A wear-resistant double-glass-fiber-covered copper flat wire and a preparation method thereof

Abstract

The present application relates to the technical field of glass silk wrapped copper flat wire, in particular to a wear-resistant double glass silk wrapped copper flat wire and a preparation method thereof. The wear-resistant double glass silk wrapped copper flat wire comprises a TU1 oxygen-free copper flat wire in an inner layer, and from the surface of the TU1 oxygen-free copper flat wire, a composite modified insulating paint, a heat-conducting high-temperature-resistant alkali-free glass fiber yarn, a composite modified insulating paint and a wear-resistant reinforced glass fiber yarn coated with a wear-resistant ceramic coating are sequentially arranged from inside to outside. The hydroxylated silicon nitride powder is modified by dimethyl biphenyl diisocyanate and end-amino hyperbranched polyamide, and the composite modified insulating paint is prepared by curing. The vinyl hyperbranched polysiloxane prepared by the reaction of vinyl trimethoxysilane and 1,3-propanediol is mixed with titanium boride, polycarbosilane and dimethylbenzene for ball milling and curing to prepare a wear-resistant ceramic coating. Finally, the wear-resistant double glass silk wrapped copper flat wire has excellent insulation, high-efficiency heat dissipation and high-surface wear resistance.

Description

Technical Field

[0001] This invention relates to the field of glass fiber coated copper flat wire technology, specifically to a wear-resistant double glass fiber coated copper flat wire and its preparation method. Background Technology

[0002] Double-glass-insulated copper flat wire is a widely used winding wire in motors, transformers, generators, and various high-voltage electromagnetic devices. This type of wire uses an inner layer of oxygen-free copper flat wire as its conductive core, wrapped with multiple layers of alkali-free glass fiber yarn and impregnated with insulating varnish, forming a composite structure that combines excellent electrical insulation, heat resistance, and mechanical strength. With the development of power electronic equipment towards higher power density, miniaturization, and higher reliability, double-glass-insulated copper flat wire must not only withstand higher operating voltages and current densities but also resist electromagnetic vibration, thermal cycling shock, and mechanical wear during long-term operation. Therefore, improving the wire's thermal conductivity and surface wear resistance while ensuring the integrity of the insulation system has become a key technical requirement in the field of high-performance electromagnetic wires.

[0003] However, existing double-glass fiber-clad copper flat wires still have the following technical shortcomings in practical applications: First, the inorganic fillers in conventional insulating varnishes have poor interfacial compatibility with the epoxy resin matrix, easily leading to agglomeration or interface debonding, resulting in microscopic defects in the insulation layer. Under high electric fields, this can easily cause partial discharge, reducing volume resistivity and breakdown strength, and it is difficult to simultaneously meet the dual requirements of high thermal conductivity and high insulation. Second, the wire surface lacks an effective wear-resistant protective layer. Under winding, embedding, and long-term vibration conditions, the outer glass fiber yarn is prone to wear, fuzzing, or even breakage, damaging the integrity of the insulation structure. Third, in order to improve heat dissipation performance, some technologies have attempted to add thermally conductive fillers between the glass fiber layers, but these often intrude into the insulation interface due to improper distribution of the thermally conductive medium, leading to deterioration of electrical performance and making it difficult to achieve synergistic optimization of efficient heat dissipation and reliable insulation. Summary of the Invention

[0004] To address the aforementioned technical deficiencies, this invention presents a wear-resistant double glass filament copper-clad flat wire and its preparation method. The prepared wear-resistant double glass filament copper-clad flat wire possesses excellent insulation, efficient heat dissipation, and high surface wear resistance.

[0005] A wear-resistant double glass fiber-clad copper flat wire includes an inner layer of TU1 oxygen-free copper flat wire, and a composite modified insulating varnish layer, a thermally conductive and high-temperature resistant alkali-free glass fiber yarn, a composite modified insulating varnish layer, and a wear-resistant reinforcing glass fiber yarn coated with a wear-resistant ceramic coating arranged sequentially from the inside to the outside of the TU1 oxygen-free copper flat wire surface. The composite modified insulating varnish layer is formed by high-temperature curing of the composite modified insulating varnish liquid, which is prepared by modifying hydroxylated silicon nitride powder with dimethyl biphenyl diisocyanate and amino-terminated hyperbranched polyamide. The wear-resistant ceramic coating is formed by high-temperature curing and pyrolysis of the wear-resistant ceramic coating precursor slurry. The wear-resistant ceramic coating precursor slurry is prepared by ball milling a vinyl hyperbranched polysiloxane obtained by reacting vinyltrimethoxysilane and 1,3-propanediol with titanium boride, polycarbosilane and xylene.

[0006] A method for preparing wear-resistant double glass filament copper-clad flat wire includes the following steps: S1: Preparation of composite modified insulating varnish; S2: Preparation of wear-resistant ceramic coating precursor slurry; S3: Assembly and curing of wear-resistant double glass fiber-clad copper flat wire.

[0007] Furthermore, the preparation of the composite modified insulating varnish in step S1 specifically includes the following steps: S1.1: Disperse silicon nitride powder in a nitric acid solution with a mass fraction of 50-60% at a solid-liquid ratio of 1:(3-4), stir at 80-90℃ for 3-5 hours, then filter and collect the residue, wash with deionized water, centrifuge until neutral, and then dry in a vacuum drying oven at 80-85℃ to constant weight. After grinding, obtain hydroxylated silicon nitride powder. S1.2: Hydroxylated silicon nitride powder is ultrasonically dispersed in N,N-dimethylformamide for 1-1.5 h, and the solid content is controlled at 10-12% to obtain a hydroxylated silicon nitride suspension. Then, under a nitrogen protective atmosphere, dimethylbiphenyl diisocyanate and dibutyltin dilaurate are added and stirred for 8-10 h to obtain an isocyanate-modified silicon nitride suspension. S1.3: The amino-terminated hyperbranched polyamide and isocyanate-modified silicon nitride suspension were placed in a container at a mass ratio of 1:(2-3) and stirred until homogeneous. The mixture was then allowed to stand for 18-20 hours under a nitrogen atmosphere. The resulting reaction solution was washed by centrifugation with acetone until the upper liquid was colorless and clear. The solid powder obtained by vacuum filtration was then placed in an electric heating drying oven at 80-85℃ and dried for 3-4 hours to obtain composite modified silicon nitride. S1.4: Dissolve bisphenol A type epoxy resin E51 in N,N-dimethylformamide to prepare an epoxy resin solution with a mass concentration of 30-40%. Then add 3-5 wt% of composite modified silicon nitride to the epoxy resin solution and stir to mix evenly. Then perform vacuum distillation at 135-140℃ to completely remove N,N-dimethylformamide. Then, based on the mass of bisphenol A type epoxy resin E51, add 80-85 phr of methyltetrahydrophthalic anhydride and 5-7 phr of hexahydropyridine to obtain a composite modified insulating varnish.

[0008] Further, step S2, preparing the wear-resistant ceramic coating precursor slurry, specifically includes the following steps: S2.1: Vinyltrimethoxysilane and 1,3-propanediol are placed in a reaction vessel at a mass ratio of 1:(0.6-0.8) and stirred until homogeneous. The reaction vessel contains a stirrer, a thermometer, and an air inlet, as well as a condensation recovery vessel connected to it. Nitrogen gas is introduced as a protective gas. The temperature inside the reaction vessel is raised to 115-120°C at a stirring speed of 150-200 rpm. The temperature inside the condensation recovery vessel is controlled at 45-50°C. When liquid distills out of the condensation recovery vessel, the temperature inside the reaction vessel is raised to 175-185°C. The reaction is continued until no new liquid distills out of the condensation recovery vessel. The substances inside the reaction vessel are collected to obtain vinyl hyperbranched polysiloxane. S2.2: Mix vinyl hyperbranched polysiloxane, titanium boride and polycarbosilane in a mass ratio of 1:(2-3):(5-6) in a container to obtain a mixture. Then add xylene in 2-3 times the mass of the mixture, stir for 30-40 min and place in a ball mill jar. Use zirconium oxide as the ball milling medium and ball mill at 500-600 rpm for 8-10 h to obtain a wear-resistant ceramic coating precursor slurry.

[0009] Furthermore, step S3, the assembly and curing of the wear-resistant double glass fiber-clad copper flat wire, specifically includes the following steps: S3.1: Add 2-5 ppm of chloroplatinic acid to the wear-resistant ceramic coating precursor slurry, then fix high-temperature resistant alkali-free glass fiber yarn with a diameter of 40-50 μm on an immersion dip coating machine, immerse it in the wear-resistant ceramic coating precursor slurry containing chloroplatinic acid at an immersion speed of 3-4 mm / s, so that the slurry completely covers the high-temperature resistant alkali-free glass fiber yarn, for 10-12 s, then pull it out at a speed of 3-4 mm / s, and place it in a blower dryer, heat it to 175-180℃ in an air atmosphere at a heating rate of 1-1.5℃ / min, hold it at that temperature for 2-3 h, then cool it down to room temperature at a cooling rate of 1.5-2℃ / min, and then place it in an atmosphere sintering furnace at 800-805℃, and pyrolyze it in an argon atmosphere for 30-40 min to obtain wear-resistant reinforced glass fiber yarn coated with a wear-resistant ceramic coating; S3.2: Use sandpaper to smooth the surface of TU1 oxygen-free copper flat wire, and wipe it with ethanol and acetone 2-3 times in sequence. Place it in an enameling machine and apply composite modified insulating varnish. The thickness of each varnish layer is 8-10μm. Perform two varnishing operations in total. Then heat and cure to form a composite modified insulating varnish layer to obtain insulated copper flat wire. S3.3: Apply TT500 thermally conductive silicone grease to both sides of a 40-50μm diameter high-temperature resistant alkali-free glass fiber yarn, with a total coating area of ​​1 / 2 of the total surface area of ​​the yarn and a thickness of 12-15μm, to obtain thermally conductive, high-temperature resistant, alkali-free glass fiber yarn. Then, wrap the yarn around an insulated copper flat wire at a wrapping angle of 10-15°, ensuring that the contact surfaces of the yarns are coated with TT500 thermally conductive silicone grease. This results in a first-stage glass fiber-wrapped copper flat wire, which is then placed in an enameling machine for painting. A composite modified insulating varnish is used, with each pass producing a film thickness of 8-10μm. Two passes are performed. After curing, a composite modified insulating varnish layer is formed. Then, maintaining the wrapping angle, only the wrapping direction is changed, and another layer of wear-resistant reinforcing glass fiber yarn is wrapped in the opposite direction to obtain a wear-resistant double-glass fiber-wrapped copper flat wire.

[0010] Further, in step S1.2, the mass ratio of hydroxylated silicon nitride powder, dimethyl biphenyl diisocyanate, and dibutyltin dilaurate is 1:(13-15):(0.01-0.02).

[0011] Furthermore, in step S1.3, the molecular weight of the terminal amino hyperbranched polyamide is 1400-1600 Da.

[0012] Furthermore, in step S2.2, the molecular weight of the polycarbosilane is 1500-2000 Da.

[0013] Furthermore, the high-temperature resistant alkali-free glass fiber yarn in steps S3.1 and S3.3 is made by twisting alkali-free glass fiber filaments with a softening point of 860°C.

[0014] Furthermore, the temperature curing operation in steps S3.2 and S3.3 is as follows: first, keep at 110-115℃ for 1 hour, then keep at 150-160℃ for 2 hours, and then keep at 180-185℃ for 3 hours. Beneficial effects

[0015] 1. This invention produces a composite modified insulating varnish by hydroxylating silicon nitride and then sequentially modifying it with dimethyl biphenyl diisocyanate and amino-terminated hyperbranched polyamide. In this process, dimethyl biphenyl diisocyanate first reacts with the hydroxyl groups on the surface of silicon nitride to introduce highly reactive isocyanate groups onto the filler surface. Subsequently, the amino groups of the amino-terminated hyperbranched polyamide react with the isocyanate groups to generate urea groups, forming chemical bonds. The hyperbranched polyamide has a three-dimensional dendritic structure with multiple amino groups densely distributed on its periphery, enabling "multi-point anchoring" coating of the filler surface. A flexible yet rigid organic-inorganic transition layer was constructed on the surface of silicon nitride particles. This modified silicon nitride, used as a filler in an epoxy resin matrix, significantly improved the interfacial compatibility between the inorganic filler and the organic resin, inhibiting particle agglomeration and achieving nanoscale uniform dispersion of the filler within the matrix. Furthermore, the steric hindrance effect and multi-point anchoring of the hyperbranched structure greatly enhanced the interfacial bonding strength and reduced microscopic interfacial defects. This interfacial layer effectively hindered carrier migration and captured space charge, thereby significantly improving the volume resistivity and breakdown field strength of the insulating varnish. This resulted in a composite modified insulating varnish with excellent electrical insulation properties, providing a stable foundation for the subsequent use of double-glass-filament copper-clad flat wires.

[0016] 2. This invention utilizes a segmented, temperature-controlled polycondensation reaction of vinyltrimethoxysilane with 1,3-propanediol to prepare a hyperbranched polysiloxane with a main chain containing Si-O-Si and Si-OC hybrid structures and a periphery rich in vinyl groups. This hyperbranched polymer exhibits high reactivity: its peripheral vinyl groups can undergo hydrosilylation reactions with the Si-H bonds in the polycarbosilane during subsequent high-temperature curing, forming a covalent cross-linked network; simultaneously, the three-dimensional morphology of the hyperbranched structure effectively coats hard titanium boride particles, preventing their aggregation through steric stabilization, and forming a gradient transition interface from a flexible organic layer to a rigid ceramic phase during the ceramization process. After uniformly dispersing vinyl hyperbranched polysiloxane, polycarbosilane, and titanium boride through ball milling, the resulting precursor slurry can be transformed into a dense ceramic coating with SiC / SiO2 as the continuous phase and TiB2 as the hard reinforcing phase through coating and high-temperature pyrolysis. This coating forms a strong chemical bond interface with the underlying glass fiber and insulating varnish. Its high hardness, low coefficient of friction, and excellent anti-abrasive wear performance significantly improve the wear resistance of the copper flat wire surface.

[0017] 3. This invention applies TT500 thermally conductive silicone grease to both sides of the high-temperature resistant alkali-free glass fiber yarn, filling the gaps between the contact surfaces of the high-temperature resistant alkali-free glass fiber yarn with TT500 thermally conductive silicone grease. This strictly confines the thermally conductive silicone grease to the area where the high-temperature resistant alkali-free glass fiber yarns come into contact with each other, preventing the silicone grease from diffusing into the interface between the fiber yarn and the inner and outer insulating varnishes. This eliminates the risk of insulation degradation. Without sacrificing the integrity of the insulation system, the invention optimizes the interlayer thermal conductivity of the winding, enabling the double glass fiber-clad copper flat wire to maintain excellent electrical insulation performance while also possessing efficient heat dissipation capabilities. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1:

[0019] A wear-resistant double glass fiber coated copper flat wire includes an inner layer of TU1 oxygen-free copper flat wire, and a composite modified insulating varnish layer, a thermally conductive and high-temperature resistant alkali-free glass fiber yarn, a composite modified insulating varnish layer, and a wear-resistant reinforcing glass fiber yarn coated with a wear-resistant ceramic coating, arranged sequentially from the inside to the outside of the TU1 oxygen-free copper flat wire. The preparation method includes the following steps: S1: Preparation of composite modified insulating varnish S1.1: Silicon nitride powder was dispersed in a 50% nitric acid solution at a solid-liquid ratio of 1:3 and stirred at 80°C for 3 hours. The residue was then collected by filtration, washed with deionized water, centrifuged until neutral, and then dried in a vacuum drying oven at 80°C until constant weight. After grinding, hydroxylated silicon nitride powder was obtained. S1.2: Hydroxylated silicon nitride powder was ultrasonically dispersed in N,N-dimethylformamide for 1 hour, with the solid content controlled at 10%, to obtain a hydroxylated silicon nitride suspension. Then, under a nitrogen protective atmosphere, dimethylbiphenyl diisocyanate and dibutyltin dilaurate were added and stirred for 8 hours to obtain an isocyanate-modified silicon nitride suspension. The mass ratio of hydroxylated silicon nitride powder, dimethylbiphenyl diisocyanate, and dibutyltin dilaurate was 1:13:0.01. S1.3: A terminal amino hyperbranched polyamide with a molecular weight of 1400 Da and isocyanate modified silicon nitride suspension were placed in a container at a mass ratio of 1:2 and stirred until homogeneous. The mixture was then allowed to stand for 18 hours under a nitrogen atmosphere. The resulting reaction solution was centrifuged and washed with acetone until the upper liquid was colorless and clear. The solid powder obtained by vacuum filtration was then placed in an electric heating drying oven at 80°C and dried for 3 hours to obtain composite modified silicon nitride. S1.4: Dissolve bisphenol A type epoxy resin E51 in N,N-dimethylformamide to prepare an epoxy resin solution with a mass concentration of 30%. Then add 3 wt% of composite modified silicon nitride to the epoxy resin solution and stir to mix evenly. Then perform vacuum distillation at 135℃ to completely remove N,N-dimethylformamide. Then, based on the mass of bisphenol A type epoxy resin E51, add 80 phr of methyltetrahydrophthalic anhydride and 5 phr of hexahydropyridine to obtain a composite modified insulating varnish.

[0020] S2: Preparation of wear-resistant ceramic coating precursor slurry S2.1: Vinyltrimethoxysilane and 1,3-propanediol were placed in a reaction vessel at a mass ratio of 1:0.6 and stirred until homogeneous. The reaction vessel contained a stirrer, a thermometer, and an air inlet, as well as a condenser recovery vessel connected to it. Nitrogen gas was introduced as a protective gas. The temperature inside the reaction vessel was raised to 115°C at a stirring speed of 150 rpm, and the temperature inside the condenser recovery vessel was controlled at 45°C. When liquid distilled out of the condenser recovery vessel, the temperature inside the reaction vessel was raised to 175°C. The reaction was continued until no new liquid distilled out of the condenser recovery vessel. The substances inside the reaction vessel were collected to obtain vinyl hyperbranched polysiloxane. S2.2: Vinyl hyperbranched polysiloxane, titanium boride, and polycarbosilane with a molecular weight of 1500 Da are mixed in a container at a mass ratio of 1:2:5 to obtain a mixture. Then, xylene with a mass of 2 times that of the mixture is added, and the mixture is stirred for 30 minutes. The mixture is then placed in a ball mill jar and ball milled at 500 rpm for 8 hours using zirconium oxide as the ball milling medium to obtain a wear-resistant ceramic coating precursor slurry.

[0021] S3: Assembly and curing of wear-resistant double glass fiber-clad copper flat wire S3.1: Add 2 ppm of chloroplatinic acid to the wear-resistant ceramic coating precursor slurry, and then fix a 40 μm diameter high-temperature alkali-free glass fiber yarn on an immersion and pull coating machine. The high-temperature alkali-free glass fiber yarn is made of alkali-free glass fiber filaments with a softening point of 860℃ twisted together. It is immersed in the wear-resistant ceramic coating precursor slurry containing chloroplatinic acid at an immersion speed of 3 mm / s, so that the slurry completely covers the high-temperature alkali-free glass fiber yarn for 10 s. Then it is pulled out at a speed of 3 mm / s and placed in a blower dryer. It is heated to 175℃ in an air atmosphere at a heating rate of 1℃ / min and held for 2 h. Then it is cooled to room temperature at a cooling rate of 1.5℃ / min. Then it is placed in an atmosphere sintering furnace at 800℃ and pyrolyzed in an argon atmosphere for 30 min to obtain wear-resistant reinforced glass fiber yarn coated with a wear-resistant ceramic coating. S3.2: The surface of the TU1 oxygen-free copper flat wire is polished smooth with sandpaper, and then wiped twice with ethanol and acetone in sequence. It is then placed in an enameling machine and coated with composite modified insulating varnish. The thickness of each coating layer is 8μm. Two coating layers are applied in total. Then, the wire is heated and cured. First, it is kept at 110℃ for 1 hour, then at 150℃ for 2 hours, and then at 180℃ for 3 hours to form a composite modified insulating varnish layer, thus obtaining the insulated copper flat wire. S3.3: Apply TT500 thermally conductive silicone grease to both sides of a 40μm diameter high-temperature resistant alkali-free glass fiber yarn, with the total coating area accounting for 1 / 2 of the total surface area of ​​the high-temperature resistant alkali-free glass fiber yarn and a thickness of 12μm, to obtain thermally conductive high-temperature resistant alkali-free glass fiber yarn. Then, wrap the thermally conductive high-temperature resistant alkali-free glass fiber yarn around an insulated copper flat wire at a wrapping angle of 10°. The contact surfaces of the thermally conductive high-temperature resistant alkali-free glass fiber yarn wrapped around the insulated copper flat wire are the sides coated with TT500 thermally conductive silicone grease, resulting in a first-stage glass fiber wrapped copper flat wire. Place it in an enameling machine for painting, using a composite modified insulating varnish. The varnish film thickness of each pass is 8μm, and a total of 2 passes are performed. After heating and curing according to the conditions in step S3.2 to form a composite modified insulating varnish layer, only change the wrapping direction and wrap another layer of wear-resistant reinforcing glass fiber yarn in the opposite direction to obtain a wear-resistant double glass fiber wrapped copper flat wire. Example 2:

[0022] A wear-resistant double glass fiber coated copper flat wire includes an inner layer of TU1 oxygen-free copper flat wire, and a composite modified insulating varnish layer, a thermally conductive and high-temperature resistant alkali-free glass fiber yarn, a composite modified insulating varnish layer, and a wear-resistant reinforcing glass fiber yarn coated with a wear-resistant ceramic coating, arranged sequentially from the inside to the outside of the TU1 oxygen-free copper flat wire. The preparation method includes the following steps: S1: Preparation of composite modified insulating varnish S1.1: Silicon nitride powder was dispersed in a 55% nitric acid solution at a solid-liquid ratio of 1:3.5 and stirred at 85°C for 4 hours. The residue was then collected by filtration, washed with deionized water, centrifuged until neutral, and then dried in a vacuum drying oven at 82°C until constant weight. After grinding, hydroxylated silicon nitride powder was obtained. S1.2: Hydroxylated silicon nitride powder was ultrasonically dispersed in N,N-dimethylformamide for 1.2 h, and the solid content was controlled at 11% to obtain a hydroxylated silicon nitride suspension. Then, under a nitrogen protective atmosphere, dimethyl biphenyl diisocyanate and dibutyltin dilaurate were added and stirred for 9 h to obtain an isocyanate-modified silicon nitride suspension. The mass ratio of hydroxylated silicon nitride powder, dimethyl biphenyl diisocyanate and dibutyltin dilaurate was 1:14:0.015. S1.3: A 1500 Da terminal amino hyperbranched polyamide and isocyanate modified silicon nitride suspension were placed in a container and stirred until homogeneous. The mixture was then allowed to stand for 19 h under a nitrogen atmosphere. The resulting reaction solution was washed by centrifugation with acetone until the supernatant was colorless and clear. The solid powder obtained by vacuum filtration was then placed in an electric heating drying oven at 82 °C and dried for 3.5 h to obtain composite modified silicon nitride. S1.4: Dissolve bisphenol A type epoxy resin E51 in N,N-dimethylformamide to prepare an epoxy resin solution with a mass concentration of 35%. Then add 4 wt% of composite modified silicon nitride to the epoxy resin solution and stir to mix evenly. Then perform vacuum distillation at 138℃ to completely remove N,N-dimethylformamide. Then, based on the mass of bisphenol A type epoxy resin E51, add 82 phr of methyltetrahydrophthalic anhydride and 6 phr of hexahydropyridine to obtain a composite modified insulating varnish.

[0023] S2: Preparation of wear-resistant ceramic coating precursor slurry S2.1: Vinyltrimethoxysilane and 1,3-propanediol are placed in a reaction vessel at a mass ratio of 1:0.7 and stirred until homogeneous. The reaction vessel contains a stirrer, a thermometer, and an air inlet, as well as a condenser recovery vessel connected to it. Nitrogen gas is introduced as a protective gas. The temperature inside the reaction vessel is raised to 118°C at a stirring speed of 180 rpm, and the temperature inside the condenser recovery vessel is controlled at 48°C. When liquid distills out of the condenser recovery vessel, the temperature inside the reaction vessel is raised to 180°C. The reaction is continued until no new liquid distills out of the condenser recovery vessel. The substances inside the reaction vessel are collected to obtain vinyl hyperbranched polysiloxane. S2.2: Vinyl hyperbranched polysiloxane, titanium boride, and polycarbosilane with a molecular weight of 1800 Da are mixed in a container at a mass ratio of 1:2.5:5.5 to obtain a mixture. Then, xylene with a mass of 2.5 times that of the mixture is added, and the mixture is stirred for 35 minutes. The mixture is then placed in a ball mill jar and ball milled at 550 rpm for 9 hours using zirconium oxide as the ball milling medium to obtain a wear-resistant ceramic coating precursor slurry.

[0024] S3: Assembly and curing of wear-resistant double glass fiber-clad copper flat wire S3.1: Add 3 ppm of chloroplatinic acid to the wear-resistant ceramic coating precursor slurry, and then fix a 45 μm diameter high-temperature alkali-free glass fiber yarn on an immersion and pull coating machine. The high-temperature alkali-free glass fiber yarn is made of alkali-free glass fiber filaments with a softening point of 860℃ twisted together. It is immersed in the wear-resistant ceramic coating precursor slurry containing chloroplatinic acid at an immersion speed of 3.5 mm / s, so that the slurry completely covers the high-temperature alkali-free glass fiber yarn for 11 seconds. Then it is pulled out at a speed of 3.5 mm / s and placed in a blower dryer. It is heated to 175℃ in an air atmosphere at a heating rate of 1.5℃ / min and held for 2.5 h. Then it is cooled to room temperature at a cooling rate of 2℃ / min. Then it is placed in an atmosphere sintering furnace at 803℃ and pyrolyzed in an argon atmosphere for 35 min to obtain wear-resistant reinforced glass fiber yarn coated with a wear-resistant ceramic coating. S3.2: The surface of the TU1 oxygen-free copper flat wire is polished smooth with sandpaper, and then wiped three times with ethanol and acetone in sequence. It is then placed in an enameling machine and coated with composite modified insulating varnish. The thickness of each coating layer is 9μm. A total of two coating operations are performed. Then, the wire is heated and cured. First, it is kept at 112℃ for 1 hour, then at 155℃ for 2 hours, and then at 182℃ for 3 hours to form a composite modified insulating varnish layer, thus obtaining an insulated copper flat wire. S3.3: Apply TT500 thermally conductive silicone grease to both sides of a 45μm diameter high-temperature resistant alkali-free glass fiber yarn, with the total coating area accounting for 1 / 2 of the total surface area of ​​the high-temperature resistant alkali-free glass fiber yarn and a thickness of 14μm, to obtain thermally conductive high-temperature resistant alkali-free glass fiber yarn. Then, wrap the thermally conductive high-temperature resistant alkali-free glass fiber yarn around an insulated copper flat wire at a wrapping angle of 12°. The contact surfaces of the thermally conductive high-temperature resistant alkali-free glass fiber yarn wrapped around the insulated copper flat wire are the sides coated with TT500 thermally conductive silicone grease, resulting in a first-stage glass fiber wrapped copper flat wire. Place it in an enameling machine for painting, using a composite modified insulating varnish. The varnish film thickness of each pass is 9μm, and a total of 2 passes are performed. After heating and curing according to the conditions in step S3.1 to form a composite modified insulating varnish layer, only the wrapping direction is changed, and another layer of wear-resistant reinforcing glass fiber yarn is wrapped in the opposite direction to obtain a wear-resistant double glass fiber wrapped copper flat wire. Example 3:

[0025] A wear-resistant double glass fiber coated copper flat wire includes an inner layer of TU1 oxygen-free copper flat wire, and a composite modified insulating varnish layer, a thermally conductive and high-temperature resistant alkali-free glass fiber yarn, a composite modified insulating varnish layer, and a wear-resistant reinforcing glass fiber yarn coated with a wear-resistant ceramic coating, arranged sequentially from the inside to the outside of the TU1 oxygen-free copper flat wire. The preparation method includes the following steps: S1: Preparation of composite modified insulating varnish S1.1: Silicon nitride powder was dispersed in a 60% nitric acid solution at a solid-liquid ratio of 1:4 and stirred at 90°C for 5 hours. The residue was then collected by filtration, washed with deionized water, centrifuged until neutral, and then dried in a vacuum drying oven at 85°C until constant weight. After grinding, hydroxylated silicon nitride powder was obtained. S1.2: Hydroxylated silicon nitride powder was ultrasonically dispersed in N,N-dimethylformamide for 1.5 h, and the solid content was controlled at 12% to obtain a hydroxylated silicon nitride suspension. Then, under a nitrogen protective atmosphere, dimethyl biphenyl diisocyanate and dibutyltin dilaurate were added and stirred for 10 h to obtain an isocyanate-modified silicon nitride suspension. The mass ratio of hydroxylated silicon nitride powder, dimethyl biphenyl diisocyanate and dibutyltin dilaurate was 1:15:0.02. S1.3: A terminal amino hyperbranched polyamide with a molecular weight of 1600 Da and isocyanate modified silicon nitride suspension were placed in a container at a mass ratio of 1:3 and stirred until homogeneous. The mixture was then allowed to stand for 20 hours under a nitrogen atmosphere. The resulting reaction solution was washed by centrifugation with acetone until the upper liquid was colorless and clear. The solid powder obtained by vacuum filtration was then placed in an electric heating drying oven at 85°C and dried for 4 hours to obtain composite modified silicon nitride. S1.4: Dissolve bisphenol A type epoxy resin E51 in N,N-dimethylformamide to prepare an epoxy resin solution with a mass concentration of 40%. Then add 5 wt% of composite modified silicon nitride to the epoxy resin solution and stir to mix evenly. Then perform vacuum distillation at 140℃ to completely remove N,N-dimethylformamide. Then, based on the mass of bisphenol A type epoxy resin E51, add 85 phr of methyltetrahydrophthalic anhydride and 7 phr of hexahydropyridine to obtain a composite modified insulating varnish.

[0026] S2: Preparation of wear-resistant ceramic coating precursor slurry S2.1: Vinyltrimethoxysilane and 1,3-propanediol were placed in a reaction vessel at a mass ratio of 1:0.8 and stirred until homogeneous. The reaction vessel contained a stirrer, a thermometer, and an air inlet, as well as a condenser recovery vessel connected to it. Nitrogen gas was introduced as a protective gas. The temperature inside the reaction vessel was raised to 120°C at a stirring speed of 200 rpm, and the temperature inside the condenser recovery vessel was controlled at 50°C. When liquid distilled out of the condenser recovery vessel, the temperature inside the reaction vessel was raised to 185°C. The reaction was continued until no new liquid distilled out of the condenser recovery vessel. The substances inside the reaction vessel were collected to obtain vinyl hyperbranched polysiloxane. S2.2: Vinyl hyperbranched polysiloxane, titanium boride, and polycarbosilane with a molecular weight of 2000 Da are mixed in a container at a mass ratio of 1:3:6 to obtain a mixture. Then, xylene with a mass of 3 times that of the mixture is added, and the mixture is stirred for 40 minutes. The mixture is then placed in a ball mill jar and ball milled at 600 rpm for 10 hours using zirconium oxide as the ball milling medium to obtain a wear-resistant ceramic coating precursor slurry.

[0027] S3: Assembly and curing of wear-resistant double glass fiber-clad copper flat wire S3.1: Add 5 ppm of chloroplatinic acid to the wear-resistant ceramic coating precursor slurry, and then fix a 50 μm diameter high-temperature alkali-free glass fiber yarn on an immersion and pull coating machine. The high-temperature alkali-free glass fiber yarn is made of alkali-free glass fiber filaments with a softening point of 860℃ twisted together. It is immersed in the wear-resistant ceramic coating precursor slurry containing chloroplatinic acid at an immersion speed of 4 mm / s, so that the slurry completely covers the high-temperature alkali-free glass fiber yarn for 12 s. Then it is pulled out at a speed of 4 mm / s and placed in a blower dryer. It is heated to 180℃ in an air atmosphere at a heating rate of 1.5℃ / min and held for 3 h. Then it is cooled to room temperature at a cooling rate of 2℃ / min. Then it is placed in an atmosphere sintering furnace at 805℃ and pyrolyzed in an argon atmosphere for 40 min to obtain wear-resistant reinforced glass fiber yarn coated with a wear-resistant ceramic coating. S3.2: The surface of the TU1 oxygen-free copper flat wire is polished smooth with sandpaper, and then wiped three times with ethanol and acetone in sequence. It is then placed in an enameling machine and coated with composite modified insulating varnish. The thickness of the varnish film is 10μm for each pass, and a total of two passes are performed. Then, the wire is heated and cured. First, it is kept at 115℃ for 1 hour, then at 160℃ for 2 hours, and then at 185℃ for 3 hours to form a composite modified insulating varnish layer, thus obtaining the insulated copper flat wire. S3.3: Apply TT500 thermally conductive silicone grease to both sides of a 50μm diameter high-temperature resistant alkali-free glass fiber yarn, with the total coating area accounting for 1 / 2 of the total surface area of ​​the high-temperature resistant alkali-free glass fiber yarn and a thickness of 15μm, to obtain thermally conductive high-temperature resistant alkali-free glass fiber yarn. Then, wrap the thermally conductive high-temperature resistant alkali-free glass fiber yarn around an insulated copper flat wire at a wrapping angle of 15°. The contact surfaces of the thermally conductive high-temperature resistant alkali-free glass fiber yarn wrapped around the insulated copper flat wire are the sides coated with TT500 thermally conductive silicone grease, resulting in a first-stage glass fiber wrapped copper flat wire. Place the wire in an enameling machine for painting, using a composite modified insulating varnish. Each coat has a film thickness of 10μm, and two coats are performed. After heating and curing according to the conditions in step S3.1 to form a composite modified insulating varnish layer, simply change the wrapping direction and wrap another layer of wear-resistant reinforcing glass fiber yarn in the opposite direction to obtain a wear-resistant double glass fiber wrapped copper flat wire.

[0028] Comparative Example 1: The difference from Example 1 is that steps S2 and S3.1 are removed in this comparative example, and the wear-resistant reinforced glass fiber yarn in step S3.3 is replaced with high-temperature resistant alkali-free glass fiber yarn. The remaining steps are the same as in Example 1.

[0029] Comparative Example 2: The difference from Example 1 is that the thermally conductive, high-temperature resistant, alkali-free glass fiber yarn in step S3.3 is replaced with high-temperature resistant, alkali-free glass fiber yarn, while the other steps are the same as in Example 1.

[0030] Comparative Example 3: The difference from Example 1 is that in step S3.3, TT500 thermal conductive silicone grease was applied to the surface of a high-temperature resistant alkali-free glass fiber yarn with a diameter of 40μm, completely covering it with a thickness of 12μm. The remaining steps were the same as in Example 1.

[0031] Experiment 1: Breakdown voltage test: The composite modified insulating varnish prepared in Examples 1-3 and commercially available D700 epoxy resin insulating varnish were used as control groups. The breakdown voltage of the samples was tested using a breakdown voltage tester according to the ASTM D149-20 standard. The test samples were made by casting according to the standard, with a diameter of 100 mm and a thickness of 1 mm. Volume resistivity test: The composite modified insulating varnish prepared in Examples 1-3 and commercially available D700 epoxy resin insulating varnish were placed in a mold to prepare cylindrical samples with a length of 100 mm and a diameter of 20 mm. The volume resistivity was tested in a volume resistivity tester. The breakdown voltage and volume resistivity tests of each group were performed 3 times. The average value of the test results is shown in Table 1.

[0032] Table 1: Breakdown voltage and volume resistivity of insulating varnish

[0033] As can be seen from the data of Examples 1-3 and the control group in Table 1, the products prepared in the examples of this application have better breakdown field strength and volume resistivity than the commercially available D700 epoxy resin insulating varnish of the control group. This proves that the composite modified insulating varnish prepared by the present invention through hydroxylation of silicon nitride and subsequent modification by dimethyl biphenyl diisocyanate and amino-terminated hyperbranched polyamide has excellent electrical insulation properties.

[0034] Experiment 2: The copper flat wires with double glass filaments prepared in Examples 1-3 and Comparative Example 1 were used as samples. The wear resistance of the samples was tested according to the standard GB / T4074.3-2008. Three samples were taken from each group for testing, and the data were recorded as shown in Table 2.

[0035] Table 2: Abrasion resistance of double glass fiber-insulated copper flat wire

[0036] As can be seen from the data of Examples 1-3 and Comparative Example 1 in Table 2, the products prepared in the examples of this application have excellent wear resistance, and compared with Comparative Example 1, their wear resistance is greatly improved. This proves that the invention obtains a wear-resistant ceramic coating with high wear resistance by uniformly mixing vinyl hyperbranched polysiloxane, polycarbosilane, and titanium boride through a segmented temperature-controlled polycondensation reaction of vinyltrimethoxysilane and 1,3-propanediol, and then undergoing high-temperature pyrolysis.

[0037] Experiment 3: Single-layer glass fiber-wrapped copper flat wires of equal length were prepared using the preparation methods of Examples 1-3, Comparative Examples 2 and 3, respectively. All were coated with a composite modified insulating varnish, with each coat having a film thickness of 8 μm, for a total of two coats. One end of each glass fiber-wrapped copper flat wire was then cut to expose the cross-section of the inner oxygen-free copper flat wire, thus obtaining a test sample. The test sample was heated to a temperature of 40°C, and the exposed oxygen-free copper flat wire was measured using a thermometer. Then, the exposed oxygen-free copper flat wire was quickly removed from the test sample. The sample was placed in methyl silicone oil to prevent heat dissipation. Then, the cooling fan was turned on to blow air onto the other end of the test sample (wind speed 4 m / s, blowing distance 30 cm) for 2 minutes. The temperature of the exposed oxygen-free copper flat wire after the air was blown was then measured. The average value of the three tests was recorded in Table 3. The composite modified insulating varnish film on the surface of the test sample was removed, and the surface resistance of the varnish film was measured using a YH-8200 digital insulation resistance tester. The test voltage was 100V, and the average value of the three tests was recorded in Table 3. The test results are shown in Table 3.

[0038] Table 3: Influence of heat dissipation performance and thermal grease application method on insulation performance of double glass fiber-insulated copper flat wire

[0039] As can be seen from the data of Examples 1-3 in Table 3, the copper flat wire of the present invention has good heat dissipation performance. The insulating varnish can also maintain good insulation performance even when thermally conductive silicone grease is added. As can be seen from the data of Comparative Example 2, the thermal conductivity is lower than that of Example 1 when thermally conductive silicone grease is not applied to both sides of the high-temperature alkali-free glass fiber yarn, and the surface resistance is comparable. As can be seen from the data of Comparative Example 3, although the thermal conductivity is better when the surface of the high-temperature alkali-free glass fiber yarn is fully coated with thermally conductive silicone grease, it significantly reduces the surface resistance of the varnish film. This proves that by applying TT500 thermally conductive silicone grease to both sides of the high-temperature alkali-free glass fiber yarn, the present application achieves the optimization of the interlayer thermal conductivity of the winding without sacrificing the integrity of the insulation system. This allows the double glass fiber-insulated copper flat wire to maintain excellent electrical insulation performance while also having efficient heat dissipation capability.

[0040] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A wear-resistant double glass fiber coated copper flat wire, comprising an inner layer of TU1 oxygen-free copper flat wire, and a composite modified insulating varnish layer, a thermally conductive and high-temperature resistant alkali-free glass fiber yarn, a composite modified insulating varnish layer and a wear-resistant reinforcing glass fiber yarn coated with a wear-resistant ceramic coating arranged sequentially from the inside to the outside of the TU1 oxygen-free copper flat wire surface. The composite modified insulating varnish layer is formed by high-temperature curing of the composite modified insulating varnish liquid, which is prepared by modifying hydroxylated silicon nitride with dimethyl biphenyl diisocyanate and amino-terminated hyperbranched polyamide. The wear-resistant ceramic coating is formed by high-temperature curing and pyrolysis of the wear-resistant ceramic coating precursor slurry. The wear-resistant ceramic coating precursor slurry is prepared by ball milling a vinyl hyperbranched polysiloxane obtained by reacting vinyltrimethoxysilane and 1,3-propanediol with titanium boride, polycarbosilane and xylene.

2. A method for preparing a wear-resistant double glass filament copper-clad flat wire as described in claim 1, characterized in that, Includes the following steps: S1: Preparation of composite modified insulating varnish; S2: Preparation of wear-resistant ceramic coating precursor slurry; S3: Assembly and curing of wear-resistant double glass fiber-clad copper flat wire.

3. The method for preparing wear-resistant double glass filament copper-clad flat wire according to claim 2, characterized in that, Step S1, the preparation of the composite modified insulating varnish, specifically includes the following steps: S1.1: Disperse silicon nitride powder in a nitric acid solution with a mass fraction of 50-60% at a solid-liquid ratio of 1:(3-4), stir at 80-90℃ for 3-5 hours, then filter and collect the residue, wash with deionized water, centrifuge until neutral, and then dry in a vacuum drying oven at 80-85℃ to constant weight. After grinding, obtain hydroxylated silicon nitride powder. S1.2: Hydroxylated silicon nitride powder is ultrasonically dispersed in N,N-dimethylformamide for 1-1.5 h, and the solid content is controlled at 10-12% to obtain a hydroxylated silicon nitride suspension. Then, under a nitrogen protective atmosphere, dimethylbiphenyl diisocyanate and dibutyltin dilaurate are added and stirred for 8-10 h to obtain an isocyanate-modified silicon nitride suspension. S1.3: The amino-terminated hyperbranched polyamide and isocyanate-modified silicon nitride suspension were placed in a container at a mass ratio of 1:(2-3) and stirred until homogeneous. The mixture was then allowed to stand for 18-20 hours under a nitrogen atmosphere. The resulting reaction solution was washed by centrifugation with acetone until the upper liquid was colorless and clear. The solid powder obtained by vacuum filtration was then placed in an electric heating drying oven at 80-85℃ and dried for 3-4 hours to obtain composite modified silicon nitride. S1.4: Dissolve bisphenol A type epoxy resin E51 in N,N-dimethylformamide to prepare an epoxy resin solution with a mass concentration of 30-40%. Then add 3-5 wt% of composite modified silicon nitride to the epoxy resin solution and stir to mix evenly. Then perform vacuum distillation at 135-140℃ to completely remove N,N-dimethylformamide. Then, based on the mass of bisphenol A type epoxy resin E51, add 80-85 phr of methyltetrahydrophthalic anhydride and 5-7 phr of hexahydropyridine to obtain a composite modified insulating varnish.

4. The method for preparing wear-resistant double glass filament copper-clad flat wire according to claim 2, characterized in that, Step S2 involves preparing the wear-resistant ceramic coating precursor slurry, specifically including the following steps: S2.1: Vinyltrimethoxysilane and 1,3-propanediol are placed in a reaction vessel at a mass ratio of 1:(0.6-0.8) and stirred until homogeneous. The reaction vessel contains a stirrer, a thermometer, and an air inlet, as well as a condensation recovery vessel connected to it. Nitrogen gas is introduced as a protective gas. The temperature inside the reaction vessel is raised to 115-120°C at a stirring speed of 150-200 rpm. The temperature inside the condensation recovery vessel is controlled at 45-50°C. When liquid distills out of the condensation recovery vessel, the temperature inside the reaction vessel is raised to 175-185°C. The reaction is continued until no new liquid distills out of the condensation recovery vessel. The substances inside the reaction vessel are collected to obtain vinyl hyperbranched polysiloxane. S2.2: Mix vinyl hyperbranched polysiloxane, titanium boride and polycarbosilane in a mass ratio of 1:(2-3):(5-6) in a container to obtain a mixture. Then add xylene in 2-3 times the mass of the mixture, stir for 30-40 min and place in a ball mill jar. Use zirconium oxide as the ball milling medium and ball mill at 500-600 rpm for 8-10 h to obtain a wear-resistant ceramic coating precursor slurry.

5. The method for preparing wear-resistant double glass filament copper-clad flat wire according to claim 2, characterized in that, Step S3, the assembly and curing of the wear-resistant double glass fiber-clad copper flat wire, specifically includes the following steps: S3.1: Add 2-5 ppm of chloroplatinic acid to the wear-resistant ceramic coating precursor slurry, then fix high-temperature resistant alkali-free glass fiber yarn with a diameter of 40-50 μm on an immersion dip coating machine, immerse it in the wear-resistant ceramic coating precursor slurry containing chloroplatinic acid at an immersion speed of 3-4 mm / s, so that the slurry completely covers the high-temperature resistant alkali-free glass fiber yarn, for 10-12 s, then pull it out at a speed of 3-4 mm / s, and place it in a blower dryer, heat it to 175-180℃ in an air atmosphere at a heating rate of 1-1.5℃ / min, hold it at that temperature for 2-3 h, then cool it down to room temperature at a cooling rate of 1.5-2℃ / min, and then place it in an atmosphere sintering furnace at 800-805℃, and pyrolyze it in an argon atmosphere for 30-40 min to obtain wear-resistant reinforced glass fiber yarn coated with a wear-resistant ceramic coating; S3.2: Use sandpaper to smooth the surface of TU1 oxygen-free copper flat wire, and wipe it with ethanol and acetone 2-3 times in sequence. Place it in an enameling machine and apply composite modified insulating varnish. The thickness of each varnish layer is 8-10μm. Perform two varnishing operations in total. Then heat and cure to form a composite modified insulating varnish layer to obtain insulated copper flat wire. S3.3: Apply TT500 thermally conductive silicone grease to both sides of a 40-50μm diameter high-temperature resistant alkali-free glass fiber yarn, with a total coating area of ​​1 / 2 of the total surface area of ​​the yarn and a thickness of 12-15μm, to obtain thermally conductive, high-temperature resistant, alkali-free glass fiber yarn. Then, wrap the yarn around an insulated copper flat wire at a wrapping angle of 10-15°, ensuring that the contact surfaces of the yarns are coated with TT500 thermally conductive silicone grease. This results in a first-stage glass fiber wrapped copper flat wire, which is then placed in an enameling machine for painting. A composite modified insulating varnish is used, with each pass producing a varnish film thickness of 8-10μm. Two passes are performed. After curing, a composite modified insulating varnish layer is formed. Then, while maintaining the wrapping angle, only the wrapping direction is changed, and a layer of wear-resistant reinforcing glass fiber yarn is wrapped in the opposite direction to obtain a wear-resistant double glass fiber wrapped copper flat wire.

6. The method for preparing a wear-resistant double glass filament copper-clad flat wire according to claim 3, characterized in that, In step S1.2, the mass ratio of hydroxylated silicon nitride powder, dimethyl biphenyl diisocyanate, and dibutyltin dilaurate is 1:(13-15):(0.01-0.02).

7. The method for preparing a wear-resistant double glass filament copper-clad flat wire according to claim 3, characterized in that, The molecular weight of the terminal amino hyperbranched polyamide in step S1.3 is 1400-1600 Da.

8. The method for preparing a wear-resistant double glass filament copper-clad flat wire according to claim 4, characterized in that, In step S2.2, the molecular weight of the polycarbosilane is 1500-2000 Da.

9. The method for preparing a wear-resistant double glass filament copper-clad flat wire according to claim 5, characterized in that, The high-temperature resistant alkali-free glass fiber yarn in steps S3.1 and S3.3 is made by twisting alkali-free glass fiber filaments with a softening point of 860℃.

10. The method for preparing a wear-resistant double glass filament copper-clad flat wire according to claim 5, characterized in that, The curing process in steps S3.2 and S3.3 involves first maintaining the temperature at 110-115℃ for 1 hour, then maintaining the temperature at 150-160℃ for 2 hours, and finally maintaining the temperature at 180-185℃ for 3 hours.

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