Water-based insulating paint as well as preparation method and application thereof

Abstract

The invention discloses water-based insulating paint as well as a preparation method and application thereof. The water-based insulating paint is prepared from the following raw materials: hyperbranched water-based epoxy resin, a curing agent and a heat-conducting filler, the hyperbranched water-borne epoxy resin comprises the following raw materials: polycarbonate polyol, diphenyl diamino or a derivative thereof, isophorone diamine or a derivative thereof, bisphenol A epoxy resin with the molecular weight of 800 or above, and hyperbranched epoxy resin; in the preparation process of the hyperbranched water-borne epoxy resin, polycarbonate polyol, diphenyl diamino or a derivative thereof and isophorone diamine or a derivative thereof are mixed for reaction, then bisphenol A epoxy resin is added for reaction, and hyperbranched epoxy resin is added for reaction after reaction; the water-based insulating paint is prepared by uniformly mixing the raw materials. According to the invention, high thermal conductivity can be taken into consideration, the thermal conductive filler is not easy to settle, permeability and paint hanging amount can be well considered, the problem that in the prior art, the permeability and the paint hanging amount are both considered is solved, and the composite material can be used for preparing electrical equipment such as motors and transformers.

Description

Technical Field

[0001] This invention relates to the field of electronics and electrical engineering, specifically to a water-based insulating varnish, its preparation method, and its application. Background Technology

[0002] Insulating varnish, a key insulating material in electrical equipment, is widely used for the insulation protection of electrical components such as motors, transformers, and coils. Its performance directly affects the safety, stability, and service life of electrical equipment. Traditional insulating varnishes are mostly solvent-based systems, using organic solvents as diluents and dispersion media. During construction and use, they release large amounts of volatile organic compounds (VOCs). These VOCs not only cause serious air pollution and harm the health of operators, but also pose significant fire safety hazards due to the flammable properties of organic solvents.

[0003] With increasingly stringent global environmental regulations and ever-improving safety requirements, the VOC emissions and flammability of solvent-based insulating varnishes have become core issues restricting their application, making the development of environmentally friendly and safe alternatives imperative. Currently, the mainstream development trend for environmentally friendly insulating varnishes is to replace organic solvents with water, forming a water-based insulating varnish system. Its core advantage lies in the virtually zero VOC emissions during construction and use, and the non-flammable nature of water fundamentally eliminates fire hazards, meeting the dual requirements of environmental protection and safety.

[0004] Currently available water-based insulating varnishes mainly include water-based epoxy systems, water-based acrylic systems, and water-based polyester systems. These systems have all achieved breakthroughs in environmental performance, effectively solving the pollution and safety problems of traditional solvent-based insulating varnishes, and have been initially applied in some electrical equipment. However, existing water-based insulating varnishes still have many shortcomings in key performance aspects, making it difficult to meet the comprehensive performance requirements of electrical equipment for insulating varnishes. Specific defects are as follows: Insufficient thermal conductivity: Electrical equipment generates a large amount of heat during operation. Insulating varnishes need to have a certain thermal conductivity to facilitate heat conduction and diffusion, preventing localized overheating that could lead to equipment failure. Existing conventional waterborne epoxy, waterborne acrylic, and waterborne polyester systems generally have low thermal conductivity and poor heat transfer efficiency, failing to meet the heat dissipation requirements of high-power, high-density electrical equipment and limiting their application in critical equipment such as high-power motors and high-frequency transformers.

[0005] Thermally conductive fillers are prone to sedimentation: To improve thermal conductivity, existing technologies typically add thermally conductive fillers to water-based insulating varnishes. However, due to the limitations of dispersion stability in water-based systems, when the amount of thermally conductive filler added reaches a certain proportion to meet thermal conductivity requirements, the filler is prone to agglomeration and sedimentation during storage. This not only affects the application performance of the insulating varnish but also leads to localized differences in the thermal conductivity and insulation performance of the cured insulation layer, reducing the operational stability of electrical equipment.

[0006] Achieving a balance between good penetration and adequate coating thickness is challenging: insulating varnishes need to possess both excellent penetration and a suitable coating thickness. Insufficient penetration prevents the varnish from fully wetting the fine structures of electrical components, such as coil gaps and substrate pores, creating insulation dead zones. Insufficient coating thickness, on the other hand, fails to form a uniform and dense insulation layer, affecting the insulation protection effect. Currently, there is a significant contradiction between penetration and coating thickness in the formulation design of water-based insulating varnishes. Optimizing the formulation to improve penetration will decrease the coating thickness, and vice versa, making it difficult to achieve a balance between the two.

[0007] The aforementioned defects result in insufficient overall performance of existing water-based environmentally friendly insulating varnishes, limiting their large-scale application in the field of electrical equipment. Therefore, developing an environmentally friendly insulating varnish that combines environmental friendliness, high thermal conductivity, good permeability, and a balanced coating amount, while ensuring stable dispersion of thermally conductive fillers, has become an urgent technical problem to be solved in this field.

[0008] It should be noted that the information disclosed in the background section above is only used for understanding the background of this application. Therefore, the background section of this invention may include background information about the problems or environment of this invention, and is not necessarily a description of prior art. Thus, the content included in the background section does not constitute an admission of prior art by the applicant. Summary of the Invention

[0009] The purpose of this invention is to overcome one or more shortcomings in the prior art and provide an improved water-based insulating varnish.

[0010] This invention also provides a method for preparing the above-mentioned water-based insulating varnish and its application in the preparation of motors and transformers.

[0011] To achieve the above objectives, the present invention employs the following technical solution: A water-based insulating varnish, wherein the raw materials of the water-based insulating varnish include hyperbranched water-based epoxy resin, curing agent, and thermally conductive filler; The raw materials for the hyperbranched waterborne epoxy resin include: Component (a), polycarbonate polyol; Component (b), the compound shown in formula (I); In equation (Ⅰ), R1 is selected from C 1-3 Alkylene, R2, R3 are independently selected from C 1-3 Alkylene, one bond, R4 and R5 independently selected from H and C. 1-6 Alkyl groups, m and n are independently selected from 0, 1, and 2; Component (c), the compound shown in formula (II); In equation (II), R6, R7, and R8 are independently selected from C.1-6 Alkyl group, R9 is selected from C 1-3 Alkylene; Component (d): Bisphenol A type epoxy resin with a molecular weight of 800 or higher; Component (e), hyperbranched epoxy resin with an epoxy value of 0.1-0.3 mol / 100g; In the process of preparing the hyperbranched waterborne epoxy resin, after components (a), (b) and (c) are mixed and reacted, component (d) is added and reacted, and then component (e) is added and reacted.

[0012] In some embodiments of the present invention, in formula (I), R1 is selected from methylene, ethylene, or propylene.

[0013] In some embodiments of the present invention, in formula (Ⅰ), R2 and R3 are both bonds.

[0014] In some embodiments of the present invention, in formula (I), R4 and R5 are independently selected from H, methyl, and ethyl.

[0015] In some embodiments of the present invention, in formula (II), R6, R7, and R8 are independently selected from methyl, ethyl, and propyl.

[0016] In some embodiments of the present invention, in formula (II), R9 is selected from methylene, ethylene, or propylene.

[0017] In some embodiments of the present invention, component (b) is selected from 4,4'-diaminodiphenylmethane.

[0018] In some embodiments of the present invention, component (c) is selected from isophorone diamine.

[0019] In some embodiments of the present invention, in component (d), the molecular weight of the bisphenol A type epoxy resin is 800-5000.

[0020] In some embodiments of the present invention, component (d) is selected from one or more combinations of epoxy resin E20, epoxy resin E12, epoxy resin E09, and epoxy resin E06.

[0021] In some embodiments of the present invention, the hyperbranched epoxy resin in component (e) has a molecular weight of 3000-4000.

[0022] According to some specific aspects of the present invention, the hyperbranched epoxy resin is hyperbranched epoxy resin E102, etc.

[0023] In some embodiments of the present invention, in component (a), the polycarbonate polyol has a molecular weight of 1000-4000.

[0024] In some embodiments of the present invention, in component (a), the polycarbonate polyol is prepared by the following method: a terminal hydroxyl hyperbranched polyester with 5 or more hydroxyl groups per molecule, 1,6-hexanediol, diethylene glycol and dimethyl carbonate are subjected to transesterification at 145-180°C. When the methanol distillation rate reaches 80%-90% of the theoretical value, the temperature is raised to 210-230°C, and a vacuum is drawn to 10-50 Pa. Polycondensation reaction is carried out under vacuum negative pressure to generate polycarbonate polyol.

[0025] Furthermore, the hydroxyl value of the polycarbonate polyol is controlled to be 70-90 mg KOH / g.

[0026] Further, the molar ratio of the terminal hydroxyl hyperbranched polyester, the 1,6-hexanediol, the diethylene glycol, and the dimethyl carbonate is 1:0.8-1.2:0.8-1.2:1.0-2.0, preferably 1:0.8-1.2:0.8-1.2:1.3-1.8.

[0027] Furthermore, the hydroxyl-terminated hyperbranched polyester has a hydroxyl value of 400-600 mg KOH / g.

[0028] Furthermore, the molecular weight of the terminal hydroxyl hyperbranched polyester is 1000-1500.

[0029] In some embodiments of the present invention, the hyperbranched waterborne epoxy resin is prepared by the following method: Components (a), (b), and (c) are reacted at a first preset temperature. After the reaction, component (d) is added, and the temperature is raised to a second preset temperature for further reaction. After the reaction, component (e) is added, and the reaction is continued at the second preset temperature until the amine value is less than 5 mg KOH / g.

[0030] Furthermore, the first preset temperature is 75-85℃.

[0031] Furthermore, the second preset temperature is 95-105℃.

[0032] Furthermore, the generated hyperbranched waterborne epoxy resin is dispersed in water to prepare a hyperbranched waterborne epoxy resin emulsion.

[0033] In some embodiments of the present invention, the thermally conductive filler includes boron nitride, spherical alumina, aluminum hydroxide, and carbon nanotubes.

[0034] Further, the mass ratio of boron nitride, spherical alumina, aluminum hydroxide, and carbon nanotubes is 1:2-4:8-10:0.5-2.0. Even further, the mass ratio of boron nitride, spherical alumina, aluminum hydroxide, and carbon nanotubes is 1:2.5-3.5:8.5-9.5:0.8-1.2.

[0035] Furthermore, the boron nitride has a particle size D50 of 1-5 μm.

[0036] Furthermore, the particle size D50 of the spherical alumina is 0.5-15 μm.

[0037] Furthermore, the particle size D50 of the aluminum hydroxide is 0.5-40 μm.

[0038] Furthermore, the carbon nanotubes have a diameter of 10-20 nm, a length of 10-30 μm, and an aspect ratio of 100-300.

[0039] The aforementioned combination of thermally conductive fillers can be better and more uniformly dispersed in the specific hyperbranched waterborne epoxy resin system of this invention. Even with a relatively large addition amount, sedimentation or even agglomeration and sedimentation are minimal, which is beneficial for improving storage stability and thermal conductivity. In particular, the combined fillers construct a multidimensional thermally conductive network within the system that significantly contributes to the thermal conductivity, resulting in high heat transfer efficiency.

[0040] In some embodiments of the present invention, the molar ratio of components (a), (b), (c), (d), and (e) is 1:1-2:1-2:1-2:1-2.

[0041] Furthermore, the molar ratio of components (a), (b), (c), (d), and (e) is 1:1.2-1.8:1.1-1.7:1.45-2.0:1.1-1.7.

[0042] Furthermore, the molar ratio of components (a), (b), (c), (d), and (e) is 1:1.2-1.6:1.3-1.7:1.4-1.85:1.3-1.7.

[0043] In some embodiments of the present invention, the raw materials of the water-based insulating varnish, by weight, comprise: Hyperbranched waterborne epoxy resin emulsion 30wt.%-45wt.%; Curing agent 5wt.%-10wt.%; Thermally conductive filler 25wt.%-40wt.%; Aqueous wetting agent 0.1wt.%-1wt.%; Water-based defoamer 0.1wt.%-1wt.%; Water 15wt.%-35wt.%; The hyperbranched waterborne epoxy resin emulsion is made by dispersing hyperbranched waterborne epoxy resin in water, and its solid content is 60wt.%-70wt.%.

[0044] In some embodiments of the present invention, the curing agent is an isocyanate or a derivative thereof, and further, the curing agent may be a blocked isocyanate BL3175.

[0045] In some embodiments of the present invention, the aqueous wetting agent includes polyurethane wetting agents, fluorocarbon wetting agents, etc.

[0046] In some embodiments of the present invention, the water-based defoamer includes silicone-based water-based defoamers, polyether-based water-based defoamers, etc.

[0047] Another technical solution provided by the present invention: a method for preparing the above-mentioned water-based insulating varnish, the preparation method comprising: A water-based insulating varnish is prepared by mixing hyperbranched waterborne epoxy resin, curing agent, thermally conductive filler, water, and selective additives.

[0048] Another technical solution provided by the present invention: the application of the above-mentioned water-based insulating varnish in the preparation of motors and transformers.

[0049] Another technical solution provided by the present invention: a hyperbranched waterborne epoxy resin, wherein the raw materials of the hyperbranched waterborne epoxy resin include: Component (a), polycarbonate polyol; Component (b), the compound shown in formula (I); In equation (Ⅰ), R1 is selected from C 1-3 Alkylene, R2, R3 are independently selected from C 1-3 Alkylene, one bond, R4 and R5 independently selected from H and C. 1-6 Alkyl groups, where m and n are independently 0, 1, and 2; Component (c), the compound shown in formula (II); In equation (II), R6, R7, and R8 are independently selected from C. 1-6 Alkyl group, R9 is selected from C 1-3 Alkylene; Component (d): Bisphenol A type epoxy resin with a molecular weight of 800 or higher; Component (e), hyperbranched epoxy resin with an epoxy value of 0.1-0.3 mol / 100g; In the process of preparing the hyperbranched waterborne epoxy resin, after components (a), (b) and (c) are mixed and reacted, component (d) is added and reacted, and then component (e) is added and reacted.

[0050] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: This invention innovatively provides a novel water-based insulating varnish. Through the formulation of its raw materials, this varnish allows for the addition of more thermally conductive fillers to improve thermal conductivity while minimizing filler sedimentation. Simultaneously, its permeability is maintained without significant deterioration. This allows the water-based insulating varnish to achieve thorough wetting of electrical equipment, preventing the formation of insulation dead zones. Furthermore, it ensures sufficient varnish application, forming a uniform and dense insulating layer of the desired thickness, resulting in excellent insulation protection. This solves the problem of compromises in existing technologies. Detailed Implementation

[0051] The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0052] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0053] The polycarbonate polyol used in the following examples was prepared by the following method: 1 mol of hydroxyl-terminated hyperbranched polyester H2O2 (HyPer H2O series, purchased from Wuhan Hyperbranched Resin Technology Co., Ltd.), 1 mol of 1,6-hexanediol, 1 mol of diethylene glycol, and 1.5 mol of dimethyl carbonate were subjected to transesterification reaction at 160℃ for 6 hours. When the methanol distillation reached the theoretical value of 85±1%, the temperature was raised to 220℃, and the vacuum was drawn to below 50 Pa. The polycondensation reaction was continued under vacuum negative pressure. The reaction was stopped when the hydroxyl value was less than 80 mg KOH / g, and the polycarbonate polyol with a molecular weight of approximately 2000 was prepared.

[0054] Blocked isocyanate BL3175 was purchased from Guangzhou Kosite New Materials Co., Ltd.; boron nitride, particle size D50: 5μm, was purchased from Henan Nitrogen-Boron New Materials Technology Co., Ltd.; spherical alumina, particle size D50: 10μm, was purchased from Shanghai Baitu High-Tech Materials Technology Co., Ltd.; aluminum hydroxide, particle size D50: 2μm, was purchased from Zhejiang Xusen Flame Retardant Co., Ltd.; carbon nanotubes, diameter: 20nm, length: 30μm, were purchased from Jiangsu Tiannai Technology Co., Ltd.; water-based wetting agent, specifically TEGO4100, was purchased from Shanghai Yitu Business Co., Ltd.; water-based defoamer, specifically BYK012, was purchased from Guangzhou Yinman New Materials Co., Ltd.; epoxy resin E20 was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd.; epoxy resin E51 was purchased from Shanghai Yuanbang Group Co., Ltd.; hyperbranched epoxy resin E102 was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd.; the epoxy value was 0.2mol / 100g.

[0055] Example 1: This example provides a water-based insulating varnish and its preparation method. The raw material formula of the water-based insulating varnish is shown in Table 1.

[0056] Table 1

[0057] The preparation method of hyperbranched waterborne epoxy resin emulsion includes: Polycarbonate polyol, 4,4'-diaminodiphenylmethane, and isophorone diamine were mixed and reacted at 80°C for 2 hours. Then, epoxy resin E20 was added, and the temperature was raised to 100°C and reacted for 2 hours. Finally, hyperbranched epoxy resin E102 was added and the reaction was continued at 100°C until the amine value was less than 5 mg KOH / g. The reaction was then terminated to obtain hyperbranched waterborne epoxy resin. The molar ratio of polycarbonate polyol, 4,4'-diaminodiphenylmethane, isophorone diamine, epoxy resin E20, and hyperbranched epoxy resin E102 was 1:1.4:1.5:1.66:1.5. The obtained hyperbranched waterborne epoxy resin was dispersed in deionized water to prepare a hyperbranched waterborne epoxy resin emulsion with a solid content of 70 wt.%.

[0058] The preparation method of this water-based insulating varnish includes: weighing each raw material according to the formula in Table 1, mixing them thoroughly, and preparing the water-based insulating varnish.

[0059] Example 2: This example provides a water-based insulating varnish and its preparation method. The raw material formula of the water-based insulating varnish is shown in Table 2.

[0060] Table 2

[0061] The preparation method of hyperbranched waterborne epoxy resin emulsion includes: Polycarbonate polyol, 4,4'-diaminodiphenylmethane, and isophorone diamine were mixed and reacted at 80°C for 2 hours. Then, epoxy resin E20 was added, and the temperature was raised to 100°C and reacted for 2 hours. Finally, hyperbranched epoxy resin E102 was added and the reaction was continued at 100°C until the amine value was less than 5 mg KOH / g. The reaction was then terminated to obtain hyperbranched waterborne epoxy resin. The molar ratio of polycarbonate polyol, 4,4'-diaminodiphenylmethane, isophorone diamine, epoxy resin E20, and hyperbranched epoxy resin E102 was 1:1.6:1.3:1.8:1.2. The obtained hyperbranched waterborne epoxy resin was dispersed in deionized water to prepare a hyperbranched waterborne epoxy resin emulsion with a solid content of 65 wt.%.

[0062] The preparation method of this water-based insulating varnish includes: weighing each raw material according to the formula in Table 2, mixing them thoroughly, and preparing the water-based insulating varnish.

[0063] Example 3: This example provides a water-based insulating varnish and its preparation method. The raw material formula of the water-based insulating varnish is shown in Table 3.

[0064] Table 3

[0065] The preparation method of hyperbranched waterborne epoxy resin emulsion includes: Polycarbonate polyol, 4,4'-diaminodiphenylmethane, and isophorone diamine were mixed and reacted at 80°C for 2 hours. Then, epoxy resin E20 was added, and the temperature was raised to 100°C and reacted for 2 hours. Finally, hyperbranched epoxy resin E102 was added and the reaction was continued at 100°C until the amine value was less than 5 mg KOH / g. The reaction was then terminated to obtain hyperbranched waterborne epoxy resin. The molar ratio of polycarbonate polyol, 4,4'-diaminodiphenylmethane, isophorone diamine, epoxy resin E20, and hyperbranched epoxy resin E102 was 1:1.8:1.1:2.0:1.1. The obtained hyperbranched waterborne epoxy resin was dispersed in deionized water to prepare a hyperbranched waterborne epoxy resin emulsion with a solid content of 60 wt.%.

[0066] The preparation method of this water-based insulating varnish includes: weighing each raw material according to the formula in Table 3, mixing them thoroughly, and preparing the water-based insulating varnish.

[0067] Comparative Example 1: This example provides a water-based insulating varnish and its preparation method, which is basically the same as in Example 1, except that in the preparation process of the hyperbranched water-based epoxy resin, epoxy resin E20 is replaced with an equal molar amount of epoxy resin E51, and isophorone diamine is replaced with an equal molar amount of 4,4'-diaminodiphenylmethane. That is, in this example, the molar ratio of polycarbonate polyol, 4,4'-diaminodiphenylmethane, epoxy resin E51, and hyperbranched epoxy resin E102 is 1:2.9:1.66:1.5.

[0068] Comparative Example 2: This example provides a water-based insulating varnish and its preparation method, which is basically the same as in Example 1, except that in the preparation process of the hyperbranched water-based epoxy resin, the polycarbonate polyol is replaced with an equal molar amount of polyether polyol (specifically polyether polyol 2000), and 4,4'-diaminodiphenylmethane is replaced with an equal molar amount of isophorone diamine. That is, in this example, the molar ratio of polyether polyol, isophorone diamine, epoxy resin E20, and hyperbranched epoxy resin E102 is 1:2.9:1.66:1.5.

[0069] Comparative Example 3: This example provides a water-based insulating varnish and its preparation method, which is basically the same as in Example 1. The only difference is that in the preparation process of the hyperbranched water-based epoxy resin, all components are mixed together and reacted at 100°C until the amine value is less than 5 mg KOH / g. The reaction ends and the hyperbranched water-based epoxy resin is obtained.

[0070] Performance testing: The water-based insulating varnishes prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests, and the specific results are shown in Table 4.

[0071] Performance indicator test instructions: 1. Viscosity test: DIN53015; 2. Temperature resistance index: Rapid aging method (TG), using TG thermogravimetric analyzer, heating rate 10℃ / min, room temperature ~ 900℃; 3. Crack resistance test: Double torsion test - fracture energy (GIC), ISO13586; 4. Thermal conductivity test: ISO8894-1; 5. Electrical strength test: GB / T 15022.3 - 2011 6. Volume resistivity test: GB / T 1410-1989; 7. Bending strength test: ISO R 527; 8. Tensile strength test: ISO R 527; 9. Glass transition temperature: TEC 1006; 10. Flame retardancy test: UL94; 11. Thermal shock / cycle count (-45~155℃), IEC60068-2-14: Place an iron block with sharp edges into the mixed adhesive, prepare a corresponding sample according to the curing method, freeze the sample in a -45℃ low-temperature chamber for 3 hours, take it out and bake it at 155℃ for 3 hours; then take out the sample again, freeze it in a -45℃ low-temperature chamber for 3 hours, take it out and bake it at 155℃ for 3 hours, repeat this cycle until cracks appear, and record the number of cycles.

[0072] 12. Storage stability / viscosity growth factor (60℃ / 24h): Test the viscosity before the test (60℃), then place it in a 60℃ oven and let it stand for 24h. After 24h, stir it evenly and test the viscosity (60℃), and record the viscosity growth factor.

[0073] Table 4

[0074] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0075] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A water-based insulating varnish, characterized in that, The raw materials of the water-based insulating varnish include hyperbranched water-based epoxy resin, curing agent, and thermally conductive filler; The raw materials for the hyperbranched waterborne epoxy resin include: Component (a), polycarbonate polyol; Component (b), the compound shown in formula (I); In equation (Ⅰ), R1 is selected from C 1-3 Alkylene, R2, R3 are independently selected from C 1-3 Alkylene, one bond, R4 and R5 independently selected from H and C. 1-6 Alkyl groups, m and n are independently selected from 0, 1, and 2; Component (c), the compound shown in formula (II); In equation (II), R6, R7, and R8 are independently selected from C. 1-6 Alkyl group, R9 is selected from C 1-3 Alkylene; Component (d): Bisphenol A type epoxy resin with a molecular weight of 800 or higher; Component (e), hyperbranched epoxy resin with an epoxy value of 0.1-0.3 mol / 100g; In the process of preparing the hyperbranched waterborne epoxy resin, after components (a), (b) and (c) are mixed and reacted, component (d) is added and reacted, and then component (e) is added and reacted.

2. The water-based insulating varnish according to claim 1, characterized in that, In formula (I), R1 is selected from methylene, ethylene, or propylene; and / or, in formula (I), R2 and R3 are each a single bond; and / or, in formula (I), R4 and R5 are independently selected from H, methyl, or ethyl; and / or, in formula (II), R6, R7, and R8 are independently selected from methyl, ethyl, or propyl; and / or, in formula (II), R9 is selected from methylene, ethylene, or propylene.

3. The water-based insulating varnish according to claim 1, characterized in that, Component (b) is selected from 4,4'-diaminodiphenylmethane; and / or, component (c) is selected from isophorone diamine; and / or, in component (d), the molecular weight of the bisphenol A type epoxy resin is 800-5000; and / or, component (d) is selected from one or more combinations of epoxy resin E20, epoxy resin E12, epoxy resin E09, and epoxy resin E06; and / or, in component (e), the molecular weight of the hyperbranched epoxy resin is 3000-4000; and / or, in component (a), the molecular weight of the polycarbonate polyol is 1000-4000.

4. The water-based insulating varnish according to claim 1, characterized in that, In component (a), the polycarbonate polyol is prepared by the following method: a hyperbranched polyester with 5 or more hydroxyl groups per molecule, 1,6-hexanediol, diethylene glycol and dimethyl carbonate are subjected to transesterification at 145-180℃. When the methanol distillation reaches 80%-90% of the theoretical value, the temperature is raised to 210-230℃, the vacuum is drawn to 10-50 Pa, and polycondensation reaction is carried out under vacuum negative pressure to generate polycarbonate polyol. Furthermore, the hydroxyl value of the polycarbonate polyol is controlled to be 70-90 mg KOH / g; Further, the molar ratio of the terminal hydroxyl hyperbranched polyester, the 1,6-hexanediol, the diethylene glycol, and the dimethyl carbonate is 1:0.8-1.2:0.8-1.2:1.0-2.0, preferably 1:0.8-1.2:0.8-1.2:1.3-1.8; Further, the hydroxyl-terminated hyperbranched polyester has a hydroxyl value of 400-600 mgKOH / g; and / or, the molecular weight of the hydroxyl-terminated hyperbranched polyester is 1000-1500.

5. The water-based insulating varnish according to claim 1, characterized in that, The hyperbranched waterborne epoxy resin is prepared by the following method: Components (a), (b), and (c) are reacted at a first preset temperature. After the reaction, component (d) is added, and the temperature is raised to a second preset temperature for further reaction. After the reaction, component (e) is added, and the reaction is continued at the second preset temperature until the amine value is less than 5 mg KOH / g. Furthermore, the first preset temperature is 75-85℃; Furthermore, the second preset temperature is 95-105℃; Furthermore, the generated hyperbranched waterborne epoxy resin is dispersed in water to prepare a hyperbranched waterborne epoxy resin emulsion.

6. The water-based insulating varnish according to claim 1, characterized in that, The thermally conductive filler includes boron nitride, spherical alumina, aluminum hydroxide, and carbon nanotubes; Furthermore, the mass ratio of the boron nitride, the spherical alumina, the aluminum hydroxide, and the carbon nanotubes is 1:2-4:8-10:0.5-2.0; Furthermore, the boron nitride has a particle size D50 of 1-5 μm; Furthermore, the particle size D50 of the spherical alumina is 0.5-15 μm; Furthermore, the particle size D50 of the aluminum hydroxide is 0.5-40 μm; Furthermore, the carbon nanotubes have a diameter of 10-20 nm, a length of 10-30 μm, and an aspect ratio of 100-300.

7. The water-based insulating varnish according to claim 1, characterized in that, The molar ratio of components (a), (b), (c), (d), and (e) is 1:1-2:1-2:1-2:1-2; and / or, The raw materials of the water-based insulating varnish, by weight, comprise: Hyperbranched waterborne epoxy resin emulsion 30wt.%-45wt.%; Curing agent 5wt.%-10wt.%; Thermally conductive filler 25wt.%-40wt.%; Aqueous wetting agent 0.1wt.%-1wt.%; Water-based defoamer 0.1wt.%-1wt.%; Water 15wt.%-35wt.%; The hyperbranched waterborne epoxy resin emulsion is made by dispersing hyperbranched waterborne epoxy resin in water, and its solid content is 60wt.%-70wt.%.

8. A method for preparing the water-based insulating varnish according to any one of claims 1-7, characterized in that, The preparation method includes: A water-based insulating varnish is prepared by mixing hyperbranched waterborne epoxy resin, curing agent, thermally conductive filler, water, and selective additives.

9. The application of the water-based insulating varnish according to any one of claims 1-7 in the preparation of motors and transformers.

10. A hyperbranched waterborne epoxy resin, characterized in that, The raw materials for the hyperbranched waterborne epoxy resin include: Component (a), polycarbonate polyol; Component (b), the compound shown in formula (I); In equation (Ⅰ), R1 is selected from C 1-3 Alkylene, R2, R3 are independently selected from C 1-3 Alkylene, one bond, R4 and R5 independently selected from H and C. 1-6 Alkyl groups, where m and n are independently 0, 1, and 2; Component (c), the compound shown in formula (II); In equation (II), R6, R7, and R8 are independently selected from C. 1-6 Alkyl group, R9 is selected from C 1-3 Alkylene; Component (d): Bisphenol A type epoxy resin with a molecular weight of 800 or higher; Component (e), hyperbranched epoxy resin with an epoxy value of 0.1-0.3 mol / 100g; In the process of preparing the hyperbranched waterborne epoxy resin, after components (a), (b) and (c) are mixed and reacted, component (d) is added and reacted, and then component (e) is added and reacted.

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