A thermally conductive insulating epoxy resin material and a method for producing the same

Abstract

This invention belongs to the field of polymer materials technology and relates to a thermally conductive and insulating epoxy resin material and its preparation method. The invention provides a thermally conductive and insulating epoxy resin material, which, by weight, comprises: 100 parts epoxy resin, 60-80 parts curing agent, 0.1-1 parts accelerator, 20-25 parts boron nitride, 0.03-0.05 parts polyaniline, and 20-25 parts octaaminophenyl cage-like silsesquioxane modified composite mica powder; the composite mica powder is composed of dry-milled mica powder and wet-milled mica powder in a weight ratio of 1:6-8. The thermally conductive and insulating epoxy resin material provided by this invention combines moisture-proof performance, thermal conductivity, and insulation performance, and is suitable for electrical engineering applications such as power electronic transformers and electrical electronic equipment.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and relates to a thermally conductive and insulating epoxy resin material and its preparation method. Background Technology

[0002] Epoxy resin, due to its excellent electrical insulation, mechanical adhesion, molding processability, and chemical stability, is one of the most widely used polymer insulation materials in the electrical engineering field, such as power electronic transformers and electrical electronic equipment. With the rapid development of power electronics technology, electrical equipment is moving towards miniaturization, high power, and integration. During operation, these devices generate a large amount of heat. If this heat cannot be dissipated in time, it can cause localized overheating, accelerating the aging and failure of the epoxy resin insulation matrix, reducing the material's insulation performance and service life, and affecting the operational stability and safety of the electrical equipment. Furthermore, the operating environment of electrical equipment is often characterized by humidity and moisture; insufficient moisture resistance of the material can lead to rapid degradation of its dielectric and mechanical properties, further limiting the applicable scenarios of the equipment. Therefore, possessing excellent thermal conductivity, insulation performance, and moisture resistance has become a core research and development requirement for epoxy resin materials used in electrical engineering.

[0003] To improve the thermal conductivity of epoxy resin, existing technologies often employ the addition of inorganic thermally conductive fillers to the epoxy resin matrix. Commonly used fillers include boron nitride, alumina, and mica powder. Among these, boron nitride, with its high thermal conductivity and good insulation properties, is a preferred filler for electrical thermally conductive and insulating materials. However, boron nitride has poor interfacial compatibility with the organic epoxy resin matrix, easily agglomerating within the matrix and making it difficult to construct continuous thermal conductive pathways, thus limiting the improvement in thermal conductivity. Mica powder, as a traditional insulating filler, possesses certain potential for both thermal conductivity and moisture resistance. However, its modification effect is poor when used alone, and existing technologies often employ single dry or wet milling of mica powder. Dry-milled mica powder has a narrow particle size distribution and poor lamellar structure integrity, while wet-milled mica powder has large lamellars but poor dispersibility. The interfacial bonding between a single type of mica powder and epoxy resin is weak, easily leading to interfacial defects, and failing to achieve a synergistic improvement in both thermal conductivity and insulation.

[0004] To improve the compatibility between fillers and epoxy resin matrices, existing technologies have attempted to modify the surface of inorganic fillers using silane coupling agents. However, these modification methods are limited, only achieving simple functionalization of the filler surface, and are insufficient to improve the interfacial bonding strength between the filler and the resin matrix. The modified fillers still tend to be unevenly dispersed in the matrix, failing to construct a stable thermally conductive network. Cage-like silsesquioxanes possess unique core-shell structures and abundant reactive functional groups, effectively improving interfacial compatibility and overall material performance in polymer modification. However, there are currently no reports on the use of octaaminophenyl cage-like silsesquioxanes for composite modification of mica powder and their application in epoxy resin thermally conductive and insulating systems. Furthermore, some studies have attempted to introduce conductive polymers such as polyaniline to improve the interfacial properties of epoxy resins. However, if the polyaniline addition ratio is improperly controlled or the composite process is unreasonable, it can easily damage the insulating properties of the epoxy resin, making it difficult to achieve a balance between thermal conductivity and insulation.

[0005] In summary, the development of existing thermally conductive and insulating epoxy resin materials still faces numerous technical bottlenecks. Most modification schemes focus only on improving a single property, failing to simultaneously address the three core properties of thermal conductivity, insulation, and moisture resistance. Inorganic fillers exhibit poor compatibility with the epoxy resin matrix, are prone to agglomeration, and are difficult to construct thermally conductive pathways. Filler modification methods are limited, resulting in low interfacial bonding strength and poor overall material stability. Furthermore, there is a lack of dedicated modification systems designed for electrical engineering applications, failing to meet the requirements of high-end electrical equipment such as power electronic transformers and electrical electronic devices. Therefore, developing an epoxy resin material with good compatibility among its components and balanced thermal conductivity, insulation, and moisture resistance has become a pressing technical challenge in the field of polymeric insulation materials. Summary of the Invention

[0006] The present invention aims to provide a thermally conductive and insulating epoxy resin material that combines moisture resistance, thermal conductivity and insulation properties, and is suitable for electrical engineering scenarios such as power electronic transformers and electrical electronic equipment.

[0007] To address this need, the present invention provides a thermally conductive and insulating epoxy resin material and its preparation method.

[0008] On one hand, the present invention relates to a thermally conductive and insulating epoxy resin material, the raw materials of which, by weight, include: 100 parts epoxy resin, 60-80 parts curing agent, 0.1-1 parts accelerator, 20-25 parts boron nitride, 0.03-0.05 parts polyaniline and 20-25 parts octaaminophenyl cage-like silsesquioxane modified composite mica powder; The composite mica powder is composed of dry-ground mica powder and wet-ground mica powder in a mass ratio of 1:6 to 8.

[0009] Furthermore, in the thermally conductive and insulating epoxy resin material provided by the present invention, the epoxy resin is a bisphenol A type epoxy resin.

[0010] Furthermore, in the thermally conductive and insulating epoxy resin material provided by the present invention, the curing agent is phthalic anhydride or methyltetrahydrophthalic anhydride.

[0011] Furthermore, in the thermally conductive and insulating epoxy resin material provided by the present invention, the accelerator is one of 2-ethyl-4-methylimidazole, 2,4-dimethylimidazole, and 1-methylimidazole.

[0012] Furthermore, in the thermally conductive and insulating epoxy resin material provided by the present invention, the average particle size of the boron nitride is not higher than 1 μm.

[0013] Furthermore, in the thermally conductive and insulating epoxy resin material provided by the present invention, the average particle size of the dry-ground mica powder is 40~50μm.

[0014] Furthermore, in the thermally conductive and insulating epoxy resin material provided by the present invention, the average particle size of the wet-milled mica powder is 30~50μm.

[0015] On the other hand, the present invention relates to a method for preparing a thermally conductive and insulating epoxy resin material, comprising: S1. Dry-ground mica powder and wet-ground mica powder are mixed at a mass ratio of 1:6 to 8 to obtain composite mica powder. 10g of the composite mica powder is dispersed in 90 to 110mL of anhydrous toluene and ultrasonically dispersed to make the mica uniformly suspended to obtain a suspension. S2. For every 10g of the composite mica powder, add 0.4mL of silane coupling agent KH-560 to the suspension, then add 2-3 drops of deionized water and seal the reaction system. Under nitrogen protection, heat to 105-115℃ and stir under reflux for 8-12h. After the reaction is completed, cool, centrifuge or filter to collect the solid, wash with anhydrous toluene 2-3 times, then wash with anhydrous ethanol 2-3 times, and dry at 45-55℃ for 4-6h to obtain epoxy-oxidized composite mica powder. S3. Dissolve 1g of octaaminophenyl cage-like silsesquioxane in 90-110mL of DMF, then add 10g of the epoxy-modified composite mica powder, ultrasonically disperse for 10-20min, stir and react at 75-85℃ for 12-36h, cool after the reaction, collect the solid by centrifugation or vacuum filtration, wash with anhydrous toluene 2-3 times, then wash with anhydrous ethanol 2-3 times, and dry at 55-65℃ for 8-12h to obtain the octaaminophenyl cage-like silsesquioxane modified composite mica powder; S4, epoxy resin, curing agent, accelerator, boron nitride and octaaminophenyl cage-like silsesquioxane modified composite mica powder are added to a mixing tank preheated to 60~80℃ according to the component ratio. After mixing at this temperature for 2~3 hours, polyaniline is added and mixed at this temperature for another 2~3 hours. Finally, the mixture is added to a mold for segmented curing to obtain the thermally conductive and insulating epoxy resin material.

[0016] Furthermore, in the preparation method of the thermally conductive and insulating epoxy resin material provided by the present invention, the segmented curing is first cured at 90~110℃ for 4~6h, and then cured at 130~150℃ for 8~10h.

[0017] Furthermore, in the preparation method of the thermally conductive and insulating epoxy resin material provided by the present invention, the stirring rate of any of the heat-insulating mixing processes is 100~150 r / min.

[0018] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: This invention, through a multi-synergistic strategy, successfully solves the technical bottlenecks of uneven filler dispersion, poor interfacial compatibility, and difficulty in achieving balanced performance in existing thermally conductive and insulating epoxy resin materials, achieving significantly superior comprehensive performance compared to existing technologies. This invention uses a composite filler made from a blend of dry-ground and wet-ground mica powder, fully leveraging the synergistic dispersion effect of the rough surface of dry-ground mica, effectively solving the problem of easy agglomeration and stacking of wet-ground mica, which hinders the formation of thermally conductive pathways for boron nitride. Simultaneously, it avoids the increased interfacial thermal resistance caused by numerous defects and a small aspect ratio in dry-ground mica. Furthermore, this invention significantly improves the interfacial compatibility between the filler and the epoxy resin matrix by modifying the composite mica powder with octaaminophenyl cage-like silsesquioxane, eliminating localized electric field concentration caused by interfacial defects and impurities, and ensuring the insulation reliability of the material under high-voltage environments. This invention utilizes a dense packing structure formed by dry and wet grinding of mica, combined with excellent interfacial bonding resulting from modification, and optimizes the filler-matrix interface structure through a stepwise addition process of trace amounts of polyaniline. This effectively reduces interfacial voids and defects within the material, exhibiting excellent resistance to humid heat aging and dimensional stability. The thermally conductive and insulating epoxy resin material provided by this invention successfully overcomes the drawbacks of existing technologies, such as the difficulty in simultaneously achieving thermal conductivity and insulation, easy agglomeration of fillers, and poor moisture resistance, thus preparing a high-performance composite electrical material with high thermal conductivity, high insulation, and low water absorption. Detailed Implementation

[0019] The technical solution of the present invention will be described below with reference to embodiments; however, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental and detection methods described in each embodiment are conventional methods; the reagents and materials described are commercially available unless otherwise specified. Unless otherwise specified, all percentages in the following embodiments refer to mass percentage content. Unless otherwise specified, all ratios in the following embodiments refer to mass ratios.

[0020] In the following embodiments, the dry-ground mica powder used has a size of 45μm (325 mesh), which meets the requirements of JC / T 595-2017 Dry-ground Mica Powder for the corresponding size; the wet-ground mica powder used has a size of 45μm (325 mesh), which meets the requirements of JC / T 596-2017 Wet-ground Mica Powder for the corresponding size; and the boron nitride used is hexagonal boron nitride micro powder with a diameter of 1μm.

[0021] Example 1

[0022] This embodiment provides the preparation process of thermally conductive and insulating epoxy resin material.

[0023] S1. Mix dry-ground mica powder and wet-ground mica powder at a mass ratio of 1:6 to obtain composite mica powder. Take 10g of composite mica powder and disperse it in 100mL of anhydrous toluene. Use ultrasonic dispersion to make the mica uniformly suspended to obtain a suspension.

[0024] S2. Add 0.4 mL of silane coupling agent KH-560 to the suspension, then add 2-3 drops of deionized water and seal the reaction system. Heat to 110 °C under nitrogen protection and stir under reflux for 10 h. After the reaction is completed, cool and collect the solid by centrifugation or vacuum filtration. Wash twice with anhydrous toluene and three times with anhydrous ethanol. Dry at 50 °C for 5 h to obtain epoxy-oxidized composite mica powder for later use.

[0025] S3. Dissolve 1g of octaaminophenyl cage-like silsesquioxane in 100mL of DMF, then add 10g of epoxy-modified composite mica powder. After ultrasonic dispersion for 15min, stir and react at 80℃ for 24h. After the reaction is completed, cool, centrifuge or filter to collect the solid, wash twice with anhydrous toluene, then wash three times with anhydrous ethanol, and dry at 60℃ for 10h to obtain octaaminophenyl cage-like silsesquioxane modified composite mica powder for later use.

[0026] S4. By weight, take 100 parts of bisphenol A type epoxy resin, 60 parts of phthalic anhydride, 0.1 parts of 2-ethyl-4-methylimidazole, 20 parts of boron nitride, 0.03 parts of polyaniline, and 20 parts of octaaminophenyl cage-like silsesquioxane modified composite mica powder as raw materials for later use; add the bisphenol A type epoxy resin, phthalic anhydride, 2-ethyl-4-methylimidazole, boron nitride, and octaaminophenyl cage-like silsesquioxane modified composite mica powder into a mixing tank preheated to 70°C according to the component ratio, keep warm and mix at a stirring rate of 100 r / min for 2 hours, add polyaniline, keep warm and mix at a stirring rate of 100 r / min for 3 hours, finally add to the mold, first cure at 100°C for 5 hours, then cure at 140°C for 9 hours to obtain a thermally conductive and insulating epoxy resin material.

[0027] Example 2

[0028] This embodiment provides the preparation process of thermally conductive and insulating epoxy resin material.

[0029] S1. Mix dry-ground mica powder and wet-ground mica powder at a mass ratio of 1:7 to obtain composite mica powder. Take 10g of composite mica powder and disperse it in 100mL of anhydrous toluene. Use ultrasonic dispersion to make the mica uniformly suspended to obtain a suspension.

[0030] S2. Add 0.4 mL of silane coupling agent KH-560 to the suspension, then add 2-3 drops of deionized water and seal the reaction system. Heat to 110 °C under nitrogen protection and stir under reflux for 10 h. After the reaction is completed, cool and collect the solid by centrifugation or vacuum filtration. Wash twice with anhydrous toluene and three times with anhydrous ethanol. Dry at 50 °C for 5 h to obtain epoxy-oxidized composite mica powder for later use.

[0031] S3. Dissolve 1g of octaaminophenyl cage-like silsesquioxane in 100mL of DMF, then add 10g of epoxy-modified composite mica powder. After ultrasonic dispersion for 15min, stir and react at 80℃ for 24h. After the reaction is completed, cool, centrifuge or filter to collect the solid, wash twice with anhydrous toluene, then wash three times with anhydrous ethanol, and dry at 60℃ for 10h to obtain octaaminophenyl cage-like silsesquioxane modified composite mica powder for later use.

[0032] S4. By weight, take 100 parts of bisphenol A type epoxy resin, 70 parts of phthalic anhydride, 0.3 parts of 2,4-dimethylimidazole, 23 parts of boron nitride, 0.04 parts of polyaniline, and 23 parts of octaaminophenyl cage-like silsesquioxane modified composite mica powder as raw materials for later use; add the bisphenol A type epoxy resin, phthalic anhydride, 2,4-dimethylimidazole, boron nitride, and octaaminophenyl cage-like silsesquioxane modified composite mica powder into a mixing tank preheated to 70°C according to the component ratio, keep warm and mix at a stirring rate of 100 r / min for 2 hours, add polyaniline, keep warm and mix at a stirring rate of 100 r / min for 3 hours, finally add to the mold, first cure at 100°C for 5 hours, then cure at 140°C for 9 hours to obtain a thermally conductive and insulating epoxy resin material.

[0033] Example 3

[0034] This embodiment provides the preparation process of thermally conductive and insulating epoxy resin material.

[0035] S1. Mix dry-ground mica powder and wet-ground mica powder at a mass ratio of 1:7 to obtain composite mica powder. Take 10g of composite mica powder and disperse it in 100mL of anhydrous toluene. Use ultrasonic dispersion to make the mica uniformly suspended to obtain a suspension.

[0036] S2. Add 0.4 mL of silane coupling agent KH-560 to the suspension, then add 2-3 drops of deionized water and seal the reaction system. Heat to 110 °C under nitrogen protection and stir under reflux for 10 h. After the reaction is completed, cool and collect the solid by centrifugation or vacuum filtration. Wash twice with anhydrous toluene and three times with anhydrous ethanol. Dry at 50 °C for 5 h to obtain epoxy-oxidized composite mica powder for later use.

[0037] S3. Dissolve 1g of octaaminophenyl cage-like silsesquioxane in 100mL of DMF, then add 10g of epoxy-modified composite mica powder. After ultrasonic dispersion for 15min, stir and react at 80℃ for 24h. After the reaction is completed, cool, centrifuge or filter to collect the solid, wash twice with anhydrous toluene, then wash three times with anhydrous ethanol, and dry at 60℃ for 10h to obtain octaaminophenyl cage-like silsesquioxane modified composite mica powder for later use.

[0038] S4. By weight, take 100 parts of bisphenol A type epoxy resin, 80 parts of methyltetrahydrophthalic anhydride, 0.8 parts of 1-methylimidazole, 23 parts of boron nitride, 0.04 parts of polyaniline, and 23 parts of octaaminophenyl cage-like silsesquioxane modified composite mica powder as raw materials for later use; add the bisphenol A type epoxy resin, methyltetrahydrophthalic anhydride, 1-methylimidazole, boron nitride, and octaaminophenyl cage-like silsesquioxane modified composite mica powder into a mixing tank preheated to 70°C according to the component ratio, keep warm and mix at a stirring rate of 100 r / min for 2 hours, add polyaniline, keep warm and mix at a stirring rate of 100 r / min for 3 hours, finally add to the mold, first cure at 90°C for 4 hours, then cure at 130°C for 8 hours to obtain a thermally conductive and insulating epoxy resin material.

[0039] Example 4

[0040] This embodiment provides the preparation process of thermally conductive and insulating epoxy resin material.

[0041] S1. Mix dry-ground mica powder and wet-ground mica powder at a mass ratio of 1:8 to obtain composite mica powder. Take 10g of composite mica powder and disperse it in 100mL of anhydrous toluene. Use ultrasonic dispersion to make the mica uniformly suspended to obtain a suspension.

[0042] S2. Add 0.4 mL of silane coupling agent KH-560 to the suspension, then add 2-3 drops of deionized water and seal the reaction system. Heat to 110 °C under nitrogen protection and stir under reflux for 10 h. After the reaction is completed, cool and collect the solid by centrifugation or vacuum filtration. Wash twice with anhydrous toluene and three times with anhydrous ethanol. Dry at 50 °C for 5 h to obtain epoxy-oxidized composite mica powder for later use.

[0043] S3. Dissolve 1g of octaaminophenyl cage-like silsesquioxane in 100mL of DMF, then add 10g of epoxy-modified composite mica powder. After ultrasonic dispersion for 15min, stir and react at 80℃ for 24h. After the reaction is completed, cool, centrifuge or filter to collect the solid, wash twice with anhydrous toluene, then wash three times with anhydrous ethanol, and dry at 60℃ for 10h to obtain octaaminophenyl cage-like silsesquioxane modified composite mica powder for later use.

[0044] S4. By weight, take 100 parts of bisphenol A type epoxy resin, 70 parts of methyltetrahydrophthalic anhydride, 1 part of 1-methylimidazole, 25 parts of boron nitride, 0.05 parts of polyaniline, and 25 parts of octaaminophenyl cage-like silsesquioxane modified composite mica powder as raw materials for later use; add the bisphenol A type epoxy resin, methyltetrahydrophthalic anhydride, 1-methylimidazole, boron nitride, and octaaminophenyl cage-like silsesquioxane modified composite mica powder into a mixing tank preheated to 70°C according to the component ratio, keep warm and mix at a stirring rate of 100 r / min for 2 hours, add polyaniline, keep warm and mix at a stirring rate of 100 r / min for 3 hours, finally add to the mold, first cure at 110°C for 6 hours, then cure at 150°C for 10 hours to obtain a thermally conductive and insulating epoxy resin material.

[0045] Comparative Example 1 This comparative example is the same as Example 1, except that the composite mica powder, which is a mixture of dry-ground mica powder and wet-ground mica powder, is replaced with a single dry-ground mica powder.

[0046] Comparative Example 2 This comparative example is the same as Example 1, except that the composite mica powder, which is a mixture of dry-ground mica powder and wet-ground mica powder, is replaced with a single wet-ground mica powder.

[0047] Comparative Example 3 This comparative example is the same as Example 1, except that the octaaminophenyl cage-like silsesquioxane modified composite mica powder in S4 is replaced with the composite mica powder in S1.

[0048] Comparative Example 4 This comparative example is the same as Example 1, except that in step S4, 100 parts by weight of bisphenol A type epoxy resin, 60 parts by weight of phthalic anhydride, 0.1 parts by weight of 2-ethyl-4-methylimidazole, 20 parts by weight of boron nitride, 0.03 parts by weight of polyaniline, and 20 parts by weight of octaaminophenyl cage-like silsesquioxane modified composite mica powder are prepared as raw materials. The bisphenol A type epoxy resin, polyaniline, phthalic anhydride, 2-ethyl-4-methylimidazole, boron nitride, and octaaminophenyl cage-like silsesquioxane modified composite mica powder are added to a mixing tank preheated to 70°C according to the component ratio, kept at the temperature, and mixed at a stirring rate of 100 r / min for 5 h. The mixture is then added to a mold and cured at 100°C for 5 h, and then cured at 140°C for 9 h to obtain a thermally conductive and insulating epoxy resin material.

[0049] Test case (1) Thermal conductivity test Thermal conductivity was tested using a hot disk thermal conductivity meter on a disc-shaped resin material. The sample was a disc with a diameter of 40 mm and a height of 10 mm.

[0050] (2) Resistivity test The volume resistivity was tested according to GB / T 1410-2006 Test Method for Volume Resistivity and Surface Resistivity of Solid Insulating Materials. The sample was a circular disc with a diameter of 18 mm and a height of 1 mm, and the test voltage was 1000 V.

[0051] (3) Water absorption rate test The sample was a circular piece with a diameter of 40 mm and a height of 10 mm. It was placed at 85°C and 85% humidity for 48 hours, and the weight change of the sample was measured as the water absorption rate.

[0052] Table 1 Test Results

[0053] As shown in Table 1, in Comparative Example 1, replacing the composite mica powder (a mixture of dry-milled and wet-milled mica powder) with a single dry-milled mica powder significantly deteriorated both its thermal conductivity and resistivity. This is because dry-milled mica powder has a rough surface, numerous defects, and a small aspect ratio, making it difficult to form a synergistic stacking effect with boron nitride in the resin when used alone. This leads to an increase in interfacial thermal resistance and a significant decrease in thermal conductivity. Simultaneously, surface defects and impurities may act as conductive channels or cause electric field concentration, resulting in a sharp decrease in resistivity by two orders of magnitude. In Comparative Example 2, replacing the composite mica powder (a mixture of dry-milled and wet-milled mica powder) with a single wet-milled mica powder significantly deteriorated its thermal conductivity and water absorption rate. This is because the single wet-milled mica powder has a smooth surface and is not evenly dispersed during preparation, resulting in localized stacking and agglomeration. This not only prevents boron nitride from forming an efficient thermal conduction pathway but also introduces more agglomerated interfacial defects. These defects provide channels for water molecule penetration and aggregation, leading to a significant increase in water absorption. The incorporation of dry-milled mica powder plays a synergistic dispersing role. Its relatively rough surface helps to break up the agglomeration of wet-milled mica powder, promoting the uniform distribution of filler in the resin matrix, thereby constructing a more complete thermally conductive network and a denser microstructure, improving thermal conductivity while reducing water absorption. In Comparative Example 3, after replacing the octaaminophenyl cage-like silsesquioxane modified composite mica powder with unmodified composite mica powder, its thermal conductivity and resistivity both deteriorated significantly, and its water absorption increased. This is because the unmodified mica powder has poor compatibility with the epoxy resin matrix, with obvious voids and defects at the interface, forming strong local electric field concentration points, leading to a significant decrease in thermal conductivity and resistivity. At the same time, these hydrophilic interface defects are more likely to adsorb moisture, resulting in increased water absorption. In Comparative Example 4, after changing the order of addition of polyaniline (mixing it with all materials), its thermal conductivity, resistivity, and water absorption all showed the most severe deterioration. This is because polyaniline, as a conductive material, can have a destructive effect if added too early. The purpose of adding polyaniline is to promote the formation of a more complete thermally conductive network and a denser microstructure together with boron nitride and modified mica powder, and to provide moisture protection. However, prolonged blending with all materials causes it to form locally conductive agglomerates in the resin, leading to a decrease in insulation performance. This mixed state also severely interferes with the orderly construction of the thermally conductive network and introduces a large number of interface and pore defects, resulting in a significant decrease in thermal conductivity and a sharp increase in water absorption.

[0054] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A thermally conductive, electrically insulating epoxy resin material, characterized in that, By weight, the raw materials include: 100 parts epoxy resin, 60-80 parts curing agent, 0.1-1 parts accelerator, 20-25 parts boron nitride, 0.03-0.05 parts polyaniline, and 20-25 parts octaaminophenyl cage-like silsesquioxane modified composite mica powder. The composite mica powder is composed of dry-ground mica powder and wet-ground mica powder in a mass ratio of 1:6 to 8.

2. The thermally conductive, electrically insulative epoxy material of claim 1, wherein, The epoxy resin is a bisphenol A type epoxy resin.

3. The thermally conductive, electrically insulative epoxy material of claim 1, wherein, The curing agent is phthalic anhydride or methyltetrahydrophthalic anhydride.

4. The thermally conductive, electrically insulative epoxy material of claim 1, wherein, The accelerator is one of 2-ethyl-4-methylimidazole, 2,4-dimethylimidazole, and 1-methylimidazole.

5. The thermally conductive, electrically insulative epoxy material of claim 1, wherein, The average particle size of the boron nitride is no higher than 1 μm.

6. The thermally conductive, electrically insulative epoxy material of claim 1, wherein, The average particle size of the dry-ground mica powder is 40~50μm.

7. The thermally conductive, electrically insulative epoxy material of claim 1, wherein, The average particle size of the wet-milled mica powder is 30~50μm.

8. A method of producing a thermally conductive, electrically insulating epoxy resin material, characterized by Preparation of the thermally conductive and insulating epoxy resin material according to any one of claims 1 to 7; comprising: S1. Dry-ground mica powder and wet-ground mica powder are mixed at a mass ratio of 1:6 to 8 to obtain composite mica powder. 10g of the composite mica powder is dispersed in 90 to 110mL of anhydrous toluene and ultrasonically dispersed to make the mica uniformly suspended to obtain a suspension. S2. For every 10g of the composite mica powder, add 0.4mL of silane coupling agent KH-560 to the suspension, then add 2-3 drops of deionized water and seal the reaction system. Under nitrogen protection, heat to 105-115℃ and stir under reflux for 8-12h. After the reaction is completed, cool, centrifuge or filter to collect the solid, wash with anhydrous toluene 2-3 times, then wash with anhydrous ethanol 2-3 times, and dry at 45-55℃ for 4-6h to obtain epoxy-oxidized composite mica powder. S3. Dissolve 1g of octaaminophenyl cage-like silsesquioxane in 90-110mL of DMF, then add 10g of the epoxy-modified composite mica powder, ultrasonically disperse for 10-20min, stir and react at 75-85℃ for 12-36h, cool after the reaction, collect the solid by centrifugation or vacuum filtration, wash with anhydrous toluene 2-3 times, then wash with anhydrous ethanol 2-3 times, and dry at 55-65℃ for 8-12h to obtain the octaaminophenyl cage-like silsesquioxane modified composite mica powder; S4, epoxy resin, curing agent, accelerator, boron nitride and octaaminophenyl cage-like silsesquioxane modified composite mica powder are added to a mixing tank preheated to 60~80℃ according to the component ratio. After mixing at this temperature for 2~3 hours, polyaniline is added and mixed at this temperature for another 2~3 hours. Finally, the mixture is added to a mold for segmented curing to obtain the thermally conductive and insulating epoxy resin material.

9. The method for preparing the thermally conductive and insulating epoxy resin material according to claim 8, characterized in that, The segmented curing process involves first curing at 90-110℃ for 4-6 hours, followed by curing at 130-150℃ for 8-10 hours.

10. The method for preparing the thermally conductive and insulating epoxy resin material according to claim 8, characterized in that, The stirring rate of any of the heat-preserving mixtures is 100~150 r / min.

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