Preparation method of PEEK conductive monofilament

Abstract

The invention relates to the technical field of monofilament preparation, and particularly discloses a preparation method of a PEEK conductive monofilament. The preparation method of the PEEK conductive monofilament provided by the invention comprises the following steps: dispersing aminated carbon fibers in a mixed aqueous solution containing polyvinyl alcohol and 3, 4-ethylenedioxythiophene to prepare a dispersion liquid; then adding an initiator to carry out a prepolymerization reaction to obtain a PEDOT / PVA coated carbon fiber prepolymer; and blending the PEDOT / PVA coated carbon fiber prepolymer with the molten PEEK, extruding by a spinning die head, drafting, and sizing to obtain the PEEK conductive monofilament.

Description

Technical Field

[0001] The present invention relates to the technical field of monofilament preparation, and in particular to a method for preparing a PEEK conductive monofilament. Background Art

[0002] Polyetheretherketone (PEEK) resin boasts high heat resistance, radiation resistance, high impact strength, excellent wear and fatigue resistance, flame retardancy, and superior electrical properties. It is currently widely used in aerospace, automotive, electronics, chemical, machinery, and medical fields. PEEK fibers or monofilaments made from PEEK are also used in applications such as conveyor belts in the paper industry, fuel filter screens for aircraft and automobiles, composite materials, high-performance ropes, woven mesh, and medical devices.

[0003] Polyetheretherketone is also a high insulation material with a surface resistivity of 10 14 -10 16 Ω, which makes it difficult to eliminate the electrostatic charge accumulated on the surface of the material, and will form an electrostatic high voltage of up to tens of thousands of volts. When polyetheretherketone is used to package electronic devices or electrical products, it needs to be conductive, otherwise the static electricity on its surface will damage the related electronic products. Traditional PEEK conductive materials mostly rely on the direct blending of high-proportion conductive fillers (such as carbon nanotubes and metal particles), which will lead to deterioration of the material's processing performance and increase in processing costs. Although there are reports of improving dispersibility by adding liquid metal, it still faces problems such as poor interfacial compatibility and high percolation threshold. Carbon fiber surface modification technology has defects such as high energy consumption and difficulty in scalability.

[0004] Based on the above situation, the purpose of the present invention is to provide a method for preparing PEEK conductive monofilaments to improve the performance of PEEK conductive monofilaments. Summary of the Invention

[0005] The main technical problem solved by the present invention is to provide a method for preparing a PEEK conductive monofilament, and also provides a PEEK conductive monofilament.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing PEEK conductive monofilament, comprising the steps of:

[0007] (1) adding polyvinyl alcohol (PVA) and 3,4-ethylenedioxythiophene (EDOT) into water to prepare a mixed aqueous solution, and dispersing the amino-treated carbon fibers in the mixed aqueous solution to prepare a dispersion;

[0008] Adding FeCl3 initiator to the dispersion to carry out a prepolymerization reaction to obtain a PEDOT / PVA coated carbon fiber prepolymer;

[0009] (2) The PEDOT / PVA coated carbon fiber prepolymer obtained in step (1) is blended with molten PEEK, and then extruded through a spinning die and stretched, and then shaped to obtain PEEK conductive monofilaments.

[0010] As one embodiment of the present invention, the mass percentage concentration of the aminated carbon fibers in the dispersion is 5 to 15%. Specifically, the mass percentage concentration of the aminated carbon fibers in the dispersion can be 5%, 8%, 10%, 12%, 15%, or any other value within the range of 5% to 15%.

[0011] As an embodiment of the present invention, the mass percentage concentration of polyvinyl alcohol in the dispersion is 5% to 10%. Specifically, the mass percentage concentration of polyvinyl alcohol in the dispersion can be 5%, 6%, 7%, 8%, 9%, 10%, or any other value within the range of 5% to 10%.

[0012] As one embodiment of the present invention, the mass percentage concentration of 3,4-ethylenedioxythiophene in the dispersion is 15% to 25%. Specifically, the mass percentage concentration of 3,4-ethylenedioxythiophene in the dispersion can be 15%, 16%, 18%, 20%, 24%, 25%, or any other value within the range of 15% to 25%.

[0013] As an embodiment of the present invention, the amount of FeCl3 initiator added to the dispersion is: the molar ratio of FeCl3 initiator to the amination carbon fiber contained in the dispersion is 1:(30-50).

[0014] As an embodiment of the present invention, the blending is carried out in a twin-screw extruder, and the twin-screw extruder includes three temperature gradient zones: zone 1, zone 2, and zone 3, wherein the temperature range of zone 1 is 320-340°C, the temperature range of zone 2 is 360-380°C, and the temperature range of zone 3 is 360-380°C.

[0015] As one embodiment of the present invention, an FeCl3 initiator is added to the materials in the twin-screw extruder at the end of the second zone or at the front end of the third zone. Adding the FeCl3 initiator to the dispersion allows for initial polymerization of EDOT on the surface of the amination-treated carbon fibers. Further FeCl3 initiator addition is selectively performed in the high-temperature zones of the second and third zones to ensure sufficient diffusion and reaction of the initiator, promoting PEDOT chain extension and crosslinking, forming a dense conductive layer, and avoiding incomplete polymerization. Adding the initiator twice improves polymerization uniformity and reduces the resistivity of the resulting PEEK conductive monofilament.

[0016] As one embodiment of the present invention, the molar ratio of the FeCl3 initiator added to the twin-screw extruder to the FeCl3 initiator added to the dispersion is (1-3):(1-12). Preferably, the molar ratio of the FeCl3 initiator added to the twin-screw extruder to the FeCl3 initiator added to the dispersion is 1:(3-5).

[0017] As an embodiment of the present invention, the PEDOT / PVA coated carbon fiber prepolymer prepared in step (1) is blended with molten PEEK in a mass ratio of 1:(2-9). Specifically, the PEDOT / PVA coated carbon fiber prepolymer and molten PEEK can be blended in a mass ratio of 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or any other value within the range of 1:(2-9).

[0018] As an embodiment of the present invention, when preparing the dispersion, the amino carbon fibers are dispersed in the mixed aqueous solution by ultrasonic dispersion method, and the ultrasonic dispersion is carried out for 30 to 60 minutes.

[0019] As an embodiment of the present invention, the amination carbon fiber is a chopped carbon fiber after amination treatment, the length of the chopped carbon fiber is 150 to 250 μm, and the surface amino density of the amination carbon fiber is ≥3.2×10 14 The use of amino-treated carbon fibers can enhance interfacial properties through chemical coupling and improve the bending resistance of the monofilament.

[0020] As an embodiment of the present invention, the preparation steps of the amination carbon fiber include:

[0021] The chopped carbon fibers are immersed in a mixed solution containing NH2OH and H2O2, reacted at 60-80°C for 2-4 hours, and then taken out, washed and dried to obtain amino-treated carbon fibers.

[0022] The mixed solution containing NH2OH and H2O2 is obtained by mixing a hydroxylamine hydrochloride aqueous solution (with a concentration of 0.5 mol / L) and hydrogen peroxide (with a mass percentage concentration of 30%). The hydroxylamine hydrochloride aqueous solution and hydrogen peroxide are mixed in a mass ratio (hydroxylamine hydrochloride aqueous solution: hydrogen peroxide) of 1:3 to 1:5.

[0023] As an embodiment of the present invention, the reaction temperature of the prepolymerization reaction is 50 to 80° C., and the prepolymerization reaction time is 1 to 2 hours.

[0024] As an embodiment of the present invention, the stretching ratio of the stretching is (3.5-4.5):1.

[0025] The present invention also provides a PEEK conductive monofilament obtained by the preparation method of the present invention.

[0026] The PEEK conductive monofilament prepared by the preparation method of the present invention has a core-shell cross-sectional structure, with a shell thickness of 30 to 150 μm, accounting for approximately 15 to 30% of the monofilament diameter. The diameter of the PEEK conductive monofilament is 200 to 500 μm. The core of the PEEK conductive monofilament is a PEEK matrix, and the shell layer wrapped around the core is a continuous conductive layer formed by PEDOT / PVA-coated carbon fibers, comprising:

[0027] PEDOT coating layer: located on the surface of carbon fiber, with a thickness of 50 to 85 μm, which is the main conductive part of the shell;

[0028] PVA cross-linked carbon residue: During the melt processing, PVA is partially carbonized to form a porous network with a pore size of 10 to 30 μm, and the mass ratio of PVA to the PEDOT coating layer is 1:3 to 1:5;

[0029] Carbon fiber: embedded in the shell as a skeleton, providing a longitudinal conductive path.

[0030] The shell layer is a composite structure, including a PEDOT coating layer, a PVA carbonized porous network and carbon fibers, which together constitute a three-dimensional interpenetrating conductive network; the PEDOT coating layer is a key component of the shell layer, responsible for the lateral conductive path; the PVA porous network serves as an auxiliary conductive channel, filling the insulating gaps in the PEEK matrix.

[0031] The method of the present invention forms a three-dimensional interpenetrating conductive network through in-situ polymerization of amino carbon fibers and a PVA / EDOT mixture, and combines the PEEK melt molding process to achieve efficient conductive path construction.

[0032] The conductive network hierarchical structure of the PEEK conductive monofilament prepared by the present invention is described as follows:

[0033] 1. Primary structure: carbon fiber-PEDOT core-shell unit

[0034] Carbon fiber surface amination: The amino group (-NH2) introduced by NH2OH / H2O2 treatment forms a hydrogen bond with the hydroxyl group (-OH) of PVA, and combines with the EDOT monomer through π-π stacking or chemical adsorption; PEDOT coating: on the Fe 3+ Under the initiation of EDOT, EDOT polymerizes on the carbon fiber surface to form a continuous PEDOT conductive coating layer. The thickness of the PEDOT conductive coating layer can be adjusted by adjusting the EDOT concentration in the dispersion and the prepolymerization time.

[0035] 2. Secondary structure: PVA cross-linked network

[0036] PVA participates in the structure in the following ways: dynamic cross-linking: PVA is partially dehydrated during melt processing to form cross-linking points; carbon residue: PVA is partially carbonized at high temperature to form a porous carbon network.

[0037] 3. Tertiary structure: PEEK matrix and conductive network interpenetrate

[0038] Interpenetration mechanism: The PEDOT / PVA network and molten PEEK are entangled and interwoven under the shearing action of the screw, forming a dual structure of "sea-island" and "network-skeleton".

[0039] The conductive path construction of the PEEK conductive monofilament prepared by the present invention is described as follows:

[0040] 1. Main conductive path:

[0041] Carbon fiber skeleton: Aminated carbon fibers provide a highly conductive longitudinal path (axial conductivity > 500S / m), forming a percolation network through end contact; PEDOT coating: The surface conductive layer laterally connects adjacent fibers to form a two-dimensional conductive plane.

[0042] 2. Secondary conductive path:

[0043] PVA carbonized residual network: The porous carbon structure provides auxiliary conductive channels (filling the insulating gaps in the PEEK matrix), with a resistance contribution rate of approximately 15%; PEDOT nanowires: Some uncoated fiber PEDOT is stretched into nanowires in the shear flow field, bridging adjacent fibers to form a conductive path.

[0044] The PEEK conductive monofilament obtained by the method of the present invention has a resistivity of ≤8Ω·cm at 23°C, and a resistance change rate of ≤5% after 100 cycles of bending (curvature radius 3mm); it has both excellent mechanical properties (tensile strength ≥80MPa) and resistance to extreme environments (limiting oxygen index (LOI) ≥32%). The conductive monofilament has an ultra-low percolation threshold. Since the PEDOT interface layer constructs a permeation network, the percolation threshold is significantly lower than the traditional filler addition method. The heat resistance of the conductive monofilament is also significantly improved, and the PVA cross-linked carbon residue layer effectively delays the thermal decomposition of PEEK. The method of the present invention can also achieve the adjustment of the thickness of the PEDOT coating layer in the shell layer of the obtained PEEK conductive monofilament to meet the needs of different market scenarios. DETAILED DESCRIPTION

[0045] The following examples are intended to further illustrate the present invention, but are not intended to limit the scope of protection of the present invention.

[0046] In the following examples or comparative examples, unless otherwise specified, the drugs used are all commercially available products.

[0047] Example 1

[0048] This embodiment provides a method for preparing a PEEK conductive monofilament, comprising the following steps:

[0049] (1) Preparation of dispersion

[0050] Polyvinyl alcohol (PVA) and 3,4-ethylenedioxythiophene (EDOT) monomers were mixed with water to prepare a mixed aqueous solution, and the amino carbon fibers were dispersed in the mixed aqueous solution. Ultrasonic dispersion was used for dispersion, and 300W ultrasonic dispersion was performed for 40 minutes to prepare a dispersion liquid. The mass percentage concentrations of the amino carbon fibers, PVA, and EDOT monomers in the dispersion liquid were 10% (amino carbon fibers), 8% (PVA), and 16% (EDOT), respectively.

[0051] The amination carbon fibers used are obtained by the following steps:

[0052] The chopped carbon fibers were immersed in a mixed solution containing NH2OH and H2O2, reacted at 75°C for 3 hours, and then taken out, washed and dried to obtain amino-treated carbon fibers;

[0053] Among them, the length of the chopped carbon fiber used is 200 μm;

[0054] The mixed solution containing NH2OH and H2O2 is obtained by mixing a hydroxylamine hydrochloride aqueous solution (concentration of 0.5 mol / L) and hydrogen peroxide (mass percentage concentration of 30%), wherein the hydroxylamine hydrochloride aqueous solution and the hydrogen peroxide are mixed in a mass ratio of 1:4 (hydroxylamine hydrochloride aqueous solution: hydrogen peroxide);

[0055] The surface amino density of amino-treated carbon fibers is 3.5×10 14 groups / cm2;

[0056] (2) 500 g of the dispersion prepared in step (1) was added with 0.09 mol of FeCl3 initiator (the molar ratio of FeCl3 initiator to the amino carbon fiber contained in the dispersion was 1:46) to carry out a prepolymerization reaction at 60° C. for 1 h to obtain a PEDOT / PVA coated carbon fiber prepolymer;

[0057] (3) blending the prepared PEDOT / PVA coated carbon fiber prepolymer with molten PEEK in a twin-screw extruder, wherein the mass ratio of the PEDOT / PVA coated carbon fiber prepolymer to the molten PEEK is 1:4;

[0058] The twin-screw extruder includes three temperature gradient zones: zone 1, zone 2, and zone 3. The temperature of zone 1 is 340°C, the temperature of zone 2 is 370°C, and the temperature of zone 3 is 380°C. The screw speed of the twin-screw extruder is 30 rpm. At the end of zone 2, 0.03 mol of FeCl3 initiator is added to the material in the twin-screw extruder.

[0059] The PEEK conductive monofilament is then extruded and drawn after passing through a spinning die with a die diameter of 0.5 mm and a draw ratio of 4:1. The monofilament is then shaped by heat setting at 180° C. for 5 minutes with a relaxation rate of 5%, thereby obtaining the PEEK conductive monofilament.

[0060] The diameter of the PEEK conductive monofilament obtained in this example is 220 μm. This PEEK conductive monofilament has a core-shell cross-sectional structure, with the core being a PEEK matrix and the shell surrounding the core being a continuous conductive layer formed from PEDOT / PVA-coated carbon fibers. The shell thickness was measured and found to be 55 ± 10 μm, representing approximately 25% of the monofilament diameter.

[0061] In this embodiment, the PVA cross-linked carbon residue forms a porous network with a pore size of 20±5 μm, and the mass ratio of the porous network to the PEDOT layer is 1:4.

[0062] The resistivity, tensile strength, interfacial bonding strength, resistance change rate after bending, TGA carbon residue rate (800°C), and percolation threshold of the conductive monofilament were tested respectively. The test results are shown in Table 1 below.

[0063] Table 1

[0064]

[0065] Example 2

[0066] This embodiment provides a method for preparing a PEEK conductive monofilament, comprising the following steps:

[0067] (1) Preparation of dispersion

[0068] Polyvinyl alcohol (PVA) and 3,4-ethylenedioxythiophene (EDOT) monomers were mixed with water to prepare a mixed aqueous solution, and the amino carbon fibers were dispersed in the mixed aqueous solution. Ultrasonic dispersion was performed at 500W for 60 minutes to prepare a dispersion liquid. The mass percentage concentrations of the amino carbon fibers, PVA, and EDOT monomers in the dispersion liquid were 12% (amino carbon fibers), 8% (PVA), and 24% (EDOT), respectively.

[0069] The amination carbon fibers used were the same as those used in Example 1;

[0070] (2) 500 g of the dispersion prepared in step (1) was added with 0.12 mol of FeCl3 initiator (the molar ratio of FeCl3 initiator to amino carbon fiber contained in the dispersion was 1:41.7), and a prepolymerization reaction was carried out at 60° C. for 1 h to obtain a PEDOT / PVA coated carbon fiber prepolymer;

[0071] (3) blending the prepared PEDOT / PVA coated carbon fiber prepolymer with molten PEEK in a twin-screw extruder, wherein the mass ratio of the PEDOT / PVA coated carbon fiber prepolymer to the molten PEEK is 1:3;

[0072] The twin-screw extruder includes three temperature gradient zones: zone 1, zone 2, and zone 3. The temperature of zone 1 is 340°C, the temperature of zone 2 is 370°C, and the temperature of zone 3 is 380°C. The screw speed of the twin-screw extruder is 30 rpm. At the end of zone 2, 0.03 mol of FeCl3 initiator is added to the material in the twin-screw extruder.

[0073] The PEEK conductive monofilament is then extruded and drawn after passing through a spinning die with a die diameter of 0.5 mm and a draw ratio of 4.5:1. The monofilament is then shaped by heat setting at 180° C. for 5 minutes with a relaxation rate of 5%, thereby obtaining the PEEK conductive monofilament.

[0074] The diameter of the PEEK conductive monofilament obtained in this example is 300 μm. The shell surrounding the core is a continuous conductive layer formed by PEDOT / PVA-coated carbon fibers. The thickness of the conductive layer (i.e., the shell) was measured to be 40 ± 8 μm, representing approximately 13.3% of the monofilament diameter.

[0075] The PVA cross-linked carbon residue formed a porous network with a pore size of 20 ± 5 μm, and the mass ratio of the porous network to the PEDOT layer was 1:4.

[0076] The resistivity and tensile strength of the conductive monofilament were tested respectively, and the test results are shown in Table 2 below.

[0077] Table 2

[0078] Test items Test results Resistivity (23℃) 5.2Ω·cm tensile strength 96MPa

[0079] Example 3

[0080] This embodiment provides a method for preparing a PEEK conductive monofilament, comprising the following steps:

[0081] (1) Preparation of dispersion

[0082] Polyvinyl alcohol (PVA) and 3,4-ethylenedioxythiophene (EDOT) monomers were mixed with water to prepare a mixed aqueous solution, and the amino carbon fibers were dispersed in the mixed aqueous solution. Ultrasonic dispersion was performed at 500W for 40 minutes to prepare a dispersion liquid. The mass percentage concentrations of the amino carbon fibers, PVA, and EDOT monomers in the dispersion liquid were 12% (amino carbon fibers), 8% (PVA), and 24% (EDOT), respectively.

[0083] The amination carbon fibers used were the same as those used in Example 1;

[0084] (2) 500 g of the dispersion obtained in step (1) was added with 0.12 mol of FeCl3 initiator to carry out a prepolymerization reaction at 60° C. for 2 h to obtain a PEDOT / PVA coated carbon fiber prepolymer;

[0085] (3) blending the prepared PEDOT / PVA coated carbon fiber prepolymer with molten PEEK in a twin-screw extruder, wherein the mass ratio of the PEDOT / PVA coated carbon fiber prepolymer to the molten PEEK is 1:3;

[0086] The twin-screw extruder includes three temperature gradient zones: zone 1, zone 2, and zone 3. The temperature of zone 1 is 340°C, the temperature of zone 2 is 370°C, and the temperature of zone 3 is 380°C. The screw speed of the twin-screw extruder is 30 rpm. At the end of zone 2, 0.03 mol of FeCl3 initiator is added to the material in the twin-screw extruder.

[0087] The PEEK conductive monofilament is then extruded and drawn after passing through a spinning die with a die diameter of 0.5 mm and a draw ratio of 4:1. The monofilament is then shaped by heat setting at 180° C. for 5 minutes with a relaxation rate of 5%, thereby obtaining the PEEK conductive monofilament.

[0088] The diameter of the PEEK conductive monofilament obtained in this example is 280 μm. The shell surrounding the core is a continuous conductive layer formed by PEDOT / PVA-coated carbon fibers. The thickness of the conductive layer (i.e., the shell) was measured to be 85 ± 15 μm, representing approximately 30% of the monofilament diameter.

[0089] In this embodiment, the PVA cross-linked carbon residue forms a porous network with a pore size of 25±5 μm, and the mass ratio of the porous network to the PEDOT layer is 1:4.5.

[0090] The resistivity and tensile strength of the conductive monofilament were tested respectively, and the test results are shown in Table 3 below.

[0091] Table 3

[0092] Test items Test results Resistivity (23℃) 3.5Ω·cm tensile strength 82MPa

[0093] Comparative Example 1

[0094] This comparative example provides a method for preparing a PEEK conductive monofilament, comprising the following steps:

[0095] (1) Preparation of dispersion

[0096] Polyvinyl alcohol (PVA) and 3,4-ethylenedioxythiophene (EDOT) monomers were mixed with water to prepare a mixed aqueous solution, and the amino carbon fibers were dispersed in the mixed aqueous solution. Ultrasonic dispersion was used for dispersion, and 300W ultrasonic dispersion was performed for 40 minutes to prepare a dispersion liquid. The mass percentage concentrations of the amino carbon fibers, PVA, and EDOT monomers in the dispersion liquid were 10% (amino carbon fibers), 8% (PVA), and 16% (EDOT), respectively.

[0097] The amination carbon fibers used were the same as those used in Example 1;

[0098] (2) 500 g of the dispersion obtained in step (1) was added with 0.12 mol of FeCl3 initiator to carry out a prepolymerization reaction at 60° C. for 1 h to obtain a PEDOT / PVA coated carbon fiber prepolymer;

[0099] (3) blending the prepared PEDOT / PVA coated carbon fiber prepolymer with molten PEEK in a twin-screw extruder, wherein the mass ratio of the PEDOT / PVA coated carbon fiber prepolymer to the molten PEEK is 1:4;

[0100] The twin-screw extruder includes three temperature gradient zones: zone 1, zone 2, and zone 3. The temperature of zone 1 is 340°C, the temperature of zone 2 is 370°C, and the temperature of zone 3 is 380°C. The screw speed of the twin-screw extruder is 30 rpm.

[0101] The PEEK conductive monofilament is then extruded and drawn after passing through a spinning die with a die diameter of 0.5 mm and a draw ratio of 4:1. The monofilament is then shaped by heat setting at 180° C. for 5 minutes with a relaxation rate of 5%, thereby obtaining the PEEK conductive monofilament.

[0102] The PEEK conductive monofilament obtained in this comparative example was compared to the PEEK conductive monofilament obtained in Example 1. The conductive layer of the conductive monofilament in Example 1 was a continuous and uniform film, while the conductive layer of this comparative example exhibited localized cracking and agglomeration. This was primarily because the initiator in Comparative Example 1 was added only during the prepolymerization reaction, resulting in uneven polymerization.

[0103] The resistivity and tensile strength of the conductive monofilament of this comparative example were tested, and the test results are shown in Table 4 below.

[0104] Table 4

[0105] Test items Test results Resistivity (23℃) 15.3Ω·cm tensile strength 76MPa

[0106] It can be seen from the data in the table that the conductive monofilament prepared in comparative example 1 has a significantly improved resistance value and a decreased tensile strength compared to the conductive monofilament in example 1. This is due to the uneven coating of the carbon fibers in the conductive layer, which leads to easy breakage.

[0107] Comparative Example 2

[0108] This comparative example provides a method for preparing a PEEK conductive monofilament, comprising the following steps:

[0109] (1) Preparation of dispersion

[0110] Polyvinyl alcohol (PVA) and 3,4-ethylenedioxythiophene (EDOT) monomers were mixed with water to prepare a mixed aqueous solution, and acetone-washed carbon fibers were dispersed in the mixed aqueous solution. Ultrasonic dispersion was used for dispersion, and 500W ultrasonic dispersion was performed for 40 minutes to prepare a dispersion liquid. The mass percentage concentrations of acetone-washed carbon fibers, PVA, and EDOT monomers in the dispersion liquid were 10% (acetone-washed carbon fibers), 8% (PVA), and 16% (EDOT), respectively.

[0111] The acetone-cleaned carbon fibers were obtained by the following steps:

[0112] The chopped carbon fibers were washed with acetone and dried to obtain acetone-washed carbon fibers; wherein the length of the chopped carbon fibers used was 200 μm;

[0113] (2) 500 g of the dispersion obtained in step (1) was added with 0.09 mol of FeCl3 initiator to carry out a prepolymerization reaction at 60° C. for 1 h to obtain a PEDOT / PVA coated carbon fiber prepolymer;

[0114] (3) blending the prepared PEDOT / PVA coated carbon fiber prepolymer with molten PEEK in a twin-screw extruder, wherein the mass ratio of the PEDOT / PVA coated carbon fiber prepolymer to the molten PEEK is 1:4;

[0115] The twin-screw extruder includes three temperature gradient zones: zone 1, zone 2, and zone 3. The temperature of zone 1 is 340°C, the temperature of zone 2 is 370°C, and the temperature of zone 3 is 380°C. The screw speed of the twin-screw extruder is 30 rpm. At the end of zone 2, 0.03 mol of FeCl3 initiator is added to the material in the twin-screw extruder.

[0116] The PEEK conductive monofilament is then extruded and drawn after passing through a spinning die with a die diameter of 0.5 mm and a draw ratio of 4:1. The monofilament is then shaped by heat setting at 180° C. for 5 minutes with a relaxation rate of 5%, thereby obtaining the PEEK conductive monofilament.

[0117] The interfacial bonding strength, resistance change rate after bending, and TGA carbon residue rate (800° C.) of the PEEK conductive monofilament obtained in this comparative example were tested, and the test results are shown in Table 5 below.

[0118] Table 5

[0119]

[0120] The data in the table show that the conductive monofilaments produced in Comparative Example 2 exhibit decreased interfacial bonding strength, increased resistance change after bending, and decreased TGA carbon residue compared to those in Example 1. This is primarily due to the fact that the chopped carbon fibers in this comparative example were not amination-treated. Using amination-treated carbon fibers enhances interfacial properties through chemical coupling, improving bendability and resisting delamination of the physically adsorbed layer. Furthermore, the PVA cross-linked carbon layer effectively inhibits matrix decomposition.

[0121] Comparative Example 3

[0122] This comparative example provides a method for preparing a PEEK conductive monofilament, comprising the following steps:

[0123] (1) Short-cut carbon fibers, polyvinyl alcohol (PVA), 3,4-ethylenedioxythiophene (EDOT) monomers and molten PEEK are blended in a twin-screw extruder. The blending mass ratio of carbon fibers, EDOT, PVA and molten PEEK is: carbon fibers: EDOT: PVA: PEEK = 10:8:2:80. The length of the short-cut carbon fibers used is 200 μm.

[0124] The twin-screw extruder includes three temperature gradient zones: zone 1, zone 2, and zone 3. The temperature of zone 1 is 340°C, the temperature of zone 2 is 370°C, and the temperature of zone 3 is 380°C. The screw speed of the twin-screw extruder is 30 rpm.

[0125] The PEEK conductive monofilament is then extruded and drawn after passing through a spinning die with a die diameter of 0.5 mm and a draw ratio of 4:1. The monofilament is then shaped by heat setting at 180° C. for 5 minutes with a relaxation rate of 5%, thereby obtaining the PEEK conductive monofilament.

[0126] The resistivity, tensile strength, and percolation threshold of the PEEK conductive monofilament obtained in this comparative example were tested, and the test results are shown in Table 6 below.

[0127] Table 6

[0128] Test items Test results Resistivity (23℃) 105Ω·cm tensile strength 63MPa Percolation threshold (vol%) 12％

[0129] As can be seen from the data in the table, the resistivity of the conductive monofilament prepared in Comparative Example 3 is significantly improved compared with the conductive monofilament in Example 1, indicating that the direct blending method cannot conduct the network; the tensile strength decreases because the excessive filler destroys the continuity of the matrix, resulting in low tensile strength; and the percolation efficiency is also increased to about 7 times that of the conductive monofilament in Example 1.

[0130] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or any direct or indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing PEEK conductive monofilament, characterized in that: Including steps: (1) adding polyvinyl alcohol and 3,4-ethylenedioxythiophene to water to prepare a mixed aqueous solution, and dispersing the amino-treated carbon fibers in the mixed aqueous solution to prepare a dispersion; Adding FeCl3 initiator to the dispersion to carry out a prepolymerization reaction to obtain a PEDOT / PVA coated carbon fiber prepolymer; (2) The PEDOT / PVA coated carbon fiber prepolymer obtained in step (1) is blended with molten PEEK, and then extruded through a spinning die and stretched, and then shaped to obtain PEEK conductive monofilaments.

2. The preparation method according to claim 1, characterized in that The mass percentage concentration of the amino carbon fibers in the dispersion is 5 to 15%; and / or, The mass percentage concentration of polyvinyl alcohol in the dispersion is 5 to 10%; and / or, The mass percentage concentration of 3,4-ethylenedioxythiophene in the dispersion is 15-25%.

3. The preparation method according to claim 1, characterized in that The amount of the FeCl3 initiator added to the dispersion is: the molar ratio of the FeCl3 initiator to the amination carbon fibers contained in the dispersion is 1:(30-50).

4. The preparation method according to any one of claims 1 to 3, characterized in that The blending is carried out in a twin-screw extruder, which includes three temperature gradient zones: zone 1, zone 2, and zone 3. The temperature range of zone 1 is 320-340°C, the temperature range of zone 2 is 360-380°C, and the temperature range of zone 3 is 360-380°C.

5. The preparation method according to claim 4, characterized in that At the end of the second zone or at the front end of the third zone, FeCl3 initiator is added to the material in the twin-screw extruder; the molar ratio of the FeCl3 initiator added to the twin-screw extruder to the FeCl3 initiator added to the dispersion is (1-3): (1-12).

6. The preparation method according to claim 1, characterized in that The amination-treated carbon fibers are short-cut carbon fibers that have been amination-treated. The length of the short-cut carbon fibers is 150 to 250 μm, and the surface amino density of the amination-treated carbon fibers is ≥3.2×10 14 groups / cm2.

7. The preparation method according to claim 6, characterized in that The preparation steps of the amination carbon fiber include: The chopped carbon fibers are immersed in a mixed solution containing NH2OH and H2O2, reacted at 60-80°C for 2-4 hours, and then taken out, washed and dried to obtain amino-treated carbon fibers.

8. The preparation method according to claim 1, characterized in that The PEDOT / PVA coated carbon fiber prepolymer prepared in step (1) is blended with molten PEEK in a mass ratio of 1:(2-9).

9. The preparation method according to claim 1, characterized in that The reaction temperature of the prepolymerization reaction is 50-80° C., and the prepolymerization reaction time is 1-2 hours.

10. A PEEK conductive monofilament obtained by the preparation method according to any one of claims 1 to 9.

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