An epoxy resin potting compound and its preparation method

Abstract

This invention relates to the field of polymer materials technology, specifically disclosing an epoxy resin potting compound and its preparation method. The epoxy resin potting compound comprises the following raw materials: 40-50 parts of epoxy resin matrix, 8-12 parts of reactive diluent, 3-6 parts of core-shell toughening agent, 40-45 parts of nanofiller, 12-16 parts of curing agent, and 1-1.5 parts of curing accelerator. The preparation method includes: S1, mixing and stirring the epoxy resin matrix, reactive diluent, core-shell toughening agent, and nanofiller until homogeneous to obtain a mixture; S2, adding the curing agent and curing accelerator to the mixture and continuing to stir until homogeneous to obtain the epoxy resin potting compound. The epoxy resin potting compound prepared by this invention exhibits excellent impact resistance, weather resistance, and salt spray corrosion resistance, while maintaining good tensile strength and electrical insulation properties, significantly improving the reliability and service life of electronic component packaging.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to an epoxy resin potting compound and its preparation method. Background Technology

[0002] With the rapid development of the modern electronics industry, electronic components are moving towards miniaturization, integration, and high power. These precision electronic devices place higher demands on the performance of packaging materials. Epoxy resin potting compounds occupy an important position in the field of electronic packaging due to their excellent electrical insulation, adhesive strength, and mechanical strength.

[0003] However, traditional epoxy resin potting compounds also have some inherent limitations. First, the high cross-linking density of cured epoxy resin results in a brittle texture and poor impact resistance. When electronic components are subjected to drops, vibrations, or thermal cycling, cracks or even detachment can easily occur, severely affecting the reliability of the equipment. Second, many electronic devices need to operate outdoors or in harsh environments, and prolonged exposure to ultraviolet radiation, humidity, heat, acids, and alkalis can cause epoxy resin to age and degrade, leading to yellowing, cracking, and a decline in mechanical properties, thus affecting its encapsulation and protective functions. Furthermore, some industrial electronic equipment requires potting compounds with excellent corrosion resistance to withstand the erosion of various chemical media.

[0004] In existing technologies, to improve the impact resistance of epoxy resins, toughening is often achieved by adding liquid rubber, silicone elastomers, or thermoplastic resins; to improve weather resistance, ultraviolet absorbers or light stabilizers are added; and to enhance corrosion resistance, inert fillers or special curing agents may be introduced. However, these single modification methods often fail to achieve a synergistic improvement in multiple properties. For example, the addition of toughening agents may sacrifice the material's hardness or thermal stability; ultraviolet absorbers may have problems with precipitation or limited absorption bands; and the enhancement of corrosion resistance often contradicts mechanical properties or weather resistance. Based on the above, this invention proposes an epoxy resin potting compound and its preparation method. Summary of the Invention

[0005] To address the shortcomings of existing epoxy resin potting compounds in terms of impact resistance, weather resistance, and corrosion resistance, this invention proposes an epoxy resin potting compound and its preparation method. This invention achieves a comprehensive and synergistic improvement in the impact resistance, weather resistance, and corrosion resistance of the epoxy resin potting compound. When used for encapsulating electronic components, the resulting potting compound significantly improves the encapsulation reliability and lifespan of electronic components.

[0006] In a first aspect, the present invention provides an epoxy resin potting compound, which adopts the following technical solution: An epoxy resin potting compound comprises the following raw materials in parts by weight: 40-50 parts epoxy resin matrix, 8-12 parts reactive diluent, 3-6 parts core-shell toughening agent, 40-45 parts nanofiller, 12-16 parts curing agent, and 1-1.5 parts curing accelerator.

[0007] Preferably, the epoxy resin matrix is ​​composed of bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester in a mass ratio of 7-9:1.

[0008] Preferably, the core-shell toughening agent is prepared by the following method: (1) Pretreated hydroxyl-terminated polybutadiene was obtained by vacuum dehydration of hydroxyl-terminated polybutadiene, anhydrous toluene was added and stirred, and then a catalyst was added and stirred and mixed to obtain a pre-reaction system. (2) The mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane was added dropwise to the pre-reaction system. After the addition was complete, the reaction was continued until the -NCO content in the system reached the theoretical value. The mixture was then cooled and filtered to obtain an isocyanate-terminated polybutadiene solution. (3) Add the isocyanate-terminated polybutadiene solution to the emulsion system, sonicate to obtain seed emulsion, add the premixture of glycidyl methacrylate, butyl acrylate and initiator dropwise to the seed emulsion, control the reaction to be completed in 2-3 hours, cool to room temperature to obtain core-shell toughening agent emulsion. (4) Under stirring, the core-shell toughening agent emulsion is added to the calcium chloride solution to break the emulsion and polymer particles are precipitated. The emulsion is then vacuum filtered, washed, and dried to obtain the core-shell toughening agent.

[0009] Preferably, in step (1), vacuum dehydration refers to vacuum dehydration for 2-3 hours at 105-115℃ and vacuum degree ≤-0.095MPa until the moisture content is ≤0.03%.

[0010] Preferably, in step (1), the mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and catalyst is 95-105:160-180:0.08-0.12.

[0011] Preferably, the catalyst in step (1) is dibutyltin dilaurate.

[0012] Preferably, in step (1), the anhydrous toluene is added at a temperature of 45-55°C, the stirring speed is 50-100 rpm, the stirring time is 30-40 min, and the catalyst is stirred for 15-20 min.

[0013] Preferably, in step (2), the amount of the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane added is 18-20% of the mass of the hydroxyl-terminated polybutadiene.

[0014] Preferably, in step (2), the mass ratio of isophorone diisocyanate to 4,4-diisocyanate dicyclohexylmethane in the mixture is 1:1.2-1.25.

[0015] Preferably, the reaction temperature in step (2) is 78-85℃.

[0016] Preferably, in step (2), the temperature inside the vessel is strictly controlled to be maintained within the range of 66-72°C during the dripping process.

[0017] Preferably, in step (2), cooling refers to cooling the reaction system to 30-40℃.

[0018] Preferably, in step (2), filtration refers to filtration through a 100-120 mesh filter.

[0019] Preferably, in step (3), the mass ratio of the isocyanate-terminated polybutadiene solution to the emulsion system is 1:2-2.5.

[0020] Preferably, the emulsification system in step (3) is a sodium dodecyl sulfate solution with a mass fraction of 1-1.5%.

[0021] Preferably, the ultrasonic treatment parameters in step (3) are as follows: ultrasonic power 300-500W, ultrasonic frequency 20-25kHz, ultrasonic treatment in an ice water bath for 15-30 minutes.

[0022] Preferably, in step (3), the amount of the premixture of glycidyl methacrylate, butyl acrylate and initiator added is 19-23% of the mass of the seed emulsion.

[0023] Preferably, in step (3), the mass ratio of glycidyl methacrylate, butyl acrylate and initiator in the premixture is 1:2.2-2.6:0.03-0.04.

[0024] Preferably, the initiator in step (3) is potassium persulfate.

[0025] Preferably, the reaction temperature in step (3) is 65-75℃ and the reaction time is 3-4h.

[0026] Preferably, the stirring speed in step (4) is 200-400 rpm.

[0027] Preferably, in step (4), the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution is 1:3-5.

[0028] Preferably, in step (4), the mass fraction of the calcium chloride solution is 1-5%, and the temperature is 70-80℃.

[0029] Preferably, the pore size of the microporous filter membrane used for filtration in step (4) is 10-30 μm.

[0030] Preferably, in step (4), washing refers to repeatedly washing with deionized water until the conductivity of the washing water is close to that of pure water.

[0031] Preferably, in step (4), drying refers to drying in a vacuum oven at 60-70°C until constant weight.

[0032] Preferably, the active diluent is diglycidyl tetrahydrophthalate or polyethylene glycol diglycidyl ether.

[0033] Preferably, the nanofiller is nano zinc oxide or nano aluminum oxide.

[0034] Preferably, the curing agent is methyltetrahydrophthalic anhydride or methylhexahydrophthalic anhydride.

[0035] Preferably, the curing accelerator is triphenylethylphosphine bromide.

[0036] Secondly, the present invention provides a method for preparing epoxy resin potting compound, which adopts the following technical solution: A method for preparing an epoxy resin potting compound includes the following steps: S1. Mix the epoxy resin matrix, reactive diluent, core-shell toughening agent and nanofiller evenly to obtain a mixture; S2. Add curing agent and curing accelerator to the mixture and continue to stir until homogeneous to obtain epoxy resin potting compound.

[0037] Preferably, in step S1, the stirring speed is 800-1200 rpm, the stirring temperature is 30-40℃, and the stirring time is 2-3 hours.

[0038] Preferably, in step S2, the stirring speed is 200-400 rpm, the stirring temperature is 20-30℃, and the stirring time is 30-45 min.

[0039] In summary, the present invention has the following beneficial effects: 1. This invention utilizes the synergistic effect of core-shell toughening agents and compounded resin matrices to compound bisphenol A type epoxy resin with alicyclic epoxy resin exhibiting excellent weather resistance, and introduces a toughening agent with a "soft core-tough shell" structure. This results in an epoxy resin potting compound with excellent impact resistance, weather resistance, and salt spray corrosion resistance, while maintaining good tensile strength and electrical insulation properties, significantly improving the reliability and service life of electronic component packaging.

[0040] 2. This invention uses a compound of hydroxyl-terminated polybutadiene, isophorone diisocyanate, and 4,4-diisocyanate dicyclohexylmethane to prepare an isocyanate-terminated polybutadiene prepolymer. The isocyanate-terminated polybutadiene prepolymer is then reacted with a mixture of glycidyl methacrylate and butyl acrylate monomers via seed emulsion polymerization to obtain a core-shell toughening agent. The hydroxyl-terminated polybutadiene serves as a soft core framework, and its long, flexible polybutadiene segments impart excellent low-temperature toughness and elasticity to the toughening agent. The isophorone diisocyanate prepolymer is used... The compound of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane, used as a capping agent, exhibits controllable reactivity compared to highly reactive aromatic diisocyanates. Furthermore, both are fully alicyclic structures, imparting excellent weather resistance and anti-yellowing properties to the toughening agent. In addition, the rigid cyclic structure of isophorone diisocyanate helps improve the stiffness of the toughening agent-matrix interface, enhancing stress transfer efficiency; while the flexible chain structure of 4,4-diisocyanate dicyclohexylmethane better imparts flexibility to the toughening agent and absorbs impact energy. This compounding process results in a core-shell toughening agent that provides excellent toughening effects without excessively sacrificing the strength and hardness of the epoxy resin, achieving a balance between toughness and rigidity.

[0041] 3. This invention uses isocyanate-terminated polybutadiene prepolymer as a seed, coating its surface with a copolymerized acrylate shell to form a toughening agent with a "soft core-tough shell" structure. The flexible polybutadiene soft core absorbs and dissipates energy upon impact, thus providing toughening. The butyl acrylate segments in the shell provide suitable toughness and regulate the glass transition temperature, while glycidyl methacrylate provides epoxy functional groups that can chemically bond with the epoxy resin matrix. The core-shell toughening agent obtained by this invention not only achieves highly efficient toughening of epoxy resin but also ensures efficient transfer of the toughening effect through chemical bonding at the core-shell and shell-matrix interfaces, avoiding sacrifices in heat resistance and modulus. This synergistically achieves comprehensive performance with high impact resistance, excellent weather resistance, and high interfacial bonding strength. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the embodiments.

[0043] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0044] The key raw materials used in this invention are sourced from the following sources: Bisphenol A type epoxy resin: grade E20 (CYD-011), brand Baling Petrochemical, purchased from Shanghai Kaiyin Chemical Co., Ltd.

[0045] 4,5-Epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester: Grade TDE-85, brand Baling Petrochemical, purchased from Hubei Qibajiu Chemical Co., Ltd.

[0046] Hydroxyl-terminated polybutadiene: Product code HTPB-3000, number average molecular weight 3000 g / mol, hydroxyl value 0.71-0.80 mmol / g, water mass fraction ≤0.05%, purchased from Wuhan Kanos Technology Co., Ltd.

[0047] Isophorone diisocyanate: Brand: Senfida, purchased from Suzhou Senfida Chemical Co., Ltd.

[0048] 4,4-Diisocyanate dicyclohexylmethane: Brand: Senfida, purchased from Suzhou Senfida Chemical Co., Ltd.

[0049] Glycidyl methacrylate: Brand: Huijinchuan, purchased from Jinan Huijinchuan Chemical Co., Ltd.

[0050] Butyl acrylate: Brand: Huijinchuan, purchased from Jinan Huijinchuan Chemical Co., Ltd.

[0051] Polyethylene glycol diglycidyl ether: Product No. 202250, Brand: Suihua, purchased from Shandong Suihua Biotechnology Co., Ltd.

[0052] Nano zinc oxide: Model VK-J20, particle size 20nm, brand Jinghe, purchased from Xuancheng Jingrui New Materials Co., Ltd.

[0053] Methyltetrahydrophthalic anhydride: anhydride content 40%, model JYS1541, brand Jiyesheng, purchased from Wuhan Jiyesheng Chemical Co., Ltd.

[0054] Triphenylethylphosphine bromide: Brand: Dali, purchased from Hubei Dali Chemical Co., Ltd.

[0055] Examples 1-3 provide an epoxy resin potting compound and its preparation method.

[0056] Example 1 An epoxy resin potting compound comprises the following raw materials in parts by weight: 40 parts epoxy resin matrix, 8 parts polyethylene glycol diglycidyl ether, 3 parts core-shell toughening agent, 40 parts nano zinc oxide, 12 parts methyltetrahydrophthalic anhydride, and 1 part triphenylethylphosphine bromide.

[0057] The epoxy resin matrix is ​​composed of bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester in a mass ratio of 7:1.

[0058] Core-shell toughening agents are prepared by the following methods: (1) The mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and dibutyltin dilaurate is controlled to be 95:160:0.08. The hydroxyl-terminated polybutadiene is added to the reactor and vacuum dehydrated for 3 hours at 105℃ and vacuum degree -0.1MPa until the moisture content is 0.02% to obtain pretreated hydroxyl-terminated polybutadiene. The temperature inside the reactor is reduced to 45℃, anhydrous toluene is added, and the mixture is stirred at 50rpm for 40min. Then, dibutyltin dilaurate is added and stirred for another 20min to obtain the pre-reaction system. (2) The amount of the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane added is 18% of the mass of hydroxyl-terminated polybutadiene, and the mass ratio of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is 1:1.2. The mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is added dropwise to the pre-reaction system. The temperature inside the reactor is strictly controlled within the range of 66-72℃ by adjusting the dropping rate in real time. After the dropping is completed, the temperature inside the reactor is raised to 78℃ and the reaction is kept at this temperature for 6 hours until the -NCO content in the system reaches the theoretical value. The reaction system is then cooled to 30℃ and filtered through a 100-mesh filter to obtain a polybutadiene solution with isocyanate end-capped. (3) The mass ratio of isocyanate-terminated polybutadiene solution to sodium dodecyl sulfate solution is controlled to be 1:2. The isocyanate-terminated polybutadiene solution is added to sodium dodecyl sulfate solution with a mass fraction of 1%. The ultrasonic power is controlled to be 300W and the ultrasonic frequency is 20kHz. The solution is ultrasonically treated for 30 minutes in an ice-water bath to obtain seed emulsion. The amount of the premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate added was controlled to be 19% of the mass of the seed emulsion, and the mass ratio of glycidyl methacrylate, butyl acrylate and potassium persulfate was 1:2.2:0.03. The premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate was added dropwise to the seed emulsion, and the addition was completed in 2 hours. After reacting at 65°C for 4 hours, the mixture was cooled to room temperature to obtain the core-shell toughening agent emulsion. (4) Control the stirring speed to 200 rpm, and the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution to 1:3. Under stirring, add the core-shell toughening agent emulsion to the calcium chloride solution at 70°C and a mass concentration of 5% to break the emulsion and precipitate the polymer particles. Use a microporous membrane with a pore size of 10 μm for vacuum filtration to obtain a filter cake. Wash the filter cake repeatedly with deionized water until the conductivity of the washing water is close to that of pure water. Place the washed filter cake in a vacuum oven at 60°C and dry it to constant weight to obtain the core-shell toughening agent.

[0059] A method for preparing an epoxy resin potting compound includes the following steps: S1. Epoxy resin matrix, polyethylene glycol diglycidyl ether, core-shell toughening agent and nano zinc oxide are stirred and mixed at 30°C and 800 rpm for 3 hours until uniformly mixed to obtain a mixture. S2. Add methyltetrahydrophthalic anhydride and triphenylethylphosphine bromide to the mixture, and continue stirring at 20°C and 200 rpm for 45 minutes until the mixture is uniform to obtain epoxy resin potting compound.

[0060] Example 2 An epoxy resin potting compound comprises the following raw materials in parts by weight: 45 parts epoxy resin matrix, 10 parts polyethylene glycol diglycidyl ether, 4.5 parts core-shell toughening agent, 43 parts nano zinc oxide, 14 parts methyltetrahydrophthalic anhydride, and 1.2 parts triphenylethylphosphine bromide.

[0061] The epoxy resin matrix is ​​composed of bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester in a mass ratio of 8:1.

[0062] Core-shell toughening agents are prepared by the following methods: (1) The mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and dibutyltin dilaurate is controlled to be 100:170:0.1. The hydroxyl-terminated polybutadiene is added to the reactor and vacuum dehydrated for 2.5 h at 110 °C and vacuum degree -0.095 MPa until the moisture content is 0.02% to obtain pretreated hydroxyl-terminated polybutadiene. The temperature inside the reactor is reduced to 50 °C, anhydrous toluene is added, and the mixture is stirred at 75 rpm for 35 min. Then, dibutyltin dilaurate is added and stirred for another 18 min to obtain the pre-reaction system. (2) The amount of the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane added is 19% of the mass of hydroxyl-terminated polybutadiene, and the mass ratio of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is 1:1.22. The mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is added dropwise to the pre-reaction system. The temperature inside the reactor is strictly controlled within the range of 66-72℃ by adjusting the dropping rate in real time. After the dropping is completed, the temperature inside the reactor is raised to 82℃ and the reaction is kept at this temperature for 5 hours until the -NCO content in the system reaches the theoretical value. The reaction system is then cooled to 35℃ and filtered through a 110-mesh filter to obtain a polybutadiene solution with isocyanate end-capped. (3) The mass ratio of isocyanate-terminated polybutadiene solution to sodium dodecyl sulfate solution was controlled to be 1:2.2. The isocyanate-terminated polybutadiene solution was added to sodium dodecyl sulfate solution with a mass fraction of 1.3%. The ultrasonic power was controlled to be 400W and the ultrasonic frequency to be 22kHz. The solution was ultrasonically treated for 18 minutes in an ice-water bath to obtain seed emulsion. The amount of the premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate added was controlled to be 21% of the mass of the seed emulsion, and the mass ratio of glycidyl methacrylate, butyl acrylate and potassium persulfate was 1:2.4:0.035. The premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate was added dropwise to the seed emulsion, and the addition was completed in 2.5 h. After reacting at 70 °C for 3.5 h, the mixture was cooled to room temperature to obtain the core-shell toughening agent emulsion. (4) Control the stirring speed to 300 rpm, and the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution to 1:4. Under stirring, add the core-shell toughening agent emulsion to the calcium chloride solution at 75°C and a mass concentration of 3% to break the emulsion and precipitate the polymer particles. Use a microporous membrane with a pore size of 20 μm for vacuum filtration to obtain a filter cake. Wash the filter cake repeatedly with deionized water until the conductivity of the washing water is close to that of pure water. Place the washed filter cake in a vacuum oven at 65°C and dry it to constant weight to obtain the core-shell toughening agent.

[0063] A method for preparing an epoxy resin potting compound includes the following steps: S1. Epoxy resin matrix, polyethylene glycol diglycidyl ether, core-shell toughening agent and nano zinc oxide are stirred and mixed at 35°C and 1000 rpm for 2.5 hours until uniformly mixed to obtain a mixture. S2. Add methyltetrahydrophthalic anhydride and triphenylethylphosphine bromide to the mixture, and continue stirring at 300 rpm for 38 minutes at 25°C until the mixture is uniform, to obtain epoxy resin potting compound.

[0064] Example 3 An epoxy resin potting compound comprises the following raw materials in parts by weight: 50 parts epoxy resin matrix, 12 parts polyethylene glycol diglycidyl ether, 6 parts core-shell toughening agent, 45 parts nano zinc oxide, 16 parts methyltetrahydrophthalic anhydride, and 1.5 parts triphenylethylphosphine bromide.

[0065] The epoxy resin matrix is ​​composed of bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester in a mass ratio of 9:1.

[0066] Core-shell toughening agents are prepared by the following methods: (1) The mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and dibutyltin dilaurate is controlled to be 105:180:0.12. The hydroxyl-terminated polybutadiene is added to the reactor and vacuum dehydrated for 2 hours at 115℃ and vacuum degree -0.095MPa until the moisture content is 0.03% to obtain pretreated hydroxyl-terminated polybutadiene. The temperature inside the reactor is reduced to 55℃, anhydrous toluene is added, and the mixture is stirred at 100rpm for 30min. Then, dibutyltin dilaurate is added and stirred for another 15min to obtain the pre-reaction system. (2) The amount of the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane added is 20% of the mass of hydroxyl-terminated polybutadiene, and the mass ratio of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is 1:1.25. The mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is added dropwise to the pre-reaction system. The temperature inside the reactor is strictly controlled within the range of 66-72℃ by adjusting the dropping rate in real time. After the dropping is completed, the temperature inside the reactor is raised to 85℃ and kept at the temperature for 4 hours until the -NCO content in the system reaches the theoretical value. The reaction system is cooled to 40℃ and filtered through a 100-mesh filter to obtain a polybutadiene solution with isocyanate end-capped. (3) The mass ratio of isocyanate-terminated polybutadiene solution to sodium dodecyl sulfate solution is controlled to be 1:2.5. The isocyanate-terminated polybutadiene solution is added to sodium dodecyl sulfate solution with a mass fraction of 1.5%. The ultrasonic power is controlled to be 500W and the ultrasonic frequency is 25kHz. The solution is ultrasonically treated for 15min in an ice-water bath to obtain seed emulsion. The amount of the premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate added was controlled to be 23% of the mass of the seed emulsion, and the mass ratio of glycidyl methacrylate, butyl acrylate and potassium persulfate was 1:2.6:0.04. The premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate was added dropwise to the seed emulsion, and the addition was completed in 3 hours. After reacting at 75°C for 3 hours, the mixture was cooled to room temperature to obtain the core-shell toughening agent emulsion. (4) Control the stirring speed to 400 rpm, and the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution to 1:5. Under stirring, add the core-shell toughening agent emulsion to the calcium chloride solution at 80℃ and a mass concentration of 1% to break the emulsion and precipitate the polymer particles. Use a microporous membrane with a pore size of 30 μm for vacuum filtration to obtain a filter cake. Wash the filter cake repeatedly with deionized water until the conductivity of the washing water is close to that of pure water. Place the washed filter cake in a vacuum oven at 70℃ and dry it to constant weight to obtain the core-shell toughening agent.

[0067] A method for preparing an epoxy resin potting compound includes the following steps: S1. Epoxy resin matrix, polyethylene glycol diglycidyl ether, core-shell toughening agent and nano zinc oxide are stirred and mixed at 40°C and 1200 rpm for 2 hours until uniformly mixed to obtain a mixture. S2. Add methyltetrahydrophthalic anhydride and triphenylethylphosphine bromide to the mixture, and continue stirring at 30°C and 400 rpm for 30 minutes until the mixture is uniform to obtain epoxy resin potting compound.

[0068] To verify the comprehensive performance of the epoxy resin potting compound provided by the present invention, comparative examples 1-5 were set up, wherein: Comparative Example 1 Comparative Example 1 is the same as Example 1, except that the epoxy resin matrix is ​​only bisphenol A type epoxy resin. Details are as follows: An epoxy resin potting compound comprises the following raw materials in parts by weight: 40 parts of bisphenol A type epoxy resin, 8 parts of polyethylene glycol diglycidyl ether, 3 parts of core-shell toughening agent, 40 parts of nano zinc oxide, 12 parts of methyltetrahydrophthalic anhydride, and 1 part of triphenylethylphosphine bromide.

[0069] The core-shell toughening agent is prepared by the following method: (1) The mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and dibutyltin dilaurate is controlled to be 95:160:0.08. The hydroxyl-terminated polybutadiene is added to the reactor and vacuum dehydrated for 3 hours at 105℃ and vacuum degree -0.1MPa until the moisture content is 0.02% to obtain pretreated hydroxyl-terminated polybutadiene. The temperature inside the reactor is reduced to 45℃, anhydrous toluene is added, and the mixture is stirred at 50rpm for 40min. Then, dibutyltin dilaurate is added and stirred for another 20min to obtain the pre-reaction system. (2) The amount of the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane added is 18% of the mass of hydroxyl-terminated polybutadiene, and the mass ratio of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is 1:1.2. The mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is added dropwise to the pre-reaction system. The temperature inside the reactor is strictly controlled within the range of 66-72℃ by adjusting the dropping rate in real time. After the dropping is completed, the temperature inside the reactor is raised to 78℃ and the reaction is kept at this temperature for 6 hours until the -NCO content in the system reaches the theoretical value. The reaction system is then cooled to 30℃ and filtered through a 100-mesh filter to obtain a polybutadiene solution with isocyanate end-capped. (3) The mass ratio of isocyanate-terminated polybutadiene solution to sodium dodecyl sulfate solution is controlled to be 1:2. The isocyanate-terminated polybutadiene solution is added to sodium dodecyl sulfate solution with a mass fraction of 1%. The ultrasonic power is controlled to be 300W and the ultrasonic frequency is 20kHz. The solution is ultrasonically treated for 30 minutes in an ice-water bath to obtain seed emulsion. The amount of the premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate added was controlled to be 19% of the mass of the seed emulsion, and the mass ratio of glycidyl methacrylate, butyl acrylate and potassium persulfate was 1:2.2:0.03. The premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate was added dropwise to the seed emulsion, and the addition was completed in 2 hours. After reacting at 65°C for 4 hours, the mixture was cooled to room temperature to obtain the core-shell toughening agent emulsion. (4) Control the stirring speed to 200 rpm, and the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution to 1:3. Under stirring, add the core-shell toughening agent emulsion to the calcium chloride solution at 70°C and a mass concentration of 5% to break the emulsion and precipitate the polymer particles. Use a microporous membrane with a pore size of 10 μm for vacuum filtration to obtain a filter cake. Wash the filter cake repeatedly with deionized water until the conductivity of the washing water is close to that of pure water. Place the washed filter cake in a vacuum oven at 60°C and dry it to constant weight to obtain the core-shell toughening agent.

[0070] A method for preparing an epoxy resin potting compound includes the following steps: S1. Bisphenol A type epoxy resin, polyethylene glycol diglycidyl ether, core-shell structure toughening agent and nano zinc oxide are stirred and mixed at 30°C and 800 rpm for 3 hours until uniformly mixed to obtain a mixture. S2. Add methyltetrahydrophthalic anhydride and triphenylethylphosphine bromide to the mixture, and continue stirring at 20°C and 200 rpm for 45 minutes until the mixture is uniform to obtain epoxy resin potting compound.

[0071] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is replaced by isophorone diisocyanate in equal mass. Specifically: An epoxy resin potting compound comprises the following raw materials in parts by weight: 40 parts epoxy resin matrix, 8 parts polyethylene glycol diglycidyl ether, 3 parts core-shell toughening agent, 40 parts nano zinc oxide, 12 parts methyltetrahydrophthalic anhydride, and 1 part triphenylethylphosphine bromide.

[0072] The epoxy resin matrix is ​​composed of bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester in a mass ratio of 7:1.

[0073] Core-shell toughening agents are prepared by the following methods: (1) The mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and dibutyltin dilaurate is controlled to be 95:160:0.08. The hydroxyl-terminated polybutadiene is added to the reactor and vacuum dehydrated for 3 hours at 105℃ and vacuum degree -0.1MPa until the moisture content is 0.02% to obtain pretreated hydroxyl-terminated polybutadiene. The temperature inside the reactor is reduced to 45℃, anhydrous toluene is added, and the mixture is stirred at 50rpm for 40min. Then, dibutyltin dilaurate is added and stirred for another 20min to obtain the pre-reaction system. (2) The amount of isophorone diisocyanate added is controlled to be 18% of the mass of hydroxyl-terminated polybutadiene. The isophorone diisocyanate is added dropwise to the pre-reaction system. The temperature inside the reactor is strictly controlled to be maintained within the range of 66-72℃ by adjusting the dropping rate in real time. After the dropping is completed, the temperature inside the reactor is raised to 78℃ and the reaction is kept at this temperature for 6 hours until the -NCO content in the system reaches the theoretical value. The reaction system is cooled to 30℃ and filtered through a 100-mesh filter to obtain a polybutadiene solution with isocyanate end-capped. (3) The mass ratio of isocyanate-terminated polybutadiene solution to sodium dodecyl sulfate solution is controlled to be 1:2. The isocyanate-terminated polybutadiene solution is added to sodium dodecyl sulfate solution with a mass fraction of 1%. The ultrasonic power is controlled to be 300W and the ultrasonic frequency is 20kHz. The solution is ultrasonically treated for 30 minutes in an ice-water bath to obtain seed emulsion. The amount of the premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate added was controlled to be 19% of the mass of the seed emulsion, and the mass ratio of glycidyl methacrylate, butyl acrylate and potassium persulfate was 1:2.2:0.03. The premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate was added dropwise to the seed emulsion, and the addition was completed in 2 hours. After reacting at 65°C for 4 hours, the mixture was cooled to room temperature to obtain the core-shell toughening agent emulsion. (4) Control the stirring speed to 200 rpm, and the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution to 1:3. Under stirring, add the core-shell toughening agent emulsion to the calcium chloride solution at 70°C and a mass concentration of 5% to break the emulsion and precipitate the polymer particles. Use a microporous membrane with a pore size of 10 μm for vacuum filtration to obtain a filter cake. Wash the filter cake repeatedly with deionized water until the conductivity of the washing water is close to that of pure water. Place the washed filter cake in a vacuum oven at 60°C and dry it to constant weight to obtain the core-shell toughening agent.

[0074] A method for preparing an epoxy resin potting compound includes the following steps: S1. Epoxy resin matrix, polyethylene glycol diglycidyl ether, core-shell toughening agent and nano zinc oxide are stirred and mixed at 30°C and 800 rpm for 3 hours until uniformly mixed to obtain a mixture. S2. Add methyltetrahydrophthalic anhydride and triphenylethylphosphine bromide to the mixture, and continue stirring at 20°C and 200 rpm for 45 minutes until the mixture is uniform to obtain epoxy resin potting compound.

[0075] Comparative Example 3 Comparative Example 3 is the same as Example 1, except that the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is replaced by 4,4-diisocyanate dicyclohexylmethane in equal mass. Specifically: An epoxy resin potting compound comprises the following raw materials in parts by weight: 40 parts epoxy resin matrix, 8 parts polyethylene glycol diglycidyl ether, 3 parts core-shell toughening agent, 40 parts nano zinc oxide, 12 parts methyltetrahydrophthalic anhydride, and 1 part triphenylethylphosphine bromide.

[0076] The epoxy resin matrix is ​​composed of bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester in a mass ratio of 7:1.

[0077] Core-shell toughening agents are prepared by the following methods: (1) The mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and dibutyltin dilaurate is controlled to be 95:160:0.08. The hydroxyl-terminated polybutadiene is added to the reactor and vacuum dehydrated for 3 hours at 105℃ and vacuum degree -0.1MPa until the moisture content is 0.02% to obtain pretreated hydroxyl-terminated polybutadiene. The temperature inside the reactor is reduced to 45℃, anhydrous toluene is added, and the mixture is stirred at 50rpm for 40min. Then, dibutyltin dilaurate is added and stirred for another 20min to obtain the pre-reaction system. (2) The amount of 4,4-diisocyanate dicyclohexylmethane added is controlled to be 18% of the mass of hydroxyl-terminated polybutadiene. 4,4-diisocyanate dicyclohexylmethane is added dropwise to the pre-reaction system. The temperature inside the reactor is strictly controlled to be maintained in the range of 66-72℃ by adjusting the dropping rate in real time. After the dropping is completed, the temperature inside the reactor is raised to 78℃ and the reaction is kept at this temperature for 6 hours until the -NCO content in the system reaches the theoretical value. The reaction system is cooled to 30℃ and filtered through a 100-mesh filter to obtain a polybutadiene solution with isocyanate end-capped. (3) The mass ratio of isocyanate-terminated polybutadiene solution to sodium dodecyl sulfate solution is controlled to be 1:2. The isocyanate-terminated polybutadiene solution is added to sodium dodecyl sulfate solution with a mass fraction of 1%. The ultrasonic power is controlled to be 300W and the ultrasonic frequency is 20kHz. The solution is ultrasonically treated for 30 minutes in an ice-water bath to obtain seed emulsion. The amount of the premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate added was controlled to be 19% of the mass of the seed emulsion, and the mass ratio of glycidyl methacrylate, butyl acrylate and potassium persulfate was 1:2.2:0.03. The premixture of glycidyl methacrylate, butyl acrylate and potassium persulfate was added dropwise to the seed emulsion, and the addition was completed in 2 hours. After reacting at 65°C for 4 hours, the mixture was cooled to room temperature to obtain the core-shell toughening agent emulsion. (4) Control the stirring speed to 200 rpm, and the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution to 1:3. Under stirring, add the core-shell toughening agent emulsion to the calcium chloride solution at 70°C and a mass concentration of 5% to break the emulsion and precipitate the polymer particles. Use a microporous membrane with a pore size of 10 μm for vacuum filtration to obtain a filter cake. Wash the filter cake repeatedly with deionized water until the conductivity of the washing water is close to that of pure water. Place the washed filter cake in a vacuum oven at 60°C and dry it to constant weight to obtain the core-shell toughening agent.

[0078] A method for preparing an epoxy resin potting compound includes the following steps: S1. Epoxy resin matrix, polyethylene glycol diglycidyl ether, core-shell toughening agent and nano zinc oxide are stirred and mixed at 30°C and 800 rpm for 3 hours until uniformly mixed to obtain a mixture. S2. Add methyltetrahydrophthalic anhydride and triphenylethylphosphine bromide to the mixture, and continue stirring at 20°C and 200 rpm for 45 minutes until the mixture is uniform to obtain epoxy resin potting compound.

[0079] Comparative Example 4 Comparative Example 4 is the same as Example 1, except that butyl acrylate is replaced by glycidyl methacrylate in equal quantities. Details are as follows: An epoxy resin potting compound comprises the following raw materials in parts by weight: 40 parts epoxy resin matrix, 8 parts polyethylene glycol diglycidyl ether, 3 parts core-shell toughening agent, 40 parts nano zinc oxide, 12 parts methyltetrahydrophthalic anhydride, and 1 part triphenylethylphosphine bromide.

[0080] The epoxy resin matrix is ​​composed of bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester in a mass ratio of 7:1.

[0081] Core-shell toughening agents are prepared by the following methods: (1) The mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and dibutyltin dilaurate is controlled to be 95:160:0.08. The hydroxyl-terminated polybutadiene is added to the reactor and vacuum dehydrated for 3 hours at 105℃ and vacuum degree -0.1MPa until the moisture content is 0.02% to obtain pretreated hydroxyl-terminated polybutadiene. The temperature inside the reactor is reduced to 45℃, anhydrous toluene is added, and the mixture is stirred at 50rpm for 40min. Then, dibutyltin dilaurate is added and stirred for another 20min to obtain the pre-reaction system. (2) The amount of the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane added is 18% of the mass of hydroxyl-terminated polybutadiene, and the mass ratio of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is 1:1.2. The mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is added dropwise to the pre-reaction system. The temperature inside the reactor is strictly controlled within the range of 66-72℃ by adjusting the dropping rate in real time. After the dropping is completed, the temperature inside the reactor is raised to 78℃ and the reaction is kept at this temperature for 6 hours until the -NCO content in the system reaches the theoretical value. The reaction system is then cooled to 30℃ and filtered through a 100-mesh filter to obtain a polybutadiene solution with isocyanate end-capped. (3) The mass ratio of isocyanate-terminated polybutadiene solution to sodium dodecyl sulfate solution is controlled to be 1:2. The isocyanate-terminated polybutadiene solution is added to sodium dodecyl sulfate solution with a mass fraction of 1%. The ultrasonic power is controlled to be 300W and the ultrasonic frequency is 20kHz. The solution is ultrasonically treated for 30 minutes in an ice-water bath to obtain seed emulsion. The amount of the premixture of glycidyl methacrylate and potassium persulfate added was controlled to be 19% of the mass of the seed emulsion, and the mass ratio of glycidyl methacrylate to potassium persulfate was 3.2:0.03. The premixture of glycidyl methacrylate and potassium persulfate was added dropwise to the seed emulsion, and the addition was completed in 2 hours. After reacting at 65°C for 4 hours, the mixture was cooled to room temperature to obtain the core-shell toughening agent emulsion. (4) Control the stirring speed to 200 rpm, and the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution to 1:3. Under stirring, add the core-shell toughening agent emulsion to the calcium chloride solution at 70°C and a mass concentration of 5% to break the emulsion and precipitate the polymer particles. Use a microporous membrane with a pore size of 10 μm for vacuum filtration to obtain a filter cake. Wash the filter cake repeatedly with deionized water until the conductivity of the washing water is close to that of pure water. Place the washed filter cake in a vacuum oven at 60°C and dry it to constant weight to obtain the core-shell toughening agent.

[0082] A method for preparing an epoxy resin potting compound includes the following steps: S1. Epoxy resin matrix, polyethylene glycol diglycidyl ether, core-shell toughening agent and nano zinc oxide are stirred and mixed at 30°C and 800 rpm for 3 hours until uniformly mixed to obtain a mixture. S2. Add methyltetrahydrophthalic anhydride and triphenylethylphosphine bromide to the mixture, and continue stirring at 20°C and 200 rpm for 45 minutes until the mixture is uniform to obtain epoxy resin potting compound.

[0083] Comparative Example 5 Comparative Example 5 is the same as Example 1, except that glycidyl methacrylate is replaced by butyl acrylate in equal mass. Details are as follows: An epoxy resin potting compound comprises the following raw materials in parts by weight: 40 parts epoxy resin matrix, 8 parts polyethylene glycol diglycidyl ether, 3 parts core-shell toughening agent, 40 parts nano zinc oxide, 12 parts methyltetrahydrophthalic anhydride, and 1 part triphenylethylphosphine bromide.

[0084] The epoxy resin matrix is ​​composed of bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester in a mass ratio of 7:1.

[0085] Core-shell toughening agents are prepared by the following methods: (1) The mass ratio of hydroxyl-terminated polybutadiene, anhydrous toluene and dibutyltin dilaurate is controlled to be 95:160:0.08. The hydroxyl-terminated polybutadiene is added to the reactor and vacuum dehydrated for 3 hours at 105℃ and vacuum degree -0.1MPa until the moisture content is 0.02% to obtain pretreated hydroxyl-terminated polybutadiene. The temperature inside the reactor is reduced to 45℃, anhydrous toluene is added, and the mixture is stirred at 50rpm for 40min. Then, dibutyltin dilaurate is added and stirred for another 20min to obtain the pre-reaction system. (2) The amount of the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane added is 18% of the mass of hydroxyl-terminated polybutadiene, and the mass ratio of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is 1:1.2. The mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane is added dropwise to the pre-reaction system. The temperature inside the reactor is strictly controlled within the range of 66-72℃ by adjusting the dropping rate in real time. After the dropping is completed, the temperature inside the reactor is raised to 78℃ and the reaction is kept at this temperature for 6 hours until the -NCO content in the system reaches the theoretical value. The reaction system is then cooled to 30℃ and filtered through a 100-mesh filter to obtain a polybutadiene solution with isocyanate end-capped. (3) The mass ratio of isocyanate-terminated polybutadiene solution to sodium dodecyl sulfate solution is controlled to be 1:2. The isocyanate-terminated polybutadiene solution is added to sodium dodecyl sulfate solution with a mass fraction of 1%. The ultrasonic power is controlled to be 300W and the ultrasonic frequency is 20kHz. The solution is ultrasonically treated for 30 minutes in an ice-water bath to obtain seed emulsion. The amount of the premixture of butyl acrylate and potassium persulfate added was controlled to be 19% of the mass of the seed emulsion, and the mass ratio of butyl acrylate to potassium persulfate was 3.2:0.03. The premixture of butyl acrylate and potassium persulfate was added dropwise to the seed emulsion, and the addition was completed in 2 hours. After reacting at 65°C for 4 hours, the mixture was cooled to room temperature to obtain the core-shell toughening agent emulsion. (4) Control the stirring speed to 200 rpm, and the volume ratio of the core-shell toughening agent emulsion to the calcium chloride solution to 1:3. Under stirring, add the core-shell toughening agent emulsion to the calcium chloride solution at 70°C and a mass concentration of 5% to break the emulsion and precipitate the polymer particles. Use a microporous membrane with a pore size of 10 μm for vacuum filtration to obtain a filter cake. Wash the filter cake repeatedly with deionized water until the conductivity of the washing water is close to that of pure water. Place the washed filter cake in a vacuum oven at 60°C and dry it to constant weight to obtain the core-shell toughening agent.

[0086] A method for preparing an epoxy resin potting compound includes the following steps: S1. Epoxy resin matrix, polyethylene glycol diglycidyl ether, core-shell toughening agent and nano zinc oxide are stirred and mixed at 30°C and 800 rpm for 3 hours until uniformly mixed to obtain a mixture. S2. Add methyltetrahydrophthalic anhydride and triphenylethylphosphine bromide to the mixture, and continue stirring at 20°C and 200 rpm for 45 minutes until the mixture is uniform to obtain epoxy resin potting compound.

[0087] The comprehensive performance of the epoxy resin potting compounds prepared in Examples 1-3 and Comparative Examples 1-5 of this invention was tested respectively.

[0088] Test samples: The epoxy resin potting compounds prepared in Examples 1-3 and Comparative Examples 1-5 were vacuum degassed and then cast into molds. The curing conditions were controlled as follows: 80℃ / 2h + 120℃ / 4h. After complete curing, test samples were prepared according to the following standards and their performance was tested. Five samples were tested in each group, and the average value of the results was taken.

[0089] Tensile strength: Tested in accordance with the national standard GB / T 1040-2006 "Determination of tensile properties of plastics" at a test speed of 50 mm / min.

[0090] Notched impact strength: Tested in accordance with national standard GB / T 1043.1-2008 "Determination of impact properties of simply supported plastic beams".

[0091] Corrosion resistance: The test was conducted in accordance with Appendix A5 of ASTM G85-19, "Standard Implementation Procedure for Modified Salt Spray Test", and the time when signs of corrosion such as blistering and cracking appeared on the sample surface was recorded.

[0092] Weather resistance: Artificial accelerated aging treatment was conducted according to the national standard GB / T 14522-2008 "Artificial Climate Aging Test Method for Plastics, Coatings and Rubber Materials for Mechanical Industry Products - Fluorescent Ultraviolet Lamp". Specific conditions were as follows: a UVB-313 ultraviolet lamp was used, with a cycle of 4 hours of ultraviolet irradiation at 60℃, followed by 4 hours of ultraviolet irradiation plus water spraying, for a total aging time of 168 hours. The notched impact strength was then tested, and the notched impact strength retention rate was calculated.

[0093] Volume resistivity: Tested in accordance with the national standard GB / T 1410-2006 "Test methods for volume resistivity and surface resistivity of solid insulating materials".

[0094] The test results are shown in Table 1: Table 1: Comprehensive performance test data of epoxy resin potting compounds in Examples 1-3 and Comparative Examples 1-5 As shown in Table 1, the epoxy resin potting compounds prepared in Examples 1-3 of this invention all exhibit excellent comprehensive performance. While maintaining high tensile strength, they also achieve extremely high notched impact strength, excellent corrosion resistance and weather resistance, and maintain excellent electrical insulation properties. Their comprehensive performance is significantly better than that of Comparative Examples 1-5.

[0095] As shown in Example 1 and Comparative Example 1, Comparative Example 1, which uses only bisphenol A type epoxy resin as the matrix, exhibits significantly reduced notched impact strength, corrosion resistance, and aging resistance. This fully demonstrates that compounding bisphenol A type epoxy resin with diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylic acid can significantly improve the toughness, corrosion resistance, and weather resistance of the potting compound.

[0096] As shown in Examples 1 and Comparative Examples 2 and 3: Comparative Example 2 used only isophorone diisocyanate as the end-capping agent for the toughening prepolymer. Although the tensile strength was improved, its notched impact strength was significantly reduced, and the potting compound exhibited obvious brittleness. Comparative Example 3 used only 4,4-diisocyanate dicyclohexylmethane as the end-capping agent for the toughening prepolymer. The notched impact strength was significantly improved, but the tensile strength decreased, the material was too soft, and the rigidity was insufficient. Example 1, by combining isophorone diisocyanate and 4,4-diisocyanate dicyclohexylmethane, achieved a "rigid-toughness balance" in terms of tensile strength and notched impact strength, demonstrating a significant synergistic effect.

[0097] As shown in Examples 1 and Comparative Examples 4 and 5, the core-shell toughening agent of Comparative Example 4 does not contain the flexible monomer butyl acrylate in its shell layer, resulting in an overly rigid shell layer and a significant reduction in the notched impact strength of the final product. The core-shell toughening agent of Comparative Example 5 does not contain glycidyl methacrylate with epoxy functional groups in its shell layer, preventing the toughening agent particles from forming effective chemical bonds with the epoxy matrix, thus significantly reducing its overall performance.

[0098] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. An epoxy resin potting compound, characterized by, The epoxy resin base is compounded by bisphenol A type epoxy resin and 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester with a mass ratio of 7-9:

1. The core-shell structure toughening agent is prepared by the following method:

2. The epoxy potting compound according to claim 1, wherein (1) vacuum dehydration of hydroxyl-terminated polybutadiene to obtain pretreated hydroxyl-terminated polybutadiene, then adding anhydrous toluene and stirring, then adding a catalyst and continuing to stir, to obtain a pre-reaction system; (2) adding a mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexyl methane to the pre-reaction system, after the dropwise addition is completed, reacting until the -NCO content in the system reaches the theoretical value, cooling and filtering to obtain an isocyanate-terminated polybutadiene solution; (3) adding the isocyanate-terminated polybutadiene solution to an emulsifying system and ultrasonic treatment to obtain a seed emulsion, then adding a premix of glycidyl methacrylate, butyl acrylate and an initiator to the seed emulsion, controlling the dropwise addition to be completed in 2-3 hours, then reacting, and cooling to room temperature to obtain a core-shell structure toughening agent emulsion; (4) under stirring, adding the core-shell structure toughening agent emulsion to a calcium chloride solution to cause the core-shell structure toughening agent emulsion to demulsify, and the polymer particles to coagulate and precipitate, then vacuum filtration, washing and drying to obtain the core-shell structure toughening agent. In step (1), the mass ratio of the hydroxyl-terminated polybutadiene, anhydrous toluene and the catalyst is 95-105:160-180:0.08-0.

12.

3. The epoxy potting compound according to claim 2, wherein In step (2), the mixture of isophorone diisocyanate and 4,4-diisocyanate dicyclohexyl methane is added in an amount of 18-20% of the mass of the hydroxyl-terminated polybutadiene.

4. The epoxy potting compound of claim 2, wherein In step (2), the mass ratio of isophorone diisocyanate to 4,4-diisocyanate dicyclohexyl methane in the mixture is 1:1.2-1.

25.

5. The epoxy potting compound of claim 2, wherein In step (2), the temperature in the kettle is strictly controlled to be maintained in the range of 66-72°C during the dropwise addition.

6. The epoxy potting compound of claim 2, wherein In step (3), the mass ratio of the isocyanate-terminated polybutadiene solution to the emulsifying system is 1:2-2.

5.

7. The epoxy potting compound of claim 2, wherein In step (3), the premix of glycidyl methacrylate, butyl acrylate and the initiator is added in an amount of 19-23% of the mass of the seed emulsion.

8. The epoxy potting compound of claim 2, wherein, In step (3), the mass ratio of glycidyl methacrylate, butyl acrylate and the initiator in the premix is 1:2.2-2.6:0.03-0.

04.

9. The epoxy potting compound of claim 2, wherein, The method comprises the following steps:

10. A method of preparing the epoxy resin potting compound according to any one of claims 1 to 9, characterized in that S1, mixing and stirring the epoxy resin base, the active diluent, the core-shell structure toughening agent and the nano filler uniformly to obtain a mixture; S2, adding the curing agent and the curing accelerator to the mixture and continuing to stir uniformly to obtain the epoxy resin pouring sealant. ​

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