Thermally conductive insulating enameled copper flat wire and preparation method thereof

Abstract

The application belongs to the technical field of new materials for enameled wire, and discloses a heat-conducting insulating enameled copper flat wire and a preparation method thereof. The preparation method comprises the following steps: 1) preparing graphene-aluminum oxide composite particles; 2) uniformly mixing the graphene-aluminum oxide composite particles and a polyimide resin solution to obtain a mixed paint; and 3) vacuum deaerating the mixed paint, then coating the mixed paint on the surface of the copper flat wire, and performing heat curing treatment, thereby obtaining the heat-conducting insulating enameled copper flat wire. The heat-conducting insulating enameled copper flat wire prepared by the application has good heat-conducting performance, thereby prolonging the service life of the enameled wire.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of enameled wire material, in particular to a heat-conducting insulated enameled copper flat wire and a preparation method thereof. BACKGROUND

[0002] Enameled wire is a main raw material of products such as motors, electrical appliances and household appliances. In recent years, the power industry has seen a sustained and rapid growth, and the rapid development of household appliances has brought a wider field of application to enameled wire, which in turn has put forward higher requirements for enameled wire. Enameled wire is a main variety of winding wire, which is composed of a conductor and an insulating layer. After the bare wire is annealed and softened, it is coated and baked for multiple times to form the enameled wire. However, it is not easy to produce a product that meets the standard requirements and customer requirements. The quality characteristics of various enameled wires are different due to the influence of factors such as raw material quality, process parameters, production equipment and environment. Therefore, various enameled wires have four major properties: mechanical properties, chemical properties, electrical properties and thermal properties.

[0003] There are various types of enameled wire. One of the earliest varieties developed in the world is acetal enameled wire. Although the temperature resistance level of this enameled wire is low, it is widely used in oil-immersed transformers due to its excellent high-temperature hydrolysis resistance. Subsequently, polyester enameled wire and polyurethane enameled wire were successfully developed in Germany. Polyurethane enameled wire was developed by Bayer in Germany in 1937. Due to its straight solderability, high-frequency resistance and dyeability, it is widely used in the fields of electronics and electrical appliances. Subsequently, the requirements for the properties of enameled wire are getting higher and higher. The polyester imine enameled wire improves the heat resistance by modifying the imine of polyester, further expanding the application range of enameled wire. Subsequently, polyimide enameled wire, polyamide enameled wire and composite coating enameled wire prepared by various materials have undergone different improvements, improving the performance of enameled wire in all aspects.

[0004] Chinese Patent Publication No. CN104130700 discloses a flexible polyimide insulating paint and a preparation method thereof, which comprises polyester imine, cresol type phenolic resin, p-t-butyl phenol type phenolic resin, silicone oil, amino resin, aromatic polyamide, butyl orthotitanate and solvent. The enameled wire prepared by the present application has good paint film flexibility. After the enameled wire is stretched by 25%, the paint film does not crack after being wound by 1 times the conductor diameter. However, the polyimide material enameled wire has poor heat conduction performance, which shortens the service life of the polyimide enameled wire. SUMMARY

[0005] The present application aims to solve the above technical problems and provides a heat-conducting insulated enameled copper flat wire and a preparation method thereof. The heat-conducting insulated enameled copper flat wire prepared by the present application has good heat conduction performance, thereby prolonging the service life of the enameled wire.

[0006] The technical scheme of the present application is implemented as follows:

[0007] A preparation method of a heat-conducting insulating enameled copper flat wire includes the following steps:

[0008] 1) Preparing graphene-aluminum oxide composite particles;

[0009] 2) Mixing the graphene-aluminum oxide composite particles and a polyimide resin solution uniformly to obtain a mixed paint;

[0010] 3) Vacuum deaerating the mixed paint, then coating the mixed paint on the surface of the copper flat wire, and performing heat curing treatment.

[0011] Preferably, in the step 3), the thickness of the mixed paint coated on the surface of the copper flat wire is controlled to be 20-40 um.

[0012] Preferably, in the step 3), the heat curing treatment temperature is 160-180 ℃, and the heat curing treatment time is 4-8 h.

[0013] Preferably, in the step 1), the preparation method of the graphene-aluminum oxide composite particles includes the following steps:

[0014] 11) Adding aluminum chloride trihydrate into deionized water to stir and dissolve, to obtain an aluminum chloride aqueous solution;

[0015] 12) Adding graphene oxide into the aluminum chloride aqueous solution to stir uniformly, adding ammonia water dropwise under stirring until the pH of the solution is 9-10, standing and aging, and then filtering, washing and drying to obtain a graphene-aluminum oxide precursor;

[0016] 13) Placing the graphene-aluminum oxide precursor in a muffle furnace to perform calcination, to obtain a graphene-aluminum oxide intermediate;

[0017] 14) Adding the graphene-aluminum oxide intermediate into an epoxy silane coupling agent hydrolysate, and performing heating and stirring reaction, to obtain a coupling agent modified graphene-aluminum oxide;

[0018] 15) Adding the coupling agent modified graphene-aluminum oxide into a polyethylene glycol aqueous solution, adding a potassium hydroxide catalyst, and performing heating and stirring reaction, and then filtering, washing and drying to obtain the graphene-aluminum oxide composite particles.

[0019] Polyimide is usually used as the resin matrix component of the enameled wire paint in the prior art, but the thermal conductivity of polyimide material is poor, and the thermal conductivity is usually below 0.2 W / (m·K), in order to improve the thermal conductivity of the polyimide enameled wire paint, graphene oxide is doped in the polyimide resin, and the thermal conductivity of the polyimide material is improved by using the thermal conductivity of the graphene oxide. However, a further problem encountered is that graphene oxide is a conductive material, and the doping of graphene oxide into the polyimide resin will reduce the insulation performance of the enameled wire paint. The team of the present application solves the above problems from two aspects: on the one hand, the graphene oxide is compounded with aluminum oxide to prepare a composite material, the aluminum oxide is an electrical insulator, and the mixing of the aluminum oxide with the graphene oxide can reduce the electrical conductivity of the graphene oxide, and the aluminum oxide has a certain thermal conductivity and does not affect the thermal conductivity of the material. On the other hand, the graphene-aluminum oxide composite material is grafted with polyethylene glycol polymer on the surface by using an epoxy silane coupling agent, the polyethylene glycol is a non-ionic water-soluble polymer and has good insulation, when the polyethylene glycol is grafted onto the surface of the graphene oxide, an insulating layer is formed on the surface of the graphene oxide, the insulating layer can block the transmission of electrons, thereby reducing the electrical conductivity of the graphene oxide, in addition, after the polyethylene glycol is grafted onto the graphene oxide, the electron transmission path between the graphene oxide layers is interfered, since the polyethylene glycol molecules are insulating, they can act as obstacles to electron transmission, increase the distance between electron hopping, and thus reduce the overall electrical conductivity and improve the insulation of the enameled wire paint.

[0020] Preferably, the mass ratio of aluminum chloride hexahydrate to graphene oxide in step 12) is 1:2-6.

[0021] Preferably, the calcination temperature in step 13) is 400-500℃.

[0022] Preferably, the heating reaction temperature in step 15) is 100℃, and the reaction time is 2h.

[0023] The mass ratio of the coupling agent modified graphene-aluminum oxide to polyethylene glycol is 1:0.2-0.7.

[0024] In the technical scheme of the present application, in order to reduce the conductive property of graphene oxide and improve the insulation property of graphene oxide, a sufficient amount of polyethylene glycol polymer must be grafted on the surface of the graphene-aluminum oxide composite material, and it is determined through experiments that the mass ratio of the coupling agent modified graphene-aluminum oxide to polyethylene glycol is less than 1:0.2. However, it is accidentally found in the experiments that when the amount of polyethylene glycol polymer is increased, that is, when the mass ratio of the coupling agent modified graphene-aluminum oxide to polyethylene glycol is less than 1:0.7, the thermal conductivity of the graphene oxide-aluminum oxide composite material is greatly reduced, which may be because polyethylene glycol is an amorphous polymer and has low thermal conductivity, and when an excessive amount of polyethylene glycol is grafted on the surface of the graphene oxide-aluminum oxide composite material, an insulating layer is formed on the surface of the graphene oxide-aluminum oxide composite material, and the polyethylene glycol molecules in the layer can act as a phonon scattering center to increase the boundary scattering of phonons, thereby reducing the thermal conductivity of the graphene oxide-aluminum oxide composite material. Therefore, in order to make the enameled copper flat wire have good thermal conductivity and insulation property, the mass ratio of the coupling agent modified graphene-aluminum oxide to polyethylene glycol is strictly controlled to be in the range of 1:0.2-0.7.

[0025] A thermal conductive and insulating enameled copper flat wire is prepared by the above method.

[0026] The present application has the following beneficial effects:

[0027] 1) The thermal conductivity of the polyimide material is improved by adding graphene oxide in the enameled wire paint, and the service life of the enameled wire is prolonged;

[0028] 2) The graphene oxide is mixed with aluminum oxide to prepare a composite material, the aluminum oxide is an electrical insulator, and the mixing of the aluminum oxide with the graphene oxide can reduce the electrical conductivity of the graphene oxide, and the aluminum oxide has certain thermal conductivity and does not affect the thermal conductivity of the material;

[0029] 3) The polyethylene glycol polymer is grafted on the surface of the graphene-aluminum oxide composite material by the epoxy silane coupling agent, the polyethylene glycol is a non-ionic water-soluble polymer and has good insulation property, and when the polyethylene glycol is grafted on the surface of the graphene oxide, an insulating layer is formed on the surface of the graphene oxide, the insulating layer can block the transmission of electrons, thereby reducing the electrical conductivity of the graphene oxide, and in addition, after the polyethylene glycol is grafted on the graphene oxide, the electronic transmission path between the graphene oxide layers is interfered, the polyethylene glycol molecules are insulating and can act as obstacles for the transmission of electrons, increase the distance between the electron jumps, and thus reduce the overall electrical conductivity and improve the insulation property of the enameled wire paint. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0031] Embodiment 1

[0032] A preparation method of a heat-conducting insulating enameled copper flat wire, comprising the following steps:

[0033] 1) preparing graphene-aluminum oxide composite particles;

[0034] 2) mixing cresol and anhydrous ethanol according to a volume ratio of 2:1 to obtain a solvent, adding polyimide resin with a solid content of 30% into the solvent according to a mass ratio of 1:50, stirring and dissolving to obtain a polyimide resin solution, adding the graphene-aluminum oxide composite particles into the polyimide resin solution according to a mass-volume ratio of 1g / 100mL, and mixing uniformly to obtain a mixed paint;

[0035] 3) vacuum deaerating the mixed paint, then coating the mixed paint on the surface of the copper flat wire, controlling the thickness of the mixed paint coated on the surface of the copper flat wire at 30um, and performing heat curing treatment at a heat curing treatment temperature of 175℃ for 7h, and the heat-conducting insulating enameled copper flat wire is obtained.

[0036] The preparation method of the graphene-aluminum oxide composite particles comprises the following steps: 11) adding 3g of aluminum chloride hexahydrate into 200mL of deionized water and stirring and dissolving to obtain an aluminum chloride aqueous solution; 12) adding graphene oxide into the aluminum chloride aqueous solution, stirring uniformly, and adding ammonia water dropwise under stirring until the pH of the solution is 9.5, standing for 24h, and then filtering, washing and drying to obtain a graphene-aluminum oxide precursor;

[0037] 13) placing the graphene-aluminum oxide precursor in a muffle furnace and calcining at 450℃ for 3h to obtain a graphene-aluminum oxide intermediate;

[0038] 14) mixing 90mL of ethanol and 10mL of water, then adding 2g of epoxy silane coupling agent KH-560, stirring and hydrolyzing to obtain an epoxy silane coupling agent hydrolysate, adding 5g of the graphene-aluminum oxide intermediate into the epoxy silane coupling agent hydrolysate, heating to 60℃, stirring and reacting for 3h, and then filtering, washing and drying to obtain a coupling agent modified graphene-aluminum oxide;

[0039] 15) 5 g of the coupling agent modified graphene-alumina is added into a 2.0 wt.% polyethylene glycol (molecular weight 8000) aqueous solution, the mass ratio of the coupling agent modified graphene-alumina to the polyethylene glycol is 1:0.6, 0.2 g of potassium hydroxide catalyst is added, and the reaction is carried out by heating and stirring, the reaction temperature is 100℃, and the reaction time is 2 h. After filtration, washing and drying, the graphene-alumina composite particles are obtained.

[0040] Example 2

[0041] A preparation method of a heat-conducting and insulating enameled copper flat wire, comprising the following steps:

[0042] 1) preparing graphene-alumina composite particles;

[0043] 2) mixing cresol and anhydrous ethanol according to a volume ratio of 2:1 to obtain a solvent, adding 30% solid content polyimide resin according to a mass ratio of 1:50 into the solvent, stirring and dissolving to obtain a polyimide resin solution, adding graphene-alumina composite particles according to a mass-volume ratio of 1 g / 100 mL into the polyimide resin solution, and mixing uniformly to obtain a mixed paint;

[0044] 3) vacuum deaerating the mixed paint, then coating the mixed paint on the surface of the copper flat wire, controlling the thickness of the mixed paint coated on the surface of the copper flat wire to be 30 um, and performing heat curing treatment, wherein the heat curing treatment temperature is 170℃, and the heat curing treatment time is 5 h.

[0045] The preparation method of the graphene-alumina composite particles comprises the following steps: 11) adding 3 g of aluminum chloride hexahydrate into 200 mL of deionized water and stirring to dissolve, to obtain an aluminum chloride aqueous solution; 12) adding graphene oxide into the aluminum chloride aqueous solution, the mass ratio of the aluminum chloride hexahydrate to the graphene oxide being 1:3, stirring uniformly, adding ammonia water dropwise under stirring conditions until the pH of the solution is 9.5, standing for 24 h, and then performing filtration, washing and drying to obtain a graphene-alumina precursor;

[0046] 13) placing the graphene-alumina precursor in a muffle furnace and calcining at 450℃ for 3 h to obtain a graphene-alumina intermediate;

[0047] 14) mixing 90 mL of ethanol with 10 mL of water, then adding 2 g of epoxy silane coupling agent KH-560, stirring to hydrolyze, to obtain an epoxy silane coupling agent hydrolysate, adding 5 g of the graphene-alumina intermediate into the epoxy silane coupling agent hydrolysate, heating to 60℃, stirring to react for 3 h, and then performing filtration, washing and drying to obtain coupling agent modified graphene-alumina;

[0048] 15) 5 g of the coupling agent modified graphene-alumina is added into a 2.0 wt.% polyethylene glycol (molecular weight 8000) aqueous solution, the mass ratio of the coupling agent modified graphene-alumina to the polyethylene glycol is 1:0.3, 0.2 g of potassium hydroxide catalyst is added, and the reaction is carried out by heating and stirring, the reaction temperature is 100℃, and the reaction time is 2 h. After filtration, washing and drying, the graphene-alumina composite particles are obtained.

[0049] Example 3

[0050] A preparation method of a heat-conducting and insulating enameled copper flat wire, comprising the following steps:

[0051] 1) preparing graphene-alumina composite particles;

[0052] 2) mixing cresol and anhydrous ethanol according to a volume ratio of 2:1 to obtain a solvent, adding 30% solid content polyimide resin according to a mass ratio of 1:50 into the solvent, stirring and dissolving to obtain a polyimide resin solution, adding graphene-alumina composite particles according to a mass-volume ratio of 1 g / 100 mL into the polyimide resin solution, and mixing uniformly to obtain a mixed paint;

[0053] 3) vacuum degassing the mixed paint, then coating the mixed paint on the surface of the copper flat wire, controlling the thickness of the mixed paint coated on the surface of the copper flat wire to be 30 um, and performing heat curing treatment, the heat curing treatment temperature is 170℃, and the heat curing treatment time is 6 h.

[0054] The preparation method of the graphene-alumina composite particles comprises the following steps: 11) adding 3 g of aluminum chloride hexahydrate into 200 mL of deionized water and stirring to dissolve, to obtain an aluminum chloride aqueous solution; 12) adding graphene oxide into the aluminum chloride aqueous solution, the mass ratio of aluminum chloride hexahydrate to graphene oxide is 1:4, stirring uniformly, adding ammonia water dropwise under stirring conditions until the pH of the solution is 9.5, standing for 24 h, and then performing filtration, washing and drying to obtain a graphene-alumina precursor;

[0055] 13) placing the graphene-alumina precursor in a muffle furnace and calcining at 450℃ for 3 h to obtain a graphene-alumina intermediate;

[0056] 14) mixing 90 mL of ethanol with 10 mL of water, then adding 2 g of epoxy silane coupling agent KH-560, stirring to hydrolyze, to obtain an epoxy silane coupling agent hydrolysate, adding 5 g of the graphene-alumina intermediate into the epoxy silane coupling agent hydrolysate, heating to 60℃, stirring for 3 h, and then performing filtration, washing and drying to obtain coupling agent modified graphene-alumina;

[0057] 15) 5 g of the coupling agent modified graphene-alumina is added into a 2.0 wt.% polyethylene glycol (molecular weight 8000) aqueous solution, the mass ratio of the coupling agent modified graphene-alumina to the polyethylene glycol is 1:0.5, 0.2 g of potassium hydroxide catalyst is added, and the reaction is carried out by heating and stirring, the reaction temperature is 100℃, and the reaction time is 2 h. After filtration, washing and drying, the graphene-alumina composite particles are obtained.

[0058] Example 4

[0059] A preparation method of a heat-conducting and insulating enameled copper flat wire, comprising the following steps:

[0060] 1) preparing graphene-alumina composite particles;

[0061] 2) mixing cresol and anhydrous ethanol according to a volume ratio of 2:1 to obtain a solvent, adding 30% solid content polyimide resin according to a mass ratio of 1:50 into the solvent, stirring and dissolving to obtain a polyimide resin solution, and adding the graphene-alumina composite particles according to a mass-volume ratio of 1 g / 100 mL into the polyimide resin solution, and uniformly mixing to obtain a mixed paint;

[0062] 3) vacuum deaerating the mixed paint, then coating the mixed paint on the surface of the copper flat wire, controlling the thickness of the mixed paint coated on the surface of the copper flat wire to be 40 um, and performing heat curing treatment, wherein the heat curing treatment temperature is 180℃, and the heat curing treatment time is 8 h.

[0063] The preparation method of the graphene-alumina composite particles comprises the following steps: 11) adding 3 g of aluminum chloride hexahydrate into 200 mL of deionized water and stirring to dissolve, to obtain an aluminum chloride aqueous solution; 12) adding graphene oxide into the aluminum chloride aqueous solution, the mass ratio of the aluminum chloride hexahydrate to the graphene oxide is 1:6, stirring uniformly, adding ammonia water dropwise under stirring conditions until the pH of the solution is 10, standing for 24 h, and then performing filtration, washing and drying to obtain a graphene-alumina precursor;

[0064] 13) placing the graphene-alumina precursor in a muffle furnace and calcining at 500℃ for 3 h to obtain a graphene-alumina intermediate;

[0065] 14) mixing 90 mL of ethanol with 10 mL of water, then adding 2 g of epoxy silane coupling agent KH-560, stirring to hydrolyze, to obtain an epoxy silane coupling agent hydrolysate, adding 5 g of the graphene-alumina intermediate into the epoxy silane coupling agent hydrolysate, heating to 60℃, stirring to react for 3 h, and then performing filtration, washing and drying to obtain the coupling agent modified graphene-alumina;

[0066] 15) 5 g of the coupling agent modified graphene-alumina is added into a 2.0 wt.% polyethylene glycol (molecular weight 8000) aqueous solution, the mass ratio of the coupling agent modified graphene-alumina to the polyethylene glycol is 1:0.7, 0.2 g of potassium hydroxide catalyst is added, and the reaction is carried out by heating and stirring, the reaction temperature is 100℃, and the reaction time is 2 h; after filtration, washing and drying, the graphene-alumina composite particles are obtained.

[0067] Example 5

[0068] A preparation method of a heat-conducting and insulating enameled copper flat wire, comprising the following steps:

[0069] 1) preparing graphene-alumina composite particles;

[0070] 2) mixing cresol and anhydrous ethanol according to a volume ratio of 2:1 to obtain a solvent, adding 30% solid content polyimide resin according to a mass ratio of 1:50 into the solvent, stirring and dissolving to obtain a polyimide resin solution, and adding the graphene-alumina composite particles according to a mass-volume ratio of 1 g / 100 mL into the polyimide resin solution, and uniformly mixing to obtain a mixed paint;

[0071] 3) vacuum deaerating the mixed paint, then coating the mixed paint on the surface of the copper flat wire, controlling the thickness of the mixed paint coated on the surface of the copper flat wire to be 20 um, and performing heat curing treatment, wherein the heat curing treatment temperature is 160℃, and the heat curing treatment time is 4 h.

[0072] The preparation method of the graphene-alumina composite particles comprises the following steps: 11) adding 3 g of aluminum chloride hexahydrate into 200 mL of deionized water and stirring to dissolve, to obtain an aluminum chloride aqueous solution; 12) adding graphene oxide into the aluminum chloride aqueous solution, the mass ratio of the aluminum chloride hexahydrate to the graphene oxide is 1:2, uniformly stirring, and adding ammonia water dropwise under stirring until the pH of the solution is 9, standing for 24 h, and then performing filtration, washing and drying to obtain a graphene-alumina precursor;

[0073] 13) placing the graphene-alumina precursor in a muffle furnace and calcining at 400℃ for 3 h to obtain a graphene-alumina intermediate;

[0074] 14) mixing 90 mL of ethanol with 10 mL of water, then adding 2 g of epoxy silane coupling agent KH-560, stirring to hydrolyze, to obtain an epoxy silane coupling agent hydrolysate, adding 5 g of the graphene-alumina intermediate into the epoxy silane coupling agent hydrolysate, heating to 60℃, and stirring to react for 3 h; after filtration, washing and drying, the coupling agent modified graphene-alumina is obtained.

[0075] 15) 5 g of the coupling agent modified graphene-alumina was added into a 2.0 wt.% polyethylene glycol (molecular weight 8000) aqueous solution, the mass ratio of the coupling agent modified graphene-alumina to the polyethylene glycol was 1:0.2, 0.2 g of potassium hydroxide catalyst was added, and the reaction was carried out by heating and stirring, the reaction temperature was 100°C, and the reaction time was 2 h. After filtration, washing and drying, graphene-alumina composite particles were obtained.

[0076] Comparative Example 1

[0077] The difference between Comparative Example 1 and Example 1 is that:

[0078] In the preparation process of the heat-conducting and insulating enameled copper flat wire, no graphene-alumina composite particles were added in the polyimide resin, and the remaining operation steps were the same as those in Example 1.

[0079] Comparative Example 2

[0080] The difference between Comparative Example 2 and Example 1 is that:

[0081] In the preparation process of the heat-conducting and insulating enameled copper flat wire,

[0082] The graphene-alumina composite particles were replaced by graphene oxide, and the remaining operation steps were the same as those in Example 1.

[0083] Comparative Example 3

[0084] The difference between Comparative Example 3 and Example 1 is that:

[0085] In the preparation process of the graphene-alumina composite particles, steps 14) and 15) were omitted,

[0086] and the remaining operation steps were the same as those in Example 1.

[0087] Comparative Example 4

[0088] The difference between Comparative Example 4 and Example 1 is that:

[0089] In the preparation process of the graphene-alumina composite particles, steps 11), 12) and 13) were omitted,

[0090] The graphene-alumina intermediate was replaced by graphene oxide; and the remaining operation steps were the same as those in Example 1.

[0091] Comparative Example 5

[0092] The difference between Comparative Example 5 and Example 5 is that:

[0093] The mass ratio of the coupling agent modified graphene-alumina to the polyethylene glycol was 1:0.1, and the remaining operation steps were the same as those in Example 5.

[0094] Comparative Example 6

[0095] The difference between Comparative Example 6 and Example 4 is that:

[0096] The mass ratio of the coupling agent modified graphene-alumina to polyethylene glycol is 1:0.8, and the remaining operation steps are the same as those of Example 4.

[0097] Comparative Example 7

[0098] The difference between Comparative Example 6 and Example 4 is that:

[0099] The mass ratio of the coupling agent modified graphene-alumina to polyethylene glycol is 1:0.9, and the remaining operation steps are the same as those of Example 4.

[0100] Comparative Example 8

[0101] The difference between Comparative Example 8 and Example 4 is that:

[0102] The mass ratio of the coupling agent modified graphene-alumina to polyethylene glycol is 1:1, and the remaining operation steps are the same as those of Example 4.

[0103] Performance test

[0104] 1. Thermal conductivity test:

[0105] The mixed paint obtained in the examples and comparative examples is coated on a steel plate with a thickness of 50 um, and then subjected to heat curing treatment, the heat curing treatment temperature is 160°C, the heat curing treatment time is 4h, and the paint film is taken out. The thermal diffusivity coefficient of the polyimide film is measured by a thermal diffusivity coefficient measuring instrument (model LFA447, Germany Netzsch) by laser flash method, and the thermal conductivity coefficient is calculated by multiplying the thermal diffusivity coefficient measurement value by the density and specific heat.

[0106] 2. Insulation performance test:

[0107] The surface resistance of the paint film is measured by using a YH-8200 digital insulation resistance tester, the test voltage is 100V, and the higher the surface resistance of the paint film, the better the insulation performance of the paint film.

[0108]

[0109] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing thermally conductive and insulating enameled copper flat wire, characterized in that, Includes the following steps: 1) Preparation of graphene-alumina composite particles; 11) Add aluminum trichloride hexahydrate to deionized water and stir to dissolve, to obtain an aqueous solution of aluminum trichloride; 12) Add graphene oxide to an aqueous solution of aluminum trichloride hexahydrate, stir until homogeneous, add ammonia dropwise under stirring until the pH of the solution reaches 9-10, let stand and age, and then filter, wash and dry to obtain the graphene-alumina precursor. 13) The graphene-alumina precursor was calcined in a muffle furnace to obtain the graphene-alumina intermediate; 14) The graphene-alumina intermediate was added to the hydrolysate of the epoxy silane coupling agent, and the mixture was heated and stirred to react, thus obtaining the coupling agent modified graphene-alumina. 15) Add the coupling agent-modified graphene-alumina to a polyethylene glycol aqueous solution, wherein the mass ratio of the coupling agent-modified graphene-alumina to polyethylene glycol is 1:0.2-0.

7. Add potassium hydroxide catalyst, heat to 100°C and stir for 2 hours. After filtration, separation, washing and drying, graphene-alumina composite particles are obtained. 2) Mix the graphene-alumina composite particles and the polyimide resin solution evenly to obtain a mixed paint; 3) Vacuum degas the mixed paint, then coat the mixed paint onto the surface of the copper flat wire, and perform heat curing treatment to obtain the final product.

2. The method for preparing a thermally conductive and insulating enameled copper flat wire according to claim 1, characterized in that, In step 3), the thickness of the mixed paint coating on the surface of the copper flat wire is controlled at 20-40 μm.

3. The method for preparing a thermally conductive and insulating enameled copper flat wire according to claim 1, characterized in that, In step 3), the heat curing temperature is 160-180℃ and the heat curing time is 4-8h.

4. The method for preparing a thermally conductive and insulating enameled copper flat wire according to claim 1, characterized in that, In step 12), the mass ratio of aluminum trichloride hexahydrate to graphene oxide is 1:2-6.

5. The method for preparing a thermally conductive and insulating enameled copper flat wire according to claim 1, characterized in that, In step 13), the calcination temperature is 400-500℃.

6. A thermally conductive and insulating enameled copper flat wire, characterized in that, Prepared by the method described in any one of claims 1-5.

Images