A corona-resistant varnish material for copper flat wire and its preparation method

Abstract

This invention relates to the field of copper flat wire coating technology, specifically to a corona-resistant coating material for copper flat wire and its preparation method, comprising the following raw materials in parts by weight: 35-40 parts polyesterimide resin, 25-30 parts aramid resin, 7-11 parts modified graphene agent, 5-8 parts silicon nitride-based modifier, 5-8 parts functional additives, 15-25 parts solvent, and 7-11 parts curing agent. The corona-resistant coating material of this invention is a compound of polyesterimide resin and aramid resin, blended by adding functional additives, solvent, and curing agent. Simultaneously, the addition of modified graphene agent and silicon nitride-based modifier provides synergistic effects, resulting in a synergistic improvement in corona resistance, adhesion, thermal conductivity, and abrasion resistance. Furthermore, the product exhibits high-temperature stability at varying degrees.

Description

Technical Field

[0001] This invention relates to the field of copper flat wire coating technology, specifically to a corona-resistant coating material for copper flat wire and its preparation method. Background Technology

[0002] Enameled wire is a major raw material for motors, electrical appliances, and household appliances. Especially in recent years, the rapid development of electrical appliances has broadened the application scope of enameled wire, leading to higher requirements for it. However, existing enamel materials used for copper flat wires, in order to optimize the product's corona resistance, tend to reduce the adhesion, thermal conductivity, and abrasion resistance of the enamel material. Furthermore, the product's stability at varying high temperatures is poor, limiting its efficiency. Therefore, this invention provides further improvements. Summary of the Invention

[0003] In view of the deficiencies of the prior art, the purpose of this invention is to provide a corona-resistant varnish material for copper flat wire and its preparation method, so as to solve the problems mentioned in the background art.

[0004] The present invention solves the technical problem by adopting the following technical solution: This invention provides a corona-resistant varnish material for copper flat wire, comprising the following raw materials in parts by weight: Polyester imide resin 35-40 parts, aramid resin 25-30 parts, modified graphene agent 7-11 parts, silicon nitride-based modifier 5-8 parts, functional additive 5-8 parts, solvent 15-25 parts, curing agent 7-11 parts.

[0005] Preferably, the corona-resistant paint material comprises the following raw materials in parts by weight: 37.5 parts polyesterimide resin, 27.5 parts aramid resin, 9 parts modified graphene agent, 6.5 parts silicon nitride-based modifier, 6.5 parts functional additive, 20 parts solvent, and 9 parts curing agent.

[0006] Preferably, the polyester imine resin is a saturated polyester resin containing an imine structure and hydroxyl groups, with a hydroxyl value of 90-110 mgKOH / g, an acid value ≤8 mgKOH / g, and an imine content of 20-22%. The aramid resin is poly(m-phenylene isophthalamide) resin, and the solid content of the poly(m-phenylene isophthalamide) resin is 17-18%. The functional additives are leveling agents, defoamers and coupling agents compounded in a weight ratio of (1-2):(1-2):1; wherein the leveling agent is BYK-346 leveling agent, the defoamer is BYK-A530 defoamer, and the coupling agent is silane coupling agent KH560. The solvent is a compound of N-methylpyrrolidone, xylene and ethylene glycol butyl ether in a weight ratio of (5-7):(2-4):(1-2); The curing agent is an isocyanate curing agent, and the isocyanate content in the isocyanate curing agent is 30-32%.

[0007] Preferably, the method for preparing the modified graphene agent is as follows: S01, Preparation of the shaking fluid: γ-glycidyl etheroxypropyltrimethoxysilane and ethanol are mixed thoroughly at a weight ratio of (20-30):100 to obtain a silane-ethanol solution. Then, 5-8 parts by weight of cerium oxide, 2-3 parts by weight of carbon nanotubes and 1-3 parts by weight of silicon carbide whiskers are mixed and added to 8-12 parts by weight of the silane-ethanol solution and stirred evenly to obtain a shaking liquid. S02, preheat graphene at 55-65℃ for 1-1.5h to obtain preheated graphene, and then ultrasonically vibrate the preheated graphene in an oscillating liquid with a weight of 4-7 times the total weight of the preheated graphene at 350-400W for 1-2h to obtain an oscillating graphene liquid. SO3, Preparation of the modifier: S04. Add 25-30% of the total amount of modifier to the vibrating graphene liquid and perform ball milling treatment. The ball milling speed is 1000-1500 r / min and the ball milling time is 1-2 h. After the ball milling is completed, filter and dry to obtain the modified graphene agent.

[0008] Preferably, the carbon nanotube is a multi-walled carbon nanotube, with an outer diameter of 10-30 nm and a length of 5-20 μm. The silicon carbide whiskers have a diameter of 0.2-1.0 μm and an aspect ratio of (20-50):1. The graphene sheet has a diameter of 50-100 nm, a thickness of 0.8-3 nm, and 1-5 layers.

[0009] Preferably, the modifier is prepared by: Boron carbide, a dopamine hydrochloride solution with a mass concentration of 1.5-3 g / L, and nanocellulose are mixed thoroughly at a weight ratio of (3-5):7:(1-2) to obtain a modified boron carbide solution; then 4-7 parts by weight of barium sulfate, 3-5 parts by weight of titanium dioxide, and 5-8 parts by weight of the modified boron carbide solution are stirred evenly, filtered, and dried to obtain the modifier.

[0010] The modified graphene agent uses graphene that has been preheated and modified, then treated with ultrasonic vibration in an oscillating liquid, and ball milled in conjunction with the modifier. The oscillating liquid is a matrix material made by blending cerium oxide, carbon nanotubes and silicon carbide whiskers. The high specific surface area of ​​the carbon nanotubes is used to coordinate with the whisker-like structure of silicon carbide whiskers, while cerium oxide is also used. The mixture is then modified by blending with a silane-ethanol solution, so that the graphene is jointly supported and synergistically supported by the carbon nanotubes and silicon carbide whiskers, which optimizes the dispersion performance of graphene and better combines with the resin matrix, thereby optimizing the performance of the product. Meanwhile, the modifier is blended with barium sulfate and titanium dioxide, and then enhanced by modified boron carbide solution. Through the mutual optimization and improvement of boron carbide, dopamine hydrochloride solution and nanocellulose in the modified boron carbide solution, the resulting modifier further enhances the performance coordination of the product in the system, optimizes the product's corona discharge, adhesion, thermal conductivity and wear resistance, and improves the product's high temperature stability at different levels.

[0011] Preferably, the solvent for the dopamine hydrochloride solution is a TrisHCl buffer solution with a pH of 8.5 to 10.

[0012] Preferably, the preparation method of the modifier based on silicon nitride is as follows: S11, 5-8 parts by weight of silicon nitride, 2-3 parts by weight of sericite powder, 5-8 parts by weight of sodium dodecylbenzenesulfonate solution and 1-2 parts by weight of hydroxyapatite are mixed evenly to obtain a silicon nitride-based additive solution. S12, 2-4 parts by weight of lanthanum oxide, 1-3 parts by weight of albite powder, 2-5 parts by weight of zirconium oxide and 5-8 parts by weight of chitosan solution with a mass fraction of 2-5% are thoroughly mixed, then filtered and dried to obtain the modifier. S13, the silicon nitride-based additive liquid and the modifier are mixed and ball-milled at a weight ratio of (7-11):5, the ball milling speed is 1000-1500 r / min, the ball milling is 2h, after the ball milling is completed, the mixture is filtered and dried to obtain the modifier based on silicon nitride.

[0013] Preferably, the sericite powder has a flake diameter of 5-25 μm, a flake thickness of 0.1-1 μm, and a diameter-to-thickness ratio of (40-60):1; the sodium dodecylbenzenesulfonate solution has a mass fraction of 6-10%.

[0014] The modifier based on silicon nitride uses silicon nitride, sericite powder, and hydroxyapatite as the matrix, and then combines lanthanum oxide, albite powder, and zirconium oxide. Through the mutual reinforcement and coordination among the raw materials, the modifier based on silicon nitride and the modified graphene agent have a better synergistic effect, thereby further improving the performance of the product.

[0015] This invention also provides a method for preparing a corona-resistant varnish material for copper flat wire, comprising the following steps: Weigh the raw materials according to the weight proportions, and add the polyesterimide resin, aramid resin, modified graphene agent, silicon nitride-based modifier, functional additive, solvent and curing agent into the mixer in sequence and stir and mix them. The stirring speed is 550-750 r / min, and the stirring is carried out for 2-3 hours. After stirring is completed, the corona-resistant paint material is obtained.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The corona-resistant paint material of this invention is made of polyesterimide resin and aramid resin compounded and blended by adding functional additives, solvents and curing agents. At the same time, it is co-blended and coordinated by adding modified graphene agent and silicon nitride-based modifier, which enhance the effect of each other. The resulting corona-resistant paint material has improved corona resistance, adhesion, thermal conductivity and wear resistance in a coordinated manner, and the product is also resistant to high temperature stability at different levels. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. 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.

[0018] This embodiment provides a corona-resistant varnish material for copper flat wire, comprising the following raw materials in parts by weight: Polyester imide resin 35-40 parts, aramid resin 25-30 parts, modified graphene agent 7-11 parts, silicon nitride-based modifier 5-8 parts, functional additive 5-8 parts, solvent 15-25 parts, curing agent 7-11 parts.

[0019] The corona-resistant paint material of this embodiment comprises the following raw materials in parts by weight: 37.5 parts polyesterimide resin, 27.5 parts aramid resin, 9 parts modified graphene agent, 6.5 parts silicon nitride-based modifier, 6.5 parts functional additive, 20 parts solvent, and 9 parts curing agent.

[0020] The polyester imine resin in this embodiment is a saturated polyester resin containing imine structure and hydroxyl groups, with a hydroxyl value of 90-110 mgKOH / g, an acid value of ≤8 mgKOH / g, and an imine content of 20-22%. The aramid resin is poly(m-phenylene isophthalamide) resin, and the solid content of the poly(m-phenylene isophthalamide) resin is 17-18%. The functional additives are leveling agents, defoamers and coupling agents compounded in a weight ratio of (1-2):(1-2):1; wherein the leveling agent is BYK-346 leveling agent, the defoamer is BYK-A530 defoamer, and the coupling agent is silane coupling agent KH560. The solvent is a compound of N-methylpyrrolidone, xylene and ethylene glycol butyl ether in a weight ratio of (5-7):(2-4):(1-2); The curing agent is an isocyanate curing agent, and the isocyanate content in the isocyanate curing agent is 30-32%.

[0021] The preparation method of the modified graphene agent in this embodiment is as follows: S01, Preparation of the shaking fluid: γ-glycidyl etheroxypropyltrimethoxysilane and ethanol are mixed thoroughly at a weight ratio of (20-30):100 to obtain a silane-ethanol solution. Then, 5-8 parts by weight of cerium oxide, 2-3 parts by weight of carbon nanotubes and 1-3 parts by weight of silicon carbide whiskers are mixed and added to 8-12 parts by weight of the silane-ethanol solution and stirred evenly to obtain a shaking liquid. S02, preheat graphene at 55-65℃ for 1-1.5h to obtain preheated graphene, and then ultrasonically vibrate the preheated graphene in an oscillating liquid with a weight of 4-7 times the total weight of the preheated graphene at 350-400W for 1-2h to obtain an oscillating graphene liquid. SO3, Preparation of the modifier: S04. Add 25-30% of the total amount of modifier to the vibrating graphene liquid and perform ball milling treatment. The ball milling speed is 1000-1500 r / min and the ball milling time is 1-2 h. After the ball milling is completed, filter and dry to obtain the modified graphene agent.

[0022] The carbon nanotubes in this embodiment are multi-walled carbon nanotubes with an outer diameter of 10-30 nm and a length of 5-20 μm. The silicon carbide whiskers have a diameter of 0.2-1.0 μm and an aspect ratio of (20-50):1. The graphene sheet has a diameter of 50-100 nm, a thickness of 0.8-3 nm, and 1-5 layers.

[0023] The preparation method of the modifier in this embodiment is as follows: Boron carbide, a dopamine hydrochloride solution with a mass concentration of 1.5-3 g / L, and nanocellulose are mixed thoroughly at a weight ratio of (3-5):7:(1-2) to obtain a modified boron carbide solution; then 4-7 parts by weight of barium sulfate, 3-5 parts by weight of titanium dioxide, and 5-8 parts by weight of the modified boron carbide solution are stirred evenly, filtered, and dried to obtain the modifier.

[0024] The solvent for the dopamine hydrochloride solution in this embodiment is a TrisHCl buffer solution with a pH of 8.5~10.

[0025] The preparation method of the modifier based on silicon nitride in this embodiment is as follows: S11, 5-8 parts by weight of silicon nitride, 2-3 parts by weight of sericite powder, 5-8 parts by weight of sodium dodecylbenzenesulfonate solution and 1-2 parts by weight of hydroxyapatite are mixed evenly to obtain a silicon nitride-based additive solution. S12, 2-4 parts by weight of lanthanum oxide, 1-3 parts by weight of albite powder, 2-5 parts by weight of zirconium oxide and 5-8 parts by weight of chitosan solution with a mass fraction of 2-5% are thoroughly mixed, then filtered and dried to obtain the modifier. S13, the silicon nitride-based additive liquid and the modifier are mixed and ball-milled at a weight ratio of (7-11):5, the ball milling speed is 1000-1500 r / min, the ball milling is 2h, after the ball milling is completed, the mixture is filtered and dried to obtain the modifier based on silicon nitride.

[0026] In this embodiment, the sericite powder has a flake diameter of 5-25 μm, a flake thickness of 0.1-1 μm, and a diameter-to-thickness ratio of (40-60):1; the sodium dodecylbenzenesulfonate solution has a mass fraction of 6-10%.

[0027] This embodiment describes a method for preparing a corona-resistant varnish material for copper flat wire, comprising the following steps: Weigh the raw materials according to the weight proportions, and add the polyesterimide resin, aramid resin, modified graphene agent, silicon nitride-based modifier, functional additive, solvent and curing agent into the mixer in sequence and stir and mix them. The stirring speed is 550-750 r / min, and the stirring is carried out for 2-3 hours. After stirring is completed, the corona-resistant paint is obtained.

[0028] Example 1

[0029] This embodiment provides a corona-resistant varnish material for copper flat wire, comprising the following raw materials in parts by weight: 35 parts polyesterimide resin, 25 parts aramid resin, 7 parts modified graphene agent, 5 parts silicon nitride-based modifier, 5 parts functional additive, 15 parts solvent, and 7 parts curing agent.

[0030] The polyester imine resin in this embodiment is a saturated polyester resin containing imine structure and hydroxyl groups, with a hydroxyl value of 90 mgKOH / g, an acid value of ≤8 mgKOH / g, and an imine content of 20%. The aramid resin is poly(m-phenylene isophthalamide) resin, and the solid content of the poly(m-phenylene isophthalamide) resin is 17%. The functional additive is a mixture of leveling agent, defoamer and coupling agent in a weight ratio of 1:1:1; wherein the leveling agent is BYK-346 leveling agent, the defoamer is BYK-A530 defoamer, and the coupling agent is silane coupling agent KH560. The solvent is a compound of N-methylpyrrolidone, xylene and ethylene glycol butyl ether in a weight ratio of 5:2:1. The curing agent is an isocyanate curing agent, and the isocyanate content in the isocyanate curing agent is 30%.

[0031] The preparation method of the modified graphene agent in this embodiment is as follows: S01, Preparation of the shaking fluid: γ-glycidoxypropyltrimethoxysilane and ethanol were mixed thoroughly at a weight ratio of 20:100 to obtain a silane-ethanol solution. Then, 5 parts by weight of cerium oxide, 2 parts by weight of carbon nanotubes and 1 part by weight of silicon carbide whiskers were mixed and added to 8 parts by weight of the silane-ethanol solution and stirred evenly to obtain a shaking liquid. S02, preheat graphene at 55℃ for 1 hour to obtain preheated graphene, and then ultrasonically vibrate the preheated graphene in an oscillating liquid with a weight of 4 times the total weight of the preheated graphene at 350W for 1 hour to obtain oscillating graphene liquid. SO3, Preparation of the modifier: S04. Add 25% of the modifier of the total amount of the oscillating graphene liquid to the oscillating graphene liquid and perform modification ball milling treatment. The ball milling speed is 1000 r / min and the ball milling time is 1 h. After the ball milling is completed, filter and dry to obtain the modified graphene agent.

[0032] The carbon nanotubes in this embodiment are multi-walled carbon nanotubes with an outer diameter of 10 nm and a length of 5 μm. The silicon carbide whiskers have a diameter of 0.2 μm and an aspect ratio of 20:1. The graphene sheet has a diameter of 50 nm, a thickness of 0.8 nm, and a layer count of 1.

[0033] The preparation method of the modifier in this embodiment is as follows: Boron carbide, a 1.5 g / L dopamine hydrochloride solution, and nanocellulose were mixed thoroughly in a weight ratio of 3:7:1 to obtain a modified boron carbide solution. Then, 4 parts by weight of barium sulfate, 3 parts by weight of titanium dioxide, and 5 parts by weight of the modified boron carbide solution were stirred evenly, filtered, and dried to obtain the modifier.

[0034] The solvent for the dopamine hydrochloride solution in this embodiment is a TrisHCl buffer solution with a pH of 8.5.

[0035] The preparation method of the modifier based on silicon nitride in this embodiment is as follows: S11, 5 parts by weight of silicon nitride, 2 parts by weight of sericite powder, 5 parts by weight of sodium dodecylbenzenesulfonate solution and 1 part of hydroxyapatite are mixed evenly to obtain a silicon nitride-based additive solution. S12, 2 parts by weight of lanthanum oxide, 1 part by weight of albite powder, 2 parts by weight of zirconium oxide and 5 parts by weight of chitosan solution with a mass fraction of 2% are thoroughly mixed, then filtered and dried to obtain the additive material. S13, the silicon nitride-based additive liquid and the modifier were mixed and ball-milled at a weight ratio of 7:5. The ball milling speed was 1000 r / min and the ball milling time was 2 h. After the ball milling was completed, the mixture was filtered and dried to obtain the modifier based on silicon nitride.

[0036] In this embodiment, the sericite powder has a flake diameter of 5 μm, a flake thickness of 0.1 μm, and a diameter-to-thickness ratio of 40:1; the sodium dodecylbenzenesulfonate solution has a mass fraction of 6%.

[0037] This embodiment describes a method for preparing a corona-resistant varnish material for copper flat wire, comprising the following steps: Weigh the raw materials according to the weight proportions, and add the polyesterimide resin, aramid resin, modified graphene agent, silicon nitride-based modifier, functional additive, solvent and curing agent into the mixer in sequence and stir and mix them. The stirring speed is 550 r / min and the stirring time is 2h. After stirring is completed, the corona resistant paint is obtained.

[0038] Example 2

[0039] This embodiment provides a corona-resistant varnish material for copper flat wire, comprising the following raw materials in parts by weight: 40 parts polyesterimide resin, 30 parts aramid resin, 11 parts modified graphene agent, 8 parts silicon nitride-based modifier, 8 parts functional additive, 25 parts solvent, and 11 parts curing agent.

[0040] The polyester imine resin in this embodiment is a saturated polyester resin containing imine structure and hydroxyl groups, with a hydroxyl value of 110 mgKOH / g, an acid value of ≤8 mgKOH / g, and an imine content of 22%. The aramid resin is poly(m-phenylene isophthalamide) resin, and the solid content of the poly(m-phenylene isophthalamide) resin is 18%. The functional additive is a mixture of leveling agent, defoamer and coupling agent in a weight ratio of 2:2:1; wherein the leveling agent is BYK-346 leveling agent, the defoamer is BYK-A530 defoamer, and the coupling agent is silane coupling agent KH560. The solvent is a compound of N-methylpyrrolidone, xylene and ethylene glycol butyl ether in a weight ratio of 7:4:2. The curing agent is an isocyanate curing agent, and the isocyanate content in the isocyanate curing agent is 32%.

[0041] The preparation method of the modified graphene agent in this embodiment is as follows: S01, Preparation of the shaking fluid: γ-glycidyl etheroxypropyltrimethoxysilane and ethanol were mixed thoroughly at a weight ratio of 30:100 to obtain a silane-ethanol solution. Then, 8 parts by weight of cerium oxide, 3 parts by weight of carbon nanotubes and 3 parts by weight of silicon carbide whiskers were mixed and added to 12 parts by weight of the silane-ethanol solution and stirred evenly to obtain a shaking liquid. S02, preheat graphene at 65℃ for 1.5h to obtain preheated graphene, and then ultrasonically vibrate the preheated graphene in an oscillating liquid with a weight of 7 times the total weight of the preheated graphene at 400W for 2h to obtain oscillated graphene liquid. SO3, Preparation of the modifier: S04. Add 30% of the modifier of the total amount of the oscillating graphene liquid to the oscillating graphene liquid and perform modification ball milling treatment. The ball milling speed is 1500 r / min and the ball milling is performed for 2 hours. After the ball milling is completed, filter and dry to obtain the modified graphene agent.

[0042] The carbon nanotubes in this embodiment are multi-walled carbon nanotubes with an outer diameter of 30 nm and a length of 20 μm. The silicon carbide whiskers have a diameter of 1.0 μm and an aspect ratio of 50:1. The graphene sheet has a diameter of 100 nm, a thickness of 3 nm, and 5 layers.

[0043] The preparation method of the modifier in this embodiment is as follows: Boron carbide, a 3 g / L dopamine hydrochloride solution, and nanocellulose were mixed thoroughly in a weight ratio of 5:7:2 to obtain a modified boron carbide solution. Then, 7 parts by weight of barium sulfate, 5 parts by weight of titanium dioxide, and 8 parts by weight of the modified boron carbide solution were stirred evenly, filtered, and dried to obtain the modifier.

[0044] The solvent for the dopamine hydrochloride solution in this embodiment is a TrisHCl buffer solution with pH=10.

[0045] The preparation method of the modifier based on silicon nitride in this embodiment is as follows: S11, 8 parts by weight of silicon nitride, 3 parts by weight of sericite powder, 8 parts by weight of sodium dodecylbenzenesulfonate solution and 2 parts by weight of hydroxyapatite are mixed evenly to obtain a silicon nitride-based additive solution. S12, 4 parts by weight of lanthanum oxide, 3 parts by weight of albite powder, 5 parts by weight of zirconium oxide and 8 parts by weight of chitosan solution with a mass fraction of 5% are thoroughly mixed, then filtered and dried to obtain the additive material. S13, the silicon nitride-based additive liquid and the modifier were mixed and ball-milled at a weight ratio of 11:5. The ball milling speed was 1500 r / min and the ball milling time was 2 h. After the ball milling was completed, the mixture was filtered and dried to obtain the modifier based on silicon nitride.

[0046] In this embodiment, the sericite powder has a flake diameter of 25 μm, a flake thickness of 1 μm, and a diameter-to-thickness ratio of 60:1; the sodium dodecylbenzenesulfonate solution has a mass fraction of 10%.

[0047] This embodiment describes a method for preparing a corona-resistant varnish material for copper flat wire, comprising the following steps: Weigh the raw materials according to the weight proportions, and add the polyesterimide resin, aramid resin, modified graphene agent, silicon nitride-based modifier, functional additive, solvent and curing agent into the mixer in sequence and stir and mix them. The stirring speed is 750 r / min and the stirring time is 3h. After stirring is completed, the corona resistant paint is obtained.

[0048] Example 3.

[0049] This embodiment provides a corona-resistant varnish material for copper flat wire, comprising the following raw materials in parts by weight: 37.5 parts polyesterimide resin, 27.5 parts aramid resin, 9 parts modified graphene agent, 6.5 parts silicon nitride-based modifier, 6.5 parts functional additive, 20 parts solvent, and 9 parts curing agent.

[0050] The polyester imine resin in this embodiment is a saturated polyester resin containing imine structure and hydroxyl groups, with a hydroxyl value of 100 mgKOH / g, an acid value of ≤8 mgKOH / g, and an imine content of 21%. The aramid resin is poly(m-phenylene isophthalamide) resin, and the solid content of the poly(m-phenylene isophthalamide) resin is 17.5%. The functional additive is a compound of leveling agent, defoamer and coupling agent in a weight ratio of 1.5:1.5:1; wherein the leveling agent is BYK-346 leveling agent, the defoamer is BYK-A530 defoamer, and the coupling agent is silane coupling agent KH560. The solvent is a compound of N-methylpyrrolidone, xylene, and ethylene glycol butyl ether in a weight ratio of 6:3:1.5. The curing agent is an isocyanate curing agent, and the isocyanate content in the isocyanate curing agent is 31%.

[0051] The preparation method of the modified graphene agent in this embodiment is as follows: S01, Preparation of the shaking fluid: γ-glycidoxypropyltrimethoxysilane and ethanol were thoroughly mixed at a weight ratio of 25:100 to obtain a silane-ethanol solution. Then, 6.5 parts by weight of cerium oxide, 2.5 parts by weight of carbon nanotubes and 2 parts by weight of silicon carbide whiskers were mixed and added to 10 parts by weight of the silane-ethanol solution and stirred evenly to obtain a shaking liquid. S02, preheat graphene at 60℃ for 1.2h to obtain preheated graphene, and then ultrasonically vibrate the preheated graphene in an oscillating liquid with a weight of 5.5 times the total weight of the preheated graphene at 375W for 1.5h to obtain an oscillating graphene liquid. SO3, Preparation of the modifier: S04. Add 27.5% of the total amount of modifier to the vibrating graphene liquid and perform ball milling treatment. The ball milling speed is 1250 r / min and the ball milling time is 1.5 h. After the ball milling is completed, filter and dry to obtain the modified graphene agent.

[0052] The carbon nanotubes in this embodiment are multi-walled carbon nanotubes with an outer diameter of 20 nm and a length of 10 μm. The silicon carbide whiskers have a diameter of 0.6 μm and an aspect ratio of 35:1. The graphene sheet has a diameter of 75 nm, a thickness of 1.5 nm, and 3 layers.

[0053] The preparation method of the modifier in this embodiment is as follows: Boron carbide, a 2.0 g / L dopamine hydrochloride solution, and nanocellulose were mixed thoroughly in a weight ratio of 4:7:1.5 to obtain a modified boron carbide solution. Then, 5.5 parts by weight of barium sulfate, 4 parts by weight of titanium dioxide, and 6.5 parts by weight of the modified boron carbide solution were stirred evenly, filtered, and dried to obtain the modifier.

[0054] The solvent for the dopamine hydrochloride solution in this embodiment is TrisHCl buffer solution with pH=9.0.

[0055] The preparation method of the modifier based on silicon nitride in this embodiment is as follows: S11, 6.5 parts by weight of silicon nitride, 2.5 parts by weight of sericite powder, 6.5 parts by weight of sodium dodecylbenzenesulfonate solution and 1.5 parts by weight of hydroxyapatite are mixed evenly to obtain a silicon nitride-based additive solution. S12, 3 parts by weight of lanthanum oxide, 2 parts by weight of albite powder, 3.5 parts by weight of zirconium oxide and 6.5 parts by weight of chitosan solution with a mass fraction of 3.5% are thoroughly mixed, then filtered and dried to obtain the modifier. S13, the silicon nitride-based additive liquid and the modifier were mixed and ball-milled at a weight ratio of 9:5. The ball milling speed was 1250 r / min and the ball milling time was 2 h. After the ball milling was completed, the mixture was filtered and dried to obtain the modifier based on silicon nitride.

[0056] In this embodiment, the sericite powder has a flake diameter of 10 μm, a flake thickness of 0.5 μm, and a diameter-to-thickness ratio of 50:1; the sodium dodecylbenzenesulfonate solution has a mass fraction of 8%.

[0057] This embodiment describes a method for preparing a corona-resistant varnish material for copper flat wire, comprising the following steps: Weigh the raw materials according to the weight proportions, and add the polyesterimide resin, aramid resin, modified graphene agent, silicon nitride-based modifier, functional additive, solvent and curing agent into the mixer in sequence and stir and mix them. The stirring speed is 600 r / min and the stirring is carried out for 2.5 h. After stirring is completed, the corona resistant paint is obtained.

[0058] Comparative Example 1 Unlike Example 3, no modified graphene agent was added.

[0059] Comparative Example 2 Unlike Example 3, the modified graphene agent was not treated with an oscillating liquid during preparation.

[0060] Comparative Example 3 Unlike Example 3, no carbon nanotubes and silicon carbide whiskers were added in the preparation of the oscillating liquid.

[0061] Comparative Example 4 Unlike Example 3, no modifier was added during the preparation of the modified graphene agent.

[0062] Comparative Example 5 Unlike Example 3, barium sulfate and titanium dioxide were not added during the preparation of the modifier.

[0063] Comparative Example 6 Unlike Example 3, boron carbide and nanocellulose were not added in the preparation of the modified boron carbide solution.

[0064] Comparative Example 7 Unlike Example 3, no silicon nitride-based additives were added.

[0065] Comparative Example 8 Unlike Example 3, no modifier was added in the preparation of the modifier based on silicon nitride.

[0066] Comparative Example 9 Unlike Example 3, no albite powder or zirconium oxide was added to the additive.

[0067] Comparative Example 10 Unlike Example 3, no silicon nitride-based additive solution was added in the preparation of the silicon nitride-based additive.

[0068] Comparative Example 11 Unlike Example 3, sericite powder and hydroxyapatite were not added in the preparation of the silicon nitride-based additive solution.

[0069] The products of Examples 1-3 and Comparative Examples 1-11 were coated onto the surface of copper flat wire. After coating, the wire was pre-baked at 160°C for 5 minutes and cured at 260°C for 2 minutes to form a varnish film with a thickness of 0.15 mm. Then, the wire was subjected to corona resistance (refer to standard GB / T24122-2009 "Varnish for Corona-Resistant Enameled Wire", power frequency AC voltage 3kV, frequency 50Hz). The following were the results of routine performance tests (GB / T1720-2020 for adhesion grade testing); thermal conductivity (GB / T 10294-2008 "Determination of Steady-State Thermal Resistance and Related Heat Transfer Properties of Insulation Materials - Protective Hot Plate Method"); and abrasion resistance (GB / T 1768-2006 "Determination of Abrasion Resistance of Paints and Varnishes - Rotating Rubber Grinding Wheel Method" with a load of 500g and a rotation speed of 60r / min, using the maximum number of friction revolutions before the paint film is worn through) at 25℃ and 50% humidity. As can be seen from the above performance tests, the anti-corona life, adhesion level, thermal conductivity and wear resistance of the products of Examples 1-3 and Comparative Examples 1-11 can all be improved in a coordinated manner. At the same time, the performance of the products of Comparative Examples 1-11 is not as good as that of Example 3 of the present invention, and the performance of the product of the present invention is the best.

[0070] The high-temperature stability of the product was further tested after being placed at 75℃ and 100℃ for 72 hours. The test results are as follows; As can be seen from Comparative Examples 1-11 and Examples 1-3; The product in Example 3 exhibits excellent high-temperature stability at 75℃ and 100℃, demonstrating stability at different temperatures. Furthermore, it maintains excellent performance stability even at a high temperature of 100℃. Without the addition of either the modified graphene agent or the silicon nitride-based modifier, the performance of the product tends to deteriorate significantly. By combining the modified graphene agent and the silicon nitride-based modifier, the product's performance is significantly improved. In the preparation of modified graphene agents, no oscillating fluid treatment was used; no carbon nanotubes and silicon carbide whiskers were added in the preparation of the oscillating fluid; no modifier was added in the preparation of the modified graphene agent; no barium sulfate and titanium dioxide were added in the preparation of the modifier; and no boron carbide and nanocellulose were added in the preparation of the modified boron carbide solution. The performance of the products all tended to deteriorate to varying degrees. Only the modified graphene agent obtained by using the oscillating fluid and modifier obtained by the specific method of this invention showed the most significant performance improvement. Other methods were not as effective as those of this invention. In the preparation of modifiers based on silicon nitride, if no modifier is added, if the modifier does not contain albite powder or zirconium oxide, if the modifier does not contain a silicon nitride-based additive solution, and if the silicon nitride-based additive solution does not contain sericite powder or hydroxyapatite, the performance of the product tends to deteriorate. Only modifiers based on silicon nitride prepared using the specific method and process steps of this invention exhibit the most significant performance improvement.

[0071] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0072] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A corona-resistant varnish material for copper flat wire, characterized in that, Including the following parts by weight of raw materials: Polyester imide resin 35-40 parts, aramid resin 25-30 parts, modified graphene agent 7-11 parts, silicon nitride-based modifier 5-8 parts, functional additive 5-8 parts, solvent 15-25 parts, curing agent 7-11 parts.

2. The corona-resistant varnish material for copper flat wire according to claim 1, characterized in that, The corona-resistant paint material comprises the following raw materials in parts by weight: 37.5 parts polyesterimide resin, 27.5 parts aramid resin, 9 parts modified graphene agent, 6.5 parts silicon nitride-based modifier, 6.5 parts functional additive, 20 parts solvent, and 9 parts curing agent.

3. The corona-resistant varnish material for copper flat wire according to claim 1, characterized in that, The polyester imine resin is a saturated polyester resin containing imine structure and hydroxyl groups, with a hydroxyl value of 90-110 mgKOH / g, an acid value of ≤8 mgKOH / g, and an imine content of 20-22%. The aramid resin is poly(m-phenylene isophthalamide) resin, and the solid content of the poly(m-phenylene isophthalamide) resin is 17-18%. The functional additive is a mixture of leveling agent, defoamer and coupling agent in a weight ratio of (1-2):(1-2):1; The solvent is a compound of N-methylpyrrolidone, xylene and ethylene glycol butyl ether in a weight ratio of (5-7):(2-4):(1-2); The curing agent is an isocyanate curing agent, and the isocyanate content in the isocyanate curing agent is 30-32%.

4. The corona-resistant varnish material for copper flat wire according to claim 1, characterized in that, The preparation method of the modified graphene agent is as follows: S01, Preparation of the shaking fluid: γ-glycidyl etheroxypropyltrimethoxysilane and ethanol are mixed thoroughly at a weight ratio of (20-30):100 to obtain a silane-ethanol solution. Then, 5-8 parts by weight of cerium oxide, 2-3 parts by weight of carbon nanotubes and 1-3 parts by weight of silicon carbide whiskers are mixed and added to 8-12 parts by weight of the silane-ethanol solution and stirred evenly to obtain a shaking liquid. S02, preheat graphene at 55-65℃ for 1-1.5h to obtain preheated graphene, and then ultrasonically vibrate the preheated graphene in an oscillating liquid with a weight of 4-7 times the total weight of the preheated graphene at 350-400W for 1-2h to obtain an oscillating graphene liquid. SO3, Preparation of the modifier: S04. Add 25-30% of the total amount of modifier to the vibrating graphene liquid and perform ball milling treatment. The ball milling speed is 1000-1500 r / min and the ball milling time is 1-2 h. After the ball milling is completed, filter and dry to obtain the modified graphene agent.

5. The corona-resistant varnish material for copper flat wire according to claim 4, characterized in that, The carbon nanotubes are multi-walled carbon nanotubes with an outer diameter of 10-30 nm and a length of 5-20 μm. The silicon carbide whiskers have a diameter of 0.2-1.0 μm and an aspect ratio of (20-50):

1. The graphene sheet has a diameter of 50-100 nm, a thickness of 0.8-3 nm, and 1-5 layers.

6. The corona-resistant varnish material for copper flat wire according to claim 4, characterized in that, The method for preparing the modifier is as follows: Boron carbide, a dopamine hydrochloride solution with a mass concentration of 1.5-3 g / L, and nanocellulose are mixed thoroughly at a weight ratio of (3-5):7:(1-2) to obtain a modified boron carbide solution; then 4-7 parts by weight of barium sulfate, 3-5 parts by weight of titanium dioxide, and 5-8 parts by weight of the modified boron carbide solution are stirred evenly, filtered, and dried to obtain the modifier.

7. The corona-resistant varnish material for copper flat wire according to claim 6, characterized in that, The solvent for the dopamine hydrochloride solution is a TrisHCl buffer solution with a pH of 8.5-10.

8. The corona-resistant varnish material for copper flat wire according to claim 1, characterized in that, The preparation method of the silicon nitride-based modifier is as follows: S11, 5-8 parts by weight of silicon nitride, 2-3 parts by weight of sericite powder, 5-8 parts by weight of sodium dodecylbenzenesulfonate solution and 1-2 parts by weight of hydroxyapatite are mixed evenly to obtain a silicon nitride-based additive solution. S12, 2-4 parts by weight of lanthanum oxide, 1-3 parts by weight of albite powder, 2-5 parts by weight of zirconium oxide and 5-8 parts by weight of chitosan solution with a mass fraction of 2-5% are thoroughly mixed, then filtered and dried to obtain the modifier. S13, the silicon nitride-based additive liquid and the modifier are mixed and ball-milled at a weight ratio of (7-11):5, the ball milling speed is 1000-1500 r / min, the ball milling is 2h, after the ball milling is completed, the mixture is filtered and dried to obtain the modifier based on silicon nitride.

9. The corona-resistant varnish material for copper flat wire according to claim 8, characterized in that, The sericite powder has a flake diameter of 5–25 μm, a flake thickness of 0.1–1 μm, and a diameter-to-thickness ratio of (40–60):1; the sodium dodecylbenzenesulfonate solution has a mass fraction of 6–10%.

10. A method for preparing a corona-resistant varnish material for copper flat wire as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Weigh the raw materials according to the weight proportions, and add the polyesterimide resin, aramid resin, modified graphene agent, silicon nitride-based modifier, functional additive, solvent and curing agent into the mixer in sequence and stir and mix them. The stirring speed is 550-750 r / min, and the stirring is carried out for 2-3 hours. After stirring is completed, the corona-resistant paint material is obtained.

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