PTFE-based polymer electrothermal composite material and solvent-free preparation method thereof

Abstract

The invention provides a PTFE-based polymer electrothermal composite material and a solvent-free preparation method thereof. Relates to the technical field of electric heating materials, and the PTFE-based polymer electric heating composite material comprises a PTFE-based electric heating layer, strip-shaped electrodes at the two ends of the PTFE-based electric heating layer, and insulating waterproof layers on the outer sides of the PTFE-based electric heating layer and the strip-shaped electrodes; the strip-shaped electrodes are adhered to the two ends of the surface of the PTFE-based electric heating layer by using conductive slurry, and the PTFE-based electric heating layer comprises a PTFE structural phase, a flexible binder and a conductive phase filler. The PTFE-based polymer electrothermal composite material has the advantages of compact structure, few defects, stable resistance, high product processing consistency and good thermal stability and mechanical property. The solvent-free preparation method can effectively avoid the problems of environmental unfriendliness, harm to human bodies and the like caused by organic solvents.

Description

Technical Field

[0001] The invention relates to the technical field of electric heating materials, in particular to a PTFE-based polymer electric heating composite material and a solvent-free preparation method thereof. Background Art

[0002] Electrothermal materials are materials that can convert electrical energy into thermal energy. Electrothermal materials have a certain degree of conductivity and can generate current under the action of voltage. According to the Joule-Lenz law, the electrons inside the material convert electrical energy into thermal energy through collision and friction, thereby generating heat. Electrothermal materials are used as heating elements in many fields, such as military, industrial, transportation, agriculture and animal husbandry, medical, and civil fields.

[0003] Polymer electrothermal composite materials are two-dimensional flexible composite materials with polymer materials as the main structure and conductive fillers (such as carbon materials, metal powders or fibers) as electron flow carriers. They have the unique advantages of rapid heating, high electrothermal efficiency, large heating area, uniform heating, simple preparation, strong chemical corrosion resistance, and lightness. Usually, the preparation method of polymer-based electrothermal composite materials is mainly solvent dissolution. The solvent dissolution method is to first dissolve the polymer material in a solvent liquid, then add a conductive filler and mix evenly, and then coat or print it on the substrate, and finally dry it to volatilize a large amount of solvent. For example, in patent CN114479640A, solvents are used to prepare composite slurry, super-hydrophobic coating and electrothermal slurry, and an anti-icing composite thin film device is finally prepared by coating method. Although the traditional solvent dissolution method is widely used because of its simple processing technology and low energy consumption, the introduction of a large amount of organic solvents causes serious pollution to the environment during the production process, and may also cause harm to human health. At the same time, organic solvents also increase the cost of raw materials. In addition, the drying temperature has a significant effect on the volatilization of the solvent, which makes the structure of the electrothermal composite material less dense, resulting in unstable resistance and unstable electrothermal performance.

[0004] Therefore, it is crucial to develop a solvent-free, non-melting method for preparing polymer-based electrothermal composites. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a PTFE-based polymer electrothermal composite material and a solvent-free preparation method thereof, which can effectively avoid the problems of being environmentally unfriendly, harmful to the human body, and having a loose material structure caused by organic solvents.

[0006] To achieve the above object, the present invention adopts the following technical solution: In the first aspect, the present invention provides a PTFE-based polymer electrothermal composite material, characterized in that the PTFE-based polymer electrothermal composite material includes a PTFE-based electrothermal layer, strip electrodes arranged at both ends of the PTFE-based electrothermal layer, and an insulating and waterproof layer arranged on the outside of the PTFE-based electrothermal layer and the strip electrodes; the strip electrodes are adhered to the two ends of the surface of the PTFE-based electrothermal layer by using a conductive slurry, wherein the PTFE-based electrothermal layer includes a PTFE structural phase, a flexible binder and a conductive phase filler.

[0007] As a further improvement of the present invention, the thickness of the PTFE-based electric heating layer is 20-200 μm.

[0008] As a further improvement of the present invention, the strip electrodes are made of one or more of aluminum, copper, nickel, stainless steel, titanium and alloys of corresponding metals.

[0009] As a further improvement of the present invention, the insulating waterproof layer is one or more of polyimide, polyethylene terephthalate, and silica gel.

[0010] As a further improvement of the present invention, the flexible binder is one or more of succinonitrile, polyethylene oxide, and polyvinylidene fluoride.

[0011] As a further improvement of the present invention, the conductive phase filler is one or more of graphite, activated carbon, pyrolytic carbon black, hard carbon, conductive carbon black, carbon nanotubes, graphene, carbon fiber, copper powder, nickel powder, aluminum powder, silver powder, iron powder, and silver nanowires.

[0012] As a further improvement of the present invention, the ratio of the PTFE to the conductive phase filler is: 2-20 parts of PTFE and 80-98 parts of the conductive phase filler; the flexible binder accounts for 20-50% of the mass of the conductive phase filler.

[0013] In a second aspect, the present invention provides a solvent-free preparation method of a PTFE-based polymer electrothermal composite material, comprising the following steps: S1, ball milling PTFE and conductive phase filler to fibrillate PTFE and stick the conductive phase filler together to form loosely connected aggregates; S2, adding a flexible binder to the S1 aggregate, performing secondary ball milling to obtain a mixture; S3, rolling the mixture to obtain a PTFE-based electric heating layer; S4, using conductive slurry to adhere the strip electrodes to both ends of the surface of the PTFE-based electric heating layer; S5. Attach an insulating waterproof layer to the outside of the PTFE-based electric heating layer and the strip electrodes to obtain a PTFE-based polymer electric heating composite material.

[0014] As a further improvement of the present invention, in S1, the ratio of the PTFE to the conductive phase filler is: 2-20 parts of PTFE and 80-98 parts of the conductive phase filler, by mass. Optionally, in S2, the flexible binder accounts for 20-50% of the mass of the conductive phase filler; Optionally, in S4, the conductive paste is one or more of conductive copper paste and conductive silver paste.

[0015] As a further improvement of the present invention, in S1 and S2, the ball milling speed is 100-300 rpm, and the ball milling time is 0.5-3 h; Optionally, in S3, the rolling temperature is 80-150°C.

[0016] Through the above technical solution, the present invention has the following advantages: The PTFE-based polymer electrothermal composite material prepared by the present invention has a dense structure, few defects, stable resistance, and high product processing consistency. At the same time, thanks to the excellent intrinsic properties of PTFE, the PTFE-based polymer electrothermal composite material also has outstanding thermal stability and mechanical properties.

[0017] Furthermore, the preparation method of the PTFE-based polymer electrothermal composite material is solvent-free throughout the entire process, which can not only reduce the cost of raw materials, but also avoid the adverse effects caused by organic solvents, such as environmental pollution and harm to the human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of the PTFE-based polymer electrothermal composite material of the present invention; Figure 2 This is a temperature-time curve of a PTFE-based polymer electrothermal composite material in Example 1 under the action of 18 V voltage.

[0019] Explanation of the reference numerals: 1 is a PTFE-based electric heating layer, 2 is a strip electrode, and 3 is an insulating and waterproof layer. 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 aspect of the present invention provides a PTFE-based polymer electrothermal composite material, which includes a PTFE-based electrothermal layer, strip electrodes at both ends of the PTFE-based electrothermal layer, and an insulating and waterproof layer outside the PTFE-based electrothermal layer and the strip electrodes; the strip electrodes are adhered to the two ends of the surface of the PTFE-based electrothermal layer by using a conductive slurry, wherein the PTFE-based electrothermal layer includes a PTFE structural phase, a flexible binder and a conductive phase filler.

[0028] The principle of the PTFE-based polymer electrothermal composite material provided by the present invention is: PTFE (polytetrafluoroethylene) is a polymer material with excellent chemical stability, thermal stability and electrical insulation. By adding flexible binders and conductive fillers, a PTFE-based electric heating layer with electric heating effect can be prepared.

[0029] The strip electrodes are adhered to both ends of the surface of the PTFE-based electric heating layer using conductive slurry, forming input and output channels for current, so that the electric heating layer can generate heat evenly.

[0030] The design of the insulating waterproof layer is to protect the electric heating layer and electrodes from corrosion by the external environment and ensure the safety and stability of the electric heating composite material.

[0031] Through a carefully designed preparation process, a PTFE-based polymer electrothermal composite material with a dense structure and few defects can be obtained, which helps to improve the electrothermal conversion efficiency and stability. In addition, the conductive phase filler in the PTFE-based electrothermal layer is evenly distributed, which makes the resistance stable and the product processing consistency high, ensuring the performance and reliability of the electrothermal composite material. Thanks to the excellent intrinsic properties of PTFE, the PTFE-based polymer electrothermal composite material also has outstanding thermal stability and mechanical properties, and can work stably for a long time in harsh environments.

[0032] Optionally, the thickness of the PTFE-based electric heating layer is 20-200 μm. For example, 50-200 μm, 100-200 μm, 20-100 μm, 20-150 μm, 10-150 μm, 20 μm, 60 μm, 80 μm, 120 μm, 150 μm, 180 μm, 200 μm, etc. can be selected.

[0033] Optionally, the strip electrodes are made of one or more of aluminum, copper, nickel, stainless steel, titanium and alloys of corresponding metals. The metal alloy can be a combination of any metals including aluminum, copper, nickel and titanium.

[0034] Optionally, the insulating waterproof layer is one or more of polyimide (PI), polyethylene terephthalate (PET), and silica gel.

[0035] Optionally, the flexible binder is one or more of succinonitrile (SN), polyethylene oxide (PEO), and polyvinylidene fluoride (PVDF).

[0036] Optionally, the conductive phase filler is one or more of graphite, activated carbon, pyrolytic carbon black, hard carbon, conductive carbon black, carbon nanotubes, graphene, carbon fiber, copper powder, nickel powder, aluminum powder, silver powder, iron powder, and silver nanowires.

[0037] The second aspect of the present invention provides a solvent-free preparation method of the PTFE-based polymer electrothermal composite material according to the first aspect, comprising the following steps: S1, mixing PTFE and conductive phase filler in a certain proportion and placing them in a ball mill, adding ball mill beads, setting the ball mill speed and time for one ball milling, so that the PTFE is fibrillated, and the conductive phase filler can be bonded together to form loosely connected aggregates; S2, adding a certain proportion of flexible binder to the loosely connected aggregates obtained in S1, setting the ball milling speed and time for secondary ball milling to obtain a uniform mixture; S3, rolling the uniform mixture obtained in S2 at a certain temperature to obtain a PTFE-based electric heating layer; S4, using conductive slurry to adhere strip electrodes to both ends of the surface of the PTFE-based electric heating layer prepared in S3; S5. Finally, an insulating waterproof layer is attached to the outside of the PTFE-based electric heating layer and the strip electrodes.

[0038] Regarding the solvent-free preparation method of the PTFE-based polymer electrothermal composite material provided by the present invention, S1: Mixing and ball milling of PTFE and conductive phase filler: PTFE and conductive phase filler (such as carbon black, graphite, metal powder, etc.) are mixed in a certain proportion and placed in a ball mill. Ball milling beads are added, and ball milling is performed once by setting an appropriate ball milling speed and time. In this process, PTFE is fibrillated to form a fibrous structure, and these fibers can stick the conductive phase filler together to form loosely connected aggregates. S2: Adding a flexible binder and secondary ball milling: A certain proportion of flexible binder (such as polyvinyl alcohol, polyethylene glycol, etc.) is added to the loosely connected aggregates obtained in S1. The ball milling speed and time are set again for secondary ball milling, so that the flexible binder is evenly distributed between PTFE and the conductive phase filler to form a uniform mixture. S3: Rolling treatment: The uniform mixture obtained in S2 is rolled at a certain temperature. In this process, the mixture is pressed into a thin sheet to form a PTFE-based electrothermal layer. The selection of rolling temperature and pressure has an important influence on the performance of the electrothermal layer. S4: Adhesion of strip electrodes: Use conductive paste (such as silver paste, copper paste, etc.) to adhere strip electrodes to both ends of the surface of the PTFE-based electric heating layer obtained in S3. These electrodes are used to connect to an external power source to achieve the heating function of the electric heating composite material. S5: Attaching an insulating waterproof layer: Attach an insulating waterproof layer (such as polytetrafluoroethylene film, polyethylene film, etc.) to the outside of the PTFE-based electric heating layer and the strip electrodes. This layer is used to protect the electric heating composite material from damage by the external environment and prevent the intrusion of water and moisture.

[0039] The PTFE-based polymer electrothermal composite material prepared by the present invention has excellent electrothermal performance and mechanical properties. Its electrothermal layer is formed by uniformly mixing PTFE and conductive phase filler, ensuring good electrical conductivity and thermal conductivity. At the same time, the addition of a flexible binder improves the flexibility and durability of the material. Due to the use of a solvent-free preparation method and environmentally friendly materials, the electrothermal composite material prepared by the present invention has less impact on the environment during production and use. In addition, its efficient electrothermal conversion performance helps to save energy and reduce energy consumption.

[0040] The whole preparation process of the present invention is solvent-free, and no organic solvent is used in the preparation process, which reduces the cost of raw materials and avoids the environmental pollution and human health risks that may be caused by organic solvents.

[0041] The solvent-free preparation process not only reduces production costs, but also meets environmental protection requirements and reduces negative impacts on the environment. At the same time, since no harmful solvents are used, the safety of the production process is also improved. PTFE-based polymer electric heating composite materials have good processability and can be made into electric heating elements of various shapes and sizes to meet the needs of different applications.

[0042] The PTFE-based polymer electrothermal composite material and the preparation method thereof provided by the present invention have the advantages of compact structure, stable resistance, outstanding thermal stability and mechanical properties, and the preparation process is environmentally friendly, safe, easy to process and use, and has broad market prospects and application potential.

[0043] Optionally, in step S1, the ratio of PTFE to conductive phase filler is 2-20 parts by mass: PTFE is 80-98 parts by mass. The total is 100 parts, which can be added as needed, for example, 5-20 parts by mass of PTFE and 80-95 parts by mass of conductive phase filler. 10-20 parts by mass of PTFE and 80-90 parts by mass of conductive phase filler; 10-15 parts by mass of PTFE and 85-95 parts by mass of conductive phase filler; 10 parts by mass of PTFE and 90 parts by mass of conductive phase filler, etc.

[0044] Optionally, in step S2, the flexible binder accounts for 20-50% of the mass of the conductive phase filler, more preferably 30-50%, 40-50%, 25-45%.

[0045] Optionally, in steps S1 and S2, the ball milling speed is 100-300 rpm, and the ball milling time is 0.5-3 h.

[0046] Optionally, in step S3, the rolling temperature is 80-150° C., more preferably 100-150° C., 120-150° C., 80-120° C., 100-120° C., 100° C., 130° C., 110° C., 90° C., etc.

[0047] Optionally, in step S4, the conductive paste is one or more of conductive copper paste and conductive silver paste.

[0048] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0049] Embodiment 1: Example 1 provides a PTFE-based polymer electrothermal composite material and a solvent-free preparation method thereof, and the specific steps are as follows: S1. Weigh 0.60 g of spherical graphite, 0.25 g of conductive carbon black, and 0.05 g of carbon nanotubes, premix them, then add 0.10 g of PTFE and place them together in a ball mill, add ball mill beads according to a ball-to-material ratio of 10:1, set the ball mill speed to 100 rpm, and the ball milling time to 2 h. Perform ball milling once to obtain loosely connected aggregates.

[0050] S2, adding 0.27 g of succinonitrile (SN) flexible binder to the loosely connected aggregates obtained in S1, setting the ball milling speed to 100 rpm, the ball milling time to 1 h, and performing secondary ball milling to obtain a uniform mixture; S3, rolling the uniform mixture obtained in S2 at 110° C. to obtain a PTFE-based electric heating layer with a thickness of about 90 μm, and then cutting the layer into a rectangle of 50×60 mm; S4, using conductive silver paste to adhere 5 mm wide copper strip electrodes to both ends of the surface of the PTFE-based electric heating layer prepared in S3; S5. Finally, use polyimide (PI) tape to attach the PI insulating waterproof layer to the outside of the PTFE-based electric heating layer and the strip electrode.

[0051] The structural schematic diagram of a PTFE-based polymer electrothermal composite material obtained in Example 1 is as follows Figure 1 As shown in FIG. 1 , a 18 V DC voltage is connected to both ends of the PTFE-based polymer electrothermal composite material. Due to the effect of the current, the PTFE-based polymer electrothermal composite material immediately heats up. The temperature-time curve collected by the thermocouple is shown in FIG. Figure 2 As shown, the heating temperature can reach 110°C.

[0052] Embodiment 2: Example 2 provides a PTFE-based polymer electrothermal composite material and a solvent-free preparation method thereof, and the specific steps are as follows: S1. Weigh 0.50 g of spherical graphite, 0.1 g of conductive carbon black, 0.2 g of copper powder, and 0.05 g of graphene, premix them, then add 0.15 g of PTFE and place them together in a ball mill, add ball mill beads according to a ball-to-material ratio of 10:1, set the ball mill speed to 200 rpm, and the ball milling time to 1 h. Perform ball milling once to obtain loosely connected aggregates.

[0053] S2, adding 0.34 g of polyethylene oxide (PEO) flexible binder to the loosely connected aggregates obtained in S1, setting the ball milling speed to 150 rpm, the ball milling time to 1 h, and performing secondary ball milling to obtain a uniform mixture; S3, rolling the uniform mixture obtained in S2 at 130°C to obtain a PTFE-based electric heating layer with a thickness of about 60 μm, and then cutting the layer into a rectangle of 50×60 mm; S4, using conductive copper paste to adhere 5 mm wide copper strip electrodes to both ends of the surface of the PTFE-based electric heating layer prepared in S3; S5. Finally, a plastic sealing machine is used to attach the PET insulating waterproof layer to the outside of the PTFE-based electric heating layer and the strip electrodes.

[0054] In Example 2, a PTFE-based polymer electrothermal composite material is obtained. A 15 V DC voltage is connected to both ends of the PTFE-based polymer electrothermal composite material. Due to the effect of the current, the PTFE-based polymer electrothermal composite material immediately generates heat, and the heating temperature can reach 80°C.

[0055] Embodiment 3: Example 3 provides a PTFE-based polymer electrothermal composite material and a solvent-free preparation method thereof, and the specific steps are as follows: S1. Weigh 0.30 g of spherical graphite, 0.30 g of nickel powder, and 0.10 g of conductive carbon black, premix them, then add 0.17 g of PTFE and place them together in a ball mill, add ball mill beads according to a ball-to-material ratio of 10:1, set the ball mill speed to 150 rpm, and the ball milling time to 1.5 h. Perform ball milling once to obtain loosely connected aggregates.

[0056] S2, adding 0.14 g of polyvinylidene fluoride (PVDF) flexible binder to the loosely connected aggregates obtained in S1, setting the ball milling speed to 150 rpm, the ball milling time to 1.5 h, and performing secondary ball milling to obtain a uniform mixture; S3, rolling the uniform mixture obtained in S2 at 100° C. to obtain a PTFE-based electric heating layer with a thickness of about 60 μm, and then cutting the layer into a rectangle with a size of 50×60 mm; S4, using conductive silver paste to adhere 5 mm wide aluminum strip electrodes to both ends of the surface of the PTFE-based electric heating layer prepared in S3; S5. Finally, thermal conductive silicone is coated on the PTFE-based electric heating layer and the outer side of the strip electrode.

[0057] In Example 3, a PTFE-based polymer electrothermal composite material is obtained. A 21 V DC voltage is connected to both ends of the PTFE-based polymer electrothermal composite material. Due to the effect of the current, the PTFE-based polymer electrothermal composite material immediately generates heat, and the heating temperature can reach 85°C.

[0058] Embodiment 4: Example 4 provides a PTFE-based polymer electrothermal composite material and a solvent-free preparation method thereof, and the specific steps are as follows: S1. Weigh 0.60 g of spherical graphite, 0.25 g of conductive carbon black, and 0.05 g of carbon nanotubes, premix them, then add 0.10 g of PTFE and place them together in a ball mill, add ball mill beads according to a ball-to-material ratio of 10:2, set the ball mill speed to 120 rpm, and the ball milling time to 1.5 h. Perform ball milling once to obtain loosely connected aggregates.

[0059] S2, adding 0.27 g of polyethylene oxide (PEO) flexible binder to the loosely connected aggregates obtained in S1, setting the ball milling speed to 130 rpm, the ball milling time to 2.5 h, and performing secondary ball milling to obtain a uniform mixture; S3, rolling the uniform mixture obtained in S2 at 120° C. to obtain a PTFE-based electric heating layer with a thickness of about 100 μm, and then cutting the layer into a rectangle with a size of 50×60 mm; S4, using conductive silver paste to adhere 8 mm wide copper strip electrodes to both ends of the surface of the PTFE-based electric heating layer prepared in S3; S5. Finally, use polyimide (PI) tape to attach the PI insulating waterproof layer to the outside of the PTFE-based electric heating layer and the strip electrode.

[0060] An 18 V DC voltage is connected to both ends of the prepared PTFE-based polymer electrothermal composite material. Due to the action of the current, the PTFE-based polymer electrothermal composite material immediately generates heat. The temperature-time collected by the thermocouple shows that the heating temperature can reach 112°C.

[0061] Embodiment 5: Example 5 provides a PTFE-based polymer electrothermal composite material and a solvent-free preparation method thereof, and the specific steps are as follows: S1. Weigh 0.50 g of carbon nanotubes, 0.1 g of conductive carbon black, 0.2 g of copper powder and nickel powder, and 0.05 g of graphene, premix them, then add 0.15 g of PTFE and place them together in a ball mill, add ball mill beads according to a ball-to-material ratio of 10:1, set the ball mill speed to 50 rpm, and the ball milling time to 2 h. Perform ball milling once to obtain loosely connected aggregates.

[0062] S2, adding 0.34 g of polyvinylidene fluoride (PVDF) flexible binder to the loosely connected aggregates obtained in S1, setting the ball milling speed to 80 rpm, the ball milling time to 2 h, and performing secondary ball milling to obtain a uniform mixture; S3, rolling the uniform mixture obtained in S2 at 130°C to obtain a PTFE-based electric heating layer with a thickness of about 70 μm, and then cutting the layer into a rectangle of 50×60 mm; S4, using conductive copper paste to adhere 6 mm wide copper strip electrodes to both ends of the surface of the PTFE-based electric heating layer prepared in S3; S5. Finally, a plastic sealing machine is used to attach the PET insulating waterproof layer to the outside of the PTFE-based electric heating layer and the strip electrodes.

[0063] In Example 5, a PTFE-based polymer electrothermal composite material is obtained. A 15 V DC voltage is connected to both ends of the PTFE-based polymer electrothermal composite material. Due to the effect of the current, the PTFE-based polymer electrothermal composite material immediately generates heat, and the heating temperature can reach 85°C.

[0064] Embodiment 6: Example 6 provides a PTFE-based polymer electrothermal composite material and a solvent-free preparation method thereof, and the specific steps are as follows: S1. Weigh 0.30 g of activated carbon and pyrolytic carbon black, 0.30 g of nickel powder, and 0.10 g of conductive carbon black, premix them, then add 0.17 g of PTFE and place them together in a ball mill, add ball mill beads according to a ball-to-material ratio of 10:1.5, set the ball mill speed to 180 rpm, the ball milling time to 0.5 h, perform ball milling once, and then obtain loosely connected aggregates.

[0065] S2, adding 0.14 g of succinonitrile flexible binder to the loosely connected aggregates obtained in S1, setting the ball milling speed to 160 rpm, the ball milling time to 0.5 h, and performing secondary ball milling to obtain a uniform mixture; S3, rolling the uniform mixture obtained in S2 at 100° C. to obtain a PTFE-based electric heating layer with a thickness of about 60 μm, and then cutting the layer into a rectangle with a size of 50×60 mm; S4, using conductive silver paste to adhere 7 mm wide aluminum strip electrodes to both ends of the surface of the PTFE-based electric heating layer prepared in S3; S5. Finally, thermal conductive silicone is coated on the PTFE-based electric heating layer and the outer side of the strip electrode.

[0066] In Example 6, a PTFE-based polymer electrothermal composite material is obtained. A 21 V DC voltage is connected to both ends of the PTFE-based polymer electrothermal composite material. Due to the effect of the current, the PTFE-based polymer electrothermal composite material immediately generates heat, and the heating temperature can reach 90°C.

[0067] The PTFE-based polymer electrothermal composite material prepared by the invention can be applied to fan blades as an electrothermal material.

[0068] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, there are other variations and modifications without exceeding the technical solutions described in the claims.

Claims

1. A PTFE-based polymer electrothermal composite material, characterized in that: The PTFE-based polymer electrothermal composite material includes a PTFE-based electrothermal layer, strip electrodes arranged at both ends of the PTFE-based electrothermal layer, and an insulating waterproof layer arranged outside the PTFE-based electrothermal layer and the strip electrodes; the strip electrodes are adhered to both ends of the surface of the PTFE-based electrothermal layer by using conductive slurry, wherein the PTFE-based electrothermal layer includes a PTFE structural phase, a flexible binder and a conductive phase filler.

2. The PTFE-based polymer electrothermal composite material according to claim 1, characterized in that: The thickness of the PTFE-based electric heating layer is 20-200 μm.

3. The PTFE-based polymer electrothermal composite material according to claim 1, characterized in that: The strip electrodes are made of one or more of aluminum, copper, nickel, stainless steel, titanium and alloys of corresponding metals.

4. The PTFE-based polymer electrothermal composite material according to claim 1, characterized in that: The insulating waterproof layer is one or more of polyimide, polyethylene terephthalate, and silica gel.

5. The PTFE-based polymer electrothermal composite material according to claim 1, characterized in that: The flexible binder is one or more of succinonitrile, polyethylene oxide, and polyvinylidene fluoride.

6. The PTFE-based polymer electrothermal composite material according to claim 1, characterized in that: The conductive phase filler is one or more of graphite, activated carbon, pyrolytic carbon black, hard carbon, conductive carbon black, carbon nanotubes, graphene, carbon fiber, copper powder, nickel powder, aluminum powder, silver powder, iron powder, and silver nanowires.

7. The PTFE-based polymer electrothermal composite material according to claim 1, characterized in that: The ratio of the PTFE to the conductive phase filler is: 2-20 parts of PTFE and 80-98 parts of the conductive phase filler; the flexible adhesive accounts for 20-50% of the mass of the conductive phase filler.

8. A solvent-free preparation method of the PTFE-based polymer electrothermal composite material according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, ball milling PTFE and conductive phase filler to fibrillate PTFE and stick the conductive phase filler together to form loosely connected aggregates; S2, adding a flexible binder to the S1 aggregate, performing secondary ball milling to obtain a mixture; S3, rolling the mixture to obtain a PTFE-based electric heating layer; S4, using conductive slurry to adhere the strip electrodes to both ends of the surface of the PTFE-based electric heating layer; S5. Attach an insulating waterproof layer to the outside of the PTFE-based electric heating layer and the strip electrodes to obtain a PTFE-based polymer electric heating composite material.

9. The solvent-free preparation method of the PTFE-based polymer electrothermal composite material according to claim 8, characterized in that: In S1, the ratio of the PTFE to the conductive phase filler is 2-20 parts by mass and 80-98 parts by mass of the conductive phase filler; In S2, the flexible binder accounts for 20-50% of the mass of the conductive phase filler; In S4, the conductive paste is one or more of conductive copper paste and conductive silver paste.

10. The solvent-free preparation method of the PTFE-based polymer electrothermal composite material according to claim 8, characterized in that: In S1 and S2, the ball milling speed is 100-300 rpm, and the ball milling time is 0.5-3 h; In S3, the rolling temperature is 80-150°C.

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