Flexible carbon fiber electrothermal film and preparation method thereof

Abstract

The present application relates to the technical field of electrothermal composite material, and discloses a flexible carbon fiber electrothermal film and a preparation method thereof.The flexible carbon fiber electrothermal film comprises a flexible carbon fiber film and an electrode layer; wherein the flexible carbon fiber film comprises a modified carbon fiber film and a thermosetting polymer, and the modified carbon fiber film contains carbon fibers and polydopamine; the electrode layer comprises a positive electrode layer and a negative electrode layer, and the positive electrode layer and the negative electrode layer are arranged on the surface of the flexible carbon fiber film; the electrical conductivity of the flexible carbon fiber electrothermal film is 700-2150 S / m, the thermal conductivity is 1.2-2.75 W / (m*K), and the temperature distribution non-uniformity of the stable state at 3 V is less than 0.025.The heating temperature of the flexible carbon fiber electrothermal film is adjustable, controllable and stable, and the flexible carbon fiber electrothermal film exhibits good rapid heating characteristics, high electrothermal radiation conversion efficiency, uniform temperature distribution and safety.

Description

Technical Field

[0001] This invention relates to the field of electrothermal composite materials technology, specifically to a flexible carbon fiber electrothermal film and a method for preparing the flexible carbon fiber electrothermal film. Background Technology

[0002] Over the past decade, the demand for electrothermal materials has increased significantly due to the rapid development of industries such as automotive, healthcare, and aerospace. Traditional electrothermal materials, mainly metal and ceramic-based, suffer from drawbacks such as high density, rigidity, susceptibility to corrosion, complex manufacturing processes, and poor portability, failing to meet the diverse requirements of various industries for electrothermal films. Carbon fiber, with its excellent electrical and thermal conductivity, corrosion resistance, low density, and high specific modulus, coupled with its lower cost, and its lightweight, flexibility, and excellent stability, has made carbon fiber electrothermal films a candidate for next-generation electrothermal materials.

[0003] Compared to traditional metal wire heating materials, carbon fiber heating films offer advantages such as high heating efficiency and good biocompatibility. However, carbon fibers have low surface energy, high inertness, and few active groups, leading to significant carbon fiber agglomeration in directly prepared carbon fiber heating films. This results in uneven temperature distribution within the film, causing overheating in some areas and posing certain safety hazards. Therefore, modifying the carbon fibers is essential for preparing uniformly heated carbon fiber heating films.

[0004] Common methods for modifying carbon fibers, such as liquid-phase oxidation and electrochemical oxidation, use large amounts of organic solvents during the modification process, causing serious environmental pollution and damaging the carbon fiber's structure. As a result, carbon fiber electrothermal films modified by these methods have low electrical conductivity and poor electrothermal performance.

[0005] CN109275212A discloses a novel electrothermal film with PTC effect and its preparation method. The method involves treating the surface of short carbon fibers with dopamine; adding the treated carbon fibers at a weight ratio of 25-60% to a hydrophilic polymer to ensure uniform distribution, thus forming a carbon paste; adding the carbon paste at a weight ratio of 40-70% to a polyurethane emulsion with a solid content of 50-65%, mixing thoroughly, and then coating the mixture onto a substrate to form an electrothermal film with a thickness of 50-150 μm. In this electrothermal film, dopamine forms a hydrophilic coating on the surface of the short carbon fibers. Due to the incompatibility between the hydrophilic polymer and polyurethane, the system is a bicontinuous phase, with the short carbon fibers mainly distributed within the hydrophilic polymer. The dopamine-modified carbon fibers act as conductive fillers. Polyurethane serves as the supporting material for the electrothermal film, providing mechanical properties and dimensional stability. Although this electrothermal film can balance volumetric thermal expansion capacity and supporting capacity, its heating and cooling response time is long; it takes one hour for the surface temperature of the electrothermal film to rise from room temperature to above 80°C. It also takes an hour for the temperature to drop from 84°C to room temperature. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of poor electrical and thermal conductivity and uneven temperature distribution of existing carbon fiber electrothermal films.

[0007] To achieve the above objectives, a first aspect of the present invention provides a flexible carbon fiber electrothermal film, the flexible carbon fiber electrothermal film comprising a flexible carbon fiber film and an electrode layer; wherein, the flexible carbon fiber film comprises a modified carbon fiber film and a thermosetting polymer; the modified carbon fiber film contains carbon fiber and polydopamine;

[0008] The electrode layer includes a positive electrode layer and a negative electrode layer, which are respectively disposed on the surface of the flexible carbon fiber film;

[0009] The flexible carbon fiber electrothermal film has an electrical conductivity of 700-2150 S / m, a thermal conductivity of 1.2-2.75 W / (m·K), and a temperature distribution non-uniformity of less than 0.025 in the steady state at 3V.

[0010] A second aspect of the present invention provides a method for preparing the flexible carbon fiber electrothermal film described in the first aspect, the method comprising:

[0011] (1) The carbon fiber is impregnated in a modifier and the resulting impregnation product is subjected to vacuum pyrolysis to obtain modified carbon fiber; wherein the modifier contains dopamine hydrochloride.

[0012] (2) The modified carbon fiber is mixed with a dispersant to obtain a slurry;

[0013] (3) The slurry is filtered to obtain a modified carbon fiber film;

[0014] (4) In the presence of an organic solvent, the modified carbon fiber film is brought into contact with a polymer, then the organic solvent is removed, and the resulting product is hot-pressed to solidify the polymer and form a flexible carbon fiber film.

[0015] (5) A conductive agent is coated on the surface of the flexible carbon fiber film to form a conductive agent layer, and an electrode layer is covered on the surface of the conductive agent layer.

[0016] Through the above technical solution, the present invention has the following advantages:

[0017] 1. The flexible carbon fiber electrothermal film provided by the present invention uses a modified carbon fiber film with high surface activity as the heating layer and a flexible polymer as the protective layer. It has high electrothermal radiation conversion efficiency, excellent mechanical properties, can be bent at will, high electrical conductivity, and uniform temperature distribution on the surface of the electrothermal film. Its temperature distribution non-uniformity is less than 0.025, preferably not higher than 0.02, which can effectively avoid local high temperature.

[0018] 2. In the flexible carbon fiber electrothermal film provided by the present invention, the modified carbon fibers in the modified carbon fiber film form a network structure, which makes the flexible electrothermal film conductive. The resistivity of the electrothermal film can be adjusted by changing the proportion of the modified carbon fiber film in the flexible carbon fiber electrothermal film.

[0019] 3. The flexible carbon fiber electrothermal film provided by this invention operates at a safe DC voltage of less than 12V, ensuring safety for human use. The stable electrothermal temperature can be adjusted by voltage and will not cause a fire.

[0020] 4. The flexible carbon fiber electrothermal film provided by this invention is portable, lightweight, bendable, and has a long service life;

[0021] 5. The preparation method provided by the present invention uses a process of vacuum pyrolysis combined with filtration-hot pressing to prepare flexible carbon fiber electrothermal film, which has a low preparation cost. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a flexible carbon fiber electrothermal film according to a specific embodiment of the present invention;

[0023] Figure 2 This is a SEM image of the carbon fiber before modification in Example 1 of this invention;

[0024] Figure 3 This is a SEM image of the modified carbon fiber in Example 1 of this invention;

[0025] Figure 4 The temperature-time curves of the flexible carbon fiber electrothermal film with a size of 4cm*5cm prepared in Example 1 of the present invention under different voltages are shown. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] In this invention, the term "thermal conductivity" refers to "in-plane thermal conductivity".

[0028] In this invention, unless otherwise stated, room temperature means 25±2℃.

[0029] The first aspect of the present invention provides a flexible carbon fiber electrothermal film, the flexible carbon fiber electrothermal film comprising a flexible carbon fiber film and an electrode layer; wherein, the flexible carbon fiber film comprises a modified carbon fiber film and a thermosetting polymer; the modified carbon fiber film contains carbon fiber and polydopamine;

[0030] The electrode layer includes a positive electrode layer and a negative electrode layer, which are respectively disposed on the surface of the flexible carbon fiber film;

[0031] The flexible carbon fiber electrothermal film has an electrical conductivity of 700-2150 S / m, a thermal conductivity of 1.2-2.75 W / (m·K), and a temperature distribution non-uniformity of less than 0.025 in the steady state at 3V.

[0032] According to some embodiments of the present invention, the positive electrode layer and the negative electrode layer are respectively disposed on the surface of the flexible carbon fiber film, preferably disposed on the surface at both ends of the flexible carbon fiber film.

[0033] According to some embodiments of the present invention, preferably, the width of the electrode layer is 2-5 mm.

[0034] According to some embodiments of the present invention, preferably, the thickness of the electrode layer is 0.01-0.1 mm.

[0035] According to some embodiments of the present invention, preferably, the electrode layer is selected from conductive copper foil and / or conductive aluminum foil. More preferably, the positive electrode layer and the negative electrode layer are the same; for example, when the positive electrode layer is conductive copper foil, the negative electrode layer is also conductive copper foil.

[0036] According to some embodiments of the present invention, preferably, a conductive agent layer is further disposed between the electrode layer and the flexible carbon fiber film. The conductive agent layer is used to connect the flexible carbon fiber film and the electrode layer.

[0037] According to some embodiments of the present invention, preferably, the width of the conductive agent layer is the same as the width of the electrode layer.

[0038] According to some embodiments of the present invention, preferably, the thickness of the conductive agent layer is 0.01-0.05 mm.

[0039] According to some embodiments of the present invention, preferably, the conductive agent layer contains silver powder and a binder. Preferably, the conductive agent layer is prepared from conductive silver paste.

[0040] According to some embodiments of the present invention, preferably, the thermosetting polymer is polydimethylsiloxane.

[0041] According to some embodiments of the present invention, preferably, the areal density of the modified carbon fiber film is 40-160 g / m³. 2 .

[0042] According to some embodiments of the present invention, preferably, the length of the carbon fiber is 1-6 mm.

[0043] According to some embodiments of the present invention, preferably, the thickness of the flexible carbon fiber film is 0.1-1 mm.

[0044] According to some embodiments of the present invention, preferably, the content of modified carbon fiber film in the flexible carbon fiber film is greater than 0 and not higher than 80 wt%. Preferably, by adjusting the mass and areal density of the modified carbon fiber film in the flexible carbon fiber electrothermal film, electrothermal films with different resistivity and different heating and temperature rise effects can be obtained.

[0045] According to some embodiments of the present invention, the flexible carbon fiber electrothermal film has excellent flexibility and can be bent arbitrarily.

[0046] According to some embodiments of the present invention, preferably, the temperature distribution non-uniformity of the flexible carbon fiber electrothermal film in a stable state at 3V is not higher than 0.02.

[0047] According to some embodiments of the present invention, preferably, the temperature distribution non-uniformity of the flexible carbon fiber electrothermal film in a stable state at 1V is 0.01-0.015.

[0048] According to some embodiments of the present invention, the flexible carbon fiber electrothermal film has excellent electrical conductivity and electrothermal properties, and a uniform temperature distribution.

[0049] This invention provides an exemplary structural schematic diagram of a flexible carbon fiber electrothermal film according to a specific embodiment, as shown below. Figure 1 As shown in the figure, the flexible carbon fiber electrothermal film includes a flexible carbon fiber film and an electrode layer. The flexible carbon fiber film comprises a modified carbon fiber film and a thermosetting polymer. The modified carbon fiber film contains carbon fiber and polydopamine. The electrode layer includes a positive electrode layer and a negative electrode layer, which are respectively disposed on the surfaces at both ends of the flexible carbon fiber film. A conductive agent layer is also disposed between the electrode layer and the flexible carbon fiber film. The width of the conductive agent layer is the same as the width of the electrode layer. After the electrode layer is connected to a DC power supply, the flexible carbon fiber film achieves a conductive path, thus generating heat.

[0050] A second aspect of the present invention provides a method for preparing the flexible carbon fiber electrothermal film described in the first aspect, the method comprising:

[0051] (1) The carbon fiber is impregnated in a modifier and the resulting impregnation product is subjected to vacuum pyrolysis to obtain modified carbon fiber; wherein the modifier contains dopamine hydrochloride.

[0052] (2) The modified carbon fiber is mixed with a dispersant to obtain a slurry;

[0053] (3) The slurry is filtered to obtain a modified carbon fiber film;

[0054] (4) In the presence of an organic solvent, the modified carbon fiber film is brought into contact with a polymer, then the organic solvent is removed, and the resulting product is hot-pressed to solidify the polymer and form a flexible carbon fiber film.

[0055] (5) A conductive agent is coated on the surface of the flexible carbon fiber film to form a conductive agent layer, and an electrode layer is covered on the surface of the conductive agent layer.

[0056] According to some embodiments of the present invention, in step (1), dopamine-modified carbon fibers from marine mussels are used and subjected to vacuum pyrolysis, avoiding the use of solvents to treat the carbon fibers. This process is simple, low-cost, and yields a flexible carbon fiber electrothermal film with excellent conductivity and uniform temperature distribution. Furthermore, currently, vacuum-pyrolyzed dopamine-modified carbon fibers have not been directly used in the preparation of electrothermal films.

[0057] According to some embodiments of the present invention, in step (1), impregnating the carbon fiber in a modifier enables dopamine to polymerize on the surface of the carbon fiber, thereby improving the surface activity and interfacial bonding ability of the carbon fiber.

[0058] According to some embodiments of the present invention, preferably, in step (1), the modifier further contains tris(hydroxymethyl)aminomethane and water to provide an alkaline environment.

[0059] According to some embodiments of the present invention, preferably, the pH value of the modifier is 8-9.

[0060] According to some embodiments of the present invention, preferably, the concentration of dopamine hydrochloride in the modifier is 2-6 mg / mL. Preferably, the modifier can be prepared by dissolving 2-4 g / L of dopamine hydrochloride in a 0.01 mol / L Tris solution.

[0061] According to some embodiments of the present invention, preferably, in step (1), the soaking time is 12-24 hours.

[0062] According to some embodiments of the present invention, in step (1), the vacuum pyrolysis not only maintains the activity of the modified carbon fiber but also improves its conductivity. The vacuum pyrolysis can be performed using a vacuum oven, with no particular limitation. Preferably, the conditions for the vacuum pyrolysis include a temperature of 120-140°C and a time of 10-12 hours. Using the above preferred embodiments is beneficial for improving the conductivity and electrothermal performance of the flexible carbon fiber electrothermal film.

[0063] According to some embodiments of the present invention, preferably, step (1) further includes pretreating the carbon fiber to remove the gum and impurities on the surface of the carbon fiber. The pretreatment includes: sequentially ultrasonically dispersing and soaking the carbon fiber with a desizing agent, and then sequentially filtering, washing, and drying the dispersion. The ultrasonic dispersion can be performed using an ultrasonic machine, and there are no particular limitations on this. Preferably, the ultrasonic dispersion time is 0.5-1 h. Preferably, the soaking time is 12-24 h.

[0064] According to some embodiments of the present invention, preferably, the desizing agent is selected from at least one of acetone, toluene, ethanol and xylene, and preferably acetone.

[0065] According to some embodiments of the present invention, preferably, the dispersant in step (2) is sodium carboxymethyl cellulose and / or hydroxyethyl cellulose. Preferably, the dispersant is provided in the form of a solution, wherein the solvent in the solution is deionized water and / or distilled water. More preferably, the concentration of the dispersant in the solution is 0.1-0.2 wt%.

[0066] According to some embodiments of the present invention, in step (3), the slurry is filtered to obtain a modified carbon fiber film, that is, the modified carbon fiber film is prepared by a wet papermaking process, which is beneficial to reduce the preparation cost. The filtration can be carried out in a vacuum filtration device, which is also equipped with a filter screen. Preferably, the filter screen is a 60-300 mesh stainless steel filter screen.

[0067] According to some embodiments of the present invention, after filtering the slurry in step (3), the filtered product is further dried. The drying can be performed with reference to existing technology, and there are no particular limitations thereto.

[0068] According to some embodiments of the present invention, in step (4), the modified carbon fiber film is contacted with a thermosetting polymer in the presence of an organic solvent, then the organic solvent is removed, and the resulting product is hot-pressed to cure the thermosetting polymer, so that the thermosetting polymer uniformly coats the modified carbon fiber film to form a protective layer, thereby obtaining a flexible carbon fiber film. It should be noted that during the hot-pressing process, while the thermosetting polymer coats the modified carbon fiber film, it may also embed itself into the porous structure of the modified carbon fiber film.

[0069] According to some embodiments of the present invention, preferably, the contact specifically includes: dissolving the thermosetting polymer in the organic solvent to obtain a polymer solution, and then immersing the modified carbon fiber film in the polymer solution. Preferably, the contact is carried out in a petri dish.

[0070] According to some embodiments of the present invention, there are no particular limitations on the method of removing the organic solvent. For example, the contact product can be placed in a room temperature environment to evaporate the solvent in order to remove the organic solvent.

[0071] According to some embodiments of the present invention, preferably, the organic solvent in step (4) is at least one of n-hexane, N-methylpyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide, preferably n-hexane.

[0072] According to some embodiments of the present invention, preferably, the mass ratio of the thermosetting polymer to the carbon fiber is 1-7:1.

[0073] According to some embodiments of the present invention, preferably, the hot pressing conditions include: a pressure of 0.1-0.3 MPa and a temperature of 60-120°C.

[0074] According to some embodiments of the present invention, preferably, before coating the surface of the flexible carbon fiber film with the conductive agent in step (5), the step further includes cutting the flexible carbon fiber film to obtain a flexible carbon fiber film of a specific size. The specific size can be selected according to the actual use and there is no particular limitation thereto. For example, the flexible carbon fiber film can be cut into a rectangle, with a length of 2-6 cm and a width of 1-4 cm.

[0075] According to some embodiments of the present invention, preferably, the size of the electrode layer in step (5) is the same as the size of the conductive agent layer.

[0076] According to some embodiments of the present invention, preferably, in step (5), a conductive agent is coated on the surfaces at both ends of the flexible carbon fiber film.

[0077] According to some embodiments of the present invention, the preparation method can prepare a flexible carbon fiber electrothermal film with a modified carbon fiber film content greater than 0 and not higher than 50 wt%, so that the resistivity of the flexible carbon fiber electrothermal film can be adjusted within a very wide range.

[0078] The present invention will be described in detail below through embodiments.

[0079] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available products.

[0080] The conductive paste was purchased from Beijing Zhongjing Scientific Instruments Technology Co., Ltd.

[0081] Conductivity: Measured at room temperature using a KDY-1 conductivity meter purchased from Guangzhou Kunde Technology Co., Ltd.

[0082] Thermal conductivity: measured according to ISO 22007-2.2015.

[0083] Example 1

[0084] (1) Pre-treating the carbon fiber, the pre-treatment includes: ultrasonically dispersing and soaking the carbon fiber and the desizing agent in sequence, and then filtering, washing and drying the dispersion in sequence;

[0085] The carbon fiber length is 3 mm; the desizing agent is acetone; the ultrasonic dispersion time is 1 hour; and the soaking time is 24 hours.

[0086] (2) The pretreated carbon fibers are impregnated in a modifier, and the resulting impregnated product is subjected to vacuum pyrolysis to obtain modified carbon fibers; wherein:

[0087] The modifier contains dopamine hydrochloride, tris(hydroxymethyl)aminomethane, and water. The specific preparation process of the modifier is as follows: dissolve dopamine hydrochloride in 0.01 mol / L Tris solution; the pH of the modifier is 8.5, and the concentration of dopamine hydrochloride in the modifier is 2 mg / mL.

[0088] The impregnation time was 24 hours; the vacuum pyrolysis conditions were: temperature 130℃ and time 12 hours.

[0089] (3) The modified carbon fiber and the dispersant are mixed to obtain a slurry;

[0090] The dispersant is a 0.1 wt% sodium carboxymethyl cellulose aqueous solution;

[0091] (4) The above slurry is poured into a vacuum filtration device for filtration and then dried to obtain a modified carbon fiber film; wherein the filter screen in the vacuum filtration device is 80 mesh.

[0092] The areal density of the modified carbon fiber film is 40 g / m³. 2 ;

[0093] (5) In the presence of an organic solvent, the modified carbon fiber film is brought into contact with a polymer, then the organic solvent is removed, and the resulting product is hot-pressed to solidify the polymer, so that it uniformly coats the modified carbon fiber film to form a protective layer, thereby obtaining a flexible carbon fiber film; wherein:

[0094] The polymer is polydimethylsiloxane (PDMS); the organic solvent is n-hexane; the mass ratio of PDMS to carbon fiber is 85:15; the hot pressing conditions are: pressure 0.1 MPa, temperature 90℃;

[0095] (6) Cut the above flexible carbon fiber film into rectangles (dimensions are shown in Table 2), then coat the surface of both ends of the rectangular flexible carbon fiber film with a conductive agent to form a conductive agent layer, and cover the surface of the conductive agent layer with an electrode layer to obtain a flexible carbon fiber electrothermal film.

[0096] The conductive agent is conductive silver paste; the electrode layer is conductive copper foil; the electrode layer consists of a positive electrode layer and a negative electrode layer, which are respectively disposed on the surfaces at both ends of the flexible carbon fiber film.

[0097] The thickness and width of each layer of the flexible carbon fiber electrothermal film are shown in Table 1.

[0098] This invention provides, by way of example, SEM images of the carbon fiber before and after modification during the preparation of the flexible carbon fiber electrothermal film, as shown in the figures below. Figure 2 (before modification) and Figure 3 As shown in the image (after modification).

[0099] As shown in the figure, after carbon fiber modification, the surface of the carbon fiber is coated with polydopamine, forming some polydopamine nanoparticles.

[0100] Example 2

[0101] The method is the same as in Example 1, except that the amount of carbon fiber added is such that the areal density of the resulting modified carbon fiber film is 80 g / m³. 2 The cutting dimensions of the flexible carbon fiber film are shown in Table 2. All other dimensions are the same as in Example 1, resulting in a flexible carbon fiber electrothermal film.

[0102] Example 3

[0103] The method is the same as in Example 1, except that the amount of carbon fiber added is such that the areal density of the resulting modified carbon fiber film is 120 g / m³. 2 The cutting dimensions of the flexible carbon fiber film are shown in Table 2. All other dimensions are the same as in Example 1, resulting in a flexible carbon fiber electrothermal film.

[0104] Example 4

[0105] The method is the same as in Example 1, except that the amount of carbon fiber added is such that the areal density of the resulting modified carbon fiber film is 160 g / m³. 2 The cutting dimensions of the flexible carbon fiber film are shown in Table 2. All other dimensions are the same as in Example 1, resulting in a flexible carbon fiber electrothermal film.

[0106] Comparative Example 1

[0107] The method of Example 1 is the same as in Example 1, except that in step (2), the impregnated product is not subjected to vacuum pyrolysis; the cutting dimensions of the flexible carbon fiber film are shown in Table 2, and the rest are the same as in Example 1, to obtain a flexible carbon fiber electrothermal film.

[0108] Table 1

[0109]

[0110]

[0111] Test case

[0112] 1. Voltage was applied to the flexible carbon fiber electrothermal films prepared in the examples and comparative examples respectively to test their electrothermal performance. The results are shown in Table 2.

[0113] The present invention provides, exemplarily, the temperature-time curve of a flexible carbon fiber electrothermal film with a size of 4*5cm prepared in Example 1, as shown below. Figure 4 As shown in the figure, we can see that:

[0114] When a 2V voltage is applied, the surface temperature of the heating film rises rapidly to 66℃ after 25 seconds of power-on, and then remains constant.

[0115] When a 3V voltage is applied, the surface temperature of the heating film rises rapidly to 98℃ after 25 seconds of power supply, and then remains constant.

[0116] When a 4V voltage is applied, the surface temperature of the heating film rises rapidly to 136℃ after 25 seconds of power-on, and then remains constant.

[0117] According to the test method provided in GB / T 7287-2008, the temperature distribution non-uniformity of the flexible carbon fiber electrothermal films prepared in the examples and comparative examples were calculated respectively, and the results are shown in Table 2.

[0118] 2. The electrical conductivity and thermal conductivity of the flexible carbon fiber electrothermal films prepared in the examples and comparative examples were tested respectively. The test results are shown in Table 2.

[0119] Table 2

[0120]

[0121]

[0122] Note: Non-uniformity* refers to the temperature distribution non-uniformity of the flexible carbon fiber electrothermal film; among them, the temperature distribution non-uniformity of the 4*5cm electrothermal film is tested at a stable state of 3V, and the temperature distribution non-uniformity of the 2.8*2.8cm electrothermal film is tested at a stable state of 1V.

[0123] The above results demonstrate that the flexible carbon fiber electrothermal film prepared using the method provided by this invention exhibits adjustable, controllable, and stable heating temperature, demonstrating excellent rapid heating characteristics, high electrothermal radiation conversion efficiency, uniform temperature distribution, and safety. This flexible carbon fiber electrothermal film can achieve rapid and stable heating under low-voltage DC power supplies, especially those below 5V, exhibiting a short response time, stable and repeatable electrothermal effect, and good flexibility, environmental friendliness, and human biocompatibility. Furthermore, the preparation method provided by this invention can be used to prepare flexible carbon fiber electrothermal films with a modified carbon fiber content greater than 0 and not exceeding 50wt%, allowing the resistivity of the flexible carbon fiber electrothermal film to be adjusted over a wide range.

[0124] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A flexible carbon fiber electrothermal film, characterized in that, The flexible carbon fiber electrothermal film includes a flexible carbon fiber film and an electrode layer; wherein, the flexible carbon fiber film includes a modified carbon fiber film and a thermosetting polymer; the modified carbon fiber film contains carbon fiber and polydopamine; The electrode layer includes a positive electrode layer and a negative electrode layer, which are respectively disposed on the surface of the flexible carbon fiber film; a conductive agent layer is also disposed between the electrode layer and the flexible carbon fiber film. The flexible carbon fiber electrothermal film has an electrical conductivity of 700-2150 S / m, a thermal conductivity of 1.2-2.75 W / (m·K), and a temperature distribution non-uniformity of less than 0.025 in the steady state at 3V. The flexible carbon fiber electrothermal film was prepared using the following method: (1) The carbon fiber is impregnated in a modifier and the impregnated product is subjected to vacuum pyrolysis to obtain modified carbon fiber; wherein the modifier contains dopamine hydrochloride; the conditions for vacuum pyrolysis include: temperature of 120-140℃ and time of 10-12h. (2) The modified carbon fiber is mixed with a dispersant to obtain a slurry; (3) The slurry is filtered to obtain a modified carbon fiber film; (4) In the presence of an organic solvent, the modified carbon fiber film is brought into contact with a thermosetting polymer, then the organic solvent is removed, and the resulting product is hot-pressed to cure the thermosetting polymer and obtain a flexible carbon fiber film; the thermosetting polymer is polydimethylsiloxane. (5) A conductive agent is coated on the surface of the flexible carbon fiber film to form a conductive agent layer, and an electrode layer is covered on the surface of the conductive agent layer.

2. The flexible carbon fiber electrothermal film according to claim 1, wherein, The width of the electrode layer is 2-5 mm; the thickness of the electrode layer is 0.01-0.1 mm. And / or, the electrode layer is selected from conductive copper foil and / or conductive aluminum foil.

3. The flexible carbon fiber electrothermal film according to claim 1, wherein, The width of the conductive agent layer is the same as the width of the electrode layer; And / or, the thickness of the conductive agent layer is 0.01-0.05 mm; And / or, the conductive agent layer contains silver powder and a binder.

4. The flexible carbon fiber electrothermal film according to any one of claims 1-3, wherein, The areal density of the modified carbon fiber film is 40-160 g / m³. 2 ; And / or, the length of the carbon fiber is 1-6 mm; And / or, the thickness of the flexible carbon fiber film is 0.1-1 mm.

5. The flexible carbon fiber electrothermal film according to any one of claims 1-3, wherein, The temperature distribution non-uniformity of the flexible carbon fiber electrothermal film in a stable state at 3V is no higher than 0.

02. And / or, the temperature distribution non-uniformity of the flexible carbon fiber electrothermal film in a stable state at 1V is 0.01-0.

015.

6. The flexible carbon fiber electrothermal film according to claim 1, wherein, In step (1), the modifier also contains tris(hydroxymethyl)aminomethane and water; the pH value of the modifier is 8-9; And / or, in the modifier, the concentration of dopamine hydrochloride is 2-6 mg / mL; And / or, the immersion time is 12-24 hours.

7. The flexible carbon fiber electrothermal film according to claim 1, wherein, Step (1) also includes pre-treating the carbon fiber, the pre-treatment including: ultrasonically dispersing and soaking the carbon fiber and desizing agent in sequence, and then filtering, washing and drying the dispersion in sequence; And / or, the desizing agent is selected from at least one of acetone, toluene, ethanol and xylene, preferably acetone.

8. The flexible carbon fiber electrothermal film according to claim 6 or 7, wherein, The dispersant mentioned in step (2) is sodium carboxymethyl cellulose and / or hydroxyethyl cellulose.

9. The flexible carbon fiber electrothermal film according to claim 6 or 7, wherein, The organic solvent mentioned in step (4) is at least one of n-hexane, N-methylpyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide; And / or, the mass ratio of the thermosetting polymer to the carbon fiber is 1-7:1; And / or, the conditions for hot pressing include: a pressure of 0.1-0.3 MPa and a temperature of 60-120°C.

10. The flexible carbon fiber electrothermal film according to claim 9, wherein, The organic solvent mentioned in step (4) is n-hexane.

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