A heat cycle resistant bio-based polyurethane thermal conductive adhesive and a preparation method thereof

Abstract

The application discloses a kind of heat cycle-resistant bio-based polyurethane heat-conducting adhesive and preparation method thereof, it is related to polyurethane adhesive technical field.The application is prepared by the preparation of bisphenol A modified bio-based polyester polyol, combined with the synergistic effect of delayed type organic tertiary amine catalyst and organic metal auxiliary catalyst, to ensure the controllability and operation window of initial curing process, at the same time, the surface of heat-conducting filler is modified by zirconium series bridging coupling agent, a transition layer with dynamic exchange potential is constructed between filler and resin matrix through zirconium-oxygen coordination bond, then, non-volatile ionic liquid is introduced, so that the zirconium series dynamic network completes topological reconstruction in the non-equilibrium state of limited molecular chain movement, and fullerene particles are implanted into the gap of resin network, and the dynamic bond exchange of zirconium series bridging layer produces synergistic dissipation effect, so that the matrix realizes the balance of high thermal conductivity and mechanical property, and the heat-conducting adhesive is endowed with excellent heat cycle-resistant aging ability.

Description

Technical Field

[0001] This invention relates to the field of polyurethane adhesive technology, specifically to a thermally resistant bio-based polyurethane thermally conductive adhesive and its preparation method. Background Technology

[0002] High-power devices in energy storage fields such as new energy power batteries, power electronic modules, and wind power generation frequently undergo heating and cooling cycles during operation, resulting in a severe "thermal-mechanical coupling" failure problem. Due to the order-of-magnitude mismatch between the coefficient of linear expansion (CTE) of polyurethane thermally conductive potting compound / structural adhesive and the metal substrate (such as copper, aluminum, and steel) (polyurethane CTE is approximately 50-200 ppm / ℃, copper approximately 17 ppm / ℃, and aluminum approximately 23 ppm / ℃), huge internal stress will accumulate at the bonding interface during thermal cycling. This stress can reach 5-15 MPa, exceeding the intrinsic strength of most structural adhesives, ultimately leading to interface debonding and cracking failure.

[0003] Existing technologies mainly employ the following strategies, but none of them fundamentally solve the problem of stress accumulation: 1. Increase crosslinking density or introduce rigid segments (such as patent CN121537920A, Nantong Gaomeng) → use "hardness" to resist "force", sacrificing toughness; 2. Adding flexible polyether segments or plasticizers to buffer stress → softens the force, but significantly reduces high-temperature strength; 3. Introducing self-healing mechanisms such as dynamic disulfide bonds (Tinci Materials CN202510864122.3) or coordination bonds (Jiangsu Shituo New Materials) → can repair performance after failure, but it is a remedial solution of "closing the barn door after the horse has bolted" and fails to actively intervene in the stress accumulation stage.

[0004] The common limitation of the above-mentioned technical approaches is that they all respond only after stress has already damaged (or even fractured) the material, rather than continuously intervening during the stress accumulation process. Essentially, these strategies still treat the polymer network as a "static" cross-linked network.

[0005] Recent advances in dynamic covalent chemistry have opened new avenues for understanding this challenge. Research from Northwestern University and BASF clearly demonstrates that zirconium acetylacetonate (Zr(acac)4) undergoes thermal activation within a polyurethane network, transforming into a more active urethane exchange catalyst. This process is associated with the irreversible loss of acetylacetonate ligands. Cross-experiments further confirm that only thermally activated Zr(acac)4 in the presence of a polyurethane network can enhance urethane exchange. This implies that the activation of the dynamic alcoholysis network is not simply temperature-dependent but also depends on external network conditions. This mechanism has not yet been applied to the "active management of thermal stress" in thermally conductive structural adhesives / potting compounds. Summary of the Invention

[0006] The purpose of this invention is to provide a thermally resistant bio-based polyurethane thermally conductive adhesive and its preparation method, so as to solve the problems existing in the prior art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a thermally resistant bio-based polyurethane thermally conductive adhesive, wherein the thermally resistant bio-based polyurethane thermally conductive adhesive comprises component A and component B; component A comprises bisphenol A modified bio-based polyester polyol, catalyst composition, thermally conductive filler, ionic liquid, and modified fullerene microparticles; component B comprises polymeric MDI, thermally conductive filler, and p-toluenesulfonyl isocyanate.

[0008] In this system, p-toluenesulfonyl isocyanate is used as a chemical dehydrating agent. Its monoisocyanate groups preferentially react with water adsorbed on the surface of the thermally conductive filler and trace amounts of moisture in the system, removing moisture and inhibiting side reactions between moisture and isocyanate, avoiding the generation of bubbles and urea bond defects, and ensuring the compactness of the cured adhesive layer. After the reaction, p-toluenesulfonyl isocyanate generates a stable sulfonamide structure and is end-capped, without participating in the construction of the crosslinking network.

[0009] A method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive includes the following steps: (1) Mix bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, catalyst composition, thermally conductive filler, ionic liquid, modified fullerene microparticles and dehydrating agent evenly to obtain component A; (2) Mix polymeric MDI, thermally conductive filler, and p-toluenesulfonyl isocyanate to obtain component B; (3) Mix component A and component B, degas under vacuum, and then cure under deep supercooling to obtain thermally resistant bio-based polyurethane thermally conductive adhesive.

[0010] Further, the preparation method of the bisphenol A modified bio-based polyester polyol in step (1) is as follows: dimer acid, sebacic acid, neopentyl glycol, 1,4-butanediol and bisphenol compounds are first dehydrated at 160°C for 1-2 hours, and then polycondensed at 220°C for 3 hours under the action of tetrabutyl titanate catalyst, and then vacuum reduced at 240°C to an acid value of 3 mgKOH / g to obtain bisphenol A modified bio-based polyester polyol with a hydroxyl value of 80-180 mgKOH / g.

[0011] Furthermore, the mass ratio of the dimer acid, sebacic acid, neopentyl glycol, 1,4-butanediol, and tetrabutyl titanate catalyst is 100:25-50:28-45:8-18:0.03-0.08.

[0012] Furthermore, the bisphenol compounds account for 10-30% of the total molar amount of the diols.

[0013] Furthermore, the bisphenol compound is at least one of bisphenol A and bio-based bisphenols.

[0014] Further, the preparation method of the bio-based bisphenol is as follows: vanillin is dissolved in anhydrous ethanol, sodium borohydride is added under ice bath conditions, and the mixture is stirred at 500 rpm for 4 hours. After the reaction is completed, the solvent is removed by extraction, washing, and rotary evaporation to obtain vanillin alcohol; the mass ratio of vanillin to anhydrous ethanol is 1:8-15; the amount of sodium borohydride is 1.1-1.5 eq of the molar amount of vanillin; vanillin alcohol and guaiacol are mixed at a molar ratio of 1:1.05, and 0.01 times the mass of vanillin alcohol of p-toluenesulfonic acid is added. The mixture is stirred at 110°C for 6 hours, during which the generated water is removed through a water separator. After the reaction solution is cooled, the solid precipitates and is purified by recrystallization to obtain the product. Furthermore, in step (1), the mass ratio of the bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, catalyst composition, thermally conductive filler, ionic liquid, modified fullerene microparticles, and dehydrating agent is 10~30:10~40:4~10:0.03-0.5:80~150:1~4:0.02~1:1~3.

[0015] Further, the ionic liquid in step (1) is at least one of 1-butyl-3-methylimidazolium hexafluorophosphate and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0016] Further, the preparation method of the modified fullerene microparticles in step (1) is as follows: fullerene is dissolved in anhydrous toluene, and under nitrogen protection, 10wt% potassium hydroxide-methanol solution is added dropwise. The temperature is raised to 60℃, and the mixture is stirred at 500rpm for 12h. After the reaction is completed, most of the toluene is removed by rotary evaporation. The residue is dialyzed with deionized water for 48h, and the molecular weight cutoff is 1000Da. The residue is then freeze-dried at -48℃ for 36h to obtain pretreated fullerene. The mass ratio of the fullerene, anhydrous toluene, and 10wt% potassium hydroxide-methanol solution is 1:200:20. The pretreated fullerene is then... Fullerene was dispersed in anhydrous toluene and sonicated at 21 kHz for 30 min. Then, 1H,1H,2H,2H-perfluorooctyltriethoxysilane and glacial acetic acid were added, and the mixture was heated to 80 °C and refluxed with stirring for 8 h. After the reaction was completed, the mixture was centrifuged at 5000 rpm for 5 min, and the solid was collected. It was washed three times with toluene and anhydrous ethanol, and finally dried under vacuum at 60 °C to constant weight to obtain the final product. The mass ratio of the pretreated fullerene, anhydrous toluene, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, and glacial acetic acid was 0.5:100:0.2:0.1.

[0017] Furthermore, the catalyst composition in step (1) consists of 2,2'-dimorpholine diethyl ether, an organometallic catalyst, and zirconium acetylacetonate, with a mass ratio of 0.1-0.5:0.03-0.2:0.1-0.5.

[0018] Furthermore, the organometallic catalyst is at least one of bismuth neodecanoate and zinc neodecanoate.

[0019] Furthermore, in step (2), the mass ratio of polymeric MDI, thermally conductive filler, and p-toluenesulfonyl isocyanate is 20:100:1.

[0020] Furthermore, the thermally conductive filler described in steps (1) and (2) is a compound powder of alumina and aluminum hydroxide, and its surface is treated with zirconium acetylacetonate.

[0021] Furthermore, the mass ratio of alumina to aluminum hydroxide is 50:30; the particle size of both alumina and aluminum hydroxide is 10~100μm.

[0022] Furthermore, the specific steps of the deep supercooling curing treatment described in step (3) are as follows: cure in an environment of -20 to -40°C for 3 to 4 hours, and then heat to 60 to 80°C for 4 to 8 hours.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention relates to the preparation of bisphenol A-modified bio-based polyester polyols. Aromatic secondary hydroxyl groups are introduced into the main chain as core sites for dynamic exchange reactions. Combined with the synergistic effect of a delayed organic tertiary amine catalyst and an organometallic auxiliary catalyst, the main reaction between isocyanate and hydroxyl groups is dominated in the room temperature to medium-low temperature range, ensuring the controllability and operating window of the initial curing process. Simultaneously, a zirconium-based bridging coupling agent is used to modify the surface of the thermally conductive filler, constructing a transition layer with dynamic exchange potential between the filler and the resin matrix through zirconium-oxygen coordination bonds. This provides an active interface for the subsequent high-temperature alcoholysis reaction of urethane bonds. Finally, a non-volatile ionic liquid is introduced into the mixed components, utilizing its ion pinning effect to induce... The conductive system enters a deep supercooled state, enabling the zirconium-based dynamic network to undergo topological reconstruction under a non-equilibrium state with restricted molecular chain movement. This results in a cured structure that combines high density with rapid stress relaxation. Simultaneously, fullerene particles are implanted into the gaps in the resin network. Leveraging their conjugated spherical structure and molecular-level rotational freedom, these particles absorb shear energy through local rotational relaxation under alternating thermal stress. Furthermore, they generate a synergistic dissipation effect through dynamic bond exchange with the zirconium-based bridging layer, effectively suppressing the initiation and propagation of interfacial microcracks. As a result, the matrix achieves a balance between high thermal conductivity and mechanical properties while endowing the thermally conductive adhesive with excellent resistance to thermal cycling aging, allowing it to maintain interfacial integrity and thermal conductivity stability in a wide temperature range service environment. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The test methods for various indicators of the thermally resistant bio-based polyurethane thermally conductive adhesive prepared in the following embodiments are as follows: Initial shear strength: The lap shear strength of ternary aluminum specimens was tested according to GB / T 7124 using examples and comparative examples of the same size.

[0026] Thermal cycling strength retention rate: Example and comparative samples of the same size were subjected to 1000 cycles of thermal cycling from -40°C to 85°C according to GB / T 25117. Each cycle involved holding at -40°C for 15 minutes, then raising the temperature from -40°C to 85°C at a rate of 8.33°C / min, and finally holding at 85°C for 15 minutes before cooling back to -40°C at a rate of 8.33°C / min. This constituted one cycle. The shear strength before and after aging was tested according to GB / T 7124, and the strength retention rate was calculated.

[0027] High-temperature shear strength: The lap shear strength of the same size examples and comparative examples after 1000 hours at 85℃ was tested according to GB / T 7124.

[0028] Thermal conductivity: The thermal conductivity under steady-state conditions was tested using examples and comparative examples of the same size according to ASTM D5470.

[0029] Aging strength retention rate: Examples and comparative examples of the same size were aged for 1000 hours at 85°C and 85%RH according to GB / T 16422.3. The shear strength before and after aging was tested according to GB / T 7124, and the strength retention rate was calculated.

[0030] Example 1 (1) Alumina and aluminum hydroxide are compounded and then mixed with zirconium acetylacetonate, anhydrous ethanol and deionized water. The mixture is stirred at 300 rpm for 30 min, heated to 50 °C, stirred for another 30 min, and finally dried at 85 °C and a vacuum of 5 Pa for 1 h to obtain a thermally conductive filler. The mass ratio of alumina, aluminum hydroxide, zirconium acetylacetonate, anhydrous ethanol and deionized water is 50:30:1.5:5:0.08. The particle size of both alumina and aluminum hydroxide is 10 μm. (2) Fullerene was dissolved in anhydrous toluene, and under nitrogen protection, 10 wt% potassium hydroxide-methanol solution was added dropwise. The temperature was raised to 60 °C, and the mixture was stirred at 500 rpm for 12 h. After the reaction was completed, most of the toluene was removed by rotary evaporation. The residue was dialyzed with deionized water for 48 h, and the molecular weight cutoff was 1000 Da. The residue was then freeze-dried at -48 °C for 36 h to obtain pretreated fullerene. The mass ratio of the fullerene, anhydrous toluene, and 10 wt% potassium hydroxide-methanol solution was 1:200:20. The pretreated fullerene was dispersed in anhydrous toluene for 21 h. The mixture was sonicated at kHz for 30 min, then 1H,1H,2H,2H-perfluorooctyltriethoxysilane and glacial acetic acid were added. The mixture was heated to 80 °C and refluxed with stirring for 8 h. After the reaction was completed, the mixture was centrifuged at 5000 rpm for 5 min, and the solid was collected. It was washed three times with toluene and anhydrous ethanol, and finally dried under vacuum at 60 °C to constant weight to obtain modified fullerene microparticles. The mass ratio of the pretreated fullerene, anhydrous toluene, 1H,1H,2H,2H-perfluorooctyltriethoxysilane and glacial acetic acid was 0.5:100:0.2:0.1. (3) Vanillin was dissolved in anhydrous ethanol, and sodium borohydride was added under ice bath conditions. The mixture was stirred at 500 rpm for 4 hours. After the reaction was completed, the solvent was removed by extraction, washing, and rotary evaporation to obtain vanillin alcohol. The mass ratio of vanillin to anhydrous ethanol was 1:8. The amount of sodium borohydride was 1.1 eq of the molar amount of vanillin. Vanillin alcohol and guaiacol were mixed at a molar ratio of 1:1.05, and 0.01 times the mass of p-toluenesulfonic acid of vanillin alcohol was added. The mixture was stirred at 110°C for 6 hours. The generated water was removed using a water separator. After the reaction solution cooled, a solid precipitated and was purified by recrystallization to obtain bio-based bisphenol. Dimeric acid, sebacic acid, neopentyl glycol, 1,4-butanediol, and bio-based bisphenol were first dehydrated at 160℃ for 1 hour, and then polycondensed at 220℃ for 3 hours under the catalysis of tetrabutyl titanate. The mixture was then vacuum reduced to an acid value of 3 mg KOH / g at 240℃ to obtain a bisphenol A-modified bio-based polyester polyol with a hydroxyl value of 80 mg KOH / g. The dimer acid, sebacic acid, and neopentyl glycol... The mass ratio of 1,4-butanediol and tetrabutyl titanate catalyst is 100:25:28:8:0.03; the bio-based bisphenol accounts for 10-30% of the total diol molar amount; bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, catalyst composition, thermally conductive filler, 1-butyl-3-methylimidazolium hexafluorophosphate, modified fullerene microparticles, and dehydrating agent are mixed evenly to obtain component A; the bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, and catalyst composition... The mass ratio of the material, thermally conductive filler, 1-butyl-3-methylimidazolium hexafluorophosphate, modified fullerene microparticles, and dehydrating agent is 10:10:4:0.03:80:1:0.02:1; the polyether polyol is specifically polyether polyol PPG1000; the chain extender is 1,4-butanediol; the catalyst composition consists of 2,2'-dimorpholine diethyl ether, bismuth neodecanoate, and zirconium acetylacetonate in a mass ratio of 0.1:0.03:0.1; the dehydrating agent is 3A molecular sieve. (4) Mix polymeric MDI, thermally conductive filler and p-toluenesulfonyl isocyanate to obtain component B; the mass ratio of polymeric MDI, thermally conductive filler and p-toluenesulfonyl isocyanate is 20:100:1; the polymeric MDI is specifically polymeric MDI PM-200. (5) Mix component A and component B at a mass ratio of 1:1, degas under vacuum, and then cure under deep supercooling. Place the mixture in a -20°C environment for 3 hours and then heat it to 60°C for 8 hours to obtain a thermally resistant bio-based polyurethane thermally conductive adhesive.

[0031] Example 2 (1) Alumina and aluminum hydroxide are compounded and then mixed with zirconium acetylacetonate, anhydrous ethanol and deionized water. The mixture is stirred at 300 rpm for 30 min, heated to 50 °C, stirred for another 30 min, and finally dried at 85 °C and a vacuum of 5 Pa for 1 h to obtain a thermally conductive filler. The mass ratio of alumina, aluminum hydroxide, zirconium acetylacetonate, anhydrous ethanol and deionized water is 50:30:1.5:5:0.08. The particle size of both alumina and aluminum hydroxide is 50 μm. (2) Fullerene was dissolved in anhydrous toluene, and under nitrogen protection, 10 wt% potassium hydroxide-methanol solution was added dropwise. The temperature was raised to 60 °C, and the mixture was stirred at 500 rpm for 12 h. After the reaction was completed, most of the toluene was removed by rotary evaporation. The residue was dialyzed with deionized water for 48 h, and the molecular weight cutoff was 1000 Da. The residue was then freeze-dried at -48 °C for 36 h to obtain pretreated fullerene. The mass ratio of the fullerene, anhydrous toluene, and 10 wt% potassium hydroxide-methanol solution was 1:200:20. The pretreated fullerene was dispersed in anhydrous toluene for 21 h. The mixture was sonicated at kHz for 30 min, then 1H,1H,2H,2H-perfluorooctyltriethoxysilane and glacial acetic acid were added. The mixture was heated to 80 °C and refluxed with stirring for 8 h. After the reaction was completed, the mixture was centrifuged at 5000 rpm for 5 min, and the solid was collected. It was washed three times with toluene and anhydrous ethanol, and finally dried under vacuum at 60 °C to constant weight to obtain modified fullerene microparticles. The mass ratio of the pretreated fullerene, anhydrous toluene, 1H,1H,2H,2H-perfluorooctyltriethoxysilane and glacial acetic acid was 0.5:100:0.2:0.1. (3) Vanillin was dissolved in anhydrous ethanol, and sodium borohydride was added under ice bath conditions. The mixture was stirred at 500 rpm for 4 hours. After the reaction was completed, the solvent was removed by extraction, washing, and rotary evaporation to obtain vanillin alcohol. The mass ratio of vanillin to anhydrous ethanol was 1:12. The amount of sodium borohydride used was 1.3 eq of the molar amount of vanillin. Vanillin alcohol and guaiacol were mixed at a molar ratio of 1:1.05, and 0.01 times the mass of p-toluenesulfonic acid of vanillin alcohol was added. The mixture was stirred at 110°C for 6 hours. The generated water was removed by a water separator, and the solid precipitated after the reaction solution cooled. After recrystallization and purification, bio-based bisphenol was obtained. Dimeric acid, sebacic acid, neopentyl glycol, 1,4-butanediol, and bio-based bisphenol were first dehydrated at 160℃ for 1.5 h, and then polycondensed at 220℃ for 3 h under the catalysis of tetrabutyl titanate. The mixture was then vacuum reduced to an acid value of 3 mg KOH / g at 240℃ to obtain bisphenol A-modified bio-based polyester polyol with a hydroxyl value of 130 mg KOH / g. The dimer acid, sebacic acid, and neopentyl glycol... The mass ratio of 1,4-butanediol and tetrabutyl titanate catalyst is 100:39:36:13:0.06; the bio-based bisphenol accounts for 10-30% of the total diol molar amount; bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, catalyst composition, thermally conductive filler, 1-butyl-3-methylimidazolium hexafluorophosphate, modified fullerene microparticles, and dehydrating agent are mixed evenly to obtain component A; the bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, and catalyst composition... The mass ratio of the material, thermally conductive filler, 1-butyl-3-methylimidazolium hexafluorophosphate, modified fullerene microparticles, and dehydrating agent is 20:25:7:0.26:120:2.5:0.5:2; the polyether polyol is specifically polyether polyol PPG1000; the chain extender is 1,4-butanediol; the catalyst composition consists of 2,2'-dimorpholine diethyl ether, bismuth neodecanoate, and zirconium acetylacetonate in a mass ratio of 0.3:0.11:0.3; and the dehydrating agent is 3A molecular sieve. (4) Mix polymeric MDI, thermally conductive filler and p-toluenesulfonyl isocyanate to obtain component B; the mass ratio of polymeric MDI, thermally conductive filler and p-toluenesulfonyl isocyanate is 20:100:1; the polymeric MDI is specifically polymeric MDI PM-200. (5) Mix component A and component B at a mass ratio of 1:1, degas under vacuum, and then cure under deep supercooling. Place the mixture in a -30℃ environment for 3.5h and then heat it to 70℃ for 5h to obtain a thermally resistant bio-based polyurethane thermally conductive adhesive.

[0032] Example 3 (1) Alumina and aluminum hydroxide are compounded and then mixed with zirconium acetylacetonate, anhydrous ethanol and deionized water. The mixture is stirred at 300 rpm for 30 min, heated to 50 °C, stirred for another 30 min, and finally dried at 85 °C and a vacuum of 5 Pa for 1 h to obtain a thermally conductive filler. The mass ratio of alumina, aluminum hydroxide, zirconium acetylacetonate, anhydrous ethanol and deionized water is 50:30:1.5:5:0.08. The particle size of both alumina and aluminum hydroxide is 100 μm. (2) Fullerene was dissolved in anhydrous toluene, and under nitrogen protection, 10 wt% potassium hydroxide-methanol solution was added dropwise. The temperature was raised to 60 °C, and the mixture was stirred at 500 rpm for 12 h. After the reaction was completed, most of the toluene was removed by rotary evaporation. The residue was dialyzed with deionized water for 48 h, and the molecular weight cutoff was 1000 Da. The residue was then freeze-dried at -48 °C for 36 h to obtain pretreated fullerene. The mass ratio of the fullerene, anhydrous toluene, and 10 wt% potassium hydroxide-methanol solution was 1:200:20. The pretreated fullerene was dispersed in anhydrous toluene for 21 h. The mixture was sonicated at kHz for 30 min, then 1H,1H,2H,2H-perfluorooctyltriethoxysilane and glacial acetic acid were added. The mixture was heated to 80 °C and refluxed with stirring for 8 h. After the reaction was completed, the mixture was centrifuged at 5000 rpm for 5 min, and the solid was collected. It was washed three times with toluene and anhydrous ethanol, and finally dried under vacuum at 60 °C to constant weight to obtain modified fullerene microparticles. The mass ratio of the pretreated fullerene, anhydrous toluene, 1H,1H,2H,2H-perfluorooctyltriethoxysilane and glacial acetic acid was 0.5:100:0.2:0.1. (3) Vanillin was dissolved in anhydrous ethanol, and sodium borohydride was added under ice bath conditions. The mixture was stirred at 500 rpm for 4 hours. After the reaction was completed, the solvent was removed by extraction, washing, and rotary evaporation to obtain vanillin alcohol. The mass ratio of vanillin to anhydrous ethanol was 1:15. The amount of sodium borohydride was 1.5 eq of the molar amount of vanillin. Vanillin alcohol and guaiacol were mixed at a molar ratio of 1:1.05, and 0.01 times the mass of p-toluenesulfonic acid of vanillin alcohol was added. The mixture was stirred at 110°C for 6 hours. The generated water was removed by a water separator, and after the reaction solution cooled, a solid precipitated. This solid was then purified by recrystallization to obtain bio-based bisphenol. Dimeric acid, sebacic acid, neopentyl glycol, 1,4-butanediol, and bio-based bisphenol were first dehydrated at 160℃ for 2 hours, and then polycondensed at 220℃ for 3 hours under the catalysis of tetrabutyl titanate. The mixture was then vacuum reduced to an acid value of 3 mg KOH / g at 240℃ to obtain bisphenol A-modified bio-based polyester polyol with a hydroxyl value of 80–180 mg KOH / g. The dimer acid, sebacic acid, ... The mass ratio of neopentyl glycol, 1,4-butanediol, and tetrabutyl titanate catalyst is 100:50:45:18:0.08; the bio-based bisphenol accounts for 10-30% of the total diol molar amount; bisphenol A-modified bio-based polyester polyol, polyether polyol, chain extender, catalyst composition, thermally conductive filler, 1-butyl-3-methylimidazolium hexafluorophosphate, modified fullerene microparticles, and dehydrating agent are mixed evenly to obtain component A; the bisphenol A-modified bio-based polyester polyol, polyether polyol, chain extender, ... The mass ratio of the catalyst composition, thermally conductive filler, 1-butyl-3-methylimidazolium hexafluorophosphate, modified fullerene microparticles, and dehydrating agent is 30:40:10:0.5:150:4:1:3; the polyether polyol is specifically polyether polyol PPG1000; the chain extender is 1,4-butanediol; the catalyst composition consists of 2,2'-dimorpholine diethyl ether, bismuth neodecanoate, and zirconium acetylacetonate in a mass ratio of 0.5:0.2:0.5; the dehydrating agent is 3A molecular sieve. (4) Mix polymeric MDI, thermally conductive filler and p-toluenesulfonyl isocyanate to obtain component B; the mass ratio of polymeric MDI, thermally conductive filler and p-toluenesulfonyl isocyanate is 20:100:1; the polymeric MDI is specifically polymeric MDI PM-200. (5) Mix component A and component B at a mass ratio of 1:1, degas under vacuum, and then cure under deep supercooling. Place the mixture in a -40℃ environment for 4 hours and then heat it to 80℃ for 4 hours to obtain a thermally resistant bio-based polyurethane thermally conductive adhesive.

[0033] Comparative Example 1 The difference between Comparative Example 1 and Example 2 lies in step (3). Step (3) is changed to: dissolving vanillin in anhydrous ethanol, adding sodium borohydride under ice bath conditions, stirring at 500 rpm for 4 hours, and after the reaction is completed, removing the solvent by extraction, washing, and rotary evaporation to obtain vanillin alcohol; the mass ratio of vanillin to anhydrous ethanol is 1:12; the amount of sodium borohydride used is 1.3 eq of the molar amount of vanillin; vanillin alcohol and guaiacol are mixed in a molar ratio of 1:1.05, and 0.01 times the mass of the comparative example (Example 2) is added. Toluenesulfonic acid was stirred at 110°C for 6 hours, during which water was removed by a water separator. After the reaction solution cooled, a solid precipitated and was purified by recrystallization to obtain bio-based bisphenol. Dimeric acid, sebacic acid, neopentyl glycol, 1,4-butanediol and bio-based bisphenol were first dehydrated at 160°C for 1-2 hours, and then polycondensed at 220°C for 3 hours under the action of tetrabutyl titanate catalyst. The mixture was then vacuum reduced at 240°C to an acid value of 3 mg KOH / g to obtain bisphenol A modified bio-based polyester polyol with a hydroxyl value of 130 mg KOH / g. The mass ratio of the dimer acid, sebacic acid, neopentyl glycol, 1,4-butanediol, and tetrabutyl titanate catalyst is 100:39:36:13:0.06; the bio-based bisphenol accounts for 10-30% of the total diol molar amount; bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, catalyst composition, thermally conductive filler, 1-butyl-3-methylimidazolium hexafluorophosphate, modified fullerene microparticles, and dehydrating agent are mixed evenly to obtain component A; the bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender... The mass ratio of the agent, catalyst composition, thermally conductive filler, 1-butyl-3-methylimidazolium hexafluorophosphate, modified fullerene microparticles, and dehydrating agent is 20:25:7:0.26:120:2.5:0.5:2; the polyether polyol is specifically polyether polyol PPG1000; the chain extender is 1,4-butanediol; the catalyst composition consists of 2,2'-dimorpholine diethyl ether and bismuth neodecanoate in a mass ratio of 0.3:0.11; the dehydrating agent is 3A molecular sieve; the remaining steps are the same as in Example 2.

[0034] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that no thermally conductive filler is added; the remaining steps are the same as in Example 2.

[0035] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that no modified fullerene microparticles are added; the remaining steps are the same as in Example 2.

[0036] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that step (5) is different. Step (5) is changed to: mix component A and component B at a mass ratio of 1:1, degas under vacuum, cure, and place in an environment of 25°C for 5 hours, then heat to 80°C for 4 hours to obtain a thermally resistant bio-based polyurethane thermally conductive adhesive; the remaining steps are the same as in Example 2.

[0037] Example of effect Table 1 below shows the performance analysis results of the thermally resistant bio-based polyurethane thermally conductive adhesives of Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention.

[0038] Table 1

[0039] A comparison of the experimental data from the examples and comparative examples in Table 1 reveals that this invention, through the preparation of bisphenol A-modified bio-based polyester polyols, introduces aromatic secondary hydroxyl groups into the main chain as core sites for dynamic exchange reactions. Combined with the synergistic effect of delayed organic tertiary amine catalysts and organometallic auxiliary catalysts, the main reaction between isocyanate and hydroxyl groups is dominated in the room temperature to medium-low temperature range, ensuring the controllability and operating window of the initial curing process. Simultaneously, a zirconium-based bridging coupling agent is used to modify the surface of the thermally conductive filler, constructing a transition layer with dynamic exchange potential between the filler and the resin matrix through zirconium-oxygen coordination bonds, facilitating the subsequent alcoholysis of urethane bonds at high temperatures. An active interface should be provided, and then a non-volatile ionic liquid should be introduced into the mixed components. The ionic pinning effect of the liquid induces the system to enter a deep supercooled state, enabling the zirconium-based dynamic network to form a solidified structure with both high density and rapid stress relaxation capability. At the same time, the fullerene particles, with their conjugated spherical structure and molecular-level rotational freedom, generate a synergistic dissipation effect through dynamic bond exchange with the zirconium-based bridging layer, effectively suppressing the initiation and propagation of interfacial microcracks. This allows the matrix to achieve a balance between high thermal conductivity and mechanical properties, while endowing the thermally conductive adhesive with excellent resistance to thermal cycling aging, enabling it to maintain interfacial integrity and thermal conductivity stability in a wide temperature range service environment.

[0040] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A thermally resistant, bio-based polyurethane thermally conductive adhesive, characterized in that, The thermally resistant, cycling-resistant bio-based polyurethane thermally conductive adhesive comprises component A and component B; component A contains bisphenol A modified bio-based polyester polyol, catalyst composition, thermally conductive filler, ionic liquid, and modified fullerene microparticles; component B contains polymeric MDI, thermally conductive filler, and p-toluenesulfonyl isocyanate.

2. A method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive, characterized in that, Includes the following steps: (1) Mix bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, catalyst composition, thermally conductive filler, ionic liquid, modified fullerene microparticles and dehydrating agent evenly to obtain component A; (2) Mix polymeric MDI, thermally conductive filler, and p-toluenesulfonyl isocyanate to obtain component B; (3) Mix component A and component B, degas under vacuum, and then cure under deep supercooling to obtain thermally resistant bio-based polyurethane thermally conductive adhesive.

3. The method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive according to claim 2, characterized in that, The preparation method of the bisphenol A modified bio-based polyester polyol in step (1) is as follows: dimer acid, sebacic acid, neopentyl glycol, 1,4-butanediol and bisphenol compounds are first dehydrated at 160℃ for 1-2 hours, and then polycondensed at 220℃ for 3 hours under the action of tetrabutyl titanate catalyst. The acid value is reduced to 3 mg KOH / g under vacuum at 240℃ to obtain bisphenol A modified bio-based polyester polyol with a hydroxyl value of 80-180 mg KOH / g.

4. The method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive according to claim 3, characterized in that, The mass ratio of the dimer acid, sebacic acid, neopentyl glycol, 1,4-butanediol, and tetrabutyl titanate catalyst is 100:25-50:28-45:8-18:0.03-0.

08.

5. The method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive according to claim 3, characterized in that, The bisphenol compounds account for 10-30% of the total molar amount of diols.

6. The method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive according to claim 3, characterized in that, The bisphenol compound is at least one of bisphenol A and bio-based bisphenols.

7. The method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive according to claim 2, characterized in that, The mass ratio of the bisphenol A modified bio-based polyester polyol, polyether polyol, chain extender, catalyst composition, thermally conductive filler, ionic liquid, modified fullerene microparticles, and dehydrating agent in step (1) is 10~30:10~40:4~10:0.03-0.5:80~150:1~4:0.02~1:1~3.

8. The method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive according to claim 2, characterized in that, The catalyst composition in step (1) consists of 2,2'-dimorpholine diethyl ether, an organometallic catalyst, and zirconium acetylacetonate, with a mass ratio of 0.1-0.5:0.03-0.2:0.1-0.

5.

9. The method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive according to claim 2, characterized in that, In step (2), the mass ratio of polymeric MDI, thermally conductive filler, and p-toluenesulfonyl isocyanate is 20:100:

1.

10. The method for preparing a thermally resistant bio-based polyurethane thermally conductive adhesive according to claim 2, characterized in that, The specific steps of the deep supercooling curing treatment in step (3) are as follows: place it in an environment of -20 to -40℃ for curing for 3 to 4 hours, and then raise the temperature to 60 to 80℃ for curing for 4 to 8 hours.

Images