Composite insulated fine copper wire and its preparation process

Abstract

The application discloses a kind of composite insulated fine copper wire and its preparation process, belong to conductor insulation technical field, for solving the technical problem that the insulation performance, mechanical property, heat conduction performance and high temperature resistance of composite insulated fine copper wire in prior art need to be further improved, specifically includes: high-density polyethylene, modified boron nitride, composite ester, modified coal gangue powder, composite reinforcing material, dicumyl peroxide and auxiliary additive melt blending extrusion coating in pretreatment copper wire outside, then send into thermoplastic system and is irradiated by 80-120kGy electron beam, obtain composite insulated fine copper wire.The application is by the synergistic effect of the modified boron nitride, composite ester, modified coal gangue powder, composite reinforcing material prepared, further improve the insulation performance, mechanical property, heat conduction performance and high temperature resistance of composite insulated fine copper wire.

Description

Technical Field

[0001] This invention relates to the field of conductor insulation technology, specifically to a composite insulating fine copper wire and its preparation process. Background Technology

[0002] In fields such as electrical transmission and electronic equipment connection, composite insulated fine copper wire has become a key basic component due to its excellent conductivity and insulation protection effect. Its insulation layer must meet multiple performance requirements such as insulation reliability, mechanical stability, thermal conductivity and heat aging resistance to adapt to long-term stable operation under complex working conditions.

[0003] Currently, the insulation layer of composite insulated fine copper wire is mostly prepared using polyolefin materials such as polyethylene as the matrix, combined with inorganic fillers for modification. However, the compatibility between inorganic fillers and organic matrices is poor, and agglomeration is prone to occur, leading to defects in the insulation layer. This not only reduces the breakdown voltage but also affects the heat transfer efficiency. In addition, the lack of targeted filler surface modification design results in insufficient bonding between the insulation layer and the copper wire surface, making it prone to interlayer delamination during stress or thermal cycling, and causing significant degradation of mechanical properties. Meanwhile, the heat aging resistance of traditional insulation systems needs to be improved. Under long-term high-temperature conditions, the molecular chains of the matrix are prone to oxidative degradation, and the interface between the filler and the matrix fails, resulting in a simultaneous decline in insulation performance and mechanical properties, which seriously affects the service life of the product. In addition, the oxide layer and impurities on the surface of the copper wire will further aggravate interface defects, reduce the density of the insulation coating, and create a hidden danger of partial discharge.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a composite insulating fine copper wire and its preparation process, which solves the technical problem that the insulation performance, mechanical properties, thermal conductivity and high temperature resistance of the composite insulating fine copper wire in the prior art need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a composite insulating fine copper wire, wherein an insulating layer is coated on the surface of the copper wire to prepare the composite insulating fine copper wire; The insulating layer comprises high-density polyethylene, filler, dicumyl peroxide, and auxiliary additives; The filler components include modified boron nitride, composite ester, modified coal gangue powder, and composite reinforcing materials; The modified boron nitride was prepared by alkaline pretreatment and hydrothermal modification using a hexamethylenediamine-glucose-tin chloride system, thereby achieving surface functionalization modification and improved interfacial bonding performance of boron nitride. The composite ester was prepared by esterification of 5-norbornene-2,3-dicarboxylic anhydride and 1-adamantanol under the catalysis of p-toluenesulfonic acid. The modified coal gangue powder was prepared by surface coating modification with a coupling agent; The composite reinforcing material is prepared by grinding and drying paraffin wax and then blending it with expanded graphite, followed by interfacial bonding through multiple cold and hot cycles, thereby achieving material densification and improved reinforcement performance.

[0007] Furthermore, the modified boron nitride is prepared by the following steps: A1. Add hexagonal boron nitride to an aqueous sodium hydroxide solution, stir at 50-60℃ for 5-6 hours, filter, wash the filter residue with deionized water until the washing liquid is neutral, then transfer it to a vacuum drying oven and dry at 80℃ for 12 hours to obtain pretreated boron nitride. A2. Add hexamethylenediamine, glucose and pretreated boron nitride to a reaction vessel containing deionized water. Stir at 20-30℃ for 40-60 min, then raise the temperature to 110-120℃. Next, add tin chloride pentahydrate ethanol solution dropwise. After the addition is complete, stir for 22-24 h. After the reaction is complete, perform post-treatment to obtain modified boron nitride.

[0008] Further, in step A1, the ratio of hexagonal boron nitride to sodium hydroxide aqueous solution is 1.0-1.1g:80mL, and the mass fraction of sodium hydroxide is 20%; in step A2, the ratio of hexamethylenediamine, glucose, pretreated boron nitride, deionized water, and tin chloride pentahydrate ethanol solution is 0.15-0.2g:0.5-0.6g:0.9g:18-22mL:25-30mL, wherein the mass fraction of tin chloride pentahydrate ethanol solution is 15%.

[0009] Furthermore, the preparation method of the composite ester is as follows: 5-norbornene-2,3-dicarboxylic anhydride, 1-adamantanol and p-toluenesulfonic acid are added to a reaction vessel containing toluene and stirred at 100-110℃ for 22-24h. After the reaction is completed, the mixture is cooled to room temperature, and then ethyl acetate is added. After stirring until the solid dissolves, a saturated sodium bicarbonate aqueous solution is added. The organic layer is collected, dried first with anhydrous MgSO4, and then dried at 60-70℃ to constant weight to obtain the composite ester.

[0010]

[0011] Furthermore, the ratio of 5-norbornene-2,3-dicarboxylic anhydride, 1-adamantanol, p-toluenesulfonic acid, and toluene is 2g:4g:0.1g:24-28mL.

[0012] Furthermore, the preparation method of the modified coal gangue powder is as follows: the coal gangue powder is dried in a forced-air drying oven at 105-110℃ to constant weight, cooled to room temperature, the coupling agent solution is sprayed on the surface of the coal gangue powder, and then transferred to a high-speed mixer and mixed at 100-120℃ and 1000-1200r / min for 10-15min. After the mixing is completed, the product is discharged and cooled to obtain the modified coal gangue powder.

[0013] Furthermore, the ratio of coal gangue powder to coupling agent solution is 10g:2-3mL, and the coupling agent solution is obtained by uniformly mixing isopropyl tris(dioctyl pyrophosphate) titanate and anhydrous ethanol at a volume ratio of 1:15.

[0014] Furthermore, the preparation method of the composite reinforcing material is as follows: paraffin wax is added to a ball mill and ground at 180 rpm for 5-6 hours, then passed through a 400-mesh sieve, and then transferred to a vacuum drying oven and vacuum dried at 40°C for 10-12 hours. After drying, it is added to a mixer along with expanded graphite and mixed for 24 hours. Then, it is taken out and spread evenly in a boat with a thickness of 2-3 mm, placed in a muffle furnace, heated at 200°C for 10-15 seconds, taken out and air-cooled at room temperature for 20-30 seconds. The heating-cooling cycle is repeated 5-7 times, then taken out and ground, and passed through a 300-mesh sieve to obtain the composite reinforcing material; the ratio of paraffin wax to expanded graphite is 1 g: 3 g.

[0015] Furthermore, the preparation process of the composite insulating fine copper wire includes the following steps: S1. Place copper wire with a diameter of 1-2.0 mm on a wire feeding rack, soak it in sodium hydroxide aqueous solution at 60-70℃ for 3-5 minutes, then treat it with sulfuric acid aqueous solution corrosion inhibitor at 30-40℃ for 1-2 minutes, rinse it with deionized water until the washing solution is neutral, and dry it in a hot air drying oven at 80-100℃ for 2-3 minutes to obtain pretreated copper wire. S2. High-density polyethylene, filler, dicumyl peroxide and auxiliary additives are added to a twin-screw extruder and melt-blended for 3-5 minutes. The mixture is then extruded and coated onto the outside of the pretreated copper wire to form a 2-3 mm thick insulating coating layer on the outside of the copper wire. S3. The copper wire with the insulating coating is irradiated with an electron beam of 80-120kGy for 3-5 minutes in an air atmosphere at normal temperature and pressure, then cooled in a cooling water bath for 3-5 minutes, and finally dried with hot air at 60-80℃ to obtain a fine copper wire with composite insulation.

[0016] Further, in step S1, the mass fraction of the sodium hydroxide aqueous solution is 10%, and the mass fraction of the sulfuric acid aqueous solution is 8%; in step S2, the dosage ratio of polyethylene, filler, dicumyl peroxide, and auxiliary additives is 70-75g:20-25g:0.8-1.2g:2-3g, wherein the filler is composed of modified boron nitride, composite ester, modified coal gangue powder, and composite reinforcing material mixed evenly in a dosage ratio of 7-8g:1-1.5g:6-7g:4-5g; the temperature of the six temperature zones set from the feed end towards the die head of the twin-screw extruder is set sequentially to 155℃, 160℃, 160℃, 165℃, 165℃, and 160℃, and the spindle speed of the twin-screw extruder is 40 r / min.

[0017] The present invention has the following beneficial effects: 1. The modified boron nitride of this invention is etched with a strong alkali to form a hydroxylated surface, and then a core-shell structure is constructed through a hydrothermal reaction. The introduction of SnO2 nanoparticles not only utilizes their insulating properties to fill internal defects in the insulating layer, but also optimizes charge distribution and reduces local electric field concentration through inter-element coordination. The ester bond structure of the composite ester can enhance the compactness of the insulating system, fill the tiny gaps between the filler and the matrix, and inhibit the formation of leakage channels. Modified coal gangue powder is grafted with a coupling agent to form Ti-O-Si / Al covalent bonds, improving the compatibility between the inorganic filler and the organic matrix and avoiding interfacial deformation. The decrease in insulation performance caused by surface voids can be mitigated by the paraffin-coated expanded graphite in the composite reinforcing material, which reduces the probability of filler agglomeration due to its core-shell structure, thereby reducing weak points in the insulation. Meanwhile, the copper wire undergoes pretreatment with alkaline washing to remove oil and acid washing to inhibit corrosion, thus removing surface impurities and oxide layers and ensuring a tight fit between the copper wire and the insulating coating layer. This prevents partial discharge caused by interfacial gaps. Finally, electron beam crosslinking treatment forms a three-dimensional network structure in the high-density polyethylene matrix, further densifying the insulating layer. This synergistic effect with the structural advantages of each modified component blocks charge migration paths and significantly improves the insulation performance.

[0018] 2. The hydrophobic long-chain groups grafted onto the surface of the modified coal gangue powder of this invention exhibit excellent compatibility with the high-density polyethylene matrix. Its rigid inorganic particle characteristics can transfer stress under load, playing a reinforcing role. The layered structure of expanded graphite in the composite reinforcing material, after being modified by paraffin coating, not only improves the dispersion uniformity but also alleviates stress concentration through the toughness adjustment effect of paraffin, forming a rigid-toughness complementary reinforcing system with the modified coal gangue powder. The core-shell structure of modified boron nitride, with its high specific surface area, forms a strong bond with the matrix, improving the interfacial bonding strength. The composite ester acts as a plasticizer to optimize the flexibility of the matrix molecular chains and reduce the anisotropy of mechanical properties. In addition, the clean and flat surface of the copper wire after pretreatment enhances the interfacial adhesion with the insulation layer, preventing interlayer delamination under load. Finally, the electron beam crosslinking treatment forms a stable crosslinked network in the polyethylene matrix, enhancing the structural integrity and deformation resistance of the insulation layer. Together with the reinforcing effect of each modified filler, it significantly improves its mechanical properties.

[0019] 3. The modified boron nitride of this invention possesses excellent thermal conductivity. Its core-shell structure and uniform dispersion form a continuous thermal conductivity pathway. The synergistic effect of SnO2 and boron nitride optimizes the thermal conductivity efficiency. The layered structure of expanded graphite in the composite reinforcing material provides a rapid channel for heat transfer, while the coating effect of paraffin ensures the continuity of the thermal conductivity pathway. Together with the modified boron nitride, these elements form a multidimensional thermal conductivity network, improving the overall thermal conductivity. In terms of heat aging resistance, the SnO2 nanoparticles on the surface of the modified boron nitride can capture free radicals generated during heat aging, inhibiting the breakage of the matrix molecular chains. The ester bond structure of the composite ester exhibits good thermal stability, which can alleviate the thermo-oxidative aging of the insulation system at high temperatures. The stable structure of the modified coal gangue powder and composite reinforcing material can maintain morphological integrity under high temperature conditions, avoiding performance degradation caused by filler agglomeration or delamination. At the same time, copper wire pretreatment avoids interfacial aging of the surface oxide layer at high temperatures. The three-dimensional network structure formed by electron beam crosslinking improves the thermal stability of the matrix. In synergy with the heat resistance characteristics of each modified component, it effectively inhibits the performance degradation of the insulation layer under high temperature conditions, achieving simultaneous improvement in thermal conductivity and heat aging resistance. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In this application, the high-density polyethylene is selected from Suzhou Xuchi Plastics Co., Ltd., and the grade is M80064S. In this application, the hexagonal boron nitride is selected from Qinghe County Chaotai Metal Materials Co., Ltd., CAS No. 1344-2-2, mesh number is 2000 mesh, model is AM-HBN-Q-01; In this application, the coal gangue powder is selected from Lingshou County Henglin Mineral Products Co., Ltd., and the particle size is 0.3μm; In this application, the paraffin wax is selected from Zhonghe Chemical (Shandong) Co., Ltd., CAS No. 8002-74-2, model No. 58; In this application, the expanded graphite is selected from Shijiazhuang Huijin Mineral Products Co., Ltd., with an expansion degree of 400 and a crystal grain size of 325 mesh.

[0022] Example 1 This embodiment provides a process for preparing composite insulating fine copper wire, including the following steps: S1. Preparation of pretreated copper wire A copper wire with a diameter of 1 mm is placed on a wire feeding rack, soaked in a 10 wt% sodium hydroxide aqueous solution at 60℃ for 3 minutes, then treated with an 8 wt% sulfuric acid aqueous solution as a corrosion inhibitor at 30℃ for 1 minute, rinsed with deionized water until the washing solution is neutral, and then dried in an 80℃ hot air drying oven for 2 minutes to obtain a pretreated copper wire.

[0023] S2, Preparation of modified boron nitride Weigh 10g of hexagonal boron nitride and add it to 800mL of 20wt% sodium hydroxide aqueous solution. Stir at 50℃ for 5h, filter, wash the filter residue with deionized water until the washing liquid is neutral, and then transfer it to a vacuum drying oven and dry at 80℃ for 12h to obtain pretreated boron nitride. Weigh out 1.5g hexamethylenediamine, 5g glucose and 9g pretreated boron nitride and add them to a reaction vessel containing 180mL deionized water. Stir at 20℃ for 40min, then raise the temperature to 110℃ and add 250mL of 15wt% tin chloride pentahydrate ethanol solution dropwise. After the addition is complete, stir for 22h. After the reaction is complete, cool to room temperature, centrifuge and wash 4 times with a mixed solution of deionized water and isopropanol. Place the product in a freeze dryer at -40℃ and freeze dry for 8h to obtain modified boron nitride.

[0024] During the reaction, hexagonal boron nitride is stirred in an aqueous sodium hydroxide solution. The strong base, through etching, breaks the BN bonds on the surface of the hexagonal boron nitride sheets, generating active groups such as hydroxyl groups. Subsequently, under hydrothermal conditions, hexamethylenediamine molecules adsorb onto the surface of boron nitride via amino groups and react with Sn. 4+A coordination complex structure is formed, and glucose acts synergistically as a growth regulator and dispersion stabilizer to construct an organic induction layer on the surface of boron nitride that is conducive to heterogeneous nucleation. In this induction and confinement environment, tin chloride pentahydrate undergoes controlled hydrolysis and SnO2 nanoparticles are deposited in situ on the surface of boron nitride, resulting in core-shell modified boron nitride.

[0025] S3, Preparation of composite esters Weigh out 10g of 5-norbornene-2,3-dicarboxylic anhydride, 20g of 1-adamantanol, and 0.5g of p-toluenesulfonic acid and add them to a reaction vessel containing 120mL of toluene. Stir at 100℃ for 22h. After the reaction is complete, cool to room temperature, then add ethyl acetate and stir until the solid dissolves. Then add saturated sodium bicarbonate aqueous solution, collect the organic layer, dry it first with anhydrous MgSO4, and then dry it at 60℃ to constant weight to obtain the composite ester.

[0026] During the reaction, under the catalysis of p-toluenesulfonic acid, the carbonyl group of 5-norbornene-2,3-dicarboxylic anhydride is activated by protons, and the hydroxyl group of 1-adamantanol acts as a nucleophile to perform nucleophilic addition, causing the anhydride to undergo ring opening and then be eliminated by proton transfer to form an ester bond. The two ends of the bifunctional anhydride undergo esterification with one molecule of 1-adamantanol, finally yielding a complex ester.

[0027] S4. Preparation of modified coal gangue powder Weigh out 1 mL of isopropyl tris(dioctyl pyrophosphoryloxy) titanate and 15 mL of anhydrous ethanol, mix them thoroughly to obtain a coupling agent solution; Weigh 20g of coal gangue powder and dry it in a 105℃ forced-air drying oven until constant weight. Cool it to room temperature and spray 4mL of coupling agent solution onto the surface of the coal gangue powder. Then transfer it to a high-speed mixer and mix it at 100℃ and 1000r / min for 10min. After mixing, discharge the product and cool it to obtain modified coal gangue powder.

[0028] During the reaction, the dried and activated coal gangue powder exposes the surface hydroxyl groups. After contacting with the isopropyltris(dioctylpyrophosphoryloxy)titanate ethanol solution, under the action of high-speed mixing heat and shear force, the isopropoxy group of the coupling agent undergoes a de-alcoholization condensation reaction with the surface hydroxyl groups of the coal gangue powder to form Ti-O-Si / Al covalent bonds to achieve grafting. The hydrophobic long chain groups are oriented to optimize the surface properties of the filler, and finally modified coal gangue powder is obtained.

[0029] S5. Preparation of composite reinforced materials Weigh 10g of paraffin wax and add it to a ball mill. Grind it at 180rpm for 5 hours, pass it through a 400-mesh sieve, and then transfer it to a vacuum drying oven. Dry it under vacuum at 40℃ for 10 hours. Then, add it to a mixer with 30g of expanded graphite and mix for 24 hours. Then, take it out and spread it evenly in a boat with a thickness of 2mm. Place it in a muffle furnace and heat it at 200℃ for 10 seconds. After taking it out, air cool it at room temperature for 20 seconds. Repeat the heating-cooling cycle 5 times. Then, take it out, grind it, and pass it through a 300-mesh sieve to obtain the composite reinforced material.

[0030] During the reaction, paraffin wax is ground and refined, dried at low temperature, and then mixed and dispersed with expanded graphite. Through multiple cycles of short-term heating at 200℃ and cooling at room temperature, the phase change characteristics of paraffin wax melting and solidification are utilized. With the help of capillary action and surface tension, it is uniformly wetted and coated on the porous structure and surface of expanded graphite. Finally, after grinding and sieving, a core-shell structured composite reinforcing material is obtained.

[0031] S6. Preparation of insulating layer Weigh out 14g of modified boron nitride, 2g of composite ester, 12g of modified coal gangue powder and 8g of composite reinforcing material, mix them evenly to obtain the filler; Weigh out 0.9g of polyethylene wax, 0.7g of stearic acid and 0.3g of antioxidant 1010 and mix them evenly to obtain the auxiliary additive; Weigh out 70g of high-density polyethylene, 20g of filler, 0.8g of dicumyl peroxide and 2g of auxiliary additives, add them to a twin-screw extruder and melt-blend for 3 minutes. Then, extrude the mixture to coat the outside of the pretreated copper wire, forming a 2mm thick insulating coating layer on the outside of the copper wire.

[0032] S7. Preparation of fine copper wire for composite insulation Copper wire with an insulating coating is irradiated with an 80 kGy electron beam for 3 minutes in an air atmosphere at normal temperature and pressure, then cooled in a cooling water bath for 3 minutes, and finally dried with hot air at 60°C to obtain a fine copper wire with composite insulation.

[0033] Example 2 This embodiment provides a process for preparing composite insulating fine copper wire, including the following steps: S1. Preparation of pretreated copper wire A copper wire with a diameter of 1.5 mm was placed on a wire feeding rack, soaked in a 10 wt% sodium hydroxide aqueous solution at 65°C for 4 minutes, then treated with an 8 wt% sulfuric acid aqueous solution as a corrosion inhibitor at 35°C for 1 minute, rinsed with deionized water until the washing solution was neutral, and dried in a 90°C hot air drying oven for 2 minutes to obtain a pretreated copper wire.

[0034] S2, Preparation of modified boron nitride Weigh 10.5g of hexagonal boron nitride and add it to 800mL of 20wt% sodium hydroxide aqueous solution. Stir at 55℃ for 5.5h, filter, wash the filter residue with deionized water until the washing liquid is neutral, and then transfer it to a vacuum drying oven and dry at 80℃ for 12h to obtain pretreated boron nitride. Weigh out 1.8 g hexamethylenediamine, 5.5 g glucose and 9 g pretreated boron nitride and add them to a reaction vessel containing 200 mL deionized water. Stir at 25 °C for 50 min and then heat to 115 °C. Then add 280 mL of 15 wt% tin chloride pentahydrate ethanol solution dropwise. After the addition is complete, stir for 23 h. After the reaction is complete, cool to room temperature, centrifuge and wash 4 times with a mixed solution of deionized water and isopropanol. Place the product in a freeze dryer at -40 °C and freeze dry for 8 h to obtain modified boron nitride.

[0035] S3, Preparation of composite esters Weigh out 10g of 5-norbornene-2,3-dicarboxylic anhydride, 20g of 1-adamantanol, and 0.5g of p-toluenesulfonic acid and add them to a reaction vessel containing 130mL of toluene. Stir at 105℃ for 23h. After the reaction is complete, cool to room temperature, then add ethyl acetate and stir until the solid dissolves. Then add saturated sodium bicarbonate aqueous solution, collect the organic layer, dry it first with anhydrous MgSO4, and then dry it at 65℃ to constant weight to obtain the composite ester.

[0036] S4. Preparation of modified coal gangue powder Weigh out 1 mL of isopropyl tris(dioctyl pyrophosphoryloxy) titanate and 15 mL of anhydrous ethanol, mix them thoroughly to obtain a coupling agent solution; Weigh 20g of coal gangue powder and dry it in a 105℃ forced-air drying oven until constant weight. Cool it to room temperature and spray 5mL of coupling agent solution onto the surface of the coal gangue powder. Then transfer it to a high-speed mixer and mix it at 110℃ and 1100r / min for 12min. After mixing, discharge the product and cool it to obtain modified coal gangue powder.

[0037] S5. Preparation of composite reinforced materials Weigh 10g of paraffin wax and add it to a ball mill. Grind it at 180rpm for 5.5 hours, pass it through a 400-mesh sieve, and then transfer it to a vacuum drying oven. Dry it under vacuum at 40℃ for 11 hours. Then, add it to a mixer with 30g of expanded graphite and mix for 24 hours. Then, take it out and spread it evenly in a boat with a thickness of 2mm. Place it in a muffle furnace and heat it at 200℃ for 12 seconds. After taking it out, air cool it at room temperature for 25 seconds. Repeat the heating-cooling cycle 6 times. Then, take it out, grind it, and pass it through a 300-mesh sieve to obtain the composite reinforced material.

[0038] S6. Preparation of insulating layer Weigh out 15g of modified boron nitride, 2.5g of composite ester, 13g of modified coal gangue powder and 9g of composite reinforcing material, mix them evenly to obtain the filler; Weigh out 1.0g of polyethylene wax, 0.9g of stearic acid and 0.4g of antioxidant 1010, mix them evenly to obtain the auxiliary additive; Weigh out 72g of high-density polyethylene, 22g of filler, 1g of dicumyl peroxide and 2.5g of auxiliary additives, add them to a twin-screw extruder and melt-blend for 4 minutes. Then, extrude the mixture to coat the outside of the pretreated copper wire, forming a 2mm thick insulating coating layer on the outside of the copper wire.

[0039] S7. Preparation of fine copper wire for composite insulation The copper wire with an insulating coating is irradiated with a 100 kGy electron beam for 4 minutes in an air atmosphere at normal temperature and pressure, then cooled in a cooling water bath for 4 minutes, and finally dried with hot air at 70℃ to obtain a fine copper wire with composite insulation.

[0040] Example 3 This embodiment provides a process for preparing composite insulating fine copper wire, including the following steps: S1. Preparation of pretreated copper wire A copper wire with a diameter of 2.0 mm was placed on a wire feeding rack, soaked in a 70℃ 10wt% sodium hydroxide aqueous solution for 5 minutes, then treated with a 40℃ 8wt% sulfuric acid aqueous solution as a corrosion inhibitor for 2 minutes, rinsed with deionized water until the washing solution was neutral, and dried in a 100℃ hot air drying oven for 3 minutes to obtain a pretreated copper wire.

[0041] S2, Preparation of modified boron nitride Weigh 11g of hexagonal boron nitride and add it to 800mL of 20wt% sodium hydroxide aqueous solution. Stir at 60℃ for 6h, filter, wash the filter residue with deionized water until the washing liquid is neutral, and then transfer it to a vacuum drying oven and dry at 80℃ for 12h to obtain pretreated boron nitride. Weigh out 2g hexamethylenediamine, 6g glucose and 9g pretreated boron nitride and add them to a reaction vessel containing 220mL deionized water. Stir at 30℃ for 60min, then raise the temperature to 120℃ and add 300mL of 15wt% tin chloride pentahydrate ethanol solution dropwise. After the addition is complete, stir for 24h. After the reaction is complete, cool to room temperature, centrifuge and wash 5 times with a mixed solution of deionized water and isopropanol. Place the product in a freeze dryer at -40℃ and freeze dry for 8h to obtain modified boron nitride.

[0042] S3, Preparation of composite esters Weigh out 10g of 5-norbornene-2,3-dicarboxylic anhydride, 20g of 1-adamantanol, and 0.5g of p-toluenesulfonic acid and add them to a reaction vessel containing 140mL of toluene. Stir at 110℃ for 24h. After the reaction is complete, cool to room temperature, then add ethyl acetate and stir until the solid dissolves. Then add saturated sodium bicarbonate aqueous solution, collect the organic layer, dry it first with anhydrous MgSO4, and then dry it at 70℃ to constant weight to obtain the composite ester.

[0043] S4. Preparation of modified coal gangue powder Weigh out 1 mL of isopropyl tris(dioctyl pyrophosphoryloxy) titanate and 15 mL of anhydrous ethanol, mix them thoroughly to obtain a coupling agent solution; Weigh 20g of coal gangue powder and dry it in a 110℃ forced-air drying oven until constant weight. Cool it to room temperature and spray 6mL of coupling agent solution onto the surface of the coal gangue powder. Then transfer it to a high-speed mixer and mix it at 120℃ and 1200r / min for 15min. After mixing, discharge the product and cool it to obtain modified coal gangue powder.

[0044] S5. Preparation of composite reinforced materials Weigh 10g of paraffin wax and add it to a ball mill. Grind it at 180rpm for 6 hours, pass it through a 400-mesh sieve, and then transfer it to a vacuum drying oven. Dry it under vacuum at 40℃ for 12 hours. Then, add it to a mixer with 30g of expanded graphite and mix for 24 hours. Then, take it out and spread it evenly in a boat with a thickness of 3mm. Place it in a muffle furnace and heat it at 200℃ for 15 seconds. After taking it out, air cool it at room temperature for 30 seconds. Repeat the heating-cooling cycle 7 times. Then, take it out, grind it, and pass it through a 300-mesh sieve to obtain the composite reinforced material.

[0045] S6. Preparation of insulating layer Weigh out 16g of modified boron nitride, 3g of composite ester, 14g of modified coal gangue powder and 10g of composite reinforcing material, mix them evenly to obtain the filler; Weigh out 1.2g of polyethylene wax, 1g of stearic acid and 0.6g of antioxidant 1010 and mix them evenly to obtain the auxiliary additive; Weigh out 75g of high-density polyethylene, 25g of filler, 1.2g of dicumyl peroxide and 3g of auxiliary additives, add them to a twin-screw extruder and melt-blend for 5 minutes. Then, extrude the mixture to coat the outside of the pretreated copper wire, forming a 3mm thick insulating coating layer on the outside of the copper wire.

[0046] S7. Preparation of fine copper wire for composite insulation The copper wire with an insulating coating is irradiated with a 120 kGy electron beam for 5 minutes in an air atmosphere at normal temperature and pressure, then cooled in a cooling water bath for 5 minutes, and finally dried with hot air at 80℃ to obtain a fine copper wire with composite insulation.

[0047] Comparative Example 1 The difference between this comparative example and Example 3 is that step S2 is omitted, and the modified boron nitride in step S6 is replaced with hexagonal boron nitride in step S2.

[0048] Comparative Example 2 The difference between this comparative example and Example 3 is that step S3 is omitted and the composite ester is not added in step S6.

[0049] Comparative Example 3 The difference between this comparative example and Example 3 is that step S4 is omitted, and the modified coal gangue powder in step S6 is replaced with the coal gangue powder in step S4.

[0050] Comparative Example 4 The difference between this comparative example and Example 3 is that step S5 is omitted, and the expanded graphite in step S5 is used to replace the composite reinforcing material in step S6.

[0051] Performance testing: The insulation properties of the fine copper wires used for composite insulation prepared in Examples 1-3 and Comparative Examples 1-4 were determined according to the standard GB / T 1408.1-2016 "Electrical strength test method for insulating materials - Part 1: Test at power frequency". The insulation performance was expressed as breakdown voltage. The tensile strength of the fine copper wires of composite insulation prepared in Examples 1-3 and Comparative Examples 1-4 was determined in accordance with the standard GB / T 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods - Thickness and Dimensional Measurement - Mechanical Properties Test". The thermal conductivity of the composite insulating fine copper wires prepared in Examples 1-3 and Comparative Examples 1-4 was determined according to the standard GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics - Part 1: General Rules", and expressed by the heat storage coefficient. The comprehensive performance of the fine copper wires with composite insulation prepared in Examples 1-3 and Comparative Examples 1-4 after heat aging in an air oven was determined according to standard GB / T 2951.12-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 12: General Test Methods - Thermal Aging Test Method". The test results are shown in Table 1 below: Table 1 - Performance Test Data of Samples

[0052] Data Analysis: Comparative analysis of the data in Table 1 above shows that the composite insulating fine copper wire prepared by this invention has a breakdown voltage of 35.8 kV, a tensile strength of 20.4 MPa, and a heat storage coefficient of 258 J / (m²) before aging. 2·K·s 1 / 2 After thermal aging, the breakdown voltage is 31.2 kV, the tensile strength is 17.5 MPa, and the heat storage coefficient is 231 J / (m²). 2 ·K·s 1 / 2 ); Comparative Example 1: Unmodified boron nitride, lacking surface hydroxylation treatment and SnO2 nanoparticle coating, cannot fill internal defects in the insulating layer and exhibits poor compatibility with the organic matrix, easily forming interfacial voids. This results in a breakdown voltage of 29.1 kV before aging and 22.9 kV after aging. Furthermore, unmodified boron nitride cannot construct a continuous thermal conductivity path, with a heat storage coefficient of 210 J / (m²) before aging. 2 ·K·s 1 / 2 The heat storage coefficient after aging is 173 J / (m²). 2 ·K·s 1 / 2 Due to insufficient interfacial bonding, the tensile strength before aging was 18.9 MPa, and the tensile strength after aging was 14.9 MPa. Comparative Example 2, lacking the plasticizing and densifying effects of the composite ester, resulted in increased porosity within the insulation layer. Furthermore, the tiny gaps between the filler and the matrix could not be filled, leading to a significant decrease in insulation performance and heat aging resistance. The breakdown voltage before aging was 30.7 kV, while after aging it was 23.5 kV. The absence of the composite ester accelerated thermo-oxidative aging, resulting in a tensile strength of 18.2 MPa before aging and 13.8 MPa after aging. The heat storage coefficient before aging was 237 J / (m²). 2 ·K·s 1 / 2 The heat storage coefficient after aging is 187 J / (m²). 2 ·K·s 1 / 2 ); Comparative Example 3: The unmodified coal gangue powder lacked surface grafting with coupling agent, preventing the formation of Ti-O-Si / Al covalent bonds with the organic matrix. This resulted in weak interfacial bonding, making mechanical properties the most significant degrading factor. The tensile strength before aging was 16.8 MPa, and after aging it was 14.0 MPa. The breakdown voltage before aging was 33.4 kV, and after aging it was 27.9 kV. The heat storage coefficient before aging was 229 J / (m³). 2 ·K·s 1 / 2 The heat storage coefficient after aging is 197 J / (m²). 2 ·K·s 1 / 2 ); Comparative Example 4: Expanded graphite without paraffin coating modification is prone to agglomeration, and its porous structure leads to increased interfacial gaps, mainly affecting the stability of thermal conductivity and mechanical properties. The heat storage coefficient before aging is 219 J / (m²). 2 ·K·s 1 / 2 The heat storage coefficient after aging is 184 J / (m²). 2 ·K·s 1 / 2Aggregates cause stress concentration, so the tensile strength before aging is 17.5 MPa, the tensile strength after aging is 14.3 MPa, the breakdown voltage before aging is 32.1 kV, and the breakdown voltage after aging is 26.1 kV.

[0053] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composite insulating fine copper wire, characterized in that, A composite insulated fine copper wire is prepared by coating the surface of a copper wire with an insulating layer. The insulating layer comprises high-density polyethylene, filler, dicumyl peroxide, and auxiliary additives; The filler components include modified boron nitride, composite ester, modified coal gangue powder, and composite reinforcing materials; The modified boron nitride was prepared by alkaline pretreatment and hydrothermal modification using a hexamethylenediamine-glucose-tin chloride system, thereby achieving surface functionalization modification and improved interfacial bonding performance of boron nitride. The composite ester was prepared by esterification of 5-norbornene-2,3-dicarboxylic anhydride and 1-adamantanol under the catalysis of p-toluenesulfonic acid. The modified coal gangue powder was prepared by surface coating modification with a coupling agent; The composite reinforcing material is prepared by grinding and drying paraffin wax and then blending it with expanded graphite, followed by interfacial bonding through multiple cold and hot cycles, thereby achieving material densification and improved reinforcement performance.

2. The composite insulating fine copper wire according to claim 1, characterized in that, The modified boron nitride is prepared by the following steps: A1. Add hexagonal boron nitride to an aqueous sodium hydroxide solution, stir at 50-60℃ for 5-6 hours, filter, wash the filter residue with deionized water until the washing solution is neutral, then transfer it to a vacuum drying oven and dry at 80℃ for 12 hours to obtain pretreated boron nitride. A2. Add hexamethylenediamine, glucose and pretreated boron nitride to a reaction vessel containing deionized water. Stir at 20-30℃ for 40-60 min, then raise the temperature to 110-120℃. Next, add tin chloride pentahydrate ethanol solution dropwise. After the addition is complete, stir for 22-24 h. After the reaction is complete, perform post-treatment to obtain modified boron nitride.

3. The composite insulating fine copper wire according to claim 2, characterized in that, In step A1, the ratio of hexagonal boron nitride to sodium hydroxide aqueous solution is 1.0-1.1g:80mL, and the mass fraction of sodium hydroxide is 20%. In step A2, the ratio of hexamethylenediamine, glucose, pretreated boron nitride, deionized water, and tin chloride pentahydrate ethanol solution is 0.15-0.2g:0.5-0.6g:0.9g:18-22mL:25-30mL, wherein the mass fraction of tin chloride pentahydrate ethanol solution is 15%.

4. The composite insulating fine copper wire according to claim 1, characterized in that, The preparation method of the composite ester is as follows: 5-norbornene-2,3-dicarboxylic anhydride, 1-adamantanol and p-toluenesulfonic acid are added to a reaction vessel containing toluene and stirred at 100-110℃ for 22-24h. After the reaction is completed, the mixture is cooled to room temperature, and then ethyl acetate is added. After stirring until the solid dissolves, a saturated sodium bicarbonate aqueous solution is added. The organic layer is collected, dried first with anhydrous MgSO4, and then dried at 60-70℃ to constant weight to obtain the composite ester.

5. The composite insulating fine copper wire according to claim 4, characterized in that, The ratio of 5-norbornene-2,3-dicarboxylic anhydride, 1-adamantanol, p-toluenesulfonic acid, and toluene is 2g:4g:0.1g:24-28mL.

6. The composite insulating fine copper wire according to claim 1, characterized in that, The modified coal gangue powder is prepared as follows: the coal gangue powder is dried in a forced-air drying oven at 105-110℃ to constant weight, cooled to room temperature, and the coupling agent solution is sprayed onto the surface of the coal gangue powder. Then it is transferred to a high-speed mixer and mixed at 100-120℃ and 1000-1200r / min for 10-15min. After mixing, the product is discharged and cooled to obtain modified coal gangue powder.

7. The composite insulating fine copper wire according to claim 6, characterized in that, The ratio of coal gangue powder to coupling agent solution is 10g:2-3mL. The coupling agent solution is obtained by uniformly mixing isopropyl tris(dioctyl pyrophosphate) titanate and anhydrous ethanol at a volume ratio of 1:

15.

8. The composite insulating fine copper wire according to claim 1, characterized in that, The preparation method of the composite reinforcing material is as follows: paraffin wax is added to a ball mill and ground at 180 rpm for 5-6 hours. After passing through a 400-mesh sieve, it is transferred to a vacuum drying oven and vacuum dried at 40°C for 10-12 hours. Then, it is mixed with expanded graphite in a mixer for 24 hours. After that, it is taken out and spread evenly in a boat with a thickness of 2-3 mm. It is placed in a muffle furnace and heated at 200°C for 10-15 seconds. After taking it out, it is air-cooled at room temperature for 20-30 seconds. The heating-cooling cycle is repeated 5-7 times. After that, it is taken out, ground, and passed through a 300-mesh sieve to obtain the composite reinforcing material. The ratio of paraffin wax to expanded graphite is 1 g: 3 g.

9. A process for preparing a composite insulating fine copper wire, characterized in that, The preparation process of the composite insulating fine copper wire includes the following steps: S1. Place copper wire with a diameter of 1-2.0 mm on a wire feeding rack, soak it in sodium hydroxide aqueous solution at 60-70℃ for 3-5 minutes, then treat it with sulfuric acid aqueous solution corrosion inhibitor at 30-40℃ for 1-2 minutes, rinse it with deionized water until the washing solution is neutral, and dry it in a hot air drying oven at 80-100℃ for 2-3 minutes to obtain pretreated copper wire. S2. High-density polyethylene, filler, dicumyl peroxide and auxiliary additives are added to a twin-screw extruder and melt-blended for 3-5 minutes. The mixture is then extruded and coated onto the outside of the pretreated copper wire to form a 2-3 mm thick insulating coating layer on the outside of the copper wire. S3. The copper wire with the insulating coating is irradiated with an electron beam of 80-120kGy for 3-5 minutes in an air atmosphere at normal temperature and pressure, then cooled in a cooling water bath for 3-5 minutes, and finally dried with hot air at 60-80℃ to obtain a fine copper wire with composite insulation.

10. The preparation process of a composite insulating fine copper wire according to claim 9, characterized in that, In step S1, the sodium hydroxide aqueous solution has a mass fraction of 10%, and the sulfuric acid aqueous solution has a mass fraction of 8%. In step S2, the ratio of polyethylene, filler, dicumyl peroxide, and auxiliary additives is 70-75g:20-25g:0.8-1.2g:2-3g. The filler is composed of modified boron nitride, composite ester, modified coal gangue powder, and composite reinforcing material mixed evenly in a ratio of 7-8g:1-1.5g:6-7g:4-5g. The twin-screw extruder has six temperature zones set from the feed end towards the die head, with temperatures sequentially set to 155℃, 160℃, 160℃, 165℃, 165℃, and 160℃. The spindle speed of the twin-screw extruder is 40 r / min.

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