Epoxy resin-based nano composite insulating material and preparation method thereof

Abstract

The invention relates to an epoxy resin-based nano composite insulating material and a preparation method thereof. The material comprises modified epoxy resin, nano filler, a surfactant, a curing agent, an amphiphilic interface coupling agent, tridecafluorooctyltrimethoxysilane, methyl nadic anhydride and an accelerant. The modified epoxy resin is prepared by reacting bisphenol A epoxy resin with methyldimethoxysilane and an imide oligomer; the preparation method comprises the following steps: carrying out a special pretreatment process on the nano filler, and carrying out surface modification on the nano filler by adopting 11-mercaptoundecyltrimethoxysilane and a polyimide siloxane copolymer; the preparation method comprises the steps of nano filler dispersion, material mixing, graded curing treatment and the like. Through molecular structure design and interface regulation and control, the problem that the insulating property of a traditional epoxy resin insulating material is reduced in a high-temperature and high-pressure environment is solved, the dielectric strength and thermal stability of the material are improved, and the epoxy resin insulating material is suitable for an insulating system of high-voltage electrical equipment.

Description

Technical Field

[0001] This invention relates to the field of insulating materials technology, specifically to an epoxy resin-based nanocomposite insulating material and its preparation method. Background Technology

[0002] Epoxy resin-based nanocomposite insulating materials are widely used in power equipment, electronic components, and aerospace due to their excellent electrical insulation properties, mechanical strength, and thermal stability. As electrical equipment develops towards high voltage, large capacity, miniaturization, and intelligence, the performance requirements for insulating materials are becoming increasingly stringent.

[0003] Traditional epoxy resin-based insulating materials are prone to degradation in insulation performance and mechanical strength under harsh environments such as high temperature, high humidity, and strong electric fields. To improve the overall performance of epoxy resin-based insulating materials, researchers have begun to introduce nanofillers into the epoxy resin matrix to prepare nanocomposite insulating materials. CN105647120B discloses an epoxy resin-based nonlinear adaptive nanocomposite insulating material composed of epoxy resin, nano-silicon carbide, and nano-zinc oxide, exhibiting excellent nonlinear conductivity and low brittleness. CN105860437A proposes a micro-nano modified epoxy-based high-temperature resistant and thermally conductive insulating composite material. By modifying the basic epoxy system with multifunctional resins and thermally conductive fillers, its temperature resistance and thermal conductivity are improved.

[0004] However, due to the polarity difference between epoxy resin and nanofillers, the nanofillers exhibit poor dispersion in the epoxy resin matrix, easily leading to agglomeration and affecting the overall performance of the composite material. CN107286586B discloses an anti-settling micro-nano composite insulating material and its preparation method. By using a silane coupling agent to surface-treat the micro-nano fillers and adding an anti-settling agent, the dispersion of filler particles in the epoxy resin matrix is ​​improved, reducing the sedimentation problem of fillers during the preparation process.

[0005] To further improve the performance of epoxy resin-based nanocomposite insulating materials, researchers have begun to functionalize epoxy resins. CN113831559A discloses a method for improving the interfacial adhesion of epoxy resin-based composite materials. This method achieves functionalization of the epoxy resin by linking it to organosilicon and a novel imide oligomer, thereby improving the interfacial adhesion of the composite material. CN112250993A provides an alicyclic epoxy resin insulating material. By combining epoxy resin, anhydride curing agents, and amine accelerators, and incorporating coupling agent-modified nano-alumina and coupling agent-modified nano-silica as nanocomposite materials, it significantly improves the insulation material's resistance to damp heat and UV aging.

[0006] Despite some progress in epoxy resin-based nanocomposite insulation materials, the following problems remain: First, the poor compatibility between epoxy resin and nanofillers limits the improvement of the overall performance of the composite material. Second, the nanofillers have insufficient dispersibility and interfacial bonding in epoxy resin, especially prone to agglomeration under humid and hot environments, leading to a decrease in the barrier properties of the composite material. Third, epoxy resin has poor high-temperature resistance and toughness, easily generating microcracks under long-term stress concentration, causing charge accumulation and the formation of electrical trees, ultimately leading to insulation breakdown. Fourth, existing nanofiller preparation processes have room for optimization, making it difficult to guarantee the yield and purity of nanofillers, thus affecting the overall performance of the composite material. Finally, the structural and performance optimization of epoxy resin and curing agents still needs improvement, making it difficult to obtain superior barrier and mechanical properties.

[0007] Therefore, there is an urgent need to develop an epoxy resin-based nanocomposite insulating material. By improving the compatibility between epoxy resin and nanofillers, enhancing the dispersibility and interfacial bonding of nanofillers, and strengthening the high-temperature resistance and toughness of epoxy resin, an insulating material with excellent comprehensive performance can be obtained. Summary of the Invention

[0008] To address the issues of poor compatibility due to the large polarity difference between epoxy resin and nanofillers, as well as the insufficient dispersibility and interfacial bonding of nanofillers in epoxy resin, poor high-temperature resistance and toughness of epoxy resin, room for optimization in the preparation process of nanofillers, and the need for further improvement in the structure and performance optimization of epoxy resin and curing agent, this invention provides an epoxy resin-based nanocomposite insulating material and its preparation method.

[0009] The objective of this invention is achieved through the following technical solution: an epoxy resin-based nanocomposite insulating material, comprising the following raw materials in parts by weight: 60-100 parts modified epoxy resin, 4-12 parts nanofiller, 1-3 parts surfactant, 1-5 parts curing agent, 0.6-1.2 parts amphiphilic interface coupling agent, 0.5-1.0 parts tridecafluorooctyltrimethoxysilane, 7-10 parts methylnadic anhydride, and 0.8-1.2 parts accelerator.

[0010] The epoxy resin-based nanocomposite insulating material of this invention effectively solves the problem of poor compatibility caused by the large polarity difference between epoxy resin and nanofillers by constructing a multifunctional interface structure system, significantly improving the interfacial bonding force between epoxy resin and nanofillers, with an improvement rate of over 40%. The preparation method of functionalized modified epoxy resin enables the modified epoxy resin to have good wettability and affinity for nanofillers, improving the dispersibility of nanofillers in the epoxy resin matrix. Through ultrasonic-shear composite dispersion technology, the dispersion degree of nanofillers can be improved by 30-50%. A gradient polarity interface transition layer is designed by constructing a self-assembled molecular monolayer on the surface of the nanofillers. The membrane forms a smooth transition from epoxy resin to nanofiller, achieving a smooth transition of polarity and effectively reducing the polarity difference between epoxy resin and nanofiller. The molecular structure of the interface coupling agent is optimized so that one end is affinity for epoxy resin and the other end is affinity for nanofiller, forming a stable bridging structure and further enhancing the interfacial bonding force. A hydrophobic fluorosilane modified layer is introduced into the interface structure design to form a dense hydrophobic protective membrane, effectively blocking water molecules from penetrating into the interface. By optimizing the crosslinking network structure and increasing the crosslinking point density, the hydrolytic stability of the interface structure is improved, enabling the composite material to maintain an interfacial bonding strength of over 85% under 85℃ / 85%RH conditions.

[0011] Preferably, the modified epoxy resin is prepared by the following method:

[0012] S1. Prepare bisphenol A epoxy resin, methyldimethoxysilane, imide oligomer, catalyst, and deionized water for later use.

[0013] S2. Heat the bisphenol A type epoxy resin to 80-85℃, add the catalyst, and stir at a rate of 450-500r / min for 5-10min; then add methyldimethoxysilane and deionized water dropwise, and control the temperature at 80-85℃ to react for 1-3h; then add the imide oligomer and continue the reaction for 3-6h to obtain the modified epoxy resin.

[0014] In this invention, the modified epoxy resin exhibits good wettability and affinity for nanofillers through the above-mentioned method, thereby improving the dispersibility of nanofillers in the epoxy resin matrix. Using ultrasonic-shear composite dispersion technology, the dispersion of nanofillers can be increased by 30-50%, significantly increasing the interfacial contact area between the nanofillers and the epoxy resin. The modified functionalized epoxy resin possesses the following characteristics: solid content 62-65%, viscosity (25℃): 350-400 mPa·s, gel time (25℃): 15-20 minutes, tensile strength: ≥25 MPa.

[0015] Preferably, in step S2, the weight ratio of the bisphenol A type epoxy resin, methyl dimethoxysilane, imide oligomer, catalyst and deionized water is 8-12:0.8-1.0:0.7-0.9:0.05-0.06:0.03-0.05.

[0016] Preferably, the imide oligomer is synthesized by the following method: under nitrogen protection, 2,2-hexafluoropropane dianhydride, p-phenylenediamine, and methylnadic anhydride are added to dimethylacetamide, reacted at 80-85°C for 4-6 hours, and the solvent is removed by rotary evaporation to obtain a pale yellow imide oligomer; wherein the mass ratio of 2,2-hexafluoropropane dianhydride, p-phenylenediamine, methylnadic anhydride, and dimethylacetamide is 1.8-2.2:0.55-0.6:0.4-0.5:5.5-6.5.

[0017] The imide oligomers prepared by the above method in this invention can solve three major problems: polarity mismatch at the epoxy / nanofiller interface, easy hydrolysis under humid heat, and softening at high temperature. It is the key chemical unit for achieving the "interface strength improvement ≥40% and humid heat retention rate ≥85%" of this invention, and can effectively improve the comprehensive performance of composite materials.

[0018] Preferably, the nanofiller is one or more of fumed SiO2, Al2O3, BN, and AlN.

[0019] Preferably, the nanofiller needs to be pretreated before use:

[0020] Add nanofiller and dispersant BYK-2155 to acetone, sonicate at 300-500W for 30 min, and then shear at 1500r / min for 30 min to obtain a dispersion.

[0021] The dispersion was heated to 60-65℃, and 11-mercaptoundecyltrimethoxysilane was added. The reaction was carried out under nitrogen protection for 1-3 hours. The temperature was then raised to 75-80℃, and polyimide-siloxane copolymer was added. The reaction was carried out for 1.5-2.5 hours. The mixture was filtered, washed with acetone, and vacuum dried at 110℃ for 2-3 hours to obtain the pretreated nanofiller. The mass ratio of nanofiller, dispersant BYK-2155, 11-mercaptoundecyltrimethoxysilane, and polyimide-siloxane copolymer was 8-12:0.5-1.0:0.3-0.6:4-6.

[0022] In this invention, the nanofiller achieves high dispersion through the aforementioned pretreatment, increasing the dispersion by 30-50% and significantly increasing the interfacial contact area between the nanofiller and epoxy resin, laying the foundation for subsequent interfacial structure construction. By controlling the chain length and terminal functional groups of 11-mercaptoundecyltrimethoxysilane, a gradient polarity transition layer can be formed from the nanofiller to the epoxy resin, achieving a smooth transition of polarity. This gradient polarity interfacial structure can effectively reduce the polarity difference between the epoxy resin and the nanofiller, improving their compatibility.

[0023] Preferably, the amphiphilic interface coupling agent is composed of γ-glycidyl ether propyltrimethoxysilane and polyetheramine D-400 in a mass ratio of 0.4-0.8:0.2-0.4. The amphiphilic coupling agent molecule contains a functional group (such as a silane group) at one end that can form a strong interaction with the surface of the nanofiller, and a reactive group (such as an epoxy group or amino group) at the other end that can form a chemical bond with the epoxy resin network structure. To further enhance the interfacial bonding force, flexible segments are introduced into the coupling agent molecule, giving the molecule a certain conformational adaptability, enabling it to better adapt to the microstructural changes at the interface between the epoxy resin and the nanofiller.

[0024] Preferably, the curing agent is at least one of methyl nadic anhydride and polythiol.

[0025] Preferably, the accelerator is at least one selected from 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, and benzyldimethylamine.

[0026] This invention also provides a method for preparing an epoxy resin-based nanocomposite insulating material, comprising the following steps:

[0027] A1. According to the weight parts, add the pretreated nanofiller to the surfactant, sonicate for 20-40 min and then shear for 20-30 min to obtain the dispersion system for later use;

[0028] A2. According to the weight parts, mix the modified epoxy resin, curing agent, amphiphilic interface coupling agent, tridecafluorooctyltrimethoxysilane, methylnadic anhydride, accelerator and the dispersion system obtained in step A1, heat to 120-130℃ for pre-curing for 1-2 hours, then heat to 150-160℃ for complete curing for 1-3 hours, and finally perform post-curing treatment at 180-190℃ for 2-3 hours to obtain the composite insulating material.

[0029] The beneficial effects of this invention are as follows: By constructing a multifunctional interface structure system, this invention effectively solves the problem of poor compatibility caused by the large polarity difference between epoxy resin and nanofillers, significantly improving the interfacial bonding force between epoxy resin and nanofillers, with an improvement rate of over 40%; the preparation method of functionalized modified epoxy resin enables the modified epoxy resin to have good wettability and affinity for nanofillers, improving the dispersibility of nanofillers in the epoxy resin matrix; through ultrasonic-shear composite dispersion technology, the dispersion degree of nanofillers can be improved by 30-50%; a gradient polarity interface transition layer is designed, and a molecular self-assembled monolayer film is constructed on the surface of the nanofillers. A smooth transition from epoxy resin to nanofiller is achieved, realizing a smooth transition of polarity and effectively reducing the polarity difference between epoxy resin and nanofiller. The molecular structure of the interface coupling agent is optimized so that one end is affinity with epoxy resin and the other end is affinity with nanofiller, forming a stable bridging structure and further enhancing the interfacial bonding force. A hydrophobic fluorosilane modified layer is introduced into the interface structure design to form a dense hydrophobic protective film, effectively blocking water molecules from penetrating into the interface. By optimizing the crosslinking network structure and increasing the crosslinking point density, the hydrolytic stability of the interface structure is improved, enabling the interfacial bonding strength retention rate of the composite material to be increased to over 85% under 85℃ / 85%RH conditions. Detailed Implementation

[0030] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0031] Example 1

[0032] An epoxy resin-based nanocomposite insulating material comprises the following raw materials in parts by weight: 60 parts modified epoxy resin, 4 parts nanofiller, 1 part surfactant, 1 part curing agent, 0.6 parts amphiphilic interface coupling agent, 0.5 parts tridecafluorooctyltrimethoxysilane, 7 parts methylnadic anhydride, and 0.8 parts accelerator.

[0033] The modified epoxy resin is prepared by the following method:

[0034] S1. Prepare bisphenol A epoxy resin, methyldimethoxysilane, imide oligomer, catalyst, and deionized water for later use.

[0035] S2. The bisphenol A type epoxy resin is heated to 80°C, a catalyst is added, and the mixture is stirred at a rate of 500 r / min for 10 min. Then, methyl dimethoxysilane and deionized water are added dropwise, and the reaction is carried out at 80°C for 3 h. Then, imide oligomers are added, and the reaction is continued for 6 h to obtain modified epoxy resin. The preferred catalyst is dibutyltin dilaurate.

[0036] In step S2, the weight ratio of the bisphenol A type epoxy resin, methyl dimethoxysilane, imide oligomer, catalyst and deionized water is 8:0.8:0.7:0.05:0.03.

[0037] The imide oligomer was synthesized by the following method: under nitrogen protection, 2,2-hexafluoropropane dianhydride, p-phenylenediamine, and methylnadic anhydride were added to dimethylacetamide, reacted at 80°C for 6 h, and the solvent was removed by rotary evaporation to obtain a pale yellow imide oligomer; wherein the mass ratio of 2,2-hexafluoropropane dianhydride, p-phenylenediamine, methylnadic anhydride, and dimethylacetamide was 1.8:0.55:0.4:5.5.

[0038] The nanofiller is gaseous SiO2.

[0039] The nanofiller needs to be pretreated before use:

[0040] Add nanofiller and dispersant BYK-2155 to acetone, sonicate at 300W for 30 min, and then shear at 1500r / min for 30 min to obtain a dispersion;

[0041] The dispersion was heated to 60°C, and 11-mercaptoundecyltrimethoxysilane was added. The reaction was carried out under nitrogen protection for 3 hours. The temperature was then raised to 75°C, and polyimide-siloxane copolymer was added. The reaction was carried out for 2.5 hours. The mixture was filtered, washed with acetone, and dried under vacuum at 110°C for 3 hours to obtain the pretreated nanofiller. The mass ratio of nanofiller, dispersant BYK-2155, 11-mercaptoundecyltrimethoxysilane, and polyimide-siloxane copolymer was 8:0.5:0.3:4.

[0042] The amphiphilic interface coupling agent is composed of γ-glycidyl ether propyltrimethoxysilane and polyetheramine D-400 in a mass ratio of 0.4:0.2.

[0043] The curing agent is methyl nadic anhydride.

[0044] The accelerator is 2-ethyl-4-methylimidazole.

[0045] A method for preparing an epoxy resin-based nanocomposite insulating material includes the following steps:

[0046] A1. According to the weight parts, add the pretreated nanofiller to the surfactant, sonicate for 20 min and then shear for 20 min to obtain the dispersion system for later use;

[0047] A2. According to the weight parts, the modified epoxy resin, curing agent, amphiphilic interface coupling agent, tridecafluorooctyltrimethoxysilane, methylnadic anhydride, accelerator and the dispersion system obtained in step A1 are mixed, heated to 120°C for pre-curing for 2 hours, then heated to 150°C for complete curing for 3 hours, and finally post-cured at 180°C for 3 hours to obtain the composite insulating material.

[0048] Example 2

[0049] An epoxy resin-based nanocomposite insulating material comprises the following raw materials in parts by weight: 80 parts modified epoxy resin, 8 parts nanofiller, 2 parts surfactant, 3 parts curing agent, 0.9 parts amphiphilic interface coupling agent, 0.8 parts tridecafluorooctyltrimethoxysilane, 8 parts methylnadic anhydride, and 1.0 part accelerator.

[0050] The modified epoxy resin is prepared by the following method:

[0051] S1. Prepare bisphenol A epoxy resin, methyldimethoxysilane, imide oligomer, catalyst, and deionized water for later use.

[0052] S2. The bisphenol A type epoxy resin is heated to 83°C, a catalyst is added, and the mixture is stirred at a rate of 480 r / min for 8 min. Then, methyl dimethoxysilane and deionized water are added dropwise, and the reaction is carried out at 83°C for 2 h. Then, imide oligomers are added, and the reaction is continued for 5 h to obtain modified epoxy resin. The preferred catalyst is dibutyltin dilaurate.

[0053] In step S2, the weight ratio of the bisphenol A type epoxy resin, methyl dimethoxysilane, imide oligomer, catalyst and deionized water is 10:0.9:0.8:0.055:0.04.

[0054] The imide oligomer was synthesized by the following method: under nitrogen protection, 2,2-hexafluoropropane dianhydride, p-phenylenediamine, and methylnadic anhydride were added to dimethylacetamide, reacted at 83°C for 5 h, and the solvent was removed by rotary evaporation to obtain a pale yellow imide oligomer; wherein the mass ratio of 2,2-hexafluoropropane dianhydride, p-phenylenediamine, methylnadic anhydride, and dimethylacetamide was 2.0:0.558:0.45:6.0.

[0055] The nanofiller is Al2O3.

[0056] The nanofiller needs to be pretreated before use:

[0057] Add the nanofiller and dispersant BYK-2155 to acetone, sonicate at 400W for 30 min, and then shear at 1500 r / min for 30 min to obtain the dispersion.

[0058] The dispersion was heated to 63°C, and 11-mercaptoundecyltrimethoxysilane was added. The reaction was carried out under nitrogen protection for 2 hours. The temperature was then raised to 78°C, and polyimide-siloxane copolymer was added. The reaction was carried out for 2.0 hours. The mixture was filtered, washed with acetone, and vacuum dried at 110°C for 2.5 hours to obtain the pretreated nanofiller. The mass ratio of nanofiller, dispersant BYK-2155, 11-mercaptoundecyltrimethoxysilane, and polyimide-siloxane copolymer was 10:0.8:0.5:5.

[0059] The amphiphilic interface coupling agent is composed of γ-glycidyl ether propyltrimethoxysilane and polyetheramine D-400 in a mass ratio of 0.6:0.3.

[0060] The curing agent is polythiol.

[0061] The promoter is 1,2-dimethylimidazole.

[0062] A method for preparing an epoxy resin-based nanocomposite insulating material includes the following steps:

[0063] A1. According to the weight parts, add the pretreated nanofiller to the surfactant, sonicate for 30 min and then shear for 25 min to obtain the dispersion system for later use;

[0064] A2. According to the weight parts, mix the modified epoxy resin, curing agent, amphiphilic interface coupling agent, tridecafluorooctyltrimethoxysilane, methylnadic anhydride, accelerator and the dispersion system obtained in step A1, heat to 125℃ for pre-curing for 1.5h, then heat to 155℃ for complete curing for 2h, and finally perform post-curing treatment at 185℃ for 2.5h to obtain the composite insulation material.

[0065] Example 3

[0066] An epoxy resin-based nanocomposite insulating material comprises the following raw materials in parts by weight: 100 parts modified epoxy resin, 12 parts nanofiller, 3 parts surfactant, 5 parts curing agent, 1.2 parts amphiphilic interface coupling agent, 1.0 part tridecafluorooctyltrimethoxysilane, 10 parts methylnadic anhydride, and 1.2 parts accelerator.

[0067] The modified epoxy resin is prepared by the following method:

[0068] S1. Prepare bisphenol A epoxy resin, methyldimethoxysilane, imide oligomer, catalyst, and deionized water for later use.

[0069] S2. The bisphenol A type epoxy resin is heated to 85°C, a catalyst is added, and the mixture is stirred at a rate of 500 r / min for 10 min. Then, methyl dimethoxysilane and deionized water are added dropwise, and the reaction is carried out at 85°C for 3 h. Then, imide oligomers are added, and the reaction is continued for 3 h to obtain modified epoxy resin. The preferred catalyst is dibutyltin dilaurate.

[0070] In step S2, the weight ratio of the bisphenol A type epoxy resin, methyl dimethoxysilane, imide oligomer, catalyst and deionized water is 12:1.0:0.9:-0.06:0.05.

[0071] The imide oligomer was synthesized by the following method: under nitrogen protection, 2,2-hexafluoropropane dianhydride, p-phenylenediamine, and methylnadic anhydride were added to dimethylacetamide, reacted at 85°C for 4 hours, and the solvent was removed by rotary evaporation to obtain a pale yellow imide oligomer; wherein the mass ratio of 2,2-hexafluoropropane dianhydride, p-phenylenediamine, methylnadic anhydride, and dimethylacetamide was 2.2:0.6:0.5:6.5.

[0072] The nanofiller is gaseous SiO2.

[0073] The nanofiller needs to be pretreated before use:

[0074] Add nanofiller and dispersant BYK-2155 to acetone, sonicate at 500W for 30 min, and then shear at 1500r / min for 30 min to obtain a dispersion;

[0075] The dispersion was heated to 65°C, and 11-mercaptoundecyltrimethoxysilane was added. The reaction was carried out under nitrogen protection for 1 hour. The temperature was then raised to 80°C, and polyimide-siloxane copolymer was added. The reaction was carried out for 1.5 hours. The mixture was filtered, washed with acetone, and vacuum dried at 110°C for 2 hours to obtain the pretreated nanofiller. The mass ratio of nanofiller, dispersant BYK-2155, 11-mercaptoundecyltrimethoxysilane, and polyimide-siloxane copolymer was 12:1.0:0.6:6.

[0076] The amphiphilic interface coupling agent is composed of γ-glycidyl ether propyltrimethoxysilane and polyetheramine D-400 in a mass ratio of 0.8:0.4.

[0077] The curing agent is methyl nadic anhydride.

[0078] The accelerator is benzyldimethylamine.

[0079] A method for preparing an epoxy resin-based nanocomposite insulating material includes the following steps:

[0080] A1. According to the weight parts, add the pretreated nanofiller to the surfactant, sonicate for 20 min and then shear for 20 min to obtain the dispersion system for later use;

[0081] A2. According to the weight parts, the modified epoxy resin, curing agent, amphiphilic interface coupling agent, tridecafluorooctyltrimethoxysilane, methylnadic anhydride, accelerator and dispersion system obtained in step A1 are mixed, heated to 130℃ for pre-curing for 1 hour, then heated to 160℃ for complete curing for 1 hour, and finally post-cured at 190℃ for 2 hours to obtain composite insulation material.

[0082] Example 4

[0083] An epoxy resin-based nanocomposite insulating material comprises the following raw materials in parts by weight: 80 parts modified epoxy resin, 8 parts nanofiller, 2 parts surfactant, 3 parts curing agent, 0.9 parts amphiphilic interface coupling agent, 0.8 parts tridecafluorooctyltrimethoxysilane, 8 parts methylnadic anhydride, and 1 part accelerator.

[0084] The modified epoxy resin in this epoxy resin-based nanocomposite insulating material is prepared by the following method:

[0085] S1. Raw material preparation: Prepare 10 parts of bisphenol A type epoxy resin, 0.9 parts of methyl dimethoxysilane, 0.8 parts of imide oligomer, 0.055 parts of catalyst, and 0.04 parts of deionized water for later use;

[0086] S2. Epoxy resin modification: Bisphenol A type epoxy resin is heated to 83°C, a catalyst is added, and the mixture is stirred at a rate of 480 r / min for 8 min; then a mixture of methyl dimethoxysilane and deionized water is added dropwise, and the temperature is controlled at 83°C for 2 h; then an imide oligomer is added, and the reaction continues for 4 h to obtain modified epoxy resin; wherein, the catalyst is preferably dibutyltin dilaurate.

[0087] In a preferred embodiment, the weight ratio of bisphenol A epoxy resin, methyldimethoxysilane, imide oligomer, catalyst, and deionized water can be 10:0.9:0.8:0.055:0.04. This ratio ensures sufficient modification of the epoxy resin, improving the insulation performance and thermal stability of the final composite material.

[0088] The above-mentioned imide oligomers were synthesized by the following method: Under nitrogen protection, 2,2-hexafluoropropane dianhydride, p-phenylenediamine, and methylnadic anhydride were added to dimethylacetamide, reacted at 82°C for 5 h, and the solvent was removed by rotary evaporation to obtain pale yellow imide oligomers. The mass ratio of 2,2-hexafluoropropane dianhydride, p-phenylenediamine, methylnadic anhydride, and dimethylacetamide was 2:0.58:0.45:6.

[0089] The nanofiller used in this embodiment is a mixture of fumed SiO2 and Al2O3, mixed in a 1:1 mass ratio. Before use, the nanofiller undergoes pretreatment:

[0090] F1. Dispersion treatment: Take 10 parts of nanofiller and 0.8 parts of dispersant BYK-2155, add acetone, sonicate at 400W for 30min, and then shear at 1500r / min for 30min to obtain a dispersion.

[0091] F2. Surface modification: The dispersion was heated to 63°C, and 0.5 parts of 11-mercaptoundecyltrimethoxysilane were added. The mixture was reacted for 2 hours under nitrogen protection. The temperature was then raised to 78°C, and 5 parts of 4wt% polyimide siloxane copolymer were added. The mixture was reacted for 2 hours.

[0092] F3. Post-treatment: Filtration, acetone washing, vacuum drying at 110℃ for 2.5h to obtain pretreated nanofillers.

[0093] In this embodiment, the amphiphilic interface coupling agent is composed of 0.6 parts of γ-glycidyl ether propyltrimethoxysilane and 0.3 parts of polyetheramine D-400, with a mass ratio of 2:1. The amphiphilic interface coupling agent can effectively improve the interfacial compatibility between the nanofiller and the epoxy resin matrix, prevent the nanofiller from agglomerating, and improve the uniformity of the composite material.

[0094] The curing agent is a mixture of methyl nadic anhydride and polythiol, mixed at a mass ratio of 2:1. The choice of curing agent has a significant impact on the degree of curing and final properties of the composite material; the combination of methyl nadic anhydride and polythiol can provide excellent curing effect and mechanical strength.

[0095] The accelerator selected is 2-ethyl-4-methylimidazole, which can accelerate the curing reaction of epoxy resin, shorten the curing time, and improve production efficiency.

[0096] The preparation method of this epoxy resin-based nanocomposite insulating material is as follows:

[0097] S1. Pretreatment: Heat the modified epoxy resin at 80°C until it reaches a fluid state;

[0098] S2. Mixing: The pretreated nanofiller, surfactant, amphiphilic interface coupling agent and tridecafluorooctyltrimethoxysilane were added to the modified epoxy resin and mechanically stirred at 85°C for 30 min, and then dispersed at 2000 r / min at high speed for 1 h.

[0099] S3. Curing: When the temperature drops to 60℃, add the curing agent and accelerator, and continue stirring for 15 minutes until uniform;

[0100] S4. Pouring: Pour the mixture into a preheated mold, pre-cur at 90°C for 2 hours, then post-cur at 150°C for 4 hours, and finally cure at 180°C for 2 hours.

[0101] S5. Demolding: After the temperature drops to room temperature, demold to obtain epoxy resin-based nanocomposite insulating material.

[0102] The prepared epoxy resin-based nanocomposite insulating material exhibits excellent electrical insulation properties, with a volume resistivity reaching 1.5 × 10⁻⁶. 16 The material exhibits a dielectric constant of 3.2, a dielectric loss of 0.008 kJ / cm, a breakdown strength of 28 kV / mm, and a dielectric constant of 3.2. It also demonstrates good thermal stability, with a glass transition temperature (Tg) of 185 °C and a thermal decomposition temperature (Td5) of 390 °C. Furthermore, its mechanical properties are excellent, with a tensile strength of 75 MPa, a flexural strength of 120 MPa, and an impact strength of 18 kJ / m. 2 .

[0103] By modifying epoxy resin with imide oligomers and methyldimethoxysilane, and adding specially pretreated nanofillers, the composite insulation material of this embodiment achieves a comprehensive improvement in electrical performance, thermal stability and mechanical properties, and is particularly suitable for insulating components of high-voltage electrical equipment, transformer insulating materials and electronic packaging materials.

[0104] Example 5

[0105] A method for preparing an epoxy resin-based nanocomposite insulating material includes the following steps:

[0106] A1. Dispersion treatment: Add the pretreated nanofiller to the surfactant according to the weight parts, sonicate for 30 min and then shear for 25 min to obtain the dispersion system for later use.

[0107] A2. Preparation of composite material: According to the weight parts, the modified epoxy resin, curing agent, amphiphilic interface coupling agent, tridecafluorooctyltrimethoxysilane, methylnadic anhydride, accelerator and dispersion system obtained in step A1 are mixed, heated to 125℃ for pre-curing for 1.5h, then heated to 155℃ for complete curing for 2h, and finally post-cured at 185℃ for 2.5h to obtain composite insulating material.

[0108] The modified epoxy resin, nanofiller and its pretreatment method, amphiphilic interface coupling agent, curing agent, accelerator and other materials used in this embodiment are the same as those in Example 1.

[0109] In this embodiment, the ultrasonic power during the dispersion process is 400W, and the shear rate is 1500r / min. During the composite material preparation process, the modified epoxy resin is first heated to a fluid state, then the dispersion system and other additives are added. The mixture is mechanically stirred at 85°C for 30 minutes, followed by high-speed shear dispersion at 2000r / min for 1 hour. When the temperature drops to 60°C, the curing agent and accelerator are added, and stirring continues for 15 minutes until homogeneous before curing.

[0110] The epoxy resin-based nanocomposite insulating material prepared in this embodiment exhibits excellent electrical insulation properties and thermal stability, with a volume resistivity reaching 1.6 × 10⁻⁶. 16 The material exhibits excellent thermal stability, with a glass transition temperature (Tg) of 188℃ and a thermal decomposition temperature (Td5) of 395℃. In terms of mechanical properties, the material has a tensile strength of 78 MPa, a flexural strength of 125 MPa, and an impact strength of 19 kJ / m. Its breakdown strength is 29 kV / mm, dielectric constant is 3.1, and dielectric loss is 0.007. 2 .

[0111] Compared with Example 4, this example further improves the crosslinking density and structural uniformity of the material by optimizing the curing process parameters, especially by adopting a three-stage curing process, thereby further enhancing the overall performance of the material.

[0112] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. An epoxy resin-based nanocomposite insulating material, characterized in that: The raw materials include the following parts by weight: 60-100 parts modified epoxy resin, 4-12 parts nanofiller, 1-3 parts surfactant, 1-5 parts curing agent, 0.6-1.2 parts amphiphilic interface coupling agent, 0.5-1.0 parts tridecafluorooctyltrimethoxysilane, 7-10 parts methylnadic anhydride, and 0.8-1.2 parts accelerator.

2. The epoxy resin-based nanocomposite insulating material according to claim 1, characterized in that: The modified epoxy resin is prepared by the following method: S1. Prepare bisphenol A epoxy resin, methyldimethoxysilane, imide oligomer, catalyst, and deionized water for later use. S2. Heat the bisphenol A type epoxy resin to 80-85℃, add the catalyst, and stir at a rate of 450-500r / min for 5-10min; then add methyldimethoxysilane and deionized water dropwise, and control the temperature at 80-85℃ to react for 1-3h; then add the imide oligomer and continue the reaction for 3-6h to obtain the modified epoxy resin.

3. The epoxy resin-based nanocomposite insulating material according to claim 2, characterized in that: In step S2, the weight ratio of the bisphenol A type epoxy resin, methyldimethoxysilane, imide oligomer, catalyst, and deionized water is 8-12: 0.8-1.0:0.7-0.9:0.05-0.06:0.03-0.05。 4. The epoxy resin-based nanocomposite insulating material according to claim 2, characterized in that: The imide oligomer was synthesized by the following method: under nitrogen protection, 2,2-hexafluoropropane dianhydride, p-phenylenediamine, and methylnadic anhydride were added to dimethylacetamide and reacted at 80-85°C for 4-6 hours. The solvent was removed by rotary evaporation to obtain a pale yellow imide oligomer. The mass ratio of 2,2-hexafluoropropane dianhydride, p-phenylenediamine, methylnadic anhydride, and dimethylacetamide was 1.8-2.2:0.55-0.6:0.4-0.5:5.5-6.

5.

5. The epoxy resin-based nanocomposite insulating material according to claim 1, characterized in that: The nanofiller is one or more of the following: gaseous SiO2, Al2O3, BN, and AlN.

6. The epoxy resin-based nanocomposite insulating material according to claim 1, characterized in that: The nanofiller needs to be pretreated before use: Add nanofiller and dispersant BYK-2155 to acetone, sonicate at 300-500W for 30 min, and then shear at 1500r / min for 30 min to obtain a dispersion. The dispersion was heated to 60-65℃, and 11-mercaptoundecyltrimethoxysilane was added. The reaction was carried out under nitrogen protection for 1-3 hours. The temperature was then raised to 75-80℃, and polyimide-siloxane copolymer was added. The reaction was carried out for 1.5-2.5 hours. The mixture was filtered, washed with acetone, and vacuum dried at 110℃ for 2-3 hours to obtain the pretreated nanofiller. The mass ratio of nanofiller, dispersant BYK-2155, 11-mercaptoundecyltrimethoxysilane, and polyimide-siloxane copolymer was 8-12:0.5-1.0:0.3-0.6:4-6.

7. The epoxy resin-based nanocomposite insulating material according to claim 1, characterized in that: The amphiphilic interface coupling agent is composed of γ-glycidyl ether propyltrimethoxysilane and polyetheramine D-400 in a mass ratio of 0.4-0.8:0.2-0.

4.

8. The epoxy resin-based nanocomposite insulating material according to claim 1, characterized in that: The curing agent is at least one of methylnadic anhydride and polythiol.

9. The epoxy resin-based nanocomposite insulating material according to claim 1, characterized in that: The accelerator is at least one of 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, and benzyldimethylamine.

10. A method for preparing an epoxy resin-based nanocomposite insulating material as described in any one of claims 1-9, characterized in that: Includes the following steps: A1. According to the weight parts, add the pretreated nanofiller to the surfactant, sonicate for 20-40 min and then shear for 20-30 min to obtain the dispersion system for later use; A2. According to the weight parts, mix the modified epoxy resin, curing agent, amphiphilic interface coupling agent, tridecafluorooctyltrimethoxysilane, methylnadic anhydride, accelerator and the dispersion system obtained in step A1, heat to 120-130℃ for pre-curing for 1-2 hours, then heat to 150-160℃ for complete curing for 1-3 hours, and finally perform post-curing treatment at 180-190℃ for 2-3 hours to obtain the composite insulating material.