Far infrared nanometer carbon fiber composite fabric

Abstract

The invention discloses a far infrared nano carbon fiber composite fabric, and belongs to the technical field of fabrics. The far infrared nano carbon fiber composite fabric sequentially comprises a first fabric base layer, a far infrared electric heating layer and a second fabric base layer from bottom to top, wherein the far infrared electric heating layer is bonded with the first fabric base layer and the second fabric base layer through insulating glue; wherein the far infrared electric heating layer comprises a nanometer carbon fiber film, electrodes and an electrifying wire, the electrodes are electrically connected to the two sides of the nanometer carbon fiber film, and the electrodes are electrically connected with the electrifying wire to form a complete circuit; the carbon nanofiber membrane is obtained by uniformly mixing and stirring formylated spiral carbon nanofibers, a flame retardant and modified polytetrafluoroethylene, then carrying out jet milling, then heating, carrying out high-speed rotary cutting and fibration, finally putting into a spreading device, uniformly spreading, and carrying out hot rolling molding; the prepared carbon nanofiber membrane is better in mechanical property and conductivity and more uniform in heating.

Description

TECHNICAL FIELD

[0001] The present application relates to a far-infrared nanocarbon fiber composite fabric. BACKGROUND

[0002] In recent years, the field of functional textile materials has witnessed an innovation breakthrough. Far-infrared nanocarbon fiber composite fabric, with its excellent thermal radiation characteristics, electrical conductivity performance, and mechanical strength, has shown great development potential in smart wearable equipment, medical aids, and spacecraft thermal control systems. However, it is important to note that the key technical bottleneck of this material has not been broken through, which has restricted its large-scale application process.

[0003] In terms of electrical heating performance, the existing nanocarbon fiber film of the composite fabric has problems of insufficient uniformity of fiber dispersion or poor interfacial bonding strength. When an electric current is applied for heating, the material exhibits obvious heterogeneity in electrical-thermal response, with a significant decrease in heat conduction efficiency in local areas, while energy accumulation occurs in adjacent areas. This non-uniform thermal field distribution not only weakens the overall performance indicators of the fabric, but also may cause material degradation risk due to local overheating.

[0004] In terms of electrical conductivity performance, although the intrinsic conductivity of nanocarbon fiber is excellent, during the construction of the composite system, due to the mismatch of interface impedance and the imperfect construction of three-dimensional conductive network, the macroscopic electrical conductivity performance shows significant attenuation. This mesoscale charge transport barrier directly causes the electrical-to-thermal conversion efficiency to drop by 20-35% compared to the theoretical value, causing a technical problem of reduced energy utilization efficiency.

[0005] In terms of mechanical adaptability, after introducing the nanocarbon fiber film through traditional composite processes, due to the modulus difference between the fiber and the matrix material, the bending stiffness of the material is increased to 3-5 times that of the original substrate. This sudden change in mechanical properties causes stress concentration in the fabric in dynamic deformation scenarios (such as human joint movement), greatly restricting the market adaptability of the product, especially in the field of intelligent motion monitoring that requires high adhesion.

[0006] In summary, developing a nanocarbon fiber film that can effectively solve the uneven heating of the composite fabric, improve electrical conductivity, and improve flexibility has become one of the key research directions. SUMMARY

[0007] The purpose of the present application is to provide a far-infrared nanocarbon fiber composite fabric to solve the technical problems mentioned in the background.

[0008] The technical solution to achieve the purpose of the present application is: The first aspect of the present application provides a far-infrared nanocarbon fiber composite fabric, which comprises a first fabric base layer, a far-infrared electrothermal layer and a second fabric base layer from bottom to top; the far-infrared electrothermal layer comprises a nanocarbon fiber film, an electrode and an electrified wire, the electrode is electrically connected to both sides of the nanocarbon fiber film, and the electrode is electrically connected to the electrified wire, thereby forming a complete circuit among the electrode, the electrified wire and the nanocarbon fiber film.

[0009] Further, the far-infrared electrothermal layer is adhesively connected to the first fabric base layer and the second fabric base layer through insulation.

[0010] Further, the nanocarbon fiber film is prepared by pre-mixing and reacting modified polytetrafluoroethylene and a flame retardant, then adding aldehyde-based spiral nanocarbon fibers and uniformly mixing and stirring, followed by airflow crushing, then high-speed rotary cutting fiberization after heating, then uniformly spreading in a spreader under a certain magnetic field, and finally hot roller molding under heat.

[0011] Further, the modified polytetrafluoroethylene is obtained by grafting modification of 4-allyl aniline on pre-irradiated PTFE.

[0012] Further, the preparation steps of the nanocarbon fiber film are as follows: S1. 500 parts by mass of 2M hydrochloric acid, 2.5-5 parts by mass of surfactant ethoxy perfluorooctyl ethanol are mixed and stirred to disperse uniformly, then 25-35 parts by mass of modified polytetrafluoroethylene, 0.5-1.5 parts by mass of hexaphenylamine-based cyclotriphosphazene are added, and the system is continuously stirred under ice bath conditions until the modified polytetrafluoroethylene and hexaphenylamine-based cyclotriphosphazene are uniformly suspended in the aqueous solution, then 360-370 parts by mass of 2M ammonium persulfate aqueous solution is added dropwise at a rate of 3-5 s / drop, and the system is stirred for 55-65 min after the addition is completed, and the temperature of the system is kept below 5℃ during the addition and reaction; S2. 10 parts by mass of aldehyde-based spiral nanocarbon fibers are added to the material obtained in step S1, and then ultrasonic treatment is carried out at 35-45℃ and under the conditions of 18 kHz and 200 W, followed by suction filtration, repeated washing with distilled water for 4-6 times, and then drying in a drying drum oven at 58-62℃ for 23.5-24.5h; S3. The material obtained in step S2 is airflow crushed; S4. The material obtained in step S3 is high-speed rotary cut fiberized after heating; S5. The material obtained in step S4 is uniformly spread in a spreader under a certain magnetic field, and then hot roller molding is carried out.

[0013] Further, the flame retardant is hexaphenylamine-based cyclotriphosphazene.

[0014] Further, the preparation steps of the aldehyde group modified helical nanometer carbon fiber are as follows: (1) uniformly smear 8-12 mass parts of nickel powder with a particle size of 30-200 nm on a graphite substrate, put into the central part of a tubular electric furnace body, and heat to 734-735 DEG C under a nitrogen atmosphere, then respectively pass in 37-38 mL / min and 62-63 mL / min of carbon source acetylene and carrier gas hydrogen, the acetylene is first passed through a container containing thiophene before entering the reaction chamber, and the thiophene is carried into the reactor as a growth promoter for reaction, the reaction time is 25-35 min, then the product is scraped off from the graphite substrate, ground in a mortar for two times, and helical nanometer carbon fiber with a fiber diameter of about 0.5-1 µm and a helical pipe diameter of about 0.5-0.8 µm is obtained; Wherein, the nanometer-sized nickel powder as a catalyst exists in a solid phase when catalyzing, has anisotropy, and thus different crystal faces have different catalytic activities, so that the nanometer carbon fiber has different growth speeds on different crystal faces; among the three directions of the nanometer-sized nickel powder particles as a catalyst, the Z direction size is greater than or equal to the X+Y direction size, based on the solid-phase catalytic growth mechanism, after the carbon source acetylene contacts the aforementioned nanometer-sized nickel powder particles at 734-735 DEG C, the nanometer-sized nickel powder particles grow into helical nanometer carbon fiber with a fiber diameter of about 0.5-1 µm and a helical pipe diameter of about 0.5-0.8 µm, and the helical nanometer carbon fiber has the nanometer-sized nickel powder particles as a catalyst inside; (2) mix the helical nanometer carbon fiber obtained in step (1) with an acid mixed solution according to a mass ratio of 1:18-22, then ultrasonic treatment for 10 min, then heat to 115-125 DEG C, stir and reflux for 1.8-2.2 h, then add deionized water with a mass of 70-90 times of the helical nanometer carbon fiber, dilute, filter, then repeatedly wash and filter with deionized water until the filtrate is neutral, then vacuum dry at 78-82 DEG C for 23-25 h, and obtain the acidified helical nanometer carbon fiber; wherein, the acid mixed solution is obtained by mixing 60wt% concentrated nitric acid and 98wt% concentrated sulfuric acid according to a volume ratio of 1:3; (3) mix the acidified helical nanometer carbon fiber obtained in step (2) with thionyl chloride according to a mass ratio of 1:38-42, then ultrasonic treatment for 10 min, then heat to 70-80 DEG C, stir and reflux for 23-25 h, then remove the excess thionyl chloride by reduced pressure distillation, and obtain the acylated helical nanometer carbon fiber; (4) mix the acylated helical nanometer carbon fiber obtained in step (3) with salicylaldehyde according to a mass ratio of 1:58-59, then ultrasonic treatment for 10 min, then heat to 115-125 DEG C, stir and react for 47-49 h, then dilute with deionized water and filter, then repeatedly wash and filter with deionized water for 4-6 times, then vacuum dry at 78-82 DEG C for 23-25 h, and obtain the aldehyde group modified helical nanometer carbon fiber.

[0015] Further, the preparation method of the modified polytetrafluoroethylene is as follows: polytetrafluoroethylene micropowder with a particle size of 0.5-20 microns is placed in an air atmosphere at room temperature in a Co radioactive source with an activity of 1.85*10 14 Bq for gamma ray irradiation treatment, to obtain pre-irradiation treated PTFE, wherein the absorption dose of the irradiation treated PTFE is 100 kGy, the free radical concentration is 60 1*10 21 Bq / m 3, and the free radical concentration is 1*10 21 Bq / m 3. After 100 parts by mass of deionized water, 0.5-1 parts by mass of a surfactant ethoxy perfluorooctyl ethanol are uniformly mixed and dispersed, 8-12 parts by mass of the pre-irradiation treated PTFE is added, and the pre-irradiation treated PTFE is uniformly suspended in the aqueous solution by continuing stirring, then 9-11 parts by mass of 4-allyl aniline, 0.009-0.011 parts by mass of a polymerization inhibitor ferrous ammonium sulfate, and 0.09-0.11 parts by mass of concentrated sulfuric acid are added, and the mixture is stirred in a water bath at 68-72 DEG C under nitrogen protection for 4.8-5.2 hours, after the reaction is completed, the upper liquid is removed by centrifugal separation, and the obtained precipitate is redispersed in water and centrifuged again, the above steps are repeated for 5-7 times, and then the mixture is dried in a forced air oven at 58-62 DEG C for 23.5-24.5 hours to obtain functionalized polytetrafluoroethylene.

[0016] Further, the heating temperature of the S4 is 60-80 DEG C, and the holding time is 2.5-3.5 hours.

[0017] Further, the heating roller pressing temperature of the S5 is 190-210 DEG C, the heating roller pressing times is 2-4 times, the magnetic field direction is parallel to the surface of the nanofiber membrane, and the magnetic field strength is 0.5-1 T.

[0018] By adopting the above technical scheme, the present application has the following beneficial effects: (1) The far infrared nanocarbon fiber composite fabric of the present application comprises a first fabric base layer, a far infrared electrothermal layer, and a second fabric base layer from bottom to top; the far infrared electrothermal layer comprises a nanocarbon fiber membrane, an electrode, and an electrified wire, the two sides of the nanocarbon fiber membrane are electrically connected with the electrode, the electrode is electrically connected with the electrified wire, and a complete circuit is formed among the electrode, the electrified wire, and the nanocarbon fiber membrane; the nanocarbon fiber membrane has good electrical conductivity and mechanical properties, and the heating is uniform; the mechanical properties of the prepared far infrared nanocarbon fiber composite fabric are also good, and the heating is relatively uniform and stable.

[0019] (2) The far infrared electrothermal layer of the present application is adhesively bonded together with the first fabric base layer and the second fabric base layer through insulation glue; the occurrence of electric leakage can be prevented, and harm to the human body can be avoided.

[0020] (3) The nanometer carbon fiber film of the present application is obtained by pre-mixing modified polytetrafluoroethylene and flame retardant, then adding aldehyde-based spiral nanometer carbon fiber, mixing and stirring uniformly, followed by airflow crushing, then high-speed rotary cutting fiberization after heating, then uniformly spreading in a spreader, and finally hot roller molding under a certain magnetic field.

[0021] (4) The advanced pre-irradiation treatment of polytetrafluoroethylene in the present application generates free radicals on the molecular chain, then introduces 4-allyl aniline, and grafts through the reaction of unsaturated carbon-carbon double bond and free radicals to introduce active group amino on the polytetrafluoroethylene molecular chain, so that the polytetrafluoroethylene is more uniformly mixed with aldehyde-based spiral nanometer carbon fiber and flame retardant.

[0022] (5) The nanometer carbon fiber film of the present application introduces flame retardant hexaphenylamine-based cyclotriphosphazene to improve the flame retardance of the nanometer carbon fiber film.

[0023] (6) The nanometer carbon fiber film of the present application selects aldehyde-based spiral nanometer carbon fiber, which first introduces polar group aldehyde group to effectively increase the dispersibility of spiral nanometer carbon fiber in the nanometer carbon fiber film, and secondly adopts spiral nanometer carbon fiber which has larger specific surface area than linear nanometer carbon fiber and can better contact with modified polytetrafluoroethylene and flame retardant, and the elasticity of spiral nanometer carbon fiber is better, so that the overall flexibility, tensile property and conductivity of the prepared nanometer carbon fiber film are better, and the heating is more uniform.

[0024] (7) The present application first pre-mixes modified polytetrafluoroethylene and flame retardant to form a pre-mixture, introduces ammonium persulfate during the pre-mixing, and the aniline on the modified polytetrafluoroethylene and flame retardant polymerizes to form a hyperbranched structure of polyaniline conductive network, a large number of cavities are formed in the pre-mixture, then aldehyde-based spiral nanometer carbon fiber is added for mixing, the aldehyde-based spiral nanometer carbon fiber quickly enters the cavities, the aldehyde group on the aldehyde-based spiral nanometer carbon fiber reacts with the remaining amino group in the cavities to form a Schiff base, the aldehyde-based spiral nanometer carbon fiber is uniformly dispersed in the pre-mixture, and the aldehyde-based spiral nanometer carbon fiber is connected with the polyaniline conductive network to form a conductive path, thereby enhancing the overall mechanical properties and conductivity of the nanometer carbon fiber film, and the nanometer carbon fiber film heats more uniformly.

[0025] (8) In the process of manufacturing the nanometer carbon fiber film of the present application, hot roller molding is performed under a certain magnetic field at 190-210 DEG C. At 190-210 DEG C, the polyaniline in the nanometer carbon fiber film melts, the spiral nanometer carbon fiber has nanometer nickel powder particles with catalyst therein, and under the action of the magnetic field, the spiral nanometer carbon fiber is arranged in the direction parallel to the surface of the nanometer carbon fiber film, thereby further increasing the conductivity of the nanometer carbon fiber film and making the heating uniformity of the nanometer carbon fiber film better. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, in which Figure 1 The structure diagram of the far-infrared nanocarbon fiber composite fabric of one embodiment of the present application.

[0027] The reference signs in the drawings are as follows: first fabric base layer 1, nanocarbon fiber film 2, second fabric base layer 3, electrode 4, power supply wire 5, and insulating glue 6. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the drawings and specific embodiments of the specification.

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts fall within the scope of protection of the present application.

[0031] It should be noted that: similar reference signs and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0032] In the description of the embodiments of the present application, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0033] In the description of the embodiments of the present application, it also needs to be explained that, unless otherwise explicitly specified and limited, the terms "arrange", "mount", "connect", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. The present application will be further described below in conjunction with the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0034] (total embodiment) See Figure 1 A far infrared nanocarbon fiber composite fabric includes a first fabric base layer 1, a far infrared electrothermal layer, and a second fabric base layer 3 from bottom to top; the far infrared electrothermal layer and the first fabric base layer 1, the second fabric base layer 3 are all bonded together by insulating glue 6; the far infrared electrothermal layer includes a nanocarbon fiber film 2, an electrode 4, and a power supply wire 5, both sides of the nanocarbon fiber film 2 are electrically connected with the electrode 4, the electrode 4 is electrically connected with the power supply wire 5, and the electrode 4, the power supply wire 5, and the nanocarbon fiber film 2 form a complete circuit.

[0035] The preparation steps of the nanocarbon fiber film are as follows: S1. 500 parts by mass of 2M hydrochloric acid, 2.5-5 parts by mass of surfactant ethoxy perfluorooctyl ethanol are mixed, stirred and uniformly dispersed, then 25-35 parts by mass of modified polytetrafluoroethylene, 0.5-1.5 parts by mass of hexaphenylamine cyclotriphosphazene are added, and the system is continuously stirred under ice bath conditions until the modified polytetrafluoroethylene and hexaphenylamine cyclotriphosphazene are uniformly suspended in the aqueous solution. Then 360-370 parts by mass of 2M ammonium persulfate aqueous solution is added dropwise at a rate of 3-5 s / drop, and the system is stirred for 55-65 min after the addition is completed. The temperature of the system is kept below 5℃ during the addition and reaction processes; S2. 10 parts by mass of aldehyde-based spiral nanocarbon fiber is added to the material obtained in step S1, and the system is heated to 35-45℃ under the condition of 18 kHz and 200 W ultrasonic wave, and then reacted for 6-10 h. Then the system is repeatedly washed and filtered with distilled water for 4-6 times, and then placed in a drying drum oven at 58-62℃ for drying for 23.5-24.5 h; S3. The material obtained in step S2 is subjected to airflow crushing, wherein the feeding airflow pressure is 0.6 MPa, and the crushing pressure is 0.4 MPa; S4. Heating the material obtained in step S3 and then high-speed rotary cutting to form fibers, wherein the heating temperature is 60-80℃, the holding time is 2.5-3.5h, and the specific steps of high-speed rotary cutting are as follows: S4.2.1 2000r / min for 5min; S4.2.2 4000r / min for 10min; S4.2.3 6000r / min for 5min; S5. Placing the material obtained in step S4 into a spreader to evenly spread, and then hot rolling under a certain magnetic field to form a nanometer carbon fiber film with a thickness of 140-150μm, wherein the hot rolling temperature is 190-210℃, the hot rolling times are 2-4 times; the magnetic field direction is parallel to the surface of the nanometer fiber film, and the magnetic field strength is 0.5-1T.

[0036] The preparation steps of the aldehyde group modified helical nanometer carbon fiber are as follows: (1) uniformly applying 8-12 parts by mass of nickel powder with a particle size of 30-200nm on a graphite substrate, placing the graphite substrate in the central part of a tubular electric furnace, and heating to 734-735℃ under a nitrogen atmosphere, then respectively introducing carbon source ethyne and carrier gas hydrogen at flow rates of 37-38mL / min and 62-63mL / min, wherein the ethyne passes through a container containing thiophene before entering the reaction chamber, and the thiophene is carried into the reactor as a growth promoter to react, and the reaction time is 25-35min, then the product is scraped off from the graphite substrate, ground in a mortar for two times, and helical nanometer carbon fiber is obtained; (2) mixing the helical nanometer carbon fiber obtained in step (1) with an acid mixture in a mass ratio of 1:18-22, then ultrasonic treatment for 10min, then heating to 115-125℃, stirring and refluxing for 1.8-2.2h, then adding deionized water in an amount of 70-90 times the mass of the helical nanometer carbon fiber, filtering, repeatedly washing and filtering with deionized water until the filtrate is neutral, and vacuum drying at 78-82℃ for 23-25h to obtain acidified helical nanometer carbon fiber; wherein the acid mixture is obtained by mixing 60wt% concentrated nitric acid and 98wt% concentrated sulfuric acid in a volume ratio of 1:3; (3) mixing the acidified helical nanometer carbon fiber obtained in step (2) with dichlorosulfoxide in a mass ratio of 1:38-42, then ultrasonic treatment for 10min, then heating to 70-80℃, stirring and refluxing for 23-25h, and removing the excess dichlorosulfoxide by distillation under reduced pressure to obtain acylated helical nanometer carbon fiber; (4) mixing the acylated helical nanometer carbon fiber obtained in step (3) with salicylaldehyde in a mass ratio of 1:58-59, then ultrasonic treatment for 10min, then heating to 115-125℃, stirring and reacting for 47-49h, then diluting with deionized water and filtering, repeatedly washing and filtering with deionized water for 4-6 times, and vacuum drying at 78-82℃ for 23-25h to obtain aldehyde group modified helical nanometer carbon fiber.

[0037] The preparation method of the modified polytetrafluoroethylene is as follows: polytetrafluoroethylene micropowder with a particle size of 0.5-20 μm is placed in an air atmosphere at room temperature with an activity of 1.85×10 14 Bq of 60 Co radioactive source to perform gamma ray irradiation treatment, to obtain pre-irradiation treated PTFE, wherein the absorption dose of the irradiation treated PTFE is 100 kGy, and the free radical concentration is ; 100 parts by mass of deionized water, 0.5-1 parts by mass of surfactant ethoxy perfluorooctyl ethanol are mixed, stirred and uniformly dispersed, then 8-12 parts by mass of pre-irradiation treated PTFE is added, and the pre-irradiation treated PTFE is uniformly suspended in the aqueous solution by continuing to stir, then 9-11 parts by mass of 4-allyl aniline, 0.009-0.011 parts by mass of polymerization inhibitor ferrous ammonium sulfate, and 0.09-0.11 parts by mass of concentrated sulfuric acid are added, and the reaction is stirred in a water bath at 68-72°C under nitrogen protection for 4.8-5.2 h, after the reaction is completed, centrifugal separation is performed, the upper liquid is removed, and the obtained precipitate is redispersed with water and centrifuged again, the above steps are repeated for 5-7 times, and then drying is performed in a blowing oven at 58-62°C for 23.5-24.5 h to obtain functionalized polytetrafluoroethylene.

[0038] Hexa-anilino-cyclotriphosphazene is prepared according to the preparation method of hexa-anilino-cyclotriphosphazene in the reference Sun De, Gao Weiquan, Li Ran, Zhang Long, Tang Shujuan. Synthesis of a new halogen-free flame retardant hexa-anilino-cyclotriphosphazene [J]. China Chlor-alkali, 2007 (12): 9-1042.

[0039] (Example 1) The structure of the far infrared nanocarbon fiber composite fabric of the present example is the same as that of the general example, and the difference lies in the preparation method of the nanocarbon fiber film. The preparation method of the nanocarbon fiber film of the present example is as follows: The preparation steps of the nanocarbon fiber film are as follows: S1. 500 parts by mass of 2M hydrochloric acid, 2.5 parts by mass of surfactant ethoxy perfluorooctyl ethanol are mixed, stirred and uniformly dispersed, then 25 parts by mass of modified polytetrafluoroethylene and 0.5 parts by mass of hexa-anilino-cyclotriphosphazene are added, and the stirring is continued under ice bath conditions until the modified polytetrafluoroethylene and hexa-anilino-cyclotriphosphazene are uniformly suspended in the aqueous solution, then 360 parts by mass of 2M ammonium persulfate aqueous solution is added dropwise at a rate of 3s / drop, and the reaction is stirred for 55 min after the dropwise addition is completed, and the temperature of the system is kept below 5°C during the dropwise addition and the reaction; S2. 10 parts by mass of aldehyde-modified spiral nanocarbon fiber is added to the material obtained in step S1, and the temperature is raised to 35°C under the condition of ultrasonic wave at 18 kHz and 200 W for reaction for 6 h, then filtration is performed, the filtration is repeated 4 times with distilled water, and then the nanocarbon fiber is dried in a drying blowing oven at 58°C for 23.5 h; S3. The material obtained in step S2 is subjected to jet milling, wherein the feeding gas pressure is 0.6 MPa, and the milling pressure is 0.4 MPa; S4. The material obtained in step S3 is heated and then subjected to high-speed rotary cutting for fiberization, wherein the heating temperature is 60℃, the holding time is 2.5 h, and the specific steps of high-speed rotary cutting are as follows: S4.2.1 rotation speed 2000 r / min, time 5 min; S4.2.2 rotation speed 4000 r / min, time 10 min; S4.2.3 rotation speed 6000 r / min, time 5 min; S5. The material obtained in step S4 is placed in a spreader and uniformly spread, and then subjected to hot roller pressing under a certain magnetic field to obtain a nanometer carbon fiber film with a thickness of 140 μm, wherein the hot roller pressing temperature is 190℃, and the hot roller pressing times are 4; the magnetic field direction is parallel to the surface of the nanometer fiber film, and the magnetic field strength is 0.5 T.

[0040] The preparation steps of the aldehyde group modified helical nanometer carbon fiber are as follows: (1) uniformly smear 8 parts by mass of nickel powder with a D50 of 30 nm on a graphite substrate, place it in the central part of a tubular electric furnace body, and heat it to 734℃ under a nitrogen atmosphere, then respectively introduce 37 mL / min and 62 mL / min of carbon source acetylene and carrier gas hydrogen, the acetylene is first passed through a container containing thiophene before entering the reaction chamber, and the thiophene is carried into the reactor as a growth promoter for reaction, the reaction time is 25 min, then the product is scraped off from the graphite substrate, ground in a mortar for two times, and helical nanometer carbon fiber is obtained; (2) the helical nanometer carbon fiber obtained in step (1) is mixed with an acid mixture in a mass ratio of 1:18, then ultrasonic treatment is performed for 10 min, then the temperature is raised to 115℃ and stirring reflux is performed for 1.8 h, then 70 times the mass of the helical nanometer carbon fiber of deionized water is added for dilution, filtration, repeated washing with deionized water, filtration until the filtrate is neutral, and vacuum drying at 78℃ for 23 h to obtain acidified helical nanometer carbon fiber; wherein the acid mixture is obtained by mixing 60wt% concentrated nitric acid and 98wt% concentrated sulfuric acid in a volume ratio of 1:3; (3) the acidified helical nanometer carbon fiber prepared in step (2) and dichlorosulfoxide are mixed in a mass ratio of 1:38, then ultrasonic treatment is performed for 10 min, then the temperature is raised to 70℃ and stirring reflux is performed for 23 h, and excess dichlorosulfoxide is removed by reduced pressure distillation to obtain acylated helical nanometer carbon fiber; (4) the acylated helical nanometer carbon fiber prepared in step (3) and salicylaldehyde are mixed in a mass ratio of 1:58, then ultrasonic treatment is performed for 10 min, then the temperature is raised to 115℃ and stirring reaction is performed for 47 h, after the reaction is completed, deionized water is added for dilution and filtration, repeated washing with deionized water and filtration for 4 times, and vacuum drying at 78℃ for 23 h to obtain aldehyde group modified helical nanometer carbon fiber.

[0041] The modified polytetrafluoroethylene is prepared as follows: Polytetrafluoroethylene micropowder with a D50 of 1 μm is placed in an air atmosphere at room temperature with an activity of 1.85 × 10⁻⁶. 14 BQ 60 Pre-irradiated PTFE was obtained by irradiating a Co radioactive source with gamma rays. The absorbed dose of the irradiated PTFE was 100 kGy and the free radical concentration was [missing information]. 100 parts by weight of deionized water and 0.5 parts by weight of surfactant ethoxyperfluorooctyl ethanol were mixed and dispersed evenly. Then, 8 parts by weight of pre-irradiated PTFE were added, and stirring was continued to suspend the pre-irradiated PTFE evenly in the aqueous solution. Subsequently, 9 parts by weight of 4-allyl aniline, 0.009 parts by weight of polymerization inhibitor ferrous ammonium sulfate, and 0.09 parts by weight of concentrated sulfuric acid were added. The reaction was carried out under nitrogen protection in a water bath at 68°C for 4.8 h. After the reaction was completed, the mixture was centrifuged to remove the supernatant. The precipitate was redispersed with water and centrifuged again. The above steps were repeated 5 times. Then, the mixture was dried in a forced-air oven at 58°C for 23.5 h to obtain functionalized polytetrafluoroethylene.

[0042] (Example 2) The structure of the far-infrared carbon nanofiber composite fabric in this embodiment is the same as that in the general embodiment, the difference being the preparation method of the carbon nanofiber membrane. The specific preparation method of the carbon nanofiber membrane in this embodiment is as follows: The preparation steps of the carbon nanofiber membrane are as follows: S1. Mix and disperse 500 parts by weight of 2M hydrochloric acid and 4.5 parts by weight of surfactant ethoxyperfluorooctylethanol. Then add 30 parts by weight of modified polytetrafluoroethylene and 1 part by weight of hexaphenylaminocyclotriphosphazene. Continue stirring under ice bath conditions until the modified polytetrafluoroethylene and hexaphenylaminocyclotriphosphazene are uniformly suspended in the aqueous solution. Then add 365 parts by weight of 2M ammonium persulfate aqueous solution dropwise at 4s / drop. After the addition is complete, stir the reaction for 60min. Keep the system temperature below 5℃ during the addition and reaction process. S2. Add 10 parts by mass of aldehyde-modified spiral carbon nanofibers to the material obtained in step S1, heat to 40°C and keep warm for 8 hours under ultrasonic conditions of 18kHz and 200W, then filter, wash repeatedly with distilled water 5 times, and then put into a drying oven at 60°C for 24 hours. S3. The material obtained in step S2 is subjected to airflow pulverization, wherein the feeding airflow pressure is 0.6 MPa and the pulverization pressure is 0.4 MPa; S4. The material obtained in step S3 is heated and then subjected to high-speed rotary cutting for fiberization. The heating temperature is 70℃ and the holding time is 3h. The specific steps of high-speed rotary cutting are as follows: S4.2.1 Rotation speed 2000r / min, time 5min; S4.2.2 Rotation speed 4000r / min, time 10min; S4.2.3 Rotation speed 6000r / min, time 5min. S5. The material obtained in step S4 is placed into a spreader and spread evenly, and then hot-rolled under a certain magnetic field to obtain a 145μm thick carbon nanofiber membrane. The hot rolling temperature is 200℃, and the hot rolling is performed 3 times. The magnetic field direction is parallel to the surface of the nanofiber membrane, and the magnetic field strength is 0.8T.

[0043] The preparation steps of aldehyde-based spiral carbon nanofibers are as follows: (1) 10 parts by mass of nickel powder with D50 of 100 nm are evenly coated on the graphite substrate and placed in the center of the tube furnace. The temperature is raised to 734.5℃ under nitrogen atmosphere. Then, carbon source acetylene and carrier gas hydrogen are introduced at 37.5 mL / min and 62.5 mL / min respectively. Before entering the reaction chamber, acetylene is first passed through a container containing thiophene. Thiophene is carried into the reactor as a growth promoter for reaction. The reaction time is 30 min. Then, the product is scraped off the graphite substrate and ground twice in a mortar to obtain spiral carbon nanofibers. (2) The spiral carbon nanofibers obtained in step (1) are mixed with the acid mixture at a mass ratio of 1:20 and ultrasonically treated for 10 min. Then, the temperature is raised to 120℃ and stirred and refluxed for 2 h. Subsequently, 80 times the mass of the spiral carbon nanofibers are added to dilute the mixture with deionized water, and the mixture is filtered. The mixture is then repeatedly washed with deionized water and filtered until the filtrate is neutral. The mixture is then vacuum dried at 80℃ for 24 h to obtain acidified spiral carbon nanofibers. The acid mixture is obtained by mixing 60 wt% concentrated nitric acid and 98 wt% concentrated sulfuric acid at a volume ratio of 1:3. (3) The acidified spiral carbon nanofibers obtained in step (2) and sulfoxide were mixed at a mass ratio of 1:40 and ultrasonically treated for 10 min. Then the temperature was raised to 75°C and stirred and refluxed for 24 h. Excess sulfoxide was removed by vacuum distillation to obtain acylated spiral carbon nanofibers. (4) The acylated helical carbon nanofibers obtained in step (3) were mixed with salicylaldehyde at a mass ratio of 1:58.5 and ultrasonically treated for 10 min. Then the temperature was raised to 120℃ and stirred for 48 h. After the reaction was completed, the mixture was diluted with deionized water and filtered. After washing with deionized water and filtering 5 times, the mixture was vacuum dried at 80℃ for 24 h to obtain aldehyde-based helical carbon nanofibers.

[0044] The modified polytetrafluoroethylene is prepared as follows: Polytetrafluoroethylene micropowder with a D50 of 10 μm is placed in an air atmosphere at room temperature with an activity of 1.85 × 10⁻⁶. 14BQ 60 Pre-irradiated PTFE was obtained by irradiating a Co radioactive source with gamma rays. The absorbed dose of the irradiated PTFE was 100 kGy and the free radical concentration was [missing information]. 100 parts by mass of deionized water and 0.8 parts by mass of surfactant ethoxyperfluorooctyl ethanol were mixed and dispersed evenly. Then, 10 parts by mass of pre-irradiated PTFE were added, and stirring was continued to suspend the pre-irradiated PTFE evenly in the aqueous solution. Subsequently, 10 parts by mass of 4-allyl aniline, 0.01 parts by mass of polymerization inhibitor ferrous ammonium sulfate, and 0.1 parts by mass of concentrated sulfuric acid were added. The reaction was carried out under nitrogen protection in a water bath at 70°C for 5 hours. After the reaction was completed, the mixture was centrifuged to remove the supernatant. The precipitate was redispersed with water and centrifuged again. The above steps were repeated 6 times. Then, the mixture was dried in a forced-air oven at 60°C for 24 hours to obtain functionalized polytetrafluoroethylene.

[0045] (Example 3) The structure of the far-infrared carbon nanofiber composite fabric in this embodiment is the same as that in the general embodiment, the difference being the preparation method of the carbon nanofiber membrane. The specific preparation method of the carbon nanofiber membrane in this embodiment is as follows: The preparation steps of the carbon nanofiber membrane are as follows: S1. Mix and disperse 500 parts by weight of 2M hydrochloric acid and 6 parts by weight of surfactant ethoxyperfluorooctylethanol evenly. Then add 35 parts by weight of modified polytetrafluoroethylene and 1.5 parts by weight of hexaphenylaminocyclotriphosphazene. Continue stirring under ice bath conditions until the modified polytetrafluoroethylene and hexaphenylaminocyclotriphosphazene are evenly suspended in the aqueous solution. Then add 370 parts by weight of 2M ammonium persulfate aqueous solution dropwise at 5s / drop. After the addition is complete, stir the reaction for 65min. Keep the system temperature below 5℃ during the addition and reaction process. S2. Add 10 parts by mass of aldehyde-modified spiral carbon nanofibers to the material obtained in step S1, heat to 45°C and keep warm for 10 hours under ultrasonic conditions of 18kHz and 200W, then filter, wash repeatedly with distilled water 6 times, and then put into a drying oven at 62°C for 24.5 hours. S3. The material obtained in step S2 is subjected to airflow pulverization, wherein the feeding airflow pressure is 0.6 MPa and the pulverization pressure is 0.4 MPa; S4. The material obtained in step S3 is heated and then subjected to high-speed rotary cutting for fiberization. The heating temperature is 80℃ and the holding time is 3.5h. The specific steps of high-speed rotary cutting are as follows: S4.2.1 Rotation speed 2000r / min, time 5min; S4.2.2 Rotation speed 4000r / min, time 10min; S4.2.3 Rotation speed 6000r / min, time 5min. S5. The material obtained in step S4 is placed into a spreader and spread evenly, and then hot-rolled under a certain magnetic field to obtain a 150μm thick carbon nanofiber membrane. The hot rolling temperature is 210℃, and the hot rolling is performed 3 times. The magnetic field direction is parallel to the surface of the nanofiber membrane, and the magnetic field strength is 1T.

[0046] The preparation steps of aldehyde-based spiral carbon nanofibers are as follows: (1) 12 parts by mass of nickel powder with D50 of 200 nm are evenly coated on the graphite substrate and placed in the center of the tube furnace. The temperature is raised to 735℃ under nitrogen atmosphere. Then, carbon source acetylene and carrier gas hydrogen are introduced at 38 mL / min and 63 mL / min respectively. Before entering the reaction chamber, acetylene is first passed through a container containing thiophene. Thiophene is carried into the reactor as a growth promoter for reaction. The reaction time is 35 min. Then, the product is scraped off the graphite substrate and ground twice in a mortar to obtain spiral carbon nanofibers. (2) The spiral carbon nanofibers obtained in step (1) were mixed with the acid mixture at a mass ratio of 1:22 and ultrasonically treated for 10 min. Then, the temperature was raised to 125℃ and stirred and refluxed for 2.2 h. Subsequently, 90 times the mass of the spiral carbon nanofibers were added to dilute the mixture with deionized water, and the mixture was filtered. The mixture was then repeatedly washed with deionized water and filtered until the filtrate was neutral. The mixture was then vacuum dried at 82℃ for 25 h to obtain the acidified spiral carbon nanofibers. The acid mixture was obtained by mixing 60 wt% concentrated nitric acid and 98 wt% concentrated sulfuric acid at a volume ratio of 1:3. (3) The acidified spiral carbon nanofibers obtained in step (2) and sulfoxide were mixed at a mass ratio of 1:42 and ultrasonically treated for 10 min. Then the temperature was raised to 80°C and stirred and refluxed for 25 h. Excess sulfoxide was removed by vacuum distillation to obtain acylated spiral carbon nanofibers. (4) The acylated helical carbon nanofibers obtained in step (3) were mixed with salicylaldehyde at a mass ratio of 1:59 and ultrasonically treated for 10 min. Then the temperature was raised to 125℃ and stirred for 49 h. After the reaction was completed, the mixture was diluted with deionized water and filtered. After repeated washing with deionized water and filtration 6 times, the mixture was vacuum dried at 82℃ for 25 h to obtain aldehyde-based helical carbon nanofibers.

[0047] The modified polytetrafluoroethylene is prepared as follows: 20 μm polytetrafluoroethylene micropowder is placed in an air atmosphere at room temperature with an activity of 1.85 × 10⁻⁶. 14 BQ 60 Pre-irradiated PTFE was obtained by irradiating a Co radioactive source with gamma rays. The absorbed dose of the irradiated PTFE was 100 kGy and the free radical concentration was [missing information]. 100 parts by mass of deionized water and 1 part by mass of surfactant ethoxyperfluorooctyl ethanol were mixed and stirred until evenly dispersed. Then, 12 parts by mass of pre-irradiated PTFE were added, and stirring was continued to suspend the pre-irradiated PTFE evenly in the aqueous solution. Subsequently, 11 parts by mass of 4-allyl aniline, 0.011 parts by mass of polymerization inhibitor ferrous ammonium sulfate, and 0.11 parts by mass of concentrated sulfuric acid were added. The reaction was carried out under nitrogen protection in a water bath at 72°C for 5.2 hours. After the reaction was completed, the mixture was centrifuged to remove the supernatant. The precipitate was redispersed with water and centrifuged again. The above steps were repeated 7 times. The mixture was then dried in a forced-air oven at 62°C for 24.5 hours to obtain functionalized polytetrafluoroethylene.

[0048] (Comparative Example 1) The only difference between Comparative Example 1 and Example 2 is that the raw materials for the nanofiber membrane in Comparative Example 1 are helical nanofibers, flame retardant hexaphenylamine cyclotriphosphazene, and modified polytetrafluoroethylene. The remaining steps and components are the same as in Example 2.

[0049] (Comparative Example 2) The only difference between Comparative Example 2 and Example 2 is that the raw materials for the nanofiber membrane in Comparative Example 2 are aldehyde-based nanofibers, flame retardant hexaphenylamine cyclotriphosphazene, and modified polytetrafluoroethylene. The remaining steps and components are the same as in Example 2.

[0050] The preparation steps of aldehyde-based carbon nanofibers are as follows: (1) The carbon nanofibers with a diameter of about 150 nm and a length of 10~20 μm were mixed with the acid mixture at a mass ratio of 1:20. The mixture was then treated with ultrasonic waves at 25 kHz for 10 min, and then heated to 120 °C and stirred and refluxed for 2 h. Subsequently, 80 times the mass of the carbon nanofibers were added to dilute the mixture with deionized water, and the mixture was filtered through a mixed fiber microporous membrane with a pore size of 0.22 μm. The mixture was then repeatedly washed with deionized water and filtered until the filtrate was neutral. The filtrate was then vacuum dried at 80 °C for 24 h to obtain the acidified carbon nanofibers. The acid mixture was obtained by mixing 60 wt% concentrated nitric acid and 98 wt% concentrated sulfuric acid at a volume ratio of 1:3. (2) The acidified carbon nanofibers obtained in step (1) and sulfoxide were mixed at a mass ratio of 1:40, and then treated with ultrasonic waves at 25 kHz for 10 min. After that, the temperature was raised to 75 °C and stirred and refluxed for 24 h. Excess sulfoxide was removed by vacuum distillation to obtain acylated carbon nanofibers. (3) The acylated carbon nanofibers obtained in step (2) were mixed with salicylaldehyde at a mass ratio of 1:58.5, and then treated with ultrasonic waves at 25 kHz for 10 min. After that, the mixture was heated to 120 °C and stirred for 48 h. After the reaction was completed, the mixture was diluted with deionized water and filtered. After washing with deionized water and filtering five times, the mixture was dried under vacuum at 80 °C for 24 h to obtain aldehyde-based carbon nanofibers.

[0051] (Comparative Example 3) The only difference between Comparative Example 3 and Example 2 is that the raw materials for the nanofiber membrane in Comparative Example 3 are aldehyde-based magnetic nanofibers, flame retardant hexaphenylamine cyclotriphosphazene, and modified polytetrafluoroethylene. The remaining steps and components are the same as in Example 2.

[0052] The preparation steps of aldehyde-based magnetic carbon nanofibers are as follows: (1) Polyacrylonitrile and nickel acetylacetone were added to dimethylformamide and stirred at 75°C until completely dissolved to obtain a homogeneous spinning solution, wherein the mass fraction of polyacrylonitrile was 8% and the mass fraction of nickel acetylacetone was 9%. Then, electrospinning was performed using aluminum foil as the receiving substrate, a spinning voltage of 12kV, a feed pump speed of 0.6mL / h, and a distance of 15cm between the spinning needle and the collecting roller. After drying at 75°C for 25h, pre-oxidation was performed using a muffle furnace. During the pre-oxidation process, an alumina ceramic substrate was used for pressing to reduce fiber shrinkage and curling during oxidation. The muffle furnace was first heated to 202°C and held for 11min, then heated to 222°C and held for 11min, then heated to 252°C and held for 11min, and finally heated to 282°C and held for 2.2h to complete the pre-oxidation. Then, it was placed in a tube furnace and carbonized at 1210°C for 2.2h under a nitrogen atmosphere. h, grind through a 300-mesh sieve to obtain magnetic carbon nanofibers; (2) After mixing the magnetic carbon nanofibers with the acid mixture at a mass ratio of 1:20, the mixture was treated with ultrasonic waves at 25 kHz for 10 min, then heated to 120 °C and stirred under reflux for 2 h. Subsequently, 80 times the mass of the magnetic carbon nanofibers were added to dilute the mixture with deionized water and filtered. The mixture was then repeatedly washed with deionized water and filtered until the filtrate was neutral. The filtrate was then vacuum dried at 80 °C for 24 h to obtain the acidified magnetic carbon nanofibers. The acid mixture was obtained by mixing 60 wt% concentrated nitric acid and 98 wt% concentrated sulfuric acid at a volume ratio of 1:3. (3) The acidified magnetic carbon nanofibers obtained in step (2) and sulfoxide were mixed at a mass ratio of 1:40, and then treated with ultrasonic waves at 25 kHz for 10 min. After that, the temperature was raised to 75 °C and stirred and refluxed for 24 h. Excess sulfoxide was removed by vacuum distillation to obtain acylated magnetic carbon nanofibers. (4) The acylated magnetic carbon nanofibers obtained in step (3) are mixed with salicylaldehyde at a mass ratio of 1:58.5, treated with ultrasonic waves at 25 kHz for 10 min, and then heated to 120 °C and stirred for 48 h. After the reaction is completed, the mixture is diluted with deionized water and filtered. After repeated washing with deionized water and filtration 5 times, the mixture is dried under vacuum at 80 °C for 24 h to obtain aldehyde-based magnetic carbon nanofibers.

[0053] (Comparative Example 4) The only difference between Comparative Example 4 and Example 2 is that the raw materials for the nanofiber membrane in Comparative Example 4 are aldehyde-based spiral nanofibers, flame retardant ammonium polyphosphate, and modified polytetrafluoroethylene. The remaining steps and components are the same as in Example 2.

[0054] (Comparative Example 5) The only difference between Comparative Example 5 and Example 2 is that the raw materials for the nanofiber membrane in Comparative Example 5 are aldehyde-based spiral nanofibers, flame retardant hexaphenylamine cyclotriphosphazene, and polytetrafluoroethylene. The remaining steps and components are the same as in Example 2.

[0055] (Comparative Example 6) The only difference between Comparative Example 6 and Example 2 is the preparation steps of the nanofiber membrane in Comparative Example 6; the other steps and components are the same as in Example 2.

[0056] The preparation steps of the carbon nanofiber membrane are as follows: S1. Aldehyde-based spiral carbon nanofibers, modified polytetrafluoroethylene, and hexaphenylamine cyclotriphosphazene are mixed and stirred evenly at a mass ratio of 10:30:1. The specific mixing steps are as follows: S1.1 Revolution speed 1000 r / min, time 10 min, revolution-to-rotation speed ratio 100%; S1.2 Revolution speed 2000 r / min, time 15 min, revolution-to-rotation speed ratio 120%; S1.3 Revolution speed 1500 r / min, time 10 min, revolution-to-rotation speed ratio 120%. S3. The material obtained in step S1 is subjected to airflow pulverization, wherein the feeding airflow pressure is 0.6 MPa and the pulverization pressure is 0.4 MPa; S3. The material obtained in step S2 is heated and then subjected to high-speed rotary cutting for fiberization. The heating temperature is 70℃ and the holding time is 3h. The specific steps of high-speed rotary cutting are as follows: S4.2.1 Rotation speed 2000r / min, time 5min; S4.2.2 Rotation speed 4000r / min, time 10min; S4.2.3 Rotation speed 6000r / min, time 5min. S4. The material obtained in step S3 is placed into a spreader and spread evenly, and then hot-rolled under a certain magnetic field to obtain a 145μm thick carbon nanofiber membrane. The hot rolling temperature is 200℃, and the hot rolling is performed 3 times. The magnetic field direction is parallel to the surface of the nanofiber membrane, and the magnetic field strength is 0.8T.

[0057] (Comparative Example 7) The only difference between Comparative Example 7 and Example 2 is that in Comparative Example 7, the material obtained in step S4 of the preparation step S5 of the nanofiber membrane is placed into a spreader and spread evenly before being directly subjected to hot roll forming. The remaining steps and components are the same as in Example 2.

[0058] (Comparative Examples 8-11) The only difference between Comparative Examples 8-11 and Example 2 is that the hot rolling temperatures in step S5 of the preparation of the nanofiber membranes in Comparative Examples 8-11 are 180°C, 185°C, 210°C, and 220°C, respectively. The other steps and components are the same as in Example 2.

[0059] Example of effect Tensile strength test: The carbon nanofiber membranes prepared in the examples and comparative examples were made into specimens with a width of (10+0.1) mm and a length of 80±2 mm. Tensile strength was then tested using a tensile testing machine with an initial distance of (80±5) mm between the clamps and a testing speed of 3 mm / min. Resistivity test: The nanofiber films prepared in the examples and comparative examples were cut into 3×3 cm squares and placed under the four-probe needle for testing to obtain the resistance value of the material. The resistivity of the material can be calculated according to the resistivity formula ρ=R·s / L=R·d·ω / L, where ρ represents the resistivity of the material (mΩ·cm), R represents the resistance of the material (mΩ / sq), d represents the thickness of the material (cm), ω represents the width of the material (cm), and L represents the length of the material (cm).

[0060] Temperature difference test: After the far-infrared electric heating layer prepared in the examples and comparative examples is energized, 20 temperature measuring points are taken at equal intervals on the nanofiber film for temperature measurement. The temperature difference of the far-infrared electric heating layer is the difference between the highest temperature measuring point and the lowest temperature measuring point.

[0061] Flexibility test: whether the carbon nanofiber membranes prepared in the examples and comparative examples cracked after being bent at 60°.

[0062] Table 1 below shows the performance test results of the carbon nanofiber membranes prepared in Examples 1-3 and Comparative Examples 1-9: Table 1

[0063] Comparing the data from Examples 1-3 and Comparative Examples 1-11 in Table 1, it can be seen that the carbon nanofiber films prepared in Examples 1-3 have better mechanical and electrical properties and more uniform heat generation.

[0064] Comparative Example 1 used helical carbon nanofibers instead of aldehyde-modified helical carbon nanofibers. The aldehyde-modification treatment improved the dispersibility and conductivity of the helical carbon nanofibers. Compared with Comparative Example 1, the carbon nanofiber film prepared in Example 2 had better tensile strength and conductivity, and more uniform heat generation.

[0065] Comparative Example 2 uses aldehyde-based linear carbon nanofibers instead of spiral ones, which are non-magnetic. The spiral structure has a larger specific surface area and better flexibility. Compared with Comparative Example 2, the carbon nanofiber film prepared in Example 2 has better tensile strength, flexibility and electrical conductivity, and more uniform heat generation.

[0066] Comparative Example 3 used aldehyde-based linear magnetic carbon nanofibers instead of spiral ones. Compared with Comparative Example 3, the carbon nanofiber membrane prepared in Example 2 had better tensile strength, flexibility and electrical conductivity.

[0067] The flame retardant used in Comparative Example 4 was ammonium polyphosphate instead of hexaphenylamine cyclotriphosphazene. Compared with Comparative Example 4, the nanofiber membrane prepared in Example 2 had better tensile and electrical conductivity and more uniform heat generation.

[0068] Comparative Example 5 used unmodified polytetrafluoroethylene. Compared with Example 2, the nanofiber membrane prepared in Comparative Example 5 had better tensile strength, flexibility and electrical conductivity, and more uniform heat generation.

[0069] Comparative Example 6 did not premix the modified polytetrafluoroethylene and flame retardant to form a premix before adding the aldehyde-based spiral carbon nanofibers. Instead, the aldehyde-based spiral carbon nanofibers, modified polytetrafluoroethylene, and hexaphenylamine cyclotriphosphazene were directly mixed and stirred evenly. Compared with Example 2, the carbon nanofiber membrane prepared by Comparative Example 6 had better tensile strength, flexibility, and electrical conductivity, and more uniform heat generation.

[0070] Comparative Example 7 was not hot-rolled under a magnetic field, so the spiral carbon nanofibers could not be oriented. Compared with Comparative Example 7, the carbon nanofiber film prepared in Example 2 had better tensile and electrical properties and more uniform heating.

[0071] In Comparative Examples 8-9, the hot rolling temperature was below 190°C, so the polyaniline could not melt and the spiral carbon nanofibers could not be oriented under the action of a magnetic field. Compared with Comparative Examples 8-9, the carbon nanofiber film prepared in Example 2 had better tensile and electrical conductivity and more uniform heating.

[0072] In Comparative Examples 10-11, the hot rolling temperature was higher than 210°C, resulting in partial Schiff base thermal decomposition and weaker bonding between the spiral carbon nanofibers, flame retardants, and modified polytetrafluoroethylene. Compared with Comparative Examples 10-11, the carbon nanofiber membrane prepared in Example 2 had better tensile and electrical properties.

[0073] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A far-infrared nanofiber composite fabric, characterized in that, The far-infrared nano-carbon fiber composite fabric includes, from bottom to top, a first fabric base layer (1), a far-infrared electrothermal layer, and a second fabric base layer (3); the far-infrared electrothermal layer includes a nano-carbon fiber film (2), an electrode (4), and an electric conductor (5). The nano-carbon fiber film (2) is electrically connected to both sides of the electrode (4), and the electrode (4) is electrically connected to the electric conductor (5). A complete circuit is formed between the electrode (4), the electric conductor (5), and the nano-carbon fiber film (2).

2. The far-infrared nanofiber composite fabric according to claim 1, characterized in that, The far-infrared electric heating layer is bonded to the first fabric base layer (1) and the second fabric base layer (3) by insulating adhesive.

3. The far-infrared nanofiber composite fabric according to claim 1, characterized in that, The nanofiber membrane (2) is obtained by first pre-mixing modified polytetrafluoroethylene and flame retardant, then adding aldehyde-based spiral nanofibers and mixing them evenly, followed by air jet pulverization, then high-speed rotary cutting and fiberization after heating, then spreading it evenly in a spreader, and finally hot rolling molding under a certain magnetic field.

4. The far-infrared nanofiber composite fabric according to claim 3, characterized in that, The modified polytetrafluoroethylene was obtained by grafting 4-allyl aniline onto pre-irradiated PTFE.

5. The far-infrared nanofiber composite fabric according to claim 3, characterized in that, The preparation steps of the carbon nanofiber membrane (2) are as follows: S1. Mix and disperse 500 parts by weight of 2M hydrochloric acid and 2.5-5 parts by weight of surfactant ethoxyperfluorooctyl ethanol evenly. Then add 25-35 parts by weight of modified polytetrafluoroethylene and 0.5-1.5 parts by weight of flame retardant. Continue stirring under ice bath conditions until the modified polytetrafluoroethylene and flame retardant are evenly suspended in the aqueous solution. Then add 360-370 parts by weight of 2M ammonium persulfate aqueous solution dropwise at 3-5 seconds. After the addition is complete, stir the reaction for 55-65 minutes. Keep the system temperature below 5°C during the addition and reaction process. S2. Add 10 parts by mass of aldehyde-modified spiral carbon nanofibers to the material obtained in step S1, heat to 35~45℃ under ultrasonic conditions of 18kHz and 200W and keep at the temperature for 6~10h, then filter, wash repeatedly with distilled water 4~6 times, and then put into a drying oven at 58~62℃ for 23.5~24.5h. S3. The material obtained in step S2 is subjected to air jet milling; S4. The material obtained in step S3 is heated and then high-speed rotary cut into fibers; S5. Place the material obtained in step S4 into a spreader and spread it evenly, and then perform hot roll forming under a certain magnetic field.

6. The far-infrared nanofiber composite fabric according to claim 5, characterized in that, The flame retardant is hexaphenylamine cyclotriphosphazene.

7. The far-infrared nanofiber composite fabric according to claim 5, characterized in that, The preparation steps of the aldehyde-based spiral carbon nanofibers are as follows: (1) 8-12 parts by weight of nickel powder with a particle size of 30-200 nm are evenly coated on the graphite substrate and placed in the center of the tubular electric furnace. The temperature is raised to 734-735℃ under nitrogen atmosphere. Then, carbon source acetylene and carrier gas hydrogen are introduced at 37-38 mL / min and 62-63 mL / min respectively. Before entering the reaction chamber, acetylene is first passed through a container containing thiophene. Thiophene is carried into the reactor as a growth promoter for reaction. The reaction time is 25-35 min. Then, the product is scraped off from the graphite substrate and ground twice in a mortar to obtain spiral carbon nanofibers. (2) The spiral carbon nanofibers obtained in step (1) are mixed with the acid mixture at a mass ratio of 1:18~22 and ultrasonically treated for 10 min. Then, the temperature is raised to 115~125℃ and stirred and refluxed for 1.8~2.2 h. Subsequently, 70~90 times the mass of the spiral carbon nanofibers are added to dilute the mixture with deionized water, and the mixture is filtered. The mixture is then repeatedly washed with deionized water and filtered until the filtrate is neutral. The mixture is then vacuum dried at 78~82℃ for 23~25 h to obtain acidified spiral carbon nanofibers. The acid mixture is obtained by mixing 60wt% concentrated nitric acid and 98wt% concentrated sulfuric acid at a volume ratio of 1:

3. (3) The acidified spiral carbon nanofibers obtained in step (2) and sulfoxide were mixed at a mass ratio of 1:38~42 and ultrasonically treated for 10 min. Then the temperature was raised to 70~80℃ and stirred and refluxed for 23~25 h. Excess sulfoxide was removed by vacuum distillation to obtain acylated spiral carbon nanofibers. (4) The acylated helical carbon nanofibers obtained in step (3) are mixed with salicylaldehyde at a mass ratio of 1:58~59 and ultrasonically treated for 10 min. Then, the temperature is raised to 115~125℃ and stirred for 47~49 h. After the reaction is completed, the mixture is diluted with deionized water and filtered. After repeated washing with deionized water and filtration 4~6 times, the mixture is vacuum dried at 78~82℃ for 23~25 h to obtain aldehyde-based helical carbon nanofibers.

8. The far-infrared nanofiber composite fabric according to claim 5, characterized in that, The modified polytetrafluoroethylene is prepared as follows: Polytetrafluoroethylene micropowder with a particle size of 0.5~20μm is placed in an air atmosphere at room temperature with an activity of 1.85×10⁻⁶. 14 BQ 60 Pre-irradiated PTFE was obtained by irradiating a Co radioactive source with gamma rays. The absorbed dose of the irradiated PTFE was 100 kGy and the free radical concentration was [missing information]. 100 parts by weight of deionized water and 0.5-1 parts by weight of surfactant ethoxyperfluorooctyl ethanol were mixed and dispersed evenly. Then, 8-12 parts by weight of pre-irradiated PTFE were added, and stirring was continued to suspend the pre-irradiated PTFE evenly in the aqueous solution. Subsequently, 9-11 parts by weight of 4-allyl aniline, 0.009-0.011 parts by weight of polymerization inhibitor ferrous ammonium sulfate, and 0.09-0.11 parts by weight of concentrated sulfuric acid were added. The reaction was carried out under nitrogen protection in a water bath at 68-72°C for 4.8-5.2 hours. After the reaction was completed, the mixture was centrifuged to remove the supernatant. The precipitate was redispersed with water and centrifuged again. The above steps were repeated 5-7 times. Then, the mixture was dried in a forced-air oven at 58-62°C for 23.5-24.5 hours to obtain functionalized polytetrafluoroethylene.

9. The far-infrared nanofiber composite fabric according to claim 5, characterized in that, The heating temperature of S4 is 60~80℃, and the holding time is 2.5~3.5h.

10. The far-infrared nanofiber composite fabric according to claim 5, characterized in that, The hot rolling temperature of S5 is 190~210℃, and the number of hot rolling cycles is 2~4; the magnetic field direction is parallel to the surface of the nanofiber membrane, and the magnetic field strength is 0.5~1T.

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