Self-repairing epoxy insulating material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of epoxy resin, and particularly relates to a self-repairing epoxy insulating material as well as a preparation method and application thereof. The invention relates to a self-repairing epoxy insulating material, which is prepared from the following raw materials: an epoxy resin matrix, a heat-conducting filler dispersed in the epoxy resin matrix, a cross-linking agent and a curing agent, wherein the heat-conducting filler is subjected to surface modification through an amphiphilic polymer, and a gradient compatibility interface layer is formed on the surface of a particle and is used for improving the interface compatibility between the heat-conducting filler and the epoxy resin matrix and reducing the interface thermal resistance; the cross-linking agent comprises reversible covalent bonds of disulfide bonds and / or imide bonds, a dynamic cross-linked network is formed in the epoxy resin matrix, and the dynamic cross-linked network can perform reversible fracture and recombination of chemical bonds through external stimulation, so that the epoxy insulating material has self-repairing capability.

Description

Technical Field

[0001] The present invention belongs to the technical field of epoxy resins, and in particular relates to a self-repairing epoxy insulating material and a preparation method and application thereof. Background Art

[0002] With the rapid development of electronic information technology and the continuous upgrading of power systems, the integration and power density of electronic components and power equipment are constantly increasing. Miniaturization, lightweighting, and high reliability have become key development trends. However, high power density operation comes with enormous heat dissipation challenges. Insulation materials, as core components of key components such as electronic packaging, motors, transformers, power modules, and new energy vehicle battery packs, must not only provide reliable electrical insulation but also effectively dissipate the heat generated during device operation to maintain the device's normal operating temperature and prevent performance degradation or even failure due to overheating.

[0003] Traditional epoxy resin-based insulating materials are widely used for their excellent adhesion, good electrical insulation properties, chemical corrosion resistance and low cost. However, the thermal conductivity of pure epoxy resin is usually very low (about 0.2W / m·K), which is far from meeting the heat dissipation requirements of modern high-power electronic equipment and power systems. This seriously limits its application in high-efficiency heat dissipation scenarios. In order to improve the thermal conductivity of epoxy resin, a method of adding high thermal conductivity fillers is usually used to prepare thermally conductive composite materials. However, this method faces many challenges:

[0004] The conflict between thermal conductivity and filler content: Achieving high thermal conductivity often requires adding a high volume fraction of thermally conductive fillers. However, this can lead to a sharp increase in composite material viscosity, poor fluidity, and difficulty processing and filling complex structures. Furthermore, high filler content can make the material brittle and reduce mechanical properties.

[0005] Interfacial thermal resistance: Significant interfacial thermal resistance due to phonon scattering exists between the filler and the epoxy resin matrix, hindering effective heat transfer across the interface and limiting the overall thermal conductivity of the composite. Filler particles are also prone to agglomeration, further reducing thermal conductivity.

[0006] Material Brittleness and Reliability: After curing, epoxy resin forms a highly cross-linked three-dimensional network structure, which is hard and brittle, with poor toughness and insufficient impact resistance. Over long-term service, microcracks can easily form within the material due to thermal stress, mechanical vibration, or environmental factors. These microcracks not only weaken the material's mechanical strength but, more seriously, damage its insulation properties, forming partial discharge channels that can ultimately lead to insulation breakdown and affect the safe and reliable operation of the equipment.

[0007] Lack of self-healing ability: Traditional thermosetting epoxy resins, once cured, form a permanent cross-linked network that cannot self-repair after damage (such as microcracks) occurs. This leads to cumulative damage to the material and shortens its service life. This shortcoming is particularly prominent in applications that require long-term stable operation or are difficult to maintain.

[0008] Therefore, developing a new type of epoxy insulation composite material that has low viscosity, high thermal conductivity, excellent mechanical properties and self-healing ability has become a research hotspot and urgent need in the field of high-performance insulation materials. Summary of the Invention

[0009] The purpose of the present invention is to solve the above-mentioned shortcomings by introducing a gradient compatibility interface layer to optimize filler dispersion and interface heat transfer, constructing a graded thermal conductive filler network, and combining a dynamic cross-linking network to give the material self-healing function, thereby preparing an epoxy insulation material with excellent comprehensive performance.

[0010] In the first aspect, a self-repairing epoxy insulation material adopts the following technical solution:

[0011] A self-repairing epoxy insulation material, the raw materials of the epoxy insulation material comprising:

[0012] An epoxy resin matrix and a thermally conductive filler dispersed in the epoxy resin matrix, as well as a cross-linking agent and a curing agent;

[0013] The thermally conductive filler is surface-modified with an amphiphilic polymer to form a gradient compatibility interface layer on the particle surface, which is used to improve the interface compatibility between the thermally conductive filler and the epoxy resin matrix and reduce the interface thermal resistance;

[0014] The cross-linking agent contains reversible covalent bonds of disulfide bonds and / or imide bonds, forming a dynamic cross-linking network in the epoxy resin matrix. The dynamic cross-linking network can reversibly break and restructure chemical bonds through external stimulation to enable the epoxy insulation material to have self-repairing ability.

[0015] Furthermore, the viscosity of the epoxy resin matrix at room temperature is 100 mPa·s to 1000 mPa·s.

[0016] Furthermore, the added amount of the cross-linking agent is 1 wt% to 10 wt% of the total mass of the epoxy resin matrix and the curing agent.

[0017] Furthermore, the mass ratio of the thermally conductive filler to the epoxy resin matrix is (50-150): (100-200); the thermally conductive filler includes a micron-sized inorganic thermally conductive filler and a nano-sized carbon material filler, and the mass ratio of the micron-sized inorganic thermally conductive filler to the nano-sized carbon material filler is (5-15):1.

[0018] Furthermore, the micron-sized inorganic thermal conductive filler includes at least one of boron nitride, aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, silicon carbide and silicate; the nano-sized carbon material filler includes at least one of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes and graphene.

[0019] Furthermore, the amphiphilic polymer accounts for 0.5 wt% to 5.0 wt% of the mass of the thermally conductive filler; the amphiphilic polymer includes at least one of functionalized polyether, polyamide, polyurethane, modified silane, polyetheramine and block copolymer.

[0020] Furthermore, the amphiphilic polymer includes a modified silane compound containing an epoxy or carboxyl terminal group.

[0021] Furthermore, the added amount of the curing agent is 10wt% to 30wt% of the mass of the epoxy resin matrix; the curing agent includes at least one of aliphatic amines, cycloaliphatic amines, modified polyamides, imidazoles, and acid anhydrides.

[0022] Furthermore, the raw materials of the epoxy insulation material also include a toughening agent, and the added amount of the toughening agent is 2wt% to 15wt% of the mass of the epoxy resin matrix; the toughening agent includes at least one of polyether amine, hydroxyl silicone oil, block copolymer, epoxy modified rubber, and polyurethane additives.

[0023] In the second aspect, a method for preparing a self-repairing epoxy insulation material adopts the following technical solution:

[0024] A method for preparing a self-repairing epoxy insulation material comprises the following steps:

[0025] Modifying the surface of the thermally conductive filler with an amphiphilic polymer by chemical bonding or physical adsorption to form a gradient compatibility interface layer on the surface of the thermally conductive filler;

[0026] The surface-modified thermal conductive filler and the epoxy resin matrix are mixed under an inert atmosphere at a mixing temperature of 25° C. to 40° C. to obtain a mixture;

[0027] The mixture is degassed under vacuum conditions, a curing agent and a cross-linking agent are added, and after uniform mixing, curing is performed in stages, with preliminary curing performed at 60° C. to 80° C. for 1 hour to 2 hours, and then curing is performed at 120° C. to 150° C. for 2 hours to 4 hours, to form a dynamic cross-linking network in the epoxy resin matrix, thereby obtaining the epoxy insulating material.

[0028] In the third aspect, an application of a self-repairing epoxy insulation material adopts the following technical solution:

[0029] An application of a self-repairing epoxy insulation material, wherein the epoxy insulation material is applied to:

[0030] Encapsulation or potting of high power density electronic components;

[0031] Insulation of power equipment such as dry-type transformers, motors, reactors, etc.

[0032] Structural bonding, thermal conductivity or packaging of new energy vehicle power battery packs;

[0033] Or, occasions where the material is required to have high thermal conductivity, good processing fluidity, excellent insulation properties and self-healing ability.

[0034] Beneficial effects of the present invention:

[0035] The present invention provides a self-repairing epoxy insulation material, which significantly improves the thermal conductivity of the material by introducing a thermally conductive filler, solving the problem of poor thermal conductivity of pure epoxy resin. In particular, the filler is surface-modified with an amphiphilic polymer to form a gradient compatibility interface layer, which effectively improves the interfacial compatibility between the filler and the epoxy matrix, promotes the uniform dispersion of the filler, and significantly reduces the interfacial thermal resistance. This allows heat to be transferred more efficiently through the filler network, thereby achieving higher overall thermal conductivity at the same or lower filler content, overcoming the limitations of interface problems on thermal conductivity efficiency in traditional composite materials. Secondly, a cross-linking agent containing reversible covalent bonds (disulfide bonds and / or imide bonds) is introduced to form a dynamic cross-linking network in the epoxy matrix. When the material is damaged and microcracks are generated, these dynamic bonds can undergo reversible breaking and reorganization under external stimulation, causing the molecular chains to rearrange and fill the cracks, thereby repairing the damage. This self-repairing ability can significantly extend the service life of the material, improve its reliability and safety during long-term service, and reduce performance degradation or ultimate failure caused by accumulation of microdamage. The present invention combines the excellent electrical insulation properties of epoxy resin, the high thermal conductivity achieved through fillers and a gradient compatibility interface layer, and the self-healing ability achieved through a dynamic cross-linked network into a single material. This makes the material particularly suitable for applications that require both reliable insulation and efficient heat dissipation, while also desiring damage tolerance and a long life. Compared to traditional epoxy insulating materials or simple thermally conductive composite materials, the epoxy insulating material provided by the present invention significantly improves thermal conductivity, reliability, and lifespan through structural and functional integration, broadening the application areas of epoxy resin, especially in the demanding high-performance electronics, power, and new energy fields. DETAILED DESCRIPTION

[0036] The following examples further describe in detail a self-healing epoxy insulation material, a preparation method and an application thereof described in the present invention. For the sake of simplicity of description, this document cannot enumerate all the alternative technical features and implementation schemes contained in the present invention. Therefore, those skilled in the art should know that any technical features and implementation schemes in this embodiment do not limit the scope of protection of the present invention, and the scope of protection includes any alternative technical features and implementation schemes adopted by all those skilled in the art without creative work. Specifically, the implementation schemes obtained by replacing any technical feature in the present invention or combining any two or more technical features provided by the present invention should be within the scope of protection of the present invention. For those examples in which specific techniques and conditions are not specified, the techniques and conditions described in the literature in this field or in accordance with the product instructions shall be followed. The reagents or instruments used, for which the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0037] The basic information of the epoxy resin in the following examples is as follows:

[0038] Bisphenol A type liquid epoxy resin, brand CYD-115, epoxy equivalent 180-194, hydrolyzability ≤0.10%, viscosity 800-1000mPa·s (25°C), volatile matter 10%.

[0039] Example

[0040] Example 1

[0041] Example 1 provides a self-healing epoxy insulation material, the raw materials of which include: 200g of epoxy resin matrix (CYD-115), 50g of thermal conductive filler, 0.25g of amphiphilic polymer (γ-glycidyloxypropyltrimethoxysilane, KH-560), 11g of cross-linking agent (dithiodipropionic acid dihydrazide), and 20g of curing agent (isophorone diamine, IPDA).

[0042] Among them, the thermal conductive filler is composed of a mixture of micron-sized hexagonal boron nitride (h-BN, average particle size 10μm, 45.5g) and multi-walled carbon nanotubes (MWCNT, diameter 1020nm, length 515μm, 4.5g) in a mass ratio of 10:1.

[0043] Example 1 also provides a method for preparing a self-repairing epoxy insulation material, comprising the following steps:

[0044] 45.5 g of micron-sized hexagonal boron nitride and 4.5 g of multi-walled carbon nanotubes were mixed and added with 500 g of anhydrous ethanol. The mixture was ultrasonically dispersed for 30 minutes. 0.25 g of γ-glycidyloxypropyltrimethoxysilane ethanol solution was added dropwise under stirring. The temperature was raised to 70°C and stirred for reaction for 4 hours. The mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 80°C for 12 hours to obtain a surface-modified thermal conductive filler.

[0045] In a planetary mixer, add 200g of epoxy resin matrix and perform vacuum pre-degassed treatment at 60°C to remove some volatiles. Under nitrogen, the mixing temperature is controlled at 30°C. Slowly add 50g of surface-modified thermal conductive filler in batches, stir at high speed for 30min, and perform ultrasonic dispersion for 20min to obtain a uniform mixture.

[0046] The mixture was stirred and degassed under a vacuum of <100 Pa. 20 g of curing agent (isophorone diamine) and 11 g of crosslinking agent (dithiodipropionic acid dihydrazide) were added and mixed at low speed for 15 minutes. The mixture was briefly vacuum-degassed again and poured into a preheated mold for staged curing. Initial curing took place at 60°C for 1.5 hours, followed by a final curing at 135°C for 3 hours. A slow temperature ramp was used to reduce bubbles caused by volatile matter release. The mold was then cooled and demolded to obtain the self-healing epoxy insulation material.

[0047] Example 2

[0048] Example 2 provides a self-healing epoxy insulation material, the raw materials of which include: 150g of epoxy resin matrix (CYD-115), 112.5g of thermal conductive filler, 2.8g of amphiphilic polymer (KH-560), 9g of cross-linking agent (dithiodipropionic acid dihydrazide), 30g of curing agent (IPDA), and 12g of toughening agent (terminated amino polyether Jeffamine D-230).

[0049] The thermal conductive filler is composed of a mixture of micron-sized hexagonal boron nitride (h-BN, 10 μm, 102.3 g) and multi-walled carbon nanotubes (MWCNT, 10.2 g) in a mass ratio of 10:1.

[0050] Example 2 also provides a method for preparing a self-repairing epoxy insulation material, comprising the following steps:

[0051] 102.3 g of micron-sized hexagonal boron nitride and 10.2 g of multi-walled carbon nanotubes were mixed and added with 800 g of anhydrous ethanol. The mixture was ultrasonically dispersed for 30 minutes. 2.8 g of KH-560 ethanol solution was added dropwise under stirring. The temperature was raised to 70°C and stirred for 4 hours. The mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 80°C for 12 hours to obtain a surface-modified thermal conductive filler.

[0052] In a planetary mixer, add 150g of epoxy resin matrix and 12g of toughening agent (Jeffamine D-230), perform vacuum pre-degassed treatment at 60°C, control the mixing temperature at 30°C under nitrogen, slowly add 112.5g of surface-modified thermal conductive filler in batches, stir at high speed for 30min, and perform ultrasonic dispersion for 20min or three-roll grinding to obtain a uniform mixture.

[0053] The mixture was stirred and degassed under a vacuum of <100 Pa. 30 g of curing agent (IPDA) and 9 g of crosslinking agent (dithiodipropionic acid dihydrazide) were added and mixed at low speed for 15 minutes. The mixture was briefly vacuum-degassed again and poured into a preheated mold for staged curing. Initial curing took place at 70°C for 1.5 hours, followed by a final curing at 135°C for 3 hours. A slow temperature ramp was used, and the mold was cooled and demolded to obtain the self-healing epoxy insulation material.

[0054] Example 3

[0055] Example 3 provides a self-healing epoxy insulation material, the raw materials of which include: 150g of epoxy resin matrix (CYD-115), 112.5g of thermal conductive filler, 2.8g of amphiphilic polymer (KH-560), 9g of cross-linking agent (dithiodipropionic acid dihydrazide), and 30g of curing agent (IPDA).

[0056] Among them, the thermal conductive filler is composed of micron-sized spherical alumina ( 5 μm, 93.75 g) and single-walled carbon nanotubes (SWCNTs, 18.75 g) were mixed.

[0057] Example 3 also provides a method for preparing a self-repairing epoxy insulation material, comprising the following steps:

[0058] 93.75 g of micron-sized spherical alumina and 18.75 g of single-walled carbon nanotubes were mixed, 800 g of anhydrous ethanol was added, and ultrasonic dispersion was performed for 30 minutes. 2.8 g of KH-560 ethanol solution was added dropwise under stirring. The temperature was raised to 70°C, and the mixture was stirred for reaction for 4 hours. The mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 80°C for 12 hours to obtain a surface-modified thermal conductive filler.

[0059] In a planetary mixer, add 150g of epoxy resin matrix and perform vacuum pre-degassed treatment at 60°C. Under nitrogen, the mixing temperature is controlled at 30°C. Then, 112.5g of surface-modified thermal conductive filler is slowly added in batches. The mixture is stirred at high speed for 30min and ultrasonically dispersed for 20min to obtain a uniform mixture.

[0060] The mixture was stirred and degassed under a vacuum of <100 Pa. 30 g of curing agent (IPDA) and 9 g of crosslinking agent (dithiodipropionic acid dihydrazide) were added and mixed at low speed for 15 minutes. The mixture was briefly vacuum-degassed again and poured into a preheated mold for staged curing. Initial curing took place at 70°C for 1.5 hours, followed by a final curing at 135°C for 3 hours. A slow temperature ramp was used, and the mold was cooled and demolded to obtain the self-healing epoxy insulation material.

[0061] Example 4

[0062] Example 4 provides a self-healing epoxy insulation material, the raw materials of which include: 150g of epoxy resin matrix (CYD-115), 112.5g of thermal conductive filler, 2.8g of amphiphilic polymer (carboxyl-terminated modified silane), 9g of crosslinking agent (dithiodipropionic acid dihydrazide), and 30g of curing agent (IPDA).

[0063] The thermal conductive filler is composed of a mixture of micron-sized hexagonal boron nitride (h-BN, 10 μm, 102.3 g) and multi-walled carbon nanotubes (MWCNT, 10.2 g) in a mass ratio of 10:1.

[0064] Example 4 also provides a method for preparing a self-repairing epoxy insulation material, comprising the following steps:

[0065] 102.3 g of micron-sized hexagonal boron nitride and 10.2 g of multi-walled carbon nanotubes were mixed, 800 g of anhydrous ethanol was added, and ultrasonic dispersion was performed for 30 minutes. 2.8 g of an ethanol solution of a carboxyl-terminated modified silane was added dropwise under stirring. The temperature was raised to 70°C, and the mixture was stirred for reaction for 4 hours. The mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 80°C for 12 hours to obtain a surface-modified thermal conductive filler.

[0066] In a planetary mixer, add 150g of epoxy resin matrix and perform vacuum pre-degassed treatment at 60°C. Under nitrogen, the mixing temperature is controlled at 30°C. Then, 112.5g of surface-modified thermal conductive filler is slowly added in batches. The mixture is stirred at high speed for 30min and ultrasonically dispersed for 20min to obtain a uniform mixture.

[0067] The mixture was stirred and degassed under a vacuum of <100 Pa. 30 g of curing agent (IPDA) and 9 g of crosslinking agent (dithiodipropionic acid dihydrazide) were added and mixed at low speed for 15 minutes. The mixture was briefly vacuum-degassed again and poured into a preheated mold for staged curing. Initial curing took place at 70°C for 1.5 hours, followed by a final curing at 135°C for 3 hours. A slow temperature ramp was used, and the mold was cooled and demolded to obtain the self-healing epoxy insulation material.

[0068] Example 5

[0069] Example 5 provides a self-healing epoxy insulation material, the raw materials of which include: 150g of epoxy resin matrix (CYD-115), 112.5g of thermal conductive filler, 2.8g of amphiphilic polymer (KH-560), 9g of cross-linking agent (monomer based on reversible reaction of imide bond), and 30g of curing agent (IPDA).

[0070] The thermal conductive filler is composed of a mixture of micron-sized hexagonal boron nitride (h-BN, 10 μm, 102.3 g) and multi-walled carbon nanotubes (MWCNT, 10.2 g) in a mass ratio of 10:1.

[0071] Example 5 also provides a method for preparing a self-repairing epoxy insulation material, comprising the following steps:

[0072] 102.3 g of micron-sized hexagonal boron nitride and 10.2 g of multi-walled carbon nanotubes were mixed and added with 800 g of anhydrous ethanol. The mixture was ultrasonically dispersed for 30 minutes. 2.8 g of KH-560 ethanol solution was added dropwise under stirring. The temperature was raised to 70°C and stirred for 4 hours. The mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 80°C for 12 hours to obtain a surface-modified thermal conductive filler.

[0073] In a planetary mixer, add 150g of epoxy resin matrix and perform vacuum pre-degassed treatment at 60°C. Under nitrogen, the mixing temperature is controlled at 30°C. Then, 112.5g of surface-modified thermal conductive filler is slowly added in batches. The mixture is stirred at high speed for 30min and ultrasonically dispersed for 20min to obtain a uniform mixture.

[0074] The mixture was stirred and degassed under a vacuum of <100 Pa. 30g of curing agent (IPDA) and 9g of a monomer crosslinker based on a reversible imide bond reaction were added, mixed at low speed for 15 minutes, and briefly degassed again under vacuum. The mixture was then poured into a preheated mold and cured in stages: an initial cure of 1.5 hours at 70°C, followed by a final cure of 3 hours at 135°C. A slow temperature ramp was used, and the mold was cooled and demolded to obtain the self-healing epoxy insulation material.

[0075] Example 6

[0076] Example 6 provides a self-healing epoxy insulation material, the raw materials of which include: 150g of epoxy resin matrix (CYD-115), 112.5g of thermal conductive filler, 2.8g of amphiphilic polymer (KH-560), 12.4g of cross-linking agent (dithiodipropionic acid dihydrazide), and 45g of curing agent (methyltetrahydrophthalic anhydride MTHPA), and 0.75g of accelerator (2-ethyl-4-methylimidazole, 2E4MZ) is added.

[0077] The thermal conductive filler is composed of a mixture of micron-sized hexagonal boron nitride (h-BN, 10 μm, 102.3 g) and multi-walled carbon nanotubes (MWCNT, 10.2 g) in a mass ratio of 10:1.

[0078] Example 6 also provides a method for preparing a self-repairing epoxy insulation material, comprising the following steps:

[0079] 102.3 g of micron-sized hexagonal boron nitride and 10.2 g of multi-walled carbon nanotubes were mixed and added with 800 g of anhydrous ethanol. The mixture was ultrasonically dispersed for 30 minutes. 2.8 g of KH-560 ethanol solution was added dropwise under stirring. The temperature was raised to 70°C and stirred for 4 hours. The mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 80°C for 12 hours to obtain a surface-modified thermal conductive filler.

[0080] In a planetary mixer, add 150g of epoxy resin matrix and perform vacuum pre-degassed treatment at 60°C. Under nitrogen, the mixing temperature is controlled at 30°C. Then, 112.5g of surface-modified thermal conductive filler is slowly added in batches. The mixture is stirred at high speed for 30min and ultrasonically dispersed for 20min to obtain a uniform mixture.

[0081] The mixture was stirred and degassed under a vacuum of <100 Pa. 45 g of curing agent (MTHPA), 0.75 g of accelerator (2E4MZ), and 12.4 g of crosslinker (dithiodipropionic acid dihydrazide) were added and mixed at low speed for 15 minutes. The mixture was briefly vacuum-degassed again and poured into a preheated mold for staged curing. Initial curing took place at 80°C for 2 hours, followed by a final curing of 4 hours at 150°C. A slow heating procedure was used, followed by cooling and demolding to obtain the self-healing epoxy insulation material.

[0082] Example 7

[0083] Example 7 provides a self-healing epoxy insulation material, the raw materials of which include: 150g of epoxy resin matrix (CYD-115), 112.5g of thermal conductive filler, 2.8g of amphiphilic polymer (KH-560), 9g of cross-linking agent (dithiodipropionic acid dihydrazide), 30g of curing agent (IPDA), and 15g of toughening agent (hydroxy-terminated polydimethylsiloxane).

[0084] The thermal conductive filler is composed of a mixture of micron-sized hexagonal boron nitride (h-BN, 10 μm, 102.3 g) and multi-walled carbon nanotubes (MWCNT, 10.2 g) in a mass ratio of 10:1.

[0085] Example 7 also provides a method for preparing a self-repairing epoxy insulation material, comprising the following steps:

[0086] 102.3 g of micron-sized hexagonal boron nitride and 10.2 g of multi-walled carbon nanotubes were mixed and added with 800 g of anhydrous ethanol. The mixture was ultrasonically dispersed for 30 minutes. 2.8 g of KH-560 ethanol solution was added dropwise under stirring. The temperature was raised to 70°C and stirred for 4 hours. The mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 80°C for 12 hours to obtain a surface-modified thermal conductive filler.

[0087] In a planetary mixer, add 150g of epoxy resin matrix and 15g of hydroxyl-terminated polydimethylsiloxane toughening agent, perform vacuum pre-degassed treatment at 60°C, control the mixing temperature at 30°C under nitrogen, slowly add 112.5g of surface-modified thermal conductive filler in batches, stir at high speed for 30min, and perform ultrasonic dispersion for 20min to obtain a uniform mixture.

[0088] The mixture was stirred and degassed under a vacuum of <100 Pa. 30 g of curing agent (IPDA) and 9 g of crosslinking agent (dithiodipropionic acid dihydrazide) were added and mixed at low speed for 15 minutes. The mixture was briefly vacuum-degassed again and poured into a preheated mold for staged curing. Initial curing took place at 70°C for 1.5 hours, followed by a final curing at 135°C for 3 hours. A slow temperature ramp was used, and the mold was cooled and demolded to obtain the self-healing epoxy insulation material.

[0089] Example 8

[0090] Example 8 provides a self-healing epoxy insulation material, the raw materials of which include: 200g of epoxy resin matrix (CYD-115), 150g of thermal conductive filler, 0.75g of amphiphilic polymer (KH-560), 11g of cross-linking agent (dithiodipropionic acid dihydrazide), and 20g of curing agent (IPDA).

[0091] The thermal conductive filler is composed of a mixture of micron-sized silicon carbide (SiC, 12 μm, 140.6 g) and multi-walled carbon nanotubes (MWCNT, 9.4 g) in a mass ratio of 15:1.

[0092] Example 8 also provides a method for preparing a self-repairing epoxy insulation material, comprising the following steps:

[0093] 140.6 g of micron-sized silicon carbide and 9.4 g of multi-walled carbon nanotubes were mixed, 1000 g of anhydrous ethanol was added, and ultrasonic dispersion was performed for 30 minutes. 0.75 g of KH-560 ethanol solution was added dropwise under stirring. The temperature was raised to 70°C, and the mixture was stirred for reaction for 4 hours. The mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 80°C for 12 hours to obtain a surface-modified thermal conductive filler.

[0094] In a planetary mixer, add 200g of epoxy resin matrix and perform vacuum pre-degassed treatment at 60°C. Under nitrogen, the mixing temperature is controlled at 35°C. Then, 150g of surface-modified thermal conductive filler is slowly added in batches. Stir at high speed for 30min, and perform ultrasonic dispersion for 20min or three-roll grinding to obtain a uniform mixture.

[0095] The mixture was stirred and degassed under a vacuum of <100 Pa. 20 g of curing agent (IPDA) and 11 g of crosslinking agent (dithiodipropionic acid dihydrazide) were added and mixed at low speed for 15 minutes. The mixture was briefly vacuum-degassed again and poured into a preheated mold for staged curing. Initial curing took place at 75°C for 1 hour, followed by a final curing at 140°C for 2.5 hours. A slow temperature ramp was used, and the mold was cooled and demolded to obtain the self-healing epoxy insulation material.

[0096] Comparative Example

[0097] Comparative Example 1

[0098] Comparative Example 1

[0099] Comparative Example 1 provides a pure epoxy resin cured product. The difference from Example 2 is that the raw materials include: 150g of epoxy resin matrix (CYD-115) and 30g of curing agent (isophorone diamine, IPDA). No thermally conductive filler, amphiphilic polymer, crosslinking agent, or toughening agent is included.

[0100] The preparation method of Comparative Example 1 comprises the following steps:

[0101] In a stirring container, 150 g of epoxy resin matrix was added and pre-degassed under vacuum at 60° C. The mixing temperature was controlled at 30° C. under nitrogen.

[0102] Stir and degas the mixture under vacuum at <100 Pa. Add 30g of curing agent (IPDA) and mix at low speed for 15 minutes. Degas briefly under vacuum again. Pour into a preheated mold and cure in stages: initially cure at 70°C for 1.5 hours; heat to 135°C for a final cure of 3 hours. Cool and demold to obtain a pure epoxy cured product.

[0103] Comparative Example 2

[0104] Comparative Example 2 provides an epoxy composite material containing untreated filler. The raw materials differ from Example 2 in that they include: 150 g of epoxy resin matrix (CYD-115), 112.5 g of unmodified thermally conductive filler (h-BN / MWCNT = 10:1), 9 g of crosslinker (dithiodipropionic acid dihydrazide), 30 g of curing agent (IPDA), and 12 g of toughening agent (Jeffamine D-230). The amphiphilic polymer (KH-560) is not included.

[0105] The thermal conductive filler is composed of a mixture of micron-sized hexagonal boron nitride (h-BN, 10 μm, 102.3 g) and multi-walled carbon nanotubes (MWCNT, 10.2 g) in a mass ratio of 10:1.

[0106] The preparation method of Comparative Example 2 comprises the following steps:

[0107] 102.3 g h-BN and 10.2 g MWCNT were directly physically mixed.

[0108] In a planetary mixer, add 150g of epoxy resin matrix and 12g of toughening agent, and pre-degassed in a vacuum at 60°C. Under nitrogen, control the mixing temperature at 30°C, and slowly add 112.5g of untreated thermally conductive filler in batches. Stir at high speed for 30 minutes, and then perform ultrasonic dispersion for 20 minutes or three-roll milling.

[0109] The subsequent steps (degassing, adding curing agent and cross-linking agent, mixing, re-degassing, pouring, and staged curing: 70°C / 1.5h+135°C / 3h) are the same as in Example 2.

[0110] Comparative Example 3

[0111] Comparative Example 3 provides an epoxy composite material without self-healing functionality. The material differs from Example 2 in that the raw materials include: 150 g of epoxy resin matrix (CYD-115), 112.5 g of thermally conductive filler (surface-modified with KH-560), 2.8 g of amphiphilic polymer (KH-560), 30 g of curing agent (IPDA), and 12 g of toughening agent (Jeffamine D-230). The crosslinker (dihydrazide dithiodipropionic acid) is omitted.

[0112] The thermally conductive filler is the same as that in Example 2.

[0113] The preparation method of Comparative Example 3 comprises the following steps:

[0114] The filler surface modification steps are the same as in Example 2.

[0115] The mixing and dispersing steps are the same as in Example 2.

[0116] After degassing, only 30 g of curing agent (IPDA) was added, mixed at low speed for 15 min, and vacuum degassing was performed again briefly. No disulfide crosslinking agent was added.

[0117] The subsequent steps (pouring, staged curing: 70°C / 1.5h+135°C / 3h) are the same as in Example 2.

[0118] Comparative Example 4

[0119] Comparative Example 4 provides an untoughened self-healing epoxy composite material. The materials differ from those in Example 2 in that they include: 150 g of epoxy resin matrix (CYD-115), 112.5 g of thermally conductive filler (surface-modified with KH-560), 2.8 g of amphiphilic polymer (KH-560), 9 g of crosslinker (dithiodipropionic acid dihydrazide), and 30 g of curing agent (IPDA). The toughening agent (Jeffamine D-230) is not included.

[0120] The thermally conductive filler is the same as that in Example 2.

[0121] The preparation method of Comparative Example 4 comprises the following steps:

[0122] The filler surface modification steps are the same as in Example 2.

[0123] In a planetary mixer, add 150g of epoxy resin matrix and pre-degassed it in a vacuum at 60°C. Under nitrogen, control the mixing temperature at 30°C. Slowly add 112.5g of surface-modified thermally conductive filler in batches. Stir at high speed for 30 minutes, then ultrasonically disperse for 20 minutes or perform three-roll milling. Omit the addition of toughening agent.

[0124] The subsequent steps (degassing, adding curing agent and cross-linking agent, mixing, re-degassing, pouring, and staged curing: 70°C / 1.5h+135°C / 3h) are the same as in Example 2.

[0125] Comparative Example 5

[0126] Comparative Example 5 provides a self-healing epoxy composite material containing only micron-sized fillers. The material differs from Example 2 in that the raw materials include: 150 g of epoxy resin matrix (CYD-115), 112.5 g of thermally conductive filler (containing only micron-sized hexagonal boron nitride h-BN, 10 μm), 2.8 g of amphiphilic polymer (KH-560), 9 g of crosslinker (dithiodipropionic acid dihydrazide), 30 g of curing agent (IPDA), and 12 g of toughening agent (Jeffamine D-230). No nanofillers (MWCNTs) are included.

[0127] The preparation method of Comparative Example 5 comprises the following steps:

[0128] 112.5 gh-BN filler was treated with 2.8 g KH-560 as in Example 1.

[0129] The mixing and dispersing steps were the same as in Example 2, but pure h-BN filler was added.

[0130] The subsequent steps (degassing, adding curing agent and cross-linking agent, mixing, re-degassing, pouring, and staged curing: 70°C / 1.5h+135°C / 3h) are the same as in Example 2.

[0131] Comparative Example 6

[0132] Comparative Example 6 provides a self-healing epoxy composite material using different filler ratios. The difference from Example 2 is that the raw materials include: 150g of epoxy resin matrix (CYD-115), 112.5g of thermal conductive filler (total mass unchanged), 2.8g of amphiphilic polymer (KH-560) (accounting for 2.5wt% of filler), 9g of cross-linking agent (dithiodipropionic acid dihydrazide), 30g of curing agent (IPDA), and 12g of toughening agent (Jeffamine D-230).

[0133] The thermal conductive filler is composed of a mixture of micron-sized hexagonal boron nitride (h-BN, 10 μm, 93.75 g) and multi-walled carbon nanotubes (MWCNT, 18.75 g) in a mass ratio of 5:1.

[0134] The preparation method of Comparative Example 6 comprises the following steps:

[0135] A mixed filler of 93.75 g gh-BN and 18.75 g MWCNT was treated with 2.8 g KH-560 according to the method of Example 1.

[0136] The mixing and dispersing steps were the same as in Example 2, but with a filler ratio of 5:1.

[0137] The subsequent steps (degassing, adding curing agent and cross-linking agent, mixing, re-degassing, pouring, and staged curing: 70°C / 1.5h+135°C / 3h) are the same as in Example 2.

[0138] Comparative Example 7

[0139] Comparative Example 7 provides a self-healing epoxy composite material prepared by a single-stage curing process. The difference from Example 2 is that the raw material composition is exactly the same as that of Example 2: 150g of epoxy resin (CYD-115), 112.5g of thermal conductive filler (h-BN / MWCNT=10:1, surface modified with KH-560), 2.8g of amphiphilic polymer (KH-560), 9g of cross-linking agent (dithiodipropionic acid dihydrazide), 30g of curing agent (IPDA), and 12g of toughening agent (Jeffamine D-230).

[0140] The preparation method of Comparative Example 7 comprises the following steps:

[0141] The steps of filler surface modification, mixing and dispersing, degassing, adding curing agent and cross-linking agent, mixing, degassing again, and pouring are the same as those in Example 2.

[0142] The curing step was changed to single-stage curing: the cast mold was directly placed in an oven at 135° C. and cured for 4.5 hours (the total curing time was the same as in Example 2).

[0143] Comparative Example 8

[0144] Comparative Example 8 provides a self-healing epoxy composite material with an improper stoichiometric ratio of the curing agent. The difference from Example 2 is that the raw materials include: 150g of epoxy resin matrix (CYD-115), 112.5g of thermal conductive filler (surface modified with KH-560), 2.8g of amphiphilic polymer (KH-560), 9.75g of cross-linking agent (dithiodipropionic acid dihydrazide), 45g of curing agent (IPDA) (equivalent to 30wt% of the mass of the epoxy resin, stoichiometric ratio of about 1.53, 53% excess amine), and 12g of toughening agent (Jeffamine D-230).

[0145] The thermally conductive filler is the same as that in Example 2.

[0146] The preparation method of Comparative Example 8 comprises the following steps:

[0147] The filler surface modification, mixing and dispersion steps are the same as in Example 2.

[0148] After degassing, 45 g of curing agent (IPDA) and 9.75 g of cross-linking agent were added, mixed at low speed for 15 min, and vacuum degassing was performed again briefly.

[0149] The subsequent steps (pouring, staged curing: 70°C / 1.5h+135°C / 3h) are the same as in Example 2.

[0150] Application Examples

[0151] Application Example 1: Potting Application of High-Performance Power Modules

[0152] background:

[0153] High-performance power modules (such as IGBT and SiC MOSFET modules) generate significant heat during operation, and their operating environments are subject to vibration and temperature cycling. This places extremely high demands on packaging materials: they must conduct heat efficiently to maintain the chip junction temperature within a safe range, provide reliable electrical insulation, and withstand thermal and mechanical stresses for long-term stable operation. Traditional epoxy potting compounds have insufficient thermal conductivity or poor toughness, and are prone to microcracks due to thermal mismatch, compromising heat dissipation and insulation reliability.

[0154] Application solutions:

[0155] The self-repairing epoxy insulating material prepared in Example 2 was used as a potting material to encapsulate a high-power-density SiC MOSFET module comprising multiple power chips, a driving circuit, and a heat dissipation substrate.

[0156] Implementation process:

[0157] Module preparation: Fix the ceramic substrate (such as DBC or AMB) with the power chip and driver circuit soldered on it on the heat dissipation substrate and clean it.

[0158] Mold preparation: Design and prepare a potting mold suitable for the power module size.

[0159] Material preparation: Prepare a sufficient amount of self-repairing epoxy insulation material mixture according to the method of Example 2, and complete the final degassing step.

[0160] Potting: Place the module in the mold and slowly inject the epoxy mixture prepared in step 3 into the mold under a vacuum environment (to further reduce bubbles), ensuring that the power chip, lead bonding points, the edge of the ceramic substrate, and areas that need insulation and protection are completely covered, and in good contact with the heat dissipation substrate.

[0161] Curing: The module with the potting material was cured according to the staged curing process of Example 2 (70° C. / 1.5 h+135° C. / 3 h).

[0162] Demolding and post-processing: After curing is completed, cool and demould to obtain the potted power module.

[0163] Effects and advantages:

[0164] Efficient heat dissipation: The material's high thermal conductivity (significantly improved compared to traditional epoxy) can quickly transfer heat generated by the chip to the heat dissipation substrate, effectively reducing the chip junction temperature and improving the module's power output capacity and efficiency.

[0165] Reliable insulation: The material maintains the excellent electrical insulation properties of epoxy resin, can withstand the high voltage inside the module, and prevent leakage and breakdown.

[0166] Enhanced reliability and lifespan:

[0167] Improved toughness: The addition of toughening agents improves the material's ability to resist thermal stress and mechanical vibration, reducing the risk of initial cracks.

[0168] Self-healing capability: Even if microcracks are generated due to temperature cycling or vibration during long-term operation, the material's dynamic cross-linked network can self-heal at the module's operating temperature (which may reach or approach the self-healing activation temperature) or under specific maintenance heating conditions, preventing crack propagation and restoring insulation performance and thermal conductivity, significantly extending the module's service life and reliability.

[0169] Good processability: Compared with materials with ultra-high filler content, the formulation of Example 2 has relatively good fluidity, making it easier to achieve complete filling and bubble-free potting of complex power module structures.

[0170] Conclusion: The application of this self-healing epoxy insulation material in power module potting can simultaneously solve the key problems of heat dissipation, insulation and long-term reliability (crack resistance and self-healing), and meet the application requirements of high-performance power electronic devices.

[0171] Application Example 2: Structural bonding and thermal conductivity of new energy vehicle power battery packs

[0172] background:

[0173] New energy vehicle power battery packs are composed of numerous battery cells, requiring structural adhesives to secure them into modules or integrate them into the package. Thermally conductive interface materials are also needed to transfer heat generated by the cells to the cooling system. During operation, battery packs experience complex operating conditions such as charge-discharge thermal cycling and vehicle vibration, placing high demands on the mechanical properties, thermal conductivity, durability, and safety of structural adhesives and thermally conductive materials. Microcracks can lead to reduced structural strength, increased thermal resistance, and even insulation failure.

[0174] Application solutions:

[0175] The self-healing epoxy insulation material prepared in Example 2 is used as a structural adhesive and a thermal interface material (TIM) in the assembly of square or soft-pack lithium-ion battery modules.

[0176] Implementation process:

[0177] Preparation of battery cells and structural parts: Clean the surface of the battery cells and the module frame or cooling plate surface.

[0178] Material preparation: Prepare a self-repairing epoxy insulation material mixture according to the method of Example 2, and complete the final degassing.

[0179] Coating and assembly:

[0180] As a thermal interface material: evenly apply the epoxy mixture to the bottom or side of the battery cell in contact with the cooling plate, and control the coating thickness to obtain low thermal resistance.

[0181] As a structural adhesive: Apply the epoxy mixture between battery cells or in areas where the battery cells and module frames need to be bonded and fixed.

[0182] Assemble the battery cells and structural parts according to the design requirements, apply appropriate pressure to ensure full contact between the adhesive layer and the thermal conductive layer and exclude air.

[0183] Curing: The entire assembled battery module was placed in an oven and cured according to the staged curing process of Example 2 (70° C. / 1.5 h+135° C. / 3 h).

[0184] Subsequent assembly: After curing, the module can be used for subsequent electrical connections and battery pack integration.

[0185] Effects and advantages:

[0186] Multifunctionality: One material meets both the strength requirements of structural bonding and the need for thermal conductivity, simplifying the design and manufacturing process of battery packs.

[0187] Effective thermal management: The high thermal conductivity of the material helps to quickly dissipate heat from the battery cell, reduce the temperature difference inside the battery, and improve battery performance, safety and life.

[0188] Structural stability and durability:

[0189] Good bonding strength: The epoxy matrix provides reliable bonding to firmly fix the battery cell.

[0190] Anti-vibration and impact: Toughening agents improve the material's ability to resist vibration and impact during vehicle driving.

[0191] Self-repair of micro-damage: During long-term use, charge-discharge thermal cycling and vibration may cause microcracks in the adhesive or thermal conductive layers of a battery pack. The material's self-healing ability can repair these micro-damages at operating temperatures or under maintenance conditions, maintaining structural integrity and low thermal resistance, and preventing hot spots or structural loosening caused by crack propagation.

[0192] Improved safety: Excellent electrical insulation ensures electrical isolation between cells. Self-healing capabilities can repair potential insulation paths caused by microcracks, further improving safety.

[0193] Performance Testing

[0194] The epoxy insulation materials provided in Examples 1 to 8 and Comparative Examples 1 to 8 were subjected to the following performance tests. The specific performance test methods include:

[0195] 1. Use standard thermal conductivity test methods (such as laser flash method or steady-state method) to measure the thermal conductivity of the material to evaluate its heat dissipation capacity; use infrared thermal imaging to analyze the thermal diffusion characteristics of the material and optimize the thermal management design.

[0196] 2. Use tensile testing (GB / T1040) and impact testing (GB / T1843) to evaluate the material's strength and toughness to ensure its stability under high-load conditions. Perform dynamic mechanical analysis (DMA) testing to determine the material's mechanical properties under different temperature conditions and optimize the cross-linking network design.

[0197] 3. The insulation performance of the material is evaluated through the breakdown voltage test (ASTMD149) and the dielectric constant test (ASTMD150) to ensure its stability in high-voltage electrical environments. The arc resistance test (ASTMD495) is used to verify the material's ability to resist electrical breakdown.

[0198] 4. Conduct microcrack repair experiments to test the material's repair efficiency at a set temperature (80-120°C) and analyze the reversibility of the dynamic cross-linked network. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe microcrack healing. Mechanical property recovery (such as tensile strength recovery) was used to evaluate the material's self-repair ability after repeated damage.

[0199] The performance tests of the epoxy insulation materials provided in Examples 1 to 8 and Comparative Examples 1 to 8 are shown in Table 1 below.

[0200] Table 1 Performance test of epoxy insulation materials provided by Examples 1 to 8 and Comparative Examples 1 to 8

[0201]

[0202] As shown in Table 1, this paper systematically evaluates the performance of a self-healing epoxy insulation composite material based on a dynamic cross-linked network, aiming to achieve a multifunctional integration of high thermal conductivity, excellent mechanical properties, reliable insulation, and self-healing capabilities. By comparing and analyzing the test data of each embodiment and comparative example, the key influences of each component and process parameter on the final material performance are clearly revealed, and the core elements for achieving comprehensive performance optimization are clarified.

[0203] The data of the benchmark comparative example 1 (pure epoxy resin) has inherent low thermal conductivity (about 0.20 W / m·K) and brittleness (impact strength about 4.0 kJ / m 2 ) highlights the necessity of functional modification. The introduction of thermally conductive fillers is a basic means to improve thermal conductivity. However, the comparison results of Comparative Example 2 (containing untreated fillers) and Example 2 (thermal conductivity coefficients are 1.25W / m·K vs 1.85W / m·K, and tensile strength is 65MPa vs 74MPa) clearly confirm that simply adding fillers is not enough to achieve optimal performance. The introduction of a gradient compatibility interface layer (through surface modification with an amphiphilic polymer KH-560) is the key to achieving high performance. It significantly reduces the interfacial thermal resistance between the filler and the matrix, promotes the construction of an efficient heat conduction path, and at the same time enhances the interfacial bonding force and improves the mechanical strength of the material. The lack of GCIL leads to prominent interface problems, which limits the potential of the composite material.

[0204] Comparative Example 3, which is almost identical in composition to Example 2 except for the lack of a dynamic crosslinker, showed a complete loss of self-repair ability (repair efficiency and strength recovery rate were both 0), while Example 2 and other formulations containing a dynamic crosslinker exhibited excellent self-repair effects (efficiency generally ranging from 85-91% and strength recovery rate from 80-86%). This strongly demonstrates that the dynamic network formed by the introduction of reversible covalent bonds containing disulfide bonds (or imide bonds, as in Example 6) is the core mechanism that imparts damage repair capabilities to the material and extends its service life.

[0205] Comparison of Comparative Example 4 / Example 9 (without toughening agent) with Example 2 shows that although their thermal conductivity and self-healing ability are similar, the impact strength of the former (about 4.8 kJ / m 2 ) is significantly lower than the latter (about 6.4kJ / m 2 ), indicating its high brittleness. The addition of a toughening agent (such as Jeffamine D-230 in Example 2) effectively absorbs impact energy and significantly improves the material's toughness, thereby enhancing its ability to resist mechanical stress, vibration, and thermal shock in practical applications and avoiding failure due to brittle fracture. Although different types of toughening agents (such as the silicone oil in Example 8) can also improve toughness, they may be accompanied by the sacrifice of other properties such as strength, requiring a trade-off.

[0206] The thermal conductivity of Comparative Example 5 (containing only micron fillers) (approximately 1.40 W / m·K) is lower than that of Example 2, indicating that the composite structure of micron and nanofillers (h-BN / MWCNT) is more effective in constructing a continuous thermal network. The nanofillers fill the gaps and bridge the micron particles, resulting in a synergistic enhancement effect. Comparative Example 6 further explores different micron / nanofiller ratios (5:1 vs. 10:1 in Example 2), demonstrating that fine-tuning the filler ratio can further fine-tune thermal conductivity (slightly improving it to 1.90 W / m·K), but the impact on processing viscosity and cost must be considered.

[0207] Comparative Example 7 (single-stage curing) exhibited slightly lower performance than Example 2 (staged curing), indicating that staged curing facilitated the formation of a more uniform, lower-stress cross-linked network. Comparative Example 8 (incorrect curing agent stoichiometric ratio) exhibited disastrous consequences, with all key performance indicators experiencing a sharp deterioration. This strongly emphasizes the critical importance of precisely controlling the chemical reaction ratio to achieve the desired polymer network structure and properties.

[0208] In summary, through systematic formulation design and performance evaluation, the present invention successfully demonstrated that by combining an optimized filler system (micro-nano composite, such as h-BN / MWCNT), an efficient interface layer (GCIL, such as KH-560 surface modification), a reversible dynamic cross-linking network (such as disulfide bonds), and an effective toughening agent (such as Jeffamine D-230), it is possible to prepare a high-performance epoxy composite material with high thermal conductivity, excellent self-healing ability, good mechanical toughness, and reliable insulation. Among them, Example 2 shows the most balanced and optimized combination of various performance indicators, representing an ideal example of realizing this type of multifunctional material, and provides a promising solution to meet the stringent application requirements in fields such as high-performance electronic packaging, power equipment insulation, and new energy devices.

[0209] It is obvious to those skilled in the art that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here, and obvious variations or modifications derived therefrom are still within the scope of protection of the claims of the present invention.

Claims

1. A self-repairing epoxy insulation material, characterized in that: The raw materials of the epoxy insulation material include: An epoxy resin matrix and a thermally conductive filler dispersed in the epoxy resin matrix, as well as a cross-linking agent and a curing agent; The thermally conductive filler is surface-modified with an amphiphilic polymer to form a gradient compatibility interface layer on the particle surface, which is used to improve the interface compatibility between the thermally conductive filler and the epoxy resin matrix and reduce the interface thermal resistance; The cross-linking agent contains reversible covalent bonds of disulfide bonds and / or imide bonds, forming a dynamic cross-linking network in the epoxy resin matrix. The dynamic cross-linking network can reversibly break and restructure chemical bonds through external stimulation to enable the epoxy insulation material to have self-repairing ability.

2. The self-repairing epoxy insulation material according to claim 1, characterized in that: The viscosity of the epoxy resin matrix at room temperature is 100 mPa·s to 1000 mPa·s.

3. The self-repairing epoxy insulation material according to claim 1, characterized in that: The mass ratio of the thermally conductive filler to the epoxy resin matrix is (50-150): (100-200); the thermally conductive filler includes a micron-sized inorganic thermally conductive filler and a nano-sized carbon material filler, and the mass ratio of the micron-sized inorganic thermally conductive filler to the nano-sized carbon material filler is (5-15):

1.

4. The self-repairing epoxy insulation material according to claim 3, characterized in that: The micron-sized inorganic thermal conductive filler includes at least one of boron nitride, aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, silicon carbide and silicate; the nano-sized carbon material filler includes at least one of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes and graphene.

5. The self-repairing epoxy insulation material according to claim 1, characterized in that: The amphiphilic polymer accounts for 0.5wt% to 5.0wt% of the mass of the thermal conductive filler; the amphiphilic polymer comprises at least one of functionalized polyether, polyamide, polyurethane, modified silane, polyetheramine and block copolymer.

6. The self-repairing epoxy insulation material according to claim 5, characterized in that: The amphiphilic polymer includes a modified silane compound containing an epoxy or carboxyl terminal group.

7. The self-repairing epoxy insulation material according to claim 1, characterized in that: The added amount of the curing agent is 10wt% to 30wt% of the mass of the epoxy resin matrix; the curing agent includes at least one of aliphatic amines, cycloaliphatic amines, modified polyamides, imidazoles, and acid anhydrides.

8. The self-repairing epoxy insulation material according to any one of claims 1 to 7, characterized in that: The raw materials of the epoxy insulation material also include a toughening agent, and the added amount of the toughening agent is 2wt% to 15wt% of the mass of the epoxy resin matrix; the toughening agent includes at least one of polyether amine, hydroxy silicone oil, block copolymer, epoxy modified rubber, and polyurethane additives.

9. A method for preparing a self-repairing epoxy insulation material, characterized in that: The following steps are involved: Modifying the surface of the thermally conductive filler with an amphiphilic polymer by chemical bonding or physical adsorption to form a gradient compatibility interface layer on the surface of the thermally conductive filler; The surface-modified thermal conductive filler and the epoxy resin matrix are mixed under an inert atmosphere at a mixing temperature of 25° C. to 40° C. to obtain a mixture; The mixture is degassed under vacuum conditions, a curing agent and a cross-linking agent are added, and after uniform mixing, curing is performed in stages, with preliminary curing performed at 60° C. to 80° C. for 1 hour to 2 hours, and then curing is performed at 120° C. to 150° C. for 2 hours to 4 hours, to form a dynamic cross-linking network in the epoxy resin matrix, thereby obtaining the epoxy insulating material.

10. An application of a self-repairing epoxy insulation material, characterized in that: The epoxy insulation material is used for: Encapsulation or potting of high power density electronic components; Insulation of power equipment such as dry-type transformers, motors, reactors, etc. Structural bonding, thermal conductivity or packaging of new energy vehicle power battery packs; Or, occasions where the material is required to have high thermal conductivity, good processing fluidity, excellent insulation properties and self-healing ability.

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