High-thermal-conductivity high-heat-resistance epoxy potting adhesive, preparation process and application thereof

Abstract

This application relates to the field of epoxy potting compound technology, and more specifically, to a high thermal conductivity and high heat resistance epoxy potting compound, its preparation process, and its application. The high thermal conductivity and high heat resistance epoxy potting compound comprises the following components in parts by weight: Component A: 90-100 parts epoxy resin, 5-15 parts reactive diluent, 5-10 parts toughening agent, and 350-500 parts thermally conductive filler; Component B: 28-35 parts alicyclic amine curing agent and 2-5 parts accelerator; wherein the thermally conductive filler comprises modified spherical alumina and carboxylated magnesium aluminum spinel. This high thermal conductivity and high heat resistance epoxy potting compound improves upon the poor temperature resistance and thermal conductivity of existing potting compounds, increases its glass transition temperature, ensures the potting compound maintains rigidity under high-temperature operating conditions, and prevents coil loosening or damage due to softening of the compound.

Description

Technical Field

[0001] This application relates to the field of epoxy potting compound technology, and more specifically, to a high thermal conductivity and high heat resistance epoxy potting compound, its preparation process, and its application. Background Technology

[0002] In the field of epoxy potting compound technology, epoxy potting compounds, as an important encapsulation material, play a crucial role in numerous fields such as electronics, electrical engineering, and machinery manufacturing. They effectively prevent external environmental factors from corroding and damaging equipment, thereby extending its service life. With the continuous development of industry, the performance requirements for potting compounds in equipment such as linear motors are increasingly demanding. Linear motors generate a large amount of heat during high-frequency reciprocating motion, requiring potting compounds to possess excellent heat dissipation capabilities and high-temperature stability to ensure the normal operation of the motor and extend its service life. The performance of the potting compound directly affects the thermal stability, output efficiency, and overall reliability of the linear motor. It can not only improve motor performance but also reduce energy consumption and increase production efficiency, showing broad application prospects in industrial production, transportation, and many other fields. Therefore, the development of high-performance epoxy potting compounds is of great significance for promoting the development of linear motor technology.

[0003] Existing potting compounds have poor heat resistance and low glass transition temperatures. The heat generated by the motor can easily cause the potting compound to reach its glass transition temperature, leading to rapid softening of the compound. This results in the coil losing its support, accelerating motor failure. Furthermore, the bonding force between fillers in existing potting compounds is weak, causing increased thermal resistance at high temperatures and affecting the thermal conductivity. After thermal cycling, the potting compound is prone to cracking and debonding, making it difficult to simultaneously improve heat resistance and thermal conductivity, thus failing to meet the stable operation requirements of linear motors under long-term high-temperature conditions. Summary of the Invention

[0004] To address the issues of poor temperature resistance and thermal conductivity in existing potting compounds, this application provides a high thermal conductivity and high heat resistance epoxy potting compound, its preparation process, and its application.

[0005] In the first aspect, this application provides a high thermal conductivity and high heat resistance epoxy potting compound, which adopts the following technical solution: A high thermal conductivity and high heat resistance epoxy potting compound comprises the following components in parts by weight: Component A: 90-100 parts epoxy resin, 5-15 parts reactive diluent, 5-10 parts toughening agent, and 350-500 parts thermally conductive filler; Component B: 28-35 parts alicyclic amine curing agent and 2-5 parts accelerator; wherein the thermally conductive filler comprises modified spherical alumina and carboxylated magnesium aluminum spinel.

[0006] Preferably, the preparation method of modified spherical alumina includes: weighing alumina of the first particle size, alumina of the second particle size, and alumina of the third particle size and mixing them evenly to obtain mixed alumina; dissolving KH-560 in an ethanol aqueous solution and stirring, adding the mixed alumina, stirring and reacting at 50-65℃ for 2-3 hours, centrifuging and drying to obtain modified spherical alumina.

[0007] Preferably, the mass ratio of alumina with the first particle size, alumina with the second particle size, and alumina with the third particle size is (8-12):(4-6):(3-5).

[0008] Preferably, the preparation method of carboxylated magnesium aluminum spinel includes: weighing magnesium aluminum spinel, adding xylene, and ultrasonically dispersing for 45-60 min; adding monobutyl maleate and DCP, and refluxing at 120-135℃ for 6-8 h under nitrogen protection; cooling to room temperature, centrifuging, washing, and drying to obtain carboxylated magnesium aluminum spinel.

[0009] More preferably, the mass ratio of modified spherical alumina to carboxylated magnesium aluminum spinel is 1:(0.15-0.25).

[0010] Epoxy resin, as the matrix, provides the basic adhesive strength and structural support for the system. Toughening agents can improve the overall toughness of the potting compound and enhance its heat resistance and stability. Its interaction with thermally conductive fillers effectively dissipates the thermal stress and internal stress generated during thermal cycling, inhibits cracking, delamination, and interface debonding, and ensures the structural integrity of the cured material, providing a mechanical basis for the long-term stability of thermal conductivity. Alicyclic amine curing agents form a high-density three-dimensional cross-linked network with epoxy resin, exhibiting excellent structural rigidity and heat resistance. This provides stable physical support for the thermally conductive fillers, preventing the matrix from softening at high temperatures and causing disordered filler arrangement. Accelerators effectively regulate the curing reaction rate, ensuring full curing of the system, reducing unreacted small molecules and internal defects, and further improving the heat resistance and structural stability of the cured product.

[0011] Spherical alumina with multi-size gradation forms a three-dimensional continuous thermally conductive network in the epoxy matrix, with interparticle point contact as the connection method, thanks to its spherical morphology and size gradient. The added magnesium aluminum spinel, due to its cubic crystal structure, has isotropic intrinsic thermal conductivity, higher Mohs hardness than alumina, and lower coefficient of thermal expansion. At the same time, its unique polyhedral crystal shape forms a multi-point stable contact with the curved surface of the spherical alumina. Utilizing the bulk thermal conductivity of magnesium aluminum spinel itself, on the basis of the alumina particle point contact network, the magnesium aluminum spinel grains themselves become independent thermally conductive units. In addition to the direct point connection between alumina particles, heat can also be rapidly transported laterally between multiple alumina particles along the structural path of the spinel crystal. This significantly increases the effective thermally conductive cross-sectional area and shortens the heat flow detour in the low thermal conductivity matrix, thereby expanding the original point connection network into a network structure in which point connection and grain bulk thermal conductivity coexist. Based on this structural combination, the spherical alumina, after surface modification to introduce epoxy groups, can better integrate with the epoxy resin matrix and carboxylated magnesium aluminum spinel, enhancing interfacial compatibility, further optimizing the continuity of the thermal conductivity pathway, reducing interfacial thermal resistance, and making heat transfer more efficient. The interaction between the carboxylated magnesium aluminum spinel and the modified spherical alumina at the interface not only eliminates the physical interfacial thermal resistance between fillers, allowing unimpeded heat transfer within the filler system, but also effectively constrains the relative displacement of filler particles at high temperatures, maintaining the packing density and continuity of the thermal conductivity pathway. This prevents the filler from becoming loose and separating under high-temperature conditions, thus reducing thermal conductivity and further enhancing the high-temperature thermal stability and heat resistance of the potting compound. Therefore, if the content of carboxylated magnesium aluminum spinel is too low, the increase in effective thermal conductivity cross-sectional area is limited, resulting in a small improvement in thermal conductivity; if the content of carboxylated magnesium aluminum spinel is too high, it disrupts the original multi-size alumina gradation packing structure, failing to fully compensate for the loss of thermal conductivity pathway continuity due to the decrease in packing density, leading to a decrease in overall thermal conductivity. This can also increase the risk of cracking due to thermal stress concentration during hot and cold cycles, and reduce heat resistance stability.

[0012] Preferably, the toughening agent includes one or more of the following: core-shell rubber, carboxyl-terminated liquid nitrile rubber, polyimide powder, and polyether polyol.

[0013] Preferably, the toughening agent comprises a core-shell rubber and polyimide powder in a mass ratio of (1.8-2.5):1.

[0014] More preferably, the polyimide powder is a modified polyimide powder, the preparation method of which includes: weighing polyimide powder and dispersing it in N-methylpyrrolidone, adding 3-aminophthalimide and sodium carbonate, reacting at 75-90℃ for 4-8h to obtain modified polyimide powder.

[0015] The core layer of the core-shell rubber is composed of flexible polymer chains. When subjected to thermal stress or impact, the molecular chains efficiently dissipate energy through chain segment rearrangement and intermolecular sliding. Without reducing the epoxy crosslinking density and glass transition temperature, the low-temperature crack resistance and long-term reliability of the potting compound are simultaneously improved, thus endowing the potting compound with excellent thermal shock resistance and low-temperature crack resistance. After modification, the modified polyimide powder introduces imide ring structures and active amino groups on the surface of the intrinsic aromatic heterocyclic rigid skeleton of polyimide. The active amino groups react with the epoxy groups to embed the polyimide in the crosslinking network, and the introduced imide rings further enhance the conjugated stacking and rigidity between molecular chains, forming highly thermally stable rigid microregions. When the two coexist in the aforementioned proportion, the flexible molecular chains of the core-shell rubber and the rigid aromatic heterocyclic structure of the modified polyimide powder constitute a flexible dissipative and rigidly stable toughening network: the flexible chain segments rapidly disperse local thermal stress and impact energy through chain segment rearrangement, while the rigid micro-regions prevent crack propagation paths and maintain dimensional stability at high temperatures by virtue of their high glass transition temperature and strong intermolecular forces. At the same time, the active functional groups on the surfaces of the two toughening agents can interact and combine with the thermally conductive filler and epoxy matrix to uniformly transfer thermal stress to the filler network, avoiding stress concentration that could lead to cracking and delamination, thereby comprehensively improving the toughness, heat resistance stability and long-term reliability of the potting compound. When the proportion of core-shell rubber is too high, the proportion of flexible molecular chains in the system is too large, resulting in insufficient overall rigidity of the cross-linked network, which destroys the density and continuity of the thermal conductivity pathway and deteriorates the heat resistance. When the proportion of polyimide powder is too high, the system becomes more brittle, and the internal stress cannot be effectively released, which easily leads to microcracks that expand into macroscopic cracks. At the same time, too many rigid micro-regions will significantly increase the viscosity of the system, hindering the uniform dispersion of the thermally conductive filler, which in turn reduces the thermal conductivity and resistance to cyclic thermal shock.

[0016] Preferably, the active diluent is selected from one or more of butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and C12-C14 alkyl glycidyl ether.

[0017] Secondly, this application provides a preparation process for a high thermal conductivity and high heat resistance epoxy potting compound, which adopts the following technical solution: including the following steps: (1) Component A: weigh epoxy resin, reactive diluent, toughening agent and add thermally conductive filler in three batches after mixing, and stir under vacuum for 0.5-1h to obtain component A; (2) Component B: weigh alicyclic amine curing agent and accelerator and mix to obtain component B; (3) mix component A and component B evenly, degas under vacuum, pot and cure.

[0018] Preferably, the curing process is as follows: heating at 80-90℃ for 1-2 hours, then heating at 100-120℃ for 2-3 hours, and then heating at 150-170℃ for 4-6 hours.

[0019] Thirdly, this application provides the use of a high thermal conductivity and high heat resistance epoxy potting compound in the potting and casting of linear motors and power electronic devices.

[0020] In summary, this application has the following beneficial effects: 1. The combination of thermally conductive filler and toughening agent in this application, along with epoxy resin as the matrix to provide basic bonding strength and structural support for the system and the curing process, increases the glass transition temperature of the cured material, ensuring that the potting compound maintains rigidity under high-temperature working conditions and avoiding coil loosening or damage due to softening of the compound. Together, these factors improve the problems of insufficient thermal conductivity, poor structural stability at high temperatures, and thermal conductivity degradation of linear motor potting compounds.

[0021] 2. The combination of modified spherical alumina and carboxylated magnesium aluminum spinel can fully leverage the high density and continuous thermal conductivity of modified spherical alumina, while the high thermal stability and low expansion characteristics of carboxylated magnesium aluminum spinel can improve the high-temperature reliability of the overall system, optimize the continuity of the thermal conduction path, reduce interfacial thermal resistance, and make heat transfer more efficient. Detailed Implementation

[0022] The present application will be further described in detail below with reference to the embodiments.

[0023] Some of the raw materials used in the preparation examples and embodiments: magnesium aluminum spinel (1µm): purchased from Maclean; polyimide resin powder: PIR-005 purchased from Quzhou Jiefeng Chemical Co., Ltd.; alumina of the first, second, and third particle sizes were all purchased from Qunhe Precision Materials Co., Ltd.; bisphenol A type epoxy resin Nanya NPEL-128; reactive diluent: butanediol diglycidyl ether; core-shell rubber Zhongyuan MX-154; alicyclic amine curing agent PACM: Wanhua Chemical; accelerator type: K54; Unless otherwise specified, all raw materials used in the embodiments and comparative examples are conventional products that can be purchased commercially.

[0024] Preparation Example 1 Preparation of modified spherical alumina: Weigh 10 parts of alumina with the first particle size, 6 parts of alumina with the second particle size, and 3 parts of alumina with the third particle size and mix them evenly to obtain mixed alumina; Dissolve 1.2 parts of KH-560 in 38 parts of ethanol solution containing 8 parts of water and stir at room temperature for 30 min; Add the mixed alumina, stir and react at 60℃ for 2 h, centrifuge and filter, and vacuum dry at 100℃ for 3 h to obtain modified spherical alumina.

[0025] Preparation Example 2 Preparation of modified spherical alumina: Weigh 7 parts of alumina with the first particle size, 9 parts of alumina with the second particle size, and 3 parts of alumina with the third particle size and mix them evenly to obtain mixed alumina; Dissolve 1.2 parts of KH-560 in 38 parts of ethanol solution containing 8 parts of water and stir at room temperature for 30 min; Add the mixed alumina, stir and react at 60℃ for 2 h, centrifuge and filter, and vacuum dry at 100℃ for 3 h to obtain modified spherical alumina.

[0026] Preparation Example 3 Preparation of modified spherical alumina: Weigh 19 parts of alumina with the first particle size and mix them evenly to obtain mixed alumina; Dissolve 1.2 parts of KH-560 in 38 parts of ethanol solution containing 8 parts of water and stir at room temperature for 30 min; Add mixed alumina, stir and react at 60℃ for 2 h, centrifuge and filter, and vacuum dry at 100℃ for 3 h to obtain modified spherical alumina.

[0027] Preparation Example 4 Preparation of modified spherical alumina: 10 parts of monocrystalline magnesium aluminum spinel were weighed and 50 parts of xylene were added. The mixture was ultrasonically dispersed for 60 min. 0.8 parts of monobutyl maleate and 0.09 parts of DCP were added. The mixture was refluxed at 135 °C for 8 h under nitrogen protection. The mixture was cooled to room temperature, centrifuged, washed three times with ethanol, and vacuum dried at 80 °C for 12 h to obtain carboxylated magnesium aluminum spinel.

[0028] Preparation Example 5 Modified polyimide powder: Weigh 10 parts of modified polyimide powder and disperse it in 35 parts of N-methylpyrrolidone, add 0.85 parts of 3-aminophthalimide and 0.25 parts of sodium carbonate, react at 80℃ for 5h; cool, centrifuge, wash with water until neutral, and vacuum dry at 80℃ for 10h to obtain modified polyimide powder. Example 1

[0029] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them, and obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina prepared in Preparation Example 1 and carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber with a mass ratio of 2:1 and polyimide powder prepared in Preparation Example 5. Example 2

[0030] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina prepared in Preparation Example 2 and carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber with a mass ratio of 2:1 and polyimide powder prepared in Preparation Example 5. Example 3

[0031] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina prepared in Preparation Example 3 and carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber with a mass ratio of 2:1 and polyimide powder prepared in Preparation Example 5. Example 4

[0032] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them, and obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina prepared in Preparation Example 1 and carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.1; the toughening agent is core-shell rubber with a mass ratio of 2:1 and polyimide powder prepared in Preparation Example 5. Example 5

[0033] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina prepared in Preparation Example 1 and carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.3; the toughening agent is core-shell rubber with a mass ratio of 2:1 and polyimide powder prepared in Preparation Example 5. Example 6

[0034] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina prepared in Preparation Example 1 and carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber and polyimide powder with a mass ratio of 2:1. Example 7

[0035] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina prepared in Preparation Example 1 and carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber with a mass ratio of 1.5:1 and polyimide powder prepared in Preparation Example 5. Example 8

[0036] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them, and obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina prepared in Preparation Example 1 and carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber with a mass ratio of 3:1 and polyimide powder prepared in Preparation Example 5. Example 9

[0037] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is the modified spherical alumina prepared in Preparation Example 1 and the carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber. Example 10

[0038] A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts epoxy resin, 8 parts reactive diluent, and 6 parts toughening agent, mix them evenly, and then add 390 parts thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts alicyclic amine curing agent and 3 parts accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is the modified spherical alumina prepared in Preparation Example 1 and the carboxylated magnesium aluminum spinel prepared in Preparation Example 4 with a mass ratio of 1:0.2; the toughening agent is the polyimide powder prepared in Preparation Example 5.

[0039] Comparative Example 1 A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts epoxy resin, 8 parts reactive diluent, and 6 parts toughening agent, mix them evenly, and then add 390 parts thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts alicyclic amine curing agent and 3 parts accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is alumina with a first particle size and carboxylated magnesium aluminum spinel prepared in preparation example 4 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber and polyimide powder prepared in preparation example 5 with a mass ratio of 2:1.

[0040] Comparative Example 2 A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is modified spherical alumina and magnesium aluminum spinel prepared in Preparation Example 1 with a mass ratio of 1:0.2; the toughening agent is core-shell rubber and polyimide powder prepared in Preparation Example 5 with a mass ratio of 2:1.

[0041] Comparative Example 3 A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is the modified spherical alumina prepared in Preparation Example 1; the toughening agent is the core-shell rubber with a mass ratio of 2:1 and the polyimide powder prepared in Preparation Example 5.

[0042] Comparative Example 4 A process for preparing a high thermal conductivity and high heat resistance epoxy potting compound includes the following steps: (1) Component A: Take 100 parts of epoxy resin, 8 parts of reactive diluent, and 6 parts of toughening agent, mix them evenly, and then add 390 parts of thermally conductive filler in three batches. Stir under vacuum for 1 hour to obtain component A; (2) Component B: Weigh 30 parts of alicyclic amine curing agent and 3 parts of accelerator, mix them evenly to obtain component B; (3) Mix component A and component B evenly, degas under vacuum, pot, heat at 80°C for 1 hour, then heat at 120°C for 2 hours, and then heat at 150°C for 6 hours to obtain a high thermal conductivity and high heat resistance epoxy potting compound. The thermally conductive filler is the carboxylated magnesium aluminum spinel prepared in Preparation Example 4; the toughening agent is the core-shell rubber with a mass ratio of 2:1 and the polyimide powder prepared in Preparation Example 5.

[0043] The performance testing of the high thermal conductivity and high heat resistance epoxy potting compound prepared in the examples and comparative examples was conducted using the following methods: a. Glass transition temperature test: Tested according to GB / T 19466.2-2004 standard; b. Thermal conductivity test: Tested according to GB / T 10295-2008 standard; c. Cyclic Stability: The potting compound sample was placed in a thermal cycling test chamber and subjected to thermal cycling tests at -25℃ and 100℃. Each cycle consisted of 30 minutes of holding at both the high and low temperatures. After each cycle, the sample was observed to ensure no cracks, delamination, or interface debonding. The thermal conductivity was then tested again, and the thermal conductivity retention rate was not less than 95%. The number of stable thermal cycles was then determined. The comparison results are shown in Table 1 below. Table 1 Performance Test Results

[0044] As shown in Table 1, the high thermal conductivity and high heat resistance epoxy potting compound obtained in the above embodiments meets the requirements of the potting compound in high-temperature working environment, improves thermal conductivity and high temperature resistance, and avoids coil loosening or damage due to softening of the colloid.

[0045] Compared with Examples 1-5 and Comparative Examples 1-4, it can be seen that the multi-size graded spherical alumina, with its spherical morphology and size gradient, forms a three-dimensional continuous thermally conductive network in the epoxy matrix, with point contact between particles as the connection mode. The carboxylated magnesium aluminum spinel and the modified spherical alumina interact at the interface, which not only eliminates the physical interface thermal resistance between fillers, allowing heat to be transferred unimpeded within the filler system, but also effectively constrains the relative displacement of filler particles under high temperature conditions, maintains the packing density and thermal conductivity continuity of the filler system, and avoids the decrease in thermal conductivity caused by the loosening and separation of fillers under high temperature conditions, further enhancing the high-temperature thermal conductivity stability and heat resistance of the potting compound.

[0046] Comparative examples 6-10 show that the flexible molecular chains of the core-shell rubber and the rigid aromatic heterocyclic structure of the modified polyimide powder constitute a flexible dissipative and rigidly stable toughening network: the flexible chain segments rapidly disperse local thermal stress and impact energy through chain segment rearrangement, while the rigid micro-regions prevent crack propagation paths and maintain dimensional stability at high temperatures by virtue of their high glass transition temperature and strong intermolecular forces. At the same time, the active functional groups on the surfaces of the two toughening agents can interact and combine with the thermally conductive fillers and epoxy groups to uniformly transfer thermal stress to the filler network, avoiding stress concentration that could lead to cracking and delamination, thereby comprehensively improving the toughness, heat resistance stability and long-term reliability of the potting compound.

[0047] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high thermal conductivity and high heat resistance epoxy potting compound, characterized in that: The product comprises the following components in parts by weight: Component A: 90-100 parts epoxy resin, 5-15 parts reactive diluent, 5-10 parts toughening agent, and 350-500 parts thermally conductive filler; Component B: 28-35 parts alicyclic amine curing agent and 2-5 parts accelerator; wherein the thermally conductive filler comprises modified spherical alumina and carboxylated magnesium aluminum spinel.

2. The high-thermal-conductivity and high-heat-resistance epoxy potting adhesive according to claim 1, characterized in that: The method for preparing the modified spherical alumina includes: weighing alumina of the first particle size, alumina of the second particle size, and alumina of the third particle size and mixing them evenly to obtain mixed alumina; dissolving KH-560 in an ethanol aqueous solution and stirring, adding the mixed alumina, stirring and reacting at 50-65℃ for 2-3 hours, centrifuging and drying to obtain modified spherical alumina.

3. The high-thermal-conductivity and high-heat-resistance epoxy potting adhesive according to claim 2, characterized in that: The mass ratio of the first-size alumina, the second-size alumina, and the third-size alumina is (8-12):(4-6):(3-5).

4. The high-thermal-conductivity and high-heat-resistance epoxy potting adhesive according to claim 1, characterized in that: The mass ratio of the modified spherical alumina to carboxylated magnesium aluminum spinel is 1:(0.15-0.25).

5. The high-thermal-conductivity and high-heat-resistance epoxy potting adhesive according to claim 1, characterized in that: The toughening agent includes one or more of the following: core-shell rubber, carboxyl-terminated liquid nitrile rubber, polyimide powder, and polyether polyol.

6. The high thermal conductivity and high heat resistance epoxy potting compound according to claim 1, characterized in that: The toughening agent comprises core-shell rubber and polyimide powder in a mass ratio of (1.8-2.5):

1.

7. The high thermal conductivity and high heat resistance epoxy potting compound according to claim 1, characterized in that: The active diluent is selected from one or more of butylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, and C12-C14 alkyl glycidyl ether.

8. The preparation process of a high thermal conductivity and high heat resistance epoxy potting compound according to claims 1-7, characterized in that: The process includes the following steps: (1) Component A: Weigh epoxy resin, reactive diluent, and toughening agent, mix them, add thermally conductive filler in three batches, and stir under vacuum for 0.5-1h to obtain component A; (2) Component B: Weigh alicyclic amine curing agent and accelerator, mix them, and obtain component B; (3) Mix component A and component B evenly, degas under vacuum, and then pot and cure.

9. The preparation process of a high thermal conductivity and high heat resistance epoxy potting compound according to claim 8, characterized in that: The specific curing process is as follows: heat at 80-90℃ for 1-2 hours, then heat at 100-120℃ for 2-3 hours, and then heat at 150-170℃ for 4-6 hours.

10. The use of the high thermal conductivity and high heat resistance epoxy potting compound according to any one of claims 1-7 in the potting and casting of linear motors and power electronic devices.

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