Apparatus and method for preparing carbon nanotube-reinforced thermoplastic composite wire

Abstract

The application provides a preparation device and method of carbon nanotube reinforced thermoplastic composite filament, relates to the technical field of 3D printing, and comprises the following steps: pre-impregnating an original filament to implant carbon nanomaterial into the surface of the original filament to form a pre-impregnated filament; and using a thermoplastic polymer to re-impregnate the pre-impregnated filament to form a composite filament. The carbon nanomaterial is uniformly implanted into the surface of the filament coated with a sizing agent through electrostatic flocking, the pre-impregnated filament is combined with the thermoplastic polymer matrix through melt impregnation, the controllable dispersion of the carbon nanomaterial is realized, and internal defects of the composite filament are avoided. The problems, such as the easy agglomeration of the dispersed carbon nanomaterial in the resin matrix and the poor combination of the carbon nanomaterial with the matrix material, in the impregnation process are effectively solved, the interlayer bonding performance of a 3D printed sample is enhanced, the dielectric loss performance of the composite filament is optimized, the electromagnetic heating characteristics of the composite filament are enhanced, the 3D printed component can realize local temperature compensation through an external electromagnetic field, the warping deformation of the sample is weakened, and the overall performance of the filament is improved.

Description

Technical Field

[0001] This application relates to the field of 3D printing technology, specifically to an apparatus and method for preparing carbon nanotube-reinforced thermoplastic composite filaments. Background Technology

[0002] Continuous fiber reinforced 3D printing, as a cutting-edge additive manufacturing technology, enables the rapid and precise fabrication of complex shapes and structures through layer-by-layer construction. This meets the requirements of thermoplastic composites in the aerospace, aviation, and medical service sectors for complex structures and high-precision manufacturing. However, weak interlayer properties and structural warping are bottlenecks hindering the large-scale industrial application of composite materials.

[0003] The current conventional approach is to introduce carbon nanotubes into composite filaments. Introducing carbon nanotubes into composite filaments is an effective measure to address the poor interlaminar properties and structural warping deformation of thermoplastic composites. However, existing processes for preparing continuous fiber-reinforced thermoplastic composite filaments mainly involve dispersing nanoparticles in a resin matrix and achieving resin-fiber composite through melt impregnation. Due to the high surface energy and interaction forces (van der Waals forces, electrostatic interactions, etc.) of nanoparticles, localized aggregation of nanoparticles dispersed in the resin is prone to occur, affecting the physicochemical properties of the filament. Summary of the Invention

[0004] The purpose of this application is to provide a device and method for preparing carbon nanotube-reinforced thermoplastic composite filaments, which can solve the problems of weak interlayer properties and structural warping deformation in composite filaments, and improve the overall performance of composite filaments.

[0005] In one aspect of this application, a method for preparing a carbon nanotube-reinforced thermoplastic composite filament is provided, comprising pre-impregnating a raw filament to implant carbon nanomaterials into the surface of the raw filament to form a pre-impregnated filament;

[0006] The prepreg filament is re-impregnated with a thermoplastic polymer to form a composite filament.

[0007] Optionally, the pre-impregnation of the filament to implant carbon nanomaterials into the surface of the filament to form a pre-impregnated filament includes:

[0008] After the raw filament is unwound, it is sized and impregnated with a sizing agent; wherein the sizing agent includes any one of polyamic acid, water-soluble polyimide, water-soluble polyamide, waterborne polyurethane, sulfonated polyether ether ketone, and epoxy resin.

[0009] The sized filaments are subjected to thermal desizing to remove excess sizing from the surface of the filaments, and the sizing on the surface of the filaments is pre-cured by heating.

[0010] The pre-cured filament is subjected to electrostatic flocking treatment, which implants the carbon nanomaterials into the surface of the filament.

[0011] The filament is heated to solidify the carbon nanomaterials on its surface, forming the prepreg filament.

[0012] Optionally, the re-impregnation of the prepreg filament with a thermoplastic polymer to form a composite filament includes:

[0013] After the prepreg filament is unwound, it is melt-impregnated with the thermoplastic polymer; wherein the thermoplastic polymer includes polyamide, thermoplastic polyurethane, polyetherimide, polyphenylene sulfide, and polyaryletherketone.

[0014] The molten impregnated filament is subjected to thermal desizing to remove excess sizing from the surface of the filament, and the thermoplastic polymer on the surface of the filament is pre-cured by heating.

[0015] The pre-cured filaments are subjected to multi-stage cooling and shaping to form the composite filaments.

[0016] Optionally, after the prepreg filament is unwound, it is melt-impregnated with a thermoplastic polymer, including:

[0017] The thermoplastic polymer is filled into a melt impregnation tank, and the prepreg filament is passed through the melt impregnation tank to coat the surface of the prepreg filament with the thermoplastic polymer.

[0018] An ultrasonic device is installed in the melt impregnation tank to eliminate the pores between the prepreg filament and the thermoplastic polymer.

[0019] Optionally, the pre-cured filament undergoes multi-stage cooling and shaping to form the composite filament, and then the method further includes:

[0020] The composite filament is wound up, and the winding angle of the composite filament is adjusted to achieve constant tension and stable winding.

[0021] Another aspect of this application provides a preparation apparatus for carbon nanotube-reinforced thermoplastic composite filaments, applied to the above-mentioned preparation method of carbon nanotube-reinforced thermoplastic composite filaments, including: a pre-impregnation device for forming pre-impregnated filaments, and a melt impregnation device for forming composite filaments;

[0022] The prepreg device includes a first unwinding assembly, a sizing and impregnation assembly, a first thermal desizing assembly, an electrostatic flocking assembly, a heat curing assembly, and a first winding assembly arranged in sequence. The original filament is coiled on the first unwinding assembly. After being unwound by the first unwinding assembly, it passes sequentially through the sizing and impregnation assembly, the first thermal desizing assembly, the electrostatic flocking assembly, and the heat curing assembly to form the coiled prepreg filament on the first winding assembly.

[0023] The melt impregnation device includes a second unwinding assembly, a melt impregnation assembly, a second hot desizing assembly, a cooling and shaping assembly, and a second winding assembly arranged in sequence. The prepreg filament is coiled on the second unwinding assembly. After being unwound by the second unwinding assembly, it passes sequentially through the melt impregnation assembly, the second hot desizing assembly, and the cooling and shaping assembly, and then forms the coiled composite filament on the second winding assembly.

[0024] Optionally, the sizing and impregnation assembly includes an impregnation tank and a first roller, the thermal desizing assembly includes a desizing tank and a first pressure roller, the electrostatic flocking assembly includes a flocking box and a plurality of carbon nanotubes disposed in the flocking box, and the heat curing assembly includes a heating box and a plurality of heating tubes disposed in the heating box. After the raw filament is unwound, it is pulled sequentially along the first roller and the first pressure roller, and then passes through the gaps between the plurality of carbon nanotubes in the flocking box and the gaps between the plurality of heating tubes in the heating box to form the prepreg filament.

[0025] Optionally, the melt impregnation assembly includes a melt impregnation tank and a second roller, the second hot desizing assembly includes a desizing tank and a second pressure roller, and the cooling and shaping assembly includes multiple heating elements and a third pressure roller. After the prepreg filament is unwound, it is pulled sequentially along the second roller and the second pressure roller, passing through the gaps between the multiple heating elements and the third pressure roller to form the composite filament.

[0026] Optionally, the melt impregnation tank is further equipped with an ultrasonic device for ultrasonically treating the filaments passing through the melt impregnation tank.

[0027] Optionally, a single-screw extruder is also provided at one end of the melt impregnation tank to convert thermoplastic resin particles into molten fluid and replenish the melt impregnation tank with thermoplastic polymer raw materials.

[0028] The equipment and method for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this application embodiment achieve uniform coating of slurry through a thermal desizing process during the pre-impregnation stage of the original filament, and partially evaporate the solvent in the slurry, giving the filament a certain degree of viscosity. Carbon nanomaterials are uniformly implanted onto the surface of the filament coated with the sizing agent through an electrostatic flocking process. Then, the pre-impregnated filament is composited with a thermoplastic polymer matrix through a melt impregnation process, achieving controllable dispersion of carbon nanomaterials and avoiding internal defects in the composite filament. On the one hand, this effectively solves the problems of easy agglomeration of dispersed carbon nanomaterials in the resin matrix and weak bonding with the matrix material during impregnation, enhancing the interlayer bonding performance of 3D printed samples. On the other hand, it optimizes the dielectric loss performance of the composite filament and enhances its electromagnetic heating characteristics, enabling 3D printed components to achieve local temperature compensation through an external electromagnetic field, reducing warpage deformation of the sample and improving the overall performance of the filament. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the pre-impregnation device structure of the equipment for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this embodiment;

[0031] Figure 2 This is a schematic diagram of the carbon nanomaterial implantation process in the preparation method of carbon nanotube-reinforced thermoplastic composite filament provided in this embodiment;

[0032] Figure 3 This is a schematic diagram of the melt impregnation device structure of the equipment for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this embodiment;

[0033] Figure 4 This is a schematic diagram of the composite filament structure prepared by the method for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this embodiment;

[0034] Figure 5 This is one of the partial structural schematic diagrams of the pre-impregnation device of the equipment for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this embodiment;

[0035] Figure 6 This is the second partial structural schematic diagram of the pre-impregnation device of the equipment for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this embodiment;

[0036] Figure 7This is one of the schematic diagrams of the melt impregnation device structure of the equipment for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this embodiment;

[0037] Figure 8 This is the second schematic diagram of the melt impregnation device structure of the equipment for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this embodiment.

[0038] Icons: 10-First unwinding assembly; 11-Sizing and impregnation assembly; 110-Impregnation tank; 111-First roller; 12-First hot desizing assembly; 120-Desizing tank; 121-First pressure roller; 13-Electrostatic flocking assembly; 130-Flocking box; 131-Carbon nanotubes; 14-Heat curing assembly; 140-Heating box; 15-First winding assembly; 16-Second unwinding assembly; 17-Melted impregnation assembly; 17 0-Melting impregnation tank; 171-Second roller; 172-Ultrasonic device; 173-Single screw extruder; 18-Second hot desizing assembly; 181-Second pressure roller; 19-Cooling and shaping assembly; 190-Shaping box; 191-Third pressure roller; 192-Heating element; 20-Second winding assembly; 30-Raw filament; 31-Prepreg filament; 32-Composite filament; 33-Carbon nanomaterial; 34-Thermoplastic polymer matrix. Detailed Implementation

[0039] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0040] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] It should also be noted that, unless otherwise explicitly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0042] Weak interlaminar properties and structural warping are currently bottlenecks restricting the large-scale industrial application of composite materials. The interface between fibers and thermoplastic resins is the medium for stress transfer, and its interface characteristics and chemical composition directly affect the mechanical properties of molded components. By introducing carbon nanotubes into composite filaments, the "interlocking" effect between interfaces can be enhanced, which is beneficial to improving the interlaminar properties of the material. In addition, carbon nanotubes are typical dielectric loss materials, and introducing them into composite filaments can improve their thermal response to electromagnetic waves. By applying an external electromagnetic field, cross-linking of the thermoplastic matrix at the interface and release of residual stress in 3D printing can be promoted. Therefore, introducing carbon nanotubes into composite filaments is an effective measure to solve the problems of poor interlaminar properties and structural warping in thermoplastic composites.

[0043] Currently, the main process for preparing continuous fiber-reinforced thermoplastic composite filaments involves dispersing nanoparticles in a resin matrix and then using a melt impregnation process to composite the resin and fibers. However, the impregnation process for nanoparticle-modified composite filaments presents several challenges, such as uneven dispersion of nanoparticles in the resin matrix, insufficient impregnation, and uneven fiber surface texture after impregnation, all of which affect filament performance and printing quality.

[0044] To address the aforementioned problems, this application provides a method for preparing a carbon nanotube-reinforced thermoplastic composite filament, the method comprising:

[0045] Step 200: Pre-impregnate the original filament 30 to implant carbon nanomaterials 33 into the surface of the original filament 30 to form a pre-impregnated filament 31.

[0046] Among them, the raw filament 30 includes any one of glass fiber, basalt fiber and carbon fiber.

[0047] Specifically, such as Figure 1 As shown, step 200.1 is as follows: after the raw filament 30 is unwound, the raw filament 30 is sized and impregnated with a sizing agent.

[0048] The raw filament 30 is wound on the first unwinding assembly 10, which is generally a reel. The rotation of the reel can pull the raw filament 30 to unwind, so that multiple bundles of parallel raw filament 30 are sized in the impregnation tank 110. The impregnation tank 110 is filled with a sizing agent for thermoplastic filaments. A first roller 111 is provided in the impregnation tank 110, and a first roller 111 is also provided outside the impregnation tank 110 through a column. The raw filament 30 is pulled along the first roller 111 to pass through the impregnation tank 110, so that the sizing agent adheres to the surface of the raw filament 30.

[0049] The sizing agent is a thermoplastic or thermosetting polymer, including any one of polyamic acid, water-soluble polyimide, water-soluble polyamide, waterborne polyurethane, sulfonated polyether ether ketone, and epoxy resin.

[0050] Step 200.2: Perform hot desizing on the sized filament to remove excess sizing from the surface of the filament and pre-cur the sizing on the surface of the filament by heating.

[0051] After being sized in the impregnation tank 110, the filament enters the desizing tank 120. The column of the desizing tank 120 is equipped with a first pressure roller 121. Two first pressure rollers 121 form a pair. The filament passes through the gap between the pair of first pressure rollers 121. The pressure rollers can be heated at 30℃ to 200℃ to pre-cure the sizing on the surface of the filament and make it sticky.

[0052] Meanwhile, a scraper is also provided on one side of the first pressure roller 121 to remove excess slurry, which is then recovered through the impregnation tank 110.

[0053] Step 200.3: Perform electrostatic flocking treatment on the pre-cured filament to implant carbon nanomaterials 33 into the surface of the filament.

[0054] The pre-cured filament is then drawn into the flocking box 130. Carbon nanomaterials 33, such as carbon nanotubes 131, are placed in the flocking box 130. After the power is turned on, the carbon nanotubes 131 are given a negative charge. When they come into contact, the carbon nanotubes 131 fly up onto the filament impregnated with the slurry under the action of the high voltage electric field.

[0055] like Figure 2 As shown, by controlling the concentration of carbon nanotubes 131 and the process parameters of the flocking equipment, carbon nanotubes 131 are uniformly implanted into the outer surface of parallel filaments.

[0056] Two carbon nanotubes 131 form a group, and the filament can pass through the gaps of multiple groups of carbon nanotubes 131 in sequence. The filament completes the implantation of carbon nanotubes 131 through multiple flocking processes in different directions.

[0057] Electrostatic flocking is a process that uses an electrostatic field to uniformly implant short fibers onto the surface of a substrate coated with an adhesive. To improve the dispersion uniformity of carbon nanotubes 131 in the composite filament 32, the carbon nanotubes are pre-embedded uniformly into the surface of the filament through electrostatic flocking. Then, the pre-impregnated filament 31 is composited with a thermoplastic resin matrix through a subsequent melt impregnation process, thereby achieving controllable dispersion of carbon nanotubes 131.

[0058] Step 200.4: Heat the filament to solidify the carbon nanomaterials 33 on the surface of the filament, forming a prepreg filament 31.

[0059] The filaments from the flocking box 130 enter the heating box 140, which has multiple heating tubes. The heating tubes dry and solidify the material on the surface of the filaments to form pre-impregnated filaments 31, which are then drawn to the first winding assembly 15 to form a coil.

[0060] Step 201: The prepreg filament 31 is re-impregnated with a thermoplastic polymer to form a composite filament 32.

[0061] The coiled prepreg filament 31 is transferred to the second unwinding assembly 16 for rewinding, allowing it to be re-impregnated. See details... Figure 3 As shown, step 201.1 is as follows: after the prepreg filament 31 is unwound, the prepreg filament 31 is melt-impregnated with a thermoplastic polymer.

[0062] The raw materials used for melt impregnation are thermoplastic polymers, including any one of polyamide, thermoplastic polyurethane, polyetherimide, polyphenylene sulfide, and polyaryletherketone.

[0063] After being unwound, the prepreg filament 31 is drawn into the melt impregnation tank 170, which is filled with a thermoplastic polymer matrix 34 for coating the surface of the prepreg filament 31 with the thermoplastic polymer.

[0064] A second roller 171 is provided inside the melt impregnation tank 170 and on the column to convey the prepreg filament 31. The tension of the prepreg filament 31 can be controlled by adjusting the relative height of the second roller 171. The second roller 171 can be heated from 30℃ to 200℃.

[0065] In addition, the melt impregnation tank 170 also has an ultrasonic device 172, which eliminates the pores between the prepreg filament 31 and the thermoplastic polymer to improve the wetting degree of the prepreg filament 31.

[0066] The melt impregnation tank 170 also has a single screw extruder 173 on one side, which converts thermoplastic resin particles into molten fluid through three-stage heating to replenish thermoplastic polymer raw materials to the melt impregnation tank 170.

[0067] Step 201.2: Perform hot desizing on the melt-impregnated filament to remove excess slurry from the surface of the filament and pre-cur the thermoplastic polymer on the surface of the filament by heating.

[0068] The hot desizing treatment of the melt-impregnated filament can be referred to the desizing treatment of the pre-impregnated filament 31 mentioned above, and will not be repeated here.

[0069] Step 201.3: The pre-cured filaments are subjected to multi-stage cooling and shaping to form composite filaments 32.

[0070] The pre-cured filament enters a cooling and shaping box, which contains multiple sections of third pressure rollers 191. Two third pressure rollers 191 form a section, with a gap between them allowing the filament to pass through. Simultaneously, heating elements 192 are installed on the outer side of each third pressure roller 191 to heat the filament, thereby improving the surface smoothness, dimensional uniformity, and crystallinity of the composite filament 32, ultimately resulting in... Figure 4The composite filament 32 shown.

[0071] Finally, the composite filament 32 is wound into a coil. By adjusting the winding angle of the composite filament 32, constant tension and stable winding are achieved.

[0072] Therefore, the method for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this application embodiment achieves uniform coating of slurry through a thermal desizing process during the pre-impregnation stage of the original filament 30, and evaporates part of the solvent in the slurry, giving the filament a certain degree of viscosity. Carbon nanomaterials 33 (short fibers) are uniformly implanted onto the surface of the filament coated with sizing agent through an electrostatic flocking process. Then, the pre-impregnated filament 31 is composited with the thermoplastic polymer matrix 34 through a melt impregnation process, achieving controllable dispersion of carbon nanomaterials 33 and avoiding internal defects in the composite filament 32. On the one hand, this effectively solves the problems of easy agglomeration of carbon nanomaterials 33 dispersed in the resin matrix and weak bonding with the matrix material during impregnation, enhancing the interlayer bonding performance of the 3D printed sample; on the other hand, it optimizes the dielectric loss performance of the composite filament 32 and enhances its electromagnetic heating characteristics, enabling the 3D printed component to achieve local temperature compensation through an external electromagnetic field, reducing warpage deformation of the sample.

[0073] Based on this, the present application also provides a preparation device for carbon nanotube-reinforced thermoplastic composite filaments, which is applied to the above-mentioned preparation method of carbon nanotube-reinforced thermoplastic composite filaments. The composite filament 32 of the present application can be prepared using this preparation device; specifically, it includes: a pre-impregnation device for forming pre-impregnated filament 31, and a melt impregnation device for forming composite filament 32.

[0074] The pre-impregnation device includes a first unwinding assembly 10, a sizing and impregnation assembly 11, a first thermal desizing assembly 12, an electrostatic flocking assembly 13, a heat curing assembly 14, and a first winding assembly 15 arranged in sequence. The raw filament 30 is coiled on the first unwinding assembly 10. After being unwound by the first unwinding assembly 10, it passes through the sizing and impregnation assembly 11, the first thermal desizing assembly 12, the electrostatic flocking assembly 13, and the heat curing assembly 14 in sequence, forming a coiled pre-impregnated filament 31 on the first winding assembly 15.

[0075] Specifically, the first unwinding assembly 10 and the first winding assembly 15 are both reels used to pull the filament for unwinding and winding.

[0076] like Figure 5 , Figure 6As shown, the sizing and impregnation assembly 11 includes an impregnation tank 110 and a first roller 111, the thermal desizing assembly includes a desizing tank 120 and a first pressure roller 121, the electrostatic flocking assembly 13 includes a flocking box 130 and a plurality of carbon nanotubes 131 disposed in the flocking box 130, and the heat curing assembly 14 includes a heating box 140 and a plurality of heating tubes disposed in the heating box 140.

[0077] After the raw filament 30 is unwound, it is pulled along the first roller 111 and the first pressure roller 121 in sequence, and then passes through the gaps between multiple carbon nanotubes 131 in the flocking box 130 and the gaps between multiple heating tubes in the heating box 140 to form the prepreg filament 31.

[0078] Two carbon nanotubes 131 are grouped together, and a gap is formed between the two carbon nanotubes 131. The filament can pass through the gap of multiple groups of carbon nanotubes 131 in sequence. After the flocking box 130 is powered on, the carbon nanotubes 131 become negatively charged. When they come close together, the carbon nanotubes 131 fly up onto the filament under the action of the high voltage electric field, thus completing the implantation of the carbon nanotubes 131.

[0079] The melt impregnation device includes a second unwinding assembly 16, a melt impregnation assembly 17, a second hot desizing assembly 18, a cooling and shaping assembly 19, and a second winding assembly 20 arranged in sequence. The pre-impregnated filament 31 is coiled on the second unwinding assembly 16. After being unwound by the second unwinding assembly 16, it passes through the melt impregnation assembly 17, the second hot desizing assembly 18, and the cooling and shaping assembly 19 in sequence, and then forms a coiled composite filament 32 on the second winding assembly 20.

[0080] Furthermore, such as Figure 7 , Figure 8 As shown, the melt impregnation assembly 17 includes a melt impregnation tank 170 and a second roller 171, the second hot desizing assembly 18 includes a desizing tank 120 and a second pressure roller 181, and the cooling and shaping assembly 19 includes multiple heating elements 192 and multiple third pressure rollers 191 disposed in the shaping box 190.

[0081] After the prepreg filament 31 is unwound, it is pulled sequentially along the second roller 171 and the second pressure roller 181, passing through the gap between the multiple heating elements 192 and the third pressure roller 191 to form the composite filament 32.

[0082] Figure 8 In the middle, two third pressure rollers 191 are connected in one section, and the filament passes through the gap between the two third pressure rollers 191. At the same time, heating elements 192 are provided on the outer side of each third pressure roller 191 to heat the filament passing through, which can improve the surface smoothness, dimensional uniformity and crystallinity of the composite filament 32.

[0083] In addition, an ultrasonic device 172 is provided in the melt impregnation tank 170 to ultrasonically treat the filaments passing through the melt impregnation tank 170, so as to eliminate the pores between the prepreg filaments 31 and the thermoplastic polymer and improve the wetting degree of the prepreg filaments 31.

[0084] A single-screw extruder 173 is also provided at one end of the melt impregnation tank 170 to convert thermoplastic resin particles into molten fluid, replenish thermoplastic polymer raw materials to the melt impregnation tank 170, and ensure that the prepreg filament 31 is fully melt impregnated.

[0085] In summary, the equipment and method for preparing carbon nanotube-reinforced thermoplastic composite filaments provided in this application, by introducing carbon nanotubes 131 into the continuous fiber-reinforced thermoplastic composite filament 32 for 3D printing, can improve the interlayer bonding performance of the printed sample, while also increasing the tensile strength, flexural strength, and impact resistance of the sample. Adjusting the content of carbon nanotubes 131 in the composite filament 32 allows for controllable adjustment of the dielectric loss properties of the composite filament 32, imparting electromagnetic heating characteristics to the printed sample. Local temperature compensation and secondary consolidation heat treatment can be performed on the sample during or after printing using microwave, radio frequency heating, or other methods to optimize interlayer bonding performance and improve warpage deformation.

[0086] This application employs an electrostatic flocking process to implant carbon nanotubes 131 onto the surface of prepreg filament 31. By adjusting the electrode voltage, electrode spacing, and carbon nanotube density of the carbon nanotubes 131, the implantation density of the carbon nanotubes 131 can be controllably adjusted, ensuring their uniform dispersion within the prepreg filament 31 and preventing agglomeration. Ultrasonic assistance is used during the prepreg and melt impregnation processes to efficiently eliminate internal pores in the composite filament 32, improving wettability between the fiber and the polymer matrix, thereby guaranteeing the overall performance of the composite filament 32.

[0087] The apparatus for preparing the carbon nanotube-reinforced thermoplastic composite filament has the same structure and beneficial effects as the method for preparing the carbon nanotube-reinforced thermoplastic composite filament in the foregoing embodiments. The structure and beneficial effects of the method for preparing the carbon nanotube-reinforced thermoplastic composite filament have been described in detail in the foregoing embodiments and will not be repeated here.

[0088] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for producing a carbon nanotube-reinforced thermoplastic composite filament, characterized by, The method comprises the following steps: pre-impregnating the raw filament to implant carbon nanomaterials on the surface of the raw filament to form a pre-impregnated filament; re-impregnating the pre-impregnated filament with thermoplastic polymer to form a composite filament; the pre-impregnating the raw filament to implant carbon nanomaterials on the surface of the raw filament to form a pre-impregnated filament comprises: after the raw filament is unwound, the raw filament is impregnated with a sizing agent; wherein the sizing agent comprises any one of polyamide acid, water-soluble polyimide, water-soluble polyamide, water-based polyurethane, sulfonated polyether ether ketone and epoxy resin; the sized filament is heat desized to remove excess sizing agent on the surface of the filament, and the sizing agent on the surface of the filament is pre-cured by heating; the pre-cured filament is subjected to electrostatic flocking treatment to implant the carbon nanomaterials on the surface of the filament; the filament is heated to cure the carbon nanomaterials on the surface of the filament to form the pre-impregnated filament.

2. The method for preparing carbon nanotube-reinforced thermoplastic composite filaments according to claim 1, characterized in that, the re-impregnating the pre-impregnated filament with thermoplastic polymer to form a composite filament comprises: after the pre-impregnated filament is unwound, the pre-impregnated filament is melt-impregnated with the thermoplastic polymer; wherein the thermoplastic polymer comprises polyamide, thermoplastic polyurethane, polyetherimide, polyphenylene sulfide, polyaryletherketone; the melt-impregnated filament is heat desized to remove excess sizing agent on the surface of the filament, and the thermoplastic polymer on the surface of the filament is pre-cured by heating; the pre-cured filament is subjected to multi-stage cooling and shaping to form the composite filament.

3. The method for preparing carbon nanotube-reinforced thermoplastic composite filaments according to claim 2, characterized in that, after the pre-impregnated filament is unwound, the pre-impregnated filament is melt-impregnated with the thermoplastic polymer, which comprises: the thermoplastic polymer is filled in a melt-impregnation tank, and the pre-impregnated filament passes through the melt-impregnation tank to coat the thermoplastic polymer on the surface of the pre-impregnated filament; an ultrasonic device is arranged in the melt-impregnation tank to eliminate pores between the pre-impregnated filament and the thermoplastic polymer.

4. The method for preparing carbon nanotube-reinforced thermoplastic composite filaments according to claim 2, characterized in that, after the pre-cured filament is subjected to multi-stage cooling and shaping to form the composite filament, the method further comprises: the composite filament is wound to adjust the winding angle of the composite filament to achieve constant tension stable winding.

5. An apparatus for producing a carbon nanotube-reinforced thermoplastic composite filament, which is used for the production method of the carbon nanotube-reinforced thermoplastic composite filament according to any one of claims 1 to 4, characterized by, The method comprises a pre-impregnation device for forming a pre-impregnated filament and a melt-impregnation device for forming a composite filament; the pre-impregnation device comprises a first unwinding assembly, a sizing and impregnation assembly, a first heat desizing assembly, an electrostatic flocking assembly, a heating and curing assembly and a first winding assembly arranged in sequence; the raw filament is wound on the first unwinding assembly, and after the raw filament is unwound through the first unwinding assembly, the raw filament passes through the sizing and impregnation assembly, the first heat desizing assembly, the electrostatic flocking assembly and the heating and curing assembly in sequence to form the pre-impregnated filament wound on the first winding assembly; The melting impregnation device comprises a second unwinding assembly, a melting impregnation assembly, a second hot desizing assembly, a cooling and shaping assembly and a second winding assembly arranged in sequence, the pre-impregnated wire is coiled on the second unwinding assembly, after unwinding through the second unwinding assembly, the wire passes through the melting impregnation assembly, the second hot desizing assembly and the cooling and shaping assembly in sequence, and the coiled composite wire is formed on the second winding assembly.

6. The apparatus for producing a carbon nanotube-reinforced thermoplastic composite wire according to claim 5, wherein The sizing impregnation assembly comprises an impregnation tank and a first roller, the hot desizing assembly comprises a desizing tank and a first compression roller, the electrostatic flocking assembly comprises a flocking box and a plurality of carbon nanotubes arranged in the flocking box, and the heating and curing assembly comprises a heating box and a plurality of heating pipes arranged in the heating box. After the raw wire is unwound, it is pulled along the first roller and the first compression roller in sequence, and then passes through the gap between the plurality of carbon nanotubes in the flocking box and the gap between the plurality of heating pipes in the heating box, thereby forming the pre-impregnated wire.

7. The apparatus for producing a carbon nanotube-reinforced thermoplastic composite wire according to claim 5, wherein The melting impregnation assembly comprises a melting impregnation tank and a second roller, the second hot desizing assembly comprises a desizing tank and a second compression roller, and the cooling and shaping assembly comprises a plurality of heating members and a third compression roller. After the pre-impregnated wire is unwound, it is pulled along the second roller and the second compression roller in sequence, and then passes through the gap between the plurality of heating members and the third compression roller, thereby forming the composite wire.

8. The apparatus for producing a carbon nanotube-reinforced thermoplastic composite wire according to claim 7, wherein The melting impregnation tank is also provided with an ultrasonic device for ultrasonic treatment of the wire passing through the melting impregnation tank.

9. The apparatus for producing a carbon nanotube-reinforced thermoplastic composite wire according to claim 7, wherein One end of the melting impregnation tank is also provided with a single-screw extruder for converting thermoplastic resin particles into a molten fluid to supplement the thermoplastic polymer raw material for the melting impregnation tank.

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