Lightweight high-voltage power cable for eVTOL suitable for low-pressure environment

Abstract

The application discloses a lightweight high-voltage power cable suitable for eVTOL in a low-pressure environment and belongs to the technical field of cables. The cable comprises, from inside to outside, a conductor, a three-layer composite insulation layer, a composite shielding layer and a weather-resistant and flame-retardant outer protective layer. The outer protective layer contains a functional additive prepared from chitosan grafted with a phosphorus-containing silicon modifier, and has the effects of toughening, flame retardation and ultraviolet aging resistance. The cable has the characteristics of light weight, high tensile strength, excellent flame retardation grade, outstanding torsion resistance and aging resistance, and can meet the high-voltage power transmission requirements of eVTOL in a low-pressure and complex working condition.

Description

Technical Field

[0001] This invention belongs to the field of cable technology, specifically, it relates to a lightweight high-voltage power cable for eVTOL suitable for low-pressure environments. Background Technology

[0002] With the rapid development of electric vertical takeoff and landing (eVTOL) aircraft, stringent requirements have been placed on their high-voltage power cables, including lightweight, high flexibility, resistance to low air pressure, flame retardancy, and long service life. However, conventional high-voltage power cables currently employ pure copper conductors, a single polyolefin insulation layer, and a common sheath structure, which presents several shortcomings in practical applications: First, pure copper conductors have high density and mass, significantly increasing the load on aircraft and hindering lightweight design; second, the electric field distribution of a single or homogeneous insulation layer is prone to distortion under low-pressure environments, and localized electric field concentration can induce partial discharge, reducing the reliability and safety of high-voltage power transmission; third, the sheath material is mostly made of common polyolefins, which have limited mechanical properties, poor resistance to repeated bending and impact, and are prone to micro-cracks that propagate under conditions such as large-angle torsion and vibration, leading to sheath cracking; at the same time, this type of sheath has insufficient flame retardant properties, making it difficult to effectively suppress the spread of flames when exposed to fire, and lacks resistance to ultraviolet radiation and thermo-oxidative aging, resulting in significant performance degradation after long-term outdoor use; in addition, traditional shielding layer structures often fail to simultaneously achieve efficient electromagnetic shielding and mechanical protection, failing to meet the complex electromagnetic environment and structural strength requirements of eVTOL.

[0003] Therefore, there is an urgent need to develop a high-voltage power cable that is suitable for low-pressure environments, lightweight, has excellent mechanical properties, is flame-retardant and aging-resistant, and has reliable shielding performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a lightweight high-voltage power cable for eVTOL suitable for low-pressure environments.

[0005] The objective of this invention can be achieved through the following technical solutions: A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments comprises, from the inside out, a conductor, an insulation layer, a composite shielding layer, and a weather-resistant and flame-retardant outer sheath. The conductor is made of copper-clad aluminum monofilament with a diameter of 0.2 mm. After being drawn by a shaped cross-section die, stranded by a wire stranding machine, and compressed twice by a radial compression die, a cross-sectional area of ​​10 mm² is obtained. 2 A tightly compressed circular conductor; The insulating layer covers the outer periphery of the conductor and includes, from the inside out, an inner insulating layer, a middle insulating layer, and an outer insulating layer; the inner insulating layer is a polyolefin material layer, the middle insulating layer is a polyimide material layer, and the outer insulating layer is a maleic anhydride-grafted polyethylene resin layer. The composite shielding layer covers the outer periphery of the outer insulation layer and includes a silver-plated aluminum-plastic composite strip longitudinal wrapping layer and a tin-plated copper wire braided layer arranged sequentially from the inside to the outside. The weather-resistant and flame-retardant outer protective layer covers the outer periphery of the composite shielding layer, and its raw materials include the following components in parts by weight: 28-36 parts high-density polyethylene, 13-15 parts low-density polyethylene, 15-22 parts ethylene-vinyl acetate copolymer, 12-15 parts functional additives, 0.8-1.5 parts antioxidants, 0.8-1.5 parts lubricants, and 8-10 parts fillers.

[0006] In a more optimized manner, the preparation process of the functional additive is as follows: the modifier is added to anhydrous N,N-dimethylformamide, and anhydrous 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and anhydrous N-hydroxysuccinimide are added sequentially. The pH is adjusted to 5.5, and the mixture is stirred at room temperature for 30 min to obtain an activated modifier solution. The activated modifier solution is mixed with anhydrous ethanol and stirred evenly to obtain a mixed solution. Separately, dry chitosan powder is weighed and dispersed in anhydrous ethanol, and directly transferred to the above mixed solution. The temperature is raised to 70°C and the reaction is carried out for 24 h. After the reaction is completed, the mixture is naturally cooled to room temperature, filtered, washed, and dried to obtain the modified additive.

[0007] In a more optimized manner, the ratio of the modifier, anhydrous 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, anhydrous N-hydroxysuccinimide, and chitosan powder is 4.8g:4.0g:2.4g:1.7g.

[0008] In a more optimized manner, the preparation process of the modifier is as follows: S1: Add eugenol to anhydrous dichloromethane, stir well, add triethylamine, heat to 0-5℃ in an ice-water bath, slowly add tert-butyldimethylchlorosilane, stir at room temperature for 8 hours after the addition is complete, wash the reaction solution with deionized water several times, extract and separate the organic phase, dry with anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure to remove solvent, recrystallize, and dry under low temperature vacuum to obtain intermediate A; S2: Under a protective atmosphere, intermediate A, p-carboxybenzenesulfonamide, and anhydrous toluene were mixed and stirred until homogeneous. The mixture was then heated to 115°C and refluxed for 8 hours. Subsequently, the temperature was lowered to 80°C, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The temperature was then raised to 115°C and refluxed for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the modifier.

[0009] The phenolic hydroxyl group of eugenol first undergoes nucleophilic substitution with tert-butyldimethylchlorosilane under alkaline conditions to generate a tert-butyldimethylsilyl ether protecting group. This step effectively shields the phenolic hydroxyl group from side reactions in the subsequent condensation process and introduces a flexible silicon-containing side chain. The aldehyde group of the resulting intermediate further undergoes Schiff base condensation and dehydration with the primary amino group of p-carboxybenzenesulfonamide to form an imine structure. Subsequently, the PH bond in 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide undergoes nucleophilic addition to the imine double bond to obtain a modifier containing carboxyl, phosphaphenanthrene, and tert-butyldimethylsilyl ether groups.

[0010] In this modifier, the tert-butyldimethylsilyl ether group is retained during the subsequent grafting process. Its Si-O bond has high bond energy and a large bond angle, allowing the molecular chain to rotate freely. This introduces flexible side chains between the rigid chitosan backbone and the DOPO aromatic ring structure. After curing, a large number of flexible buffer points are formed inside the material, which can absorb fracture energy under external force, significantly improving toughness. Simultaneously, silicon itself has condensed-phase flame-retardant properties and can form a synergistic flame-retardant effect with the phosphaphenanthrene group, further enhancing flame-retardant performance. Finally, the carboxyl group on the modifier, activated by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide, first transforms into an active O-acylisourea intermediate, then generates a stable NHS active ester. This active ester is subjected to nucleophilic attack by the primary amino group on the chitosan molecular chain, forming an amide bond through addition-elimination, thus achieving covalent grafting of the modifier onto the chitosan molecule, ultimately yielding a functional additive with both flame-retardant and toughening functions.

[0011] The structure of the functional additive is shown below:

[0012] In a more optimized manner, the ratio of the amounts of eugenol, anhydrous dichloromethane, triethylamine, and tert-butyldimethylchlorosilane in S1 is 10g:120mL:7g:10g.

[0013] In a more optimized manner, in S2, the ratio of intermediate A, p-carboxybenzenesulfonamide, anhydrous toluene, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 10 g: 6.8 g: 120 mL: 7.6 g.

[0014] More preferably, the antioxidant is antioxidant 1010.

[0015] Ideally, the lubricant is polyethylene wax.

[0016] Ideally, the filler is one or more of carbon black, montmorillonite, and calcium carbonate.

[0017] The beneficial effects of this invention are: This invention effectively improves the overall performance of the cable by introducing functional additives into the sheath layer, as detailed below: The functional additive uses natural chitosan as its macromolecular backbone, and introduces flexible siloxane side chains and phosphorus-containing phenanthrene flame-retardant groups through chemical grafting. In terms of mechanical properties, the grafted tert-butyldimethylsilyl ether side chains contain compliant Si-O bonds. When the sheath is subjected to bending or tensile stress, these flexible side chains act as stress buffer nodes in the matrix, dispersing and dissipating concentrated stress through conformational rearrangement and chain segment slippage, thereby inhibiting the initiation and propagation of microcracks. Simultaneously, the tert-butyl groups at the ends of the silyl ether side chains help improve the interfacial compatibility between the additive and the matrix resin, promoting uniform dispersion and avoiding internal defects caused by agglomeration. This simultaneously enhances the tensile strength, impact toughness, and resistance to repeated bending of the sheath, ensuring the structural integrity of the cable under large-angle torsion conditions.

[0018] In terms of flame retardant properties, the phosphorus-containing phenanthrene groups decompose upon heating to produce phosphates, which catalyze the dehydration of the matrix resin into char, forming a dense protective layer. The siloxane components undergo high-temperature cracking to generate silicon oxides, which embed into the char layer, enhancing its density and thermal stability, effectively blocking the transfer of heat and oxygen inward. Simultaneously, the chitosan backbone thermally decomposes to release inert gases such as ammonia and nitrogen, diluting the flammable atmosphere in the combustion zone. The phosphorus groups also possess free radical scavenging capabilities, interrupting the combustion chain reaction. The synergistic effect of phosphorus, nitrogen, and silicon along the two pathways of condensed-phase char formation and gas-phase dilution allows the sheath to achieve good flame retardant effects and inhibit melt dripping even at relatively low addition levels.

[0019] In terms of aging resistance, the eugenol aromatic conjugated unit and the phosphorophenanthrene aromatic heterocycle in the additive molecule both have ultraviolet absorption capabilities and are covalently grafted onto the chitosan backbone, making them less prone to migration and precipitation. Therefore, they can resist ultraviolet radiation and thermo-oxidative aging for a long time and slow down the deterioration of the sheath performance.

[0020] In addition, the cable has been specifically designed in terms of structure. The conductor uses copper-clad aluminum composite material and is radially compressed, which reduces weight and enhances vibration resistance; the composite shielding layer is composed of silver-plated aluminum-plastic composite tape wrapped longitudinally and tin-plated copper wire braiding, which takes into account both electromagnetic shielding and mechanical protection; the three-layer gradient insulation structure, through the gradual transition of dielectric properties, helps to mitigate electric field concentration and suppress partial discharge in low-pressure environments, thereby improving the reliability of high-voltage power transmission. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments, comprising, from the inside out, a conductor, an insulation layer, a composite shielding layer, and a weather-resistant and flame-retardant outer sheath; The conductor is made of copper-clad aluminum monofilament with a diameter of 0.2 mm. After being drawn by a shaped cross-section die, stranded by a wire stranding machine, and compressed twice by a radial compression die, a cross-sectional area of ​​10 mm² is obtained. 2 A tightly compressed circular conductor; The insulating layer covers the outer periphery of the conductor and comprises, from the inside out, an inner insulating layer, a middle insulating layer, and an outer insulating layer; the inner insulating layer is a polyolefin material layer (thickness 0.1 mm), the middle insulating layer is a polyimide material layer (thickness 0.2 mm), and the outer insulating layer is a maleic anhydride-grafted polyethylene resin layer (thickness 0.1 mm). The composite shielding layer covers the outer periphery of the outer insulation layer and includes a silver-plated aluminum-plastic composite strip longitudinal wrapping layer and a tin-plated copper wire braided layer arranged sequentially from the inside to the outside. The weather-resistant and flame-retardant outer sheath is coated around the outer periphery of the composite shielding layer. Its preparation method is as follows: 28 parts high-density polyethylene, 13 parts low-density polyethylene, 15 parts ethylene-vinyl acetate copolymer, 12 parts functional additives, 0.8 parts antioxidant (antioxidant 1010), 0.8 parts lubricant (polyethylene wax), and 8 parts filler (carbon black) are placed in a high-speed mixer and stirred at 1000 r / min for 20 min at room temperature to ensure uniform mixing. The mixture is then transferred to a twin-screw extruder and melt-blended at 160°C. After water cooling, pelletizing, and drying, the sheath material is obtained. Finally, the sheath material is extruded and coated around the outer periphery of the composite shielding layer to form the weather-resistant and flame-retardant outer sheath. The preparation process of the functional additive is as follows: 4.8g of modifier is added to 50mL of anhydrous N,N-dimethylformamide, followed by the sequential addition of 4.0g of anhydrous 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2.4g of anhydrous N-hydroxysuccinimide. The pH is adjusted to 5.5, and the mixture is stirred at room temperature for 30min to obtain an activated modifier solution. The activated modifier solution is then mixed with 100mL of anhydrous ethanol and stirred until homogeneous. Separately, 1.7g of dried chitosan powder is weighed and dispersed in 80mL of anhydrous ethanol, which is then directly transferred to the above mixture. The mixture is heated to 70℃ and reacted for 24h. After the reaction is completed, the mixture is naturally cooled to room temperature, filtered, washed, and dried to obtain the modified additive. The preparation process of the modifier is as follows: S1: Add 10g of eugenol to 120mL of anhydrous dichloromethane, stir well, add 7g of triethylamine, heat to 0℃ in an ice-water bath, slowly add 10g of tert-butyldimethylchlorosilane, stir at room temperature for 8h after the addition is complete, wash the reaction solution with deionized water several times, extract and separate the organic phase, dry with anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure to remove the solvent, recrystallize, and dry under low temperature vacuum to obtain intermediate A; S2: Under a nitrogen atmosphere, 10g of intermediate A, 6.8g of p-carboxybenzenesulfonamide, and 120mL of anhydrous toluene were mixed and stirred until homogeneous. The mixture was then heated to 115℃ and refluxed for 8 hours. Subsequently, the temperature was lowered to 80℃, and 7.6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The temperature was then further increased to 115℃ and refluxed for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the modifier.

[0023] Example 2: A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments, comprising, from the inside out, a conductor, an insulation layer, a composite shielding layer, and a weather-resistant and flame-retardant outer sheath; The conductor is made of copper-clad aluminum monofilament with a diameter of 0.2 mm. After being drawn by a shaped cross-section die, stranded by a wire stranding machine, and compressed twice by a radial compression die, a cross-sectional area of ​​10 mm² is obtained. 2 A tightly compressed circular conductor; The insulating layer covers the outer periphery of the conductor and comprises, from the inside out, an inner insulating layer, a middle insulating layer, and an outer insulating layer; the inner insulating layer is a polyolefin material layer (thickness 0.1 mm), the middle insulating layer is a polyimide material layer (thickness 0.2 mm), and the outer insulating layer is a maleic anhydride-grafted polyethylene resin layer (thickness 0.1 mm). The composite shielding layer covers the outer periphery of the outer insulation layer and includes a silver-plated aluminum-plastic composite strip longitudinal wrapping layer and a tin-plated copper wire braided layer arranged sequentially from the inside to the outside. The weather-resistant and flame-retardant outer sheath is coated around the outer periphery of the composite shielding layer. Its preparation method is as follows: 36 parts high-density polyethylene, 15 parts low-density polyethylene, 22 parts ethylene-vinyl acetate copolymer, 15 parts functional additives, 1.5 parts antioxidant (antioxidant 1010), 1.5 parts lubricant (polyethylene wax), and 10 parts filler (carbon black) are placed in a high-speed mixer and stirred at 1000 r / min for 20 min at room temperature to ensure uniform mixing. The mixture is then transferred to a twin-screw extruder and melt-blended at 160°C. After water cooling, pelletizing, and drying, the sheath material is obtained. Finally, the sheath material is extruded and coated around the outer periphery of the composite shielding layer to form the weather-resistant and flame-retardant outer sheath. The preparation process of the functional additive is as follows: 4.8g of modifier is added to 50mL of anhydrous N,N-dimethylformamide, followed by the sequential addition of 4.0g of anhydrous 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2.4g of anhydrous N-hydroxysuccinimide. The pH is adjusted to 5.5, and the mixture is stirred at room temperature for 30min to obtain an activated modifier solution. The activated modifier solution is then mixed with 100mL of anhydrous ethanol and stirred until homogeneous to obtain a mixed solution. Separately, 1.7g of dried chitosan powder is weighed and dispersed in 80mL of anhydrous ethanol, which is then directly transferred to the above mixed solution. The mixture is heated to 70℃ and reacted for 24h. After the reaction is completed, the mixture is naturally cooled to room temperature, filtered, washed, and dried to obtain the modified additive. The preparation process of the modifier is as follows: S1: Add 10g of eugenol to 120mL of anhydrous dichloromethane, stir well, add 7g of triethylamine, heat to 5℃ in an ice-water bath, slowly add 10g of tert-butyldimethylchlorosilane, stir at room temperature for 8h after the addition is complete, wash the reaction solution with deionized water several times, extract and separate the organic phase, dry with anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure to remove the solvent, recrystallize, and dry under low temperature vacuum to obtain intermediate A; S2: Under a nitrogen atmosphere, 10g of intermediate A, 6.8g of p-carboxybenzenesulfonamide, and 120mL of anhydrous toluene were mixed and stirred until homogeneous. The mixture was then heated to 115℃ and reacted for 8h. Subsequently, the temperature was lowered to 80℃, and 7.6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The temperature was further increased to 115℃ and refluxed for 8h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the modifier.

[0024] Example 3: A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments, comprising, from the inside out, a conductor, an insulation layer, a composite shielding layer, and a weather-resistant and flame-retardant outer sheath; The conductor is made of copper-clad aluminum monofilament with a diameter of 0.2 mm. After being drawn by a shaped cross-section die, stranded by a wire stranding machine, and compressed twice by a radial compression die, a cross-sectional area of ​​10 mm² is obtained. 2 A tightly compressed circular conductor; The insulating layer covers the outer periphery of the conductor and comprises, from the inside out, an inner insulating layer, a middle insulating layer, and an outer insulating layer; the inner insulating layer is a polyolefin material layer (thickness 0.1 mm), the middle insulating layer is a polyimide material layer (thickness 0.2 mm), and the outer insulating layer is a maleic anhydride-grafted polyethylene resin layer (thickness 0.1 mm). The composite shielding layer covers the outer periphery of the outer insulation layer and includes a silver-plated aluminum-plastic composite strip longitudinal wrapping layer and a tin-plated copper wire braided layer arranged sequentially from the inside to the outside. The weather-resistant and flame-retardant outer sheath is coated around the outer periphery of the composite shielding layer. Its preparation method is as follows: 30 parts high-density polyethylene, 14 parts low-density polyethylene, 20 parts ethylene-vinyl acetate copolymer, 13 parts functional additives, 1 part antioxidant (antioxidant 1010), 1 part lubricant (polyethylene wax), and 9 parts filler (carbon black) are placed in a high-speed mixer and stirred at 1000 r / min for 20 minutes at room temperature to ensure uniform mixing. The mixture is then transferred to a twin-screw extruder and melt-blended at 160°C. After water cooling, pelletizing, and drying, the sheath material is obtained. Finally, the sheath material is extruded and coated around the outer periphery of the composite shielding layer to form the weather-resistant and flame-retardant outer sheath. The preparation process of the functional additive is as follows: 4.8g of modifier is added to 50mL of anhydrous N,N-dimethylformamide, followed by the sequential addition of 4.0g of anhydrous 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2.4g of anhydrous N-hydroxysuccinimide. The pH is adjusted to 5.5, and the mixture is stirred at room temperature for 30min to obtain an activated modifier solution. The activated modifier solution is then mixed with 100mL of anhydrous ethanol and stirred until homogeneous to obtain a mixed solution. Separately, 1.7g of dried chitosan powder is weighed and dispersed in 80mL of anhydrous ethanol, which is then directly transferred to the above mixed solution. The mixture is heated to 70℃ and reacted for 24h. After the reaction is completed, the mixture is naturally cooled to room temperature, filtered, washed, and dried to obtain the modified additive. The preparation process of the modifier is as follows: S1: Add 10g of eugenol to 120mL of anhydrous dichloromethane, stir well, add 7g of triethylamine, heat to 2.5℃ in an ice-water bath, slowly add 10g of tert-butyldimethylchlorosilane, stir at room temperature for 8h after the addition is complete, wash the reaction solution with deionized water several times, extract and separate the organic phase, dry with anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure to remove the solvent, recrystallize, and dry under low temperature vacuum to obtain intermediate A; S2: Under a nitrogen atmosphere, 10g of intermediate A, 6.8g of p-carboxybenzenesulfonamide, and 120mL of anhydrous toluene were mixed and stirred until homogeneous. The mixture was then heated to 115℃ and reacted for 8h. Subsequently, the temperature was lowered to 80℃, and 7.6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The temperature was further increased to 115℃ and refluxed for 8h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the modifier.

[0025] Comparative Example 1: No functional additives were added, as follows: A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments comprises, from the inside out, a conductor, an insulation layer, a composite shielding layer, and an outer sheath. The conductor is made of copper-clad aluminum monofilament with a diameter of 0.2 mm. After being drawn by a shaped cross-section die, stranded by a wire stranding machine, and compressed twice by a radial compression die, a cross-sectional area of ​​10 mm² is obtained. 2 A tightly compressed circular conductor; The insulating layer covers the outer periphery of the conductor and comprises, from the inside out, an inner insulating layer, a middle insulating layer, and an outer insulating layer; the inner insulating layer is a polyolefin material layer (thickness 0.1 mm), the middle insulating layer is a polyimide material layer (thickness 0.2 mm), and the outer insulating layer is a maleic anhydride-grafted polyethylene resin layer (thickness 0.1 mm). The composite shielding layer covers the outer periphery of the outer insulation layer and includes a silver-plated aluminum-plastic composite strip longitudinal wrapping layer and a tin-plated copper wire braided layer arranged sequentially from the inside to the outside. The outer protective layer covers the outer periphery of the composite shielding layer, and its preparation method is as follows: 30 parts of high-density polyethylene, 14 parts of low-density polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 1 part of antioxidant (antioxidant 1010), 1 part of lubricant (polyethylene wax) and 9 parts of filler (carbon black) are placed in a high-speed mixer and stirred and mixed at 1000 r / min for 20 min at room temperature to make the components uniformly mixed. Then, it is transferred to a twin-screw extruder and melt-blended and extruded at 160°C. After water cooling, pelletizing, and drying, the sheath material is obtained. Finally, the sheath material is extruded and coated on the outer periphery of the composite shielding layer to form the outer protective layer.

[0026] Comparative Example 2: An excessive amount of functional additives was added, as detailed below: A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments comprises, from the inside out, a conductor, an insulation layer, a composite shielding layer, and a weather-resistant and flame-retardant outer sheath. The conductor is made of copper-clad aluminum monofilament with a diameter of 0.2 mm. After being drawn by a shaped cross-section die, stranded by a wire stranding machine, and compressed twice by a radial compression die, a cross-sectional area of ​​10 mm² is obtained. 2 A tightly compressed circular conductor; The insulating layer covers the outer periphery of the conductor and comprises, from the inside out, an inner insulating layer, a middle insulating layer, and an outer insulating layer; the inner insulating layer is a polyolefin material layer (thickness 0.1 mm), the middle insulating layer is a polyimide material layer (thickness 0.2 mm), and the outer insulating layer is a maleic anhydride-grafted polyethylene resin layer (thickness 0.1 mm). The composite shielding layer covers the outer periphery of the outer insulation layer and includes a silver-plated aluminum-plastic composite strip longitudinal wrapping layer and a tin-plated copper wire braided layer arranged sequentially from the inside to the outside. The weather-resistant and flame-retardant outer sheath is coated around the outer periphery of the composite shielding layer. Its preparation method is as follows: 30 parts high-density polyethylene, 14 parts low-density polyethylene, 20 parts ethylene-vinyl acetate copolymer, 18 parts functional additives, 1 part antioxidant (antioxidant 1010), 1 part lubricant (polyethylene wax), and 9 parts filler (carbon black) are placed in a high-speed mixer and stirred at 1000 r / min for 20 minutes at room temperature to ensure uniform mixing. The mixture is then transferred to a twin-screw extruder and melt-blended at 160°C. After water cooling, pelletizing, and drying, the sheath material is obtained. Finally, the sheath material is extruded and coated around the outer periphery of the composite shielding layer to form the weather-resistant and flame-retardant outer sheath. The preparation process of the functional additive is as follows: 4.8g of modifier is added to 50mL of anhydrous N,N-dimethylformamide, followed by the sequential addition of 4.0g of anhydrous 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2.4g of anhydrous N-hydroxysuccinimide. The pH is adjusted to 5.5, and the mixture is stirred at room temperature for 30min to obtain an activated modifier solution. The activated modifier solution is then mixed with 100mL of anhydrous ethanol and stirred until homogeneous to obtain a mixed solution. Separately, 1.7g of dried chitosan powder is weighed and dispersed in 80mL of anhydrous ethanol, which is then directly transferred to the above mixed solution. The mixture is heated to 70℃ and reacted for 24h. After the reaction is completed, the mixture is naturally cooled to room temperature, filtered, washed, and dried to obtain the modified additive. The preparation process of the modifier is as follows: S1: Add 10g of eugenol to 120mL of anhydrous dichloromethane, stir well, add 7g of triethylamine, heat to 2.5℃ in an ice-water bath, slowly add 10g of tert-butyldimethylchlorosilane, stir at room temperature for 8h after the addition is complete, wash the reaction solution with deionized water several times, extract and separate the organic phase, dry with anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure to remove the solvent, recrystallize, and dry under low temperature vacuum to obtain intermediate A; S2: Under a nitrogen atmosphere, 10g of intermediate A, 6.8g of p-carboxybenzenesulfonamide, and 120mL of anhydrous toluene were mixed and stirred until homogeneous. The mixture was then heated to 115℃ and reacted for 8h. Subsequently, the temperature was lowered to 80℃, and 7.6g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The temperature was further increased to 115℃ and refluxed for 8h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the modifier.

[0027] Test Experiment (1): (1) The tensile strength of the outer sheath of the cables in the examples and comparative examples was tested in accordance with standard GB / T 2951.11-2008; (2) The outer sheath of the cables in the examples and comparative examples was subjected to a high-temperature test in accordance with standard GB / T 2406.2-2009 to determine its oxygen index; (3) The outer sheath of the cables in the examples and comparative examples was subjected to an accelerated aging test in accordance with the standard GB / T 16422.2-2022. Xenon arc lamps were used as the light source and the exposure time was 720h. The change rate of tensile strength before and after aging was measured. (4) The mass per unit length of the cables in the examples and comparative examples was measured in accordance with standard GB / T 2951.11-2008, and the mass per meter (g / m) was recorded. (5) Apply AC 1000V power frequency voltage to the cables of the examples and comparative examples for 5 minutes and observe whether breakdown occurs; (6) At room temperature, fix one end of the cable of the example and the comparative example on the fixed clamp of the testing machine and the other end on the rotating clamp. Set the torsion angle (±180°), the speed (30 times / min), and the target number of times (100,000 times). Start the testing machine to ensure that the cable axis coincides with the torsion axis. During the test, stop the machine every 10,000 times to check: observe whether there is cracking in the appearance; evaluate whether it passes after the test. Evaluation criteria: no cracks or twisting on the surface of the sample. The obtained data is shown in Table 1: Table 1

[0028] Conclusion: Based on the test results of the above embodiments and comparative examples, the following conclusions can be drawn: The lightweight high-voltage power cable for eVTOL suitable for low-pressure environments provided by the present invention significantly improves the overall performance of the cable by introducing functional additives with specific structures into the outer sheath.

[0029] The tensile strength of the sheaths in Examples 1 to 3 all reached over 26.8 MPa, significantly better than that of Comparative Example 1 (22.1 MPa) without functional additives. While Comparative Example 2 had slightly higher strength (28.1 MPa) due to excessive addition of functional additives, it failed the room temperature torsion test, indicating that excessive functional additives lead to decreased sheath toughness and insufficient resistance to repeated bending. Regarding flame retardant properties, the oxygen index of the examples was all above 32.5%, far superior to the 25.5% of Comparative Example 1, indicating that the synergistic flame retardant effect of phosphorus, nitrogen, and silicon was effectively achieved. After 720 hours of accelerated aging under a xenon arc lamp, the tensile strength change rate of the examples was controlled within -12.5%, significantly better than the -23.6% of Comparative Example 1, and also better than the -19.4% of Comparative Example 2 with excessive addition, proving that the ultraviolet absorbing groups in the functional additives can exist stably in the form of covalent bonds, giving the sheath excellent aging resistance. Meanwhile, the unit length mass of all embodiments remained at around 68 g / m, which is only slightly higher than Comparative Example 1, but much lower than 71.2 g / m of Comparative Example 2, demonstrating the advantages of lightweight design.

[0030] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0031] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments, characterized in that, From the inside out, it consists of a conductor, an insulating layer, a composite shielding layer, and a weather-resistant and flame-retardant outer sheath. The insulating layer covers the outer periphery of the conductor and includes, from the inside out, an inner insulating layer, a middle insulating layer, and an outer insulating layer; the inner insulating layer is a polyolefin material layer, the middle insulating layer is a polyimide material layer, and the outer insulating layer is a maleic anhydride-grafted polyethylene resin layer. The composite shielding layer covers the outer periphery of the outer insulation layer and includes a silver-plated aluminum-plastic composite strip longitudinal wrapping layer and a tin-plated copper wire braided layer arranged sequentially from the inside to the outside. The weather-resistant and flame-retardant outer protective layer covers the outer periphery of the composite shielding layer, and its raw materials include the following components in parts by weight: 28-36 parts high-density polyethylene, 13-15 parts low-density polyethylene, 15-22 parts ethylene-vinyl acetate copolymer, 12-15 parts functional additives, 0.8-1.5 parts antioxidants, 0.8-1.5 parts lubricants, and 8-10 parts fillers; The preparation process of the functional additive is as follows: the modifier is added to anhydrous N,N-dimethylformamide, and anhydrous 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and anhydrous N-hydroxysuccinimide are added sequentially. The pH is adjusted to 5.5, and the mixture is stirred at room temperature for 30 minutes to obtain an activated modifier solution. The activated modifier solution is mixed with anhydrous ethanol and stirred evenly to obtain a mixed solution. Dry chitosan powder is separately weighed and dispersed in anhydrous ethanol, and directly transferred to the above mixed solution. The temperature is raised to 70°C and the reaction is carried out for 24 hours. After the reaction is completed, the mixture is naturally cooled to room temperature, filtered, washed, and dried to obtain the modified additive. The ratio of the modifier, anhydrous 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, anhydrous N-hydroxysuccinimide, and chitosan powder is 4.8g:4.0g:2.4g:1.7g. The preparation process of the modifier is as follows: S1: Add eugenol to anhydrous dichloromethane, stir well, add triethylamine, heat to 0-5℃ in an ice-water bath, slowly add tert-butyldimethylchlorosilane, stir at room temperature for 8 hours after the addition is complete, wash the reaction solution with deionized water several times, extract and separate the organic phase, dry with anhydrous sodium sulfate, filter, concentrate the filtrate under reduced pressure to remove solvent, recrystallize, and dry under low temperature vacuum to obtain intermediate A; S2: Under a protective atmosphere, intermediate A, p-carboxybenzenesulfonamide, and anhydrous toluene were mixed and stirred until homogeneous. The mixture was then heated to 115°C and refluxed for 8 hours. Subsequently, the temperature was lowered to 80°C, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. The temperature was then raised to 115°C and refluxed for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the modifier.

2. The lightweight high-voltage power cable for eVTOL suitable for low-pressure environments according to claim 1, characterized in that, In S1, the ratio of eugenol, anhydrous dichloromethane, triethylamine, and tert-butyldimethylchlorosilane is 10g:120mL:7g:10g.

3. A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments according to claim 1, characterized in that, In S2, the ratio of intermediate A, p-carboxybenzenesulfonamide, anhydrous toluene, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 10g:6.8g:120mL:7.6g.

4. A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments according to claim 1, characterized in that, The antioxidant is antioxidant 1010.

5. A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments according to claim 1, characterized in that, The lubricant is polyethylene wax.

6. A lightweight high-voltage power cable for eVTOL suitable for low-pressure environments according to claim 1, characterized in that, The filler is one or more of carbon black, montmorillonite, and calcium carbonate.

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