A cable for DC charging system of new energy vehicles

Abstract

The present invention relates to the field of charging cables and discloses a cable for a DC charging system of a new energy vehicle. The cable comprises, from the inside to the outside, an inner lining layer, a shielding layer, and a sheath layer. The inner lining layer is provided with two power cores, one ground cable core, one signal control core, and two auxiliary power cores. The power core comprises a conductor and an insulating layer extruded on the outer surface of the conductor. The signal control core is provided with two signal cores. The outer surfaces of the signal cores are sequentially covered with an aluminum-plastic composite tape shielding layer and a copper wire braided shielding layer. The sheath layer is prepared by drawing a sheath layer material out of the outer periphery of the shielding layer through an extrusion device. The sheath layer material comprises: polyvinyl chloride, nitrile rubber, ethylene-tetrafluoroethylene copolymer, modified aramid fiber, modified nano titanium dioxide, a stabilizer, a plasticizer, and a lubricant. The present invention imparts excellent flame retardant properties, high-temperature aging resistance, and mechanical properties to the material by adding modified aramid fiber and modified nano titanium dioxide.

Description

Technical Field

[0001] The present invention belongs to the technical field of charging cables, and in particular relates to a cable for a DC charging system of a new energy vehicle. Background Art

[0002] New energy vehicles (NEVs) use unconventional fuels as their power source (or use conventional fuels with new onboard power units), integrating advanced technologies in vehicle power control and drive to create vehicles with advanced technical principles, new technologies, and new structures. New energy vehicles include pure electric vehicles, extended-range electric vehicles, hybrid vehicles, fuel cell electric vehicles, and hydrogen engine vehicles. Compared to traditional vehicles, new energy vehicles offer smooth operation, quiet operation, zero pollution, low carbon emissions, and enhanced safety, resulting in broad market application prospects.

[0003] Among them, pure electric vehicles, extended-range electric vehicles and other rechargeable vehicles have incomparable advantages over traditional vehicles in terms of energy conservation and emission reduction, and reducing human dependence on traditional petroleum energy, and have become a new generation of transportation. The rise of rechargeable vehicles has greatly promoted the development of charging piles, and charging pile cables are an important component of charging piles. The demand for electric vehicle charging pile cables has also doubled. DC charging pile cables usually use high-voltage DC cables, which can withstand higher currents and voltages to meet the needs of fast charging.

[0004] The primary cause of failure for existing charging cables used in new energy vehicles is the failure of the sheath material, which in turn is primarily due to heat generation from the conductor's current-carrying load and environmental influences. Therefore, the high-temperature aging resistance of the sheath material plays a crucial role in the cable's service life, ensuring that the cable does not soften, melt, or thermally decompose in high-temperature environments. Furthermore, during the use of electric vehicle charging piles, the cable may be exposed to external fire sources. Therefore, the cable's flame retardancy is an important indicator for ensuring the safety of the charging pile and the surrounding environment. The cable's flame retardancy primarily depends on the choice of sheath material. Furthermore, the cable is subject to tensile and impact forces, so the cable's tensile and impact resistance are crucial indicators for ensuring a secure charging pile connection and preventing the cable from breaking. Summary of the Invention

[0005] In order to address the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a cable for a DC charging system of a new energy vehicle. By adding modified aramid fiber and modified nano-titanium dioxide, the material is given excellent flame retardant properties, high temperature aging resistance and mechanical properties.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A cable for a DC charging system of a new energy vehicle, comprising, from the inside out, an inner lining layer, a shielding layer, and a sheath layer. The inner lining layer is provided with two power cores, one ground cable core, one signal control core, and two auxiliary power cores. The power core comprises a conductor and an insulating layer extruded on the outer surface of the conductor. The signal control core is provided with two signal cores. The outer surfaces of the signal cores are sequentially coated with an aluminum-plastic composite tape shielding layer and a copper wire braided shielding layer. A filling layer is provided in the gaps between the inner lining layer and the power core, ground cable core, signal control core, and auxiliary power core.

[0008] The sheath layer is prepared by drawing a sheath layer material around the shielding layer through an extrusion device; the sheath layer material comprises the following raw materials in parts by weight: 50-70 parts of polyvinyl chloride, 20-30 parts of nitrile rubber, 5-15 parts of ethylene-tetrafluoroethylene copolymer, 3-8 parts of modified aramid fiber, 2-5 parts of modified nano titanium dioxide, 3-7 parts of stabilizer, 4-10 parts of plasticizer, and 2.5-5 parts of lubricant;

[0009] The modified aramid fiber is made by grafting a modified silane coupling agent prepared by a ring-opening reaction between a modifying additive and 3-(2,3-epoxypropoxy)propyltrimethoxysilane onto the surface of the aramid fiber; wherein the modified additive is made by a substitution reaction between a flame retardant additive prepared by an addition reaction between 5,10-dihydrophosphazizine-10-oxide and 4-maleimidophenol and a phosphorus-containing intermediate; wherein the phosphorus-containing intermediate is made by a substitution reaction between diphenylphosphinyl chloride and 1,3-dimethoxy-2-propanol;

[0010] The modified nano titanium dioxide is prepared by grafting an antioxidant coupling agent onto the surface of the nano titanium dioxide through a chemical reaction; the antioxidant coupling agent is prepared by a hindered phenol antioxidant component prepared by a thiol-ene click reaction between pentaerythritol tetraacrylate and 2,6-di-tert-butyl-4-mercaptophenol, and further prepared by a thiol-ene click reaction between the hindered phenol antioxidant component and 3-mercaptopropyltriethoxysilane.

[0011] Preferably, the method for preparing the modified aramid fiber comprises the following steps:

[0012] (1) 5,10-dihydrophosphazizine-10-oxide, 4-maleimidophenol and N,N-dimethylformamide were placed in a reactor, stirred and mixed at 75-85°C, then heated to 95-115°C, and stirred and reacted for 20-24 hours. After the reaction was completed, the mixture was cooled to room temperature, added to ethyl acetate for precipitation, and finally filtered, washed and dried to prepare a flame retardant additive.

[0013] (2) Diphenylphosphine chloride and 1,3-dimethoxy-2-propanol were placed in a reactor, tetrahydrofuran was added, and the mixture was stirred for 4 to 6 hours. Triethylamine was added during the reaction to remove the hydrogen chloride produced by the reaction. After the reaction was completed, the mixture was filtered, rotary evaporated, and dried to obtain a phosphorus-containing intermediate.

[0014] (3) Put the flame retardant additive and dimethyl sulfoxide in a reactor, add the phosphorus-containing intermediate and sodium hydroxide, stir and react at 150-160°C for 10-12 hours, cool to 100-105°C after the reaction is completed, and then place at 195-200°C for vacuum rotary evaporation for 2-3 hours to prepare the modified additive;

[0015] (4) Place the modified additive and tetrahydrofuran in a reactor, then add 3-(2,3-epoxypropoxy)propyltrimethoxysilane and triphenylphosphine, and stir the reaction at 85-100°C for 6-12 hours. After the reaction is completed, filter, wash, and dry to obtain a modified silane coupling agent.

[0016] (5) The aramid fiber was placed in acetone, ultrasonically shaken for 0.5-1 h, and then filtered under reduced pressure. The fiber was washed with anhydrous ethanol and dried. The fiber was then oxidized with a 25-30% phosphoric acid solution at 35-50 °C for 3-8 min to prepare the pretreated aramid fiber.

[0017] (6) Take the modified silane coupling agent, anhydrous ethanol and deionized water in a reactor, put the pretreated aramid fiber into it and fully immerse it, ultrasonically vibrate it for 0.5~1h, and then place it at 45~60℃ and stir it for 2~3h. After the reaction is completed, filter, wash and dry it to prepare the modified aramid fiber.

[0018] Preferably, in step (1), the molar ratio of 5,10-dihydrophosphazizine-10-oxide to 4-maleimidophenol is 1:1-1.2; and in step (2), the molar ratio of diphenylphosphine chloride to 1,3-dimethoxy-2-propanol is 1:1-1.2.

[0019] Preferably, the molar ratio of the flame retardant additive to the phosphorus-containing intermediate in step (3) is 2-2.1:1; and the molar ratio of the modifying additive to 3-(2,3-epoxypropoxy)propyltrimethoxysilane in step (4) is 1:2-2.3.

[0020] Preferably, the structural formula of 5,10-dihydrophosphazizine-10-oxide in step (1) is as follows:

[0021] ;

[0022] The preparation method comprises the following steps:

[0023] A mixture of diphenylamine and phosphorus trichloride is stirred at room temperature for 25 to 40 minutes, then heated to 200 to 210°C and stirred for 7 to 8 hours. After stirring, the mixture is cooled to room temperature and flushed with nitrogen to remove hydrochloric acid and residual phosphorus trichloride. The obtained brown solid product is powdered and added to boiling water and stirred for 2 to 2.5 hours. The obtained solid is then dissolved in hot ethanol and filtered to remove insoluble components. The filtrate is treated with an aqueous sodium hydroxide solution to precipitate a yellow substance. The ethanol is then evaporated to obtain a crude product. The crude product is washed with deionized water, recrystallized using glacial acetic acid, and dried in vacuo to prepare 5,10-dihydrophosphazine-10-oxide.

[0024] Preferably, the preparation method of the modified nano-titanium dioxide comprises the following steps:

[0025] A. Pentaerythritol tetraacrylate, tetrahydrofuran, and triethylamine are placed in a reactor, nitrogen is introduced, 2,6-di-tert-butyl-4-mercaptophenol is added, and the mixture is stirred at 40-55° C. for 20-24 hours. The reaction product is precipitated into petroleum ether, and the precipitated product is dried to prepare a hindered phenol antioxidant component;

[0026] B. Take the hindered phenol antioxidant component and 3-mercaptopropyltriethoxysilane in a reactor, add acetone solvent, heat to 40-50°C under a nitrogen atmosphere, and then add triethylamine to react for 4-5 hours to prepare an antioxidant coupling agent;

[0027] C. Ultrasonic dispersion of nano-titanium dioxide in a mixed solution of ethanol and deionized water to obtain a suspension, and the pH value of the system is adjusted to 9-11 with ammonia water. Then, an antioxidant coupling agent is added to the suspension under a nitrogen atmosphere, and the suspension is stirred at 50-65°C for 4-5 hours. After the reaction is completed, the suspension is centrifuged, washed, and dried to obtain modified nano-titanium dioxide.

[0028] Preferably, in step A, the molar ratio of pentaerythritol tetraacrylate to 2,6-di-tert-butyl-4-mercaptophenol is 1:3-3.5.

[0029] Preferably, in step B, the molar ratio of the hindered phenol antioxidant component to 3-mercaptopropyltriethoxysilane is 1:1-1.2.

[0030] Preferably, the plasticizer is any one of dimethyl phthalate, dioctyl phthalate, and diisodecyl phthalate; the stabilizer is one of calcium zinc stabilizer and organic tin stabilizer; and the lubricant is one of polyethylene wax and oxidized polyethylene wax.

[0031] Preferably, the preparation method of the sheath layer material comprises the following steps: weighing each raw material by weight, uniformly mixing polyvinyl chloride, nitrile rubber, ethylene-tetrafluoroethylene copolymer, modified aramid fiber, modified nano titanium dioxide, stabilizer, plasticizer and lubricant to obtain a mixture, placing the mixture into a twin-screw extruder for extrusion molding to prepare the sheath layer material.

[0032] Beneficial effects of the present invention:

[0033] The invention utilizes the PH bond in 5,10-dihydrophosphazizine-10-oxide and the double bond in 4-maleimidophenol to undergo an addition reaction to prepare a flame retardant additive. Simultaneously, the invention utilizes the chlorine atom in diphenylphosphinyl chloride and the hydroxyl group in 1,3-dimethoxy-2-propanol to undergo a substitution reaction to prepare a phosphorus-containing intermediate. Then, the hydroxyl group in the prepared flame retardant additive and the methoxy group in the phosphorus-containing intermediate undergo a substitution reaction to release methanol to prepare a modified additive. Then, the -NH group in the modified additive and the epoxy group in 3-(2,3-epoxypropoxy)propyltrimethoxysilane undergo a ring-opening reaction to prepare the flame retardant additive. A modified silane coupling agent containing phosphorus, nitrogen and ether bonds is added, and the silicon hydroxyl groups in the modified silane coupling agent are further condensed with the hydroxyl groups on the surface of the aramid fiber to prepare a modified aramid fiber, wherein the aramid fiber has excellent properties such as high strength, high modulus, good heat resistance and low density. The modified silane coupling agent is grafted onto the surface of the aramid fiber through a strong chemical bond, which improves the interface compatibility between the aramid fiber and the matrix material and is beneficial to the development of its mechanical properties. At the same time, the grafted phosphorus and nitrogen elements play a synergistic flame retardant role to achieve a long-term flame retardant effect, and the introduced ether bond increases the flexibility of the molecule, which is beneficial to improving the impact resistance of the cable.

[0034] The present invention utilizes a thiol-ene click reaction between the double bonds in pentaerythritol tetraacrylate and the thiol groups in three 2,6-di-tert-butyl-4-mercaptophenol antioxidant molecules to prepare a hindered phenol antioxidant component. The ungrafted double bonds in the hindered phenol antioxidant component are then subjected to a thiol-ene click reaction with 3-mercaptopropyltriethoxysilane to prepare an antioxidant coupling agent. This antioxidant coupling agent is then subjected to a hydrolysis-condensation reaction with nano-titanium dioxide to graft the hindered phenol antioxidant component onto the surface of the nano-titanium dioxide. The prepared modified nano-titanium dioxide has improved dispersibility, providing a better reinforcement effect on the base material. The grafting reaction also inhibits the migration and precipitation of the hindered phenol antioxidant component, thereby enhancing the long-term antioxidant capacity of the sheath layer material. The sheath layer material of the present invention utilizes polyvinyl chloride, nitrile rubber, and ethylene-tetrafluoroethylene copolymer as base materials. By adding modified aramid fiber and modified nano-titanium dioxide, the material is endowed with excellent flame retardancy, high-temperature aging resistance, and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] Figure 1 It is a structural schematic diagram of the cable for the DC charging system of new energy vehicles of the present invention.

[0037] In the figure: 1- lining layer, 2- shielding layer, 3- sheath layer, 4- conductor, 5- insulation layer, 6- signal core, 7- aluminum-plastic composite tape shielding layer, 8- copper wire braided shielding layer, 9- ground cable core, 10- auxiliary power core. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] like Figure 1 As shown, a cable for a DC charging system of a new energy vehicle comprises, from the inside to the outside, a non-woven fabric lining layer 1, a copper wire braided shielding layer 2 with a diameter of 0.25 mm, and a sheath layer 3. The inner lining layer 1 is provided with two power cores, one ground cable core 9, one signal control core, and two auxiliary power cores 10. The power core comprises a conductor 4 and a cross-linked polyethylene insulation layer 5 extruded on the outer surface of the conductor 4. The signal control core is provided with two signal cores 6. The outer surface of the signal core 6 is sequentially covered with an aluminum-plastic composite tape shielding layer 7 with a thickness of 0.1 mm and a copper wire braided shielding layer 8 with a diameter of 0.15 mm, with a braiding density of 80%. The gaps between the inner lining layer 1 and the power core, ground cable core 9, signal control core, and auxiliary power core 10 are filled with a polypropylene filling rope filling layer.

[0040] Example 1 A method for preparing modified aramid fiber comprises the following steps:

[0041] (1) 2.1 g of 5,10-dihydrophosphazizine-10-oxide, 1.9 g of 4-maleimidophenol and 15 mL of N,N-dimethylformamide were placed in a reactor, stirred and mixed uniformly at 80 ° C, then heated to 110 ° C, and stirred and reacted for 24 h. After the reaction was completed, the mixture was cooled to room temperature and added to 300 mL of ethyl acetate for precipitation. Finally, the mixture was filtered, washed and dried to prepare a flame retardant additive.

[0042] (2) 2.3 g of diphenylphosphinoyl chloride and 1.4 g of 1,3-dimethoxy-2-propanol were placed in a reactor, 100 mL of tetrahydrofuran was added, and the mixture was stirred for 6 h. During the reaction, 1 g of triethylamine was added to remove the hydrogen chloride produced by the reaction. After the reaction was completed, the mixture was filtered, rotary evaporated, and dried to obtain a phosphorus-containing intermediate.

[0043] (3) 3.8 g of flame retardant additive (Mr = 404.2) and 50 mL of dimethyl sulfoxide were placed in a reactor, 1.5 g of phosphorus-containing intermediate (Mr = 320.3) and 0.4 g of sodium hydroxide were added, and the mixture was stirred at 160 ° C for 12 h. After the reaction was completed, it was cooled to 100 ° C, and then placed at 200 ° C for vacuum rotary evaporation for 2.5 h to prepare the modified additive;

[0044] (4) 5.3 g of the modified additive (Mr = 1064.7) and 50 mL of tetrahydrofuran were placed in a reactor, and then 2.4 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.01 g of triphenylphosphine were added. The mixture was stirred at 90 °C for 8 h. After the reaction was completed, the mixture was filtered, washed, and dried to prepare a modified silane coupling agent.

[0045] (5) 5 g of aramid fiber was dissolved in 50 mL of acetone, ultrasonically shaken for 0.5 h, and then filtered under reduced pressure. The fiber was washed with anhydrous ethanol and dried. The fiber was then oxidized with 30% phosphoric acid solution at 40 °C for 5 min to prepare pretreated aramid fiber.

[0046] (6) Take 3.7 g of modified silane coupling agent, 50 mL of anhydrous ethanol and 100 mL of deionized water in a reactor, put 5 g of pretreated aramid fiber into it and fully immerse it, ultrasonically vibrate it for 1 hour, and then place it at 55 ° C and stir it for 2 hours. After the reaction is completed, filter, wash and dry it to prepare modified aramid fiber.

[0047] The preparation method of 5,10-dihydrophospharazine-10-oxide in step (1) is as follows: a mixture of 50.8 g of diphenylamine and 43.9 g of phosphorus trichloride is stirred at room temperature for 30 min, then heated to 210° C. and stirred for 7 h. After stirring, the mixture is cooled to room temperature, flushed with nitrogen to remove hydrochloric acid and residual phosphorus trichloride, the obtained brown solid product is powdered, added to 100 mL of boiling water and stirred for 2 h, and then the obtained solid is dissolved in hot ethanol and filtered to remove insoluble components. The filtrate is treated with a 10% sodium hydroxide aqueous solution to precipitate a yellow substance, and then the ethanol is evaporated to obtain a crude product. The crude product is washed with deionized water, recrystallized using glacial acetic acid and vacuum dried to prepare 5,10-dihydrophospharazine-10-oxide.

[0048] Example 2 A method for preparing modified nano-titanium dioxide comprises the following steps:

[0049] A. 10 g of pentaerythritol tetraacrylate, 100 mL of tetrahydrofuran, and 0.5 g of triethylamine were placed in a reactor, nitrogen was introduced, 20.3 g of 2,6-di-tert-butyl-4-mercaptophenol was added, and the mixture was stirred at 45 ° C for 24 h. The reaction product was precipitated into 100 mL of petroleum ether, and the precipitated product was dried to prepare a hindered phenol antioxidant component;

[0050] B. Take 10.6g of hindered phenol antioxidant component (Mr=1067.5) and 2.4g of 3-mercaptopropyltriethoxysilane in a reactor, add 120mL of acetone solvent, heat to 45°C under a nitrogen atmosphere, then add 0.5g of triethylamine and react for 5h to prepare an antioxidant coupling agent;

[0051] C. Take 5 g of nano-titanium dioxide and ultrasonically disperse it in a mixed solution of 90 mL of ethanol and 20 mL of deionized water to obtain a suspension. Use ammonia water to adjust the pH value of the system to 10. Then, add 2.4 g of antioxidant coupling agent to the suspension under a nitrogen atmosphere, place it at 60°C and stir to react for 4 hours. After the reaction is completed, centrifuge, wash, and dry to prepare modified nano-titanium dioxide.

[0052] Example 3 A sheath layer material includes the following raw materials in parts by weight: 54 parts of polyvinyl chloride, 21 parts of nitrile rubber, 6 parts of ethylene-tetrafluoroethylene copolymer, 3 parts of modified aramid fiber prepared in Example 1, 2 parts of modified nano titanium dioxide prepared in Example 2, 3 parts of calcium zinc stabilizer, 4.5 parts of plasticizer dimethyl phthalate, and 2.5 parts of lubricant polyethylene wax.

[0053] The preparation method of the above-mentioned sheath layer material includes the following steps: weighing each raw material by weight, uniformly mixing polyvinyl chloride, nitrile rubber, ethylene-tetrafluoroethylene copolymer, modified aramid fiber, modified nano titanium dioxide, stabilizer, plasticizer and lubricant to obtain a mixture, placing the mixture into a twin-screw extruder for extrusion molding to prepare the sheath layer material.

[0054] Example 4 A sheath layer material includes the following raw materials in parts by weight: 60 parts of polyvinyl chloride, 23 parts of nitrile rubber, 10 parts of ethylene-tetrafluoroethylene copolymer, 5 parts of modified aramid fiber prepared in Example 1, 4 parts of modified nano titanium dioxide prepared in Example 2, 4 parts of calcium zinc stabilizer, 6 parts of plasticizer dioctyl phthalate, and 3 parts of lubricant oxidized polyethylene wax.

[0055] The preparation method of the above-mentioned sheath layer material is the same as that of Example 3.

[0056] Example 5 A sheath layer material includes the following raw materials in parts by weight: 66 parts of polyvinyl chloride, 27 parts of nitrile rubber, 12 parts of ethylene-tetrafluoroethylene copolymer, 7 parts of modified aramid fiber prepared in Example 1, 5 parts of modified nano titanium dioxide prepared in Example 2, 6 parts of calcium zinc stabilizer, 9 parts of plasticizer dioctyl phthalate, and 4.5 parts of lubricant oxidized polyethylene wax.

[0057] The preparation method of the above-mentioned sheath layer material is the same as that of Example 3.

[0058] Comparative Example 1 A method for preparing modified aramid fiber comprises the following steps:

[0059] (1) 2.1 g of 5,10-dihydrophosphazizine-10-oxide, 1.9 g of 4-maleimidophenol and 15 mL of N,N-dimethylformamide were placed in a reactor, stirred and mixed uniformly at 80 ° C, then heated to 110 ° C, and stirred and reacted for 24 h. After the reaction was completed, the mixture was cooled to room temperature and added to 300 mL of ethyl acetate for precipitation. Finally, the mixture was filtered, washed and dried to prepare a flame retardant additive.

[0060] (2) 2 g of flame retardant additive (Mr = 404.2) and 50 mL of tetrahydrofuran were placed in a reactor, and then 2.4 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.01 g of triphenylphosphine were added. The mixture was stirred at 90 °C for 8 h. After the reaction was completed, the mixture was filtered, washed, and dried to prepare a modified silane coupling agent.

[0061] (3) 5 g of aramid fiber was dissolved in 50 mL of acetone, ultrasonically shaken for 0.5 h, and then filtered under reduced pressure. The fiber was washed with anhydrous ethanol and dried. The fiber was then oxidized with 30% phosphoric acid solution at 40 °C for 5 min to prepare pretreated aramid fiber.

[0062] (4) Take 3.7 g of modified silane coupling agent, 50 mL of anhydrous ethanol and 100 mL of deionized water in a reactor, put 5 g of pretreated aramid fiber into it and fully immerse it, ultrasonically vibrate it for 1 hour, and then place it at 55 ° C and stir it for 2 hours. After the reaction is completed, filter, wash and dry it to prepare modified aramid fiber.

[0063] The preparation method of 5,10-dihydrophospharazine-10-oxide in step (1) is as follows: a mixture of 50.8 g of diphenylamine and 43.9 g of phosphorus trichloride is stirred at room temperature for 30 min, then heated to 210° C. and stirred for 7 h. After stirring, the mixture is cooled to room temperature, flushed with nitrogen to remove hydrochloric acid and residual phosphorus trichloride, the obtained brown solid product is powdered, added to 100 mL of boiling water and stirred for 2 h, and then the obtained solid is dissolved in hot ethanol and filtered to remove insoluble components. The filtrate is treated with a 10% sodium hydroxide aqueous solution to precipitate a yellow substance, and then the ethanol is evaporated to obtain a crude product. The crude product is washed with deionized water, recrystallized using glacial acetic acid and vacuum dried to prepare 5,10-dihydrophospharazine-10-oxide.

[0064] Comparative Example 2 A sheath layer material includes the following raw materials in parts by weight: 66 parts of polyvinyl chloride, 27 parts of nitrile rubber, 12 parts of ethylene-tetrafluoroethylene copolymer, 7 parts of modified aramid fiber prepared in Comparative Example 1, 5 parts of modified nano titanium dioxide prepared in Example 2, 6 parts of calcium zinc stabilizer, 9 parts of plasticizer dioctyl phthalate, and 4.5 parts of lubricant oxidized polyethylene wax.

[0065] The preparation method of the above-mentioned sheath layer material is the same as that of Example 3.

[0066] Comparative Example 3 A sheath layer material includes the following raw materials in parts by weight: 66 parts of polyvinyl chloride, 27 parts of nitrile rubber, 12 parts of ethylene-tetrafluoroethylene copolymer, 7 parts of aramid fiber, 5 parts of modified nano-titanium dioxide prepared in Example 2, 6 parts of calcium zinc stabilizer, 9 parts of plasticizer dioctyl phthalate, and 4.5 parts of lubricant oxidized polyethylene wax.

[0067] The preparation method of the above-mentioned sheath layer material is the same as that of Example 3.

[0068] Comparative Example 4 A sheath layer material includes the following raw materials in parts by weight: 66 parts of polyvinyl chloride, 27 parts of nitrile rubber, 12 parts of ethylene-tetrafluoroethylene copolymer, 7 parts of modified aramid fiber prepared in Example 1, 5 parts of nano-titanium dioxide, 6 parts of calcium zinc stabilizer, 9 parts of plasticizer dioctyl phthalate, and 4.5 parts of lubricant oxidized polyethylene wax.

[0069] The preparation method of the above-mentioned sheath layer material is the same as that of Example 3.

[0070] Performance testing

[0071] The performance of the sheath layer materials prepared in Examples 3-5 and Comparative Examples 2-4 was tested:

[0072] (1) Flame retardant performance test: The flame retardant performance of the samples was evaluated by referring to the limiting oxygen index of the test samples in GB / T 2406.2-2009. The data results are shown in Table 1.

[0073] Table 1 Flame retardant performance test results of samples

[0074]

[0075] The data in Table 1 demonstrate that the jacket layer materials prepared in Examples 3-5 and Comparative Example 4 exhibit excellent flame retardancy. Comparative Example 2, in which the modified aramid fiber was added without the introduction of a phosphorus-containing intermediate, exhibited a lower limiting oxygen index than that of Examples 3-5. This is because the phosphorus in the phosphorus-containing intermediate further enhances the flame retardancy of the material. Comparative Example 3, in which the aramid fiber was not modified, exhibited a significantly lower limiting oxygen index than that of Examples 3-5, demonstrating that the grafting of the modified silane coupling agent significantly enhances the flame retardancy of the material.

[0076] (2) Mechanical properties and high temperature aging resistance test: The tensile properties were tested with reference to GB / T 1040.2-2022; and the change rate of tensile strength and elongation at break was tested after aging at 110°C for 168 h; the impact strength was tested with reference to GB / T1843-2008, and the data results are shown in Table 2.

[0077] Table 2 Test results of mechanical properties and high temperature aging resistance of samples

[0078]

[0079] As can be seen from the data in Table 2, the sheath layer materials prepared in Examples 3-5 of the present invention have high tensile strength and impact strength, and still have high tensile strength after aging at 110°C for 168 hours, and have excellent high-temperature aging resistance. Among them, the modified aramid fiber added in Comparative Example 2 does not introduce a phosphorus-containing intermediate, and its measured impact strength is lower than that of Examples 3-5. This may be due to the fact that no ether bond is introduced into the modified aramid fiber structure, the aramid fiber is not modified in Comparative Example 3, and the nano-titanium dioxide is not modified in Comparative Example 4. The tensile strength, elongation at break, and impact strength of Comparative Example 3-4 are lower than those of Examples 3-5. This is because the dispersibility and interfacial compatibility of the aramid fiber and the nano-titanium dioxide are poor, resulting in reduced mechanical properties. The measured change rate of tensile strength and elongation at break of Comparative Example 4 are significantly different from those of Examples 3-5. This is because the hindered phenol antioxidant component is not grafted into the nano-titanium dioxide structure.

[0080] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0081] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A cable for a DC charging system of a new energy vehicle, characterized in that: The cable comprises an inner lining layer, a shielding layer, and a sheath layer from the inside to the outside, wherein two power cores, one ground cable core, one signal control core, and two auxiliary power cores are arranged in the inner lining layer, wherein the power core comprises a conductor and an insulating layer extruded on the outer surface of the conductor, and the signal control core is provided with two signal cores, and the outer surface of the signal core is sequentially coated with an aluminum-plastic composite tape shielding layer and a copper wire braided shielding layer, and the gaps between the inner lining layer and the power core, the ground cable core, the signal control core, and the auxiliary power core are filled with a filling layer; The sheath layer is prepared by drawing a sheath layer material around the shielding layer through an extrusion device; the sheath layer material comprises the following raw materials in parts by weight: 50-70 parts of polyvinyl chloride, 20-30 parts of nitrile rubber, 5-15 parts of ethylene-tetrafluoroethylene copolymer, 3-8 parts of modified aramid fiber, 2-5 parts of modified nano titanium dioxide, 3-7 parts of stabilizer, 4-10 parts of plasticizer, and 2.5-5 parts of lubricant; The modified nano-titanium dioxide is prepared by grafting an antioxidant coupling agent onto the surface of the nano-titanium dioxide through a chemical reaction; the antioxidant coupling agent is prepared by a hindered phenol antioxidant component prepared by a thiol-ene click reaction between pentaerythritol tetraacrylate and 2,6-di-tert-butyl-4-mercaptophenol, and further by a thiol-ene click reaction between the hindered phenol antioxidant component and 3-mercaptopropyltriethoxysilane; The preparation method of the modified aramid fiber comprises the following steps: (1) 5,10-dihydrophosphazizine-10-oxide, 4-maleimidophenol and N,N-dimethylformamide were placed in a reactor, stirred and mixed at 75-85°C, then heated to 95-115°C, and stirred and reacted for 20-24 hours. After the reaction was completed, the mixture was cooled to room temperature, added to ethyl acetate for precipitation, and finally filtered, washed and dried to prepare a flame retardant additive. (2) Diphenylphosphine chloride and 1,3-dimethoxy-2-propanol were placed in a reactor, tetrahydrofuran was added, and the mixture was stirred for 4 to 6 hours. Triethylamine was added during the reaction to remove the hydrogen chloride produced by the reaction. After the reaction was completed, the mixture was filtered, rotary evaporated, and dried to obtain a phosphorus-containing intermediate. (3) Put the flame retardant additive and dimethyl sulfoxide in a reactor, add the phosphorus-containing intermediate and sodium hydroxide, stir and react at 150-160°C for 10-12 hours, cool to 100-105°C after the reaction is completed, and then place at 195-200°C for vacuum rotary evaporation for 2-3 hours to prepare the modified additive; (4) Place the modified additive and tetrahydrofuran in a reactor, then add 3-(2,3-epoxypropoxy)propyltrimethoxysilane and triphenylphosphine, and stir the reaction at 85-100°C for 6-12 hours. After the reaction is completed, filter, wash, and dry to obtain a modified silane coupling agent. (5) The aramid fiber was placed in acetone, ultrasonically shaken for 0.5-1 h, and then filtered under reduced pressure. The fiber was washed with anhydrous ethanol and dried. The fiber was then oxidized with a 25-30% phosphoric acid solution at 35-50 °C for 3-8 min to prepare the pretreated aramid fiber. (6) Take the modified silane coupling agent, anhydrous ethanol and deionized water in a reactor, put the pretreated aramid fiber into it and fully immerse it, ultrasonically vibrate it for 0.5~1h, and then place it at 45~60℃ and stir it for 2~3h. After the reaction is completed, filter, wash and dry it to prepare the modified aramid fiber.

2. The cable for the DC charging system of new energy vehicles according to claim 1, characterized in that: In the step (1), the molar ratio of 5,10-dihydrophosphazizine-10-oxide to 4-maleimidophenol is 1:1-1.2; and in the step (2), the molar ratio of diphenylphosphine chloride to 1,3-dimethoxy-2-propanol is 1:1-1.

2.

3. The cable for the DC charging system of new energy vehicles according to claim 1, characterized in that: The molar ratio of the flame retardant additive to the phosphorus-containing intermediate in step (3) is 2-2.1:1; the molar ratio of the modifying additive to 3-(2,3-epoxypropoxy)propyltrimethoxysilane in step (4) is 1:2-2.

3.

4. The cable for the DC charging system of new energy vehicles according to claim 1, characterized in that: The structural formula of 5,10-dihydrophosphazizine-10-oxide in step (1) is as follows: ； The preparation method comprises the following steps: A mixture of diphenylamine and phosphorus trichloride is stirred at room temperature for 25 to 40 minutes, then heated to 200 to 210°C and stirred for 7 to 8 hours. After stirring, the mixture is cooled to room temperature and flushed with nitrogen to remove hydrochloric acid and residual phosphorus trichloride. The obtained brown solid product is powdered and added to boiling water and stirred for 2 to 2.5 hours. The obtained solid is then dissolved in hot ethanol and filtered to remove insoluble components. The filtrate is treated with an aqueous sodium hydroxide solution to precipitate a yellow substance. The ethanol is then evaporated to obtain a crude product. The crude product is washed with deionized water, recrystallized using glacial acetic acid, and dried in vacuo to prepare 5,10-dihydrophosphazine-10-oxide.

5. The cable for the DC charging system of new energy vehicles according to claim 1, characterized in that: The preparation method of the modified nano titanium dioxide comprises the following steps: A. Pentaerythritol tetraacrylate, tetrahydrofuran, and triethylamine are placed in a reactor, nitrogen is introduced, 2,6-di-tert-butyl-4-mercaptophenol is added, and the mixture is stirred at 40-55° C. for 20-24 hours. The reaction product is precipitated into petroleum ether, and the precipitated product is dried to prepare a hindered phenol antioxidant component; B. Take the hindered phenol antioxidant component and 3-mercaptopropyltriethoxysilane in a reactor, add acetone solvent, heat to 40-50°C under a nitrogen atmosphere, and then add triethylamine to react for 4-5 hours to prepare an antioxidant coupling agent; C. Ultrasonic dispersion of nano-titanium dioxide in a mixed solution of ethanol and deionized water to obtain a suspension, and the pH value of the system is adjusted to 9-11 with ammonia water. Then, an antioxidant coupling agent is added to the suspension under a nitrogen atmosphere, and the suspension is stirred at 50-65°C for 4-5 hours. After the reaction is completed, the suspension is centrifuged, washed, and dried to obtain modified nano-titanium dioxide.

6. The cable for the DC charging system of new energy vehicles according to claim 5, characterized in that: In the step A, the molar ratio of pentaerythritol tetraacrylate to 2,6-di-tert-butyl-4-mercaptophenol is 1:3-3.

5.

7. The cable for the DC charging system of new energy vehicles according to claim 5, characterized in that: The molar ratio of the hindered phenol antioxidant component to 3-mercaptopropyltriethoxysilane in step B is 1:1-1.

2.

8. The cable for the DC charging system of new energy vehicles according to claim 1, characterized in that: The plasticizer is any one of dimethyl phthalate, dioctyl phthalate, and diisodecyl phthalate; the stabilizer is one of calcium zinc stabilizer and organic tin stabilizer; and the lubricant is one of polyethylene wax and oxidized polyethylene wax.

9. The cable for the DC charging system of new energy vehicles according to claim 1, characterized in that: The preparation method of the sheath layer material comprises the following steps: weighing each raw material by weight, uniformly mixing polyvinyl chloride, nitrile rubber, ethylene-tetrafluoroethylene copolymer, modified aramid fiber, modified nano titanium dioxide, stabilizer, plasticizer and lubricant to obtain a mixture, placing the mixture into a twin-screw extruder for extrusion molding to prepare the sheath layer material.

Images