[0109] Example 10

[0110] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0111] The ZnO ceramic coating in Example 1 was replaced with an aluminum-doped zinc oxide (ZAO) ceramic coating.

[0112] Example 11

[0113] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0114] The ZnO ceramic coating in Example 1 was replaced with a copper metal layer.

[0115] Example 12

[0116] The method in this embodiment is basically the same as that in Embodiment 1, with the only difference being:

[0117] The ZnO ceramic coating in Example 1 was replaced with a silver metal layer.

[0118] Comparative Example 1

[0119] The only difference between this comparative example and Example 1 is that:

[0120] (1) Only a graphene film with a thickness of 230 μm is prepared as a heating film, excluding step (2), that is, excluding the ceramic coating.

[0121] The emissivity of the composite heating films prepared in Examples 1-12 and the graphene heating film prepared in Comparative Example 1 were tested. The test method was as follows: the temperature of each composite heating film was measured using an infrared radiation meter, and the emissivity was adjusted to display the correct temperature, which was then taken as the emissivity of the material. The test results are shown in Table 1.

[0122] The composite heating films prepared in Examples 1-12 and the graphene heating film prepared in Comparative Example 1 were used in ovens. The heating films were located at the top of the oven. By directional installation, the heating film layer with higher emissivity was placed on the side closer to the food, and the shielding film layer with lower emissivity was placed on the side closer to the oven shell. The distance between the composite heating film and the upper or lower inner surface of the oven was 5 cm, and the oven cavity had a capacity of 30 L.

[0123] The oven heating time (heating to 200°C), maximum cavity temperature, maximum temperature of the upper inner surface of the oven, and bread baking time of Examples 1-12 and Comparative Example 1 were tested respectively. The test results are shown in Table 1. Figure 9 This is a schematic diagram of the internal temperature rise curve of the oven in Example 1 and Comparative Example 1. Figure 10 This is a schematic diagram of the temperature rise curve of the upper inner surface of the oven in Example 1 and Comparative Example 1.

[0124] Table 1

[0125]

[0126]

[0127] As shown in Table 1, compared with Comparative Example 1, the time for the oven interior to reach 200°C, the cooking time for bread baking, and the highest temperature on the upper inner surface of the oven in Examples 1-12 were all significantly reduced. Conversely, the highest cavity temperature in Examples 1-12 was significantly increased. This demonstrates that by using a composite heating film comprising a heating film layer with high emissivity and a shielding film layer with low emissivity, energy utilization can be effectively improved, the highest cavity temperature can be effectively increased, and cooking time and the time for the oven interior to reach 200°C can be shortened. Furthermore, placing the shielding film layer with low emissivity on the side closer to the oven shell effectively suppresses heat radiation, thereby effectively reducing energy dissipation and lowering the highest temperature on the upper inner surface of the oven.

[0128] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0129] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A composite heat-generating film sheet, characterized by comprising: The composite heating film sheet comprises: a heating film layer; a shielding film layer disposed on one side of the heating film layer, the shielding film layer having a radiation rate less than that of the heating film layer.

2. The composite heat-generating film sheet according to claim 1, characterized by The difference between the radiation rate of the heating film layer and that of the shielding film layer is not less than 0.

2.

3. The composite heat-generating film sheet according to claim 1, wherein The difference between the radiation rate of the heating film layer and that of the shielding film layer is not less than 0.

6.

4. The composite heat-generating film sheet according to claim 1, wherein The radiation rate of the heating film layer is greater than or equal to 0.7 and less than 1.

0.

5. The composite heat-generating film sheet according to claim 1, wherein The radiation rate of the shielding film layer is not greater than 0.

5.

6. The composite heat-generating film sheet according to any one of claims 1 to 5, characterized by, The material of the heating film layer is a carbon-based material.

7. The composite heat-generating film sheet according to claim 6, wherein The material of the heating film layer comprises at least one of graphene, artificial graphite, natural graphite and carbon felt.

8. The composite heat-generating film sheet according to any one of claims 1 to 5, characterized by, The shielding film layer comprises at least one of a metal shielding film layer and a ceramic shielding film layer.

9. The composite heat-generating film sheet according to claim 8, characterized by The material of the metal shielding film layer comprises at least one of copper, silver and gold.

10. The composite heat-generating film sheet according to claim 8, wherein The material of the ceramic shielding film layer comprises at least one of ZnO, SnO2, ZnS, ITO and ZAO.

11. The composite heat-generating film sheet according to any one of claims 1 to 5, characterized by The thickness of the heating film layer is 100-300 μm. The thickness of the shielding film layer is 10-50 μm.

12. A method of preparing the composite heat-generating film sheet according to any one of claims 1 to 11, characterized by, The composite heating film sheet comprises: forming a heating film layer; forming a shielding film layer on one side of the heating film layer.

13. A heat generating element, characterized by The composite heating film sheet is prepared by the method of any one of claims 1-11.

14. A heat generating element according to claim 13, characterised in that, The composite heating film sheet further comprises: a sleeve in which the composite heating film sheet is disposed; terminals disposed at both ends of the composite heating film sheet.

15. A heating appliance characterized by The heating element comprises the composite heating film sheet of any one of claims 13 or 14.

16. The heating appliance of claim 15, wherein, The heating appliance comprises at least one of an electric oven, a microwave oven, a steam oven, an electric kettle, an electric blanket, an electric heater, an electric radiator, a bathroom heater, an electric ceramic stove and a sterilizer.

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