Fiber-reinforced wave-absorbing tube
By introducing high-density polyethylene and boron-doped SiC nanofibers into PE pipes, the dielectric polarization loss and conductivity loss are synergistically combined to form a continuous three-dimensional conductive network, which solves the shielding problem of PE pipes in complex electromagnetic environments and achieves efficient electromagnetic wave absorption and improved mechanical properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ERA CO LTD
- Filing Date
- 2026-04-30
- Publication Date
- 2026-06-05
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to a fiber-reinforced microwave absorbing tube, belonging to the field of pipe material technology. Background Technology
[0002] PE (polyethylene) pipes are widely used in municipal water supply and drainage, chemical transportation, communication cabling, and special electromagnetic protection applications due to their excellent corrosion resistance, long service life, and good toughness. Existing pipes include composite pipes formed by three-layer co-extrusion, such as the composite pipe disclosed in Chinese Patent (Authorization Announcement No.: 2859158Y), which includes an inner polyethylene layer, an outer polyethylene layer, and a fiber-reinforced polyethylene intermediate layer. However, whether single-layer or multi-layered, traditional PE pipes typically only provide basic structural transportation functions, lacking active protection capabilities, especially in complex electromagnetic environments. Furthermore, when used as communication cable protection pipes, underground pipelines, or military-grade pipelines, they are susceptible to external electromagnetic interference, radar detection reflections, and strong electromagnetic pulse impacts, affecting the stability and safety of the system.
[0003] To address the aforementioned electromagnetic interference issues, current technologies attempt to improve the electromagnetic performance of pipelines by introducing metallic fillers or conductive polymer materials. For example, conductive fillers such as metal powder and carbon black are blended with the PE matrix to achieve electromagnetic shielding. However, such solutions have significant limitations in engineering applications: First, metallic fillers are prone to corrosion and have high density, increasing pipeline weight and limiting long-term outdoor use; second, traditional shielding materials primarily rely on "reflective shielding," easily generating secondary electromagnetic reflection interference and exhibiting poor compatibility in precise electromagnetic environments; third, high-content metallic fillers severely compromise the toughness and processability of the PE matrix. Therefore, current electromagnetic shielding technologies struggle to balance structural strength and functional requirements.
[0004] Silicon carbide (SiC) fiber materials possess high strength, excellent chemical stability, high temperature resistance, acid and alkali corrosion resistance, and good dielectric loss characteristics, making them an ideal high-performance reinforcing and functional filler. In recent years, although studies have found that SiC fibers can effectively absorb and attenuate electromagnetic waves through mechanisms such as dielectric polarization loss and conductivity loss, possessing great potential as a wave-absorbing functional phase, the current application of silicon carbide in pipe materials is usually only as a filler or thermal insulation material. For example, a high-temperature resistant polyethylene pipe disclosed in existing patent literature (publication number: CN115073835A) adds silicon carbide powder material to the polyethylene resin matrix material, mainly to improve the high-temperature resistance of the pipe. Another example is the polyethylene underfloor heating pipe disclosed in patent literature (authorization announcement number: CN116063768B), which uses silicon carbide whiskers as a high thermal conductivity reinforcing filler. Essentially, this utilizes the thermal conductivity of silicon carbide whiskers, which is also equivalent to using it as a filler. There is no related technology for applying silicon carbide fibers as electromagnetic shielding materials to pipe materials, nor is there any disclosure on how to achieve the required electromagnetic shielding capability. Furthermore, directly applying unmodified pure SiC fiber materials to pipe materials results in insufficient electromagnetic shielding performance, failing to meet the required electromagnetic shielding requirements. Summary of the Invention
[0005] To address the problems existing in the prior art, this invention provides a fiber-reinforced microwave absorbing tube, which solves the problem of how to improve the electromagnetic shielding performance of the tube.
[0006] The objective of this invention is achieved through the following technical solution: a fiber-reinforced microwave absorbing tube, comprising an outer layer, a middle microwave-absorbing functional layer, and an inner layer, wherein the middle microwave-absorbing functional layer is located between the outer layer and the inner layer, and the middle microwave-absorbing functional layer comprises the following components by mass percentage:
[0007] High-density polyethylene: 70%–85%; boron-doped SiC nanofibers: 10%–28%; silane coupling agent: 0.1%–1.5%; antioxidant: 0.15%–0.3%; dispersant: 0.2%–0.5%.
[0008] By incorporating a high content of boron-doped silicon carbide nanofibers into the intermediate absorbing functional layer, the synergistic effect of the dielectric polarization loss and conductivity loss of the boron-doped silicon carbide nanofibers achieves effective absorption and attenuation of electromagnetic waves in the 2–18 GHz frequency band, ensuring the pipe's reflection loss. The effective absorption bandwidth for electromagnetic waves is ≥7 GHz, meeting electromagnetic protection and anti-interference requirements. Simultaneously, the silicon carbide fibers also provide a certain degree of reinforcement, better guaranteeing the overall mechanical properties of the pipe. More specifically, compared to using pure silicon carbide fibers, this invention, through boron doping, increases the "heterogeneous interface polarization loss" mechanism, namely SiC / free carbon and SiC / SiC...x O γ SiC x O γ The heterogeneous interface polarization loss of free carbon and other multi-interfaces minimizes the reflection loss (RL) of the pipe in the 8–18 GHz (Ku band). min The absorption capacity reaches -45dB to -60dB, with an effective absorption bandwidth (RL≤-10dB) ≥7GHz electromagnetic wave band, capable of completely covering Ku-band electromagnetic waves. Its absorption performance far surpasses that of existing pure SiC absorbing materials (current RL...). min With a strength ≥-30dB and bandwidth ≤5GHz, this invention achieves excellent electromagnetic shielding with low electromagnetic wave reflection loss. Primarily relying on absorption and attenuation, it effectively avoids secondary electromagnetic reflection interference caused by existing methods using metal fillers. This allows the pipe to be better suited for applications with high electromagnetic compatibility requirements, such as precision computer rooms and military shelters. Furthermore, the use of boron-doped silicon carbide nanofibers effectively avoids the high resistivity and limited polarization defects of the pipe's intermediate layer. Simultaneously, by adding boron-doped silicon carbide fibers to the intermediate layer to provide electromagnetic shielding, the design effectively places the absorbing material between the inner and outer layers, preventing external environmental influences on the absorbing material's performance and better protecting the electromagnetic shielding performance.
[0009] In the aforementioned fiber-reinforced microwave absorbing tube, preferably, the diameter of the boron-doped SiC nanofibers is 50–100 nm, and the length of the boron-doped SiC nanofibers is 4 μm–15 μm. This better facilitates the formation of a continuous three-dimensional conductive network in the intermediate layer, significantly increasing the number of dielectric polarization centers and enhancing the synergistic effect of dielectric polarization loss and conductivity loss. More specifically, by employing the aforementioned aspect ratio, the surge in melt viscosity caused by excessively long fibers can be better avoided, preventing problems such as fiber breakage and agglomeration during extrusion. As a further preferred embodiment, the aspect ratio of the boron-doped SiC nanofibers is 80–150. An aspect ratio above 80 prevents the fibers from being too short to form a continuous conductive network, thereby achieving excellent microwave absorption (electromagnetic shielding) performance. On the other hand, by controlling the aspect ratio of boron-doped SiC nanofibers, the "one-dimensional reinforcement" effect can be fully utilized to form a good interfacial bond with the PE matrix, thereby increasing the ring stiffness of the pipe by 15% to 25% and the tensile strength by 10% to 20%, thus solving the problem of the contradiction between "improved wave absorption performance and decreased mechanical properties" in wave-absorbing pipes.
[0010] In the aforementioned fiber-reinforced microwave absorbing tube, preferably, the boron-doped SiC nanofibers are mainly produced by electrospinning from the following raw material ratios by weight:
[0011] The mass ratio of boric acid:polyvinylpyrrolidone:polycarbosilane is 3:10-12:20-22.
[0012] By using the above-mentioned raw material ratio as a precursor and electrospinning, boron-doped SiC nanofibers can be effectively produced. By using boron raw materials with the above-mentioned content, the obtained boron-doped SiC nanofibers can better improve their effective absorption bandwidth (RL≤-10dB) ≥7GHz compared with pure SiC nanofibers, which can basically completely cover the Ku band and the absorption performance far exceeds that of existing pure SiC absorbing materials.
[0013] In the aforementioned fiber-reinforced microwave absorbing tube, preferably, the thickness of the intermediate microwave absorbing functional layer accounts for 38% to 48% of the total wall thickness of the tube. This allows the electromagnetic shielding function of the intermediate microwave absorbing functional layer to play a better role, enabling better absorption and attenuation of electromagnetic waves in the 2–18 GHz frequency band through the synergistic effect of the dielectric polarization loss and conductivity loss of boron-doped SiC nanofibers. This ensures an effective absorption bandwidth of ≥7 GHz with a reflection loss ≤-10 dB, meeting the requirements for electromagnetic protection and anti-interference. At the same time, the thickness percentage can be enhanced by the reinforcing effect of boron-doped SiC nanofibers, improving the overall mechanical properties of the tube.
[0014] In the aforementioned fiber-reinforced microwave absorbing tube, preferably, the dispersant in the intermediate microwave absorbing functional layer is selected from one or more of EVA wax, stearic acid derivatives, and polymeric dispersants. This promotes the uniform dispersion of boron-doped SiC nanofibers in the PE melt, which is more conducive to the formation of a stable dielectric loss network.
[0015] In the aforementioned fiber-reinforced microwave absorbing tube, preferably, the silane coupling agent in the intermediate microwave absorbing functional layer is selected from KH-550 or KH-570; and the antioxidant is selected from one or more of antioxidant 1010, antioxidant 168 and antioxidant 1030.
[0016] In the aforementioned fiber-reinforced microwave absorbing tube, preferably, the outer layer comprises the following components by mass percentage:
[0017] High-density polyethylene: 94%–98%; UV stabilizer: 2.0%–5.0%; antioxidant: 0.2%–0.5%; processing aids: 0.1%–0.5%.
[0018] This design better ensures the overall ring stiffness and mechanical strength of the pipe. Through the synergistic effect of UV stabilizers and antioxidants, it achieves UV shielding and anti-photoaging functions. Simultaneously, the processing aids enhance the surface gloss of the pipe. As a further preferred option, the UV stabilizer in the outer layer can be selected from carbon black, such as carbon black N330 or carbon black N550, with a particle size of 20nm to 50nm; the antioxidant can be selected from antioxidant 1010 or antioxidant 168, which can better inhibit the thermo-oxidative aging properties of the PE matrix; the processing aids are selected from polyethylene wax or oxidized polyethylene wax. In the aforementioned fiber-reinforced microwave absorbing pipe, preferably, the wall thickness of the outer layer accounts for 28% to 35% of the total pipe wall thickness.
[0019] In the aforementioned fiber-reinforced microwave absorbing tube, preferably, the inner layer comprises the following components by mass percentage:
[0020] High-density polyethylene: 96%–98.5%; antioxidant: 0.15%–0.3%; processing aid: 0.1%–0.2%; antistatic agent: 0.5%–1.0%; PTFE micro powder: 0.5%–1.0%.
[0021] The inner wall made from the above materials has a smooth finish, and the inner layer material contains an antistatic agent, which can effectively reduce the surface resistance of the inner layer to 10. 8 ~10 10 With an Ω / sq rating, when the conduit is used as an outer conduit for cables, it can effectively prevent static electricity from being generated during cable threading, thus avoiding interference with the electromagnetic environment. At the same time, the presence of the antistatic agent ensures that it will not interfere with the intermediate wave-absorbing layer.
[0022] In the aforementioned fiber-reinforced microwave absorbing tube, preferably, the inner layer's wall thickness accounts for 20% to 30% of the total tube wall thickness. This not only provides the advantage of a low-friction inner wall, facilitating cable threading or fluid transport, but more importantly, by laminating the aforementioned inner wall to the inside of the intermediate microwave absorbing layer, direct contact between the SiC fibers in the intermediate microwave absorbing functional layer and the transport medium can be prevented, thus better preventing exposed fibers from being scratched or contaminated and compromising their electromagnetic shielding performance.
[0023] In summary, compared with the prior art, the present invention has the following advantages:
[0024] 1. By leveraging the synergistic effect of dielectric polarization loss and conductivity loss of boron-doped SiC nanofibers, effective absorption and attenuation of electromagnetic waves in the 8–18 GHz frequency band are achieved, resulting in minimal reflection loss (RL) of the pipe material in the 8–18 GHz (Ku band). minThe reflectance reaches -45dB to -60dB, ensuring that the pipe reflection loss is ≤-10dB, while the effective absorption bandwidth of electromagnetic waves (RL≤-10dB) is ≥7GHz, meeting the requirements of electromagnetic protection and anti-interference. At the same time, the silicon carbide fiber can also play a certain role in reinforcement, better ensuring the overall mechanical properties of the pipe.
[0025] 2. By controlling the length and diameter of boron-doped SiC nanofibers, a continuous three-dimensional conductive network can be formed in the intermediate layer, which can significantly increase the number of dielectric polarization centers and enhance the synergistic effect of dielectric polarization loss and conductivity loss.
[0026] 3. By controlling the aspect ratio of boron-doped SiC nanofibers, the "one-dimensional reinforcement" effect can be fully utilized, and a good interfacial bond can be formed between them and the polyethylene (PE) matrix. This increases the ring stiffness of the pipe by 15% to 25% and the tensile strength by 10% to 20%, thus solving the problem of the contradiction between "improved microwave absorption performance and decreased mechanical properties" in microwave absorbing pipes.
[0027] 4. The ring stiffness of this fiber-reinforced pipe reaches 12 N / m. 2 The tensile strength reaches 20 MPa or above. Detailed Implementation
[0028] The technical solution of the present invention will be further described in detail below through specific embodiments, but the present invention is not limited to these embodiments.
[0029] Example 1
[0030] The fiber-reinforced microwave absorbing tube of this embodiment includes an outer layer, a middle microwave absorbing functional layer, and an inner layer. The middle microwave absorbing functional layer is located between the outer layer and the inner layer. More importantly, the middle microwave absorbing functional layer includes the following components by mass percentage:
[0031] High-density polyethylene: 80.2%; Boron-doped SiC nanofibers: 18.3%; Silane coupling agent: 1.0%; Antioxidant: 0.2%; Dispersant: 0.3%. The diameter of the boron-doped SiC nanofibers is 50nm-55nm, the length is 4.0μm-4.5μm, and the aspect ratio of the boron-doped SiC nanofibers is not less than 80; the silane coupling agent is KH-550, the dispersant is EVA wax, and the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.
[0032] The aforementioned boron-doped SiC nanofibers are mainly made from the following raw materials in parts by weight:
[0033] The mass ratio of boric acid:polyvinylpyrrolidone:polycarbosilane is 3:10:20. Specifically, boric acid is selected as the dopant. Boric acid, polyvinylpyrrolidone, and polycarbosilane are mixed in a mass ratio of 3:10:20 to prepare a precursor solution. After electrospinning and curing at 200℃ for 2 hours, boron-doped SiC nanofibers are prepared by high-temperature pyrolysis at 1200℃ for 3 hours.
[0034] The inner layer further comprises the following components by mass percentage:
[0035] Polyethylene: 98.1%; Antioxidant: 0.3%; Processing aid: 0.2%; Antistatic agent: 1%; PTFE micro powder: 0.4%. The antioxidant in the inner layer can also be antioxidant 1010, the processing aid is polyethylene wax, and the antistatic agent is HBS-204P.
[0036] The outer layer comprises the following mass percentages:
[0037] High-density polyethylene: 97%; UV stabilizer: 2.2%; Antioxidant 1010: 0.15%; Antioxidant 168: 0.25%; Processing aids: 0.4%. The UV stabilizer in the outer layer is carbon black N330, and the processing aid is polyethylene wax.
[0038] The thickness ratio of the outer layer, the middle wave-absorbing functional layer, and the inner layer of the aforementioned pipe to the pipe wall thickness is 30:42:28.
[0039] The aforementioned fiber-reinforced microwave absorbing tubes can be manufactured using mature three-layer co-extrusion technology.
[0040] Example 2
[0041] The fiber-reinforced microwave absorbing tube of this embodiment includes an outer layer, a middle microwave absorbing functional layer, and an inner layer. The middle microwave absorbing functional layer is located between the outer layer and the inner layer. More importantly, the middle microwave absorbing functional layer includes the following components by mass percentage:
[0042] High-density polyethylene: 81.5%; Boron-doped SiC nanofibers: 17.2%; Silane coupling agent: 1.0%; Antioxidant: 0.2%; Dispersant: 0.1%. The aspect ratio of the above boron-doped SiC nanofibers is not less than 100, and the diameter of the boron-doped SiC nanofibers is 60 nm to 65 nm, and the length is 6.0 μm to 7.0 μm; the above silane coupling agent is KH-550, the dispersant is EVA wax, and the antioxidant is antioxidant 1010; the above boron-doped SiC nanofibers are mainly made from the following raw materials in parts by weight:
[0043] The mass ratio of boric acid, polyvinylpyrrolidone, and polycarbosilane was 3:10:20. Specifically, boric acid was selected as the dopant. A precursor solution was prepared by mixing boric acid, polyvinylpyrrolidone, and polycarbosilane in a mass ratio of 3:10:20. After electrospinning and curing at 200°C for 2 hours, boron-doped SiC nanofibers were obtained by high-temperature pyrolysis at 1200°C for 3 hours.
[0044] The inner layer further comprises the following components by mass percentage:
[0045] Polyethylene: 98.4%; Antioxidant: 0.3%; Processing aid: 0.2%; Antistatic agent: 0.7%; PTFE micro powder: 0.4%. The antioxidant in the inner layer can also be antioxidant 1010, the processing aid is polyethylene wax, and the antistatic agent is HBS-204P.
[0046] The outer layer comprises the following mass percentages:
[0047] High-density polyethylene: 96.5%; UV stabilizer: 3.0%; antioxidant: 0.2%; processing aid: 0.3%. The UV stabilizer in the outer layer is carbon black N330, the antioxidant is antioxidant 1010, and the processing aid is polyethylene wax.
[0048] The thickness ratio of the outer layer, the middle wave-absorbing functional layer, and the inner layer of the aforementioned pipe to the pipe wall thickness is 32:40:28.
[0049] The aforementioned fiber-reinforced microwave absorbing tubes can be manufactured using mature three-layer co-extrusion technology.
[0050] Example 3
[0051] The fiber-reinforced microwave absorbing tube of this embodiment includes an outer layer, a middle microwave absorbing functional layer, and an inner layer. The middle microwave absorbing functional layer is located between the outer layer and the inner layer. More importantly, the middle microwave absorbing functional layer includes the following components by mass percentage:
[0052] High-density polyethylene: 80%; Boron-doped SiC nanofibers: 17.8%; Silane coupling agent: 1.5 wt%; Antioxidant: 0.2%; Dispersant: 0.5%. The aspect ratio of the above boron-doped SiC nanofibers is 85-90, and the diameter of the boron-doped SiC nanofibers is 50 nm-55 nm, and the length is 5.0 μm-5.5 μm; the above silane coupling agent is KH-550, the dispersant is EVA wax, and the antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2; the above boron-doped SiC nanofibers are mainly made from the following raw materials in parts by weight:
[0053] The mass ratio of boric acid, polyvinylpyrrolidone, and polycarbosilane was 3:10:20. Specifically, boric acid was selected as the dopant. A precursor solution was prepared by mixing boric acid, polyvinylpyrrolidone, and polycarbosilane in a mass ratio of 3:10:20. After electrospinning and curing at 200°C for 2 hours, boron-doped SiC nanofibers were obtained by high-temperature pyrolysis at 1200°C for 3 hours.
[0054] The inner layer further comprises the following components by mass percentage:
[0055] High-density polyethylene: 98.5%; antioxidant: 0.2%; processing aid: 0.1%; antistatic agent: 0.7%; PTFE micro powder: 0.5%. The antioxidant in the inner layer can also be antioxidant 1010, the processing aid is polyethylene wax, and the antistatic agent is HBS-204P.
[0056] The outer layer comprises the following mass percentages:
[0057] High-density polyethylene: 96.5%; UV stabilizer: 3.0%; antioxidant: 0.2%; processing aid: 0.3%. The UV stabilizer in the outer layer is carbon black N330, the antioxidant is antioxidant 1010, and the processing aid is polyethylene wax.
[0058] The thickness ratio of the outer layer, the middle wave-absorbing functional layer, and the inner layer of the aforementioned pipe to the pipe wall thickness is 30:40:30.
[0059] The aforementioned fiber-reinforced microwave absorbing tubes can be manufactured using mature three-layer co-extrusion technology.
[0060] Example 4
[0061] The fiber-reinforced microwave absorbing tube of this embodiment includes an outer layer, a middle microwave absorbing functional layer, and an inner layer. The middle microwave absorbing functional layer is located between the outer layer and the inner layer. More importantly, the middle microwave absorbing functional layer includes the following components by mass percentage:
[0062] High-density polyethylene: 75%; boron-doped SiC nanofibers: 23.5%; silane coupling agent: 1.0%; antioxidant: 0.2%; dispersant: 0.3%. The aspect ratio of the boron-doped SiC nanofibers is 85–95, and the diameter of the boron-doped SiC nanofibers is 70 nm–80 nm, and the length is 6 μm–8 μm; the silane coupling agent is KH-550, the dispersant is EVA wax, and the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.
[0063] The aforementioned boron-doped SiC nanofibers are mainly made from the following raw materials in parts by weight:
[0064] The mass ratio of boric acid, polyvinylpyrrolidone, and polycarbosilane was 3:10:20. Specifically, boric acid was selected as the dopant. A precursor solution was prepared by mixing boric acid, polyvinylpyrrolidone, and polycarbosilane in a mass ratio of 3:10:20. After electrospinning and curing at 200°C for 2 hours, boron-doped SiC nanofibers were obtained by high-temperature pyrolysis at 1200°C for 3 hours.
[0065] The inner layer further comprises the following components by mass percentage:
[0066] Polyethylene: 98.5%; Antioxidant: 0.3%; Processing aid: 0.2%; Antistatic agent: 1%. The antioxidant in the inner layer can also be antioxidant 1010, the processing aid is polyethylene wax, the antistatic agent is HBS-204P, and PTFE micro powder: 0.2%.
[0067] The outer layer comprises the following mass percentages:
[0068] High-density polyethylene: 96.5%; UV stabilizer: 3.0%; antioxidant: 0.2%; processing aid: 0.3%. The UV stabilizer in the outer layer is carbon black N330, the antioxidant is antioxidant 1010, and the processing aid is polyethylene wax.
[0069] The thickness ratio of the outer layer, the middle wave-absorbing functional layer, and the inner layer of the aforementioned pipe to the pipe wall thickness is 32:45:23.
[0070] The aforementioned fiber-reinforced microwave absorbing tubes can be manufactured using mature three-layer co-extrusion technology.
[0071] Example 5
[0072] The fiber-reinforced microwave absorbing tube of this embodiment includes an outer layer, a middle microwave absorbing functional layer, and an inner layer. The middle microwave absorbing functional layer is located between the outer layer and the inner layer. More importantly, the middle microwave absorbing functional layer includes the following components by mass percentage:
[0073] High-density polyethylene: 78%; Boron-doped SiC nanofibers: 20%; Silane coupling agent: 1.5%; Antioxidant: 0.2%; Dispersant: 0.3%. The boron-doped SiC nanofibers have a diameter of 90nm–100nm and a length of 10μm–15μm; the silane coupling agent is KH-550, the dispersant is EVA wax, and the antioxidant is antioxidant 1010; the boron-doped SiC nanofibers are mainly made from the following raw materials in parts by weight:
[0074] The mass ratio of boric acid:polyvinylpyrrolidone:polycarbosilane is 3:10:20. Specifically, boric acid is selected as the dopant. A precursor solution is prepared by mixing boric acid, polyvinylpyrrolidone, and polycarbosilane in a mass ratio of 3:12:22. The solution is then electrospun, cured at 200°C for 2 hours, and pyrolyzed at 1200°C for 3 hours to obtain boron-doped SiC nanofibers.
[0075] The inner layer further comprises the following components by mass percentage:
[0076] Polyethylene: 98.5%; Antioxidant: 0.3%; Processing aid: 0.2%; Antistatic agent: 1%. The antioxidant in the inner layer can also be antioxidant 1010, the processing aid is polyethylene wax, and the antistatic agent is HBS-204P.
[0077] The outer layer comprises the following mass percentages:
[0078] High-density polyethylene: 96.5%; UV stabilizer: 3.0%; antioxidant: 0.2%; processing aid: 0.3%. The UV stabilizer in the outer layer is carbon black N330, the antioxidant is antioxidant 1010, and the processing aid is polyethylene wax.
[0079] The thickness ratio of the outer layer, the middle wave-absorbing functional layer, and the inner layer of the aforementioned pipe to the pipe wall thickness is 28:38:34.
[0080] The aforementioned fiber-reinforced microwave absorbing tubes can be manufactured using mature three-layer co-extrusion technology.
[0081] Example 6
[0082] The fiber-reinforced microwave absorbing tube of this embodiment includes an outer layer, a middle microwave absorbing functional layer, and an inner layer. The middle microwave absorbing functional layer is located between the outer layer and the inner layer. More importantly, the middle microwave absorbing functional layer includes the following components by mass percentage:
[0083] High-density polyethylene: 78%; Boron-doped SiC nanofibers: 20%; Silane coupling agent: 1.5%; Antioxidant: 0.2%; Dispersant: 0.3%. The aspect ratio of the above boron-doped SiC nanofibers is not less than 80, and the diameter of the boron-doped SiC nanofibers is 50nm~55nm, and the length is 4.0μm~4.5μm; the above silane coupling agent is KH-550, the dispersant is EVA wax, and the antioxidant is antioxidant 1010; the above boron-doped SiC nanofibers are mainly made from the following raw materials in parts by weight:
[0084] The mass ratio of boric acid:polyvinylpyrrolidone:polycarbosilane is 3:10:20. Specifically, boric acid is selected as the dopant. A precursor solution is prepared by mixing boric acid, polyvinylpyrrolidone, and polycarbosilane in a mass ratio of 3:12:22. The solution is then electrospun, cured at 200°C for 2 hours, and pyrolyzed at 1200°C for 3 hours to obtain boron-doped SiC nanofibers.
[0085] The inner layer further comprises the following components by mass percentage:
[0086] Polyethylene: 98.5%; Antioxidant: 0.3%; Processing aid: 0.2%; Antistatic agent: 1%. The antioxidant in the inner layer can also be antioxidant 1010, the processing aid is polyethylene wax, and the antistatic agent is HBS-204P.
[0087] The outer layer comprises the following mass percentages:
[0088] High-density polyethylene: 96.5%; UV stabilizer: 3.0%; antioxidant: 0.2%; processing aid: 0.3%. The UV stabilizer in the outer layer is carbon black N330, the antioxidant is antioxidant 1010, and the processing aid is polyethylene wax.
[0089] The thickness ratio of the outer layer, the middle wave-absorbing functional layer, and the inner layer of the aforementioned pipe to the pipe wall thickness is 28:38:34.
[0090] The aforementioned fiber-reinforced microwave absorbing tubes can be manufactured using mature three-layer co-extrusion technology.
[0091] Comparative Example 1
[0092] This comparative example is used to illustrate the improvement in electromagnetic shielding performance achieved by boron-doped silicon carbide nanofibers in this invention. Pure silicon carbide fibers were used instead for comparison, while other components and contents remained unchanged.
[0093] The fiber-reinforced microwave absorbing tube of this comparative example includes an outer layer, a middle microwave absorbing functional layer, and an inner layer. The middle microwave absorbing functional layer is located between the outer layer and the inner layer. More importantly, the middle microwave absorbing functional layer includes the following components by mass percentage:
[0094] High-density polyethylene: 81.5%; pure SiC nanofibers: 17.2%; silane coupling agent: 1.0%; antioxidant: 0.2%; dispersant: 0.1%. The aspect ratio of the boron-doped SiC nanofibers is not less than 100, and the diameter of the pure SiC nanofibers is 60 nm to 65 nm, and the length is 6.0 μm to 7.0 μm; the silane coupling agent is KH-550, the dispersant is EVA wax, and the antioxidant is antioxidant 1010.
[0095] The inner layer further comprises the following components by mass percentage:
[0096] Polyethylene: 98.4%; Antioxidant: 0.3%; Processing aid: 0.2%; Antistatic agent: 0.7%; PTFE micro powder: 0.4%. The antioxidant in the inner layer can also be antioxidant 1010, the processing aid is polyethylene wax, and the antistatic agent is HBS-204P.
[0097] The outer layer comprises the following mass percentages:
[0098] High-density polyethylene: 96.5%; UV stabilizer: 3.0%; antioxidant: 0.2%; processing aid: 0.3%. The UV stabilizer in the outer layer is carbon black N330, the antioxidant is antioxidant 1010, and the processing aid is polyethylene wax.
[0099] The thickness ratio of the outer layer, the middle wave-absorbing functional layer, and the inner layer of the aforementioned pipe to the pipe wall thickness is 32:40:28.
[0100] The aforementioned fiber-reinforced microwave absorbing tubes can be manufactured using mature three-layer co-extrusion technology.
[0101] The fiber-reinforced microwave absorbing tubes obtained from the above embodiments and comparative examples were randomly selected for corresponding performance tests. The specific test results are shown in Table 1 below.
[0102] Table 1:
[0103]
[0104] As can be seen from the above test results, the effective absorption bandwidth (RL≤-10dB) of the fiber-reinforced absorbing tube obtained by the present invention is superior, achieving full coverage of the Ku band. For example, 7.6 in Example 1 represents 7.6 (full coverage of the Ku band), and the representation in other examples is consistent with the above. The value corresponding to the pure HDPE tube is 0, indicating that the requirements are not met.
[0105] The specific embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.
[0106] Although the present invention has been described in detail and specific embodiments have been cited, it will be apparent to those skilled in the art that various changes or modifications can be made without departing from the spirit and scope of the invention.
Claims
1. A fiber-reinforced microwave absorbing tube, the fiber-reinforced microwave absorbing tube comprising an outer layer, a middle microwave absorbing functional layer, and an inner layer, wherein the middle microwave absorbing functional layer is located between the outer layer and the inner layer, characterized in that, The intermediate absorbing functional layer comprises the following components by mass percentage: High-density polyethylene: 70%–85%; Boron-doped SiC nanofibers: 10%–28%; Silane coupling agent: 0.1%–1.5%; Antioxidant: 0.15%–0.3%, dispersant: 0.2%–0.5%.
2. The fiber-reinforced microwave absorbing tube according to claim 1, characterized in that, The diameter of the boron-doped SiC nanofibers is 50–100 nm, and the length of the boron-doped SiC nanofibers is 4 μm–15 μm.
3. The fiber-reinforced microwave absorbing tube according to claim 2, characterized in that, The aspect ratio of the boron-doped SiC nanofibers is 80–150.
4. The fiber-reinforced microwave absorbing tube according to claim 1, characterized in that, The boron-doped SiC nanofibers are mainly made from the following raw materials in parts by weight: The mass ratio of boric acid:polyvinylpyrrolidone:polycarbosilane is 3:10-12:20-22.
5. The fiber-reinforced microwave absorbing tube according to claim 1, characterized in that, The thickness of the intermediate microwave absorbing functional layer accounts for 38% to 48% of the total wall thickness of the pipe.
6. The fiber-reinforced microwave absorbing tube according to any one of claims 1-5, characterized in that, The dispersant in the intermediate microwave absorbing functional layer is selected from one or more of EVA wax, stearic acid derivatives, and polymeric dispersants.
7. The fiber-reinforced microwave absorbing tube according to any one of claims 1-5, characterized in that, The silane coupling agent in the intermediate microwave absorbing functional layer is selected from KH-550 or KH-570; the antioxidant is selected from one or more of antioxidant 1010, antioxidant 168 and antioxidant 1030.
8. The fiber-reinforced microwave absorbing tube according to any one of claims 1-5, characterized in that, The outer layer comprises the following components by mass percentage: High-density polyethylene: 94%–98%; UV stabilizer: 2.0%–5.0%; antioxidant: 0.2%–0.5%; processing aids: 0.1%–0.5%.
9. The fiber-reinforced microwave absorbing tube according to any one of claims 1-5, characterized in that, The inner layer comprises the following components by mass percentage: High-density polyethylene: 96%–98.5%; Antioxidant: 0.15%–0.3%; Processing aids: 0.1%–0.2%; Antistatic agent: 0.5%~1.0%; PTFE micro powder: 0.5%~1.0%.
10. The fiber-reinforced microwave absorbing tube according to any one of claims 1-5, characterized in that, The outer layer has a wall thickness of 28% to 35% of the total wall thickness of the pipe; the inner layer has a wall thickness of 20% to 30% of the total wall thickness of the pipe.