High-strength light-weight weather-resistant cable for unmanned aerial vehicle and preparation process thereof

Abstract

The present application relates to the technical field of cable, in particular to a high-strength lightweight weather-resistant cable for unmanned aerial vehicle and a preparation process thereof.The high-strength lightweight weather-resistant cable for unmanned aerial vehicle is obtained by sequentially coating an insulating layer, an aramid silicone grease sheath layer and a polyethylene sheath layer outside the conductor.The preparation process of the polyethylene sheath is as follows: linear low-density polyethylene, irradiation crosslinking agent and flame-retardant POSS are mixed and pre-irradiated to obtain pretreated polyethylene;the pretreated polyethylene, high-density polyethylene resin, polyolefin elastomer resin, weather-resistant modified carbon nanotube and magnesium calcium carbonate are mixed, high-temperature blending and extrusion molding are performed to obtain the polyethylene sheath.The finished product prepared by the present application has excellent weather resistance and flame retardance, and also has high strength, bending resistance and electromagnetic interference resistance, so it has a wide application prospect in the technical field of cable.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) and its manufacturing process. Background Technology

[0002] As a key intelligent equipment for developing the low-altitude economy, unmanned aerial vehicles (UAVs) are experiencing explosive growth, and UAV cables are demonstrating unique modern value in this process. From a performance assurance perspective, UAV cables with cross-linked polyethylene (XLPE) sheaths are crucial components for ensuring the stable operation of UAVs. The XLPE sheath possesses excellent electrical insulation and mechanical properties, effectively protecting the internal conductors and enabling efficient power transmission. This ensures the stable delivery of battery power to various components, guaranteeing the normal operation of the UAV's power system, flight control system, and other systems. Simultaneously, the well-protected sheath also provides excellent signal transmission performance, accurately transmitting control commands and sensor data, enabling the UAV to execute missions precisely.

[0003] However, during drone missions, cables continuously transmit power and signals. If these cables overheat or ignite due to short circuits, overloads, or other reasons, safety accidents can easily occur. Therefore, cables with excellent flame-retardant properties are necessary to effectively prevent the spread of fire and avoid larger accidents. Furthermore, during drone flight, cables are exposed to various environments. Oxygen in the air reacts chemically with the cable materials, causing them to age. If the cable insulation layer is oxidized, its insulation performance will decrease, potentially leading to leakage, short circuits, and other problems, severely affecting the normal operation of the drone. Improving the cable's oxidation and weather resistance can slow down the oxidation rate, extend the cable's lifespan, and reduce the frequency and cost of cable replacement.

[0004] To overcome the shortcomings of existing technologies, this invention provides a high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) and its manufacturing process. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) and its manufacturing process, in order to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) includes a conductor, an insulation layer, an aramid silicone grease sheath layer, and a polyethylene sheath layer; the insulation layer is a sheath-foam-sheath carbon-based coating lightweight insulation, consisting of an inner sheath layer, an intermediate layer, and an outer sheath layer from the inside out.

[0008] In a more optimized configuration, the conductor is a lightweight, high-strength conductor with a structure consisting of a composite strand of 0.02-0.04mm ultra-fine silver-plated copper-clad aluminum alloy wire and carbon fiber; the inner sheath material is an ethylene-tetrafluoroethylene copolymer with a thickness of 0.05-0.2mm; the middle layer is a foamed ethylene-tetrafluoroethylene copolymer with a foaming degree of 40-60%; the outer sheath is a semi-conductive nano-graphite coating; and the aramid silicone grease sheath layer is a mixture of aramid and silicone grease.

[0009] In a more optimized manner, the conductor possesses excellent tensile strength and bending resistance, and can withstand 30 million small-radius bends.

[0010] In a more optimized manner, the inner skin layer is an ethylene-tetrafluoroethylene copolymer, which is a type of Teflon plastic and has the advantages of chemical corrosion resistance, high and low temperature resistance, and low density.

[0011] In a more optimized manner, the intermediate foam structure can effectively reduce the density and dielectric constant of the material, reduce the weight of the cable, and improve the signal transmission performance of the cable.

[0012] In a more optimized manner, the foaming degree of the intermediate layer foam structure is 40-60%; the foaming process adopts physical foaming, the foaming source is high-purity nitrogen, and the foaming rate is controlled by controlling the amount of nitrogen injected.

[0013] In a more optimized manner, the formation process of the outer semi-conductive nano-graphite coating is as follows: dispersing graphite nanoparticles in a solvent, then adding a thickener and additives to form a stable sol; coating the sol onto the substrate surface, and curing it at 500℃ for 3-5 seconds to form a semi-conductive nano-graphite coating; the coating thickness is 0.03-0.08 mm.

[0014] In a more optimized manner, the sol coating process involves atomizing the sol into uniform micron-sized droplets through an atomizing nozzle, and then adhering the droplets to the surface of the substrate.

[0015] More preferably, the solvent is a polar solution formed by mixing hexadecyltrimethylammonium bromide and polyvinylpyrrolidone.

[0016] Ideally, the tackifier is graphene or a graphene derivative, specifically graphene oxide or functionalized graphene; the present invention uses graphene oxide as a tackifier, which is suitable for polar systems.

[0017] The optimal strength of the graphene-modified cable is 30.1 MPa when the graphene oxide addition ratio is 1.5%. When the graphene oxide addition ratio exceeds 1.5%, the graphene oxide tends to agglomerate, resulting in a decrease in strength.

[0018] In a more optimized manner, the semi-conductive graphite coating has the characteristics of being lightweight, tough, low-cost, and corrosion-resistant; the semi-conductive graphite coating can also effectively improve the cable's resistance to electromagnetic interference.

[0019] In a more optimized way, aramid fibers have the advantages of high strength, high modulus, and high temperature resistance, and using them as sheathing materials can effectively improve the tensile strength of cables.

[0020] In a more optimized manner, the formation process of the aramid silicone grease sheath layer is as follows: silicone grease is sprayed onto the outside of aramid fibers and then sintered and cured to obtain the aramid silicone grease sheath layer; according to different tensile strength requirements, aramid fibers of different specifications (100D-30000D) are selected to braid the cable sheath layer.

[0021] A more optimized preparation process for the polyethylene sheath layer is as follows: linear low-density polyethylene, irradiation crosslinking agent, and flame-retardant POSS are mixed evenly and pre-irradiated to obtain pretreated polyethylene; the pretreated polyethylene, high-density polyethylene resin, polyolefin elastomer resin, weather-resistant modified carbon nanotubes, and magnesium calcium carbonate are mixed, stirred at 150-180℃ for 8-10 minutes, and extruded to obtain a polyethylene sheath with a thickness of 1.0-1.2 mm.

[0022] In a more optimized manner, the content of each component of the polyethylene sheath is as follows: by mass parts, 20-25 parts linear low-density polyethylene, 0.2-0.3 parts irradiation crosslinking agent, 2-3 parts high-density polyethylene resin, 3-5 parts polyolefin elastomer resin, 4-5 parts flame retardant POSS, 0.25-0.30 parts weather-resistant modified carbon nanotubes, and 20-25 parts magnesium calcium carbonate; wherein the irradiation crosslinking agent is triallyl isocyanurate.

[0023] The optimized pre-irradiation treatment parameters are: a transfer velocity of 0.08-0.09 m / s and a pre-irradiation dose of 18-20 kGy.

[0024] A more optimized preparation process for weather-resistant modified carbon nanotubes is as follows:

[0025] Step S1: Add thionyl chloride to dimethyl sulfoxide and stir until homogeneous to obtain a thionyl chloride solution; add the thionyl chloride solution and methacrylic acid to tetrahydrofuran, stir until homogeneous, then add N,N-dimethylformamide and react at 60-65℃ for 4-5 hours. After the reaction is complete, distill under reduced pressure to obtain methacryloyl chloride.

[0026] Step S2: Under nitrogen atmosphere, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid was added to anhydrous dichloromethane, stirred evenly, and then thionyl chloride was added. The mixture was refluxed at 40-45℃ for 8-10 hours. After the reaction was completed, the chlorinated antioxidant was obtained by vacuum distillation.

[0027] Step S3: Hydroxylated carbon nanotubes were added to anhydrous toluene and ultrasonically dispersed until uniform. Then, 3-aminopropyltriethoxysilane was added and stirred until uniform. Deionized water was added and the mixture was stirred at 65-70℃ for 25-30 h. After the reaction was completed, the mixture was filtered, extracted, and dried to obtain aminolated carbon nanotubes. Methacrylamide chloride, chlorinated antioxidant, and hexachlorocyclotriphosphazene were added to anhydrous toluene and ultrasonically dispersed until uniform. Then, the mixture was added to the anhydrous toluene dispersion of aminolated carbon nanotubes and stirred until uniform. Triethylamine was added dropwise and the mixture was reacted at 75-80℃ for 20-30 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain weather-resistant modified carbon nanotubes.

[0028] In a more optimized manner, the reaction molar ratio of thionyl chloride to methacrylic acid is 1:(1.0-1.1); the reaction mass ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to thionyl chloride is (0.35-0.36):1.5; the reaction mass ratio of hydroxylated carbon nanotubes to 3-aminopropyltriethoxysilane is 0.4:(1.6-1.8); and the reaction mass ratio of methacryloyl chloride, chlorinated antioxidant, hexachlorocyclotriphosphazene, and aminolated carbon nanotubes is 0.7:(0.2-0.3):(0.8-1.0):0.25.

[0029] A more optimized preparation process for flame-retardant POSS is as follows:

[0030] Step S1: Add triallyl cyanurate and azobisisobutyronitrile to ethyl acetate and stir until homogeneous to obtain a triallyl cyanurate reaction solution; under nitrogen atmosphere, add 2,2'-(1,2-ethylenedioxy)diethylthiol to ethyl acetate, stir to dissolve, heat to 70-75℃, and then slowly add the triallyl cyanurate reaction solution dropwise. After the dropwise addition is complete, continue the reaction for 20-25 hours. After the reaction is complete, filter, rotary evaporate, wash, and dry to obtain a mercapto-terminated flame retardant.

[0031] Step S2: Add vinyl POSS and terminal thiol flame retardant to toluene, stir evenly, and then purify by bubbling for 30-40 min. Then add azobisisobutyronitrile and continue to bubble and stir for 10-15 min. After stirring, react at 80-90℃ for 6-7 h. After the reaction is completed, dry by rotary evaporation and vacuum to obtain flame retardant POSS.

[0032] In a more optimized manner, the reaction molar ratio of triallyl cyanurate to 2,2'-(1,2-ethylenedioxy)diethyl mercaptan is 1:(3.1-3.2); and the reaction molar ratio of vinyl POSS to end-thiol flame retardant is 1:(4.5-5.0).

[0033] The beneficial effects of this invention are:

[0034] The present invention is characterized in that linear low-density polyethylene, irradiation crosslinking agent, and flame retardant POSS are mixed and pre-irradiated to obtain pretreated polyethylene; the pretreated polyethylene, high-density polyethylene resin, polyolefin elastomer resin, weather-resistant modified carbon nanotubes, and magnesium calcium carbonate are mixed, and then blended at high temperature and extruded to obtain a polyethylene sheath.

[0035] The key feature of this invention is that, in the preparation of weather-resistant modified carbon nanotubes, the chlorinated antioxidant is obtained by reacting 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with thionyl chloride. 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid is a common hindered phenolic antioxidant; its phenolic hydroxyl group contains an active hydrogen atom that can react with free radicals, terminating free radical chain reactions and thus inhibiting the oxidation process. Through a substitution reaction with aminated carbon nanotubes, this antioxidant group is introduced onto the surface of the carbon nanotubes. When these weather-resistant modified carbon nanotubes are dispersed in a polyethylene sheath, the antioxidant group can capture free radicals generated during oxidation, preventing the oxidative degradation of the polyethylene molecular chains and improving the antioxidant properties of the sheath. Furthermore, the carbon nanotubes themselves possess excellent chemical stability and mechanical properties. It forms a conductive network in the polyethylene matrix, which can not only improve the physical properties of the material, but also disperse stress to a certain extent and reduce micro-defects caused by external environmental factors (such as light, oxygen, etc.), thereby reducing the contact opportunity between polyethylene molecular chains and oxygen, and further enhancing the antioxidant effect.

[0036] The key feature of this invention is that, during the preparation of the flame-retardant POSS, triallyl cyanurate contains nitrogen, and 2,2'-(1,2-ethylenedioxy)diethyl mercaptan contains sulfur; these elements possess flame-retardant properties during combustion. Through a mercapto-olefin click reaction, these flame-retardant groups are introduced into the vinyl POSS. POSS (polyhedral oligomeric silsesquioxane) has a unique cage-like structure, and silicon itself also possesses excellent flame-retardant properties. When the polyethylene sheath burns, the nitrogen, sulfur, and silicon elements in the flame-retardant POSS can form a dense char layer on the material surface. This char layer can block the transfer of oxygen and heat, inhibiting further combustion. Furthermore, the phosphorus-containing groups (from hexachlorocyclotriphosphazene) in the weather-resistant modified carbon nanotubes can promote carbonization during combustion, forming a char layer that synergistically enhances the flame-retardant effect with the flame-retardant POSS. Simultaneously, magnesium calcium carbonate decomposes and absorbs heat at high temperatures, lowering the material surface temperature and also contributing to combustion inhibition.

[0037] The key feature of this invention is that methacryloyl chloride, a chlorinated antioxidant, hexachlorocyclotriphosphazene, and aminated carbon nanotubes are mixed to undergo a substitution reaction, resulting in weather-resistant modified carbon nanotubes. By setting the reaction mass ratio of methacryloyl chloride, chlorinated antioxidant, hexachlorocyclotriphosphazene, and aminated carbon nanotubes to 0.7:(0.2-0.3):(0.8-1.0):0.25, both the weather resistance and flame retardancy of the carbon nanotubes are improved, and carbon-carbon double bonds are introduced onto the surface of the carbon nanotubes. Therefore, the weather-resistant modified carbon nanotubes can be effectively crosslinked and blended with raw materials in polyolefin resins.

[0038] The preparation process of flame-retardant POSS is as follows: A mercapto-olefin click reaction is initiated by adding triallyl cyanurate, azobisisobutyronitrile, and 2,2'-(1,2-ethylenedioxy)bis(ethyl mercapto) mercapto-olefin click reaction to obtain a mercapto-terminated flame retardant. The mercapto-terminated flame retardant is then mixed with vinyl POSS, and the mercapto-olefin click reaction continues. By setting the molar ratio of vinyl POSS to mercapto-terminated flame retardant to 1:(4.5-5.0), a flame-retardant POSS is obtained that introduces a flame-retardant structure while retaining some carbon-carbon double bonds. Therefore, this flame-retardant POSS can be effectively crosslinked and blended with raw materials in polyolefin resins.

[0039] The cable product prepared by this invention includes a conductor, an insulation layer, an aramid silicone grease sheath layer, and a polyethylene sheath layer; the insulation layer is a lightweight insulation material with a sheath-foam-sheath carbon-based coating, consisting of an inner sheath layer, an intermediate layer, and an outer sheath layer from the inside out. This structure has the following advantages:

[0040] (1) The cable has high strength and can meet the various complex working scenarios of the UAV during flight;

[0041] (2) The conductor of the cable is made of a composite stranded wire of ultra-fine silver-plated copper-clad aluminum alloy wire and carbon fiber, which gives the cable excellent bending resistance, thus providing an effective guarantee for the efficient operation of the UAV.

[0042] (3) The cable insulation material adopts a carbon-based coating of sheath-foam-sheath lightweight insulation, which effectively improves the cable's anti-electromagnetic interference capability and signal transmission capability; this advantage can ensure the long-distance operation of the UAV.

[0043] (4) The outer sheath is made of aramid silicone grease, which solves the problem of cable winding and unwinding in traditional cables.

[0044] In summary, the finished product prepared by this invention has excellent weather resistance and flame retardancy, as well as high strength, bending resistance, and electromagnetic interference resistance, thus having broad application prospects in the field of cable technology. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Raw material source:

[0048] Hydroxylated carbon nanotubes, provided by Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences, have a hydroxyl content of 5.6 wt% and an outer diameter of 10 nm; vinyl POSS, provided by Hubei Xingyan New Material Technology Co., Ltd., has a molecular weight of 633; ​​linear low-density polyethylene, provided by China National Petroleum Corporation (CNPC), specification DFDA-7024; high-density polyethylene resin, provided by Shanghai Hongchao Plastic Raw Materials Co., Ltd., has a density of 0.962 g / cm³. 3 Polyolefin elastomer resin, provided by Suzhou Xuchi Plastics Co., Ltd., model number 8401; magnesium calcium carbonate, provided by Lingshou County Shuangshi Mineral Products Processing Plant, 325 mesh; ethylene-tetrafluoroethylene copolymer, provided by Dongguan Wanshixin Plastic Raw Materials Co., Ltd., model number 750; by weight, one part is 1g.

[0049] Example 1: Step S1: Add thionyl chloride to dimethyl sulfoxide and stir until homogeneous to obtain a thionyl chloride solution; add the thionyl chloride solution and methacrylic acid to tetrahydrofuran, stir until homogeneous, then add N,N-dimethylformamide and react at 65°C for 5 hours. After the reaction is complete, distill under reduced pressure to obtain methacryloyl chloride; the molar ratio of thionyl chloride to methacrylic acid is 1:1.05.

[0050] Step S2: Under nitrogen atmosphere, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid was added to anhydrous dichloromethane, stirred until homogeneous, and then thionyl chloride was added. The mixture was refluxed at 45°C for 10 hours. After the reaction was completed, the chlorinated antioxidant was obtained by vacuum distillation. The mass ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to thionyl chloride was 0.355:1.5.

[0051] Step S3: Hydroxylated carbon nanotubes were added to anhydrous toluene and ultrasonically dispersed. 3-Aminopropyltriethoxysilane was then added, stirred until homogeneous, and deionized water was added. The mixture was stirred at 70°C for 30 hours. After the reaction, the mixture was filtered, extracted, and dried to obtain aminolated carbon nanotubes. Methacrylamide chloride, chlorinated antioxidant, and hexachlorocyclotriphosphazene were added to anhydrous toluene and ultrasonically dispersed. This mixture was then added to the anhydrous toluene dispersion of aminolated carbon nanotubes. After stirring until homogeneous, triethylamine was added dropwise. The mixture was reacted at 80°C for 30 hours. After the reaction, the mixture was filtered, washed, and dried to obtain weather-resistant modified carbon nanotubes. The mass ratio of hydroxylated carbon nanotubes to 3-aminopropyltriethoxysilane was 0.4:1.7; the mass ratio of methacryloylamide chloride, chlorinated antioxidant, hexachlorocyclotriphosphazene, and aminolated carbon nanotubes was 0.7:0.25:0.9:0.25.

[0052] Step S4: Add allyl cyanate and azobisisobutyronitrile to ethyl acetate and stir until homogeneous to obtain an allyl cyanate reaction solution; under nitrogen atmosphere, add 2,2'-(1,2-ethylenedioxy)diethylthiol to ethyl acetate, stir to dissolve, heat to 75°C, and then slowly add the allyl cyanate reaction solution dropwise. After the addition is complete, continue the reaction for 25 hours. After the reaction is complete, filter, rotary evaporate, wash, and dry to obtain a mercapto-terminated flame retardant; the molar ratio of allyl cyanate to 2,2'-(1,2-ethylenedioxy)diethylthiol is 1:3.15.

[0053] Step S5: Add vinyl POSS and mercapto-terminated flame retardant to toluene, stir evenly, and purify by bubbling for 40 min. Then add azobisisobutyronitrile and continue bubbling and stirring for 15 min. After stirring, react at 90℃ for 7 h. After the reaction, evaporate by rotary evaporation and vacuum dry to obtain flame retardant POSS. The molar ratio of vinyl POSS to mercapto-terminated flame retardant is 1:4.8.

[0054] Step S6: Mix 20g of linear low-density polyethylene, 0.2g of triallyl isocyanate, and 4g of flame-retardant POSS evenly, and pre-irradiate to obtain pretreated polyethylene; mix the pretreated polyethylene, 2g of high-density polyethylene resin, 3g of polyolefin elastomer resin, 0.25g of weather-resistant modified carbon nanotubes, and 20g of magnesium calcium carbonate, stir at 180℃ for 10min, and extrude to obtain a polyethylene sheath with a thickness of 1.0mm; pre-irradiation treatment parameters: transfer velocity is 0.09m / s, pre-irradiation dose is 20kGy;

[0055] Step S7: The insulation layer, aramid silicone grease sheath layer, and polyethylene sheath layer are sequentially wrapped around the outside of the conductor to obtain the finished product; the insulation layer is a skin-foam-skin carbon-based coating lightweight insulation, which consists of an inner skin layer, an intermediate layer, and an outer skin layer from the inside out;

[0056] The conductor is a lightweight, high-strength conductor, with a structure consisting of a composite strand of 0.04mm ultra-fine silver-plated copper-clad aluminum alloy wire and carbon fiber; the inner sheath material is ethylene-tetrafluoroethylene copolymer with a thickness of 0.05mm; the middle layer is foamed ethylene-tetrafluoroethylene copolymer with a foaming degree of 42%; the outer sheath is a semi-conductive nano-graphite coating; the aramid silicone grease sheath layer is composed of a mixture of aramid and silicone grease; the formation process of the semi-conductive nano-graphite coating is as follows: graphite nanoparticles are dispersed in a solvent, and then binders and additives are added to form a stable sol; the sol is coated on the surface of the substrate and cured at 500℃ for 4s to form a semi-conductive nano-graphite coating; the coating thickness is 0.035mm.

[0057] Example 2: Step S1: Add thionyl chloride to dimethyl sulfoxide and stir until homogeneous to obtain a thionyl chloride solution; add the thionyl chloride solution and methacrylic acid to tetrahydrofuran, stir until homogeneous, then add N,N-dimethylformamide and react at 62°C for 4.5 h. After the reaction is complete, distill under reduced pressure to obtain methacryloyl chloride; the molar ratio of thionyl chloride to methacrylic acid is 1:1.05.

[0058] Step S2: Under nitrogen atmosphere, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid was added to anhydrous dichloromethane, stirred until homogeneous, and then thionyl chloride was added. The mixture was refluxed at 42°C for 9 hours. After the reaction was completed, the chlorinated antioxidant was obtained by vacuum distillation. The mass ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to thionyl chloride was 0.355:1.5.

[0059] Step S3: Hydroxylated carbon nanotubes were added to anhydrous toluene and ultrasonically dispersed. 3-Aminopropyltriethoxysilane was then added, stirred until homogeneous, and deionized water was added. The mixture was stirred at 67°C for 27 hours. After the reaction, the mixture was filtered, extracted, and dried to obtain aminolated carbon nanotubes. Methacrylamide chloride, chlorinated antioxidant, and hexachlorocyclotriphosphazene were added to anhydrous toluene and ultrasonically dispersed. This mixture was then added to the anhydrous toluene dispersion of aminolated carbon nanotubes. After stirring until homogeneous, triethylamine was added dropwise. The mixture was reacted at 77°C for 25 hours. After the reaction, the mixture was filtered, washed, and dried to obtain weather-resistant modified carbon nanotubes. The mass ratio of hydroxylated carbon nanotubes to 3-aminopropyltriethoxysilane was 0.4:1.7; the mass ratio of methacryloylamide chloride, chlorinated antioxidant, hexachlorocyclotriphosphazene, and aminolated carbon nanotubes was 0.7:0.25:0.9:0.25.

[0060] Step S4: Add allyl cyanate and azobisisobutyronitrile to ethyl acetate and stir until homogeneous to obtain an allyl cyanate reaction solution; under nitrogen atmosphere, add 2,2'-(1,2-ethylenedioxy)diethylthiol to ethyl acetate, stir to dissolve, heat to 72°C, and then slowly add the allyl cyanate reaction solution dropwise. After the addition is complete, continue the reaction for 22 hours. After the reaction is complete, filter, rotary evaporate, wash, and dry to obtain a mercapto-terminated flame retardant; the molar ratio of allyl cyanate to 2,2'-(1,2-ethylenedioxy)diethylthiol is 1:3.15.

[0061] Step S5: Add vinyl POSS and mercapto-terminated flame retardant to toluene, stir evenly, and purify by bubbling for 35 min. Then add azobisisobutyronitrile and continue bubbling and stirring for 12 min. After stirring, react at 85℃ for 6.5 h. After the reaction, evaporate by rotary evaporation and vacuum dry to obtain flame retardant POSS. The molar ratio of vinyl POSS to mercapto-terminated flame retardant is 1:4.8.

[0062] Step S6: Mix 20g of linear low-density polyethylene, 0.2g of triallyl isocyanate, and 4g of flame-retardant POSS evenly, and pre-irradiate to obtain pre-treated polyethylene; mix the pre-treated polyethylene, 2g of high-density polyethylene resin, 3g of polyolefin elastomer resin, 0.25g of weather-resistant modified carbon nanotubes, and 20g of magnesium calcium carbonate, stir at 165℃ for 9min, and extrude to obtain a polyethylene sheath with a thickness of 1.0mm; pre-irradiation treatment parameters: transfer velocity is 0.085m / s, pre-irradiation dose is 19kGy;

[0063] Step S7: The insulation layer, aramid silicone grease sheath layer, and polyethylene sheath layer are sequentially wrapped around the outside of the conductor to obtain the finished product; the insulation layer is a skin-foam-skin carbon-based coating lightweight insulation, which consists of an inner skin layer, an intermediate layer, and an outer skin layer from the inside out;

[0064] The conductor is a lightweight, high-strength conductor, with a structure consisting of a composite strand of 0.04mm ultra-fine silver-plated copper-clad aluminum alloy wire and carbon fiber; the inner sheath material is ethylene-tetrafluoroethylene copolymer with a thickness of 0.05mm; the middle layer is foamed ethylene-tetrafluoroethylene copolymer with a foaming degree of 42%; the outer sheath is a semi-conductive nano-graphite coating; the aramid silicone grease sheath layer is composed of a mixture of aramid and silicone grease; the formation process of the semi-conductive nano-graphite coating is as follows: graphite nanoparticles are dispersed in a solvent, and then binders and additives are added to form a stable sol; the sol is coated on the surface of the substrate and cured at 500℃ for 4s to form a semi-conductive nano-graphite coating; the coating thickness is 0.035mm.

[0065] Example 3: Step S1: Add thionyl chloride to dimethyl sulfoxide and stir until homogeneous to obtain a thionyl chloride solution; add the thionyl chloride solution and methacrylic acid to tetrahydrofuran, stir until homogeneous, then add N,N-dimethylformamide and react at 60°C for 4 hours. After the reaction is completed, distill under reduced pressure to obtain methacryloyl chloride; the molar ratio of thionyl chloride to methacrylic acid is 1:1.05.

[0066] Step S2: Under nitrogen atmosphere, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid was added to anhydrous dichloromethane, stirred until homogeneous, and then thionyl chloride was added. The mixture was refluxed at 40°C for 8 hours. After the reaction was completed, the chlorinated antioxidant was obtained by vacuum distillation. The mass ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to thionyl chloride was 0.355:1.5.

[0067] Step S3: Hydroxylated carbon nanotubes were added to anhydrous toluene and ultrasonically dispersed. 3-Aminopropyltriethoxysilane was then added, stirred until homogeneous, and deionized water was added. The mixture was stirred at 65°C for 25 hours. After the reaction, the mixture was filtered, extracted, and dried to obtain aminolated carbon nanotubes. Methacrylamide chloride, chlorinated antioxidant, and hexachlorocyclotriphosphazene were added to anhydrous toluene and ultrasonically dispersed. This mixture was then added to the anhydrous toluene dispersion of aminolated carbon nanotubes. After stirring until homogeneous, triethylamine was added dropwise. The mixture was reacted at 75°C for 20 hours. After the reaction, the mixture was filtered, washed, and dried to obtain weather-resistant modified carbon nanotubes. The mass ratio of hydroxylated carbon nanotubes to 3-aminopropyltriethoxysilane was 0.4:1.7; the mass ratio of methacryloylamide chloride, chlorinated antioxidant, hexachlorocyclotriphosphazene, and aminolated carbon nanotubes was 0.7:0.25:0.9:0.25.

[0068] Step S4: Add allyl cyanate and azobisisobutyronitrile to ethyl acetate and stir until homogeneous to obtain an allyl cyanate reaction solution; under nitrogen atmosphere, add 2,2'-(1,2-ethylenedioxy)diethylthiol to ethyl acetate, stir to dissolve, heat to 70°C, and then slowly add the allyl cyanate reaction solution dropwise. After the addition is complete, continue the reaction for 20 hours. After the reaction is complete, filter, rotary evaporate, wash, and dry to obtain a mercapto-terminated flame retardant; the molar ratio of allyl cyanate to 2,2'-(1,2-ethylenedioxy)diethylthiol is 1:3.15.

[0069] Step S5: Add vinyl POSS and mercapto-terminated flame retardant to toluene, stir evenly, and purify by bubbling for 30 min. Then add azobisisobutyronitrile and continue bubbling and stirring for 10 min. After stirring, react at 80℃ for 6 h. After the reaction, evaporate by rotary evaporation and vacuum dry to obtain flame retardant POSS. The molar ratio of vinyl POSS to mercapto-terminated flame retardant is 1:4.8.

[0070] Step S6: Mix 20g of linear low-density polyethylene, 0.2g of triallyl isocyanate, and 4g of flame-retardant POSS evenly, and pre-irradiate to obtain pretreated polyethylene; mix the pretreated polyethylene, 2g of high-density polyethylene resin, 3g of polyolefin elastomer resin, 0.25g of weather-resistant modified carbon nanotubes, and 20g of magnesium calcium carbonate, stir at 150℃ for 8min, and extrude to obtain a polyethylene sheath with a thickness of 1.0mm; pre-irradiation treatment parameters: transfer velocity is 0.08m / s, pre-irradiation dose is 18kGy;

[0071] Step S7: The insulation layer, aramid silicone grease sheath layer, and polyethylene sheath layer are sequentially wrapped around the outside of the conductor to obtain the finished product; the insulation layer is a skin-foam-skin carbon-based coating lightweight insulation, which consists of an inner skin layer, an intermediate layer, and an outer skin layer from the inside out;

[0072] The conductor is a lightweight, high-strength conductor, with a structure consisting of a composite strand of 0.04mm ultra-fine silver-plated copper-clad aluminum alloy wire and carbon fiber; the inner sheath material is ethylene-tetrafluoroethylene copolymer with a thickness of 0.05mm; the middle layer is foamed ethylene-tetrafluoroethylene copolymer with a foaming degree of 42%; the outer sheath is a semi-conductive nano-graphite coating; the aramid silicone grease sheath layer is composed of a mixture of aramid and silicone grease; the formation process of the semi-conductive nano-graphite coating is as follows: graphite nanoparticles are dispersed in a solvent, and then binders and additives are added to form a stable sol; the sol is coated on the surface of the substrate and cured at 500℃ for 4s to form a semi-conductive nano-graphite coating; the coating thickness is 0.035mm.

[0073] Comparative Example 1: The weather-resistant modified carbon nanotubes were removed, and the rest was the same as in Example 1. The specific steps are as follows: Step S1: Triallyl cyanurate and azobisisobutyronitrile were added to ethyl acetate and stirred until homogeneous to obtain a cyanallyl cyanurate reaction solution; under nitrogen atmosphere, 2,2'-(1,2-ethylenedioxy)diethylthiol was added to ethyl acetate, stirred until dissolved, heated to 75°C, and then the cyanallyl cyanurate reaction solution was slowly added dropwise. After the addition was completed, the reaction was continued for 25 hours. After the reaction was completed, the mixture was filtered, rotary evaporated, washed, and dried to obtain a mercapto-terminated flame retardant; the molar ratio of cyanallyl cyanurate to 2,2'-(1,2-ethylenedioxy)diethylthiol was 1:3.15.

[0074] Step S2: Add vinyl POSS and mercapto-terminated flame retardant to toluene, stir evenly, and purify by bubbling for 40 min. Then add azobisisobutyronitrile and continue bubbling and stirring for 15 min. After stirring, react at 90℃ for 7 h. After the reaction, evaporate by rotary evaporation and vacuum dry to obtain flame retardant POSS. The molar ratio of vinyl POSS to mercapto-terminated flame retardant is 1:4.8.

[0075] Step S3: Mix 20g of linear low-density polyethylene, 0.2g of triallyl isocyanate, and 4g of flame-retardant POSS evenly, and pre-irradiate to obtain pretreated polyethylene; mix the pretreated polyethylene, 2g of high-density polyethylene resin, 3g of polyolefin elastomer resin, and 20g of magnesium calcium carbonate, stir at 180℃ for 10min, and extrude to obtain a polyethylene sheath with a thickness of 1.0mm; pre-irradiation parameters: transfer speed is 0.09m / s, pre-irradiation dose is 20kGy;

[0076] Step S4: The insulation layer, aramid silicone grease sheath layer, and polyethylene sheath layer are sequentially wrapped around the outside of the conductor to obtain the finished product; the insulation layer is a lightweight insulation with a skin-foam-skin carbon-based coating, consisting of an inner skin layer, an intermediate layer, and an outer skin layer from the inside out;

[0077] The conductor is a lightweight, high-strength conductor, with a structure consisting of a composite strand of 0.04mm ultra-fine silver-plated copper-clad aluminum alloy wire and carbon fiber; the inner sheath material is ethylene-tetrafluoroethylene copolymer with a thickness of 0.05mm; the middle layer is foamed ethylene-tetrafluoroethylene copolymer with a foaming degree of 42%; the outer sheath is a semi-conductive nano-graphite coating; the aramid silicone grease sheath layer is composed of a mixture of aramid and silicone grease; the formation process of the semi-conductive nano-graphite coating is as follows: graphite nanoparticles are dispersed in a solvent, and then binders and additives are added to form a stable sol; the sol is coated on the surface of the substrate and cured at 500℃ for 4s to form a semi-conductive nano-graphite coating; the coating thickness is 0.035mm.

[0078] Comparative Example 2: Weather-resistant modified carbon nanotubes and flame-retardant POSS were removed, and the rest was the same as in Example 1. The specific steps are as follows: Step S1: 20g of linear low-density polyethylene and 0.2g of triallyl isocyanate were mixed evenly and pre-irradiated to obtain pre-treated polyethylene; the pre-treated polyethylene, 2g of high-density polyethylene resin, 3g of polyolefin elastomer resin and 20g of magnesium calcium carbonate were mixed and stirred at 180℃ for 10min and extruded to obtain a polyethylene sheath with a thickness of 1.0mm; the pre-irradiation treatment parameters were: transfer speed of 0.09m / s and pre-irradiation dose of 20kGy.

[0079] Step S2: The insulation layer, aramid silicone grease sheath layer, and polyethylene sheath layer are sequentially wrapped around the outside of the conductor to obtain the finished product; the insulation layer is a lightweight insulation with a skin-foam-skin carbon-based coating, consisting of an inner skin layer, an intermediate layer, and an outer skin layer from the inside out;

[0080] The conductor is a lightweight, high-strength conductor, with a structure consisting of a composite strand of 0.04mm ultra-fine silver-plated copper-clad aluminum alloy wire and carbon fiber; the inner sheath material is ethylene-tetrafluoroethylene copolymer with a thickness of 0.05mm; the middle layer is foamed ethylene-tetrafluoroethylene copolymer with a foaming degree of 42%; the outer sheath is a semi-conductive nano-graphite coating; the aramid silicone grease sheath layer is composed of a mixture of aramid and silicone grease; the formation process of the semi-conductive nano-graphite coating is as follows: graphite nanoparticles are dispersed in a solvent, and then binders and additives are added to form a stable sol; the sol is coated on the surface of the substrate and cured at 500℃ for 4s to form a semi-conductive nano-graphite coating; the coating thickness is 0.035mm.

[0081] Testing and experimentation:

[0082] Flame retardancy test: Referring to GB / T 2406.2-2022 "Determination of burning behavior of plastics by oxygen index method - Part 2: Room temperature test", the polyethylene sheath prepared by this invention was cut into long strips, and the oxygen index value was tested and recorded.

[0083] Vertical burning test: The polyethylene sheath prepared in this invention was cut into 130×13mm specimens, and the flame retardancy rating of the specimens was determined using the FFT008 instrument in accordance with ASTM D 3801.

[0084] Antioxidant resistance test: The polyethylene sheath prepared according to this invention was immersed in an aqueous solution with a chlorine content of 5 mg / L for 15 days to obtain a pretreated polyethylene sheath. The oxidation induction period was tested according to GB / T 19466.6-2009 at a test temperature of 250℃. The results are shown in the table below:

[0085] Oxygen index / % Flame class Oxidation induction time / min Example 1 31.6 V-0 185 Example 2 31.4 V-0 183 Example 3 31.3 V-0 182 Comparative Example 1 27.5 V-0 137 Comparative Example 2 23.3 V-1 129

[0086] Conclusion: In Examples 1-3, the dosage remained unchanged, with only some reaction parameters modified. Experimental data showed no significant fluctuations in the performance of the samples.

[0087] Comparative Example 1: The weather-resistant modified carbon nanotubes were removed, while the rest remained the same as in Example 1. Experimental data showed that, compared to Example 1, the oxygen index decreased to 27.5%, and the oxidation induction period shortened to 137 min. The reason for this is that the weather-resistant modified carbon nanotubes contain phosphorus-containing groups, which synergistically enhance the flame-retardant effect with the flame-retardant POSS. Therefore, removing them reduced the oxygen index. Furthermore, hindered phenols were introduced onto the surface of the weather-resistant modified carbon nanotubes; therefore, removing them shortened the oxidation induction period.

[0088] Comparative Example 2: Weather-resistant modified carbon nanotubes and flame-retardant POSS were removed, while the rest remained the same as in Example 1. Experimental data showed that, compared with Example 1, the oxygen index decreased to 23.3%, the flammability rating changed to V-1, and the oxidation induction period was shortened to 129 min. The reasons for this are as follows: Based on Comparative Example 1, removing the flame-retardant POSS further reduced the amount of flame-retardant elements, thus lowering the oxygen index; POSS (polyhedral oligomeric silsesquioxane) has a unique cage-like structure, thus possessing a relatively stable structure. Therefore, removing it reduced weather resistance and shortened the oxidation induction period.

[0089] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process method article or apparatus.

[0090] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs), characterized in that: It includes a conductor, an insulating layer, an aramid silicone grease sheath layer, and a polyethylene sheath layer; the insulating layer is a skin-foam-skin carbon-based coating lightweight insulation, consisting of an inner skin layer, an intermediate layer, and an outer skin layer from the inside out; The preparation process of the polyethylene sheath layer is as follows: linear low-density polyethylene, irradiation crosslinking agent, and flame retardant POSS are mixed evenly and pre-irradiated to obtain pretreated polyethylene; the pretreated polyethylene, high-density polyethylene resin, polyolefin elastomer resin, weather-resistant modified carbon nanotubes, and magnesium calcium carbonate are mixed and stirred at 150-180℃ for 8-10 minutes and extruded to obtain a polyethylene sheath with a thickness of 1.0-1.2 mm; The preparation process of weather-resistant modified carbon nanotubes is as follows: Step S1: Add thionyl chloride to dimethyl sulfoxide and stir until homogeneous to obtain a thionyl chloride solution; add the thionyl chloride solution and methacrylic acid to tetrahydrofuran, stir until homogeneous, then add N,N-dimethylformamide and react at 60-65℃ for 4-5 hours. After the reaction is complete, distill under reduced pressure to obtain methacryloyl chloride. Step S2: Under nitrogen atmosphere, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid was added to anhydrous dichloromethane, stirred evenly, and then thionyl chloride was added. The mixture was refluxed at 40-45℃ for 8-10 hours. After the reaction was completed, the chlorinated antioxidant was obtained by vacuum distillation. Step S3: Hydroxylated carbon nanotubes were added to anhydrous toluene and ultrasonically dispersed until uniform. Then, 3-aminopropyltriethoxysilane was added and stirred until uniform. Deionized water was added and the mixture was stirred at 65-70℃ for 25-30 hours. After the reaction was completed, the mixture was filtered, extracted, and dried to obtain aminolated carbon nanotubes. Methacrylamide chloride, chlorinated antioxidant, and hexachlorocyclotriphosphazene were added to anhydrous toluene and ultrasonically dispersed until uniform. Then, the mixture was added to the anhydrous toluene dispersion of aminolated carbon nanotubes and stirred until uniform. Triethylamine was added dropwise and the mixture was reacted at 75-80℃ for 20-30 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain weather-resistant modified carbon nanotubes. The preparation process of flame-retardant POSS is as follows: Step S1: Add triallyl cyanurate and azobisisobutyronitrile to ethyl acetate and stir until homogeneous to obtain a triallyl cyanurate reaction solution; under nitrogen atmosphere, add 2,2'-(1,2-ethylenedioxy)diethylthiol to ethyl acetate, stir to dissolve, heat to 70-75℃, and then slowly add the triallyl cyanurate reaction solution dropwise. After the dropwise addition is complete, continue the reaction for 20-25 hours. After the reaction is complete, filter, rotary evaporate, wash, and dry to obtain a mercapto-terminated flame retardant. Step S2: Add vinyl POSS and terminal thiol flame retardant to toluene, stir evenly, and then purify by bubbling for 30-40 min. Then add azobisisobutyronitrile and continue to bubble and stir for 10-15 min. After stirring, react at 80-90℃ for 6-7 h. After the reaction is completed, dry by rotary evaporation and vacuum to obtain flame retardant POSS.

2. The high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) according to claim 1, characterized in that: The conductor is a lightweight, high-strength conductor, with a structure consisting of a composite strand of 0.02-0.04mm ultra-fine silver-plated copper-clad aluminum alloy wire and carbon fiber; the inner sheath material is ethylene-tetrafluoroethylene copolymer with a thickness of 0.05-0.2mm; the middle layer is foamed ethylene-tetrafluoroethylene copolymer with a foaming degree of 40-60%; the outer sheath is a semi-conductive nano-graphite coating; and the aramid silicone grease sheath layer is a mixture of aramid and silicone grease.

3. The high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) according to claim 2, characterized in that: The formation process of the semi-conductive nano-graphite coating is as follows: graphite nanoparticles are dispersed in a solvent, and then binders and additives are added to form a stable sol; the sol is coated on the surface of the substrate and cured at 500℃ for 3-5 seconds to form a semi-conductive nano-graphite coating; the coating thickness is 0.03-0.08 mm.

4. The high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) according to claim 1, characterized in that: The components of the polyethylene sheath are as follows (by weight): 20-25 parts linear low-density polyethylene, 0.2-0.3 parts irradiation crosslinking agent, 2-3 parts high-density polyethylene resin, 3-5 parts polyolefin elastomer resin, 4-5 parts flame retardant POSS, 0.25-0.30 parts weather-resistant modified carbon nanotubes, and 20-25 parts magnesium calcium carbonate; the irradiation crosslinking agent is triallyl isocyanurate.

5. A high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) according to claim 1, characterized in that: Pre-irradiation treatment parameters: transfer velocity of 0.08-0.09 m / s, pre-irradiation dose of 18-20 kGy.

6. A high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) according to claim 1, characterized in that: The molar ratio of thionyl chloride to methacrylic acid is 1:(1.0-1.1); the mass ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to thionyl chloride is (0.35-0.36):1.5; the mass ratio of hydroxylated carbon nanotubes to 3-aminopropyltriethoxysilane is 0.4:(1.6-1.8); and the mass ratio of methacryloyl chloride, chlorinated antioxidant, hexachlorocyclotriphosphazene, and aminolated carbon nanotubes is 0.7:(0.2-0.3):(0.8-1.0):0.

25.

7. A high-strength, lightweight, weather-resistant cable for unmanned aerial vehicles (UAVs) according to claim 1, characterized in that: The reaction molar ratio of triallyl cyanurate to 2,2'-(1,2-ethylenedioxy)diethyl mercaptan is 1:(3.1-3.2); the reaction molar ratio of vinyl POSS to end-thiol flame retardant is 1:(4.5-5.0).

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