Self-repairing two-component polyurethane heat-conducting structural adhesive and preparation method thereof

Abstract

The invention discloses a self-repairing two-component polyurethane heat-conducting structural adhesive and a preparation method thereof. The self-repairing double-component polyurethane heat-conducting structural adhesive comprises a component A and a component B, the volume ratio of the component A to the component B is (0.9-1.1): 1; the component A comprises 5-10 parts of modified castor oil polyol; 1 to 5 parts of polyol containing a ureido pyrimidone structure; 2 to 5 parts of polyether polyol; 3-5 parts of a chain extender containing disulfide bonds; 0.01 to 0.1 part of a catalyst; 0.5-1 part of an auxiliary agent; 1.5 to 2.5 parts of a physical adsorbent; 0.1 to 0.5 part of a dispersant; 55-70 parts of a first modified heat-conducting filler; the component B comprises the following components in parts by weight: 20-35 parts of an isocyanate-terminated polyurethane prepolymer; 0.5 to 0.8 part of a water absorbent; 70-80 parts of a second modified heat-conducting filler; the first modified heat-conducting filler and the second modified heat-conducting filler are respectively and independently selected from at least one of silane coupling agent modified heat-conducting fillers. The self-repairing type two-component polyurethane heat-conducting structural adhesive disclosed by the invention has high heat conductivity, high mechanical property and efficient self-repairing capability.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a self-healing two-component polyurethane thermally conductive structural adhesive and its preparation method. Background Technology

[0002] With the rapid development of electronic devices towards high power density and high integration, and the continuous improvement of thermal management requirements in fields such as new energy vehicles and high-end energy storage, the reliability of thermally conductive structural adhesives, as a key material that combines structural bonding and thermal conduction functions, faces increasingly severe challenges. Under long-term thermal cycling, mechanical vibration, and stress impact, traditional thermally conductive adhesives are prone to developing microcracks internally or at interfaces, leading to the disruption of heat conduction paths, increased thermal resistance, and ultimately, overheating failure of devices, severely restricting the service life and safety performance of the entire system. Self-healing materials offer a new approach to solving this problem. By introducing dynamic and reversible chemical bonds or supramolecular interactions into the material, it can autonomously repair cracks after damage through external stimuli (such as heat or light), thereby restoring mechanical and functional integrity and significantly improving the material's reliability and service life.

[0003] Currently, research on self-healing systems largely focuses on intrinsically self-healing polymers, such as systems based on Diels-Alder reversible reactions, disulfide bond exchange, hydrogen bonding, or ionic interactions. However, when these self-healing materials are applied to structural adhesives requiring high mechanical strength and high thermal conductivity, a prominent contradiction arises: to obtain sufficient mechanical load-bearing capacity and high thermal conductivity, it is usually necessary to fill the matrix with a large amount of rigid thermally conductive fillers (such as alumina and boron nitride); however, the introduction of high filler content severely restricts the mobility of polymer chain segments, hindering the contact, rearrangement, and exchange of dynamic bonds at the damaged interface, leading to a significant decrease in self-healing efficiency or even failure. This contradiction has become a key bottleneck restricting the practical application of self-healing high-performance thermally conductive structural adhesives. In addition, existing self-healing systems typically require high temperatures above 120°C to achieve self-healing, which poses high safety risks and implementation difficulties in many application scenarios (such as power batteries).

[0004] Therefore, there is an urgent technical need and significant industrial value in how to maintain the excellent mechanical and thermal conductivity of high-filler systems while still endowing materials with efficient and reliable self-healing capabilities, and to achieve structural adhesives that combine high thermal conductivity, high mechanical properties and efficient self-healing capabilities. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide a self-healing two-component polyurethane thermally conductive structural adhesive that can balance high thermal conductivity, high mechanical properties and efficient self-healing ability. Moreover, its self-healing conditions are mild, and it can achieve efficient self-healing of damaged interfaces under temperature of 80-110℃ or ultraviolet irradiation of 280-365nm.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a self-healing two-component polyurethane thermally conductive structural adhesive, comprising component A and component B; wherein the volume ratio of component A to component B is (0.9-1.1):1; Component A, by weight, comprises the following components: 5-10 parts of modified castor oil polyol; 1-5 parts of polyols containing a ureidopyrimidinone structure; 2-5 parts of polyether polyol; 3-5 parts of chain extender containing disulfide bonds; Catalyst 0.01-0.1 parts; Additives: 0.5-1 part; 1.5-2.5 parts of physical adsorbent; Dispersant 0.1-0.5 parts; 55-70 parts of the first modified thermally conductive filler; Component B, by weight, comprises the following components: 20-35 parts of isocyanate-terminated polyurethane prepolymer; 0.5-0.8 parts of absorbent; 70-80 parts of the second modified thermally conductive filler; The first modified thermally conductive filler and the second modified thermally conductive filler are each independently selected from at least one of silane coupling agent modified thermally conductive fillers.

[0007] Furthermore, the silane coupling agent is selected from at least one of aminosilane coupling agents or mercaptosilane coupling agents; the thermally conductive filler is selected from at least one of alumina and aluminum hydroxide.

[0008] The silane coupling agent modified thermally conductive filler of the present invention can be obtained commercially or in-house. The preparation method of the silane coupling agent modified thermally conductive filler includes the following steps: drying the thermally conductive filler at 100-120°C for 2-4 hours, adding it to an acidic ethanol-water solution containing the silane coupling agent, reacting at 70-85°C for 4-6 hours, and then washing and drying to obtain the silane coupling agent modified thermally conductive filler.

[0009] Furthermore, in the acidic ethanol-water solution containing the silane coupling agent, the mass concentration of the silane coupling agent is 3-5 wt%, the volume ratio of ethanol to water is (2-4):1, and the pH value is 4-5.

[0010] Furthermore, the mass ratio of the silane coupling agent to the thermally conductive filler is (0.5-2):100.

[0011] The modified castor oil polyol of this invention is a bio-based polyol compound made primarily from castor oil. Furthermore, the functionality of the modified castor oil polyol is 3-4.

[0012] The modified castor oil polyol of the present invention can be obtained commercially, such as, but not limited to, SY796 from Shanghai Shuyu Chemical Co., Ltd.

[0013] Furthermore, the polyol containing the ureidopyrimidinone structure is a functional polymer obtained by grafting the ureidopyrimidinone supramolecular unit onto the polyether glycol or polyester glycol chain via chemical bonds.

[0014] The polyols containing the ureidopyrimidinone structure of the present invention can be obtained commercially or prepared by existing methods. The present invention provides a method for preparing polyols containing the ureidopyrimidinone structure, comprising the following steps: ① Synthesis of ureidopyrimidinone (UPy-NCO) intermediates containing isocyanate groups: Under nitrogen protection, 2-amino-4-hydroxy-6-methylpyrimidine (MIC) was slowly added to excess hexamethylene diisocyanate (HMDI) in N,N-dimethylformamide (DMF) at a molar ratio of HMDI to MIC of 5:1. The temperature was raised to approximately 100°C, and the reaction was carried out for 24 hours. After the reaction was completed, excess HMDI was removed by vacuum distillation to obtain the UPy-NCO intermediate with an isocyanate group (-NCO) at the end. ②Preparation of hydroxyl-containing ureidopyrimidinone functional molecules (UPy-OH): 2-Amino-2-methyl-1,3-propanediol (AMPD) was dissolved in anhydrous chloroform and other solvents. Under ice bath cooling and stirring, the UPy-NCO intermediate was slowly added dropwise at a molar ratio of AMPD to UPy-NCO of 1:1. The reaction was carried out at room temperature, and infrared spectroscopy (IR) was used to monitor the reaction until the NCO peak essentially disappeared. After purification, UPy-OH, a ureidopyrimidinone functional molecule with hydroxyl groups at the terminal or side chains, was obtained. ③ Synthetic end-NCO prepolymer Strictly dehydrated polyether polyol (polypropylene glycol PPG-1000, number average molecular weight of 1000) is mixed with HMDI at a molar ratio of NCO:OH of 2:1 and reacted at 75-85℃ for 2-4 hours to generate a prepolymer with isocyanate groups at the end. ④ Synthesize polyols containing ureidopyrimidinone structures UPy-OH was added as a chain extender to the terminal-NCO prepolymer; the molar ratio of hydroxyl groups in UPy-OH to NCO groups in the prepolymer was controlled at 1:1; the reaction was carried out at 60-80℃ in the presence of the catalyst dibutyltin dilaurate (DBTDL) until the characteristic peak of NCO was completely disappeared in the IR spectroscopy. The final product was a polyol containing a ureidopyrimidinone structure.

[0015] Furthermore, the functionality of the polyether polyol is 2-3; the molecular weight of the polyether polyol is 400-2000.

[0016] Further, the isocyanate-terminated polyurethane prepolymer is prepared by reacting a polyol with an isocyanate; the mass fraction of NCO in the isocyanate-terminated polyurethane prepolymer is 15%-20%. The polyol is preferably at least one selected from polypropylene glycol, dimer polyester polyol, polytetrahydrofuran glycol, polyethylene glycol, and polyethylene adipate diol; the isocyanate is preferably at least one selected from diphenylmethane diisocyanate, liquefied MDI, and polymeric MDI.

[0017] This invention provides a method for preparing isocyanate-terminated polyurethane prepolymers, comprising the following steps: adding dehydrated polyol and isocyanate to a reaction vessel for dispersion and stirring, heating to 75-85℃ and reacting for 1-2 hours until the NCO content no longer changes during titration, then cooling to obtain the isocyanate-terminated polyurethane prepolymer.

[0018] The amount of polyol and isocyanate used is controlled so that the mass fraction of NCO is 15%-20% of the theoretical amount.

[0019] The dehydration treatment of the polyol includes the following steps: adding the polyol to a reaction vessel for dispersion and stirring, heating to 110-120℃, and simultaneously drawing a vacuum for dehydration for 1-3 hours.

[0020] Furthermore, the chain extender containing disulfide bonds is selected from at least one of bis(hydroxymethyl) disulfide, bis(3-hydroxypropyl) disulfide, and bis(4-hydroxybutyl) disulfide.

[0021] Furthermore, the additive includes at least one of a silane coupling agent or a pigment. Furthermore, the catalyst is selected from at least one of an organotin, organozinc, or organobismuth.

[0022] Furthermore, the physical adsorbent is selected from at least one of molecular sieves.

[0023] Furthermore, the dispersant is an optional wetting and dispersing agent for polyurethane structural adhesives, including but not limited to BYK-9076 from BYK Chemicals.

[0024] Furthermore, the absorbent is selected from p-toluenesulfonyl isocyanate.

[0025] Furthermore, component B, by weight, also includes 0.04-0.08 parts of pigment. The pigment includes, but is not limited to, color paste.

[0026] Secondly, the present invention also provides a method for preparing the self-healing two-component polyurethane thermally conductive structural adhesive, comprising the following steps: preparing component A and component B respectively; The preparation method of component A includes the following steps: According to the formula, add the other components except for the physical adsorbent and the first modified thermally conductive filler into the reaction vessel, stir and disperse them at a planetary speed of 10-15 rpm and a dispersion speed of 300-400 rpm, and vacuum is required during the stirring process; after stirring for 30-35 min, add the molecular sieve and the first modified thermally conductive filler, then increase the dispersion speed to 600-700 rpm and vacuum is applied; stir for 1-1.5 h, during which the vessel is cleaned twice, and after stirring, degas for 30-40 min to obtain component A; The preparation method of component B includes the following steps: According to the formula, add all components except the second modified thermally conductive filler into the reaction vessel, stir and disperse at room temperature, with a planetary speed of 10-15 rpm and a dispersion speed of 300-400 rpm, and vacuum is required during the stirring process; after stirring for 30-35 min, add the second modified thermally conductive filler, then increase the dispersion speed to 600-700 rpm and vacuum is applied; stir for 1-1.5 h, during which the vessel is cleaned twice, and after stirring, degas for 30-40 min to obtain component B; Component A and component B were stirred and mixed evenly according to the volume ratio to prepare a self-healing two-component polyurethane thermally conductive structural adhesive.

[0027] The present invention has the following beneficial effects: The self-healing two-component polyurethane thermally conductive structural adhesive provided by this invention overcomes the technical bottleneck of traditional high-filler thermally conductive adhesives, which struggle to simultaneously achieve high mechanical properties, high thermal conductivity, and efficient self-healing capabilities, by synergistically introducing dynamic disulfide covalent bonds and ureidopyrimidinone supramolecular hydrogen bonds into a multi-component polyurethane system and by surface chemically modifying the thermally conductive filler. The structural adhesive of this invention can trigger efficient repair under medium-low temperature (80-110℃) or ultraviolet light (280-365nm) irradiation conditions. It not only achieves crack healing in the matrix resin but also rebuilds chemical connections at the filler-matrix interface, thereby achieving overall performance recovery with a high retention rate. Simultaneously, this structural adhesive possesses excellent thermal conductivity, high adhesive strength, and good toughness, with moderate viscosity and user-friendly construction processes. It can be widely applied in fields with stringent long-term thermo-mechanical reliability requirements, such as power battery thermal management and high-power electronic device heat dissipation, significantly improving the system's service life and safety performance. Detailed Implementation

[0028] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0029] Where specific experimental steps or conditions are not specified in the examples, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0030] Unless otherwise specified, the temperature in the embodiments of the present invention is room temperature or ambient temperature; room temperature or ambient temperature refers to 25±1℃.

[0031] The materials used in the embodiments and comparative examples of this invention are described below, but are not limited to these materials.

[0032] Modified castor oil polyol: SY796 from Shanghai Shuyu Chemical Co., Ltd., with a functionality of 3.5.

[0033] Polyols containing ureidopyrimidinone structures: prepared in-house, as follows: ① Synthesis of UPy-NCO Under nitrogen protection, MIC was slowly added to excess HMDI in DMF at a molar ratio of 5:1; the temperature was raised to 100°C, and the reaction was allowed to proceed for 24 hours. After the reaction was complete, excess HMDI was removed by vacuum distillation to obtain UPy-NCO. ②Preparation of UPy-OH AMPD was dissolved in anhydrous chloroform and other solvents, and UPy-NCO intermediates were slowly added dropwise under ice bath cooling and stirring. The molar ratio of AMPD to UPy-NCO was 1:1. The reaction was carried out at room temperature, and the NCO peak was monitored by IR until it basically disappeared. After purification, UPy-OH, a ureidopyrimidinone functional molecule with hydroxyl groups at the terminal or side chains, was obtained. ③ Synthetic end-NCO prepolymer Strictly dehydrated polyether polyol (polypropylene glycol PPG-1000, number average molecular weight of 1000) was mixed with HMDI at a molar ratio of NCO:OH of 2:1 and reacted at 80°C for 3 hours to generate terminal-NCO prepolymer. ④ Synthesize polyols containing ureidopyrimidinone structures UPy-OH was added as a chain extender to the terminal-NCO prepolymer; the molar ratio of hydroxyl groups in UPy-OH to NCO groups in the prepolymer was controlled at 1:1; the reaction was carried out at 70°C in the presence of the catalyst DBTDL until the characteristic NCO peaks completely disappeared in the IR spectroscopy. The final product was a polyol containing a ureidopyrimidinone structure.

[0034] Polyether polyol: Polypropylene glycol PPG-1000, with a functionality of 2, a hydroxyl value of 109-115 mgKOH / g, and a number-average molecular weight of 1000.

[0035] Chain extenders containing disulfide bonds: bis(hydroxymethyl) disulfides.

[0036] Organotin catalyst: dibutyltin dilaurate.

[0037] Organic bismuth catalyst: bismuth isooctanoate.

[0038] Additive 1: Silane coupling agent KH-550.

[0039] Additive 2: Pigment; carbon black paste.

[0040] Physical adsorbent: Molecular sieve.

[0041] Dispersant: BYK-9076 from BYK Chemicals.

[0042] Water-absorbing agent: p-Toluenesulfonyl isocyanate.

[0043] Isocyanate-terminated polyurethane prepolymer 1: self-made, prepared as follows: 100 parts of dimer polyester polyol (Baiyuan Chemical BY3022) were added to a reaction vessel for dispersion and stirring, heated to 120°C, and vacuumed. After dehydration for 2 hours, the mixture was cooled to 50°C and taken out for later use. 25 parts of the dehydrated dimer polyester polyol and 70 parts of liquefied MDI (Wanhua Chemical CDMDI-100L) were added to a clean reaction vessel for dispersion and stirring, heated to 80°C, and reacted for 1.5 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain isocyanate-terminated polyurethane prepolymer 1 with an NCO mass fraction of 16.7%.

[0044] Isocyanate-terminated polyurethane prepolymer 2: self-made, the preparation method is as follows: 100 parts of polypropylene glycol (molecular weight 1000) were added to a reaction vessel for dispersion and stirring, heated to 120°C, and vacuumed. After dehydration for 2 hours, the temperature was lowered to 50°C and the product was taken out for use. 30 parts of dehydrated polypropylene glycol and 70 parts of liquefied MDI (Wanhua Chemical CDMDI-100L) were added to a clean reaction vessel for dispersion and stirring, heated to 80°C, and the reaction was continued for 1.5 hours. After the reaction was completed, the product was cooled to room temperature to obtain isocyanate-terminated polyurethane prepolymer 2 with an NCO mass fraction of 16.9%.

[0045] Aminosilane coupling agent modified thermally conductive filler: self-made; the preparation method is as follows: aluminum hydroxide is placed in an oven and dried at 105℃ for 4h; 40g of γ-aminopropyltriethoxysilane, 700g of anhydrous ethanol and 300g of deionized water are added to a container, the pH is adjusted to 4 with glacial acetic acid, and hydrolyzed at room temperature for 30 minutes to obtain silane hydrolysate; the above silane hydrolysate is slowly added to a three-necked flask containing dried aluminum hydroxide, the temperature is raised to 80℃, and the reaction is refluxed for 4.5h; after the reaction is completed, the mixture is filtered, washed with ethanol, and vacuum dried at 80℃ for 12h to obtain aminosilane coupling agent modified thermally conductive filler, which is then sealed for later use.

[0046] Thiol-silane coupling agent modified thermally conductive filler: self-made; the preparation method is as follows: aluminum hydroxide is placed in an oven and dried at 120℃ for 4h; 40g of γ-mercaptopropyltrimethoxysilane, 700g of anhydrous ethanol and 300g of deionized water are added to a container, the pH is adjusted to 4 with glacial acetic acid, and hydrolyzed at room temperature for 30 minutes to obtain silane hydrolysate; the above silane hydrolysate is slowly added to a three-necked flask containing dried aluminum hydroxide, the temperature is raised to 85℃, and the reaction is refluxed for 4h; after the reaction is completed, the mixture is filtered, washed with ethanol, and vacuum dried at 80℃ for 12h to obtain thiol-silane coupling agent modified thermally conductive filler, which is then sealed for later use.

[0047] The preparation steps of the structural adhesives in the examples and comparative examples are as follows: Preparation of Component A: According to the formula, all components except the physical adsorbent and the first modified thermally conductive filler were added to the reactor. The mixture was stirred and dispersed at room temperature with a planetary speed of 12 rpm and a dispersion speed of 300 rpm, while the vacuum was evacuated to -0.08 MPa. After stirring for 30 min, the molecular sieve and the first modified thermally conductive filler were added, and the dispersion speed was increased to 600 rpm. The vacuum was then continued to be evacuated to -0.09 MPa. Stirring was continued for 1-1.5 h, with reactor cleaning performed at 45 min and 75 min of stirring. After stirring was completed, the mixture was degassed under vacuum for 30 min to obtain structural adhesive component A. Preparation of Component B: According to the formula, all components except the second modified thermally conductive filler were added to the reaction vessel. The mixture was stirred and dispersed at room temperature with a planetary speed of 12 rpm and a dispersion speed of 300 rpm. During stirring, a vacuum was applied to maintain the vacuum level in the reaction vessel at -0.07 MPa. After stirring for 30 min, the second modified thermally conductive filler was added, and the dispersion speed was increased to 600 rpm while maintaining the vacuum state and adjusting the vacuum level to -0.09 MPa. During the subsequent 1 h of stirring, the vessel was cleaned every 30 min for a total of two cleanings. After stirring, degassing was performed for 30 min to obtain the structural adhesive component B.

[0048] The structural adhesive was prepared by mixing components A and B at a volume ratio of 1:1.

[0049] Relevant performance tests: Mixed viscosity: determined according to standard GB / T 2794-2013.

[0050] Shear strength: Tested according to standard GB / T 7124-2008, using 3003 aluminum plate.

[0051] Tensile strength and elongation at break: determined in accordance with standard GB / T 528-2009.

[0052] Repair rate: After curing, the standard shear test specimen is completely cut off at the center of the adhesive layer with a sharp blade. The fresh cut surfaces are realigned and tightly bonded, and pressure is applied to maintain contact. The treated specimen is placed in a 100°C oven and heated statically for 1 hour for repair. After being removed and cooled to room temperature, its shear strength is retested; Repair rate calculation: (Repaired strength / Initial strength) × 100%.

[0053] Thermal conductivity: determined in accordance with standard GB / T3399-1982.

[0054] Table 1: Distribution ratios (by weight) and performance test results of each group in the examples and comparative examples

[0055] The above results show that this invention, by synergistically introducing dynamic disulfide covalent bonds and ureidopyrimidinone supramolecular hydrogen bonds into a multi-component polyurethane system and by surface chemically modifying the thermally conductive filler, prepares a self-healing two-component polyurethane thermally conductive structural adhesive. This adhesive can balance high thermal conductivity (thermal conductivity ≥1.30 W / mK), high mechanical properties (shear strength ≥9.9MPa, tensile strength ≥12.5MPa, elongation at break ≥27%), and high self-healing capability. Its self-healing conditions are mild, and efficient repair can be triggered under medium and low temperature (80-110℃) or ultraviolet light (280-365 nm) irradiation conditions. It can not only achieve crack healing in the matrix resin, but also rebuild chemical connections at the filler-matrix interface, thereby achieving overall and high performance recovery (repair rate ≥86%). Moreover, this structural adhesive has moderate viscosity and a user-friendly construction process, and can be widely used in fields with stringent requirements for long-term thermo-mechanical reliability, such as power battery thermal management and high-power electronic device heat dissipation, significantly improving the system's service life and safety performance.

[0056] Component A of Comparative Example 1 / 2, which did not contain modified castor oil polyol or polyether polyol, had poor mechanical properties.

[0057] In Comparative Example 3, component A, which did not contain a polyol with a ureidopyrimidinone structure, exhibited poor mechanical properties and a significantly reduced repair rate.

[0058] The thermally conductive filler in Comparative Example 4 was aluminum hydroxide without surface modification by silane coupling agent, which had poor mechanical properties, reduced thermal conductivity, and significantly decreased repair rate.

[0059] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A self-healing two-component polyurethane thermally conductive structural adhesive, characterized in that, It includes component A and component B; the volume ratio of component A to component B is (0.9-1.1):1; Component A, by weight, comprises the following components: 5-10 parts of modified castor oil polyol; 1-5 parts of polyols containing a ureidopyrimidinone structure; 2-5 parts of polyether polyol; 3-5 parts of chain extender containing disulfide bonds; Catalyst 0.01-0.1 parts; Additives: 0.5-1 part; 1.5-2.5 parts of physical adsorbent; Dispersant 0.1-0.5 parts; 55-75 parts of the first modified thermally conductive filler; Component B, by weight, comprises the following components: 20-35 parts of isocyanate-terminated polyurethane prepolymer; 0.5-0.8 parts of absorbent; 70-80 parts of the second modified thermally conductive filler; The first modified thermally conductive filler and the second modified thermally conductive filler are each independently selected from at least one of silane coupling agent modified thermally conductive fillers.

2. The self-healing two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The silane coupling agent is selected from at least one of aminosilane coupling agents or mercaptosilane coupling agents; the thermally conductive filler is selected from at least one of alumina and aluminum hydroxide.

3. The self-healing two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The preparation method of the silane coupling agent modified thermally conductive filler includes the following steps: drying the thermally conductive filler at 100-120℃ for 2-4 hours, adding it to an acidic ethanol-water solution containing the silane coupling agent, reacting it at 70-85℃ for 4-6 hours, and then washing and drying it to obtain the silane coupling agent modified thermally conductive filler.

4. The self-healing two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The functionality of the modified castor oil polyol is 3-4.

5. The self-healing two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The polyol containing the ureidopyrimidinone structure is a functional polymer obtained by grafting the ureidopyrimidinone supramolecular unit onto the polyether glycol or polyester glycol chain through chemical bonds.

6. The self-healing two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The functionality of the polyether polyol is 2-3; the number average molecular weight of the polyether polyol is 400-2000.

7. The self-healing two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The isocyanate-terminated polyurethane prepolymer is prepared by reacting polyol with isocyanate; the mass fraction of NCO in the isocyanate-terminated polyurethane prepolymer is 15%-20%. The polyol is selected from at least one of polypropylene glycol, dimer polyester polyol, polytetrahydrofuran glycol, polyethylene glycol, and polyethylene adipate diol; the isocyanate is selected from at least one of diphenylmethane diisocyanate, liquefied MDI, and polymeric MDI.

8. The self-healing two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, The chain extender containing disulfide bonds is selected from at least one of bis(hydroxymethyl) disulfide, bis(3-hydroxypropyl) disulfide, and bis(4-hydroxybutyl) disulfide; The additives include at least one of silane coupling agents or pigments; The catalyst is selected from at least one of organotin, organozinc, and organobismuth; The physical adsorbent is selected from at least one of molecular sieves; The absorbent is selected from p-toluenesulfonyl isocyanate.

9. The self-healing two-component polyurethane thermally conductive structural adhesive according to claim 1, characterized in that, Component B, by weight, also includes 0.04-0.08 parts of pigment.

10. The method for preparing the self-healing two-component polyurethane thermally conductive structural adhesive according to any one of claims 1-8, characterized in that, Includes the following steps: Prepare component A and component B separately; The preparation method of component A includes the following steps: According to the formula, add the other components except for the physical adsorbent and the first modified thermally conductive filler into the reaction vessel, stir and disperse them at a planetary speed of 10-15 rpm and a dispersion speed of 300-400 rpm, and vacuum is required during the stirring process; after stirring for 30-35 min, add the molecular sieve and the first modified thermally conductive filler, then increase the dispersion speed to 600-700 rpm and vacuum is applied; stir for 1-1.5 h, during which the vessel is cleaned twice, and after stirring, degas for 30-40 min to obtain component A; The preparation method of component B includes the following steps: According to the formula, add all components except the second modified thermally conductive filler into the reaction vessel, stir and disperse at room temperature, with a planetary speed of 10-15 rpm and a dispersion speed of 300-400 rpm, and vacuum is required during the stirring process; after stirring for 30-35 min, add the second modified thermally conductive filler, then increase the dispersion speed to 600-700 rpm and vacuum is applied; stir for 1-1.5 h, during which the vessel is cleaned twice, and after stirring, degas for 30-40 min to obtain component B; Component A and component B were stirred and mixed evenly according to the volume ratio to prepare a self-healing two-component polyurethane thermally conductive structural adhesive.

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