Nanofiber yarn coated carbon fiber bundle composite filament and preparation method thereof

Abstract

The invention relates to the technical field of carbon fiber composite materials, and discloses a nanofiber yarn coated carbon fiber bundle composite filament which comprises a carbon fiber bundle and nanofiber yarn, and the nanofiber yarn is coated on the outer surface of the carbon fiber bundle; the carbon fiber bundle is a high-modulus carbon fiber bundle, and the nanofiber yarn is prepared from a polymer material through a conjugate electrostatic spinning method. A layer of compact and uniformly-distributed nanofiber yarn is introduced to the surface of the high-modulus carbon fiber bundle by using a conjugate electrostatic spinning technology to obtain the nanofiber yarn coated carbon fiber bundle composite filament, and the composite filament has good wear resistance and toughness, and the processability is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber composite materials, and in particular to a nanofiber yarn-coated carbon fiber bundle composite filament and a preparation method thereof. Background Art

[0002] High modulus carbon fiber (HMCF) has a specific modulus 5-7 times greater than that of aluminum alloy, and a smaller mass density than metal materials. Its reinforced composite materials can achieve zero expansion in a temperature alternating environment, and have lightweight, high stiffness and dimensional stability. Therefore, it is widely used in aerospace vehicles, deep space exploration and other fields. However, the current production process of HMCF includes a 3000℃ high-temperature graphitization process, so HMCF has a tighter arrangement of graphite crystal layers parallel to the fiber axis, and its surface structure is closer to a three-dimensional ordered graphite structure, making its surface extremely inert and hairy, resulting in poor fiber weaving performance and easy breakage during processing. Therefore, how to improve the weaving performance of high modulus carbon fiber is an urgent problem to be solved. Summary of the invention

[0003] In view of this, the present invention provides a nanofiber yarn-coated carbon fiber bundle composite filament and a preparation method thereof, in order to solve the problem that high modulus carbon fiber has poor weaving performance and is easy to break during processing.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] In one aspect, the present invention provides a nanofiber yarn-coated carbon fiber bundle composite filament, comprising a carbon fiber bundle and a nanofiber yarn, wherein the nanofiber yarn is coated on the outer surface of the carbon fiber bundle;

[0006] The carbon fiber bundle is a high modulus carbon fiber bundle, and the nanofiber yarn is prepared from a polymer material by a conjugated electrostatic spinning method.

[0007] Preferably, the carbon fiber bundle consists of 1000-36000 high modulus carbon fiber filaments, and the diameter of a single high modulus carbon fiber filament is 5-7 μm.

[0008] Preferably, the carbon content of the high modulus carbon fiber is ≥99%, the tensile strength is ≥3200MPa, the tensile modulus is ≥350GPa, and the bulk density is 1.81-1.83g / cm 3 .

[0009] Preferably, the coating thickness of the nanofiber yarn is 10-30 μm.

[0010] Preferably, the average diameter of the nanofiber yarn is 50-800 nm.

[0011] Preferably, the polymer material includes one or more of silk fibroin, polyvinylidene fluoride, polyimide, nanocellulose, aramid, and aramid sulfone.

[0012] On the other hand, the present invention provides a method for preparing a nanofiber yarn-coated carbon fiber bundle composite filament, comprising the following steps:

[0013] (1) mixing a polymer material with an organic solvent to obtain an electrospinning solution;

[0014] (2) The carbon fiber bundle is fixed on a spinning turntable of an electrospinning machine, and then the electrospinning solution is sprayed onto the surface of the carbon fiber bundle to form nanofiber yarn, thereby obtaining a carbon fiber bundle composite filament coated with nanofiber yarn.

[0015] Preferably, the mass percentage concentration of the electrospinning solution is 5-20%.

[0016] Preferably, the organic solvent includes one or more of N,N-dimethylformamide, dichloromethane, formic acid, tetrahydrofuran and methyl pyrrolidone.

[0017] Preferably, the moving speed of the carbon fiber bundle is 2-10 mm / s.

[0018] Preferably, the distance between the spinning needle of the electrospinning machine and the collecting turntable is 6-10 cm.

[0019] Preferably, the rotation speed of the wire collecting turntable is 200-1000 rpm.

[0020] Preferably, the propulsion speed of the electrospinning solution is 0.2-3 mL / h.

[0021] Preferably, the distance between the positive electrode spinning needle and the negative electrode spinning needle of the electrospinning machine is 9-15 cm.

[0022] Preferably, the electrospinning solutions sprayed out by the positive electrode spinning needle and the negative electrode spinning needle of the electrospinning machine are the same or different.

[0023] Preferably, the positive electrode voltage of the electrospinning machine is 4-20 kV, and the negative electrode voltage is -4 to -20 kV.

[0024] The present invention provides a nanofiber yarn-coated carbon fiber bundle composite wire material and a preparation method thereof. Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention utilizes conjugated electrospinning technology to introduce a layer of dense and evenly distributed nanofiber yarn on the surface of a high modulus carbon fiber bundle, thereby obtaining a carbon fiber bundle composite filament coated with nanofiber yarn. The composite filament has good wear resistance and toughness, thereby improving its weaving performance and greatly improving its processability. In addition, a large number of gaps exist on the surface of the carbon fiber bundle composite filament coated with nanofiber yarn of the present invention, which can effectively improve the permeability, and the nanofiber yarn can play a certain supporting role and buffer the stress conduction, which is beneficial to the strengthening of the interface of the composite filament. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0027] Figure 1 Schematic diagram of the electrospinning process of the present invention;

[0028] Figure 2 This is a scanning electron microscope image of the surface of the carbon fiber bundle composite wire material coated with nanofiber yarn prepared in Example 1;

[0029] Figure 3 This is a scanning electron microscope image of a cross section of a carbon fiber bundle composite wire material coated with nanofiber yarn prepared in Example 1;

[0030] Figure 4 2 are scanning electron microscope images of the cross section (right image) and longitudinal section (left image) of the second sample to be tested;

[0031] Figure 5 This is a test diagram of the nanofiber yarn-coated carbon fiber bundle composite filament prepared in Example 8 and the carbon fiber bundle knotting test diagram of Comparative Example 1. DETAILED DESCRIPTION

[0032] The present invention will be described below by specific examples, and it will be appreciated by those skilled in the art that the following specific examples are only for illustrative purposes, and do not limit the scope of the present invention in any way. In addition, in the following examples, unless otherwise specified, the reagents and equipment used are all commercially available. If in the following examples, specific treatment conditions and treatment methods are not clearly described, then conditions and methods known in the art can be used to process.

[0033] In one aspect of the present invention, the present invention proposes a nanofiber yarn-coated carbon fiber bundle composite filament, comprising a carbon fiber bundle and nanofiber yarn, wherein the nanofiber yarn is coated on the outer surface of the carbon fiber bundle; the carbon fiber bundle is a high modulus carbon fiber bundle, and the nanofiber yarn is prepared from a polymer material by a conjugated electrospinning method.

[0034] In some embodiments of the present invention, the carbon fiber bundle is composed of 1000-36000 high modulus carbon fiber filaments, that is, the specification of the carbon fiber bundle is 1-36K, for example, it can be 1K, 5K, 10K, 15K, 20K, 25K, 30K, 36K, etc.; the diameter of a single high modulus carbon fiber filament is 5-7μm, for example, it can be 5μm, 5.5μm, 6μm, 6.5μm, 7μm, etc.

[0035] In some embodiments of the present invention, the high modulus carbon fiber has a carbon content of ≥99%, a tensile strength of ≥3200 MPa, a tensile modulus of ≥350 GPa, and a bulk density of 1.81-1.83 g / cm 3 Specifically, the high modulus carbon fiber may be, for example, polyacrylonitrile-based carbon fiber, and more specifically, may be BHM3 carbon fiber.

[0036] In some embodiments of the present invention, the coating thickness of the nanofiber yarn is 10-30 μm, for example, it can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.; the average diameter of the nanofiber yarn is 50-800 nm, for example, it can be 50 nm, 100 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, etc.

[0037] In some embodiments of the present invention, the polymer material includes one or more of silk fibroin, polyvinylidene fluoride, polyimide, nanocellulose, aramid, and aramid sulfone.

[0038] In another aspect of the present invention, the present invention provides a method for preparing a nanofiber yarn-coated carbon fiber bundle composite wire, comprising the following steps:

[0039] (1) mixing a polymer material with an organic solvent to obtain an electrospinning solution;

[0040] (2) The carbon fiber bundle is fixed on a spinning turntable of an electrospinning machine, and then the electrospinning solution is sprayed onto the surface of the carbon fiber bundle to form nanofiber yarn, thereby obtaining a carbon fiber bundle composite filament coated with nanofiber yarn.

[0041] In the present invention, the polymer material is firstly mixed with an organic solvent to obtain an electrospinning solution.

[0042] In some embodiments of the present invention, the mass percentage concentration of the electrospinning solution is 5-20%, for example, it can be 5%, 8%, 10%, 12%, 15%, 18%, 20%, etc. Specifically, the diameter of the nanofiber yarn can be adjusted by changing the concentration of the electrospinning solution. The organic solvent includes one or more of N,N-dimethylformamide, dichloromethane, formic acid, tetrahydrofuran, and methyl pyrrolidone.

[0043] In the present invention, the carbon fiber bundle is fixed on the spinning turntable of the electrospinning machine, and then the electrospinning solution is sprayed onto the surface of the carbon fiber bundle to form nanofiber yarn, thereby obtaining a carbon fiber bundle composite filament coated with nanofiber yarn.

[0044] In some embodiments of the present invention, the moving speed of the carbon fiber bundle is adjusted by controlling the rotation speed of the winding turntable so that the moving speed of the carbon fiber bundle is 2-10 mm / s, for example, 2 mm / s, 5 mm / s, 8 mm / s, 10 mm / s, etc.

[0045] In some embodiments of the present invention, the electrospinning solution is injected into the spinning needle of the electrospinning machine, and the electrospinning solution is sprayed onto the surface of the carbon fiber bundle through the spinning needle to form the nanofiber yarn.

[0046] In some embodiments of the present invention, the coating thickness of the nanofiber yarn is 10-30 μm, and there is no special limitation on the thickness of the nanofiber yarn, which can be adjusted according to actual conditions. However, it should be noted that as the coating thickness of the nanofiber yarn increases, the tensile strength of the composite wire material will be significantly improved, and if the coating thickness of the nanofiber yarn is too large, the interlayer shear strength of the composite wire material will decrease slightly, because the excessively thick nanofiber yarn will affect the penetration of the resin, thereby causing the interlayer shear strength to decrease.

[0047] In some embodiments of the present invention, the average diameter of the nanofiber yarn is 50-800nm, for example, it can be 50nm, 100nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, etc. The average diameter of the nanofiber yarn is mainly related to the voltage, the propulsion speed of the electrospinning solution, and the type of electrospinning solution. There are certain differences in the average diameter of the nanofiber yarn under different parameters. For example, when the voltage is 6kV and the propulsion speed of the electrospinning solution is 0.5mL / h, when the positive and negative electrodes are both 8% silk fibroin electrospinning solution, the average diameter of the nanofiber yarn is 160nm, when the positive electrode is 8% silk fibroin electrospinning solution and the negative electrode is 10% polyvinylidene fluoride electrospinning solution, the average diameter of the nanofiber yarn is 710nm, and when the positive and negative electrodes are both 10% silk fibroin electrospinning solution, the average diameter of the nanofiber yarn is 175nm.

[0048] In some embodiments of the present invention, the electrospinning solutions injected into the positive electrode spinning needle and the negative electrode spinning needle of the electrospinning machine may be the same or different, and there is no special limitation on this, and it can be adjusted according to the actual situation. For example, both the positive electrode spinning needle and the negative electrode spinning needle are injected with silk fibroin electrospinning solution or polyvinylidene fluoride electrospinning solution or polyimide spinning solution or nanocellulose electrospinning solution or aramid electrospinning solution or aromatic sulfone electrospinning solution; or the positive electrode spinning needle is injected with silk fibroin spinning solution, and the negative electrode spinning needle is injected with polyvinylidene fluoride electrospinning solution or polyimide spinning solution or nanocellulose electrospinning solution or aramid electrospinning solution or aromatic sulfone electrospinning solution.

[0049] In some embodiments of the present invention, the positive electrode voltage of the electrospinning machine is 4-20 kV, for example, it can be 4kV, 6kV, 8kV, 10kV, 12kV, 15kV, 18kV, 20kV, etc., and the negative electrode voltage is -4 to -20 kV, for example, it can be -4kV, -6kV, -8kV, -10kV, -12kV, -15kV, -18kV, -20kV, etc.

[0050] In some embodiments of the present invention, the propulsion speed of the electrospinning liquid in the spinning needle is 0.2-3 mL / h, for example, it can be 0.2 mL / h, 0.5 mL / h, 1 mL / h, 1.5 mL / h, 2 mL / h, 2.5 mL / h, 3 mL / h, etc.

[0051] In some embodiments of the present invention, the distance between the positive electrode spinning needle and the negative electrode spinning needle of the electrospinning machine is 9-15 cm, for example, 9 cm, 12 cm, or 15 cm.

[0052] In some embodiments of the present invention, the distance between the spinning needle of the electrospinning machine and the collecting turntable is 6-10 cm, for example, it can be 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, etc., specifically refers to the distance from the end of the spinning needle close to the collecting turntable to the collecting turntable, and the rotation speed of the spinning needle of the electrospinning machine and the collecting turntable is 200-1000 rpm, for example, it can be 200 rpm, 400 rpm, 600 rpm, 800 rpm, 1000 rpm, etc.

[0053] like Figure 1As shown, it is a schematic diagram of the electrospinning process of the present invention, the carbon fiber bundle is fixed on the receiving turntable of the electrospinning machine, and the two spinning needles are both facing the direction of the receiving turntable, so that the ejection direction of the electrospinning liquid forms an acute angle with the carbon fiber bundle, and the electrospinning liquid ejected from the spinning needle is curled and formed on the surface of the carbon fiber bundle through the high-speed rotation of the receiving turntable, and a stable nanofiber cone surface is formed at the receiving part of the carbon fiber bundle. The receiving turntable is rotated at a high speed for stretching, so that the electrospinning liquid is evenly coated on the surface of the carbon fiber bundle to form a carbon fiber bundle composite filament coated with nanofiber yarn.

[0054] The technical solutions in the present invention will be described clearly and completely below in conjunction with specific embodiments. The embodiments of the present application are only used as examples, and all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0055] The electrospinning machine used in the following examples is a classic spinning machine produced by Changsha Nayi Instrument Technology Co., Ltd.

[0056] Example 1

[0057] This embodiment provides a method for preparing a nanofiber yarn-coated carbon fiber bundle composite wire material, and the specific steps are as follows:

[0058] (1) Dissolving silk fibroin in formic acid to obtain a silk fibroin electrospinning solution with a mass percent concentration of 8%.

[0059] (2) The carbon fiber bundle was fixed on the spinning turntable of the electrospinning machine, and the rotation speed of the spinning turntable was adjusted so that the moving speed of the carbon fiber bundle was 2 mm / min.

[0060] The carbon fiber bundle is 3K polyacrylonitrile-based carbon fiber BHM3, the diameter of a single carbon fiber filament is 7 μm, the carbon content of the carbon fiber filament is 99%, the tensile strength is 3200 MPa, the tensile modulus is 400 GPa, and the bulk density is 1.82 g / cm 3 .

[0061] (3) 8% silk fibroin electrospinning solution was injected into the positive spinning needle and the negative spinning needle of the electrospinning machine, and the electrospinning solution was sprayed from the spinning needle to the surface of the carbon fiber bundle to form nanofiber yarn, thereby obtaining a carbon fiber bundle composite filament coated with nanofiber yarn (hereinafter referred to as "composite filament").

[0062] Among them, the positive electrode voltage of the electrospinning machine is 6kV, the negative electrode voltage is -6kV, the propulsion speed of the electrospinning liquid is 0.5mL / h, the distance between the positive spinning needle and the negative spinning needle is 12cm, the distance between the spinning needle and the winding turntable is 8cm, the rotation speed of the winding turntable is 800rpm, the average diameter of the nanofiber yarn is 160nm, and the coating thickness of the nanofiber yarn is 30μm.

[0063] like Figures 2 to 3 Shown are scanning electron microscope images of the surface of the carbon fiber bundle composite wire coated with nanofiber yarn prepared in this example and the cross-section of the carbon fiber bundle composite wire.

[0064] from Figure 2 It can be seen that the surface of the carbon fiber bundle composite wire has reached the nanometer level, showing extremely high fineness and uniformity. During the winding process of the nanofiber yarn, the nanofiber yarn shows a certain orientation, which can not only enhance the mechanical properties of the composite wire, but also effectively improve its weaving performance.

[0065] from Figure 3 It can be seen that the nanofiber yarn fits tightly to the outer layer of the carbon fiber bundle. This tight combination significantly enhances the bundling of the carbon fiber, making the overall structure more stable and strong. At the same time, the existence of the nanofiber yarn can be intuitively presented. It is evenly distributed and tightly arranged, which can effectively improve the mechanical properties and weaving properties of the composite bundle.

[0066] Embodiment 2-9

[0067] Examples 2-9 are basically the same as Example 1, and the only difference is the type of electrospinning solution in the positive and negative electrode spinning needles and some electrospinning parameters, see Table 1 for details. The polyvinylidene fluoride electrospinning solution is obtained by dissolving polyvinylidene fluoride in N,N-dimethylformamide.

[0068] Table 1

[0069]

[0070] Comparative Example 1

[0071] This comparative example is a carbon fiber bundle that is not coated with nanofiber yarn, namely 3K polyacrylonitrile-based carbon fiber BHM3, with a carbon content of ≥99%, a tensile strength of 3200 MPa, a tensile modulus of 400 GPa, and a bulk density of 1.82 g / cm 3 .

[0072] The present invention measured the interlaminar shear strength, bending strength, impact strength, hook strength, tensile strength, and tensile strength of the composite wires prepared in Examples 1-9 and the carbon fiber bundle in Comparative Example 1. The results are shown in Table 2.

[0073] (1) Testing method of hook strength and first tensile strength: The composite wire materials of Examples 1 to 9 and the carbon fiber bundle of Comparative Example 1 were used as the first samples to be tested.

[0074] The first sample to be tested is tested using a universal tensile testing machine. The test standard for hook strength refers to GJB 1982-94, the test standard for the first tensile strength refers to GB / T 3362 (2005), and the first tensile strength test is performed on a sample with a length of 200 mm.

[0075] (2) Test method for interlaminar shear strength and second tensile strength: The same amount of bisphenol A epoxy resin 6101 was coated on the surface of the composite wire materials of Examples 1-9 and the carbon fiber bundle of Comparative Example 1, respectively, and cured at 80°C for 2 hours using a curing agent, triethylenetetramine, to obtain a second test sample, wherein the volume ratio of the composite wire material / carbon fiber to the bisphenol A epoxy resin 6101 was 6:4, and the mass ratio of the bisphenol A epoxy resin 6101 to the curing agent was 10:1.

[0076] The second sample to be tested is tested using a universal tensile testing machine. The test standard for interlaminar shear strength refers to JC / T773-82, the test standard for the second tensile strength refers to GB / T 3362 (2005), and the second tensile strength test is performed on a sample with a length of 150 mm.

[0077] Table 2

[0078]

[0079]

[0080] As shown in Table 2, compared with the carbon fiber bundle not coated with nanofiber yarn, the hook strength of the carbon fiber bundle composite wire coated with nanofiber yarn of the present invention can be increased by up to 228.77%. This is because when the composite wire is subjected to lateral force, the nanofiber yarn plays a buffering role, which can significantly improve the bending resistance of the carbon fiber bundle, thereby improving its folding resistance and wear resistance during the process of being processed into fabric. The tensile strength does not change much because the wire tension during the electrospinning process may cause damage to the carbon fiber filaments in the carbon fiber bundle.

[0081] like Figure 4The figure shows the scanning electron microscope images of the cross section (left) and longitudinal section (right) of the second sample to be tested. It can be seen from the figure that the second sample to be tested presents a clear layered structure. Specifically, the second sample to be tested is composed of a resin layer, nanofiber yarn and carbon fiber bundle from the outside to the inside, wherein the nanofiber yarn plays an important transitional role between the resin layer and the carbon fiber bundle. This transition not only effectively alleviates the interfacial stress between different materials, but also further enhances the overall performance and durability of the composite material (the second sample to be tested), so that the composite material has excellent mechanical properties and weaving properties while maintaining light weight.

[0082] In addition, the present invention also tests the processing flexibility of the composite wire material of Example 8 and the carbon fiber bundle of Comparative Example 1, and performs knotting tests on the two respectively. Figure 5 As shown, the carbon fiber bundle of comparative example 1 is broken after knotting, while the composite wire of example 8 is intact. This indicates that the carbon fiber bundle composite wire coated with nanofiber yarn of the present invention has good weaving performance and good processing flexibility.

[0083] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A nanofiber yarn-coated carbon fiber bundle composite wire material, characterized in that: It comprises a carbon fiber bundle and a nanofiber yarn, wherein the nanofiber yarn is coated on the outer surface of the carbon fiber bundle; The carbon fiber bundle is a high modulus carbon fiber bundle, and the nanofiber yarn is prepared from a polymer material through a conjugated electrostatic spinning method.

2. The nanofiber yarn-coated carbon fiber bundle composite filament according to claim 1, characterized in that: The carbon fiber bundle is composed of 1000-36000 high modulus carbon fiber filaments, and the diameter of a single high modulus carbon fiber filament is 5-7 μm; The high modulus carbon fiber has a carbon content of ≥99%, a tensile strength of ≥3200 MPa, a tensile modulus of ≥350 GPa, and a bulk density of 1.81-1.83 g / cm 3 .

3. The nanofiber yarn-coated carbon fiber bundle composite filament according to claim 1, characterized in that: The coating thickness of the nanofiber yarn is 10-30 μm, and the average diameter of the nanofiber yarn is 50-800 nm.

4. The nanofiber yarn-coated carbon fiber bundle composite filament according to any one of claims 1 to 3, characterized in that: The polymer material includes one or more of silk fibroin, polyvinylidene fluoride, polyimide, nanocellulose, aramid, and aramid sulfone.

5. A method for preparing the nanofiber yarn-coated carbon fiber bundle composite filament according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) mixing a polymer material with an organic solvent to obtain an electrospinning solution; (2) The carbon fiber bundle is fixed on a spinning turntable of an electrospinning machine, and then the electrospinning solution is sprayed onto the surface of the carbon fiber bundle to form nanofiber yarn, thereby obtaining a carbon fiber bundle composite filament coated with nanofiber yarn.

6. The method for preparing the nanofiber yarn-coated carbon fiber bundle composite wire material according to claim 5, characterized in that: The mass percentage concentration of the electrospinning solution is 5-20%; The organic solvent includes one or more of N,N-dimethylformamide, dichloromethane, formic acid, tetrahydrofuran and methyl pyrrolidone.

7. The method for preparing the nanofiber yarn-coated carbon fiber bundle composite filament according to claim 5, characterized in that: The moving speed of the carbon fiber bundle is 2-10 mm / s.

8. The method for preparing the nanofiber yarn-coated carbon fiber bundle composite wire material according to claim 5, characterized in that: The distance between the spinning needle of the electrospinning machine and the collecting turntable is 6-10 cm, and the rotation speed of the collecting turntable is 200-1000 rpm; The propulsion speed of the electrospinning solution is 0.2-3 mL / h.

9. The method for preparing the nanofiber yarn-coated carbon fiber bundle composite filament according to claim 5, characterized in that: The distance between the positive electrode spinning needle and the negative electrode spinning needle of the electrospinning machine is 9-15 cm; The electrospinning solutions sprayed out by the positive electrode spinning needle and the negative electrode spinning needle of the electrospinning machine are the same or different.

10. The method for preparing the nanofiber yarn-coated carbon fiber bundle composite filament according to any one of claims 5 to 9, characterized in that: The positive electrode voltage of the electrospinning machine is 4-20 kV, and the negative electrode voltage is -4 to -20 kV.

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