Preparation method of self-temperature-limiting far-infrared carbon fiber composite conductive material

Abstract

The invention discloses a preparation method of a self-temperature-limiting far-infrared carbon fiber composite conductive material, which comprises the following steps: pulping molded fibers, grinding and homogenizing the molded fibers, preparing a water-phase treatment chopped carbon fiber solution, preparing a graphene mixture, mixing, homogenizing and dispersing the solution, and the like, thereby obtaining the self-temperature-limiting far-infrared carbon fiber composite conductive material. And finally, obtaining the self-temperature-limiting far-infrared carbon fiber composite conductive material by adopting wet-process fourdrinier net or rotary net forming equipment. When the far infrared electric heating material prepared by the preparation method disclosed by the invention reaches a limited temperature, the contact number and the gap size between the chopped carbon fibers and the graphene mixture particles can be reduced through the volume expansion of the self-temperature-limiting polymer, so that the aim of limiting the temperature is fulfilled.

Description

Technical Field

[0001] This invention relates to a material preparation method, specifically to a method for preparing a self-limiting far-infrared carbon fiber composite conductive material. Technical Background

[0002] Carbon fiber planar composite heating materials possess excellent infrared properties. Electrothermal materials prepared using these materials exhibit high electrothermal conversion efficiency, with infrared radiation typically exceeding 60%. These materials primarily consist of carbon fiber conductive paper, conductive materials, and electrothermal films, and are widely used in far-infrared heating applications. However, conductive paper suffers from high rigidity, poor flexibility, and limited bending and folding performance. Furthermore, humidity has a significant impact on conductive paper; it is highly susceptible to breakage and damage under humid conditions, and its electrical properties become extremely unstable under moderate humidity, leading to a sharp increase in resistance and rendering it unusable.

[0003] Chinese Patent Publication No. CN102226325A discloses a far-infrared carbon fiber low-temperature conductive heating paper. This method involves impregnating pulp with carbon fibers that have undergone carbonization, aqueous treatment, and hydrophilic treatment, homogenizing the pulp, and then continuing to beat it. The resistance of the mixed pulp is measured, and the mixed pulp with a resistance error within 2% ± 10% is used to form paper. The conductive paper produced by this method has high rigidity but poor flexibility, with poor bending and folding properties, making it unsuitable for flexible heating applications. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the present invention aims to provide a method for preparing a self-regulating far-infrared carbon fiber composite conductive material. The method utilizes a stable conductive network constructed from short-cut carbon fibers to solve the problem of short lifespan caused by unstable conductive pathways in existing far-infrared heating materials. Furthermore, it possesses a self-regulating temperature function; when the far-infrared electrothermal material prepared using this method reaches its temperature limit, the carbon fiber conductive network of the self-regulating far-infrared carbon fiber composite conductive material expands, thus preventing further heating and achieving the temperature-limiting purpose. The carbon fiber composite conductive material prepared using the method of the present invention can be widely used in flexible planar far-infrared electric heating elements such as wearable devices and infrared therapy devices.

[0005] The present invention provides a method for preparing a self-regulating far-infrared carbon fiber composite conductive material, which is achieved through the following technical solution: A method for preparing a self-regulating far-infrared carbon fiber composite conductive material, wherein the conductive material is composed of four raw materials: shaped fibers, chopped carbon fibers, a graphene mixture, a self-regulating polymer, and a dispersant. The method for preparing the conductive material includes at least the following steps:

[0006] Step 1: Pulping the shaped fibers;

[0007] Step 2: Pulping and homogenizing the shaped fibers;

[0008] Step 3: Prepare an aqueous solution for treating short-cut carbon fibers;

[0009] Step 4: Prepare a graphene mixture;

[0010] Step 5: Weigh and proportion the components of the self-limiting temperature polymer to prepare a high molecular weight polymer;

[0011] Step 6: Prepare graphene mixture and molding fiber slurry;

[0012] Step 7: Add the polymer obtained in Step 5 to the mixed slurry solution obtained in Step 6 for homogenization and mixing for 5-15 minutes. The polymer will dissolve in the solution at 70-90℃ and adhere to the long or short fibers of the molded fiber.

[0013] Step 8: Add the self-limiting temperature effect material obtained in Step 5 to the mixed slurry solution completed in Step 7 for homogenization and mixing for 10-15 minutes.

[0014] Step 9: Add the short-cut carbon fiber aqueous phase treatment mixed solution obtained in Step 3 to the mixed slurry solution in Step 8 for mixing, homogenization and dispersion. During the mixing and homogenization, continue to heat the slurry in the slurry tank with steam to keep the temperature of the slurry solution at 70-80℃. The homogenization time is 30-45 minutes.

[0015] Step 10: During the homogenization process, the mixed slurry is continuously extracted from the slurry pool in Step 9 and used to make paper using a papermaking machine. After the paper is hot-pressed and dried, electrodes are attached and the resistance is measured multiple times. If the resistance error is within ±5% after multiple measurements, the slurry for preparing conductive materials is obtained.

[0016] Step 11: The mixed slurry with a resistance error of ±5% obtained in Step 10 is used to obtain a self-limiting far-infrared carbon fiber composite conductive material by wet long screen or round screen forming equipment.

[0017] The above-mentioned method for preparing self-temperature-limiting far-infrared carbon fiber composite conductive material, wherein the molding fiber in step 1 is composed of a mixture of long and short fibers, and step 1 further includes the following steps:

[0018] Step 1.1: Place the long fibers into the pulper and soak them in hot water at 55-80℃ for 15-30 minutes. Start the pulper and pulp for 30-90 minutes at a speed of 1200-1800 r / min.

[0019] Step 1.2: Place the short fibers into the pulper and soak them in hot water at 55-80℃ for 15-30 minutes. Start the pulper and pulp for 30-90 minutes at a speed of 1200-1800 r / min.

[0020] The above-mentioned method for preparing self-temperature-limiting far-infrared carbon fiber composite conductive material further includes the following steps in step 2:

[0021] Step 2.1: Refine the long fibers obtained from the pulping process in Step 1.1;

[0022] Step 2.2: Refine the short fibers after pulping in Step 1.2;

[0023] Step 2.3: The long and short fibers obtained from the pulping process in Steps 2.1 and 2.2 are fed into a homogenizer for homogenization and mixing to obtain the shaped fiber pulp. The homogenization and mixing time is 15-30 minutes, and the homogenizer speed is 800-1600 r / min.

[0024] The above-mentioned method for preparing self-temperature-limiting far-infrared carbon fiber composite conductive material, wherein step 3 further includes the following steps:

[0025] Step 3.1: Weigh the water-dispersible short-cut carbon fibers with lengths of 1mm, 2mm, and 3mm according to the specified proportions;

[0026] Step 3.2: Weigh the dispersant according to the specified ratio;

[0027] Step 3.3: Start the homogenizer and inject 60-80℃ pure water into the homogenizer container at a dispersant solution concentration of 0.1%. The homogenizer speed is 400-800 r / min.

[0028] Step 3.4: Dispersant dissolution heat treatment; wherein,

[0029] Step 3.4.1: The dispersant of the 1mm water-dispersible short-cut carbon fiber obtained in step 3.2 is loaded into a funnel. The dispersant in the funnel is placed above the homogenizer container. The dispersant in the funnel flows into the homogenizer container of step 3.3 for dissolution treatment. The dissolution time is 10-20 minutes.

[0030] Step 3.4.2: The dispersant of the 2mm water-dispersible short-cut carbon fiber obtained in step 3.2 is loaded into a funnel. The dispersant in the funnel is placed above the homogenizer container. The dispersant in the funnel flows into the homogenizer container of step 3.3 for dissolution treatment. The dissolution time is 10-20 minutes.

[0031] Step 3.4.3: The dispersant of the 3mm water-dispersible short-cut carbon fiber obtained in step 3.2 is loaded into a funnel. The dispersant in the funnel is placed above the homogenizer container. The dispersant in the funnel flows into the homogenizer container of step 3.3 for dissolution treatment. The dissolution time is 10-20 minutes.

[0032] Step 3.5: Perform aqueous phase treatment on short-cut carbon fibers of various lengths; wherein,

[0033] Step 3.5.1: Add the 1 mm long water-dispersible short-cut carbon fiber obtained in step 3.1 into the dispersant aqueous solution in step 3.4.1, homogenize for 15-20 min, and the homogenizer speed is 1200-1600 r / min to obtain a 1 mm long water-treated carbon fiber solution.

[0034] Step 3.5.2: Add the 2mm long water-dispersible short-cut carbon fibers obtained in step 3.1 to the dispersant aqueous solution in step 3.4.2, homogenize for 10-20 minutes, and the homogenizer speed is 1200-1600 r / min to obtain a 2mm long water-treated carbon fiber solution.

[0035] Step 3.5.3: Add the 3mm long water-dispersible short-cut carbon fibers obtained in step 3.1 into the dispersant aqueous solution in step 3.4.3, homogenize for 20-30 minutes, and the homogenizer speed is 1200-1600 r / min to obtain a 3mm long water-treated carbon fiber solution.

[0036] Step 3.6: Prepare a mixed solution for aqueous treatment of short-cut carbon fibers; wherein,

[0037] Step 3.6.1: Homogenize the 1 mm long aqueous phase treated carbon fiber solution obtained in step 3.5.1 and the 3 mm long aqueous phase treated carbon fiber solution obtained in step 3.5.3. The homogenization time is 10-20 min and the homogenizer speed is 1200-1600 r / min.

[0038] Step 3.6.2: Add the 2mm long aqueous phase treated carbon fiber solution obtained in step 3.5.2 to the homogenized solution completed in step 3.6.1. The homogenization time is 15-30 minutes and the homogenizer speed is 1200-1600 r / min to obtain a short-cut carbon fiber aqueous phase treated mixed solution.

[0039] The above-mentioned method for preparing self-temperature-limiting far-infrared carbon fiber composite conductive material further includes the following step 4:

[0040] Step 4.1: Weigh graphene, graphite, and conductive carbon black according to a weight ratio of 1:20-40:10-30;

[0041] Step 4.2: The graphene, graphite and conductive carbon black obtained in step 4.1 are fed into an air jet mill for mixing for 15-30 minutes to obtain a graphene mixture.

[0042] The above-mentioned method for preparing self-regulating far-infrared carbon fiber composite conductive material, wherein the self-regulating polymer in step 5 is composed of hot-melt fibers, polymers and self-regulating effect materials in a weight ratio of 1:1-3:0.2-0.5, and the polymer is obtained by weighing the hot-melt fibers, polymers and self-regulating effect materials according to the ratio.

[0043] The above-mentioned method for preparing self-temperature-limiting far-infrared carbon fiber composite conductive material further includes the following step 6:

[0044] Step 6.1: Pump the molded fiber slurry obtained in step 2.3 into the mixing tank and turn on the mixer in the mixing tank. The mixer speed is 800-1200 r / min.

[0045] Step 6.2: Pour the graphene mixture obtained in step 4.2 into a mixing tank for homogenization and mixing for 15-30 minutes;

[0046] Step 6.3: Place the steam pipe into the mixing tank to heat the mixed solution from Step 6.2. The steam temperature is 110-120℃, and the temperature of the solution in the mixing tank is heated to 70-90℃. Step 6.4: Add the thermoplastic fibers obtained in Step 5 to the mixed solution obtained in Step 6.3 for homogenization and mixing for 10-20 minutes to obtain a graphene mixture and shaped fiber mixed slurry.

[0047] The above-mentioned method for preparing self-temperature-limiting far-infrared carbon fiber composite conductive material is used to prepare the self-temperature-limiting far-infrared carbon fiber composite conductive material.

[0048] Because the preparation method of the self-limiting far-infrared carbon fiber composite conductive material of the present invention adopts the above-mentioned scheme, it has the following advantages and positive effects compared with the prior art:

[0049] (1) The self-limiting far-infrared carbon fiber composite conductive material prepared by the method of the present invention has good flexibility and toughness, and excellent bending and folding performance. Because the conductive network built by carbon fiber is fixed in the fabric, carbon fiber will not fall off during use. It can be widely used in wearable devices, infrared therapy and various flexible heating scenarios.

[0050] (2) The product obtained by the preparation method of the self-limiting far-infrared carbon fiber composite conductive material of the present invention has a self-limiting function. When the far-infrared electrothermal material prepared by it reaches its temperature limit, the volume expansion of the self-limiting polymer reduces the number of contacts and the size of gaps between the short carbon fiber and graphene mixture particles, thereby achieving the purpose of temperature limit.

[0051] (3) The preparation method disclosed in this invention uses environmentally friendly and energy-saving raw materials. This method can be used to obtain more conductive materials with good electromagnetic compatibility and low electromagnetic radiation, and has excellent safety. Detailed Implementation

[0052] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0053] Example 1:

[0054] The present invention discloses a self-regulating far-infrared carbon fiber composite conductive material, achieved through the following technical solution: A self-regulating far-infrared carbon fiber composite conductive material comprises: molded fibers, chopped carbon fibers, a graphene mixture, a self-regulating polymer, and a dispersant. The chopped carbon fibers are entangled within the molded fibers to form a three-dimensional conductive network. The graphene polymer and the self-regulating polymer bonded to the molded fibers fill the conductive network constructed by the chopped carbon fibers, thereby forming a complete three-dimensional conductive filled network structure. During operation, when the self-regulating far-infrared carbon fiber composite conductive material reaches a predetermined temperature, the self-regulating polymer expands, reducing the number of contacts in the conductive network constructed by the chopped carbon fibers and increasing the resistance, thus achieving the self-regulating purpose. This conductive material is composed of the following raw materials in the indicated mass percentages: molded fibers 44%-91%, chopped carbon fibers 2.5%-40%, graphene mixture 1%-5%, self-regulating polymer 5%-10%, and dispersant 0.5%-1%.

[0055] The shaped fiber is composed of a mixture of long and short fibers. The length of the long fibers is 2-4.5 mm, and the length of the short fibers is 0.5-1.5 mm. The long and short fibers are pulped, refined, and homogenized in a weight ratio of 2-4:1. The shaped fiber is a combination of natural and chemical fibers. The natural fiber is cotton fiber, and the chemical fiber is one or a combination of polyester fiber, polypropylene fiber, nylon fiber, spandex fiber, acrylic fiber, ethylene fiber, and chlorofiber fiber.

[0056] The carbon fiber is water-dispersible short-cut carbon fiber, which is a polyacrylonitrile-based carbon fiber with lengths of 1 mm, 2 mm and 3 mm respectively, and the weight ratio of the above short-cut carbon fibers is 2:1-1.5:1.

[0057] The graphene mixture is prepared by mixing graphene, graphite and conductive carbon black in a weight ratio of 1:20-40:10-30 using an air jet mill.

[0058] The self-regulating polymer is composed of hot-melt fibers, a polymer, and a self-regulating material in a weight ratio of 1:1-3:0.2-0.5. The hot-melt fibers can be one or a combination of polyester fibers, copolyamide fibers, ethylene resin acetate fibers, polyethylene fibers, or polypropylene fibers. The polymer is one or a combination of polyethylene glycol, polypropylene, polyethylene, and polyvinylidene fluoride. The polymer is in powder form with a particle size of 10-60 μm. The self-regulating material is one or a combination of quartz, barium titanate, or montmorillonite with a particle size of 5-50 μm.

[0059] The dispersant is one or a combination of polyacrylamide and polyethylene oxide. In this embodiment, the polyacrylamide is preferably a cationic polyacrylamide with a molecular weight of 16 million. The aqueous solution concentration of the dispersant is 0.5-2%.

[0060] A method for preparing the above-mentioned self-limiting far-infrared carbon fiber composite conductive material, the method comprising at least the following steps;

[0061] Step 1: Pulping the shaped fibers;

[0062] Step 1.1: Place the long fibers into the pulper and soak them in hot water at 55-80℃ for 15-30 minutes. Start the pulper and pulp for 30-90 minutes at a speed of 1200-1800 r / min.

[0063] Step 1.2: Place the short fibers into the pulper and soak them in hot water at 55-80℃ for 15-30 minutes. Start the pulper to pulp for 30-90 minutes at a speed of 1200-1800 r / min.

[0064] Step 2: Pulping and homogenizing the shaped fibers;

[0065] Step 2.1: Refine the long fibers obtained from the pulping process in Step 1.1;

[0066] Step 2.2: Refine the short fibers after pulping in Step 1.2;

[0067] Step 2.3: The long and short fibers obtained from the pulping process in Steps 2.1 and 2.2 are fed into a homogenizer for homogenization and mixing to obtain the shaped fiber pulp. The homogenization and mixing time is 15-30 minutes, and the homogenizer speed is 800-1600 r / min.

[0068] Step 3: Prepare an aqueous solution for treating short-cut carbon fibers;

[0069] Step 3.1: Weigh the 1mm, 2mm, and 3mm lengths of water-dispersible short-cut carbon fibers according to the specified proportions;

[0070] Step 3.2: Weigh the dispersant according to the specified ratio;

[0071] Step 3.3: Start the homogenizer and inject 60-80℃ pure water into the homogenizer container at a dispersant solution concentration of 0.1%. The homogenizer speed is 400-800 r / min.

[0072] Step 3.4: Dispersant dissolution heat treatment;

[0073] Step 3.4.1: The dispersant of the 1mm water-dispersible short-cut carbon fiber obtained in step 3.2 is loaded into a funnel. The dispersant in the funnel is placed above the homogenizer container. The dispersant in the funnel flows into the homogenizer container of step 3.3 for dissolution treatment. The dissolution time is 10-20 minutes.

[0074] Step 3.4.2: The dispersant of the 2mm water-dispersible short-cut carbon fiber obtained in step 3.2 is loaded into a funnel. The dispersant in the funnel is placed above the homogenizer container. The dispersant in the funnel flows into the homogenizer container of step 3.3 for dissolution treatment. The dissolution time is 10-20 minutes.

[0075] Step 3.4.3: The dispersant of the 3mm water-dispersible short-cut carbon fiber obtained in step 3.2 is loaded into a funnel. The dispersant in the funnel is placed above the homogenizer container. The dispersant in the funnel flows into the homogenizer container of step 3.3 for dissolution treatment. The dissolution time is 10-20 minutes.

[0076] Step 3.5: Aqueous phase treatment of short-cut carbon fibers of various lengths;

[0077] Step 3.5.1: Add the 1 mm long water-dispersible short-cut carbon fiber obtained in step 3.1 into the dispersant aqueous solution in step 3.4.2, homogenize for 15-20 min, and the homogenizer speed is 1200-1600 r / min to obtain a 1 mm long water-treated carbon fiber solution.

[0078] Step 3.5.2: Add the 2mm long water-dispersible short-cut carbon fibers obtained in step 3.1 into the dispersant aqueous solution in step 3.4.1, homogenize for 10-20 minutes, and the homogenizer speed is 1200-1600 r / min to obtain a 2mm long water-treated carbon fiber solution.

[0079] Step 3.5.3: Add the 3mm long water-dispersible short-cut carbon fibers obtained in step 3.1 to the dispersant aqueous solution in step 3.4.1, homogenize for 20-30 minutes, and the homogenizer speed is 1200-1600 r / min to obtain a 3mm long water-treated carbon fiber solution.

[0080] Although water-dispersible short-cut carbon fibers have undergone hydrophilic treatment, their dispersion is affected by their length. The longer the short-cut carbon fibers are, the more difficult they are to disperse. Generally, water-dispersible short-cut carbon fibers with a length of 1-2 mm are relatively easy to disperse, while those with a length exceeding 2 mm are more difficult to disperse. Therefore, increasing the homogenization time can improve their dispersion.

[0081] Step 3.6: Prepare a mixed solution for aqueous treatment of short-cut carbon fibers;

[0082] Step 3.6.1: Homogenize the 1 mm long aqueous phase treated carbon fiber solution obtained in step 3.5.1 and the 3 mm long aqueous phase treated carbon fiber solution obtained in step 3.5.3. The homogenization time is 10-20 min and the homogenizer speed is 1200-1600 r / min.

[0083] Step 3.6.2: Add the 2mm long aqueous phase treated carbon fiber solution obtained in step 3.5.2 to the homogenized solution completed in step 3.6.1. The homogenization time is 15-30 minutes and the homogenizer speed is 1200-1600 r / min to obtain a short-cut carbon fiber aqueous phase treated mixed solution.

[0084] Although the aqueously treated carbon fibers are uniformly dispersed, flocculation easily occurs when carbon fibers of different lengths are mixed, especially short-cut carbon fibers longer than 2mm. Mass production trials revealed that homogenizing solutions of 1mm and 3mm length aqueously treated carbon fibers first resulted in uniform dispersion of the fibers in the solution. This is mainly because the 1mm short-cut carbon fibers continuously impact and comb the 3mm length fibers in the solution during homogenization, leading to uniform dispersion of the 3mm length fibers in the mixed solution. Subsequently, 2mm length aqueously treated carbon fiber solutions were added sequentially. The impact and combing of the different length fibers in the solution prevented flocculation, ensuring uniform dispersion of the carbon fibers while avoiding flocculation of the longer short-cut fibers.

[0085] Step 4: Prepare a graphene mixture;

[0086] Step 4.1: Weigh graphene, graphite, and conductive carbon black according to a weight ratio of 1:20-40:10-30;

[0087] Step 4.2: The graphene, graphite and conductive carbon black obtained in step 4.1 are fed into an air jet mill for mixing for 15-30 minutes to obtain a graphene mixture.

[0088] Step 5: Weigh the self-regulating polymer, hot melt fiber, polymer and self-regulating effect material according to the ratio to obtain the polymer.

[0089] Step 6: Preparation of graphene mixture and molding fiber slurry

[0090] Step 6.1: Pump the molded fiber slurry obtained in step 2.3 into the mixing tank and turn on the mixer in the mixing tank. The mixer speed is 800-1200 r / min.

[0091] Step 6.2: Pour the graphene mixture obtained in step 4.2 into a mixing tank for homogenization and mixing for 15-30 minutes;

[0092] Step 6.3: Place the steam pipe into the mixing tank to heat the mixed solution from Step 6.2. The steam temperature is 110-120℃, and the temperature of the solution in the mixing tank is heated to 70-90℃.

[0093] Step 6.4: Add the thermoplastic fibers obtained in Step 5 to the mixed solution obtained in Step 6.3 for homogenization and mixing for 10-20 minutes to obtain a graphene mixture and molding fiber slurry. The thermoplastic fibers can quickly dissolve in water heated to 70-90℃. The water-soluble thermoplastic fibers can effectively adhere the graphene mixture to the long or short fibers of the molding fiber, ensuring that the manufactured conductive paper forms a stable three-dimensional conductive filled network structure.

[0094] Self-limiting far-infrared carbon fiber composite conductive material uses molded fibers as the matrix. A three-dimensional conductive network is constructed by uniformly dispersing and mixing short-cut carbon fibers within the molded fibers. This conductive network is built from a 3mm long carbon fiber skeleton, with 1mm and 2mm carbon fibers filling the gaps and forming smaller three-dimensional conductive networks. This ensures a combined structure of the skeleton and supplementary three-dimensional conductive networks. Carbon fiber composite conductive materials are planar heating materials. Existing technologies primarily use a skeleton three-dimensional conductive network structure, where gaps lack carbon fibers, leading to excessive surface temperature differences and high energy consumption. However, by combining the skeleton and supplementary three-dimensional conductive networks, the supplementary network fills the gaps in the skeleton, ensuring the entire surface of the carbon fiber composite conductive material is filled with the supplementary three-dimensional conductive network. This results in a heating surface where the entire surface is a heating surface. Because the supplementary network fills the gaps in the skeleton, the entire heating surface is microscopically free of voids, resulting in uniform heating, smaller temperature differences, and lower energy consumption.

[0095] Step 7: Add the polymer obtained in Step 5 to the mixed slurry solution obtained in Step 6.4 for homogenization and mixing for 5-15 minutes. The polymer will dissolve in the solution at 70-90℃ and adhere to the long or short fibers of the molded fiber.

[0096] Step 8: Add the self-limiting temperature effect material obtained in Step 5 to the mixed slurry solution completed in Step 7 for homogenization and mixing for 10-15 minutes.

[0097] Step 9: Add the short-cut carbon fiber aqueous phase treatment mixed solution obtained in step 3.6.4 to the mixed slurry solution in step 8 for mixing, homogenization and dispersion. During the mixing and homogenization, continue to heat the slurry in the slurry tank with steam to keep the temperature of the slurry solution at 70-80℃. The homogenization time is 30-45 minutes.

[0098] Self-regulating far-infrared carbon fiber composite conductive materials conform to the conductive chain and thermal expansion model and the tunneling conductivity model. In these materials, chopped carbon fibers directly contact each other to form a three-dimensional conductive network. Graphene mixture particles adhered to the molded fibers also directly contact each other, filling and supplementing the continuous three-dimensional conductive network formed by the chopped carbon fibers, thus creating a complete conductive network and conductive pathway. Generally, when chopped carbon fibers and graphene mixture particles contact each other, forming a chain-like network—that is, a three-dimensional conductive filling network—the more contacting particles in the network, the denser the network, and the smaller the gaps between particles, the higher the conductivity. According to the "conductive channel" theory, conductivity only occurs when a complete, continuous conductive network is formed, i.e., when the gaps between conductive particles are very small. Therefore, the main factors affecting its conductivity σ include the number of contacts, contact resistance, and gap size. The conductivity of self-regulating far-infrared carbon fiber composite conductive materials can be increased or decreased by altering the number of contacts and the gap size between the short-cut carbon fiber and graphene mixture particles. The "tunneling effect" posits that while conductivity still involves the formation of a conductive network, it doesn't rely on direct contact between conductive particles. Instead, it's caused by thermal vibrations leading to electron migration between the particles. The tunneling effect only occurs between closely spaced filler aggregates; aggregates with large gaps exhibit no conductive behavior. The tunneling effect suggests a close relationship between conductivity and temperature, with thermal excitation voltage increasing conductivity. Initially, conductive particles form conductive chains within the polymer. As the temperature rises, the polymer matrix expands. Due to the different expansion rates of the matrix and the conductive chains, the chains gradually separate, increasing resistance. At the melting point, the polymer volume suddenly increases, disrupting the conductive chains and causing a sudden increase in resistance—the PTC phenomenon observed in the composite system. Therefore, self-regulating far-infrared carbon fiber composite conductive materials achieve PTC by adjusting the number of contacts and the gap size between the short-cut carbon fiber and graphene mixture particles through the volume expansion of the self-regulating polymer.

[0099] Step 10: During the homogenization process, the mixed slurry is continuously extracted from the slurry pool in Step 9 and used to make paper using a papermaking machine. After the paper is hot-pressed and dried, electrodes are attached and the resistance is measured multiple times. If the resistance error is within ±5% after multiple measurements, the slurry for preparing the self-limiting far-infrared carbon fiber composite conductive material is obtained.

[0100] Step 11: The mixed slurry with a resistance error of ±5% obtained in Step 10 is used to obtain a self-limiting far-infrared carbon fiber composite conductive material by wet long screen or round screen forming equipment.

[0101] In this embodiment, the composite conductive material is fabricated into a composite conductive cloth, exhibiting good flexibility and toughness, and excellent bending and folding properties. The heat transfer of the self-regulating far-infrared carbon fiber composite conductive material of this invention is primarily through far-infrared radiation, and it also releases far-infrared light waves of 5–15 μm, activating water molecules in the human body, increasing blood oxygen levels, enhancing cell vitality, improving microcirculation, and promoting metabolism. The self-regulating far-infrared carbon fiber composite conductive material products manufactured using the preparation method of this invention achieve temperature limiting by reducing the number of contacts and the size of gaps between short-cut carbon fiber and graphene mixture particles through the volume expansion of the self-regulating polymer.

[0102] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientation or positional relationships, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0103] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0104] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a self-limiting temperature far infrared carbon fiber composite conductive material, characterized in that, The conductive material is composed of four raw materials: shaped fibers, chopped carbon fibers, graphene mixture, self-limiting polymer and dispersant. The method for preparing the conductive material comprises at least the following steps: Step 1: beating the shaped fibers; Step 2: grinding and homogenizing the shaped fibers; Step 3: preparing a water-phase treated chopped carbon fiber solution; Step 4: preparing a graphene mixture; Step 5: preparing a high-molecular polymer by weighing and mixing the components of the self-limiting polymer; Step 6: preparing a mixture of the graphene mixture and the shaped fiber pulp; Step 7: adding the high-molecular polymer obtained in Step 5 to the mixed pulp solution obtained in Step 6 for homogenizing mixing, for a time of 5-15 min, so that the high-molecular polymer is dissolved in the solution at 70-90℃ and adheres to the long fibers or short fibers of the shaped fibers; Step 8: adding the self-limiting effect material obtained in Step 5 to the mixed pulp solution completed in Step 7 for homogenizing mixing, for a time of 10-15 min. Step 9: adding the water-phase treated mixed solution of the chopped carbon fibers obtained in Step 3 to the mixed pulp solution in Step 8 for mixing, homogenizing and dispersing, and continuously heating the pulp in the pulp pool with steam so that the temperature of the pulp solution is maintained at 70-80℃, and the homogenizing time is 30-45 min; Step 10: continuously extracting the mixed pulp from the pulp pool in Step 9 during the homogenizing process, and using a sheet former to make paper from the mixed pulp, and measuring the resistance of the obtained sheet paper after hot-press drying and electrode connection for multiple times, and the error of the resistance is within ±5%, so that the pulp for preparing the conductive material is obtained; Step 11: using a wet long net or circular net forming device to obtain a self-limiting far-infrared carbon fiber composite conductive material from the mixed pulp with the resistance error within ±5% obtained in Step 10.

2. The preparation method of the self-temperature-limiting far-infrared carbon fiber composite conductive material as described in claim 1, characterized in that, The shaped fibers in Step 1 are composed of long fibers and short fibers, and Step 1 further comprises the following steps: Step 1.1: placing the long fibers into a beater, soaking them with hot water at 55-80℃ for 15-30 min, and starting the beater for beating, for a time of 30-90 min, and the rotation speed of the beater is 1200-1800 r / min; Step 1.2: placing the short fibers into a beater, soaking them with hot water at 55-80℃ for 15-30 min, and starting the beater for beating, for a time of 30-90 min, and the rotation speed of the beater is 1200-1800 r / min.

3. The preparation method of the self-temperature-limiting far-infrared carbon fiber composite conductive material as described in claim 2, characterized in that, Step 2 further comprises the following steps: Step 2.1: grinding the long fibers after beating in Step 1.1; Step 2.2: grinding the short fibers after beating in Step 1.2; Step 2.3: feeding the ground long fibers and short fibers obtained in Steps 2.1 and 2.2 into a homogenizer for homogenizing mixing, so as to obtain shaped fiber pulp, and the homogenizing mixing time is 15-30 min, and the rotation speed of the homogenizer is 800-1600 r / min.

4. The preparation method of the self-temperature-limiting far-infrared carbon fiber composite conductive material as described in claim 3, characterized in that, Step 3 further comprises the following steps: Step 3.1: weighing the water-dispersible chopped carbon fibers with lengths of 1 mm, 2 mm and 3 mm respectively according to the proportion; Step 3.2: weighing the dispersant according to the proportion; Step 3.3: Start the homogenizer, inject 60-80°C pure water into the homogenizer container according to the dispersant solution concentration of 0.1%, and the rotation speed of the homogenizer is 400-800r / min; Step 3.4: Dispersant solution heat treatment; wherein, Step 3.4.1: Put the dispersant of 1mm water dispersible chopped carbon fiber obtained in step 3.2 into the funnel, and place the dispersant in the funnel above the homogenizer container, and the dispersant in the funnel flows into the homogenizer container of step 3.3 for dispersant dissolution treatment, and the dissolution time is 10-20min; Step 3.4.2: Put the dispersant of 2mm water dispersible chopped carbon fiber obtained in step 3.2 into the funnel, and place the dispersant in the funnel above the homogenizer container, and the dispersant in the funnel flows into the homogenizer container of step 3.3 for dispersant dissolution treatment, and the dissolution time is 10-20min; Step 3.4.3: Put the dispersant of 3mm water dispersible chopped carbon fiber obtained in step 3.2 into the funnel, and place the dispersant in the funnel above the homogenizer container, and the dispersant in the funnel flows into the homogenizer container of step 3.3 for dispersant dissolution treatment, and the dissolution time is 10-20min; Step 3.5: Water phase treatment of each length of chopped carbon fiber; wherein, Step 3.5.1: Put the 1mm length of water dispersible chopped carbon fiber obtained in step 3.1 into the dispersant aqueous solution of step 3.4.1, and the homogenization time is 15-20min, and the rotation speed of the homogenizer is 1200-1600r / min, thereby obtaining a 1mm length of water phase treated carbon fiber solution; Step 3.5.2: Put the 2mm length of water dispersible chopped carbon fiber obtained in step 3.1 into the dispersant aqueous solution of step 3.4.2, and the homogenization time is 10-20min, and the rotation speed of the homogenizer is 1200-1600r / min, thereby obtaining a 2mm length of water phase treated carbon fiber solution; Step 3.5.3: Put the 3mm length of water dispersible chopped carbon fiber obtained in step 3.1 into the dispersant aqueous solution of step 3.4.3, and the homogenization time is 20-30min, and the rotation speed of the homogenizer is 1200-1600r / min, thereby obtaining a 3mm length of water phase treated carbon fiber solution; Step 3.6: Prepare a mixed solution of water phase treated chopped carbon fiber; wherein, Step 3.6.1: Homogenize the 1mm length of water phase treated carbon fiber solution obtained in step 3.5.1 and the 3mm length of water phase treated carbon fiber solution obtained in step 3.5.3, and the homogenization time is 10-20min, and the rotation speed of the homogenizer is 1200-1600r / min; Step 3.6.2: Add the 2mm length of water phase treated carbon fiber solution obtained in step 3.5.2 to the solution completed in step 3.6.1, and the homogenization time is 15-30min, and the rotation speed of the homogenizer is 1200-1600r / min, thereby obtaining a mixed solution of water phase treated chopped carbon fiber.

5. The preparation method of the self-limiting far-infrared carbon fiber composite conductive material as described in claim 4, characterized in that, Step 4 further comprises the following steps: Step 4.1: weighing graphene, graphite and conductive carbon black according to the weight ratio of 1:20-40:10-30; Step 4.2: the graphene, graphite and conductive carbon black obtained in step 4.1 are sent into an airflow crusher for mixing, and the mixing time is 15-30 min, thereby obtaining a graphene mixture.

6. The method for preparing the self-temperature-limiting far-infrared carbon fiber composite conductive material as described in claim 5, characterized in that, The self-limiting temperature polymer in the step 5 is composed of the hot melt fiber, the polymer and the self-limiting temperature effect material according to the weight ratio of 1:1-3:0.2-0.5, and the hot melt fiber, the polymer and the self-limiting temperature effect material are weighed according to the ratio to obtain the polymer.

7. The method for preparing the self-temperature-limiting far-infrared carbon fiber composite conductive material as described in claim 6, characterized in that, Step 6 further comprises the following steps: Step 6.1: the shaped fiber slurry obtained in step 2.3 is pumped into a slurry mixing tank, and a stirrer in the slurry mixing tank is started, and the rotating speed of the stirrer is 800-1200 r / min; Step 6.2: the graphene mixture obtained in step 4.2 is poured into the slurry mixing tank for homogeneous mixing, and the time is 15-30 min; Step 6.3: a steam pipe is placed in the slurry mixing tank to heat the mixed solution of step 6.2, and the steam temperature is 110-120℃, and the solution temperature in the slurry mixing tank is heated to 70-90℃; Step 6.4: the hot melt fiber obtained in step 5 is added to the mixed solution obtained in step 6.3 for homogeneous mixing, and the time is 10-20 min, thereby obtaining a graphene mixture and shaped fiber mixed slurry.

8. The method for preparing the self-temperature-limiting far-infrared carbon fiber composite conductive material as described in claim 7, characterized in that, The self-limiting temperature far infrared carbon fiber composite conductive cloth is prepared by the preparation method.