Heat-conducting adhesive and preparation process thereof

Abstract

The invention relates to a heat-conducting adhesive and a preparation process thereof, and relates to the field of heat-conducting adhesive materials. The main material comprises the following components in parts by mass: 40-50 parts of polyimide modified epoxy resin, 14-20 parts of bismaleimide, 4-8 parts of carboxyl-terminated nitrile rubber, 25-35 parts of a curing agent, 5-15 parts of a plasticizer, 1-3 parts of a polymeric dispersant, 3-5 parts of carbon nanotubes and 80-120 parts of a reactive diluent; the auxiliary material comprises the following components in parts by mass: 50-70 parts of magnesium oxide, 10-20 parts of aluminum oxide, 10-18 parts of aluminum nitride and 3-7 parts of a coupling agent. The heat-conducting adhesive prepared by the invention has good heat-conducting property, insulating property, adhesive property and temperature resistance.

Description

Technical Field

[0001] This application relates to the field of thermally conductive adhesive materials, and in particular to a thermally conductive adhesive and its preparation process. Background Technology

[0002] As electronic components become smaller, more powerful, and more integrated, the heat they generate increases dramatically. Efficient heat dissipation has become crucial for ensuring equipment performance and reliability, making thermally conductive adhesives, which combine thermal conductivity and bonding functions, essential in fields such as chip packaging and power device assembly.

[0003] Traditional thermally conductive adhesives are primarily based on silicone resin systems, curing through addition or condensation reactions. These materials have historically met basic heat dissipation and bonding requirements, providing a preliminary solution for thermal management in electronic devices. However, silicone-based thermally conductive adhesives have significant limitations: their thermal conductivity is generally low, making them unsuitable for handling high-power heating; their insulation properties are insufficient, posing safety hazards; and their bond strength and temperature resistance are poor, making them prone to performance degradation under long-term vibration or high-temperature environments. Therefore, they can no longer meet the development requirements of current high-performance electronic devices and need improvement. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a thermally conductive adhesive and its preparation process.

[0005] This application provides a thermally conductive adhesive and its preparation process, which adopts the following technical solution: In a first aspect, this application provides a thermally conductive adhesive, employing the following technical solution: A thermally conductive adhesive includes a main ingredient and auxiliary ingredients, wherein the main ingredient comprises the following components in parts by weight: 40-50 parts of polyimide-modified epoxy resin 14-20 parts of bismaleimide 4-8 parts of carboxyl-terminated nitrile butadiene rubber 25-35 parts of curing agent 5-15 parts plasticizer 1-3 parts of polymeric dispersant 3-5 parts of carbon nanotubes 80-120 parts of reactive diluent; The polyimide-modified epoxy resin is prepared using the following steps: Under a protective atmosphere and stirring conditions, bisphenol A type epoxy resin and triphenylphosphine were mixed, heated, and then added to a polyimide prepolymer solution. The mixture was heated and stirred to react, then cooled and discharged to obtain polyimide modified epoxy resin.

[0006] Polyimide-modified epoxy resin serves as the matrix, introducing heat-resistant rigid segments of polyimide to enhance the thermal stability and bulk strength of the matrix. The added bismaleimide further complements the modified epoxy resin, synergistically constructing a polymer skeleton with superior temperature resistance. Carboxyl-terminated nitrile butadiene rubber, acting as a reactive toughening agent, reacts with epoxy groups to form chemical crosslinks, introducing flexible segments into the cured network. This helps disperse stress, thereby improving the toughness of the adhesive layer and its adhesion to the substrate. Carbon nanotubes, under the action of a polymeric dispersant, are easily dispersed and overlapped within the resin matrix, forming thermally conductive pathways conducive to heat transfer. Simultaneously, the specific electrical insulation properties of the resin, synergistically with the additives, enhance thermal conductivity while maintaining the insulating properties of the adhesive. The curing agent enables the components to form a dense three-dimensional network through chemical reactions, ensuring the dimensional stability and mechanical property retention of the adhesive layer at high temperatures. The synergistic effect of the components in structure, interface, and function results in an adhesive that achieves a good balance in thermal conductivity, insulation, adhesion, and temperature resistance.

[0007] Preferably, the mass ratio of the bisphenol A type epoxy resin, triphenylphosphine and polyimide prepolymer is 1:0.01:(0.2-0.3).

[0008] By limiting the component ratio of polyimide-modified epoxy resin, the microstructure of the modified resin was optimized: bisphenol A type epoxy resin serves as the main reactant and network framework; triphenylphosphine acts as a catalyst to precisely control the reaction rate and extent between epoxy groups and polyimide prepolymer end groups, promoting the formation of a uniform and stable chemical bond between the two; the polyimide prepolymer, according to the above dosage, introduces sufficient heat-resistant and high-strength segments into the epoxy network, while avoiding excessive addition which may lead to phase separation or excessive decrease in the crosslinking density of the matrix itself; the modified resin formed by the above-mentioned reaction ratio combines the adhesiveness of epoxy resin with the heat resistance and rigidity of polyimide, improving the thermal stability and interfacial compatibility of thermally conductive adhesives, thereby enhancing thermal conductivity, insulation performance, adhesive performance, and temperature resistance.

[0009] Preferably, the polyimide prepolymer solution is prepared using the following steps: Under a protective atmosphere, the composite diamine monomer is added to N-methylpyrrolidone. 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is added at 0-5°C with stirring. After stirring and reacting, a polyamic acid solution is obtained. A mixture of acetic anhydride and pyridine is added, and the mixture is heated and stirred to obtain a polyimide prepolymer solution.

[0010] Under a protective atmosphere and polar solvent environment, a low-temperature polycondensation reaction is used to gradually polymerize the composite diamine monomer and aromatic dianhydride to form a polyamic acid intermediate with a controllable structure. Subsequently, a chemical imidization ring-closing process is used to promote the formation of imide rings under relatively mild conditions, thereby obtaining a polyimide prepolymer solution with active groups at the ends of the molecular chains, which can participate in subsequent reactions. The above steps generate a prepolymer with suitable molecular weight and good solubility, which can be uniformly dispersed and effectively chemically bonded in the subsequent modification reaction with epoxy resin, thereby improving the temperature resistance, cohesive strength and interfacial adhesion of the thermally conductive adhesive.

[0011] Preferably, the composite diamine monomer comprises 4,4'-diaminodiphenyl ether and diaminopropyl-terminated polydimethylsiloxane.

[0012] 4,4'-Diaminodiphenyl ether, as a rigid aromatic diamine monomer, constitutes the main chain backbone of polyimide, enhancing its inherent high thermal stability and mechanical strength. Meanwhile, flexible organosilicon segments with active amino groups at both ends act as built-in flexible modules, introducing appropriate flexibility into the polymer backbone. The structure formed by the copolymerization of these two monomers allows the synthesized prepolymer to achieve micro-phase region adjustment of rigidity and flexibility within the cured network during subsequent fusion with epoxy resin. This mitigates internal stress in the material, increases the adhesive layer's resistance to thermal shock or mechanical deformation, enhances the material's toughness and interfacial compatibility with different substrates, thereby improving the performance of the thermally conductive adhesive.

[0013] Preferably, the molar ratio of 4,4'-diaminodiphenyl ether, diaminopropyl-terminated polydimethylsiloxane, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is (0.82-0.88):(0.12-0.18):1.

[0014] The above ratio optimizes the microstructure of the polyimide prepolymer, enabling the prepolymer to contribute to the inherent heat resistance and strength of polyimide while also imparting certain deformation capabilities and internal stress relaxation characteristics to the material through built-in flexible siloxane segments, thereby improving the temperature resistance and adhesion performance of the thermally conductive adhesive.

[0015] Preferably, the carbon nanotubes are replaced with modified copper-plated carbon nanotubes, prepared using the following steps: Copper-plated carbon nanotubes were stirred in an acetic acid solution, washed, and dried to obtain pretreated copper-plated carbon nanotubes. The pretreated copper-plated carbon nanotubes were then added to an ethanol aqueous solution, the pH was adjusted to alkaline, and a mixture of tetraethyl orthosilicate and γ-glycidoxypropyltrimethoxysilane was added. After stirring and reacting, the mixture was centrifuged, washed, and dried to obtain modified copper-plated carbon nanotubes.

[0016] The surface of copper-plated carbon nanotubes is cleaned and activated by acid pickling, and then tetraethyl orthosilicate and silane coupling agent are co-hydrolyzed and condensed under alkaline catalytic conditions. This results in the construction of a composite coating structure on the surface of the copper-plated carbon nanotubes, which contains both an inorganic silica layer and an epoxy functional organic layer. This modification process utilizes the good thermal conductivity of the copper layer itself, while enhancing the bulk electrical insulation of the filler through the silica layer on the surface. The introduced epoxy functional groups can chemically react with the epoxy components in the resin matrix, strengthening the interfacial chemical bonding and stress transfer efficiency between the filler and the matrix. This helps to establish a more stable and low thermal resistance thermally conductive pathway in the adhesive curing network, thereby synergistically optimizing the thermal conductivity, insulation performance, and adhesion performance of the colloid.

[0017] Preferably, the mass ratio of the copper-plated carbon nanotubes, tetraethyl orthosilicate and γ-glycidyl etheroxypropyltrimethoxysilane is 1:0.5:(0.3-0.4).

[0018] By limiting the mass ratio of three key materials in the surface modification process of copper-plated carbon nanotubes, the design and control of the filler interface structure were achieved. Tetraethyl orthosilicate forms a moderately thick, continuous, and complete silica insulating coating layer on the surface of the copper-plated carbon nanotubes, effectively improving the electrical insulation reliability of the filler. An appropriate amount of silane coupling agent grafts a sufficient density of epoxy functional groups onto the silica layer surface, thereby forming a strong chemical bond interface with the resin matrix. This allows the modified filler to utilize the high thermal conductivity of the copper layer and the carbon nanotube core to construct an effective thermal pathway, while ensuring electrical safety through the insulating layer. At the same time, the surface chemical bonding improves its dispersion stability and interfacial stress transfer efficiency in the resin, thereby synergistically optimizing the thermal conductivity, insulation, and overall bonding performance of the thermally conductive adhesive.

[0019] Preferably, the curing agent comprises methylhexahydrophthalic anhydride.

[0020] Methylhexahydrophthalic anhydride can undergo a stepwise ring-opening addition reaction with the epoxy groups in epoxy resins. This process helps to form a three-dimensional network skeleton with a uniform structure and moderate crosslinking density. The reaction characteristics of methylhexahydrophthalic anhydride have good process compatibility and synergy with other reactive components in the formulation, such as polyimide-modified epoxy resin and carboxyl-terminated nitrile rubber. This is beneficial for uniformly introducing rigid and flexible segments into the cured network. The resulting cured product has good thermal and chemical stability, thereby improving the adhesion, insulation and temperature resistance of the adhesive.

[0021] Preferably, the excipients comprise the following components in parts by weight: 50-70 parts magnesium oxide, 10-20 parts aluminum oxide, 10-18 parts aluminum nitride, and 3-7 parts coupling agent.

[0022] Magnesium oxide, with its high thermal conductivity and good insulation, serves as the main framework and basic filler for constructing thermally conductive pathways. Aluminum oxide, with its stable properties, can effectively fill the gaps in the main framework, increasing the packing density, reducing interfacial thermal resistance, and helping to maintain the process flowability of the colloid. Aluminum nitride, with its good thermal conductivity and low dielectric constant, serves as a high-performance thermally conductive reinforcing phase, improving the conduction efficiency of the thermal pathways. The synergistic effect of these three fillers enables the formation of a denser packing and a more continuous heat flow path. Meanwhile, the introduction of coupling agents builds a strong bridge between the inorganic fillers and the organic resin, improving interfacial compatibility. This interfacial strengthening effect not only reduces interfacial thermal resistance caused by phonon scattering but also significantly improves the bonding force between the filler and the matrix, preventing interfacial delamination due to stress or thermal cycling. This synergistically optimizes the thermal conductivity, insulation, and heat resistance of the adhesive.

[0023] Secondly, this application provides a preparation process for a thermally conductive adhesive, employing the following technical solution: A process for preparing a thermally conductive adhesive includes the following steps: S1. Dry magnesium oxide, aluminum oxide and aluminum nitride to obtain dried magnesium oxide, aluminum oxide and aluminum nitride; pre-hydrolyze the silane coupling agent solution and add it to the dried magnesium oxide, aluminum oxide and aluminum nitride, heat and stir to react, filter, wash and dry to obtain the excipient; S2. Add carbon nanotubes and dispersant to solvent, shear and disperse, and ball mill to obtain carbon nanotube slurry; mix polyimide modified epoxy resin, bismaleimide, carboxyl-terminated nitrile rubber, plasticizer and carbon nanotube slurry, heat and stir under vacuum, add auxiliary materials, heat and stir under vacuum, add preheated and melted curing agent, stir until air bubbles are removed, discharge and encapsulate to obtain thermally conductive adhesive.

[0024] The above process, through meticulous material pretreatment and mixing sequence, promotes a strong bond and tight packing between the filler and the matrix, thereby improving the thermal conductivity, insulation properties, adhesion properties and temperature resistance of the adhesive.

[0025] In summary, this application includes at least one of the following beneficial technical effects: Polyimide-modified epoxy resin serves as the matrix, introducing heat-resistant rigid segments of polyimide to enhance the thermal stability and bulk strength of the matrix. The added bismaleimide further complements the modified epoxy resin, synergistically constructing a polymer skeleton with superior temperature resistance. Carboxyl-terminated nitrile butadiene rubber, acting as a reactive toughening agent, reacts with epoxy groups to form chemical crosslinks, introducing flexible segments into the cured network. This helps disperse stress, thereby improving the toughness of the adhesive layer and its adhesion to the substrate. Carbon nanotubes, under the action of a polymeric dispersant, are easily dispersed and overlapped within the resin matrix, forming thermally conductive pathways conducive to heat transfer. Simultaneously, the specific electrical insulation properties of the resin, synergistically with the additives, enhance thermal conductivity while maintaining the insulating properties of the adhesive. The curing agent enables the components to form a dense three-dimensional network through chemical reactions, ensuring the dimensional stability and mechanical property retention of the adhesive layer at high temperatures. The synergistic effect of the components in structure, interface, and function results in an adhesive that achieves a good balance in thermal conductivity, insulation, adhesion, and temperature resistance.

[0026] The surface of copper-plated carbon nanotubes is cleaned and activated by acid pickling, and then tetraethyl orthosilicate and silane coupling agent are co-hydrolyzed and condensed under alkaline catalytic conditions. This results in the construction of a composite coating structure on the surface of the copper-plated carbon nanotubes, which contains both an inorganic silica layer and an epoxy functional organic layer. This modification process utilizes the good thermal conductivity of the copper layer itself, while enhancing the bulk electrical insulation of the filler through the silica layer on the surface. The introduced epoxy functional groups can chemically react with the epoxy components in the resin matrix, strengthening the interfacial chemical bonding and stress transfer efficiency between the filler and the matrix. This helps to establish a more stable and low thermal resistance thermally conductive pathway in the adhesive curing network, thereby synergistically optimizing the thermal conductivity, insulation performance, and adhesion performance of the colloid. Detailed Implementation

[0027] This application discloses a thermally conductive adhesive and its preparation process. Unless otherwise specified, all raw materials used in this application are commercially available. The following detailed description, in conjunction with embodiments, further illustrates this application: Raw material specifications: 4,4'-Diaminodiphenyl ether (CAS No.: 101-80-4), diaminopropyl-terminated polydimethylsiloxane was purchased from Zhengzhou Huiju Chemical Co., Ltd.; 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (CAS No.: 1823-59-2), N-methylpyrrolidone (CAS No.: 872-50-4), acetic anhydride (CAS No.: 108-24-7), pyridine (CAS No.: 110-86-1), bisphenol A type epoxy resin Nanya NPEL-128 was purchased from Shenzhen Weinuohua Chemical Materials Co., Ltd.; triphenylphosphine (CAS No.: 603-35-0), N,N'-(4,4'-methylenediphenyl)bismaleimide was purchased from Wuhan Smike Biotechnology Co., Ltd.; carboxyl-terminated butadiene-acrylonitrile rubber Hypox. RA1340 was purchased from Shanghai Huanyang Chemical Technology Co., Ltd.; methyl hexahydrophthalic anhydride (CAS No.: 19438-64-3); dioctyl phthalate (CAS No.: 117-81-7); high molecular weight dispersant BYK-163 was purchased from Hubei Langbowan Biomedical Co., Ltd.; carbon nanotubes and copper-plated carbon nanotubes were purchased from Guangzhou Hongwu Materials Technology Co., Ltd.; 1,4-butanediol diglycidyl ether (CAS No.: 2425-79-8); γ-glycidyl etheroxypropyltrimethoxysilane (CAS No.: 2530-83-8); magnesium oxide, aluminum oxide and aluminum nitride were purchased from Hubei Chuyuebang New Materials Technology Co., Ltd.; and tetraethyl orthosilicate (CAS No.: 78-10-4). Example 1

[0028] Preparation of polyimide-modified epoxy resin The composite diamine monomers are 4,4'-diaminodiphenyl ether and diaminopropyl-terminated polydimethylsiloxane. The molar ratio of 4,4'-diaminodiphenyl ether, diaminopropyl-terminated polydimethylsiloxane, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is 0.82:0.18:1, and the weight-average molecular weight of diaminopropyl-terminated polydimethylsiloxane is 1000.

[0029] Under a dry nitrogen protective atmosphere, the composite diamine monomer (solid content 15%) was added to N-methylpyrrolidone. 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride was added in three batches under ice-water bath (0-5℃) and stirring at 400 rpm, with the reaction temperature controlled below 20℃. After the addition was complete, the reaction was stirred at 400 rpm for 8 hours to obtain a polyamic acid solution. A mixture of acetic anhydride and pyridine was then added (the amounts of acetic anhydride and pyridine were 2.5 times and 0.75 times the total molar amount of the monomer, respectively). The temperature was raised to 80℃ and the reaction was stirred at 200 rpm for 4 hours to obtain a polyimide prepolymer solution.

[0030] The mass ratio of bisphenol A type epoxy resin, triphenylphosphine and polyimide prepolymer is 1:0.01:0.2, and the type of bisphenol A type epoxy resin is Nanya NPEL-128.

[0031] Under a dry nitrogen protective atmosphere, bisphenol A epoxy resin and triphenylphosphine were mixed and stirred at 300 rpm. The mixture was heated to 120°C and added to the polyimide prepolymer solution. The addition was completed within 1 hour. After the addition was completed, the temperature was raised to 150°C and stirred at 400 rpm for 2 hours. The vacuum was then drawn to <-0.095 MPa, and the solvent and small molecules were removed at 130°C. When the viscosity reached 15000 mPa·s (25°C), the temperature was lowered to 80°C and the material was discharged to obtain polyimide modified epoxy resin.

[0032] Preparation of thermally conductive adhesive Weigh out 40 parts of polyimide-modified epoxy resin, 14 parts of bismaleimide, 4 parts of carboxyl-terminated nitrile butadiene rubber, 25 parts of curing agent, 5 parts of plasticizer, 1 part of polymeric dispersant, 3 parts of carbon nanotubes, and 80 parts of reactive diluent; weigh out 50 parts of magnesium oxide, 10 parts of aluminum oxide, 10 parts of aluminum nitride, and 3 parts of coupling agent; the bismaleimide is N,N'-(4,4'-methylenediphenyl)bismaleimide, and the carboxyl-terminated nitrile butadiene rubber is Hypox. RA1340 uses methylhexahydrophthalic anhydride as the curing agent, dioctyl phthalate as the plasticizer, BYK-163 as the polymeric dispersant, multi-walled carbon nanotubes with an aspect ratio of 500 as the carbon nanotubes, 1,4-butanediol diglycidyl ether as the reactive diluent, γ-glycidyl etheroxypropyltrimethoxysilane as the coupling agent, and has a D50 of 50 μm for magnesium oxide, 5 μm for aluminum oxide, and 50 μm for aluminum nitride.

[0033] S1. Magnesium oxide, aluminum oxide, and aluminum nitride were dried at 110℃ for 2 hours to obtain dried magnesium oxide, aluminum oxide, and aluminum nitride. After pre-hydrolyzing the silane coupling agent in an ethanol aqueous solution (ethanol to water volume ratio of 9:1, solid content 2%) for 30 minutes, it was added to the dried magnesium oxide, aluminum oxide, and aluminum nitride. The mixture was stirred at 500 rpm at 60℃ for 1 hour. After filtration and washing with ethanol, the mixture was dried at 110℃ for 4 hours to obtain the excipient. S2. Add carbon nanotubes and dispersant to reactive diluent, shear and disperse at 2000 rpm for 1 hour, and ball mill for 3 hours to obtain carbon nanotube slurry; mix polyimide modified epoxy resin, bismaleimide, carboxyl-terminated nitrile rubber, plasticizer and carbon nanotube slurry, stir at 200 rpm for 1 hour under 60℃ and -0.095MPa vacuum conditions, add auxiliary materials, stir at 200 rpm for 1.5 hours under 60℃ and -0.095MPa vacuum conditions, cool to below 40℃, add preheated and melted curing agent, complete the addition within 1 hour, reduce the speed to 100 rpm under -0.095MPa vacuum conditions, stir until air bubbles are removed, discharge and encapsulate to obtain thermally conductive adhesive. Example 2

[0034] Preparation of polyimide-modified epoxy resin The composite diamine monomers are 4,4'-diaminodiphenyl ether and diaminopropyl-terminated polydimethylsiloxane. The molar ratio of 4,4'-diaminodiphenyl ether, diaminopropyl-terminated polydimethylsiloxane, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is 0.88:0.12:1, and the weight-average molecular weight of diaminopropyl-terminated polydimethylsiloxane is 1000.

[0035] Under a dry nitrogen protective atmosphere, the composite diamine monomer (solid content 15%) was added to N-methylpyrrolidone. 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride was added in three batches under ice-water bath (0-5℃) and stirring at 400 rpm, with the reaction temperature controlled below 20℃. After the addition was complete, the reaction was stirred at 400 rpm for 8 hours to obtain a polyamic acid solution. A mixture of acetic anhydride and pyridine was then added (the amounts of acetic anhydride and pyridine were 2.5 times and 0.75 times the total molar amount of the monomer, respectively). The temperature was raised to 80℃ and the reaction was stirred at 200 rpm for 4 hours to obtain a polyimide prepolymer solution.

[0036] The mass ratio of bisphenol A type epoxy resin, triphenylphosphine and polyimide prepolymer is 1:0.01:0.3, and the type of bisphenol A type epoxy resin is Nanya NPEL-128.

[0037] Under a dry nitrogen protective atmosphere, bisphenol A epoxy resin and triphenylphosphine were mixed and stirred at 300 rpm. The mixture was heated to 120°C and added to the polyimide prepolymer solution. The addition was completed within 1 hour. After the addition was completed, the temperature was raised to 150°C and stirred at 400 rpm for 2 hours. The vacuum was then drawn to <-0.095 MPa, and the solvent and small molecules were removed at 130°C. When the viscosity reached 15000 mPa·s (25°C), the temperature was lowered to 80°C and the material was discharged to obtain polyimide modified epoxy resin.

[0038] Preparation of thermally conductive adhesive Weigh out 50 parts of polyimide-modified epoxy resin, 20 parts of bismaleimide, 8 parts of carboxyl-terminated nitrile butadiene rubber, 35 parts of curing agent, 15 parts of plasticizer, 3 parts of polymeric dispersant, 5 parts of carbon nanotubes, and 120 parts of reactive diluent; weigh out 70 parts of magnesium oxide, 20 parts of aluminum oxide, 18 parts of aluminum nitride, and 7 parts of coupling agent; the bismaleimide is N,N'-(4,4'-methylenediphenyl)bismaleimide, and the carboxyl-terminated nitrile butadiene rubber is Hypox. RA1340 uses methylhexahydrophthalic anhydride as the curing agent, dioctyl phthalate as the plasticizer, BYK-163 as the polymeric dispersant, multi-walled carbon nanotubes with an aspect ratio of 500 as the carbon nanotubes, 1,4-butanediol diglycidyl ether as the reactive diluent, γ-glycidyl etheroxypropyltrimethoxysilane as the coupling agent, and has a D50 of 50 μm for magnesium oxide, 5 μm for aluminum oxide, and 50 μm for aluminum nitride.

[0039] S1. Magnesium oxide, aluminum oxide, and aluminum nitride were dried at 110℃ for 2 hours to obtain dried magnesium oxide, aluminum oxide, and aluminum nitride. After pre-hydrolyzing the silane coupling agent in an ethanol aqueous solution (ethanol to water volume ratio of 9:1, solid content 2%) for 30 minutes, it was added to the dried magnesium oxide, aluminum oxide, and aluminum nitride. The mixture was stirred at 500 rpm at 60℃ for 1 hour. After filtration and washing with ethanol, the mixture was dried at 110℃ for 4 hours to obtain the excipient. S2. Add carbon nanotubes and dispersant to reactive diluent, shear and disperse at 2000 rpm for 1 hour, and ball mill for 3 hours to obtain carbon nanotube slurry; mix polyimide modified epoxy resin, bismaleimide, carboxyl-terminated nitrile rubber, plasticizer and carbon nanotube slurry, stir at 200 rpm for 1 hour under 60℃ and -0.095MPa vacuum conditions, add auxiliary materials, stir at 200 rpm for 1.5 hours under 60℃ and -0.095MPa vacuum conditions, cool to below 40℃, add preheated and melted curing agent, complete the addition within 1 hour, reduce the speed to 100 rpm under -0.095MPa vacuum conditions, stir until air bubbles are removed, discharge and encapsulate to obtain thermally conductive adhesive. Example 3

[0040] Preparation of polyimide-modified epoxy resin The composite diamine monomers are 4,4'-diaminodiphenyl ether and diaminopropyl-terminated polydimethylsiloxane. The molar ratio of 4,4'-diaminodiphenyl ether, diaminopropyl-terminated polydimethylsiloxane, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is 0.85:0.15:1, and the weight-average molecular weight of diaminopropyl-terminated polydimethylsiloxane is 1000.

[0041] Under a dry nitrogen protective atmosphere, the composite diamine monomer (solid content 15%) was added to N-methylpyrrolidone. 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride was added in three batches under ice-water bath (0-5℃) and stirring at 400 rpm, with the reaction temperature controlled below 20℃. After the addition was complete, the reaction was stirred at 400 rpm for 8 hours to obtain a polyamic acid solution. A mixture of acetic anhydride and pyridine was then added (the amounts of acetic anhydride and pyridine were 2.5 times and 0.75 times the total molar amount of the monomer, respectively). The temperature was raised to 80℃ and the reaction was stirred at 200 rpm for 4 hours to obtain a polyimide prepolymer solution.

[0042] The mass ratio of bisphenol A epoxy resin, triphenylphosphine and polyimide prepolymer is 1:0.01:0.25, and the type of bisphenol A epoxy resin is Nanya NPEL-128.

[0043] Under a dry nitrogen protective atmosphere, bisphenol A epoxy resin and triphenylphosphine were mixed and stirred at 300 rpm. The mixture was heated to 120°C and added to the polyimide prepolymer solution. The addition was completed within 1 hour. After the addition was completed, the temperature was raised to 150°C and stirred at 400 rpm for 2 hours. The vacuum was then drawn to <-0.095 MPa, and the solvent and small molecules were removed at 130°C. When the viscosity reached 15000 mPa·s (25°C), the temperature was lowered to 80°C and the material was discharged to obtain polyimide modified epoxy resin.

[0044] Preparation of thermally conductive adhesive Weigh out 45 parts of polyimide-modified epoxy resin, 17 parts of bismaleimide, 6 parts of carboxyl-terminated nitrile butadiene rubber, 30 parts of curing agent, 10 parts of plasticizer, 2 parts of polymeric dispersant, 4 parts of carbon nanotubes, and 100 parts of reactive diluent; weigh out 60 parts of magnesium oxide, 15 parts of aluminum oxide, 14 parts of aluminum nitride, and 5 parts of coupling agent; the bismaleimide is N,N'-(4,4'-methylenediphenyl)bismaleimide, and the carboxyl-terminated nitrile butadiene rubber is Hypox. RA1340 uses methylhexahydrophthalic anhydride as the curing agent, dioctyl phthalate as the plasticizer, BYK-163 as the polymeric dispersant, multi-walled carbon nanotubes with an aspect ratio of 500 as the carbon nanotubes, 1,4-butanediol diglycidyl ether as the reactive diluent, γ-glycidyl etheroxypropyltrimethoxysilane as the coupling agent, and has a D50 of 50 μm for magnesium oxide, 5 μm for aluminum oxide, and 50 μm for aluminum nitride.

[0045] S1. Magnesium oxide, aluminum oxide, and aluminum nitride were dried at 110℃ for 2 hours to obtain dried magnesium oxide, aluminum oxide, and aluminum nitride. After pre-hydrolyzing the silane coupling agent in an ethanol aqueous solution (ethanol to water volume ratio of 9:1, solid content 2%) for 30 minutes, it was added to the dried magnesium oxide, aluminum oxide, and aluminum nitride. The mixture was stirred at 500 rpm at 60℃ for 1 hour. After filtration and washing with ethanol, the mixture was dried at 110℃ for 4 hours to obtain the excipient. S2. Add carbon nanotubes and dispersant to reactive diluent, shear and disperse at 2000 rpm for 1 hour, and ball mill for 3 hours to obtain carbon nanotube slurry; mix polyimide modified epoxy resin, bismaleimide, carboxyl-terminated nitrile rubber, plasticizer and carbon nanotube slurry, stir at 200 rpm for 1 hour under 60℃ and -0.095MPa vacuum conditions, add auxiliary materials, stir at 200 rpm for 1.5 hours under 60℃ and -0.095MPa vacuum conditions, cool to below 40℃, add preheated and melted curing agent, complete the addition within 1 hour, reduce the speed to 100 rpm under -0.095MPa vacuum conditions, stir until air bubbles are removed, discharge and encapsulate to obtain thermally conductive adhesive. Example 4

[0046] Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that in Example 4, the mass ratio of bisphenol A epoxy resin, triphenylphosphine and polyimide prepolymer is 1:0.01:0.1 when preparing polyimide modified epoxy resin. Example 5

[0047] Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that in Example 5, the mass ratio of bisphenol A epoxy resin, triphenylphosphine and polyimide prepolymer is 1:0.01:0.4 when preparing polyimide modified epoxy resin. Example 6

[0048] Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that in Example 6, the molar ratio of 4,4'-diaminodiphenyl ether, diaminopropyl-terminated polydimethylsiloxane and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride in the polyimide prepolymer used to prepare the polyimide-modified epoxy resin is 0.75:0.25:1. Example 7

[0049] Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that in Example 7, the molar ratio of 4,4'-diaminodiphenyl ether, diaminopropyl-terminated polydimethylsiloxane, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride in the polyimide prepolymer used to prepare the polyimide-modified epoxy resin is 0.95:0.05:1. Example 8

[0050] Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that the polyimide prepolymer solution prepared in Example 8 using the following steps (without adding diaminopropyl-terminated polydimethylsiloxane as a diamine monomer) is prepared when preparing the polyimide-modified epoxy resin.

[0051] The molar ratio of 4,4'-diaminodiphenyl ether and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is 1:1.

[0052] Under a dry nitrogen protective atmosphere, 4,4'-diaminodiphenyl ether was added to N-methylpyrrolidone (solid content 15%). 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride was added in three batches under ice-water bath (0-5℃) and stirring at 400 rpm, with the reaction temperature controlled below 20℃. After the addition was complete, the mixture was stirred at 400 rpm for 8 hours to obtain a polyamic acid solution. A mixture of acetic anhydride and pyridine was then added (acetic anhydride and pyridine were added in amounts of 2.5 times and 0.75 times the total molar amount of the monomer, respectively). The mixture was heated to 80℃ and stirred at 200 rpm for 4 hours to obtain a polyimide prepolymer solution. Example 9

[0053] Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that in Example 9, carbon nanotubes are replaced with modified copper-plated carbon nanotubes. The modified copper-plated carbon nanotubes are prepared using the following steps: Preparation of modified copper-plated carbon nanotubes The mass ratio of copper-plated carbon nanotubes, tetraethyl orthosilicate, and γ-glycidyl etheroxypropyltrimethoxysilane is 1:0.5:0.3. The copper-plated carbon nanotubes are multi-walled carbon nanotubes with an aspect ratio of 500, and the copper content accounts for 30% of the total mass.

[0054] Copper-plated carbon nanotubes were stirred at 200 rpm for 5 min in a 1% (w / w) aqueous acetic acid solution, washed with anhydrous ethanol, and then vacuum dried at 60 °C to obtain pretreated copper-plated carbon nanotubes. The pretreated copper-plated carbon nanotubes were added to an ethanol aqueous solution (ethanol to water volume ratio 4:1, solid content 0.5%), and the pH was adjusted to 9 with 0.5 mol / L ammonia. A mixture of tetraethyl orthosilicate and γ-glycidyl etheroxypropyltrimethoxysilane was added over 2 h. The mixture was stirred at 200 rpm for 12 h, centrifuged, washed with anhydrous ethanol, and vacuum dried at 60 °C to obtain modified copper-plated carbon nanotubes. Example 10

[0055] Example 10 is based on Example 9. The only difference between Example 10 and Example 9 is that the mass ratio of copper-plated carbon nanotubes, tetraethyl orthosilicate and γ-glycidoxypropyltrimethoxysilane in Example 10 is 1:0.5:0.4. Example 11

[0056] Example 11 is based on Example 9. The only difference between Example 11 and Example 9 is that the mass ratio of copper-plated carbon nanotubes, tetraethyl orthosilicate and γ-glycidoxypropyltrimethoxysilane in Example 11 is 1:0.5:0.35. Example 12

[0057] Example 12 is based on Example 9. The only difference between Example 12 and Example 9 is that the mass ratio of copper-plated carbon nanotubes, tetraethyl orthosilicate and γ-glycidoxypropyltrimethoxysilane in Example 12 is 1:0.5:0.2. Example 13

[0058] Example 13 is based on Example 9. The only difference between Example 13 and Example 9 is that the mass ratio of copper-plated carbon nanotubes, tetraethyl orthosilicate and γ-glycidoxypropyltrimethoxysilane in Example 13 is 1:0.5:0.5. Example 14

[0059] Example 14 is based on Example 3. The only difference between Example 14 and Example 3 is that in Example 14, the carbon nanotubes are replaced with modified copper-plated carbon nanotubes prepared in the following steps (without adding γ-glycidoxypropyltrimethoxysilane).

[0060] Preparation of modified copper-plated carbon nanotubes The mass ratio of copper-plated carbon nanotubes to tetraethyl orthosilicate is 1:0.5. The copper-plated carbon nanotubes are multi-walled carbon nanotubes with an aspect ratio of 500, and the copper content accounts for 30% of the total mass of the copper-plated carbon nanotubes.

[0061] Copper-plated carbon nanotubes were stirred at 200 rpm for 5 min in a 1% (w / w) aqueous acetic acid solution, washed with anhydrous ethanol, and then vacuum dried at 60 °C to obtain pretreated copper-plated carbon nanotubes. The pretreated copper-plated carbon nanotubes were added to an ethanol aqueous solution (ethanol to water volume ratio 4:1, solid content 0.5%), the pH was adjusted to 9 with 0.5 mol / L ammonia, and tetraethyl orthosilicate was added. The addition was completed within 2 h, and the reaction was stirred at 200 rpm for 12 h. After centrifugation, the nanotubes were washed with anhydrous ethanol and vacuum dried at 60 °C to obtain modified copper-plated carbon nanotubes. Example 15

[0062] Example 15 is based on Example 3. The only difference between Example 15 and Example 3 is that in Example 15, the carbon nanotubes are replaced with unmodified copper-plated carbon nanotubes.

[0063] Comparative Example 1 Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that the polyimide-modified epoxy resin is replaced with bisphenol A type epoxy resin in Comparative Example 1.

[0064] Comparative Example 2 Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that carbon nanotubes are not added in Comparative Example 2.

[0065] Preparation of thermally conductive adhesive Weigh 45 parts of polyimide-modified epoxy resin, 17 parts of bismaleimide, 6 parts of carboxyl-terminated nitrile butadiene rubber, 30 parts of curing agent, 10 parts of plasticizer, 2 parts of polymeric dispersant, and 100 parts of reactive diluent; weigh 60 parts of magnesium oxide, 15 parts of aluminum oxide, 14 parts of aluminum nitride, and 5 parts of coupling agent; the bismaleimide is N,N'-(4,4'-methylenediphenyl)bismaleimide, the carboxyl-terminated nitrile butadiene rubber is Hypox RA1340, the curing agent is methylhexahydrophthalic anhydride, the plasticizer is dioctyl phthalate, the polymeric dispersant is BYK-163, the reactive diluent is 1,4-butanediol diglycidyl ether, and the coupling agent is γ-glycidyl etheroxypropyltrimethoxysilane.

[0066] S1. Magnesium oxide, aluminum oxide, and aluminum nitride were dried at 110℃ for 2 hours to obtain dried magnesium oxide, aluminum oxide, and aluminum nitride. After pre-hydrolyzing the silane coupling agent in an ethanol aqueous solution (ethanol to water volume ratio of 9:1, solid content 2%) for 30 minutes, it was added to the dried magnesium oxide, aluminum oxide, and aluminum nitride. The mixture was stirred at 500 rpm at 60℃ for 1 hour. After filtration and washing with ethanol, the mixture was dried at 110℃ for 4 hours to obtain the excipient. S2. Mix polyimide-modified epoxy resin, bismaleimide, carboxyl-terminated nitrile rubber, plasticizer, polymeric dispersant, and reactive diluent. Stir at 200 rpm for 1 hour under 60°C and -0.095 MPa vacuum conditions. Add auxiliary materials and stir at 200 rpm for 1.5 hours under 60°C and -0.095 MPa vacuum conditions. Cool down to below 40°C and add the preheated and melted curing agent. Add the curing agent within 1 hour. Reduce the stirring speed to 100 rpm under -0.095 MPa vacuum conditions and stir until air bubbles are removed. Discharge and encapsulate to obtain thermally conductive adhesive. Performance testing experiment

[0067] (1) The standard GB / T 10294-2008 Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials by Protective Hot Plate Method was selected. The sample was cured according to the stepped curing process: 80℃ / 1h, 120℃ / 1h, 180℃ / 2h. A 300mm×300mm (2mm thick) sample was cut from the cured adhesive block. The hot plate temperature was set to 40℃ and the cold plate temperature was set to 20℃. A contact pressure of 2kPa was applied, and the thermal conductivity was measured and calculated. The average value was taken after measurement and the results were recorded in Table 1.

[0068] (2) Select GB / T 31838.2-2019 Dielectric and resistive properties of solid insulating materials - Part 2: Resistance characteristics (DC) test as the standard. The sample was cured according to the stepped curing process: 80℃ / 1h, 120℃ / 1h, 180℃ / 2h to make a disc sample with a diameter of 100mm and a thickness of 2mm. The volume resistivity was tested and calculated. Each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.

[0069] (3) Select GB / T 7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material) as the standard. Apply the sample to the bonding surface and cure it according to the stepped curing process: 80℃ / 1h, 120℃ / 1h, 180℃ / 2h. Apply tensile load to the bonding part at a constant displacement rate of 1.3mm / min on a universal testing machine until the sample fails. Record the maximum tensile force and calculate the tensile shear strength. Prepare five samples for each sample, and take the average value after measurement. Record the results in Table 1. Place the sample in a 200℃ forced-air drying oven and age it for 1000h. After aging, take it out and restore it at room temperature for 24h. Then test and calculate the tensile shear strength and calculate the retention rate after aging. Prepare five samples for each sample, and take the average value after measurement. Record the results in Table 1.

[0070] Table 1. Test results of thermal conductivity, insulation properties, adhesive properties, and temperature resistance. Test results Thermal conductivity (W / (m·K)) Volume resistivity (Ω·cm) Tensile shear strength (MPa) Retention rate (%) Example 1 2.33 <![CDATA[1.81×10 14 ]]> 20.5 91.7 Example 2 2.58 <![CDATA[1.35×10 14 ]]> 19.8 90.9 Example 3 2.45 <![CDATA[1.52×10 14 ]]> 20.2 91.2 Example 4 2.15 <![CDATA[1.65×10 14 ]]> 18.5 88.4 Example 5 2.32 <![CDATA[1.37×10 14 ]]> 18.1 87.2 Example 6 2.18 <![CDATA[1.85×10 14 ]]> 19.5 90.6 Example 7 2.49 <![CDATA[1.24×10 14 ]]> 19.1 89.7 Example 8 2.22 <![CDATA[1.13×10 14 ]]> 17.9 84.7 Example 9 3.17 <![CDATA[8.9×10 13 ]]> 22.3 92.6 Example 10 3.11 <![CDATA[9.5×10 13 ]]> 23.1 92.9 Example 11 3.22 <![CDATA[0.96×10 14 ]]> 24.5 93.5 Example 12 3.28 <![CDATA[5.0×10 13 ]]> 21.6 91.9 Example 13 2.97 <![CDATA[1.1×10 14 ]]> 22.8 92.4 Example 14 3.10 <![CDATA[5.5×10 13 ]]> 20.9 91.5 Example 15 3.45 <![CDATA[6.8×10 9 ]]> 20.5 91.2 Comparative Example 1 1.82 <![CDATA[2.2×10 14 ]]> 14.3 78.6 Comparative Example 2 1.47 <![CDATA[5.8×10 14 ]]> 17.2 89.2 As shown in Table 1, the thermal conductivity of Examples 1-3 is greater than 2.33 W / (m·K), and the volume resistivity is greater than 1.35 × 10⁻⁶. 14 The tensile shear strength is greater than 19.8 MPa and the retention rate is greater than 90.9%, indicating that the thermally conductive adhesive prepared in this application has good thermal conductivity, insulation properties, adhesion properties and temperature resistance.

[0071] As shown in Table 1, the differences between Examples 4-8 and Example 3 are only as follows: In Examples 4 and 5, the composition ratio of the polyimide-modified epoxy resin was disrupted, and too much or too little polyimide prepolymer would affect the balance of properties within the system; In Examples 6 and 7, the synthesis ratio of the polyimide prepolymer was changed, and too much or too little organosilicon diamine would affect the balance of rigidity and flexibility of the polymer chain segments, thereby affecting the performance of the adhesive; In Example 8, no organosilicon diamine was added, and the brittleness of the resin increased, and the temperature resistance deteriorated significantly.

[0072] As shown in Table 1, the only difference between Examples 9-15 and Example 3 is that in Examples 9-11, carbon nanotubes were replaced with modified copper-plated carbon nanotubes. The copper plating layer improved the intrinsic thermal conductivity, while the silica insulating layer and epoxy functionalization treatment on the surface synergistically ensured high insulation and strong interfacial bonding, thereby achieving simultaneous optimization of thermal conductivity, insulation performance and adhesion performance. Examples 12 and 13 violated the specified ratio, resulting in a decrease in performance improvement. Example 14 did not use γ-glycidoxypropyltrimethoxysilane, resulting in a decrease in interfacial bonding. Example 15 used unmodified copper-plated carbon nanotubes, which significantly reduced their insulation performance, demonstrating the necessity of modifying copper-plated carbon nanotubes.

[0073] As shown in Table 1, the only difference between Comparative Example 1 and Example 3 is that Comparative Example 1 uses pure bisphenol A type epoxy resin without polyimide modification, which lacks heat-resistant and high-strength polyimide segments, resulting in poorer synergistic effect between resin matrix components and a significant decrease in performance.

[0074] As shown in Table 1, the only difference between Comparative Example 2 and Example 3 is that no carbon nanotubes were added in Comparative Example 2, resulting in a lack of thermal conductivity pathways in the polymer matrix and a significant decrease in thermal conductivity.

[0075] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A thermally conductive adhesive, characterized in that: It includes main ingredients and auxiliary ingredients, wherein the main ingredients comprise the following components in parts by weight: 40-50 parts of polyimide-modified epoxy resin 14-20 parts of bismaleimide 4-8 parts of carboxyl-terminated nitrile butadiene rubber 25-35 parts of curing agent 5-15 parts plasticizer 1-3 parts of polymeric dispersant 3-5 parts of carbon nanotubes 80-120 parts of reactive diluent; The polyimide-modified epoxy resin is prepared using the following steps: Under a protective atmosphere and stirring conditions, bisphenol A type epoxy resin and triphenylphosphine were mixed, heated, and then added to a polyimide prepolymer solution. The mixture was heated and stirred to react, then cooled and discharged to obtain polyimide modified epoxy resin.

2. The thermally conductive adhesive according to claim 1, characterized in that: The mass ratio of the bisphenol A type epoxy resin, triphenylphosphine and polyimide prepolymer is 1:0.01:(0.2-0.3).

3. The thermally conductive adhesive according to claim 2, characterized in that: The polyimide prepolymer solution was prepared using the following steps: Under a protective atmosphere, the composite diamine monomer is added to N-methylpyrrolidone. 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is added at 0-5°C with stirring. After stirring and reacting, a polyamic acid solution is obtained. A mixture of acetic anhydride and pyridine is added, and the mixture is heated and stirred to obtain a polyimide prepolymer solution.

4. The thermally conductive adhesive according to claim 3, characterized in that: The composite diamine monomer includes 4,4'-diaminodiphenyl ether and diaminopropyl-terminated polydimethylsiloxane.

5. The thermally conductive adhesive according to claim 4, characterized in that: The molar ratio of the 4,4'-diaminodiphenyl ether, the diaminopropyl-terminated polydimethylsiloxane, and the 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride is (0.82-0.88):(0.12-0.18):

1.

6. The thermally conductive adhesive according to claim 1, characterized in that: The carbon nanotubes were replaced with modified copper-plated carbon nanotubes, and the following steps were used for preparation: Copper-plated carbon nanotubes were stirred in an acetic acid solution, washed, and dried to obtain pretreated copper-plated carbon nanotubes. The pretreated copper-plated carbon nanotubes were then added to an ethanol aqueous solution, the pH was adjusted to alkaline, and a mixture of tetraethyl orthosilicate and γ-glycidoxypropyltrimethoxysilane was added. After stirring and reacting, the mixture was centrifuged, washed, and dried to obtain modified copper-plated carbon nanotubes.

7. The thermally conductive adhesive according to claim 6, characterized in that: The mass ratio of the copper-plated carbon nanotubes, tetraethyl orthosilicate, and γ-glycidyl etheroxypropyltrimethoxysilane is 1:0.5:(0.3-0.4).

8. The thermally conductive adhesive according to claim 1, characterized in that: The curing agent includes methylhexahydrophthalic anhydride.

9. The thermally conductive adhesive according to claim 1, characterized in that: The excipients comprise the following components in parts by weight: 50-70 parts magnesium oxide, 10-20 parts aluminum oxide, 10-18 parts aluminum nitride, and 3-7 parts coupling agent.

10. A preparation process for a thermally conductive adhesive as described in any one of claims 1-9, characterized in that: Includes the following steps: S1. Dry magnesium oxide, aluminum oxide and aluminum nitride to obtain dried magnesium oxide, aluminum oxide and aluminum nitride; After pre-hydrolyzing the silane coupling agent solution, it was added to dried magnesium oxide, aluminum oxide and aluminum nitride, heated and stirred to react, filtered, washed and dried to obtain the excipient; S2. Add carbon nanotubes and dispersant to solvent, shear and disperse, and ball mill to obtain carbon nanotube slurry; mix polyimide modified epoxy resin, bismaleimide, carboxyl-terminated nitrile rubber, plasticizer and carbon nanotube slurry, heat and stir under vacuum, add auxiliary materials, heat and stir under vacuum, add preheated and melted curing agent, stir until air bubbles are removed, discharge and encapsulate to obtain thermally conductive adhesive.