Microstructure support electrothermal composite film and preparation method thereof

Abstract

The invention relates to the technical field of electric heating materials, in particular to a microstructure supporting body electric heating composite film and a preparation method thereof.The microstructure supporting body electric heating composite film comprises an upper electrode layer, a lower electrode layer, a heating layer and supporting bodies regularly distributed in the heating layer; insulating layers are arranged on the outer sides of the upper electrode layer and the lower electrode layer; the support body is arranged between the upper electrode layer and the lower electrode layer; the heating layer and the supporting body are connected with the lower electrode layer in a curing manner; the upper electrode layer is attached to the heating layer and the supporting body. The micro-structure supporting body electric heating compound has good supporting performance, mechanical strength and mechanical property, the risk of short circuit is reduced, and the service life of a sandwich structure electric heating film is prolonged; meanwhile, the PTC characteristic is excellent, and the good automatic temperature control performance is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of electric heating materials, and in particular to an electric heating composite film of a microstructure support and a preparation method thereof. Background Art

[0002] With the rapid development of electric heating film floor heating, it has become a comfortable and necessary product for families to improve their living environment. Electric heating film is mainly made of special conductive fillers and insulating polymer resins. It has good PTC (Positive temperature coefficient) characteristics, that is, the resistivity of the material will change sharply at a certain temperature critical point as the temperature of the material or the environment changes. At the same time, it is safe, environmentally friendly, low-cost, flexible and has high electric heating efficiency. It is a high-tech functional material with market prospects.

[0003] Although the polymer PTC composite electric heating film has a wide range of applications, it is limited by the preparation process and has the problems of high driving voltage and uneven heating. Therefore, a new type of electric heating film with a "sandwich" structure, in which the electric heating layer is stacked and assembled in the upper and lower electrode layers, was born. This new type of electric heating film can realize two-dimensional planar electron conduction transmission between the upper and lower electrode layers and achieve synchronous planar heating. It not only shortens the transmission distance of electrons, reduces the driving voltage, but also improves the problem of uneven heating.

[0004] The preparation process of this new type of "sandwich" structure electric heating film requires that both sides of the electric heating layer be in close contact with the electrode layer. However, due to the poor mechanical properties of the electric heating layer, it is very easy to cause the electric heating layer to be thinned and cracked during rolling, resulting in a short circuit between the electrode layers on both sides of the electric heating layer, causing safety accidents.

[0005] It can be seen that this new structure is in urgent need of improvement and development. Summary of the invention

[0006] The present invention is to solve the deficiencies in the prior art, and therefore provides a microstructure support electrothermal composite film and a preparation method thereof. One of the purposes of the present invention is to provide a microstructure support electrothermal composite film, the microstructure support electrothermal composite film comprising an upper electrode layer, a lower electrode layer, a heating layer, a support body regularly distributed inside the heating layer, and an insulating layer arranged on both sides of the electrode layer. Compared with the "sandwich" structure electrothermal film, the introduction of the support body has good self-supporting performance, enhances the mechanical properties, and avoids the short circuit of the two electrodes of the electrothermal film due to external force; at the same time, the support body selects low-melting point glass powder with good linear expansion coefficient and flame retardancy, which improves the safe service life under high temperature operation. The second purpose of the present invention is to provide a microstructure support electrothermal composite film, which has excellent PTC strength and stability and achieves good self-temperature control performance.

[0007] To solve the above problems, the technical solution of the present invention is: In the first aspect, the present invention provides a microstructure support electrothermal composite film, comprising an upper electrode layer, a lower electrode layer, a heating layer, and a support body regularly distributed inside the heating layer; an insulating layer is provided on the outside of the upper electrode layer and the lower electrode layer; the support body is arranged between the upper electrode layer and the lower electrode layer; the heating layer and the support body are connected to the lower electrode layer by curing; and the upper electrode layer is adhered to the heating layer and the support body.

[0008] As a further improvement of the present invention, the support body comprises a current collector metal layer and a current collector substrate; the current collector metal layer is one of copper and aluminum; the support body is obtained by casting, drying and separation by a template method, and the shape of the support body is customized by the template.

[0009] As a further improvement of the present invention, the current collector substrate comprises, by weight: 1 to 20 parts by weight of low melting point glass powder, 1 to 30 parts by weight of polymer resin, and 10 to 90 parts by weight of dispersion solvent.

[0010] As a further improvement of the present invention, the low melting point glass powder has a mesh number of 1500-300 meshes and a particle size of 5-13 μm.

[0011] As a further improvement of the present invention, the electrothermal composite membrane slurry comprises, by weight: 5 to 30 parts by weight of a polymer resin, 5 to 30 parts by weight of a conductive filler, and 40 to 90 parts by weight of a dispersing solvent.

[0012] As a further improvement of the present invention, the polymer resin is one or more of polyimide, thermoplastic polyurethane, polyethylene, polypropylene, vinyl acetate, and polystyrene; Preferably, the conductive filler is one or more of graphite, carbon black, carbon nanotubes, carbon fibers, graphene, silver nanowires, and metal copper powder; Preferably, the dispersing solvent is one or more of dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, isopropanol and n-butanol.

[0013] As a further improvement of the present invention, the thickness of the electric heating layer and the support body regularly distributed inside the heating layer is 50-200 μm.

[0014] As a further improvement of the present invention, the material of the encapsulation layer is one of polyethylene hot melt adhesive, polypropylene hot melt adhesive, ethylene and its copolymer hot melt adhesive, polyester hot melt adhesive, polyamide hot melt adhesive and polyurethane hot melt adhesive.

[0015] In a second aspect, the present invention provides a method for preparing a microstructure support electrothermal composite film, comprising the following steps: Adding corresponding weights of low-melting-point glass powder and polymer resin into a dispersing solvent to form a uniform support slurry under high-speed mechanical stirring; Place a support template on the metal surface of the current collector, pour the support slurry into the template, separate the template after drying, and form a current collector substrate with a support; Dissolving corresponding weights of polymer resin and conductive filler into a dispersing solvent and stirring to form a uniform electrothermal composite film ink; The prepared electrothermal composite membrane slurry is uniformly coated on a current collector substrate having a support body by using an adjustable scraper, and then cured to form an electrothermal composite membrane having a microstructure support body; The double-sided current collector conductive tape is attached to the surface of the electric heating film and plastic-sealed to obtain a microstructure support electric heating composite film with a "sandwich" structure.

[0016] As a further improvement of the present invention, the support slurry is poured into the template and dried at 60-120°C for 8-24 hours. Curing conditions: 50~350℃ for 1~24 h.

[0017] Compared with the prior art, the microstructure support electrothermal composite film provided by the present invention has the following beneficial effects: The support introduced in the present invention enables the "sandwich" structure electric heating film to have good self-supporting performance, enhances the mechanical properties, and prevents the electric heating film from short-circuiting the two electrodes due to external forces. The support introduced in the present invention selects low-melting-point glass powder with good linear expansion coefficient and flame retardancy, which improves the safe service life under high-temperature operation; the microstructure support electric heating composite film of the present invention has excellent PTC strength and stability, and achieves good self-temperature control performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of the microstructure support electrothermal composite membrane of the present invention; Figure 2 It is a schematic diagram of the cross-sectional structure of the microstructure support electrothermal composite membrane of the present invention; Figure 3 It is a top view of the electric heating layer structure in Example 1 of the present invention; Figure 4 A top view of the electric heating layer structure in Example 2 of the present invention; Figure 5 is the electrothermal curve of the electrothermal composite film of the microstructure support in Example 1; Figure 6 The electrothermal curve of the electrothermal composite film of the microstructure support in Example 1 after the bending test.

[0019] In the accompanying drawings, the components represented by the reference numerals are listed as follows: 1. Insulation layer 2. Upper electrode layer; 3. Electric heating layer; 4. Lower electrode layer; 5. Insulation layer; 6. Support body. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0022] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0023] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0024] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0025] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also indicate the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass in the embodiment description of the present application can be a mass unit known in the chemical industry such as µg, mg, g, kg, etc.

[0026] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0027] The first object of the present invention is to provide a microstructure support body electrothermal composite film, comprising an upper electrode layer 2, a lower electrode layer 4, a heating layer 3, a support body 6 regularly distributed inside the heating layer 3, and an insulating layer 1 arranged on both sides of the electrode layer. The heating layer 3 and the support body 6 regularly distributed inside the heating layer 3 are arranged between the upper electrode layer 2 and the lower electrode layer 4; the heating layer 3 and the support body 6 regularly distributed inside the heating layer 3 are connected to the lower electrode layer 4 by curing; the upper electrode layer 2 is attached to the heating layer and the support body 6 regularly distributed inside the heating layer.

[0028] The electrothermal composite membrane of the present invention is composed of an upper electrode layer, a heating layer, a support body and a lower electrode layer, with an insulating layer in between. This structure allows current to flow between the electrode layers and generate heat through the heating layer.

[0029] In particular, the support body is located inside the heating layer, which plays a role in supporting and enhancing the mechanical strength of the electric heating composite film. At the same time, the regular distribution can ensure that the heating layer is heated evenly and prevent local overheating. The hot melt adhesive material used has good insulation and thermal stability, which can effectively protect the internal structure of the electric heating composite film and prevent erosion from the external environment.

[0030] Preferably, the support body comprises a current collector metal layer and a current collector substrate; the current collector metal layer is one of copper and aluminum; the support body is obtained by casting, drying and separation by template method, and the shape of the support body is customized by the template. Copper and aluminum are both good conductive materials with excellent electrical and thermal conductivity, and are suitable for use as current collectors. The shape obtained by casting, drying and separation by template method can be customized as needed to achieve customized production.

[0031] Preferably, the encapsulation layer is one of polyethylene hot melt adhesive, polypropylene hot melt adhesive, ethylene and its copolymer hot melt adhesive, polyester hot melt adhesive, polyamide hot melt adhesive and polyurethane hot melt adhesive. Hot melt adhesive materials such as polyethylene and polypropylene have good insulation and thermal stability, and can effectively prevent the electric heating composite film from being disturbed and damaged by the external environment during operation.

[0032] Preferably, the support comprises, by weight, 1 to 20 parts by weight of low melting point glass powder, 1 to 30 parts by weight of polymer resin, and 10 to 90 parts by weight of a dispersing solvent.

[0033] Preferably, the mesh number of the low melting point glass powder is 1500-300 meshes, and the particle size is 5-13 μm. As a part of the support, the low melting point glass powder can be melted at a relatively low temperature and combined with the polymer resin to form a solid support structure.

[0034] Preferably, the electrothermal composite membrane slurry comprises, by weight, 5 to 30 parts by weight of a polymer resin, 5 to 30 parts by weight of a conductive filler, and 30 to 90 parts by weight of a dispersing solvent.

[0035] Preferably, the polymer resin is one or more of polyimide, thermoplastic polyurethane, polyethylene, polypropylene, vinyl acetate, polystyrene, etc. As a matrix material, it provides flexibility and strength to the electric heating composite film, and different polymer resins can adjust the performance of the electric heating composite film as needed.

[0036] Preferably, the conductive filler is one or more of graphite, carbon black, carbon nanotubes, carbon fibers, graphene, silver nanowires, metal copper powder, and the like.

[0037] Preferably, the dispersing solvent is one or more of dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, isopropanol, n-butanol, etc. The dispersing solvent is used to mix the polymer resin and the conductive filler into a uniform slurry, and different dispersing solvents can affect the fluidity and film-forming properties of the slurry.

[0038] Preferably, the thickness of the electric heating layer and the support body regularly distributed inside the heating layer is 50-200 μm, which improves the conductivity of the electric heating composite film. Different conductive fillers can adjust the resistivity and heating efficiency of the electric heating composite film.

[0039] The microstructure support electrothermal composite film provided by the present invention has a working principle mainly based on the principle of electrothermal conversion. The electrothermal composite film is composed of an upper electrode layer, a heating layer, a support body and a lower electrode layer, with an insulating layer in between. When current passes through the upper electrode layer and the lower electrode layer, the current will flow in the heating layer. Since the heating layer contains conductive fillers, Joule heat will be generated to convert electrical energy into thermal energy. At the same time, the support body is located inside the heating layer, which plays a role in supporting and enhancing the mechanical strength of the electrothermal composite film, and the regular distribution can ensure that the heating layer is heated evenly to prevent local overheating.

[0040] The introduction of the support body enhances the mechanical strength of the electric heating composite film, making it less likely to deform or damage during use. The regular distribution of the support body ensures uniform heating of the heating layer and avoids performance degradation or failure caused by local overheating. The heating layer contains conductive fillers such as graphite, carbon black, carbon nanotubes, etc. These fillers have good electrical conductivity, which makes the electric heating composite film have low resistivity and high heating efficiency. By adjusting the type and content of the conductive filler, the resistivity and heating power of the electric heating composite film can be flexibly adjusted to meet different application requirements. The support body is obtained by casting, drying and separation by the template method, and can be customized in shape and size as needed to achieve customized production. This customized production capability enables the electric heating composite film to adapt to various complex application scenarios and shape requirements. The setting of the insulating layer effectively isolates the electrode layer from the external environment, preventing current leakage and short circuit.

[0041] At the same time, the insulating layer can also protect the internal structure of the electric heating composite film from erosion and damage by the external environment. The selection range of materials such as polymer resins, conductive fillers and dispersed solvents is wide, and they can be flexibly matched according to different application requirements. Different material combinations can give the electric heating composite film different performance characteristics, such as flexibility, strength, temperature resistance, etc. The electric heating composite film converts electrical energy into thermal energy during operation, does not produce harmful substances or emit pollutants, and meets environmental protection requirements. At the same time, since the electric heating composite film has high heating efficiency and good thermal insulation performance, it can save energy and reduce operating costs. The microstructure support body electric heating composite film has a wide range of application prospects, such as heating elements, temperature sensors, thermistors and other fields. Its excellent conductivity, structural stability and customized production capabilities enable it to maintain good performance in various harsh environments.

[0042] The microstructure support electrothermal composite film provided by the present invention has reasonable design, proper material selection, excellent electrical conductivity, heating efficiency, mechanical strength and durability, and is suitable for various occasions requiring electrothermal heating.

[0043] The second object of the present invention is to provide a method for preparing a microstructure support electrothermal composite film, comprising the following steps: (1) Adding corresponding weights of low-melting-point glass powder and polymer resin into a dispersing solvent to form a uniform support slurry under high-speed mechanical stirring; (2) Place a support template on the metal surface of the current collector, pour the support slurry into the template, dry it at 60-120 °C for 8-24 h, and then separate the template to form a current collector substrate with a support; (3) Dissolving corresponding weights of polymer resin and conductive filler into a dispersing solvent and mechanically stirring at high speed to form a uniform electrothermal composite film ink; (4) using an adjustable scraper to evenly coat the electrothermal composite membrane slurry prepared in step (3) on a current collector substrate having a support, and curing at a high temperature of 50 to 350 °C for 1 to 24 h to form an electrothermal composite membrane having a microstructure support; (5) A double-sided current collector conductive tape is attached to the surface of the electric heating film in step (4), and a plastic sealing machine is used to seal it, and the thickness of the packaging layer is 1-5 cm, so as to obtain a microstructure support electric heating composite film with a "sandwich" structure.

[0044] The preparation method of the microstructure support electrothermal composite film provided by the present invention is mainly based on the preparation of support slurry, preparation of electrothermal composite film ink, and coating and curing of electrothermal composite film. Low melting point glass powder and polymer resin are added to a dispersion solvent, and a uniform support slurry is formed by high-speed mechanical stirring. The addition amount of low melting point glass powder and polymer resin needs to be adjusted accordingly according to specific needs to obtain the best support performance. A support template is placed on the metal surface of the current collector, and the support slurry is poured into the template. By controlling the drying temperature and time, the slurry is dried in the template and forms a support. The template is then separated to form a current collector substrate with a support. The polymer resin and the conductive filler are dissolved in the dispersion solvent, and a uniform electrothermal composite film ink is formed by high-speed mechanical stirring. The addition amount of the conductive filler needs to be adjusted according to the conductive performance requirements of the electrothermal composite film. The electrothermal composite film ink is evenly coated on the current collector substrate with a support using an adjustable scraper. By controlling the coating thickness and the curing temperature and time, the electrothermal composite film is formed and cured on the substrate. During the curing process, the polymer resin will undergo a cross-linking reaction to form a stable film structure.

[0045] Formation of the "sandwich" structure: The double-sided current collector conductive tape is attached to the surface of the electric heating film and is sealed with a plastic sealing machine. The plastic sealing layer can provide additional protection and support while maintaining the structural stability and conductive properties of the electric heating composite film. By controlling the thickness of the plastic sealing layer, a microstructure support electric heating composite film with different properties can be obtained.

[0046] By combining low-melting-point glass powder and polymer resin, a stable support structure is formed. This structure can provide good mechanical support and thermal stability, so that the electrothermal composite film is not easy to deform or damage during use. By adjusting the amount of conductive filler added, an electrothermal composite film with excellent conductive properties can be obtained. This electrothermal composite film can generate enough heat at a lower voltage to meet various heating needs. The preparation method provided by the present invention has clear steps, simple operation, and is easy to realize industrial production. Through simple coating and curing steps, an electrothermal composite film with a microstructure support can be prepared.

[0047] The microstructure support electrothermal composite film has a wide range of application prospects, such as in the fields of heating elements, temperature sensors, thermistors, etc. Its excellent electrical conductivity and structural stability enable it to maintain good performance in various harsh environments. The preparation method provided by the present invention uses environmentally friendly dispersing solvents and polymer resins and other materials, reducing pollution to the environment. At the same time, the electrothermal composite film can efficiently convert electrical energy into thermal energy during use, thereby improving energy utilization.

[0048] The technical solution of the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0049] Embodiment 1: A microstructure support electrothermal composite film, the specific material composition and steps in implementation are: (1) 10 g of low-melting-point glass powder and 15 g of thermoplastic polyurethane weighed in parts by weight were added to 30 g of N-methyl-2-pyrrolidone solvent to form a uniform support slurry under high-speed mechanical stirring; (2) Place a support template on the surface of aluminum foil, pour the support slurry into the template, dry it at 60 °C for 10 h, and then separate the template to form a current collector substrate with a support; (3) 10 g of polyethylene and 10 g of carbon black powder weighed in parts by weight were added to 40 g of N-methyl-2-pyrrolidone solvent, and mechanically stirred at high speed to form a uniform electrothermal composite film ink; (4) using an adjustable scraper to evenly coat the electrothermal composite membrane slurry prepared in step (3) on a current collector substrate having a support, and curing at 80°C for 11 h to form an electrothermal composite membrane having a microstructure support; (5) Aluminum foil conductive tape is pasted on the surface of the electric heating film in step (4), and a plastic sealing machine is used to seal it. The thickness of the polyethylene hot melt adhesive sealing layer is 2 cm, and a microstructure support electric heating composite film with a "sandwich" structure is obtained.

[0050] Figure 3This is a top view of the electric heating layer structure in Example 1 of the present invention; the support body is a cylindrical structure.

[0051] The prepared microstructure support electrothermal composite film was subjected to electrothermal performance test and bending test. Figure 5 As shown in the figure, the electric heating film reaches a constant temperature within 100 s under a voltage of 4 V, with a maximum temperature of 50 °C, and can work stably at the highest temperature; Figure 6 As shown in the figure, the heating film can still work normally after being bent 50 times.

[0052] Embodiment 2: (1) 12 g of low-melting-point glass powder and 20 g of polypropylene weighed in parts by weight were added to 35 g of N-methyl-2-pyrrolidone solvent to form a uniform support slurry under high-speed mechanical stirring; (2) Place a support template on the surface of the copper foil, pour the support slurry into the template, dry it at 70 °C for 12 h, and then separate the template to form a current collector substrate with a support; (3) 10 g of polyimide and 20 g of silver nanowires weighed in parts by weight were added to 60 g of dimethylacetamide and mechanically stirred at high speed to form a uniform electrothermal composite film ink; (4) using an adjustable scraper to evenly coat the electrothermal composite membrane slurry prepared in step (3) on a current collector substrate having a support, and curing at 280° C. for 6 h to form an electrothermal composite membrane having a microstructure support; (5) A copper foil conductive tape is attached to the surface of the electric heating film in step (4), and a plastic sealing machine is used to seal it. The thickness of the polyethylene hot melt adhesive sealing layer is 5 cm, and a microstructure support electric heating composite film with a "sandwich" structure is obtained.

[0053] Figure 4 This is a top view of the electric heating layer structure in Example 2 of the present invention; the support body is a rectangular parallelepiped structure.

[0054] The electrothermal performance test and bending test of the prepared microstructure support electrothermal composite film were carried out. Under a voltage of 3V, the electrothermal film reached a constant temperature within 100 seconds, with a maximum temperature of 53°C, and could work stably at the highest temperature; after being bent 40 times, the electrothermal film could still work normally.

[0055] Embodiment 3: (1) 20 g of low-melting-point glass powder and 25 g of polystyrene weighed in parts by weight are added to 80 g of isopropanol solvent to form a uniform support slurry under high-speed mechanical stirring; (2) placing a support template on the surface of aluminum foil, pouring the support slurry into the template, drying at 120 °C for 15 h, and then separating the template to form a current collector substrate with a support; (3) 10 g of thermoplastic polyurethane and vinyl acetate, 25 g of carbon fiber and metallic copper powder weighed in parts by weight were added to 75 g of dimethylformamide, and mechanically stirred at high speed to form a uniform electrothermal composite film ink; (4) using an adjustable scraper to evenly coat the electrothermal composite membrane slurry prepared in step (3) on a current collector substrate having a support, and curing at 90° C. for 15 h to form an electrothermal composite membrane having a microstructure support; (5) Aluminum foil conductive tape is pasted on the surface of the electric heating film in step (4), and a plastic sealing machine is used to seal it. The thickness of the polyurethane hot melt adhesive sealing layer is 3 cm, and a microstructure support electric heating composite film with a "sandwich" structure is obtained.

[0056] The electrothermal performance test and bending test of the prepared microstructure support electrothermal composite film were carried out. Under a voltage of 2.5 V, the electrothermal film reached a constant temperature within 100 s, with a maximum temperature of 65 ℃, and could work stably at the highest temperature; after being bent 45 times, the electrothermal film could still work normally.

[0057] Embodiment 4: (1) 18 g of low-melting-point glass powder, 25 g of polyethylene and polystyrene weighed in parts by weight were added to 90 g of dimethylformamide to form a uniform support slurry under high-speed mechanical stirring; (2) Place a support template on the surface of the copper foil, pour the support slurry into the template, dry it at 60 °C for 24 h, and then separate the template to form a current collector substrate with a support; (3) 10 g of thermoplastic polyurethane and vinyl acetate, 25 g of carbon fiber and metal copper powder weighed in parts by weight are added to 75 g of n-butanol, and mechanically stirred at high speed to form a uniform electrothermal composite film ink; (4) using an adjustable scraper to evenly coat the electrothermal composite membrane slurry prepared in step (3) on a current collector substrate having a support, and curing at 90° C. for 15 h to form an electrothermal composite membrane having a microstructure support; (5) The copper foil conductive tape is adhered to the surface of the electric heating film in step (4), and the film is plastic-sealed by a plastic sealing machine. The thickness of the polyamide hot melt adhesive packaging layer is 5 cm, and a microstructure support electric heating composite film with a "sandwich" structure is obtained.

[0058] The electrothermal performance test and bending test of the prepared microstructure support electrothermal composite film were carried out. Under a voltage of 3.5 V, the electrothermal film reached a constant temperature within 100 s, with a maximum temperature of 45 °C, and could work stably at the highest temperature; after being bent 65 times, the electrothermal film could still work normally.

[0059] Embodiment 5: (1) 25 g of low-melting-point glass powder, 15 g of polyimide and thermoplastic polyurethane weighed in parts by weight were added to 70 g of N-methyl-2-pyrrolidone solvent to form a uniform support slurry under high-speed mechanical stirring; (2) Place a support template on the surface of aluminum foil, pour the support slurry into the template, dry it at 100 °C for 20 h, and then separate the template to form a current collector substrate with a support; (3) 10 g of thermoplastic polyurethane and vinyl acetate, 25 g of carbon fiber and metallic copper powder weighed in parts by weight were added to 75 g of dimethylformamide, and mechanically stirred at high speed to form a uniform electrothermal composite film ink; (4) using an adjustable scraper to evenly coat the electrothermal composite membrane slurry prepared in step (3) on a current collector substrate having a support, and curing at 90° C. for 15 h to form an electrothermal composite membrane having a microstructure support; (5) Aluminum foil conductive tape is pasted on the surface of the electric heating film in step (4), and a plastic sealing machine is used to seal it. The thickness of the polyurethane hot melt adhesive sealing layer is 3 cm, and a microstructure support electric heating composite film with a "sandwich" structure is obtained.

[0060] The electrothermal performance test and bending test of the prepared microstructure support electrothermal composite film were carried out. Under a voltage of 2.5 V, the electrothermal film reached a constant temperature within 100 s, with a maximum temperature of 64 °C, and could work stably at the highest temperature; after being bent 45 times, the electrothermal film could still work normally.

[0061] Embodiment 6: (1) 18 g of low-melting-point glass powder, 25 g of vinyl acetate and polystyrene weighed in parts by weight were added to 90 g of n-butanol to form a uniform support slurry under high-speed mechanical stirring; (2) Place a support template on the surface of the copper foil, pour the support slurry into the template, dry it at 60 °C for 24 h, and then separate the template to form a current collector substrate with a support; (3) 20 g of thermoplastic polyurethane and vinyl acetate, 15 g of carbon fiber and metallic copper powder weighed in parts by weight were added to 80 g of n-butanol, and mechanically stirred at high speed to form a uniform electrothermal composite film ink; (4) using an adjustable scraper to evenly coat the electrothermal composite membrane slurry prepared in step (3) on a current collector substrate having a support, and curing at 100°C for 20 h to form an electrothermal composite membrane having a microstructure support; (5) The copper foil conductive tape is adhered to the surface of the electric heating film in step (4), and the film is sealed by a plastic sealing machine. The thickness of the polyamide hot melt adhesive sealing layer is 4 cm, and a microstructure support electric heating composite film with a "sandwich" structure is obtained.

[0062] The electrothermal performance test and bending test of the prepared microstructure support electrothermal composite film were carried out. Under a voltage of 3.5 V, the electrothermal film reached a constant temperature within 100 s, with a maximum temperature of 46 ℃, and could work stably at the highest temperature; after being bent 65 times, the electrothermal film could still work normally.

[0063] The microstructure support body electric heating composite film prepared by the invention can be applied to fan blades as an electric heating material.

[0064] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A microstructure support electrothermal composite film, characterized in that: It includes an upper electrode layer, a lower electrode layer, a heating layer, and a support body regularly distributed inside the heating layer; an insulating layer is provided on the outside of the upper electrode layer and the lower electrode layer; the support body is arranged between the upper electrode layer and the lower electrode layer; the heating layer and the support body are connected to the lower electrode layer by curing; and the upper electrode layer is adhered to the heating layer and the support body.

2. The microstructure support electrothermal composite film according to claim 1, characterized in that: The support body comprises a current collector metal layer and a current collector substrate; the current collector metal layer is one of copper and aluminum; the support body is obtained by casting, drying and separation by a template method, and the shape of the support body is customized by the template.

3. The microstructure support electrothermal composite film according to claim 2, characterized in that: The current collector substrate comprises, by weight: 1 to 20 parts by weight of low melting point glass powder, 1 to 30 parts by weight of polymer resin, and 10 to 90 parts by weight of a dispersing solvent.

4. The microstructure support electrothermal composite film according to claim 2, characterized in that: The low melting point glass powder has a mesh number of 1500-300 meshes and a particle size of 5-13 μm.

5. The microstructure support electrothermal composite film according to claim 1, characterized in that: The electrothermal composite membrane slurry comprises, by weight: 5 to 30 parts by weight of a polymer resin, 5 to 30 parts by weight of a conductive filler, and 40 to 90 parts by weight of a dispersing solvent.

6. The microstructure support electrothermal composite film according to claim 5, characterized in that: The polymer resin is one or more of polyimide, thermoplastic polyurethane, polyethylene, polypropylene, vinyl acetate, and polystyrene; The conductive filler is one or more of graphite, carbon black, carbon nanotubes, carbon fibers, graphene, silver nanowires, and metal copper powder; The dispersing solvent is one or more of dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, isopropanol and n-butanol.

7. The microstructure support electrothermal composite film according to claim 1, characterized in that: The thickness of the electric heating layer and the support body regularly distributed inside the heating layer is 50-200 μm.

8. The microstructure support electrothermal composite film according to claim 1, characterized in that: The material of the encapsulation layer is one of polyethylene hot melt adhesive, polypropylene hot melt adhesive, ethylene and its copolymer hot melt adhesive, polyester hot melt adhesive, polyamide hot melt adhesive and polyurethane hot melt adhesive.

9. The method for preparing the microstructure support electrothermal composite film according to any one of claims 1 to 8, characterized in that: The following steps are involved: Adding corresponding weights of low-melting-point glass powder and polymer resin into a dispersing solvent to form a uniform support slurry under high-speed mechanical stirring; Place a support template on the metal surface of the current collector, pour the support slurry into the template, separate the template after drying, and form a current collector substrate with a support; Dissolving corresponding weights of polymer resin and conductive filler into a dispersing solvent and stirring to form a uniform electrothermal composite film ink; The prepared electrothermal composite membrane slurry is uniformly coated on a current collector substrate having a support body by using an adjustable scraper, and then cured to form an electrothermal composite membrane having a microstructure support body; The double-sided current collector conductive tape is attached to the surface of the electric heating film and plastic-sealed to obtain a microstructure support electric heating composite film.

10. The method for preparing the microstructure support electrothermal composite film according to claim 9, characterized in that: Pour the support slurry into the template and dry it at 60-120℃ for 8-24 hours. Curing conditions: 50~350℃ for 1~24 h.

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