A heat-conducting heat-resistant high-temperature stable insulation board

Abstract

The application relates to the technical field of thermal insulation materials, in particular to a high-temperature stable insulation plate with heat conduction and heat resistance, which is used for solving the problems that the existing thermal insulation materials have poor heat conduction and unstable insulation performance under high temperature; the insulation plate is obtained by compounding a heat conduction framework, a flame-retardant heat-resistant prepolymer and a semi-cured sheet of alkali-free glass fiber cloth which is surface-modified through heat treatment and a silane coupling agent, the semi-cured sheets are alternately stacked and placed in a hot press, a ladder curing process is adopted to perform hot pressing forming, and the insulation plate is obtained after cooling, pressure releasing and demolding; a double-continuous interpenetrating network structure of heat conduction phase and flame-retardant heat-resistant phase is constructed in the plate through the reaction-induced phase separation of the heat conduction framework and the flame-retardant heat-resistant prepolymer, the heat conduction path is continuous, the flame-retardant elements are anchored to the crosslinked network through chemical bonds, and the flame-retardant, insulation and heat-resistant performances are synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials technology, specifically to a thermally conductive and heat-resistant high-temperature stable insulation board. Background Technology

[0002] With the rapid development of modern industry, the demand for materials in various high-temperature environments is increasing. In these high-temperature scenarios, materials are required not only to withstand extreme temperature changes, but also to have good thermal stability and certain thermal conductivity. As a material with such special requirements, insulation boards are being used in a wider range of fields, such as electronic equipment, aerospace, petrochemicals and other industries, where they have unique needs.

[0003] However, traditional insulating materials usually have good insulation properties, but they often cannot maintain stable performance under high temperature conditions, thus failing to meet the requirements for use in high-temperature environments. These materials are prone to aging, decomposition, or swelling at high temperatures, affecting the operating efficiency and safety of equipment. Existing thermal insulation materials often experience a decrease in thermal conductivity at high temperatures, making it impossible to maintain excellent insulation performance stably for a long time.

[0004] Therefore, the thermally conductive and heat-resistant high-temperature stable insulation board provided by the present invention is of great significance in the field of thermal insulation material technology. Summary of the Invention

[0005] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a thermally conductive and heat-resistant high-temperature stable insulation board, which solves the problem that existing thermal insulation materials have poor thermal conductivity and unstable insulation performance at high temperatures.

[0006] The objective of this invention can be achieved through the following technical solutions: This application provides a thermally conductive and heat-resistant high-temperature stable insulating board, comprising the following components in parts by weight: 50-70 parts of thermally conductive skeleton, 30-50 parts of flame-retardant and heat-resistant prepolymer, 5-8 parts of silane coupling agent treatment liquid and 55-60 parts of glass fiber cloth. The silane coupling agent treatment solution is composed of silane coupling agent of model KH550, deionized water and anhydrous ethanol in a ratio of 20g:1000mL:200mL; the glass fiber cloth is 06 alkali-free glass fiber cloth.

[0007] In a preferred embodiment of the present invention, the thermally conductive skeleton is prepared by the following steps: Step a1: Add anhydrous ethanol and silane coupling agent to a three-necked flask equipped with a stirrer and thermometer, mix and stir for 30 min, adjust the pH to 4.5-5 with glacial acetic acid, hydrolyze at 25℃ for 30 min, add boron nitride nanotubes, ultrasonically disperse at 300 W and 20 kHz for 30 min, transfer to an oil bath at 75℃, stir and react at 300 r / min for 4 h, after the reaction is completed, vacuum filter with a filter membrane with a pore size of 0.22 μm, wash the filter cake 2-3 times with distilled water, place in a vacuum drying oven, vacuum dry at 80℃ for 12 h to obtain modified boron nitride nanotubes; Step a2: Add biphenyl-type liquid crystal epoxy resin to a flask, immerse it in an oil bath, heat it to 100℃, stir it at a constant speed of 150-200 r / min for 30 min, cool it to 90℃, add modified boron nitride nanotubes, shear and disperse it at a speed of 1300-1500 r / min for 1-2 h, apply pulsed ultrasound with a power of 200W to assist dispersion, then continue stirring at 800 r / min, while applying a constant magnetic field of 0.3-0.5T along the stirring axis, add imidazole accelerator, continue stirring for 30 min, heat the oil bath to 120℃, stir the reaction at a speed of 300-400 r / min under nitrogen protection for 0.5-1 h, remove it from the oil bath after the reaction is complete, and cool it to 25℃ in an ice-water bath of 0-5℃ to obtain a thermally conductive framework.

[0008] In a preferred embodiment of the present invention, the ratio of anhydrous ethanol, silane coupling agent, and boron nitride nanotubes in step a1 is 200-250 mL: 2-3 mL: 10-13 g; the silane coupling agent is KH-550; and the boron nitride nanotubes have a diameter of 20-50 nm and a length of 5-30 μm.

[0009] In a preferred embodiment of the present invention, the ratio of the biphenyl-type liquid crystal epoxy resin, the modified boron nitride nanotubes, and the imidazole accelerator in step a2 is 90-100g: 12-18g: 0.3-0.8g; the biphenyl-type liquid crystal epoxy resin is 4,4'-biphenyl diglycidyl ether; and the imidazole accelerator is 2-ethyl-4-methylimidazole.

[0010] In a preferred embodiment of the present invention, the flame-retardant and heat-resistant prepolymer is prepared by the following steps: Step b1: Add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the first portion of 1,4-dioxane to a three-necked flask equipped with a stirrer and thermometer. Mix and stir at 150-200 r / min for 30 min at 25°C. Immerse in an oil bath and reflux at 85°C. Add p-nitrobenzaldehyde and the second portion of 1,4-dioxane to a beaker. Mix and stir for 30 min. Transfer to a constant pressure dropping funnel and add dropwise to the above three-necked flask at a rate of 3-4 mL / min. Add catalyst. Raise the oil bath temperature to 100°C and react under reflux for 5-6 h. After the reaction is complete, cool naturally to 25°C and pour into deionized water. A white solid precipitate will precipitate. Filter with a Buchner funnel and wash the filter cake 2-3 times with distilled water to obtain the intermediate product. Step b2: Add the intermediate product to a high-pressure reactor, along with anhydrous ethanol and palladium-on-carbon catalyst. Seal the reactor and purge the air inside with nitrogen 2-3 times, then purge the nitrogen with hydrogen 2-3 times. Finally, purge with hydrogen until the pressure reaches 0.8 MPa. Start the stirring at 400-500 rpm and heat the reactor to 50-55°C. Under isothermal and pressure-controlled conditions, carry out the catalytic hydrogenation reaction for 6-8 hours, continuously purging with hydrogen to maintain a pressure of 0.8 MPa during the reaction. After the reaction is complete, the mixture is naturally cooled to 25°C and then vacuum filtered through a 0.45 μm filter membrane. The filtrate is transferred to a round-bottom flask and placed on a rotary evaporator. It is then distilled under reduced pressure at a water bath temperature of 45°C and a vacuum degree of -0.095 MPa for 3-5 hours. Ethyl acetate is added, and the mixture is stirred for 30 minutes. The mixture is washed 1-2 times with saturated brine. The organic phases are combined, and anhydrous magnesium sulfate is added and dried for 24 hours. The mixture is then filtered, and the filtrate is distilled under reduced pressure at 45°C for 2-3 hours to obtain the flame-retardant curing agent. Step b3: Add epoxy resin and 4,4'-bismaleimide diphenylmethane to a three-necked flask equipped with a stirrer and thermometer, immerse in an oil bath, heat to 130°C, mix and stir at 200-250 r / min for 30-40 min to obtain a copolymer, cool to 110°C, add flame retardant curing agent while stirring at 200 r / min, increase the stirring speed to 400 r / min, and perform a constant temperature prepolymerization reaction at 110°C for 45-50 min. After the reaction is complete, remove the flask and cool it to 25°C in an ice-water bath at 0-5°C to obtain a flame retardant and heat-resistant prepolymer.

[0011] In a preferred embodiment of the present invention, the ratio of the amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, the total amount of 1,4-dioxane, p-nitrobenzaldehyde, catalyst, and deionized water in step b1 is 18-20g: 150-200mL: 10-15g: 0.3-0.8g: 300-400mL; the first part of 1,4-dioxane accounts for 2 / 3 of the total amount of 1,4-dioxane; the second part of 1,4-dioxane accounts for 1 / 3 of the total amount of 1,4-dioxane; and the catalyst is zinc chloride.

[0012] In a preferred embodiment of the present invention, the ratio of the intermediate product, anhydrous ethanol, palladium on carbon catalyst, ethyl acetate and anhydrous magnesium sulfate in step b2 is 25-28g: 200-250mL: 1-2g: 40-50mL: 5-8g; the CAS number of the palladium on carbon catalyst is 7440-05-3.

[0013] In a preferred embodiment of the present invention, the ratio of epoxy resin, 4,4'-bismaleimide diphenylmethane, and flame retardant curing agent in step b3 is 50-60g: 12-18g: 20-30g; the epoxy resin is bisphenol A diglycidyl ether.

[0014] In a preferred embodiment of the present invention, the thermally conductive and heat-resistant high-temperature stable insulating board is prepared by the following steps: Step 1: Weigh out 50-70 parts of thermally conductive skeleton, 30-50 parts of flame-retardant and heat-resistant prepolymer, 40-60 parts of toluene, 40-60 parts of anhydrous ethanol, 5-8 parts of silane coupling agent treatment solution, and 55-60 parts of glass fiber cloth according to the following weight proportions. Step 2: Cut the fiberglass cloth and lay it flat in a muffle furnace. Heat it to 400℃ at a rate of 2-5℃ / min, and maintain the temperature for 1.5-2 hours. Cool it to 25℃ in the furnace and immerse it in a silane coupling agent treatment solution for 10-15 minutes. After immersion, remove it and hang it vertically to air dry for 30 minutes. Transfer it to a forced-air drying oven and bake it at 120℃ for 1-2 hours to obtain modified fiberglass cloth. Mix the thermally conductive skeleton, flame-retardant and heat-resistant prepolymer, toluene, and anhydrous ethanol and stir for 30 minutes to obtain... The modified glass fiber cloth is impregnated with the adhesive solution, and the adhesive content is controlled to be 42-46% to obtain a semi-cured sheet. 10-20 layers of semi-cured sheets are alternately stacked and placed in a hot press. The hot press is formed by a stepped curing process. The mold is closed at 25°C, the temperature is raised to 120°C and a pressure of 7MPa is applied, the temperature is raised to 150°C and the pressure is held for 30 minutes and then increased to 20MPa. The temperature is raised to 180°C and held for 2 hours, the temperature is raised to 210°C and held for 3 hours. After natural cooling to 25°C, the pressure is released and the mold is demolded to obtain a thermally conductive and heat-resistant high-temperature stable insulation board.

[0015] The beneficial effects of this invention are: This invention discloses a thermally conductive and heat-resistant high-temperature stable insulating board. The process involves cutting and heat-treating glass fiber cloth, impregnating it with a silane coupling agent solution, and then air-drying and baking it to obtain modified glass fiber cloth. A thermally conductive skeleton, a flame-retardant and heat-resistant prepolymer, toluene, and anhydrous ethanol are mixed to obtain an adhesive solution. The modified glass fiber cloth is then impregnated with the adhesive solution to obtain a prepreg. The prepregs are alternately stacked and placed in a hot press, where a stepped curing process is used for hot pressing and molding. After cooling, the pressure is released and the board is demolded to obtain the thermally conductive and heat-resistant high-temperature stable insulating board. The self-orientation of the molecular chains of the biphenyl-type liquid crystal epoxy resin under magnetic field induction and the through-hole thermally conductive network formed by high thermal conductivity boron nitride nanotubes improve the heat transfer efficiency. The boron nitride nanotubes themselves are insulators, which do not degrade the resistivity, resulting in a high volume resistivity and good insulation performance. The orientation of the liquid crystal epoxy resin endows the material with high phonon conduction efficiency along the orientation direction, giving the insulating board excellent network-through thermal conductivity. The imide heterocycles and rigid benzene ring cross-linked structure formed by bismaleimide diphenylmethane with epoxy resin and aromatic amine curing agent, as well as the rigidity of the main chain of the liquid crystal epoxy itself, prevent the material from softening and deforming under long-term high-temperature conditions, resulting in good heat resistance. At the same time, the flame-retardant curing agent is embedded in the epoxy cross-linked network through chemical bonds, forming an intrinsic flame-retardant structure, which also gives the material a flame-retardant effect.

[0016] In the preparation of a thermally conductive and heat-resistant high-temperature stable insulating board, a thermally conductive framework was first prepared. A silane coupling agent was hydrolyzed in acidic ethanol, converting ethoxy groups to silanol groups, generating a highly active silanol intermediate. The silanol's silanol hydroxyl groups underwent dehydration condensation with the hydroxyl groups or edge defect sites on the surface of boron nitride nanotubes, forming stable Si-OB covalent bonds. Organic segments with active amino groups at the ends of the coupling agent molecules were chemically anchored to the surface of the boron nitride nanotubes, resulting in amino-functionalized modified boron nitride nanotubes. The active amino groups introduced onto the surface of this modified product can participate in the subsequent ring-opening curing reaction of the epoxy resin. The boron nitride nanotubes, which have poor compatibility with the resin and are prone to aggregation, are chemically embedded into the epoxy crosslinking network, achieving interfacial chemical bridging between the filler and the matrix. This reduces phonon scattering and interfacial thermal resistance, improves thermal conductivity, avoids filler migration and interfacial delamination, and ensures the synergistic stability of the insulating board's thermal conductivity and insulation performance under long-term high-temperature operation. Under the catalysis of imidazole accelerators, the epoxy groups of the preheated biphenyl-type liquid crystal epoxy resin undergo ring-opening addition reactions with the primary amine groups anchored on the surface of modified boron nitride nanotubes to generate β-hydroxyamine structural segments. The boron nitride nanotubes are then grafted onto the molecular chain backbone of the liquid crystal epoxy resin through these covalent bonds, resulting in a thermally conductive framework. Under the synergistic effect of an external magnetic field and high-speed shear flow, the rigid mesocrystalline units of the biphenyl-type liquid crystal epoxy resin undergo pre-oriented molecular chain segment alignment along the magnetic field direction. The boron nitride nanotubes also form a preferred alignment along the orientation direction along with the resin flow, constructing a through-through thermally conductive pathway with orientation characteristics. The prepolymerization reaction firmly locks the high thermal conductivity boron nitride nanotubes into the resin matrix through covalent bonds, avoiding the random distribution of fillers and high interfacial thermal resistance in ordinary physical blending. At the same time, the orientation alignment of the liquid crystal epoxy resin endows the material with higher phonon conduction efficiency along the orientation direction, enabling the insulating board to obtain excellent network through-through thermal conductivity in the vertical direction.

[0017] In the preparation of a thermally conductive and heat-resistant high-temperature stable insulating board, a flame-retardant and heat-resistant prepolymer was first prepared. The PH bond in the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide structure underwent a nucleophilic addition reaction with p-nitrobenzaldehyde under catalyst catalysis. The phosphorus atom nucleophilically attacked the aldehyde carbon, generating an α-hydroxyphosphonate intermediate containing a PC bond. Through this one-step reaction, the phosphaphenanthrene group, which has a highly efficient gas-phase free radical scavenging function, and the nitrophenyl group, which can be converted into an active amino group, were simultaneously introduced into the same molecular skeleton. This allowed the flame-retardant element phosphorus to react with the potentially active curing reaction site nitrogen in the molecular water... The chemical bonding on the surface of the resin lays the structural foundation for the subsequent preparation of intrinsic reactive flame retardant curing agents, avoiding the defects of poor compatibility and easy migration and precipitation of traditional physically blended flame retardants with resins. The nitro group on the benzene ring of the intermediate product undergoes a heterogeneous catalytic hydrogenation reduction reaction with hydrogen on the surface of a palladium-carbon catalyst. The nitro group successively passes through nitroso and hydroxylamine intermediates, and is finally reduced to a primary amino group, yielding the flame retardant curing agent. The contained primary amino group can undergo ring-opening addition reactions with epoxy groups, embedding itself into the epoxy crosslinking network in the form of chemical bonds, eliminating the deteriorating effect of free flame retardants on insulation performance. The phosphoranthroline structure in the molecular skeleton... During warm or burning, phosphorus-containing free radicals are released through decomposition, capturing hydrogen and hydroxyl radicals that promote the combustion chain reaction. In the gas phase, these free radicals act as flame retardants, blocking combustion, while simultaneously promoting dehydration and char formation on the resin surface to create a condensed phase barrier. Phosphorus reacts with the inherent nitrogen element in the molecule to produce a phosphorus-nitrogen synergistic flame retardant effect, significantly improving flame retardant efficiency while maintaining excellent electrical insulation and heat resistance. At high temperatures, epoxy resin and 4,4'-bismaleimide diphenylmethane undergo a Michael addition reaction between the bismaleimide double bond and the secondary hydroxyl group in the epoxy resin, forming a copolymer. The added flame retardant curing agent has a primary amine... The radical undergoes a ring-opening addition reaction with the residual epoxy groups in the epoxy resin, introducing the structural units containing phosphorus-containing phenanthrene and nitrogen-containing benzene rings into the prepolymer chain segment through CN covalent bonds to obtain a flame-retardant and heat-resistant prepolymer. Through chemical prepolymerization, the rigid structure of the bismaleimide imide heterocyclic ring, the phosphorus-containing phenanthrene flame-retardant unit, and the tough skeleton of the epoxy resin are pre-connected into a low-crosslinking intermediate. During the hot pressing of the laminate, this prepolymer can form an independent high-flame-retardant and heat-resistant phase through reaction-induced phase separation. This phase is rich in high-density aromatic heterocycles and phosphorus-nitrogen synergistic structure, giving the board excellent thermomechanical stability that maintains high strength even at high temperatures. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1:

[0020] This embodiment describes a thermally conductive and heat-resistant high-temperature stable insulating board, which is prepared by the following steps: Step S1: Add 200 mL of anhydrous ethanol and 2 mL of silane coupling agent KH-550 to a three-necked flask equipped with a stirrer and thermometer. Mix and stir for 30 min. Adjust the pH to 4.5 with glacial acetic acid. Hydrolyze at 25 °C for 30 min. Add 10 g of boron nitride nanotubes. Sonicate at 300 W and 20 kHz for 30 min. Transfer to an oil bath at 75 °C and stir at 300 r / min for 4 h. After the reaction is complete, filter under vacuum through a 0.22 μm pore size filter membrane. Wash the filter cake twice with distilled water. Place in a vacuum drying oven and vacuum dry at 80 °C for 12 h to obtain modified boron nitride nanotubes. The diameter of the boron nitride nanotubes is 20 nm and the length is 5 μm. Step S2: Add 90g of 4,4'-biphenyl diglycidyl ether to a flask, immerse it in an oil bath, heat it to 100℃, stir it at a constant speed of 150r / min for 30min, cool it to 90℃, add 12g of modified boron nitride nanotubes, shear and disperse it at a speed of 1300r / min for 1h, apply pulsed ultrasound with a power of 200W to assist dispersion, then continue stirring at 800r / min, while applying a constant magnetic field of 0.3T along the stirring axis, add 0.3g of 2-ethyl-4-methylimidazole, continue stirring for 30min, heat the oil bath to 120℃, stir the reaction at a speed of 300r / min for 0.5h under nitrogen protection, remove it from the oil bath, and cool it to 25℃ in an ice-water bath at 0℃ to obtain a thermally conductive framework; Step S3: Add 18g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 100mL of 1,4-dioxane to a three-necked flask equipped with a stirrer and thermometer. Mix and stir at 150r / min for 30min at 25℃. Immerse in an oil bath and reflux at 85℃. Add 10g of p-nitrobenzaldehyde and 50mL of 1,4-dioxane to a beaker. Mix and stir for 30min. Transfer to a constant pressure dropping funnel and add dropwise to the above three-necked flask at a rate of 3mL / min. Add 0.3g of zinc chloride. Raise the oil bath temperature to 100℃ and react at reflux for 5h. After the reaction is complete, cool naturally to 25℃ and pour into 300mL of deionized water. A white solid precipitate precipitates. Filter with a Buchner funnel and wash the filter cake twice with distilled water to obtain the intermediate product. Step S4: Add 25g of intermediate product to a high-pressure reactor, along with 200mL of anhydrous ethanol and 1g of palladium on carbon catalyst. Seal the reactor, purge the air inside with nitrogen twice, then purge the nitrogen twice with hydrogen. Finally, purge with hydrogen until the pressure reaches 0.8MPa. Start the stirring at 400r / min and heat the reactor to 50℃. Perform the catalytic hydrogenation reaction under constant temperature and pressure conditions for 6 hours. During the reaction, continuously purge with hydrogen to maintain the pressure at 0.8MPa. After the reaction is complete, allow it to cool naturally to 25℃. The solution was vacuum filtered through a 0.45 μm filter membrane at ℃, and the filtrate was transferred to a round-bottom flask and placed on a rotary evaporator. It was then distilled under reduced pressure for 3 hours at a water bath temperature of 45℃ and a vacuum degree of -0.095 MPa. 40 mL of ethyl acetate was added, and the mixture was stirred for 30 minutes. The mixture was washed once with saturated brine, and the organic phases were combined. 5 g of anhydrous magnesium sulfate was added, and the mixture was dried for 24 hours. The solution was filtered, and the filtrate was distilled under reduced pressure at 45℃ for 2 hours to obtain the flame-retardant curing agent. The CAS number of the palladium-on-carbon catalyst is 7440-05-3. Step S5: Add 50g of bisphenol A diglycidyl ether and 12g of 4,4'-bismaleimide diphenylmethane to a three-necked flask equipped with a stirrer and thermometer, immerse it in an oil bath, heat to 130℃, mix and stir at 200r / min for 30min to obtain a copolymer, cool to 110℃, add 20g of flame retardant curing agent while stirring at 200r / min, increase the stirring speed to 400r / min, and prepolymerize at 110℃ for 45min. After the reaction is complete, remove the flask and cool it to 25℃ in an ice-water bath at 0℃ to obtain a flame retardant and heat-resistant prepolymer. Step S6: Weigh out 50 parts by weight of the thermally conductive skeleton, 30 parts by weight of the flame-retardant and heat-resistant prepolymer, 40 parts by weight of toluene, 40 parts by weight of anhydrous ethanol, 5 parts by weight of the silane coupling agent treatment solution, and 55 parts by weight of the glass fiber cloth; the silane coupling agent treatment solution is prepared by mixing silane coupling agent of type KH550, deionized water, and anhydrous ethanol in a dosage ratio of 20g:1000mL:200mL; the glass fiber cloth is 06 alkali-free glass fiber cloth; Step S7: Cut the glass fiber cloth and lay it flat in a muffle furnace. Heat it to 400℃ at a heating rate of 2℃ / min and maintain the temperature for 1.5 hours. Cool it to 25℃ in the furnace and immerse it in a silane coupling agent treatment solution for 10 minutes. After immersion, remove it and hang it vertically to air dry for 30 minutes. Transfer it to a forced-air drying oven and bake it at 120℃ for 1 hour to obtain modified glass fiber cloth. Mix the thermally conductive skeleton, flame-retardant and heat-resistant prepolymer, toluene, and anhydrous ethanol for 30 minutes to obtain... Adhesive solution; Modified glass fiber cloth is impregnated with the adhesive solution, and the adhesive content is controlled at 42% to obtain a prepreg; Ten layers of prepreg are alternately stacked and placed in a hot press, and hot-pressed using a stepped curing process. The mold is closed at 25°C, the temperature is raised to 120°C and a pressure of 7MPa is applied, the temperature is raised to 150°C and held for 30 minutes and then the pressure is increased to 20MPa, the temperature is raised to 180°C and held for 2 hours, the temperature is raised to 210°C and held for 3 hours, and after natural cooling to 25°C, the pressure is released and the mold is demolded to obtain a thermally conductive and heat-resistant high-temperature stable insulation board.

[0021] Example 2:

[0022] This embodiment describes a thermally conductive and heat-resistant high-temperature stable insulating board, which is prepared by the following steps: Step S1: Add 225 mL of anhydrous ethanol and 2.5 mL of silane coupling agent KH-550 to a three-necked flask equipped with a stirrer and thermometer. Mix and stir for 30 min. Adjust the pH to 5 with glacial acetic acid. Hydrolyze at 25 °C for 30 min. Add 12 g of boron nitride nanotubes. Sonicate at 300 W and 20 kHz for 30 min. Transfer to an oil bath at 75 °C and stir at 300 r / min for 4 h. After the reaction is complete, filter under vacuum through a 0.22 μm pore size filter membrane. Wash the filter cake three times with distilled water. Place in a vacuum drying oven and vacuum dry at 80 °C for 12 h to obtain modified boron nitride nanotubes. The diameter of the boron nitride nanotubes is 35 nm and the length is 20 μm. Step S2: Add 95g of 4,4'-biphenyl diglycidyl ether to a flask, immerse it in an oil bath, heat it to 100℃, stir it at a constant temperature of 175r / min for 30min, cool it to 90℃, add 15g of modified boron nitride nanotubes, shear and disperse it at 1400r / min for 1.5h, apply pulsed ultrasound with a power of 200W to assist dispersion, then continue stirring at 800r / min, while applying a constant magnetic field of 0.4T along the stirring axis, add 0.5g of 2-ethyl-4-methylimidazole, continue stirring for 30min, heat the oil bath to 120℃, stir it at 350r / min for 1h under nitrogen protection, after the reaction is complete, remove it from the oil bath, cool it to 25℃ in an ice-water bath at 3℃ to obtain a thermally conductive framework; Step S3: Add 19g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 125mL of 1,4-dioxane to a three-necked flask equipped with a stirrer and thermometer. Mix and stir at 175r / min for 30min at 25℃. Immerse in an oil bath and reflux at 85℃. Add 13g of p-nitrobenzaldehyde and 50mL of 1,4-dioxane to a beaker. Mix and stir for 30min. Transfer to a constant pressure dropping funnel and add dropwise to the above three-necked flask at a rate of 3.5mL / min. Add 0.5g of zinc chloride. Raise the oil bath temperature to 100℃ and react under reflux for 5.5h. After the reaction is complete, cool naturally to 25℃ and pour into 350mL of deionized water. A white solid precipitate precipitates. Filter with a Buchner funnel and wash the filter cake three times with distilled water to obtain the intermediate product. Step S4: Add 27g of intermediate product to a high-pressure reactor, along with 225mL of anhydrous ethanol and 1.5g of palladium on carbon catalyst. Seal the reactor, purge the air inside with nitrogen three times, then purge the nitrogen with hydrogen three times. Finally, purge with hydrogen until the pressure reaches 0.8MPa. Start the stirring at 450r / min and heat the reactor to 53℃. Perform the catalytic hydrogenation reaction under constant temperature and pressure conditions for 7 hours. During the reaction, continuously purge with hydrogen to maintain the pressure at 0.8MPa. After the reaction is complete, allow it to cool naturally to 25℃. The solution was vacuum filtered through a 0.45 μm filter membrane at ℃, and the filtrate was transferred to a round-bottom flask and placed on a rotary evaporator. It was then distilled under reduced pressure at 45℃ and -0.095 MPa for 4 hours. 45 mL of ethyl acetate was added, and the mixture was stirred for 30 minutes. The mixture was washed twice with saturated brine, and the organic phases were combined. 7 g of anhydrous magnesium sulfate was added, and the mixture was dried for 24 hours. The solution was filtered, and the filtrate was distilled under reduced pressure at 45℃ for 2.5 hours to obtain the flame-retardant curing agent. The CAS number of the palladium-on-carbon catalyst is 7440-05-3. Step S5: Add 55g of bisphenol A diglycidyl ether and 15g of 4,4'-bismaleimide diphenylmethane to a three-necked flask equipped with a stirrer and thermometer, immerse it in an oil bath, heat to 130℃, mix and stir at 225r / min for 35min to obtain a copolymer, cool to 110℃, add 25g of flame retardant curing agent while stirring at 200r / min, increase the stirring speed to 400r / min, and prepolymerize at 110℃ for 48min. After the reaction is complete, remove the flask and cool it to 25℃ in an ice-water bath at 3℃ to obtain a flame retardant and heat-resistant prepolymer. Step S6: Weigh out 60 parts by weight of the thermally conductive skeleton, 40 parts by weight of the flame-retardant and heat-resistant prepolymer, 50 parts by weight of toluene, 50 parts by weight of anhydrous ethanol, 7 parts by weight of the silane coupling agent treatment solution, and 58 parts by weight of the glass fiber cloth; the silane coupling agent treatment solution is prepared by mixing silane coupling agent of type KH550, deionized water, and anhydrous ethanol in a ratio of 20g:1000mL:200mL; the glass fiber cloth is 06 alkali-free glass fiber cloth; Step S7: Cut the glass fiber cloth and lay it flat in a muffle furnace. Heat it to 400℃ at a heating rate of 4℃ / min, and heat-treat it at this temperature for 2 hours. Cool it to 25℃ in the furnace and immerse it in a silane coupling agent treatment solution for 13 minutes. After immersion, remove it and hang it vertically to air dry for 30 minutes. Transfer it to a forced-air drying oven and bake it at 120℃ for 1.5 hours to obtain modified glass fiber cloth. Mix the thermally conductive skeleton, flame-retardant and heat-resistant prepolymer, toluene, and anhydrous ethanol and stir for 30 minutes to obtain... Adhesive solution; Modified glass fiber cloth is impregnated with adhesive solution, and the adhesive content is controlled at 44% to obtain a semi-cured sheet; 15 layers of semi-cured sheets are alternately stacked and placed in a hot press, and hot-pressed using a stepped curing process. The mold is closed at 25°C, the temperature is raised to 120°C and a pressure of 7MPa is applied, the temperature is raised to 150°C and held for 30 minutes and then the pressure is increased to 20MPa, the temperature is raised to 180°C and held for 2 hours, the temperature is raised to 210°C and held for 3 hours, and after natural cooling to 25°C, the pressure is released and the mold is demolded to obtain a thermally conductive and heat-resistant high-temperature stable insulation board.

[0023] Example 3:

[0024] This embodiment describes a thermally conductive and heat-resistant high-temperature stable insulating board, which is prepared by the following steps: Step S1: Add 250 mL of anhydrous ethanol and 3 mL of silane coupling agent KH-550 to a three-necked flask equipped with a stirrer and thermometer. Mix and stir for 30 min. Adjust the pH to 5 with glacial acetic acid. Hydrolyze at 25 °C for 30 min. Add 13 g of boron nitride nanotubes. Sonicate at 300 W and 20 kHz for 30 min. Transfer to an oil bath at 75 °C and stir at 300 r / min for 4 h. After the reaction is complete, filter under vacuum through a 0.22 μm pore size filter membrane. Wash the filter cake three times with distilled water. Place in a vacuum drying oven and vacuum dry at 80 °C for 12 h to obtain modified boron nitride nanotubes. The diameter of the boron nitride nanotubes is 50 nm and the length is 30 μm. Step S2: Add 100g of 4,4'-biphenyl diglycidyl ether to a flask, immerse it in an oil bath, heat it to 100℃, stir it at a constant speed of 200r / min for 30min, cool it to 90℃, add 18g of modified boron nitride nanotubes, shear and disperse it at a speed of 1500r / min for 2h, apply pulsed ultrasound with a power of 200W to assist dispersion, then continue stirring at 800r / min, while applying a constant magnetic field of 0.5T along the stirring axis, add 0.8g of 2-ethyl-4-methylimidazole, continue stirring for 30min, heat the oil bath to 120℃, stir it at a speed of 400r / min for 1h under nitrogen protection, after the reaction is completed, remove it from the oil bath, cool it to 25℃ in an ice-water bath at 5℃ to obtain a thermally conductive framework; Step S3: Add 20g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 150mL of 1,4-dioxane to a three-necked flask equipped with a stirrer and thermometer. Mix and stir at 200r / min for 30min at 25℃. Immerse in an oil bath and reflux at 85℃. Add 15g of p-nitrobenzaldehyde and 50mL of 1,4-dioxane to a beaker. Mix and stir for 30min. Transfer to a constant pressure dropping funnel and add dropwise to the above three-necked flask at a rate of 4mL / min. Add 0.8g of zinc chloride. Raise the oil bath temperature to 100℃ and react at reflux for 6h. After the reaction is complete, cool naturally to 25℃ and pour into 400mL of deionized water. A white solid precipitate precipitates. Filter with a Buchner funnel and wash the filter cake three times with distilled water to obtain the intermediate product. Step S4: Add 28g of intermediate product to a high-pressure reactor, along with 250mL of anhydrous ethanol and 2g of palladium on carbon catalyst. Seal the reactor, purge the air inside with nitrogen three times, then purge the nitrogen with hydrogen three times. Finally, purge with hydrogen until the pressure reaches 0.8MPa. Start the stirring at 500r / min and heat the reactor to 55℃. Perform the catalytic hydrogenation reaction under constant temperature and pressure conditions for 8 hours. During the reaction, continuously purge with hydrogen to maintain the pressure at 0.8MPa. After the reaction is complete, allow it to cool naturally to 25℃. The solution was vacuum filtered through a 0.45 μm filter membrane at ℃, and the filtrate was transferred to a round-bottom flask and placed on a rotary evaporator. It was then distilled under reduced pressure for 5 hours at a water bath temperature of 45℃ and a vacuum degree of -0.095 MPa. 50 mL of ethyl acetate was added, and the mixture was stirred for 30 minutes. The mixture was washed twice with saturated brine, and the organic phases were combined. 8 g of anhydrous magnesium sulfate was added and the mixture was dried for 24 hours. The solution was filtered, and the filtrate was distilled under reduced pressure at 45℃ for 3 hours to obtain the flame-retardant curing agent. The CAS number of the palladium-on-carbon catalyst is 7440-05-3. Step S5: Add 60g of bisphenol A diglycidyl ether and 18g of 4,4'-bismaleimide diphenylmethane to a three-necked flask equipped with a stirrer and thermometer, immerse it in an oil bath, heat to 130℃, mix and stir at 250r / min for 40min to obtain a copolymer, cool to 110℃, add 30g of flame retardant curing agent while stirring at 200r / min, increase the stirring speed to 400r / min, and prepolymerize at 110℃ for 50min. After the reaction is complete, remove the flask and cool it to 25℃ in an ice-water bath at 5℃ to obtain a flame retardant and heat-resistant prepolymer. Step S6: Weigh out 70 parts by weight of the thermally conductive skeleton, 50 parts by weight of the flame-retardant and heat-resistant prepolymer, 60 parts by weight of toluene, 60 parts by weight of anhydrous ethanol, 8 parts by weight of the silane coupling agent treatment solution, and 60 parts by weight of the glass fiber cloth; the silane coupling agent treatment solution is prepared by mixing silane coupling agent of type KH550, deionized water, and anhydrous ethanol in a ratio of 20g:1000mL:200mL; the glass fiber cloth is 06 alkali-free glass fiber cloth; Step S7: Cut the glass fiber cloth and lay it flat in a muffle furnace. Heat it to 400℃ at a heating rate of 5℃ / min and maintain the temperature for 2 hours. Cool it to 25℃ in the furnace and immerse it in a silane coupling agent treatment solution for 15 minutes. After immersion, remove it and hang it vertically to air dry for 30 minutes. Transfer it to a forced-air drying oven and bake it at 120℃ for 2 hours to obtain modified glass fiber cloth. Mix the thermally conductive skeleton, flame-retardant and heat-resistant prepolymer, toluene, and anhydrous ethanol for 30 minutes to obtain adhesive. Liquid; impregnate modified glass fiber cloth with adhesive liquid, control the adhesive content to 46%, to obtain a semi-cured sheet; after 20 layers of semi-cured sheets are alternately stacked, they are placed in a hot press and hot-pressed using a stepped curing process. The mold is closed at 25℃, the temperature is raised to 120℃ and a pressure of 7MPa is applied, the temperature is raised to 150℃ and the pressure is held for 30 minutes and then increased to 20MPa, the temperature is raised to 180℃ and held for 2 hours, the temperature is raised to 210℃ and held for 3 hours, and after natural cooling to 25℃, the pressure is released and the mold is demolded to obtain a thermally conductive and heat-resistant high-temperature stable insulation board.

[0025] Comparative Example 1: This comparative example is a thermally conductive and heat-resistant high-temperature stable insulating board, which is prepared by the following steps: Step S1: Weigh out 60 parts by weight of boron nitride, 40 parts by weight of flame retardant, 50 parts by weight of toluene, 50 parts by weight of anhydrous ethanol, 7 parts by weight of silane coupling agent treatment solution, and 58 parts by weight of glass fiber cloth; the silane coupling agent treatment solution is prepared by mixing silane coupling agent of type KH550, deionized water, and anhydrous ethanol in a ratio of 20g:1000mL:200mL; the glass fiber cloth is 06 alkali-free glass fiber cloth; the flame retardant is type JY4-05; Step S2: Cut the fiberglass cloth and lay it flat in a muffle furnace. Heat it to 400℃ at a heating rate of 4℃ / min and maintain the temperature for 2 hours. Cool it to 25℃ in the furnace and immerse it in a silane coupling agent treatment solution for 13 minutes. After immersion, remove it and hang it vertically to air dry for 30 minutes. Transfer it to a forced-air drying oven and bake it at 120℃ for 1.5 hours to obtain modified fiberglass cloth. Mix boron nitride, flame retardant JY4-05, toluene, and anhydrous ethanol and stir for 30 minutes to obtain... The modified glass fiber cloth is impregnated with the adhesive solution, and the adhesive content is controlled to be 44% to obtain a semi-cured sheet. After 15 layers of semi-cured sheets are alternately stacked, they are placed in a hot press and hot-pressed using a stepped curing process. The mold is closed at 25°C, the temperature is raised to 120°C and a pressure of 7MPa is applied, the temperature is raised to 150°C and the pressure is held for 30 minutes and then increased to 20MPa, the temperature is raised to 180°C and held for 2 hours, the temperature is raised to 210°C and held for 3 hours, and after natural cooling to 25°C, the pressure is released and the mold is demolded to obtain a thermally conductive and heat-resistant high-temperature stable insulation board.

[0026] Comparative Example 2: This comparative example is a thermally conductive and heat-resistant high-temperature stable insulating board, which is prepared by the following steps: Step S1: 19g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 125mL of 1,4-dioxane were added to a three-necked flask equipped with a stirrer and thermometer. The mixture was stirred at 175r / min for 30min at 25℃, then immersed in an oil bath and refluxed at 85℃. 13g of p-nitrobenzaldehyde and 50mL of 1,4-dioxane were added to a beaker and stirred for 30min. The mixture was then transferred to a constant pressure dropping funnel and added dropwise to the three-necked flask at a rate of 3.5mL / min. 0.5g of zinc chloride was added, and the oil bath temperature was raised to 100℃. The mixture was refluxed and reacted at a constant temperature for 5.5h. After the reaction was completed, the mixture was naturally cooled to 25℃ and poured into 350mL of deionized water. A white solid precipitate was precipitated. The precipitate was filtered using a Buchner funnel and washed three times with distilled water to obtain the intermediate product. Step S2: Add 27g of intermediate product to a high-pressure reactor, along with 225mL of anhydrous ethanol and 1.5g of palladium on carbon catalyst. Seal the reactor, purge the air inside with nitrogen three times, then purge the nitrogen with hydrogen three times. Finally, purge with hydrogen until the pressure reaches 0.8MPa. Start the stirring at 450r / min and heat the reactor to 53℃. Perform the catalytic hydrogenation reaction under constant temperature and pressure conditions for 7 hours. During the reaction, continuously purge with hydrogen to maintain the pressure at 0.8MPa. After the reaction is complete, allow it to cool naturally to 25℃. The solution was vacuum filtered through a 0.45 μm filter membrane at ℃, and the filtrate was transferred to a round-bottom flask and placed on a rotary evaporator. It was then distilled under reduced pressure at 45℃ and -0.095 MPa for 4 hours. 45 mL of ethyl acetate was added, and the mixture was stirred for 30 minutes. The mixture was washed twice with saturated brine, and the organic phases were combined. 7 g of anhydrous magnesium sulfate was added, and the mixture was dried for 24 hours. The solution was filtered, and the filtrate was distilled under reduced pressure at 45℃ for 2.5 hours to obtain the flame-retardant curing agent. The CAS number of the palladium-on-carbon catalyst is 7440-05-3. Step S3: Add 55g of bisphenol A diglycidyl ether and 15g of 4,4'-bismaleimide diphenylmethane to a three-necked flask equipped with a stirrer and thermometer, immerse it in an oil bath, heat it to 130℃, mix and stir at 225r / min for 35min to obtain a copolymer, cool it to 110℃, add 25g of flame retardant curing agent while stirring at 200r / min, increase the stirring speed to 400r / min, and prepolymerize at 110℃ for 48min. After the reaction is complete, remove it and cool it to 25℃ in an ice-water bath at 3℃ to obtain a flame retardant and heat-resistant prepolymer. Step S4: Weigh out 60 parts by weight of boron nitride, 40 parts by weight of flame-retardant and heat-resistant prepolymer, 50 parts by weight of toluene, 50 parts by weight of anhydrous ethanol, 7 parts by weight of silane coupling agent treatment solution, and 58 parts by weight of glass fiber cloth; the silane coupling agent treatment solution is prepared by mixing silane coupling agent of type KH550, deionized water, and anhydrous ethanol in a dosage ratio of 20g:1000mL:200mL; the glass fiber cloth is 06 alkali-free glass fiber cloth; Step S5: Cut the glass fiber cloth and lay it flat in a muffle furnace. Heat it to 400℃ at a heating rate of 4℃ / min and maintain the temperature for 2 hours. Cool it to 25℃ in the furnace and immerse it in a silane coupling agent treatment solution for 13 minutes. After immersion, remove it and hang it vertically to air dry for 30 minutes. Transfer it to a forced-air drying oven and bake it at 120℃ for 1.5 hours to obtain modified glass fiber cloth. Mix boron nitride, flame-retardant and heat-resistant prepolymer, toluene, and anhydrous ethanol and stir for 30 minutes to obtain... Adhesive solution; Modified glass fiber cloth is impregnated with adhesive solution, and the adhesive content is controlled at 44% to obtain a semi-cured sheet; 15 layers of semi-cured sheets are alternately stacked and placed in a hot press, and hot-pressed using a stepped curing process. The mold is closed at 25°C, the temperature is raised to 120°C and a pressure of 7MPa is applied, the temperature is raised to 150°C and held for 30 minutes and then the pressure is increased to 20MPa, the temperature is raised to 180°C and held for 2 hours, the temperature is raised to 210°C and held for 3 hours, and after natural cooling to 25°C, the pressure is released and the mold is demolded to obtain a thermally conductive and heat-resistant high-temperature stable insulation board.

[0027] Comparative Example 3: This comparative example is a thermally conductive and heat-resistant high-temperature stable insulating board, which is prepared by the following steps: Step S1: Add 225 mL of anhydrous ethanol and 2.5 mL of silane coupling agent KH-550 to a three-necked flask equipped with a stirrer and thermometer. Mix and stir for 30 min. Adjust the pH to 5 with glacial acetic acid. Hydrolyze at 25 °C for 30 min. Add 12 g of boron nitride nanotubes. Sonicate at 300 W and 20 kHz for 30 min. Transfer to an oil bath at 75 °C and stir at 300 r / min for 4 h. After the reaction is complete, filter under vacuum through a 0.22 μm pore size filter membrane. Wash the filter cake three times with distilled water. Place in a vacuum drying oven and vacuum dry at 80 °C for 12 h to obtain modified boron nitride nanotubes. The diameter of the boron nitride nanotubes is 35 nm and the length is 20 μm. Step S2: Add 95g of 4,4'-biphenyl diglycidyl ether to a flask, immerse it in an oil bath, heat it to 100℃, stir it at a constant temperature of 175r / min for 30min, cool it to 90℃, add 15g of modified boron nitride nanotubes, shear and disperse it at 1400r / min for 1.5h, apply pulsed ultrasound with a power of 200W to assist dispersion, then continue stirring at 800r / min, while applying a constant magnetic field of 0.4T along the stirring axis, add 0.5g of 2-ethyl-4-methylimidazole, continue stirring for 30min, heat the oil bath to 120℃, stir it at 350r / min for 1h under nitrogen protection, after the reaction is complete, remove it from the oil bath, cool it to 25℃ in an ice-water bath at 3℃ to obtain a thermally conductive framework; Step S3: Weigh out 60 parts by weight of the thermally conductive skeleton, 40 parts by weight of the flame retardant, 50 parts by weight of the toluene, 50 parts by weight of the anhydrous ethanol, 7 parts by weight of the silane coupling agent treatment solution, and 58 parts by weight of the glass fiber cloth; the silane coupling agent treatment solution is prepared by mixing silane coupling agent of type KH550, deionized water, and anhydrous ethanol in a ratio of 20g:1000mL:200mL; the glass fiber cloth is 06 alkali-free glass fiber cloth; the flame retardant is flame retardant JY4-05; Step S4: Cut the fiberglass cloth and lay it flat in a muffle furnace. Heat it to 400℃ at a heating rate of 4℃ / min and maintain the temperature for 2 hours. Cool it to 25℃ in the furnace and immerse it in a silane coupling agent treatment solution for 13 minutes. After immersion, remove it and hang it vertically to air dry for 30 minutes. Transfer it to a forced-air drying oven and bake it at 120℃ for 1.5 hours to obtain modified fiberglass cloth. Mix the thermally conductive skeleton, flame retardant JY4-05, toluene, and anhydrous ethanol and stir for 30 minutes to obtain... The modified glass fiber cloth is impregnated with the adhesive solution, and the adhesive content is controlled to be 44% to obtain a semi-cured sheet. After 15 layers of semi-cured sheets are alternately stacked, they are placed in a hot press and hot-pressed using a stepped curing process. The mold is closed at 25°C, the temperature is raised to 120°C and a pressure of 7MPa is applied, the temperature is raised to 150°C and the pressure is held for 30 minutes and then increased to 20MPa, the temperature is raised to 180°C and held for 2 hours, the temperature is raised to 210°C and held for 3 hours, and after natural cooling to 25°C, the pressure is released and the mold is demolded to obtain a thermally conductive and heat-resistant high-temperature stable insulation board.

[0028] The thermally conductive and heat-resistant high-temperature stable insulating boards obtained in Examples 1-3 and Comparative Examples 1-3 were tested for thermal conductivity using the hot-wire method according to standard GB / T10297-2015; the test results are shown in the table below:

[0029] The volume resistivity at high temperatures was tested according to standard GB / T 10581-1989; the test results are shown in the table below:

[0030] Comparing Examples 1-3 with Comparative Examples 1-3: Example 1 had lower amounts of raw materials, shorter prepolymerization time, and lower magnetic field strength, resulting in an incomplete orientation network formed by the thermally conductive filler in the resin matrix. The crosslinking density of the flame-retardant and heat-resistant phase and the density of the phosphorus-nitrogen synergistic flame-retardant structure were lower, thus resulting in the lowest thermal conductivity and high-temperature insulation performance. Example 3 had the highest amounts of raw materials. The excessively high filler content made uniform dispersion in the prepolymer difficult, and the larger size of the boron nitride nanotubes made single-unit dispersion and magnetic field orientation difficult, resulting in lower thermal conductivity and high-temperature insulation performance than Example 2. Example 2 had moderate amounts of raw materials, combined with a suitable magnetic field strength, prepolymerization time, and boron nitride nanotube size, enabling the boron nitride nanotubes to achieve monodispersion and highly oriented alignment along the magnetic field direction. The flame-retardant and heat-resistant prepolymer formed a network structure during hot pressing, and the high-density phosphorus-nitrogen synergistic structure of the flame-retardant phase and the ceramic precursor were well distributed. Therefore, Example 2 had higher thermal conductivity and volume resistivity across the entire temperature range. Comparing Example 2 with Comparative Example 1 shows that: Comparative Example 1... Unmodified ordinary boron nitride powder was simply physically blended with the added flame retardant JY4-05, lacking chemical interfacial bonding. Numerous voids existed at the filler-matrix interface, preventing the formation of an effective thermally conductive network. Furthermore, its ionic components became charge carriers under a high-temperature electric field, resulting in poor insulation performance. Comparing Example 2 with Comparative Example 2, although Comparative Example 2 used a flame-retardant and heat-resistant prepolymer as the resin matrix, the thermally conductive filler was unmodified ordinary boron nitride powder, with only weak van der Waals forces between it and the flame-retardant and heat-resistant prepolymer. Due to physical adsorption, the filler is unevenly dispersed and prone to agglomeration, making it impossible to form a continuous and penetrating thermal conductive path. As a result, the overall heat transfer is mainly based on inefficient matrix heat conduction, thus Comparative Example 2 has lower performance. Comparing Example 2 with Comparative Example 3, it can be seen that Comparative Example 3 completely replaces the flame-retardant and heat-resistant prepolymer with the added flame retardant JY4-05. The flame retardant JY4-05 and the thermal conductive skeleton are only physically mixed, and the two have poor compatibility. The flame retardant is dispersed in the skeleton, which breaks the continuity of the thermal conductive network, resulting in a decrease in thermal conductivity compared with Example 2.

[0031] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0032] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A thermally conductive and heat-resistant high-temperature stable insulating board, characterized in that, Includes the following components by weight: 50-70 parts of thermally conductive skeleton, 30-50 parts of flame-retardant and heat-resistant prepolymer, 5-8 parts of silane coupling agent treatment liquid and 55-60 parts of glass fiber cloth. The thermally conductive framework is prepared by the following steps: Step a1: Mix anhydrous ethanol and silane coupling agent, adjust pH with glacial acetic acid, hydrolyze, add boron nitride nanotubes and ultrasonically disperse, stir the reaction in an oil bath, filter under vacuum with a filter membrane, wash the filter cake, and vacuum dry to obtain modified boron nitride nanotubes. Step a2: Add biphenyl-type liquid crystal epoxy resin to a flask, immerse it in an oil bath, heat and stir, cool, add modified boron nitride nanotubes for shear dispersion, use ultrasonic-assisted dispersion, apply a constant magnetic field with the magnetic field direction along the stirring axis, add imidazole accelerator and stir, heat, stir and react under nitrogen protection, cool to obtain a thermally conductive framework.

2. The thermally conductive and heat-resistant high-temperature stable insulating board according to claim 1, characterized in that, The silane coupling agent treatment solution is prepared by mixing silane coupling agent of model KH550, deionized water and anhydrous ethanol in a ratio of 20g:1000mL:200mL; the glass fiber cloth is 06 alkali-free glass fiber cloth.

3. The thermally conductive and heat-resistant high-temperature stable insulating board according to claim 1, characterized in that, In step a1, the ratio of anhydrous ethanol, silane coupling agent, and boron nitride nanotubes is 200-250 mL: 2-3 mL: 10-13 g; the silane coupling agent is KH-550; and the boron nitride nanotubes have a diameter of 20-50 nm and a length of 5-30 μm.

4. The thermally conductive and heat-resistant high-temperature stable insulating board according to claim 1, characterized in that, In step a2, the ratio of the biphenyl-type liquid crystal epoxy resin, modified boron nitride nanotubes, and imidazole accelerator is 90-100g: 12-18g: 0.3-0.8g; the biphenyl-type liquid crystal epoxy resin is 4,4'-biphenyl diglycidyl ether; and the imidazole accelerator is 2-ethyl-4-methylimidazole.

5. The thermally conductive and heat-resistant high-temperature stable insulating board according to claim 1, characterized in that, The flame-retardant and heat-resistant prepolymer is prepared by the following steps: Step b1: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the first portion of 1,4-dioxane were added to a three-necked flask and mixed. The mixture was then immersed in an oil bath and heated to reflux. p-nitrobenzaldehyde and the second portion of 1,4-dioxane were mixed and transferred to a constant pressure dropping funnel and added dropwise to the above three-necked flask. A catalyst was added and the mixture was heated to react. After cooling, the mixture was poured into deionized water, and a white solid precipitate was formed. The precipitate was filtered, and the filter cake was washed to obtain the intermediate product. Step b2: Add the intermediate product, anhydrous ethanol and palladium on carbon catalyst to the reactor, replace the air in the reactor with nitrogen, then replace the nitrogen with hydrogen, and finally introduce hydrogen. Stir, heat and carry out catalytic hydrogenation reaction, cool, vacuum filter, distill the filtrate under reduced pressure, add ethyl acetate and mix, wash with saturated brine, combine the organic phases, add anhydrous magnesium sulfate to dry, filter, distill under reduced pressure to obtain flame retardant curing agent; Step b3: Add epoxy resin and 4,4'-bismaleimide diphenylmethane to a three-necked flask, immerse in an oil bath, heat and stir to obtain a copolymer, cool down, add flame retardant curing agent, and carry out prepolymerization reaction at constant temperature. After the reaction is completed, remove and cool to obtain flame retardant and heat resistant prepolymer.

6. The thermally conductive and heat-resistant high-temperature stable insulating board according to claim 5, characterized in that, In step b1, the ratio of the total amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 1,4-dioxane, p-nitrobenzaldehyde, catalyst, and deionized water is 18-20g: 150-200mL: 10-15g: 0.3-0.8g: 300-400mL; the first part of 1,4-dioxane accounts for 2 / 3 of the total amount of 1,4-dioxane; the second part of 1,4-dioxane accounts for 1 / 3 of the total amount of 1,4-dioxane; the catalyst is zinc chloride.

7. A thermally conductive and heat-resistant high-temperature stable insulating board according to claim 5, characterized in that, The ratio of the intermediate product, anhydrous ethanol, palladium on carbon catalyst, ethyl acetate, and anhydrous magnesium sulfate in step b2 is 25-28g: 200-250mL: 1-2g: 40-50mL: 5-8g; the CAS number of the palladium on carbon catalyst is 7440-05-3.

8. The thermally conductive and heat-resistant high-temperature stable insulating board according to claim 5, characterized in that, In step b3, the ratio of epoxy resin, 4,4'-bismaleimide diphenylmethane, and flame retardant curing agent is 50-60g: 12-18g: 20-30g; the epoxy resin is bisphenol A diglycidyl ether.

9. A thermally conductive and heat-resistant high-temperature stable insulating board according to claim 1, characterized in that, The thermally conductive and heat-resistant high-temperature stable insulating board is prepared by the following steps: Step 1: Weigh out 50-70 parts of thermally conductive skeleton, 30-50 parts of flame-retardant and heat-resistant prepolymer, 40-60 parts of toluene, 40-60 parts of anhydrous ethanol, 5-8 parts of silane coupling agent treatment solution, and 55-60 parts of glass fiber cloth according to the following weight proportions. Step 2: Cut the fiberglass cloth, lay it flat, and place it in a muffle furnace for heat treatment. After cooling, immerse it in a silane coupling agent solution, hang it vertically to air dry, and then bake it with a forced air to obtain modified fiberglass cloth. Mix the thermally conductive skeleton, flame-retardant and heat-resistant prepolymer, toluene, and anhydrous ethanol to obtain an adhesive solution. Impregnate the modified fiberglass cloth with the adhesive solution to obtain a prepreg. Alternately stack the prepregs and place them in a hot press. Use a stepped curing process for hot pressing and molding. After cooling, release the pressure and demold to obtain a thermally conductive and heat-resistant high-temperature stable insulation board.

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