Winding cable and preparation method thereof

Abstract

The invention relates to the technical field of cable materials, and particularly discloses a winding cable. The composite material is prepared from the following raw materials in parts by weight: 35 to 55 parts of hydroxyl-silane double modified graphene / silicon oxide composite sheet layers, 45 to 65 parts of poly [2-(trifluoromethanesulfonyl) ethyl acrylate]-co-[N-(3-coumarin acyl propyl) acrylamide], 0.3 to 0.8 part of an antioxidant, 0.5 to 1.2 parts of a silane coupling agent, 5 to 12 parts of a nitrogen-phosphorus-silicon synergistic flame retardant, 0.5 to 1.0 part of dicumyl peroxide and 0.2 to 0.6 part of an ultraviolet-near infrared bidirectional shielding agent. The cable realizes excellent comprehensive performance of heat conductivity, insulativity, flame retardance, weather resistance and heat stability by constructing an interface synergistic heat conduction structure and a stable cross-linked network, and is suitable for a motor winding system under high-temperature, high-frequency and high-voltage complex working conditions. A bifunctional modified sheet layer and a fluorine-containing-aromatic copolymerization network are introduced in structural design, so that the thermal conductivity and dielectric property of the material are synergistically improved, and the material has good industrial application prospect and popularization value.

Description

Technical Field

[0001] The present invention relates to the technical field of cable materials, and in particular to a winding cable and a preparation method thereof. Background Art

[0002] With the rapid development of new energy vehicles, high-speed motors, and other new energy equipment, winding cables must simultaneously meet multiple requirements, including high voltage, high temperature, high frequency, and long-term stable operation. Commonly used cable insulation materials, such as polyethylene, polyvinyl chloride, or polyimide, while offering good processability and reasonable electrical properties, suffer from significant shortcomings such as low thermal conductivity, high dielectric loss, and poor dimensional stability. These factors are particularly susceptible to failures such as breakdown, deformation, and aging at high power densities and in complex environments. Currently, research has been conducted to introduce inorganic fillers such as graphene, alumina, and boron nitride to enhance the thermal conductivity and dielectric strength of polymers. However, due to the poor interfacial compatibility of fillers, these fillers often cause agglomeration, electric field distortion, and interfacial debonding, which in turn weakens their overall performance. To enhance environmental adaptability, research has also been conducted to introduce antioxidants, flame retardants, and shielding agents, but composite efficiency and material uniformity still need to be improved. Existing material structures are often inert and lack the ability to adjust to external stimuli such as light and heat, hindering service life.

[0003] Therefore, there is an urgent need to develop a high-performance winding cable material with stable interface structure, excellent thermoelectric synergistic performance, anti-aging and flame retardant shielding functions to meet the comprehensive requirements of cable performance in complex application environments in the future. Summary of the Invention

[0004] To address the deficiencies mentioned in the above background technology, the present invention provides a winding cable and a method for preparing the same. The cable utilizes a hydroxyl-silane dual-modified graphene / silicon oxide composite sheet and a poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] copolymer as the primary composite substrate, supplemented with an antioxidant, a silane coupling agent, a nitrogen-phosphorus-silicon synergistic flame retardant, a peroxide initiator, and a UV-NIR bidirectional shielding agent for functional optimization. The resulting winding cable exhibits high thermal conductivity, low dielectric loss, excellent interfacial stability, good flame retardancy, aging resistance, and UV-NIR shielding capabilities.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A winding cable comprises the following raw materials in parts by weight: 35-55 parts of a hydroxyl-silane double-modified graphene / silicon oxide composite sheet; 45-65 parts of poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide]; 0.3-0.8 parts of an antioxidant; 0.5-1.2 parts of a silane coupling agent; 5-12 parts of a nitrogen-phosphorus-silicon synergistic flame retardant; 0.5-1.0 parts of dicumyl peroxide; and 0.2-0.6 parts of a UV-near infrared bidirectional shielding agent. The hydroxyl-silane double-modified graphene / silicon oxide composite sheet is an organic-inorganic synergistic sheet material prepared by modifying an inorganic skeleton formed of graphene oxide and ethyl orthosilicate with 3-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane disilane.

[0007] Optionally, the hydroxyl-silane dual-modified graphene / silicon oxide composite sheet contains the following raw materials in parts by weight: 5 to 15 parts of graphene oxide, 20 to 40 parts of ethyl orthosilicate, 2 to 6 parts of 3-aminopropyltriethoxysilane, 1 to 3 parts of p-toluenesulfonyl chloride, 30 to 60 parts of anhydrous ethanol, 15 to 35 parts of deionized water, 1 to 3 parts of hydrochloric acid, and 1 to 3 parts of ammonia water; the concentration of the hydrochloric acid is 0.1 mol / L; and the volume fraction of the ammonia water is 25%.

[0008] Optionally, poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] contains the following raw materials in parts by weight: 40 to 70 parts of 2-(trifluoromethanesulfonyl)ethyl acrylate, 20 to 50 parts of N-(3-coumarinoylpropyl)acrylamide, 0.5 to 1.5 parts of initiator, and 100 to 200 parts of N-methylpyrrolidone; the initiator is azobisisobutyronitrile.

[0009] Optionally, the antioxidant is a mixture of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and tris(2,4-di-tert-butylphenyl) phosphate in a mass ratio of 3:1 to 5:1; the silane coupling agent is a mixture of 3-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane in a mass ratio of 1:1 to 2:1; the nitrogen-phosphorus-silicon synergistic flame retardant is a mixture of melamine polyphosphate and polydimethylsiloxane-white carbon black composite in a mass ratio of 4:1 to 6:1; the ultraviolet-near infrared bidirectional shielding agent is a mixture of hollow titanium dioxide particles and perylene diimide ultraviolet absorbers in a mass ratio of 4:1 to 6:1.

[0010] Optionally, the preparation method of the hydroxyl-silane dual-modified graphene / silicon oxide composite layer comprises the following steps:

[0011] (1) adding graphene oxide and tetraethyl orthosilicate into a mixed solvent of anhydrous ethanol and deionized water, and dispersing them under ultrasonic conditions for 20 to 40 minutes to form a uniform precursor system;

[0012] (2) adding hydrochloric acid solution dropwise to the homogeneous precursor system to adjust the pH to 1.5-3.5, and reacting under magnetic stirring at 25-35° C. for 1-3 hours to form a composite lamellar structure;

[0013] (3) Add ammonia water dropwise to the homogeneous precursor system, adjust the pH to 9-11, and maintain the reaction for 20-40 minutes;

[0014] (4) After cooling the reaction system to 20-30° C., 3-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane were added and reacted at 65-85° C. for 1.5-2.5 hours to construct a stable organic-inorganic synergistic interface structure;

[0015] (5) After the reaction is completed, the obtained solid is centrifuged and washed with ethanol and deionized water for 2 to 4 times in sequence until the pH of the filtrate is 6 to 7, and then freeze-dried at -40 to -60 ° C for 20 to 30 hours to obtain hydroxyl-silane dual-modified graphene / silicon oxide composite sheet powder.

[0016] Alternatively, the preparation method of poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] comprises the following steps:

[0017] (a) adding 2-(trifluoromethanesulfonyl)ethyl acrylate and N-(3-coumarinoylpropyl)acrylamide to N-methylpyrrolidone and stirring to dissolve to form a monomer solution;

[0018] (b) adding azobisisobutyronitrile as an initiator to the monomer solution, and carrying out a free radical polymerization reaction at 70 to 80° C. under nitrogen protection for 6 to 10 hours;

[0019] (c) After the polymerization is completed, the reaction solution is poured into excess anhydrous ether to precipitate the polymer, which is then centrifuged and washed repeatedly 2 to 3 times to obtain a precipitate;

[0020] (d) drying the obtained precipitate in a vacuum drying oven at 50-60° C. for 12-24 hours to obtain a poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] copolymer.

[0021] Optionally, a method for preparing a winding cable comprises the following steps:

[0022] S1, adding the hydroxyl-silane dual-modified graphene / silicon oxide composite layer and the poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] copolymer into a mixing and melting extruder, and blending them uniformly under shear conditions;

[0023] S2, adding an antioxidant, a silane coupling agent, a nitrogen-phosphorus-silicon synergistic flame retardant, dicumyl peroxide, and a UV-near infrared bidirectional shielding agent in sequence during the blending process, and continuing to mix and plasticize to form a thermally stable composite melt;

[0024] S3, injection molding the heat-stable composite melt to obtain an insulation-coating composite layer material, and coating the insulating-coating composite layer material on the outer layer of the winding cable conductor under a continuous extrusion process, and performing a heat cross-linking treatment to form a winding cable.

[0025] Optionally, in step S1, the mass ratio of the hydroxyl-silane dual-modified graphene / silicon oxide composite layer to the poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] copolymer is 1:2 to 1:1; the shear conditions are a temperature of 170 to 190°C, a shear rate of 100 to 150 rpm, and a blending time of 5 to 10 minutes.

[0026] The beneficial effects of the present invention are:

[0027] By introducing a hydroxyl-silane dual-modified graphene / silicon oxide composite sheet, this invention creates a stable organic-inorganic synergistic thermal conductive structure. This significantly improves the thermal conductivity of the material while maintaining insulation performance, and effectively enhances the filler's dispersion and interfacial compatibility within the polymer matrix. The hydroxyl groups in the composite sheet enhance hydrogen bonding with the polymer segments, while the silane coupling structure further enhances interfacial bonding stability, reducing the thermal resistance of the conductive interface.

[0028] The main chain of the copolymer contains fluorinated side groups and amide groups, and has low dielectric, high thermal stability and good light shielding properties. The coumarin structure also provides certain ultraviolet absorption and self-crosslinking functions, thereby enhancing the structural stability and insulation durability of the material in complex electrothermal environments.

[0029] The winding cable prepared by the present invention achieves balanced optimization of performance in terms of thermal conductivity, insulation, flame retardancy and weather resistance, meets the comprehensive performance requirements of the insulation layer of the motor system under complex working conditions such as high temperature, high frequency and high voltage, and has good application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] Figure 1This is a comparison of infrared spectra of unmodified graphene / silicon oxide composite sheet-acrylate insulating material and hydroxyl-silane dual-modified graphene / silicon oxide-trifluoromethanesulfonyl-coumarin copolymer composite insulating material;

[0032] Figure 2 This is a scanning electron microscope image of a hydroxyl-silane dual-modified graphene / silicon oxide-trifluoromethanesulfonyl-coumarin copolymer composite insulating material;

[0033] Figure 3 The bar chart shows the performance comparison of winding cables with different ratios. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit of the present invention should also be deemed to fall within the scope of protection of the present invention.

[0035] Example 1:

[0036] The structural integrity and comprehensive performance of the winding cable produced under medium ratio conditions were investigated.

[0037] The infrared comparison of the modified winding cable and the unmodified sample shows that the two have the same wavelength in the range of 1800–500 cm -1 There are significant differences in the range. 1730cm -1 The modified sample showed a sharp carboxylate C=O absorption, while the unmodified sample had no corresponding peak, indicating that 2-(trifluoromethanesulfonyl)ethyl acrylate had been esterified and cured in the polymer chain, laying the foundation for subsequent heat resistance and dielectric properties. -1 The aromatic ring peaks in the region are significantly enhanced and broadened after modification, verifying that the embedding of conjugated units such as coumarin and perylene diimide can improve UV shielding and weather resistance life. -1 and 1185cm -1 The emergence of a new S=O absorption peak corresponds to the symmetric / asymmetric stretching vibration of the –SO2–CF3 sulfonyl group, indicating that the trifluoromethanesulfonyl group has been successfully grafted; this type of group gives the material both flame retardancy and high insulation properties. -1 The Si–O–Si bending peak reflects the inorganic silicon-oxygen skeleton constructed by the polycondensation of silane coupling agent and ethyl orthosilicate, which improves the interface between the sheet and the polymer, and enhances thermal stability and mechanical strength. -1 The newly added sharp C–F stretching peak at 3430 cm clearly proves that the –CF3 group has been embedded in the poly chain, further reducing the dielectric loss and improving the flame retardancy. -1 The broad –OH / –NH peaks of 2950 cm-1 became narrower and the intensity decreased after modification, indicating that the hydroxyl and amine groups underwent silane condensation or esterification, reducing polar defects.-1 、2870cm -1 The alkyl C–H stretching peak of the alkyl group is slightly enhanced, which proves that the content of aliphatic segments has increased. -1 The amide C=O peak shows a decrease and slight blue shift after modification, indicating that some amides are embedded or the polarity of the environment is reduced, which helps improve long-term insulation reliability. Overall, the newly added or strengthened ester C=O, sulfonyl S=O, Si–O–Si, C–F, and aromatic ring peaks together constitute the infrared fingerprint of the modified system. These structural changes directly support the synergistic performance improvements of the material in thermal conductivity, insulation, flame retardancy, and weather resistance.

[0038] Figure 2 The scanned image of the modified winding cable material can be seen more intuitively.

[0039] Preparation steps:

[0040] S1, 10 parts of graphene oxide, 30 parts of ethyl orthosilicate, 50 parts of anhydrous ethanol and 25 parts of deionized water were mixed and dispersed in an ultrasonic processor for 30 minutes to form a stable and transparent precursor solution; 2 parts of hydrochloric acid (0.1 mol / L) were slowly added dropwise to adjust the pH to 2.5, and the mixture was stirred and reacted at room temperature (30°C) for 2 hours; 2 parts of ammonia water (25%) were continued to be added dropwise to adjust the pH to 10, and the mixture was stirred and reacted for another 30 minutes; after cooling the system to 25°C, 4 parts of 3-aminopropyltriethoxysilane and 2 parts of γ-glycidoxypropyltrimethoxysilane were added, and the mixture was reacted at 75°C for 2 hours; after the reaction, the mixture was centrifuged and washed with ethanol and deionized water in sequence until neutral, and freeze-dried at -50°C for 24 hours to obtain a modified composite sheet powder;

[0041] S2, dissolving 55 parts of 2-(trifluoromethanesulfonyl)ethyl acrylate and 35 parts of N-(3-coumarinoylpropyl)acrylamide in 175 parts of N-methylpyrrolidone, stirring evenly, adding 1 part of azobisisobutyronitrile as an initiator, and reacting at 70°C under nitrogen for 8 hours. After the reaction, pouring into anhydrous ether to precipitate the product, washing it by centrifugation three times, and drying it in a vacuum at 50°C for 24 hours to obtain a white copolymer powder;

[0042] S3, blending 45 parts of the composite sheet with 55 parts of the copolymer, and melt blending at 180° C. and a shear rate of 130 rpm for 8 min;

[0043] S4, during the mixing process, 0.6 parts of antioxidant (phenol ester and phosphate ester in a mass ratio of 4:1), 0.9 parts of silane coupling agent (ratio 1.5:1), 9 parts of nitrogen-phosphorus-silicon flame retardant (ratio 5:1), 0.8 parts of dicumyl peroxide, and 0.4 parts of ultraviolet / near infrared shielding agent (ratio 5:1) were added in sequence, and the mixture was continuously blended for 5 minutes to form a uniform melt;

[0044] S5, injection molding the mixed melt into a coating layer, continuously extruding the coating layer onto the surface of the cable conductor, and heat-crosslinking at 180° C. for 30 minutes to obtain a finished cable.

[0045] Example 2:

[0046] Verify the structural forming and process adaptability of the material when the content of each component is at the upper limit of the recommended range.

[0047] Preparation steps:

[0048] S1, 15 parts of graphene oxide, 40 parts of tetraethyl orthosilicate, 60 parts of anhydrous ethanol and 35 parts of deionized water were mixed, placed in an ice bath and ultrasonically dispersed for 40 minutes to obtain a transparent and uniform precursor solution; 3 parts of hydrochloric acid (0.1 mol / L) were slowly added dropwise to adjust the pH to 2.0, and the mixture was magnetically stirred at 30°C for 2 hours; then 3 parts of ammonia water (25%) were added dropwise to adjust the pH to 10, and stirring was continued for 30 minutes; after the reaction solution was cooled to 25°C, 6 parts of 3-aminopropyltriethoxysilane and 3 parts of γ-glycidoxypropyltrimethoxysilane were added, and the reaction was continued at 80°C for 2 hours to form an organic-inorganic synergistic modified interface structure; after the reaction was completed, the solid was collected by centrifugation, washed with ethanol and deionized water in sequence until the filtrate pH was 7, and freeze-dried at -50°C for 24 hours to obtain a modified graphene / silicon oxide composite sheet powder;

[0049] S2, dissolving 70 parts of 2-(trifluoromethanesulfonyl)ethyl acrylate and 50 parts of N-(3-coumarinoylpropyl)acrylamide in 200 parts of N-methylpyrrolidone, stirring to form a uniform solution, adding 1.5 parts of azobisisobutyronitrile, nitrogen protection, and polymerizing at 70°C for 8 hours; after completion of the polymerization, pouring into anhydrous ether to precipitate a solid, washing it by centrifugation three times, and drying it in a vacuum at 50°C for 24 hours to obtain a white copolymer powder;

[0050] S3, adding 55 parts of the modified sheet and 65 parts of the copolymer in a mass ratio of 1:1 into a twin-screw extruder, and blending them at 180° C. and a shear rate of 150 rpm for 10 min;

[0051] S4, during the blending process, 0.8 parts of antioxidant (octadecylphenol ester and phosphate in a ratio of 5:1), 1.2 parts of silane coupling agent (in a ratio of 2:1), 12 parts of flame retardant (polyphosphate and siloxane complex in a ratio of 6:1), 1.0 parts of dicumyl peroxide, and 0.6 parts of ultraviolet / near-infrared shielding agent (hollow titanium dioxide and perylene diimide in a ratio of 5:1) were added in sequence; blending was continued for 5 minutes to form a stable melt;

[0052] S5, the composite melt is injection molded to obtain a coating insulation layer material, which is then coated on the outside of the conductor under a continuous extrusion process, and subjected to a heat cross-linking treatment at 180° C. for 30 minutes to obtain a finished winding cable.

[0053] Example 3:

[0054] Verify the formability and structural stability of the formula at low ratios.

[0055] Preparation steps:

[0056] S1: 5 parts of graphene oxide, 20 parts of ethyl orthosilicate, 40 parts of anhydrous ethanol and 15 parts of deionized water were mixed and ultrasonically dispersed for 20 minutes, 1 part of hydrochloric acid (0.1 mol / L) was added dropwise to adjust the pH to 2.5, and stirred for 1.5 hours. Then, 1 part of ammonia water was added dropwise to adjust the pH to 10, and the reaction was continued for 20 minutes; after cooling, 2 parts of 3-aminopropyltriethoxysilane and 1 part of γ-glycidoxypropyltrimethoxysilane were added, and the reaction was carried out at 70°C for 1.5 hours. The post-treatment was the same as S1 to obtain a powder;

[0057] S2, dissolving 40 parts of 2-(trifluoromethanesulfonyl)ethyl acrylate and 20 parts of N-(3-coumarinoylpropyl)acrylamide in 100 parts of N-methylpyrrolidone, adding 0.5 parts of azobisisobutyronitrile, and polymerizing for 6 hours. Post-treatment is the same as above;

[0058] S3, 35 parts of the sheet and 45 parts of the copolymer were added to the equipment at a mass ratio of 1:1.3, and blended at 180°C and a shear rate of 110 rpm for 6 min;

[0059] S4, adding 0.3 parts of antioxidant (3:1), 0.5 parts of coupling agent (1:1), 5 parts of flame retardant (4:1), 0.5 parts of dicumyl peroxide, and 0.2 parts of shielding agent (4:1), and blending to form a uniform composite melt;

[0060] S5, preparing the coating layer, extruding and then thermally cross-linking to obtain the final cable.

[0061] Comparative Example 1:

[0062] This comparative example is used to verify the interfacial bonding ability and material performance differences between the sheet and the polymer when there is no hydroxyl-silane modification.

[0063] Preparation steps:

[0064] S1, 15 parts of graphene oxide, 40 parts of ethyl orthosilicate, 60 parts of anhydrous ethanol and 35 parts of deionized water were mixed, placed in an ice bath and ultrasonically dispersed for 40 minutes to form a uniform precursor solution; 3 parts of hydrochloric acid (0.1 mol / L) were slowly added dropwise to adjust the pH to 2.0, and the mixture was magnetically stirred at 30°C for 2 hours; then 3 parts of ammonia water (25%) were added dropwise to adjust the pH to 10, and stirring was continued for 30 minutes to form an unmodified graphene / silicon oxide composite sheet; 3-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane were no longer added to the system; after the reaction, the solid was collected by centrifugation, washed with ethanol and deionized water in sequence until the filtrate pH was 7, and freeze-dried at -50°C for 24 hours to obtain a graphene / silicon oxide composite sheet powder for comparison;

[0065] S2, dissolving 70 parts of 2-(trifluoromethanesulfonyl)ethyl acrylate and 50 parts of N-(3-coumarinoylpropyl)acrylamide in 200 parts of N-methylpyrrolidone, stirring to form a uniform solution, adding 1.5 parts of azobisisobutyronitrile, nitrogen protection, and polymerizing at 70°C for 8 hours; after completion of the polymerization, pouring into anhydrous ether to precipitate a solid, washing it by centrifugation three times, and drying it in a vacuum at 50°C for 24 hours to obtain a copolymer powder;

[0066] S3, adding 55 parts of the unmodified sheet and 65 parts of the copolymer in a mass ratio of 1:1 into a twin-screw extruder, and blending them at 180°C and a shear rate of 150 rpm for 10 min;

[0067] S4, during the blending process, 0.8 parts of antioxidant (octadecylphenol ester and phosphate in a ratio of 5:1), 1.2 parts of silane coupling agent (in a ratio of 2:1), 12 parts of flame retardant (polyphosphate and siloxane composite in a ratio of 6:1), 1.0 parts of dicumyl peroxide, and 0.6 parts of ultraviolet / near-infrared shielding agent (hollow titanium dioxide and perylene diimide in a ratio of 5:1) were added in sequence; blending was continued for 5 minutes to form a composite melt;

[0068] S5, the composite melt is injection molded to obtain an insulating layer material, which is then coated on the outside of the conductor under a continuous extrusion process, and subjected to a heat cross-linking treatment at 180°C for 30 minutes to obtain a comparative winding cable sample.

[0069] Comparative Example 2:

[0070] This comparative example is used to verify the effect of not introducing functional structures (-CF3, coumarin) on polymer properties.

[0071] Preparation steps:

[0072] S1, preparing a hydroxyl-silane dual-modified graphene / silicon oxide composite sheet according to the steps of Example 2, all conditions are the same;

[0073] S2, dissolving 100 parts of polyethyl acrylate in 200 parts of N-methylpyrrolidone, stirring at room temperature until completely dissolved, without a polymerization step, to obtain a common polymer solution; precipitating with diethyl ether, washing, and drying to obtain a white solid powder;

[0074] S3, adding 55 parts of the modified sheet and 65 parts of the ordinary polymer in a mass ratio of 1:1 into a twin-screw extruder, and blending at 180°C and a shear rate of 150 rpm for 10 min;

[0075] S4, during the blending process, 0.8 parts of antioxidant (octadecylphenol ester and phosphate in a ratio of 5:1), 1.2 parts of silane coupling agent (in a ratio of 2:1), 12 parts of flame retardant (polyphosphate and siloxane complex in a ratio of 6:1), 1.0 parts of dicumyl peroxide, and 0.6 parts of ultraviolet / near-infrared shielding agent (hollow titanium dioxide and perylene diimide in a ratio of 5:1) were added in sequence; blending was continued for 5 minutes to form a stable melt;

[0076] S5, injection molding the composite melt and continuously extruding the outer layer of the conductor, and thermally cross-linking at 180° C. for 30 minutes to obtain a finished winding cable using a common polymer.

[0077] Performance Testing

[0078] Thermal conductivity test method

[0079] To determine the thermal conductivity of winding cable sheathing materials within the operating temperature range, thermal conductivity testing was performed using the laser flash method (LFA). Samples were cut into circular specimens with a diameter of 10 mm and a thickness of 2 mm and placed on the sample stage of a thermal conductivity tester. The test temperature range was set between 25°C and 150°C to simulate the operating environment of the motor system. The equipment illuminated the sample surface with a pulsed laser, measured the temperature rise curve, and calculated the thermal conductivity coefficient. Each group of samples was tested three times, and the average value was taken. This method can evaluate the heat dissipation performance of cable materials under high-frequency and high-current conditions.

[0080] Volume resistivity and dielectric strength test methods

[0081] To evaluate the insulation reliability of winding cable sheaths under high voltage and high frequency conditions, a combined volume resistivity and dielectric breakdown strength test was performed. First, samples were cut into 40 mm × 40 mm × 1 mm flat plates according to standard GB / T 1410-2006 and placed in a high resistance meter. The volume resistivity was tested at 500 V DC. Subsequently, the voltage was gradually increased on a dielectric strength tester, and the breakdown voltage was recorded and the dielectric strength (in kV / mm) was calculated. Both tests were performed at room temperature (25°C) and at high temperature (120°C), respectively. The tests were repeated three times, and the average results were taken to fully characterize the insulation performance.

[0082] Flame retardant performance test method

[0083] To verify the burning behavior and self-extinguishing ability of winding cables in a fire environment, the UL-94 vertical flame test and oxygen index (LOI) test were conducted. The vertical flame test follows the UL-94 standard. Samples are cut into 125mm × 13mm × 1.6mm strips, clamped vertically, and ignited with a flame for 10 seconds. Extinguishment time and dripping behavior are observed and rated according to V-0, V-1, and V-2. The oxygen index test uses an oxygen index meter to ignite the sample in a specific oxygen / nitrogen mixture and record the minimum oxygen concentration required to maintain combustion, thereby assessing its tendency to continue burning. These two methods are combined to quantify the intrinsic flame retardancy of the material.

[0084] Weathering performance test method

[0085] To evaluate the performance retention of winding cables under UV, damp heat, and high-temperature aging conditions, a xenon lamp aging test method was employed. Samples were fixed according to their dimensions in a weathering chamber, irradiated at a wavelength of 340 nm, an intensity of 0.7 W / m², a temperature of 65±3°C, and a relative humidity of 60%, for a cumulative aging time of 500 hours. Samples were regularly taken during the test and tested for color change (ΔE), mechanical strength changes (tensile properties), and surface integrity. This method simulates the aging process under actual outdoor or high-temperature conditions, reflecting the material's long-term reliability.

[0086] Thermal stability test method

[0087] In order to confirm the structural stability and life potential of the cable under high temperature conditions, thermogravimetric analysis (TGA) and hot air aging tests were carried out respectively. In the TGA test, 5-10 mg of sample was placed in a platinum crucible and heated from room temperature to 700 ° C in a nitrogen atmosphere at a heating rate of 10 ° C / min. The pyrolysis starting temperature, maximum weight loss rate temperature and residual carbon rate of the sample were recorded. In the hot air aging test, the sample was placed in an aging box and continuously treated at 150 ° C for 168 hours. Then its tensile strength retention and elongation change were tested to characterize its resistance to thermal oxidative aging. The two indicators are combined to evaluate its high-temperature service stability.

[0088] Table 1 Comprehensive performance test results of winding cables

[0089]

[0090] According to Table 1 and Figure 3The results show that the prepared example samples exhibit superior performance in five aspects: thermal conductivity, insulation, flame retardancy, weather resistance and thermal stability, which are significantly better than the comparative examples, highlighting the synergistic effect between the hydroxyl-silane dual-modified graphene / silicon oxide composite sheet and the poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] copolymer.

[0091] In terms of thermal conductivity, the thermal conductivity coefficients of Examples 1, 2, and 3 were 0.52, 0.47, and 0.44 W / m·K, respectively, all significantly higher than those of Comparative Example 1 (0.38 W / m·K) and Comparative Example 2 (0.35 W / m·K). This demonstrates that by introducing highly dispersed modified graphene / silicon oxide flakes into the polymer matrix, an effective heat conduction path is established, significantly improving the lateral diffusion efficiency of heat within the insulating material, meeting the heat dissipation requirements of the motor under high-frequency and high-load operation, and reducing the risk of heat accumulation.

[0092] In terms of insulation performance, the volume resistivity of the embodiments all reached 101 5 The dielectric strength exceeds 28 kV / mm, with Example 1 reaching as high as 31.2 kV / mm, while the comparative example only reaches 18.7-20.3 kV / mm. This fully demonstrates that under high temperature and high pressure conditions, the highly dense polymer network constructed by synergistic cross-linking can effectively block electron migration channels. At the same time, the interfacial effect of the composite filler enhances the uniformity of charge distribution, significantly improving the dielectric strength and leakage suppression capability, and providing reliable insulation protection for the winding system.

[0093] In terms of flame retardancy, the oxygen index of the examples ranged from 30.2% to 32.8%, both above the critical flame retardancy value (26%) and significantly better than the 22.4% and 24.2% values ​​of the comparative examples. This advantage is attributed to the nitrogen-phosphorus-silicon synergistic flame retardant generating an inert gas and silicon-carbon protective layer under flame conditions, which, combined with the shielding effect of graphene, suppresses the spread of combustion, significantly improving the material's intrinsic flame retardancy and meeting the UL-94 V-0 rating.

[0094] In terms of weather resistance, ΔE color difference is an important indicator for measuring the degree of aging of the material surface. After aging, the ΔE of the example samples is all below 1.5, while that of the comparative example exceeds 3.0, indicating that the UV-near infrared bidirectional shielding agent and coumarin-based polymer structure used in the present invention have excellent stability against UV radiation and heat and humidity cycles, and can effectively resist UV degradation, yellowing and cracking in outdoor environments, thereby extending the service life of the material.

[0095] In terms of thermal stability, the thermogravimetric carbon residue rate of the examples ranged from 15.7% to 18.2%, while that of the comparative examples was only 8.3% to 9.6%, showing a significant advantage. The high carbon residue indicates that the carbon layer formed after the high-temperature decomposition of the material is dense, which helps to insulate and flame retardant and enhance structural integrity. In addition, the thermogravimetric starting temperature is higher and the thermal weight loss rate is lower. Combined with the hot air aging performance, it can be confirmed that the material of the present invention can maintain mechanical and dielectric stability for a long time at a high temperature of 150°C, ensuring long-term stable operation.

[0096] From the above analysis results, it can be seen that the synergistic material system in the present invention performs excellently in many key indicators, and has high thermal conductivity, high insulation, excellent flame retardancy, good weather resistance and high-temperature thermal stability. It provides a reliable solution for high-performance winding cable insulation layer materials and has significant engineering practical value and industrialization potential.

Claims

1. A winding cable, characterized in that: The cable comprises the following raw materials in parts by weight: 35 to 55 parts of a hydroxyl-silane double-modified graphene / silicon oxide composite sheet; 45 to 65 parts of poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide]; 0.3 to 0.8 parts of an antioxidant; 0.5 to 1.2 parts of a silane coupling agent; 5 to 12 parts of a nitrogen-phosphorus-silicon synergistic flame retardant; 0.5 to 1.0 parts of dicumyl peroxide; and 0.2 to 0.6 parts of a UV-near infrared bidirectional shielding agent. The hydroxyl-silane double-modified graphene / silicon oxide composite sheet is an organic-inorganic synergistic sheet material prepared by modifying an inorganic skeleton formed by graphene oxide and ethyl orthosilicate with 3-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane.

2. A winding cable according to claim 1, characterized in that: The hydroxyl-silane double-modified graphene / silicon oxide composite sheet comprises the following raw materials in parts by weight: 5 to 15 parts of graphene oxide, 20 to 40 parts of ethyl orthosilicate, 2 to 6 parts of 3-aminopropyltriethoxysilane, 1 to 3 parts of p-toluenesulfonyl chloride, 30 to 60 parts of anhydrous ethanol, 15 to 35 parts of deionized water, 1 to 3 parts of hydrochloric acid, and 1 to 3 parts of ammonia water; the concentration of the hydrochloric acid is 0.1 mol / L; and the volume fraction of the ammonia water is 25%.

3. A winding cable according to claim 1, characterized in that: The poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] comprises the following raw materials in parts by weight: 40 to 70 parts of 2-(trifluoromethanesulfonyl)ethyl acrylate, 20 to 50 parts of N-(3-coumarinoylpropyl)acrylamide, 0.5 to 1.5 parts of an initiator, and 100 to 200 parts of N-methylpyrrolidone; the initiator is azobisisobutyronitrile.

4. A winding cable according to claim 1, characterized in that: The antioxidant is a mixture of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and tris(2,4-di-tert-butylphenyl) phosphate in a mass ratio of 3:1 to 5:1; the silane coupling agent is a mixture of 3-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane in a mass ratio of 1:1 to 2:1; the nitrogen-phosphorus-silicon synergistic flame retardant is a mixture of melamine polyphosphate and polydimethylsiloxane-white carbon black composite in a mass ratio of 4:1 to 6:1; the ultraviolet-near infrared bidirectional shielding agent is a mixture of hollow titanium dioxide particles and perylene diimide ultraviolet absorbers in a mass ratio of 4:1 to 6:

1.

5. A winding cable according to claim 1 or 2, characterized in that: The preparation method of the hydroxyl-silane dual-modified graphene / silicon oxide composite layer comprises the following steps: (1) adding graphene oxide and tetraethyl orthosilicate into a mixed solvent of anhydrous ethanol and deionized water, and dispersing them under ultrasonic conditions for 20 to 40 minutes to form a uniform precursor system; (2) adding hydrochloric acid solution dropwise to the homogeneous precursor system to adjust the pH to 1.5-3.5, and reacting under magnetic stirring at 25-35°C for 1-3 hours; (3) Add ammonia water dropwise to the homogeneous precursor system, adjust the pH to 9-11, and maintain the reaction for 20-40 minutes; (4) After cooling the reaction system to 20-30° C., 3-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane were added and reacted at 65-85° C. for 1.5-2.5 hours; (5) After the reaction is completed, the obtained solid is centrifuged and washed with ethanol and deionized water for 2 to 4 times in sequence until the pH of the filtrate is 6 to 7, and then freeze-dried at -40 to -60 ° C for 20 to 30 hours to obtain hydroxyl-silane dual-modified graphene / silicon oxide composite sheet powder.

6. A winding cable according to claim 1 or 3, characterized in that: The preparation method of the poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] comprises the following steps: (a) adding 2-(trifluoromethanesulfonyl)ethyl acrylate and N-(3-coumarinoylpropyl)acrylamide to N-methylpyrrolidone and stirring to dissolve to form a monomer solution; (b) adding azobisisobutyronitrile as an initiator to the monomer solution, and carrying out a free radical polymerization reaction at 70 to 80° C. under nitrogen protection for 6 to 10 hours; (c) After the polymerization is completed, the reaction solution is poured into excess anhydrous ether to precipitate the polymer, which is then centrifuged and washed repeatedly 2 to 3 times to obtain a precipitate; (d) drying the obtained precipitate in a vacuum drying oven at 50-60° C. for 12-24 hours to obtain a poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] copolymer.

7. A method for preparing a winding cable, the winding cable being as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1, adding the hydroxyl-silane dual-modified graphene / silicon oxide composite layer and the poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] copolymer into a mixing and melting extruder, and blending them uniformly under shear conditions; S2, adding an antioxidant, a silane coupling agent, a nitrogen-phosphorus-silicon synergistic flame retardant, dicumyl peroxide, and a UV-near infrared bidirectional shielding agent in sequence during the blending process, and continuing to mix and plasticize to form a thermally stable composite melt; S3, injection molding the heat-stable composite melt to obtain an insulation-coating composite layer material, and coating the insulating-coating composite layer material on the outer layer of the winding cable conductor under a continuous extrusion process, and performing a heat cross-linking treatment to form a winding cable.

8. A winding cable according to claim 7, characterized in that: In step S1, the mass ratio of the hydroxyl-silane dual-modified graphene / silicon oxide composite layer to the poly[2-(trifluoromethanesulfonyl)ethyl acrylate]-co-[N-(3-coumarinoylpropyl)acrylamide] copolymer is 1:2 to 1:1; the shear conditions are a temperature of 170 to 190°C, a shear rate of 100 to 150 rpm, and a blending time of 5 to 10 minutes.

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