A wave-absorbing thermoplastic 3D printing material containing a conductive polymer and a preparation method thereof

Abstract

The present application relates to the technical field of additive manufacturing, in particular to a kind of wave-absorbing thermoplastic 3D printing material containing conductive polymer and preparation method thereof, comprising the following components by weight: 0.5-20% of conductive polymer, 0.1-30% of wave-absorbing agent, 50-90% of thermoplastic resin, 0.1-20% of dispersant and 0.1-20% of filler.The purpose of the wave-absorbing thermoplastic 3D printing material containing conductive polymer and preparation method thereof is to solve the problem of poor compatibility between wave-absorbing agent and resin matrix.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, specifically to a microwave-absorbing thermoplastic 3D printing material containing a conductive polymer and its preparation method. Background Technology

[0002] Fused deposition modeling (FDM) has become a new method and means for processing thermoplastic materials due to its low cost, rapid manufacturing, and ability to prepare special structures. To prevent electromagnetic interference, additive manufacturing using absorbing filaments is widely used. These filaments typically contain magnetic loss absorbing agents, such as iron-cobalt-nickel metal powder and its oxide powder, or electrical loss absorbing agents, such as carbon nanotubes and carbon black. The absorbing filaments are obtained by blending the absorbing agent with a resin matrix.

[0003] Chinese patent document CN117343514A discloses a thermoplastic resin filament containing magnetic and electrical loss absorbing agents and its preparation method. Since the absorbing agent is a metal or inorganic material, it has poor compatibility with thermoplastic resin, making it difficult to mix evenly. It also causes a decrease in the toughness of the filament, increases the printing difficulty, and results in poor mechanical properties of 3D printed products made using this material.

[0004] Therefore, the inventors provide a microwave-absorbing thermoplastic 3D printing material containing a conductive polymer and its preparation method. Summary of the Invention

[0005] (1) Technical problems to be solved This invention provides a microwave-absorbing thermoplastic 3D printing material containing a conductive polymer and its preparation method, which solves the technical problem of poor compatibility between the microwave absorber and the resin matrix.

[0006] (2) Technical solution The present invention provides a microwave-absorbing thermoplastic 3D printing material containing a conductive polymer, comprising the following components by weight: 0.5-20% conductive polymer, 0.1-30% microwave absorber, 50-90% thermoplastic resin, 0.1-20% dispersant and 0.1-20% filler.

[0007] Furthermore, the conductive polymer includes polyacetylene, polyaniline, polypyrrole, poly(p-phenylene), polythiophene, polypyridine, and polyphenylene oxide.

[0008] Furthermore, the absorbing agent includes a magnetic loss absorbing agent and an electrical loss absorbing agent.

[0009] Furthermore, the magnetic loss absorbing agent includes iron powder, nickel powder, cobalt powder, ferrite, and carbonyl iron, while the electrical loss absorbing agent includes elemental carbon with a molecular structure and a conductive ceramic compound.

[0010] Furthermore, the thermoplastic resin includes polylactic acid, polycarbonate, ABS resin, nylon, polyetheretherketone, polyetherketoneketone, polyaryletherketone, polyetherimide, and thermoplastic polyimide.

[0011] Furthermore, the dispersant includes stearic acid, long-chain fatty acids, polysiloxanes, high molecular weight silicones, oxidized polyethylene wax, siloxane coupling agents, titanate coupling agents, and cage-like polyhedral oligomeric silsesquioxanes.

[0012] Furthermore, the filler includes continuous or chopped fibers, organic fibers, inorganic fibers, metal wires, ceramic particles, and powders.

[0013] The present invention also provides a method for preparing the above-mentioned microwave-absorbing thermoplastic 3D printing material containing conductive polymer, comprising the following steps: A composite mixture is obtained by mixing a conductive polymer and a microwave absorbing agent. The composite mixture, thermoplastic resin, and filler are fed into a twin-screw extruder through a hopper in a set ratio and heated to the molten state of the thermoplastic resin and mixed to obtain a molten mixture. The molten mixture is drawn into filaments from a die using a traction device.

[0014] Furthermore, the diameter of the exit end of the die is 2-6 mm.

[0015] Furthermore, the diameter of the filament is 0.5–2 mm.

[0016] (3) Beneficial effects In summary, this invention utilizes electropolymers as carbon-based polymer macromolecules, which, when mixed with microwave absorbers, improve compatibility with thermoplastic resin matrices and suppress the embrittlement effect of heterogeneous microwave absorber materials. This improves the process applicability of filaments or particles, increases the printing success rate, and enhances the mechanical properties of the printed material. Furthermore, the conductive polymer's molecular structure differs significantly from the thermoplastic resin matrix. For semi-crystalline resin matrices, adding conductive polymers helps control crystallization during the printing process. As a different structure, it hinders the orderly arrangement of resin matrix molecules, improving the crystallization rate and crystallinity during additive manufacturing, and enhancing the interlayer and interfilament bonding forces after filament or particle printing, thereby improving the overall mechanical properties of the printed material. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of a method for preparing a microwave-absorbing thermoplastic 3D printing material containing a conductive polymer, provided in an embodiment of the present invention. Detailed Implementation

[0019] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] A first aspect of the present invention provides a microwave-absorbing thermoplastic 3D printing material containing a conductive polymer, comprising the following components by weight: 0.5-20% conductive polymer, 0.1-30% microwave absorber, 50-90% thermoplastic resin, 0.1-20% dispersant and 0.1-20% filler.

[0022] In the above embodiments, the conductive polymers include, but are not limited to, polyacetylene, polyaniline, polypyrrole, poly(p-phenylene), polythiophene, polypyridine, and polyphenylene oxide. The microwave absorbing agents include magnetic loss absorbing agents and electrical loss absorbing agents. Magnetic loss absorbing agents include iron powder, nickel powder, cobalt powder, ferrite, and iron carbonyl. Electrical loss absorbing agents include elemental carbon with various molecular structures and conductive ceramic compounds, mainly including various elemental carbon with various molecular structures such as carbon powder, carbon black, carbon nanotubes, carbon fibers, graphite, and graphene; conductive ceramic compounds such as silicon carbide; various two-dimensional molecular structures with microwave absorbing properties such as MXene; various metal powders; and various ceramic materials with dielectric polarization relaxation loss, such as barium iron titanate. Thermoplastic resins include, but are not limited to, polylactic acid, polycarbonate, ABS resin, nylon, polyetheretherketone, polyetherketoneketone, polyaryletherketone, polyetherimide, and thermoplastic polyimide. Dispersants include, but are not limited to, stearic acid, long-chain fatty acids, polysiloxanes, high molecular weight silicones, oxidized polyethylene wax, siloxane coupling agents, titanate coupling agents, and cage-like polyhedral oligomeric silsesquioxanes.

[0023] As a carbon-based polymer macromolecule, conductive polymers, when mixed with microwave absorbers, improve their compatibility with thermoplastic resin matrices, suppress the embrittlement effect of heterogeneous microwave absorber materials on materials, and are beneficial to improving the process applicability of filaments or granules, thereby increasing the printing success rate of filaments or granules and the mechanical properties after printing.

[0024] The molecular structure of conductive polymers differs significantly from that of thermoplastic resin matrices. For semi-crystalline resin matrices, the addition of conductive polymers helps control the crystallization of the material during the printing process. As a different structure, it hinders the orderly arrangement of the resin matrix molecular structure, improves the crystallization rate and crystallinity during the additive manufacturing process, and enhances the interlayer and interfilament bonding force after the filament or particle printing, thereby improving the overall mechanical properties of the material after printing.

[0025] As an optional implementation, the filler includes, but is not limited to, continuous or chopped fibers, organic fibers, inorganic fibers, metal wires, ceramic particles and powders, including carbon fibers, glass fibers, quartz fibers, mullite fibers, basalt fibers, lignin fibers, natural fibers, carbon nanotube fibers, ceramic fibers, boron fibers, aramid fibers, Kevlar fibers, ultra-high molecular weight polyethylene fibers, liquid crystal polymers (LCP), optical fibers, polyaryletherketone fibers, nylon fibers, polyimide fibers, etc. Fillers can also be ceramic particles or powders, such as polymer powders, polytetrafluoroethylene powder, liquid crystal polymer powders, glass microspheres, ceramic microspheres, alumina (carborundum), zinc oxide, titanium dioxide, mullite, calcium carbonate, magnesium carbonate, calcium silicate, aluminum silicate, magnesium silicate, potassium aluminum silicate, barium sulfate, silicon carbide, silicon nitride, boron nitride, silicon dioxide, whiskers, zirconium dioxide, yttrium dioxide, tungsten sulfide, adamantane, montmorillonite, nano-silver, cage-like polyhedral oligomeric silsesquioxane (POSS), copper chromium black, copper hydroxyphosphate, pigments, etc. Added fillers improve material properties or provide certain functions, such as processability, mechanical properties, thermal conductivity, dielectric properties, heat resistance, phase change energy storage, flame retardancy, ablation resistance, color control, radiation resistance, barrier properties, tribological properties, biological properties, optical properties, and laser marking capability. Fillers can be in various states, such as fibers, particles, powders, and flakes.

[0026] A second aspect of this invention provides a method for preparing a microwave-absorbing thermoplastic 3D printing material containing a conductive polymer, see [link to relevant documentation]. Figure 1 The method may include the following steps: S100. The conductive polymer and the microwave absorbing agent are mixed to obtain a composite mixture.

[0027] Specifically, methods such as physical blending and in-situ polymerization coating can be employed. For example, physical blending involves mixing two powdered materials in a specific ratio using a high-speed mixer and crusher, followed by stirring; grinding the two powdered materials in a specific ratio using a ball mill; preparing conductive polymer solutions or emulsions using liquid-phase assisted coating mixing, and blending them with the microwave absorber to prepare microwave absorber microspheres coated with conductive polymers; blowing conductive polymer micropowder onto the surface of the microwave absorber using a fluidization method with a gas-phase carrier; and spraying conductive polymer powder onto the surface of the microwave absorber using an electrostatic spraying method. For example, in-situ polymerization coating involves preparing a solution or emulsion of the conductive polymer monomer or prepolymer, adding solid-phase microwave absorber powder, and stirring until homogeneous. A catalyst is added to control polymerization and generate a conductive polymer, which is then in-situ coated onto the surface of the microwave absorber. Preferably, the catalyst and solid-phase microwave absorber are combined and directly added to initiate a chemical reaction between the monomer or prepolymer to generate a conductive polymer that coats the surface of the microwave absorber.

[0028] S200: The composite mixture, thermoplastic resin, and filler are fed into a twin-screw extruder through a hopper in a set ratio, heated to the molten state of the thermoplastic resin, and mixed to obtain a molten mixture.

[0029] Specifically, depending on the different properties of different materials, multiple feeding or main feeding combined with side feeding is often used to enhance the dispersion and mixing of materials.

[0030] S300: The molten mixture is drawn from the die into filaments using a traction device.

[0031] Specifically, the exit diameter of the die is 2 to 6 mm. By controlling the screw speed and traction rate, long filaments with a diameter of 0.5 to 2 mm are formed. The long filaments can be used directly as additive manufacturing raw materials, or mechanically cut and granulated. The granules can be used directly as raw materials for melt deposition modeling additive manufacturing, or further processed into long filaments through a single screw extruder and traction and winding equipment.

[0032] Example 1 The preparation method of this microwave-absorbing thermoplastic 3D printing material containing conductive polymer specifically includes: Step 1: Grind 10 parts of conductive polymer polypyrrole (PPy), 10 parts of carbonyl iron powder microwave absorber, and 5 parts of POSS dispersant together in a ball mill for 1 hour. After mixing evenly, take out the composite mixture.

[0033] Step 2: Premix 100 parts of polyetheretherketone (PEEK) powder with a melt index of 20 g / 10 min at 380℃ / 5 kg and the composite mixture prepared in Step 1 in a high-speed mixer.

[0034] Step 3: Dry the mixed powder in a 150℃ oven for 5 hours, feed it into the hopper of a twin-screw extruder, add 10 parts of chopped carbon fiber into the side feed port, and set the extrusion temperature to 300℃ for the front section, 360℃ for the middle and rear sections, and 370℃ for the die head. After extrusion, pelletize the product.

[0035] Step 4: Feed the granules prepared in Step 3 into a single screw extruder, and use a traction device and a winding device to prepare additive manufacturing filaments with a diameter of 1.75 mm, and then coil them into filament rolls.

[0036] The material was printed using an FDM printer with a nozzle temperature of 420℃, a cavity temperature of 230℃, a fan temperature of 0%, unidirectional 100% filling, and a printing speed of 30mm / s.

[0037] After printing, the mechanical properties of the material in different printing directions were measured. The tensile strength along the filament filling direction (X direction) was 80 MPa, the tensile strength between filaments (Y direction) was 60 MPa, and the tensile strength between layers (Z direction) was 50 MPa. Compared with traditional microwave absorbing PEEK printing, the mechanical properties are improved by more than 50%.

[0038] Example 2 The preparation method of this microwave-absorbing thermoplastic 3D printing material containing conductive polymer specifically includes: Step 1: Prepare a micelle suspension by complexing and dispersing 20 parts of the conductive polymer polythiophene:polysulfonated styrene (PEDOT:PSS) in water. Add 30 parts of microwave absorbing ultrafine iron powder to the suspension and stir thoroughly for 3 hours. Remove the solvent water by vacuum distillation, then evaporate at room temperature for 10 hours, and finally dry in an oven at 70°C for 3 hours to prepare the composite mixture.

[0039] Step 2: Feed 100 parts of polyetherketoneketone (PEKK) powder with a melt index of 10 g / 10 min at 380℃ / 5 kg and the composite mixture prepared in step 1 into the hopper of a twin-screw extruder. Add 20 parts of chopped glass fiber into the side feed port. The extrusion temperature is 280℃ for the front section, 350℃ for the middle and rear sections, and 370℃ for the die head. After extrusion, pelletize the product.

[0040] Step 3: Feed the granules prepared in Step 2 into a single screw extruder, and use traction equipment and filament winding equipment to prepare additive manufacturing filaments with a diameter of 1.75 mm, and coil them into filament rolls.

[0041] The material was printed using an FDM printer with a nozzle temperature of 420℃, a cavity temperature of 120℃, a fan speed of 50%, and a printing speed of 100mm / s.

[0042] After printing, the mechanical properties of the material in different printing directions were measured. The tensile strength along the filament filling direction (X direction) was 70 MPa, the tensile strength between filaments (Y direction) was 60 MPa, and the tensile strength between layers (Z direction) was 60 MPa. Compared with traditional microwave absorbing PEKK printing, the mechanical properties are improved by more than 20%.

[0043] Example 3 The preparation method of this microwave-absorbing thermoplastic 3D printing material containing conductive polymer specifically includes: Step 1: Wash and dry 5 parts of carbon nanotubes (CNTs) and 2 parts of silane coupling agent with anhydrous ethanol, then add them to distilled water and stir thoroughly until evenly dispersed. Add 20 parts of aniline (AN) monomer, stir thoroughly, maintain heating in an ice-water bath at 10°C, and slowly add 1 part of ammonium persulfate (APS). After the addition is complete, keep stirring and react for 3 hours. Filter the reaction product under reduced pressure, wash repeatedly with anhydrous ethanol until the washing solution is colorless and transparent, then dry at 60°C for 24 hours to prepare the composite mixture.

[0044] Step 2: 100 parts of nylon (PA) powder with a melt index of 5 g / 10 min at 230℃ / 5 kg and the composite mixture prepared in step 1 are fed into the hopper of a twin-screw extruder. The extrusion temperature is 200℃ at the front section, 220℃ at the middle and rear sections, and 230℃ at the die head. After extrusion, the mixture is pelletized.

[0045] Step 3: Feed the granules prepared in Step 2 into a single screw extruder, and use traction equipment and filament winding equipment to prepare additive manufacturing filaments with a diameter of 1.75 mm, and coil them into filament rolls.

[0046] The material was printed using an FDM printer with a nozzle temperature of 250°C, a cavity temperature of 60°C, a fan speed of 20%, and a printing speed of 40 mm / s.

[0047] After printing, the mechanical properties of the material in different printing directions were measured. The tensile strength along the filament filling direction (X direction) was 60 MPa, the tensile strength between filaments (Y direction) was 40 MPa, and the tensile strength between layers (Z direction) was 30 MPa. Compared with traditional microwave absorbing PA printing, the mechanical properties were improved by more than 35%.

[0048] Comparative Example 1 Step 1: Feed 30 parts of microwave absorbing agent ultrafine iron powder and 100 parts of polyether ether ketone (PEEK) powder with a melt index of 10g / 10min at 380℃ / 5kg into the hopper of a twin-screw extruder. The extrusion temperature is 280℃ in the front section, 350℃ in the middle and rear sections, and 380℃ at the die head. After extrusion, the material is granulated.

[0049] Step 2: Feed the granules prepared in Step 1 into a single screw extruder, and use traction equipment and filament winding equipment to prepare additive manufacturing filaments with a diameter of 1.75 mm, and coil them into filament rolls.

[0050] The material was printed using an FDM printer with a nozzle temperature of 420℃, a cavity temperature of 120℃, a fan speed of 50%, and a printing speed of 100mm / s.

[0051] After printing, the mechanical properties of the material in different printing directions were measured. The tensile strength along the filament filling direction (X direction) was 50 MPa, the tensile strength in the interfilament direction (Y direction) was 30 MPa, and the tensile strength in the interlayer direction (Z direction) was 10 MPa.

[0052] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0053] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A microwave-absorbing thermoplastic 3D printing material containing a conductive polymer, characterized in that, Includes the following components by weight: 0.5–20% conductive polymer, 0.1–30% microwave absorber, 50–90% thermoplastic resin, 0.1–20% dispersant and 0.1–20% filler.

2. The microwave-absorbing thermoplastic 3D printing material containing a conductive polymer according to claim 1, characterized in that, The conductive polymers include polyacetylene, polyaniline, polypyrrole, poly(p-phenylene), polythiophene, polypyridine, and polyphenylene oxide.

3. The microwave-absorbing thermoplastic 3D printing material containing a conductive polymer according to claim 1, characterized in that, The microwave absorbing agent includes magnetic loss microwave absorbing agent and electrical loss microwave absorbing agent.

4. The microwave-absorbing thermoplastic 3D printing material containing a conductive polymer according to claim 3, characterized in that, The magnetic loss absorbing agent includes iron powder, nickel powder, cobalt powder, ferrite, and carbonyl iron, while the electrical loss absorbing agent includes elemental carbon with a molecular structure and conductive ceramic compounds.

5. The microwave-absorbing thermoplastic 3D printing material containing a conductive polymer according to claim 1, characterized in that, The thermoplastic resins include polylactic acid, polycarbonate, ABS resin, nylon, polyetheretherketone, polyetherketoneketone, polyaryletherketone, polyetherimide, and thermoplastic polyimide.

6. The microwave-absorbing thermoplastic 3D printing material containing a conductive polymer according to claim 1, characterized in that, The dispersants include, but are not limited to, stearic acid, long-chain fatty acids, polysiloxanes, high molecular weight silicones, oxidized polyethylene wax, siloxane coupling agents, titanate coupling agents, and cage-like polyhedral oligomeric silsesquioxanes.

7. The microwave-absorbing thermoplastic 3D printing material containing a conductive polymer according to claim 1, characterized in that, The filler includes continuous or chopped fibers, organic fibers, inorganic fibers, metal wires, ceramic particles, and powders.

8. A method for preparing a microwave-absorbing thermoplastic 3D printing material containing a conductive polymer as described in claim 1, characterized in that, The method includes the following steps: A composite mixture is obtained by mixing a conductive polymer and a microwave absorbing agent. The composite mixture, thermoplastic resin, and filler are fed into a twin-screw extruder through a hopper in a set ratio and heated to the molten state of the thermoplastic resin and mixed to obtain a molten mixture. The molten mixture is drawn into filaments from a die using a traction device.

9. The method for preparing the microwave-absorbing thermoplastic 3D printing material containing a conductive polymer according to claim 1, characterized in that, The diameter of the exit end of the die is 2-6 mm.

10. The method for preparing the microwave-absorbing thermoplastic 3D printing material containing a conductive polymer according to claim 1, characterized in that, The diameter of the filament is 0.5 to 2 mm.

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