High-thermal-conductivity organic-inorganic composite electrothermal film and preparation method thereof

Abstract

The invention relates to the field of electrothermal materials, and discloses a high-thermal-conductivity organic-inorganic composite electrothermal film, which comprises a fiber skeleton, a polymer-based conductive phase material filled in a gap arranged in the fiber skeleton, and end electrodes arranged at the two ends of the composite electrothermal film, the fiber skeleton has an inner-outer double-layer structure, an inner core layer is a high-thermal-conductivity ceramic particle layer, and a shell layer is a single-phase polymer layer. The organic-inorganic composite electrothermal film disclosed by the invention has excellent heat-conducting property and thermal stability; a heat transmission path formed by the continuous high-thermal-conductivity ceramic particles can quickly lead out heat generated in the electrothermal film to the surface, so that ultrafast thermal response of the electrothermal film is realized. Compared with a traditional electrothermal film, the heating time is greatly shortened, the applied voltage is greatly reduced, it is guaranteed that the constant temperature requirement is rapidly met, and the electrothermal film has high practical value and wide application prospects.

Description

Technical Field

[0001] The invention relates to the field of electric heating materials, and in particular to a high thermal conductivity organic-inorganic composite electric heating film and a preparation method thereof. Background Art

[0002] The electric heating film is a new type of two-dimensional electrothermal composite thin film material. It uses polymer materials as the main structure, conductive materials and other materials are distributed in the polymer, and end electrodes are set at both ends of the electric heating film. When power is turned on, the electrical energy can be converted into thermal energy and radiated from the surface of the electric heating film into the air or transferred to the device to be heated.

[0003] Generally, according to their electric heating performance, they can be divided into high-temperature electric heating films (>150℃) and low-temperature electric heating films (<150℃). High-temperature electric heating films are usually used in high-power heating devices, such as home appliances and military fields; low-temperature electric heating films are mostly used in electric heating film floor heating, medical thermal therapy products, etc. Patent CN118474931A discloses a flexible electric heating film and its preparation method. The prepared electric heating film can still maintain good flexibility under the condition of long-term operation at 120℃.

[0004] However, under current technology, the electric heating film heats up slowly when it is powered on, and the thermal response time is long, and it takes a long time to reach a constant working temperature range. Patent CN117295194A discloses a double-sided heating graphene electric heating film and its preparation method. The thermal response time of the electric heating film is more than 300 seconds, which will be unfavorable for the widespread application of the electric heating film. Therefore, it is very important to develop an electric heating film material that can heat quickly. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a highly thermally conductive organic-inorganic composite electric heating film and a preparation method thereof, using coaxial electrospinning technology to obtain a fiber skeleton with a core layer of highly thermally conductive ceramic particles and a shell layer of a single-phase polymer layer, and filling the gaps in the fiber skeleton with a polymer-based conductive phase material, and the obtained organic-inorganic composite electric heating film has excellent thermal conductivity and thermal stability. The heat transfer path composed of continuous highly thermally conductive ceramic particles in the invention can quickly conduct the heat generated inside the electric heating film to the surface, achieving an ultra-fast thermal response of the electric heating film.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a high thermal conductivity organic-inorganic composite electric heating film, comprising a fiber skeleton, a polymer-based conductive phase material filling the gaps set in the fiber skeleton, and end electrodes arranged at both ends of the composite electric heating film; the fiber skeleton has an inner and outer double-layer structure, the inner core layer is a high thermal conductivity ceramic particle layer, and the outer shell layer is a single-phase polymer layer.

[0007] Preferably, the thickness of the organic-inorganic composite electric heating film is 20-60 μm.

[0008] Preferably, the terminal electrode is one or more of a metal copper bar, a metal aluminum bar or a metal nickel bar.

[0009] Preferably, the high thermal conductivity ceramic particle layer is one or more of glass fiber, aluminum nitride, silicon dioxide, aluminum oxide, silicon boride, and zirconium oxide.

[0010] Preferably, the single-phase polymer layer is one of polyvinylidene fluoride, polyacrylonitrile or polyacrylic acid.

[0011] In a second aspect, the present invention provides a method for preparing a high thermal conductivity organic-inorganic composite electric heating film, characterized in that it comprises the following steps: S1: preparing two coaxial electrospinning slurries, one containing high thermal conductivity ceramic particles and the other containing a single-phase polymer; S2: Use a core-sheath structure for coaxial electrospinning, with a slurry containing high thermal conductivity ceramic particles as the core layer and a slurry containing a single-phase polymer as the shell layer; after spinning, dry the slurry to obtain a fiber skeleton; S3: preparing a conductive ink, pouring it on the fiber skeleton prepared in S2, so that the conductive ink fully penetrates the gaps in the fiber skeleton, and then drying to remove the dispersion solvent to obtain an electric heating film; S4: Roll-pressing the electric heating film obtained in S3 to make its thickness uniform, and finally attaching end electrodes to both ends of the electric heating film.

[0012] Preferably, the slurry containing high thermal conductivity ceramic particles in step S1 is composed of 60-90 parts of high thermal conductivity ceramic particles, 5-30 parts of polymer binder, and 200-500 parts of dispersion solvent; the polymer binder component is the same as the single-phase polymer.

[0013] Preferably, the coaxial electrospinning parameters in step S2 are: voltage of 15-20 kV, distance from needle to collector of 10-20 cm, injection rate of 0.4-0.6 ml / h, and time of 2.5-4 h.

[0014] Preferably, in S4, the drying temperature is 80-130° C., and the drying time is 3-12 h.

[0015] Preferably, the roller pressing pressure in step S5 is 10-25 MPa.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The inner and outer double-layer structure of the fiber skeleton improves the mechanical strength and thermal conductivity of the electric heating film, and has good deformation resistance and tensile strength; the high thermal conductivity ceramic particle layer serves as the inner core layer, which effectively improves the thermal conduction efficiency of the electric heating film, has a fast thermal response, and heats up rapidly, and can reach a constant temperature value in a very short time; the single-phase polymer layer serves as the outer shell layer, which provides good insulation and protection performance, wraps the high thermal conductivity ceramic particles of the inner core layer, and can prevent the ceramic particles from scattering.

[0017] Furthermore, the thickness limit of 20~60μm ensures that the electric heating film has good flexibility and mechanical strength; this thickness is conducive to reducing the thermal resistance of the electric heating film and improving the heat conduction efficiency.

[0018] Furthermore, the metal terminal electrodes provide good electrical conductivity and mechanical strength; the selective use of a variety of metals can adjust the conductivity and cost of the electric heating film according to actual needs.

[0019] Furthermore, the high thermal conductivity ceramic particle layer significantly improves the thermal conductivity of the electric heating film; the selective use of a variety of ceramic particles can adjust the thermal conductivity and cost of the electric heating film according to actual needs.

[0020] Furthermore, the single-phase polymer layer provides good insulation and protection properties; the selective use of multiple polymers can adjust the flexibility and mechanical strength of the electric heating film according to actual needs.

[0021] On the other hand, the method for preparing a highly thermally conductive organic-inorganic composite electric heating film can precisely control the inner and outer double-layer structure of the fiber skeleton by coaxial electrospinning with a core-sheath structure; a conductive network is formed by preparing a conductive ink and filling it in the gaps of the fiber skeleton. The conductive filler (such as graphite, conductive carbon black, metal powder, etc.) in the conductive ink can provide an electron transmission channel to realize the heating function of the electric heating film. One or more of a metal copper strip, a metal aluminum strip, or a metal nickel strip is selected as the terminal electrode. These metal materials have good electrical conductivity and mechanical strength.

[0022] Furthermore, the voltage is 15~20kV, the distance from the needle to the collector is 10~20cm, the injection rate is 0.4~0.6ml / h, and the time is 2.5~4h. These spinning parameters ensure the quality and performance of the fiber skeleton, such as the uniformity and continuity of the fiber skeleton; the stable spinning process is conducive to large-scale production.

[0023] Furthermore, the drying temperature is 80~130℃ and the drying time is 3~12h. These drying temperatures and times can remove the dispersed solvent, make the electric heating film structure more stable, and ensure the quality and performance of the electric heating film; the stable drying process can ensure the complete volatilization of the solvent and the curing of the conductive ink, while avoiding thermal damage to the electric heating film.

[0024] Furthermore, the rolling processing pressure is 10~25 MPa. These appropriate rolling processing pressures can make the thickness of the electric heating film uniform, improve the contact quality between the electric heating film and the end electrode, and ensure the thickness uniformity and mechanical strength of the electric heating film; the stable rolling process is conducive to the large-scale production and quality control of the electric heating film. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are only for explanation purposes and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 Schematic diagram of the structure of a high thermal conductivity organic-inorganic composite electric heating film obtained in Example 1; Figure 2 A schematic diagram of the fiber skeleton structure of a high thermal conductivity organic-inorganic composite electric heating film obtained in Example 1; Figure 3 1 is an electric heating curve of a high thermal conductivity organic-inorganic composite electric heating film obtained in Example 1 at 12 V; Among them, 1. fiber skeleton; 2. polymer-based conductive phase material; 3. single-phase polymer layer; 4. high thermal conductivity ceramic particle layer. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0029] Embodiment 1: Example 1 provides a high thermal conductivity organic-inorganic composite electric heating film and a preparation method thereof, and the specific steps are as follows: (1) Weigh 1.4 g aluminum nitride powder and 0.4 g polyvinylidene fluoride and add them to 8 ml N-methyl-2-pyrrolidone, heat and stir at 80 °C, speed of 500 rpm, and duration for 6 h. Separately weigh 1.6 g polyvinylidene fluoride and add them to 8 ml N-methyl-2-pyrrolidone, heat and stir at 80 °C, speed of 500 rpm, and duration for 3 h.

[0030] (2) The two slurries prepared in step (1) were injected into the core-sheath structure of the coaxial electrospinning propeller, with the slurry containing high thermal conductivity ceramic particles as the core layer and the slurry containing the single-phase polymer as the shell layer. The spinning voltage was set to 15 kV, the distance from the needle to the collector was 15 cm, the injection rate was 0.4 ml / h, and the time was 4 h.

[0031] The advantages of coaxial electrospinning in making electric heating films are mainly reflected in the advantages of structure and performance, production efficiency and cost, and application prospects; coaxial electrospinning technology can produce electric heating films with core-shell structure. This structure enables the electric heating film to have other special properties, such as corrosion resistance and wear resistance, while maintaining high thermal stability; by adjusting the process parameters in the coaxial electrospinning process, such as voltage, solution concentration, flow rate, etc., the diameter of the fibers in the electric heating film can be precisely controlled. This helps to optimize the thermal conductivity and electrical properties of the electric heating film to meet specific application requirements; coaxial electrospinning technology allows the use of a variety of high-performance materials to prepare electric heating films, such as high temperature resistant and highly conductive polymers. The selection and combination of these materials can further improve the performance of the electric heating film.

[0032] From the production perspective, the coaxial electrospinning system can achieve continuous production, which greatly improves the production efficiency of the electric heating film; compared with the traditional preparation method, the coaxial electrospinning technology can produce a large number of electric heating film products more quickly; due to the high efficiency and flexibility of the coaxial electrospinning technology, the production cost of the electric heating film can be reduced; in addition, by optimizing the process parameters and selecting suitable materials, the material consumption and energy consumption can be further reduced, thereby reducing the total cost.

[0033] From the perspective of multi-field applications, the electric heating film prepared by coaxial electrospinning has broad application prospects; for example, in the energy field, the electric heating film can be used for battery separators, electrode materials, etc.; in the biomedical field, the electric heating film can be used for drug carriers, tissue engineering scaffolds, etc.; in the textile industry, the electric heating film can be used to make clothing and textiles with warming function; coaxial electrospinning technology can be customized according to customer needs; by adjusting process parameters and material selection, electric heating film products with different performances can be prepared to meet the needs of different fields and applications.

[0034] (3) Weigh 1.4 g of thermoplastic polyurethane rubber (TPU) and add it to 7 ml of N-methyl-2-pyrrolidone, heat and stir at 80 °C, 400 rpm, and last for 3 h; then add 0.3 g of graphite, 0.2 g of conductive carbon black, 0.02 g of defoaming agent, and 0.02 g of coupling agent and heat and stir again, set the temperature to 80 °C, 600 rpm, and last for 5 h; (4) The fiber skeleton 1 prepared in step (2) is laid flat on a polytetrafluoroethylene (PTFE) plate, and then the conductive ink prepared in step (3) is scraped onto one side of the fiber skeleton 1. After drying in an 80°C forced air oven for 4 h, the fiber skeleton 1 is turned over and the scraping is continued on the other side of the fiber skeleton 1 to allow the conductive ink to fully penetrate the gaps in the fiber skeleton 1. The fiber skeleton 1 is then placed in an 80°C forced air oven for drying for 4 h. The thickness of the two scrapings is 200 μm.

[0035] (5) Roll-press the electric heating film obtained in step (4) at a pressure of 10 MPa and cut the composite electric heating film into pieces of 4×4 cm. 2 The heating film is rectangular in shape, and copper end electrode strips about 3 mm wide are attached to both ends of the heating film.

[0036] The structure of a high thermal conductivity organic-inorganic composite electric heating film obtained in Example 1 is as follows Figure 1 As shown, the polymer-based conductive phase material 2 is filled in the gaps of the fiber skeleton 1. The thickness of the organic-inorganic composite electric heating film is 20 μm. The structure of the fiber skeleton 1 prepared by coaxial electrospinning technology is as follows Figure 2 As shown in FIG. 4 , the core layer is a high thermal conductivity ceramic particle layer 4 and the shell layer is a single-phase polymer layer 3. The composite electric heating film can reach a constant temperature state within 20 s at a DC voltage of 12 V, and the heating temperature is about 60 ° C. The electric heating curve is shown in FIG. Figure 3 shown.

[0037] Embodiment 2: Example 2 provides a high thermal conductivity organic-inorganic composite electric heating film and a preparation method thereof, and the specific steps are as follows: (1) Weigh 1.8 g of glass fiber powder and 0.2 g of polyacrylonitrile and add them to 5 ml of N,N-dimethylformamide, heat and stir at 90 °C, speed at 450 rpm, and time for 5 h. Separately weigh 1.5 g of polyacrylonitrile and add them to 5 ml of N,N-dimethylformamide, heat and stir at 90 °C, speed at 450 rpm, and time for 2 h.

[0038] (2) The two slurries prepared in step (1) were injected into the core-sheath structure of the coaxial electrospinning propeller, with the slurry containing high thermal conductivity ceramic particles as the core layer and the slurry containing the single-phase polymer as the shell layer. The spinning voltage was set to 15 kV, the distance from the needle to the collector was 18 cm, the injection rate was 0.5 ml / h, and the time was 3 h.

[0039] (3) Weigh 1.4 g of polyethersulfone resin (PES) and add it to 7 ml of N-methyl-2-pyrrolidone and heat it. The stirring temperature is set to 80 °C and the speed is 400 rpm for 3 h. Then add 0.4 g of conductive carbon black, 0.1 g of carbon nanotubes, 0.02 g of leveling agent, and 0.04 g of coupling agent and heat and stir again. The stirring temperature is set to 80 °C and the speed is 600 rpm for 5 h. (4) The fiber skeleton 1 prepared in step (2) is laid flat on a polytetrafluoroethylene (PTFE) plate, and then the conductive ink prepared in step (3) is scraped onto one side of the fiber skeleton 1. After drying in a 100°C forced air oven for 3 h, the fiber skeleton 1 is turned over and the scraping is continued on the other side of the fiber skeleton 1 to allow the conductive ink to fully penetrate the gaps in the fiber skeleton 1. The fiber skeleton 1 is placed in a 100°C forced air oven for drying again for 3 h. The thickness of the two scrapings is 150 μm.

[0040] (5) Roll-press the electric heating film obtained in step (4) at a pressure of 20 MPa, and cut the composite electric heating film into pieces of 4×4 cm. 2 The heating film is rectangular in shape, and nickel end electrode strips about 3 mm wide are attached to both ends of the heating film.

[0041] The high thermal conductivity organic-inorganic composite electric heating film obtained in Example 2 can reach a constant temperature state within 25 s at a DC voltage of 9 V, and the heating temperature is about 55 °C. The trend of its electric heating curve is similar to that of Figure 3 The trends shown are basically the same and are omitted here. The thickness of the organic-inorganic composite electric heating film is 40 μm.

[0042] Embodiment 3: Example 3 provides a high thermal conductivity organic-inorganic composite electric heating film and a preparation method thereof, and the specific steps are as follows: (1) Weigh 1.6 g of zirconium oxide powder and 0.4 g of polyacrylic acid and add them to 8 ml of N,N-dimethylacetamide, heat and stir at 90 °C and 450 rpm for 5 h. Separately, weigh 1.2 g of polyacrylic acid and add them to 7 ml of N,N-dimethylacetamide, heat and stir at 90 °C and 450 rpm for 2 h.

[0043] (2) The two slurries prepared in step (1) were injected into the core-sheath structure of the coaxial electrospinning propeller, with the slurry containing high thermal conductivity ceramic particles as the core layer and the slurry containing the single-phase polymer as the shell layer. The spinning voltage was set to 20 kV, the distance from the needle to the collector was 20 cm, the injection rate was 0.6 ml / h, and the time was 2.5 h.

[0044] (3) Weigh 1.2 g of polyacrylic acid (PAA) and add it to 10 ml of N,N-dimethylacetamide, heat and stir at 80 °C, 400 rpm, and last for 3 h; then add 0.3 g of carbon fiber, 0.3 g of graphite, 0.04 g of defoamer, and 0.06 g of coupling agent and heat and stir again, set the temperature to 80 °C, 600 rpm, and last for 5 h; (4) The fiber skeleton 1 prepared in step (2) is laid flat on a polytetrafluoroethylene (PTFE) plate, and then the conductive ink prepared in step (3) is scraped onto one side of the fiber skeleton 1. After drying in a 130°C forced air oven for 6 h, the fiber skeleton 1 is turned over and the scraping is continued on the other side of the fiber skeleton 1 to allow the conductive ink to fully penetrate the gaps in the fiber skeleton 1. The fiber skeleton 1 is then placed in a 90°C forced air oven for drying for 12 h. The thickness of the two scrapings is 200 μm.

[0045] (5) Roll the electric heating film obtained in step (4) at a pressure of 25 MPa and cut the composite electric heating film into pieces of 4×4 cm. 2 Rectangular shape, with aluminum end electrode strips about 3mm wide attached to both ends of the electric heating film.

[0046] The high thermal conductivity organic-inorganic composite electric heating film obtained in Example 3 can reach a constant temperature state within 30 seconds at a DC voltage of 15V, and the heating temperature is about 90°C. The trend of its electric heating curve is similar to Figure 3 The trends shown are basically the same and are omitted here. The thickness of the organic-inorganic composite electric heating film is 60 μm.

[0047] Embodiment 4: Example 4 provides a high thermal conductivity organic-inorganic composite electric heating film and a preparation method thereof, and the specific steps are as follows: (1) Weigh 1.2 g of silica powder and 0.6 g of polyacrylic acid and add them to 5 ml of N,N-dimethylacetamide, heat and stir at 90 °C, speed of 450 rpm, and duration for 5 h. Separately weigh 0.6 g of polyacrylic acid and add them to 5 ml of N,N-dimethylacetamide, heat and stir at 90 °C, speed of 450 rpm, and duration for 2 h.

[0048] (2) The two slurries prepared in step (1) were injected into the core-sheath structure of the coaxial electrospinning propeller, with the slurry containing high thermal conductivity ceramic particles as the core layer and the slurry containing the single-phase polymer as the shell layer. The spinning voltage was set to 20 kV, the distance from the needle to the collector was 10 cm, the injection rate was 0.6 ml / h, and the time was 3 h.

[0049] (3) Weigh 1 g of polyethersulfone resin (PES) and add it to 8 ml of N,N-dimethylacetamide, heat and stir at 90 °C, 600 rpm, and last for 5 h. Then add 0.05 g of graphene, 0.08 g of carbon nanotubes, 0.02 g of defoaming agent, and 0.02 g of coupling agent and heat and stir again. Set the temperature to 90 °C, 400 rpm, and last for 6 h. (4) The fiber skeleton 1 prepared in step (2) is laid flat on a polytetrafluoroethylene (PTFE) plate, and then the conductive ink prepared in step (3) is scraped onto one side of the fiber skeleton 1. After drying in a 130°C forced air oven for 12 h, the fiber skeleton 1 is turned over and the scraping is continued on the other side of the fiber skeleton 1 to allow the conductive ink to fully penetrate the gaps in the fiber skeleton 1. The fiber skeleton 1 is then placed in a 90°C forced air oven for drying for 12 h. The thickness of the two scrapings is 100 μm.

[0050] (5) Roll-press the electric heating film obtained in step (4) at a pressure of 20 MPa, and cut the composite electric heating film into pieces of 4×4 cm. 2 The heating film is rectangular in shape, and copper end electrode strips about 3mm wide are attached to both ends of the heating film.

[0051] The high thermal conductivity organic-inorganic composite electric heating film obtained in Example 3 can reach a constant temperature state within 30 seconds at a DC voltage of 12V, and the heating temperature is about 80°C. The trend of its electric heating curve is similar to Figure 3 The trends shown are basically the same and are omitted here. The thickness of the organic-inorganic composite electric heating film is 30 μm.

[0052] The material selection of the four embodiments is compared horizontally. The core layer material of Embodiment 1 adopts aluminum nitride powder, which has high thermal conductivity; the shell layer material adopts polyvinylidene fluoride, which provides good insulation and mechanical strength; the conductive ink uses thermoplastic polyurethane rubber (TPU) as the matrix, and graphite and conductive carbon black are added to improve the conductivity.

[0053] The core layer material of Example 2 uses glass fiber powder to provide additional mechanical strength and certain thermal conductivity, but the thermal conductivity is lower than that of aluminum nitride; the shell layer material uses polyacrylonitrile, which also provides good insulation and mechanical strength; the conductive ink uses polyethersulfone resin (PES) as the matrix, and adds conductive carbon black and carbon nanotubes. The addition of carbon nanotubes improves the formation of the conductive network.

[0054] The core layer material of Example 3 is zirconium oxide powder, which has a high melting point and high hardness, but its thermal conductivity is between that of aluminum nitride and glass fiber. The shell layer material is polyacrylic acid, which also provides good processability and insulation. The conductive ink uses polyacrylic acid (PAA) as the matrix, with carbon fiber and graphite added. The addition of carbon fiber significantly improves the conductivity and mechanical strength.

[0055] The core layer material of Example 4 is made of silicon dioxide powder, which has good thermal conductivity and fine particle size, but the added content is high, and the comprehensive thermal conductivity is similar to that of glass fiber; the shell layer material is also made of polyacrylic acid, which provides good processability and insulation; the conductive ink uses polyethersulfone resin (PES) as the matrix, which has high strength, and adding a small amount of graphene and carbon nanotubes can greatly improve the conductivity.

[0056] The preparation processes of the four embodiments were compared horizontally. All embodiments used coaxial electrospinning technology, but the spinning voltage, the distance from the needle to the collector, the injection rate and time were different; the spinning voltage of embodiment 3 was the highest and the distance was the farthest, resulting in a larger fiber diameter or a looser structure. In terms of the scraping and drying process of the conductive ink, the scraping thickness and drying conditions vary from embodiment to embodiment, affecting the final performance and structure of the electric heating film; the drying temperature of embodiment 3 was the highest and the time was the longest, resulting in a more stable structure of the electric heating film, but it also increased the manufacturing cost.

[0057] The performance of the electric heating films of the four embodiments is compared horizontally. Embodiment 1 reaches 60°C at 12V and the response time is 20s; Embodiment 2 reaches 55°C at 9V and the response time is 25s; Embodiment 3 reaches 90°C at 15V and the response time is 30s. Obviously, the heating temperature of Embodiment 3 is the highest, but the response time is also the longest.

[0058] The thickness of Example 1 is 20 μm, the thinnest; the thickness of Example 2 is 40 μm; the thickness of Example 3 is 60 μm, the thickest. The thickness affects the flexibility, mechanical strength and heat conduction efficiency of the electric heating film.

[0059] The characteristics of the electric heating films of the four embodiments are summarized as follows: The advantages of Example 1 are moderate heating temperature, short response time, thin thickness, and suitability for occasions with strict space requirements; the disadvantage is that it is limited by the cost and processability of aluminum nitride powder.

[0060] The advantages of Example 2 are lower cost (using glass fiber powder and polyacrylonitrile), moderate heating temperature, and suitability for general applications; the disadvantages are slightly lower thermal conductivity than Example 1 and slightly longer response time.

[0061] The advantages of Example 3 are that the heating temperature is high and it is suitable for occasions requiring high-temperature heating; the addition of carbon fiber improves the mechanical strength; the disadvantages are that it has the longest response time and the largest thickness and may not be suitable for applications requiring high flexibility; and the manufacturing cost is relatively high.

[0062] The advantage of Example 4 is that only a small amount of conductive material is needed to make the material have good conductivity; the disadvantage is that the silicon dioxide powder has a small particle size and a larger content is needed to obtain satisfactory thermal conductivity; at the same time, the cost of graphene and carbon nanotubes is relatively high.

[0063] In summary, the inner and outer double-layer structure of the fiber skeleton 1 improves the mechanical strength and thermal conductivity of the electric heating film, and has good deformation resistance and tensile strength; the high thermal conductivity ceramic particle layer 4 serves as the inner core layer, which effectively improves the thermal conduction efficiency of the electric heating film, has a fast thermal response, and heats up rapidly, and can reach a constant temperature value in a very short time; the single-phase polymer layer 3 serves as the outer shell layer, which provides good insulation and protection performance, and wraps the high thermal conductivity ceramic particles of the inner core layer to prevent the ceramic particles from scattering; the high thermal conductivity ceramic particle layer 4 of the inner core layer can transfer heat quickly, while the single-phase polymer layer 3 of the outer shell layer ensures uniform heat distribution. This inner and outer double-layer structural combination enables the electric heating film to transfer heat more efficiently during the heating process, thereby improving the overall thermal conductivity efficiency; by adjusting the type and filling amount of the polymer-based conductive phase material 2, the electric heating performance of the electric heating film can be further optimized; for example, selecting a material with high conductivity can increase the heating speed of the electric heating film; and appropriately increasing the filling amount can improve the energy storage capacity and thermal stability of the electric heating film. Moreover, the use of organic and inorganic materials at the same time not only utilizes the good flexibility and toughness of organic materials, which helps to improve the impact resistance and fracture resistance of glass films, but also utilizes the higher hardness and strength of inorganic materials, which can provide excellent wear resistance and scratch resistance for glass films; not only utilizes the specific functional groups and chemical reactions of organic materials to further enhance the corrosion resistance of glass films, but also utilizes the fact that they are not easily corroded by chemical substances, which can effectively prevent problems such as aging, discoloration, and yellowing of glass films; not only utilizes organic materials by adding heat stabilizers to improve the stability of glass films at high temperatures, but also utilizes excellent heat resistance, which can be used for a long time in high temperature environments without deformation or failure. Organic / inorganic composite films can also reduce environmental pollution by selecting appropriate materials and preparation processes.

[0064] In addition, in addition to polyvinylidene fluoride PVDF, polyacrylonitrile PAN or polyacrylic acid PAA, the single-phase polymer layer 3 can also use polyisophthalamide PMIA; PMIA is an aromatic polyamide with a polymer chain structure, and exhibits the characteristics of typical polymer materials such as high strength and high modulus; PMIA is insoluble in water, insoluble in organic solvents such as ethanol, acetone, and gasoline, and has excellent chemical stability; due to its excellent flame retardant, high temperature resistant, high strength and other properties, PMIA fibers are widely used in special clothing such as firefighting suits and welding work clothes, as well as in the manufacture of load-bearing structural parts in the automotive, high-speed rail, yacht, aircraft, satellite, missile and other industries; polyisophthalamide PMIA has certain processability and can be processed into products of various shapes and sizes through molding processes such as injection molding, extrusion, and spinning.

[0065] Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

[0066] The above content is a further detailed description of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, they can also make several simple deductions or substitutions, which should be regarded as belonging to the protection scope of the present invention determined by the submitted claims.

Claims

1. A highly thermally conductive organic-inorganic composite electric heating film, characterized in that: It comprises a fiber skeleton (1), a polymer-based conductive phase material (2) filled in gaps arranged in the fiber skeleton (1), and end electrodes arranged at both ends of the composite electric heating film; the fiber skeleton (1) has an inner and outer double-layer structure, the inner core layer is a high thermal conductivity ceramic particle layer (4), and the outer shell layer is a single-phase polymer layer (3).

2. The high thermal conductivity organic-inorganic composite electric heating film according to claim 1, characterized in that: The thickness of the organic-inorganic composite electric heating film is 20-60 μm.

3. The high thermal conductivity organic-inorganic composite electric heating film according to claim 1, characterized in that: The terminal electrode is one or more of a metal copper bar, a metal aluminum bar or a metal nickel bar.

4. The high thermal conductivity organic-inorganic composite electric heating film according to claim 1, characterized in that: The high thermal conductivity ceramic particle layer (4) is one or more of glass fiber, aluminum nitride, silicon dioxide, aluminum oxide, silicon boride, and zirconium oxide.

5. The high thermal conductivity organic-inorganic composite electric heating film according to claim 1, characterized in that: The single-phase polymer layer (3) is one of polyvinylidene fluoride, polyacrylonitrile or polyacrylic acid.

6. A method for preparing a highly thermally conductive organic-inorganic composite electric heating film according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: preparing two coaxial electrospinning slurries, one containing high thermal conductivity ceramic particles and the other containing a single-phase polymer; S2: Using a core-sheath structure for coaxial electrospinning, a slurry containing high thermal conductivity ceramic particles is used as a core layer, and a slurry containing a single-phase polymer is used as a shell layer; after the spinning is completed, a drying process is performed to obtain a fiber skeleton (1); S3: preparing a conductive ink, pouring it on the fiber skeleton (1) prepared in S2, so that the conductive ink fully permeates the gaps in the fiber skeleton (1), and then drying to remove the dispersion solvent, thereby obtaining an electric heating film; S4: Roll-pressing the electric heating film obtained in S3 to make its thickness uniform, and finally attaching end electrodes to both ends of the electric heating film.

7. The method for preparing a highly thermally conductive organic-inorganic composite electric heating film according to claim 6, characterized in that: The slurry containing high thermal conductivity ceramic particles in step S1 is composed of 60-90 parts of high thermal conductivity ceramic particles, 5-30 parts of polymer binder, and 200-500 parts of dispersion solvent; the polymer binder component is the same as the single-phase polymer.

8. The method for preparing a highly thermally conductive organic-inorganic composite electric heating film according to claim 6, characterized in that: The coaxial electrospinning parameters in step S2 are: voltage of 15-20 kV, distance from needle to collector of 10-20 cm, injection rate of 0.4-0.6 ml / h, and time of 2.5-4 h.

9. The method for preparing a highly thermally conductive organic-inorganic composite electric heating film according to claim 6, characterized in that: In the step S4, the drying temperature is 80-130° C. and the drying time is 3-12 h.

10. The method for preparing a highly thermally conductive organic-inorganic composite electric heating film according to claim 6, characterized in that: The roller pressing pressure in step S5 is 10-25 MPa.

Images