Continuous spinning device and spinning method for pitch-based carbon fibers

Abstract

The invention discloses a continuous spinning device and method for pitch-based carbon fibers, and belongs to the technical field of carbon fibers. The technical problems that in the prior art, due to the fact that the pitch-based carbon fibers are large in diameter, local excessive oxidation or insufficient oxidation is prone to occurring in the pre-oxidation treatment process, cracks, holes and other defects are formed in the surfaces and the interiors of the carbon fibers, and the mechanical performance is affected are solved. The spinning device comprises an air storage tank, a material storage tank, a magnetic control spinning device, an electrostatic device, a melt spinning drafting device and a control system. According to the spinning device, a melt spinning, magnetic field and electrostatic spinning combined technology is adopted, pitch molecular orientation regulation is achieved by regulating the intensity of a magnetic field, then the drafting force of carbon fiber precursors is regulated under the assistance of a high-voltage electric field, pitch carbon fibers with the diameter smaller than 1 micrometer are obtained, and the pitch carbon fibers are subjected to high-temperature carbonization in the later-stage pre-oxidation-carbonization treatment process. The number of internal defects of the fiber can be effectively reduced, and the mechanical property and the conduction property of the carbon fiber are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon fiber, and specifically relates to a continuous spinning device and a spinning method for asphalt-based carbon fiber. Background Art

[0002] Asphalt-based carbon fiber is usually made of petroleum asphalt or coal asphalt as raw materials. After asphalt refining, melt spinning, pre-oxidation, and carbonization, it is a fibrous carbon material with certain mechanical properties. It has been widely used in the fields of national defense, military industry, and high-end equipment. Compared with polyacrylonitrile-based (PAN) carbon fiber, asphalt-based carbon fiber has a thicker diameter, often exceeding 10μm. During the pre-oxidation process, it is easy to have local over-oxidation or insufficient oxidation, resulting in defects such as splitting and holes on the surface and inside of the carbon fiber, affecting the mechanical properties of the carbon fiber.

[0003] The thinning of asphalt-based carbon fiber is closely related to the spinnability of the precursor asphalt. The traditional melt-spinning drafting process cannot over-stretch the carbon fiber precursor, otherwise it is easy to cause breakage and affect the continuity of melt spinning. In addition, the molten asphalt is quickly cooled and solidified after leaving the spinneret during the melt spinning process. Compared with polyacrylonitrile-based carbon fiber, the later pre-oxidation-carbonization process of asphalt-based carbon fiber only allows a weak drafting force to be applied, which has no significant effect on the contraction of fiber diameter. In order to improve the melt spinning efficiency of asphalt and obtain carbon fiber precursors with uniform quality and smaller diameter, people have conducted various explorations on melt spinning devices and processes. For example, a Chinese patent discloses a mesophase asphalt spinning winding device (publication number 203959519U), which reduces a rotating guide wheel by using only one guide wheel and a winding wheel, simplifies the mechanical structure of the winding device, improves the measurement and control ability of tension, and significantly improves the accuracy of tension control, meeting the precision requirements of tension of mesophase asphalt carbon fiber during the drawing process. However, this method does not improve the particle size of asphalt-based carbon fiber. Another example is a Chinese patent that discloses a special-shaped spinneret (CN204080208U), which realizes the melt spinning of asphalt by changing the shape of the spinneret spinneret holes. Compared with the traditional circular spinneret holes, it is found that the special-shaped spinneret holes developed by this method enhance the shear force of asphalt during the melting process, improve the homogeneity of asphalt fibers to a certain extent, and can effectively avoid defects inside the fibers during the later heat treatment process, greatly improving the toughness and tensile strength of the fibers, but this method cannot effectively reduce the cross-sectional area of ​​the carbon fibers. Therefore, it is of great significance to develop a new type of melt spinning device and spinning method for the melt spinning performance of the precursor asphalt to prepare asphalt-based carbon fibers with small diameters (<1μm). Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a continuous spinning device and a spinning method for asphalt-based carbon fibers. The spinning device and the spinning method adopt a combined process of melt spinning and magnetic field plus electrostatic spinning. The orientation of asphalt molecules is regulated by adjusting the strength of the magnetic field, and then the drawing force of the carbon fiber precursor is regulated with the assistance of a high-voltage electric field to obtain asphalt carbon fibers with a diameter of less than 1 μm. The asphalt carbon fibers are heated more evenly during the subsequent pre-oxidation-carbonization treatment process, which can effectively reduce the number of internal defects in the fibers and improve the mechanical properties and conduction characteristics of the carbon fibers.

[0005] The present invention is achieved through the following technical solutions:

[0006] The continuous spinning device of the present invention comprises a gas storage tank, a material storage tank, a magnetron spinning device, an electrostatic device, a melt-spinning drafting device and a control system;

[0007] The gas storage tank is used to store inert atmosphere;

[0008] The material storage tank is connected to the gas storage tank through a pipeline provided with a back pressure valve. The material storage tank is provided with a venting valve, a negative pressure degassing device, a heating device and a temperature sensor. The venting valve is used for venting, the negative pressure degassing device degasses the material in the material storage tank, the heating device heats the material in the material storage tank, and the temperature sensor collects the temperature of the material in the material storage tank and transmits it to the control system;

[0009] The magnetically controlled spinning device comprises a magnetic field generator and a spinning device, wherein the spinning device is connected to a material storage tank through a pipeline with a valve, and the delivered material is ejected through a spinneret of the spinning device, and the magnetic field generator is fixed on the outer surface of the spinning device to generate a magnetic field;

[0010] The electrostatic device forms an electric field between the spinneret of the magnetron spinning device and the take-up roller of the melt-spinning drafting device;

[0011] The receiving roller of the melt-spinning drafting device draws and reels the raw yarn ejected from the spinneret, and collects stress data of the raw yarn on the receiving roller through a stress sensor, and transmits the data to the control system;

[0012] The control system is connected to the heating device, temperature sensor, magnetic field generator, electrostatic device, motor and stress sensor of the melt-spinning drafting device. The control system adjusts the heating temperature of the heating device according to the temperature data collected by the temperature sensor, adjusts the rotation speed of the wire collecting roller by adjusting the motor according to the stress data collected by the stress sensor, and controls the switch and magnetic field strength of the magnetic field generator, as well as the switch and electrostatic strength of the electrostatic device.

[0013] Preferably, the inert atmosphere is nitrogen, argon or helium.

[0014] Preferably, the negative pressure foam reduction device comprises a negative pressure valve and a vacuum pump, the negative pressure valve is arranged on the upper surface of the storage tank, and the vacuum pump is connected to the negative pressure valve through a pipeline;

[0015] More preferably, the negative pressure valve and the vacuum pump are both connected to a control system, and the control system controls the switching of the negative pressure valve and the vacuum pump.

[0016] Preferably, the heating device is an electric heating sleeve, which is mounted outside the storage tank. The electric heating sleeve is powered by an external power supply to heat the storage tank.

[0017] Preferably, the magnetic field generator generates a magnetic field with a temperature 50-80° C. above the softening point of the material.

[0018] Preferably, the output power of the magnetic field generator is in the range of 100-1000KW.

[0019] Preferably, the magnetic field generator is an excitation coil wound on the side wall of the spinning pot.

[0020] Preferably, the spinning device comprises a spinning pot, a spinning plate, a copper gasket and a distribution plate; the top of the spinning pot is connected to the storage tank through a pipeline with a valve, and the bottom of the spinning pot is provided with a through hole, and the distribution plate, the copper gasket and the spinning plate are fixed on the through hole in sequence from top to bottom;

[0021] More preferably, the number of spinnerets on the spinneret is 1-100, and the diameter of the spinnerets is 1-3 μm;

[0022] More preferably, the diameter of the distribution holes on the distribution plate is 1.5-2.5 mm, and particularly preferably 2 mm.

[0023] Preferably, the spinning pressure of the spinning device is 0.2-1.2 MPa.

[0024] Preferably, the electrostatic device comprises an electrostatic emitter and an electrostatic controller; the positive plate and the negative plate of the electrostatic emitter are respectively placed below the magnetron spinning device and above the receiving roller of the melt spinning drafting device, the control system is connected to the electrostatic controller, and the control system controls the electrostatic emitter through the electrostatic controller;

[0025] More preferably, the voltage of the electrostatic emitter is 1-3KV.

[0026] Preferably, the rotation speed of the wire collecting roller is 300-500r / min.

[0027] Preferably, the control system is connected to both the back pressure valve and the valve, and the control system controls the switching of the back pressure valve and the valve.

[0028] Preferably, the control system is fixed outside the motor of the melt-spinning drafting device.

[0029] Preferably, the continuous spinning device of the asphalt-based carbon fiber further comprises a control instrument, which is connected to the control system, and the control system is controlled by the control instrument.

[0030] The present invention also provides a method for preparing asphalt-based carbon fiber using the above-mentioned continuous spinning device, the steps of which are as follows:

[0031] Step 1: Place the spinnable asphalt in a storage tank, open the vent valve of the storage tank and the switch of the gas storage tank, and adjust the pressure in the storage tank through the back pressure valve. After purging the inner cavity of the storage tank with an inert atmosphere, close the vent valve of the storage tank and the switch of the gas storage tank and turn on the heating device to heat the storage tank to a temperature higher than the softening point of the spinnable asphalt by 50-80°C, and keep it warm for 1-3 hours.

[0032] Step 2: After turning on the negative pressure degassing device to degas the material in the storage tank, turn on the switch of the gas storage tank, and adjust the pressure in the storage tank through the back pressure valve and keep it stable, and at the same time turn on the magnetron spinneret, the electrostatic device and the melt-spinning drafting device to make the molten asphalt flow out from the spinneret holes of the spinneret, set the temperature and power of the magnetron spinneret and the voltage and current of the electrostatic device, and adjust the speed of the collection roller to keep the asphalt-based carbon fiber precursor perpendicular to the axial direction of the collection roller, and obtain the asphalt-based carbon fiber precursor on the collection roller;

[0033] Step 3. After spinning, the asphalt-based carbon fiber raw yarn is removed, first heated to 250-280°C at 1°C / min in an air atmosphere for 0.5-3h, and then heated to 800-1200°C at 5°C / min in an inert atmosphere for carbonization treatment for 0.5-2h to obtain asphalt-based carbon fiber.

[0034] Preferably, in step 1 and step 2, the pressure of the inert atmosphere in the storage tank is adjusted to 0.1-5 MPa respectively by a back pressure valve.

[0035] Preferably, in step 1, the heating rate of the heating device is 1-5°C / min.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The continuous spinning device of asphalt-based carbon fiber of the present invention has a compact structure, reliable principle and is easy to operate; the storage tank adopts a real-time temperature control design, and can set a suitable melt-spinning temperature according to the type of spinnable asphalt to ensure that the molten asphalt is in the most suitable temperature range. At the same time, a negative pressure degassing device is arranged in the storage tank, which can remove bubbles in the molten asphalt under negative pressure conditions to avoid broken wires during melt spinning; the magnetic control spinneret can select spinneret holes of different diameters or shapes according to actual needs, and can obtain special-shaped fibers while efficiently melt spinning. At the same time, the high-temperature magnetic field not only makes the spinneret temperature the same as the molten asphalt temperature, avoiding the temperature difference affecting the spinnability of the asphalt, but also the high-temperature magnetic field can induce the orientation of asphalt molecules, which helps to improve the mechanical properties and conductive properties of carbon fiber; the electrostatic device can make the extruded asphalt subject to a large stretching force before solidification, and instantly realize the fiber thinning. At the same time, high-speed stretching can help to improve the orderliness of the internal microstructure of the carbon fiber, reduce microscopic defects, and improve the mechanical properties and conductive properties of the obtained carbon fiber; a stress sensor is arranged in the melt-spinning drafting device, and the speed of the collection roller is regulated by stress output, which can effectively avoid the occurrence of broken wires.

[0038] The continuous spinning device of the asphalt-based carbon fiber of the present invention is suitable for preparing isotropic asphalt-based carbon fiber and mesophase asphalt-based carbon fiber.

[0039] The continuous spinning method of the asphalt-based carbon fiber of the present invention adopts a combined process of melt spinning and magnetic field plus electrostatic spinning to obtain asphalt carbon fiber with a diameter less than 1 μm, and can effectively reduce the number of internal defects of the fiber and improve the mechanical properties and conductive properties of the carbon fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained without creative work.

[0041] Figure 1 It is a schematic structural diagram of a continuous spinning device for pitch-based carbon fibers of the present invention;

[0042] In the figure, 1. gas storage tank, 2. material storage tank, 2-1. vacuum pump, 2-2. heating device, 3. magnetron spinning device, 4. electrostatic device, 4-1. electrostatic field generator, 5. melt-spinning drawing device, 5-1. collecting roller, 5-2. stress sensor, 5-3. motor, 6. control system, 7. back pressure valve, 8. valve, 9. control instrument. DETAILED DESCRIPTION

[0043] In order to have a deeper understanding of the present invention, the preferred embodiments of the present invention are described below to further illustrate the features and advantages of the present invention. Any changes or modifications that do not deviate from the spirit of the present invention can be understood by those skilled in the art. The scope of protection of the present invention is determined by the scope of the claims.

[0044] like Figure 1 As shown, the continuous spinning device of the present invention comprises a gas storage tank 1, a material storage tank 2, a magnetron spinning device 3, an electrostatic device 4, a melt-spinning drafting device 5 and a control system 6;

[0045] Among them, the gas storage tank 1 has its own switch for storing inert atmosphere; the material storage tank 2 is connected to the gas storage tank 1 through a pipeline provided with a back pressure valve 7, and the material storage tank 2 is provided with a vent valve, a negative pressure degassing device, a heating device 2-2 and a temperature sensor. The vent valve is used for venting, the negative pressure degassing device degasses the material in the material storage tank 2, the heating device 2-2 heats the material in the material storage tank 2, and the temperature sensor collects the temperature of the material in the material storage tank 2 and transmits it to the control system 6; the magnetron spinneret 3 includes a magnetic field generator and a spinneret, the spinneret is connected to the material storage tank 2 through a pipeline with a valve 8, and the transported material is ejected through a spinneret, and the magnetic field generator is fixed on the outer surface of the spinneret to generate a magnetic field; the electrostatic device 4 is between the spinneret of the magnetron spinneret 3 and the melt spinning drafting device 5 An electric field is formed between the receiving roller 5-1 of the melt-spinning drafting device 5; the receiving roller 5-1 of the melt-spinning drafting device 5 draws and reels the raw silk ejected from the spinneret, and collects the stress data of the raw silk on the receiving roller 5-1 through the stress sensor 5-2, and transmits it to the control system 6; the control system 6 is connected to the heating device 2-2, the temperature sensor, the magnetic field generator, the electrostatic device 4, the motor 5-3 of the melt-spinning drafting device 5 and the stress sensor 5-2. The control system 6 adjusts the heating temperature of the heating device 2-2 according to the temperature data collected by the temperature sensor, and adjusts the rotation speed of the receiving roller 5-1 by adjusting the motor 5-3 of the melt-spinning drafting device 5 according to the stress data collected by the stress sensor 5-2; and controls the switch and magnetic field strength of the magnetic field generator, as well as the switch and electrostatic strength of the electrostatic device 4.

[0046] In the above technical solution, the inert atmosphere is not particularly limited, and is preferably nitrogen, argon or helium.

[0047] In the above technical solution, the negative pressure defoaming device includes a negative pressure valve and a vacuum pump 2-1. The negative pressure valve is arranged on the upper surface of the storage tank 2, and the vacuum pump 2-1 is connected to the negative pressure valve through a pipeline; the heating device 2-2 is an electric heating sleeve, which is mounted outside the storage tank 2. After the electric heating sleeve is powered by an external power supply, it heats the storage tank 2. The storage tank 2 can realize high pressure and negative pressure bidirectional operation, that is, the pressure above the liquid surface of the molten asphalt is adjusted and kept stable by the back pressure valve 7, and the defoaming treatment of the molten asphalt is realized by vacuuming the negative pressure defoaming device. The air release valve is arranged on the upper surface of the storage tank 2, and the temperature sensor is fixed inside the storage tank 2.

[0048] In the above technical scheme, the spinneret includes a spinneret, a spinneret plate, a copper gasket and a distribution plate. The top of the spinneret is connected to the storage tank 2 through a pipe with a valve, and a through hole is provided at the bottom of the spinneret, on which a distribution plate, a copper gasket and a spinneret are fixed from top to bottom in sequence, and the copper gasket provides space capacity for molten asphalt; the number of spinneret holes on the spinneret is 1-100, and the diameter of the spinneret hole is 1-3 μm. When in use, spinnerets with different pore sizes and numbers of holes can be replaced according to demand, and spinnerets with special-shaped spinneret holes can be used. The diameter of the distribution hole on the distribution plate is preferably 1.5-2.5 mm; more preferably 2 mm, the distribution plate can ensure that the material is evenly distributed above the spinneret during melt spinning, and the distribution plate can be built-in with a groove to place a filter screen to remove solid impurities in the molten asphalt. The output power range of the magnetic field generator is 100-1000KW. The spinning pressure of the spinneret is 0.2-1.2MPa.

[0049] In the above technical solution, the electrostatic device 4 includes an electrostatic emitter 4-1 and an electrostatic controller; the positive plate and the negative plate of the electrostatic emitter 4-1 are respectively placed below the magnetron spinning device 3 and above the collection roller 5-1 of the melt spinning drafting device 5, and the control system 6 is connected to the electrostatic controller, and the control system controls the electrostatic emitter through the electrostatic controller 4-1. The electrostatic device 4 forms a high-voltage electric field between the spinneret and the collection roller 5-1, and the asphalt on the surface of the spinneret hole of the spinneret is quickly drawn under the action of the electrostatic force to form a thin diameter carbon fiber precursor, and the electric field voltage range is 1-3KV, and the current range is 10-50mA.

[0050] In the above technical solution, the melt spinning drafting device 5 can conveniently and flexibly adjust the size of the fiber drafting tension, effectively control the fiber diameter and avoid the phenomenon of broken wires. The speed of the wire collection roller 5-1 is controlled by the motor 5-3, and the speed is 300-500r / min.

[0051] In the above technical solution, the control system 6 can also be connected to both the back pressure valve 7 and the valve 8, and the control system 6 controls the switch of the back pressure valve 7 and the valve 8, which is more convenient for controlling the device. The control system and the heating device 2-2, the back pressure valve 7, the valve 8, the magnetron spinning device 3, the electrostatic device 4, the motor 5-3 of the melt spinning drafting device 5, the temperature sensor, and the stress sensor can be connected electrically or wirelessly. The control system 6 can be fixed outside the motor 5-3 of the melt spinning drafting device 5, and the fixed position can be changed according to needs.

[0052] In the above technical solution, the continuous spinning device of asphalt-based carbon fiber also includes a control instrument 9, which is connected to the control system 6, and the control system 6 is controlled by the control instrument 9.

[0053] The present invention can use a method for preparing asphalt-based carbon fibers using a continuous spinning device, and the steps are as follows:

[0054] Step 1: Place the spinnable asphalt in the storage tank 2, open the vent valve of the storage tank 2 and the switch of the gas tank 1, and adjust the pressure in the storage tank 2 through the back pressure valve 7. After the inner cavity of the storage tank 2 is purged with an inert atmosphere, close the vent valve of the storage tank 2 and the switch of the gas tank 1 and turn on the heating device 2-2, heat the storage tank 2 to a temperature higher than the softening point of the spinnable asphalt by 50-80°C and keep it warm for 1-3 hours;

[0055] Step 2, after turning on the negative pressure degassing device 2-1 to degas the material in the storage tank 2, turn on the switch of the gas storage tank 1, and adjust the pressure in the storage tank 2 through the back pressure valve 7 and keep it stable, so that the molten asphalt flows out from the spinneret hole of the spinneret, and at the same time turn on the magnetron spinneret 3, the electrostatic device 4 and the melt-spinning drafting device 5, set the temperature and power of the magnetron spinneret 3 and the voltage and current of the electrostatic device 4, and adjust the speed of the collection roller 5-1, keep the asphalt-based carbon fiber precursor perpendicular to the axial direction of the collection roller 5-1, and obtain the asphalt-based carbon fiber precursor on the collection roller 5-1;

[0056] Step 3. After spinning, the asphalt-based carbon fiber raw yarn is removed, first heated to 250-280°C at 1°C / min in an air atmosphere for 0.5-3h, and then heated to 800-1200°C at 5°C / min in an inert atmosphere for carbonization treatment for 0.5-2h to obtain asphalt-based carbon fiber.

[0057] In the above technical scheme, in step one and step two, the pressure in the storage tank 2 is adjusted to 0.1-5MPa by the back pressure valve 7; in step one, the heating rate of the heating device is 1-5°C / min; in step two, the power of the magnetron generator is 100-1000KW, more preferably 400KW; the voltage of the electrostatic device 4 is 1-3KV, and the current is 10-50mA.

[0058] The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified.

[0059] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with embodiments.

[0060] In the following examples, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, devices, instruments, equipment, etc. used in the following examples can be obtained from commercial sources.

[0061] Example 1

[0062] 2 kg of intermediate phase asphalt with a softening point of about 290 ° C is placed in the storage tank 2, the vent valve of the storage tank 2 and the switch of the gas tank 1 (storing argon) are opened, and the pressure in the storage tank 2 is adjusted to 0.1 MPa by the back pressure valve 7 for argon purge for 15 minutes, and then the vent valve of the storage tank 2 is closed and the heating device 2-2 is turned on, and the temperature is raised to 340 ° C at 5 ° C / min and kept warm for 1 hour, and the negative pressure valve and the vacuum pump 2-1 are opened to remove bubbles under negative pressure. The switch of the gas tank 1 is opened, and the pressure in the storage tank 2 is adjusted to 3 MPa by the back pressure valve 7, and the magnetron spinning device 3 is turned on, and the temperature is set to 340 ° C, and the magnetic field power is 100KW. The electrostatic device 4 is turned on and the voltage is set to 2KV, and the melt drawing device 5 (rotation speed 300r / min) is turned on at the same time to obtain evenly distributed asphalt-based carbon fiber precursor on the surface of the collection roller 5-1;

[0063] After spinning, the asphalt-based carbon fiber precursor was removed and placed in a tubular furnace for pre-oxidation treatment at 270°C at a rate of 1°C / min in an air atmosphere for 1 hour. Then, in an argon atmosphere, the temperature was raised to 1000°C at a rate of 5°C / min for high-temperature carbonization treatment for 0.5 hour. Finally, asphalt-based carbon fiber was obtained with a measured diameter of 9.8 μm, a tensile strength of 1.8 GPa, a tensile modulus of 200 GPa, and a thermal conductivity of 330 W / m·K.

[0064] Example 2

[0065] 2 kg of intermediate phase asphalt with a softening point of about 290 ° C is placed in the storage tank 2, the vent valve of the storage tank 2 and the switch of the gas tank 1 (storing argon) are opened, and the pressure in the storage tank 2 is adjusted to 1 MPa by the back pressure valve 7 for argon purge for 15 minutes, and then the vent valve of the storage tank 2 is closed and the heating device 2-2 is turned on, and the temperature is raised to 350 ° C at 5 ° C / min and kept warm for 1 hour, and the negative pressure valve and the vacuum pump 2-1 are opened to remove bubbles under negative pressure. The switch of the gas tank 1 is opened, and the pressure in the storage tank 2 is adjusted to 3 MPa by the back pressure valve 7, and the magnetron spinning device 3 is turned on, and the temperature is set to 350 ° C, and the magnetic field power is 400KW. The electrostatic device 4 is turned on and the voltage is set to 3KV, and the melt drawing device 5 (rotation speed 300r / min) is turned on at the same time to obtain evenly distributed asphalt-based carbon fiber precursor on the surface of the collection roller 5-1;

[0066] After spinning, the asphalt-based carbon fiber precursor was removed and placed in a tubular furnace in an air atmosphere at a temperature of 1°C / min to 270°C for pre-oxidation treatment for 1 hour. Then, in an argon atmosphere, the temperature was increased to 1000°C at a temperature of 5°C / min for high-temperature carbonization treatment for 0.5 hours. Finally, asphalt-based carbon fiber was obtained with a measured diameter of 8.5μm, a tensile strength of 2.0GPa, a tensile modulus of 240GPa, and a thermal conductivity of 350W / m·K.

[0067] Example 3

[0068] 2 kg of intermediate phase asphalt with a softening point of about 230 ° C is placed in the storage tank 2, the vent valve of the storage tank 2 and the switch of the gas tank 1 (storing argon) are opened, and the pressure in the storage tank 2 is adjusted to 0.1 MPa by the back pressure valve 7 for argon purge for 15 minutes, and then the vent valve of the storage tank 2 is closed and the heating device 2-2 is turned on, and the temperature is raised to 270 ° C at 5 ° C / min and kept warm for 1 hour, and the negative pressure valve and the vacuum pump 2-1 are opened to remove bubbles under negative pressure. The switch of the gas tank 1 is opened, and the pressure in the storage tank 2 is adjusted to 3 MPa by the back pressure valve 7, and the magnetron spinning device 3 is turned on, and the temperature is set to 270 ° C, and the magnetic field power is 600KW. The electrostatic device 4 is turned on and the voltage is set to 3KV, and the melt drawing device (rotation speed 400r / min) is turned on at the same time to obtain evenly distributed asphalt-based carbon fiber precursor on the surface of the collection roller;

[0069] After spinning, the asphalt-based carbon fiber precursor was removed and placed in a tubular furnace in an air atmosphere at a temperature of 1°C / min to 270°C for pre-oxidation treatment for 1 hour. Then, in an argon atmosphere, the temperature was increased to 1000°C at a temperature of 5°C / min for high-temperature carbonization treatment for 0.5 hours. Finally, asphalt-based carbon fiber was obtained with a measured diameter of 7.8μm, a tensile strength of 2.3GPa, a tensile modulus of 270GPa, and a thermal conductivity of 360W / m·K.

[0070] Example 4

[0071] 2 kg of intermediate phase asphalt with a softening point of about 230 ° C is placed in the storage tank 2, the vent valve of the storage tank 2 and the switch of the gas tank 1 (storing argon) are opened, and the pressure in the storage tank 2 is adjusted to 0.1 MPa by the back pressure valve 7 for argon purge for 15 minutes, and then the vent valve of the storage tank 2 is closed and the heating device 2-2 is turned on, and the temperature is raised to 270 ° C at 5 ° C / min and kept warm for 1 hour, and the negative pressure valve and the vacuum pump 2-1 are opened to remove bubbles under negative pressure. The switch of the gas tank 1 is opened, and the pressure in the storage tank 2 is adjusted to 3 MPa by the back pressure valve 7, and the magnetron spinning device 3 is turned on, and the temperature is set to 270 ° C, and the magnetic field power is 600KW. The electrostatic device 4 is turned on and the voltage is set to 1KV, and the melt drawing device (rotation speed 300r / min) is turned on at the same time to obtain evenly distributed asphalt-based carbon fiber precursor on the surface of the collection roller;

[0072] After spinning, the asphalt-based carbon fiber precursor was removed and placed in a tubular furnace in an air atmosphere, heated to 270°C at 1°C / min for pre-oxidation treatment for 1 hour, and then heated to 1000°C at 5°C / min in an argon atmosphere for high-temperature carbonization treatment for 0.5 hours. Finally, asphalt-based carbon fiber was obtained with a measured diameter of 14.8μm, a tensile strength of 1.8GPa, a tensile modulus of 180GPa, and a thermal conductivity of 300W / m·K.

[0073] Example 5

[0074] 2 kg of intermediate phase asphalt with a softening point of about 230 ° C is placed in the storage tank 2, the vent valve of the storage tank 2 and the switch of the gas tank 1 (storing argon) are opened, and the pressure in the storage tank 2 is adjusted to 0.1 MPa by the back pressure valve 7 for argon purge for 15 minutes, and then the vent valve of the storage tank 2 is closed and the heating device 2-2 is turned on, and the temperature is raised to 270 ° C at 5 ° C / min and kept warm for 1 hour, and the negative pressure valve and the vacuum pump 2-1 are opened to remove bubbles under negative pressure. The switch of the gas tank 1 is opened, and the pressure in the storage tank 2 is adjusted to 3 MPa by the back pressure valve 7, and the magnetron spinning device 3 is turned on, and the temperature is set to 270 ° C, and the magnetic field power is 600KW. The electrostatic device 4 is turned on and the voltage is set to 1KV, and the melt drawing device (rotation speed 500r / min) is turned on at the same time to obtain evenly distributed asphalt-based carbon fiber precursor on the surface of the collection roller;

[0075] After spinning, the asphalt-based carbon fiber precursor was removed and placed in a tubular furnace in an air atmosphere, heated to 270°C at 1°C / min for pre-oxidation treatment for 1 hour, and then heated to 1000°C at 5°C / min in an argon atmosphere for high-temperature carbonization treatment for 0.5 hours. Finally, asphalt-based carbon fiber was obtained with a measured diameter of 10.8μm, a tensile strength of 2.2GPa, a tensile modulus of 290GPa, and a thermal conductivity of 310W / m·K.

[0076] Example 6

[0077] 2 kg of intermediate phase asphalt with a softening point of about 230 ° C is placed in the storage tank 2, the vent valve of the storage tank 2 and the switch of the gas tank 1 (storing argon) are opened, and the pressure in the storage tank 2 is adjusted to 0.1 MPa by the back pressure valve 7 for argon purge for 15 minutes, and then the vent valve of the storage tank 2 is closed and the heating device 2-2 is turned on, and the temperature is raised to 270 ° C at 5 ° C / min and kept warm for 1 hour, and the negative pressure valve and the vacuum pump 2-1 are opened to remove bubbles under negative pressure. The switch of the gas tank 1 is opened, and the pressure in the storage tank 2 is adjusted to 3 MPa by the back pressure valve 7, and the magnetron spinning device 3 is turned on, and the temperature is set to 270 ° C, and the magnetic field power is 600KW. The electrostatic device 4 is turned on and the voltage is set to 3KV, and the melt drawing device (rotation speed 300r / min) is turned on at the same time to obtain evenly distributed asphalt-based carbon fiber precursor on the surface of the collection roller;

[0078] After spinning, the asphalt-based carbon fiber precursor was removed and placed in a tubular furnace in an air atmosphere, heated to 270°C at 1°C / min for pre-oxidation treatment for 1 hour, and then heated to 1000°C at 5°C / min in an argon atmosphere for high-temperature carbonization treatment for 0.5 hours. Finally, asphalt-based carbon fiber was obtained with a measured diameter of 10.2μm, a tensile strength of 2.1GPa, a tensile modulus of 305GPa, and a thermal conductivity of 340W / m·K.

[0079] Example 7

[0080] 2 kg of intermediate phase asphalt with a softening point of about 230 ° C is placed in the storage tank 2, the vent valve of the storage tank 2 and the switch of the gas tank 1 (storing argon) are opened, and the pressure in the storage tank 2 is adjusted to 0.1 MPa by the back pressure valve 7 for argon purge for 15 minutes, and then the vent valve of the storage tank 2 is closed and the heating device 2-2 is turned on, and the temperature is raised to 270 ° C at 5 ° C / min and kept warm for 1 hour, and the negative pressure valve and the vacuum pump 2-1 are opened to remove bubbles under negative pressure. The switch of the gas tank 1 is opened, and the pressure in the storage tank 2 is adjusted to 3 MPa by the back pressure valve 7, and the magnetron spinning device 3 is turned on, and the temperature is set to 270 ° C, and the magnetic field power is 600KW. The electrostatic device 4 is turned on and the voltage is set to 3KV, and the melt drawing device (rotation speed 500r / min) is turned on at the same time to obtain evenly distributed asphalt-based carbon fiber precursor on the surface of the collection roller;

[0081] After spinning, the asphalt-based carbon fiber precursor was removed and placed in a tubular furnace in an air atmosphere at a temperature of 1°C / min to 270°C for pre-oxidation treatment for 1 hour. Then, in an argon atmosphere, the temperature was increased to 1000°C at a temperature of 5°C / min for high-temperature carbonization treatment for 0.5 hours. Finally, asphalt-based carbon fiber was obtained with a measured diameter of 6.8μm, a tensile strength of 3.2GPa, a tensile modulus of 350GPa, and a thermal conductivity of 380W / m·K.

[0082] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A continuous spinning device, characterized in that: It comprises a gas storage tank (1), a material storage tank (2), a magnetron spinning device (3), an electrostatic device (4), a melt spinning and drawing device (5) and a control system (6); The gas storage tank (1) is used to store inert atmosphere; The material storage tank (2) is connected to the gas storage tank (1) through a pipeline provided with a back pressure valve (7). The material storage tank (2) is provided with a venting valve, a negative pressure degassing device, a heating device (2-2) and a temperature sensor. The venting valve is used for venting, the negative pressure degassing device degasses the material in the material storage tank (2), the heating device (2-2) heats the material in the material storage tank (2), and the temperature sensor collects the temperature of the material in the material storage tank (2) and transmits it to the control system (6); The magnetically controlled spinning device (3) comprises a magnetic field generator and a spinning device, the spinning device being connected to the material storage tank (2) via a pipeline with a valve (8) and ejecting the delivered material through a spinneret of the spinning device, and the magnetic field generator being fixed on the outer surface of the spinning device to generate a magnetic field; The electrostatic device (4) forms an electric field between the spinneret of the magnetron spinneret device (3) and the collection roller (5-1) of the melt-spinning drafting device (5); The receiving roller (5-1) of the melt-spinning drafting device (5) draws and reels the raw yarn ejected from the spinneret, and collects stress data of the raw yarn on the receiving roller (5-1) through a stress sensor (5-2), and transmits the data to a control system (6); The control system (6) is connected to the heating device (2-2), the temperature sensor, the magnetic field generator, the electrostatic device (4), the motor (5-3) of the melt-spinning drafting device (5), and the stress sensor (5-2). The control system (6) controls the heating temperature of the heating device (2-2) according to the temperature data collected by the temperature sensor, controls the rotation speed of the wire collection roller (5-1) by adjusting the motor (5-3) according to the stress data collected by the stress sensor (5-2), and controls the switch of the magnetic field generator and the magnetic field strength, as well as the switch and the electrostatic strength of the electrostatic device (4).

2. The continuous spinning device according to claim 1, characterized in that: The inert atmosphere is nitrogen, argon or helium; The control system (6) is connected to both the back pressure valve (7) and the valve (8), and the control system (6) controls the switching of the back pressure valve (7) and the valve (8).

3. The continuous spinning device according to claim 1, characterized in that: The negative pressure foam reduction device comprises a negative pressure valve and a vacuum pump (2-1), wherein the negative pressure valve is arranged on the upper surface of the material storage tank (2), and the vacuum pump (2-1) is connected to the negative pressure valve through a pipeline; The negative pressure valve and the vacuum pump (2-1) are both connected to a control system (6), and the control system (6) controls the switching of the negative pressure valve and the vacuum pump (2-1).

4. The continuous spinning device according to claim 1, characterized in that: The heating device (2-2) is an electric heating sleeve, which is sleeved on the outside of the material storage tank (2). The electric heating sleeve heats the material storage tank (2) after being powered by an external power source.

5. The continuous spinning device according to claim 1, characterized in that: The spinning device comprises a spinning pot, a spinning plate, a copper gasket and a distribution plate; The top of the spinning pot is connected to the material storage tank (2) through a pipeline with a valve (8), and the bottom of the spinning pot is provided with a through hole, on which a distribution plate, a copper gasket and a spinning plate are fixed in sequence from top to bottom; The number of spinneret holes of the spinneret plate is 1-100, and the diameter of the spinneret holes is 1-3 μm; The diameter of the distribution holes on the distribution plate is 1.5-2.5 mm; The spinning pressure of the spinning device is 0.2-1.2 MPa.

6. The continuous spinning device according to claim 1, characterized in that: The magnetic field generator generates a magnetic field with a temperature 50-80°C higher than the softening point of the material; The output power of the magnetic field generator ranges from 100 to 1000 KW.

7. The continuous spinning device according to claim 1, characterized in that: The electrostatic device (4) comprises an electrostatic emitter (4-1) and an electrostatic controller; the positive plate and the negative plate of the electrostatic emitter (4-1) are respectively placed below the magnetron spinning device (3) and above the wire collection roller (5-1) of the melt spinning drafting device (5); the control system (6) is connected to the electrostatic controller, and the control system (6) controls the electrostatic emitter (4-1) through the electrostatic controller; The electric field voltage range is 1-3KV; The rotation speed of the wire collecting roller (5-1) is 300-500r / min.

8. The continuous spinning device according to claim 1, characterized in that: The control system (6) is fixed outside the motor (5-3) of the melt-spinning drafting device (5); The continuous spinning device further comprises a control instrument (9), which is connected to the control system (6) and controls the control system (6) via the control instrument (9).

9. A method for preparing pitch-based carbon fibers using the continuous spinning device according to any one of claims 1 to 8, characterized in that: Here are the steps: Step 1: Place the spinnable asphalt in a storage tank (2), open the air release valve of the storage tank (2) and the switch of the gas storage tank (1), and adjust the pressure in the storage tank (2) through the back pressure valve (7). After purging the inner cavity of the storage tank (2) with an inert atmosphere, close the air release valve of the storage tank (2) and the switch of the gas storage tank (1) and turn on the heating device (2-2), heat the storage tank (2) to a temperature higher than the softening point of the spinnable asphalt by 50-80°C and keep it warm for 1-3 hours; Step 2: After turning on the negative pressure degassing device to degas the material in the storage tank (2), turn on the switch of the gas storage tank (1), and adjust the pressure in the storage tank (2) through the back pressure valve (7) and keep it stable, so that the molten asphalt flows out from the spinneret holes of the spinneret of the spinneret device, and at the same time turn on the magnetron spinneret device (3), the electrostatic device (4) and the melt spinning drafting device (5), set the temperature and power of the magnetron spinneret device (3) and the voltage and current of the electrostatic device (4), adjust the rotation speed of the collection roller (5-1), keep the asphalt-based carbon fiber precursor perpendicular to the axial direction of the collection roller (5-1), and obtain the asphalt-based carbon fiber precursor on the collection roller (5-1); Step 3. After spinning, the asphalt-based carbon fiber raw yarn is removed, first heated to 250-280°C at 1°C / min in an air atmosphere for 0.5-3h, and then heated to 800-1200°C at 5°C / min in an inert atmosphere for carbonization treatment for 0.5-2h to obtain asphalt-based carbon fiber.

10. The method for preparing pitch-based carbon fiber according to claim 9, characterized in that: In step 1 and step 2, the pressure in the storage tank (2) is adjusted to 0.1-5 MPa respectively by the back pressure valve (7); In step 1, the heating speed of the heating device is 1-5°C / min.

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