Degradable epoxy resin insulating material for electrical equipment as well as preparation method and application of degradable epoxy resin insulating material

Abstract

The invention discloses a degradable epoxy resin insulating material for electrical equipment as well as a preparation method and application of the degradable epoxy resin insulating material, and relates to the technical field of functional polymer materials. The degradable epoxy insulating material is prepared from an epoxy monomer, a transesterification catalyst N-methyldiethanolamine and an anhydride curing agent. Compared with a material prepared by a traditional method, the material has more excellent insulating property and mechanical property, the breakdown strength can reach up to 48.2 kV / mm, the dielectric loss is as low as 0.00116, the tensile strength reaches up to 93.5 Mpa, and the thermal stability is equivalent to that of traditional epoxy resin. Meanwhile, the epoxy resin disclosed by the invention can realize hot-pressing remolding recovery and chemical degradation recovery under mild conditions by virtue of a dynamic ester exchange reaction, and the performance retention rate gt of the physically regenerated resin is gt; the performance retention rate of the chemically regenerated resin is gt; 87%. According to the invention, a high-performance and sustainable new scheme can be provided for an electrical equipment insulating material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional polymer materials, and particularly relates to a degradable epoxy resin insulating material for electrical equipment and a preparation method and application thereof. BACKGROUND

[0002] An acid anhydride cured epoxy resin can form a highly cross-linked three-dimensional network structure after curing, and thus has excellent electrical and mechanical properties, and is widely used in casting insulation of electrical equipment such as dry-type transformers, voltage transformers and composite insulators. After the electrical equipment is retired, due to the insoluble and infusible characteristics of the traditional epoxy resin insulating layer, the expensive metal devices inside are difficult to recycle, and the whole is usually treated by recycling and burying. This not only causes serious environmental pollution problems, but also causes waste of resources, and thus it is urgent to develop a degradable epoxy resin with excellent comprehensive performance.

[0003] At present, by introducing reversible dynamic covalent bonds such as disulfide bonds, Schiff bases, acetal bonds and borate ester bonds into epoxy resins, the degradability and recyclability of the materials can be realized. However, the introduction of the above dynamic bonds usually also sacrifices some other properties of the material, for example, the glass transition temperature (Tg) is reduced, and the mechanical strength does not meet the application requirements, and there is still a significant gap between the actual industrialization level and the commercialization target.

[0004] Traditional anhydride-cured epoxy resin has excellent comprehensive performance, and is rich in ester bonds inside. These ester bonds are very stable under normal conditions (without catalyst), have high bond energy, and require a lot of energy to break, making it difficult to recycle the material. By introducing an endogenous transesterification catalyst during the curing process of anhydride-cured epoxy resin, the activation energy of the transesterification reaction can be significantly reduced. The internal transesterification catalyst remains stable at service temperature, and under the condition of higher temperature and external acid-base solution, the ester bonds in the crosslinked network can undergo reversible breaking and recombination, making the material degradable and recyclable. However, there are many types of transesterification catalysts, and the usage, dosage and catalytic effect are not clear. The performance retention rate of recycled and reused materials is not high enough. For example, the existing literature (Wu Y, Hu Y, Lin H, et al. An anhydride-cured degradable epoxy insulating material exhibiting recyclability, reusability, and excellent electrical performance[J]. Green Chemistry, 2024, 26(4): 2258-2268.) discloses a degradable epoxy insulating material prepared by using transesterification catalyst triethanolamine (TEOA) and epoxy monomer, anhydride curing agent methylhexahydrophthalic anhydride (MHHPA). The performance retention rate of the recycled and reused material is only about 70%, the breakdown field strength of the physically recycled material is only about 25kV / mm, and the breakdown field strength of the chemically recycled material is only about 33kV / mm. Therefore, it is of great significance to develop a degradable epoxy resin preparation method based on transesterification, and to explore the regulation relationship between the dosage of transesterification catalyst and the performance of the material, in order to improve the performance retention rate of the recycled and reused material. SUMMARY

[0005] In view of the above problems, the present application provides a degradable epoxy resin insulating material for electrical equipment and a preparation method and application thereof, which solves the problem of low performance retention rate of the degradable epoxy insulating material prepared by the prior art after recycling and reuse, and the specific technical scheme is as follows: A preparation method of a degradable epoxy resin insulating material for electrical equipment, comprising the following steps: (1) mixing epoxy monomer and transesterification catalyst according to a molar ratio of 1:0.05-0.2, stirring and reacting, and vacuum degassing; (2) adding an anhydride curing agent to the mixed solution after vacuum degassing in step (1), the molar ratio of the epoxy monomer to the anhydride curing agent being 1:0.5-0.55, stirring and reacting, and vacuum degassing; (3) Pour the mixed solution after vacuum degassing in step (2) into a mold for casting, and then put it into a thermostat for gradient curing molding, to obtain the degradable epoxy insulating material.

[0006] Further, in step (1), the epoxy monomer includes one or more of glycidyl ether, glycidyl ester, glycidyl amine, alicyclic epoxy resin, epoxidized olefin, hydantoin epoxy resin, and imide epoxy resin.

[0007] Further, in step (1), the transesterification catalyst includes one or more of N-methyldiethanolamine (MDEA), triisopropanolamine (TIPA), triethanolamine (TEOA), diethanolamine, triethylamine (TEA), zinc acetylacetonate (Zn(acac)2), zinc acetate, 1,5,7-triazabicyclodec-5-ene (TBD), dimethylaminomethylphenol, triphenylphosphine, titanate, and imidazole compound.

[0008] Further, in step (1), the stirring reaction temperature is 80-100℃, and the stirring time is 10-30 minutes; the vacuum degassing temperature is 80-100℃, and the degassing time is 10-30 minutes.

[0009] Further, in step (2), the anhydride curing agent includes one or more of phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, methyl nadic anhydride, glutaric anhydride, maleic anhydride, eleostearic anhydride, olefin-based succinic anhydride, methylcyclohexene tetra-carboxylic dianhydride, dodecenyl succinic anhydride, trimellitic anhydride, hydrogenated trimellitic anhydride, hydrogenated pyromellitic dianhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, polyadipic anhydride, polynonanoic anhydride, polysebacic anhydride, ethylene glycol bis-trimellitic anhydride ester, glycerol tri-trimellitic anhydride ester, and diphenyl sulfone tetracarboxylic dianhydride.

[0010] Further, in step (2), the stirring reaction temperature is 60-80℃, and the stirring time is 10-30 minutes; the vacuum degassing temperature is 60-80℃, and the degassing time is 10-30 minutes.

[0011] Further, in step (3), the gradient curing procedure includes four stages: first stage: 80℃ for 2-3 hours; second stage: temperature rising to 90-100℃ at ≤5℃ / min, and holding for 1-2 hours; third stage: temperature rising to 110-120℃, and holding for 1-2 hours; and fourth stage: temperature rising to 140-160℃, and holding for 4-6 hours.

[0012] The application also provides a degradable epoxy resin insulating material prepared by the preparation method.

[0013] Further, the insulating material can be physically recycled and chemically recycled at the same time. The physical recycling method is: crushing the insulating material to a particle size of ≤800 μm, hot pressing at 180-220℃ and a pressure of 6-10 MPa for 2-3 hours to obtain a physically regenerated epoxy resin, and the performance retention rate of the physically regenerated epoxy resin is >85%. The chemical recycling method is: preparing a mixed solvent according to a mass ratio of MDEA:ethanol of 1:1, crushing the insulating material and adding it into the mixed solvent, the mass ratio of the insulating material to the mixed solvent is 1:5, after the insulating material is completely degraded, the degradation product is taken out and resolidified with an epoxy monomer and an anhydride curing agent to obtain a chemically regenerated epoxy resin, and the performance retention rate of the chemically regenerated epoxy resin is >87%.

[0014] The application also provides an application of the degradable epoxy resin insulating material prepared by the preparation method in the field of electrical insulation, and the application is used as an insulating material in electrical equipment.

[0015] Compared with the prior art, the application has the following beneficial effects: 1. The application has more excellent insulating performance and mechanical properties than the traditional epoxy resin system, wherein the breakdown strength of the insulating material prepared by the application can be as high as 48.2kV / mm, the dielectric loss can be as low as 0.00116, the tensile strength can be as high as 93.5Mpa, and the thermal stability is equivalent to that of the traditional epoxy resin (Ts=188.41℃, Tg=133.8℃). At the same time, the epoxy resin of the application can realize hot pressing recycling (physical method) and chemical degradation recycling under mild conditions by virtue of the dynamic ester exchange reaction, the performance retention rate of the physically regenerated resin is >85%, and the chemical degradation product can be directly used for the synthesis of regenerated resin, and the performance retention rate of the chemically regenerated resin is >87%. The application provides a high-performance and sustainable new solution for electrical equipment insulating materials.

[0016] 2. The N-methyldiethanolamine (MDEA) in the application can not only be used as an ester exchange catalyst, but also be used as an epoxy resin degrading agent. On the basis of the traditional anhydride curing epoxy resin formula, the MDEA is added as an ester exchange catalyst for modification, and the molded material can be prepared only by a simple process. The modified preparation method is suitable for various epoxy resins and anhydride curing systems. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description.

[0018] Figure 1 (a) Preparation scheme of the degradable epoxy resin based on transesterification reaction for inventive examples 1, 2, 3, 4.

[0019] Figure 1 (b) Preparation scheme of the degradable epoxy resin based on transesterification reaction for inventive examples 5, 6, 7, 8.

[0020] Figure 2 Flow chart of the physical hot-pressing recycling and chemical degradation recycling for inventive example 10.

[0021] Figure 3 Digital picture of the hot-pressing remolding recycling results for inventive example 9.

[0022] Figure 4 Fourier infrared spectrum of the degradable epoxy insulation material based on transesterification reaction for inventive examples 1, 2, 3, 4.

[0023] Figure 5 Fourier infrared spectrum of the degradable epoxy insulation material based on transesterification reaction for inventive examples 5, 6, 7, 8.

[0024] Figure 6 Fourier infrared spectrum of the degradable epoxy insulation material based on transesterification reaction for comparative examples 1, 2, 3.

[0025] Figure 7 Preparation flow chart of inventive examples 1, 2, 3, 4, 5, 6, 7, 8 and comparative examples 1, 2, 3, 4. DETAILED DESCRIPTION

[0026] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0027] The raw materials in the following examples and comparative examples are commercially purchased unless otherwise specified.

[0028] Main test methods: Thermogravimetric analysis: 5 mg of resin sample was placed in an alumina crucible, and the temperature was increased from room temperature to 800℃ at a rate of 10℃ / min under N2 atmosphere to obtain T d(5％) , T d(30％) d; wherein, Td (5％) represents the initial decomposition temperature of the polymer; Td (30％) represents the temperature at which the mass loss of the polymer is 30%, and the heat resistance index is calculated by the formula: Tensile strength test: mechanical property test was performed on a Japan Toray universal material testing machine according to GB / T 2567-2008; According to GB / T 1408.1-2016, the test instrument is composed of a power frequency AC power supply, a protective water resistance, a voltage divider, and a rod electrode device. Under high voltage conditions, the electrical strength of insulating materials is a probability value, and the experimental results vary greatly. The electrical strength of the sample is fitted using the Weibull distribution model. The calculation formula of the Weibull distribution is: wherein, is the electrical strength, is the scale parameter, which represents the electrical strength when the breakdown probability reaches 63.2%, is the shape parameter, which corresponds to the inverse of the dispersion of the breakdown data.

[0029] Dielectric properties: measured by NEISYS integrated electrochemical analyzer (Novocontrol, Germany). The text is at ambient temperature with a frequency of 1-10 6 Hz, and the sample thickness is 1 mm.

[0030] The glass transition temperature is measured by dynamic thermodynamic analysis (DMA; Mettler Toledo). The DMA experiment uses a "single cantilever" mode, a frequency of 1 Hz, and a heating rate of 5 ℃ min -1 . The sample size used is 35 mm (length) x 10 mm (width) x 2 mm (thickness).

[0031] Example 1 (1) Preparation of degradable epoxy resin based on MDEA catalysis Take 5g of bisphenol A type epoxy resin (E-51) into a container containing magnetic particles, then add 0.088g of transesterification catalyst N-methyldiethanolamine (MDEA) into the above container, mix and stir the E-51 epoxy resin and MDEA resin at 100℃ for 20 min to make them uniformly mixed, wherein the stirring speed is 200rpm. Perform vacuum degassing treatment on the mixed solution in a vacuum drying box at a temperature of 80℃ for 30 min; after the vacuum degassing is completed, add methyltetrahydrophthalic anhydride (MTHPA) 2.44g into the mixed solution, and stir again at a constant temperature of 70℃ for 20 min to make them uniformly mixed, thereby preparing a resin prepolymer glue solution. Then perform vacuum degassing treatment on the degassed resin prepolymer glue solution in a vacuum drying box at a temperature of 80℃ for 15 min. Pour the degassed resin prepolymer glue solution into a stainless steel mold preheated at 90℃ and coated with a release agent, and perform curing according to the following four stages: first stage: 80℃ for 2 hours; second stage: temperature rising to 90℃ at a rate of ≤5℃ / min, and keeping the temperature for 2 hours; third stage: temperature rising to 120℃, and keeping the temperature for 1 hour; fourth stage: temperature rising to 140℃, and keeping the temperature for 4 hours. After the curing is completed, naturally cool, demold, and prepare a degradable epoxy insulating material based on MDEA catalysis.

[0032] Example 2: Prepare a modified epoxy resin according to the method basically same as that of Example 1, with the only difference being that the mass of the added transesterification catalyst N-methyldiethanolamine (MDEA) is 0.176g.

[0033] Example 3: Prepare a modified epoxy resin according to the method basically same as that of Example 1, with the only difference being that the mass of the added transesterification catalyst N-methyldiethanolamine (MDEA) is 0.264g.

[0034] Example 4: Prepare a modified epoxy resin according to the method basically same as that of Example 1, with the only difference being that the mass of the added transesterification catalyst N-methyldiethanolamine (MDEA) is 0.352g.

[0035] Example 5: Prepare a modified epoxy resin according to the method basically same as that of Example 1, with the only difference being that the anhydride curing agent used is methyl nadic anhydride (MNA), and the amount used is 2.62g. The curing conditions are as follows: first stage: 80℃ for 2 hours; second stage: temperature rising to 100℃ at a rate of ≤5℃ / min, and keeping the temperature for 2 hours; third stage: temperature rising to 120℃, and keeping the temperature for 2 hours; fourth stage: temperature rising to 160℃, and keeping the temperature for 4 hours.

[0036] Example 6: A modified epoxy resin was prepared by referring to a method substantially the same as that in Example 5, except that 0.176 g of N-methyldiethanolamine (MDEA) was added as an ester exchange catalyst.

[0037] Example 7: The modified epoxy resin was prepared by referring to a method substantially the same as that in Example 5, except that 0.264 g of N-methyldiethanolamine (MDEA) was added as an ester exchange catalyst.

[0038] Example 8: The modified epoxy resin was prepared by referring to a method substantially the same as that in Example 5, except that 0.352 g of N-methyldiethanolamine (MDEA) was added as an ester exchange catalyst.

[0039] Example 9: (2) Epoxy resin physical recovery experiment First, use a grinder to crush the epoxy resin, and take 2.5g of epoxy resin powder into a metal mold that has been sprayed with a release agent and preheated. Under the action of a flat vulcanizer, hot press treatment is performed under hot pressing conditions of 200℃-10MPa-3h to hot press the epoxy resin powder into shape.

[0040] Example 10: (3) Epoxy resin degradation experiment Epoxy resins prepared with different transesterification catalysts were pulverized using a grinder. A degradation solution was prepared using N-methyldiethanolamine (MDEA) as a degradation agent at a 1:1 MDEA:ethanol mass ratio. The epoxy resin and degradation solution were added to a sealed container at a 1:5 mass ratio. The container was placed in an incubator at 130°C for degradation, and the time required for complete degradation was calculated. The epoxy resin used in this example weighed 1g.

[0041] Example 11: (4) Resolidification of chemical degradation products Bisphenol A epoxy resin and methyltetrahydrophthalic anhydride (MTHPA) were added to a container at a molar ratio of 1:1. The degradation product solution was then added at a concentration of 2% of the total mass of the epoxy monomer and anhydride curing agent. The mixed solution was stirred at 80°C at 200 rpm until uniformly mixed. The subsequent steps of Example 1 were then followed to obtain a re-cured epoxy resin material.

[0042] Comparative Example 1: The modified epoxy resin was prepared by referring to the method basically the same as that in Example 1, except that the transesterification catalyst added was 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), with a mass of 0.04 g. Comparative Example 2: Take 5g of bisphenol A type epoxy resin (E-51) into a container containing a magnet, add solid catalyst 1,5,7-triazobicyclo[4.4.0]dec-5-ene (TBD) 0.1g into the mixed solution, mix and stir the TBD and E-51 resin at 80°C for 30 minutes to make them uniformly mixed, wherein the stirring speed is 200 rpm. The mixed solution is subjected to vacuum degassing treatment in a vacuum drying box at a temperature of 80°C for 30 min; after vacuum degassing is completed, 2.44g of curing agent methyltetrahydrophthalic anhydride (MTHPA) is weighed into the above container, mixed and stirred at 60°C for 20 minutes to make them uniformly mixed, and a resin prepolymer glue solution is prepared. Then, the degassed resin prepolymer glue solution is poured into a stainless steel mold preheated to 100°C and coated with a release agent, and cured at a temperature of 100°C for 2h, then cured at a temperature of 140°C for 3h, and finally cured at a temperature of 170°C for 3h, naturally cooled, demolded, to prepare an epoxy resin based on TBD catalysis.

[0043] Comparative Example 3: Take 5g of bisphenol A type epoxy resin (E-51) into a container containing a magnet, add solid catalyst acetylacetone zinc (Zn(acac)2) 0.097g into the mixed solution, mix and stir the Zn(acac)2 and E-51 resin at 130°C for 30 minutes to make them uniformly mixed, wherein the stirring speed is 200 rpm. The mixed solution is subjected to vacuum degassing treatment in a vacuum drying box at a temperature of 80°C for 30 min; at the same time, 1.68g of curing agent glutaric anhydride (GA) is weighed into another container and placed in a 130°C constant temperature oven to melt into a liquid, then the GA is added to the resin matrix after vacuum degassing is completed, mixed and stirred at 100°C for 20 minutes to make them uniformly mixed, and a resin prepolymer glue solution is prepared. Then, the degassed resin prepolymer glue solution is poured into a stainless steel mold preheated to 110°C and coated with a release agent, and cured at a temperature of 110°C for 3h, then cured at a temperature of 140°C for 6h, and finally cured at a temperature of 160°C for 2h, naturally cooled, demolded, to prepare an epoxy resin based on Zn(acac)2 catalysis.

[0044] Comparative Example 4: A modified epoxy resin was prepared according to the same method as in Example 1, except that the mass of the ester exchange catalyst triethanolamine (TEOA) was 0.22 g; the acid anhydride curing agent used was methylhexahydrophthalic anhydride (MHHPA) with a mass of 2.47 g. The curing conditions were 100°C / 2h+130°C / 2h+70°C / 2h. The hot-pressing experiment was performed according to Example 9, and the hot-pressing conditions were 200°C / 10 MPa / 3 h. The degradation experiment was performed according to Example 10, and the degradation solution was replaced with triethanolamine (TEOA).

[0045] The raw material formulations of Examples 1-8 and Comparative Examples 1-4 are shown in Tables 1 and 2, respectively: Table 1 Raw material formulations of Examples 1-8 Table 2 Raw material formulations of Comparative Examples 1-4 The performance test results of Examples 1-8 and Comparative Examples 1-4 are shown in Table 3: Table 3 Performance test results of each group The performance test results of Example 11 are shown in Table 4. Among the two acid anhydride curing systems of Examples 1-8, the resins of Example 2 and Example 6 with the best overall performance were selected for hot-pressing and degradation recycling, and Comparative Example 4 of the existing resin system was selected for comparison and illustration: Table 4 Performance test results of each group It can be seen that the acid anhydride-cured epoxy resin catalyzed by MDEA has excellent overall performance, and the insulation performance is particularly improved (the breakdown strength can reach 48.2KV / mm). Moreover, it can be recycled not only by chemical recycling, but also by physical hot-pressing recycling. However, the acid anhydride-cured epoxy resin catalyzed by DMP-30 and TBD cannot be physically hot-pressed, and the chemical recycling time is also longer. The acid anhydride-cured epoxy resin catalyzed by Zn(acac)2 and glutaric anhydride can be recycled by both physical and chemical methods, but the Zn 2+ reduces the insulation strength of the resin, which is not suitable for use as an insulating material. Compared with the existing epoxy resin catalyzed by triethanolamine (TEOA) (background art), the performance retention rate of the recycled material by physical (>85%) or chemical (>87%) recycling according to the present application is greater than that of the epoxy resin insulating material catalyzed by TEOA (>70%).

[0046] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.

Claims

1. A method for preparing a degradable epoxy resin insulation material for electrical equipment, characterized in that: The following steps are involved: (1) Mix epoxy monomer and N-methyldiethanolamine in a molar ratio of 1:0.05-0.2, stir to react, and vacuum degas; (2) adding an anhydride curing agent to the mixed solution after vacuum degassing in step (1), wherein the molar ratio of the epoxy monomer to the anhydride curing agent is 1:0.5-0.55, stirring to react, and vacuum degassing; (3) The mixed solution after vacuum degassing in step (2) is poured into a mold for casting, and then placed in a constant temperature box for gradient curing and molding, thereby obtaining the degradable epoxy insulation material.

2. The method for preparing a degradable epoxy resin insulation material for electrical equipment according to claim 1, characterized in that: In step (1), the epoxy monomer includes one or more of glycidyl ethers, glycidyl esters, glycidyl amines, alicyclic epoxy resins, epoxidized olefins, hydantoin epoxy resins and imide epoxy resins.

3. The method for preparing a degradable epoxy resin insulation material for electrical equipment according to claim 1, characterized in that: In step (1), the temperature of the stirring reaction is 80-100° C., and the stirring time is 10-30 minutes; the temperature of the vacuum degassing is 80-100° C., and the degassing time is 10-30 minutes.

4. The method for preparing a degradable epoxy resin insulation material for electrical equipment according to claim 1, characterized in that: In step (2), the anhydride curing agent includes one or more of phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, glutaric anhydride, maleic anhydride, tung oil anhydride, olefin succinic anhydride, methylcyclohexene tetracarboxylic dianhydride, dodecenyl succinic anhydride, trimellitic anhydride, hydrogenated trimellitic anhydride, hydrogenated pyromellitic dianhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, polyadipic anhydride, polyazepine anhydride, polyselenoic anhydride, ethylene glycol bis(trimellitic anhydride), propylene glycol trimellitic anhydride, and diphenyl sulfone tetracarboxylic dianhydride.

5. The method for preparing a degradable epoxy resin insulation material for electrical equipment according to claim 1, characterized in that: In step (2), the temperature of the stirring reaction is 60-80°C, and the stirring time is 10-30 minutes; the temperature of the vacuum degassing is 60-80°C, and the degassing time is 10-30 minutes.

6. The method for preparing a degradable epoxy resin insulation material for electrical equipment according to claim 1, characterized in that: In step (3), the gradient curing procedure includes four stages: the first stage: curing at 80°C for 2 to 3 hours; the second stage: heating to 90 to 100°C at a rate of ≤5°C / min and keeping warm for 1 to 2 hours; the third stage: heating to 110 to 120°C and keeping warm for 1 to 2 hours; the fourth stage: heating to 140 to 160°C and keeping warm for 4 to 6 hours.

7. A degradable epoxy resin insulating material, characterized in that: The insulating material is prepared by the preparation method according to any one of claims 1 to 6.

8. The degradable epoxy resin insulating material according to claim 7, characterized in that: The insulating material can be recycled physically and chemically at the same time; The physical recycling method comprises: crushing the insulating material to a particle size of ≤800 μm, hot pressing at 180-220° C. and 6-10 MPa pressure for 2-3 hours to obtain a physically regenerated epoxy resin, wherein the performance retention rate of the physically regenerated epoxy resin is greater than 85%; The chemical recovery method comprises: preparing a mixed solvent in a mass ratio of MDEA to ethanol of 1:1, crushing the insulating material and adding it to the mixed solvent, wherein the mass ratio of the insulating material to the mixed solvent is 1:5; after the insulating material is completely degraded, taking the degradation product and re-curing it with an epoxy monomer and an acid anhydride curing agent to obtain a chemically regenerated epoxy resin, wherein the performance retention rate of the chemically regenerated epoxy resin is greater than 87%.

9. Use of a degradable epoxy resin insulating material prepared by the preparation method according to any one of claims 1 to 6 in the field of electrical insulation, characterized in that: The application is as an insulating material in electrical equipment.

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